Verifying and Validating Proposed Models for FSW Process Optimization

NASA Technical Reports Server (NTRS)

Schneider, Judith

2008-01-01

This slide presentation reviews Friction Stir Welding (FSW) and the attempts to model the process in order to optimize and improve the process. The studies are ongoing to validate and refine the model of metal flow in the FSW process. There are slides showing the conventional FSW process, a couple of weld tool designs and how the design interacts with the metal flow path. The two basic components of the weld tool are shown, along with geometries of the shoulder design. Modeling of the FSW process is reviewed. Other topics include (1) Microstructure features, (2) Flow Streamlines, (3) Steady-state Nature, and (4) Grain Refinement Mechanisms

Investigation of Friction Stir Welding and Laser Engineered Net Shaping of Metal Matrix Composite Materials

NASA Technical Reports Server (NTRS)

Diwan, Ravinder M.

2002-01-01

The improvement in weld quality by the friction stir welding (FSW) process invented by TWI of Cambridge, England, patented in 1991, has prompted investigation of this process for advanced structural materials including Al metal matrix composite (Al-MMC) materials. Such materials can have high specific stiffness and other potential beneficial properties for the extreme environments in space. Developments of discontinuous reinforced Al-MMCs have found potential space applications and the future for such applications is quite promising. The space industry has recognized advantages of the FSW process over conventional welding processes such as the absence of a melt zone, reduced distortion, elimination of the need for shielding gases, and ease of automation. The process has been well proven for aluminum alloys, and work is being carried out for ferrous materials, magnesium alloys and copper alloys. Development work in the FSW welding process for joining of Al-MMCs is relatively recent and some of this and related work can be found in referenced research publications. NASA engineers have undertaken to spear head this research development work for FSW process investigation of Al-MMCs. Some of the reported related work has pointed out the difficulty in fusion welding of particulate reinforced MMCs where liquid Al will react with SiC to precipitate aluminum carbide (Al4C3). Advantages of no such reaction and no need for joint preparation for the FSW process is anticipated in the welding of Al-MMCs. The FSW process has been best described as a combination of extrusion and forging of metals. This is carried out as the pin tool rotates and is slowly plunged into the bond line of the joint as the pin tool's shoulder is in intimate contact with the work piece. The material is friction-stirred into a quality weld. Al-MMCs, 4 in. x 12 in. plates of 0.25 in. (6.35mm) thickness, procured from MMCC, Inc. were butt welded using FSW process at Marshall Space Flight Center (MSFC) using prior set of operating conditions. Weld quality was evaluated using radiography and standard metallography techniques. Another aspect of the MMCs centered around the use of the laser engineered net shaping (LENS) processing of selected Narloy-Z composites. Such an approach has been earlier studied for fabrication of stainless steels. In the present study, attempts were made to fabricate straight cylindrical specimens using LENS process of Narloy-Z and Narloy-Z with 20 vol. % Al2O3 MMCs using the direct metal deposition Optomec LENS-750 system.

Calibration of 3D ALE finite element model from experiments on friction stir welding of lap joints

NASA Astrophysics Data System (ADS)

Fourment, Lionel; Gastebois, Sabrina; Dubourg, Laurent

2016-10-01

In order to support the design of such a complex process like Friction Stir Welding (FSW) for the aeronautic industry, numerical simulation software requires (1) developing an efficient and accurate Finite Element (F.E.) formulation that allows predicting welding defects, (2) properly modeling the thermo-mechanical complexity of the FSW process and (3) calibrating the F.E. model from accurate measurements from FSW experiments. This work uses a parallel ALE formulation developed in the Forge® F.E. code to model the different possible defects (flashes and worm holes), while pin and shoulder threads are modeled by a new friction law at the tool / material interface. FSW experiments require using a complex tool with scroll on shoulder, which is instrumented for providing sensitive thermal data close to the joint. Calibration of unknown material thermal coefficients, constitutive equations parameters and friction model from measured forces, torques and temperatures is carried out using two F.E. models, Eulerian and ALE, to reach a satisfactory agreement assessed by the proper sensitivity of the simulation to process parameters.

Friction Stir Welding Development

NASA Technical Reports Server (NTRS)

Romine, Peter L.

1998-01-01

The research of this summer was a continuation of work started during the previous summer faculty fellowship period. The Friction Stir Welding process (FSW) patented by The Welding Institute (TWI), in Great Britain, has become a popular topic at the Marshall Space Flight Center over the past year. Last year it was considered a novel approach to welding but few people took it very seriously as a near term solution. However, due to continued problems with cracks in the new aluminum-lithium space shuttle external tank (ET), the friction stir process is being mobilized at full speed in an effort to mature this process for the potential manufacture of flight hardware. It is now the goal of NASA and Lockheed-Martin Corporation (LMC) to demonstrate a full-scale friction stir welding system capable of welding ET size barrel sections. The objectives this summer were: (1) Implementation and validation of the rotating dynamometer on the MSFC FSW system; (2) Collection of data for FSW process modeling efforts; (3) Specification development for FSW implementation on the vertical weld tool; (4) Controls and user interface development for the adjustable pin tool; and (5) Development of an instrumentation system for the planishing process. The projects started this summer will lead to a full scale friction stir welding system that is expected to produce a friction stir welded shuttle external tank type barrel section. The success of this could lead to the implementation of the friction stir process for manufacturing future shuttle external tanks.

Analysing the strength of friction stir welded dissimilar aluminium alloys using Sugeno Fuzzy model

NASA Astrophysics Data System (ADS)

Barath, V. R.; Vaira Vignesh, R.; Padmanaban, R.

2018-02-01

Friction stir welding (FSW) is a promising solid state joining technique for aluminium alloys. In this study, FSW trials were conducted on two dissimilar plates of aluminium alloy AA2024 and AA7075 by varying the tool rotation speed (TRS) and welding speed (WS). Tensile strength (TS) of the joints were measured and a Sugeno - Fuzzy model was developed to interconnect the FSW process parameters with the tensile strength. From the developed model, it was observed that the optimum heat generation at WS of 15 mm.min-1 and TRS of 1050 rpm resulted in dynamic recovery and dynamic recrystallization of the material. This refined the grains in the FSW zone and resulted in peak tensile strength among the tested specimens. Crest parabolic trend was observed in tensile strength with variation of TRS from 900 rpm to 1200 rpm and TTS from 10 mm.min-1 to 20 mm.min-1.

Friction Stir Welding: Standards and Specifications in Today's U.S. Manufacturing and Fabrication

NASA Technical Reports Server (NTRS)

Ding, Robert Jeffrey

2008-01-01

New welding and technology advancements are reflected in the friction stir welding (FSW) specifications used in the manufacturing sector. A lack of publicly available specifications as one of the reasons that the FSW process has not propagate through the manufacturing sectors. FSW specifications are an integral supporting document to the legal agreement written between two entities for deliverable items. Understanding the process and supporting specifications is essential for a successful FSW manufacturing operation. This viewgraph presentation provides an overview of current FSW standards in the industry and discusses elements common to weld specifications.

Improving Flight Software Module Validation Efforts : a Modular, Extendable Testbed Software Framework

NASA Technical Reports Server (NTRS)

Lange, R. Connor

2012-01-01

Ever since Explorer-1, the United States' first Earth satellite, was developed and launched in 1958, JPL has developed many more spacecraft, including landers and orbiters. While these spacecraft vary greatly in their missions, capabilities,and destination, they all have something in common. All of the components of these spacecraft had to be comprehensively tested. While thorough testing is important to mitigate risk, it is also a very expensive and time consuming process. Thankfully,since virtually all of the software testing procedures for SMAP are computer controlled, these procedures can be automated. Most people testing SMAP flight software (FSW) would only need to write tests that exercise specific requirements and then check the filtered results to verify everything occurred as planned. This gives developers the ability to automatically launch tests on the testbed, distill the resulting logs into only the important information, generate validation documentation, and then deliver the documentation to management. With many of the steps in FSW testing automated, developers can use their limited time more effectively and can validate SMAP FSW modules quicker and test them more rigorously. As a result of the various benefits of automating much of the testing process, management is considering this automated tools use in future FSW validation efforts.

Friction Stir Welding of Metal Matrix Composites for use in aerospace structures

NASA Astrophysics Data System (ADS)

Prater, Tracie

2014-01-01

Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramics and have a very high strength to weight ratio, a property which makes them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Since FSW occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This work characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. Based on the results of these experiments, a phenomenological model of the wear process was constructed based on the rotating plug model for FSW. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is explored. In-process force, torque, and vibration signals are analyzed to assess the feasibility of on-line monitoring of tool shape changes as a result of wear (an advancement which would eliminate the need for off-line evaluation of tool condition during joining). Monitoring, controlling, and reducing tool wear in FSW of MMCs is essential to the implementation of these materials in structures (such as launch vehicles) where they would be of maximum benefit.

Solid State Welding Development at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Ding, Robert J.; Walker, Bryant

2012-01-01

What is TSW and USW? TSW is a solid state weld process consisting of an induction coil heating source, a stir rod, and non-rotating containment plates Independent heating, stirring and forging controls Decouples the heating, stirring and forging process elements of FSW. USW is a solid state weld process consisting of an induction coil heating source, a stir rod, and a non-rotating containment plate; Ultrasonic energy integrated into non-rotating containment plate and stir rod; Independent heating, stirring and forging controls; Decouples the heating, stirring and forging process elements of FSW.

Investigation of Microstructure and Microhardness in Self-Reacting Friction Stir Welded AA2014-T6 and AA2219-T87

NASA Technical Reports Server (NTRS)

Horton, K. Renee; McGill, Preston; Barkey, Mark

2011-01-01

Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. This work reports on the microstructure and microhardness of SR-FSW between two dissimilar aluminum alloys. Specifically, the study examines the cross section of the weld joint formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side. The microstructural analysis shows an irregularly displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the weld nugget region. There are sharp variations in the microhardness across the weld. These variations are described in the paper and mechanisms for their formation are discussed.

Flexible Friction Stir Joining Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Zhili; Lim, Yong Chae; Mahoney, Murray

2015-07-23

Reported herein is the final report on a U.S. Department of Energy (DOE) Advanced Manufacturing Office (AMO) project with industry cost-share that was jointly carried out by Oak Ridge National Laboratory (ORNL), ExxonMobil Upstream Research Company (ExxonMobil), and MegaStir Technologies (MegaStir). The project was aimed to advance the state of the art of friction stir welding (FSW) technology, a highly energy-efficient solid-state joining process, for field deployable, on-site fabrications of large, complex and thick-sectioned structures of high-performance and high-temperature materials. The technology innovations developed herein attempted to address two fundamental shortcomings of FSW: 1) the inability for on-site welding andmore » 2) the inability to weld thick section steels, both of which have impeded widespread use of FSW in manufacturing. Through this work, major advance has been made toward transforming FSW technology from a “specialty” process to a mainstream materials joining technology to realize its pervasive energy, environmental, and economic benefits across industry.« less

Microstructural Aspects in FSW and TIG Welding of Cast ZE41A Magnesium Alloy

NASA Astrophysics Data System (ADS)

Carlone, Pierpaolo; Astarita, Antonello; Rubino, Felice; Pasquino, Nicola

2016-04-01

In this paper, magnesium ZE41A alloy plates were butt joined through friction stir welding (FSW) and Tungsten Inert Gas welding processes. Process-induced microstructures were investigated by optical and SEM observations, EDX microanalysis and microhardness measurements. The effect of a post-welded T5 heat treatment on FSW joints was also assessed. Sound joints were produced by means of both techniques. Different elemental distributions and grain sizes were found, whereas microhardness profiles reflect microstructural changes. Post-welding heat treatment did not induce significant alterations in elemental distribution. The FSW-treated joint showed a more homogeneous hardness profile than the as-welded FSW joint.

Investigation of Machine Design for Friction Stir Welding

NASA Technical Reports Server (NTRS)

Romine, Peter L.

1996-01-01

The process of joining two pieces of metal together has not significantly changed over the last few decades. The basic idea used is to bring the pieces together and apply enough heat to melt the metal at the interface. The molten metal mixes and after cooling forms a strong joint. This process is called the fusion process. The most significant difference between the many fusion processes is how the heat is generated and applied. The Welding Institute (TWI), in Great Britain, has recently patented an innovative application of mechanical friction. TWI designed a tool and process called Friction Stir Welding (FSW) that uses friction to heat the metal to within a few hundred degrees Fahrenheit of melting, just to the point of being plastic-like. The tool then stirs the plasticized metal together forming a joint that has been shown to be as good or better than an equivalent fusion joint. The FSW process is well suited for the joining of the aluminum alloys used in the aerospace industry. The relatively low melting point of aluminum eliminates the requirements for exotic materials for pin tool design. The FSW process has been successfully used to join alloys such as 7075 which were before considered "unweldable", and aluminum-lithium 2195 which exhibits many problems when fusion welded. The objective this summer was to investigate the design of a FSW system that could take this process from the laboratory to the manufacturing floor. In particular, it was the goal of my NASA colleague to develop a concept for applying the FSW process to the manufacturing of aluminum cryogenic oxygen and hydrogen tanks, of the sort used to make the Shuttle External Tank.

Cassini Attitude Control Flight Software: from Development to In-Flight Operation

NASA Technical Reports Server (NTRS)

Brown, Jay

2008-01-01

The Cassini Attitude and Articulation Control Subsystem (AACS) Flight Software (FSW) has achieved its intended design goals by successfully guiding and controlling the Cassini-Huygens planetary mission to Saturn and its moons. This paper describes an overview of AACS FSW details from early design, development, implementation, and test to its fruition of operating and maintaining spacecraft control over an eleven year prime mission. Starting from phases of FSW development, topics expand to FSW development methodology, achievements utilizing in-flight autonomy, and summarize lessons learned during flight operations which can be useful to FSW in current and future spacecraft missions.

Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

2012-09-01

Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

Recent Developments for Ultrasonic-Assisted Friction Stir Welding: Joining, Testing, Corrosion - an Overview

NASA Astrophysics Data System (ADS)

Thomä, M.; Wagner, G.; Straß, B.; Conrad, C.; Wolter, B.; Benfer, S.; Fürbeth, W.

2016-03-01

Due to the steadily increasing demand on innovative manufacturing processes, modern lightweight construction concepts become more and more important. Especially joints of dissimilar metals offer a variety of advantages due to their high potential for lightweight construction. The focus of the investigations was Al/Mg-joints. Friction Stir Welding (FSW) is an efficient process to realize high strength joints between these materials in ductile condition. Furthermore, for a simultaneous transmission of power ultrasound during the FSW-process (US-FSW) a positive effect on the achievable tensile strength of the Al/Mg-joints was proven. In the present work the industrial used die cast alloys EN AC-48000 (AlSi12CuNiMg) and AZ80 (MgAl8Zn) were joined by a machining center modified especially for Ultrasound Supported Friction Stir Welding. The appearing welding zone and the formation of intermetallic phases under the influence of power ultrasound were examined in particular. In order to identify optimal process parameters extensive preliminary process analyzes have been carried out. Following this, an ultrasound-induced more intensive stirring of the joining zone and as a result of this a considerably modified intermetallic zone was detected. At the same time an increase of the tensile strength of about 25% for US-FSW-joints and for fatigue an up to three times higher number of cycles to failure in comparison to a conventional welding process was observed. Moreover, detailed corrosion analyzes have shown that especially the welding zone was influenced by the corrosive attack. To expand and deepen the knowledge of the US-FSW-process further material combinations such as Ti/Steel and Al/Steel will be considered in future.

Supporting Development of Satellite's Guidance Navigation and Control Software: A Product Line Approach

NASA Technical Reports Server (NTRS)

McComas, David; Stark, Michael; Leake, Stephen; White, Michael; Morisio, Maurizio; Travassos, Guilherme H.; Powers, Edward I. (Technical Monitor)

2000-01-01

The NASA Goddard Space Flight Center Flight Software Branch (FSB) is developing a Guidance, Navigation, and Control (GNC) Flight Software (FSW) product line. The demand for increasingly more complex flight software in less time while maintaining the same level of quality has motivated us to look for better FSW development strategies. The GNC FSW product line has been planned to address the core GNC FSW functionality very similar on many recent low/near Earth missions in the last ten years. Unfortunately these missions have not accomplished significant drops in development cost since a systematic approach towards reuse has not been adopted. In addition, new demands are continually being placed upon the FSW which means the FSB must become more adept at providing GNC FSW functionality's core so it can accommodate additional requirements. These domain features together with engineering concepts are influencing the specification, description and evaluation of FSW product line. Domain engineering is the foundation for emerging product line software development approaches. A product line is 'A family of products designed to take advantage of their common aspects and predicted variabilities'. In our product line approach, domain engineering includes the engineering activities needed to produce reusable artifacts for a domain. Application engineering refers to developing an application in the domain starting from reusable artifacts. The focus of this paper is regarding the software process, lessons learned and on how the GNC FSW product line manages variability. Existing domain engineering approaches do not enforce any specific notation for domain analysis or commonality and variability analysis. Usually, natural language text is the preferred tool. The advantage is the flexibility and adapt ability of natural language. However, one has to be ready to accept also its well-known drawbacks, such as ambiguity, inconsistency, and contradictions. While most domain analysis approaches are functionally oriented, the idea of applying the object-oriented approach in domain analysis is not new. Some authors propose to use UML as the notation underlying domain analysis. Our work is based on the same idea of merging UML and domain analysis. Further, we propose a few extensions to UML in order to express variability, and we define precisely their semantics so that a tool can support them. The extensions are designed to be implemented on the API of a popular industrial CASE tool, with obvious advantages in cost and availability of tool support. The paper outlines the product line processes and identifies where variability must be addressed. Then it describes the product line products with respect to how they accommodate variability. The Celestial Body subdomain is used as a working example. Our results to date are summarized and plans for the future are described.

Framework Based Guidance Navigation and Control Flight Software Development

NASA Technical Reports Server (NTRS)

McComas, David

2007-01-01

This viewgraph presentation describes NASA's guidance navigation and control flight software development background. The contents include: 1) NASA/Goddard Guidance Navigation and Control (GN&C) Flight Software (FSW) Development Background; 2) GN&C FSW Development Improvement Concepts; and 3) GN&C FSW Application Framework.

The microstructure of aluminum A5083 butt joint by friction stir welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasri, M. A. H. M.; Afendi, M.; Ismail, A.

This study presents the microstructure of the aluminum A5083 butt joint surface after it has been joined by friction stir welding (FSW) process. The FSW process is a unique welding method because it will not change the chemical properties of the welded metals. In this study, MILKO 37 milling machine was modified to run FSW process on 4 mm plate of aluminum A5083 butt joint. For the experiment, variables of travel speed and tool rotational speed based on capability of machine were used to run FSW process. The concentrated heat from the tool to the aluminum plate changes the platemore » form from solid to plastic state. Two aluminum plates is merged to become one plate during plastic state and return to solid when concentrated heat is gradually further away. After that, the surface and cross section of the welded aluminum were investigated with a microscope by 400 x multiplication zoom. The welding defect in the FSW aluminum was identified. Then, the result was compared to the American Welding Society (AWS) FSW standard to decide whether the plate can be accepted or rejected.« less

Prolegomena to the Study of Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.

2010-01-01

The literature contains many approaches toward modeling of the friction stir welding (FSW) process with varying treatments of the weld metal properties. It is worthwhile to consider certain fundamental features of the process before attempting to interpret FSW phenomena: Because of the unique character of metal deformation (as opposed to, say, viscous deformation) a velocity "discontinuity" or shear surface occurs in FSW and determines much of the character of the welding mechanism. A shear surface may not always produce a sound bond. Balancing mechanical power input against conduction and convection heat losses yields a relation, a "temperature index", between spindle speed and travel speed to maintain constant weld temperature. But many process features are only weakly dependent upon temperature. Thus, unlike modeling of metal forming processes, it may be that modeling the FSW process independently of the material conditions has some merit.

Thermomechanical conditions and stresses on the friction stir welding tool

NASA Astrophysics Data System (ADS)

Atthipalli, Gowtam

Friction stir welding has been commercially used as a joining process for aluminum and other soft materials. However, the use of this process in joining of hard alloys is still developing primarily because of the lack of cost effective, long lasting tools. Here I have developed numerical models to understand the thermo mechanical conditions experienced by the FSW tool and to improve its reusability. A heat transfer and visco-plastic flow model is used to calculate the torque, and traverse force on the tool during FSW. The computed values of torque and traverse force are validated using the experimental results for FSW of AA7075, AA2524, AA6061 and Ti-6Al-4V alloys. The computed torque components are used to determine the optimum tool shoulder diameter based on the maximum use of torque and maximum grip of the tool on the plasticized workpiece material. The estimation of the optimum tool shoulder diameter for FSW of AA6061 and AA7075 was verified with experimental results. The computed values of traverse force and torque are used to calculate the maximum shear stress on the tool pin to determine the load bearing ability of the tool pin. The load bearing ability calculations are used to explain the failure of H13 steel tool during welding of AA7075 and commercially pure tungsten during welding of L80 steel. Artificial neural network (ANN) models are developed to predict the important FSW output parameters as function of selected input parameters. These ANN consider tool shoulder radius, pin radius, pin length, welding velocity, tool rotational speed and axial pressure as input parameters. The total torque, sliding torque, sticking torque, peak temperature, traverse force, maximum shear stress and bending stress are considered as the output for ANN models. These output parameters are selected since they define the thermomechanical conditions around the tool during FSW. The developed ANN models are used to understand the effect of various input parameters on the total torque and traverse force during FSW of AA7075 and 1018 mild steel. The ANN models are also used to determine tool safety factor for wide range of input parameters. A numerical model is developed to calculate the strain and strain rates along the streamlines during FSW. The strain and strain rate values are calculated for FSW of AA2524. Three simplified models are also developed for quick estimation of output parameters such as material velocity field, torque and peak temperature. The material velocity fields are computed by adopting an analytical method of calculating velocities for flow of non-compressible fluid between two discs where one is rotating and other is stationary. The peak temperature is estimated based on a non-dimensional correlation with dimensionless heat input. The dimensionless heat input is computed using known welding parameters and material properties. The torque is computed using an analytical function based on shear strength of the workpiece material. These simplified models are shown to be able to predict these output parameters successfully.

Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm

PubMed Central

Tamjidy, Mehran; Baharudin, B. T. Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

2017-01-01

The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon’s entropy. PMID:28772893

Multi-Objective Optimization of Friction Stir Welding Process Parameters of AA6061-T6 and AA7075-T6 Using a Biogeography Based Optimization Algorithm.

PubMed

Tamjidy, Mehran; Baharudin, B T Hang Tuah; Paslar, Shahla; Matori, Khamirul Amin; Sulaiman, Shamsuddin; Fadaeifard, Firouz

2017-05-15

The development of Friction Stir Welding (FSW) has provided an alternative approach for producing high-quality welds, in a fast and reliable manner. This study focuses on the mechanical properties of the dissimilar friction stir welding of AA6061-T6 and AA7075-T6 aluminum alloys. The FSW process parameters such as tool rotational speed, tool traverse speed, tilt angle, and tool offset influence the mechanical properties of the friction stir welded joints significantly. A mathematical regression model is developed to determine the empirical relationship between the FSW process parameters and mechanical properties, and the results are validated. In order to obtain the optimal values of process parameters that simultaneously optimize the ultimate tensile strength, elongation, and minimum hardness in the heat affected zone (HAZ), a metaheuristic, multi objective algorithm based on biogeography based optimization is proposed. The Pareto optimal frontiers for triple and dual objective functions are obtained and the best optimal solution is selected through using two different decision making techniques, technique for order of preference by similarity to ideal solution (TOPSIS) and Shannon's entropy.

Microstructure and Mechanical Property Change During FSW and GTAW of Al6061 Alloy

NASA Astrophysics Data System (ADS)

Fahimpour, V.; Sadrnezhaad, S. K.; Karimzadeh, F.

2013-05-01

The variation of morphology and mechanical properties of Al6061 automotive aluminum alloy due to friction stir welding (FSW) and gas tungsten arc welding (GTAW) was investigated by optical metallography, scanning electron microscopy, microhardness measurement, X-ray diffraction, tensile testing, and fractography. The center-line dendrite emergence and microhardness reduction in the heat-affected zone were observed in the GTAW process. Although similar microhardness reduction with respect to the base metal was observed in the FSW samples, higher HVs were obtained for the FSW rather than the GTAW process at almost all heat-affected locations. Ultimate tensile strengths of the FSW and the GTAW samples in the transverse direction were ~0.57 and ~0.35 of the base metal, respectively. Post-weld aging improved the strength, but reduced the ductility of the welding.

Wear-Induced Changes in FSW Tool Pin Profile: Effect of Process Parameters

NASA Astrophysics Data System (ADS)

Sahlot, Pankaj; Jha, Kaushal; Dey, G. K.; Arora, Amit

2018-06-01

Friction stir welding (FSW) of high melting point metallic (HMPM) materials has limited application due to tool wear and relatively short tool life. Tool wear changes the profile of the tool pin and adversely affects weld properties. A quantitative understanding of tool wear and tool pin profile is crucial to develop the process for joining of HMPM materials. Here we present a quantitative wear study of H13 steel tool pin profile for FSW of CuCrZr alloy. The tool pin profile is analyzed at multiple traverse distances for welding with various tool rotational and traverse speeds. The results indicate that measured wear depth is small near the pin root and significantly increases towards the tip. Near the pin tip, wear depth increases with increase in tool rotational speed. However, change in wear depth near the pin root is minimal. Wear depth also increases with decrease in tool traverse speeds. Tool pin wear from the bottom results in pin length reduction, which is greater for higher tool rotational speeds, and longer traverse distances. The pin profile changes due to wear and result in root defect for long traverse distance. This quantitative understanding of tool wear would be helpful to estimate tool wear, optimize process parameters, and tool pin shape during FSW of HMPM materials.

Investigation of Friction Stir Welding of Al Metal Matrix Composite Materials

NASA Technical Reports Server (NTRS)

Diwan, Ravinder M.

2003-01-01

The innovative process of Friction Stir Welding (FSW) has generated tremendous interest since its inception about a decade or so ago since the first patent in 1991 by TWI of Cambridge, England. This interest has been seen in many recent international conferences and publications on the subject and relevant published literature. Still the process needs both intensive basic study of deformation mechanisms during this FSW process and analysis and feasibility study to evaluate production methods that will yield high quality strong welds from the stirring action of the appropriate pin tool into the weld plate materials. Development of production processes is a complex task that involves effects of material thickness, materials weldability, pin tool design, pin height, and pin shoulder diameter and related control conditions. The frictional heating with rotational speeds of the pin tool as it plunges into the material and the ensuing plastic flow arising during the traverse of the welding faying surfaces provide the known special advantages of the FSW process in the area of this new advanced joining technology.

Emission of nanoparticles during friction stir welding (FSW) of aluminium alloys.

PubMed

Gomes, J F; Miranda, R M; Santos, T J; Carvalho, P A

2014-01-01

Friction stir welding (FSW) is now well established as a welding process capable of joining some different types of metallic materials, as it was (1) found to be a reliable and economical way of producing high quality welds, and (2) considered a "clean" welding process that does not involve fusion of metal, as is the case with other traditional welding processes. The aim of this study was to determine whether the emission of particles during FSW in the nanorange of the most commonly used aluminum (Al) alloys, AA 5083 and AA 6082, originated from the Al alloy itself due to friction of the welding tool against the item that was being welded. Another goal was to measure Al alloys in the alveolar deposited surface area during FSW. Nanoparticles dimensions were predominantly in the 40- and 70-nm range. This study demonstrated that microparticles were also emitted during FSW but due to tool wear. However, the biological relevance and toxic manifestations of these microparticles remain to be determined.

[New welding processes and health effects of welding].

PubMed

La Vecchia, G Marina; Maestrelli, Piero

2011-01-01

This paper describes some of the recent developments in the control technology to enhance capability of Pulse Gas Metal Arc Welding. Friction Stir Welding (FSW) processing has been also considered. FSW is a new solid-state joining technique. Heat generated by friction at the rotating tool softens the material being welded. FSW can be considered a green and energy-efficient technique without deleterious fumes, gas, radiation, and noise. Application of new welding processes is limited and studies on health effects in exposed workers are lacking. Acute and chronic health effects of conventional welding have been described. Metal fume fever and cross-shift decline of lung function are the main acute respiratory effects. Skin and eyes may be affected by heat, electricity and UV radiations. Chronic effects on respiratory system include chronic bronchitis, a benign pneumoconiosis (siderosis), asthma, and a possible increase in the incidence of lung cancer. Pulmonary infections are increased in terms of severity, duration, and frequency among welders.

Experimental Investigation on Friction Stir Welding of Cryorolled AA2219 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Babu, K. Kamal; Panneerselvam, K.; Sathiya, P.; Haq, A. Noorul; Sundarrajan, S.; Mastanaiah, P.; Murthy, C. V. Srinivasa

2017-07-01

In this paper, experimental investigation on cryorolled aluminum AA2219-T87 plate by using friction stir welding (FSW) process is carried out. AA2219-T87 plates with a size of 200×100×22.4 mm were rolled and reduced to 12.2mm thickness (more than 45% of reduction in total thickness of the base material) at cryogenic temperature (operating temperature range -90--30∘C). The cryorolled (CR) plates have reduced grain size, improved hardness and increased corrosion resistance property compared with the uncryorolled AA2219-T87 plates. FSW joints of cryorolled AA2219-T87 plates were prepared using cylindrical threaded FSW tool pin profile. Mechanical and metallurgical behaviors of friction stir welded joints were analyzed and the effects of the FSW process parameters are discussed in this paper. The variation of microhardness in the FSW joint regions were correlated with the microstructure of FSW joints. Cryorolled plate and FSW joints were tested for corrosion resistance using potentiodynamic polarization test. FSW joints shows better result during the corrosion resistance analysis compared to base AA2219-T87. The X-ray diffraction (XRD) test results showed that fine α-Al grains with eutectic phase (Al2Cu) were present in the weld nugget (WN). The large clusters of strengthening precipitates were reduced in size and merged with the weld nugget portion.

TEM study of the FSW nugget in AA2195-T81

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.; Chen, P. S.; Steele, G.

2004-01-01

During fiiction stir welding (FSW) the material being joined is subjected to a thermal- mechanical process in which the temperature, strain and strain rates are not completely understood. To produce a defect fiee weld, process parameters for the weld and tool pin design must be chosen carefully. The ability to select the weld parameters based on the thermal processing requirements of the material, would allow optimization of mechanical properties in the weld region. In this study, an attempt is made to correlate the microstructure with the variation in thermal history the material experiences during the FSW process.

NASA Design Strengthens Welds

NASA Technical Reports Server (NTRS)

2008-01-01

Friction Stir Welding (FSW) is a solid-state joining process-a combination of extruding and forging-ideal for use when the original metal characteristics must remain as unchanged as possible. While exploring methods to improve the use of FSW in manufacturing, engineers at Marshall Space Flight Center created technologies to address the method's shortcomings. MTS Systems Corporation, of Eden Prairie, Minnesota, discovered the NASA-developed technology and then signed a co-exclusive license agreement to commercialize Marshall's design for use in high-strength structural alloys. The resulting process offers the added bonuses of being cost-competitive, efficient, and most importantly, versatile.

A Study on Tooling and Its Effect on Heat Generation and Mechanical Properties of Welded Joints in Friction Stir Welding

NASA Astrophysics Data System (ADS)

Tikader, Sujoy; Biswas, Pankaj; Puri, Asit Baran

2018-04-01

Friction stir welding (FSW) has been the most attracting solid state welding process as it serves numerous advantages like good mechanical, metallurgical properties etc. Non weldable aluminium alloys like 5XXX, 7XXX series can be simply joined by this process. In this present study a mathematical model has been developed and experiments were successfully performed to evaluate mechanical properties of FSW on similar aluminium alloys i.e. AA1100 for different process parameters and mainly two kind of tool geometry (straight cylindrical and conical or cylindrical tapered shaped pin with flat shoulder). Tensile strength and micro hardness for different process parameters are reported of the welded plate sample. It was noticed that in FSW of similar alloy with tool made of SS-310 tool steel, friction is the major contributor for the heat generation. It was seen that tool geometry, tool rotational speed, plunging force by the tool and traverse speed have significant effect on tensile strength and hardness of friction stir welded joints.

Effect of process parameters on microstructure and electrical conductivity during FSW of Al-6101 and Pure Copper

NASA Astrophysics Data System (ADS)

Sharma, Nidhi; Khan, Zahid A.; Siddiquee, Arshad Noor; Shihab, Suha K.; Atif Wahid, Mohd

2018-04-01

Copper (Cu) is predominantly used material as a conducting element in electrical and electronic components due to its high conductivity. Aluminum (Al) being lighter in weight and more conductive on weight basis than that of Cu is able to replace or partially replace Cu to make lighter and cost effective electrical components. Conventional methods of joining Al to Cu, such as, fusion welding process have many shortcomings. Friction Stir Welding (FSW) is a solid state welding process which overcomes the shortcoming of the fusion welding. FSW parameters affect the mechanical and electrical properties of the joint. This study aims to evaluate the effect of different process parameters such as shoulder diameter, pin offset, welding and rotational speed on the microstructure and electrical conductivity of the dissimilar Al-Cu joint. FSW is performed using cylindrical pin profile, and four process parameters. Each parameter at different levels is varied according to Taguchi’s L18 standard orthogonal array. It is found that the electrical conductivity of the FSWed joints are equal to that of aluminum at all the welded sections. FSW is found to be an effective technique to join Al to Cu without compromising with the electrical properties. However, the electrical conductivity gets influenced by the process parameters in the stir zone. The optimal combination of the FSW parameters for maximum electrical conductivity is determined. The analysis of variance (ANOVA) technique applied on stir zone suggests that the rotational speed and tool pin offset are the significant parameters to influence the electrical conductivity.

Study on nondestructive inspection using HTS-SQUID for friction stir welding between dissimilar metals

NASA Astrophysics Data System (ADS)

Hatsukade, Y.; Takahashi, T.; Yasui, T.; Tsubaki, M.; Fukumono, M.; Tanaka, S.

2007-10-01

We have developed an SQUID-NDI technique for evaluation of friction stir welding (FSW) between aluminum alloy A6063 and stainless steel SUS304 from the electric conductivities in board specimens bonded by FSW. A SQUID-NDI system employing an HTS-SQUID gradiometer was constructed to measure current distribution in the FSW specimens by applying voltage to the specimen. By measuring field gradients dBz/dy and dBz/dx above the FSW specimens made with various FSW conditions and then converting them to current vector Jx and Jy, conductivities of FSW areas were estimated. Due to the difference in the FSW conditions, the conductivity distributions varied dramatically. From these results, it was suggested that the conductivities in FSW areas should be varied due to the temperature heated by the friction between the milling tool and the materials.

Friction Stir Welding of SiC/Aluminum Metal Matrix Composites

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.

1999-01-01

Friction Stir Welding (FSW) is a new solid state process for joining metals by plasticizing and consolidating materials around the bond line using thermal energy producing from frictional forces. A feasibility study for FSW of Metal Matrix Composites (MMC) was investigated using aluminum 6092 alloy reinforced with 17% SiC particulates. FSW process consists of a special rotating pin tool that is positioned to plunge into the MMC surface at the bond line. As the tool rotates and move forward along the bond line, the material at the bond line is heated up and forced to flow around the rotating tip to consolidate on the tip's backside to form a solid state joint. FSW has the potential for producing sound welds with MMC because the processing temperature occurs well below the melting point of the metal matrix; thereby eliminating the reinforcement-to-matrix solidification defects, reducing the undesirable chemical reactions and porosity problems.

Experimental investigations of tungsten inert gas assisted friction stir welding of pure copper plates

NASA Astrophysics Data System (ADS)

Constantin, M. A.; Boșneag, A.; Nitu, E.; Iordache, M.

2017-10-01

Welding copper and its alloys is usually difficult to join by conventional fusion welding processes because of high thermal diffusivity of the copper, alloying elements, necessity of using a shielding gas and a clean surface. To overcome this inconvenience, Friction Stir Welding (FSW), a solid state joining process that relies on frictional heating and plastic deformation, is used as a feasible welding process. In order to achieve an increased welding speed and a reduction in tool wear, this process is assisted by another one (WIG) which generates and adds heat to the process. The aim of this paper is to identify the influence of the additional heat on the process parameters and on the welding joint properties (distribution of the temperature, hardness and roughness). The research includes two experiments for the FSW process and one experiment for tungsten inert gas assisted FSW process. The outcomes of the investigation are compared and analysed for both welding variants. Adding a supplementary heat source, the plates are preheated and are obtain some advantages such as reduced forces used in process and FSW tool wear, faster and better plasticization of the material, increased welding speed and a proper weld quality.

Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network.

PubMed

De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Facchini, Francesco; Mummolo, Giovanni; Ludovico, Antonio Domenico

2016-11-10

A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration.

Friction Stir Welding (FSW) of Aged CuCrZr Alloy Plates

NASA Astrophysics Data System (ADS)

Jha, Kaushal; Kumar, Santosh; Nachiket, K.; Bhanumurthy, K.; Dey, G. K.

2018-01-01

Friction Stir Welding (FSW) of Cu-0.80Cr-0.10Zr (in wt pct) alloy under aged condition was performed to study the effects of process parameters on microstructure and properties of the joint. FSW was performed over a wide range of process parameters, like tool-rotation speed (from 800 to 1200 rpm) and tool-travel speed (from 40 to 100 mm/min), and the resulting thermal cycles were recorded on both sides (advancing and retreating) of the joint. The joints were characterized for their microstructure and tensile properties. The welding process resulted in a sound and defect-free weld joint, over the entire range of the process parameters used in this study. Microstructure of the stir zone showed fine and equiaxed grains, the scale of which varied with FSW process parameters. Grain size in the stir zone showed direct correlation with tool rotation and inverse correlation with tool-travel speed. Tensile strength of the weld joints was ranging from 225 to 260 MPa, which is substantially lower than that of the parent metal under aged condition ( 400 MPa), but superior to that of the parent material under annealed condition ( 220 MPa). Lower strength of the FSW joint than that of the parent material under aged condition can be attributed to dissolution of the precipitates in the stir zone and TMAZ. These results are presented and discussed in this paper.

An Introduction to Flight Software Development: FSW Today, FSW 2010

NASA Technical Reports Server (NTRS)

Gouvela, John

2004-01-01

Experience and knowledge gained from ongoing maintenance of Space Shuttle Flight Software and new development projects including Cockpit Avionics Upgrade are applied to projected needs of the National Space Exploration Vision through Spiral 2. Lessons learned from these current activities are applied to create a sustainable, reliable model for development of critical software to support Project Constellation. This presentation introduces the technologies, methodologies, and infrastructure needed to produce and sustain high quality software. It will propose what is needed to support a Vision for Space Exploration that places demands on the innovation and productivity needed to support future space exploration. The technologies in use today within FSW development include tools that provide requirements tracking, integrated change management, modeling and simulation software. Specific challenges that have been met include the introduction and integration of Commercial Off the Shelf (COTS) Real Time Operating System for critical functions. Though technology prediction has proved to be imprecise, Project Constellation requirements will need continued integration of new technology with evolving methodologies and changing project infrastructure. Targets for continued technology investment are integrated health monitoring and management, self healing software, standard payload interfaces, autonomous operation, and improvements in training. Emulation of the target hardware will also allow significant streamlining of development and testing. The methodologies in use today for FSW development are object oriented UML design, iterative development using independent components, as well as rapid prototyping . In addition, Lean Six Sigma and CMMI play a critical role in the quality and efficiency of the workforce processes. Over the next six years, we expect these methodologies to merge with other improvements into a consolidated office culture with all processes being guided by automated office assistants. The infrastructure in use today includes strict software development and configuration management procedures, including strong control of resource management and critical skills coverage. This will evolve to a fully integrated staff organization with efficient and effective communication throughout all levels guided by a Mission-Systems Architecture framework with focus on risk management and attention toward inevitable product obsolescence. This infrastructure of computing equipment, software and processes will itself be subject to technological change and need for management of change and improvement,

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

PubMed Central

Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

2013-01-01

Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force. PMID:28788430

Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

PubMed

Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

2013-12-18

Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

Innovative Tools Advance Revolutionary Weld Technique

NASA Technical Reports Server (NTRS)

2009-01-01

The iconic, orange external tank of the space shuttle launch system not only contains the fuel used by the shuttle s main engines during liftoff but also comprises the shuttle s backbone, supporting the space shuttle orbiter and solid rocket boosters. Given the tank s structural importance and the extreme forces (7.8 million pounds of thrust load) and temperatures it encounters during launch, the welds used to construct the tank must be highly reliable. Variable polarity plasma arc welding, developed for manufacturing the external tank and later employed for building the International Space Station, was until 1994 the best process for joining the aluminum alloys used during construction. That year, Marshall Space Flight Center engineers began experimenting with a relatively new welding technique called friction stir welding (FSW), developed in 1991 by The Welding Institute, of Cambridge, England. FSW differs from traditional fusion welding in that it is a solid-state welding technique, using frictional heat and motion to join structural components without actually melting any of the material. The weld is created by a shouldered pin tool that is plunged into the seam of the materials to be joined. The tool traverses the line while rotating at high speeds, generating friction that heats and softens but does not melt the metal. (The heat produced approaches about 80 percent of the metal s melting temperature.) The pin tool s rotation crushes and stirs the plasticized metal, extruding it along the seam as the tool moves forward. The material cools and consolidates, resulting in a weld with superior mechanical properties as compared to those weld properties of fusion welds. The innovative FSW technology promises a number of attractive benefits. Because the welded materials are not melted, many of the undesirables associated with fusion welding porosity, cracking, shrinkage, and distortion of the weld are minimized or avoided. The process is more energy efficient, safe (no toxic smoke or shielding gas, liquid metal splatter, arcing, dangerous voltage, or radiation), and environmentally sound (no consumables, fumes, or noise) than fusion welding. Under computer control, an automated FSW machine can create welds with high reproducibility, improving efficiency and overall quality of manufactured materials. The process also allows for welding dissimilar metals as well as those metals considered to be "unweldable" such as the 7xxx series aluminum alloys. Its effectiveness and versatility makes FSW useful for aerospace, rail, automotive, marine, and military applications. A downside to FSW, however, is the keyhole opening left in the weld when the FSW pin tool exits the weld joint. This is a significant problem when using the FSW process to join circumferential structures such as pipes and storage containers. Furthermore, weld joints that taper in material thickness also present problems when using the conventional FSW pin tool, because the threaded pin rotating within the weld joint material is a fixed length. There must be capability for the rotating pin to both increase and decrease in length in real time while welding the tapered material. (Both circumferential and tapered thickness weldments are found in the space shuttle external tank.) Marshall engineers addressed both the keyhole and tapered material thickness problems by developing the auto-adjustable pin tool. This unique piece of equipment automatically withdraws the pin into the tool s shoulder for keyhole closeout. In addition, the auto-adjustable pin tool retracts, or shortens, the rotating pin while welding a weld joint that tapers from one thickness to a thinner thickness. This year, the impact of the Marshall innovation was recognized with an "Excellence in Technology Transfer Award" from the Federal Laboratory Consortium.

Metal Flow in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.

2006-01-01

The plastic deformation field in Friction Stir Welding (FSW) is compared to that in metal cutting. A shear surface around the FSW tool analogous to the metal cutting shear plane is identified and comprises the basis of the "rotating plug" flow field model and the "wiping" model of tool interaction with weld metal. Within the context of these models: The FSW shear rate is estimated to be comparable to metal cutting shear rates. The effect of tool geometry on the FSW shear surface is discussed and related to published torque measurements. Various FS W structural features are explained, including a difference in structure of bimetallic welds when alloys on the advancing and retreating sides of the weld seam are exchanged. The joining mechanism and critical parameters of the FSW process are made clear.

Tool for Two Types of Friction Stir Welding

NASA Technical Reports Server (NTRS)

Carter, Robert

2006-01-01

A tool that would be useable in both conventional and self-reacting friction stir welding (FSW) has been proposed. The tool would embody both a prior tooling concept for self-reacting FSW and an auto-adjustable pin-tool (APT) capability developed previously as an augmentation for conventional FSW. Some definitions of terms are prerequisite to a meaningful description of the proposed tool. In conventional FSW, depicted in Figure 1, one uses a tool that includes (1) a rotating shoulder on top (or front) of the workpiece and (2) a rotating pin that protrudes from the shoulder into the depth of the workpiece. The main axial force exerted by the tool on the workpiece is reacted through a ridged backing anvil under (behind) the workpiece. When conventional FSW is augmented with an APT capability, the depth of penetration of the pin into the workpiece is varied in real time by a position- or force-control system that extends or retracts the pin as needed to obtain the desired effect. In self-reacting (also known as self-reacted) friction stir welding (SR-FSW), there are two rotating shoulders: one on top (or front) and one on the bottom (or back) of the workpiece. In this case, a threaded shaft protrudes from the tip of the pin to beyond the back surface of the workpiece. The back shoulder is held axially in place against tension by a nut on the threaded shaft. The main axial force exerted on the workpiece by the tool and front shoulder is reacted through the back shoulder and the threaded shaft, back into the FSW machine head, so that a backing anvil is no longer needed. A key transmits torque between the bottom shoulder and the threaded shaft, so that the bottom shoulder rotates with the shaft. A tool for SRFSW embodying this concept was reported in "Mechanism for Self-Reacted Friction Stir Welding" (MFS-31914), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 53. In its outward appearance, the proposed tool (see Figure 2) would fit the above description of an SR-FSW tool. In this case, the FSW machine would have an APT capability and the pin would be modified to accept a bottom shoulder. The APT capability could be used to vary the distance between the front and back shoulders in real time to accommodate process and workpiece-thickness variations. The tool could readily be converted to a conventional FSW tool, with or without APT capability, by simply replacing the modified pin with a conventional FSW pin.

Development of a Robust and Cost-Effective Friction Stir Welding Process for Use in Advanced Military Vehicles

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Pandurangan, B.; Hariharan, A.; Yen, C.-F.; Cheeseman, B. A.

2011-02-01

To respond to the advent of more lethal threats, recently designed aluminum-armor-based military-vehicle systems have resorted to an increasing use of higher strength aluminum alloys (with superior ballistic resistance against armor piercing (AP) threats and with high vehicle-light weighing potential). Unfortunately, these alloys are not very amenable to conventional fusion-based welding technologies and in-order to obtain high-quality welds, solid-state joining technologies such as Friction stir welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced military vehicle structures is not straight forward and entails a comprehensive multi-step approach. One such (three-step) approach is developed in the present work. Within the first step, experimental and computational techniques are utilized to determine the optimal tool design and the optimal FSW process parameters which result in maximal productivity of the joining process and the highest quality of the weld. Within the second step, techniques are developed for the identification and qualification of the optimal weld joint designs in different sections of a prototypical military vehicle structure. In the third step, problems associated with the fabrication of a sub-scale military vehicle test structure and the blast survivability of the structure are assessed. The results obtained and the lessons learned are used to judge the potential of the current approach in shortening the development time and in enhancing reliability and blast survivability of military vehicle structures.

Community empowerment and involvement of female sex workers in targeted sexual and reproductive health interventions in Africa: a systematic review.

PubMed

Moore, Lizzie; Chersich, Matthew F; Steen, Richard; Reza-Paul, Sushena; Dhana, Ashar; Vuylsteke, Bea; Lafort, Yves; Scorgie, Fiona

2014-06-10

Female sex workers (FSWs) experience high levels of sexual and reproductive health (SRH) morbidity, violence and discrimination. Successful SRH interventions for FSWs in India and elsewhere have long prioritised community mobilisation and structural interventions, yet little is known about similar approaches in African settings. We systematically reviewed community empowerment processes within FSW SRH projects in Africa, and assessed them using a framework developed by Ashodaya, an Indian sex worker organisation. In November 2012 we searched Medline and Web of Science for studies of FSW health services in Africa, and consulted experts and websites of international organisations. Titles and abstracts were screened to identify studies describing relevant services, using a broad definition of empowerment. Data were extracted on service-delivery models and degree of FSW involvement, and analysed with reference to a four-stage framework developed by Ashodaya. This conceptualises community empowerment as progressing from (1) initial engagement with the sex worker community, to (2) community involvement in targeted activities, to (3) ownership, and finally, (4) sustainability of action beyond the community. Of 5413 articles screened, 129 were included, describing 42 projects. Targeted services in FSW 'hotspots' were generally isolated and limited in coverage and scope, mostly offering only free condoms and STI treatment. Many services were provided as part of research activities and offered via a clinic with associated community outreach. Empowerment processes were usually limited to peer-education (stage 2 of framework). Community mobilisation as an activity in its own right was rarely documented and while most projects successfully engaged communities, few progressed to involvement, community ownership or sustainability. Only a few interventions had evolved to facilitate collective action through formal democratic structures (stage 3). These reported improved sexual negotiating power and community solidarity, and positive behavioural and clinical outcomes. Sustainability of many projects was weakened by disunity within transient communities, variable commitment of programmers, low human resource capacity and general resource limitations. Most FSW SRH projects in Africa implemented participatory processes consistent with only the earliest stages of community empowerment, although isolated projects demonstrate proof of concept for successful empowerment interventions in African settings.

Community empowerment and involvement of female sex workers in targeted sexual and reproductive health interventions in Africa: a systematic review

PubMed Central

2014-01-01

Background Female sex workers (FSWs) experience high levels of sexual and reproductive health (SRH) morbidity, violence and discrimination. Successful SRH interventions for FSWs in India and elsewhere have long prioritised community mobilisation and structural interventions, yet little is known about similar approaches in African settings. We systematically reviewed community empowerment processes within FSW SRH projects in Africa, and assessed them using a framework developed by Ashodaya, an Indian sex worker organisation. Methods In November 2012 we searched Medline and Web of Science for studies of FSW health services in Africa, and consulted experts and websites of international organisations. Titles and abstracts were screened to identify studies describing relevant services, using a broad definition of empowerment. Data were extracted on service-delivery models and degree of FSW involvement, and analysed with reference to a four-stage framework developed by Ashodaya. This conceptualises community empowerment as progressing from (1) initial engagement with the sex worker community, to (2) community involvement in targeted activities, to (3) ownership, and finally, (4) sustainability of action beyond the community. Results Of 5413 articles screened, 129 were included, describing 42 projects. Targeted services in FSW ‘hotspots’ were generally isolated and limited in coverage and scope, mostly offering only free condoms and STI treatment. Many services were provided as part of research activities and offered via a clinic with associated community outreach. Empowerment processes were usually limited to peer-education (stage 2 of framework). Community mobilisation as an activity in its own right was rarely documented and while most projects successfully engaged communities, few progressed to involvement, community ownership or sustainability. Only a few interventions had evolved to facilitate collective action through formal democratic structures (stage 3). These reported improved sexual negotiating power and community solidarity, and positive behavioural and clinical outcomes. Sustainability of many projects was weakened by disunity within transient communities, variable commitment of programmers, low human resource capacity and general resource limitations. Conclusions Most FSW SRH projects in Africa implemented participatory processes consistent with only the earliest stages of community empowerment, although isolated projects demonstrate proof of concept for successful empowerment interventions in African settings. PMID:24916108

Immigration status and HIV-risk related behaviors among female sex workers in South America.

PubMed

Bautista, Christian T; Mosquera, Carlos; Serra, Margarita; Gianella, Alberto; Avila, Maria M; Laguna-Torres, Victor; Carr, Jean K; Montano, Silvia M; Sanchez, José L

2008-03-01

This study compares immigrant (i.e., foreigner) with non-immigrant (i.e., local/native) HIV-related risk behaviors among female sex workers (FSW) in South America. A total of 1,845 FSW were enrolled in Argentina, Bolivia, Ecuador, and Uruguay. According to their nationality, 10.1% of participants were immigrant FSW. Immigrant FSW were more likely to be younger in Argentina; to work in a disco/bar in Bolivia; to be single and use illegal drugs in Ecuador; and to work in a brothel, consume alcohol, and have sex with foreign clients in Uruguay. HIV-related sexual and drug use behaviors were more common among immigrant FSW in Bolivia, Ecuador, and Uruguay. Country-specific HIV/STI prevention and control programs should be developed for immigrant FSW populations in South America.

The Core Flight System (cFS) Community: Providing Low Cost Solutions for Small Spacecraft

NASA Technical Reports Server (NTRS)

McComas, David; Wilmot, Jonathan; Cudmore, Alan

2016-01-01

In February 2015 the NASA Goddard Space Flight Center (GSFC) completed the open source release of the entire Core Flight Software (cFS) suite. After the open source release a multi-NASA center Configuration Control Board (CCB) was established that has managed multiple cFS product releases. The cFS was developed and is being maintained in compliance with the NASA Class B software development process requirements and the open source release includes all Class B artifacts. The cFS is currently running on three operational science spacecraft and is being used on multiple spacecraft and instrument development efforts. While the cFS itself is a viable flight software (FSW) solution, we have discovered that the cFS community is a continuous source of innovation and growth that provides products and tools that serve the entire FSW lifecycle and future mission needs. This paper summarizes the current state of the cFS community, the key FSW technologies being pursued, the development/verification tools and opportunities for the small satellite community to become engaged. The cFS is a proven high quality and cost-effective solution for small satellites with constrained budgets.

Manufacturing Challenges Associated with the Use of Metal Matrix Composites in Aerospace Structures

NASA Technical Reports Server (NTRS)

Prater, Tracie

2014-01-01

Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramic particles or fibers. These materials possess a very high strength to weight ratio, good resistance to impact and wear, and a number of other properties which make them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as NASA's Orion Crew Exploration Vehicle and Space Launch System. A current focus of FSW research is to extend the process to new materials, such as MMCs, which are difficult to weld using conventional fusion techniques. Since Friction Stir Welding occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This chapter summarizes the challenges encountered when joining MMCs to themselves or to other materials in structures. Specific attention is paid to the influence of process variables in Friction Stir Welding on the wear process characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. A phenomenological model of the wear process was constructed based on the rotating plug model of Friction Stir Welding. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is also explored. In-process force, torque, and vibration signals are analyzed to assess the feasibility of in situ monitoring of tool shape changes as a result of wear (an advancement which would eliminate the need for off-line evaluation of tool condition during joining). Monitoring, controlling, and reducing tool wear in FSW of MMCs is essential to implementation of these materials in structures (such as launch vehicles) where they would be of maximum benefit. The work presented here is extendable to machining of MMCs, where wear of the tool is also a limiting factor.

Friction Stir Welding for Aluminum Metal Matrix Composites (MMC's) (Center Director's Discretionary Fund, Project No. 98-09)

NASA Technical Reports Server (NTRS)

Lee, J. A.; Carter, R. W.; Ding, J.

1999-01-01

This technical memorandum describes an investigation of using friction stir welding (FSW) process for joining a variety of aluminum metal matrix composites (MMC's) reinforced with discontinuous silicon-carbide (SiC) particulate and functional gradient materials. Preliminary results show that FSW is feasible to weld aluminum MMC to MMC or to aluminum-lithium 2195 if the SiC reinforcement is <25 percent by volume fraction. However, a softening in the heat-affected zone was observed and is known to be one of the major limiting factors for joint strength. The pin tool's material is made from a low-cost steel tool H-13 material, and the pin tool's wear was excessive such that the pin tool length has to be manually adjusted for every 5 ft of weldment. Initially, boron-carbide coating was developed for pin tools, but it did not show a significant improvement in wear resistance. Basically, FSW is applicable mainly for butt joining of flat plates. Therefore, FSW of cylindrical articles such as a flange to a duct with practical diameters ranging from 2-5 in. must be fully demonstrated and compared with other proven MMC joining techniques for cylindrical articles.

Prediction of the Vickers Microhardness and Ultimate Tensile Strength of AA5754 H111 Friction Stir Welding Butt Joints Using Artificial Neural Network

PubMed Central

De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Facchini, Francesco; Mummolo, Giovanni; Ludovico, Antonio Domenico

2016-01-01

A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans. The quality of joints was evaluated through destructive and non-destructive tests (visual tests, macro graphic analysis, tensile tests, indentation Vickers hardness tests and t thermographic controls). The simulation model was based on the adoption of the Artificial Neural Networks (ANNs) characterized by back-propagation learning algorithm with different types of architecture, which were able to predict with good reliability the FSW process parameters for the welding of the AA5754 H111 aluminum plates in Butt-Joint configuration. PMID:28774035

Linking process and structure in the friction stir scribe joining of dissimilar materials: A computational approach with experimental support

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Varun; Upadhyay, Piyush; Fifield, Leonard S.

The friction stir welding (FSW) is a popular technique to join dissimilar materials in numerous applications. The solid state nature of the process enables joining materials with strikingly different physical properties. For the welds in lap configuration, an enhancement to this technology is made by introducing a short hard insert, referred to as cutting-scribe, at the bottom of the tool pin. The cutting-scribe induces deformation in the bottom plate which leads to the formation of mechanical interlocks or hook like structures at the interface of two materials. A thermo-mechanically coupled computational model employing coupled Eulerian-Lagrangian approach is developed to quantitativelymore » capture the morphology of these interlocks during the FSW process. The simulations using developed model are validated by the experimental observations.The identified interface morphology coupled with the predicted temperature field from this process-structure model can then be used to estimate the post-weld microstructure and joint strength.« less

Friction Stir Welding of Curved Plates

NASA Technical Reports Server (NTRS)

Sanchez, Nestor

1999-01-01

Friction stir welding (FSW) is a remarkable technology for making butt and lap joints in aluminum alloys. The process operates by passing a rotating tool between two closely butted plates. This process generates heat and the heated material is stirred from both sides of the plates to generate a high quality weld. Application of this technique has a very broad field for NASA. In particular, NASA is interested in using this welding process to manufacture tanks and curved elements. Therefore, this research has been oriented to the study the FSW of curved plates. The study has covered a number of topics that are important in the model development and to uncover the physical process involve in the welding itself. The materials used for the experimental welds were as close to each other as we could possibly find, aluminum 5454-0 and 5456-0 with properties listed at http://matweb.com. The application of FSW to curved plates needs to consider the behavior that we observed in this study. There is going to be larger force in the normal direction (Fz) as the curvature of the plate increases. A particular model needs to be derived for each material and thickness. A more complete study should also include parameters such as spin rate, tool velocity, and power used. The force in the direction of motion (Fx) needs to be reconsidered to make sure of its variability with respect to other parameters such as velocity, thickness, etc. It seems like the curvature does not play a role in this case. Variations in temperature were found with respect to the curvature. However, these changes seem to be smaller than the effect on Fz. The temperatures were all below the melting point. We understand now that the process of FSW produces a three dimensional flow of material that takes place during the weld. This flow needs to be study in a more detailed way to see in which directions the flow of material is stronger. It could be possible to model the flow using a 2-dimensional model in the particular directions where the flow moves faster. More experimental information is required to enrich the knowledge about FSW, and from this point, derive useful mathematical formulas to optimize the process and the design of the machines that will perform it. More experiments and experimental equipment are required to uncover the mathematics of the process.

Thermal Management in Friction-Stir Welding of Precipitation-Hardened Aluminum Alloys

NASA Astrophysics Data System (ADS)

Upadhyay, Piyush; Reynolds, Anthony P.

2015-05-01

Process design and implementation in friction-stir welding (FSW) is mostly dependent on empirical information. Basic science of FSW and processing can only be complete when fundamental interrelationships between the process control parameters and response variables and the resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters such as tool rotation, translation rates, and forge axis force have complicated and interactive relationships to process-response variables such as peak temperature and time at temperature. Of primary influence on the other process-response parameters are temperature and its gradient in the deformation and heat-affected zones. Through a review of pertinent works in the literature and results from boundary condition experiments performed in precipitation-hardening aluminum alloys, this article partially elucidates the nature and effects of temperature transients caused by variation of thermal boundaries in FSW.

Corrosion Properties of Cryorolled AA2219 Friction Stir Welded Joints Using Different Tool Pin Profiles

NASA Astrophysics Data System (ADS)

Kamal Babu, K.; Panneerselvam, K.; Sathiya, P.; Noorul Haq, A.; Sundarrajan, S.; Mastanaiah, P.; Srinivasa Murthy, C. V.

The purpose of this paper is to present the corrosion behavior of the Cryorolled (CR) material and its Friction Stir Welded joints. Due to the thermal cycles of Friction Stir Welding (FSW) process, the corrosion behavior of the material gets affected. Here, the cryorolling process was carried out on AA2219 alloy and CR material was joined by FSW process using four different pin tool profiles such as cylindrical, threaded cylindrical, square and hexagonal pin. The FSW joints were analyzed by corrosion resistance with the help of potentiodynamic polarization test with 3.5% NaCl solution. From the analysis, it is found that CR AA2219 material exhibits good corrosion resistance compared to the base AA2219 material, and also a hexagonal pin profile FSW joint exhibits high corrosion resistance. Among the weld joints created by four different tools, the lowest corrosion resistance was found in the cylindrical pin tool FSW welds. Further, the corroded samples were investigated through metallurgical investigations like OM, Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray Spectroscopy (EDX) and X-Ray Diffraction (XRD). It was found that the amount of dissolution of Al2Cu precipitate was present in the weld nugget. The amount of dissolution of Al2Cu precipitate is higher in the weld nugget produced by hexagonal pin tool. This is due to the enhancement of the corrosion resistance.

Metal Cutting Theory and Friction Stir Welding Tool Design

NASA Technical Reports Server (NTRS)

Payton, Lewis N.

2003-01-01

Friction Stir Welding (FSW) is a relatively new industrial process that was invented at The Weld Institute (TWI, United Kingdom) and patented in 1992 under research funded by in part by the National Aeronautics and Space Administration (NASA). Often quoted advantages of the process include good strength and ductility along with minimization of residual stress and distortion. Less well advertised are the beneficial effects of this solid state welding process in the field of occupational and environmental safety. It produces superior weld products in difficult to weld materials without producing any toxic fumes or solid waste that must be controlled as hazardous waste. In fact, it reduces noise pollution in the workspace as well. In the early days of FSW, most welding was performed on modified machine tools, in particular on milling machines with modified milling cutters. In spite of the obvious milling heritage of the process, the techniques and lessons learned from almost 250 years of successful metalworking with milling machines have not been applied in the field of modern Friction Stir Welding. The goal of the current research was to study currently successful FSW tools and parameterize the process in such a way that the design of new tools for new materials could be accelerated. Along the way, several successful new tooling designs were developed for current issues at the Marshall Space Flight Center with accompanying patent disclosures

Molecular dynamics modeling of bonding two materials by atomic scale friction stir welding at different process parameters

NASA Astrophysics Data System (ADS)

Konovalenko S., Iv.; Psakhie, S. G.

2017-12-01

Using the molecular dynamics method, we simulated the atomic scale butt friction stir welding on two crystallites and varied the onset FSW tool plunge depth. The effects of the plunge depth value on the thermomechanical evolution of nanosized crystallites and mass transfer in the course of FSW have been studied. The increase of plunge depth values resulted in more intense heating and reducing the plasticized metal resistance to the tool movement. The mass transfer intensity was hardly dependent on the plunge depth value. The plunge depth was recommended to be used as a FSW process control parameter in addition to the commonly used ones.

Effect of Weld Tool Geometry on Friction Stir Welded AA2219-T87 Properties

NASA Technical Reports Server (NTRS)

Querin, Joseph A.; Schneider, Judy A.

2008-01-01

In this study, flat panels of AA2219-T87 were friction stir welded (FSWed) using weld tools with tapered pins The three pin geometries of the weld tools included: 0 (straight cylinder), 30 , and 60 angles on the frustum. For each weld tool geometry, the FSW process parameters were optimized to eliminate defects. A constant heat input was maintained while varying the process parameters of spindle rpm and travel speed. This provided a constant heat input for each FSW weld panel while altering the hot working conditions imparted to the workpiece. The resulting mechanical properties were evaluated from tensile test results of the FSW joint.

Pearson's Functions to Describe FSW Weld Geometry

NASA Astrophysics Data System (ADS)

Lacombe, D.; Gutierrez-Orrantia, M. E.; Coupard, D.; Tcherniaeff, S.; Girot, F.

2011-01-01

Friction stir welding (FSW) is a relatively new joining technique particularly for aluminium alloys that are difficult to fusion weld. In this study, the geometry of the weld has been investigated and modelled using Pearson's functions. It has been demonstrated that the Pearson's parameters (mean, standard deviation, skewness, kurtosis and geometric constant) can be used to characterize the weld geometry and the tensile strength of the weld assembly. Pearson's parameters and process parameters are strongly correlated allowing to define a control process procedure for FSW assemblies which make radiographic or ultrasonic controls unnecessary. Finally, an optimisation using a Generalized Gradient Method allows to determine the geometry of the weld which maximises the assembly tensile strength.

Confidentiality, Privacy, and Respect: Experiences of Female Sex Workers Participating in HIV Research in Andhra Pradesh, India

PubMed Central

Reed, Elizabeth; Khoshnood, Kaveh; Blankenship, Kim M.; Fisher, Celia B.

2014-01-01

Female sex workers (FSW) from Andhra Pradesh, India who had participated in HIV research were interviewed to examine participant perspectives on research ethics. Content analysis indicated that aspects of the consent process, staff gender and demeanor, study environment, survey content, time requirements for study participation, and perceived FSW community support for research were key factors influencing whether FSW perceived their confidentiality and privacy had been maintained, and whether they felt the study was conducted respectfully. Findings suggest that partnership with community-based organizations and investigation of participant’s experiences in HIV prevention research can provide critical information to best inform research ethics protocols, a particular priority among research studies with highly stigmatized populations, such as FSW. PMID:24572080

Spacecraft Onboard Software Maintenance: An Effective Approach which Reduces Costs and Increases Science Return

NASA Technical Reports Server (NTRS)

Shell, Elaine M.; Lue, Yvonne; Chu, Martha I.

1999-01-01

Flight software (FSW) is a mission critical element of spacecraft functionality and performance. When ground operations personnel interface to a spacecraft, they are dealing almost entirely with onboard software. This software, even more than ground/flight communications systems, is expected to perform perfectly at all times during all phases of on-orbit mission life. Due to the fact that FSW can be reconfigured and reprogrammed to accommodate new spacecraft conditions, the on-orbit FSW maintenance team is usually significantly responsible for the long-term success of a science mission. Failure of FSW can result in very expensive operations work-around costs and lost science opportunities. There are three basic approaches to staffing on-orbit software maintenance, namely: (1) using the original developers, (2) using mission operations personnel, or (3) assembling a Center of Excellence for multi-spacecraft on-orbit FSW support. This paper explains a National Aeronautics and Space Administration, Goddard Space Flight Center (NASA/GSFC) experience related to the roles of on-orbit FSW maintenance personnel. It identifies the advantages and disadvantages of each of the three approaches to staffing the FSW roles, and demonstrates how a cost efficient on-orbit FSW Maintenance Center of Excellence can be established and maintained with significant return on the investment.

Complete Status Report Documenting Development of Friction Stir Welding for Joining Thin Wall Tubing of ODS Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoelzer, David T.; Bunn, Jeffrey R.; Gussev, Maxim N.

The development of friction stir welding (FSW) for joining thin sections of the advanced oxide dispersion strengthened (ODS) 14YWT ferritic alloy was initiated in Fuel Cycle Research and Development (FCRD), now the Nuclear Technology Research and Development (NTRD), in 2015. The first FSW experiment was conducted in late FY15 and successfully produced a bead-on-plate stir zone (SZ) on a 1 mm thick plate of 14YWT (SM13 heat). The goal of this research task is to ultimately demonstrate that FSW is a feasible method for joining thin wall (0.5 mm thick) tubing of 14YWT.

Strategies for recruiting steady male partners of female sex workers for HIV research

PubMed Central

Fleming, Paul J.; Barrington, Clare; Perez, Martha; Donastorg, Yeycy; Kerrigan, Deanna

2014-01-01

Steady male partners of female sex workers (FSW) are a key population for HIV prevention, but researchers face challenges finding and recruiting this population. We conducted forty in-depth interviews with FSW and steady male partners of FSW in Santo Domingo, Dominican Republic about how to engage steady male partners in HIV research. Participants cautioned that male partners might be unwilling to participate because of discomfort disclosing intimate information and cultural norms of masculinity. They recommended inviting male partners to research offices, instead of venue-based recruitment, because it was more private and trust-promoting. Most participants suggested that FSW could refer their partners or men could refer their friends who have FSW partners. Participants emphasized that referrals could break down trust-related barriers that prevent male partners from participating. Establishing an environment of respect and trust in the research setting can aid referral processes as individuals who participate communicate their positive experiences to their networks. PMID:25192901

Friction Stir Weld Restart+Reweld Repair Allowables

NASA Technical Reports Server (NTRS)

Clifton, Andrew

2008-01-01

A friction stir weld (FSW) repair method has been developed and successfully implemented on Al 2195 plate material for the Space Shuttle External Fuel Tank (ET). The method includes restarting the friction stir weld in the termination hole of the original weld followed by two reweld passes. Room temperature and cryogenic temperature mechanical properties exceeded minimum FSW design strength and compared well with the development data. Simulated service test results also compared closely to historical data for initial FSW, confirming no change to the critical flaw size or inspection requirements for the repaired weld. Testing of VPPA fusion/FSW intersection weld specimens exhibited acceptable strength and exceeded the minimum design value. Porosity, when present at the intersection was on the root side toe of the fusion weld, the "worst case" being 0.7 inch long. While such porosity may be removed by sanding, this "worst case" porosity condition was tested "as is" and demonstrated that porosity did not negatively affect the strength of the intersection weld. Large, 15-inch "wide panels" FSW repair welds were tested to demonstrate strength and evaluate residual stresses using photo stress analysis. All results exceeded design minimums, and photo stress analysis showed no significant stress gradients due to the presence of the restart and multi-pass FSW repair weld.

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Heat Transfer Modeling and Thermal History Analysis

NASA Astrophysics Data System (ADS)

Pan, Yi; Lados, Diana A.

2017-02-01

Friction stir welding (FSW) is a technique that can be used for materials joining and local microstructural refinement. Owing to the solid-state character of the process, FSW has significant advantages over traditional fusion welding, including reduced part distortion and overheating. In this study, a novel heat transfer model was developed to predict weld temperature distributions and quantify peak temperatures under various combinations of processing parameters for different wrought and cast Al alloys. Specifically, an analytical analysis was first developed to characterize and predict heat generation rate within the weld nugget, and then a two-dimensional (2D) numerical simulation was performed to evaluate the temperature distribution in the weld cross-section and top-view planes. A further three-dimensional (3D) simulation was developed based on the heat generation analysis. The model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for all studied materials and conditions.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

2011-01-01

NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Friction Pull Plug Welding in Aluminum Alloys

NASA Technical Reports Server (NTRS)

Brooke, Shane A.; Bradford, Vann

2012-01-01

NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

Characterization of friction stir welded joint of low nickel austenitic stainless steel and modified ferritic stainless steel

NASA Astrophysics Data System (ADS)

Mondal, Mounarik; Das, Hrishikesh; Ahn, Eun Yeong; Hong, Sung Tae; Kim, Moon-Jo; Han, Heung Nam; Pal, Tapan Kumar

2017-09-01

Friction stir welding (FSW) of dissimilar stainless steels, low nickel austenitic stainless steel and 409M ferritic stainless steel, is experimentally investigated. Process responses during FSW and the microstructures of the resultant dissimilar joints are evaluated. Material flow in the stir zone is investigated in detail by elemental mapping. Elemental mapping of the dissimilar joints clearly indicates that the material flow pattern during FSW depends on the process parameter combination. Dynamic recrystallization and recovery are also observed in the dissimilar joints. Among the two different stainless steels selected in the present study, the ferritic stainless steels shows more severe dynamic recrystallization, resulting in a very fine microstructure, probably due to the higher stacking fault energy.

Microstructural Evolution in Friction Stir Welding of Ti-6Al-4V

NASA Technical Reports Server (NTRS)

Rubisoff, H.; Querin, J.; Magee, D.; Schneider, J.

2008-01-01

Friction stir welding (FSW) is a thermo-mechanical process that utilizes a nonconsumable rotating pin tool to consolidate a weld joint. In the conventional FSW process, the pin tool is responsible for generating both the heat required to soften the material and the forces necessary to deform and combine the weld seam. As such, the geometry of the pin tool is important to the quality of the weld and the process parameters required to produce the weld. Because the geometry of the pin tool is limitless, a reduced set of pin tools was formed to systematically study their effect on the weldment with respect to mechanical properties and resultant microstructure. In this study 0deg, 15deg, 30deg, 45deg, and 60deg tapered, microwave sintered, tungsten carbide (WC) pin tools were used to FSW Ti-6Al-4V. Transverse sections of the weld were used to test for mechanical properties and to document the microstructure using optical microscopy. X-ray diffraction (XRD) was also used to characterize the microstructure in the welds. FSW results for the 45deg and 60deg pin tools are reported in this paper.

Physics-based process model approach for detecting discontinuity during friction stir welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrivastava, Amber; Pfefferkorn, Frank E.; Duffie, Neil A.

2015-02-12

The goal of this work is to develop a method for detecting the creation of discontinuities during friction stir welding. This in situ weld monitoring method could significantly reduce the need for post-process inspection. A process force model and a discontinuity force model were created based on the state-of-the-art understanding of flow around an friction stir welding (FSW) tool. These models are used to predict the FSW forces and size of discontinuities formed in the weld. Friction stir welds with discontinuities and welds without discontinuities were created, and the differences in force dynamics were observed. In this paper, discontinuities weremore » generated by reducing the tool rotation frequency and increasing the tool traverse speed in order to create "cold" welds. Experimental force data for welds with discontinuities and welds without discontinuities compared favorably with the predicted forces. The model currently overpredicts the discontinuity size.« less

Cassini's Test Methodology for Flight Software Verification and Operations

NASA Technical Reports Server (NTRS)

Wang, Eric; Brown, Jay

2007-01-01

The Cassini spacecraft was launched on 15 October 1997 on a Titan IV-B launch vehicle. The spacecraft is comprised of various subsystems, including the Attitude and Articulation Control Subsystem (AACS). The AACS Flight Software (FSW) and its development has been an ongoing effort, from the design, development and finally operations. As planned, major modifications to certain FSW functions were designed, tested, verified and uploaded during the cruise phase of the mission. Each flight software upload involved extensive verification testing. A standardized FSW testing methodology was used to verify the integrity of the flight software. This paper summarizes the flight software testing methodology used for verifying FSW from pre-launch through the prime mission, with an emphasis on flight experience testing during the first 2.5 years of the prime mission (July 2004 through January 2007).

Optimization and Characterization of the Friction Stir Welded Sheets of AA 5754-H111: Monitoring of the Quality of Joints with Thermographic Techniques.

PubMed

De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Palumbo, Davide; De Finis, Rosa; Galietti, Umberto

2017-10-11

Friction Stir Welding (FSW) is a solid-state welding process, based on frictional and stirring phenomena, that offers many advantages with respect to the traditional welding methods. However, several parameters can affect the quality of the produced joints. In this work, an experimental approach has been used for studying and optimizing the FSW process, applied on 5754-H111 aluminum plates. In particular, the thermal behavior of the material during the process has been investigated and two thermal indexes, the maximum temperature and the heating rate of the material, correlated to the frictional power input, were investigated for different process parameters (the travel and rotation tool speeds) configurations. Moreover, other techniques (micrographs, macrographs and destructive tensile tests) were carried out for supporting in a quantitative way the analysis of the quality of welded joints. The potential of thermographic technique has been demonstrated both for monitoring the FSW process and for predicting the quality of joints in terms of tensile strength.

High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

2015-05-01

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

A Combined Experimental and Analytical Modeling Approach to Understanding Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.; Stewart, Michael B.; Adams, Glynn P.; Romine, Peter

1998-01-01

In the Friction Stir Welding (FSW) process a rotating pin tool joins the sides of a seam by stirring them together. This solid state welding process avoids problems with melting and hot-shortness presented by some difficult-to weld high-performance light alloys. The details of the plastic flow during the process are not well understood and are currently a subject of research. Two candidate models of the FSW process, the Mixed Zone (MZ) and the Single Slip Surface (S3) model are presented and their predictions compared to experimental data.

Friction Stir Welding of Line-Pipe Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanderson, Samuel; Mahoney, Murray; Feng, Zhili

Friction stir welding (FSW) offers both economic and technical advantages over conventional fusion welding practices for welding line-pipe. For offshore line-pipe construction, the economic savings has been shown to be considerable, approaching a calculated 25%. Offshore pipe is relatively small diameter but heavy wall compared to onshore pipe. One concern is the ability to achieve consistent full weld penetration in an on-site offshore FSW operation, e.g., on a lay-barge. In addition, depending on the size and morphology of the unwelded zone, lack of penetration at the weld root can be difficult if not impossible to detect by conventional NDE methods.more » Thus, an approach to assure consistent full penetration via process control is required for offshore line-pipe construction using FSW. For offshore construction, an internal structural mandrel can be used offering the opportunity to use a sacrificial anvil FSW approach. With this approach, a small volume of sacrificial material can be inserted into the structural anvil. The FSW tool penetrates into the sacrificial anvil, beyond the inner diameter of the pipe wall, thus assuring full penetration. The sacrificial material is subsequently removed from the pipe inner wall. In the work presented herein, FSW studies were completed on both 6 mm and 12 mm wall thickness line-pipe. Lastly, post-FSW evaluations including radiography, root-bend tests, and metallography demonstrated the merits of the sacrificial anvil approach to achieve consistent full penetration.« less

Characterization of Plastic flow and Resulting Micro-Textures in a Friction Stir Weld

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.

2003-01-01

The mechanically affected zone of a friction stir weld (FSW) cross section exhibits two distinct microstructural regions, possibly the residues of two distinct currents of metal in the FSW flow process. In this study the respective textures of these microstructural regions are investigated using orientation image mapping (OIM).

Microstructure Characterization and Stress Corrosion Evaluation of Autogenous and Hybrid Friction Stir Welded Al-Cu-Li 2195 Alloy

NASA Technical Reports Server (NTRS)

Li, Zhixian; Arbegast, William J.; Meletis, Efstathios I.

1997-01-01

Friction stir welding process is being evaluated for application on the Al-Cu-Li 2195 Super-Light Weight External Tank of the Space Transportation System. In the present investigation Al-Cu-Li 2195 plates were joined by autogenous friction stir welding (FSW) and hybrid FSW (friction stir welding over existing variable polarity plasma arc weld). Optical microscopy and transmission electron microscopy (TEM) were utilized to characterize microstructures of the weldments processed by both welding methods. TEM observations of autogenous FSW coupons in the center section of the dynamically-recrystallized zone showed an equiaxed recrystallized microstructure with an average grain size of approx. 3.8 microns. No T(sub 1), precipitates were present in the above-mentioned zone. Instead, T(sub B) and alpha precipitates were found in this zone with a lower population. Alternate immersion, anodic polarization, constant load, and slow strain tests were carried out to evaluate the general corrosion and stress-corrosion properties of autogenous and hybrid FSW prepared coupons. The experimental results will be discussed.

Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.

2008-01-01

Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

2017-02-01

Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

Friction Stir Welding and Processing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Carsley, John; Clarke, Kester D.

2015-05-01

With nearly twenty years of international research and collaboration in friction stir welding (FSW) and processing industrial applications have spread into nearly every feasible market. Currently applications exist in aerospace, railway, automotive, personal computers, technology, marine, cutlery, construction, as well as several other markets. Implementation of FSW has demonstrated diverse opportunities ranging from enabling new materials to reducing the production costs of current welding technologies by enabling condensed packaging solutions for traditional fabrication and assembly. TMS has sponsored focused instruction and communication in this technology area for more than fifteen years, with leadership from the Shaping and Forming Committee, whichmore » organizes a biannual symposium each odd year at the annual meeting. A focused publication produced from each of these symposia now comprises eight volumes detailing the primary research and development activities in this area over the last two decades. The articles assembled herein focus on both recent developments and technology reviews of several key markets from international experts in this area.« less

Hybrid FSWeld-bonded joint fatigue behaviour

NASA Astrophysics Data System (ADS)

Lertora, Enrico; Mandolfino, Chiara; Gambaro, Carla; Pizzorni, Marco

2018-05-01

Aluminium alloys, widely used in aeronautics, are increasingly involved in the automotive industry due to the good relationship between mechanical strength and specific weight. The lightening of the structures is the first objective, which allows the decreasing in the weight in motion. The use of aluminium alloys has also seen the introduction of the Friction Stir Welding (FSW) technique for the production of structural overlapping joints. FSW allows us to weld overlap joints free from defects, but with the presence of a structural notch further aggravated by the presence of a "hook" defect near the edge of the weld. Furthermore, FSW presents a weld penetration area connected to the tool geometry and penetration. The experimental activity will be focused on the combination of two different joining techniques, which can synergistically improve the final joint resistance. In particular, the welding and bonding process most commonly known as weld-bonding is defined as a hybrid process, as it combines two different junction processes. In this paper we analyse FSWelded AA6082 aluminium alloy overlapped joint with the aim of quantitatively evaluating the improvement provided by the presence of an epoxy adhesive between the plates. After optimising the weld-bonding process, the mechanical behaviour of welded joints will be analysed by static and dynamic tests. The presence of the adhesive should limit the negative effect of the structural notch inevitable in a FSW overlapped joint.

2014/2219 Tri-Point Crack Analysis

NASA Technical Reports Server (NTRS)

Horton, Karla Renee

2011-01-01

Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. The objective of this study was to evaluate the deformation response at the tips of cracks located in the heat affected zone of friction plug welds and to study the fracture behavior of welds with defects in the form of fatigue cracks. The study used existing 2014-T6 to 2219-T87 self-reacting friction stir weld panels with 2219-T87 friction plug welds. Electro-discharge machined (EDM) notches were machined into the heat affected zone of the plug at the plug-to-base metal interface. Samples were then cycled to generate a fatigue crack emanating from the notch. After the fatigue crack reached a pre-defined length, a speckle pattern was applied and the ARAMIS system (a three dimensional imaging correlation system) was used to measure the deformations at the crack tip under a sequence of loads. Testing was conducted at ambient laboratory conditions. Fracture data from the testing was analyzed to evaluate residual strength capability of the panel as a function of flaw size. ARAMIS strain data was evaluated to examine strain and deformation patterns that develop around the crack tip and at the plug/weld interfaces. Four samples were used in this study, with three samples in a post-weld heat treated condition. Three samples contained large diameter plugs (M5) and one sample contained a small diameter plug (M3). Two samples were 4 inches in width and two samples were 8.5 inches in width. All samples failed through the precrack with residual strengths ranging from 37 ksi to 42 ksi.

Nano-Sized Grain Refinement Using Friction Stir Processing

DTIC Science & Technology

2013-03-01

friction stir weld is a very fine grain microstructure produced as a result of dynamic recrystallization. The friction stir ... Friction Stir Processing, Magnesium, Nano-size grains Abstract A key characteristic of a friction stir weld is a very fine grain microstructure...state process developed on the basis of the friction stir welding (FSW) technique invented by The Welding Institute (TWI) in 1991 [2]. During

Sexual and physical violence against female sex workers in Kenya: a qualitative enquiry.

PubMed

Okal, Jerry; Chersich, Matthew F; Tsui, Sharon; Sutherland, Elizabeth; Temmerman, Marleen; Luchters, Stanley

2011-05-01

Few studies in Africa provide detailed descriptions of the vulnerabilities of female sex workers (FSW) to sexual and physical violence, and how this impacts on their HIV risk. This qualitative study documents FSW's experiences of violence in Mombasa and Naivasha, Kenya. Eighty-one FSW who obtained clients from the streets, transportation depots, taverns, discos and residential areas were recruited through local sex workers trained as peer counsellors to participate in eight focus-group discussions. Analysis showed the pervasiveness of sexual and physical violence among FSW, commonly triggered by negotiation around condoms and payment. Pressing financial needs of FSW, gender-power differentials, illegality of trading in sex and cultural subscriptions to men's entitlement for sex sans money underscore much of this violence. Sex workers with more experience had developed skills to avoid threats of violence by identifying potentially violent clients, finding safer working areas and minimising conflict with the police. Addressing violence and concomitant HIV risks and vulnerabilities faced by FSW should be included in Kenya's national HIV/AIDS strategic plan. This study indicates the need for multilevel interventions, including legal reforms so that laws governing sex work promote the health and human rights of sex workers in Kenya.

HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Wei; Chen, Gaoqiang; Chen, Jian

Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zonemore » mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.« less

Optimization and Characterization of the Friction Stir Welded Sheets of AA 5754-H111: Monitoring of the Quality of Joints with Thermographic Techniques

PubMed Central

De Filippis, Luigi Alberto Ciro; Serio, Livia Maria; Galietti, Umberto

2017-01-01

Friction Stir Welding (FSW) is a solid-state welding process, based on frictional and stirring phenomena, that offers many advantages with respect to the traditional welding methods. However, several parameters can affect the quality of the produced joints. In this work, an experimental approach has been used for studying and optimizing the FSW process, applied on 5754-H111 aluminum plates. In particular, the thermal behavior of the material during the process has been investigated and two thermal indexes, the maximum temperature and the heating rate of the material, correlated to the frictional power input, were investigated for different process parameters (the travel and rotation tool speeds) configurations. Moreover, other techniques (micrographs, macrographs and destructive tensile tests) were carried out for supporting in a quantitative way the analysis of the quality of welded joints. The potential of thermographic technique has been demonstrated both for monitoring the FSW process and for predicting the quality of joints in terms of tensile strength. PMID:29019948

Automation of Flight Software Regression Testing

NASA Technical Reports Server (NTRS)

Tashakkor, Scott B.

2016-01-01

NASA is developing the Space Launch System (SLS) to be a heavy lift launch vehicle supporting human and scientific exploration beyond earth orbit. SLS will have a common core stage, an upper stage, and different permutations of boosters and fairings to perform various crewed or cargo missions. Marshall Space Flight Center (MSFC) is writing the Flight Software (FSW) that will operate the SLS launch vehicle. The FSW is developed in an incremental manner based on "Agile" software techniques. As the FSW is incrementally developed, testing the functionality of the code needs to be performed continually to ensure that the integrity of the software is maintained. Manually testing the functionality on an ever-growing set of requirements and features is not an efficient solution and therefore needs to be done automatically to ensure testing is comprehensive. To support test automation, a framework for a regression test harness has been developed and used on SLS FSW. The test harness provides a modular design approach that can compile or read in the required information specified by the developer of the test. The modularity provides independence between groups of tests and the ability to add and remove tests without disturbing others. This provides the SLS FSW team a time saving feature that is essential to meeting SLS Program technical and programmatic requirements. During development of SLS FSW, this technique has proved to be a useful tool to ensure all requirements have been tested, and that desired functionality is maintained, as changes occur. It also provides a mechanism for developers to check functionality of the code that they have developed. With this system, automation of regression testing is accomplished through a scheduling tool and/or commit hooks. Key advantages of this test harness capability includes execution support for multiple independent test cases, the ability for developers to specify precisely what they are testing and how, the ability to add automation, and the ability of the harness and cases to be executed continually. This test concept is an approach that can be adapted to support other projects.

Evaluation of Friction Stir Processing of HY-80 Steel Under Wet and Dry Conditions

DTIC Science & Technology

2012-03-01

MS80. The tool design included a convex scroll shoulder with a step-spiral protruding pin (CS4). Figure 4. PCBN FSW/P threaded tool. 12 For...and cooling water was pumped through during the FSW/P process, Figure 7. Sea salt was added to distilled water to create a 3.5% salt content. 14... Vacuum hot extraction was used to determine the hydrogen concentration as specified by ASTM E 146–83. In addition, combustion infrared detection

Friction stir welding process and material microstructure evolution modeling in 2000 and 5000 series of aluminum alloy

NASA Astrophysics Data System (ADS)

Yalavarthy, Harshavardhan

Interactions between the rotating and advancing pin-shaped tool (terminated at one end with a circular-cylindrical shoulder) with the clamped welding-plates and the associated material and heat transport during a Friction Stir Welding (FSW) process are studied computationally using a fully-coupled thermo-mechanical finite-element analysis. To surmount potential numerical problems associated with extensive mesh distortions/entanglement, an Arbitrary Lagrangian Eulerian (ALE) formulation was used which enabled adaptive re-meshing (to ensure the continuing presence of a high-quality mesh) while allowing full tracking of the material free surfaces. To demonstrate the utility of the present computational approach, the analysis is applied to the cases of same-alloy FSW of two Aluminum-alloy grades: (a) AA5083 (a solid-solution strengthened and strain-hardened/stabilized Al-Mg-Mn alloy); and (b) AA2139 (a precipitation hardened quaternary Al-Cu-Mg-Ag alloy). Both of these alloys are currently being used in military-vehicle hull structural and armor systems. In the case of non-age-hardenable AA5083, the dominant microstructure evolution processes taking place during FSW are extensive plastic deformation and dynamic recrystallization of highly-deformed material subjected to elevated temperatures approaching the melting temperature. To account for the competition between plastic-deformation controlled strengthening and dynamic-recrystallization induced softening phenomena during the FSW process, the original Johnson-Cook strain- and strain-rate hardening and temperature-softening material strength model is modified in the present work using the available recrystallization-kinetics experimental data. In the case of AA2139, in addition to plastic deformation and dynamic recrystallization, precipitates coarsening, over-aging, dissolution and re-precipitation had to be also considered. Limited data available in the open literature pertaining to the kinetics of the aforementioned microstructure-evolution processes are used to predict variation in the material hardness and the residual stresses throughout the various FSW zones of the two alloys. The results showed that with proper modeling of the material behavior under high-temperature/severe-plastic-deformation conditions, significantly improved agreement can be attained between the computed and measured post-FSW residual-stress and material-strength distribution results. Keywords: Friction Stir Welding; AA5083; AA2139; Johnson-Cook Strength Model; Finite Element Analysis; Hardness Prediction.

Software Cost Estimation Using a Decision Graph Process: A Knowledge Engineering Approach

NASA Technical Reports Server (NTRS)

Stukes, Sherry; Spagnuolo, John, Jr.

2011-01-01

This paper is not a description per se of the efforts by two software cost analysts. Rather, it is an outline of the methodology used for FSW cost analysis presented in a form that would serve as a foundation upon which others may gain insight into how to perform FSW cost analyses for their own problems at hand.

Computational Investigation of Hardness Evolution During Friction-Stir Welding of AA5083 and AA2139 Aluminum Alloys

DTIC Science & Technology

2011-01-01

expensive post-weld machining; and (g) low 102 environmental impact . However, some disadvantages of the 103 FSW process have also been identified such as (a...material. Its 443 density and thermal properties are next set to that of AISI- H13 , 444 a hot-worked tool steel, frequently used as the FSW-tool 445

Modifications in the AA5083 Johnson-Cook Material Model for Use in Friction Stir Welding Computational Analyses

DTIC Science & Technology

2011-12-30

which reduces the need for expensive post-weld machining; and (g) low environmental impact . However, some disadvantages of the FSW process have also...next set to that of AISI- H13 , a hot-worked tool steel, frequently used as the FSW-tool material (Ref 16). The work-piece material is assumed to be

Welding parameter optimization of alloy material by friction stir welding using Taguchi approach and design of experiments

NASA Astrophysics Data System (ADS)

Karwande, Amit H.; Rao, Seeram Srinivasa

2018-04-01

Friction stir welding (FSW) a welding process in which metals are joint by melting them at their solid state. In different engineering areas such as civil, mechanical, naval and aeronautical engineering beams are widely used of the magnesium alloys for different applications and that are joined by conventional inert gas welding process. Magnesium metal has less density and low melting point for that reason large heat generation in the common welding process so its necessity to adapt new welding process. FSW process increases the weld quality which observed under various mechanical testing by using different tool size.

Influence of Processing Parameters on the Flow Path in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.

2006-01-01

Friction stir welding (FSW) is a solid phase welding process that unites thermal and mechanical aspects to produce a high quality joint. The process variables are rpm, translational weld speed, and downward plunge force. The strain-temperature history of a metal element at each point on the cross-section of the weld is determined by the individual flow path taken by the particular filament of metal flowing around the tool as influenced by the process variables. The resulting properties of the weld are determined by the strain-temperature history. Thus to control FSW properties, improved understanding of the processing parameters on the metal flow path is necessary.

Bioconversion of fish solid waste into PHB using Bacillus subtilis based submerged fermentation process.

PubMed

Mohapatra, S; Sarkar, B; Samantaray, D P; Daware, A; Maity, S; Pattnaik, S; Bhattacharjee, S

2017-12-01

Currently, one of the major problem affecting the world is solid waste management, predominantly petroleum-based plastic and fish solid waste (FSW). However, it is very difficult to reduce the consumption of plastic as well as fish products, but it is promising to convert FSW to biopolymer to reduce eco-pollution. On account of that, the bioconversion of FSW extract to polyhydroxybutyrate (PHB) was undertaken by using Bacillus subtilis (KP172548). Under optimized conditions, 1.62 g/L of PHB has been produced by the bacterium. The purified compound was further characterized by advanced analytical technologies to elucidate its chemical structure. Results indicated that the biopolymer was found to be PHB, the most common homopolymer of polyhydroxyalkanoates (PHAs). This is the first report demonstrating the efficacy of B. subtilis to utilize FSW extract to produce biopolymer. The biocompatibility of the PHB against murine macrophage cell line RAW264.7 demonstrated that, it was comparatively less toxic, favourable for surface attachment and proliferation in comparison with poly-lactic acid (PLA) and commercially available PHB. Thus, further exploration is highly indispensable to use FSW extract as a substrate for production of PHB at pilot scale.

Mechanical Property Analysis in the Retracted Pin-Tool (RPT) Region of Friction Stir Welded (FSW) Aluminum Lithium 2195

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Oelgoetz, Peter A.

1999-01-01

The "Auto-Adjustable Pin Tool for Friction Stir Welding", was developed at The Marshall Space Flight Center to address process deficiencies unique to the FSW process. The auto-adjustable pin tool, also called the retractable pin-tool (R.PT) automatically withdraws the welding probe of the pin-tool into the pin-tool's shoulder. The primary function of the auto-adjustable pin-tool is to allow for keyhole closeout, necessary for circumferential welding and localized weld repair, and, automated pin-length adjustment for the welding of tapered material thickness. An overview of the RPT hardware is presented. The paper follows with studies conducted using the RPT. The RPT was used to simulate two capabilities; welding tapered material thickness and closing out the keyhole in a circumferential weld. The retracted pin-tool regions in aluminum- lithium 2195 friction stir weldments were studied through mechanical property testing and metallurgical sectioning. Correlation's can be =de between retractable pin-tool programmed parameters, process parameters, microstructure, and resulting weld quality.

Friction-Stir Welding - Heavy Inclusions in Bi-metallic welds of Al 2219/2195

NASA Technical Reports Server (NTRS)

Rietz, Ward W., Jr.

2008-01-01

Heavy Inclusions (HI) were detected for the first time by radiographic examination in aluminum alloy 2219forging/2195plate (advancing/retreating side) Friction Sir Welds (FSW) for the Space Shuttle External Tank (ET) Program. Radiographic HI indications appear as either small (approx.0.005"-0.025") individual particles or clusters of small particles. Initial work was performed to verify that the HI was not foreign material or caused by FSW pin tool debris. That and subsequent elemental analysis determined that the HI were large agglomerations of Al2Cu (theta phase), which is the strengthening precipitate in Al2219. A literature search on that subject determined that the agglomeration of phase has also been found in Al2219 bead on plate FSW [Ref. 1]. Since this was detected in ET space flight hardware, an investigative study of the effect of agglomerated theta phase particles in FSW Al2219f/2195p was performed. Numerous panels of various lengths were welded per ET weld procedures and radiographically inspected to determine if any HI was detected. Areas that had HI were sampled for room temperature and cyclic cryogenic (-423F) tensile testing and determined no significant adverse affect on mechanical properties when compared to test specimens without HI and historical data. Fracture surface examination using the Scanning Electron Microscope (SEM) revealed smaller phase agglomerations undetectable by radiographic inspection dispersed throughout the Al2219f/2195p FSW. This indicates that phase agglomeration is inherent to the Al2219f/2195p FSW process and only rarely creates agglomerations large enough to be detected by radiography. HI has not been observed in FSW of plate to plate material for either Al2219 or AL2195.

Cost effectiveness of targeted HIV prevention interventions for female sex workers in India.

PubMed

Prinja, Shankar; Bahuguna, Pankaj; Rudra, Shalini; Gupta, Indrani; Kaur, Manmeet; Mehendale, S M; Chatterjee, Susmita; Panda, Samiran; Kumar, Rajesh

2011-06-01

To ascertain the cost effectiveness of targeted interventions for female sex workers (FSW) under the National AIDS Control Programme in India. A compartmental mathematical Markov state model was used over a 20-year time horizon (1995-2015) to estimate the cost effectiveness of FSW targeted interventions, with a health system perspective. The incremental costs and effects of FSW targeted interventions were compared against a baseline scenario of mass media for the general population alone. The incremental cost-effectiveness ratio was computed at a 3% discount rate using HIV infections averted and disability-adjusted life-years (DALY) as benefit measures. It was assumed that the transmission of the HIV virus moves from a high-risk group (FSW) to the client population and finally to the general population (partners of clients). Targeted interventions for FSW result in a reduction of 47% (1.6 million) prevalent and 36% (2.7 million) cumulative HIV cases, respectively, in 2015. Adult HIV prevalence in India, with and without (mass media only) FSW interventions, would be 0.25% and 0.48% in 2015. Indian government and development partners spend an average US $104 (INR4680) per HIV infection averted and US $10.7 (INR483) per DALY averted. Discounting at 3%, FSW targeted interventions cost US $105.5 (INR4748) and US $10.9 (INR490) per HIV case and DALY averted, respectively. At the current gross domestic product in India, targeted intervention is a cost-effective strategy for HIV prevention in India.

Effect of tool offsetting on microstructure and mechanical properties dissimilar friction stir welded Mg-Al alloys

NASA Astrophysics Data System (ADS)

Baghdadi, Amir Hossein; Fazilah Mohamad Selamat, Nor; Sajuri, Zainuddin

2017-09-01

Automotive and aerospace industries are attempting to produce lightweight structure by using materials with low density such as aluminum and magnesium alloys to increase the fuel efficiency and consequently reduce the environmental pollution. It can be beneficial to join Mg to Al to acquire ideal performance in special applications. Friction stir welding (FSW) is solid state welding processes and relatively lower temperature of the process compared to fusion welding processes. This makes FSW a potential joining technique for joining of the dissimilar materials. In this study, Mg-Al butt joints were performed by FSW under different tool offset conditions, rotation rates (500-600 rpm) and traverse speeds (20 mm/min) with tool axis offset 1 mm shifted into AZ31B or Al6061 (T6), and without offset. During the welding process AZ31B was positioned at the advancing side (AS) and Al6061 (T6) was located at the retreating side (RS). Defect free AZ31B-Al6061 (T6) dissimilar metal FSW joints with good mechanical properties were obtained with the combination of intermediate rotation rate and low traverse speed pin is in the middle. When tool positioned in -1 mm or +1 mm offsetting, some defects were found in SZ of dissimilar FSWed joints such as cavity, tunnel, and crack. Furthermore, a thin layer of intermetallic compounds was observed in the stir zone at the interface between Mg-Al plates. The strength of the joint was influenced by FSW parameters. Good mechanical properties obtained with the combination of intermediate rotational speed of 600 rpm and low travelling speed of 20 mm/min by locating Mg on advancing side when pin is in the middle. Also, Joint efficiency of the welds prepared in the present study was between 29% and 68% for the different welding parameters.

Prediction of the Grain-Microstructure Evolution Within a Friction Stir Welding (FSW) Joint via the Use of the Monte Carlo Simulation Method

NASA Astrophysics Data System (ADS)

Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Avuthu, V.; Galgalikar, R.; Zhang, Z.

2015-09-01

A thermo-mechanical finite element analysis of the friction stir welding (FSW) process is carried out and the evolution of the material state (e.g., temperature, the extent of plastic deformation, etc.) monitored. Subsequently, the finite-element results are used as input to a Monte-Carlo simulation algorithm in order to predict the evolution of the grain microstructure within different weld zones, during the FSW process and the subsequent cooling of the material within the weld to room temperature. To help delineate different weld zones, (a) temperature and deformation fields during the welding process, and during the subsequent cooling, are monitored; and (b) competition between the grain growth (driven by the reduction in the total grain-boundary surface area) and dynamic-recrystallization grain refinement (driven by the replacement of highly deformed material with an effectively "dislocation-free" material) is simulated. The results obtained clearly revealed that different weld zones form as a result of different outcomes of the competition between the grain growth and grain refinement processes.

Microhardness, strength and strain field characterization of self-reacting friction stir and plug welds of dissimilar aluminum alloys

NASA Astrophysics Data System (ADS)

Horton, Karla Renee

Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side and a SR-FSW (AA2014-T6 to AA2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures. The initial weld microstructure analysis showed a nugget region with fine grains and a displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the nugget region. The displaced material shared the same hardness as the parent material. Dynamic recrystallization was observed in the SR-FSW zone and the displaced weld seam region. The welds revealed a fine grain structure in the SR-FSW zone with a sharp demarcation seen on the advancing side and fairly diffuse flow observed on the retreating side. The parent material hardness is 145 HV700g with a drop in hardness starting at the HAZ to 130 HV700g. The hardness further drops in the TMAZ to118 HV700g with an increase representing a dispersed interface of AA2014-T6 material to 135 HV700g. The hardness then drops significantly within the nugget region to 85 HV700g followed by an increase through the retreating side TMAZ into the HAZ to 135 HV 700g. There was a sharp increase in the hardness value within the nugget region with the samples that were PWHT showing an increase of 58%. The welded joints were tested for ultimate strength. The testing variations included two specimen widths, two plug sizes (M3 and M5), room temperature and cryogenic testing, and post weld heat treated (PWHT) samples. Initial welds had an average ultimate strength of 370 MPa. There was a slight drop from initial weld strength to plug weld strength of approximately 13.8 MPa was observed with M3 plug strength approximately equal to M5 plug strength. The PWHT strengths at room temperature were slightly higher than non-PWHT of 13.8--20.7 MPa and PWHT strengths were equal to non-PWHT at cryogenic temperature. Non-PWHT had a cryogenic strength enhancement approximately 59.2 MPa and PWHT had a cryogenic strength enhancement of approximately 57.2 MPa in the M3 and M5 plugs. Within the subsets of data collected no major statistical significance in strength behavior was observed between the samples tested at room temperature or between the subsets tested at LN2. In almost all cases, failure occurred on the retreating side of the weld which corresponds to the softer material (AA2219-T87). Exceptions were characterized with flaws (weld defects) in the sample. In these cases, failure occurred on the advancing side, the side where flaws were detected. Ductile fracture was noted in most all samples. Digital image correlation using the ARAMIS system was used to define strain patterns in the weld joint. Strain accumulation was observed in the weld along the retreating side and around the plug. ARAMIS data in comparison to extensometer data shows a very reasonable comparison. The ARAMIS strain gage data showed the retreating side of the major diameter has a greater yield than the advancing side. This behavior is identical to the external electrical resistance strain gages.

The association between substance use and sub-optimal HIV treatment engagement among HIV-infected female sex workers in Lilongwe, Malawi.

PubMed

Lancaster, Kathryn E; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C; Chadwick, Katy; Powers, Kimberly A; Pence, Brian W; Go, Vivian F; Hoffman, Irving F; Miller, William C

2017-02-01

Female sex workers (FSW) have a high prevalence of substance use and HIV, but the impact of substance use on HIV treatment engagement is not well established. We evaluated the association between alcohol and marijuana use and sub-optimal HIV treatment engagement outcomes among HIV-infected FSW in Lilongwe, Malawi. We enroled FSW using venue-based recruitment into a cross-sectional evaluation assessing substance use and HIV treatment engagement. Seropositive FSW, identified through HIV rapid testing, received rapid CD4 count and viral load testing. We used Poisson regression with robust variance estimates to ascertain associations of alcohol and marijuana use with sub-optimal HIV treatment outcomes: (1) lack of ART use among previously diagnosed, ART-eligible FSW and (2) viral nonsuppression among FSW on ART. Of previously diagnosed, ART-eligible FSW (n = 96), 29% were not using ART. Patterns of hazardous drinking were identified in 30%, harmful drinking in 10%, and alcohol dependence in 12%. ART-eligible FSW with harmful drinking or alcohol dependency were 1.9 (95% CI: 1.0, 3.8) times as likely to not use ART compared to FSW without harmful or dependent drinking. Among those on ART, 14% were virally nonsuppressed. The prevalence ratio for viral nonsuppression was 2.0 (95% CI: 0.6, 6.5) for harmful drinkers and alcohol-dependent FSW. Over 30% of ART-eligible FSW reported using marijuana. Marijuana-using FSW were 1.9 (95% CI: 0.8, 4.6) times as likely to not use ART compared to FSW who were not using marijuana. Given the high prevalence of alcohol use and its association with lack of ART use, ART uptake and alcohol reduction strategies should be tailored for alcohol-using FSW in Malawi.

The association between substance use and sub-optimal HIV treatment engagement among HIV-infected female sex workers in Lilongwe, Malawi

PubMed Central

Lancaster, Kathryn E.; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C.; Chadwick, Katy; Powers, Kimberly A.; Pence, Brian W.; Go, Vivian F.; Hoffman, Irving F.; Miller, William C.

2016-01-01

Female sex workers (FSW) have a high prevalence of substance use and HIV, but the impact of substance use on HIV treatment engagement is not well established. We evaluated the association between alcohol and marijuana use and sub-optimal HIV treatment engagement outcomes among HIV-infected FSW in Lilongwe, Malawi. We enroled FSW using venue-based recruitment into a cross-sectional evaluation assessing substance use and HIV treatment engagement. Seropositive FSW, identified through HIV rapid testing, received rapid CD4 count and viral load testing. We used Poisson regression with robust variance estimates to ascertain associations of alcohol and marijuana use with sub-optimal HIV treatment outcomes: (1) lack of ART use among previously diagnosed, ART-eligible FSW and (2) viral nonsuppression among FSW on ART. Of previously diagnosed, ART-eligible FSW (n = 96), 29% were not using ART. Patterns of hazardous drinking were identified in 30%, harmful drinking in 10%, and alcohol dependence in 12%. ART-eligible FSW with harmful drinking or alcohol dependency were 1.9 (95% CI: 1.0, 3.8) times as likely to not use ART compared to FSW without harmful or dependent drinking. Among those on ART, 14% were virally nonsuppressed. The prevalence ratio for viral nonsuppression was 2.0 (95% CI: 0.6, 6.5) for harmful drinkers and alcohol-dependent FSW. Over 30% of ART-eligible FSW reported using marijuana. Marijuana-using FSW were 1.9 (95% CI: 0.8, 4.6) times as likely to not use ART compared to FSW who were not using marijuana. Given the high prevalence of alcohol use and its association with lack of ART use, ART uptake and alcohol reduction strategies should be tailored for alcohol-using FSW in Malawi. PMID:27442009

Microstructure Evolution and Mechanical Properties of High-Speed Friction Stir Welded Aluminum Alloy Thin Plate Joints

NASA Astrophysics Data System (ADS)

Liu, Fenjun; Fu, Li; Chen, Haiyan

2018-06-01

Sound friction stir welded (FSW) joints of 6061-T6 aluminum alloy sheets with an 0.8 mm thickness were obtained at conventional speed (2000 rpm, 300 mm/min) and high speed (11,000 rpm, 1500 mm/min). The recrystallization mechanism, precipitate evolution, mechanical properties and fracture behavior were investigated in detail. Microstructure analyses revealed that the grain structure evolution in the nugget zone (NZ) was dominated by continuous dynamic recrystallization. In the process of FSW, high speed facilitates the formation of finer equiaxed recrystallized grains, higher density of dislocations and substructures, and a larger number of precipitates in the NZ compared to the conventional speed, which further significantly improves the hardness and tensile strength of the joints. The maximum tensile strength was obtained with 292.6 MPa, 83.2% for the 6061-T6 aluminum alloy and 122.6% for the conventional-speed FSW joints. This work provides an effective method for preparing FSW aluminum alloy thin plate joints with excellent mechanical properties.

Versatile Friction Stir Welding/Friction Plug Welding System

NASA Technical Reports Server (NTRS)

Carter, Robert

2006-01-01

A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

Development strategies for the satellite flight software on-board Meteosat Third Generation

NASA Astrophysics Data System (ADS)

Tipaldi, Massimo; Legendre, Cedric; Koopmann, Olliver; Ferraguto, Massimo; Wenker, Ralf; D'Angelo, Gianni

2018-04-01

Nowadays, satellites are becoming increasingly software dependent. Satellite Flight Software (FSW), that is to say, the application software running on the satellite main On-Board Computer (OBC), plays a relevant role in implementing complex space mission requirements. In this paper, we examine relevant technical approaches and programmatic strategies adopted for the development of the Meteosat Third Generation Satellite (MTG) FSW. To begin with, we present its layered model-based architecture, and the means for ensuring a robust and reliable interaction among the FSW components. Then, we focus on the selection of an effective software development life cycle model. In particular, by combining plan-driven and agile approaches, we can fulfill the need of having preliminary SW versions. They can be used for the elicitation of complex system-level requirements as well as for the initial satellite integration and testing activities. Another important aspect can be identified in the testing activities. Indeed, very demanding quality requirements have to be fulfilled in satellite SW applications. This manuscript proposes a test automation framework, which uses an XML-based test procedure language independent of the underlying test environment. Finally, a short overview of the MTG FSW sizing and timing budgets concludes the paper.

Mechanical Properties of Friction Stir Welds in A12195-T8

NASA Technical Reports Server (NTRS)

Kinchen, David G.; Li, Zhixian; Adams, Glynn P.

1999-01-01

An extensive study of the mechanical properties of friction stir welded Al-Li 2195 has been conducted by Lockheed Martin Michoud Space Systems under contract to NASA. The study was part of a development program in which weld parameters were defined for using FSW to assemble large-scale aluminum cryogenic tanks. In excess of 300 feet of 0.320 in. gage plate material was welded and tested. The tests include room temperature and cryogenic temperature tensile tests and surface crack tension (SCT) tests, nondestructive evaluation, metallurgical studies, and photostress analysis. The results of the testing demonstrated improved mechanical properties with FSW as compared to typical fusion welding processes. Increases in ultimate tensile strength, cryogenic enhancement and elongation were observed with the tensile test results. Increased fracture toughness was observed with the SCT results. Nondestructive evaluations were conducted on all welded Joints. No volumetric defects were indicated. Surface indications on the root side of the welds did not significantly affect weld strength. The results of the nondestructive evaluations were confirmed via metallurgical studies. Photostress analysis revealed strain concentrations in multi-pass and heat-repaired FSW's. Details of the tests and results are presented.

Laser Peening Effects on Friction Stir Welding

NASA Technical Reports Server (NTRS)

Hatamleh, Omar

2011-01-01

Friction Stir Welding (FSW) is a welding technique that uses frictional heating combined with forging pressure to produce high strength bonds. It is attractive for aerospace applications. Although residual stresses in FSW are generally lower when compared to conventional fusion welds, recent work has shown that significant tensile residual stresses can be present in the weld after fabrication. Therefore, laser shock peening was investigated as a means of moderating the tensile residual stresses produced during welding. This slide presentation reviews the effect of Laser Peening on the weld, in tensile strength, strain, surface roughness, microhardness, surface wear/friction, and fatigue crack growth rates. The study concluded that the laser peening process can result in considerable improvement to crack initiaion, propagation and mechanical properties in FSW.

Determination of airborne nanoparticles from welding operations.

PubMed

Gomes, João Fernando Pereira; Albuquerque, Paula Cristina Silva; Miranda, Rosa Maria Mendes; Vieira, Maria Teresa Freire

2012-01-01

The aim of this study is to assess the levels of airborne ultrafine particles emitted in welding processes (tungsten inert gas [TIG], metal active gas [MAG] of carbon steel, and friction stir welding [FSW] of aluminum) in terms of deposited area in pulmonary alveolar tract using a nanoparticle surface area monitor (NSAM) analyzer. The obtained results showed the dependence of process parameters on emitted ultrafine particles and demonstrated the presence of ultrafine particles compared to background levels. Data indicated that the process that resulted in the lowest levels of alveolar deposited surface area (ADSA) was FSW, followed by TIG and MAG. However, all tested processes resulted in significant concentrations of ultrafine particles being deposited in humans lungs of exposed workers.

Behavioral and Psychosocial Correlates of HIV Testing Among Male Clients of Female Sex Workers in Tijuana, Mexico.

PubMed

Fleming, Paul J; Patterson, Thomas L; Chavarin, Claudia V; Semple, Shirley J; Magis-Rodriguez, Carlos; Pitpitan, Eileen V

2017-08-01

We use data collected from a sample of 400 male clients of female sex workers (FSW) to examine their HIV testing behavior. We present frequencies of HIV testing and used bivariate and multivariable analyses to assess its socio-demographic, behavioral, and psychosocial correlates. We found that the majority (55 %) of male clients of FSW in Tijuana, Mexico had never had an HIV test and the prevalence of HIV testing within the past year was low (9 %). In multivariable analyses, significant correlates of having ever tested for HIV were higher age, higher HIV knowledge score, lower sexual compulsiveness score, lower misogynistic attitudes score, having a condom break during sex with a FSW, and higher frequency of sex with a FSW while she was high. Our findings represent an important starting point for developing effective interventions to address the need to promote HIV testing among this population.

Three Dimensional Numerical Simulation and Characterization of Crack Growth in the Weld Region of a Friction Stir Welded Structure

NASA Technical Reports Server (NTRS)

Seshadri, Banavara R.; Smith, Stephen W.; Newman, John A.

2013-01-01

Friction stir welding (FSW) fabrication technology is being adopted in aerospace applications. The use of this technology can reduce production cost, lead-times, reduce structural weight and need for fasteners and lap joints, which are typically the primary locations of crack initiation and multi-site fatigue damage in aerospace structures. FSW is a solid state welding process that is well-suited for joining aluminum alloy components; however, the process introduces residual stresses (both tensile and compressive) in joined components. The propagation of fatigue cracks in a residual stress field and the resulting redistribution of the residual stress field and its effect on crack closure have to be estimated. To insure the safe insertion of complex integral structures, an accurate understanding of the fatigue crack growth behavior and the complex crack path process must be understood. A life prediction methodology for fatigue crack growth through the weld under the influence of residual stresses in aluminum alloy structures fabricated using FSW will be detailed. The effects and significance of the magnitude of residual stress at a crack tip on the estimated crack tip driving force are highlighted. The location of the crack tip relative to the FSW and the effect of microstructure on fatigue crack growth are considered. A damage tolerant life prediction methodology accounting for microstructural variation in the weld zone and residual stress field will lead to the design of lighter and more reliable aerospace structures

Aquarius' Object-Oriented, Plug and Play Component-Based Flight Software

NASA Technical Reports Server (NTRS)

Murray, Alexander; Shahabuddin, Mohammad

2013-01-01

The Aquarius mission involves a combined radiometer and radar instrument in low-Earth orbit, providing monthly global maps of Sea Surface Salinity. Operating successfully in orbit since June, 2011, the spacecraft bus was furnished by the Argentine space agency, Comision Nacional de Actividades Espaciales (CONAE). The instrument, built jointly by NASA's Caltech/JPL and Goddard Space Flight Center, has been successfully producing expectation-exceeding data since it was powered on in August of 2011. In addition to the radiometer and scatterometer, the instrument contains an command & data-handling subsystem with a computer and flight software (FSW) that is responsible for managing the instrument, its operation, and its data. Aquarius' FSW is conceived and architected as a Component-based system, in which the running software consists of a set of Components, each playing a distinctive role in the subsystem, instantiated and connected together at runtime. Component architectures feature a well-defined set of interfaces between the Components, visible and analyzable at the architectural level (see [1]). As we will describe, this kind of an architecture offers significant advantages over more traditional FSW architectures, which often feature a monolithic runtime structure. Component-based software is enabled by Object-Oriented (OO) techniques and languages, the use of which again is not typical in space mission FSW. We will argue in this paper that the use of OO design methods and tools (especially the Unified Modeling Language), as well as the judicious usage of C++, are very well suited to FSW applications, and we will present Aquarius FSW, describing our methods, processes, and design, as a successful case in point.

High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri

Friction-stir-welding (FSW) is a cost-effective and high quality joining process for aluminum alloys (especially heat-treatable allo ys) that has been applied successfully in the aerospace industry. However, the full potential of FSW on more cost-sensitive applications is still limited by the production rate, namely the welding speed of the process. The majority of literature evaluating FSW of aluminum alloys is based on welds made in the range of welding speeds around hundreds of millimeters per minute, and only a handful are at a moderate speed of 1 m/min. In this study we present a microstructural analysis of friction stir weldedmore » AA7075-T6 blanks with welding speeds up to 3 m/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. Results are coupled with welding parameters to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high speed processing.« less

Genesis of Microstructures in Friction Stir Welding of Ti-6Al-4V

NASA Astrophysics Data System (ADS)

Tchein, Gnofam Jacques; Jacquin, Dimitri; Coupard, Dominique; Lacoste, Eric; Girot Mata, Franck

2018-06-01

This paper is focused on the genesis of microstructures in friction stir welding (FSW) of the Ti-6Al-4V alloy. Several titanium joints, initially prepared with four different preheat treatments, were processed by FSW. Detailed microstructural analyses were performed in order to investigate change in the microstructure during the process. In this work, the FSW processing allows a controlled and stable microstructure to be produced in the stirring zone, regardless of the initial heat treatment or the welding conditions. The welded material undergoes a severe thermomechanical treatment which can be divided into two steps. First, the friction in the shoulder and the plastic strain give rise to the necessary conditions to allow a continuous dynamic recrystallization of the β phase. This operation produces a fine and equiaxed β grain structure. Second, once the pin has moved away, the temperature decreases, and the material undergoes a heat treatment equivalent to air quenching. The material thus exhibits a β → β + α transformation with germination of a fine intergranular Widmanstätten phase within the ex-fully-recrystallized- β grains.

Fundamental Study of Material Flow in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Reynolds, Anthony P.

1999-01-01

The presented research project consists of two major parts. First, the material flow in solid-state, friction stir, butt-welds as been investigated using a marker insert technique. Changes in material flow due to welding parameter as well as tool geometry variations have been examined for different materials. The method provides a semi-quantitative, three-dimensional view of the material transport in the welded zone. Second, a FSW process model has been developed. The fully coupled model is based on fluid mechanics; the solid-state material transport during welding is treated as a laminar, viscous flow of a non-Newtonian fluid past a rotating circular cylinder. The heat necessary for the material softening is generated by deformation of the material. As a first step, a two-dimensional model, which contains only the pin of the FSW tool, has been created to test the suitability of the modeling approach and to perform parametric studies of the boundary conditions. The material flow visualization experiments agree very well with the predicted flow field. Accordingly, material within the pin diameter is transported only in the rotation direction around the pin. Due to the simplifying assumptions inherent in the 2-D model, other experimental data such as forces on the pin, torque, and weld energy cannot be directly used for validation. However, the 2-D model predicts the same trends as shown in the experiments. The model also predicts a deviation from the "normal" material flow at certain combinations of welding parameters, suggesting a possible mechanism for the occurrence of some typical FSW defects. The next step has been the development of a three-dimensional process model. The simplified FSW tool has been designed as a flat shoulder rotating on the top of the workpiece and a rotating, cylindrical pin, which extends throughout the total height of the flow domain. The thermal boundary conditions at the tool and at the contact area to the backing plate have been varied to fit experimental data such as temperature profiles, torque and tool forces. General aspects of the experimentally visualized material flow pattern are confirmed by the 3-D model.

Flight Software Math Library

NASA Technical Reports Server (NTRS)

McComas, David

2013-01-01

The flight software (FSW) math library is a collection of reusable math components that provides typical math utilities required by spacecraft flight software. These utilities are intended to increase flight software quality reusability and maintainability by providing a set of consistent, well-documented, and tested math utilities. This library only has dependencies on ANSI C, so it is easily ported. Prior to this library, each mission typically created its own math utilities using ideas/code from previous missions. Part of the reason for this is that math libraries can be written with different strategies in areas like error handling, parameters orders, naming conventions, etc. Changing the utilities for each mission introduces risks and costs. The obvious risks and costs are that the utilities must be coded and revalidated. The hidden risks and costs arise in miscommunication between engineers. These utilities must be understood by both the flight software engineers and other subsystem engineers (primarily guidance navigation and control). The FSW math library is part of a larger goal to produce a library of reusable Guidance Navigation and Control (GN&C) FSW components. A GN&C FSW library cannot be created unless a standardized math basis is created. This library solves the standardization problem by defining a common feature set and establishing policies for the library s design. This allows the libraries to be maintained with the same strategy used in its initial development, which supports a library of reusable GN&C FSW components. The FSW math library is written for an embedded software environment in C. This places restrictions on the language features that can be used by the library. Another advantage of the FSW math library is that it can be used in the FSW as well as other environments like the GN&C analyst s simulators. This helps communication between the teams because they can use the same utilities with the same feature set and syntax.

The effects of maintaining temperature in annealing heat treatment for an FSWed 6061-T6 Al alloy.

PubMed

Lee, Seung-Jun; Han, Min-Su; Kim, Seong-Jong

2013-08-01

The technological development of all kinds of lightweight transportation devices including vehicles, aircraft, ships, etc. has progressed markedly with the demand for energy saving and environmental protection. Aluminum alloy is in the spotlight as it is a suitable environmentally friendly material. However, deformation is a major problem during the welding process because aluminum alloy has a large thermal expansion coefficient. In addition, it is known that its corrosion resistance is excellent; nevertheless, in practice, considerable corrosion is generated and this is a major problem. To solve this problem, the friction stir welding (FSW) technology is applied extensively at various industrial fields as a new welding technique. This method involves a process in which materials are joined by frictional heat and physical force. Therefore, we evaluated improvements in mechanical properties and corrosion resistance through annealing heat treatment after FSW. The electrochemical experiment did not show a significant difference. However, the microstructure observation showed defectless, fine crystal particles, indicating excellent properties at 200-225°C.

Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

DOE PAGES

Rabby, Reza; Tang, Wei; Reynolds, A. P.

2015-05-13

In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rabby, Reza; Tang, Wei; Reynolds, A. P.

In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

Friction stir welded AM50 and AZ31 Mg alloys: Microstructural evolution and improved corrosion resistance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Templeman, Yael

One of the major drawbacks of Mg alloys is poor weldability, caused by porosity formation during conventional fusion welding processes. Friction Stir Welding (FSW) is promising technique in this context since it is a solid state technique. Contradicting results were published in the literature regarding the FSWed Mg alloys joint's properties. Current research was performed in order to investigate the microstructure and corrosion properties of FSWed Mg alloys, studying representatives of two commercial families: wrought AZ31-H24 and die cast AM50. It was found that in both alloys recrystallization occurred during the FSW. In AM50 the mechanism of the recrystallization wasmore » continuous, manifested by dislocation rearrangement into sub grain boundaries. In AZ31 discontinuous recrystallization had occurred through grain boundaries migration - twins rotated with respect to the matrix, turning into low angle grain boundaries. Corrosion resistance has improved during the FSW in both alloys to different extents. In the AM50 alloy, the nugget exhibited significantly higher surface potential than the base metal mainly due to the higher Al concentration in the matrix of the nugget, resulting from the dissolution of Al-enrichment and β-Mg{sub 17}Al{sub 12} phase. In the AZ31 alloy, no change in Al concentration had occurred, and the surface potential measured in the nugget was only slightly higher than in the base metal. These results underline the appropriateness of the FSW for Mg alloys since during the conventional welding deterioration of the corrosion resistance occurs. - Highlights: • Following FSW, AZ31-H24 experienced discontinuous recrystallization. • In AZ31 grain boundaries migration occurred, thus twins rotated. • In die cast AM50 continuous recrystallization occurred during the FSW. • In AM50 - dislocations rearranged into sub grain boundaries. • Corrosion resistance has improved during the FSW in both alloys to different extent.« less

The HIV Care Continuum among Female Sex Workers: A Key Population in Lilongwe, Malawi.

PubMed

Lancaster, Kathryn Elizabeth; Powers, Kimberly A; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C; Chadwick, Katy; Go, Vivian F; Pence, Brian W; Hoffman, Irving F; Miller, William C

2016-01-01

The HIV care continuum among female sex workers (FSW), a key population, has not been well characterized, especially within the generalized epidemics of sub-Saharan Africa. This was the first study to characterize the HIV care continuum among FSW in Lilongwe, Malawi. From July through September 2014, we used venue-based sampling to enroll 200 adult FSW in Lilongwe, Malawi into a cross-sectional evaluation assessing HIV care continuum outcomes. Seropositive FSW, identified using HIV rapid testing, received rapid CD4 counts in addition to viral loads using dried blood spots. We calculated proportions of HIV-infected FSW who had history of care, were on ART, and had suppressed viral load and we used Poisson regression to estimate the associations of demographic characteristics and transmission risk behaviors with each outcome. HIV seroprevalence was 69% (n = 138). Among all FSW the median age was 24 years (IQR: 22-28). Among the 20% who were newly diagnosed and reported previously testing negative, the median time since last HIV test was 11 months (interquartile range: 3-17). The majority (69%) of HIV-infected FSW had a history of HIV care, 52% reported current ART use, and 45% were virally suppressed. Of the FSW who reported current ART use, 86% were virally suppressed. Transmission risk behaviors were not associated with continuum outcomes. FSW in Lilongwe were predominately young and have a high HIV prevalence. Only half of HIV-infected FSW reported current ART use, but the majority of those on ART were virally suppressed. To reduce ongoing transmission and improve health outcomes, increased HIV testing, care engagement, and ART coverage is urgently needed among FSW. Universal testing and treatment strategies for all FSW in Malawi must be strongly considered.

The HIV Care Continuum among Female Sex Workers: A Key Population in Lilongwe, Malawi

PubMed Central

Lancaster, Kathryn Elizabeth; Powers, Kimberly A.; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C.; Chadwick, Katy; Go, Vivian F.; Pence, Brian W.; Hoffman, Irving F.; Miller, William C.

2016-01-01

Objective The HIV care continuum among female sex workers (FSW), a key population, has not been well characterized, especially within the generalized epidemics of sub-Saharan Africa. This was the first study to characterize the HIV care continuum among FSW in Lilongwe, Malawi. Methods From July through September 2014, we used venue-based sampling to enroll 200 adult FSW in Lilongwe, Malawi into a cross-sectional evaluation assessing HIV care continuum outcomes. Seropositive FSW, identified using HIV rapid testing, received rapid CD4 counts in addition to viral loads using dried blood spots. We calculated proportions of HIV-infected FSW who had history of care, were on ART, and had suppressed viral load and we used Poisson regression to estimate the associations of demographic characteristics and transmission risk behaviors with each outcome. Results HIV seroprevalence was 69% (n = 138). Among all FSW the median age was 24 years (IQR: 22–28). Among the 20% who were newly diagnosed and reported previously testing negative, the median time since last HIV test was 11 months (interquartile range: 3–17). The majority (69%) of HIV-infected FSW had a history of HIV care, 52% reported current ART use, and 45% were virally suppressed. Of the FSW who reported current ART use, 86% were virally suppressed. Transmission risk behaviors were not associated with continuum outcomes. Conclusions FSW in Lilongwe were predominately young and have a high HIV prevalence. Only half of HIV-infected FSW reported current ART use, but the majority of those on ART were virally suppressed. To reduce ongoing transmission and improve health outcomes, increased HIV testing, care engagement, and ART coverage is urgently needed among FSW. Universal testing and treatment strategies for all FSW in Malawi must be strongly considered. PMID:26808043

Modular, Autonomous Command and Data Handling Software with Built-In Simulation and Test

NASA Technical Reports Server (NTRS)

Cuseo, John

2012-01-01

The spacecraft system that plays the greatest role throughout the program lifecycle is the Command and Data Handling System (C&DH), along with the associated algorithms and software. The C&DH takes on this role as cost driver because it is the brains of the spacecraft and is the element of the system that is primarily responsible for the integration and interoperability of all spacecraft subsystems. During design and development, many activities associated with mission design, system engineering, and subsystem development result in products that are directly supported by the C&DH, such as interfaces, algorithms, flight software (FSW), and parameter sets. A modular system architecture has been developed that provides a means for rapid spacecraft assembly, test, and integration. This modular C&DH software architecture, which can be targeted and adapted to a wide variety of spacecraft architectures, payloads, and mission requirements, eliminates the current practice of rewriting the spacecraft software and test environment for every mission. This software allows missionspecific software and algorithms to be rapidly integrated and tested, significantly decreasing time involved in the software development cycle. Additionally, the FSW includes an Onboard Dynamic Simulation System (ODySSy) that allows the C&DH software to support rapid integration and test. With this solution, the C&DH software capabilities will encompass all phases of the spacecraft lifecycle. ODySSy is an on-board simulation capability built directly into the FSW that provides dynamic built-in test capabilities as soon as the FSW image is loaded onto the processor. It includes a six-degrees- of-freedom, high-fidelity simulation that allows complete closed-loop and hardware-in-the-loop testing of a spacecraft in a ground processing environment without any additional external stimuli. ODySSy can intercept and modify sensor inputs using mathematical sensor models, and can intercept and respond to actuator commands. ODySSy integration is unique in that it allows testing of actual mission sequences on the flight vehicle while the spacecraft is in various stages of assembly, test, and launch operations all without any external support equipment or simulators. The ODySSy component of the FSW significantly decreases the time required for integration and test by providing an automated, standardized, and modular approach to integrated avionics and component interface and functional verification. ODySSy further provides the capability for on-orbit support in the form of autonomous mission planning and fault protection.

Full-Field Strain Behavior of Friction Stir-Welded Titanium Alloy

DTIC Science & Technology

2008-01-01

and slag formed on the upper weld surface by the FSW process and the remnant laser weld bead on the underside of the FSW surface were removed from...using 3M brand ‘Super 77’ spray adhesive and then hand sanding against a mechanically flat ceramic backing surface using silicon 32 carbide...weld surface using Loctite brand “5-minute Epoxy” and allowing to cure. Following the required cure period, the aluminum grating glass backing was

Computational modeling of heat transfer and visco-plastic flow in friction stir welding

NASA Astrophysics Data System (ADS)

Nandan, Rituraj

With a focus to develop a quantitative understanding of the FSW process, a comprehensive three dimensional heat transfer and plastic flow model is developed. The model can predict variables such as temperature and velocity fields and torque based on the given welding parameters like weld velocity, tool rotational speed and axial pressure. It considers tool design dependent spatially variable heat generation rates, deformational work, non-Newtonian viscosity as a function of local strain rate, temperature and the nature of the material and temperature dependent thermal conductivity, specific heat capacity and yield stress. It is shown that the temperature fields, cooling rates, the plastic flow fields and the geometry of the thermo-mechanically affected zone (TMAZ) can be adequately described by solving the equations of conservation of mass, momentum and energy in three dimensions with appropriate boundary conditions and constitutive equations for viscosity. The model is tested for four different alloys: (1) AA 6061-T6, (2) 1018 Mn steel, (3) 304L stainless steel and (4) Ti-6Al-4V which have widely different thermophysical and rheological properties. Numerically computed temperature fields, variations of peak temperatures with FSW variables and TMAZ geometry were compared with the experimental results. Currently, due to unknown parameters in existing transport phenomena based models, the computed temperature and velocity fields and torque may not always agree with the corresponding experimentally determined values and may not show the same trend as experimental results for a range of welding variables. Here, it is shown that this problem can be solved by combining the rigorous phenomenological process sub-model with a multivariable optimization scheme called Differential Evolution. The values of the uncertain model input parameters from a limited volume of independent experimental data which includes temperature measurements obtained using thermocouples and torque measured using dynamometers. This approach resulted in agreement between the phenomenological model and the experimental results with a greater degree of certainty. It is tested for FSW of: (1) dissimilar AA 6061-T6 to AA 1200, (2) 1018 Mn steel and (3) Ti-6Al-4V. Independent thermocouple and dynamometer measurements are also used for validation and verification of results. Improvement in the reliability of the numerical model is an important first step towards increasing its practical usefulness. Also, one of the reasons why current models do not find extensive applications is because they cannot be used to tailor weld attributes. The aim of the present research is to develop a reliable bi-directional model which can find wide use in manufacturing and process control. It is shown that by coupling a reliable model with an evolutionary search algorithm, we can find multiple sets of welding parameters to achieve a target peak temperature and cooling rate in welds. The model is tested for dissimilar welds of AA 6351 and AA 1200. FSW is being increasingly used for dissimilar metal joining. Models are needed to calculate the redistribution of alloying elements when two alloys with dissimilar alloying element contents are joined. The transport and mixing of magnesium from Mg-rich AA 6061 alloy into a commercially pure aluminum AA 1200 was examined experimentally and numerically at various locations in the welded workpiece. The concentration of the solute is measured in transverse cross-sections across the weld-center line at various depths from the top surface of the workpiece. The measurement was done using electron probe micro-analysis (EPMA) of polished transverse-cut friction-stir welded samples. The comparison of the experimental and computed concentration profiles of magnesium shows imperfect mixing of the plasticized alloys during FSW. The plasticized material seem to move in layers without significant diffusive interlayer mixing. A comprehensive model for FSW is developed with capability of calculating temperature fields, material flow patterns and concentration fields in both similar and dissimilar welds in three dimensions. The model is tested for the FSW of alloys with widely different thermophysical properties. A mechanism for improving reliability and ability to provide guidance to tailor weld attributes is incorporated into the model to increase its practical usefulness. This is done by by combining the transport phenomena based model with Differential Evolution algorithm to minimize the objective function based on limited volume of experimental thermal cycles and torque measurements. (Abstract shortened by UMI.)

Optimizing friction stir weld parameters of aluminum and copper using conventional milling machine

NASA Astrophysics Data System (ADS)

Manisegaran, Lohappriya V.; Ahmad, Nurainaa Ayuni; Nazri, Nurnadhirah; Noor, Amirul Syafiq Mohd; Ramachandran, Vignesh; Ismail, Muhammad Tarmizizulfika; Ahmad, Ku Zarina Ku; Daruis, Dian Darina Indah

2018-05-01

The joining of two of any particular materials through friction stir welding (FSW) are done by a rotating tool and the work piece material that generates heat which causes the region near the FSW tool to soften. This in return will mechanically intermix the work pieces. The first objective of this study is to join aluminum plates and copper plates by means of friction stir welding process using self-fabricated tools and conventional milling machine. This study also aims to investigate the optimum process parameters to produce the optimum mechanical properties of the welding joints for Aluminum plates and Copper plates. A suitable tool bit and a fixture is to be fabricated for the welding process. A conventional milling machine will be used to weld the aluminum and copper. The most important parameters to enable the process are speed and pressure of the tool (or tool design and alignment of the tool onto the work piece). The study showed that the best surface finish was produced from speed of 1150 rpm and tool bit tilted to 3°. For a 200mm × 100mm Aluminum 6061 with plate thickness of 2 mm at a speed of 1 mm/s, the time taken to complete the welding is only 200 seconds or equivalent to 3 minutes and 20 seconds. The Copper plates was successfully welded using FSW with tool rotation speed of 500 rpm, 700 rpm, 900 rpm, 1150 rpm and 1440 rpm and with welding traverse rate of 30 mm/min, 60 mm/min and 90 mm/min. As the conclusion, FSW using milling machine can be done on both Aluminum and Copper plates, however the weld parameters are different for the two types of plates.

Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

PubMed

Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

2012-09-01

This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers.

Formation of Oxides in the Interior of Friction Stir Welds

NASA Technical Reports Server (NTRS)

Schneider, Judy; Chen, Po; Nunes, Arthur C., Jr.

2016-01-01

In friction stir welding (FSWing) the actual solid state joining takes place between the faying surfaces which form the weld seam. Thus the seam trace is often investigated for clues when the strength of the weld is reduced. Aluminum and its alloys are known to form a native, protective oxide on the surface. If these native surface oxides are not sufficiently broken up during the FSW process, they are reported to remain in the FSW interior and weaken the bond strength. This type of weld defect has been referred to as a lazy "S", lazy "Z", joint line defect, kissing bond, or residual oxide defect. Usually these defects are mitigated by modification of the process parameters, such as increased tool rotation rate, which causes a finer breakup of the native oxide particles. This study proposes that there may be an alternative mechanism for formation of oxides found within the weld nugget. As the oxidation rate increases at elevated temperatures above 400ºC, it may be possible for enhanced oxidation to occur on the interior surfaces during the FSW process from entrained air entering the seam gap. Normally, FSWs of aluminum alloys are made without a purge gas and it is unknown how process parameters and initial fit up could affect a potential air path into the interior during the processing. In addition, variations in FSW parameters, such as the tool rotation, are known to have a strong influence on the FSW temperature which may affect the oxidation rate if internal surfaces are exposed to entrained air. A series of FSWs were made in 3 different thickness panels of AA2219 (0.95, 1.27 and 1.56 cm) at 2 different weld pitches. As the thickness of the panels increased, there was an increased tendency for a gap to form in advance of the weld tool. If sufficient air is able to enter the workpiece gap prior to consolidation, the weld temperature can increase the oxidation rate on the interior surfaces. These oxidation rates would also be accelerated in areas of localized liquation. Metallographs from the weld panels showed indications of liquation at the grain boundaries. In FSWs of thicker panels, these regions of liquation were found to be heavily oxidized. The quality of the FSWs was evaluated from tensile testing at room temperature. As the panel thickness increased, a slight decrease in tensile strength was observed which was attributed to the presence of oxides. No oxide formation was observed in the thinner workpieces, although there were indications of localized liquation at the grain boundaries. Results from this study will assist in a better understand of the mechanisms of oxide formation in FSW interiors and provide methodology for minimizing their occurrence.

Sexual Health Knowledge and Health Practices of Female Sex Workers in Liuzhou, China, Differ by Size of Venue

PubMed Central

Brown, Jane D.; Muessig, Kathryn E.; Xianxiang, Feng; Wenzhen, He

2013-01-01

We conducted qualitative interviews with 48 female sex workers (FSW) recruited from entertainment venues in Liuzhou, China. Analyses found that HIV knowledge and sexual health seeking strategies differed by size of venue: (1) Women in smaller venues said they douched before/after sex and used condoms with all but their regular partners and clients. Most found the brochures distributed by Chinese CDC workers “irrelevant” or “boring” and relied on friends for health advice. (2) FSW in middle and large venues were less concerned about prevention, claiming their clients were “healthy.” They relied more on the Internet for health information and were less concerned about the cost of seeing a doctor. (3) Pregnancies and abortions were frequent, especially among the younger women in large venues. This research documents the need to develop tailored HIV-related messages and prevention strategies with the help of FSW to address differences among FSW working in venues of different sizes. PMID:23612941

Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

DTIC Science & Technology

2011-01-01

tool material (AISI H13 tool steel ) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process...threads/m; (b) tool 598 material = AISI H13 tool steel ; (c) workpiece material = 599 AA5059; (d) tool rotation speed = 500 rpm; (e) tool travel 600 speed...the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13

Modeling of AA5083 Material-Microstructure Evolution During Butt Friction-Stir Welding

DTIC Science & Technology

2010-07-01

a rigid material. Its density and thermal properties are set to that of AISI- H13 , the hot-worked tool steel which is often used as a FSW- tool ...joining process (Ref 1-3). Within FSW, a (typically) cylindrical tool - pin (threaded at the bottom and terminated with a circular-plate shape shoulder...applied to the shoulder and owing to frictional sliding and plastic deforma- tion, substantial amount of heat is generated at the tool /work- piece

Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

NASA Astrophysics Data System (ADS)

Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

2016-08-01

Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

Loading Considerations for Implementing Friction STIR Welding for Large Diameter Tank Fabrication

NASA Technical Reports Server (NTRS)

Adams, Glynn

1998-01-01

The main objectives of the research presented here are to determine the reaction loads associated with friction stir welding (FSW) and to determine the suitability of an existing welding fixture for implementing this welding process in the fabrication of large diameter tanks. Friction stir welding is a relatively new process which is being investigated as a method for joining aluminum alloys. The aluminum-lithium alloy, Al-Li 2195, which is being used to fabricate the super-light-weight shuttle external tank has proven difficult to join using fusion techniques. Therefore, FSW and its potential applicability to joining Al-Li 2195 are of particular interest to NASA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paillard, Pascal

Two try-out campaigns of friction stir welding (FSW) were performed with different friction parameters to join S690QL high yield strength steel. The welds were investigated at macroscopic and microscopic scales using optical and electronic microscopy and microhardness mapping. Welds of the second campaign exhibit microstructures and mechanical properties in accordance with requirements for service use. Microtexture measurements were carried out in different zones of welds by electron backscattered diffraction (EBSD). It is shown that that texture of the bottom of the weld is similar to that of the base metal, suggesting a diffusion bonding mechanism. Finally, the mechanical properties (tensilemore » strength, resilience, bending) were established on the most promising welds. It is shown that it is possible to weld this high yield strength steel using FSW process with satisfactory geometric, microstructural and mechanical properties. - Highlights: •1000 mm ∗ 400 mm ∗ 8 mm S690QL steel plates are joined by friction stir welding (FSW). •Maximum hardness is reduced by optimization of process parameters. •Various microstructures are formed but no martensite after process optimization. •Texture is modified in mechanically affected zones of the weld. •Texture in the bottom of the weld is preserved, suggesting diffusion bonding.« less

Phased Array Ultrasound: Initial Development of PAUT Inspection of Self-Reacting Friction Stir Welds

NASA Technical Reports Server (NTRS)

Rairigh, Ryan

2008-01-01

This slide presentation reviews the development of Phased Array Ultrasound (PAUT) as a non-destructive examination method for Self Reacting Friction Stir Welds (SR-FSW). PAUT is the only NDE method which has been shown to detect detrimental levels of Residual Oxide Defect (ROD), which can result in significant decrease in weld strength. The presentation reviews the PAUT process, and shows the results in comparison with x-ray radiography.

Sexually transmissible infections among female sex workers: an international review with an emphasis on hard-to-access populations.

PubMed

Cwikel, Julie G; Lazer, Tal; Press, Fernanda; Lazer, Simcha

2008-03-01

Women who work commercially in sex work (female sex workers [FSW]) are considered a high-risk group for sexually transmissible infections (STI), yet the level of reported pathogens varies in studies around the world. This study reviewed STI rates reported in 42 studies of FSW around the world published between 1995 and 2006 and analysed the trends and types of populations surveyed, emphasising difficult to access FSW populations. Studies were retrieved by PUBMED and other search engines and were included if two or more pathogens were studied and valid laboratory methods were reported. The five most commonly assessed pathogens were Neisseria gonorrhea (prevalence 0.5-41.3), Chlamydia trachomatis (0.61-46.2), Treponema pallidum (syphilis; 1.5-60.5), HIV (0-76.6), and Trichomonas vaginalis (trichomoniasis; 0.11-51.0). Neisseria gonorrhea and C. trachomatis were the most commonly tested pathogens and high prevalence levels were found in diverse areas of the world. HIV was highly prevalent mostly in African countries. Although human papillomavirus infection was surveyed in few studies, prevalence rates were very high and its aetiological role in cervical cancer warrant its inclusion in future FSW monitoring. Hard-to-access FSW groups tended to have higher rates of STI. The five most commonly detected pathogens correspond to those that are highly prevalent in the general population, however there is an urgent need to develop rapid testing diagnostics for all five pathogens to increase prevention and treatment, especially in outreach programs to the most vulnerable groups among FSW.

Sexual risk behaviours, HIV and other sexually transmitted infections among female sex workers in Indonesia.

PubMed

Magnani, Robert; Riono, Pandu; Nurhayati; Saputro, Eko; Mustikawati, Dyah; Anartati, Atiek; Prabawanti, Ciptasari; Majid, Nurholis; Morineau, Guy

2010-10-01

To assess the HIV/AIDS epidemic situation among female sex workers (FSW) in Indonesia using data from the 2007 Integrated Biological-Behavioural Surveillance (IBBS). Behavioural data were collected from time-location samples of 5947 FSW in 10 cities in late 2007. HIV, syphilis, gonorrhoea and chlamydia test results were obtained for 4396, 4324, 3291 and 3316 FSW, respectively. Trends in HIV prevalence were assessed via linkage with sentinel surveillance data. Factors associated with HIV, gonorrhoea and chlamydia infection were assessed using multivariable logistic regression. HIV prevalence averaged 10.5% among direct and 4.9% among indirect FSW, and had increased steadily among direct FSW from 2002 to 2007. Prevalence of chlamydia, gonorrhoea and active syphilis averaged 35.6%, 31.8% and 7.3%, respectively, among direct FSW, and 28.7%, 14.3% and 3.5% among indirect FSW. Being a direct FSW, younger age and having current infection with syphilis and gonorrhoea and/or chlamydia were associated with a higher likelihood of HIV infection. Number of clients in the past week and consumption of alcohol before having sex were associated with a higher likelihood of gonorrhoea and/or chlamydia infection, while having received a STI clinic check-up in the previous 3 months and/or periodic presumptive treatment for sexually transmitted infections (STIs) in the past 6 months were associated with reduced likelihood of infection. The HIV/AIDS epidemic among FSW in Indonesia appears to be expanding, albeit unevenly across provinces and types of FSW. High STI prevalence is conducive to further expansion, but recent efforts to strengthen STI control appear promising.

Why female sex workers participate in HIV research: the illusion of voluntariness.

PubMed

Reed, Elizabeth; Fisher, Celia B; Blankenship, Kim M; West, Brooke S; Khoshnood, Kaveh

2017-07-01

The purpose of this study was to examine factors influencing the motivation for and perceived voluntariness of participation in non-intervention HIV research among female sex workers (FSW) in India. FSW (n = 30) who participated in non-intervention HIV studies in the previous three years were recruited from a local community-based organization. Semi-structured qualitative interviews focused on women's personal and economic motivations for participation and their perceptions of the informed consent process. Interviews were audio-recorded, translated, transcribed, and reviewed for common themes. Content analysis indicated that while many women reported willing participation, reports of obligatory participation were also a common theme. Obligations included money-related pressures and coercion by other FSW, social pressures, not wanting to disappoint the researchers, and perceiving that they had a contractual agreement to complete participation as a result of signing the consent form. Findings suggest a need for additional efforts during and following informed consent to prevent obligatory participation in HIV research studies among FSW. Findings emphasize the importance of integrating ongoing participant feedback into research ethics practices to identify issues not well addressed via standard ethics protocols when conducting HIV research among vulnerable populations.

Nugget Structure Evolution with Rotation Speed for High-Rotation-Speed Friction-Stir-Welded 6061 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Wang, M.; Zhu, Z.; Zhang, X.; Yu, T.; Wu, Z. Q.

2018-03-01

High-rotation-speed friction stir welding (HRS-FSW) is a promising technique to reduce the welding loads during FSW and thus facilitates the application of FSW for in situ fabrication and repair. In this study, 6061 aluminum alloy was friction stir welded at high-rotation speeds ranging from 3000 to 7000 rpm at a fixed welding speed of 50 mm/min, and the effects of rotation speed on the nugget zone macro- and microstructures were investigated in detail in order to illuminate the process features. Temperature measurements during HRS-FSW indicated that the peak temperature did not increase consistently with rotation speed; instead, it dropped remarkably at 5000 rpm because of the lowering of material shear stress. The nugget size first increased with rotation speed until 5000 rpm and then decreased due to the change of the dominant tool/workpiece contact condition from sticking to sliding. At the rotation speed of 5000 rpm, where the weld material experienced weaker thermal effect and higher-strain-rate plastic deformation, the nugget exhibited relatively small grain size, large textural intensity, and high dislocation density. Consequently, the joint showed superior nugget hardness and simultaneously a slightly low tensile ductility.

The organization of sex work in low and high-priced venues with a focus on the experiences of ethnic minority women working in these venues

PubMed Central

Qian, Liu; Zhuang, Kongshao; Henderson, Gail E.; Shenglong, Quzhen; Fang, Jingwen; Yao, Huiqin; Qin, Jingxin; Yang, Yanzhen; Abler, Laurie

2013-01-01

Prior research on female sex workers (FSW) in China, and their risk for HIV and STI, neglects the nuanced experiences of ethnic minority FSW. We conducted participant observations and in-depth interviews with 33 FSW and six venue bosses to describe the experiences of FSW and management structures in high and low-priced sex work venues in Liuzhou, China. In low-priced venues, FSW had more autonomy and stronger relationships with their ethnic minority peers. Mid and high-priced venues had more formal management structures. Ethnic minority FSW working in higher priced venues experienced less support and kinship with their peers. HIV/STI prevention outreach activities occurred in all of the venues, but they were not tailored for different venue types or for ethnic minority FSW. Our findings provide guidance for tailoring public health programs that meet the needs of ethnic minority women working in different types of sex work venues. PMID:23912337

The organization of sex work in low- and high-priced venues with a focus on the experiences of ethnic minority women working in these venues.

PubMed

Liu, Qian; Zhuang, Kongshao; Henderson, Gail E; Shenglong, Quzhen; Fang, Jingwen; Yao, Huiqin; Qin, Jingxin; Yang, Yanzhen; Abler, Laurie

2014-02-01

Prior research on female sex workers (FSW) in China, and their risk for HIV and STI, neglects the nuanced experiences of ethnic minority FSW. We conducted participant observations and in-depth interviews with 33 FSW and six venue bosses to describe the experiences of FSW and management structures in low and high-priced sex work venues in Liuzhou, China. In low-priced venues, FSW had more autonomy and stronger relationships with their ethnic minority peers. Mid- and high-priced venues had more formal management structures. Ethnic minority FSW working in higher priced venues experienced less support and kinship with their peers. HIV/STI prevention outreach activities occurred in all of the venues, but they were not tailored for different venue types or for ethnic minority FSW. Our findings provide guidance for tailoring public health programs that meet the needs of ethnic minority women working in different types of sex work venues.

Prevalence and correlates of probable depression and post-traumatic stress disorder among female sex workers in Lilongwe, Malawi.

PubMed

MacLean, Sarah A; Lancaster, Kathryn E; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C; Pence, Brian W; Gaynes, Bradley N; Hoffman, Irving F; Miller, William C

2018-02-01

Globally, female sex workers (FSW) experience a high prevalence of mental health disorders, but in sub-Saharan Africa these are rarely identified. If left untreated, mental health disorders may place FSW and their partners at risk for HIV/sexually transmitted infections (STIs). We assessed the prevalence and correlates of probable depression, post-traumatic stress disorder (PTSD), and suicidal ideation (SI) in a cohort of 200 FSW in Lilongwe, Malawi. FSW completed the Patient Health Questionnaire-9 and the PTSD Check List-Civilian Version. The prevalence of depression was 8%, as was the prevalence of PTSD. Nearly half (49%) of FSW were experiencing mild depression. FSW were more likely to have probable depression if they completed primary school or initiated sex work before 18 years. They were more likely to have probable PTSD if they had ≥ 20 clients per week or initiated sex work before 18 years. Interventions are needed to diagnose mental health disorders among FSW at great risk for HIV/STIs.

Development of Inspection for Friction Stir Welds for Rocket Fuel Tanks

NASA Technical Reports Server (NTRS)

Russell, Samuel S.

2012-01-01

During development of the Ares I weld processes nondestructive and destructive testing were used to identify and characterize defects that occurred. These defects were named and character noted. This catalogue of defects and characteristics was then used to develop inspection methods for Self Reacting Friction Stir Welds (SR ]FSW) and Conventional Friction Stir Welds (C ]FSW). Dye penetrant, eddy current, x ]radiography, single element ultrasonic, and phased array ultrasonic (PAUT) inspection procedures were developed to target the expected defects. Once the method procedure was developed a comparison was performed to allow for selection of the best inspection method. Tests of the effectiveness of the inspection were performed on purposely fabricated flawed specimens and electrodischarge machined notches. The initial test results prompted a revisit of the PAUT procedure and a redesign of the inspection. Subsequent testing showed that a multi ]angle PAUT inspection resulted in better detection capability. A discussion of the most effective orientations of the PAUT transducer will be presented. Also, the implementation of the inspection on production hardware will be presented. In some cases the weld tool is used as the transducer manipulator and in some cases a portable scanner is used

Advances in Solid State Joining of High Temperature Alloys

NASA Technical Reports Server (NTRS)

Ding, Jeff; Schneider, Judy

2011-01-01

Many of the metals used in the oil and gas industry are difficult to fusion weld including Titanium and its alloys. Solid state joining processes are being pursued as an alternative process to produce robust structures more amenable to high pressure applications. Various solid state joining processes include friction stir welding (FSW) and a patented modification termed thermal stir welding (TSW). The configuration of TSWing utilizes an induction coil to preheat the material minimizing the burden on the weld tool extending its life. This provides the ability to precisely select and control the temperature to avoid detrimental changes to the microstructure. The work presented in this presentation investigates the feasibility of joining various titanium alloys using the solid state welding processes of FSW and TSW. Process descriptions and attributes of each weld process will be presented. Weld process set ]up and welding techniques will be discussed leading to the challenges experienced. Mechanical property data will also be presented.

NASA Operational Simulator for Small Satellites: Tools for Software Based Validation and Verification of Small Satellites

NASA Technical Reports Server (NTRS)

Grubb, Matt

2016-01-01

The NASA Operational Simulator for Small Satellites (NOS3) is a suite of tools to aid in areas such as software development, integration test (IT), mission operations training, verification and validation (VV), and software systems check-out. NOS3 provides a software development environment, a multi-target build system, an operator interface-ground station, dynamics and environment simulations, and software-based hardware models. NOS3 enables the development of flight software (FSW) early in the project life cycle, when access to hardware is typically not available. For small satellites there are extensive lead times on many of the commercial-off-the-shelf (COTS) components as well as limited funding for engineering test units (ETU). Considering the difficulty of providing a hardware test-bed to each developer tester, hardware models are modeled based upon characteristic data or manufacturers data sheets for each individual component. The fidelity of each hardware models is such that FSW executes unaware that physical hardware is not present. This allows binaries to be compiled for both the simulation environment, and the flight computer, without changing the FSW source code. For hardware models that provide data dependent on the environment, such as a GPS receiver or magnetometer, an open-source tool from NASA GSFC (42 Spacecraft Simulation) is used to provide the necessary data. The underlying infrastructure used to transfer messages between FSW and the hardware models can also be used to monitor, intercept, and inject messages, which has proven to be beneficial for VV of larger missions such as James Webb Space Telescope (JWST). As hardware is procured, drivers can be added to the environment to enable hardware-in-the-loop (HWIL) testing. When strict time synchronization is not vital, any number of combinations of hardware components and software-based models can be tested. The open-source operator interface used in NOS3 is COSMOS from Ball Aerospace. For testing, plug-ins are implemented in COSMOS to control the NOS3 simulations, while the command and telemetry tools available in COSMOS are used to communicate with FSW. NOS3 is actively being used for FSW development and component testing of the Simulation-to-Flight 1 (STF-1) CubeSat. As NOS3 matures, hardware models have been added for common CubeSat components such as Novatel GPS receivers, ClydeSpace electrical power systems and batteries, ISISpace antenna systems, etc. In the future, NASA IVV plans to distribute NOS3 to other CubeSat developers and release the suite to the open-source community.

Effect of tool rotation speed on microstructure and tensile properties of FSW joints of 2024-T351 and 7075-T651 reinforced with SiC nano particle: The role of FSW single pass

NASA Astrophysics Data System (ADS)

Kumar, K. S. Anil; Murigendrappa, S. M.; Kumar, Hemantha; Shekhar, Himanshu

2018-04-01

Friction stir welding (FSW) dissimilar joints of aluminium alloys of 2024-T351 and 7075-T651 were produced by reinforcing silicon carbide nano particle (SiCNP) in the rectangular cut groove made on the adjoining surface of the two dissimilar alloy plates joined in the butt configuration. A FSW tool of taper threaded cylindrical shape is used for producing the FSW dissimilar joints reinforced with SiCNP in the weld nugget zone (WNZ) and to produce metal matrix nano composite (MMNC) at the WNZ. In the experimental investigation, the constant FSW tool traverse speed of 40 mm/min and tool plunge depth of 6.2 mm/min is kept as constant, while the FSW tool rotation speed was varied from 400 rpm to 1800 rpm. The effect continuous varying tool rotation speed range from 400 rpm to 1800 rpm along the weld length and on the distribution of SiCNP in WNZ is analysed by conducting macro and microstructure study using optical microscopy (OM) and scanning electron microscopy (SEM) provided with energy dispersive spectrometry (EDS). In the experimental investigation, the combination of continuous varying FSW tool rotation speed range from 900rpm to 1150 rpm, constant tool traverse speed range 40 mm/min and tool plunge depth of 6.2 mm results in defect free, proper distribution of SiCNP and highest tensile properties for the FSW dissimilar joints. The highest ultimate tensile strength (UTS) of 380 MPa and yield strength (YS) of 150 MPa was observed for the combination of FSW tool rotation speed of 1000 rpm and tool traverse speed of 40 mm/min. The increasing in FSW tool rotation speed above 1250 rpm results in non homogeneous distribution of SiCNP in WNZ, excessive flash in the weld crown area and shows decreasing tendency in the tensile properties of the FSW dissimilar weld joints produced with reinforcing the SiCNP in the WNZ.

Estimates of the number of female sex workers in different regions of the world

PubMed Central

Vandepitte, J; Lyerla, R; Dallabetta, G; Crabbé, F; Alary, M; Buvé, A

2006-01-01

Objectives To collect estimated numbers of female sex workers (FSW) and present proportions of FSW in the female population (FSW prevalence) in different regions of the world. Methods Subnational and national estimated numbers of FSW reported in published and unpublished literature, as well as from field investigators involved in research or interventions targeted at FSW, were collected. The proportion of FSW in the adult female population was calculated. Subnational estimates were extrapolated to national estimates if appropriate. Population surveys were scanned for proportions of adult women having sex in exchange for money or goods. Results In sub‐Saharan Africa, the FSW prevalence in the capitals ranged between 0.7% and 4.3% and in other urban areas between 0.4% and 4.3%. Population surveys from this same region yielded even higher proportions of women involved in transactional sex. The national FSW prevalence in Asia ranged between 0.2% and 2.6%; in the ex‐Russian Federation between 0.1% and 1.5%; in East Europe between 0.4% and 1.4%; in West Europe between 0.1% and 1.4%; and in Latin America between 0.2% and 7.4%. Estimates from rural areas were only available from one country. Conclusions Although it is well known and accepted that FSW are a highly vulnerable group in the scope of the HIV epidemic, most countries in the world do not know the size of this population group. The estimates of the prevalence of FSW presented in this paper show how important this hard‐to‐reach population group is in all parts of the world. PMID:16735288

Determinants of HIV prevalence among female sex workers in four south Indian states: analysis of cross-sectional surveys in twenty-three districts.

PubMed

Ramesh, Banadakoppa M; Moses, Stephen; Washington, Reynold; Isac, Shajy; Mohapatra, Bidhubhushan; Mahagaonkar, Sangameshwar B; Adhikary, Rajatashuvra; Brahmam, Ginnela N V; Paranjape, Ramesh S; Subramanian, Thilakavathi; Blanchard, James F

2008-12-01

In four states in southern India we explored the determinants of HIV prevalence among female sex workers (FSW), as well as factors associated with district-level variations in HIV prevalence among FSW. Data from cross-sectional surveys in 23 districts were analysed, with HIV prevalence as the outcome variable, and sociodemographic and sex work characteristics as predictor variables. Multilevel logistic regression was applied to identify factors that could explain variations in HIV prevalence among districts. HIV prevalence among the 10 096 FSW surveyed was 14.5% (95% confidence interval 14.0-15.4), with a large interdistrict variation, ranging from 2% to 38%. Current marital status and the usual place of solicitation emerged as important factors that determine individual probability of being HIV positive, as well as the HIV prevalence within districts. In multivariate analysis, compared with home-based FSW, the odds of being HIV positive was greater for brothel-based FSW [adjusted odds ratio (AOR) 2.17, P

Analysis and design of friction stir welding tool

NASA Astrophysics Data System (ADS)

Jagadeesha, C. B.

2016-12-01

Since its inception no one has done analysis and design of FSW tool. Initial dimensions of FSW tool are decided by educated guess. Optimum stresses on tool pin have been determined at optimized parameters for bead on plate welding on AZ31B-O Mg alloy plate. Fatigue analysis showed that the chosen FSW tool for the welding experiment has not ∞ life and it has determined that the life of FSW tool is 2.66×105 cycles or revolutions. So one can conclude that any arbitrarily decided FSW tool generally has finite life and cannot be used for ∞ life. In general, one can determine the suitability of tool and its material to be used in FSW of the given workpiece materials in advance by this analysis in terms of fatigue life of the tool.

Levels of advertised unprotected vaginal and oral sex by independent indoor female sex workers in West Yorkshire, UK.

PubMed

Eccles, Claire; Clarke, Janette

2014-02-01

To assess the proportion of independent indoor female sex workers (FSW) in West Yorkshire, UK who advertise unprotected sex, and to investigate any association with cost, location and provision of anal sex. Data on whether independent indoor FSW (defined as those not advertising via an escort agency or through a parlour) advertised unprotected sexual services, along with demographic data, were collected from 462 advertisement profiles of FSW in West Yorkshire from the website http://www.adultwork.com. Independent t test and χ(2) statistics were used to test the association between advertised unprotected vaginal and oral sex, and FSW age, cost of services, location and whether they advertised anal sex. Unprotected vaginal sex was advertised by 8% of FSW, and unprotected oral sex by 74% of FSW. FSW advertising unprotected vaginal sex were more likely to live in Wakefield and Bradford than in Leeds, had significantly lower hourly rates, and were more likely to advertise anal sex. Advertised condom use for vaginal and oral sex by independent indoor FSW in West Yorkshire was significantly lower than reported rates of protected sex found in previous studies based in London and the south of England. The advertisement of unprotected vaginal sex is associated with factors such as lower hourly rates and the advertisement of higher risk anal sex, which may signify greater economic need. FSW offering unprotected sex therefore represent an at-risk target group for health promotion.

Effects of Different R ratios on Fatigue Crack Growth in Laser Peened Friction Stir Welds

NASA Technical Reports Server (NTRS)

Hatamleh, Omar; Hackel, Lloyd; Forth, Scott

2007-01-01

The influence of laser peening on the fatigue crack growth behavior of friction stir welded (FSW) Aluminum Alloy (AA) 7075-T7351 sheets was investigated. The surface modification resulting from the peening process on the fatigue crack growth of FSW was assessed for two different R ratios. The investigation indicated a significant decrease in fatigue crack growth rates resulting from using laser shock peening compared with unpeened, welded and unwelded specimens. The slower fatigue crack growth rate was attributed to the compressive residual stresses induced by the peening.

Speech intelligibility at high helium-oxygen pressures.

PubMed

Rothman, H B; Gelfand, R; Hollien, H; Lambertsen, C J

1980-12-01

Word-list intelligibility scores of unprocessed speech (mean of 4 subjects) were recorded in helium-oxygen atmospheres at stable pressures equivalent to 1600, 1400, 1200, 1000, 860, 690, 560, 392, and 200 fsw daring Predictive Studies IV-1975 by wide-bandwidth condenser microphones (frequency responses not degraded by increased gas density). Intelligibility scores were substantially lower in helium-oxygen a 200 fsw than in air at l ATA, but there was little difference between 200 fsw and 1600 fsw. A previously documented prominent decrease in intelligibility of speech between 200 or 600 fsw because of helium and pressure was probably due to degradation of microphone frequency response by high gas density.

29 CFR 1910.427 - Liveboating.

Code of Federal Regulations, 2011 CFR

2011-07-01

... deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw; (3) Using mixed gas at depths greater than 220 fsw; (4) In rough seas which significantly...

Advanced Metalworking Solutions for Naval Systems that go in Harm’s Way

DTIC Science & Technology

2009-01-01

friction stir welding (FSW) and advanced machining and casting techniques to produce a prototype Automated weld seam facing on DDG 1000 ships will...transportable friction stir welding (FSW) machine. FSW is a solid state joining technology that offers benefits over traditional welding for several...addition, by locating FSW operation at the construction yard, the aluminum panels that will be friction stir - welded are built to the size needed instead

Sexual behavior of female sex workers and access to condoms in Kenya and Uganda on the Trans-Africa highway.

PubMed

Morris, Chester N; Morris, Sheldon R; Ferguson, Alan G

2009-10-01

Female sex workers and their clients remain a high risk core group for HIV in Africa. We measured sexual behavior of a snowball sample of female sex workers (FSW) along the Trans Africa highway from Mombasa, Kenya to Kampala, Uganda and surveyed the availability of male condoms at 1,007 bars and lodgings in Kenya along the highway trucking stops where transactional sex occurs. There were 578 FSW one month sex diaries analyzed, 403 from Kenya and 175 from Uganda. Kenyan FSW had a median of 45 sexual acts per 28 days compared to 39 sex acts per 28 days by Ugandan FSW (P < 0.05). Condom use by FSW for all sexual liaisons was 79% in Kenya compared to 74% in Uganda. In multivariate analysis, adjusting for repeated measures, Kenyan FSW were more likely to use a condom by an adjusted odds ratio of 2.54 (95% confidence interval 1.89-3.41) compared to Ugandan FSW. Condom use with regular clients was 50.8% in Uganda compared with 68.7% in Kenya (P < 0.01). The number of sex workers reporting 100% condom use was 26.8% in Kenya and 18.9% in Uganda (P < 0.01). Bars and lodges in Kenya compared to Uganda were more likely to: have condom dispensers, 25% versus 1%, respectively (P < 0.01); distribute or sell condoms, 73.9% versus 47.6% (P < 0.01); and have more weekly condom distribution, 4.92 versus 1.27 condoms per seating capacity (P < 0.01). Our data indicate that in both countries condom use for FSW is suboptimal, particularly with regular partners, and greater condom use by Trans African highway FSW in Kenya compared to Uganda may be related to availability. Targeted interventions are warranted for FSW and truck drivers to prevent transmission in this important core group.

U.S. Drug Use and Migration experiences of Mexican Female Sex Workers who are injection Drug Users

PubMed Central

Ojeda, Victoria D.; Burgos, José Luis; Rangel, María Gudelia; Lozada, Remedios; Vera, Alicia

2013-01-01

Objective To describe U.S.-based drug/sex behaviors and correlates of lifetime U.S. drug use by Mexican female sex workers who inject drugs (FSW-IDUs). Methods Between 2008–2010, 315 migrant FSW-IDUs residing in Tijuana and Ciudad Juarez, Mexico responded to questionnaires. Results Twenty-seven percent (n=85) of FSW-IDUs were U.S. migrants; of these, 46% (n=39) were deportees. One-half of U.S.-migrant FSW-IDUs consumed illicit drugs in the U.S., and two-thirds of these injected drugs in the U.S. Among U.S. injectors, over 75% ever received or shared used injection equipment. The majority (92%) of U.S.-migrant FSW-IDUs never obtained U.S. drug treatment services. HIV prevalence was 4% among U.S.-migrant and 5% among non-U.S. migrant FSW-IDUs; 100% of U.S.-migrant and 75% of non-U.S. migrant FSW-IDUs were unaware of their HIV status. Conclusions Binational coordination to improve access to substance use treatment and HIV testing services in Mexico and the U.S. among marginalized binational migrants may be critical to containing HIV transmission. PMID:23698687

U.S. drug use and migration experiences of Mexican female sex workers who are injection drug users.

PubMed

Ojeda, Victoria D; Burgos, José Luis; Rangel, A Gudelia; Lozada, Remedios; Vera, Alicia

2012-11-01

To describe U.S.-based drug/sex behaviors and correlates of lifetime U.S. drug use by Mexican female sex workers who inject drugs (FSW-IDUs). Between 2008-2010, 315 migrant FSW-IDUs residing in Tijuana and Ciudad Juarez, Mexico responded to questionnaires. Twenty-seven percent (n=85) of FSW-IDUs were U.S. migrants; of these, 46% (n=39) were deportees. One-half of U.S.-migrant FSW-IDUs consumed illicit drugs in the U.S., and two-thirds of these injected drugs in the U.S. Among U.S. injectors, over 75% ever received or shared used injection equipment. The majority (92%) of U.S.-migrant FSW-IDUs never obtained U.S. drug treatment services. HIV prevalence was 4% among U.S.-migrant and 5% among non-U.S. migrant FSW-IDUs; 100% of U.S.-migrant and 75% of non-U.S. migrant FSW-IDUs were unaware of their HIV status. Binational coordination to improve access to substance use treatment and HIV testing services in Mexico and the U.S. among marginalized binational migrants may be critical to containing HIV transmission.

Correlates of HIV infection among female sex workers in Vietnam: injection drug use remains a key risk factor.

PubMed

Le, Linh-Vi N; Nguyen, Tuan A; Tran, Hoang V; Gupta, Nisha; Duong, Thanh C; Tran, Ha T T; Nadol, Patrick; Sabin, Keith; Maher, Lisa; Kaldor, John M

2015-05-01

Women who sell sex and use drugs have dual risks for HIV infection. Despite increasing reports of drug use among female sex workers (FSW) in Vietnam, FSW HIV interventions remain focused mainly on sexual risk reduction. We assessed the impact of drug use and inconsistent condom use on HIV infection among FSW in Vietnam, which few studies have quantified. We surveyed 5298 women aged ≥18 years who had sold sex in the past month from ten geographically dispersed provinces. We performed multivariate logistic regression on data from provinces with high (≥10%) or low (<10%) HIV prevalence among FSW. Compared to FSW who never used illicit drugs, the odds of HIV infection among FSW who had ever injected drugs and those who reported non-injection drug use were 3.44 (CI 2.32-5.09) and 1.76 (CI 1.14-2.71), respectively, in high-prevalence provinces. FSW who always used condoms with clients had lower odds of HIV infection than those who did not (AOR=0.71; CI 0.52-0.98). In low-prevalence provinces lifetime injection drug use (AOR 22.05, CI 12.00-40.49), but not non-injecting drug use or inconsistent condom use, was significantly associated with HIV infection. Because injection drug use and inconsistent condom use were key risk factors for HIV infection in high-prevalence provinces, drug injection risk reduction should be as much a focus of HIV prevention as sexual risk reduction. Where HIV prevalence remains low in FSW, a more general emphasis on harm reduction for all drug users will benefit FSW. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mental Health and Functioning of Female Sex Workers in Chittagong, Bangladesh.

PubMed

Hengartner, Michael P; Islam, Md Nazrul; Haker, Helene; Rössler, Wulf

2015-01-01

To examine the mental health and functioning of female sex workers (FSW) in Chittagong, Bangladesh, a population that has commonly been neglected in mental health policy and research. We included 259 women in the study (M age: 23.2 years; range: 11-48). The comprehensive Composite International Diagnostic Interview was used to assess their 12-month prevalence rates of DSM-IV mental disorders, and a comprehensive questionnaire was adapted to explore various factors, such as socio-demographics, working and living conditions, or experiences of abuse. On average, participants began their commercial sex work at 18.5 years old (range: 10-45). Their main motives for sex work were coercion (49.4%) and the necessity to financially support families (54.8%). In total, 224 FSW (86.5%) wanted to quit commercial sex work. A mental disorder within the past 12 months was reported by 100 FSW (38.6%), with drug abuse clearly being the most prevalent diagnosis (15.4%). Sexual, physical, and emotional abuse were very common among the FSW, and substance use disorders (SUD) were significantly more prevalent in persons who experienced emotional abuse (OR = 2.2). Prevalence rates of any mental disorder and SUD were higher in women who did sex work to support their family, whereas mood disorders were more frequent in those who needed the money to pay debts. Participants with any disorder were significantly older than those without (M age: 24.4 vs. 22.5 years) and had started significantly later in the sex business (M age: 19.7 vs. 17.7 years). Our study revealed that FSW in Chittagong are very vulnerable and highly impaired, as expressed by high rates of abuse and mental disorders. Coercion is very common and many FSW are required to work in the sex business because they need the money to support their families. FSW are a very marginalized population, especially in the developing countries where awareness for mental health is low and the availability of mental health services is insufficient.

Microstructure Stability During Creep of Friction Stir Welded AA2024-T3 Alloy

NASA Astrophysics Data System (ADS)

Regev, Michael; Rashkovsky, Tal; Cabibbo, Marcello; Spigarelli, Stefano

2018-01-01

The poor weldability of the AA2024 aluminum alloy limits its use in industrial applications. Because friction stir welding (FSW) is a non-fusion welding process, it seems to be a promising solution for welding this alloy. In the current study, FSW was applied to butt weld AA2024-T3 aluminum alloy plates. Creep tests were conducted at 250 and at 315 °C on both the parent material and the friction stir welded specimens. The microstructures of the welded and non-welded AA2024-T3 specimens before and after the creep tests were studied and compared. A comprehensive transmission electron microscopy study together with a high-resolution scanning electron microscopy study and energy-dispersive x-ray spectroscopy analysis was conducted to investigate the microstructure stability. The parent material seems to contain two kinds of Cu-rich precipitates—coarse precipitates of a few microns each and uniformly dispersed fine nanosized precipitates. Unlike the parent material, the crept specimens were found to contain the two kinds of precipitates mentioned above together with platelet-like precipitates. In addition, extensive decoration of the grain boundaries with precipitates was clearly observed in the crept specimens. Controlled aging experiments for up to 280 h at the relevant temperatures were conducted on both the parent material and the welded specimens in order to isolate the contribution of exposure to high temperatures to the microstructure changes. TEM study showed the development of dislocation networks into a cellular dislocation structure in the case of the parent metal. Changes in the dislocation structure as a function of the creep strain and the FSW process were recorded. A detailed creep data analysis was conducted, taking into account the instability of the microstructure.

Socio-demographic, Behavioral and Health Characteristics of Underage Female Sex Workers in Mozambique: The Need to Protect a Generation from HIV Risk.

PubMed

Inguane, Celso; Horth, Roberta Z; Miranda, Angélica E; Young, Peter W; Sathane, Isabel; Cummings, Beverley E; Augusto, Ângelo; Raymond, Henry F; Mcfarland, Willi

2015-12-01

Characteristics, HIV risk, and program coverage for underage female sex workers (FSW) are rarely systematically described worldwide. We compared characteristics of underage (15-17 years old) and adult (≥18 years old) FSW in three main urban areas of Mozambique (Maputo, Beira and Nampula) using data from three respondent-driven sampling surveys implemented in 2011-2012. Among survey participants, 9.8 % (39/400) in Maputo, 17.0 % (70/411) in Beira and 25.6 % (110/429) in Nampula were underage. Over half reported performing sex work to afford daily living, and 29.7-50.0 % had unprotected sex with their last client. The proportion of underage FSW having accessed care and prevention services was lower compared to adult FSW. While HIV prevalence among underage FSW was lower than in adults, it increased markedly with age. Our results point to the urgency of expanding prevention and care programs geared towards underage FSW.

Socio-demographic, Behavioral and Health Characteristics of Underage Female Sex Workers in Mozambique: The Need to Protect a Generation from HIV Risk

PubMed Central

Horth, Roberta Z.; Miranda, Angélica E.; Young, Peter W.; Sathane, Isabel; Cummings, Beverley E.; Augusto, Ângelo; Raymond, Henry F.; Mcfarland, Willi

2016-01-01

Characteristics, HIV risk, and program coverage for underage female sex workers (FSW) are rarely systematically described worldwide. We compared characteristics of underage (15–17 years old) and adult (≥18 years old) FSW in three main urban areas of Mozambique (Maputo, Beira and Nampula) using data from three respondent-driven sampling surveys implemented in 2011–2012. Among survey participants, 9.8 % (39/400) in Maputo, 17.0 % (70/411) in Beira and 25.6 % (110/429) in Nampula were underage. Over half reported performing sex work to afford daily living, and 29.7–50.0 % had unprotected sex with their last client. The proportion of underage FSW having accessed care and prevention services was lower compared to adult FSW. While HIV prevalence among underage FSW was lower than in adults, it increased markedly with age. Our results point to the urgency of expanding prevention and care programs geared towards underage FSW. PMID:25931241

Assessing reported condom use among female sex workers in southern India through examination of condom availability.

PubMed

Bradley, Janet; Moses, Stephen; Blanchard, James F; Rajaram, S; Ramesh, B M; Verma, Supriya; Alary, Michel

2010-02-01

A key indicator of success of HIV prevention programmes is the number of female sex worker (FSW) sex acts protected by condoms. This measure usually relies on FSW reports, which may be biased. We examined condom availability data in five Karnataka districts to estimate the proportion of FSW sex acts potentially protected by condoms. Financial, programme, population, condom and contraceptive data were obtained from governmental and non-governmental sources, surveys and HIV prevention programmes. Sexual behaviour data were obtained from general population and FSW surveys. We examined four scenarios in a sensitivity analysis, each one assuming different proportions of available condoms that might have been used by sex workers. Possible condom use rates for all FSW sex acts ranged from 3%-36% in 2004 to 56%-96% in 2008. The two most realistic scenarios that discounted the number of private sector condoms that might have been bought for sex acts other than with FSWs showed that 16-24% of FSW sex acts could have been protected by condoms in 2004 rising to 77-85% in 2008. These data suggest that condom availability in these Karnataka districts in 2004 was low in relation to the number of FSW sex acts, but rose substantially over the ensuing 4 years. Condom availability data can be useful for triangulation with other available data, such as self-reported condom use, to provide a range of possibilities regarding the number of FSW sex acts protected by condoms.

Abriendo Puertas: Feasibility and Effectiveness a Multi-Level Intervention to Improve HIV Outcomes Among Female Sex Workers Living with HIV in the Dominican Republic.

PubMed

Kerrigan, Deanna; Barrington, Clare; Donastorg, Yeycy; Perez, Martha; Galai, Noya

2016-09-01

Female sex workers (FSW) are disproportionately affected by HIV. Yet, few interventions address the needs of FSW living with HIV. We developed a multi-level intervention, Abriendo Puertas (Opening Doors), and assessed its feasibility and effectiveness among a cohort of 250 FSW living with HIV in the Dominican Republic. We conducted socio-behavioral surveys and sexually transmitted infection and viral load testing at baseline and 10-month follow-up. We assessed changes in protected sex and adherence to antiretroviral therapy (ART) with logistic regression using generalized estimating equations. Significant pre-post intervention changes were documented for adherence (72-89 %; p < 0.001) and protected sex (71-81 %; p < 0.002). Higher intervention exposure was significantly associated with changes in adherence (AOR 2.42; 95 % CI 1.23-4.51) and protected sex (AOR 1.76; 95 % CI 1.09-2.84). Illicit drug use was negatively associated with both ART adherence and protected sex. Abriendo Puertas is feasible and effective in improving behavioral HIV outcomes in FSW living with HIV.

Effect of rotation speed and welding speed on Friction Stir Welding of AA1100 Aluminium alloy

NASA Astrophysics Data System (ADS)

Raja, P.; Bojanampati, S.; Karthikeyan, R.; Ganithi, R.

2018-04-01

Aluminum AA1100 is the most widely used grade of Aluminium due to its excellent corrosion resistance, high ductility and reflective finish, the selected material was welded with Friction Stir Welding (FSW) process on a CNC machine, using a combination of different tool rotation speed (1500 rpm, 2500 rpm, 3500 rpm) and welding speed (10 mm/min, 30 mm/min, 50 mm/min) as welding parameters. The effect of FSW using this welding parameter was studied by measuring the ultimate tensile strength of the welded joints. A high-speed steel tool was prepared for welding the Aluminium AA1100 alloy having an 8mm shoulder diameter and pin dimension of 4mm diameter and 2.8 mm length. The welded joints were tested using the universal testing machine. It was found that Ultimate Tensile Strength of FSW specimen was highest with a value of 98.08 MPa when the weld was performed at rotation speed of 1500 RPM and welding speed of 50 mm/min.

Computed Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

2005-01-01

In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and is carried with the macro-flow of the weld metal. By using CT images, a 3-dimensional (3D) image of the lead flow pattern can be reconstructed. CT imaging was found to be a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

Partner Violence and Psychosocial Distress among Female Sex Workers in China

PubMed Central

Hong, Yan; Zhang, Chen; Li, Xiaoming; Liu, Wei; Zhou, Yuejiao

2013-01-01

Background Despite recognized vulnerability of female sex workers (FSW), most data on this population are focused on their HIV and STI prevalence; studies on their experience of partner violence and psychosocial distress are limited, especially FSW in China. Methods and Findings A cross-sectional survey was administered among 1,022 FSW recruited from 9 different types of commercial sex venues in Southwest China. Partner violence scales were adapted from WHO's Women's Health and Domestic Violence scale and psychosocial distress was measured by five indicators, including alcohol intoxication, drug use, suicidal behavior, depression, and loneliness. Random effects modeling was used to control for cluster effects. Findings: About 58% of FSW ever experienced violence from their stable partners, and 45% suffered it from their clients. Partner violence was strongly associated with each of the five measures of psychosocial distress, even after controlling for potential confounders. Conclusion This study is one of the first to examine the association between partner violence and psychosocial distress among FSW in China. The high prevalence of violence experience and distress in this population suggests urgency for intervention. The public health programs targeting FSW should go beyond the focus on HIV/STI prevention and care for the fundamental health and human rights of millions of FSW in China. PMID:23626798

STI Screening Uptake and Knowledge of STI Symptoms among Female Sex Workers Participating in a Community Randomized Trial in Peru

PubMed Central

Kohler, Pamela K.; Campos, Pablo E.; Garcia, Patricia J.; Carcamo, Cesar P.; Buendia, Clara; Hughes, James P.; Mejia, Carolina; Garnett, Geoff P.; King, K.

2016-01-01

This study aims to evaluate condom use, STI screening, and knowledge of STI symptoms among female sex workers (FSW) in Peru associated with sex work venue and a community randomized trial of STI control. One component of the Peru PREVEN intervention conducted mobile-team outreach to FSW to reduce STIs and increase condom use and access to government clinics for STI screening and evaluation. Prevalence ratios were calculated using multivariate Poisson regression models with robust standard errors, clustering by city. As-treated analyses were conducted to assess outcomes associated with reported exposure to the intervention. Care-seeking was more frequent in intervention communities, but differences were not statistically significant. FSW reporting exposure to the intervention had significantly higher likelihood of condom use, STI screening at public health clinics, and symptom recognition compared to those not exposed. Compared with street or bar-based FSW, brothel-based FSW reported significantly higher rates of condom use with last client, recent screening exams for STIs and HIV testing. Brothel-based FSW also more often reported knowledge of STIs and recognition of STI symptoms in women and in men. Interventions to promote STI-detection and prevention among FSW in Peru should consider structural or regulatory factors related to sex work venue. PMID:25941053

Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

NASA Astrophysics Data System (ADS)

Maleki, E.

2015-12-01

Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters.

Physical and Sexual Violence Affecting Female Sex Workers in Abidjan, Côte d'Ivoire: Prevalence, and the Relationship with the Work Environment, HIV, and Access to Health Services.

PubMed

Lyons, Carrie E; Grosso, Ashley; Drame, Fatou M; Ketende, Sosthenes; Diouf, Daouda; Ba, Ibrahima; Shannon, Kate; Ezouatchi, Rebecca; Bamba, Amara; Kouame, Abo; Baral, Stefan

2017-05-01

Violence is a human rights violation, and an important measure in understanding HIV among female sex workers (FSW). However, limited data exist regarding correlates of violence among FSW in Côte d'Ivoire. Characterizing prevalence and determinants of violence and the relationship with structural risks for HIV can inform development and implementation of comprehensive HIV prevention and treatment programs. FSW > 18 years were recruited through respondent driven sampling (RDS) in Abidjan, Côte d'Ivoire. In total, 466 participants completed a socio-behavioral questionnaire and HIV testing. Prevalence estimates of violence were calculated using crude and RDS-adjusted estimates. Relationships between structural risk factors and violence were analyzed using χ tests and multivariable logistic regression. The prevalence of physical violence was 53.6% (250/466), and sexual violence was 43.2% (201/465) among FSW in this study. Police refusal of protection was associated with physical (adjusted Odds Ratio [aOR]: 2.8; 95% confidence interval [CI]: 1.7 to 4.4) and sexual violence (aOR: 3.0; 95% CI: 1.9 to 4.8). Blackmail was associated with physical (aOR: 2.5; 95% CI: 1.5 to 4.2) and sexual violence (aOR: 2.4; 95% CI: 1.5 to 4.0). Physical violence was associated with fear (aOR: 2.2; 95% CI: 1.3 to 3.1) and avoidance of seeking health services (aOR: 2.3; 95% CI: 1.5 to 3.8). Violence is prevalent among FSW in Abidjan and associated with features of the work environment and access to care. These relationships highlight layers of rights violations affecting FSW, underscoring the need for structural interventions and policy reforms to improve work environments, and to address police harassment, stigma, and rights violations to reduce violence and improve access to HIV interventions.

Prevalence of lifetime abortion and methods of contraception among female sex workers in Bogota, Colombia.

PubMed

Bautista, Christian T; Mejía, Alfredo; Leal, Luis; Ayala, Claudia; Sanchez, Jose L; Montano, Silvia M

2008-03-01

The primary objective was to estimate the lifetime prevalence of abortion and the secondary objective was to describe the use of contraceptive methods among female sex workers (FSW) in Bogota, Colombia. A cross-sectional survey was conducted among FSW. Information on sociodemographic characteristics, contraceptive methods, number of abortions, reasons for abortions and sexual practices was collected. A total of 514 FSW were enrolled. Of these, 264 (53%) had a lifetime abortion. Age, years in sex work and a previous sexually transmitted infection were associated with abortion. A total of 89 FSW(17%) reported no contraception method. Oral contraceptives, use of condoms, female sterilization and intrauterine device insertion were the most common methods of contraception. Women who were poorer, who initiated sex work at a younger age and who reported use of illegal drugs were associated with inconsistent contraception. A high lifetime prevalence of abortion and inconsistent contraception was found among FSW in Bogota. There is a need for effective and practical contraceptive methods of family health planning among FSW in Colombia.

Effects of thread interruptions on tool pins in friction stir welding of AA6061

DOE PAGES

Reza-E-Rabby, Md.; Tang, Wei; Reynolds, Anthony P.

2017-06-21

In this paper, effects of pin thread and thread interruptions (flats) on weld quality and process response parameters during friction stir welding (FSW) of 6061 aluminium alloy were quantified. Otherwise, identical smooth and threaded pins with zero to four flats were adopted for FSW. Weldability and process response variables were examined. Results showed that threads with flats significantly improved weld quality and reduced in-plane forces. A three-flat threaded pin led to production of defect-free welds under all examined welding conditions. Spectral analyses of in-plane forces and weld cross-sectional analysis were performed to establish correlation among pin flats, force dynamics andmore » defect formation. Finally, the lowest in-plane force spectra amplitudes were consistently observed for defect-free welds.« less

Effects of thread interruptions on tool pins in friction stir welding of AA6061

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reza-E-Rabby, Md.; Tang, Wei; Reynolds, Anthony P.

In this paper, effects of pin thread and thread interruptions (flats) on weld quality and process response parameters during friction stir welding (FSW) of 6061 aluminium alloy were quantified. Otherwise, identical smooth and threaded pins with zero to four flats were adopted for FSW. Weldability and process response variables were examined. Results showed that threads with flats significantly improved weld quality and reduced in-plane forces. A three-flat threaded pin led to production of defect-free welds under all examined welding conditions. Spectral analyses of in-plane forces and weld cross-sectional analysis were performed to establish correlation among pin flats, force dynamics andmore » defect formation. Finally, the lowest in-plane force spectra amplitudes were consistently observed for defect-free welds.« less

Human papillomavirus infection in female sex workers in Lima, Peru.

PubMed

Montano, Silvia M; Hsieh, Evelyn J; Calderón, Martha; Ton, Thanh G N; Quijano, Eberth; Solari, Vicky; Zunt, Joseph R

2011-02-01

To determine the prevalence and risk factors for human papillomavirus (HPV) infection in female sex workers (FSW) in Lima, Peru. Cross-sectional study of 87 FSW. Information regarding demographics, sex work practices, and genital and blood specimens was collected. Forty-four (50.6%) of 87 FSW had HPV detected in cervical swabs. The prevalence of coinfection by two or more HPV types was 39.1%. Thirty-one (35.6%) were infected by at least one high-risk HPV type, representing 70.5% of women with HPV infection. HPV infection was associated with younger age but not with any demographic or sexual characteristics. Our study confirms the high prevalence of HPV infection in FSW reported by other groups and suggests that brothel-based FSW may be at lower risk for acquiring high-risk HPV infection.

Socioecological Factors Related to Hazardous Alcohol use among Female Sex Workers in Lilongwe, Malawi: A Mixed Methods Study.

PubMed

Lancaster, Kathryn E; MacLean, Sarah A; Lungu, Thandie; Mmodzi, Pearson; Hosseinipour, Mina C; Hershow, Rebecca B; Powers, Kimberly A; Pence, Brian W; Hoffman, Irving F; Miller, William C; Go, Vivian F

2018-04-16

Alcohol use is pervasive among female sex workers (FSW) placing them at increased risk of violence and sexual risk behaviors. FSW often live and work where alcohol is highly normative. To understand the socioecological influences on hazardous alcohol use among FSW in Malawi. In 2014, 200 FSW identified through venue-based sampling in Lilongwe, Malawi, completed a quantitative behavioral survey, with a sub-sample participating in qualitative interviews. Multivariable log-binomial regression was used to identify associations between hazardous alcohol use (AUDIT score ≥ 7) and time in sex work, clients per week, unprotected sex, alcohol use with clients, and living environment. Qualitative interviews enhanced findings from quantitative data and identify emergent themes around socioecological influences on alcohol use. Over 50% reported hazardous alcohol use and lived in an alcohol-serving venue. Hazardous alcohol use was associated with sex work duration of ≥2 years (aPR: 1.30; 95%CI: 1.02,1.65) and alcohol use at last sex with a client (aPR: 1.29; 95%CI: 1.06,1.57). FSW perceived alcohol as a facilitator for sex work by reducing inhibitions and attracting clients, but acknowledged alcohol leads to violence and/or unprotected sex. Despite these risks and a motivation to reduce use, FSW feared that refusing to drink would be tantamount to turning away clients. Although FSW recognized alcohol-related risks, the norms and power dynamics of sex work perpetuated hazardous alcohol use. Multilevel interventions are needed to collectively change norms around drinking and sex work that will enable FSW to reduce alcohol consumption when engaging in their work.

Risk of sexual, physical and verbal assaults on men who have sex with men and female sex workers in coastal Kenya.

PubMed

Micheni, Murugi; Rogers, Sam; Wahome, Elizabeth; Darwinkel, Marianne; van der Elst, Elise; Gichuru, Evans; Graham, Susan M; Sanders, Eduard J; Smith, Adrian D

2015-12-01

Violence toward MSM and female sex workers (FSW) is associated with HIV risk, and its prevention is prioritized in international HIV/AIDS policy. Sociodemographic and behavioural data derived from HIV risk and follow-up cohorts including MSM and FSW in coastal Kenya between 2005 and 2014 was used to estimate the risk of rape, physical assault and verbal abuse, and to assess associations between first occurrence of assault with individual and recent behavioural factors. Incidence of first reported rape was similar for MSM [3.9, confidence interval (CI) 3.1-5.0 per 100 person-years (pyrs)] and FSW (4.8 CI 3.5-6.4 per 100 pyrs), P = 0.22. Incidence of first reported physical and verbal assault was higher for FSW than MSM (21.1 versus 12.9 per 100 pyrs, P = 0.14 and 51.3 versus 30.9 per 100 pyrs, P = 0.03 respectively). Recent alcohol use was associated with reporting of all forms of assault by MSM [adjusted odds ratio (AOR) 1.8, CI 0.9-3.5] and FSW (AOR 4.4, CI 1.41-14.0), as was recent sale of sex for MSM (AOR 2.0, CI 1.1-3.8). Exclusive sex with men, active sex work, and group sex were also specifically associated with reporting rape for MSM. Perpetrators of sexual and verbal assault were usually unknown, whilst perpetrators of physical violence toward FSW were usually regular sexual partners. MSM and FSW experienced a similarly high incidence of sexual assault in coastal Kenya, in addition to physical and verbal assault. Current national policies focus heavily on gender-based violence against women and young girls, but need to be inclusive of MSM and FSW.

Enabling high speed friction stir welding of aluminum tailor welded blanks

NASA Astrophysics Data System (ADS)

Hovanski, Yuri

Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

Psychological Stressors in the Context of Commercial Sex Among Female Sex Workers in China

PubMed Central

Zhang, Chen; Hong, Yan; Li, Xiaoming; Qiao, Shan; Zhou, Yuejiao; Su, Shaobing

2014-01-01

Because of the illegality and stigma associated with female sex workers (FSW) in China, data were limited regarding their psychological stressors examined through the lens of occupational health. Analyzing qualitative data from 16 gatekeepers and 38 FSW, we explored these stressors in the context of commercial sex in China. We found that FSW faced a continuum of stressors that resulted from poverty, limited employment, lack of social protection, violence perpetrated by clients, and limited social support from peers and stable partners. We call for empowerment and a structural approach to address the needs of FSW to improve their psychological well-being. PMID:24180467

A Border Context of Violence: Mexican Female Sex Workers on the U.S.–Mexico Border

PubMed Central

Cepeda, Alice; Nowotny, Kathryn M.

2018-01-01

Female sex workers (FSW) represent a population confronted with an array of intersecting social problems. We explore the case of FSW in Nuevo Laredo and Ciudad Juarez to understand the everyday violence associated with sex work within the unique context of Mexico. Life history interviews were conducted with 109 FSW revealing violent acts by clients and other sex industry employees (bar owners, police, other FSW). The risk of violence by different types of persons associated with the sex work industry varied by venue and geographic area. Moreover, the violence was shaped by the social structural constraints of dominant gender ideologies. PMID:25409891

Factors associated with condom use among brothel-based female sex workers in Thailand.

PubMed

Buckingham, R W; Moraros, J; Bird, Y; Meister, E; Webb, N C

2005-07-01

This study sought to determine the actual levels of condom use by female sex workers (FSW) in Thailand brothels. Specifically, it examined the influence that the country of origin of the FSW patrons exerted on usage of a condom, and it assessed the relevancy of constructs from the Health Belief Model in predicting FSW requesting condom usage by their clients. A survey was administered to a cross-sectional non-randomized convenience sample of 150 FSW in four geographic locations in Thailand, which included: Bangkok, Chang Mai, Mae Hong Son and Other (comprised mainly of brothels in small villages). Statistical interpretation of the data indicated that Thai FSW requested condom use in 63% of the cases, while the overall mean of condom use was only 51%. Condom use by patrons' country of origin was as follows: westerners 76%, foreign Asians 52% and native Thai men 27%. These results fall considerably short of the Ministry of Health's goal of 100% condom use in Thai brothels. Furthermore, public health education initiatives need to effectively target the native Thai FSW patrons since they represent the clients least likely to use a condom (27%).

Gas tungsten arc welding and friction stir welding of ultrafine grained AISI 304L stainless steel: Microstructural and mechanical behavior characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabooni, S., E-mail: s.sabooni@ma.iut.ac.ir; Karimzadeh, F.; Enayati, M.H.

In the present study, an ultrafine grained (UFG) AISI 304L stainless steel with the average grain size of 650 nm was successfully welded by both gas tungsten arc welding (GTAW) and friction stir welding (FSW). GTAW was applied without any filler metal. FSW was also performed at a constant rotational speed of 630 rpm and different welding speeds from 20 to 80 mm/min. Microstructural characterization was carried out by High Resolution Scanning Electron Microscopy (HRSEM) with Electron Backscattered Diffraction (EBSD) and Transmission Electron Microscopy (TEM). Nanoindentation, microhardness measurements and tensile tests were also performed to study the mechanical properties ofmore » the base metal and weldments. The results showed that the solidification mode in the GTAW welded sample is FA (ferrite–austenite) type with the microstructure consisting of an austenite matrix embedded with lath type and skeletal type ferrite. The nugget zone microstructure in the FSW welded samples consisted of equiaxed dynamically recrystallized austenite grains with some amount of elongated delta ferrite. Sigma phase precipitates were formed in the region ahead the rotating tool during the heating cycle of FSW, which were finally fragmented into nanometric particles and distributed in the weld nugget. Also there is a high possibility that the existing delta ferrite in the microstructure rapidly transforms into sigma phase particles during the short thermal cycle of FSW. These suggest that high strain and deformation during FSW can promote sigma phase formation. The final austenite grain size in the nugget zone was found to decrease with increasing Zener–Hollomon parameter, which was obtained quantitatively by measuring the peak temperature, calculating the strain rate during FSW and exact examination of hot deformation activation energy by considering the actual grain size before the occurrence of dynamic recrystallization. Mechanical properties observations showed that the welding efficiency of the FSW welded sample is around 70%, which is more than 20% higher than the GTAW welded sample. - Highlights: • Microstructure and mechanical properties of UFG 304L stainless steel were studied during GTAW and FSW. • Sigma phase formation mechanism was studied during FSW of 304L stainless steel. • THERMOCALC analysis was performed to obtain possible formation temperatures for sigma phase. • Nano-mechanical twins were found in the TMAZ region.« less

Integrated bio-behavioural HIV surveillance surveys among female sex workers in Sudan, 2011-2012.

PubMed

Elhadi, Magda; Elbadawi, Abdulateef; Abdelrahman, Samira; Mohammed, Ibtisam; Bozicevic, Ivana; Hassan, Ehab A; Elmukhtar, Mohammed; Ahmed, Sally; Abdelraheem, Mohammed Sidahmed; Mubarak, Nazik; Elsanousi, Salwa; Setayesh, Hamidreza

2013-11-01

To assess HIV and syphilis prevalence, HIV-related behaviours and testing for HIV in female sex workers (FSW) in Sudan. Bio-behavioural surveys using respondent-driven sampling were carried out among FSW in the capital cities of 14 states in Sudan in 2011-2012. HIV and syphilis testing was done by rapid tests. 4220 FSW aged 15-49 years were recruited. The median age of recruited women varied from 21 to 28 years per site. The highest HIV prevalence was measured at two sites in the eastern zone (5.0% and 7.7%), while in the other zones it ranged from 0% to 1.5%. Syphilis prevalence ranged from 1.5% in the northern zone to 8.9% in the eastern zone. Ever having been tested for HIV was reported by 4.4%-23.9% of FSW across all sites. Condom use at last sex with a client varied from 4.7% to 55.1%, while consistent condom use with clients in the month preceding the surveys was reported by 0.7%-24.5% of FSW. The highest reporting of ever injecting drugs was measured at a site in the western zone (5.0%). The surveys' findings indicate that the highest burden of HIV in FSW is in the eastern states of the country. Condom use and HIV testing data demonstrate the need for HIV interventions that should focus on HIV testing and risk reduction strategies that include stronger condom promotion programmes in FSW and their clients.

Interfacial microstructure and properties of copper clad steel produced using friction stir welding versus gas metal arc welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Z.; Chen, Y.; Haghshenas, M., E-mail: mhaghshe@uwaterloo.ca

A preliminary study compares the feasibility and microstructures of pure copper claddings produced on a pressure vessel A516 Gr. 70 steel plate, using friction stir welding versus gas metal arc welding. A combination of optical and scanning electron microscopy is used to characterize the grain structures in both the copper cladding and heat affected zone in the steel near the fusion line. The friction stir welding technique produces copper cladding with a grain size of around 25 μm, and no evidence of liquid copper penetration into the steel. The gas metal arc welding of copper cladding exhibits grain sizes overmore » 1 mm, and with surface microcracks as well as penetration of liquid copper up to 50 μm into the steel substrate. Transmission electron microscopy reveals that metallurgical bonding is produced in both processes. Increased diffusion of Mn and Si into the copper cladding occurs when using gas metal arc welding, although some nano-pores were detected in the FSW joint interface. - Highlights: • Cladding of steel with pure copper is possible using either FSW or GMAW. • The FSW yielded a finer grain structure in the copper, with no evidence of cracking. • The FSW joint contains some evidence of nano-pores at the interface of the steel/copper. • Copper cladding by GMAW contained surface cracks attributed to high thermal stresses. • The steel adjacent to the fusion line maintained a hardness value below 248 HV.« less

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C

NASA Astrophysics Data System (ADS)

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled θ (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Filling the Knowledge Gap: Measuring HIV Prevalence and Risk Factors among Men Who Have Sex with Men and Female Sex Workers in Tripoli, Libya

PubMed Central

Valadez, Joseph J.; Berendes, Sima; Jeffery, Caroline; Thomson, Joanna; Ben Othman, Hussain; Danon, Leon; Turki, Abdullah A.; Saffialden, Rabea; Mirzoyan, Lusine

2013-01-01

Background Publications on Libya’s HIV epidemic mostly examined the victims of the tragic nosocomial HIV outbreak in the 1990s and the related dispute about the detention of foreign medical workers. The dispute resolution in 2003 included an agreement with the European Union on humanitarian cooperation and the development of Libya’s first National HIV Strategy. As part of this we conducted Libya’s first bio-behavioural survey among men having sex with men (MSM) and female sex workers (FSW). Methods Using respondent-driven sampling, we conducted a cross-sectional study to estimate the prevalence of HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), and related risk factors among 227 MSM and 69 FSW in Tripoli (FSW recruitment ended prematurely due to the political events in 2011). Results For MSM we estimated an HIV prevalence of 3.1%, HBV prevalence of 2.9%, and HCV prevalence of 7.3%, and for FSW an HIV prevalence of 15.7%, HBV prevalence of 0%, and HCV prevalence of 5.2%. We detected high levels of risk behaviours, poor HIV-related knowledge, high stigma and lack of prevention programmes. These results must be interpreted in the context of the political situation which prohibited reaching an ideal sample size for FSW. Conclusion There is urgent need to implement an effective National HIV Strategy informed by the results of this research. The risk of transmission within different risk groups and to the general population may be high given the recent military events that led to increased violence, migration, and the disruption of essential HIV-related services. PMID:23840521

Sexual violence against female sex workers in The Gambia: a cross-sectional examination of the associations between victimization and reproductive, sexual and mental health.

PubMed

Sherwood, Jennifer A; Grosso, Ashley; Decker, Michele R; Peitzmeier, Sarah; Papworth, Erin; Diouf, Daouda; Drame, Fatou Maria; Ceesay, Nuha; Baral, Stefan

2015-03-19

Female sex workers (FSW) are a vulnerable population for sexual violence and poor sexual and reproductive health outcomes. Sexual violence against FSW has not been widely studied in The Gambia. This study will report the prevalence of and evaluate the health issues correlated with forced sex perpetrated by clients against FSW in The Gambia, and will secondly aim to inform future research and efforts to improve health outcomes for survivors of violence. A cross-sectional survey was administered among 251 FSW accrued through a combination of chain referral and venue-based sampling in The Gambia. Eligibility criteria included being over 16 years old and having exchanged sex for money, goods, or favors in the past 12 months. There is a high prevalence of sexual violence against FSW in The Gambia, with 29% (n = 70) of participants reporting a client forced them to have sex in their lifetime. Women who reported forced sex by a client were more likely to report symptoms of depression (aOR 2.15, CI: 1.10-4.16 p < 0.05), unwanted pregnancy (aOR: 2.69, CI: 1.12-6.49 p < 0.05) and report "no", "difficult" or "somewhat difficult" access to condoms (aOR: 3.31, CI: 1.76-6.26 p < .01) compared to women who did not report forced sex. Client-perpetrated forced sex was also negatively associated with receiving any sexually transmitted infection (STI) test in the past 12 months (aOR: 0.49, CI: .26-.91 p < .05). FSW who experience sexual violence by a client are more likely to experience poor sexual, reproductive and mental health outcomes. Responding to sexual violence among FSW, including providing survivors with access to post-exposure prophylaxis, emergency contraception, and mental health services, must be a priority given the prevalence of forced sex and links with poor health outcomes. Efforts to reduce sexual violence against FSW is a vital strategy to improve the health and safety of FSW as well as impact the spread of HIV/STIs in The Gambia.

Orion GN and C Model Based Development: Experience and Lessons Learned

NASA Technical Reports Server (NTRS)

Jackson, Mark C.; Henry, Joel R.

2012-01-01

The Orion Guidance Navigation and Control (GN&C) team is charged with developing GN&C algorithms for the Exploration Flight Test One (EFT-1) vehicle. The GN&C team is a joint team consisting primarily of Prime Contractor (Lockheed Martin) and NASA personnel and contractors. Early in the GN&C development cycle the team selected MATLAB/Simulink as the tool for developing GN&C algorithms and Mathworks autocode tools as the means for converting GN&C algorithms to flight software (FSW). This paper provides an assessment of the successes and problems encountered by the GN&C team from the perspective of Orion GN&C developers, integrators, FSW engineers and management. The Orion GN&C approach to graphical development, including simulation tools, standards development and autocode approaches are scored for the main activities that the team has completed through the development phases of the program.

Friction Stir Welding of Steel Alloys

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

2001-01-01

The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

A border context of violence: Mexican female sex workers on the U.S.-Mexico border.

PubMed

Cepeda, Alice; Nowotny, Kathryn M

2014-12-01

Female sex workers (FSW) represent a population confronted with an array of intersecting social problems. We explore the case of FSW in Nuevo Laredo and Ciudad Juarez to understand the everyday violence associated with sex work within the unique context of Mexico. Life history interviews were conducted with 109 FSW revealing violent acts by clients and other sex industry employees (bar owners, police, other FSW). The risk of violence by different types of persons associated with the sex work industry varied by venue and geographic area. Moreover, the violence was shaped by the social structural constraints of dominant gender ideologies. © The Author(s) 2014.

Low-Temperature Friction-Stir Welding of 2024 Aluminum

NASA Technical Reports Server (NTRS)

Benavides, S.; Li, Y.; Murr, L. E.; Brown, D.; McClure, J. C.

1998-01-01

Solid state friction-stir welding (FSW) has been demonstrated to involve dynamic recrystallization producing ultra-fine, equiaxed grain structures to facilitate superplastic deformation as the welding or joining mechanism. However, the average residual, equiaxed, grain size in the weld zone has ranged from roughly 0.5 micron to slightly more than 10 micron, and the larger weld zone grain sizes have been characterized as residual or static grain growth as a consequence of the temperatures in the weld zone (where center-line temperatures in the FSW of 6061 Al have been shown to be as high as 480C or -0.8 T(sub M) where T(sub M) is the absolute melting temperature)). In addition, the average residual weld zone grain size has been observed to increase near the top of the weld, and to decrease with distance on either side of the weld-zone centerline, an d this corresponds roughly to temperature variations within the weld zone. The residual grain size also generally decreases with decreasing FSW tool rotation speed. These observations are consistent with the general rules for recrystallization where the recrystallized grain size decreases with increasing strain (or deformation) at constant strain rate, or with increasing strain-rate, or with increasing strain rate at constant strain; especially at lower ambient temperatures, (or annealing temperatures). Since the recrystallization temperature also decreases with increasing strain rate, the FSW process is somewhat complicated because the ambient temperature, the frictional heating fraction, and the adiabatic heating fraction )proportional to the product of strain and strain-rate) will all influence both the recrystallization and growth within the FSW zone. Significantly reducing the ambient temperature of the base metal or work pieces to be welded would be expected to reduce the residual weld-zone grain size. The practical consequences of this temperature reduction would be the achievement of low temperature welding. This study compares the residual grain sizes and microstructures in 2024 Al friction-stir welded at room temperature (about 30C and low temperature (-30C).

Correlation of Fracture Behavior With Microstructure in Friction Stir Welded, and Spin Formed AI-Li 2195 Domes

NASA Technical Reports Server (NTRS)

Tayon, Wesley A.; Domack, Marcia S.; Hales, Stephen J.

2012-01-01

Single-piece, spin-formed domes manufactured from friction stir welded (FSW) plates of Al-Li alloy 2195 have the potential to reduce the cost of fabricating cryogenic propellant tanks. Mechanical properties in the completed domes can be related directly to the final material condition and the microstructures developed. However, these new fabrication techniques have resulted in unexpected material challenges, such as abnormal grain growth in the weld nugget and the propensity for fracture in the adjacent thermo-mechanically affected zone (TMAZ). In this study, the microstructure and texture transformations within the TMAZ are related to fracture location in the vicinity of the weldment. The texture variations in the TMAZ are caused primarily by the varying amounts of shear deformation introduced during the FSW process. Grain morphology and microtexture characteristics are examined as a function of location in the TMAZ via electron backscatter diffraction (EBSD). A strong correlation between fracture location and the presence of texture banding in the TMAZ is observed. The fracture path tends to follow a distinct region of low Taylor Factor (TF) grains.

Correlation of Fracture Behavior with Microstructure in Friction Stir Welded, and Spin-Formed Al-Li 2195 Domes

NASA Astrophysics Data System (ADS)

Tayon, Wesley A.; Domack, Marcia S.; Hales, Stephen J.

Single-piece, spin-formed domes manufactured from friction stir welded (FSW) plates of Al-Li alloy 2195 have the potential to reduce the cost of fabricating cryogenic propellant tanks. Mechanical properties in the completed domes can be related directly to the final material condition and the microstructures developed. However, these new fabrication techniques have resulted in unexpected material challenges, such as abnormal grain growth in the weld nugget and the propensity for fracture in the adjacent thermo-mechanically affected zone (TMAZ). In this study, the microstructure and texture transformations within the TMAZ are related to fracture location in the vicinity of the weldment. The texture variations in the TMAZ are caused primarily by the varying amounts of shear deformation introduced during the FSW process. Grain morphology and microtexture characteristics are examined as a function of location in the TMAZ via electron backscatter diffraction (EBSD). A strong correlation between fracture location and the presence of texture banding in the TMAZ is observed. The fracture path tends to follow a distinct region of low Taylor Factor (TF) grains.

Near Net Manufacturing Using Thin Gage Friction Stir Welding

NASA Technical Reports Server (NTRS)

Takeshita, Jennifer; Potter, David; Holquin, Michael

2006-01-01

Friction Stir Welding (FSW) and near net spin forming of FSW aluminumn blanks were investigated for large-scale pressure vessel applications. With a specific focus on very thin gage 2xxx and 7xxx aluminum alloys, the program concentrated on the following: the criteria used for material selection, a potential manufacturing flow, and the effectiveness and associated risks of near net spin forming. Discussion will include the mechanical properties of the friction stir welds and the parent material from before and after the spin forming process. This effort was performed under a NASA Space Exploration initiative focused on increasing the affordability, reliability and performance of pressure vessels larger than 10 ft. diameter.

Mechanical Properties and Microstructure of TIG and FSW Joints of a New Al-Mg-Mn-Sc-Zr Alloy

NASA Astrophysics Data System (ADS)

Xu, Guofu; Qian, Jian; Xiao, Dan; Deng, Ying; Lu, Liying; Yin, Zhimin

2016-04-01

A new Al-5.8%Mg-0.4%Mn-0.25%Sc-0.10%Zr (wt.%) alloy was successfully welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques, respectively. The mechanical properties and microstructure of the welded joints were investigated by microhardness measurements, tensile tests, and microscopy methods. The results show that the ultimate tensile strength, yield strength, and elongation to failure are 358, 234 MPa, and 27.6% for TIG welded joint, and 376, 245 MPa and 31.9% for FSW joint, respectively, showing high strength and superior ductility. The TIG welded joint fails in the heat-affected zone and the fracture of FSW joint is located in stirred zone. Al-Mg-Mn-Sc-Zr alloy is characterized by lots of dislocation tangles and secondary coherent Al3(Sc,Zr) particles. The superior mechanical properties of the TIG and FSW joints are mainly derived from the Orowan strengthening and grain boundary strengthening caused by secondary coherent Al3(Sc,Zr) nano-particles (20-40 nm). For new Al-Mg-Mn-Sc-Zr alloy, the positive effect from secondary Al3(Sc, Zr) particles in the base metal can be better preserved in FSW joint than in TIG welded joint.

Barriers to Follow-Up for Abnormal Papanicolaou Smears among Female Sex Workers in Lima, Peru.

PubMed

Aharon, Devora; Calderon, Martha; Solari, Vicky; Alarcon, Patricia; Zunt, Joseph

2017-01-01

Cervical cancer is the most prevalent cancer among Peruvian women. Female sex workers (FSW) in Peru are at elevated risk for HPV infection, and receive annual Papanicolaou screening. The objective of this study was to identify barriers to follow-up for abnormal Pap smears among FSW in Peru. 97 FSW attending the Alberto Barton Health Center in Lima were surveyed regarding their STI screening history. 17 women with a history of an abnormal Pap smear were interviewed about their experiences regarding follow-up care. Of the 27 HPV-positive women, only 8 (30%) received follow-up treatment. Of the 19 women who did not receive follow-up, 7 (37%) had not been informed of their abnormal result. Qualitative interviews revealed that the major barrier to follow-up was lack of knowledge about HPV and potential health consequences of an abnormal Pap smear. HPV infection is highly prevalent in Peruvian FSW, yet only 30% of FSW with abnormal Pap smears receive follow-up care. The predominant barriers to follow-up were lack of standardization in recording and communicating results and insufficient FSW knowledge regarding health consequences of HPV infection. Standardization of record-keeping and distribution of educational pamphlets have been implemented to improve follow-up for HPV.

HIV care and treatment experiences among female sex workers living with HIV in sub-Saharan Africa: A systematic review.

PubMed

Lancaster, Kathryn E; Cernigliaro, Dana; Zulliger, Rose; Fleming, Paul F

2016-12-01

Female sex workers (FSW) living with HIV in sub-Saharan Africa have poor engagement to HIV care and treatment. Understanding the HIV care and treatment engagement experiences of FSW has important implications for interventions to enhance care and treatment outcomes. We conducted a systematic review to examine the HIV care experiences and determinants of linkage and retention in care, antiretroviral therapy (ART) initiation, and ART adherence and viral suppression among FSW living with HIV in sub-Saharan Africa. The databases PubMed, Embase, Web of Science, SCOPUS, CINAHL, Global Health, Psycinfo, Sociological Abstracts, and Popline were searched for variations of search terms related to sex work and HIV care and treatment among sub-Saharan African populations. Ten peer-reviewed articles published between January 2000 and August 2015 met inclusion criteria and were included in this review. Despite expanded ART access, FSW in sub-Saharan Africa have sub-optimal HIV care and treatment engagement outcomes. Stigma, discrimination, poor nutrition, food insecurity, and substance use were commonly reported and associated with poor linkage to care, retention in care, and ART initiation. Included studies suggest that interventions with FSW should focus on multilevel barriers to engagement in HIV care and treatment and explore the involvement of social support from intimate male partners. Our results emphasise several critical points of intervention for FSW living with HIV, which are urgently needed to enhance linkage to HIV care, retention in care, and treatment initiation, particularly where the HIV prevalence among FSW is greatest.

Changes in risk behaviours and prevalence of sexually transmitted infections following HIV preventive interventions among female sex workers in five districts in Karnataka state, south India.

PubMed

Ramesh, B M; Beattie, Tara S H; Shajy, Isac; Washington, Reynold; Jagannathan, Latta; Reza-Paul, Sushena; Blanchard, James F; Moses, Stephen

2010-02-01

To examine the impact of a large-scale HIV prevention programme for female sex workers (FSW) in Karnataka state, south India, on the prevalence of HIV/sexually transmitted infections (STI), condom use and programme coverage. Baseline and follow-up integrated biological and behavioural surveys were conducted on random samples of FSW in five districts in Karnataka between 2004 and 2009. 4712 FSW participated in the study (baseline 2312; follow-up 2400), with follow-up surveys conducted 28-37 months after baseline. By follow-up, over 85% of FSW reported contact by a peer educator and having visited a project STI clinic. Compared with baseline, there were reductions in the prevalence of HIV (19.6% vs 16.4%, adjusted odds ratio (AOR) 0.81, 95% CI 0.67 to 0.99, p=0.04); high-titre syphilis (5.9% vs 3.4%, AOR 0.53, 95% CI 0.37 to 0.77, p=0.001); and chlamydia and/or gonorrhoea (8.9% vs 7.0%, AOR 0.72, 95% CI 0.54 to 0.94, p=0.02). Reported condom use at last sex increased significantly for repeat clients (66.1% vs 84.1%, AOR 1.98, 95% CI 1.58 to 2.48, p<0.001) and marginally for occasional clients (82.9% vs 88.0%, AOR 1.22, 95% CI 0.89 to 1.66, p=0.2), but remained stable for regular partners (32%). Compared with street and home-based FSW, brothel-based FSW were at highest risk of HIV and STI, despite high levels of reported condom use. This large-scale HIV prevention programme for FSW achieved reductions in HIV and STI prevalence, high rates of condom use with clients and high rates of programme coverage. Improved strategies to increase condom use with regular partners and reduce the vulnerability of brothel-based FSW to HIV are required.

Risk of sexual, physical and verbal assaults on men who have sex with men and female sex workers in coastal Kenya

PubMed Central

Micheni, Murugi; Rogers, Sam; Wahome, Elizabeth; Darwinkel, Marianne; van der Elst, Elise; Gichuru, Evans; Graham, Susan M.; Sanders, Eduard J.; Smith, Adrian D.

2016-01-01

Background Violence toward MSM and female sex workers (FSW) is associated with HIV risk, and its prevention is prioritized in international HIV/AIDS policy. Methods Sociodemographic and behavioural data derived from HIV risk and follow-up cohorts including MSM and FSW in coastal Kenya between 2005 and 2014 was used to estimate the risk of rape, physical assault and verbal abuse, and to assess associations between first occurrence of assault with individual and recent behavioural factors. Results Incidence of first reported rape was similar for MSM [3.9, confidence interval (CI) 3.1–5.0 per 100 person-years (pyrs)] and FSW (4.8 CI 3.5–6.4 per 100 pyrs), P =0.22. Incidence of first reported physical and verbal assault was higher for FSW than MSM (21.1 versus 12.9 per 100 pyrs, P =0.14 and 51.3 versus 30.9 per 100 pyrs, P =0.03 respectively). Recent alcohol use was associated with reporting of all forms of assault by MSM [adjusted odds ratio (AOR) 1.8, CI 0.9–3.5] and FSW (AOR 4.4, CI 1.41–14.0), as was recent sale of sex for MSM (AOR 2.0, CI 1.1–3.8). Exclusive sex with men, active sex work, and group sex were also specifically associated with reporting rape for MSM. Perpetrators of sexual and verbal assault were usually unknown, whilst perpetrators of physical violence toward FSW were usually regular sexual partners. Conclusion MSM and FSW experienced a similarly high incidence of sexual assault in coastal Kenya, in addition to physical and verbal assault. Current national policies focus heavily on gender-based violence against women and young girls, but need to be inclusive of MSM and FSW. PMID:26562812

Linking process and structure in the friction stir scribe joining of dissimilar materials: A computational approach with experimental support

DOE PAGES

Gupta, Varun; Upadhyay, Piyush; Fifield, Leonard S.; ...

2018-04-04

We present that friction stir welding (FSW) is a popular technique to join dissimilar materials in numerous applications. The solid state nature of the process enables joining materials with strikingly different physical properties. For welds in lap configuration, an enhancement to this technology is made by introducing a short, hard insert, referred to as a cutting-scribe, at the bottom of the tool pin. The cutting-scribe induces deformation in the bottom plate which leads to the formation of mechanical interlocks or hook like structures at the interface of two materials. A thermo-mechanical computational model employing a coupled Eulerian-Lagrangian approach is developedmore » to quantitatively capture the morphology of these interlocks during the FSW process. Simulations using this model are validated by experimental observations. In conclusion, the identified interface morphology coupled with the predicted temperature field from this process–structure model can be used to estimate the post-weld microstructure and joint strength.« less

Linking process and structure in the friction stir scribe joining of dissimilar materials: A computational approach with experimental support

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Varun; Upadhyay, Piyush; Fifield, Leonard S.

We present that friction stir welding (FSW) is a popular technique to join dissimilar materials in numerous applications. The solid state nature of the process enables joining materials with strikingly different physical properties. For welds in lap configuration, an enhancement to this technology is made by introducing a short, hard insert, referred to as a cutting-scribe, at the bottom of the tool pin. The cutting-scribe induces deformation in the bottom plate which leads to the formation of mechanical interlocks or hook like structures at the interface of two materials. A thermo-mechanical computational model employing a coupled Eulerian-Lagrangian approach is developedmore » to quantitatively capture the morphology of these interlocks during the FSW process. Simulations using this model are validated by experimental observations. In conclusion, the identified interface morphology coupled with the predicted temperature field from this process–structure model can be used to estimate the post-weld microstructure and joint strength.« less

Process Model for Friction Stir Welding

NASA Technical Reports Server (NTRS)

Adams, Glynn

1996-01-01

Friction stir welding (FSW) is a relatively new process being applied for joining of metal alloys. The process was initially developed by The Welding Institute (TWI) in Cambridge, UK. The FSW process is being investigated at NASA/MSEC as a repair/initial weld procedure for fabrication of the super-light-weight aluminum-lithium shuttle external tank. The FSW investigations at MSFC were conducted on a horizontal mill to produce butt welds of flat plate material. The weldment plates are butted together and fixed to a backing plate on the mill bed. A pin tool is placed into the tool holder of the mill spindle and rotated at approximately 400 rpm. The pin tool is then plunged into the plates such that the center of the probe lies at, one end of the line of contact, between the plates and the shoulder of the pin tool penetrates the top surface of the weldment. The weld is produced by traversing the tool along the line of contact between the plates. A lead angle allows the leading edge of the shoulder to remain above the top surface of the plate. The work presented here is the first attempt at modeling a complex phenomenon. The mechanical aspects of conducting the weld process are easily defined and the process itself is controlled by relatively few input parameters. However, in the region of the weld, plasticizing and forging of the parent material occurs. These are difficult processes to model. The model presented here addresses only variations in the radial dimension outward from the pin tool axis. Examinations of the grain structure of the weld reveal that a considerable amount of material deformation also occurs in the direction parallel to the pin tool axis of rotation, through the material thickness. In addition, measurements of the axial load on the pin tool demonstrate that the forging affect of the pin tool shoulder is an important process phenomenon. Therefore, the model needs to be expanded to account for the deformations through the material thickness and the forging affect of the shoulder. The energy balance at the boundary of the plastic region with the environment required that energy flow away from the boundary in both radial directions. One resolution to this problem may be to introduce a time dependency into the process model, allowing the energy flow to oscillate across this boundary. Finally, experimental measurements are needed to verify the concepts used here and to aid in improving the model.

Complete Status Report Documenting Weld Development for Thin Wall Tubing of ODS Ferritic Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoelzer, David T.; Edmondson, Philip D.; Gussev, Maxim N.

Beginning in 2015, research in the FCRD program began the development of FSW for joining thin sections of 14YWT in the form of thin (0.5 mm) plate and ultimately thin wall tubing. In the previous fiscal year, a ~1 mm thick plate, or sheet, of 14YWT was produced by hot rolling with no edge cracking. The initial FSW experiment was performed on the 1 mm thick plate and involved a bead-on-plate weld in which the spinning pin tool is plunged into the plate surface, but does not penetrate the thickness of the plate, and then travels the length of themore » plate. The FSW run successfully produced a bead-on-plate stir zone on the 1 mm thick plate of 14YWT, but no characterization studies of the stir zone were performed by the end of FY15. Therefore, the results presented in this report cover the microstructural analysis of the bead-on-plate stir zone and the initial research task on obtaining tensile properties of the stir zone using the digital image correlation (DIC) approach during testing of miniature tensile specimens to assess the quality of the FSW parameters used in the initial experiment. The results of the microstructural characterization study using optical, scanning electron and scanning transmission electron microscopies showed the grain structure in the SZ to have isotropic and irregular shape but very similar size compared to the highly elongated grains oriented horizontally with the plane of the plate that were observed in the unaffected zone of 14YWT. Several cracks oriented horizontally were observed mostly on the retreating side of the SZ in both the SZ and TMAZ. These cracks may have formed due to insufficient pressure being exerted on the top surface of the plate by the shoulder and pin tool during the FSW run. High resolution STEM-EDS analysis showed the presence of the Y-Ti-O particles in the SZ, but that some particles exhibited coarsening. Overall, the FSW parameters used to produce the bead-on-plate SZ in the 0.1 cm thick plate of 14YWT were nearly optimized. The results of the digital image correlation (DIC) analysis of the two SS-Mini-2 tensile specimens fabricated from the 0.1 cm thick plate of 14YWT showed that the specimens exhibited high strength and good ductility. However, strain localization occurred in one of the specimens during the tensile test that was too close to the grips, which invalidated the data from the DIC analysis. This was surprising since the abrupt crack pop-in that occurred in the 0.1 cm thick plate of 14YWT during fabrication by wire EDM suggested that residual stresses were high. Residual stress measurements and the effects of post weld heat treatment on the FSW quality of joined 14YWT plates will be investigated in the next FW work package.« less

Control of forward swept wing configurations dominated by flight-dynamic/aeroelastic interactions

NASA Technical Reports Server (NTRS)

Rimer, M.; Chipman, R.; Muniz, B.

1984-01-01

An active control system concept for an aeroelastic wind-tunnel model of a statically unstable FSW configuration with wing-mounted stores is developed to provide acceptable longitudinal flying qualities while maintaining adequate flutter speed margin. On FSW configurations, the inherent aeroelastic wing divergence tendency causes strong flight-dynamic/aeroelastic interactions that in certain cases can produce a dynamic instability known as body-freedom flutter (BFF). The carriage of wing-mounted stores is shown to severely aggravate this problem. The control system developed combines a canard-based SAS with an Active Divergence/Flutter Suppression (ADFS) system which relies on wing-mounted sensors and a trailing-edge device (flaperon). Synergism between these two systems is exploited to obtain the flying qualities and flutter speed objectives.

A Vehicle Management End-to-End Testing and Analysis Platform for Validation of Mission and Fault Management Algorithms to Reduce Risk for NASAs Space Launch System

NASA Technical Reports Server (NTRS)

Trevino, Luis; Johnson, Stephen B.; Patterson, Jonathan; Teare, David

2015-01-01

The engineering development of the National Aeronautics and Space Administration's (NASA) new Space Launch System (SLS) requires cross discipline teams with extensive knowledge of launch vehicle subsystems, information theory, and autonomous algorithms dealing with all operations from pre-launch through on orbit operations. The nominal and off-nominal characteristics of SLS's elements and subsystems must be understood and matched with the autonomous algorithm monitoring and mitigation capabilities for accurate control and response to abnormal conditions throughout all vehicle mission flight phases, including precipitating safing actions and crew aborts. This presents a large and complex systems engineering challenge, which is being addressed in part by focusing on the specific subsystems involved in the handling of off-nominal mission and fault tolerance with response management. Using traditional model-based system and software engineering design principles from the Unified Modeling Language (UML) and Systems Modeling Language (SysML), the Mission and Fault Management (M&FM) algorithms for the vehicle are crafted and vetted in Integrated Development Teams (IDTs) composed of multiple development disciplines such as Systems Engineering (SE), Flight Software (FSW), Safety and Mission Assurance (S&MA) and the major subsystems and vehicle elements such as Main Propulsion Systems (MPS), boosters, avionics, Guidance, Navigation, and Control (GNC), Thrust Vector Control (TVC), and liquid engines. These model-based algorithms and their development lifecycle from inception through FSW certification are an important focus of SLS's development effort to further ensure reliable detection and response to off-nominal vehicle states during all phases of vehicle operation from pre-launch through end of flight. To test and validate these M&FM algorithms a dedicated test-bed was developed for full Vehicle Management End-to-End Testing (VMET). For addressing fault management (FM) early in the development lifecycle for the SLS program, NASA formed the M&FM team as part of the Integrated Systems Health Management and Automation Branch under the Spacecraft Vehicle Systems Department at the Marshall Space Flight Center (MSFC). To support the development of the FM algorithms, the VMET developed by the M&FM team provides the ability to integrate the algorithms, perform test cases, and integrate vendor-supplied physics-based launch vehicle (LV) subsystem models. Additionally, the team has developed processes for implementing and validating the M&FM algorithms for concept validation and risk reduction. The flexibility of the VMET capabilities enables thorough testing of the M&FM algorithms by providing configurable suites of both nominal and off-nominal test cases to validate the developed algorithms utilizing actual subsystem models such as MPS, GNC, and others. One of the principal functions of VMET is to validate the M&FM algorithms and substantiate them with performance baselines for each of the target vehicle subsystems in an independent platform exterior to the flight software test and validation processes. In any software development process there is inherent risk in the interpretation and implementation of concepts from requirements and test cases into flight software compounded with potential human errors throughout the development and regression testing lifecycle. Risk reduction is addressed by the M&FM group but in particular by the Analysis Team working with other organizations such as S&MA, Structures and Environments, GNC, Orion, Crew Office, Flight Operations, and Ground Operations by assessing performance of the M&FM algorithms in terms of their ability to reduce Loss of Mission (LOM) and Loss of Crew (LOC) probabilities. In addition, through state machine and diagnostic modeling, analysis efforts investigate a broader suite of failure effects and associated detection and responses to be tested in VMET to ensure reliable failure detection, and confirm responses do not create additional risks or cause undesired states through interactive dynamic effects with other algorithms and systems. VMET further contributes to risk reduction by prototyping and exercising the M&FM algorithms early in their implementation and without any inherent hindrances such as meeting FSW processor scheduling constraints due to their target platform - the ARINC 6535-partitioned Operating System, resource limitations, and other factors related to integration with other subsystems not directly involved with M&FM such as telemetry packing and processing. The baseline plan for use of VMET encompasses testing the original M&FM algorithms coded in the same C++ language and state machine architectural concepts as that used by FSW. This enables the development of performance standards and test cases to characterize the M&FM algorithms and sets a benchmark from which to measure their effectiveness and performance in the exterior FSW development and test processes. This paper is outlined in a systematic fashion analogous to a lifecycle process flow for engineering development of algorithms into software and testing. Section I describes the NASA SLS M&FM context, presenting the current infrastructure, leading principles, methods, and participants. Section II defines the testing philosophy of the M&FM algorithms as related to VMET followed by section III, which presents the modeling methods of the algorithms to be tested and validated in VMET. Its details are then further presented in section IV followed by Section V presenting integration, test status, and state analysis. Finally, section VI addresses the summary and forward directions followed by the appendices presenting relevant information on terminology and documentation.

Violence victimisation, sexual risk and sexually transmitted infection symptoms among female sex workers in Thailand.

PubMed

Decker, Michele R; McCauley, Heather L; Phuengsamran, Dusita; Janyam, Surang; Seage, George R; Silverman, Jay G

2010-06-01

Commercial sex work is a primary context for heterosexual HIV/AIDS transmission. Violence victimisation is considered to compromise women's ability to protect against HIV and other sexually transmitted infections (STI); little research has investigated violence as it relates to sexual risk and STI among female sex workers (FSW). This study sought to compare sexual risk and STI symptoms among FSW based on recent violence exposure. Data from 815 FSW in Thailand were used to assess the prevalence of physical or sexual violence within the context of sex work, and associations of victimisation with sexual risk and STI symptoms. Approximately one in seven FSW (14.6%) had experienced violence in the week before the survey. Compared with their unexposed counterparts, FSW exposed to violence demonstrated a greater risk of condom failure (19.6% vs 12.3%, ARR 1.92, 95% CI 1.24 to 2.95) and client condom refusal (85.7% vs 69.0%, ARR 1.24, 95% CI 1.14 to 1.35). In analyses adjusted for sexual risk, violence related to STI symptoms collectively (ARR 1.11, 95% CI 1.02 to 1.21) and genital lesions as an individual STI symptom (ARR 1.78, 95% CI 1.20 to 2.66). Physical and sexual violence against FSW in Thailand appears to be common, with women experiencing such violence demonstrating diminished capacity for STI/HIV harm reduction and greater prevalence of STI symptoms. Efforts to reduce violence towards this vulnerable population must be prioritised, as a means of protecting the health and wellbeing of FSW, and as a key component of STI/HIV prevention and control.

Update on Risk Reduction Activities for a Liquid Advanced Booster for NASA's Space Launch System

NASA Technical Reports Server (NTRS)

Crocker, Andy; Graham, Bart

2016-01-01

Dynetics has designed innovative structure assemblies; manufactured them using Friction Stir Welding (FSW) to leverage NASA investments in tools, facilities, and processes; conducted proof and burst testing, demonstrating viability of design/build processes Dynetics/AR has applied state-of-the-art manufacturing and processing techniques to the heritage F-1, reducing risk for engine development Dynetics/AR has also made progress on technology demonstrations for ORSC cycle engine, which offers affordability and performance for both NASA and other launch vehicles Full-scale integrated oxidizer-rich test article. Testing will evaluate performance and combustion stability characteristics. Contributes to technology maturation for ox-rich staged combustion engines.

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints

PubMed Central

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-01-01

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σa (R = −1) = 1.68 HV (σa is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints. PMID:28772543

Fatigue Strength Estimation Based on Local Mechanical Properties for Aluminum Alloy FSW Joints.

PubMed

Sillapasa, Kittima; Mutoh, Yoshiharu; Miyashita, Yukio; Seo, Nobushiro

2017-02-15

Overall fatigue strengths and hardness distributions of the aluminum alloy similar and dissimilar friction stir welding (FSW) joints were determined. The local fatigue strengths as well as local tensile strengths were also obtained by using small round bar specimens extracted from specific locations, such as the stir zone, heat affected zone, and base metal. It was found from the results that fatigue fracture of the FSW joint plate specimen occurred at the location of the lowest local fatigue strength as well as the lowest hardness, regardless of microstructural evolution. To estimate the fatigue strengths of aluminum alloy FSW joints from the hardness measurements, the relationship between fatigue strength and hardness for aluminum alloys was investigated based on the present experimental results and the available wide range of data from the references. It was found as: σ a ( R = -1) = 1.68 HV ( σ a is in MPa and HV has no unit). It was also confirmed that the estimated fatigue strengths were in good agreement with the experimental results for aluminum alloy FSW joints.

Circular Migration by Mexican Female Sex Workers Who are Injection Drug Users: Implications for HIV in Mexican Sending Communities

PubMed Central

Ojeda, Victoria D.; Burgos, José Luis; Hiller, Sarah P.; Lozada, Remedios; Rangel, Gudelia; Vera, Alicia; Artamonova, Irina; Rodriguez, Carlos Magis

2013-01-01

Background Circular migration and injection drug use increase the risk of HIV transmission in sending communities. We describe female sex workers who are injection drug users’ (FSW-IDUs) circular migration and drug use behaviors. Methods Between 2008-2010, 258 migrant FSW-IDUs residing in Tijuana and Ciudad Juarez, Mexico responded to questionnaires. Results 24% of FSW-IDUs were circular migrants. HIV prevalence was 3.3% in circular migrants and 6.1% in non-circular migrants; 50% of circular and 82% of non-circular migrants were unaware of their HIV infection. Among circular migrants, 44% (n=27) consumed illicit drugs in their birthplace; 70% of these (n=20) injected drugs and one-half of injectors shared injection equipment in their birthplace. Women reporting active social relationships were significantly more likely to return home. Discussion Circular migrant FSW-IDUs exhibit multiple HIV risks and opportunities for bridging populations. Regular HIV testing and treatment and access to substance use services is critical for FSW-IDUs and their sexual/drug-using contacts. PMID:21833727

Characterization of exposures to airborne nanoscale particles during friction stir welding of aluminum.

PubMed

Pfefferkorn, Frank E; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; McCarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M Abbas; Gruetzmacher, George; Hoover, Mark D

2010-07-01

Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 microm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 microm) with 1-s resolution, lung deposited surface areas, and PM(2.5) concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 microm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at approximately 30 and approximately 550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at approximately 4.0 x 10(5) particles cm(-3), whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm(-3), depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10-100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) microg m(-3); the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial operations.

Characterization of Exposures to Airborne Nanoscale Particles During Friction Stir Welding of Aluminum

PubMed Central

Pfefferkorn, Frank E.; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; Mccarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M. Abbas; Gruetzmacher, George; Hoover, Mark D.

2010-01-01

Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 μm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 μm) with 1-s resolution, lung deposited surface areas, and PM2.5 concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 μm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at ∼30 and ∼550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at ∼4.0 × 105 particles cm−3, whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm−3, depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10–100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) μg m−3; the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial operations. PMID:20453001

Analysis of cooling media effects on microstructure and mechanical properties during FSW/UFSW of AA 6082-T6

NASA Astrophysics Data System (ADS)

Atif Wahid, Mohd; Siddiquee, Arshad Noor; Khan, Zahid A.; Sharma, Nidhi

2018-04-01

The aim of the present study is to investigate the effect of cooling media on the temperature distribution, microstructure and mechanical properties of the joint produced during Underwater Friction Stir Welding (UFSW) in normal water, cold water (water with crushed ice (CFSW)) and air (FSW), for aluminum alloy (AA) 6082-T6. The results showed that peak temperature during UFSW and CFSW were significantly lower than the FSW. The temperature at the advancing side (AS) of the joint was higher than the retreating side (RS). Substantial reduction in TMAZ/HAZ width was observed during UFSW and CFSW as compared to FSW. Al-Mn-Fe-Si intermetallic phases were seen in all the joints along with the BM. The main strengthening precipitates found in UFSW and CFSW was β″ (Mg5Si6) which changed to β (Mg2Si) precipitates during FSW due to increased temperature. The tensile strength of the joints was best during UFSW followed by FSW and CFSW. The controlled temperature distribution resulted in improved tensile strength whereas both undercooling and overcooling resulted in decreased tensile strength, however, increased cooling rate does not improve the elongation. A typical ‘W’ shape hardness profile was observed in all the joints irrespective of the cooling media used. Maximum hardness was obtained in the UFSW joint due to refined grain structure, high-density dislocations and presence of β″ phases.

Burden and characteristics of HIV infection among female sex workers in Kampala, Uganda - a respondent-driven sampling survey.

PubMed

Hladik, Wolfgang; Baughman, Andrew L; Serwadda, David; Tappero, Jordan W; Kwezi, Rachel; Nakato, Namakula D; Barker, Joseph

2017-06-10

Sex workers in Uganda are at significant risk for HIV infection. We characterized the HIV epidemic among Kampala female sex workers (FSW). We used respondent-driven sampling to sample FSW aged 15+ years who reported having sold sex to men in the preceding 30 days; collected data through audio-computer assisted self-interviews, and tested blood, vaginal and rectal swabs for HIV, syphilis, neisseria gonorrhea, chlamydia trachomatis, and trichomonas vaginalis. A total of 942 FSW were enrolled from June 2008 through April 2009. The overall estimated HIV prevalence was 33% (95% confidence intervals [CI] 30%-37%) and among FSW 25 years or older was 44%. HIV infection is associated with low levels of schooling, having no other work, never having tested for HIV, self-reported genital ulcers or sores, and testing positive for neisseria gonorrhea or any sexually transmitted infections (STI). Two thirds (65%) of commercial sex acts reportedly were protected by condoms; one in five (19%) FSW reported having had anal sex. Gender-based violence was frequent; 34% reported having been raped and 24% reported having been beaten by clients in the preceding 30 days. One in three FSW in Kampala is HIV-infected, suggesting a severe HIV epidemic in this population. Intensified interventions are warranted to increase condom use, HIV testing, STI screening, as well as antiretroviral treatment and pre-exposure prophylaxis along with measures to overcome gender-based violence.

CERES Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_TRMM-PFM-VIRS_Beta1)

NASA Technical Reports Server (NTRS)

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2000-03-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

CERES Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_Terra-FM1-MODIS_Edition2C)

NASA Technical Reports Server (NTRS)

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2005-12-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

CERES) Monthly Gridded Single Satellite Fluxes and Clouds (FSW) in HDF (CER_FSW_Terra-FM2-MODIS_Edition2C)

NASA Technical Reports Server (NTRS)

Wielicki, Bruce A. (Principal Investigator); Barkstrom, Bruce R. (Principal Investigator)

The Monthly Gridded Radiative Fluxes and Clouds (FSW) product contains a month of space and time averaged Clouds and the Earth's Radiant Energy System (CERES) data for a single scanner instrument. The FSW is also produced for combinations of scanner instruments. All instantaneous fluxes from the CERES CRS product for a month are sorted by 1-degree spatial regions and by the Universal Time (UT) hour of observation. The mean of the instantaneous fluxes for a given region-hour bin is determined and recorded on the FSW along with other flux statistics and scene information. The mean adjusted fluxes at the four atmospheric levels defined by CRS are also included for both clear-sky and total-sky scenes. In addition, four cloud height categories are defined by dividing the atmosphere into four intervals with boundaries at the surface, 700-, 500-, 300-hPa, and the Top-of-the-Atmosphere (TOA). The cloud layers from CRS are put into one of the cloud height categories and averaged over the region. The cloud properties are also column averaged and included on the FSW. [Location=GLOBAL] [Temporal_Coverage: Start_Date=1998-01-01; Stop_Date=2001-10-31] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180] [Data_Resolution: Latitude_Resolution=1 degree; Longitude_Resolution=1 degree; Horizontal_Resolution_Range=100 km - < 250 km or approximately 1 degree - < 2.5 degrees; Temporal_Resolution=1 month; Temporal_Resolution_Range=Monthly - < Annual].

Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin Tool

NASA Technical Reports Server (NTRS)

Adams, Glynn; Venable, Richard; Lawless, Kirby

2003-01-01

Friction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.

HIV, sexually transmitted infections and sexual behaviour of male clients of female sex workers in Andhra Pradesh, Tamil Nadu and Maharashtra, India: results of a cross-sectional survey.

PubMed

Subramanian, Thilakavathi; Gupte, Mohan D; Paranjape, Ramesh S; Brahmam, Ginnela N V; Ramakrishnan, Lakshmi; Adhikary, Rajatashuvra; Kangusamy, Boopathi; Thomas, Beena E; Kallam, Srinivasan; Girish, C P K

2008-12-01

To characterize and describe patterns of HIV, sexually transmitted infections (STI) and sexual behaviour of male clients of female sex workers (FSW). A cross-sectional study was conducted among 4821 clients of FSW from 12 districts in three states in India: Andhra Pradesh, Maharashtra and Tamil Nadu. A structured questionnaire was administered to elicit demographic characteristics and sexual behavioural patterns. Blood and urine samples were tested for HIV, syphilis and herpes simplex type 2 serology, gonococcal and chlamydial infection. The median age of clients surveyed was 30 years; 57% were married and 64% had a steady sexual partner; 61% had sex with more than one FSW and 39% had four or more sexual encounters in the past month. The prevalence of HIV ranged from 2.0% to 10.9%, syphilis ranged from 3.1% to 10.1%; gonorrhoea and chlamydia ranged between 0% and 4.5%. Clients older than 30 years [odds ratio (OR) 1.65; 95% confidence interval (CI) 1.33-2.05] and having a different mix of commercial and non-commercial partners (OR 1.56; 95% CI 1.25-1.96) had a higher volume of sex acts with FSW. Inconsistent condom use with FSW was significantly associated with older clients (OR 4.2; 95% CI 3.33-5.29), illiteracy (OR 1.39; 95% CI 1.14-1.69), age <18 years at first paid sex (OR 1.83; 95% CI 1.24-2.70) and having different FSW partners in the past month (OR 1.64; 95% CI 1.23-2.18). Clients of FSW studied here constitute a significant bridge group for HIV and other STI, because of their high volume of different sexual partners and very low consistent condom use. HIV prevention programmes need to address male clients.

Metallurgical and Mechanical Characterization of High Temperature Titanium Alloys Joined by Friction Stir Welding

NASA Astrophysics Data System (ADS)

Gangwar, Kapil Dev

In the world of joining, riveting and additive manufacturing, weight reduction, and omission of defects (at both macro and micro level) remain of paramount. Therefore, in the wake of ubiquitous fusion welding (FW) and widely accepted approach of riveting using Inconel bolts to resist corrosion at higher temperature, friction stir welding (FSW) has emerged as a novice jewel in friction based additive manufacturing industry. With advancements in automation of welding process and tool material, FSW of materials with higher work hardening such as steel and titanium has also become probable. Process and property relations associated with FSW are inevitable in case of dissimilar titanium alloys, due to presence of heterogeneity (whether atrocious or advantageous) in and around the weld nugget. These process property relationships are needed to be studied and addressed properly in order to optimize the processing window for improved mechanical and metallurgical properties. In this study FSWed similar and dissimilar butt joints of α+β, and near α titanium, alloys have been produced for varying processing conditions in order to study the effect of rotation speed (rpm) and traverse speed (TS; mm-min-1). The aim of this study is to assess the effect of tool geometry, tool rpm, TS on microstructure and mechanical properties of most widely used α+β titanium alloy, Ti-6Al-4V (Ti-64), standard grain and fine grain in addition to α+β,Ti-5Al-4V (T-54M), standard grain, and near α, Ti-6Al-2Mo-4Zr-2Sn (Ti-6242), standard grain (SG) and fine grain (FG). During FSW, a unique α+β fine-grained microstructure has been formed depending on whether or not the peak temperature in the weld nugget (WN) reached above or below β transus temperature. The resulting microstructure consists of acicular α+β, emanating from the prior β grain boundary as the weld cools off. The changes in the microstructure are observed by optical microscopy (OM). Later, a detailed analysis of material flow has been done by scanning electron microscopy (SEM), and electron dispersive spectroscopy (EDS). Hardness profiles on the transverse cross section of the weld have been measured in order to relate the deformation of main constituents, α {hexagonal close packed (hcp)}, and β {body centered cubic (bcc)} that provides a new paradigm into grain refinement mechanism. Material flow and evolving microstructure along with distribution of corresponding elements distribution was characterized by SEM, and EDS respectively. For the case of dissimilar alloys (Ti-6242 & Ti-54M, and Ti-6242 & Ti-64 ) a necklace shaped macrostructure has been observed in the WN consisting of untransformed α migrating from the side of Ti-6242, and of basket-weave morphology (prior β grains transforming into α+β decorated with grain boundary α) of Ti-54M. Microhardness characterization undoubtedly reveals distinct boundaries between weld nugget and parent material. However, to understand the constitutive behavior of the thermo mechanically affected zone (TMAZ) on the advancing side (ADV), or retreating side (RET) and of WN, digital image correlation (DIC) technique has been adapted to develop strain maps in transverse tensile specimens. Improved mechanical properties of TMAZ on the ADV in comparison with RET TMAZ are in accordance with hardness values. Occurrence of fracture on the RET side, and morphology of the fractured surface have also been discussed. Based on the fractured morphology, it can be said that the presence of distinct and clustered island like morphologies in the form of transcrystalline and intercrystalline fracture is a results of microstructure that evolves due to difference in β transus temperature of two alloys. The mechanical properties are analyzed and discussed in that regard. Evolving volume fraction of phases along with their crystallographic orientation has also been elucidated. Evolution of texture has been discussed in terms of (100)_α,(002)_α,(110)_β,(101)_α and (102)_α. Main constituents of texture in friction stir welded dissimilar titanium alloys, (101)_α and (002)_α have been discussed for their strength and orientation at various rotation speed. It has been highlighted that for the FSW of dissimilar titanium alloys (near α,and α+β), center of the WN is stronger in texture in comparison with RET and ADV side. Furthermore, state-of-the-art FSW technique has been used to weld dissimilar titanium alloys for post weld heat treatment (PWHT) studies at 933°C for 45 minutes. The processing parameters for welding are 225 rpm, and 125 mm-min-1. In light of recent PWHT, conducted for FSWed Ti-6Al-4V, in order to achieve super plasticity, our study focuses on dissimilar titanium alloys, Ti-54M, and Ti-6242 FG. A proper understanding of underlying material flow during FSW of dissimilar titanium alloys is essential in designing a monolithic structure operating under varying thermal and mechanical loading. Higher fraction of α with no pre-defined prior β grain boundaries has been observed in PWHTed condition. Uniform, rather lower values of hardness have been achieved in the PWHTed specimen. Furthermore, Spatial arrangement, whether on ADV or RET, can significantly affect the evolution of microstructure, and congruent mechanical properties. In this study, Ti-54M and Ti-6242 FG have been joined by FSW with Ti-6242 FG being on ADV side. X-ray diffraction (XRD) technique has been utilized for phase evaluation, pole figure analysis, and residual stress measurements. Finally, a wide range of weld surfaces, macrostructures, microstructures, microhardness profiles, phase evolution, pole figures, full field strain maps, material flow patterns, fractographs and development of residual stresses has been presented in corresponding appendices. The morphology of the fractured surfaces along with the residual stress distribution, rendered by different rpm and TS employed on different combination of similar and dissimilar joints of titanium alloys, provided an insight to correlate the material flow, hardness distributions, tensile properties; yield strength (YS), ultimate tensile strength (UTS), and percentage elongation (% Elong.).

Investigation and development of friction stir welding process for unreinforced polyphenylene sulfide and reinforced polyetheretherketone

NASA Astrophysics Data System (ADS)

Ahmed, Hossain

The joining of thermoplastics through welding, a specific form of fusion bonding, offers numerous advantages over mechanical joining. It eliminates the use of costly fasteners and has only a limited effect on the strength of the parts being joined since it does not require the introduction of holes and loading pins, and it does not create significant stress concentrations. A specific form of welding, Friction Stir Welding, was investigated for the creation of butt joints of unreinforced polyphenylene sulfide (PPS) and short carbon fiber reinforced polyetheretherketone (PEEK) plates. Friction stir welding requires a rotating pin, a shoulder arrangement, relative movement between the tool and the weld piece and a clamping mechanism to hold the weld piece in place. Analytical models and experimental results show that the heat generated by the FSW tool is insufficient to produce the heat required to weld thermoplastic materials which makes FSW of polymers different from FSW of metals. A second heat source is required for preheating the thermoplastic parts prior to welding. A resistance type surface heater was placed at the bottom of two identical weld pieces for the experiments. Two types of shoulder design i.e. a rotating shoulder and a stationary shoulder were developed. Taguchi's Design of Experiment method was utilized to investigate the welding process, where duration of heating, process temperature, tool rotational speed and tool traverse speed were used as the welding parameters. The quality of the welding process was assumed to be indicated by the weld strength. DoE revealed that one of the process parameters, tool traverse speed, had significant influence on the tensile strength of PPS samples. While PPS sample showed relatively lower tensile strength with higher traverse speed, short carbon fiber reinforced PEEK samples had higher tensile strength with higher traverse speeds. In addition to tensile tests on dog bone shaped specimen, fracture toughness tests were performed for both PPS and PEEK samples to identify the fracture toughness of these materials. Presence of un-welded section in the welded specimen due to the setup of the experiments yielded notched tensile strengths during the tensile test process. With the help of fracture toughness values of these materials, notched tensile strengths of the welded samples were compared with the notched tensile strengths or residual tensile strengths of the base materials. In this study, residual joint efficiency of PEEK samples was found higher than that of PPS samples. Additionally, notched tensile strengths of the welded samples were compared with un-notched tensile strengths of the materials. The notched tensile strengths of PPS and PEEK were found about 80% and 75% of the respective base materials. Micrographs of PEEK samples showed the presence of more voids and cracks in the weld line compared to the un-welded samples. In this study, continuous friction stir welding process has been developed for butt joining of unreinforced PPS and short carbon fiber reinforced PEEK. The process parameters and the experimental setup can be utilized to investigate the weldability of different types of thermoplastic composites and various types of joint configurations.

Control of Structure in Conventional Friction Stir Welds through a Kinematic Theory of Metal Flow

NASA Technical Reports Server (NTRS)

Rubisoff, H.A.; Schneider, J.A.; Nunes, A.C.

2009-01-01

In friction stir welding (FSW), a rotating pin is translated along a weld seam so as to stir the sides of the seam together. Metal is prevented from flowing up the pin, which would result in plowing/cutting instead of welding, by a shoulder on the pin. In conventional FSW, the weld metal rests on an "anvil", which supports the heavy "plunge" load on the tool. In this study, both embedded tungsten wires along and copper plating on the faying surfaces were used to trace the flow of AA2219 weld metal around the C-FSW tool. The effect of tool rotational speed, travel speed, plunge load, and pin thread pitch on the resulting weld metal flow was evaluated. Plan, longitudinal, and transverse section x-ray radiographs were examined to trace the metal flow paths. The results are interpreted in terms of a kinematic theory of metal flow in FSW.

HIV testing behaviors among female sex workers in Southwest China.

PubMed

Hong, Yan; Zhang, Chen; Li, Xiaoming; Fang, Xiaoyi; Lin, Xiuyun; Zhou, Yuejiao; Liu, Wei

2012-01-01

Despite the recognized importance of HIV testing in prevention, care and treatment, HIV testing remains low in China. Millions of female sex workers (FSW) play a critical role in China's escalating HIV epidemic. Limited data are available regarding HIV testing behavior among this at-risk population. This study, based on a cross-sectional survey of 1,022 FSW recruited from communities in Southwest China, attempted to address the literature gap. Our data revealed that 48% of FSW ever took HIV testing; older age, less education, working in higher-income commercial sex venues and better HIV knowledge were associated with HIV testing. Those who never took HIV testing were more likely to engage in high-risk behaviors including inconsistent condom use with clients and stable partners. A number of psychological and structural barriers to testing were also reported. We call for culturally appropriate interventions to reduce HIV risks and promote HIV testing for vulnerable FSW in China.

Homogeneity of Mechanical Properties of Underwater Friction Stir Welded 2219-T6 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Liu, H. J.; Zhang, H. J.; Yu, L.

2011-11-01

Underwater friction stir welding (FSW) has been demonstrated to be available for the improvement in tensile strength of normal FSW joints. In order to illuminate the intrinsic reason for strength improvement through underwater FSW, a 2219 aluminum alloy was underwater friction stir welded and the homogeneity of mechanical properties of the joint was investigated by dividing the joint into three layers. The results indicate that the tensile strength of the three layers of the joint is all improved by underwater FSW, furthermore, the middle and lower layers have larger extent of strength improvement than the upper layer, leading to an increase in the homogeneity of mechanical properties of the joint. The minimum hardness value of each layer, especially the middle and lower layers, is improved under the integral water cooling effect, which is the intrinsic reason for the strength improvement of underwater joint.

The influence of stigma and discrimination on female sex workers' access to HIV services in St. Petersburg, Russia.

PubMed

King, Elizabeth J; Maman, Suzanne; Bowling, J Michael; Moracco, Kathryn E; Dudina, Viktoria

2013-10-01

Stigma associated with HIV and risk behaviors is known to be a barrier to health care access for many populations. Less is known about female sex workers (FSW) in Russia, a population that is especially vulnerable to HIV-infection, and yet hard-to-reach for service providers. We administered a questionnaire to 139 FSW to better understand how stigma and discrimination influence HIV service utilization. Logistic regression analysis indicated that HIV-related stigma is negatively associated with uptake of HIV testing, while sex work-related stigma is positively associated with HIV testing. HIV-positive FSW are more likely than HIV-negative FSW to experience discrimination in health care settings. While decreasing societal stigma should be a long-term goal, programs that foster inclusion of marginalized populations in Russian health care settings are urgently needed.

High Burden of HIV Infection and Risk Behaviors Among Female Sex Workers in Three Main Urban Areas of Mozambique.

PubMed

Augusto, Ângelo do Rosário; Young, Peter W; Horth, Roberta Z; Inguane, Celso; Sathane, Isabel; Ngale, Katia; Benedetti, Marcos; Cummings, Beverley; Botão, Carlos Francisco Sande; Baltazar, Cynthia Amino Semá; Frank, Heidi; Fagan, Jennifer; Fisher Raymond, Henry; McFarland, Willi

2016-04-01

This is the first integrated biological and behavioral survey among female sex workers (FSW) in Mozambique. Using respondent-driven sampling, 400, 411 and 429 FSW were enrolled respectively in Maputo, Beira and Nampula in 2011-2012. Estimates were produced using RDSAT 7.1. HIV prevalence was 31.2, 23.6, and 17.8 % in each location respectively. Among HIV-positive FSW, 48.1, 79.8 and 89.6 % in each city, were unaware of their serostatus. Condom use at last sex with a client was 85.8, 73.4 and 62.8 % among FSW, respectively. HIV was associated with current age, age of first sex for money, low educational level, and having had a genital ulcer in the last 6 months. Results suggest the urgent need to increase behavioral and structural interventions in this key population.

Effects Of Welding On The Fatigue Behaviour Of Commercial Aluminum AA-1100 Joints

NASA Astrophysics Data System (ADS)

Uthayakumar, M.; Balasubramanian, V.; Rani, Ahmad Majdi Abdul; Hadzima, Branislav

2018-04-01

Friction Stir Welding (FSW) is an budding solid state welding process, which is frequently used for joining aluminum alloys where materials can be joined without melt and recast. Therefore, when welding alloys through FSW the phase transformations occurs will be in the solid state form. The present work is aimed in evaluating the fatigue life of friction stir welded commercial grade aluminum alloy joints. The commercial grade AA1100 aluminum alloy of 12mm thickness plate is welded and the specimens are tested using a rotary beam fatigue testing machine at different stress levels. The stress versus number of cycles (S-N) curves was plotted using the data points. The Fatigue life of tungsten inert gas (TIG) and metal inert gas (MIG) welded joints was compared. The fatigue life of the weld joints was interrelated with the tensile properties, microstructure and micro hardness properties. The effects of the notches and welding processes are evaluated and reported.

Exploring dynamics of anal sex among female sex workers in Andhra Pradesh.

PubMed

Tucker, Saroj; Krishna, Rama; Prabhakar, Parimi; Panyam, Swarup; Anand, Pankaj

2012-01-01

The anal sex among heterosexual couples is on the rise as reported in many scientific studies. Considering that unprotected anal sex has higher risk of human immunodeficiency virus (HIV) transmission than the vaginal sex, we undertook a study to understand the anal sex practices among Female Sex Workers (FSW). The study was conducted among FSW attending 11 randomly selected sexually transmitted infection (STI) clinics in Bill and Melinda Gates supported targeted interventions in Andhra Pradesh. A structured questionnaire was administered to the 555 FSW attending these clinics by project clinic counselors. Informed consent was obtained from all the study participants. Engaging in anal sex was self reported by 22% of sex workers, though demand from clients was reported to be much higher (40%). The reasons for anal sex practices included more money (61%), clout/influence of the client (45%), risk of losing client (27%), and forced sex (1.2%). Factors associated with anal sex were higher number of clients, higher duration of sex work, higher income, and older age group. Associated risks perceived by FSW were bleeding and injury to anal canal (98%) while only 28% associated it with higher HIV transmission risk. Reported Condom and lubricant use was about 88% and 39% respectively. The study shows that there is frequent anal sex, inconsistent condom and infrequent lubricant usage, economic and physical coercion, and low awareness of STI/HIV transmission risk among FSW, which have serious implications for HIV prevention programmes. There is a need to focus on anal sex education and use of lubricants along with condoms during anal sex in FSW-targeted interventions in AP.

Intermetallic layers in temperature controlled Friction Stir Welding of dissimilar Al-Cu-joints

NASA Astrophysics Data System (ADS)

Marstatt, R.; Krutzlinger, M.; Luderschmid, J.; Constanzi, G.; Mueller, J. F. J.; Haider, F.; Zaeh, M. F.

2018-06-01

Friction Stir Welding (FSW) can be performed to join dissimilar metal combinations like aluminium and copper, which is of high interest in modern production of electrical applications. The amount of intermetallic phases in the weld seam is significantly reduced compared to traditional fusion welding technologies. Because the solidus temperature is typically not reached during FSW, the growth of intermetallic phases is impeded and the intermetallic layer thicknesses typically remains on the scale of a few hundred nanometres. These layers provide a substance-to-substance bond, which is the main joining mechanism. Latest research confirms that the layer formation is most likely driven by the heat input during processing. Hence, the welding temperature is the key to achieve high quality joints. In this study, aluminium and copper sheets were welded in lap joint configuration using temperature-controlled FSW. An advanced in-tool measurement set-up was used to determine precise temperature data. Scanning electron microscopy (SEM) was used to analyse metallurgical aspects (e.g. structure and composition of the intermetallic phases) of the joints. The results show a correlation between the welding temperature and the thickness of the intermetallic layer and its structure. The temperature control significantly improved the correlation compared to previous studies. This leads to an enhanced understanding of the dominating joining mechanisms.

Differences in risk behaviours and HIV/STI prevalence between low-fee and medium-fee female sex workers in three provinces in China.

PubMed

Han, Lifeng; Zhou, Chu; Li, Zhijun; Poon, Adrienne N; Rou, Keming; Fuller, Serena; Li, Yan; Shen, Limei; Kang, Dianmin; Huang, Lu; Liao, Meizhen; Fu, Xiaobing; Shepard, Colin; Wu, Zunyou; Bulterys, Marc

2016-06-01

To better understand risk behaviours and factors associated with low-fee female sex workers (FSW) and support HIV/sexually transmitted infections (STI) epidemic control among this key population in China. A cross-sectional study using convenience sampling to recruit 1487 eligible low-fee and medium-fee FSW was conducted in 2012 in three provinces. The participants were interviewed using a structured questionnaire and tested for HIV-1, herpes simplex virus (HSV)-2 and syphilis antibody. Log-binomial modelling was used to estimate prevalence ratios (PR) and examine factors associated with low-fee sex work. Prevalence of HIV-1, syphilis and HSV-2 antibody positive were 0.5%, 4.8% and 27.8%, respectively. Low-fee FSW were more likely to have HSV-2 infection (adjusted prevalence ratio (APR)=1.3, 95% CI 1.1 to 1.7), but not more likely to have HIV-1 and syphilis infection compared with medium-fee FSW. Compared with medium-fee FSW, low-fee FSW were more likely to be ≥35 years of age (APR=2.1, 95% CI 1.3 to 3.6), engage in sex work ≥6 days/per week (APR=1.7, 95% CI 1.2 to 2.6), have ≥3 clients per day (APR=2.2, 95% CI 1.5 to 3.3), have clients decide condom use (APR=1.6, 95% CI 1.1 to 2.3), fail to persuade clients to use condoms (APR=1.6, 95% CI 1.1 to 2.6), express willingness to have unprotected sex in return for receipt of a higher fee (APR=1.8, 95% CI 1.2 to 2.8), have had genital symptoms in the past year (APR=1.4, 95% CI 1.1 to 1.8) and have migrated from another city. Low-fee FSW in China have unique risks for acquiring HIV/STI, in part due to greater economic pressures. Tailored interventions targeting low-fee FSW and incorporating their prevailing perception of HIV/STI risks and condom use negotiation challenges that they face are urgently needed. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The Software Design for the Wide-Field Infrared Explorer Attitude Control System

NASA Technical Reports Server (NTRS)

Anderson, Mark O.; Barnes, Kenneth C.; Melhorn, Charles M.; Phillips, Tom

1998-01-01

The Wide-Field Infrared Explorer (WIRE), currently scheduled for launch in September 1998, is the fifth of five spacecraft in the NASA/Goddard Small Explorer (SMEX) series. This paper presents the design of WIRE's Attitude Control System flight software (ACS FSW). WIRE is a momentum-biased, three-axis stabilized stellar pointer which provides high-accuracy pointing and autonomous acquisition for eight to ten stellar targets per orbit. WIRE's short mission life and limited cryogen supply motivate requirements for Sun and Earth avoidance constraints which are designed to prevent catastrophic instrument damage and to minimize the heat load on the cryostat. The FSW implements autonomous fault detection and handling (FDH) to enforce these instrument constraints and to perform several other checks which insure the safety of the spacecraft. The ACS FSW implements modules for sensor data processing, attitude determination, attitude control, guide star acquisition, actuator command generation, command/telemetry processing, and FDH. These software components are integrated with a hierarchical control mode managing module that dictates which software components are currently active. The lowest mode in the hierarchy is the 'safest' one, in the sense that it utilizes a minimal complement of sensors and actuators to keep the spacecraft in a stable configuration (power and pointing constraints are maintained). As higher modes in the hierarchy are achieved, the various software functions are activated by the mode manager, and an increasing level of attitude control accuracy is provided. If FDH detects a constraint violation or other anomaly, it triggers a safing transition to a lower control mode. The WIRE ACS FSW satisfies all target acquisition and pointing accuracy requirements, enforces all pointing constraints, provides the ground with a simple means for reconfiguring the system via table load, and meets all the demands of its real-time embedded environment (16 MHz Intel 80386 processor with 80387 coprocessor running under the VRTX operating system). The mode manager organizes and controls all the software modules used to accomplish these goals, and in particular, the FDH module is tightly coupled with the mode manager.

A Preliminary Report on the Strength and Metallography of a Bimetallic Friction Stir Weld Joint Between AA6061 and MIL-DTL-46100E High Hardness Steel Armor

DTIC Science & Technology

2012-11-26

alloy and High Hardness steel armor (MIL- STD-46100) were successfully joined by the friction stir welding (FSW) process using a tungsten- rhenium ...tungsten- rhenium stir tool. Process parameter variation experiments, which included inductive pre-heating, tool design geometry, plunge and traverse

Welding of Al6061and Al6082-Cu composite by friction stir processing

NASA Astrophysics Data System (ADS)

Iyer, R. B.; Dhabale, R. B.; Jatti, V. S.

2016-09-01

Present study aims at investigating the influence of process parameters on the microstructure and mechanical properties such as tensile strength and hardness of the dissimilar metal without and with copper powder. Before conducting the copper powder experiments, optimum process parameters were obtained by conducting experiments without copper powder. Taguchi's experimental L9 orthogonal design layout was used to carry out the experiments without copper powder. Threaded pin tool geometry was used for conducting the experiments. Based on the experimental results and Taguchi's analysis it was found that maximum tensile strength of 66.06 MPa was obtained at 1400 rpm spindle speed and weld speed of 20 mm/min. Maximum micro hardness (92 HV) was obtained at 1400 rpm spindle speed and weld speed of 16 mm/min. At these optimal setting of process parameters aluminium alloys were welded with the copper powder. Experimental results demonstrated that the tensile strength (96.54 MPa) and micro hardness (105 HV) of FSW was notably affected by the addition of copper powder when compared with FSW joint without copper powder. Tensile failure specimen was analysed using Scanning Electron Microscopy in order to study the failure mechanism.

Increasing Flight Software Reuse with OpenSatKit

NASA Technical Reports Server (NTRS)

McComas, David C.

2018-01-01

In January 2015 the NASA Goddard Space Flight Center (GSFC) released the Core Flight System (cFS) as open source under the NASA Open Source Agreement (NOSA) license. The cFS is based on flight software (FSW) developed for 12 spacecraft spanning nearly two decades of effort and it can provide about a third of the FSW functionality for a low-earth orbiting scientific spacecraft. The cFS is a FSW framework that is portable, configurable, and extendable using a product line deployment model. However, the components are maintained separately so the user must configure, integrate, and deploy them as a cohesive functional system. This can be very challenging especially for organizations such as universities building cubesats that have minimal experience developing FSW. Supporting universities was one of the primary motivators for releasing the cFS under NOSA. This paper describes the OpenSatKit that was developed to address the cFS deployment challenges and to serve as a cFS training platform for new users. It provides a fully functional out-of-the box software system that includes NASA's cFS, Ball Aerospace's command and control system COSMOS, and a NASA dynamic simulator called 42. The kit is freely available since all of the components have been released as open source. The kit runs on a Linux platform, includes 8 cFS applications, several kit-specific applications, and built in demos illustrating how to use key application features. It also includes the software necessary to port the cFS to a Raspberry Pi and instructions for configuring COSMOS to communicate with the target. All of the demos and test scripts can be rerun unchanged with the cFS running on the Raspberry Pi. The cFS uses a 3-tiered layered architecture including a platform abstraction layer, a Core Flight Executive (cFE) middle layer, and an application layer. Similar to smart phones, the cFS application layer is the key architectural feature for users to extend the FSW functionality to meet their mission-specific requirements. The platform abstraction layer and the cFE layers go a step further than smart phones by providing a platform-agnostic Application Programmer Interface (API) that allows applications to run unchanged on different platforms. OpenSatKit can serve two significant architectural roles that will further help the adoption of the cFS and help create a community of users that can share assets. First, the kit is being enhanced to automate the integration of applications with the goal of creating a virtual cFS "App Store".. Second, a platform certification test suite can be developed that would allow users to verify the port of the cFS to a new platform. This paper will describe the current state of these efforts and future plans.

Lay versus expert understandings of workplace risk in the food service industry: a multi-dimensional model with implications for participatory ergonomics.

PubMed

Cann, Adam P; MacEachen, Ellen; Vandervoort, Anthony A

2008-01-01

The recent trend towards cooperative management and prevention of workplace injuries has introduced numerous health and safety actors to the workplace with varying amounts and types of expertise. The purpose of this qualitative research project was to explore the understandings of risk as experienced by food service workers (FSW) and how these compare with an 'expert' in risk assessment. In total 13 FSW, selected based on age, work location, and gender, and one experienced Ergonomist participated in the study. In-depth semi-structured telephone interviews were conducted with each participant and transcripts of the interviews were analyzed using thematic analysis by drawing on methods closely related to grounded theory. The findings of this study indicated that the risks for occupational injury as experienced by FSW were multi-dimensional in nature representing not only the physical requirements of the individual's job, but also the social interactions of the FSW with their coworkers, management, and the organization. FSW were also found to be a rich source of knowledge and experience concerning occupational risk and may be under-utilized when designing interventions. The results of this study support a cooperative team approach to reduce the risks of injury in the workplace, with a specific emphasis on inclusion of the worker.

On the microstructure analysis of FSW joints of aluminium components made via direct metal laser sintering

NASA Astrophysics Data System (ADS)

Scherillo, Fabio; Astarita, Antonello; di Martino, Daniela; Contaldi, Vincenzo; di Matteo, Luca; di Petta, Paolo; Casarin, Renzo; Squillace, Antonino; Langella, Antonio

2017-10-01

Additive Manufacturing (AM), applied to metal industry, is a family of processes that allow complex shape components to be realized from raw materials in the form of powders. The compaction of the powders can be achieved by local melting of the powder bed or by solid state sintering. Direct Metal Laser Sintering (DMLS) is an additive manufacturing process in which a focalized laser beam is the heat source that allows the powders to be compacted. By DMLS it is possible to realize complex shape components. One of the limits of DMLS, as for every additive layer manufacturing techniques, is the unfeasibility to realize large dimension parts. Due to this limit the study of joining process of parts made via ALM is of great interest. One of the most promising options is the Friction Stir Welding (FSW), a solid state welding technique that has been proven to be very effective in the welding of metals difficult to weld, above all aluminium alloys. Since FSW is a solid-state technique, the microstructure of the various zone of the weld bead depends not only by the process itself but also by the parent microstruct ure of the parts to be welded. Furthermore, parts made of aluminium alloy via DMLS have a particular microstructure that is the result of repeated severe thermal cycles. In the present work the authors, starting from the description of the parent microstructure of parts made of AlSi10Mg aluminium alloy, study the microstructure evolution occurred within the joint made by Friction Stir Welding, analysing in details the microstructure of the main well recognized zone of the weld bead. The structure of the parent material is characterized by the presence of melting pools with a very fine microstructure. In the joint the recrystallization, the grain refinement and, above all, the redistribution of intermetallic phases occurs, resulting in an homogenization of the microstructure and in an increase of micro hardness.

Compression Buckling Behavior of Large-Scale Friction Stir Welded and Riveted 2090-T83 Al-Li Alloy Skin-Stiffener Panels

NASA Technical Reports Server (NTRS)

Hoffman, Eric K.; Hafley, Robert A.; Wagner, John A.; Jegley, Dawn C.; Pecquet, Robert W.; Blum, Celia M.; Arbegast, William J.

2002-01-01

To evaluate the potential of friction stir welding (FSW) as a replacement for traditional rivet fastening for launch vehicle dry bay construction, a large-scale friction stir welded 2090-T83 aluminum-lithium (Al-Li) alloy skin-stiffener panel was designed and fabricated by Lockheed-Martin Space Systems Company - Michoud Operations (LMSS) as part of NASA Space Act Agreement (SAA) 446. The friction stir welded panel and a conventional riveted panel were tested to failure in compression at the NASA Langley Research Center (LaRC). The present paper describes the compression test results, stress analysis, and associated failure behavior of these panels. The test results provide useful data to support future optimization of FSW processes and structural design configurations for launch vehicle dry bay structures.

Differential Evolution algorithm applied to FSW model calibration

NASA Astrophysics Data System (ADS)

Idagawa, H. S.; Santos, T. F. A.; Ramirez, A. J.

2014-03-01

Friction Stir Welding (FSW) is a solid state welding process that can be modelled using a Computational Fluid Dynamics (CFD) approach. These models use adjustable parameters to control the heat transfer and the heat input to the weld. These parameters are used to calibrate the model and they are generally determined using the conventional trial and error approach. Since this method is not very efficient, we used the Differential Evolution (DE) algorithm to successfully determine these parameters. In order to improve the success rate and to reduce the computational cost of the method, this work studied different characteristics of the DE algorithm, such as the evolution strategy, the objective function, the mutation scaling factor and the crossover rate. The DE algorithm was tested using a friction stir weld performed on a UNS S32205 Duplex Stainless Steel.

Investigation of effects of process parameters on properties of friction stir welded joints

NASA Astrophysics Data System (ADS)

Chauhan, Atul; Soota, Tarun; Rajput, S. K.

2018-03-01

This work deals with application of friction stir welding (FSW) using application of Taguchi orthogonal array. FSW procedure is used for joining the aluminium alloy AA6063-T0 plates in butt configuration with orthogonal combination of factors and their levels. The combination of factors involving tool rotation speed, tool travel speed and tool pin profile are used in three levels. Grey relational analysis (GRA) has been applied to select optimum level of factors for optimising UTS, ductility and hardness of joint. Experiments have been conducted with two different tool materials (HSS and HCHCr steel) with various factors level combinations for joining AA6063-T0. On the basis of grey relational grades at different levels of factors and analysis of variance (ANOVA) ideal combination of factors are determined. The influence of tool material is also studied.

Investigation of Abnormal Grain Growth in a Friction Stir Welded and Spin-Formed Al-Li Alloy 2195 Crew Module

NASA Technical Reports Server (NTRS)

Tayon, Wesley A.; Domack, Marcia S.; Hoffman, Eric K.; Hales, Stephen J.

2013-01-01

In order to improve manufacturing efficiency and reduce structural mass and costs in the production of launch vehicle structures, NASA is pursuing a wide-range of innovative, near-net shape manufacturing technologies. A technology that combines friction stir welding (FSW) and spin-forming has been applied to manufacture a single-piece crew module using Aluminum-Lithium (AL-Li) Alloy 2195. Plate size limitations for Al-Li alloy 2195 require that two plates be FSW together to produce a spin-forming blank of sufficient size to form the crew module. Subsequent forming of the FSW results in abnormal grain growth (AGG) within the weld region upon solution heat treatment (SHT), which detrimentally impacts strength, ductility, and fracture toughness. The current study seeks to identify microstructural factors that contribute to the development of AGG. Electron backscatter diffraction (EBSD) was used to correlate driving forces for AGG, such as stored energy, texture, and grain size distributions, with the propensity for AGG. Additionally, developmental annealing treatments prior to SHT are examined to reduce or eliminate the occurrence of AGG by promoting continuous, or uniform, grain growth

Population size estimation of female sex workers in Iran: Synthesis of methods and results.

PubMed

Sharifi, Hamid; Karamouzian, Mohammad; Baneshi, Mohammad Reza; Shokoohi, Mostafa; Haghdoost, AliAkbar; McFarland, Willi; Mirzazadeh, Ali

2017-01-01

Estimating the number of key populations at risk of HIV is essential for planning, monitoring, and evaluating prevention, care, and treatment programmes. We conducted this study to estimate the number of female sex workers (FSW) in major cities of Iran. We used three population size estimation methods (i.e., wisdom of the crowds, multiplier method, and network scale-up) to calculate the number of FSW in 13 cities in Iran. The wisdom of the crowds and multiplier methods were integrated into a nationwide bio-behavioural surveillance survey in 2015, and the network scale-up method was included in a national survey of the general population in 2014. The median of the three methods was used to calculate the proportion of the adult female population who practice sex work in the 13 cities. These figures were then extrapolated to provide a national population size estimation of FSW across urban areas. The population size of FSW was 91,500 (95% Uncertainty Intervals [UIs] 61,400-117,700), corresponding to 1.43% (95% UIs 0.96-1.84) of the adult (i.e., 15-49 year-old) female population living in these 13 cities. The projected numbers of FSW for all 31 provincial capital cities were 130,800 (95% UIs 87,800-168,200) and 228,700 (95% UIs 153,500-294,300) for all urban settings in Iran. Using methods of comparable rigor, our study provided a data-driven national estimate of the population size of FSW in urban areas of Iran. Our findings provide vital information for enhancing HIV programme planning and lay a foundation for assessing the impact of harm reduction efforts within this marginalized population.

Population size estimation of female sex workers in Iran: Synthesis of methods and results

PubMed Central

Sharifi, Hamid; Karamouzian, Mohammad; Baneshi, Mohammad Reza; Shokoohi, Mostafa; Haghdoost, AliAkbar; McFarland, Willi

2017-01-01

Introduction Estimating the number of key populations at risk of HIV is essential for planning, monitoring, and evaluating prevention, care, and treatment programmes. We conducted this study to estimate the number of female sex workers (FSW) in major cities of Iran. Methods We used three population size estimation methods (i.e., wisdom of the crowds, multiplier method, and network scale-up) to calculate the number of FSW in 13 cities in Iran. The wisdom of the crowds and multiplier methods were integrated into a nationwide bio-behavioural surveillance survey in 2015, and the network scale-up method was included in a national survey of the general population in 2014. The median of the three methods was used to calculate the proportion of the adult female population who practice sex work in the 13 cities. These figures were then extrapolated to provide a national population size estimation of FSW across urban areas. Results The population size of FSW was 91,500 (95% Uncertainty Intervals [UIs] 61,400–117,700), corresponding to 1.43% (95% UIs 0.96–1.84) of the adult (i.e., 15–49 year-old) female population living in these 13 cities. The projected numbers of FSW for all 31 provincial capital cities were 130,800 (95% UIs 87,800–168,200) and 228,700 (95% UIs 153,500–294,300) for all urban settings in Iran. Conclusions Using methods of comparable rigor, our study provided a data-driven national estimate of the population size of FSW in urban areas of Iran. Our findings provide vital information for enhancing HIV programme planning and lay a foundation for assessing the impact of harm reduction efforts within this marginalized population. PMID:28796847

High prevalence of unhealthy alcohol use and comparison of self-reported alcohol consumption to phosphatidylethanol among women engaged in sex work and their male clients in Cambodia

PubMed Central

Couture, Marie-Claude; Page, Kimberly; Sansothy, Neth; Stein, Ellen; Vun, Mean Chhi; Hahn, Judith A

2017-01-01

Background In Cambodia, most of the female sex workers (FSW) work in venues where unhealthy alcohol use is ubiquitous and potentially contributing to the HIV epidemic. However, no accurate data exists. We compare self-reported unhealthy alcohol consumption to a biomarker of alcohol intake in Cambodian FSW and male clients, and determine factors associated with unhealthy alcohol use. Methods A cross-sectional study was conducted among FSW (n=100) and male clients (n=100) in entertainment and sex work venues in Cambodia. Self-reported unhealthy alcohol use (AUDIT-C) was compared to phosphatidylethanol (PEth) positive (≥50ng/ml), a biomarker of alcohol intake. Sociodemographics data was collected. Correlates of self-reported unhealthy alcohol use and PEth positive were determined. Results The prevalence of PEth positive in FSW was 60.0%. Self-reported unhealthy alcohol consumption was reported by 85.0% of the women. Almost all women (95.0%) testing PEth positive also reported unhealthy alcohol use. Prevalence of unhealthy alcohol consumption (self-report and PEth positive) was higher in FSW working in entertainment establishments compared to other sex work venues (p<0.01). Among male clients, 47.0% reported unhealthy alcohol consumption and 42.0% had a PEth positive. However, only 57.1% of male clients with PEth positive reported unhealthy alcohol use. Conclusions Unhealthy alcohol consumption is prevalent in Cambodian sex work settings. Self-reported unhealthy alcohol use is well reported by FSW, but less by male clients. These findings highlight the urgency of using accurate measures of unhealthy alcohol consumption and integrating this health issue into HIV prevention interventions. PMID:27251102

High prevalence of unhealthy alcohol use and comparison of self-reported alcohol consumption to phosphatidylethanol among women engaged in sex work and their male clients in Cambodia.

PubMed

Couture, Marie-Claude; Page, Kimberly; Sansothy, Neth; Stein, Ellen; Vun, Mean Chhi; Hahn, Judith A

2016-08-01

In Cambodia, most of the female sex workers (FSW) work in venues where unhealthy alcohol use is ubiquitous and potentially contributing to the HIV epidemic. However, no accurate data exists. We compare self-reported unhealthy alcohol consumption to a biomarker of alcohol intake in Cambodian FSW and male clients, and determine factors associated with unhealthy alcohol use. A cross-sectional study was conducted among FSW (n=100) and male clients (n=100) in entertainment and sex work venues in Cambodia. Self-reported unhealthy alcohol use (AUDIT-C) was compared to phosphatidylethanol (PEth) positive (≥50ng/ml), a biomarker of alcohol intake. Sociodemographics data was collected. Correlates of self-reported unhealthy alcohol use and PEth positive were determined. The prevalence of PEth positive in FSW was 60.0%. Self-reported unhealthy alcohol consumption was reported by 85.0% of the women. Almost all women (95.0%) testing PEth positive also reported unhealthy alcohol use. Prevalence of unhealthy alcohol consumption (self-report and PEth positive) was higher in FSW working in entertainment establishments compared to other sex work venues (p<0.01). Among male clients, 47.0% reported unhealthy alcohol consumption and 42.0% had a PEth positive. However, only 57.1% of male clients with PEth positive reported unhealthy alcohol use. Unhealthy alcohol consumption is prevalent in Cambodian sex work settings. Self-reported unhealthy alcohol use is well reported by FSW, but less by male clients. These findings highlight the urgency of using accurate measures of unhealthy alcohol consumption and integrating this health issue into HIV prevention interventions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

HIV risk behaviors differ by workplace stability among Mexican female sex workers with truck driver clientele.

PubMed

Chen, Nadine E; Strathdee, Steffanie A; Rangel, Gudelia; Patterson, Thomas L; Uribe-Salas, Felipe J; Rosen, Perth; Villalobos, Jorge; Brouwer, Kimberly C

2012-12-28

In a study of female sex workers (FSW) servicing truck driver clients in Mexican border cities, we evaluated differences in HIV/STI risk behaviors by workplace. Cross-sectional study of FSW servicing truck drivers in Mexico: 100 from Nuevo Laredo (U.S. border); 100 from Ciudad Hidalgo (Guatemalan border). Main outcome was unstable workplace, defined as primary place of sex work in a public place (street, vehicle, gas station, etc.) vs. stable workplace (bar, brothel, and hotel). Logistic regression was used to identify correlates associated with trading sex at unstable workplaces in the last month. Of the FSW surveyed, 18% reported an unstable workplace. The majority of FSW surveyed were young (<30), single, had <9 th grade education, and had worked in the sex trade for a median of 4.9 years. After controlling for study site, FSW with unstable vs. stable workplaces were more likely to have a majority/all truck driver clientele, but were less likely to have visited a gynecologist in the last year (OR 0.1, 95%CI 0.03-0.4) or ever had an HIV test (OR 0.1, 95%CI 0.06-0.3), and there was a trend towards lower condom use self-efficacy scores (OR 0.8 per unit increase, 95%CI 0.7-1.0). On multivariate regression, unstable workplace was associated with having majority/all truck driver clientele, being surveyed in Nuevo Laredo, and decreased odds of ever having an HIV test. Among Mexican FSW with truck driver clients, providing safe indoor spaces for sex work may help facilitate public health interventions that improve HIV/STI and reproductive health outcomes.

Friction Stir Process Mapping Methodology

NASA Technical Reports Server (NTRS)

Kooney, Alex; Bjorkman, Gerry; Russell, Carolyn; Smelser, Jerry (Technical Monitor)

2002-01-01

In FSW (friction stir welding), the weld process performance for a given weld joint configuration and tool setup is summarized on a 2-D plot of RPM vs. IPM. A process envelope is drawn within the map to identify the range of acceptable welds. The sweet spot is selected as the nominal weld schedule. The nominal weld schedule is characterized in the expected manufacturing environment. The nominal weld schedule in conjunction with process control ensures a consistent and predictable weld performance.

Accuracy of HIV-related risk behaviors reported by female sex workers, Iran: a method to quantify measurement bias in marginalized populations.

PubMed

Mirzazadeh, Ali; Haghdoost, Ali Akbar; Nedjat, Saharnaz; Navadeh, Soodabeh; McFarland, Willi; Mohammad, Kazem

2013-02-01

We quantified discrepancies in reported behaviors of female sex workers (FSW) by comparing 63 face-to-face interviews (FTFI) to in-depth interviews (IDI), with corroboration of the directions and magnitudes of reporting by a panel of psychologists who work with FSW. Sensitivities, specificities, positive and negative predictive values (PPV and NPV) were assessed for FTFI responses using IDI as a "gold standard". Sensitivities were lowest in reporting symptoms of sexually transmitted infections (63.9 %), finding sex partners in venues (52.4 %) and not receiving HIV test results (66.7 %). Specificities (all >83 %) and PPVs (all >74.0 %) were higher than NPV. FSW significantly under-reported number of clients, sexual contacts and non-condom use sex acts with clients and number of days engaging in sex work in the preceding week. This study provides a quantified gauge of reporting biases in FSW behaviors. Such estimates and methods help better understand true HIV risk in marginalized populations and calibrate survey estimates accordingly.

Understanding STI Risk and Condom Use Patterns by Partner Type Among Female Sex Workers in Peru.

PubMed

Kinsler, Janni J; Blas, Magaly M; Cabral, Alejandra; Carcamo, Cesar; Halsey, Neal; Brown, Brandon

2014-01-01

While brothel-based sex work is regulated by the Peruvian government, there is little data on STI risk factors reported by female sex workers (FSW). This study compared high risk behaviors among 120 Peruvian FSW from government regulated brothels with both clients and non-commercial partners. Our study found that 12% of FSW reported unprotected vaginal sex with clients (compared to 75% with non-commercial partners), and 42% reported unprotected anal sex with clients (compared to 87% with non-commercial partners). Group differences were observed in the expectation to have oral sex (32% for partners vs 60% for clients; p<0.01), and a history of anal sex (65% for partners vs 32% for clients; p<0.01) and both vaginal and anal sex with the same partners (46% for partners vs 25% for clients; p<0.001). These findings suggest that FSW constitute an important bridge population for STI/HIV transmission in Peru.

Community Savings Groups, Financial Security, and HIV Risk Among Female Sex Workers in Iringa, Tanzania.

PubMed

Mantsios, Andrea; Galai, Noya; Mbwambo, Jessie; Likindikoki, Samuel; Shembilu, Catherine; Mwampashi, Ard; Beckham, S W; Leddy, Anna; Davis, Wendy; Sherman, Susan; Kennedy, Caitlin; Kerrigan, Deanna

2018-02-24

This study assessed the association between community savings group participation and consistent condom use (CCU) among female sex workers (FSW) in Iringa, Tanzania. Using cross-sectional data from a survey of venue-based FSW (n = 496), logistic regression was used to examine the associations between financial indicators including community savings group participation and CCU. Over one-third (35%) of the women participated in a savings group. Multivariable regression results indicated that participating in a savings group was significantly associated with nearly two times greater odds of CCU with new clients in the last 30 days (aOR = 1.77, 95% CI 1.10-2.86). Exploratory mediation analysis indicated that the relationship between savings group participation and CCU was partially mediated by financial security, as measured by monthly income. Findings indicate that community savings groups may play an important role in reducing sexual risk behaviors of FSW and hold promise as part of comprehensive, community-led HIV prevention strategies among FSW.

Reconceptualizing the HIV epidemiology and prevention needs of Female Sex Workers (FSW) in Swaziland.

PubMed

Baral, Stefan; Ketende, Sosthenes; Green, Jessie L; Chen, Ping-An; Grosso, Ashley; Sithole, Bhekie; Ntshangase, Cebisile; Yam, Eileen; Kerrigan, Deanna; Kennedy, Caitlin E; Adams, Darrin

2014-01-01

HIV is hyperendemic in Swaziland with a prevalence of over 25% among those between the ages of 15 and 49 years old. The HIV response in Swaziland has traditionally focused on decreasing HIV acquisition and transmission risks in the general population through interventions such as male circumcision, increasing treatment uptake and adherence, and risk-reduction counseling. There is emerging data from Southern Africa that key populations such as female sex workers (FSW) carry a disproportionate burden of HIV even in generalized epidemics such as Swaziland. The burden of HIV and prevention needs among FSW remains unstudied in Swaziland. A respondent-driven-sampling survey was completed between August-October, 2011 of 328 FSW in Swaziland. Each participant completed a structured survey instrument and biological HIV and syphilis testing according to Swazi Guidelines. Unadjusted HIV prevalence was 70.3% (n = 223/317) among a sample of women predominantly from Swaziland (95.2%, n = 300/316) with a mean age of 21(median 25) which was significantly higher than the general population of women. Approximately one-half of the FSW(53.4%, n = 167/313) had received HIV prevention information related to sex work in the previous year, and about one-in-ten had been part of a previous research project(n = 38/313). Rape was common with nearly 40% (n = 123/314) reporting at least one rape; 17.4% (n = 23/314)reported being raped 6 or more times. Reporting blackmail (34.8%, n = 113/314) and torture(53.2%, n = 173/314) was prevalent. While Swaziland has a highly generalized HIV epidemic, reconceptualizing the needs of key populations such as FSW suggests that these women represent a distinct population with specific vulnerabilities and a high burden of HIV compared to other women. These women are understudied and underserved resulting in a limited characterization of their HIV prevention, treatment, and care needs and only sparse specific and competent programming. FSW are an important population for further investigation and rapid scale-up of combination HIV prevention including biomedical, behavioral, and structural interventions.

Constitutive model of friction stir weld with consideration of its inhomogeneous mechanical properties

NASA Astrophysics Data System (ADS)

Zhang, Ling; Min, Junying; Wang, Bin; Lin, Jianping; Li, Fangfang; Liu, Jing

2016-03-01

In practical engineering, finite element(FE) modeling for weld seam is commonly simplified by neglecting its inhomogeneous mechanical properties. This will cause a significant loss in accuracy of FE forming analysis, in particular, for friction stir welded(FSW) blanks due to the large width and good formability of its weld seam. The inhomogeneous mechanical properties across weld seam need to be well characterized for an accurate FE analysis. Based on a similar AA5182 FSW blank, the metallographic observation and micro-Vickers hardness analysis upon the weld cross-section are performed to identify the interfaces of different sub-zones, i.e., heat affected zone(HAZ), thermal-mechanically affected zone(TMAZ) and weld nugget(WN). Based on the rule of mixture and hardness distribution, a constitutive model is established for each sub-zone to characterize the inhomogeneous mechanical properties across the weld seam. Uniaxial tensile tests of the AA5182 FSW blank are performed with the aid of digital image correlation(DIC) techniques. Experimental local stress-strain curves are obtained for different weld sub-zones. The experimental results show good agreement with those derived from the constitutive models, which demonstrates the feasibility and accuracy of these models. The proposed research gives an accurate characterization of inhomogeneous mechanical properties across the weld seam produced by FSW, which provides solutions for improving the FE simulation accuracy of FSW sheet forming.

Measurement and analysis of applied power, forces and material response in friction stir welding of aluminum alloy 6061

NASA Astrophysics Data System (ADS)

Avila, Ricardo E.

The process of Friction Stir Welding (FSW) 6061 aluminum alloy is investigated, with focus on the forces and power being applied in the process and the material response. The main objective is to relate measurements of the forces and power applied in the process with mechanical properties of the material during the dynamic process, based on mathematical modeling and aided by computer simulations, using the LS-DYNA software for finite element modeling. Results of measurements of applied forces and power are presented. The result obtained for applied power is used in the construction of a mechanical variational model of FSW, in which minimization of a functional for the applied torque is sought, leading to an expression for shear stress in the material. The computer simulations are performed by application of the Smoothed Particle Hydrodynamics (SPH) method, in which no structured finite element mesh is used to construct a spatial discretization of the model. The current implementation of SPH in LS-DYNA allows a structural solution using a plastic kinematic material model. This work produces information useful to improve understanding of the material flow in the process, and thus adds to current knowledge about the behavior of materials under processes of severe plastic deformation, particularly those processes in which deformation occurs mainly by application of shear stress, aided by thermoplastic strain localization and dynamic recrystallization.

29 CFR 1910.427 - Liveboating.

Code of Federal Regulations, 2010 CFR

2010-07-01

... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving Operations Specific Operations Procedures § 1910.427... of 220 fsw; (3) Using mixed gas at depths greater than 220 fsw; (4) In rough seas which significantly... while a diver is in the water. (5) A diver-carried reserve breathing gas supply shall be carried by each...

Microstructure and Mechanical Characterization of Friction-Stir-Welded Dual-Phase Brass

NASA Astrophysics Data System (ADS)

Ramesh, R.; Dinaharan, I.; Akinlabi, E. T.; Murugan, N.

2018-03-01

Friction stir welding (FSW) is an ideal process to join brass to avoid the evaporation of zinc. In the present investigation, 6-mm-thick dual-phase brass plates were joined efficiently using FSW at various tool rotational speeds. The microstructures were studied using optical microscopy, electron backscattered diffraction and transmission electron microscopy. The optical micrographs revealed the evolution of various zones across the joint line. The microstructure of the heat-affected zone was similar to that of base metal. The weld zone exhibited finer grains due to dynamic recrystallization. The recrystallization was inhomogeneous and the inhomogeneity reduced with increased tool rotational speed. The dual phase was preserved in the weld zone due to the retention of zinc. The severe plastic deformation created a lot of dislocations in the weld zone. The weld zone was strengthened after welding. The role of tool rotational speed on the joint strength is further reported.

Spatially resolved positron annihilation spectroscopy on friction stir weld induced defects.

PubMed

Hain, Karin; Hugenschmidt, Christoph; Pikart, Philip; Böni, Peter

2010-04-01

A friction stir welded (FSW) Al alloy sample was investigated by Doppler broadening spectroscopy (DBS) of the positron annihilation line. The spatially resolved defect distribution showed that the material in the joint zone becomes completely annealed during the welding process at the shoulder of the FSW tool, whereas at the tip, annealing is prevailed by the deterioration of the material due to the tool movement. This might be responsible for the increased probability of cracking in the heat affected zone of friction stir welds. Examination of a material pairing of steel S235 and the Al alloy Silafont36 by coincident Doppler broadening spectroscopy (CDBS) indicates the formation of annealed steel clusters in the Al alloy component of the sample. The clear visibility of Fe in the CDB spectra is explained by the very efficient trapping at the interface between steel cluster and bulk.

Effect of Exchanging Advancing and Retreating Side Materials on Mechanical Properties and Electrochemical Corrosion Resistance of Dissimilar 6013-T4 and 7003 Aluminum Alloys FSW Joints

NASA Astrophysics Data System (ADS)

Zhao, Zhixia; Liang, Haimei; Zhao, Yong; Yan, Keng

2018-03-01

Friction stir welding (FSW) was used to weld dissimilar joints between Al 6013-T4 and Al7003 alloys in this work. The effect of exchanging advancing (AS) and retreating (RS) side material on microstructure, mechanical behaviors and electrochemical corrosion resistance was discussed. Results showed that different joint cross sections were obtained when exchanging AS and RS materials. The material on the AS would be more deformed during the welding process. When the Al6013 placed on the AS, the plastic flow of weld is more sufficient. Whether on the AS or RS, the Al6013-T4 side is the weak region for both tensile specimens and hardness samples. The fracture position corresponds to the minimum hardness position. Also, more strengthening phase can be retained in the joint, and the joint of A6R7 has better corrosion resistance.

Detection and assessment of flaws in friction stir welded metallic plates

NASA Astrophysics Data System (ADS)

Fakih, Mohammad Ali; Mustapha, Samir; Tarraf, Jaafar; Ayoub, Georges; Hamade, Ramsey

2017-04-01

Investigated is the ability of ultrasonic guided waves to detect flaws and assess the quality of friction stir welds (FSW). AZ31B magnesium plates were friction stir welded. While process parameters of spindle speed and tool feed were fixed, shoulder penetration depth was varied resulting in welds of varying quality. Ultrasonic waves were excited at different frequencies using piezoelectric wafers and the fundamental symmetric (S0) mode was selected to detect the flaws resulting from the welding process. The front of the first transmitted wave signal was used to capture the S0 mode. A damage index (DI) measure was defined based on the amplitude attenuation after wave interaction with the welded zone. Computed Tomography (CT) scanning was employed as a nondestructive testing (NDT) technique to assess the actual weld quality. Derived DI values were plotted against CT-derived flaw volume resulting in a perfectly linear fit. The proposed approach showed high sensitivity of the S0 mode to internal flaws within the weld. As such, this methodology bears great potential as a future predictive method for the evaluation of FSW weld quality.

The Plastic Flow Field in the Vicinity of the Pin-Tool During Friction Stir Welding

NASA Technical Reports Server (NTRS)

Bernstein, E. L.; Nunes, A. C., Jr.

2000-01-01

The plastic flow field in the vicinity of the pin-tool during Friction Stir Welding (FSW) needs to be understood if a theoretical understanding of the process is to be attained. The structure of welds does not exhibit the flow field itself, but consists in a residue of displacements left by the plastic flow field. The residue requires analysis to extract from it the instantaneous flow field around the pin-tool. A simplified merry-go-round model makes sense of some tracer experiments reported in the literature. A quantitative comparison is made of the displacements of copper wire markers with displacements computed from a hypothetical plastic flow field. The hypothetical plastic flow field consists in a circular rotation field about a translating pin tool with angular velocity varying with radius from the pin centerline. A sharply localized rotational field comprising slip on a surface around the tool agreed better with observations than a distributed slip field occupying a substantial volume around the tool. Both the tracer and the wire displacements support the "rotating plug" model, originally invoked or thermal reasons, of the FSW process.

Friction Stir Weld Inspection Through Conductivity Imaging Using Shaped Field MWM(Registered Trademark) - Arrays

NASA Technical Reports Server (NTRS)

Goldfine, Neil; Grundy, David; Zilberstein, Vladimir; Kinchen, David G.; McCool, Alex (Technical Monitor)

2002-01-01

Friction Stir Welds (FSW) of Al 2195-T8 and Al 2219-T8, provided by Lockheed Martin Michoud Operations, were inspected for lack-of-penetration (LOP) defects using a custom designed MWM-Array, a multi-element eddy-current sensor. MWM (registered trademark) electrical conductivity mapping demonstrated high sensitivity to LOP as small as 0.75 mm (0.03 in.), as confirmed by metallographic data that characterized the extent of LOP defects. High sensitivity and high spatial resolution was achieved via a 37-element custom designed MWM-Array allowing LOP detection using the normalized longitudinal component of the MWM measured conductivity. This permitted both LOP detection and correlation of MWM conductivity features with the LOP defect size, as changes in conductivity were apparently associated with metallurgical features within the near-surface layer of the LOP defect zone. MWM conductivity mapping reveals information similar to macro-etching as the MWM-Array is sensitive to small changes in conductivity due to changes in microstructure associated with material thermal processing, in this case welding. The electrical conductivity measured on the root side of FSWs varies across the weld due to microstructural differences introduced by the FSW process, as well as those caused by planar flaws. Weld metal, i.e., dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMZ), heat-affected zone (HAZ), and parent metal (PM) are all evident in the conductivity maps. While prior efforts had met with limited success for NDE (Nondestructive Evaluation) of dissimilar alloy, Al2219 to Al2195 FSW, the new custom designed multi-element MWM-Array achieved detection of all LOP defects even in dissimilar metal welds.

The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Z.L., E-mail: zhilihuhit@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology

Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that themore » tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.« less

The relationship between health worker stigma and uptake of HIV counseling and testing and utilization of non-HIV health services: the experience of male and female sex workers in Kenya.

PubMed

Nyblade, Laura; Reddy, Aditi; Mbote, David; Kraemer, John; Stockton, Melissa; Kemunto, Caroline; Krotki, Karol; Morla, Javier; Njuguna, Stella; Dutta, Arin; Barker, Catherine

2017-11-01

The barrier HIV-stigma presents to the HIV treatment cascade is increasingly documented; however less is known about female and male sex worker engagement in and the influence of sex-work stigma on the HIV care continuum. While stigma occurs in all spheres of life, stigma within health services may be particularly detrimental to health seeking behaviors. Therefore, we present levels of sex-work stigma from healthcare workers (HCW) among male and female sex workers in Kenya, and explore the relationship between sex-work stigma and HIV counseling and testing. We also examine the relationship between sex-work stigma and utilization of non-HIV health services. A snowball sample of 497 female sex workers (FSW) and 232 male sex workers (MSW) across four sites was recruited through a modified respondent-driven sampling process. About 50% of both male and female sex workers reported anticipating verbal stigma from HCW while 72% of FSW and 54% of MSW reported experiencing at least one of seven measured forms of stigma from HCW. In general, stigma led to higher odds of reporting delay or avoidance of counseling and testing, as well as non-HIV specific services. Statistical significance of relationships varied across type of health service, type of stigma and gender. For example, anticipated stigma was not a significant predictor of delay or avoidance of health services for MSW; however, FSW who anticipated HCW stigma had significantly higher odds of avoiding (OR = 2.11) non-HIV services, compared to FSW who did not. This paper adds to the growing evidence of stigma as a roadblock in the HIV treatment cascade, as well as its undermining of the human right to health. While more attention is being paid to addressing HIV-stigma, it is equally important to address the key population stigma that often intersects with HIV-stigma.

Laser Peening Effects on Friction Stir Welding

NASA Technical Reports Server (NTRS)

Hatameleh, Omar

2009-01-01

The laser peening process can result in considerable improvement to crack initiation, propagation, and mechanical properties in FSW which equates to longer hardware service life Processed hardware safety is improved by producing higher failure tolerant hardware, and reducing risk. Lowering hardware maintenance cost produces longer hardware service life, and lower hardware down time. Application of this proposed technology will result in substantial benefits and savings throughout the life of the treated components

Increasing Flight Software Reuse with OpenSatKit

NASA Technical Reports Server (NTRS)

McComas, David

2018-01-01

In January 2015 the NASA Goddard Space Flight Center (GSFC) released the Core Flight System (cFS) as open source under the NASA Open Source Agreement (NOSA) license. The cFS is based on flight software (FSW) developed for 12 spacecraft spanning nearly two decades of effort and it can provide about a third of the FSW functionality for a low-earth orbiting scientific spacecraft. The cFS is a FSW framework that is portable, configurable, and extendable using a product line deployment model. However, the components are maintained separately so the user must configure, integrate, and deploy them as a cohesive functional system. This can be very challenging especially for organizations such as universities building cubesats that have minimal experience developing FSW. Supporting universities was one of the primary motivators for releasing the cFS under NOSA. This paper describes the OpenSatKit that was developed to address the cFS deployment challenges and to serve as a cFS training platform for new users. It provides a fully functional out-of-the box software system that includes NASA's cFS, Ball Aerospaceâ€"TM"s command and control system COSMOS, and a NASA dynamic simulator called 42. The kit is freely available since all of the components have been released as open source. The kit runs on a Linux platform, includes 8 cFS applications, several kit-specific applications, and built in demos illustrating how to use key application features. It also includes the software necessary to port the cFS to a Raspberry Pi and instructions for configuring COSMOS to communicate with the target. All of the demos and test scripts can be rerun unchanged with the cFS running on the Raspberry Pi. The cFS uses a 3-tiered layered architecture including a platform abstraction layer, a Core Flight Executive (cFE) middle layer, and an application layer. Similar to smart phones, the cFS application layer is the key architectural feature for userâ€"TM"s to extend the FSW functionality to meet their mission-specific requirements. The platform abstraction layer and the cFE layers go a step further than smart phones by providing a platform-agnostic Application Programmer Interface (API) that allows applications to run unchanged on different platforms. OpenSatKit can serve two significant architectural roles that will further help the adoption of the cFS and help create a community of users that can share assets. First, the kit is being enhanced to automate the integration of applications with the goal of creating a virtual cFS 'App Store'. Second, a platform certification test suite can be developed that would allow users to verify the port of the cFS to a new platform. This paper will describe the current state of these efforts and future plans.

Structural determinants of client perpetrated violence among female sex workers in two Mexican-U.S. border cities

PubMed Central

Conners, Erin E.; Silverman, Jay G.; Ulibarri, Monica; Magis-Rodriguez, Carlos; Strathdee, Steffanie A.; Staines-Orozco, Hugo; Patterson, Thomas L.; Brouwer, Kimberly C.

2015-01-01

Female sex workers (FSW) are disproportionately affected by both HIV and gender-based violence, such as that perpetrated by clients (CPV). We used a structural determinants framework to assess correlates of physical or sexual CPV in the past 6 months among FSW in the Mexico/U.S. border cities of Ciudad Juárez and Tijuana. Bivariate and multivariate logistic regression analysis identified individual, client, interpersonal, work environment and macrostructural factors associated with recent CPV. Among 496 FSW, 5% experienced recent CPV. Witnessing violence towards other FSW in one's neighborhood (aOR:5.6, 95% CI:1.8-17.2), having a majority of foreign (aOR:3.5, 95% CI:1.4-8.4) or substance using (aOR:4.0, 95% CI:1.5-10.4) clients, and being a street worker (aOR:3.0, 95% CI:1.1-7.7) were independently associated with recent CPV. Our findings underscore the vulnerability of FSWs and the need to design policies and interventions addressing macro-level influences on CPV rather than exclusively targeting individual behaviors. PMID:26111732

In-Situ Neutron Diffraction Studies of Micromechanical Behavior in a Friction Stir Welded AA7475-T761

NASA Astrophysics Data System (ADS)

Liu, X. P.; Lin Peng, R.; Hofmann, M.; Johansson, S.; Wang, Y. D.

2011-01-01

An in-situ neutron diffraction technique was used to investigate the lattice strain distributions and micromechanical behavior in a friction stir welded (FSW) sheet of AA7475-T761. The neutron diffraction experiments were performed on the spectrometer for material research, STRESS-SPEC, at FRM II (Garching, Germany). The lattice strain profiles around the weld center were measured as a function of the applied strain during the tensile loading and unloading. The anisotropic elastic and plastic properties of the FSW aluminum alloy were simulated by elasto-plastic self-consistent (EPSC) model to predict the anisotropic deformation behaviors involving the grain-to-grain interactions. Material parameters used for describing the constitutive laws of each test position were determined from the measured lattice strain distributions for different diffraction hkl planes as well as the macroscopic stress-strain curve of the FSW aluminum alloy. A good agreement between experimental results and numerical simulations was obtained. The present investigations provided a reliable prediction of the anisotropic micromechanical behavior of the FSW aluminum alloy during tensile deformation.

Transactional sex risk across a typology of rural and urban female sex workers in Indonesia: a mixed methods study.

PubMed

Puradiredja, Dewi Ismajani; Coast, Ernestina

2012-01-01

Context-specific typologies of female sex workers (FSWs) are essential for the design of HIV intervention programming. This study develops a novel FSW typology for the analysis of transactional sex risk in rural and urban settings in Indonesia. Mixed methods include a survey of rural and urban FSWs (n=310), in-depth interviews (n=11), key informant interviews (n=5) and ethnographic assessments. Thematic analysis categorises FSWs into 5 distinct groups based on geographical location of their sex work settings, place of solicitation, and whether sex work is their primary occupation. Multiple regression analysis shows that the likelihood of consistent condom use was higher among urban venue-based FSWs for whom sex work is not the only source of income than for any of the other rural and urban FSW groups. This effect was explained by the significantly lower likelihood of consistent condom use by rural venue-based FSWs (adjusted OR: 0.34 95% CI 0.13-0.90, p=0.029). The FSW typology and differences in organisational features and social dynamics are more closely related to the risk of unprotected transactional sex, than levels of condom awareness and availability. Interventions need context-specific strategies to reach the different FSWs identified by this study's typology.

Unpacking the ‘structural’ in a structural approach for HIV prevention among female sex workers: A case study from China

PubMed Central

Huang, Yingying; Muessig, Kathryn E.; Zhang, Ning; Maman, Suzanne

2015-01-01

Interventions for HIV prevention among female sex workers (FSWs) in China focus on HIV/sexually transmitted infection (STI) and individual behaviour change. An occupational health framework facilitates intervention across an array of health issues FSWs face including HIV/STI, violence, reproductive health, stigma and substance use. Through a case study of a community-based Jiaozhou (JZ) FSW programme, we developed a conceptual framework incorporating global discussions of structural approaches to HIV prevention with the specific social and structural contexts identified among FSWs in China. Based on ethnographic fieldwork between August 2010 and May 2013, we describe the evolution of this programme to its current occupational health focus and unpack the intervention strategies. We describe the critical features of the programme that have fostered success among FSWs including high-quality clinical services provided within a welcoming setting, responsive outreach work through staff and trained FSW peers, interpersonal and community-level engagement aimed at changing the local social and structural environments of sex work and tailored health education materials. This intervention differs from other projects in China by adopting a more holistic approach to FSW health that incorporates social issues. It also demonstrates the feasibility of structural interventions among FSWs even within an environment that has strong anti-prostitution policies. PMID:25742611

Effect of Tool Offset and Tool Rotational Speed on Enhancing Mechanical Property of Al/Mg Dissimilar FSW Joints

NASA Astrophysics Data System (ADS)

Liang, Zhiyuan; Chen, Ke; Wang, Xiaona; Yao, Junshan; Yang, Qi; Zhang, Lanting; Shan, Aidang

2013-08-01

Friction stir welding (FSW) is a promising solid-state joining technique for producing effective welds between Al alloy and Mg alloy. However, previously reported Al/Mg dissimilar FSW joints generally have limited strength or barely any ductility with relatively high strength, which was blamed on the brittle intermetallics formed during welding. In this study, effective joints with comparably high strength (163 MPa) and large elongation (~6 pct) were obtained. Three crucial/weak zones were identified in the welds: (1) Al/Mg bottom interface (BI) zone that resulted from the insufficient materials' intermixing and interdiffusion; (2) banded structure (BS) zone which contains intermetallic particles possibly formed by constitutional liquation; and (3) softened Al alloy to the retreating side (SAA-RS) zone due to the dissolution and coarsening of the strengthening precipitates. Three fracture modes observed in the tensile specimens perpendicular to the weld seam were found closely related to these zones. Their microstructure evolution with the change of tool rotational speed and tool offset was characterized and the consequent effect on the fracture mode alteration was studied. It turned out that enhancing the strengths of all these zones, but keeping the strength of the SAA lowest, is an effective way for enhancing ductility while keeping comparatively high strength in Al/Mg FSW joints. Also, suggestions for further improving the mechanical property of the Al/Mg dissimilar FSW joints were made accordingly for practical applications.

Unexpectedly high HIV prevalence among female sex workers in Bangkok, Thailand in a respondent-driven sampling survey.

PubMed

Manopaiboon, C; Prybylski, D; Subhachaturas, W; Tanpradech, S; Suksripanich, O; Siangphoe, U; Johnston, L G; Akarasewi, P; Anand, A; Fox, K K; Whitehead, S J

2013-01-01

The pattern of sex work in Thailand has shifted substantially over the last two decades from direct commercial establishments to indirect venues and non-venue-based settings. This respondent-driven sampling survey was conducted in Bangkok in 2007 among female sex workers (FSW) in non-venue-based settings to pilot a new approach to surveillance among this hidden population. Fifteen initial participants recruited 707 consenting participants who completed a behavioural questionnaire, and provided oral fluid for HIV testing, and urine for sexually transmitted infection (STI) testing. Overall HIV prevalence was 20.2% (95% confidence interval [CI] 16.3-24.7). Three-quarters of women were street-based (75.8%, 95% CI 69.9-81.1) who had an especially high HIV prevalence (22.7%, 95% CI 18.2-28.4); about 10 times higher than that found in routine sentinel surveillance among venue-based FSW (2.5%). STI prevalence (Chlamydia trachomatis and Neisseria gonorrhoeae) was 8.7% (95% CI 6.4-10.8) and 1.0% (95% CI 0.2-1.9), respectively. Lower price per sex act and a current STI infection were independently associated with HIV infection (P < 0.05). High HIV prevalence found among FSW participating in the survey, particularly non-venue-based FSW, identifies need for further prevention efforts. In addition, it identifies a higher-risk segment of FSW not reached through routine sentinel surveillance but accessible through this survey method.

Kaposi`s sarcoma associated herpesvirus infection among female sex workers and general population women in Shanghai, China: a cross-sectional study.

PubMed

Zhang, Tiejun; Yang, Ying; Yu, Feng; Zhao, Yanping; Lin, Feifei; Minhas, Veenu; Wood, Charles; He, Na

2014-02-05

Limited information on epidemiologic patterns of KSHV, with none focusing on heterosexual transmission, is available in mainland China. To clarify this, a cross-sectional study was conducted among a group of female sex workers (FSW) and general population women (GW) in Shanghai, China. An anonymous questionnaire interview was administrated among 600 FSW and 600 GW. Blood samples were collected and tested for antibodies to KSHV, HSV-2, HIV, syphilis and HBsAg. Correlates of KSHV and HSV-2 were examined using multiple logistic regression analysis. None of the study participants were tested positive for HIV. The seroprevalence of KSHV, HSV-2 , HBV and syphilis was 10.0%, 52.2%, 12.3% and 10.5%, respectively for FSW, and was 11.0%, 15.3%, 9.8% and 2.8%, respectively for GW. KSHV seropositivity was not associated with syphilis and HSV-2 infection as well as sexual practices among either FSW or GW. Nevertheless, HSV-2 infection among FSW was independently associated with being ever married (OR = 1.59; 95%CI: 1.04-2.45), >5 years of prostitution (OR = 2.06; 95%CI: 1.16-3.68) and being syphilis positive (OR = 2.65; 95%CI: 1.43-4.93). HSV-2 infection among GW was independently associated with an age of >35 years (OR = 2.29; 95%CI: 1.07-4.93), having had more than 2 sex partners in the prior 12 months (OR = 6.44; 95%CI: 1.67-24.93) and being syphilis positive (OR = 3.94; 95%CI: 1.38-11.23). A gradual increase of prevalence with the prostitution time group was also detected for HSV-2 and syphilis, but not for KSHV. KSHV is moderately and equivalently prevalent among FSW and GW. Heterosexual contact is not a predominant route for KSHV transmission among Chinese women.

Potential Impact of Integrated Stigma Mitigation Interventions in Improving HIV/AIDS Service Delivery and Uptake for Key Populations in Senegal.

PubMed

Lyons, Carrie E; Ketende, Sosthenes; Diouf, Daouda; Drame, Fatou M; Liestman, Benjamin; Coly, Karleen; Ndour, Cheikh; Turpin, Gnilane; Mboup, Souleymane; Diop, Karim; Toure-Kane, Coumba; Castor, Delivette; Leye-Diouf, Nafissatou; Baral, Stefan

2017-01-01

Men who have sex with men (MSM) and female sex workers (FSW) are consistently shown to have a higher burden of HIV compared with other adults in Senegal. This study, HIV Prevention 2.0, evaluates the impact of the 3-tiered integrated stigma mitigation interventions (ISMIs) approach to optimizing HIV service delivery for key populations in Senegal. Baseline assessment includes a questionnaire and biological testing for HIV. A proportion of participants enrolled into a 24-month longitudinal cohort with questionnaires and biological testing every 3 months. In these preliminary analyses, ISMIs are evaluated from participants in the cohort through uptake of HIV services and implementation outcomes. Overall, 724 MSM and 758 FSW participated in the baseline assessment. HIV prevalence is 30.2% (n = 219/724) among MSM and 5.3% (n = 40/758) among FSW. Fear of seeking health services among MSM is 17.7% (n = 128/724) at baseline, 10.5% (n = 18/172) at month 3, and 9.8% (n = 10/102) at month 6 (P < 0.004); and among FSW is 21.9% (n = 166/758) at baseline, 8.1% (n = 15/185) at month 3, and 10.7% (n = 18/168) at month 6 (P < 0.001). Overall, 63.9% (n = 62/97) of MSM and 82.5% (n = 118/143) of FSW agreed that the intervention is effective in addressing stigma; however, loss to follow-up was 41.1% among MSM and 10% among FSW. Baseline data reinforce the need for stigma mitigation interventions, combined with enhanced linkage and retention to optimize HIV treatment. Preliminary results show high levels of HIV-related risk determinants and suggest the potential utility of the ISMI to decrease perceived stigma relating to engagement in HIV prevention, treatment, and care services among key populations in Senegal.

HIV prevention and care services for female sex workers: efficacy of a targeted community-based intervention in Burkina Faso.

PubMed

Traore, Isidore T; Meda, Nicolas; Hema, Noelie M; Ouedraogo, Djeneba; Some, Felicien; Some, Roselyne; Niessougou, Josiane; Sanon, Anselme; Konate, Issouf; Van De Perre, Philippe; Mayaud, Philippe; Nagot, Nicolas

2015-01-01

Although interventions to control HIV among high-risk groups such as female sex workers (FSW) are highly recommended in Africa, the contents and efficacy of these interventions are unclear. We therefore designed a comprehensive dedicated intervention targeting young FSW and assessed its impact on HIV incidence in Burkina Faso. Between September 2009 and September 2011 we conducted a prospective, interventional cohort study of FSW aged 18 to 25 years in Ouagadougou, with quarterly follow-up for a maximum of 21 months. The intervention combined prevention and care within the same setting, consisting of peer-led education sessions, psychological support, sexually transmitted infections and HIV care, general routine health care and reproductive health services. At each visit, behavioural characteristics were collected and HIV, HSV-2 and pregnancy were tested. We compared the cohort HIV incidence with a modelled expected incidence in the study population in the absence of intervention, using data collected at the same time from FSW clients. The 321 HIV-uninfected FSW enrolled in the cohort completed 409 person-years of follow-up. No participant seroconverted for HIV during the study (0/409 person-years), whereas the expected modelled number of HIV infections were 5.05/409 person-years (95% CI, 5.01-5.08) or 1.23 infections per 100 person-years (p=0.005). This null incidence was related to a reduction in the number of regular partners and regular clients, and by an increase in consistent condom use with casual clients (adjusted odds ratio (aOR)=2.19; 95% CI, 1.16-4.14, p=0.01) and with regular clients (aOR=2.18; 95% CI, 1.26-3.76, p=0.005). Combining peer-based prevention and care within the same setting markedly reduced the HIV incidence among young FSW in Burkina Faso, through reduced risky behaviours.

Process Modeling of Ti-6Al-4V Linear Friction Welding (LFW)

DTIC Science & Technology

2012-10-01

metallurgy of Ti-6Al-4V to predict microstructure and mechanical properties within the LFW joints (as a function of the LFW process parameters). A... metallurgy aspects of Ti-6Al-4V are reviewed in section 2. The LFW behavior of the same alloy is discussed in section 3. The fully coupled...6. 2. Physical Metallurgy of Ti-6Al-4V Before one can expect to successfully complete the task of understanding the effect of FSW process parameters

Friction-Stir Welding and Mathematical Modeling

NASA Technical Reports Server (NTRS)

Rostant, Victor D.

1999-01-01

The friction-stir welding process is a remarkable way for making butt and lap joints in aluminum alloys. This process operates by passing a rotating tool between two closely butted plates. Through this process it generates a lot of heat and heated material is stirred from both sides of the plates in which the outcome will one high quality weld. My research has been done to study the FSW through mathematical modeling, and using modeling to better understand what take place during the friction-stir weld.

Student Financial Aid Handbook, 2000-2001. Volume 6: Federal Work-Study.

ERIC Educational Resources Information Center

Department of Education, Washington, DC. Student Financial Assistance.

The Federal Work-Study (FWS) Program encourages the part-time employment of undergraduate and graduate students who need the income to help pay the cost of their education and encourages FSW recipients to participate in community service activities. This volume describes the ways schools are required to use money from their FSW Program funds to…

Deconvoluting the Friction Stir Weld Process for Optimizing Welds

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C.

2008-01-01

In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.

Overlapping HIV and sex-work stigma among female sex workers recruited to 14 respondent-driven sampling surveys across Zimbabwe, 2013.

PubMed

Hargreaves, J R; Busza, J; Mushati, P; Fearon, E; Cowan, F M

2017-06-01

HIV stigma can inhibit uptake of HIV testing and antiretroviral therapy as well as negatively affect mental health. Efforts to reduce discrimination against people living with HIV (LWH) have contributed to greater acceptance of the infection. Female sex workers (FSW) LWH may experience overlapping stigma due to both their work and HIV status, although this is poorly understood. We examined HIV and sex-work stigma experienced by FSW LWH in Zimbabwe. Using the SAPPH-IRe cluster-randomised trial baseline survey, we analysed the data from 1039 FSW self-reporting HIV. The women were recruited in 14 sites using respondent-driven sampling. We asked five questions to assess internalised and experienced stigma related to working as a sex worker, and the same questions were asked in reference to HIV. Among all FSW, 91% reported some form of sex-work stigma. This was not associated with sociodemographic or sex-work characteristics. Rates of sex-work stigma were higher than those of HIV-related stigma. For example, 38% reported being "talked badly about" for LWH compared with 77% for their involvement in sex work. Those who reported any sex-work stigma also reported experiencing more HIV stigma compared to those who did not report sex-work stigma, suggesting a layering effect. FSW in Zimbabwe experience stigma for their role as "immoral" women and this appears more prevalent than HIV stigma. As HIV stigma attenuates, other forms of social stigma associated with the disease may persist and continue to pose barriers to effective care.

Association of high-risk sexual behaviour with diversity of the vaginal microbiota and abundance of Lactobacillus

PubMed Central

Wessels, Jocelyn M.; Lajoie, Julie; Vitali, Danielle; Omollo, Kenneth; Kimani, Joshua; Oyugi, Julius; Cheruiyot, Juliana; Kimani, Makubo; Mungai, John N.; Akolo, Maureen; Stearns, Jennifer C.; Surette, Michael G.; Fowke, Keith R.

2017-01-01

Objective To compare the vaginal microbiota of women engaged in high-risk sexual behaviour (sex work) with women who are not engaged in high-risk sexual behaviour. Diverse vaginal microbiota, low in Lactobacillus species, like those in bacterial vaginosis (BV), are associated with increased prevalence of sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) acquisition. Although high-risk sexual behaviour increases risk for STIs, the vaginal microbiota of sex workers is understudied. Methods A retrospective cross-sectional study was conducted comparing vaginal microbiota of women who are not engaged in sex work (non-sex worker controls, NSW, N = 19) and women engaged in sex work (female sex workers, FSW, N = 48), using Illumina sequencing (16S rRNA, V3 region). Results Bacterial richness and diversity were significantly less in controls, than FSW. Controls were more likely to have Lactobacillus as the most abundant genus (58% vs. 17%; P = 0.002) and composition of their vaginal microbiota differed from FSW (PERMANOVA, P = 0.001). Six microbiota clusters were detected, including a high diversity cluster with three sub-clusters, and 55% of women with low Nugent Scores fell within this cluster. High diversity was observed by 16S sequencing in FSW, regardless of Nugent Scores, suggesting that Nugent Score may not be capable of capturing the diversity present in the FSW vaginal microbiota. Conclusions High-risk sexual behaviour is associated with diversity of the vaginal microbiota and lack of Lactobacillus. These factors could contribute to increased risk of STIs and HIV in women engaged in high-risk sexual behaviour. PMID:29095928

Association of high-risk sexual behaviour with diversity of the vaginal microbiota and abundance of Lactobacillus.

PubMed

Wessels, Jocelyn M; Lajoie, Julie; Vitali, Danielle; Omollo, Kenneth; Kimani, Joshua; Oyugi, Julius; Cheruiyot, Juliana; Kimani, Makubo; Mungai, John N; Akolo, Maureen; Stearns, Jennifer C; Surette, Michael G; Fowke, Keith R; Kaushic, Charu

2017-01-01

To compare the vaginal microbiota of women engaged in high-risk sexual behaviour (sex work) with women who are not engaged in high-risk sexual behaviour. Diverse vaginal microbiota, low in Lactobacillus species, like those in bacterial vaginosis (BV), are associated with increased prevalence of sexually transmitted infections (STIs) and human immunodeficiency virus (HIV) acquisition. Although high-risk sexual behaviour increases risk for STIs, the vaginal microbiota of sex workers is understudied. A retrospective cross-sectional study was conducted comparing vaginal microbiota of women who are not engaged in sex work (non-sex worker controls, NSW, N = 19) and women engaged in sex work (female sex workers, FSW, N = 48), using Illumina sequencing (16S rRNA, V3 region). Bacterial richness and diversity were significantly less in controls, than FSW. Controls were more likely to have Lactobacillus as the most abundant genus (58% vs. 17%; P = 0.002) and composition of their vaginal microbiota differed from FSW (PERMANOVA, P = 0.001). Six microbiota clusters were detected, including a high diversity cluster with three sub-clusters, and 55% of women with low Nugent Scores fell within this cluster. High diversity was observed by 16S sequencing in FSW, regardless of Nugent Scores, suggesting that Nugent Score may not be capable of capturing the diversity present in the FSW vaginal microbiota. High-risk sexual behaviour is associated with diversity of the vaginal microbiota and lack of Lactobacillus. These factors could contribute to increased risk of STIs and HIV in women engaged in high-risk sexual behaviour.

Federal Student aid Handbook, 2002-2003. Volume 6: Federal Work-Study.

ERIC Educational Resources Information Center

Office of Federal Student Aid (ED), Washington, DC.

The Federal Work-Study (FWS) Program allows undergraduate and graduate students to work part-time to help pay for the cost of their education. Schools must use 75% of their FSW Program funds to compensate students employed in community service jobs. This volume describes the ways schools are required to use money from FSW program funds to…

A Framework for Sexual Decision-Making Among Female Sex Workers in Jamaica.

PubMed

Bailey, Althea; Figueroa, J Peter

2016-05-01

The Jamaican government has provided targeted HIV and sexually transmitted infection prevention, treatment, and other services for female sex workers (FSW) since 1989. HIV prevalence among FSW declined from 20 to 12% between 1989 and 1994, then to 9% in 2005, 5% in 2008, and 4.1% in 2011. This article distills the literature and two decades of experience working with FSW in Jamaica. Drawing on the constant comparative method, we put forward an innovative conceptual framework for explaining sexual decision-making and risk behaviors within both transactional and relational sexual situations. This framework helps fill the gaps in existing models that focus on individual behaviors. The model identifies interactions between environmental and structural elements of sex work, and three individual-level factors: risk perception, perceived relationship intimacy, and perceived control, as the four primary mediating factors influencing sexual decision-making among FSW. We propose that other factors such as violence, socioeconomic vulnerability, and policy/legal frameworks influence sexual decision-making through these primary mediating factors. This conceptual model may offer a useful framework for planning and evaluating prevention interventions among sex workers. However, it remains to be tested in order to establish its value.

Crystal methamphetamine use and its correlates in women engaged in sex work in a developing country setting.

PubMed

Shokoohi, Mostafa; Karamouzian, Mohammad; Sharifi, Hamid; Rahimi-Movaghar, Afarin; Carrico, Adam W; Hosseini Hooshyar, Samira; Mirzazadeh, Ali

2018-04-01

Worldwide, crystal methamphetamine (CM) use and associated high-risk sexual behaviors are a concern, but they are less studied among female sex workers (FSW) in developing countries. This study aimed to characterize the prevalence and individual, interpersonal, and structural correlates of self-reported past-month CM use among FSW in Iran. FSW aged ≥ 18 years who reported penetrative sex with more than one client in the last year were recruited (analytic sample: 1295). Data were collected in one-on-one interviews using a standardized behavioral questionnaire. Poisson regression model was used to assess the correlated of past-month self-reported CM use by crude and adjusted prevalence ratio (APR) and 95% confidence intervals (CI). Non-injecting and injecting CM use was reported by 15.0% (95% CI: 8.7, 24.7) and 0.9% (95% CI: 0.4, 2.1) of participants. CM use was positively associated with concurrent use of opioids (APR from 2.08 to 3.84, P-value < 0.01), higher number of sexual partners (APR: 2.05, P-value: 0.018), housing instability (APR: 3.54, P-value: 0.001), and history of forced sex (APR: 1.47, P-value: 0.050). A considerable number of FSWs use CM along with opioids, have a higher number of sexual partners, forced sex, and housing instability. Both prevention strategies as well as strategies to reduce harm associated with CM need to be added to current programs that predominantly focus on opioid dependency and male drug injectors. Copyright © 2018 Elsevier B.V. All rights reserved.

Risk factors for HIV infection among female sex workers in Bangui, Central African Republic.

PubMed

Longo, Jean De Dieu; Simaleko, Marcel Mbeko; Diemer, Henri Saint-Calvaire; Grésenguet, Gérard; Brücker, Gilles; Belec, Laurent

2017-01-01

The aims of the study were i) to categorize female sex workers (FSW) according to socio-anthropologic criteria in Bangui; ii) to examine the association between a selection of demographic and risk variables with the different categories of female sex work as outcome, and iii) to investigate factors associated with HIV status. A cross-sectional questionnaire survey was conducted to describe the spectrum of commercial sex work in Bangui among 345 sexually active women. After collection of social and behavioral characteristics, each woman received a physical examination and a blood sample was taken for biological analyses, including HIV testing. The relationships between sociodemographic characteristics, behavioral variables involved in high risk for HIV as well as biological results were investigated by bivariate analysis in relationship with FSW categories as main outcomes, and by bivariate analysis followed by multivariate logistic regression analysis in relationship with HIV as the main outcome. The strength of statistical associations was measured by crude and adjusted Odds ratios (OR) and their 95% confidence intervals. The typology of FSW comprised six different categories. Two groups were the "official" professional FSW primarily classified according to their locations of work [i) "kata"(18.55%) representing women working in poor neighborhoods of Bangui; ii) "pupulenge" (13.91%) working in hotels and night clubs to seek white men]. Four groups were "clandestine" nonprofessional FSW classified according to their reported main activity [i) "market and street vendors" (20.86%); ii) "schoolgirls or students" (19.13%) involved in occasional transactional sex (during holidays); iii) "housewives or unemployed women" (15.65%); iv) "civil servants" (11.88%) working as soldiers or in the public sector]. The overall prevalence of HIV-1 was 19.12% (66/345). HIV varied according to FSW categories. Thus, among professional FSW, the HIV prevalence was 6-fold higher in "kata" than "pupulenge" (39.13% versus 6.30%; P = 0.001). Among nonprofessional FSW, the "vendors" showed the highest HIV prevalence (31.91%), which was higher than in "students" (6.10%; P = 0.001), "civil servants" (9.83%; P = 0.005), and "housewives" (13.00%; P = 0.01). In bivariate analysis, the following variables showed statistically significant association with risk for HIV infection: nationality; age of first sexual intercourse; self-assessment of HIV risk; knowledge of HIV status; anal sex practice with last clients; irregular condom use in last week; consumption of alcohol; other psycho-active substances; past history of STIs; HBs Ag; HSV-2 and bacterial vaginosis. However, the variable "sex workers categories" dichotomized into professional versus nonprofessional FSW was no longer associated with HIV. In multivariate logistical regression analysis, HIV infection was strongly associated with nationality (15.65% versus 3.77%) [adjusted OR (aOR) 3.39: 95% CI:1.25-9.16, P<0.05]; age of first sexual intercourse (21.10% versus 14.00%) (aOR 2.13: 95% CI: 1.03-4.39, P<0.05); anal sex practice with last clients (43.40% versus 11.50%) (aOR 4.31: 95% CI:2.28-8.33, P<0.001); irregular condom use in past week (33.50% versus 3.00%) (aOR 5.49: 95% CI:1.89-15.98, P<0.001); alcohol consumption before sex (34.70% versus 7.80%) (aOR 2.69: 95% CI:1.22-4.96, P<0.05); past history of STIs (41.00% versus 10.80%) (aOR 2.46: 95% CI:1.22-4.97, P<0.05) and bacterial vaginosis (29.80% versus 4.29%) (aOR 6.36: 95% CI: 2.30-17.72, P<0.001). Our observations highlight the high level of vulnerability for HIV acquisition of both poor professional "kata" and nonprofessional "street vendor" FSW categories. These categories should be particularly taken into account when designing specific prevention programs for STIs/HIV control purposes.

Thermo-Mechanical Processing in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Schneider, J. A.; Nunes, A. C., Jr.

2002-01-01

In Friction Stir Welding (FSW) a rotating pin-tool inserted into a weld seam literally stirs the edges of the seam together. In this study, two flow paths are proposed that define the FWS zone. Studies using a longitudinal tungsten wire (0.0025 dia.) were used to visualize and document the material flow. The material flow path is described using a mathematical model.

Effect of Pin Geometry on the Mechanical Strength of Friction-Stir-Welded Polypropylene Composite Plates

NASA Astrophysics Data System (ADS)

Kordestani, F.; Ashenai Ghasemi, F.; Arab, N. B. M.

2017-09-01

Friction stir welding (FSW) is a solid-state welding process, which has successfully been applied in aerospace and automotive industries for joining materials. The friction stir tool is the key element in the FSW process. In this study, the effect of four different tool pin geometries on the mechanical properties of two types of polypropylene composite plates, with 30% glass and carbon fiber, respectively, were investigated. For this purpose, four pins of different geometry, namely, a threaded-tapered pin, square pin, four-flute threaded pin, and threaded-tapered pin with a chamfer were made and used to carry out the butt welding of 5-mm-thick plates. The standard tensile and Izod impact tests were performed to evaluate the tensile strength and impact toughness of welded specimens. The results indicated that the threaded-tapered pin with a chamfer produced welds with a better surface appearance and higher tensile and impact strengths. The tests also showed that, with the threaded-tapered pin with a chamfer, the impact strength of the glass- and carbon-fiber composite welds were about 40 and 50%, respectively, of that of the base materials.

Closed-Loop Control System for Friction Stir Welding Retractable Pin Tool

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Romine, Peter L.; Munafo, Paul M. (Technical Monitor)

2001-01-01

NASA invention disclosure, NASA Case No. MFS-31413, entitled "System for Controlling the Stirring Pin of a Friction Stir Welding Apparatus", (Patent Pending) authored by Jeff Ding, Dr Peter Romine and Pete Oelgoetz, addresses the precision control of the friction stir welding process. The closed-loop control system automatically adjusts the spinning welding pin, real-time, to maintain a precise penetration ligament (i.e., distance between pin-tip and weld panel backside surface). A specific pin length can be maintained while welding constant thickness or tapered material thickness weld panels. The closed-loop control system provides operator data and information relative to the exact position of the welding pin inside the weld joint. This paper presents the closed-loop RPT control system that operates using the auto-feedback of force signals sensed by the tip and shoulder of the welding pin. Significance: The FSW process can be successfully used in a production environment only if there is a method or technique that informs the FSW operator the precise location of the welding pin inside the weld joint. This is essential for applications in aerospace, automotive, pressure vessel, commercial aircraft and other industries.

The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

NASA Astrophysics Data System (ADS)

Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

2017-11-01

This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

Alcohol use, expectancies and HIV-related sexual risk: a cross-sectional survey of male migrant workers in South India.

PubMed

Steward, Wayne T; Satyanarayana, Veena A; Heylen, Elsa; Srikrishnan, Aylur K; Vasudevan, Canjeevaram K; Krishnan, Gopal; Solomon, Davidson; Ekstrand, Maria L

2018-05-01

Male migrant workers (MMWs) in India are vulnerable to developing alcohol-related problems and engaging in unprotected sex, putting them at risk of HIV. Research has shown that alcohol-related expectancies mediate vulnerability to alcoholism. We examined which expectancies were associated with sexual risk and drinking. We surveyed 1085 heterosexual MMWs in two South Indian municipalities, assessing expectancies, sex under the influence, and unprotected sex with female sex workers (FSW) and casual female partners in the prior 30 days. Men more strongly endorsed positive than negative expectancies (t = 53.59, p < .01). In multivariate logistic regression, the expectancy of having more fun helped drive the combination of alcohol and unprotected sex with FSW partners (OR = 1.22, p < .05), whereas the expectancy of better sex helped drive a similar combination with casual partners (OR = 1.24, p < .01). Men concerned about alcohol-induced deficits were less likely to drink with FSW partners (OR = 0.81, p < .01), but more likely to have unprotected sex with them (OR = 1.78, p < .01). To reduce risk, MMWs would benefit from combination prevention approaches that use behavioral strategies to address drinking norms and awareness of risk, while using biomedical strategies to reduce viral transmission when risk does occur.

Transactional Sex Risk across a Typology of Rural and Urban Female Sex Workers in Indonesia: A Mixed Methods Study

PubMed Central

Puradiredja, Dewi Ismajani; Coast, Ernestina

2012-01-01

Context-specific typologies of female sex workers (FSWs) are essential for the design of HIV intervention programming. This study develops a novel FSW typology for the analysis of transactional sex risk in rural and urban settings in Indonesia. Mixed methods include a survey of rural and urban FSWs (n = 310), in-depth interviews (n = 11), key informant interviews (n = 5) and ethnographic assessments. Thematic analysis categorises FSWs into 5 distinct groups based on geographical location of their sex work settings, place of solicitation, and whether sex work is their primary occupation. Multiple regression analysis shows that the likelihood of consistent condom use was higher among urban venue-based FSWs for whom sex work is not the only source of income than for any of the other rural and urban FSW groups. This effect was explained by the significantly lower likelihood of consistent condom use by rural venue-based FSWs (adjusted OR: 0.34 95% CI 0.13–0.90, p = 0.029). The FSW typology and differences in organisational features and social dynamics are more closely related to the risk of unprotected transactional sex, than levels of condom awareness and availability. Interventions need context-specific strategies to reach the different FSWs identified by this study's typology. PMID:23285205

Progress Summaries

DTIC Science & Technology

1973-01-10

nitrogenous urinary metabolites and osmolarity ave been verified and extended to include electrolytes, ketogenic teroids and hydroxysteroids...epidemiological surveys of oral disease for interrelating the effects of climate, diet , oral care motivation and work activity. Oral health factors are monitored...from young rats saturated at 5D FSW days and 60 FSW for 35 days in air while receiving low, normal, and gh calcium diets . Samples from matur8 rats

Advanced Welding Applications

NASA Technical Reports Server (NTRS)

Ding, Robert J.

2010-01-01

Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

Analysis of microstructure and mechanical properties of aluminium-copper joints welded by FSW process

NASA Astrophysics Data System (ADS)

Iordache, M.; Sicoe, G.; Iacomi, D.; Niţu, E.; Ducu, C.

2017-08-01

The research conducted in this article aimed to check the quality of joining some dissimilar materials Al-Cu by determining the mechanical properties and microstructure analysis. For the experimental measurements there were used tin alloy Al - EN-AW-1050A with a thickness of 2 mm and Cu99 sheet with a thickness of 2 mm, joined by FSW weld overlay. The main welding parameters were: rotating speed of the rotating element 1400 rev/min, speed of the rotating element 50 mm/min. The experimental results were determined on samples specially prepared for metallographic analysis. In order to prepare samples for their characterization, there was designed and built a device that allowed simultaneous positioning and fixing for grinding. The characteristics analyzed in the joint welded samples were mictrostructure, microhardness and residual stresses. The techniques used to determine these characteristics were optical microscopy, electron microscopy with fluorescence radioactive elemental analysis (EDS), Vickers microhardness line - HV0.3 and X-ray diffractometry.

Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

2004-01-01

In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

Power, community mobilization, and condom use practices among female sex workers in Andhra Pradesh, India.

PubMed

Blankenship, Kim M; West, Brooke S; Kershaw, Trace S; Biradavolu, Monica R

2008-12-01

We used a structural interventions framework to analyse the associations between power and condom use among a sample of female sex workers (FSW), and how exposure to a local community mobilization intervention (CMI) affects these associations. Data came from a cross-sectional survey of 812 FSW in the East Godavari district of Andhra Pradesh, India, recruited through respondent-driven sampling. We identified three types of power - collective power, control over work, and economic power, and three dimensions of collective power - collective identity, efficacy, and agency. Multivariate logistic regression analysis was used to analyse the relationship of these three types of power and exposure to a CMI with consistent condom use with clients. A total of 803 respondents exchanged sex with an occasional or regular client in the 7 days before the interview. Multivariate logistic regression shows that control over both the type of sex [adjusted odds ratio (AOR) 1.70, 95% confidence interval (CI) 1.23-2.34] and the amount charged (AOR 1.56, 95% CI 1.12-2.16), and economic dependence (AOR 0.54, 95% CI 0.35-0.83) are associated with consistent condom use as is programme exposure (AOR 2.09, 95% CI 1.48-2.94). The interaction between programme exposure and collective agency was also significant (chi-square 6.62, P = 0.01). Among respondents who reported both programme exposure and high levels of collective agency, the odds ratio of consistent condom use was 2.5 times that of other FSW. A structural interventions framework is useful for understanding HIV risk among FSW. More needs to be done to promote FSW control over work and access to economic resources.

Social and structural factors associated with HIV infection among female sex workers who inject drugs in the Mexico-US border region.

PubMed

Strathdee, Steffanie A; Lozada, Remedios; Martinez, Gustavo; Vera, Alicia; Rusch, Melanie; Nguyen, Lucie; Pollini, Robin A; Uribe-Salas, Felipe; Beletsky, Leo; Patterson, Thomas L

2011-04-25

FSWs who inject drugs (FSW-IDUs) can acquire HIV through high risk sexual and injection behaviors. We studied correlates of HIV infection among FSW-IDUs in northern Mexico, where sex work is quasi-legal and syringes can be legally obtained without a prescription. FSW-IDUs>18 years old who reported injecting drugs and recent unprotected sex with clients in Tijuana and Ciudad Juarez underwent surveys and HIV/STI testing. Logistic regression identified correlates of HIV infection. Of 620 FSW-IDUs, prevalence of HIV, gonorrhea, Chlamydia, trichomonas, syphilis titers ≥1:8, or any of these infections was 5.3%, 4%, 13%, 35%, 10% and 72%, respectively. Compared to other FSW-IDUs, HIV-positive women were more likely to: have syphilis titers ≥1:8 (36% vs. 9%, p<0.001), often/always inject drugs with clients (55% vs. 32%, p = 0.01), and experience confiscation of syringes by police (49% vs. 28%, p = 0.02). Factors independently associated with HIV infection were syphilis titers ≥1:8, often/always injecting with clients and police confiscation of syringes. Women who obtained syringes from NEPs (needle exchange programs) within the last month had lower odds of HIV infection associated with active syphilis, but among non-NEP attenders, the odds of HIV infection associated with active syphilis was significantly elevated. Factors operating in both the micro-social environment (i.e., injecting drugs with clients) and policy environment (i.e., having syringes confiscated by police, attending NEPs) predominated as factors associated with risk of HIV infection, rather than individual-level risk behaviors. Interventions should target unjustified policing practices, clients' risk behaviors and HIV/STI prevention through NEPs.

Social and Structural Factors Associated with HIV Infection among Female Sex Workers Who Inject Drugs in the Mexico-US Border Region

PubMed Central

Strathdee, Steffanie A.; Lozada, Remedios; Martinez, Gustavo; Vera, Alicia; Rusch, Melanie; Nguyen, Lucie; Pollini, Robin A.; Uribe-Salas, Felipe; Beletsky, Leo; Patterson, Thomas L.

2011-01-01

Background FSWs who inject drugs (FSW-IDUs) can acquire HIV through high risk sexual and injection behaviors. We studied correlates of HIV infection among FSW-IDUs in northern Mexico, where sex work is quasi-legal and syringes can be legally obtained without a prescription. Methods FSW-IDUs>18 years old who reported injecting drugs and recent unprotected sex with clients in Tijuana and Ciudad Juarez underwent surveys and HIV/STI testing. Logistic regression identified correlates of HIV infection. Results Of 620 FSW-IDUs, prevalence of HIV, gonorrhea, Chlamydia, trichomonas, syphilis titers ≥1∶8, or any of these infections was 5.3%, 4%, 13%, 35%, 10% and 72%, respectively. Compared to other FSW-IDUs, HIV-positive women were more likely to: have syphilis titers ≥1∶8 (36% vs. 9%, p<0.001), often/always inject drugs with clients (55% vs. 32%, p = 0.01), and experience confiscation of syringes by police (49% vs. 28%, p = 0.02). Factors independently associated with HIV infection were syphilis titers ≥1∶8, often/always injecting with clients and police confiscation of syringes. Women who obtained syringes from NEPs (needle exchange programs) within the last month had lower odds of HIV infection associated with active syphilis, but among non-NEP attenders, the odds of HIV infection associated with active syphilis was significantly elevated. Conclusions Factors operating in both the micro-social environment (i.e., injecting drugs with clients) and policy environment (i.e., having syringes confiscated by police, attending NEPs) predominated as factors associated with risk of HIV infection, rather than individual-level risk behaviors. Interventions should target unjustified policing practices, clients' risk behaviors and HIV/STI prevention through NEPs. PMID:21541349

Orion FSW V and V and Kedalion Engineering Lab Insight

NASA Technical Reports Server (NTRS)

Mangieri, Mark L.

2010-01-01

NASA, along with its prime Orion contractor and its subcontractor s are adapting an avionics system paradigm borrowed from the manned commercial aircraft industry for use in manned space flight systems. Integrated Modular Avionics (IMA) techniques have been proven as a robust avionics solution for manned commercial aircraft (B737/777/787, MD 10/90). This presentation will outline current approaches to adapt IMA, along with its heritage FSW V&V paradigms, into NASA's manned space flight program for Orion. NASA's Kedalion engineering analysis lab is on the forefront of validating many of these contemporary IMA based techniques. Kedalion has already validated many of the proposed Orion FSW V&V paradigms using Orion's precursory Flight Test Article (FTA) Pad Abort 1 (PA-1) program. The Kedalion lab will evolve its architectures, tools, and techniques in parallel with the evolving Orion program.

Two-Level Weld-Material Homogenization for Efficient Computational Analysis of Welded Structure Blast-Survivability

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Hariharan, A.; Pandurangan, B.

2012-06-01

The introduction of newer joining technologies like the so-called friction-stir welding (FSW) into automotive engineering entails the knowledge of the joint-material microstructure and properties. Since, the development of vehicles (including military vehicles capable of surviving blast and ballistic impacts) nowadays involves extensive use of the computational engineering analyses (CEA), robust high-fidelity material models are needed for the FSW joints. A two-level material-homogenization procedure is proposed and utilized in this study to help manage computational cost and computer storage requirements for such CEAs. The method utilizes experimental (microstructure, microhardness, tensile testing, and x-ray diffraction) data to construct: (a) the material model for each weld zone and (b) the material model for the entire weld. The procedure is validated by comparing its predictions with the predictions of more detailed but more costly computational analyses.

Unraveling the Processing Parameters in Friction Stir Welding

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C., Jr.

2005-01-01

In friction stir welding (FSW), a rotating threaded pin tool is translated along a weld seam, literally stirring the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path or paths is required. In this study, various markers are used to trace the flow paths of the metal. X-ray radiographs record the segmentation and position of the wire. Several variations in the trajectories can be differentiated within the weld zone.

The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

DTIC Science & Technology

2008-09-01

unavailability of a precise load cell. This scale was set on the machine working table. Since the shaft spindle had been placed in fixed vertical...4 Figure 4. Mill Spindle with Slip Ring and Brush Assembly, Weld Tip is in W orking Position...areas . FSW of HSLA 65 and Type 304L Processing Parameter HSLA-65 304L Spindle Speed (RPM) 850 850 Travel Speed (ipm) 6 2 Z-Load (Ibs) 3500 3500

FSW between Al alloy and Mg Alloy: the comparative study

NASA Astrophysics Data System (ADS)

Jagadeesha, C. B.

2017-04-01

It is difficult to fusion weld Al alloy to Mg alloy, so by experimental optimization procedure (EOP) optimum parameters for FSW between Al alloy and Mg alloy were determined and experiment conducted using these parameters resulted in not only sound weld but also highest strength weld for 5 mm thickness of the alloys plates. One can arrive to optimum parameters by following the EOP in case of similar and dissimilar materials FSW, such as Al alloy and Mg alloy FSW. It has observed that tensile sample having least thickness intermetallics (IMs) layer has highest strength compared to sample with larger thickness of intermetallics layer and also it has observed that weld of lesser thickness plates have strength higher than welds of larger thickness plates. It has observed that, Vickers hardness in WN i.e. on the region containing layers of IMs is considerably higher, which leads to emerge of new type of laminated composite materials. It has observed that, it is the least thickness IMs layers in the weld are responsible for higher strength of weld not the ductility of the IMs formed owing to the insertion of intermediate material in the weld. It has found that coefficient of friction is =0.25, in case of bead on plate welding of Mg alloy.

Rule-Based Flight Software Cost Estimation

NASA Technical Reports Server (NTRS)

Stukes, Sherry A.; Spagnuolo, John N. Jr.

2015-01-01

This paper discusses the fundamental process for the computation of Flight Software (FSW) cost estimates. This process has been incorporated in a rule-based expert system [1] that can be used for Independent Cost Estimates (ICEs), Proposals, and for the validation of Cost Analysis Data Requirements (CADRe) submissions. A high-level directed graph (referred to here as a decision graph) illustrates the steps taken in the production of these estimated costs and serves as a basis of design for the expert system described in this paper. Detailed discussions are subsequently given elaborating upon the methodology, tools, charts, and caveats related to the various nodes of the graph. We present general principles for the estimation of FSW using SEER-SEM as an illustration of these principles when appropriate. Since Source Lines of Code (SLOC) is a major cost driver, a discussion of various SLOC data sources for the preparation of the estimates is given together with an explanation of how contractor SLOC estimates compare with the SLOC estimates used by JPL. Obtaining consistency in code counting will be presented as well as factors used in reconciling SLOC estimates from different code counters. When sufficient data is obtained, a mapping into the JPL Work Breakdown Structure (WBS) from the SEER-SEM output is illustrated. For across the board FSW estimates, as was done for the NASA Discovery Mission proposal estimates performed at JPL, a comparative high-level summary sheet for all missions with the SLOC, data description, brief mission description and the most relevant SEER-SEM parameter values is given to illustrate an encapsulation of the used and calculated data involved in the estimates. The rule-based expert system described provides the user with inputs useful or sufficient to run generic cost estimation programs. This system's incarnation is achieved via the C Language Integrated Production System (CLIPS) and will be addressed at the end of this paper.

Origins of Line Defects in Self-Reacting Friction Stir Welds and Their Impact on Weld Quality

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C., Jr.

2016-01-01

Friction stir welding (FSWing) is a solid state joining technique which reduces the occurrence of typical defects formed in fusion welds, especially of highly alloyed metals. Although the process is robust for aluminum alloys, occasional reductions in the strength of FSWs have been observed. Shortly after the NASA-MSFC implemented a variation of FSW called self-reacting (SR), low strength properties were observed. At that time, this reduction in strength was attributed to a line defect. At that time, the limited data suggested that the line defect was related to the accumulation of native oxides that form on the weld lands and faying surfaces. Through a series of improved cleaning methods, tool redesign, and process parameter modifications, the reduction in the strength of the SR-FSWs was eliminated. As more data has been collected, the occasional reduction in the strength of SR-FSW still occurs. These occasional reductions indicate a need to reexamine the underlying causes. This study builds off a series of self reacting (SR)-FSWs that were made in 3 different thickness panels of AA2219 (0.95, 1.27 and 1.56 cm) at 2 different weld pitches. A bead on plate SR-FSW was also made in the 1.56 cm thick panel to understand the contribution of the former faying surfaces. Copper tracer studies were used to understand the flow lines associated with the weld tool used. The quality of the SR-FSWs was evaluated from tensile testing at room temperature. Reductions in the tensile strength were observed in some weldments, primarily at higher weld pitch or tool rotations. This study explores possible correlations between line defects and the reduction of strength in SR-FSWs. Results from this study will assist in a better understand of the mechanisms responsible for reduced tensile strength and provide methodology for minimizing their occurrence.

Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties

NASA Astrophysics Data System (ADS)

Shunmugasamy, Vasanth C.; Mansoor, Bilal; Ayoub, Georges; Hamade, Ramsey

2018-03-01

Friction stir welding (FSW) is an ecologically benign solid-state joining process. In this work, FSW of low-carbon AISI 1006 steel was carried out to study the microstructure and mechanical properties of the resulting joints at both room temperature (RT) and 200 °C. In the parameter space investigated here, a rotational tool speed and translation feed combination of 1200 rpm and 60 mm/min produced a defect-free weld with balanced mechanical properties and a superior Vickers microhardness profile compared to all other conditions and to base metal (BM). At faster translation feeds (100 and 150 mm/min), wormhole defects were observed in the weld microstructure and were attributed to higher strain rate experienced by the weld zone. Under tensile loading, welded material exhibited yield strength that was up to 86 and 91% of the BM at RT and 200 °C, respectively. On the other hand, tensile strength of welded material was nearly similar to that of the base metal at both RT and 200 °C. However, at both temperatures the tensile ductility of the welded joints was observed to be significantly lower than the BM. Annealing of the 1200 rpm and 60 mm/min FSW specimen resulted in tensile strength of 102% compared to base material and 47% increase in the strain at failure compared to the as-welded specimen. The Charpy impact values revealed up to 62 and 53% increase in the specific impact energy for the 1200 rpm and 60 mm/min welded joints as compared with the BM.

Increasing FSW join strength by optimizing feed rate, rotating speed and pin angle

NASA Astrophysics Data System (ADS)

Darmadi, Djarot B.; Purnowidodo, Anindito; Siswanto, Eko

2017-10-01

Principally the join in Friction Stir Welding (FSW) is formed due to mechanical bonding. At least there are two factors determines the quality of this join, first is the temperature in the area around the interface and secondly the intense of mixing forces in nugget zone to create the mechanical bonding. The adequate temperature creates good flowability of the nugget zone and an intensive mixing force produces homogeneous strong bonding. Based on those two factors in this research the effects of feed rate, rotating speed and pin angle of the FSW process to the tensile strength of resulted join are studied. The true experimental method was used. Feed rate was varied at 24, 42, 55 and 74 mm/minutes and from the experimental results, it can be concluded that the higher feed rate decreases the tensile strength of weld join and it is believed due to the lower heat embedded in the material. Inversely, the higher rotating speed increases the join’s tensile strength as a result of higher heat embedded in base metal and higher mixing force in the nugget zone. The rotating speed were 1842, 2257 and 2904 RPMs. The pin angle determines the direction of mixing force. With variation of pin angle: 0°, 4°, 8° and 12° the higher pin angle generally increases the tensile strength because of more intensive mixing force. For 12° pin angle the lower tensile strength is found since the force tends to push out the nugget area from the joint gap.

Social support and recovery among Mexican female sex workers who inject drugs

PubMed Central

Hiller, Sarah; Syvertsen, Jennifer; Lozada, Remedios; Ojeda, Victoria D.

2013-01-01

This qualitative study describes social support that female sex workers who inject drugs (FSW-IDUs) receive and recovery efforts in the context of relationships with family and intimate partners. We conducted thematic analysis of in-depth interviews with 47 FSW-IDUs enrolled in an intervention study to reduce injection/sexual risk behaviors in Tijuana, Mexico. FSW-IDUs received instrumental and emotional social support, which positively and negatively influenced recovery efforts. Participants reported how some intimate partners provided conflicting positive and negative support during recovery attempts. Problematic support (i.e., well-intended support with unintended consequences) occurred in strained family relationships, limiting the positive effects of support. Mexican drug treatment programs should consider addressing social support in recovery curricula through evidence-based interventions that engage intimate partners, children and family to better reflect socio-cultural and contextual determinants of substance abuse. PMID:23375570

Friction Stir Welding of ODS and RAFM Steels

DOE PAGES

Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; ...

2015-09-14

Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW onmore » grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.« less

Social support and recovery among Mexican female sex workers who inject drugs.

PubMed

Hiller, Sarah P; Syvertsen, Jennifer L; Lozada, Remedios; Ojeda, Victoria D

2013-07-01

This qualitative study describes social support that female sex workers who inject drugs (FSW-IDUs) receive and recovery efforts in the context of relationships with family and intimate partners. We conducted thematic analysis of in-depth interviews with 47 FSW-IDUs enrolled in an intervention study to reduce injection/sexual risk behaviors in Tijuana, Mexico. FSW-IDUs received instrumental and emotional social support, which positively and negatively influenced recovery efforts. Participants reported how some intimate partners provided conflicting positive and negative support during recovery attempts. Problematic support (i.e., well-intended support with unintended consequences) occurred in strained family relationships, limiting the positive effects of support. Mexican drug treatment programs should consider addressing social support in recovery curricula through evidence-based interventions that engage intimate partners, children and family to better reflect socio-cultural and contextual determinants of substance abuse. Copyright © 2013 Elsevier Inc. All rights reserved.

Associations Between Vaginal Infections and Potential High-risk and High-risk Human Papillomavirus Genotypes in Female Sex Workers in Western Kenya.

PubMed

Menon, Sonia; Broeck, Davy Vanden; Rossi, Rodolfo; Ogbe, Emilomo; Harmon, Stacy; Mabeya, Hillary

2016-12-01

Infection with and persistence of high-risk human papillomavirus (HR HPV) are the strongest risk factors for cervical cancer. Little is known about the prevalence and role of concurrent sexually transmitted infections (STIs) found in HPV-infected female sex workers (FSW) in Africa. This study purports to test our a priori hypotheses that STIs are associated with genotypes pertaining to the α-group species 9. The objectives were to determine the prevalence of bacterial vaginosis (BV), Trichomonas vaginalis, and Candida spp in FSW, the association between these STIs and the prevalence of any potential HR and HR HPV genotypes in FSWs. A cross-sectional study design of 616 FSW from Western Kenya aged between 18 and 61 years during 2009-2015 using a peer recruitment sampling strategy. Inclusion criteria for the study entailed female sex and >18 years of age and having engaged in transactional sex in exchange for money, goods, services, or drugs in the last 3 months. Women were excluded if they were pregnant, <18 years of age, had a history of cervical dysplasia or cancer, had current abnormal bleeding, or had a hysterectomy. Of the FSW, 33.3% had HIV and 57.7% harbored a potential HR and HR HPV genotype. The 2 most prevalent potential HR and HR genotypes were HPV 16 (16.10%) and HPV 59 (12.20%). BV was the most common infection (48.3%), followed by Trichomonas vaginalis (31.4%) and Candida spp (19.9%). A multivariate regression revealed significant associations with both α-group 9 and 6; BV and HPV 58 (adjusted odds ratio [aOR] = 2.3; 95% CI, 1.0-5.2; P = 0.05), Trichomonas vaginalis and HPV 31 and HPV 35 (aOR = 2.0; 95% CI, 1.0-3.8; P = 0.04 and aOR = 1.8; 95% CI, 1.0-3.3, P = 0.05 respectively); and between Candida spp and HPV 53 (aOR = 2.0; 95% CI, 1.1-4.0; P = 0.03) and 16 (aOR = 1.9; 95% CI, 1.1-3.3; P = 0.03). Snowball sampling may have inadvertently excluded FSW less likely to benefit from a social network. Significant associations between BV and HPV 58 and between Candida spp and HPV 16 and 53 suggest the need for sexually transmitted disease management within a cervical cancer prevention program. The probable synergistic effects of the vaginal microbiota should be elucidated, especially within this vulnerable population. Given the potential for FSW to transmit STIs, robust epidemiologic sampling methods are urgently required that account for the heterogeneity of the FSW population. Copyright © 2016 Elsevier HS Journals, Inc. All rights reserved.

A Concurrent Product-Development Approach for Friction-Stir Welded Vehicle-Underbody Structures

NASA Astrophysics Data System (ADS)

Grujicic, M.; Arakere, G.; Hariharan, A.; Pandurangan, B.

2012-04-01

High-strength aluminum and titanium alloys with superior blast/ballistic resistance against armor piercing (AP) threats and with high vehicle light-weighing potential are being increasingly used as military-vehicle armor. Due to the complex structure of these vehicles, they are commonly constructed through joining (mainly welding) of the individual components. Unfortunately, these alloys are not very amenable to conventional fusion-based welding technologies [e.g., gas metal arc welding (GMAW)] and to obtain high-quality welds, solid-state joining technologies such as friction-stir welding (FSW) have to be employed. However, since FSW is a relatively new and fairly complex joining technology, its introduction into advanced military-vehicle-underbody structures is not straight forward and entails a comprehensive multi-prong approach which addresses concurrently and interactively all the aspects associated with the components/vehicle-underbody design, fabrication, and testing. One such approach is developed and applied in this study. The approach consists of a number of well-defined steps taking place concurrently and relies on two-way interactions between various steps. The approach is critically assessed using a strengths, weaknesses, opportunities, and threats (SWOT) analysis.

[Implementation of intervention programs on AIDS-related sexual transmission in China].

PubMed

Dong, Wei; Zhou, Chu; Ge, Lin; Li, Dongmin; Wu, Zunyou; Rou, Keming

2015-12-01

To analyze the implementation of intervention programs targeted on AIDS high risk sexual transmission groups since 2008, when the relative prevention and control information systems on HIV/AIDS were developed. Data from both aggregated interventions and sentinel surveillance programs from 2008 to the end of 2014 were used. Descriptive statistics were performed to analyze the trends of implementation on high risk groups including men who have sex with men, female sex workers (FSW) and migrant workers. From 2008 to 2012, the monthly average numbers receiving intervention programs and the average monthly coverage rate on intervention for MSM, increased from 49 000 to 252 000, and from 8.6% to 78.5% respectively. The FSW related indicators increased from 329 000 to 625 000, and from 30.9% to 87.0% respectively. Above indexes on the two populations had dropped slightly in 2013 and 2014. Sentinel surveillance data showed that knowledge and behavior indicators observed from the MSM and FSW populations increased annually. The coverage of intervention programs on migrant workers increased from 4.7% to almost 10.0%, but the surveillance data on migrant men showed that the knowledge and behavior indicators were still lower than the other high-risk groups. Intervention related to sexual transmission on HIV/AIDS among high-risk populations were effectively implemented, with some achievements seen. However, as sexual contact currently became the main route of AIDS epidemic, new challenges called for serious attention.

Risk factors for HIV infection among female sex workers in Bangui, Central African Republic

PubMed Central

Diemer, Henri Saint-Calvaire; Grésenguet, Gérard; Brücker, Gilles; Belec, Laurent

2017-01-01

Objective The aims of the study were i) to categorize female sex workers (FSW) according to socio-anthropologic criteria in Bangui; ii) to examine the association between a selection of demographic and risk variables with the different categories of female sex work as outcome, and iii) to investigate factors associated with HIV status. Methods A cross-sectional questionnaire survey was conducted to describe the spectrum of commercial sex work in Bangui among 345 sexually active women. After collection of social and behavioral characteristics, each woman received a physical examination and a blood sample was taken for biological analyses, including HIV testing. The relationships between sociodemographic characteristics, behavioral variables involved in high risk for HIV as well as biological results were investigated by bivariate analysis in relationship with FSW categories as main outcomes, and by bivariate analysis followed by multivariate logistic regression analysis in relationship with HIV as the main outcome. The strength of statistical associations was measured by crude and adjusted Odds ratios (OR) and their 95% confidence intervals. Results The typology of FSW comprised six different categories. Two groups were the “official” professional FSW primarily classified according to their locations of work [i) “kata“(18.55%) representing women working in poor neighborhoods of Bangui; ii) “pupulenge” (13.91%) working in hotels and night clubs to seek white men]. Four groups were “clandestine” nonprofessional FSW classified according to their reported main activity [i) “market and street vendors” (20.86%); ii) “schoolgirls or students” (19.13%) involved in occasional transactional sex (during holidays); iii) “housewives or unemployed women” (15.65%); iv) “civil servants” (11.88%) working as soldiers or in the public sector]. The overall prevalence of HIV-1 was 19.12% (66/345). HIV varied according to FSW categories. Thus, among professional FSW, the HIV prevalence was 6-fold higher in "kata" than "pupulenge" (39.13% versus 6.30%; P = 0.001). Among nonprofessional FSW, the "vendors" showed the highest HIV prevalence (31.91%), which was higher than in "students" (6.10%; P = 0.001), "civil servants" (9.83%; P = 0.005), and "housewives" (13.00%; P = 0.01). In bivariate analysis, the following variables showed statistically significant association with risk for HIV infection: nationality; age of first sexual intercourse; self-assessment of HIV risk; knowledge of HIV status; anal sex practice with last clients; irregular condom use in last week; consumption of alcohol; other psycho-active substances; past history of STIs; HBs Ag; HSV-2 and bacterial vaginosis. However, the variable “sex workers categories” dichotomized into professional versus nonprofessional FSW was no longer associated with HIV. In multivariate logistical regression analysis, HIV infection was strongly associated with nationality (15.65% versus 3.77%) [adjusted OR (aOR) 3.39: 95% CI:1.25–9.16, P<0.05]; age of first sexual intercourse (21.10% versus 14.00%) (aOR 2.13: 95% CI: 1.03–4.39, P<0.05); anal sex practice with last clients (43.40% versus 11.50%) (aOR 4.31: 95% CI:2.28–8.33, P<0.001); irregular condom use in past week (33.50% versus 3.00%) (aOR 5.49: 95% CI:1.89–15.98, P<0.001); alcohol consumption before sex (34.70% versus 7.80%) (aOR 2.69: 95% CI:1.22–4.96, P<0.05); past history of STIs (41.00% versus 10.80%) (aOR 2.46: 95% CI:1.22–4.97, P<0.05) and bacterial vaginosis (29.80% versus 4.29%) (aOR 6.36: 95% CI: 2.30–17.72, P<0.001). Conclusion Our observations highlight the high level of vulnerability for HIV acquisition of both poor professional “kata” and nonprofessional “street vendor” FSW categories. These categories should be particularly taken into account when designing specific prevention programs for STIs/HIV control purposes. PMID:29108022

Prevalence and predictors of cervicitis in female sex workers in Peru: an observational study.

PubMed

Pollett, Simon; Calderon, Martha; Heitzinger, Kristen; Solari, Vicky; Montano, Silvia M; Zunt, Joseph

2013-04-30

Cervicitis is a syndrome of cervical inflammation and a common condition in female sex workers (FSW), a subpopulation vulnerable to sexually transmitted infections. Local data is essential for guiding syndromic management of cervicitis in FSW working in Peru. We sought to describe the prevalence and etiologies of cervicitis in this population. We also aimed to identify sociodemographic, behavioral and biological factors associated with cervicitis, including bacterial vaginosis (BV), a condition with a possible role in cervicitis. FSW 18 years of age or older presenting to a free public sexual health clinic in Callao-Lima, Peru were eligible for inclusion upon consent. 467 participants completed a face-to-face questionnaire and underwent genital examination. Vaginal, endocervical and blood samples were collected and tested for C. trachomatis (CT), N. gonorrhea (GC), T. vaginalis (TV), BV, HIV and Human T-Cell Lymphotropic Virus -1. Logistic regression was used to determine whether sociodemographic, behavioral, or other sexual health related characteristics were associated with the diagnosis of cervicitis. Cervicitis was detected in 99 (24.9%) of 397 FSW. The presence of cervicitis was unable to be determined in 70 participants. In women with cervicitis, CT was present in 4.6% (4/87), TV in 4.0% (4/99), GC in 0% (0/87) and no pathogen was detected on cervical microbiology in 91.9% (91/99). BV was detected on vaginal microbiology in 36.9% (31/84) of cervicitis cases. BV was more common in women with cervicitis, however this association did not reach statistical significance (aOR = 1.47 [0.87, 2.48], p = 0.15). Other STI were not associated with cervicitis. Regular clinic attendance (aOR = 0.54 [0.34, 0.87], p = 0.01) and Ecuadorian nationality (aOR = 0.31 [0.13, 0.76], p = 0.01) were associated with reduced risk of cervicitis. Cervicitis was common in FSW working Peru and was predominantly nongonococcal and non-chlamydial in etiology. Further study is warranted to clarify the role of BV and other emerging cervicitis pathogens in this population. The current Peruvian program of free health checks for FSW may be effective for reducing rates of cervicitis. The protective effect of Ecuadorian nationality prompts further study.

High-Powered, Ultrasonically Assisted Thermal Stir Welding

NASA Technical Reports Server (NTRS)

Ding, Robert

2013-01-01

This method is a solid-state weld process capable of joining metallic alloys without melting. The weld workpieces to be joined by thermal stir welding (TSW) are drawn, by heavy forces, between containment plates past the TSW stir tool that then causes joining of the weld workpiece. TSW is similar to friction stir welding (FSW) in that material is heated into a plastic state (not melted) and stirred using a stir rod. The FSW pin tool is an integrated geometrical structure consisting of a large-diameter shoulder, and a smaller-diameter stir pin protruding from the shoulder. When the pin is plunged into a weld workpiece, the shoulder spins on the surface of the weld workpiece, thus inducing frictional heat into the part. The pin stirs the fraying surfaces of the weld joint, thus joining the weld workpiece into one structure. The shoulder and stir pin of the FSW pin tool must rotate together at a desired rotational speed. The induced frictional energy control and stir pin control of the pin tool cannot be de-coupled. The two work as one integrated unit. TSW, on the other hand, de-couples the heating and stirring of FSW, and allows for independent control of each process element. A uniquely designed induction coil heats the weld workpiece to a desired temperature, and once heated, the part moves into a stir rod whose RPM is also independently controlled. As the weld workpiece moves into the stir rod, the piece is positioned, or sandwiched, between upper and lower containment plates. The plate squeezes together, thus compressing the upper and lower surfaces of the weld workpiece. This compressive force, also called consolidation force, consolidates the plastic material within the weld nugget material as it is being stirred by the stir rod. The stir rod is positioned through the center of the top containment plate and protrudes midway through the opposite lower containment plate where it is mechanically captured. The upper and lower containment plates are separated by a distance equal to the thickness of the material being welded. The TSW process can be significantly improved by reducing the draw forces. This can be achieved by reducing the friction forces between the weld workpieces and the containment plates. High-power ultrasonic (HPU) vibrations of the containment plates achieve friction reduction in the TSW process. Furthermore, integration of the HPU energy into the TSW stir rod can increase tool life of the stir rod, and can reduce shear forces to which the stir rod is subjected during the welding process. TSW has been used to successfully join 0.500-in (˜13-mm) thick commercially pure (CP) titanium, titanium 6AL- 4V, and titanium 6AL-4V ELI in weld joint lengths up to 9 ft (˜2.75-m) long. In addition, the TSW process was used to fabricate a sub-scale hexagonally shaped gun turret component for the U.S. Navy. The turret is comprised of six 0.5000-in (˜13-mm) thick angled welds. Each angled weld joint was prepared by machining the mating surfaces to 120deg. The angled weld joint was then fixtured using an upper and lower containment plate of the same geometry of the angled weld joint. The weld joint was then stirred by the stir rod as it and the upper and lower containment plates traverse through the angled joint prep.

Feasibility of Underwater Friction Stir Welding of Hardenable Alloy Steel

DTIC Science & Technology

2010-12-01

Base Material CNC – Computer Numerical Controlled EDM – Electrical Discharge Machining FSP – Friction Stir Processing FSW – Friction Stir Welding...Hydrogen content was determined through vacuum hot extraction according to ASTM E 146-83. All other components were analyzed by direct current plasma ...emission spectroscopy according to ASTM E 1097-07. C. MICROSTRUCTURE ANALYSIS 1. Specimen Preparation A Charmilles Andrew EF630 CNC Wire EDM

Estimating the population of female sex workers in two Chinese cities on the basis of the HIV/AIDS behavioural surveillance approach combined with a multiplier method

PubMed Central

Zhang, Dapeng; Lv, Fan; Wang, Liyan; Sun, Liangxian; Zhou, Jian; Su, Wenyi; Bi, Peng

2007-01-01

Objective To estimate the size of the population of female sex workers (FSWs) on the basis of the HIV/AIDS behavioural surveillance approach in two Chinese cities, using a multiplier method. Method Relevant questions were inserted into the questionnaires given to two behavioural surveillance groups—female attendees of sexually transmitted disease (STD) clinics and FSWs. The size of the FSW population was derived by multiplying the number of FSWs in selected STD clinics during the study period by the proportion of FSW population who reported having attended the selected STD clinics during the same period. Results The size of the FSW population in the urban area of Xingyi, China, was estimated to be about 2500 (95% CI 2000 to 3400). This accounted for 3.6% of the total urban adult female population. There were an estimated 17 500 FSWs in the urban area of Guiyang, China (95% CI 10 300 to 31 900) or about 3.4% of its total urban adult female population (rounded to the nearest 100). Conclusions The multiplier method could be a useful and cost‐effective approach to estimate the FSW population, especially suitable in countries where HIV behavioural surveillance has been established in high‐risk populations. PMID:17090568

Predictors of Sexual Risk Reduction Among Mexican Female Sex Workers Enrolled in a Behavioral Intervention Study

PubMed Central

Strathdee, Steffanie A.; Mausbach, Brent; Lozada, Remedios; Staines-Orozco, Hugo; Semple, Shirley J.; Abramovitz, Daniela; Fraga-Vallejo, Miguel; de la Torre, Adela; Amaro, Hortensia; Martínez-Mendizábal, Gustavo; Magis-Rodríguez, Carlos; Patterson, Thomas L.

2009-01-01

Objective We recently showed efficacy of an intervention to increase condom use among female sex workers (FSWs) in Tijuana and Ciudad Juarez, situated on the Mexico–United States border. We determined whether increases in condom use were predicted by social cognitive theory and injection drug user status among women randomized to this intervention. Methods Four hundred nine HIV-negative FSWs aged ≥18 years having unprotected sex with clients within the prior 2 months received a brief individual counseling session integrating motivational interviewing and principles of behavior change (ie, HIV knowledge, self-efficacy for using condoms, and outcome expectancies). Results Increases in self-efficacy scores were associated with increases in percent condom use (P = 0.008), whereas outcome expectancies were not. Female sex workers who inject drugs (FSW-IDUs) increased condom use with clients but not to the same extent as other FSWs (P = 0.09). Change in HIV knowledge was positively associated with change in percent condom use among FSW-IDUs (P = 0.03) but not noninjection drug users. Conclusions Increases in self-efficacy significantly predicted increased condom use among FSWs, consistent with social cognitive theory. Increased HIV knowledge was also important among FSW-IDUs, but their changes in condom use were modest. Enhanced interventions for FSW-IDUs are needed, taking into account realities of substance use during sexual transactions that can compromise safer sex negotiation. PMID:19384101

Testing commercial sex workers for sexually transmitted infections in Victoria, Australia: an evaluation of the impact of reducing the frequency of testing.

PubMed

Chow, Eric P F; Fehler, Glenda; Chen, Marcus Y; Bradshaw, Catriona S; Denham, Ian; Law, Matthew G; Fairley, Christopher K

2014-01-01

The frequency of testing sex workers for sexually transmitted infections (STIs) in Victoria, Australia, was changed from monthly to quarterly on 6 October 2012. Our aim was to determine the impact of this change to the clients seen at the Melbourne Sexual Health Centre (MHSC). Computerised medical records of all clients attending at MHSC from 7 October 2011 to 7 October 2013 were analysed. Comparing between the monthly and quarterly testing periods, the number of consultations at MSHC with female sex workers (FSW) halved from 6146 to 3453 (p<0.001) and the consultation time spent on FSW reduced by 40.6% (1942 h to 1153 h). More heterosexual men (p<0.001), and women (p<0.001) were seen in the quarterly testing period. The number of STIs diagnosed in the clinic increased from 2243 to 2589 from the monthly to quarterly period, respectively [15.4% increase (p<0.001)]. Up to AU$247,000 was saved on FSW testing after the shift to quarterly testing. The change to STIs screening frequency for sex workers from monthly to quarterly resulted in a 15% increase in STI diagnoses in the clinic and approximate a quarter of a million dollars was diverted from FSW testing to other clients. Overall the change in frequency is likely to have had a beneficial effect on STI control in Victoria.

A Vehicle Management End-to-End Testing and Analysis Platform for Validation of Mission and Fault Management Algorithms to Reduce Risk for NASA's Space Launch System

NASA Technical Reports Server (NTRS)

Trevino, Luis; Patterson, Jonathan; Teare, David; Johnson, Stephen

2015-01-01

The engineering development of the new Space Launch System (SLS) launch vehicle requires cross discipline teams with extensive knowledge of launch vehicle subsystems, information theory, and autonomous algorithms dealing with all operations from pre-launch through on orbit operations. The characteristics of these spacecraft systems must be matched with the autonomous algorithm monitoring and mitigation capabilities for accurate control and response to abnormal conditions throughout all vehicle mission flight phases, including precipitating safing actions and crew aborts. This presents a large and complex system engineering challenge, which is being addressed in part by focusing on the specific subsystems involved in the handling of off-nominal mission and fault tolerance with response management. Using traditional model based system and software engineering design principles from the Unified Modeling Language (UML) and Systems Modeling Language (SysML), the Mission and Fault Management (M&FM) algorithms for the vehicle are crafted and vetted in specialized Integrated Development Teams (IDTs) composed of multiple development disciplines such as Systems Engineering (SE), Flight Software (FSW), Safety and Mission Assurance (S&MA) and the major subsystems and vehicle elements such as Main Propulsion Systems (MPS), boosters, avionics, Guidance, Navigation, and Control (GNC), Thrust Vector Control (TVC), and liquid engines. These model based algorithms and their development lifecycle from inception through Flight Software certification are an important focus of this development effort to further insure reliable detection and response to off-nominal vehicle states during all phases of vehicle operation from pre-launch through end of flight. NASA formed a dedicated M&FM team for addressing fault management early in the development lifecycle for the SLS initiative. As part of the development of the M&FM capabilities, this team has developed a dedicated testbed that integrates specific M&FM algorithms, specialized nominal and off-nominal test cases, and vendor-supplied physics-based launch vehicle subsystem models. Additionally, the team has developed processes for implementing and validating these algorithms for concept validation and risk reduction for the SLS program. The flexibility of the Vehicle Management End-to-end Testbed (VMET) enables thorough testing of the M&FM algorithms by providing configurable suites of both nominal and off-nominal test cases to validate the developed algorithms utilizing actual subsystem models such as MPS. The intent of VMET is to validate the M&FM algorithms and substantiate them with performance baselines for each of the target vehicle subsystems in an independent platform exterior to the flight software development infrastructure and its related testing entities. In any software development process there is inherent risk in the interpretation and implementation of concepts into software through requirements and test cases into flight software compounded with potential human errors throughout the development lifecycle. Risk reduction is addressed by the M&FM analysis group working with other organizations such as S&MA, Structures and Environments, GNC, Orion, the Crew Office, Flight Operations, and Ground Operations by assessing performance of the M&FM algorithms in terms of their ability to reduce Loss of Mission and Loss of Crew probabilities. In addition, through state machine and diagnostic modeling, analysis efforts investigate a broader suite of failure effects and associated detection and responses that can be tested in VMET to ensure that failures can be detected, and confirm that responses do not create additional risks or cause undesired states through interactive dynamic effects with other algorithms and systems. VMET further contributes to risk reduction by prototyping and exercising the M&FM algorithms early in their implementation and without any inherent hindrances such as meeting FSW processor scheduling constraints due to their target platform - ARINC 653 partitioned OS, resource limitations, and other factors related to integration with other subsystems not directly involved with M&FM such as telemetry packing and processing. The baseline plan for use of VMET encompasses testing the original M&FM algorithms coded in the same C++ language and state machine architectural concepts as that used by Flight Software. This enables the development of performance standards and test cases to characterize the M&FM algorithms and sets a benchmark from which to measure the effectiveness of M&FM algorithms performance in the FSW development and test processes.

Mars Science Laboratory Boot Robustness Testing

NASA Technical Reports Server (NTRS)

Banazadeh, Payam; Lam, Danny

2011-01-01

Mars Science Laboratory (MSL) is one of the most complex spacecrafts in the history of mankind. Due to the nature of its complexity, a large number of flight software (FSW) requirements have been written for implementation. In practice, these requirements necessitate very complex and very precise flight software with no room for error. One of flight software's responsibilities is to be able to boot up and check the state of all devices on the spacecraft after the wake up process. This boot up and initialization is crucial to the mission success since any misbehavior of different devices needs to be handled through the flight software. I have created a test toolkit that allows the FSW team to exhaustively test the flight software under variety of different unexpected scenarios and validate that flight software can handle any situation after booting up. The test includes initializing different devices on spacecraft to different configurations and validate at the end of the flight software boot up that the flight software has initialized those devices to what they are suppose to be in that particular scenario.

Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321

DTIC Science & Technology

2011-01-01

durable structures are: (a) FSW is 111being used in a serial production of aluminum alloy -based 112ferryboat deck structures in Finland; (b) Al-Mg- Si -based...and strain-hardened/stabilized Al-Mg-Mn alloy ) are characterized by a relatively large statistical scatter. This scatter is closely related to the...associated with friction stir-welded (FSW) joints of AA5083-H321 (a solid-solution-strengthened and strain-hardened/stabilized Al-Mg-Mn alloy ) are

Prevalence and characteristics of abuse experiences and depression symptoms among injection drug-using female sex workers in Mexico.

PubMed

Ulibarri, Monica D; Hiller, Sarah P; Lozada, Remedios; Rangel, M Gudelia; Stockman, Jamila K; Silverman, Jay G; Ojeda, Victoria D

2013-01-01

This mixed methods study examined the prevalence and characteristics of physical and sexual abuse and depression symptoms among 624 injection drug-using female sex workers (FSW-IDUs) in Tijuana and Ciudad Juarez, Mexico; a subset of 47 from Tijuana also underwent qualitative interviews. Linear regressions identified correlates of current depression symptoms. In the interviews, FSW-IDUs identified drug use as a method of coping with the trauma they experienced from abuse that occurred before and after age 18 and during the course of sex work. In a multivariate linear regression model, two factors-ever experiencing forced sex and forced sex in the context of sex work-were significantly associated with higher levels of depression symptoms. Our findings suggest the need for integrated mental health and drug abuse services for FSW-IDUs addressing history of trauma as well as for further research on violence revictimization in the context of sex work in Mexico.

Prevalence and Characteristics of Abuse Experiences and Depression Symptoms among Injection Drug-Using Female Sex Workers in Mexico

PubMed Central

Ulibarri, Monica D.; Hiller, Sarah P.; Lozada, Remedios; Rangel, M. Gudelia; Stockman, Jamila K.; Silverman, Jay G.; Ojeda, Victoria D.

2013-01-01

This mixed methods study examined the prevalence and characteristics of physical and sexual abuse and depression symptoms among 624 injection drug-using female sex workers (FSW-IDUs) in Tijuana and Ciudad Juarez, Mexico; a subset of 47 from Tijuana also underwent qualitative interviews. Linear regressions identified correlates of current depression symptoms. In the interviews, FSW-IDUs identified drug use as a method of coping with the trauma they experienced from abuse that occurred before and after age 18 and during the course of sex work. In a multivariate linear regression model, two factors—ever experiencing forced sex and forced sex in the context of sex work—were significantly associated with higher levels of depression symptoms. Our findings suggest the need for integrated mental health and drug abuse services for FSW-IDUs addressing history of trauma as well as for further research on violence revictimization in the context of sex work in Mexico. PMID:23737808

Workplace violence among female sex workers who use drugs in Vancouver, Canada: does client-targeted policing increase safety?

PubMed

Prangnell, Amy; Shannon, Kate; Nosova, Ekaterina; DeBeck, Kora; Milloy, M-J; Kerr, Thomas; Hayashi, Kanna

2018-02-01

Workplace violence, by clients or predators, poses serious negative health consequences for sex workers. In 2013, the Vancouver (British Columbia), Canada Police Department changed their guidelines with the goal of increasing safety for sex workers by focusing law enforcement on clients and third parties, but not sex workers. We sought to examine the trends and correlates of workplace violence among female sex workers (FSW) before and after the guideline change, using data collected from prospective cohorts of persons who use illicit drugs in Vancouver, Canada. Among 259 FSW, 21.0% reported workplace violence at least once during the study period between 2008 and 2014. There was no statistically significant change in rates of workplace violence after the guideline change. In our multivariable analysis, daily heroin use was independently associated with workplace violence. The 2013 policing guideline change did not appear to have resulted in decreased reports of workplace violence. Increased access to opioid agonist therapies may reduce workplace violence among drug-using FSW.

A cross-sectional survey of attitudes to HIV risk and rapid HIV testing among clients of sex workers in Switzerland.

PubMed

Darling, Katharine E A; Diserens, Esther-Amélie; N'garambe, Chantal; Ansermet-Pagot, Anne; Masserey, Eric; Cavassini, Matthias; Bodenmann, Patrick

2012-10-01

To assess attitudes to HIV risk and acceptability of rapid HIV testing among clients of street-based female sex workers (FSW) in Lausanne, Switzerland, where HIV prevalence in the general population is 0.4%. The authors conducted a cross-sectional study in the red light district of Lausanne for five nights in September of 2008, 2009 and 2010. Clients of FSW were invited to complete a questionnaire in the street assessing demographic characteristics, attitudes to HIV risk and HIV testing history. All clients interviewed were then offered anonymous finger stick rapid HIV testing in a van parked on-site. The authors interviewed 112, 127 and 79 clients in 2008, 2009 and 2010, respectively. All were men, average age 32-37 years old; 40-60% were in a stable relationship. History of unprotected sex was higher with non-commercial partners (33-50%) than with FSW (6-11%); 29-46% of clients had never undergone an HIV test. Anonymous rapid HIV testing was accepted by 45-50% of clients. Out of 109 HIV tests conducted during the three study periods, none was reactive. On-site HIV counselling and testing is acceptable among clients of FSW in this urban setting. These individuals represent an unquantified population, a proportion of which has an incomplete understanding of HIV risk in the face of high-risk behaviour, with implications for potential onward transmission to non-commercial sexual partners.

Numerical study on influence of single control surface on aero elastic behavior of forward-swept wing

NASA Astrophysics Data System (ADS)

Wang, Ning; Su, Xinbing; Ma, Binlin; Zhang, Xiaofei

2017-10-01

In order to study the influence of elastic forward-swept wing (FSW) with single control surface, the computational fluid dynamics/computational structural dynamics (CFD/CSD) loose coupling static aero elastic numerical calculation method was adopted for numerical simulation. The effects of the elastic FSW with leading- or trailing-edge control surface on aero elastic characteristics were calculated and analysed under the condition of high subsonic speed. The result shows that, the deflection of every single control surface could change the aero elastic characteristics of elastic FSW greatly. Compared with the baseline model, when leading-edge control surface deflected up, under the condition of small angles of attack, the aerodynamic characteristics was poor, but the bending and torsional deformation decreased. Under the condition of moderate angles of attack, the aerodynamic characteristics was improved, but bending and torsional deformation increased; When leading-edge control surface deflected down, the aerodynamic characteristics was improved, the bending and torsional deformation decreased/increased under the condition of small/moderate angles of attack. Compared with the baseline model, when trailing-edge control surface deflected down, the aerodynamic characteristics was improved. The bending and torsional deformation increased under the condition of small angles of attack. The bending deformation increased under the condition of small angles of attack, but torsional deformation decreases under the condition of moderate angles of attack. So, for the elastic FSW, the deflection of trailing-edge control surface play a more important role on the improvement of aerodynamic and elastic deformation characteristics.

Vaginal and anal human papillomavirus infection and seropositivity among female sex workers in Amsterdam, the Netherlands: Prevalence, concordance and risk factors.

PubMed

Marra, E; Kroone, N; Freriks, E; van Dam, C L; Alberts, C J; Hogewoning, A A; Bruisten, S; van Dijk, A; Kroone, M M; Waterboer, T; Schim van der Loeff, M F

2018-04-01

We studied prevalence, risk factors and concordance of vaginal and anal HPV infection and L1 seropositivity among female sex workers (FSW) in Amsterdam. In 2016, FSW aged ≥18 years having a sexually transmitted infections (STI) consultation were invited to participate. Participation entailed taking vaginal and anal self-swabs. Demographics and sexual behaviour data were collected. HPV DNA was analysed using the SPF10-PCR-DEIA-LiPA25-system-v1. Serum was tested for HPV L1 antibodies using multiplex serology assays. Determinants of vaginal and anal high risk HPV (hrHPV) infection and L1 seropositivity were assessed with logistic regression analyses. We included 304 FSW; median age was 29 years (IQR 25-37). Vaginal and anal hrHPV prevalence were 46% and 55%, respectively. HrHPV L1 seropositivity was 37%. Vaginal-anal hrHPV concordance was strong, but no significant association between vaginal or anal hrHPV infection and seropositivity was found. Having had anal sexual contact was not associated with anal hrHPV infection (P = 0.119). Vaginal and anal hrHPV prevalence is high among FSW in Amsterdam, the Netherlands. Promotion of HPV vaccination, preferably at the beginning of the sex (work) career, may be a useful prevention method against hrHPV infection and disease. Copyright © 2017 The British Infection Association. Published by Elsevier Ltd. All rights reserved.

Orion MPCV Touchdown Detection Threshold Development and Testing

NASA Technical Reports Server (NTRS)

Daum, Jared; Gay, Robert

2013-01-01

A robust method of detecting Orion Multi ]Purpose Crew Vehicle (MPCV) splashdown is necessary to ensure crew and hardware safety during descent and after touchdown. The proposed method uses a triple redundant system to inhibit Reaction Control System (RCS) thruster firings, detach parachute risers from the vehicle, and transition to the post ]landing segment of the Flight Software (FSW). The vehicle crew is the prime input for touchdown detection, followed by an autonomous FSW algorithm, and finally a strictly time based backup timer. RCS thrusters must be inhibited before submersion in water to protect against possible damage due to firing these jets under water. In addition, neglecting to declare touchdown will not allow the vehicle to transition to post ]landing activities such as activating the Crew Module Up ]righting System (CMUS), resulting in possible loss of communication and difficult recovery. A previous AIAA paper gAssessment of an Automated Touchdown Detection Algorithm for the Orion Crew Module h concluded that a strictly Inertial Measurement Unit (IMU) based detection method using an acceleration spike algorithm had the highest safety margins and shortest detection times of other methods considered. That study utilized finite element simulations of vehicle splashdown, generated by LS ]DYNA, which were expanded to a larger set of results using a Kriging surface fit. The study also used the Decelerator Systems Simulation (DSS) to generate flight dynamics during vehicle descent under parachutes. Proto ]type IMU and FSW MATLAB models provided the basis for initial algorithm development and testing. This paper documents an in ]depth trade study, using the same dynamics data and MATLAB simulations as the earlier work, to further develop the acceleration detection method. By studying the combined effects of data rate, filtering on the rotational acceleration correction, data persistence limits and values of acceleration thresholds, an optimal configuration was determined. The lever arm calculation, which removes the centripetal acceleration caused by vehicle rotation, requires that the vehicle angular acceleration be derived from vehicle body rates, necessitating the addition of a 2nd order filter to smooth the data. It was determined that using 200 Hz data directly from the vehicle IMU outperforms the 40 Hz FSW data rate. Data persistence counter values and acceleration thresholds were balanced in order to meet desired safety and performance. The algorithm proved to exhibit ample safety margin against early detection while under parachutes, and adequate performance upon vehicle splashdown. Fall times from algorithm initiation were also studied, and a backup timer length was chosen to provide a large safety margin, yet still trigger detection before CMUS inflation. This timer serves as a backup to the primary acceleration detection method. Additionally, these parameters were tested for safety on actual flight test data, demonstrating expected safety margins.

Type II decompression sickness in a hyperbaric inside attendant.

PubMed

Johnson-Arbor, Kelly

2012-01-01

Decompression sickness (DCS) of an inside attendant (IA) is rarely encountered in hyperbarics. This report describes an IA who developed Type II DCS after a routine hyperbaric exposure. A 50-year-old male complained of lower extremity weakness and paresthesias after serving as an IA during a hyperbaric treatment to 40 fsw (122.52 kPa). Within 10 minutes after the conclusion of the treatment, the IA experienced irritability and confusion, and was unable to walk. Physical examination revealed decreased sensation below the T7 level, and decreased strength in the lower extremities. Type II DCS was diagnosed, and the IA was recompressed to 60 fsw (183.78 kPa) on a U.S. Navy Treatment Table 6, which resulted in improvement of his symptoms. Transthoracic echocardiography with bubble study performed 16 months after the event demonstrated a large patent foramen ovale (PFO). Increased age, decreased physical fitness and the undiagnosed PFO may have predisposed this attendant to developing DCS. Although rare, DCS may occur in IAs. Routine monitoring and reporting of the long-term health of hyperbaric IAs should be considered by hyperbaric facilities and medical directors in order to further understand the characteristics of DCS and other hyperbaric-related conditions in these workers.

Syringe confiscation as an HIV risk factor: the public health implications of arbitrary policing in Tijuana and Ciudad Juarez, Mexico.

PubMed

Beletsky, Leo; Lozada, Remedios; Gaines, Tommi; Abramovitz, Daniela; Staines, Hugo; Vera, Alicia; Rangel, Gudelia; Arredondo, Jaime; Strathdee, Steffanie A

2013-04-01

Female sex workers who inject drugs (FSW-IDUs) face elevated risk for HIV/STIs and constitute a key population for public health prevention. Through direct and indirect pathways including human rights violations, policing practices like syringe confiscation can compound FSW-IDU health risk and facilitate the spread of disease. We studied correlates of experiencing syringe confiscation among FSW-IDUs in northern Mexico, where formal policy allows for syringes to be available over the counter without a prescription, but police practices are often at odds with the law. FSW-IDUs reporting recent syringe sharing and unprotected sex with clients in Tijuana and Ciudad Juarez were administered surveys and HIV/STI testing. Logistic regression was used to identify correlates of syringe confiscation. Among 624 respondent FSW-IDUs, prevalence of syringe confiscation in the last 6 months was 48%. The following factors were positively associated with syringe confiscation: testing positive for HIV (adjusted odds ratio [aOR] = 2.54, 95% confidence interval [CI] = 1.11-5.80), reporting sexual abuse by police (aOR = 12.76, 95% CI = 6.58-24.72), engaging in groin injection (aOR = 1.84, 95% CI = 1.15-2.93), injecting in public (aOR = 1.64; 95% CI = 1.14-2.36), and obtaining syringes from pharmacies (aOR = 1.54; 95% CI = 1.06-2.23). Higher education level was negatively associated with syringe confiscation (aOR = 0.92, 95% CI = 0.87-0.98) as was frequent injection with clients within the last month (aOR = 0.64, 95% CI = 0.44-0.94). This analysis adds to the body of evidence linking unauthorized law enforcement actions targeting high-risk groups with HIV and other adverse health outcomes. Using a public health lens to conceptualize abuse as a structural risk factor, we advocate for multi-prong prevention, systematic monitoring, and evidence-based intervention response to deleterious police practices.

HIV risk and behaviour among part-time versus professional FSW: baseline report of an interventional cohort in Burkina Faso.

PubMed

Traore, Isidore T; Hema, Noelie M; Sanon, Anselme; Some, Felicien; Ouedraogo, Djeneba; Some, Roselyne; Niessougou, Josiane; Konate, Issouf; Mayaud, Philippe; Van De Perre, Philippe; Meda, Nicolas; Nagot, Nicolas

2016-02-01

To readjust HIV control programmes in Africa, we assessed the factors associated with high-risk behaviours and HIV infection among young female sex workers (FSW) in Burkina Faso. We carried out a cross-sectional study from September 2009 to September 2010 in Ouagadougou, the capital city. FSW were categorised as professionals and part-time sex workers (PTSW). After a face-to-face questionnaire, blood and urine samples were collected for HIV, HSV-2, genital infections and pregnancy. High-risk behaviour was defined as a recent unprotected sex with either casual clients, regular clients or regular partners. We recruited 609 FSW including 188 (30.9%) professionals. Their median age was 21 years (IQR 19-23), and the prevalence of HIV was 10.3% among professionals and 6.5% among PTSW. Only 3 of 46 HIV-infected women were aware of their status. Overall, 277 (45.6%) women reported high-risk behaviours (41.2% among professionals and 47.5% among PTSW), which were driven mainly by non-systematic condom use with regular partners. In multivariable analysis, PTSW (adjusted OR (AOR)=1.89; 95% CI 1.27 to 2.82) and having a primary (AOR=1.75; 95% CI 1.15 to 2.67) or higher education level (AOR=1.80; 95% CI 1.13 to 2.89) remained associated with high-risk behaviours. HIV infection was associated with older age (AOR=1.44; 95% CI 1.22 to 1.71), with being married/cohabiting (AOR=2.70; 95% CI 1.21 to 6.04) and with Trichomonas vaginalis infection (AOR=9.63; 95% CI 2.93 to 31.59), while history of HIV testing was associated with a decreased risk (AOR=0.18; 95% CI 0.08 to 0.40). This study highlights the need for targeted interventions among young FSW focusing particularly on PTSW, sexual behaviours with regular partners and regular HIV testing. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Occupational and demographic factors associated with drug use among female sex workers at the China-Myanmar border.

PubMed

Hail-Jares, Katie; Choi, Sugy; Duo, Lin; Luo, Zhi; Huang, Z Jennifer

2016-04-01

Within the last decade, the use of amphetamine type stimulants (ATS) has swelled in Myanmar. Regionally, female sex workers have reported turning to ATS for occupational reasons. In doing so, drug-using female sex workers (FSW) face compounded risks for HIV and other sexually transmitted infections (STI). Here, we examine the factors that impact FSW drug use in Muse, a town along the China-Myanmar border. In 2012, 101 FSW were recruited from entertainment venues and brothels along the Myanmar-Chinese border. Participants participated in a self-administered behavioral survey covering demographics, drug use, sex work, and risk behaviors. Bivariate and regression analyses were conducted in SPSS. Thirty four percent of respondents indicated current drug use. ATS derivatives were the most commonly used drugs (87.5%) with injection drug use being nearly non-existent in the sample. Drug using FSWs were older, had engaged in sex work longer, had more Chinese clients, and were more likely to have a previous boyfriend who had used drugs. They were also 3.5 times more likely to report a STI. Client condom use, HIV testing rates, and familiarity with public health resources did not statistically differ by drug use status. More research is needed to examine how romantic and professional sexual relationships push-and-pull FSW into using drugs. Our results suggest that diverse safer sex strategies, beyond client condom use, should be promoted with drug using FSWs, including strategies that acknowledge the impact of ATS use. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Understanding the Relationship Between Female Sex Workers and Their Intimate Partners: Lessons and Initial Findings From Participatory Research in North Karnataka, South India.

PubMed

Bhattacharjee, Parinita; Campbell, Linda; Thalinja, Raghavendra; Nair, Sapna; Doddamane, Mahesh; Ramanaik, Satyanarayana; Isac, Shajy; Beattie, Tara S

2018-04-01

While traditional HIV prevention programs with female sex workers (FSWs) in Karnataka, India, have focused on reducing HIV transmission between FSWs and clients through increased condom use, these programs have not fully addressed the transmission risk between FSWs and their nonpaying intimate partners (IPs). Condom use is infrequent and violence is recurrent in these relationships: Furthermore, there is little evidence on the precise nature of FSW-IP relationships. Our study addresses this knowledge gap to inform HIV programs targeted at FSWs. A series of workshops, using participatory tools, was held to explore FSW-IP relationships; 31 FSWs and 37 IPs participated. Three aspects of FSW-IP relationships were examined: how FSWs and IPs understand and interpret their relationships, factors influencing condom use, and the role of violence and its consequences. FSWs wish to be perceived as their IPs' wives, while IPs expect their FSW partners to accept their dominance in the relationship. Nonuse of condoms signals fidelity and elevates the status of the relationship almost to that of marriage, which helps FSWs enter the category of "good" (married) women. Tolerating and accepting violence in these relationships is normative, as in other marital relationships; IPs justify violence as necessary to establish and maintain their power within the relationship. Both FSWs and IPs value their relationships despite the high degree of risk posed by low condom use and high levels of violence. Implications for program design include addressing current norms around masculinity and gender roles, and improving communication within relationships.

Variations in condom use by locale: a comparison of mobile Chinese female sex workers in Hong Kong and mainland China.

PubMed

Lau, Joseph T F; Tsui, H Y; Ho, Shara P Y

2007-12-01

The present study investigated the prevalence of HIV and HIV-related behaviors and perceptions among 336 female sex workers (FSW) traveling from mainland China to work in Hong Kong. None of the participants tested HIV positive. Of the participants, 13.2% and 26.8%, respectively, would have unprotected sex with a client in Hong Kong or in mainland China if they liked the client; 16.7% and 21.7%, respectively, would have unprotected sex with a client in Hong Kong and in mainland China if he paid more. Of the participants, 98.5% used condoms in the last episode of sex work in Hong Kong and 78.1% were consistent condom users in Hong Kong in the last month. Yet, among those who previously worked as FSW in mainland China (n = 141), only 28.6% used condoms consistently in mainland China in the last year; 60% of those who used condoms inconsistently while in mainland China became consistent condom users in Hong Kong. Among those who did not use condoms in mainland China, willingness to have unprotected sex with a client who was liked by the FSW was a strong predictor for consistent condom use in Hong Kong (OR = 18.67, p < .001). Among those who were consistent condom users in Hong Kong, the same variable predicted inconsistent condom use while in mainland China (OR = 14.02, p < .05). Condom use behaviors change when FSW are working in different social contexts and behavioral changes are possible. Education programs should take socio-contextual factors into account.

Friction stir welding of T joints of dissimilar aluminum alloy: A review

NASA Astrophysics Data System (ADS)

Thakare, Shrikant B.; Kalyankar, Vivek D.

2018-04-01

Aluminum alloys are preferred in the mechanical design due to their advantages like high strength, good corrosion resistance, low density and good weldability. In various industrial applications T joints configuration of aluminum alloys are used. In different fields, T joints having skin (horizontal sheet) strengthen by stringers (vertical sheets) were used to increase the strength of structure without increasing the weight. T joints are usually carried out by fusion welding which has limitations in joining of aluminum alloy due to significant distortion and metallurgical defects. Some aluminum alloys are even non weldable by fusion welding. The friction stir welding (FSW) has an excellent replacement of conventional fusion welding for T joints. In this article, FSW of T joints is reviewed by considering aluminum alloy and various joint geometries for defect analysis. The previous experiments carried out on T joints shows the factors such as tool geometry, fixturing device and joint configurations plays significant role in defect free joints. It is essential to investigate the material flow during FSW to know joining mechanism and the formation of joint. In this study the defect occurred in the FSW are studied for various joint configurations and parameters. Also the effect of the parameters and defects occurs on the tensile strength are studied. It is concluded that the T-joints of different joint configurations can be pretended successfully. Comparing to base metal some loss in tensile strength was observed in the weldments as well as overall reduction of the hardness in the thermos mechanically affected zone also observed.

Sex Trade Behavior Among Heterosexually Active Homeless Men

PubMed Central

Tucker, Joan S.; Wenzel, Suzanne L.; Kennedy, David P.; Golinelli, Daniela; Ewing, Brett

2013-01-01

Sex trade behavior is fairly common among homeless adults and may contribute to higher rates of HIV/AIDS in this population. This study provides a detailed examination of the sex trade-related attitudes and behaviors of homeless men by: (1) determining the prevalence of sex trade-related behaviors, including sex with female sex workers (FSWs); (2) identifying risk factors for having sex with FSWs; and (3) comparing men's relationships with FSWs and non-FSWs in terms of relationship qualities and HIV-related risk behaviors, such as condom use. Structured interviews were conducted with a probability sample of 305 heterosexually active homeless men recruited from meal lines in Los Angeles. Recent sex with a FSW was reported by 26% of men, and more likely among those who were older, used crack cocaine, had more sex partners, believed that sometimes men just need to have sex no matter what, and were embedded in networks that were denser and where risky sex was more normative. Compared to non-FSW partners, men with FSW partners felt less emotionally close to them, were more likely to believe the partner had never been tested for HIV, and were more likely to have sex with them under the influence of drugs or alcohol; however, they were not more likely to talk about using condoms or to use condoms with FSWs. Whether the relationship was considered “serious” was a stronger correlate of condom use than whether the partner was a FSW. Implications of these findings for HIV prevention efforts among homeless adults are discussed. PMID:23720137

Association of sex work with reduced activation of the mucosal immune system.

PubMed

Lajoie, Julie; Kimani, Makubo; Plummer, Francis A; Nyamiobo, Francis; Kaul, Rupert; Kimani, Joshua; Fowke, Keith R

2014-07-15

Unprotected intercourse and seminal discharge are powerful activators of the mucosal immune system and are important risk factors for transmission of human immunodeficiency virus (HIV). This study was designed to determine if female sex work is associated with changes in the mucosal immunity. Cervicovaginal lavage and plasma from 122 HIV-uninfected female sex workers (FSW) and 44 HIV-uninfected low-risk non-FSW from the same socioeconomic district of Nairobi were analyzed for evidence of immune activation (IA). The cervico-mononuclear cells (CMC) were analyzed for cellular activation by flow cytometry. Lower IA was observed in FSW compared to the low-risk women as demonstrated by the lower level of MIP-3α (P < .001), ITAC (P < .001), MIG (p.0001), IL-1α (P < .001), IL-1β (P < .001), IL-1Rα (P = .0002), IL-6 (P < .001), IL-8 (P < .001), IL-10 (P = .01), IP-10 (P = .0001), MDC (P < .001), MIP-1α, (P < .001), MIP-1β (P = .005), MCP-1 (P = .03), and TNF-α (P = .006). Significant differences were noted as early as 1 year following initiation of sex work and increased with duration of sex work. This study showed that sex work is associated with important changes in the mucosal immune system. By analyzing chemokine/cytokine levels and CMC activation, we observed a lower mucosal IA in HIV-uninfected FSW compared to low-risk women. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Mechanical Properties of Aluminum-Based Dissimilar Alloy Joints by Power Beams, Arc and FSW Processes

NASA Astrophysics Data System (ADS)

Okubo, Michinori; Kon, Tomokuni; Abe, Nobuyuki

Dissimilar smart joints are useful. In this research, welded quality of dissimilar aluminum alloys of 3 mm thickness by various welding processes and process parameters have been investigated by hardness and tensile tests, and observation of imperfection and microstructure. Base metals used in this study are A1050-H24, A2017-T3, A5083-O, A6061-T6 and A7075-T651. Welding processes used are YAG laser beam, electron beam, metal inert gas arc, tungsten inert gas arc and friction stir welding. The properties of weld zones are affected by welding processes, welding parameters and combination of base metals. Properties of high strength aluminum alloy joints are improved by friction stir welding.

Study on microstructure and tensile properties of fly ash AMCs welded by FSW

NASA Astrophysics Data System (ADS)

Sachinkumar, Narendranath, S.; Chakradhar, D.

2018-04-01

Aluminum matrix composite (AMCs) constitute a new class of light weight and high strength materials which have widespread applications in almost all engineering sectors. But the cost of AMCs is the only barrier to increase their applications still. Hence there is a huge demand for the composites containing low cost reinforcement with less weight, keeping this in mind, in the present work, Friction stir welding (FSW) of AA6061/SiC/fly ash was carried out successfully. Microstructural study on the welded specimens was performed using optical microscopy (OM) and scanning electron microscopy (SEM). Results indicate that fly ash particles were uniformly distributed in the weld nugget area because of the stirring action of the FSW tool also promoted the grain refinement of the matrix material with complete elimination of clusters present in matrix material which resulting in sound welds without any defects for AA6061/SiC/fly ash composites. 82% of joint efficiency is obtained for selected AMCs. Transverse tensile test results showed that all welds fractured in HAZ.

Assessment of Ductile-to-Brittle Transition Behavior of Localized Microstructural Regions in a Friction-Stir Welded X80 Pipeline Steel with Miniaturized Charpy V-Notch Testing

NASA Astrophysics Data System (ADS)

Avila, Julian A.; Lucon, Enrico; Sowards, Jeffrey; Mei, Paulo Roberto; Ramirez, Antonio J.

2016-06-01

Friction-stir welding (FSW) is an alternative welding process for pipelines. This technology offers sound welds, good repeatability, and excellent mechanical properties. However, it is of paramount importance to determine the toughness of the welds at low temperatures in order to establish the limits of this technology. Ductile-to-brittle transition curves were generated in the present study by using a small-scale instrumented Charpy machine and miniaturized V-notch specimens (Kleinstprobe, KLST); notches were located in base metal, heat-affected, stirred, and hard zones within a FSW joint of API-5L X80 Pipeline Steel. Specimens were tested at temperatures between 77 K (-196 °C) and 298 K (25 °C). Based on the results obtained, the transition temperatures for the base material and heat-affected zone were below 173 K (-100 °C); conversely, for the stirred and hard zones, it was located around 213 K (-60 °C). Fracture surfaces were characterized and showed a ductile fracture mechanism at high impact energies and a mixture of ductile and brittle mechanisms at low impact energies.

High Rotation Speed Friction Stir Welding for 2014 Aluminum Alloy Thin Sheets

NASA Astrophysics Data System (ADS)

Chen, Shujin; Zhou, Yang; Xue, Junrong; Ni, Ruiyang; Guo, Yue; Dong, Jianghui

2017-03-01

In this study, 2014 aluminum alloy sheets with 1 mm thickness are welded successfully by friction stir welding (FSW) robot under the condition of high rotation speed. When the high rotation speed of 10,000-16,500 rpm is applied, the lower axial pressure (less than 200 N) is obtained, which reduces stiffness requirements for equipment. Welding deformation is inevitable because high rotation speed can easily result in rapid heating rate and uneven heat input. The welding distortion caused by two cooling methods is measured, respectively, by laser range finder. The experimental results show that the welding distortion is smaller under the condition of water cooling. When the rotation speed is up to 15,000 rpm and welding speed 50-170 mm/min, the whole welding process is controllable. Under the higher rotation speed condition, the welding defects disappear gradually and more stable mechanical properties can be obtained up to 75% of base metal (ω = 16,000 rpm, ν = 110 mm/min). The results of different welding parameters demonstrate that the high rotation speed can increase material mixing and reduce the axial force (z force), and it can benefit lightweight sheet welding by using FSW robot.

Dynamics and control of infections on social networks of population types.

PubMed

Williams, Brian G; Dye, Christopher

2018-06-01

Random mixing in host populations has been a convenient simplifying assumption in the study of epidemics, but neglects important differences in contact rates within and between population groups. For HIV/AIDS, the assumption of random mixing is inappropriate for epidemics that are concentrated in groups of people at high risk, including female sex workers (FSW) and their male clients (MCF), injecting drug users (IDU) and men who have sex with men (MSM). To find out who transmits infection to whom and how that affects the spread and containment of infection remains a major empirical challenge in the epidemiology of HIV/AIDS. Here we develop a technique, based on the routine sampling of infection in linked population groups (a social network of population types), which shows how an HIV/AIDS epidemic in Can Tho Province of Vietnam began in FSW, was propagated mainly by IDU, and ultimately generated most cases among the female partners of MCF (FPM). Calculation of the case reproduction numbers within and between groups, and for the whole network, provides insights into control that cannot be deduced simply from observations on the prevalence of infection. Specifically, the per capita rate of HIV transmission was highest from FSW to MCF, and most HIV infections occurred in FPM, but the number of infections in the whole network is best reduced by interrupting transmission to and from IDU. This analysis can be used to guide HIV/AIDS interventions using needle and syringe exchange, condom distribution and antiretroviral therapy. The method requires only routine data and could be applied to infections in other populations. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

NASA Astrophysics Data System (ADS)

Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

2017-10-01

The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

On the effect of β phase on the microstructure and mechanical properties of friction stir welded commercial brass alloys.

PubMed

Heidarzadeh, Akbar; Saeid, Tohid

2015-12-01

Conventional fusion welding of brass (Cu-Zn) alloys has some difficulties such as evaporation of Zn, toxic behavior of Zn vapor, solidification cracking, distortion, and oxidation [1], [2], [3]. Fortunately, friction stir welding (FSW) has been proved to be a good candidate for joining the brass alloys, which can overcome the fusion welding short comes [4], [5], [6], [7]. The data presented here relates to FSW of the single and double phase brass alloys. The data is the microstructure and mechanical properties of the base metals and joints.

On the effect of β phase on the microstructure and mechanical properties of friction stir welded commercial brass alloys

PubMed Central

Heidarzadeh, Akbar; Saeid, Tohid

2015-01-01

Conventional fusion welding of brass (Cu–Zn) alloys has some difficulties such as evaporation of Zn, toxic behavior of Zn vapor, solidification cracking, distortion, and oxidation [1], [2], [3]. Fortunately, friction stir welding (FSW) has been proved to be a good candidate for joining the brass alloys, which can overcome the fusion welding short comes [4], [5], [6], [7]. The data presented here relates to FSW of the single and double phase brass alloys. The data is the microstructure and mechanical properties of the base metals and joints. PMID:26793745

Cycle 24 HST+COS Target Acquisition Monitor Summary

NASA Astrophysics Data System (ADS)

Penton, Steven V.; White, James

2018-06-01

HST/COS calibration program 14847 (P14857) was designed to verify that all three COS Target Acquisition (TA) modes were performing nominally during Cycle 24. The program was designed not only to determine if any of the COS TA flight software (FSW) patchable constants need updating but also to determine the values of any required parameter updates. All TA modes were determined to be performing nominally during the Cycle 24 calendar period of October 1, 2016 - October 1, 2017. No COS SIAF, TA subarray, or FSW parameter updates were required as a result of this program.

Characterization of the Micro Textures in a Friction Stir Weld

NASA Technical Reports Server (NTRS)

Schneider, Judy; Nunes, Arthur C.

2004-01-01

In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. The Dynamically-Recrystallized-Zone (DXZ) of a polished and etched FSW cross-section exhibits contrasting bands (the "onion-ring" structure), the origins of which are unclear. An orientation image mapping (OIM) study suggests that the corresponding bands may correspond respectively to a "straight-through" current of metal bypassing the pin tool in a single rotation or less and a "maelstrom" current rotating a number of times around the pin tool.

Inspecting Friction Stir Welding using Electromagnetic Probes

NASA Technical Reports Server (NTRS)

Kinchen, David G.

2004-01-01

A report describes the use of advanced electromagnetic probes to measure the dimensions, the spatial distribution of electrical conductivity, and related other properties of friction stir welds (FSWs) between parts made of the same or different aluminum alloy(s). The probes are of the type described in in another Tech Brief. To recapitulate: A probe of this type is essentially an eddy-current probe that includes a primary (driver) winding that meanders and multiple secondary (sensing) windings that meander along the primary winding. Electrical conductivity is commonly used as a measure of heat treatment and tempering of aluminum alloys, but prior to the development of these probes, the inadequate sensitivity and limited accuracy of electrical-conductivity probes precluded such use on FSWs between different aluminum alloys, and the resolution of those probes was inadequate for measurement of FSW dimensions with positions and metallurgical properties. In contrast, the present probes afford adequate accuracy and spatial resolution for the purposes of measuring the dimensions of FSW welds and correlating spatially varying electrical conductivities with metallurgical properties, including surface defects.

An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method

PubMed Central

Lee, Hyoungwook; Kim, Cheolhee; Song, Jung Han

2015-01-01

The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ), but the presence of a soft zone in the heat-affected zone (HAZ) was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM). The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC) methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties. PMID:28793720

An Evaluation of Global and Local Tensile Properties of Friction-Stir Welded DP980 Dual-Phase Steel Joints Using a Digital Image Correlation Method.

PubMed

Lee, Hyoungwook; Kim, Cheolhee; Song, Jung Han

2015-12-04

The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction-stir-welded (FSW) dual-phase (DP) steel was investigated for the potential applications on the lightweight design of vehicles. Friction-stir-welded specimens with a butt joint configuration were prepared, and quasi-static tensile tests were conducted, to evaluate the tensile properties of DP980 dual-phase steels. The friction-stir welding led to the formation of martensite and a significant hardness rise in the stir zone (SZ), but the presence of a soft zone in the heat-affected zone (HAZ) was caused by tempering of the pre-existing martensite. Owing to the appearance of severe soft zone, DP980 FSW joint showed almost 93% joint efficiency with the view-point of ultimate tensile strength and relatively low ductility than the base metal (BM). The local tensile deformation characteristic of the FSW joints was also examined using the digital image correlation (DIC) methodology by mapping the global and local strain distribution, and was subsequently analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous, leading to a significant decrease in global ductility. The HAZ of the joints is the weakest region where the strain localizes early, and this localization extends until fracture with a strain near 30%, while the strain in the SZ and BM is only 1% and 4%, respectively. Local constitutive properties in different heterogeneous regions through the friction-stir-welded joint was also briefly evaluated by assuming iso-stress conditions. The local stress-strain curves of individual weld zones provide a clear indication of the heterogeneity of the local mechanical properties.

Correlates of HIV infection among street-based and venue-based sex workers in Vietnam.

PubMed

Le, Thuy Tc; Nguyen, Quoc C; Tran, Ha Tt; Schwandt, Michael; Lim, Hyun J

2016-10-01

Commercial sex work is one of the driving forces of the HIV epidemic across the world. In Vietnam, although female sex workers (FSWs) carry a disproportionate burden of HIV, little is known about the risk profile and associated factors for HIV infection among this population. There is a need for large-scale research to obtain reliable and representative estimates of the measures of association. This study involved secondary data analysis of the 'HIV/STI Integrated Biological and Behavioral Surveillance' study in Vietnam in 2009-2010 to examine the correlates of HIV among FSWs. Data collected from 5298 FSWs, including 2530 street-based sex workers and 2768 venue-based sex workers from 10 provinces in Vietnam, were analyzed using descriptive statistics and bivariate and multivariate logistic regression analyses. HIV prevalence among the overall FSW population was 8.6% (n = 453). However, when stratified by FSW subpopulations, HIV prevalence was 10.6% (n = 267) for street-based sex workers and 6.7% (n = 186) for venue-based sex workers. Factors independently associated with HIV infection in the multivariate analysis, regardless of sex work types, were injecting drug use, high self-perceived HIV risk, and age ≥ 25 years. Additional factors independently associated with HIV risk within each FSW subpopulation included having ever been married among street-based sex workers and inconsistent condom use with clients and having sex partners who injected drugs among venue-based sex workers. Apart from strategies addressing modifiable risk behaviours among all FSWs, targeted strategies to address specific risk behaviours within each FSW subpopulation should be adopted. © The Author(s) 2016.

Decompression tables for inside chamber attendants working at altitude.

PubMed

Bell, James; Thombs, Paul A; Davison, William J; Weaver, Lindell K

2014-01-01

Hyperbaric oxygen (HBO2) multiplace chamber inside attendants (IAs) are at risk for decompression sickness (DCS). Standard decompression tables are formulated for sea-level use, not for use at altitude. At Presbyterian/St. Luke's Medical Center (Denver, Colorado, 5,924 feet above sea level) and Intermountain Medical Center (Murray, Utah, 4,500 feet), the decompression obligation for IAs is managed with U.S. Navy Standard Air Tables corrected for altitude, Bühlmann Tables, and the Nobendem© calculator. IAs also breathe supplemental oxygen while compressed. Presbyterian/St. Luke's (0.83 atmospheres absolute/atm abs) uses gauge pressure, uncorrected for altitude, at 45 feet of sea water (fsw) (2.2 atm abs) for routine wound care HBO2 and 66 fsw (2.8 atm abs) for carbon monoxide/cyanide poisoning. Presbyterian/St. Luke's provides oxygen breathing for the IAs at 2.2 atm abs. At Intermountain (0.86 atm abs), HBO2 is provided at 2.0 atm abs for routine treatments and 3.0 atm abs for carbon monoxide poisoning. Intermountain IAs breathe intermittent 50% nitrogen/50% oxygen at 3.0 atm abs and 100% oxygen at 2.0 atm abs. The chamber profiles include a safety stop. From 1990-2013, Presbyterian/St. Luke's had 26,900 total IA exposures: 25,991 at 45 fsw (2.2 atm abs) and 646 at 66 fsw (2.8 atm abs); there have been four cases of IA DCS. From 2008-2013, Intermountain had 1,847 IA exposures: 1,832 at 2 atm abs and 15 at 3 atm abs, with one case of IA DCS. At both facilities, DCS incidents occurred soon after the chambers were placed into service. Based on these results, chamber inside attendant risk for DCS at increased altitude is low when the inside attendants breathe supplemental oxygen.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial.

PubMed

Sobouti, Farhad; Rakhshan, Vahid; Saravi, Mahdi Gholamrezaei; Zamanian, Ali; Shariati, Mahsa

2016-03-01

Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results.

Two-year survival analysis of twisted wire fixed retainer versus spiral wire and fiber-reinforced composite retainers: a preliminary explorative single-blind randomized clinical trial

PubMed Central

Sobouti, Farhad; Rakhshan, Vahid; Saravi, Mahdi Gholamrezaei; Zamanian, Ali

2016-01-01

Objective Traditional retainers (both metal and fiber-reinforced composite [FRC]) have limitations, and a retainer made from more flexible ligature wires might be advantageous. We aimed to compare an experimental design with two traditional retainers. Methods In this prospective preliminary clinical trial, 150 post-treatment patients were enrolled and randomly divided into three groups of 50 patients each to receive mandibular canine-to-canine retainers made of FRC, flexible spiral wire (FSW), and twisted wire (TW). The patients were monitored monthly. The time at which the first signs of breakage/debonding were detected was recorded. The success rates of the retainers were compared using chi-squared, Kaplan-Meier, and Cox proportional-hazard regression analyses (α = 0.05). Results In total, 42 patients in the FRC group, 41 in the FSW group, and 45 in the TW group completed the study. The 2-year failure rates were 35.7% in the FRC group, 26.8% in the FSW group, and 17.8% in the TW group. These rates differed insignificantly (chi-squared p = 0.167). According to the Kaplan-Meier analysis, failure occurred at 19.95 months in the FRC group, 21.37 months in the FSW group, and 22.36 months in the TW group. The differences between the survival rates in the three groups were not significant (Cox regression p = 0.146). Conclusions Although the failure rate of the experimental retainer was two times lower than that of the FRC retainer, the difference was not statistically significant. The experimental TW retainer was successful, and larger studies are warranted to verify these results. PMID:27019825

The Effect of Cu Powder During Friction Stir Welding on Microstructure and Mechanical Properties of AA3003-H18

NASA Astrophysics Data System (ADS)

Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

2014-08-01

Friction stir welding (FSW) was used to join 3003-H18 non-heat-treatable aluminum alloy plates by adding copper powder. The copper powder was first added to the gap (0.1 and 0.2 mm) between two plates and then the FSW was performed. The specimens were joined at various rotational speeds of 800, 1000, and 1200 rpm at traveling speeds of 70 and 100 mm/min. The effects of rotational speed, second pass of FSW, and direction of second pass also were studied on copper particle distribution and formation of Al-Cu intermetallic compounds in the stir zone. The second pass of FSW was carried out in two ways; in line with the first pass direction (2F) and in the reverse direction of the first pass (FB). The microstructure, mechanical properties, and formation of intermetallic compounds type were investigated. In high copper powder compaction into the gap, large clusters were formed in the stir zone, while fine clusters and sound copper particles distribution were obtained in low powder compaction. The copper particle distribution and amount of Al-Cu intermetallic compounds were increased in the stir zone with increasing the rotational speed and applying the second pass. Al2Cu and AlCu intermetallic phases were formed in the stir zone and consequently the hardness was significantly increased. The copper particles and in situ intermetallic compounds were symmetrically distributed in both advancing and retreating sides of weld zone after FB passes. Thus, the wider area was reinforced by the intermetallic compounds. Also, the tensile test specimens tend to fracture from the coarse copper aggregation at the low rotational speeds. At high rotational speeds, the fracture locations are placed in HAZ and TMAZ.

HIV risks and needs related to the Sustainable Development Goals among female sex workers who were commercially sexually exploited as children in Lesotho.

PubMed

Grosso, Ashley; Busch, Shianne; Mothopeng, Tampose; Sweitzer, Stephanie; Nkonyana, John; Mpooa, Nkomile; Taruberekera, Noah; Baral, Stefan

2018-02-01

Sustainable Development Goals (SDGs) about gender equality; decent work; and peace, justice, and strong institutions include a focus on eradicating trafficking and sexual exploitation of and violence against women and children. In Lesotho, 86% of women have experienced gender-based violence. In addition, overall HIV prevalence is among the highest globally, and higher among adolescent girls than boys. Moreover, nearly three quarters of female sex workers (FSW) are estimated to be living with HIV in Lesotho. In this context, sexually exploited children may be particularly vulnerable to violence and HIV acquisition risks. This study's objective is to examine the prevalence and correlates of experiencing sexual exploitation as a child among FSW in Lesotho. FSW (≥18 years) recruited through respondent-driven sampling in Maseru and Maputsoe from February to September 2014 completed HIV and syphilis testing and an interviewer-administered survey, including a question about the age at which they started providing sex for money. This study examined correlates of experiencing sexual exploitation as a child (<18 years) through multivariable logistic regression analyses for each city, controlling for current age. Across both cities, 20.0% (142/710) of participants were sexually exploited as children. Among them, 65.5% (93/142) tested positive for HIV and 31.0% (44/142) for syphilis, which was similar to those who started selling sex as adults, after adjusting for current age. Participants who experienced child sexual exploitation were more likely to have been forced to have sex before age 18 than those who started selling sex as adults (Maseru-adjusted odds ratio (aOR): 3.52, 95% Confidence Interval (CI): 1.61 to 7.66, p = 0.002; Maputsoe-aOR: 4.39, 95% CI: 1.22 to 15.75, p = 0.023). In Maseru, participants who were sexually exploited as children were more likely to avoid carrying condoms to prevent trouble with police (aOR: 3.18, 95% CI: 1.50 to 6.75, p = 0.003). Risk determinants for HIV and violence among sexually exploited children can be studied retrospectively through research with adult FSW. Further research working directly with sexually exploited children will improve understanding of their needs. Preventing commercial sexual exploitation of children and addressing the social and healthcare needs of those who are exploited are necessary to fully achieve SDGs 5, 8 and 16 and an AIDS-Free Generation. © 2018 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

NASA Astrophysics Data System (ADS)

Pan, Yi; Lados, Diana A.

2017-04-01

Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

Upgrading weld quality of a friction stir welded aluminum alloys AMG6

NASA Astrophysics Data System (ADS)

Chernykh, I. K.; Vasil'ev, E. V.; Matuzko, E. N.; Krivonos, E. V.

2018-01-01

In the course of introduction of FSW technology into the industry there is a keen interest in this process; there are issues such as how does joining take place, what is the structure of the joint, and where there are dangerous zones. The objective of this research is to obtain information about the structure of the joint, what are the temperatures that arise during the joining, what strength is apply to the tool when joining the material, what tensile strength of joint, and where fracture tended to occur. Specimens were produced at different modes of welding at a tool rotation speed of 315 to 625 rpm and tool travel speed of 40 to 125 mm/min. During the experiment, the strength applied to the tool was measured, which reached 800016000 N (Fz) and 400-1400 N (Fx) and the temperature on the surface of the tool, which is in the range 250-400°C. Before the welding process the tool was heated to a temperature in the range of 100-250 degrees, but the tensile strength is not had a tangible impact. The tensile strength is about 80 % of that of the aluminum alloy base metal tensile strength, and fracture tended is occur not at the line of joint but follow the shape of the tool. In the transverse cross section of a FSW material there is a microstructural regions such as weld nugget, thermomechanically affected zone and heat-affected zone with parent material.

The microstructure and microhardness of friction stir welded dissimilar copper/Al-5% Mg alloys

NASA Astrophysics Data System (ADS)

Kalashnikova, T. A.; Shvedov, M. A.; Vasilyev, P. A.

2017-12-01

A friction stir welded joint between copper and aluminum alloy has been investigated and characterized for the microstructure and microhardness number distribution. The microstructural evolution of the joint is studied using optical microscopy and microhardness. The mechanical characteristics in structural zones of FSW joints are determined by Vickers microhardness measurements. Samples were cut across the cross section. It is shown that intermetallic Cu/Al particles are formed at interfaces. The intermetallics microhardness in the dissimilar aluminum/cooper FSW joint differs from that of the joint produced by fusion welding. The grain structures obtained in different dissimilar joint zones are examined.

Multi-Day Air Saturation at 20 and 22 FSW With Direct Ascent: Data Report on Project 92-09

DTIC Science & Technology

2002-03-01

0802 0 air L/S; Divers 7, 8, 9, 10, 11, 12 0803 22 air R/B Feb 09 1919 22 air DMO entry, Diver 12 has scratchy throat and post-nasal drip, given aspirin...10,11, fsw 12 _ Galley is shipshape as is food. 1919 8 OK Robinson 12 describes scratchy throat & post nasal drip with ????? with purulent nasal...Ball 12 scratchy throat , sniffles, ASA 2 PO every 4 hrs 9 no c/o 7 no c/o 10 no c/o 11 mild congestion, Sudafed 60 mg Divers in good spirits 1250 8

Microstructure Evolution during Dissimilar Friction Stir Welding of AA7003-T4 and AA6060-T4.

PubMed

Dong, Jialiang; Zhang, Datong; Zhang, Weiwen; Zhang, Wen; Qiu, Cheng

2018-02-27

In this work, the dissimilar joint of AA7003-T4 and 6060-T4 alloy has been produced by friction stir welding (FSW). The microstructure was examined by optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and the mechanical properties of the joint were investigated. It is demonstrated that sound dissimilar joint can be produced through FSW. In the nugget; precipitations dissolve into the matrix and η' reprecipitate subsequently; and the elongated aluminum grains are replaced by fine and equiaxed grains due to dynamic recrystallization (DRX). In the heat affected zone (HAZ), coarse β' and η precipitates are formed and the aluminum grains are coarser as compared to the base materials. In the thermo-mechanical affected zone (TMAZ), equiaxed and elongated grains coexist due to incomplete DRX. The ultimate tensile strength of the dissimilar joint is 159.2 MPa and its elongation is 10.4%. The weak area exists in the HAZ of 6060 alloy, which is placed in the retreating side during FSW. The correlations between the microstucture and mechanical properties of the dissimilar joint are discussed.

Microstructure Evolution during Dissimilar Friction Stir Welding of AA7003-T4 and AA6060-T4

PubMed Central

Dong, Jialiang; Zhang, Datong; Zhang, Weiwen; Zhang, Wen; Qiu, Cheng

2018-01-01

In this work, the dissimilar joint of AA7003-T4 and 6060-T4 alloy has been produced by friction stir welding (FSW). The microstructure was examined by optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and the mechanical properties of the joint were investigated. It is demonstrated that sound dissimilar joint can be produced through FSW. In the nugget; precipitations dissolve into the matrix and η′ reprecipitate subsequently; and the elongated aluminum grains are replaced by fine and equiaxed grains due to dynamic recrystallization (DRX). In the heat affected zone (HAZ), coarse β′ and η precipitates are formed and the aluminum grains are coarser as compared to the base materials. In the thermo-mechanical affected zone (TMAZ), equiaxed and elongated grains coexist due to incomplete DRX. The ultimate tensile strength of the dissimilar joint is 159.2 MPa and its elongation is 10.4%. The weak area exists in the HAZ of 6060 alloy, which is placed in the retreating side during FSW. The correlations between the microstucture and mechanical properties of the dissimilar joint are discussed. PMID:29495463

Differing HIV vulnerability among female sex workers in a high HIV burden Indian state.

PubMed

Mamulwar, Megha; Godbole, Sheela; Bembalkar, Shilpa; Kamble, Pranil; Dulhani, Nisha; Yadav, Rajesh; Kadu, Chitra; Kumar, Pradeep; Lalikar, Shivraj; Acharya, Shrikala; Gangakhedkar, Raman; Risbud, Arun; Venkatesh, Srinivas

2018-01-01

The HIV sentinel surveillance [HSS] conducted in 2010-11 among female sex workers [FSW] in the state of Maharashtra, India provided an opportunity to assess characteristics of different types of FSWs and their HIV risk. It is important for India's National AIDS Control Program, to understand the differences in vulnerability among these FSW, in order to define more specific and effective risk reduction intervention strategies. Therefore, we analyzed data from HSS with the objective of understanding the HIV vulnerability among different types of FSW in Maharashtra. Cross sectional data collected as a part of HSS among FSWs in year 2010-11 from 21 sentinel sites in the state of Maharashtra were analyzed to understand the vulnerability and characteristics of different types of female sex workers based on their place of solicitation using multinomial logistic regression. While the HIV prevalence was 6.6% among all FSWs, it was 9.9% among brothel based [BB], 9% among street based [SB] and 3.1% and 3.7% among home based [HB], and bar based [Bar-B] sex workers respectively. SB FSWs were least likely to be located in HIV low burden districts [ANC] [ARRR: 0.61[95% CI: 0.49, 0.77

Estimating the number of female sex workers in Côte d'Ivoire: results and lessons learned.

PubMed

Vuylsteke, Bea; Sika, Lazare; Semdé, Gisèle; Anoma, Camille; Kacou, Elise; Laga, Marie

2017-09-01

To report on the results of three size estimations of the populations of female sex workers (FSW) in five cities in Côte d'Ivoire and on operational lessons learned, which may be relevant for key population programmes in other parts of the world. We applied three methods: mapping and census, capture-recapture and service multiplier. All were applied between 2008 and 2009 in Abidjan, San Pedro, Bouaké, Yamoussoukro and Abengourou. Abidjan was the city with the highest number of FSW by far, with estimations between 7880 (census) and 13 714 (service multiplier). The estimations in San Pedro, Bouaké and Yamoussoukro were very similar, with figures ranging from 1160 (Yamoussoukro, census) to 1916 (San Pedro, capture-recapture). Important operational lessons were learned, including strategies for mapping, the importance of involving peer sex workers for implementing the capture-recapture and the identification of the right question for the multiplier method. Successful application of three methods to estimate the population size of FSW in five cities in Côte d'Ivoire enabled us to make recommendations for size estimations of key population in low-income countries. © 2017 John Wiley & Sons Ltd.

Prevalence of rape and client-initiated gender-based violence among female sex workers: Kampala, Uganda, 2012.

PubMed

Schwitters, Amee; Swaminathan, Mahesh; Serwadda, David; Muyonga, Michael; Shiraishi, Ray W; Benech, Irene; Mital, Sasha; Bosa, Rose; Lubwama, George; Hladik, Wolfgang

2015-02-01

We utilized data from the 2012 Crane Survey in Kampala, Uganda to estimate prevalence of rape among female sex workers (FSWs) and to identify risk factors for and prevalence of client-initiated gender-based violence (GBV) among FSWs. Participants were recruited using respondent-driven sampling. Analyses were weighted using RDSAT-generated individualized weights for each of the five dependent GBV outcomes. Analyses were conducted utilizing SAS 9.3. Among 1,467 FSWs who were interviewed, 82 % (95 % CI: 79-84) experienced client-initiated GBV and 49 % (95 % CI: 47-53) had been raped at least once in their lifetime. GBV risk increased with increasing frequency of client demands for unprotected sex, length of time engaged in sex work, and FSW alcohol consumption. Risk decreased when sex with clients occurred at the FSW's or client's house or a hotel compared to when sex occurred in open spaces. Our findings demonstrate a high prevalence of GBV among FSWs. This research reinforces the urgent need for GBV prevention and response strategies to be integrated into FSW programming and the continuing need for GBV research among key populations.

Flow in the Proximity of the Pin-Tool in Friction Stir Welding and Its Relation to Weld Homogeneity

NASA Technical Reports Server (NTRS)

Nunes, Arthur C., Jr.

2000-01-01

In the Friction Stir Welding (FSW) process a rotating pin inserted into a seam literally stirs the metal from each side of the seam together. It is proposed that the flow in the vicinity of the pin-tool comprises a primary rapid shear over a cylindrical envelope covering the pin-tool and a relatively slow secondary flow taking the form of a ring vortex about the tool circumference. This model is consistent with a plastic characterization of metal flow, where discontinuities in shear flow are allowed but not viscous effects. It is consistent with experiments employing several different kinds of tracer: atomic markers, shot, and wire. If a rotating disc with angular velocity w is superposed on a translating continuum with linear velocity omega, the trajectories of tracer points become circular arcs centered upon a point displaced laterally a distance v/omega from the center of rotation of the disc in the direction of the advancing side of the disc. In the present model a stream of metal approaching the tool (taken as the coordinate system of observation) is sheared at the slip surface, rapidly rotated around the tool, sheared again on the opposite side of the tool, and deposited in the wake of the tool. Local shearing rates are high, comparable to metal cutting in this model. The flow patterns in the vicinity of the pin-tool determine the level of homogenization and dispersal of contaminants that occurs in the FSW process. The approaching metal streams enfold one another as they are rotated around the tool. Neglecting mixing they return to the same lateral position in the wake of the tool preserving lateral tracer positions as if the metal had flowed past the tool like an extrusion instead of being rotated around it. (The seam is, however, obliterated.) The metal stream of thickness approximately that of the tool diameter D is wiped past the tool at elevated temperatures drawn out to a thickness of v/2(omega) in the wiping zone. Mixing distances in the wiping zone are multiplied in the unfolded metal. Inhomogeneities on a smaller scale than the mixing length are obliterated, but structure on a larger scale may be transmitted to the wake of a FSW weld.

[Survey adaptation for bio-behavioural surveillance of HIV in Chilean female sex workers].

PubMed

Carvajal, Bielka; Stuardo, Valeria; Manríquez, José Manuel; Belmar, Julieta; Folch, Cinta

To adapt a behavioural questionnaire for second-generation HIV/AIDS surveillance in female sex workers (FSWs) in the Metropolitan Region, Chile. Qualitative study of instruments validation. A Spanish instrument adapted in Catalonia was validated through a translation and back-translation of the original version. The content validity was determined through a modified Delphi method, via FSW and HIV experts representing community, political and institutional levels. Applicability aspects were determined by the application of the questionnaire to FSW in the Metropolitan Region. The questionnaire, drafted in Spain, was successfully adapted to Chilean Spanish. The content validity process enabled sections to be created that address HIV in FSWs. The adapted questionnaire takes less than 15minutes to complete, which makes it usable in fieldwork. The 61 women surveyed came from different countries (all were Latin Americans) and had different educational levels; all this enabled potential applicability problems to be detected. The adapted questionnaire for Chile contains all the UNAIDS indicators for FSWs, as well as the recommended indicators of Family Health International for bio-behavioural surveillance. Said questionnaire serves as a tool for second-generation HIV/other STD surveillance and further contributes to preventive policies in Chilean FSWs. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

Effects of Laser and Shot Peening on Fatigue Crack Growth in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Hatamleh, Omar; Forman, Royce; Lyons, Jed

2006-01-01

The effects of laser, and shot peening on the fatigue life of Friction Stir Welds (FSW) have been investigated. The surface roughness resulting from various peening techniques was assessed, and the fracture surfaces microstructure was characterized. Laser peening resulted in an increase in fatigue life approximately 60%, while shot peening resulted in 10% increase when compared to the unpeened material. The surface roughness of shot peening was significantly higher compared to the base material, while specimens processed with laser peening were relatively smooth.

Performance Improvement of Friction Stir Welds by Better Surface Finish

NASA Technical Reports Server (NTRS)

Russell, Sam; Nettles, Mindy

2015-01-01

The as-welded friction stir weld has a cross section that may act as a stress concentrator. The geometry associated with the stress concentration may reduce the weld strength and it makes the weld challenging to inspect with ultrasound. In some cases, the geometry leads to false positive nondestructive evaluation (NDE) indications and, in many cases, it requires manual blending to facilitate the inspection. This study will measure the stress concentration effect and develop an improved phased array ultrasound testing (PAUT) technique for friction stir welding. Post-welding, the friction stir weld (FSW) tool would be fitted with an end mill that would machine the weld smooth, trimmed shaved. This would eliminate the need for manual weld preparation for ultrasonic inspections. Manual surface preparation is a hand operation that varies widely depending on the person preparing the welds. Shaving is a process that can be automated and tightly controlled.

Health Services Use and HIV Prevalence Among Migrant and National Female Sex Workers in Portugal: Are We Providing the Services Needed?

PubMed

Dias, Sónia; Gama, Ana; Pingarilho, Marta; Simões, Daniel; Mendão, Luís

2017-08-01

This cross-sectional bio-behavioral survey conducted with 853 female sex workers (FSW) aimed to examine differences in use of HIV health services, testing and prevalence among migrant and national FSW. A quarter of undocumented FSW had never used National Health Service (NHS) and 15 % never tested for HIV, significantly more than nationals (p < 0.001 and p = 0.024, respectively). HIV infection was self-reported by 11.9 % of nationals, 1.8 % of documented and 0.8 % of undocumented migrants (p < 0.001). The HIV rapid test was reactive in 13.6 % of undocumented, 8.0 % of nationals and 2.3 % of documented. A higher proportion of migrants were unaware of their positive serostatus compared to nationals. Ever had HIV testing was less likely among undocumented, who never used the NHS and who didn't know where to go if suspected being HIV-infected. Promoting early diagnosis with linkage to care among migrant FSW should be supported, while developing health services better tailored to their needs. Una encuesta transversal biocomportamental fue realizada con una muestra de 853 trabajadoras sexuales (TS) con el objetivo de examinar diferencias en el uso de servicios de salud del VIH, test y prevalencia entre TS migrantes y nacionales. Un cuarto de las TS indocumentadas nunca utilizaron el Servicio Nacional de Salud (SNS) y el 15 % nunca fueron testadas respecto al VIH, porcentajes significativamente superiores a las observadas para las nacionales (p < 0.001 y p = 0.024, respectivamente). La infección por VIH fue auto reportada por 11.9 % de las nacionales, 1.8 % de las migrantes documentadas y 0.8 % de las indocumentadas (p < 0.001). El test rápido del VIH fue reactivo para un 13.6 % de las indocumentadas, 8.0 % de las nacionales y 2.3 % de las documentadas. Una proporción mayor de migrantes desconocía su serostatus positivo en comparación con las nacionales. El test del VIH fue menos frecuente entre las indocumentadas, quien nunca utilizó el SNS y quien no sabía dónde recurrir si sospechaba estar infectada por el VIH. Promover un diagnóstico precoz en conexión con los cuidados en TS migrantes debe ser respaldado mientras se desarrollan servicios de salud mejor adaptados a sus necesidades.

cFE/CFS (Core Flight Executive/Core Flight System)

NASA Technical Reports Server (NTRS)

Wildermann, Charles P.

2008-01-01

This viewgraph presentation describes in detail the requirements and goals of the Core Flight Executive (cFE) and the Core Flight System (CFS). The Core Flight Software System is a mission independent, platform-independent, Flight Software (FSW) environment integrating a reusable core flight executive (cFE). The CFS goals include: 1) Reduce time to deploy high quality flight software; 2) Reduce project schedule and cost uncertainty; 3) Directly facilitate formalized software reuse; 4) Enable collaboration across organizations; 5) Simplify sustaining engineering (AKA. FSW maintenance); 6) Scale from small instruments to System of Systems; 7) Platform for advanced concepts and prototyping; and 7) Common standards and tools across the branch and NASA wide.

Second COS FUV Lifetime Position: FUV Target Acquisition Parameter Update {FENA4}

NASA Astrophysics Data System (ADS)

Penton, Steven

2011-10-01

Verify the ability of the Cycle 20 COS FSW to place an isolated point source at the center of the PSA, using FUV dispersed light target acquisition {TA} from the object and all three FUV gratings at the Second Lifetime Position {SLP}. This program is modeled from the activity summary of FENA4.This program should be executed after the new HV, XD spectral positions, and focus are determined and updated. In addition, the LIFETIME=ALTERNATE TA FSW parameters should be updated prior to execution of this program.NUV imaging TAs have previously been used to determine the correct locations for FUV spectra. We follow the same procedure here.

Effect of Water Cooling on the Performances of Friction Stir Welding Heat-Affected Zone

NASA Astrophysics Data System (ADS)

Zhang, H. J.; Liu, H. J.; Yu, L.

2012-07-01

The heat-affected zone (HAZ) is generally the intrinsic weakest location of the normal friction stir welded precipitate hardened aluminum alloys. In order to improve the mechanical properties of the HAZ by controlling the temperature level, underwater friction stir welding (FSW) of an Al-Cu aluminum alloy was conducted in the present study. The results indicate that the hardness of the HAZ can be improved through underwater FSW. Microstructural analysis reveals that the hardness improvement is attributed to the lowering of precipitate coarsening level and the narrowing of precipitate free zone, which are essentially induced by the variations of welding thermal cycles under the cooling effect of water.

Microstructure and mechanical properties of friction stir welded and laser welded high entropy alloy CrMnFeCoNi

NASA Astrophysics Data System (ADS)

Jo, Min-Gu; Kim, Han-Jin; Kang, Minjung; Madakashira, Phaniraj P.; Park, Eun Soo; Suh, Jin-Yoo; Kim, Dong-Ik; Hong, Sung-Tae; Han, Heung Nam

2018-01-01

The high entropy alloy CrMnFeCoNi has been shown to have promising structural properties. For a new alloy to be used in a structural application it should be weldable. In the present study, friction stir welding (FSW) and laser welding (LW) techniques were used to butt weld thin plates of CrMnFeCoNi. The microstructure, chemical homogeneity and mechanical behavior of the welds were characterized and compared with the base metal. The tensile stress-strain behavior of the welded specimens were reasonable when compared with that of the base metal. FSW refined the grain size in the weld region by a factor of ˜14 when compared with the base metal. High-angle annular dark field transmission electron microscopy in combination with energy dispersive X-ray spectroscopy showed chemical inhomogeneity between dendritic and interdendritic regions in the fusion zone of LW. Large fluctuations in composition (up to 15 at%) did not change the crystal structure in the fusion zone. Hardness measurements were carried out in the weld cross section and discussed in view of the grain size, low angle grain boundaries and twin boundaries in FSW specimens and the dendritic microstructure in LW specimens.

Hydrogen accelerated fatigue crack growth of friction stir welded X52 steel pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ronevich, Joseph Allen; Somerday, Brian P.; Feng, Zhili

Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitudemore » compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. In conclusion, the X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.« less

Hydrogen accelerated fatigue crack growth of friction stir welded X52 steel pipe

DOE PAGES

Ronevich, Joseph Allen; Somerday, Brian P.; Feng, Zhili

2016-11-17

Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitudemore » compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. In conclusion, the X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.« less

Orion MPCV Touchdown Detection Threshold Development and Testing

NASA Technical Reports Server (NTRS)

Daum, Jared; Gay, Robert

2013-01-01

A robust method of detecting Orion Multi-Purpose Crew Vehicle (MPCV) splashdown is necessary to ensure crew and hardware safety during descent and after touchdown. The proposed method uses a triple redundant system to inhibit Reaction Control System (RCS) thruster firings, detach parachute risers from the vehicle, and transition to the post-landing segment of the Flight Software (FSW). An in-depth trade study was completed to determine optimal characteristics of the touchdown detection method resulting in an algorithm monitoring filtered, lever-arm corrected, 200 Hz Inertial Measurement Unit (IMU) vehicle acceleration magnitude data against a tunable threshold using persistence counter logic. Following the design of the algorithm, high fidelity environment and vehicle simulations, coupled with the actual vehicle FSW, were used to tune the acceleration threshold and persistence counter value to result in adequate performance in detecting touchdown and sufficient safety margin against early detection while descending under parachutes. An analytical approach including Kriging and adaptive sampling allowed for a sufficient number of finite element analysis (FEA) impact simulations to be completed using minimal computation time. The combination of a persistence counter of 10 and an acceleration threshold of approximately 57.3 ft/s2 resulted in an impact performance factor of safety (FOS) of 1.0 and a safety FOS of approximately 2.6 for touchdown declaration. An RCS termination acceleration threshold of approximately 53.1 ft/s(exp)2 with a persistence counter of 10 resulted in an increased impact performance FOS of 1.2 at the expense of a lowered under-parachutes safety factor of 2.2. The resulting tuned algorithm was then tested on data from eight Capsule Parachute Assembly System (CPAS) flight tests, showing an experimental minimum safety FOS of 6.1. The formulated touchdown detection algorithm will be flown on the Orion MPCV FSW during the Exploration Flight Test 1 (EFT-1) mission in the second half of 2014.

HIV decline associated with changes in risk behaviours among young key populations in Nepal: analysis of population-based HIV prevalence surveys between 2001 and 2012.

PubMed

Deuba, Keshab; Ekström, Anna Mia; Tomson, Göran; Shrestha, Rachana; Marrone, Gaetano

2017-08-01

We assessed changes in HIV prevalence and risk behaviours among young key populations in Nepal. A total of 7505 participants (aged 16-24 years) from key populations who were at increased risk of HIV infection (2767 people who inject drugs (PWID); 852 men who have sex with men/transgender (MSM/TG); 2851 female sex workers (FSW) and 1035 male labour migrants) were recruited randomly over a 12-year period, 2001-2012. Local epidemic zones of Nepal (Kathmandu valley, Pokhara valley, Terai Highway and West to Far West hills) were analysed separately. We found a very strong and consistent decline in HIV prevalence over the past decade in different epidemic zones among PWID and MSM/TG in Kathmandu, the capital city, most likely due to a parallel increase in safe needle and syringe use and increased condom use. A decrease in HIV prevalence in 22 Terai highway districts, sharing an open border with India, was also consistent with increased condom use among FSW. Among male labour migrants, HIV prevalence was low throughout the period in the West to Far West hilly regions. Condom use by migrant workers involved with FSW abroad increased while their condom use with Nepalese FSW declined. Other risk determinants such as mean age at starting first injection, injection frequency, place of commercial sex solicitation, their mean age when leaving to work abroad did not change consistently across epidemic zones among the young key populations under study. In Nepal, the decline in HIV prevalence over the past decade was remarkably significant and consistent with an increase in condom use and safer use of clean needles and syringes. However, diverging trends in risk behaviours across local epidemic zones of Nepal suggest a varying degree of implementation of national HIV prevention policies. This calls for continued preventive efforts as well as surveillance to sustain the observed downward trend.

Anal intercourse among female sex workers in East Africa is associated with other high-risk behaviours for HIV.

PubMed

Veldhuijzen, Nienke J; Ingabire, Chantal; Luchters, Stanley; Bosire, Wilkister; Braunstein, Sarah; Chersich, Matthew; van de Wijgert, Janneke

2011-06-01

Epidemiological and HIV prevention studies in sub-Saharan Africa have almost exclusively focussed on vaginal transmission of HIV, the primary mode of transmission in the region. Little is known about the prevalence of heterosexual anal intercourse (AI), its correlates and its role in the spread of HIV. Prevention messaging seldom, if ever, includes AI. Sexual and other risk behaviours (including frequency of AI) were assessed in two cross-sectional surveys of female sex workers (FSW) in Kigali, Rwanda (n=800) and Mombasa, Kenya (n=820). In addition, a subset of FSW surveyed in Kigali attended seven focus group discussions and four in-depth interviews. AI was reported by 5.5% and 4.3% of FSW in the cross-sectional surveys, in Kigali and Mombasa, respectively. FSW practising AI reported multiple risk factors for HIV transmission: inconsistent condom use (odds ratio (OR) Kigali 5.9 (95% CI 1.4-24.7); OR Mombasa 2.1 (1.1-4.2)); more than five sexual partners in the past week (OR Kigali 4.3 (1.5-12.4); OR Mombasa 2.2 (1.1-4.3)); alcohol use before sex (OR Kigali 2.8 (1.4-5.8)); more than 5 years of female sex work (OR Mombasa 2.4 (1.2-4.9)); and history of genital symptoms in the past year (OR Mombasa 3.6 (1.7-7.9)). AI was, however, not associated with HIV prevalence (OR Kigali 0.9 (0.5-1.9); OR Mombasa 0.5 (0.2-1.2)). Negative connotations and stigma associated with AI were expressed during qualitative interviews. AI was associated with several indicators of sexual risk behaviour. Prevalence of AI was probably underreported due to social desirability bias. Stigma associated with AI poses methodological challenges in obtaining valid data.

Applying a nonlinear, pitch-catch, ultrasonic technique for the detection of kissing bonds in friction stir welds.

PubMed

Delrue, Steven; Tabatabaeipour, Morteza; Hettler, Jan; Van Den Abeele, Koen

2016-05-01

Friction stir welding (FSW) is a promising technology for the joining of aluminum alloys and other metallic admixtures that are hard to weld by conventional fusion welding. Although FSW generally provides better fatigue properties than traditional fusion welding methods, fatigue properties are still significantly lower than for the base material. Apart from voids, kissing bonds for instance, in the form of closed cracks propagating along the interface of the stirred and heat affected zone, are inherent features of the weld and can be considered as one of the main causes of a reduced fatigue life of FSW in comparison to the base material. The main problem with kissing bond defects in FSW, is that they currently are very difficult to detect using existing NDT methods. Besides, in most cases, the defects are not directly accessible from the exposed surface. Therefore, new techniques capable of detecting small kissing bond flaws need to be introduced. In the present paper, a novel and practical approach is introduced based on a nonlinear, single-sided, ultrasonic technique. The proposed inspection technique uses two single element transducers, with the first transducer transmitting an ultrasonic signal that focuses the ultrasonic waves at the bottom side of the sample where cracks are most likely to occur. The large amount of energy at the focus activates the kissing bond, resulting in the generation of nonlinear features in the wave propagation. These nonlinear features are then captured by the second transducer operating in pitch-catch mode, and are analyzed, using pulse inversion, to reveal the presence of a defect. The performance of the proposed nonlinear, pitch-catch technique, is first illustrated using a numerical study of an aluminum sample containing simple, vertically oriented, incipient cracks. Later, the proposed technique is also applied experimentally on a real-life friction stir welded butt joint containing a kissing bond flaw. Copyright © 2016 Elsevier B.V. All rights reserved.

Sex work and HIV in Cambodia: trajectories of risk and disease in two cohorts of high-risk young women in Phnom Penh, Cambodia.

PubMed

Page, Kimberly; Stein, Ellen; Sansothy, Neth; Evans, Jennifer; Couture, Marie-Claude; Sichan, Keo; Cockroft, Melissa; Mooney-Somers, Julie; Phlong, Pisith; Kaldor, John; Maher, Lisa

2013-09-10

HIV prevalence among Cambodian female sex workers (FSW) is among the highest in Southeast Asia. We describe HIV prevalence and associated risk exposures in FSW sampled serially in Phnom Penh, Cambodia (Young Women's Health Study (YWHS)), before and after the implementation of a new law designed to combat human trafficking and sexual exploitation. Cross-sectional analysis of baseline data from two prospective cohorts. Community-based study in Phnom Penh, Cambodia. Women aged 15-29 years, reporting ≥2 sexual partners in the last month and/or engaged in transactional sex in the last 3 months, were enrolled in the studies in 2007 (N=161; YWHS-1), and 2009 (N=220; YWHS-2) following information sessions where 285 and 345 women attended. HIV prevalence, sexual risk behaviour, amphetamine-type stimulant (ATS) and alcohol use, and work-related factors were compared in the two groups, enrolled before and after implementation of the new law. Participants in the two cohorts were similar in age (median 25 years), but YWHS-2 women reported fewer sex partners, more alcohol use and less ATS use. A higher proportion of YWHS-2 compared with YWHS-1 women worked in entertainment-based venues (68% vs 31%, respectively). HIV prevalence was significantly lower in the more recently sampled women: 9.2% (95% CI 4.5% to 13.8%) vs 23% (95% CI 16.5% to 29.7%). Sex work context and risk have shifted among young FSW in Phnom Penh, following implementation of anti-prostitution and anti-trafficking laws. While both cohorts were recruited using the same eligibility criteria, more recently sampled women had lower prevalence of sexual risk and HIV infection. Women engaging more directly in transactional sex have become harder to sample and access. Future prevention research and programmes need to consider how new policies and demographic changes in FSW impact HIV transmission.

Scale-Up, Retention and HIV/STI Prevalence Trends among Female Sex Workers Attending VICITS Clinics in Guatemala

PubMed Central

Morales-Miranda, Sonia; Jacobson, Jerry O.; Loya-Montiel, Itzel; Mendizabal-Burastero, Ricardo; Galindo-Arandi, César; Flores, Carlos; Chen, Sanny Y.

2014-01-01

Background Since 2007, Guatemala integrated STI clinical service with an HIV prevention model into four existing public health clinics to prevent HIV infection, known as the VICITS strategy. We present the first assessment of VICITS scale-up, retention, HIV and STI prevalence trends, and risk factors associated with HIV infection among Female Sex Workers (FSW) attending VICITS clinics in Guatemala. Methods Demographic, behavioral and clinical data were collected using a standardized form. Data was analyzed by year and health center. HIV and STI prevalence were estimated from routine visits. Retention was estimated as the percent of new users attending VICITS clinics who returned for at least one follow-up visit to any VICITS clinic within 12 months. Separate multivariate logistic regression models were conducted to investigate factors associated with HIV infection and program retention. Results During 2007–2011 5,682 FSW visited a VICITS clinic for the first-time. HIV prevalence varied from 0.4% to 5.8%, and chlamydia prevalence from 0% to 14.3%, across sites. Attending the Puerto Barrios clinic, having a current syphilis infection, working primarily on the street, and using the telephone or internet to contact clients were associated with HIV infection. The number of FSW accessing VICITS annually increased from 556 to 2,557 (361%) during the period. In 2011 retention varied across locations from 7.7% to 42.7%. Factors negatively impacting retention included current HIV diagnosis, having practiced sex work in another country, being born in Honduras, and attending Marco Antonio Foundation or Quetzaltenango clinic sites. Systematic time trends did not emerge, however 2008 and 2010 were characterized by reduced retention. Conclusions Our data show local differences in HIV prevalence and clinic attendance that can be used to prioritize prevention activities targeting FSW in Guatemala. VICITS achieved rapid scale-up; however, a better understanding of the causes of low return rates is urgently needed. PMID:25167141

Scale-up, retention and HIV/STI prevalence trends among female sex workers attending VICITS clinics in Guatemala.

PubMed

Morales-Miranda, Sonia; Jacobson, Jerry O; Loya-Montiel, Itzel; Mendizabal-Burastero, Ricardo; Galindo-Arandi, César; Flores, Carlos; Chen, Sanny Y

2014-01-01

Since 2007, Guatemala integrated STI clinical service with an HIV prevention model into four existing public health clinics to prevent HIV infection, known as the VICITS strategy. We present the first assessment of VICITS scale-up, retention, HIV and STI prevalence trends, and risk factors associated with HIV infection among Female Sex Workers (FSW) attending VICITS clinics in Guatemala. Demographic, behavioral and clinical data were collected using a standardized form. Data was analyzed by year and health center. HIV and STI prevalence were estimated from routine visits. Retention was estimated as the percent of new users attending VICITS clinics who returned for at least one follow-up visit to any VICITS clinic within 12 months. Separate multivariate logistic regression models were conducted to investigate factors associated with HIV infection and program retention. During 2007-2011 5,682 FSW visited a VICITS clinic for the first-time. HIV prevalence varied from 0.4% to 5.8%, and chlamydia prevalence from 0% to 14.3%, across sites. Attending the Puerto Barrios clinic, having a current syphilis infection, working primarily on the street, and using the telephone or internet to contact clients were associated with HIV infection. The number of FSW accessing VICITS annually increased from 556 to 2,557 (361%) during the period. In 2011 retention varied across locations from 7.7% to 42.7%. Factors negatively impacting retention included current HIV diagnosis, having practiced sex work in another country, being born in Honduras, and attending Marco Antonio Foundation or Quetzaltenango clinic sites. Systematic time trends did not emerge, however 2008 and 2010 were characterized by reduced retention. Our data show local differences in HIV prevalence and clinic attendance that can be used to prioritize prevention activities targeting FSW in Guatemala. VICITS achieved rapid scale-up; however, a better understanding of the causes of low return rates is urgently needed.

Extracorporeal shock wave therapy is effective in treating chronic plantar fasciitis

PubMed Central

Sun, Jiale; Gao, Fuqiang; Wang, Yanhua; Sun, Wei; Jiang, Baoguo; Li, Zirong

2017-01-01

Abstract Background: Plantar fasciitis (PF) is the most common reason for heel pain. The efficacy of extracorporeal shock wave therapy (ESWT) as an ideal alternative to conservative treatments and surgery is controversial, and almost all previous articles compared general ESWT with placebo without indicating the kind of shock wave. We undertook a meta-analysis to compare the efficacy of general ESWT, focused shock wave (FSW), and radial shock wave (RSW) with placebo, to assess their effectiveness in chronic PF. Methods: The PubMed, Medline, EmBase, Web of Science, and Cochrane library databases were searched for studies comparing FSW or RSW therapy with placebo in chronic PF. Clinical outcomes included the odds ratios (ORs) of pain relief, pain reduction, and complications. Relevant data were analyzed using RevMan v5.3. Results: Nine studies involving 935 patients were included. ESWT had higher improvement rates than the placebo group (OR 2.58, 95% confidence interval [CI] 1.97–3.39, P < .00001). ESWT had markedly lower standardized mean difference than placebo, with heterogeneity observed (standardized mean difference 1.01, 95% CI −0.01 to 2.03, P = .05, I2 = 96%, P < .00001). FSW and RSW therapies had greater therapeutic success in pain relief than the placebo group (OR 2.17, 95% CI 1.49–3.16, P < .0001; OR 4.63, 95% CI 1.30–16.46, P = .02), but significant heterogeneity was observed in RSW therapy versus placebo (I2 = 81%, P = .005). Conclusion: This meta-analysis suggested that FSW therapy can relieve pain in chronic PF as an ideal alternative option; meanwhile, no firm conclusions of general ESWT and RSW effectiveness can be drawn. Due to variations in the included studies, additional trials are needed to validate these conclusions. PMID:28403111

Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Reynolds, Anthony

2015-05-25

Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient atmore » the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.« less

Work Capability and physiological effects predictive studies. 4: In He-O2 excursions to pressures of 400- 800- 1200- and 1600 feet of sea water

NASA Technical Reports Server (NTRS)

Lambertsen, C. J. (Editor); Gelfand, R. (Editor); Clark, J. M. (Editor); Fletcher, M. E. (Editor)

1978-01-01

Experiments which exposed men in chambers, breathing helium with oxygen, to progressive increases of pressure equivalent to 400-800-1200-1600 feet of sea water (fsw) were conducted. Rates of compression and exposure to stable high pressure. Goals included: 1) determination of the specific character and time course of onset of physiological and performance decrements during the intentionally rapid compressions, and determination of rates of adaptation on reaching stable elevated pressure; 2) investigation of accelerated methods for decompression in deep saturation excursion diving; and 3) determination of competence in practical work performed in water at pressures equivalent to the extreme diving depths of 1200 and 1600 fsw.

Nondestructive Evaluation of the Friction Weld Process on 2195/2219 Grade Aluminum

NASA Technical Reports Server (NTRS)

Suits, Michael W.; Clark, Linda S.; Cox, Dwight E.

1999-01-01

In 1996, NASA's Marshall Space Flight Center began an ambitious program designed to find alternative methods of repairing conventional TIG (Tungsten Inert Gas) welds and VPPA (Variable Polarity Plasma Arc) welds on the Space Shuttle External Tank without producing additional heat-related anomalies or conditions. Therefore, a relatively new method, invented by The Welding Institute (TWI) in Cambridge, England, called Friction Stir Welding (FSW), was investigated for use in this application, as well as being used potentially as an initial weld process. As with the conventional repair welding processes, nondestructive evaluation (NDE) plays a crucial role in the verification of these repairs. Since it was feared that conventional NDE might have trouble with this type of weld structure (due to shape of nugget, grain structure, etc.) it was imperative that a complete study be performed to address the adequacy of the NDE process. This paper summarizes that process.

The Evolution of Friction Stir Welding Theory at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Nunes, Arthur C.

2012-01-01

From 1995 to the present the friction stir welding (FSW) process has been under study at Marshall Space Flight Center (MSFC). This is an account of the progressive emergence of a set of conceptual tools beginning with the discovery of the shear surface, wiping metal transfer, and the invention of a kinematic model and making possible a treatment of both metallurgical structure formation and process dynamics in friction stir welding from a unified point of view. It is generally observed that the bulk of the deformation of weld metal around the FSW pin takes place in a very narrow, almost discontinuous zone with high deformation rates characteristic of metal cutting. By 1999 it was realized that this zone could be treated as a shear surface like that in simple metal cutting models. At the shear surface the seam is drawn out and compressed and pressure and flow conditions determine whether or not a sound weld is produced. The discovery of the shear surface was followed by the synthesis of a simple 3- flow kinematic model of the FSW process. Relative to the tool the flow components are: (1) an approaching translational flow at weld speed V, (2) a rotating cylindrical plug flow with the angular velocity of the tool , and (3) a relatively slow ring vortex flow (like a smoke ring) encircling the tool and driven by shoulder scrolls and pin threads. The rotating plug flow picks up an element of weld metal, rotates it around with the tool, and deposits it behind the tool ( wiping metal transfer ); it forms plan section loops in tracers cut through by the tool. Radially inward flow from the ring vortex component retains metal longer in the rotating plug and outward flow expels metal earlier; this interaction forms the looping weld seam trace and the tongue and groove bimetallic weld contour. The radial components of the translational and ring vortex flows introduce parent metal intrusions into the small grained nugget material close to the tool shoulder; if this feature is pronounced, nugget collapse may result. Certain weld features, in particular internal banding seen in transverse section as onion rings and associated surface ridges called tool marks , have long implied an oscillation flow component, but have only recently been attributed in the literature to tool eccentricity. Rotating plug shape, typically a hollow cylinder flared at the end where it sticks to the shoulder, varies as pressure distribution on the tool determines where sticking occurs. Simplified power input estimates balanced against heat loss estimates give reasonable temperature estimates, explain why the power requirement changes hardly at all over a wide range of RPM s, and yield isotherms that seem to fall along boundaries of parameter windows of operation.

The Effect of Premixed Al-Cu Powder on the Stir Zone in Friction Stir Welding of AA3003-H18

NASA Astrophysics Data System (ADS)

Abnar, B.; Kazeminezhad, M.; Kokabi, A. H.

2015-02-01

In this research, 3-mm-thick AA3003-H18 non-heat-treatable aluminum alloy plates were joined by friction stir welding (FSW). It was performed by adding pure Cu and premixed Cu-Al powders at various rotational speeds of 800, 1000, and 1200 rpm and constant traveling speeds of 100 mm/min. At first, the powder was filled into the gap (0.2 or 0.4 mm) between two aluminum alloy plates, and then the FSW process was performed in two passes. The microstructure, mechanical properties, and formation of intermetallic compounds were investigated in both cases of using pure Cu and premixed Al-Cu powders. The results of using pure Cu and premixed Al-Cu powders were compared in the stir zone at various rotational speeds. The copper particle distribution and formation of Al-Cu intermetallic compounds (Al2Cu and AlCu) in the stir zone were desirable using premixed Al-Cu powder into the gap. The hardness values were significantly increased by formation of Al-Cu intermetallic compounds in the stir zone and it was uniform throughout the stir zone when premixed Al-Cu powder was used. Also, longitudinal tensile strength from the stir zone was higher when premixed Al-Cu powder was used instead of pure Cu powder.

Diving behavior and fishing performance: the case of lobster artisanal fishermen of the Yucatan coast, Mexico.

PubMed

Huchim-Lara, Oswaldo; Salas, Silvia; Chin, Walter; Montero, Jorge; Fraga, Julia

2015-01-01

An average of 209 cases of decompression sickness (DCS) have been reported every year among artisanal fishermen. divers of the Yucatan Peninsula, Mexico. DCS is a major problem among fishermen divers worldwide. This paper explores how diving behavior and fishing techniques among fishermen relate to the probability of experiencing DCS (Pdcs). Fieldwork was conducted in two communities during the 2012-2013 fishing season. Fishermen were classified into three groups (two per group) according to their fishing performance and followed during their journeys. Dive profiles were recorded using Sensus Ultra dive recorders (Reefet Inc.). Surveys were used to record fishing yields from cooperative and individual fishermen along with fishing techniques and dive behavior. 120 dives were recorded. Fishermen averaged three dives/day, with an average depth of 47 ± 2 feet of sea water (fsw) and an average total bottom time (TBT) of 95 ± 11 minutes. 24% of dives exceeded the 2008 U.S. Navy no-decompression limit. The average ascent rate was 20 fsw/minute, and 5% of those exceeded 40 fsw/minute. Inadequate decompression was observed in all fishermen. Fishermen are diving outside the safety limits of both military and recreational standards. Fishing techniques and dive behavior were important factors in Pdcs. Fishermen were reluctant to seek treatment, and symptoms were relieved with analgesics.

Correlates of Injection Drug Use among Female Sex Workers in Two Mexico-U.S. Border Cities

PubMed Central

Strathdee, Steffanie A.; Philbin, Morgan M.; Semple, Shirley J.; Pu, Minya; Orozovich, Prisci; Martinez, Gustavo; Lozada, Remedios; Fraga, Miguel; de la Torre, Adela; Staines, Hugo; Magis-Rodríguez, Carlos; Patterson, Thomas L.

2008-01-01

Objective: To characterize the overlap between injection drug use and sex work by women in Tijuana and Cd. Juarez, situated on the Mexico-U.S. border. Methods: FSWs aged ≥18 years who were not knowingly HIV-positive and reported having unprotected sex with ≥1 client in the prior two months underwent interviews and testing for HIV, syphilis gonorrhea and Chlamydia. Logistic regression identified factors associated with injecting drugs within the last month. Results: Of 924 FSWs, 18.0% had ever injected drugs. Among FSW-IDUs (N=114), prevalence of HIV, syphilis titers >1:8, gonorrhea and Chlamydia was significantly higher at 12.3%, 22.7%, 15.2% and 21.2% compared to 4.8%, 13.1%, 5.2% and 11.9% among other FSWs (N=810). FSW-IDUs also had more clients in the past six months (median: 300 vs. 240, p=0.02). Factors independently associated with injecting drugs in the past month included living in Tijuana, being younger, being married/common-law, longer duration in the sex trade, speaking English, earning less for sex without condoms, often using drugs before sex, and knowing other FSWs who injected drugs. Conclusions: FSW-IDUs had higher STI levels, engaged in riskier behaviors and were more vulnerable to having unsafe sex with clients compared to other FSWs, indicating that this subgroup is an important bridge population requiring focused prevention. PMID:17714888

Thermo-Mechanical Processing in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Schneider, Judy

2003-01-01

Friction stir welding is a solid-phase joining, or welding process that was invented in 1991 at The Welding Institute (TWI). The process is potentially capable of joining a wide variety of aluminum alloys that are traditionally difficult to fusion weld. The friction stir welding (FSW) process produces welds by moving a non-consumable rotating pin tool along a seam between work pieces that are firmly clamped to an anvil. At the start of the process, the rotating pin is plunged into the material to a pre-determined load. The required heat is produced by a combination of frictional and deformation heating. The shape of the tool shoulder and supporting anvil promotes a high hydrostatic pressure along the joint line as the tool shears and literally stirs the metal together. To produce a defect free weld, process variables (RPM, transverse speed, and downward force) and tool pin design must be chosen carefully. An accurate model of the material flow during the process is necessary to guide process variable selection. At MSFC a plastic slip line model of the process has been synthesized based on macroscopic images of the resulting weld material. Although this model appears to have captured the main features of the process, material specific interactions are not understood. The objective of the present research was to develop a basic understanding of the evolution of the microstructure to be able to relate it to the deformation process variables of strain, strain rate, and temperature.

Population-level impact of an accelerated HIV response plan to reach the UNAIDS 90-90-90 target in Côte d'Ivoire: Insights from mathematical modeling.

PubMed

Maheu-Giroux, Mathieu; Vesga, Juan F; Diabaté, Souleymane; Alary, Michel; Baral, Stefan; Diouf, Daouda; Abo, Kouamé; Boily, Marie-Claude

2017-06-01

National responses will need to be markedly accelerated to achieve the ambitious target of the Joint United Nations Programme on HIV/AIDS (UNAIDS). This target aims for 90% of HIV-positive individuals to be aware of their status, for 90% of those aware to receive antiretroviral therapy (ART), and for 90% of those on treatment to have a suppressed viral load by 2020, with each individual target reaching 95% by 2030. We aimed to estimate the impact of various treatment-as-prevention scenarios in Côte d'Ivoire, one of the countries with the highest HIV incidence in West Africa, with unmet HIV prevention and treatment needs, and where key populations are important to the broader HIV epidemic. An age-stratified dynamic model was developed and calibrated to epidemiological and programmatic data using a Bayesian framework. The model represents sexual and vertical HIV transmission in the general population, female sex workers (FSW), and men who have sex with men (MSM). We estimated the impact of scaling up interventions to reach the UNAIDS targets, as well as the impact of 8 other scenarios, on HIV transmission in adults and children, compared to our baseline scenario that maintains 2015 rates of testing, ART initiation, ART discontinuation, treatment failure, and levels of condom use. In 2015, we estimated that 52% (95% credible intervals: 46%-58%) of HIV-positive individuals were aware of their status, 72% (57%-82%) of those aware were on ART, and 77% (74%-79%) of those on ART were virologically suppressed. Reaching the UNAIDS targets on time would avert 50% (42%-60%) of new HIV infections over 2015-2030 compared to 30% (25%-36%) if the 90-90-90 target is reached in 2025. Attaining the UNAIDS targets in FSW, their clients, and MSM (but not in the rest of the population) would avert a similar fraction of new infections (30%; 21%-39%). A 25-percentage-point drop in condom use from the 2015 levels among FSW and MSM would reduce the impact of reaching the UNAIDS targets, with 38% (26%-51%) of infections averted. The study's main limitation is that homogenous spatial coverage of interventions was assumed, and future lines of inquiry should examine how geographical prioritization could affect HIV transmission. Maximizing the impact of the UNAIDS targets will require rapid scale-up of interventions, particularly testing, ART initiation, and limiting ART discontinuation. Reaching clients of FSW, as well as key populations, can efficiently reduce transmission. Sustaining the high condom-use levels among key populations should remain an important prevention pillar.

Population-level impact of an accelerated HIV response plan to reach the UNAIDS 90-90-90 target in Côte d’Ivoire: Insights from mathematical modeling

PubMed Central

Diabaté, Souleymane; Alary, Michel; Diouf, Daouda; Abo, Kouamé; Boily, Marie-Claude

2017-01-01

Background National responses will need to be markedly accelerated to achieve the ambitious target of the Joint United Nations Programme on HIV/AIDS (UNAIDS). This target aims for 90% of HIV-positive individuals to be aware of their status, for 90% of those aware to receive antiretroviral therapy (ART), and for 90% of those on treatment to have a suppressed viral load by 2020, with each individual target reaching 95% by 2030. We aimed to estimate the impact of various treatment-as-prevention scenarios in Côte d’Ivoire, one of the countries with the highest HIV incidence in West Africa, with unmet HIV prevention and treatment needs, and where key populations are important to the broader HIV epidemic. Methods and findings An age-stratified dynamic model was developed and calibrated to epidemiological and programmatic data using a Bayesian framework. The model represents sexual and vertical HIV transmission in the general population, female sex workers (FSW), and men who have sex with men (MSM). We estimated the impact of scaling up interventions to reach the UNAIDS targets, as well as the impact of 8 other scenarios, on HIV transmission in adults and children, compared to our baseline scenario that maintains 2015 rates of testing, ART initiation, ART discontinuation, treatment failure, and levels of condom use. In 2015, we estimated that 52% (95% credible intervals: 46%–58%) of HIV-positive individuals were aware of their status, 72% (57%–82%) of those aware were on ART, and 77% (74%–79%) of those on ART were virologically suppressed. Reaching the UNAIDS targets on time would avert 50% (42%–60%) of new HIV infections over 2015–2030 compared to 30% (25%–36%) if the 90-90-90 target is reached in 2025. Attaining the UNAIDS targets in FSW, their clients, and MSM (but not in the rest of the population) would avert a similar fraction of new infections (30%; 21%–39%). A 25-percentage-point drop in condom use from the 2015 levels among FSW and MSM would reduce the impact of reaching the UNAIDS targets, with 38% (26%–51%) of infections averted. The study’s main limitation is that homogenous spatial coverage of interventions was assumed, and future lines of inquiry should examine how geographical prioritization could affect HIV transmission. Conclusions Maximizing the impact of the UNAIDS targets will require rapid scale-up of interventions, particularly testing, ART initiation, and limiting ART discontinuation. Reaching clients of FSW, as well as key populations, can efficiently reduce transmission. Sustaining the high condom-use levels among key populations should remain an important prevention pillar. PMID:28617810

Deformation and Plateau Region of Functionally Graded Aluminum Foam by Amount Combinations of Added Blowing Agent.

PubMed

Hangai, Yoshihiko; Utsunomiya, Takao; Kuwazuru, Osamu; Kitahara, Soichiro; Yoshikawa, Nobuhiro

2015-10-21

Recently, to further improve the performance of aluminum foam, functionally graded (FG) aluminum foams, whose pore structure varies with their position, have been developed. In this study, three types of FG aluminum foam of aluminum alloy die casting ADC12 with combinations of two different amounts of added blowing agent titanium(II) hydride (TiH₂) powder were fabricated by a friction stir welding (FSW) route precursor foaming method. The combinations of 1.0-0 mass %, 0.4-0 mass %, and 0.2-0 mass % TiH₂ were selected as the amounts of TiH₂ relative to the mass of the volume stirred by FSW. The static compression tests of the fabricated FG aluminum foams were carried out. The deformation and fracture of FG aluminum foams fundamentally started in the high-porosity (with TiH₂ addition) layer and shifted to the low-porosity (without TiH₂ addition) layer. The first and second plateau regions in the relationship between compressive stress and strain independently appeared with the occurrence of deformations and fractures in the high- and low-porosity layers. It was shown that FG aluminum foams, whose plateau region varies in steps by the combination of amounts of added TiH₂ ( i.e. , the combination of pore structures), can be fabricated.

Detection and assessment of flaws in friction stir welded joints using ultrasonic guided waves: experimental and finite element analysis

NASA Astrophysics Data System (ADS)

Fakih, Mohammad Ali; Mustapha, Samir; Tarraf, Jaafar; Ayoub, Georges; Hamade, Ramsey

2018-02-01

Ultrasonic guided waves (GWs), e.g. Lamb waves, have been proven effective in the detection of defects such as corrosion, cracking, delamination, and debonding in both composite and metallic structures. They are a significant tool employed in structural health monitoring. In this study, the ability of ultrasonic GWs to assess the quality of friction stir welding (FSW) was investigated. Four friction stir welded AZ31B magnesium plates processed with different welding parameters and a non-welded plate were used. The fundamental symmetric (S0) Lamb wave mode was excited using piezoelectric wafers (PZTs). Further, the S0 mode was separated using the "Improved complete ensemble empirical mode decomposition with adaptive noise (Improved CEEMDAN)" technique. A damage index (DI) was defined based on the variation in the amplitude of the captured wave signals in order to detect the presence and asses the severity of damage resulting from the welding process. As well, computed tomography (CT) scanning was used as a non-destructive testing (NDT) technique to assess the actual weld quality and validate predictions based on the GW approach. The findings were further confirmed using finite element analysis (FEA). To model the actual damage profile in the welds, "Mimics" software was used for the 3D reconstruction of the CT scans. The built 3D models were later used for evaluation of damage volume and for FEA. The damage volumes were correlated to the damage indices computed from both experimental and numerical data. The proposed approach showed high sensitivity of the S0 mode to internal flaws within the friction stir welded joints. This methodology has great potential as a future classification method of FSW quality.

Microstructural variation through weld thickness and mechanical properties of peened friction stir welded 6061 aluminum alloy joints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulstaar, Mustafa A., E-mail: mustafa.abdulstaar

The current study examined the effect of microstructure variation on the development of mechanical properties in friction stir welded joints of 6061-T6 aluminum alloy, which were subsequently processed by shot peening (SP). Following to FSW, fatigue specimens were extracted perpendicularly to the welding direction. Surface Skimming to 0.5 mm from crown and root sides of the joint was made and SP was later applied on the two sides using ceramic shots of two different Almen intensities of 0.18 mmA and 0.24 mmA. Microstructural examination by electron back scattered diffraction (EBSD) indicated variation in the grain refinement of the weld zone,more » with coarsest grains (5 μm) at the crown side and finest grains (2 μm) at the root side. Reduction of microhardness to 60 HV occurred in the weld zone for samples in FSW condition. Application of SP promoted significant strain hardening at the crown side, with Almen intensities of 0.24 mmA providing maximum increase in microhardness to 120 HV. On the contrary, only a maximum microhardness of 75 HV was obtained at the root side. The difference in strain hardening capability at the two sides was strongly dependent on grain size. The two Almen intensities produced similar distribution of compressive residual stresses in the subsurface regions that led to enhance the fatigue strength to the level of base metal for N ≥ 10{sup 5} cycles. Yet, the increase in fatigue strength was more pronounced with increasing Almen intensity to 0.24 mmA, demonstrating further enhancement by strain hardening. - Highlights: • Grain refinement was observed after friction stir welding of AA 6061-T6. • Reduction in microhardness and fatigue strength were obtained after welding. • Variation in grain refinement led to different hardening behavior after peening. • Shot peening induced beneficial compressive residual stresses. • Shot peening and surface skimming markedly improved the fatigue performance.« less

Advances in Solid State Joining of Haynes 230 High Temperature Alloy

NASA Technical Reports Server (NTRS)

Ding, R. Jeffrey; Schneider, Judy; Walker, Bryant

2010-01-01

The J-2X engine is being designed for NASA s new class of crew and launch vehicles, the Ares I and Ares V. The J-2X is a LOX/Hydrogen upper stage engine with 294,000 lbs of thrust and a minimum Isp of 448 seconds. As part of the design criteria to meet the performance requirements a large film-cooled nozzle extension is being designed to further expand the hot gases and increases the specific impulse. The nozzle extension is designed using Haynes 230, a nickel-chromium-tungsten-molybdenum superalloy. The alloy was selected for its high strength at elevated temperatures and resistance to hydrogen embrittlement. The nozzle extension is manufactured from Haynes 230 plate spun-forged to form the contour and chemically-milled pockets for weight reduction. Currently fusion welding is being evaluated for joining the panels which are then mechanically etched and thinned to required dimensions for the nozzle extension blank. This blank is then spun formed into the parabolic geometry required for the nozzle. After forming the nozzle extension, weight reduction pockets are chemically milled into the nozzle. Fusion welding of Haynes results in columnar grains which are prone to hot cracking during forming processes. This restricts the ability to use spin forging to produce the nozzle contour. Solid state joining processes are being pursued as an alternative process to produce a structure more amenable to spin forming. Solid state processes have been shown to produce a refined grain structure within the joint regions as illustrated in Figure 1. Solid state joining processes include friction stir welding (FSW) and a patented modification termed thermal stir welding (TSW). The configuration of TSWing utilizes an induction coil to preheat the material minimizing the burden on the weld tool extending its life. This provides the ability to precisely select and control the temperature. The work presented in this presentation investigates the feasibility of joining the Haynes 230 alloy using the solid state welding processes of FSW and TSW. Process descriptions and attributes of each weld process will be presented. Weld process set-up and welding techniques will be discussed leading to the challenges experienced in joining the superalloy. Mechanical property data will also be presented.

Effect of Friction Stir Process Parameters on the Mechanical and Thermal Behavior of 5754-H111 Aluminum Plates.

PubMed

Serio, Livia Maria; Palumbo, Davide; De Filippis, Luigi Alberto Ciro; Galietti, Umberto; Ludovico, Antonio Domenico

2016-02-23

A study of the Friction Stir Welding (FSW) process was carried out in order to evaluate the influence of process parameters on the mechanical properties of aluminum plates (AA5754-H111). The process was monitored during each test by means of infrared cameras in order to correlate temperature information with eventual changes of the mechanical properties of joints. In particular, two process parameters were considered for tests: the welding tool rotation speed and the welding tool traverse speed. The quality of joints was evaluated by means of destructive and non-destructive tests. In this regard, the presence of defects and the ultimate tensile strength (UTS) were investigated for each combination of the process parameters. A statistical analysis was carried out to assess the correlation between the thermal behavior of joints and the process parameters, also proving the capability of Infrared Thermography for on-line monitoring of the quality of joints.

Effect of Friction Stir Process Parameters on the Mechanical and Thermal Behavior of 5754-H111 Aluminum Plates

PubMed Central

Serio, Livia Maria; Palumbo, Davide; De Filippis, Luigi Alberto Ciro; Galietti, Umberto; Ludovico, Antonio Domenico

2016-01-01

A study of the Friction Stir Welding (FSW) process was carried out in order to evaluate the influence of process parameters on the mechanical properties of aluminum plates (AA5754-H111). The process was monitored during each test by means of infrared cameras in order to correlate temperature information with eventual changes of the mechanical properties of joints. In particular, two process parameters were considered for tests: the welding tool rotation speed and the welding tool traverse speed. The quality of joints was evaluated by means of destructive and non-destructive tests. In this regard, the presence of defects and the ultimate tensile strength (UTS) were investigated for each combination of the process parameters. A statistical analysis was carried out to assess the correlation between the thermal behavior of joints and the process parameters, also proving the capability of Infrared Thermography for on-line monitoring of the quality of joints. PMID:28773246

Surface enhancement of cold work tool steels by friction stir processing with a pinless tool

NASA Astrophysics Data System (ADS)

Costa, M. I.; Verdera, D.; Vieira, M. T.; Rodrigues, D. M.

2014-03-01

The microstructure and mechanical properties of enhanced tool steel (AISI D2) surfaces produced using a friction stir welding (FSW) related procedure, called friction stir processing (FSP), are analysed in this work. The surface of the tool steel samples was processed using a WC-Co pinless tool and varying processing conditions. Microstructural analysis revealed that meanwhile the original substrate structure consisted of a heterogeneous distribution of coarse carbides in a ferritic matrix, the transformed surfaces consisted of very small carbides, homogenously distributed in a ferrite- bainite- martensite matrix. The morphology of the surfaces, as well as its mechanical properties, evaluated by hardness and tensile testing, were found to vary with increasing tool rotation speed. Surface hardness was drastically increased, relative to the initial hardness of bulk steel. This was attributed to ferrite and carbide refinement, as well as to martensite formation during solid state processing. At the highest rotation rates, tool sliding during processing deeply compromised the characteristics of the processed surfaces.

Client-perpetrated and husband-perpetrated violence among female sex workers in Andhra Pradesh, India: HIV/STI risk across personal and work contexts.

PubMed

Reed, Elizabeth; Erausquin, J T; Groves, Allison K; Salazar, Marissa; Biradavolu, Monica; Blankenship, Kim M

2016-09-01

This study examines violence experienced in work and personal contexts and relation to HIV risk factors in these contexts among female sex workers (FSW) in Andhra Pradesh, India. FSW at least 18 years of age (n=2335) were recruited through three rounds of respondent-driven sampling between 2006 and 2010 for a survey on HIV risk. Using crude and adjusted logistic regression models, any sexual/physical violence (last 6 months) perpetrated by clients and husbands were separately assessed in association with accepting more money for sex without a condom (last 30 days), consistent condom use with clients and husbands (last 30 days), and sexually transmitted infection (STI) symptoms (last 6 months). The mean age among participants was 32, 22% reported being currently married, and 22% and 21% reported physical/sexual violence by clients and husbands, respectively. In adjusted logistic regression models, FSW who experienced client violence were more likely to report accepting more money for unprotected sex trades (adjusted OR (AOR)=1.7; 95% CI 1.4 to 2.2), less likely to report consistent condom use with clients (AOR=0.6; 95% CI 0.5 to 0.7) and more likely to report STI symptoms (AOR=3.5; 95% CI 2.6 to 4.6). Women who reported husband violence were more likely to report accepting more money for unprotected sex trades (AOR=2.1; 95% CI 1.2 to 3.7), less likely to report consistent condom use with clients (AOR=0.5; 95% CI 0.3 to 0.8) and more likely to report STI symptoms (AOR=2.6; 95% CI 1.6 to 4.1). Among FSW, experiences of violence in work and personal contexts are associated with sexual HIV risk behaviours with clients as well as STI symptoms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Estimation of the sexual transmission of HIV in Kenya and Uganda on the trans-Africa highway: the continuing role for prevention in high risk groups.

PubMed

Morris, C N; Ferguson, A G

2006-10-01

To explore the effect of transactional sex on the trans-Africa highway from Mombasa-Kampala in contributing to the HIV epidemic and the impact that an effective prevention intervention could have. Variables for input into a simple model of HIV prevention, AVERT, were derived from a study of hot spots of transactional sex on the trans-Africa highway. Diaries were completed by a sample of sex workers at selected sites of transactional sex for a period of 28 consecutive days. Key information elicited included numbers, types and occupations of clients, numbers of liaisons, sexual acts in each liaison, and condom use. 857 diaries were distributed and 578 received and usable in 30 sites. A sexual patterning matrix was completed by 202 truckers at the Malaba border point as part of a health seeking behaviour survey. Two methods were employed to estimate female sex worker (FSW) numbers on the highway. FSW focus group discussions (FGDs) at 15 sites were carried out and included questioning on the number of sex workers at the site. As most transactional sex on the highway is centred on bars and lodgings, a patron census and survey of 1007 bars and lodgings was carried out which included questions on the presence and proportions of FSWs among the clientele. There are an estimated 8000 FSWs on the trans-Africa highway from Mombasa to Kampala. Annual numbers of different sexual partners per FSW were 129, annual numbers of sexual acts per FSW were 634, percentage of sexual acts protected by condom use was 77.7%. Using these input data an estimated 3200-4148 new HIV infections occur on this portion of the trans-Africa highway in 1 year. Having a 90% condom use programme in place could prevent almost two thirds of these infections and cumulative incidence would decline from 1.29% to 0.42%. In generalised epidemics there has been a debate as to the place of targeted interventions. In the current east African epidemic we show that a targeted intervention could have significant impact in averting HIV infections related to the trans-Africa highway.

Predictors of Injection Cessation and Relapse among Female Sex Workers who Inject Drugs in Two Mexican-US Border Cities.

PubMed

West, Brooke S; Abramovitz, Daniela; Staines, Hugo; Vera, Alicia; Patterson, Thomas L; Strathdee, Steffanie A

2016-02-01

We know little about predictors of injection drug cessation and relapse among female sex workers who inject drugs (FSW-PWID) at the US-Mexico border. Among HIV-negative FSW-PWID taking part in a behavioral intervention study in Tijuana and Ciudad Juárez, Cox regression was used to identify predictors of time to first cessation of injection, which was defined as reporting not having injected drugs for a period of 4 months or longer, and among that subset, we examined predictors of time to injection relapse. Among 440 women, 84 (19%) reported ceasing injection during follow-up (median time to cessation = 9.3 months); of these, 30 (35%) reported relapse to injection (median time to relapse = 3.5 months). The rate of injection cessation was lower for women reporting trading sex prior to age 18 (adj. hazard ratio (HR) = 0.64, 95% confidence interval (CI) = 0.41-1.01), ever being sexually abused (adj. HR = 0.44, 95% CI = 0.27-0.71), and a higher number of vaginal sex acts with casual clients (adj. HR = 0.99 per transaction, 95% CI = 0.98-1.00). The rate of cessation was higher for women who spent more hours on the streets on a typical day (adj. HR = 1.04/h, 95% CI = 1.01-1.08) and who lived in Tijuana vs. Ciudad Juárez (adj. HR = 2.15, 95% CI = 1.14-4.07). The rate of relapse was higher among women reporting regular drug use with clients (adj. HR = 2.17, 95% CI = 0.96-4.89) and those scoring higher on a risk injection index (adj. HR = 2.04, 95% CI = 1.15-3.61). The rate of relapse was lower for FSW-PWID with higher than average incomes (adj. HR = 0.40, 95% CI = 0.18-0.89). These findings have important implications for the scale-up of methadone maintenance treatment programs (MMTPs) in Mexico and indicate a need for gender-specific programs that address sexual abuse experiences and economic vulnerabilities faced by FSW-PWID.

Sex work and HIV in Cambodia: trajectories of risk and disease in two cohorts of high-risk young women in Phnom Penh, Cambodia

PubMed Central

Page, Kimberly; Stein, Ellen; Sansothy, Neth; Evans, Jennifer; Couture, Marie-Claude; Sichan, Keo; Cockroft, Melissa; Mooney-Somers, Julie; Phlong, Pisith; Kaldor, John; Maher, Lisa

2013-01-01

Objectives HIV prevalence among Cambodian female sex workers (FSW) is among the highest in Southeast Asia. We describe HIV prevalence and associated risk exposures in FSW sampled serially in Phnom Penh, Cambodia (Young Women's Health Study (YWHS)), before and after the implementation of a new law designed to combat human trafficking and sexual exploitation. Design Cross-sectional analysis of baseline data from two prospective cohorts. Setting Community-based study in Phnom Penh, Cambodia. Participants Women aged 15–29 years, reporting ≥2 sexual partners in the last month and/or engaged in transactional sex in the last 3 months, were enrolled in the studies in 2007 (N=161; YWHS-1), and 2009 (N=220; YWHS-2) following information sessions where 285 and 345 women attended. Primary outcomes HIV prevalence, sexual risk behaviour, amphetamine-type stimulant (ATS) and alcohol use, and work-related factors were compared in the two groups, enrolled before and after implementation of the new law. Results Participants in the two cohorts were similar in age (median 25 years), but YWHS-2 women reported fewer sex partners, more alcohol use and less ATS use. A higher proportion of YWHS-2 compared with YWHS-1 women worked in entertainment-based venues (68% vs 31%, respectively). HIV prevalence was significantly lower in the more recently sampled women: 9.2% (95% CI 4.5% to 13.8%) vs 23% (95% CI 16.5% to 29.7%). Conclusions Sex work context and risk have shifted among young FSW in Phnom Penh, following implementation of anti-prostitution and anti-trafficking laws. While both cohorts were recruited using the same eligibility criteria, more recently sampled women had lower prevalence of sexual risk and HIV infection. Women engaging more directly in transactional sex have become harder to sample and access. Future prevention research and programmes need to consider how new policies and demographic changes in FSW impact HIV transmission. PMID:24022389

Automated Test for NASA CFS

NASA Technical Reports Server (NTRS)

McComas, David C.; Strege, Susanne L.; Carpenter, Paul B. Hartman, Randy

2015-01-01

The core Flight System (cFS) is a flight software (FSW) product line developed by the Flight Software Systems Branch (FSSB) at NASA's Goddard Space Flight Center (GSFC). The cFS uses compile-time configuration parameters to implement variable requirements to enable portability across embedded computing platforms and to implement different end-user functional needs. The verification and validation of these requirements is proving to be a significant challenge. This paper describes the challenges facing the cFS and the results of a pilot effort to apply EXB Solution's testing approach to the cFS applications.

Advanced Welding Concepts

NASA Technical Reports Server (NTRS)

Ding, Robert J.

2010-01-01

Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

Microstructure evolution in dissimilar AA6060/copper friction stir welded joints

NASA Astrophysics Data System (ADS)

Kalashnikova, T. A.; Shvedov, M. A.; Vasilyev, P. A.

2017-12-01

Friction stir welding process has been applied for making a dissimilar copper/aluminum alloy joint. The grain microstructure and mechanical properties of the obtained joint were studied. The structure of the cross-section of the FSW compound was analyzed. The microstructural evolution of the joint was examined using optical microscopy. The mechanical properties of the intermetallic particles were evaluated by measuring the microhardness according to the Vickers method. The microhardness of the intermetallic particles was by a factor of 4 lower than that of the particles obtained by fusion welding. The results of the investigations enable using friction stir welding for making dissimilar joints.

Spacecraft Onboard Interface Services: Current Status and Roadmap

NASA Astrophysics Data System (ADS)

Prochazka, Marek; Lopez Trescastro, Jorge; Krueger, Sabine

2016-08-01

Spacecraft Onboard Interface Services (SOIS) is a set of CCSDS standards defining communication stack services to interact with hardware equipment onboard spacecraft. In 2014 ESA kicked off three parallel activities to critically review the SOIS standards, use legacy spacecraft flight software (FSW), make it compliant to a preselected subset of SOIS standards and make performance and architecture assessment. As a part of the three parallel activities, led by Airbus DS Toulouse, OHB Bremen and Thales Alenia Space Cannes respectively, it was to provide feedback back to ESA and CCSDS and also to propose a roadmap of transition towards an operational FSW system fully compliant to applicable SOIS standards. The objective of the paper is twofold: Firstly it is to summarise main results of the three parallel activities and secondly, based on the results, to propose a roadmap for the future.

Sex and drug risk behavior pre- and post-emigration among Latino migrant men in post-Hurricane Katrina New Orleans.

PubMed

Mills, Jennifer; Burton, Nicole; Schmidt, Norine; Salinas, Oscar; Hembling, John; Aran, Alberto; Shedlin, Michele; Kissinger, Patricia

2013-06-01

High rates of sex and drug risk behaviors have been documented among Latino migrant men in the US. Whether these behaviors were established in the migrants' home countries or were adopted in the US has not been described and has implications for prevention strategies. Quarterly surveys were conducted to gather information on selected sex and drug risk practices of Latino migrant men who arrived in New Orleans after Hurricane Katrina seeking work. Both kappa scores and McNemar's tests were performed to determine if practice of these behaviors in home country was similar to practice post-emigration to the US. Female sex worker (FSW) patronage, same sex encounters (MSM), and crack cocaine use was more likely to occur post- rather than pre-emigration. Of those who ever engaged in these selected behaviors, most adopted the behavior in the US (i.e., 75.8% of FSW patrons, 72.7% of MSM participants, and 85.7% of crack cocaine users), with the exception of binge drinking (26.8%). Men who were living with a family member were less likely to adopt FSW patronage OR = 0.27, CI = 0.10-0.76, whereas men who earned >$465 per week were more likely to adopt crack cocaine use OR = 6.29 CI = 1.29, 30.57. Interventions that facilitate the maintenance of family cohesion and provide strategies for financial management may be useful for reducing sex and drug risk among newly arrived migrants.

Effect of Local Post Weld Heat Treatment on Tensile Properties in Friction Stir Welded 2219-O Al Alloy

NASA Astrophysics Data System (ADS)

Chu, Guannan; Sun, Lei; Lin, Caiyuan; Lin, Yanli

2017-11-01

To improve the formability of the aluminum alloy welds and overcome the size limitation of the bulk post weld heat treatment (BPWHT) on large size friction stir welded joints, a local post weld heat treatment method (LPWHT) was proposed. In this method, the resistance heating as the moving heat source is adopted to only heat the weld seam. The temperature field of LPWHT and its influence on the mechanical properties and formability of FSW 2219-O Al alloy joints was investigated. The evaluation of the tensile properties of FSW samples was also examined by mapping the global and local strain distribution using the digital image correlation methodology. The results indicated that the formability was improved greatly after LPWHT, while the hardness distribution of the FSW joint was homogenized. The maximum elongation can reach 1.4 times that of as-welded joints with increase the strength and the strain of the nugget zone increased from 3 to 8% when annealing at 300 °C. The heterogeneity on the tensile deformation of the as-welded joints was improved by the nugget zone showing large local strain value and the reason was given according to the dimple fracture characteristics at different annealing temperatures. The tensile strength and elongation of LPWHT can reach 93.3 and 96.1% of the BPWHT, respectively. Thus, the LPWHT can be advantageous compared to the BPWHT for large size welds.

Correlates of unprotected sex with female sex workers among male clients in Tijuana, Mexico.

PubMed

Goldenberg, Shira M; Gallardo Cruz, Manuel; Strathdee, Steffanie A; Nguyen, Lucie; Semple, Shirley J; Patterson, Thomas L

2010-05-01

Tijuana, situated adjacent to San Diego, CA on the US-Mexico border, is experiencing an emerging HIV epidemic, with prevalence among female sex workers (FSWs) having risen in recent years from <1% to 6%. Comparable data on FSWs' clients are lacking. We explored correlates of unprotected sex with FSWs among male clients in Tijuana. In 2008, males from San Diego (N = 189) and Tijuana (N = 211) aged 18 or older who had paid or traded for sex with a FSW in Tijuana during the past 4 months were recruited in Tijuana's red light district. Participants underwent psychosocial interviews, and were tested for HIV, syphilis (Treponema pallidum), gonorrhea (Neisseria gonorrhoeae), and Chlamydia (Chlamydia trachomatis). Of 394 men, median age was 36 years, 42.1% were married, and 39.3% were unemployed. Ethnic composition was 13.2% white, 79.4% Hispanic, and 7.4% black or other. Half (50.3%) reported unprotected vaginal or anal sex with FSWs in Tijuana in the past 4 months. High proportions reported using drugs during sex (66%), and 36% reported frequenting the same FSW. Factors independently associated with unprotected sex with FSWs were using drugs during sex, visiting the same FSW, being married, and being unemployed. FSWs' clients represent a sexually transmitted infections/HIV transmission "bridge" through unprotected sex with FSWs, wives, and other partners. Tailored interventions to promote consistent condom use are needed for clients, especially within the context of drug use and ongoing relations with particular FSWs.

Modelisation numerique des phenomenes physiques du soudage par friction-malaxage et comportement en fatigue de joints soudes en aluminium 7075-T6

NASA Astrophysics Data System (ADS)

Gemme, Frederic

The aim of the present research project is to increase the amount of fundamental knowledge regarding the process by getting a better understanding of the physical phenomena involved in friction stir welding (FSW). Such knowledge is required to improve the process in the context of industrial applications. In order to do so, the first part of the project is dedicated to a theoretical study of the process, while the microstructure and the mechanical properties of welded joints obtained in different welding conditions are measured and analyzed in the second part. The combination of the tool rotating and translating movements induces plastic deformation and heat generation of the welded material. The material thermomechanical history is responsible for metallurgical phenomena occurring during FSW such as recrystallization and precipitate dissolution and coarsening. Process modelling is used to reproduce this thermomechanical history in order to predict the influence of welding on the material microstructure. It is helpful to study heat generation and heat conduction mechanisms and to understand how joint properties are related to them. In the current work, a finite element numerical model based on solid mechanics has been developed to compute the thermomechanical history of the welded material. The computation results were compared to reference experimental data in order to validate the model and to calibrate unknown physical parameters. The model was used to study the effect of the friction coefficient on the thermomechanical history. Results showed that contact conditions at the workpiece/tool interface have a strong effect on relative amounts of heat generated by friction and by plastic deformation. The comparison with the experimental torque applied by the tool for different rotational speeds has shown that the friction coefficient decreases when the rotational speed increases. Consequently, heat generation is far more important near the material/tool interface and the material deformation is shallower, increasing the lack of penetration probability. The variation of thermomechanical conditions with regards to the rotational speed is responsible for the variation of the nugget shape, as recrystallization conditions are not reached in the same volume of material. The second part of the research project was dedicated to a characterization of the welded joints microstructure and mechanical properties. Sound joints were obtained by using a manufacturing procedure involving process parameters optimization and quality control of the joint integrity. Five different combinations of rotational and advancing speeds were studied. Microstructure observations have shown that the rotational speed has an effect on recrystallization conditions because of the variation of the contact conditions at the material/tool interface. On the other hand, the advancing speed has a strong effect on the precipitation state in the heat affected zone (HAZ). The heat input increases when the advancing speed decreases. The material softening in the HAZ is then more pronounced. Mechanical testing of the welded joints showed that the fatigue resistance increases when the rotational speed increases and the advancing speed decreases. The fatigue resistance of FSW joints mainly depends on the ratio of the advancing speed on the rotational speed, called the welding pitch k. When the welding pitch is high (k ≥ 0,66 mm/rev), the fatigue resistance depends on crack initiation at the root of circular grooves left by the tool on the weld surface. The size of these grooves is directly related to the welding pitch. When the welding pitch is low (k ≤ 0,2 mm/rev), the heat input is high and the fatigue resistance is limited by the HAZ softening. The fatigue resistance is optimized when k stands in the 0,25-0,30 mm/rev range. Outside that range, the presence of small lateral lips is critical. The results of the characterization part of the project showed that the effects of the applied vertical force on the formation of lateral lips should be submitted to further investigations. The elimination of the lateral lip, which could be achieved with a more precise adjustment of the vertical force, could lead to an improved fatigue resistance. The elimination of lateral lips, but also the circular grooves left by the tool, may be obtained by developing an appropriate surfacing technique and could lead to an improved fatigue resistance without reducing the advancing speed. (Abstract shortened by UMI.)

The Plunge Phase of Friction Stir Welding

NASA Technical Reports Server (NTRS)

McClure, John C.

2005-01-01

The many advantages of Friction Stir Welding have led to a relatively rapid acceptance in the often conservative welding community. Because the process is so different from traditional fusion welding, with which most investigators are most familiar, there remain many aspects of FSW for which there is no clear consensus. For example, the well known onion rings seen in transverse sections have been variously interpreted as grain size variations, variation in density of second phase particles and parts of the carousel of material rotating with the pin that have been shed from the carousel. Using Orientation Imaging Microscopy, Schneider has recently noted that the onion rings have a different orientation (and hence etch differently) than the surrounding material, and this orientation is consistent with slip plane orientations at the edge of the carousel. Likewise, the forces and torque exerted by the FSW tool on the work piece largely remain unaccounted for. Although these forces are routinely measured by investigators with commercial instrumented welders, they are rarely reported or even qualitatively analyzed. This paper will introduce a model based on a carousel or disk of material that rotates with the tool to estimate the torque and plunge force required to plunge a tool into the work piece. A stationary tool is modeled rather than the moving tool because effects such as thermal transients and metallurgical changes in the sample (primarily aging in aluminum) can be more easily accounted for. It is believed, however, that with some modifications the model should be applicable to a moving tool also.

Effects of various tool pin profiles on mechanical and metallurgical properties of friction stir welded joints of cryorolled AA2219 aluminium alloy

NASA Astrophysics Data System (ADS)

Kamal Babu, Karupannan; Panneerselvam, Kavan; Sathiya, Paulraj; Noorul Haq, Abdul Haq; Sundarrajan, Srinivasan; Mastanaiah, Potta; Srinivasa Murthy, Chunduri Venkata

2018-02-01

Friction stir welding (FSW) process was conducted on cryorolled (CR) AA2219 plate using different tool pin profiles such as cylindrical pin, threaded cylindrical pin, square pin and hexagonal pin profiles. The FSW was carried out with pairs of 6 mm thick CR aluminium plates with different tool pin profiles. The different tool pin profile weld portions' behaviors like mechanical (tensile strength, impact and hardness) and metallurgical characteristics were analyzed. The results of the mechanical analysis revealed that the joint made by the hexagonal pin tool had good strength compared to other pin profiles. This was due to the pulsating action and material flow of the tool resulting in dynamic recrystallization in the weld zone. This was confirmed by the ultra fine grain structure formation in Weld Nugget (WN) of hexagonal pin tool joint with a higher percentage of precipitate dissolution. The fractograph of the hexagonal tool pin weld portion confirmed the finer dimple structure morphology without having any interior defect compared to other tool pin profiles. The lowest weld joint strength was obtained from cylindrical pin profile weld joint due to insufficient material flow during welding. The Transmission Electron Microscope and EDX analysis showed the dissolution of the metastable θ″, θ' (Al2Cu) partial precipitates in the WN and proved the influence of metastable precipitates on enhancement of mechanical behavior of weld. The XRD results also confirmed the Al2Cu precipitation dissolution in the weld zone.

Lateral position detection and control for friction stir systems

DOEpatents

Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

2010-12-14

A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

A pedigree-based proxy measure of genetic predisposition of drinking and alcohol use among female sex workers in China: a cross-sectional study.

PubMed

Zhang, Chen; Li, Xiaoming; Liu, Yu; Qiao, Shan; Su, Shaobing; Zhang, Liying; Zhou, Yuejiao

2017-02-01

Scientific evidence has suggested that genetic factors accounted for more than half of the vulnerability of developing alcohol use problems. However, collecting genetic data poses a significant challenge for most population-based behavioral studies. The aim of this study was to assess the utilities of a pedigree-based proxy measure of genetic predisposition of drinking (GPD) and its effect on alcohol use behaviors as well as its interactions with personal and environmental factors. In the current study, cross-sectional data were collected from 700 female sex workers (FSW) in Guangxi, China. Participants provided information on a pedigree-based proxy measure of GPD and their alcohol use behaviors. Chi-square and independent t-test was applied for examining the bivariate associations between GPD and alcohol use behaviors; multivariate and ordinal regression models were used to examine the effect of GPD on alcohol use. This study found that women with a higher composite score of GPD tended to have a higher risk of alcohol use problem compared to their counterparts (p < .05). GPD was a significant predictor of alcohol use problems (p < .05), especially among women who had mental health issues or lack of health cares. The pedigree-based measure provided a useful proxy of GPD among participants. Both FSW's mental health and health care access interact with GPD and affect their drinking patterns. By understanding the genetic basis of alcohol use, we can develop scalable and efficacious interventions that will take into consideration the individual risk profile and environmental influences.

A Vehicle Management End-to-End Testing and Analysis Platform for Validation of Mission and Fault Management Algorithms to Reduce Risk for NASA's Space Launch System

NASA Technical Reports Server (NTRS)

Trevino, Luis; Johnson, Stephen B.; Patterson, Jonathan; Teare, David

2015-01-01

The development of the Space Launch System (SLS) launch vehicle requires cross discipline teams with extensive knowledge of launch vehicle subsystems, information theory, and autonomous algorithms dealing with all operations from pre-launch through on orbit operations. The characteristics of these systems must be matched with the autonomous algorithm monitoring and mitigation capabilities for accurate control and response to abnormal conditions throughout all vehicle mission flight phases, including precipitating safing actions and crew aborts. This presents a large complex systems engineering challenge being addressed in part by focusing on the specific subsystems handling of off-nominal mission and fault tolerance. Using traditional model based system and software engineering design principles from the Unified Modeling Language (UML), the Mission and Fault Management (M&FM) algorithms are crafted and vetted in specialized Integrated Development Teams composed of multiple development disciplines. NASA also has formed an M&FM team for addressing fault management early in the development lifecycle. This team has developed a dedicated Vehicle Management End-to-End Testbed (VMET) that integrates specific M&FM algorithms, specialized nominal and off-nominal test cases, and vendor-supplied physics-based launch vehicle subsystem models. The flexibility of VMET enables thorough testing of the M&FM algorithms by providing configurable suites of both nominal and off-nominal test cases to validate the algorithms utilizing actual subsystem models. The intent is to validate the algorithms and substantiate them with performance baselines for each of the vehicle subsystems in an independent platform exterior to flight software test processes. In any software development process there is inherent risk in the interpretation and implementation of concepts into software through requirements and test processes. Risk reduction is addressed by working with other organizations such as S&MA, Structures and Environments, GNC, Orion, the Crew Office, Flight Operations, and Ground Operations by assessing performance of the M&FM algorithms in terms of their ability to reduce Loss of Mission and Loss of Crew probabilities. In addition, through state machine and diagnostic modeling, analysis efforts investigate a broader suite of failure effects and detection and responses that can be tested in VMET and confirm that responses do not create additional risks or cause undesired states through interactive dynamic effects with other algorithms and systems. VMET further contributes to risk reduction by prototyping and exercising the M&FM algorithms early in their implementation and without any inherent hindrances such as meeting FSW processor scheduling constraints due to their target platform - ARINC 653 partitioned OS, resource limitations, and other factors related to integration with other subsystems not directly involved with M&FM. The plan for VMET encompasses testing the original M&FM algorithms coded in the same C++ language and state machine architectural concepts as that used by Flight Software. This enables the development of performance standards and test cases to characterize the M&FM algorithms and sets a benchmark from which to measure the effectiveness of M&FM algorithms performance in the FSW development and test processes. This paper is outlined in a systematic fashion analogous to a lifecycle process flow for engineering development of algorithms into software and testing. Section I describes the NASA SLS M&FM context, presenting the current infrastructure, leading principles, methods, and participants. Section II defines the testing philosophy of the M&FM algorithms as related to VMET followed by section III, which presents the modeling methods of the algorithms to be tested and validated in VMET. Its details are then further presented in section IV followed by Section V presenting integration, test status, and state analysis. Finally, section VI addresses the summary and forward directions followed by the appendices presenting relevant information on terminology and documentation.

HIV, HSV2 and Syphilis Prevalence in Female Sex Workers in Kerman, South-East Iran; Using Respondent-Driven Sampling

PubMed Central

Navadeh, S; Mirzazadeh, A; Mousavi, L; Haghdoost, AA; Fahimfar, N; Sedaghat, A

2012-01-01

Background We estimated the prevalence of HIV, sexually transmitted infections (STIs), and risky behaviors among female sex workers (FSW) in Kerman City, Iran. Methods: Women, 18 years or older, who reported selling sex for at least 6 months during their lifetime and had at least one sexual contact with a client in the recent 12 months were sampled using Responding Driven Sampling (RDS). Participants were interviewed about their sexual behaviors and provided whole blood for HIV, syphilis, and Herpes simplex type 2 (HSV2) testing. Data were analyzed using RDSAT Version 6.0 software. Results: Among samples of 177 FSW, we did not find any HIV positive cases. The weighted prevalence of syphilis and HSV2 were 7.2% and 18.0%, respectively. The reported STI syndromes for the proceeding year of the survey were 36%. Unprotected sexual contact was about 17–22% and link to injecting drug users through injection was about 18%. Conclusion: While this survey found no HIV, there were findings of risky sexual behaviors and STI, markers for potential infection for HIV. The prevalence of STI and sexual risk behaviors for HIV is considerably high in this subpopulation that alarming for an urgent public health preventive measures and national control-plan to be developed and implemented. PMID:23641392

Risk behaviours and prevalences of HIV and sexually transmitted infections among female sex workers in various venues in Changzhou, China.

PubMed

Guo, Yanli; Xu, Xiaoguo; Fu, Gengfeng; Huan, Xiping; Jiang, Ning; Yin, Yueping; Chen, Xiangsheng

2017-10-01

Female sex workers (FSWs) play an important role in the heterosexual transmission of HIV and sexually transmitted infections (STIs) in China. We conducted a cross-sectional study of 609 FSWs from various venues in Changzhou to investigate risk behaviours and prevalences of HIV and STIs among FSW subgroups. Structured questionnaires were used in face-to-face interviews to collect information. Blood and cervical specimens were collected to test for HIV, syphilis, Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) infections. The overall prevalences of syphilis, NG and CT were 5.6, 2.3 and 17.0%, respectively. The highest prevalence of syphilis (13.8%, P < 0.001) was observed among FSWs in low-class (LC) venues. No case of HIV infection was found. Less than half of all FSWs (40.7%) reported consistent condom use with clients during the last month. A multivariate analysis revealed a 13-fold increased risk for FSWs with NG infection to be infected with syphilis and a four-fold increased risk for FSWs aged 30-39 years to have a CT infection relative to FSWs aged 15-20 years. The prevalences of STIs were high, and risky sexual behaviours were common, especially among FSWs in LC venues. More tailored and comprehensive prevention programmes should be developed for specific FSW subgroups.

Deformation and Plateau Region of Functionally Graded Aluminum Foam by Amount Combinations of Added Blowing Agent

PubMed Central

Hangai, Yoshihiko; Utsunomiya, Takao; Kuwazuru, Osamu; Kitahara, Soichiro; Yoshikawa, Nobuhiro

2015-01-01

Recently, to further improve the performance of aluminum foam, functionally graded (FG) aluminum foams, whose pore structure varies with their position, have been developed. In this study, three types of FG aluminum foam of aluminum alloy die casting ADC12 with combinations of two different amounts of added blowing agent titanium(II) hydride (TiH2) powder were fabricated by a friction stir welding (FSW) route precursor foaming method. The combinations of 1.0–0 mass %, 0.4–0 mass %, and 0.2–0 mass % TiH2 were selected as the amounts of TiH2 relative to the mass of the volume stirred by FSW. The static compression tests of the fabricated FG aluminum foams were carried out. The deformation and fracture of FG aluminum foams fundamentally started in the high-porosity (with TiH2 addition) layer and shifted to the low-porosity (without TiH2 addition) layer. The first and second plateau regions in the relationship between compressive stress and strain independently appeared with the occurrence of deformations and fractures in the high- and low-porosity layers. It was shown that FG aluminum foams, whose plateau region varies in steps by the combination of amounts of added TiH2 (i.e., the combination of pore structures), can be fabricated. PMID:28793626

Comprehensive optimization of friction stir weld parameters of lap joint AA1100 plates using artificial neural networks and modified NSGA-II

NASA Astrophysics Data System (ADS)

Khalkhali, Abolfazl; Ebrahimi-Nejad, Salman; Geran Malek, Nima

2018-06-01

Friction stir welding (FSW) process overcomes many difficulties arising in conventional fusion welding processes of aluminum alloys. The current paper presents a comprehensive investigation on the effects of rotational speed, traverse speed, tool tilt angle and tool pin profile on the longitudinal force, axial force, maximum temperature, tensile strength, percent elongation, grain size, micro-hardness of welded zone and welded zone thickness of AA1100 aluminum alloy sheets. Design of experiments (DOE) was applied using the Taguchi approach and subsequently, effects of the input parameter on process outputs were investigated using analysis of variance (ANOVA). A perceptron neural network model was developed to find a correlation between the inputs and outputs. Multi-objective optimization using modified NSGA-II was implemented followed by NIP and TOPSIS approaches to propose optimum points for each of the square, pentagon, hexagon, and circular pin profiles. Results indicate that the optimization process can reach horizontal and vertical forces as low as 1452 N and 2913 N, respectively and a grain size as low as 2 μm. This results in hardness values of up to 57.2 and tensile strength, elongation and joint thickness of 2126 N, 5.9% and 3.7 mm, respectively. The maximum operating temperature can also reach a sufficiently high value of 374 °C to provide adequate material flow.

FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.

2015-02-16

Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribemore » welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.« less

Friction Stir Welding of Magnesium Alloy Type AZ 31

NASA Astrophysics Data System (ADS)

Kupec, Tomáš; Behúlová, Mária; Turňa, Milan; Sahul, Miroslav

The paper deals with welding of Mg alloy of the type AZ 31 by Friction Stir Welding technology (FSW). The FSW technology is at present predominantly used for welding light metals and alloys, as aluminium, magnesium and their alloys. Experimental part consists of performing the simulation and fabrication of welded joints on a new-installed welding equipment available at the Welding Research Institute — Industrial Institute of SR Bratislava. Welding tools made of tool steel type H 13 were used for welding experiments. Geometry of welding tools was designed on the base of literature knowledge. Suitable welding parameters and conditions were determined using numerical simulation. Main emphasis was laid upon the tool revolutions, welding speed and tool bevel angle. The effect of welding parameters on the quality of welded joints was assessed. Assessment of welded joints was carried out by radiography, light microscopy, hardness measurement and EDX microanalysis. Static tensile test was employed for mechanical testing.

Evaluation of Surface Residual Stresses in Friction Stir Welds Due to Laser and Shot Peening

NASA Technical Reports Server (NTRS)

Hatamleh, Omar; Rivero, Iris V.; Lyons, Jed

2007-01-01

The effects of laser, and shot peening on the residual stresses in Friction Stir Welds (FSW) has been investigated. The surface residual stresses were measured at five different locations across the weld in order to produce an adequate residual stress profile. The residual stresses before and after sectioning the coupon from the welded plate were also measured, and the effect of coupon size on the residual stress relaxation was determined and characterized. Measurements indicate that residual stresses were not uniform along the welded plate, and large variation in stress magnitude could be exhibited at various locations along the FSW plate. Sectioning resulted in significant residual stress relaxation in the longitudinal direction attributed to the large change in dimensions in this direction. Overall, Laser and shot peening resulted in a significant reduction in tensile residual stresses at the surface of the specimens.

HIV Testing and Counseling Among Female Sex Workers: A Systematic Literature Review.

PubMed

Tokar, Anna; Broerse, Jacqueline E W; Blanchard, James; Roura, Maria

2018-02-20

HIV testing uptake continues to be low among Female Sex Workers (FSWs). We synthesizes evidence on barriers and facilitators to HIV testing among FSW as well as frequencies of testing, willingness to test, and return rates to collect results. We systematically searched the MEDLINE/PubMed, EMBASE, SCOPUS databases for articles published in English between January 2000 and November 2017. Out of 5036 references screened, we retained 36 papers. The two barriers to HIV testing most commonly reported were financial and time costs-including low income, transportation costs, time constraints, and formal/informal payments-as well as the stigma and discrimination ascribed to HIV positive people and sex workers. Social support facilitated testing with consistently higher uptake amongst married FSWs and women who were encouraged to test by peers and managers. The consistent finding that social support facilitated HIV testing calls for its inclusion into current HIV testing strategies addressed at FSW.

Syphilis infection among female sex workers in Colombia.

PubMed

Mejia, Alfredo; Bautista, Christian T; Leal, Luis; Ayala, Claudia; Prieto, Franklyn; de la Hoz, Fernando; Alzate, Martha L; Acosta, Jacqueline; Sanchez, Jose L

2009-04-01

To study the epidemiology of Treponema pallidum (syphilis) among female sex workers (FSW) in Santa Fe de Bogotá, Colombia. A cross-sectional study was conducted. Participants were interviewed using a standardized questionnaire, which collected socio-demographic characteristics and risk behavior information. Blood samples were screened for syphilis using the VDRL test and the MHATP assay. The prevalence of syphilis was 10.3% (53/514). Adjusted risk factors significantly associated with syphilis were: age (linear increase), education (primary or no education), monthly income (or=4 years), number of clients per week (>or=22), main workplace (street), inconsistent (never) condom use in sex work, previous STI history, and use of illegal drugs. Effective health education programs for improving the level of knowledge of STI and the promotion of consistent condom use activities along with other appropriate harm reduction activities are urgently required among FSW in Colombia.

Condoms used but sex not well protected.

PubMed

Lau, J T F; Zhou, H; Su, X Y; Feng, T J; Hong, F C; Tsui, H Y; Ma, Y L; Wang, Z; Walden, D

2014-10-01

Condom use is often equated to safer sex. The prevalence of condom use during sex work among female sex workers (FSW) in China is high. Condom use, however, co-exists with condom failure and improper use and hence risk of HIV transmission. In a cross-sectional study, we interviewed 195 FSW in Shenzhen, China. The prevalence of condom use in the last episode of sex work was 97.4 %, However, respectively 53.8 and 86.2 % had experienced at least one condition of condom failure that may lead to genital contact (wearing condoms after penetration, condom breakage/slippage, condoms removed by clients) and at least one condition of improper condom use (not removing air from the tip of the condom, not pulling it down to the root of penis and not choosing good quality condoms). Factors of individual level (e.g. never choosing high quality condoms for sex work), inter-personal level (e.g. agreement to have unprotected sex if fond of clients or paid more) and environmental/structural level (e.g. non-availability of condoms) were associated with various types of condom failure and improper use. Although HIV prevention interventions have increased prevalence of condom use among FSW, the risk of HIV transmission may still be high as "unsafe" sex due to condom failure and improper use is prevalent. Interventions promoting safer sex need to address such issues and take socio-ecological factors into account. Condom use during sex work is not equivalent to well protected sex as the protective effects could be compromised by frequent condom failure and improper use.

Testing for amphetamine-type stimulant (ATS) use to ascertain validity of self-reported ATS use among young female sex workers in Cambodia.

PubMed

Kab, Vannda; Evans, Jennifer; Sansothy, Neth; Stein, Ellen; Claude-Couture, Marie; Maher, Lisa; Page, Kimberly

2012-06-28

To assess concordance between self-reported amphetamine-type stimulant (ATS) use and toxicology results among young female sex workers (FSW) in Phnom Penh, Cambodia. Cross-sectional data from the Young Women's Health Study-2 (YWHS-2), a prospective study of HIV and ATS use among young (15 to 29 years) FSW in Phnom Penh, Cambodia, was analyzed. The YWHS-2 assessed sociodemographic characteristics, HIV serology, HIV risk, and ATS use by self-report and urine toxicology testing at each quarterly visit, the second of which provided data for this assessment. Outcomes include sensitivity, specificity, positive- and negative predictive values (overall and stratified by age), sex-work setting, and HIV status. Among 200 women, prevalence of positive toxicology screening for ATS use was 14% (95% confidence interval [CI], 9.2, 18.9%) and concurrent prevalence of self-reported ATS was 15.5% (95% CI, 10.4, 20.6%). The sensitivity and specificity of self-reported ATS use compared to positive toxicology test results was 89.3% (25/28), and 96.5% (166/172), respectively. The positive predictive value of self-reported ATS use was 80.6% (25/31); the negative predictive value was 98.2% (166/169). Some differences in concordance between self-report and urine toxicology results were noted in analyses stratified by age group and sex-work setting but not by HIV status. Results indicate a high prevalence of ATS use among FSW in Phnom Penh, Cambodia, and high concordance between self-reported and toxicology-test confirmed ATS use.

Sex and drug risk behavior pre- and post-emigration among Latino migrant men in post-Hurricane Katrina New Orleans

PubMed Central

Mills, Jennifer; Burton, Nicole; Schmidt, Norine; Salinas, Oscar; Hembling, John; Aran, Alberto; Shedlin, Michele; Kissinger, Patricia

2012-01-01

High rates of sex and drug risk behaviors have been documented among Latino migrant men in the U.S. Whether these behaviors were established in the migrants’ home countries or were adopted in the U.S. has not been described and has implications for prevention strategies. Quarterly surveys were conducted to gather information on selected sex and drug risk practices of Latino migrant men who arrived in New Orleans after Hurricane Katrina seeking work. Both kappa scores and McNemar’s tests were performed to determine if practice of these behaviors in home country was similar to practice post-emigration to the U.S. Female sex worker (FSW) patronage, same sex encounters (MSM), and crack cocaine use was more likely to occur post-rather than pre-emigration. Of those who ever engaged in these selected behaviors, most adopted the behavior in the U.S. (i.e. 75.8% of FSW patrons, 72.7% of MSM participants, and 85.7% of crack cocaine users), with the exception of binge drinking (26.8%). Men who were living with a family member were less likely to adopt FSW patronage OR=0.27, CI=0.10-0.76, whereas men who earned >$465 per week were more likely to adopt crack cocaine use OR=6.29 CI=1.29, 30.57. Interventions that facilitate the maintenance of family cohesion and provide strategies for financial management may be useful for reducing sex and drug risk among newly arrived migrants. PMID:22669638

Correlates of HIV, STIs and Associated High Risk Behaviors among Male Clients of Female Sex Workers in Tijuana, Mexico

PubMed Central

Patterson, Thomas L.; Goldenberg, Shira; Gallardo, Manuel; Lozada, Remedios; Semple, Shirley J.; Orozovich, Prisci; Abramovitz, Daniela; Strathdee, Steffanie A.

2009-01-01

Objectives To determine sociodemographic and behavioral correlates of HIV infection among male clients of FSWs in Tijuana. Methods 400 men aged 18 or older who had paid or traded for sex with a FSW in Tijuana during the past 4 months were recruited in Tijuana’s “zone of tolerance,” where prostitution is practiced openly under a municipal permit system. Efforts were made to balance the sample between residents of the U.S. (San Diego County) and of Mexico (Tijuana). Participants underwent interviews and testing for HIV, syphilis, gonorrhea, and Chlamydia. Logistic regression identified correlates of HIV infection. Results Mean age was 36.6. One quarter had injected drugs within the previous 4 months. Lifetime use of heroin, cocaine and methamphetamine was 36%, 50% and 64%, respectively. Men had frequented FSWs for an average of 11 years, visiting FSWs an average of 26 times last year. In the past four months, one half reported having unprotected sex with an FSW; 46% reported frequently being high when having sex with an FSW. Prevalence of HIV, syphilis, gonorrhea, and Chlamydia was 4%, 2%, 2.5% and 7.5%; 14.2% were positive for at least one infection. Factors independently associated with HIV infection were living in Mexico, ever using methamphetamine, living alone, and testing positive for syphilis. Conclusions Male clients of FSWs in Tijuana had a high sex and drug risk profile. While STI prevalence was lower than among FSWs, HIV prevalence was comparable, suggesting the need for interventions among clients to prevent spread of HIV and STIs. PMID:19584699

Estimation of the sexual transmission of HIV in Kenya and Uganda on the trans‐Africa highway: the continuing role for prevention in high risk groups

PubMed Central

Morris, C N; Ferguson, A G

2006-01-01

Objective To explore the effect of transactional sex on the trans‐Africa highway from Mombasa‐Kampala in contributing to the HIV epidemic and the impact that an effective prevention intervention could have. Methods Variables for input into a simple model of HIV prevention, AVERT, were derived from a study of hot spots of transactional sex on the trans‐Africa highway. Diaries were completed by a sample of sex workers at selected sites of transactional sex for a period of 28 consecutive days. Key information elicited included numbers, types and occupations of clients, numbers of liaisons, sexual acts in each liaison, and condom use. 857 diaries were distributed and 578 received and usable in 30 sites. A sexual patterning matrix was completed by 202 truckers at the Malaba border point as part of a health seeking behaviour survey. Two methods were employed to estimate female sex worker (FSW) numbers on the highway. FSW focus group discussions (FGDs) at 15 sites were carried out and included questioning on the number of sex workers at the site. As most transactional sex on the highway is centred on bars and lodgings, a patron census and survey of 1007 bars and lodgings was carried out which included questions on the presence and proportions of FSWs among the clientele. Results There are an estimated 8000 FSWs on the trans‐Africa highway from Mombasa to Kampala. Annual numbers of different sexual partners per FSW were 129, annual numbers of sexual acts per FSW were 634, percentage of sexual acts protected by condom use was 77.7%. Using these input data an estimated 3200–4148 new HIV infections occur on this portion of the trans‐Africa highway in 1 year. Having a 90% condom use programme in place could prevent almost two thirds of these infections and cumulative incidence would decline from 1.29% to 0.42%. Conclusions In generalised epidemics there has been a debate as to the place of targeted interventions. In the current east African epidemic we show that a targeted intervention could have significant impact in averting HIV infections related to the trans‐Africa highway. PMID:16854995

Mujer Mas Segura (Safer Women): a combination prevention intervention to reduce sexual and injection risks among female sex workers who inject drugs.

PubMed

Vera, Alicia; Abramovitz, Daniela; Lozada, Remedios; Martinez, Gustavo; Rangel, M Gudelia; Staines, Hugo; Patterson, Thomas L; Strathdee, Steffanie A

2012-08-14

Female sex workers who inject drugs (FSW-IDUs) are at risk of acquiring HIV, sexually transmitted infections (STI) and blood-borne infections through unprotected sex and sharing injection equipment. We conducted a 2×2 factorial randomized controlled trial to evaluate combination interventions to simultaneously reduce sexual and injection risks among FSW-IDUs in Tijuana and Ciudad Juarez, Mexico. FSW-IDUs ≥18 years reporting sharing injection equipment and unprotected sex with clients within the last month were randomized to one of four conditions based on an a priori randomization schedule, blinding interviewer/counselors to assignment. Due to the extreme vulnerability of this population, we did not include a control group that would deny some women access to preventive information. All women received similar information regardless of group allocation; the difference was in the way the information was delivered and the extent to which women had an interactive role. Each condition was a single 60-minute session, including either an interactive or didactic version of an injection risk intervention and sexual risk intervention. Women underwent interviewer-administered surveys and testing for HIV, syphilis, gonorrhea, Chlamydia, and Trichomonas at baseline and quarterly for 12 months. Combined HIV/STI incidence will be the primary outcome. Secondary outcomes are proportionate reductions in sharing of injection equipment and unprotected sex with clients. Of 1,132 women, 548 (48.4%) were excluded (88.9% were ineligible; 11.1% refused to participate or did not return); 584 eligible women enrolled (284 in Tijuana; 300 in Ciudad Juarez). All 584 participants completed the baseline interview, provided biological samples and were randomized to one of the four groups. During follow-up, 17 participants (2.9%) were lost to follow-up, of whom 10 (58.8%) had died, leaving 567 participants for analysis. This study appears to be the first intervention to attempt to simultaneously reduce injection and sexual risk behaviors among FSW-IDUs. The factorial design will permit analysis to determine whether the combination of the two interactive interventions and/or its respective components are effective in reducing injection and/or sexual risks, which will have direct, tangible policy implications for Mexico and potentially other resource-poor countries. NCT00840658.

Mujer Mas Segura (Safer Women): a combination prevention intervention to reduce sexual and injection risks among female sex workers who inject drugs

PubMed Central

2012-01-01

Background Female sex workers who inject drugs (FSW-IDUs) are at risk of acquiring HIV, sexually transmitted infections (STI) and blood-borne infections through unprotected sex and sharing injection equipment. We conducted a 2×2 factorial randomized controlled trial to evaluate combination interventions to simultaneously reduce sexual and injection risks among FSW-IDUs in Tijuana and Ciudad Juarez, Mexico. Methods/design FSW-IDUs ≥18 years reporting sharing injection equipment and unprotected sex with clients within the last month were randomized to one of four conditions based on an a priori randomization schedule, blinding interviewer/counselors to assignment. Due to the extreme vulnerability of this population, we did not include a control group that would deny some women access to preventive information. All women received similar information regardless of group allocation; the difference was in the way the information was delivered and the extent to which women had an interactive role. Each condition was a single 60-minute session, including either an interactive or didactic version of an injection risk intervention and sexual risk intervention. Women underwent interviewer-administered surveys and testing for HIV, syphilis, gonorrhea, Chlamydia, and Trichomonas at baseline and quarterly for 12 months. Combined HIV/STI incidence will be the primary outcome. Secondary outcomes are proportionate reductions in sharing of injection equipment and unprotected sex with clients. Discussion Of 1,132 women, 548 (48.4%) were excluded (88.9% were ineligible; 11.1% refused to participate or did not return); 584 eligible women enrolled (284 in Tijuana; 300 in Ciudad Juarez). All 584 participants completed the baseline interview, provided biological samples and were randomized to one of the four groups. During follow-up, 17 participants (2.9%) were lost to follow-up, of whom 10 (58.8%) had died, leaving 567 participants for analysis. This study appears to be the first intervention to attempt to simultaneously reduce injection and sexual risk behaviors among FSW-IDUs. The factorial design will permit analysis to determine whether the combination of the two interactive interventions and/or its respective components are effective in reducing injection and/or sexual risks, which will have direct, tangible policy implications for Mexico and potentially other resource-poor countries. Trial registration NCT00840658 PMID:22891807

Sustainability of Welding Process through Bobbin Friction Stir Welding

NASA Astrophysics Data System (ADS)

Sued, M. K.; Samsuri, S. S. M.; Kassim, M. K. A. M.; Nasir, S. N. N. M.

2018-03-01

Welding process is in high demand, which required a competitive technology to be adopted. This is important for sustaining the needs of the joining industries without ignoring the impact of the process to the environment. Friction stir welding (FSW) is stated to be benefitting the environment through low energy consumption, which cannot be achieved through traditional arc welding. However, this is not well documented, especially for bobbin friction stir welding (BFSW). Therefore, an investigation is conducted by measuring current consumption of the machine during the BFSW process. From the measurement, different phases of BFSW welding process and its electrical demand are presented. It is found that in general total energy in BFSW is about 130kW inclusive of all identified process phases. The phase that utilise for joint formation is in weld phase that used the highest total energy of 120kWs. The recorded total energy is still far below the traditional welding technology and the conventional friction stir welding (CFSW) energy demand. This indicates that BFSW technology with its vast benefit able to sustain the joining technology in near future.

Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling

PubMed Central

Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

2017-01-01

Background In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. Objective The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. Methods MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. Results RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball samples. In addition, RDS samples indicated lower exposure to HIV prevention information, less knowledge about HIV prevention, limited access to HIV prevention tools such as condoms, and less-reported frequency of sexually transmitted infections (STI) and HIV testing as compared with the venue-based samples. Findings pertaining to the level of disclosure of sexual practices and sexual practice–related stigma were mixed. Conclusions Samples generated by RDS and venue-based snowball sampling produced significantly different prevalence estimates of several important characteristics. These findings are tempered by limitations to the application of both approaches in practice. Ultimately, these findings provide further context for understanding existing surveillance data and how differences in methods of sampling can influence both the type of individuals captured and whether or not these individuals are representative of the larger target population. These data highlight the need to consider how program coverage estimates of marginalized populations are determined when characterizing the level of unmet need. PMID:29054832

Wake Cycle Robustness of the Mars Science Laboratory Flight Software

NASA Technical Reports Server (NTRS)

Whitehill, Robert

2011-01-01

The Mars Science Laboratory (MSL) is a spacecraft being developed by the Jet Propulsion Laboratory (JPL) for the purpose of in-situ exploration on the surface of Mars. The objective of MSL is to explore and quantitatively assess a local region on the Martian surface as a habitat for microbial life, past or present. This objective will be accomplished through the assessment of the biological potential of at least one target environment, the characterization of the geology and geochemistry of the landing region, an investigation of the planetary process relevant to past habitability, and a characterization of surface radiation. For this purpose, MSL incorporates a total of ten scientific instruments for which functions are to include, among others, atmospheric and descent imaging, chemical composition analysis, and radiation measurement. The Flight Software (FSW) system is responsible for all mission phases, including launch, cruise, entry-descent-landing, and surface operation of the rover. Because of the essential nature of flight software to project success, each of the software modules is undergoing extensive testing to identify and correct errors.

Declines in risk behaviour and sexually transmitted infection prevalence following a community-led HIV preventive intervention among female sex workers in Mysore, India.

PubMed

Reza-Paul, Sushena; Beattie, Tara; Syed, Hafeez Ur Rahman; Venukumar, Koppal T; Venugopal, Mysore S; Fathima, Mary P; Raghavendra, H R; Akram, Pasha; Manjula, Ramaiah; Lakshmi, M; Isac, Shajy; Ramesh, Banadakoppa M; Washington, Reynold; Mahagaonkar, Sangameshwar B; Glynn, Judith R; Blanchard, James F; Moses, Stephen

2008-12-01

To investigate the impact on sexual behaviour and sexually transmitted infections (STI) of a comprehensive community-led intervention programme for reducing sexual risk among female sex workers (FSW) in Mysore, India. The key programme components were: community mobilization and peer-mediated outreach; increasing access to and utilization of sexual health services; and enhancing the enabling environment to support programme activities. Two cross-sectional surveys among random samples of FSW were conducted 30 months apart, in 2004 and 2006. Of over 1000 women who sell sex in Mysore city, 429 participated in the survey at baseline and 425 at follow-up. The median age was 30 years, median duration in sex work 4 years, and the majority were street based (88%). Striking increases in condom use were seen between baseline and follow-up surveys: condom use at last sex with occasional clients was 65% versus 90%, P < 0001; with repeat clients 53% versus 66%, P < 0.001; and with regular partners 7% versus 30%, P < 0.001. STI prevalence declined from baseline to follow-up: syphilis 25% versus 12%, P < 0.001; trichomonas infection 33% versus 14%, P < 0.001; chlamydial infection 11% versus 5%, P = 0.001; gonorrhoea 5% versus 2%, P = 0.03. HIV prevalence remained stable (26% versus 24%), and detuned assay testing suggested a decline in recent HIV infections. This comprehensive HIV preventive intervention empowering FSW has resulted in striking increases in reported condom use and a concomitant reduction in the prevalence of curable STI. This model should be replicated in similar urban settings across India.

High Drop-off Along the HIV Care Continuum and ART Interruption Among Female Sex Workers in the Dominican Republic.

PubMed

Zulliger, Rose; Barrington, Clare; Donastorg, Yeycy; Perez, Martha; Kerrigan, Deanna

2015-06-01

Engagement in HIV care offers clear individual and societal benefits, but little evidence exists on the care experiences of key populations. A cross-sectional survey was conducted with 268 female sex workers (FSWs) living with HIV in Santo Domingo, Dominican Republic, to describe the HIV care continuum and to determine factors associated with antiretroviral therapy (ART) interruption. FSWs disengaged throughout the care continuum with the highest drop-off after ART initiation. Most participants were linked to care (92%), retained in care (85%), and initiated onto ART (78%), but ART discontinuation and irregular adherence were frequent. Only 48% of participants had an undetectable HIV viral load. Overall, 36% of participants ever initiated onto ART reported lifetime experience with ART interruption. The odds of ART interruption were 3.24 times higher among women who experienced FSW-related discrimination [95% confidence interval (CI): 1.28 to 8.20], 2.41 times higher among women who used any drug (95% CI: 1.09 to 5.34), and 2.35 times higher among women who worked in an FSW establishment (95% CI: 1.20 to 4.60). Internalized stigma related to FSW was associated with higher odds of interruption (adjusted odds ratio: 1.09; 95% CI: 1.02 to 1.16), and positive perceptions of HIV providers were protective (adjusted odds ratio: 0.91; 95% CI: 0.85 to 0.98). FSWs living with HIV confront multiple barriers throughout the HIV care continuum, many of which are related to the social context and stigmatization of sex work. Given the clear importance of maximizing the potential benefits of engagement in HIV care, there is an urgent need for interventions to support FSWs throughout the HIV care continuum.

Prevalence and Correlates of ‘Agua Celeste’ Use among Female Sex Workers who Inject Drugs in Ciudad Juarez, Mexico

PubMed Central

Morris, Meghan D.; Case, Patricia; Robertson, Angela M.; Lozada, Remedios; Vera, Alicia; Clapp, John D.; Medina-Mora, Maria Elena; Strathdee, Steffanie A.

2011-01-01

Background Agua celeste, or “heavenly water,” is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of Agua Celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Methods Between 2008 and 2010, baseline data from FSW-IDUs ≥ 18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Results Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14–23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8 hours per day, and younger age. Discussion We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. PMID:21441001

Prevalence and correlates of 'agua celeste' use among female sex workers who inject drugs in Ciudad Juarez, Mexico.

PubMed

Morris, Meghan D; Case, Patricia; Robertson, Angela M; Lozada, Remedios; Vera, Alicia; Clapp, John D; Medina-Mora, Maria Elena; Strathdee, Steffanie A

2011-09-01

Agua celeste, or "heavenly water", is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of agua celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico. Between 2008 and 2010, baseline data from FSW-IDUs≥18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression. Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14-23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8h per day, and younger age. We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Behavioral and psychosocial correlates of anal sex among male clients of female sex workers in Tijuana, Mexico.

PubMed

Semple, Shirley J; Strathdee, Steffanie A; Pitpitan, Eileen V; Chavarin, Claudia; Patterson, Thomas L

2015-05-01

Most studies of heterosexual sex risk practices have focused on condomless vaginal sex despite evidence that condomless anal sex has a significantly higher risk of HIV transmission. The present study focused on male clients' anal sex practices with female sex workers (FSWs) in Tijuana, Mexico, where an HIV epidemic is growing among high-risk groups. Logistic regression analyses were used to identify psychosocial and behavioral correlates of anal sex among male clients. Our sample of HIV-negative men (N = 400) was predominantly Latino (87.5 %), born in Mexico (78.8 %), never married (36.8 %) or in a regular or common-law marriage (31.5 %), and employed (62.8 %), with an average age and education of 37.8 and 9.2 years, respectively. Eighty-nine percent identified as heterosexual and 11 % as bisexual. By design, 50 % of the sample resided in Tijuana and the other 50 % in San Diego County. Nearly half (49 %) reported at least one incident of anal sex with a FSW in Tijuana in the past 4 months; of those participants, 85 % reported that one or more of their anal sex acts with FSWs had been without a condom. In a multivariate model, anal sex with a FSW in the past 4 months was associated with bisexual identification, methamphetamine use with FSWs, repeat visits to the same FSW, higher scores on perceived stigma about being a client of FSWs, and sexual compulsivity. Prevention programs are needed that address the behavioral and psychosocial correlates of heterosexual anal sex in order to reduce HIV/STI transmission risk among male clients, FSWs, and their sexual network members.

Correlates of HIV, sexually transmitted infections, and associated high-risk behaviors among male clients of female sex workers in Tijuana, Mexico.

PubMed

Patterson, Thomas L; Goldenberg, Shira; Gallardo, Manuel; Lozada, Remedios; Semple, Shirley J; Orozovich, Prisci; Abramovitz, Daniela; Strathdee, Steffanie A

2009-08-24

To determine sociodemographic and behavioral correlates of HIV infection among male clients of female sex workers (FSWs) in Tijuana. Four hundred men aged 18 years or older who had paid or traded for sex with a FSW in Tijuana during the past 4 months were recruited in Tijuana's 'zone of tolerance,' where prostitution is practiced openly under a municipal permit system. Efforts were made to balance the sample between residents of the United States (San Diego County) and of Mexico (Tijuana). Participants underwent interviews and testing for HIV, syphilis, gonorrhea, and Chlamydia. Logistic regression identified correlates of HIV infection. Mean age was 36.6 years. One-quarter had injected drugs within the previous 4 months. Lifetime use of heroin, cocaine, and methamphetamine was 36, 50, and 64%, respectively. Men had frequented FSWs for an average of 11 years, visiting FSWs an average of 26 times last year. In the past 4 months, one-half reported having unprotected sex with a FSW; 46% reported being high fairly or very often when having sex with a FSW. Prevalence of HIV, syphilis, gonorrhea, and Chlamydia was 4, 2, 2.5, and 7.5%; 14.2% were positive for at least one infection. Factors independently associated with HIV infection were living in Mexico, ever using methamphetamine, living alone, and testing positive for syphilis. Male clients of FSWs in Tijuana had a high sex and drug risk profile. Although sexually transmitted infection prevalence was lower than among FSWs, HIV prevalence was comparable suggesting the need for interventions among clients to prevent spread of HIV and sexually transmitted infections.

Microstructural Analysis of Severe Plastic Deformed Twin Roll Cast AZ31 for the Optimization of Superplastic Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, John P.; Askari, Hesam A.; Heiden, Michael J.

2013-07-08

In recent years magnesium alloys have attracted significant attention as potential candidates to replace many of the heavier metals used in some automotive applications. However, the limited formability of magnesium and its alloys at room temperature has driven interest in the superplastic forming magnesium as an alternative shaping method. Severe plastic deformation techniques have become a well studied method of refining the grain size and modifying the microstructural characteristics of many magnesium alloys to achieve greater superplastic properties. In this study twin roll cast (TRC) AZ31 magnesium alloy was subjected to equal channel angular pressing (ECAP) and friction stir weldingmore » (FSW). The influence of these severe plastic deformation processes on the grain size, texture and grain boundary character distribution was investigated to identify the optimum severe plastic deformation process for the superplastic forming of AZ31.« less

Assessment of vertical excursions and open-sea psychological performance at depths to 250 fsw.

PubMed

Miller, J W; Bachrach, A J; Walsh, J M

1976-12-01

A series of 10 two-man descending vertical excursion dives was carried out in the open sea from an ocean-floor habitat off the coast of Puerto Rico by four aquanauts saturated on a normoxic-nitrogen breathing mixture at a depth of 106 fsw. The purpose of these dives was two-fold: to validate laboratory findings with respect to decompression schedules and to determine whether such excursions would produce evidence of adaptation to nitrogen narcosis. For the latter, tests designed to measure time estimation, short-term memory, and auditory vigilance were used. The validation of experimental excursion tables was carried out without incidence of decompression sickness. Although no signs of nitrogen narcosis were noted during testing, all subjects made significantly longer time estimates in the habitat and during the excursions than on the surface. Variability and incomplete data prevented a statistical analysis of the short-term memory results, and the auditory vigilance proved unusable in the water.

Consistent Condom Use by Female Sex Workers in Kolkata, India: Testing Theories of Economic Insecurity, Behavior Change, Life Course Vulnerability and Empowerment.

PubMed

Fehrenbacher, Anne E; Chowdhury, Debasish; Ghose, Toorjo; Swendeman, Dallas

2016-10-01

Consistent condom use (CCU) is the primary HIV/STI prevention option available to sex workers globally but may be undermined by economic insecurity, life-course vulnerabilities, behavioral factors, disempowerment, or lack of effective interventions. This study examines predictors of CCU in a random household survey of brothel-based female sex workers (n = 200) in two neighborhoods served by Durbar (the Sonagachi Project) in Kolkata, India. Multivariate logistic regression analyses indicated that CCU was significantly associated with perceived HIV risk, community mobilization participation, working more days in sex work, and higher proportion of occasional clients to regular clients. Exploratory analyses stratifying by economic insecurity indicators (i.e., debt, savings, income, housing security) indicate that perceived HIV risk and community mobilization were only associated with CCU for economically secure FSW. Interventions with FSW must prioritize economic security and access to social protections as economic insecurity may undermine the efficacy of more direct condom use intervention strategies.

Friction Stir Welding of Al-B4C Composite Fabricated by Accumulative Roll Bonding: Evaluation of Microstructure and Mechanical Behavior

NASA Astrophysics Data System (ADS)

Moradi Faradonbeh, Alireza; Shamanian, Morteza; Edris, Hossein; Paidar, Moslem; Bozkurt, Yahya

2018-02-01

In this investigation, friction stir welding (FSW) of Al-B4C composite fabricated by 10 cycles accumulative roll bonding was conducted. In order to investigate the influences of pin geometry on microstructure and mechanical properties, four different pin geometries (cylindrical, square, triangular and hexagonal) were selected. It was found that FSW parameters had a major effect on the fragmentation and distribution of reinforcement particles in stir zone. When the tool travel speed was increased, the distribution of B4C particles was become gradually uniform in the aluminum matrix. The effect of tool rotational speed on the peak temperature was determined to be greater than the tool travel speed. The attained data of tensile properties and microhardness tests showed that the tool travel speed had bilateral effect on the tensile strength. The maximum tensile joint efficiency was obtained as 238% for FSWed of Al-2%B4C composite to annealed base Al sheet.

Improving Joint Formation and Tensile Properties of Dissimilar Friction Stir Welding of Aluminum and Magnesium Alloys by Solving the Pin Adhesion Problem

NASA Astrophysics Data System (ADS)

Liu, Zhenlei; Ji, Shude; Meng, Xiangchen

2018-03-01

Friction stir welding (FSW), as a solid-state welding technology invented by TWI in 1991, has potential to join dissimilar Al/Mg alloys. In this study, the pin adhesion phenomenon affecting joint quality during FSW of 6061-T6 aluminum and AZ31B magnesium alloys was investigated. The adhesion phenomenon induced by higher heat input easily transformed the tapered-and-screwed pin into a tapered pin, which greatly reduced the tool's ability to drive the plasticized materials and further deteriorated joint formation. Under the condition without the pin adhesion, the complex intercalated interlayer at the bottom of stir zone was beneficial to mechanical interlocking of Al/Mg alloys, improving tensile properties. However, the formation of intermetallic compounds was still the main reason of the joint fracture, significantly deteriorating tensile properties. Under the welding speed of 60 mm/min without the pin adhesion phenomenon, the maximum tensile strength of 107 MPa and elongation of 1.2% were achieved.

3D simulation of friction stir welding based on movable cellular automaton method

NASA Astrophysics Data System (ADS)

Eremina, Galina M.

2017-12-01

The paper is devoted to a 3D computer simulation of the peculiarities of material flow taking place in friction stir welding (FSW). The simulation was performed by the movable cellular automaton (MCA) method, which is a representative of particle methods in mechanics. Commonly, the flow of material in FSW is simulated based on computational fluid mechanics, assuming the material as continuum and ignoring its structure. The MCA method considers a material as an ensemble of bonded particles. The rupture of interparticle bonds and the formation of new bonds enable simulations of crack nucleation and healing as well as mas mixing and microwelding. The simulation results showed that using pins of simple shape (cylinder, cone, and pyramid) without a shoulder results in small displacements of plasticized material in workpiece thickness directions. Nevertheless, the optimal ratio of longitudinal velocity to rotational speed makes it possible to transport the welded material around the pin several times and to produce a joint of good quality.

Remaining Gap in HIV Testing Uptake Among Female Sex Workers in Iran.

PubMed

Shokoohi, Mostafa; Noori, Atefeh; Karamouzian, Mohammad; Sharifi, Hamid; Khajehkazemi, Razieh; Fahimfar, Noushin; Hosseini-Hooshyar, Samira; Kazerooni, Parvin Afsar; Mirzazadeh, Ali

2017-08-01

We estimated the prevalence of recent HIV testing (i.e., having an HIV test during the last 12 months and knew the results) among 1295 HIV-negative Iranian female sex workers (FSW) in 2015. Overall, 70.4% (95% confidence intervals: 59.6, 79.3) of the participants reported a recent HIV testing. Concerns about their HIV status (83.2%) was reported as the most common reason for HIV testing. Incarceration history, having >5 paying partners, having >1 non-paying partner, receiving harm reduction services, utilizing healthcare services, and knowing an HIV testing site were significantly associated with recent HIV testing. In contrast, outreach participants, having one non-paying sexual partner, and self-reported inconsistent condom use reduced the likelihood of recent HIV testing. HIV testing uptake showed a ~2.5 times increase among FSW since 2010. While these findings are promising and show improvement over a short period, HIV testing programs should be expanded particularly through mobile and outreach efforts.

Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

NASA Astrophysics Data System (ADS)

Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

2016-10-01

In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

Associations of HIV Testing, Sexual Risk and Access to Prevention Among Female Sex Workers in the Dominican Republic.

PubMed

Johnston, Lisa G; Bonilla, Luis; Caballero, Tessie; Rodriguez, Martha; Dolores, Yordana; de la Rosa, Miguel Angel; Malla, Annie; Burnett, Janet; Terrero, Víctor; Martinez, Sam; Morgan, Oliver

2017-08-01

The Caribbean region has one of the highest proportions of HIV in the general female population attributable to sex work. In 2008 (n = 1256) and 2012 (n = 1525) in the Dominican Republic, HIV biological and behavioral surveys were conducted among female sex workers (FSW) in four provinces using respondent driven sampling. Participants were ≥15 years who engaged in intercourse in exchange for money in the past 6 months and living/working in the study province. There were no statistically significant changes in HIV and other infections prevalence from 2008 to 2012, despite ongoing risky sexual practices. HIV testing and receiving results was low in all provinces. FSW in 2012 were more likely to receive HIV testing and results if they participated in HIV related information and education and had regular checkups at health centers. Further investigation is needed to understand barriers to HIV testing and access to prevention services.

Adverse Pregnancy Outcomes and Sexual Violence Among Female Sex Workers Who Inject Drugs on the United States–Mexico Border

PubMed Central

McDougal, Lotus; Strathdee, Steffanie A.; Rangel, Gudelia; Martinez, Gustavo; Vera, Alicia; Sirotin, Nicole; Stockman, Jamila K.; Ulibarri, Monica D.; Raj, Anita

2014-01-01

This study examines the prevalence of miscarriage/stillbirth among female sex workers who inject drugs (FSW-IDUs) and measures its associations with physical and sexual violence. Baseline data from 582 FSW-IDUs enrolled in an HIV intervention study in Tijuana and Ciudad Juárez, Mexico were used for current analyses. 30% of participants had experienced at least one miscarriage/stillbirth, 51% had experienced sexual violence, and 49% had experienced physical violence. History of miscarriage/stillbirth was associated with sexual violence (adjusted odds ratio [aOR] = 1.7, p = .02) but not physical violence. Additional reproductive risks associated with miscarriage/stillbirth included high numbers of male clients in the previous month (aOR = 1.1 per 30 clients, p = 0.04), history of abortion (aOR = 3.7, p < .001), and higher number of pregnancies (aOR = 1.4 per additional pregnancy, p < .001). Programs and research with this population should integrate reproductive health and consider gender-based violence. PMID:23862312

Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling.

PubMed

Rao, Amrita; Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

2017-10-20

In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball samples. In addition, RDS samples indicated lower exposure to HIV prevention information, less knowledge about HIV prevention, limited access to HIV prevention tools such as condoms, and less-reported frequency of sexually transmitted infections (STI) and HIV testing as compared with the venue-based samples. Findings pertaining to the level of disclosure of sexual practices and sexual practice-related stigma were mixed. Samples generated by RDS and venue-based snowball sampling produced significantly different prevalence estimates of several important characteristics. These findings are tempered by limitations to the application of both approaches in practice. Ultimately, these findings provide further context for understanding existing surveillance data and how differences in methods of sampling can influence both the type of individuals captured and whether or not these individuals are representative of the larger target population. These data highlight the need to consider how program coverage estimates of marginalized populations are determined when characterizing the level of unmet need. ©Amrita Rao, Shauna Stahlman, James Hargreaves, Sharon Weir, Jessie Edwards, Duncan Kochelani, Duncan Kochelani, Mpumelelo Mavimbela, Stefan Baral. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 20.10.2017.

Prevalence of high-risk human papilloma virus types and cervical smear abnormalities in female sex workers in Chandigarh, India.

PubMed

Singh, M P; Kaur, M; Gupta, N; Kumar, A; Goyal, K; Sharma, A; Majumdar, M; Gupta, M; Ratho, R K

2016-01-01

Cervical cancer is the most common cancer among women in developing nations. Nearly 90% of the cases have been linked to the presence of high-risk human papillomavirus (hrHPV) types 16 and 18. The risk of cervical cancer may be high in female sex workers (FSWs) due to multiple sexual partners. This study aimed to determine the prevalence of cytological abnormalities and hrHPV types 16 and 18 in FSWs in Chandigarh, North India using the liquid-based cytology (LBC) approach. The cervical brush samples were collected from 120 FSW and 98 age-matched healthy controls (HCs). These were subjected to pap smear using conventional method, LBC and the detection of hrHPV types 16 and 18 was carried out using polymerase chain reaction. The LBC samples showed better cytological details and also reduced the number of unsatisfactory smears from 11% in Pap to 1.5% in the LBC. A significantly higher number of inflammatory smears were reported in FSWs (51.7% vs. 34.7%, P = 0.01). The hrHPV types 16/18 were detected in 33/120 (27.5%) FSW versus 23/98 (23.5%) HCs. The risk of acquiring hrHPV was higher in FSWs, who had age at first sex ≤25 years, higher income and the habit of smoking. The high prevalence of hrHPV among FSWs and HCs suggests the need for the implementation of effective National Screening Programme for early detection of hrHPV types to decrease the burden of cervical cancer, especially in high-risk population.

Managing redwood ecosystems using Sudden Oak Death as a silvicultural tool

Treesearch

Frederick D. Euphrat

2015-01-01

In response to the wave of sudden oak death (SOD), caused by Phytophthora ramorum, sweeping the redwood forest ecosystems of California's North Coast, the role of foresters and other ecosystem managers is being tested. On Bear Flat Tree Farm, near Healdsburg, California, Forest, Soil & Water, Inc. (FSW) has conducted a multi-year,...

29 CFR 1910.425 - Surface-supplied air diving.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 29 Labor 5 2013-07-01 2013-07-01 false Surface-supplied air diving. 1910.425 Section 1910.425... Procedures § 1910.425 Surface-supplied air diving. (a) General. Employers engaged in surface-supplied air...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom...

29 CFR 1910.425 - Surface-supplied air diving.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 29 Labor 5 2012-07-01 2012-07-01 false Surface-supplied air diving. 1910.425 Section 1910.425... Procedures § 1910.425 Surface-supplied air diving. (a) General. Employers engaged in surface-supplied air...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom...

29 CFR 1910.425 - Surface-supplied air diving.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 5 2010-07-01 2010-07-01 false Surface-supplied air diving. 1910.425 Section 1910.425... Procedures § 1910.425 Surface-supplied air diving. (a) General. Employers engaged in surface-supplied air...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom...

29 CFR 1910.425 - Surface-supplied air diving.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 29 Labor 5 2011-07-01 2011-07-01 false Surface-supplied air diving. 1910.425 Section 1910.425... Procedures § 1910.425 Surface-supplied air diving. (a) General. Employers engaged in surface-supplied air...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom...

Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

NASA Technical Reports Server (NTRS)

Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

2006-01-01

A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

Influence of the welding temperature and the welding speed on the mechanical properties of friction stir welds in EN AW-2219-T87

NASA Astrophysics Data System (ADS)

Bachmann, A.; Krutzlinger, M.; Zaeh, M. F.

2018-06-01

Friction Stir Welding (FSW) is an innovative joining technique, which has proven to produce high quality joints in high strength aluminum alloys. Consequently, it is commonly used to manufacture lightweight aerospace structures with stringent requirements. For these structures, it is necessary to ensure a high ultimate tensile strength (UTS). Various studies have reported that the UTS is significantly influenced by the welding parameters. Samples welded with different parameter sets showed a considerably different UTS, despite being free from detectable welding defects (e.g. tunnel defect, voids, or lack of penetration). Based on the observations in the literature, a hypothesis was posed. The welding temperature along with the welding speed determine the UTS of the weld. This study aims to prove this hypothesis experimentally by using temperature-controlled FSW to join plates of EN AW-2219-T87 in butt joint configuration. The welded samples were examined using visual inspection, metallography, X-ray imaging, and uniaxial tensile tests. Finally, a statistical analysis was conducted. Hereby, the hypothesis was confirmed.

Visual Target Tracking on the Mars Exploration Rovers

NASA Technical Reports Server (NTRS)

Kim, Won S.; Biesiadecki, Jeffrey J.; Ali, Khaled S.

2008-01-01

Visual Target Tracking (VTT) has been implemented in the new Mars Exploration Rover (MER) Flight Software (FSW) R9.2 release, which is now running on both Spirit and Opportunity rovers. Applying the normalized cross-correlation (NCC) algorithm with template image magnification and roll compensation on MER Navcam images, VTT tracks the target and enables the rover to approach the target within a few cm over a 10 m traverse. Each VTT update takes 1/2 to 1 minute on the rovers, 2-3 times faster than one Visual Odometry (Visodom) update. VTT is a key element to achieve a target approach and instrument placement over a 10-m run in a single sol in contrast to the original baseline of 3 sols. VTT has been integrated into the MER FSW so that it can operate with any combination of blind driving, Autonomous Navigation (Autonav) with hazard avoidance, and Visodom. VTT can either guide the rover towards the target or simply image the target as the rover drives by. Three recent VTT operational checkouts on Opportunity were all successful, tracking the selected target reliably within a few pixels.

Investigation of the material flow and texture evolution in friction-stir welded aluminum alloy

NASA Astrophysics Data System (ADS)

Kang, Suk Hoon; Han, Heung Nam; Oh, Kyu Hwan; Cho, Jae-Hyung; Lee, Chang Gil; Kim, Sung-Joon

2009-12-01

The material flow and crystallographic orientation in aluminum alloy sheets joined by friction stir welding (FSW) were investigated by electron back scattered diffraction (EBSD). The microstructure and microtexture of the material near the stir zone was found to be influenced by the rotational behavior of the tool pin. It was found that, during FSW, the forward movement of the tool pin resulted in loose contact between the tool pin and the receding material at the advancing side. This material behavior inside the joined aluminum plates was also observed by an X-ray micrograph by inlaying a gold marker into the plates. As the advancing speed of the tool increases at a given rotation speed, the loose contact region widens. As the microtexture of the material near the stir zone is very close to the simple shear texture on the basis of the frame of the tool pin in the normal and tangent directions, the amount of incompletely rotated material due to the loose contact could be estimated from the tilt angle of the shear texture in the pole figure around the key hole.

The longitudinal association of venue stability with consistent condom use among female sex workers in two Mexico–USA border cities

PubMed Central

Gaines, T L; Rudolph, A E; Brouwer, K C; Strathdee, S A; Lozada, R; Martinez, G; Goldenberg, S M; Rusch, M L A

2014-01-01

Summary We examined the relationship between venue stability and consistent condom use (CCU) among female sex workers who inject drugs (FSW-IDUs; n = 584) and were enrolled in a behavioural intervention in two Mexico–USA border cities. Using a generalized estimating equation approach stratified by client type and city, we found venue stability affected CCU. In Tijuana, operating primarily indoors was significantly associated with a four-fold increase in the odds of CCU among regular clients (odds ratio [OR]: 3.77, 95% confidence interval [CI]: 1.44, 9.89), and a seven-fold increase among casual clients (OR: 7.18, 95% CI: 2.32, 22.21), relative to FSW-IDUs spending equal time between indoor and outdoor sex work venues. In Ciudad Juarez, the trajectory of CCU increased over time and was highest among those operating primarily indoors. Results from this analysis highlight the importance of considering local mobility, including venue type and venue stability, as these characteristics jointly influence HIV risk behaviours. PMID:23970766

FSW of Aluminum Tailor Welded Blanks across Machine Platforms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovanski, Yuri; Upadhyay, Piyush; Carlson, Blair

2015-02-16

Development and characterization of friction stir welded aluminum tailor welded blanks was successfully carried out on three separate machine platforms. Each was a commercially available, gantry style, multi-axis machine designed specifically for friction stir welding. Weld parameters were developed to support high volume production of dissimilar thickness aluminum tailor welded blanks at speeds of 3 m/min and greater. Parameters originally developed on an ultra-high stiffness servo driven machine where first transferred to a high stiffness servo-hydraulic friction stir welding machine, and subsequently transferred to a purpose built machine designed to accommodate thin sheet aluminum welding. The inherent beam stiffness, bearingmore » compliance, and control system for each machine were distinctly unique, which posed specific challenges in transferring welding parameters across machine platforms. This work documents the challenges imposed by successfully transferring weld parameters from machine to machine, produced from different manufacturers and with unique control systems and interfaces.« less

High HIV Prevalence and Risk Among Male Clients of Female Sex Workers in Hanoi and Ho Chi Minh City, Vietnam.

PubMed

Nadol, Patrick; Hoang, Tran Vu; Le, Linh-Vi; Nguyen, Tuan Anh; Kaldor, John; Law, Matthew

2017-08-01

In Vietnam's concentrated HIV epidemic, female sex workers (FSWs) are at increased risk for acquiring and transmitting HIV, largely through their male clients. A high proportion of males in Vietnam report being clients of FSWs. Studying HIV-related risk factors and prevalence among male clients is important, particularly given the potential for male clients to be a 'bridge' of HIV transmission to the more general population or to sex workers. Time-location sampling was used to identify FSW in Hanoi and Ho Chi Minh City, Vietnam's largest cities, in 2013-2014. Recruited FSWs were asked to refer one male client to the study. Demographic and risk behavior data were collected from FSWs and male clients by administered questionnaires. Biologic specimens collected from male clients were tested for HIV and opiates. Sampling weights, calculated based on the FSWs probability of being selected for enrolment, were applied to prevalence estimates for both FSWs and male clients. Logistic regression models were developed to obtain odds ratios for HIV infection among male clients. A total of 804 male clients were enrolled. Overall, HIV prevalence among male clients was 10.2%; HIV prevalence was 20.7% (95% confidence interval (CI) 15.0-27.9%) among those reporting a history of illegal drug use and 32.4% (95% CI 20.2-47.7%) among those with opioids detected in urine. HIV prevalence among male clients did not differ across 'bridging' categories defined by condom use with FSWs and regular partners over the previous 6 months. HIV among male clients was associated with a reported history of illegal drug use (OR 3.76; 95% CI 1.87-7.56), current opioid use (OR 2.55; 95% CI 1.02-6.36), and being referred by an FSW who self-reported as HIV-positive (OR 5.37; 95% CI 1.46-19.75). Self-reported HIV prevalence among enrolled FSWs was 2.8%. Based on HIV test results of male clients and self-reported status from FSWs, an estimated 12.1% of male client-FSW pairs were sero-discordant. These results indicate high HIV prevalence among male clients of FSWs, particularly among those with a history of drug use. Programs to expand HIV testing, drug-use harm reduction, and HIV treatment for HIV-infected male clients of FSWs should be considered as key interventions for controlling the HIV epidemic in Vietnam.

Epidemiology of HPV Genotypes among HIV Positive Women in Kenya: A Systematic Review and Meta-Analysis.

PubMed

Menon, Sonia; Wusiman, Aibibula; Boily, Marie Claude; Kariisa, Mbabazi; Mabeya, Hillary; Luchters, Stanley; Forland, Frode; Rossi, Rodolfo; Callens, Steven; Vanden Broeck, Davy

2016-01-01

There is a scarcity of data on the distribution of human papillomavirus (HPV) genotypes in the HIV positive population and in invasive cervical cancer (ICC) in Kenya. This may be different from genotypes found in abnormal cytology. Yet, with the advent of preventive HPV vaccines that target HPV 16 and 18, and the nonavalent vaccine targeting 90% of all ICC cases, such HPV genotype distribution data are indispensable for predicting the impact of vaccination and HPV screening on prevention. Even with a successful vaccination program, vaccinated women will still require screening to detect those who will develop ICC from other High risk (HR) HPV genotypes not prevented by current vaccines. The aim of this review is to report on the prevalence of pHR/HR HPV types and multiple pHR/HR HPV genotypes in Kenya among HIV positive women with normal, abnormal cytology and ICC. PUBMED, EMBASE, SCOPUS, and PROQUEST were searched for articles on HPV infection up to August 2nd 2016. Search terms were HIV, HPV, Cervical Cancer, Incidence or Prevalence, and Kenya. The 13 studies included yielded a total of 2116 HIV-infected women, of which 89 had ICC. The overall prevalence of pHR/HR HPV genotypes among HIV-infected women was 64% (95%CI: 50%-77%). There was a borderline significant difference in the prevalence of pHR/HR HPV genotypes between Female Sex workers (FSW) compared to non-FSW in women with both normal and abnormal cytology. Multiple pHR/HR HPV genotypes were highly prominent in both normal cytology/HSIL and ICC. The most prevalent HR HPV genotypes in women with abnormal cytology were HPV 16 with 26%, (95%CI: 23.0%-30.0%) followed by HPV 35 and 52, with 21% (95%CI: 18%-25%) and 18% (95%CI: 15%-21%), respectively. In women with ICC, the most prevalent HPV genotypes were HPV 16 (37%; 95%CI: 28%-47%) and HPV 18 (24%; 95%CI: 16%-33%). HPV 16/18 gains prominence as the severity of cervical disease increases, with HPV 16/18 accounting for 61% (95%CI: 50.0%-70.0%) of all ICC cases. A secondary prevention program will be necessary as this population harbors multiple pHR/HR HPV co-infections, which may not be covered by current vaccines. A triage based on FSW as an indicator may be warranted.

Epidemiology of HPV Genotypes among HIV Positive Women in Kenya: A Systematic Review and Meta-Analysis

PubMed Central

Menon, Sonia; Wusiman, Aibibula; Boily, Marie Claude; Kariisa, Mbabazi; Mabeya, Hillary; Luchters, Stanley; Forland, Frode; Rossi, Rodolfo; Callens, Steven; vanden Broeck, Davy

2016-01-01

Background There is a scarcity of data on the distribution of human papillomavirus (HPV) genotypes in the HIV positive population and in invasive cervical cancer (ICC) in Kenya. This may be different from genotypes found in abnormal cytology. Yet, with the advent of preventive HPV vaccines that target HPV 16 and 18, and the nonavalent vaccine targeting 90% of all ICC cases, such HPV genotype distribution data are indispensable for predicting the impact of vaccination and HPV screening on prevention. Even with a successful vaccination program, vaccinated women will still require screening to detect those who will develop ICC from other High risk (HR) HPV genotypes not prevented by current vaccines. The aim of this review is to report on the prevalence of pHR/HR HPV types and multiple pHR/HR HPV genotypes in Kenya among HIV positive women with normal, abnormal cytology and ICC. Methods PUBMED, EMBASE, SCOPUS, and PROQUEST were searched for articles on HPV infection up to August 2nd 2016. Search terms were HIV, HPV, Cervical Cancer, Incidence or Prevalence, and Kenya. Results The 13 studies included yielded a total of 2116 HIV-infected women, of which 89 had ICC. The overall prevalence of pHR/HR HPV genotypes among HIV-infected women was 64% (95%CI: 50%-77%). There was a borderline significant difference in the prevalence of pHR/HR HPV genotypes between Female Sex workers (FSW) compared to non-FSW in women with both normal and abnormal cytology. Multiple pHR/HR HPV genotypes were highly prominent in both normal cytology/HSIL and ICC. The most prevalent HR HPV genotypes in women with abnormal cytology were HPV 16 with 26%, (95%CI: 23.0%-30.0%) followed by HPV 35 and 52, with 21% (95%CI: 18%-25%) and 18% (95%CI: 15%-21%), respectively. In women with ICC, the most prevalent HPV genotypes were HPV 16 (37%; 95%CI: 28%-47%) and HPV 18 (24%; 95%CI: 16%-33%). Conclusion HPV 16/18 gains prominence as the severity of cervical disease increases, with HPV 16/18 accounting for 61% (95%CI: 50.0%-70.0%) of all ICC cases. A secondary prevention program will be necessary as this population harbors multiple pHR/HR HPV co-infections, which may not be covered by current vaccines. A triage based on FSW as an indicator may be warranted. PMID:27764092

Diversity among clients of female sex workers in India: comparing risk profiles and intervention impact by site of solicitation. implications for the vulnerability of less visible female sex workers.

PubMed

Suryawanshi, Dipak; Bhatnagar, Tarun; Deshpande, Sucheta; Zhou, Weiwei; Singh, Pankaj; Collumbien, Martine

2013-01-01

It seems generally accepted that targeted interventions in India have been successful in raising condom use between female sex workers (FSWs) and their clients. Data from clients of FSWs have been under-utilised to analyse the risk environments and vulnerability of both partners. The 2009 Integrated Biological and Behavioural Assessment survey sampled clients of FSWs at hotspots in Andhra Pradesh, Maharashtra and Tamil Nadu (n=5040). The risk profile of clients in terms of sexual networking and condom use are compared across usual pick-up place. We used propensity score matching (PSM) to estimate the average treatment effect on treated (ATT) of intervention messages on clients' consistent condom use with FSW. Clients of the more hidden sex workers who solicit from home or via phone or agents had more extensive sexual networks, reporting casual female partners as well as anal intercourse with male partners and FSW. Clients of brothel-based sex workers, who were the least educated, reported the fewest number/categories of partners, least anal sex, and lowest condom use (41%). Consistent condom use varied widely by state: 65% in Andhra Pradesh, 36% in Maharashtra and 29% in Tamil Nadu. Exposure to intervention messages on sexually transmitted infections was lowest among men frequenting brothels (58%), and highest among men soliciting less visible sex workers (70%). Exposure had significant impact on consistent condom use, including among clients of home-based sex workers (ATT 21%; p=0.001) and among men soliciting other more hidden FSW (ATT 17%; p=0.001). In Tamil Nadu no impact could be demonstrated. Commercial sex happens between two partners and both need to be, and can be, reached by intervention messages. Commercial sex is still largely unprotected and as the sex industry gets more diffuse a greater focus on reaching clients of sex workers seems important given their extensive sexual networks.

Diversity among Clients of Female Sex Workers in India: Comparing Risk Profiles and Intervention Impact by Site of Solicitation. Implications for the Vulnerability of Less Visible Female Sex Workers

PubMed Central

Suryawanshi, Dipak; Bhatnagar, Tarun; Deshpande, Sucheta; Zhou, Weiwei; Singh, Pankaj; Collumbien, Martine

2013-01-01

Background It seems generally accepted that targeted interventions in India have been successful in raising condom use between female sex workers (FSWs) and their clients. Data from clients of FSWs have been under-utilised to analyse the risk environments and vulnerability of both partners. Methods The 2009 Integrated Biological and Behavioural Assessment survey sampled clients of FSWs at hotspots in Andhra Pradesh, Maharashtra and Tamil Nadu (n=5040). The risk profile of clients in terms of sexual networking and condom use are compared across usual pick-up place. We used propensity score matching (PSM) to estimate the average treatment effect on treated (ATT) of intervention messages on clients’ consistent condom use with FSW. Results Clients of the more hidden sex workers who solicit from home or via phone or agents had more extensive sexual networks, reporting casual female partners as well as anal intercourse with male partners and FSW. Clients of brothel-based sex workers, who were the least educated, reported the fewest number/categories of partners, least anal sex, and lowest condom use (41%). Consistent condom use varied widely by state: 65% in Andhra Pradesh, 36% in Maharashtra and 29% in Tamil Nadu. Exposure to intervention messages on sexually transmitted infections was lowest among men frequenting brothels (58%), and highest among men soliciting less visible sex workers (70%). Exposure had significant impact on consistent condom use, including among clients of home-based sex workers (ATT 21%; p=0.001) and among men soliciting other more hidden FSW (ATT 17%; p=0.001). In Tamil Nadu no impact could be demonstrated. Conclusion Commercial sex happens between two partners and both need to be, and can be, reached by intervention messages. Commercial sex is still largely unprotected and as the sex industry gets more diffuse a greater focus on reaching clients of sex workers seems important given their extensive sexual networks. PMID:24023877

Factors associated with history of drug use among female sex workers (FSW) in a high HIV prevalence state of India.

PubMed

Medhi, Gajendra Kumar; Mahanta, Jagadish; Kermode, Michelle; Paranjape, Ramesh S; Adhikary, Rajatashuvra; Phukan, Sanjib Kumar; Ngully, P

2012-04-05

The intersection between illicit drug use and female commercial sex work has been identified as an important factor responsible for rising HIV prevalence among female sex workers (FSW) in several northeastern states of India. But, little is know about the factors associated with the use of drugs among FSWs in this region. The objective of the paper was to describe the factors associated with history of drug use among FSWs in Dimapur, an important commercial hub of Nagaland, which is a high HIV prevalence state of India. FSWs were recruited using respondent driven sampling (RDS), and were interviewed to collect data on socio-demographic characteristics and HIV risk behaviours. Biological samples were tested for HIV, syphilis gonorrhea and Chlamydia. Logistic regression analysis was performed to identify factors associated with drug use. Among the 426 FSWs in the study, about 25% (n = 107) reported having ever used illicit drugs. Among 107 illicit drug users, 83 (77.6%) were non-injecting and 24 (22.4%) were injecting drug users. Drug-using FSWs were significantly more likely to test positive for one or more STIs (59% vs. 33.5%), active syphilis (27.1% vs. 11.4%) and Chlamydia infection (30% vs. 19.9%) compared to their non-drug using peers. Drug-using FSWs were also significantly more likely to be currently married, widowed or separated compared with non-drug-using FSWs. In multiple logistic regression analysis, being an alcohol user, being married, having a larger volume of clients, and having sexual partners who have ever used or shared injecting drugs were found to be independently associated with illicit drug use. Drug-using FSWs were more vulnerable to STIs including HIV compared to their non-drug using peers. Several important factors associated with being an FSW who uses drugs were identified in this study and this knowledge can be used to plan more effectively targeted harm reduction strategies and programs.

A comprehensive review of available epidemiologic and HIV service data for female sex workers, men who have sex with men, and people who inject drugs in select West and Central African countries.

PubMed

MacAllister, Jack; Sherwood, Jennifer; Galjour, Joshua; Robbins, Sarah; Zhao, Jinkou; Dam, Kim; Grosso, Ashley; Baral, Stefan D

2015-03-01

To identify gaps in epidemiologic and HIV service coverage data for key populations (KP), including men who have sex with men (MSM), female sex workers (FSW), people who inject drugs (PWID), and transgender persons, in 8 West and Central Africa countries: Cameroon, Chad, Cote d'Ivoire, Democratic Republic of Congo, Ghana, Guinea-Bissau, Niger, and Nigeria. A comprehensive search of peer-reviewed literature was conducted using PubMed and MEDLINE. This search was supplemented by an additional search of relevant non-peer-reviewed, or gray, literature. Available data on HIV prevalence, KP size estimates, HIV prevention service targets, and HIV prevention service coverage, including the availability of population-specific minimum packages of services, were included in the review. No data for transgender persons were found. HIV prevalence data and size estimates were more frequently available for FSW, followed by MSM. Only 2 countries (Ghana and Nigeria) had both KP size estimates and HIV prevalence data for PWID. The degree to which HIV prevention service targets were adopted was highly variable across the selected countries, and the collection of relevant HIV prevention service coverage data for those targets that were identified was inconsistent. Population-specific minimum packages of services were identified in 3 countries (Cote d'Ivoire, Ghana, and Nigeria), although only Ghana and Nigeria included services for PWID. Epidemiologic and HIV prevention service data for FSW, MSM, PWID, and transgender persons remain sparse, and these KP are inconsistently accounted for in-service delivery and nationally endorsed minimum packages of HIV services in West and Central Africa. The strengthening of data collection and reporting to consistently include KP and the inclusion of that data in national planning is imperative for effectively addressing the HIV epidemic.

Deformation During Friction Stir Welding

NASA Technical Reports Server (NTRS)

White, Henry J.

2002-01-01

Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

Assembly of 5.5-Meter Diameter Developmental Barrel Segments for the Ares I Upper Stage

NASA Technical Reports Server (NTRS)

Carter, Robert W.

2011-01-01

Full scale assembly welding of Ares I Upper Stage 5.5-Meter diameter cryogenic tank barrel segments has been performed at the Marshall Space Flight Center (MSFC). One full-scale developmental article produced under the Ares 1 Upper Stage project is the Manufacturing Demonstration Article (MDA) Barrel. This presentation will focus on the welded assembly of this barrel section, and associated lessons learned. Among the MDA articles planned on the Ares 1 Program, the Barrel was the first to be completed, primarily because the process of manufacture from piece parts (barrel panels) utilized the most mature friction stir process planned for use on the Ares US program: Conventional fixed pin Friction Stir Welding (FSW). This process is in use on other space launch systems, including the Shuttle s External Tank, the Delta IV common booster core, the Delta II, and the Atlas V rockets. The goals for the MDA Barrel development were several fold: 1) to prove out Marshall Space Flight Center s new Vertical Weld Tool for use in manufacture of cylindrical barrel sections, 2) to serve as a first run for weld qualification to a new weld specification, and 3) to provide a full size cylindrical section for downstream use in precision cleaning and Spray-on Foam Insulation development. The progression leading into the welding of the full size barrel included sub scale panel welding, subscale cylinder welding, a full length confidence weld, and finally, the 3 seamed MDA barrel processing. Lessons learned on this MDA program have been carried forward into the production tooling for the Ares 1 US Program, and in the use of the MSFC VWT in processing other large scale hardware, including two 8.4 meter diameter Shuttle External Tank barrel sections that are currently being used in structural analysis to validate shell buckling models.

High-Speed Friction Stir Welding of AA7075-T6 Sheet: Microstructure, Mechanical Properties, Micro-texture, and Thermal History

NASA Astrophysics Data System (ADS)

Zhang, Jingyi; Upadhyay, Piyush; Hovanski, Yuri; Field, David P.

2018-01-01

Friction stir welding (FSW) is a cost-effective and high-quality joining process for aluminum alloys (especially heat-treatable alloys) that is historically operated at lower joining speeds (up to hundreds of millimeters per minute). In this study, we present a microstructural analysis of friction stir welded AA7075-T6 blanks with high welding speeds up to 3 M/min. Textures, microstructures, mechanical properties, and weld quality are analyzed using TEM, EBSD, metallographic imaging, and Vickers hardness. The higher welding speed results in narrower, stronger heat-affected zones (HAZs) and also higher hardness in the nugget zones. The material flow direction in the nugget zone is found to be leaning towards the welding direction as the welding speed increases. Results are coupled with welding parameters and thermal history to aid in the understanding of the complex material flow and texture gradients within the welds in an effort to optimize welding parameters for high-speed processing.

Weldability of AA 5052 H32 aluminium alloy by TIG welding and FSW process - A comparative study

NASA Astrophysics Data System (ADS)

Shanavas, S.; Raja Dhas, J. Edwin

2017-10-01

Aluminium 5xxx series alloys are the strongest non-heat treatable aluminium alloy. Its application found in automotive components and body structures due to its good formability, good strength, high corrosion resistance, and weight savings. In the present work, the influence of Tungsten Inert Gas (TIG) welding parameters on the quality of weld on AA 5052 H32 aluminium alloy plates were analyzed and the mechanical characterization of the joint so produced was compared with Friction stir (FS) welded joint. The selected input variable parameters are welding current and inert gas flow rate. Other parameters such as welding speed and arc voltage were kept constant throughout the study, based on the response from several trial runs conducted. The quality of the weld is measured in terms of ultimate tensile strength. A double side V-butt joints were fabricated by double pass on one side to ensure maximum strength of TIG welded joints. Macro and microstructural examination were conducted for both welding process.

Assessing the Role of Head Start Family Service Workers.

ERIC Educational Resources Information Center

Franze, Sarah E.; Foster, Martha; Abbott-Shim, Martha

The purpose of this paper is to address the evaluation of the social service component of Head Start, through its main contributor, the family service worker (FSW). Sixty-six Head Start family service workers--arranged in 3 focus groups of 10 to 20 workers--from both rural and urban communities in the Southeast met to discuss the characteristics…

An HIV-Prevention Intervention for Sex Workers in Tijuana, Mexico: A Pilot Study

ERIC Educational Resources Information Center

Patterson, Thomas L.; Semple, Shirley J.; Fraga, Miguel; Bucardo, Jesus; Davila-Fraga, Wendy; Strathdee, Steffanie A.

2005-01-01

Female sex workers (FSW) are at high risk of acquiring sexually transmitted infections (STIs), including HIV, and putting their clients and other partners at risk for infection. There is considerable evidence that Social Cognitive Theory (SCT)?based interventions are effective in reducing high-risk sexual behavior among at-risk populations in the…

Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints

NASA Astrophysics Data System (ADS)

Lakshminarayanan, A. K.; Balasubramanian, V.

2012-04-01

This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.