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1

An Approach to Optimize Size Parameters of Forging by Combining Hot-Processing Map and FEM  

NASA Astrophysics Data System (ADS)

The size parameters of 6061 aluminum alloy rib-web forging were optimized by using hot-processing map and finite element method (FEM) based on high-temperature compression data. The results show that the stress level of the alloy can be represented by a Zener-Holloman parameter in a hyperbolic sine-type equation with the hot deformation activation energy of 343.7 kJ/mol. Dynamic recovery and dynamic recrystallization concurrently preceded during high-temperature deformation of the alloy. Optimal hot-processing parameters for the alloy corresponding to the peak value of 0.42 are 753 K and 0.001 s-1. The instability domain occurs at deformation temperature lower than 653 K. FEM is an available method to validate hot-processing map in actual manufacture by analyzing the effect of corner radius, rib width, and web thickness on workability of rib-web forging of the alloy. Size parameters of die forgings can be optimized conveniently by combining hot-processing map and FEM.

Hu, H. E.; Wang, X. Y.; Deng, L.

2014-11-01

2

Effect of the Process Parameters on the Formability, Microstructure, and Mechanical Properties of Thin Plates Fabricated by Rheology Forging Process with Electromagnetic Stirring Method  

NASA Astrophysics Data System (ADS)

A thin plate (150 × 150 × 1.2 mm) with embedded corrugation is fabricated using the rheoforming method. Semisolid slurry is created using the electromagnetic stirring (EMS) system, and the thin plate is made with the forging die at the 200-ton hydraulic press. The cross sections and microstructures of the slurry with and without stirring are examined. To investigate the effect of the process parameters on the formability, microstructure, and mechanical properties of thin plate the slurry is subjected to 16 types of condition for the forging experiment. The 16 types included the following conditions: Whether the EMS is applied or not, three fractions of the solid phase at 35, 45 and 55 pct; two compression velocities at 30 and 300 mm s-1; and four different compression pressures—100, 150, 200 and 250 MPa. The thin plate's formability is enhanced at higher punch velocity for compressing the slurry, and fine solid particles are uniformly distributed, which in turn, enhances the plate's mechanical properties. The pressure between 150 and 200 MPa is an appropriate condition to form thin plates. A thin plate without defects can be created when the slurry at 35 pct of the solid fraction (f s) was applied at the compression velocity of 300 mm s-1 and 150 MPa of pressure. The surface state of thin plate is excellent with 220 MPa of tensile strength and 13.5 pct of elongation. The primary particles are fine over the entire plate, and there are no liquid segregation-related defects.

Jin, Chul Kyu; Jang, Chang Hyun; Kang, Chung Gil

2014-01-01

3

Industrial introduction of the modeling of aeronautical forging and foundry process simulation  

NASA Astrophysics Data System (ADS)

Problems encountered in the industrial application of aeronautical forging and foundry process simulation modeling which arise from both the complexity of the processes simulated and the geometries considered are reviewed. It is noted that current three-demensional meshes are useful in modeling complex geometries. Such simulation programs make possible: (1) detailed process analysis; (2) the study of the sensitivity of various fabrication parameters; (3) equipment optimization; and (4) the efficient automation of fabrication. The most advanced modeling integration has been in the industrial production of large axisymmetric forged parts.

Bachelet, Eric; Honnorat, Yves

1988-08-01

4

Application of the finite element method in cold forging processes  

Microsoft Academic Search

The demand for more efficient manufacturing processes has been increasing in the last few years. The cold forging process is presented as a possible solution, because it allows the production of parts with a good surface finish and with good mechanical properties. Nevertheless, the cold forming sequence design is very empirical and it is based on the designer experience. The

Cristina Maria; Oliveira Lima

2000-01-01

5

Prediction of Final Material State in MultiStage Forging Processes  

Microsoft Academic Search

Multi-stage forging processes are used to manufacture reservoirs for high pressure hydrogen and tritium storage. The warm-forging process is required to produce required macro and microscale forged material properties of 304 and 21-6-9 stainless steel. Strict requirements on the forged material strength, grain size and grain flow are necessitated to inhibit the diffusion of gas which inevitably leads to material

Michael L. Chiesa; Arthur A. Brown; Bonnie R. Antoun; Jakob T. Ostien; Richard A. Regueiro; Douglas J. Bammann; Nancy Y. Yang

2004-01-01

6

Process modelings and simulations of heavy castings and forgings  

NASA Astrophysics Data System (ADS)

The Materials Process Modeling Division, IMR, CAS has been promoting for more than 10 years research activities on modeling and experimental studies on heavy castings and forgings. In this report, we highlight some selected achievements and impacts in this area: To satisfy domestic strategic requirements, such as nuclear and hydraulic power, marine projects and high speed rail, we have developed a number of casting and forging technologies, which combine advanced computing simulations, X-ray real time observation techniques and industrial-scaled trial experiments. These technologies have been successfully applied in various industrial areas and yielded a series of scientific and technological breakthroughs and innovation. Important examples of this strategic research include the hot-processing technologies of the Three Gorge water turbine runner, marine crankshaft manufacturers, backup rolls for hot rolling mills and the production of hundreds-ton steel ingot.

Li, Dianzhong; Sun, Mingyue; Wang, Pei; Kang, Xiuhong; Fu, Paixian; Li, Yiyi

2013-05-01

7

First Results of Energy Saving at Process Redesign of Die Forging Al-Alloys  

SciTech Connect

The contribution deals with eco-friendly solutions for shortened production chains of forging light alloys. During the die forging operations a remarkable amount of material goes into the flash and later on into chips during finish machining. These low value side products are rich with embedded energy therefore recycling or reprocessing could be very energy saving procedure.In cooperation with a die forging company a shortened reprocessing cycle has been studied starting from re-melting the forging flash and without additional heating to cast preforms for subsequent die forging. As such preforms have not as good formability characteristics as those done from extruded billets the isothermal forging process has been adopted. First results showed that without cracks and other defects the formability is sufficient for a broad spectrum of forgings.To improve the formability a homogenization process of cast preforms has been implemented. As the process started immediately after casting, amount of additional energy for heating was minimized. To reduce voids forging process was redesigned in a way to assure greater hydrostatic pressures in parts during forging. First results were promising therefore research is going towards improving processes without adding significantly more energy as it is needed for casting with homogenization and die forging.

Pepelnjak, Tomaz; Kuzman, Karl [Faculty of Mechanical Engineering, Askerceva 6, SI-1000 Ljubljana (Slovenia); Kokol, Anton [Kovinar-forging company, Kovaska cesta 12, SI-3205 Vitanje (Slovenia)

2011-05-04

8

Material Behavior Based Hybrid Process for Sheet Draw-Forging Thin Walled Magnesium Alloys  

SciTech Connect

Magnesium alloys are conventionally formed at the elevated temperatures. The thermally improved formability is sensitive to the temperature and strain rate. Due to limitations in forming speeds, tooling strength and narrow processing windows, complex thin walled parts cannot be made by traditional warm drawing or hot forging processes. A hybrid process, which is based on the deformation mechanism of magnesium alloys at the elevated temperature, is proposed that combines warm drawing and hot forging modes to produce an aggressive geometry at acceptable forming speed. The process parameters, such as temperatures, forming speeds etc. are determined by the FEM modeling and simulation. Sensitivity analysis under the constraint of forming limits of Mg alloy sheet material and strength of tooling material is carried out. The proposed approach is demonstrated on a conical geometry with thin walls and with bottom features. Results show that designed geometry can be formed in about 8 seconds, this cannot be formed by conventional forging while around 1000s is required for warm drawing. This process is being further investigated through controlled experiments.

Sheng, Z.Q.; Shivpuri, R. [Industrial, Welding and System Engineering at the Ohio State University, Columbus, Oh, 43210 (United States)

2005-08-05

9

A novel process for breakdown forging of coarse-grain intermetallic alloys  

SciTech Connect

The objective of the present work was to develop a novel hot forging process for breakdown of high-temperature intermetallic alloys which exhibit dynamic recrystallization during hot working. During typical forging processes in hydraulic processes, be they based on isothermal or conventional approaches, the ram speed (or sometimes the effective strain rate) is held constant during the forging stroke. In the method introduced here, the ram speed is increased substantially during the forging stroke as the material recrystallizes to a finer-grained structure and its hot workability increases. By this means, fracture is avoided, grain size is reduced, and processing time is decreased, thus improving material quality and reducing cost. The material used to develop and demonstrate the novel forging process was the single phase gamma titanium aluminide, Ti-51Al-2Mn.

Semiatin, S.L. (Wright Lab., Wright-Patterson AFB, OH (United States). Materials Directorate); McQuay, P.A. (AFOSR/AOARD, Tokyo (Japan). Asian Office of Aerospace R and D); Seetharaman, V. (UES, Dayton, OH (United States))

1993-11-01

10

Mesoscale simulation of microstructure evolution during multi-stage hot forging processes  

NASA Astrophysics Data System (ADS)

The paper presents a two-dimensional cellular automaton (CA) approach coupled with a topology deformation technique for quantitative and topographic prediction of the microstructure evolution during multi-stage hot forging processes. The simulation presented in this work was implemented by an in-house developed C++ program. The grain topography, recrystallization fraction and average grain size were also obtained during a four-hit forging process. The simulated results agree well with the experimental data in terms of average grain size, suggesting that the developed CA model is a reliable numerical approach for predicting microstructure evolution for ultra-super-critical rotor steel during multi-stage hot forging processes.

Chen, Fei; Cui, Zhenshan

2012-06-01

11

An optimization method for radial forging process using ANN and Taguchi method  

Microsoft Academic Search

In this study, the artificial neural network (ANN) and the Taguchi method are employed to optimize the radial force and strain\\u000a inhomogeneity in radial forging process. The finite element analysis of the process verified by the microhardness test (to\\u000a confirm the predicted strain distribution) and the experimental forging load published by the previous researcher are used\\u000a to predict the strain

M. Sanjari; A. Karimi Taheri; M. R. Movahedi

2009-01-01

12

Processing and properties of hot-forged bulk superconductors  

SciTech Connect

(Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223) and TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Tl-1223) bars were hot forged in air at 820--850C. Final stresses of 2--3 MPa were sufficient to produce >95% dense Bi-2223 bars. In contrast, stresses to {approx}42 MPa were able to produce only 75--80% dense Tl-1223 bars. The Bi-2223 bars were more phase-pure and exhibited much stronger c-axis textures than the Tl-1223. Maximum critical current densities at 77 K were 8 {times} 10{sup 4} A/cm{sup 2} for the Bi-2223 and 2 {times} 10{sup 4}/cm{sup 2} for the Tl-1223. Fracture strength and toughness values were 140 MPa and 2.9 MPa{radical}m for the Bi-2223 and 50 MPa and 0.5 MPa{radical}m for the Tl-1223.

Goretta, K.C.; Lanagan, M.T.; Picciolo, J.J.; Youngdahl, C.A.; Balachandran, U. [Argonne National Lab., IL (United States); Chen, Nan [Illinois Superconductor Corp., Mount Prospect, IL (United States)

1995-12-31

13

Computer-assisted Rheo-forging Processing of A356 Aluminum Alloys  

SciTech Connect

Die casting process has been used widely for complex automotive products such as the knuckle, arm and etc. Generally, a part fabricated by casting has limited strength due to manufacturing defects by origin such as the dendrite structure and segregation. As an attempt to offer a solution to these problems, forging has been used as an alternative process. However, the forging process provides limited formability for complex shape products. Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials of the desired microstructure, a stirring process is applied during solidification of A356 aluminum molten state. This paper presents the results of an A356 aluminum alloy sample, which were obtained by experiment and by simulation using DEFORM 3D V6.1. Samples of metal parts were subsequently fabricated by using hydraulic press machinery. In order to compare the influence of loading method, two types of samples were fabricated: (1) samples fabricated under direct loading die sets (2) those fabricated under indirect loading die sets. The formability and defects, which were predicted by FEM simulation, were similar to those of samples used in practice.

Kim, H. H. [Department of Mechanical and Precision Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, C. G. [School of Mechanical Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2010-06-15

14

An investigation of a new near-beta forging process for titanium alloys and its application in aviation components  

Microsoft Academic Search

In this paper, the authors present a new near-beta forging process, in which materials are heated at about 15°C below the beta transus, to improve the combined properties of titanium alloys. Materials processed by the near-beta forging process, followed by rapid water-cooling, then high temperature toughening and low temperature strengthening heat treatments, produce a new kind of microstructure for titanium

Y. G. Zhou; W. D. Zeng; H. Q. Yu

2005-01-01

15

An analysis of the forging processes for 6061 aluminum-alloy wheels  

Microsoft Academic Search

The metal forming processes of aluminum-alloy wheel forging at elevated temperatures are analyzed by the finite element method. A coupled thermo-mechanical model for the analysis of plastic deformation and heat transfer is adapted in the finite element formulation. In order to consider the strain-rate effects on material properties and the flow stress dependence on temperatures, the rigid visco-plasticity is applied

Y. H. Kim; T. K. Ryou; H. J. Choi; B. B. Hwang

2002-01-01

16

Manufacturing of Precision Forgings by Radial Forging  

SciTech Connect

Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

Wallner, S.; Harrer, O.; Buchmayr, B. [Chair of Metal Forming, Department Product Engineering, University of Leoben, Franz Josef Strasse 18, 8700 Leoben (Austria); Hofer, F. [GFM GmbH, Ennser Strasse 14, 4403 Steyr (Austria)

2011-01-17

17

The effects of casting and forging processes on joint properties in friction-welded AISI 1050 and AISI 304 steels  

Microsoft Academic Search

The aim of the present study was to investigate the effects of investment casting and forging process on the microstructure\\u000a and mechanical properties of friction weldments, AISI 1050–AISI 304. A continuous-drive friction welding device with the automatic\\u000a control ability of friction time and forging pressure was designed and constructed. Factorial design of experiments was performed\\u000a to join investment cast AISI

Tolga Y. Sunay; Mumin Sahin; Sabri Altintas

2009-01-01

18

A review of radial forging technology including preform design for process optimization  

NASA Astrophysics Data System (ADS)

The Engineering Research Center for Net Shape Manufacturing (located at Ohio State University, Columbus, Ohio) was contracted by Benet Laboratories to investigate the rotary forging operation at Watervliet Arsenal. They were asked to make recommendations on how to optimize the shape and size of the starting material (preform) prior to forging which would reduce or eliminate variations in mechanical properties along the length of the resulting forging. Based on the data supplied by Benet Laboratories, the study resulted in recommendation of a two-step preform design. This was a preliminary recommendation and further testing was suggested to separate the effects of forging reduction from post-forging heat treatment.

Domblesky, Joseph P.; Shivpuri, Rajiv; Altan, Taylan

1994-02-01

19

Consolidation of nanostructured metal powders by rapid forging: Processing, modeling, and subsequent mechanical behavior  

NASA Astrophysics Data System (ADS)

Fe-10Cu powders containing 20-nm grains were produced by attritor milling of elemental powders in argon. A rapid powder forging technique was developed to consolidate the powders into fully dense compacts while maintaining nanoscale grain sizes. Grain growth during the consolidation was controlled by reducing the time of exposure at elevated temperature to a few minutes or less, a technique which is applicable to all materials and does not necessitate the addition of dispersoids. This was achieved by heating green compacts quickly using an induction heater, and then forging and rapidly cooling them back to room temperature. Forging was conducted in a protective argon atmosphere to limit contamination. Fully dense compacts were produced at relatively low temperatures, mainly due to the accelerated creep rates exhibited by the nanostructures. Transmission electron microscopy and X-ray diffraction analysis found an average grain size of 45 nm in the fully dense samples forged at 530°C. Indications are that finer grain sizes should be attainable by using slightly lower temperatures and higher pressures. The success of the technique (compared to hot-isostatic pressing (“hipping”)) is due to both reducing time at elevated temperatures and applying relatively high pressures. Microhardness tests revealed a significant strengthening effect due to grain size refinement, following a Hall-Petch relation. Compression testing at room temperature showed no strain hardening during plastic deformation, which occurred by shear banding. High strengths, up to 1800 MPa, were obtained at room temperature. Compression testing at 575°C revealed a significant strain rate dependence of mechanical behavior and also the possibility of superplastic behavior. Power-law creep was observed at 575°C, with very high steady-state creep rates on the order of 50 pct/s at 230 MPa. The consolidation process was successfully modeled by slightly modifying and applying the Arzt, Ashby, and Easterling (AAE) hot-isostatic press (HIP) model. The experiments and modeling indicated that creep was the dominant densification mechanism in these materials, even at relatively low temperatures and high loading rates. The results of this investigation suggest the possibility of a commercially viable nanostructured metal, which is easily processed to large strains at moderate temperatures, yet maintains high strength at room temperature without the necessity of heat treatment or mechanical working.

Shaik, G. R.; Milligan, W. W.

1997-03-01

20

Processing and development of aluminum-silicon powder metallurgy alloys for hot forging technologies  

NASA Astrophysics Data System (ADS)

The growing field of aluminum powder metallurgy (PM) brings promise to an economical and environmental demand for the production of high strength, light weight aluminum engine components. To tackle the limited selection of readily available light alloy blends, an experimental hypoeutectic AlSi alloy was chosen for study. The optimal processing route for this alloy was determined and the mechanical properties were examined. In an effort to further enhance the mechanical properties of the alloys, post sinter forging was investigated. This body of work consists of an introduction to relevant topics in PM, aluminum alloys, and forging followed by three sections of results and discussion. Each represents an accepted or submitted Journal Manuscript intended for journal publication. These sections deliver detailed experimental procedures, results and discussion for the development of the experimental PM alloy Al-65i, a comparison of hot deformation behaviours of Al-65i and Alumix-231 Al5i PM alloys, and their mechanical properties observed upon hot densification. A final section was added to summarize the important findings from each experiment. In the development of Al-65i, the alloy was able to achieve a high sintered density approaching 98%, and a yield strength of 232 MPa in the T6 condition. Upon hot upset forging, the experimental alloy achieved an average density of 99.6% (+/- 0.2%) while the commercial alloy (Alumix-231) achieved 98.3% (+/- 0.6%) of its theoretical density. It was found that the experimentally obtained peak flow stresses for each material studied could be very closely approximated using the semi-empirical Zener-Hollomon models. Upon hot densification it was found that all the mechanical properties of the Al-65i alloy were significantly enhanced. However, due to the fracturing of 5i particles during deformation, Alumix-231 experienced a reduction in density and UT5, while making improvements in ductility.

Mosher, Winston G. E.

21

Development of Replacements for Phoscoating Used in Forging, Extrusion and Metal Forming Processes  

SciTech Connect

Many forging, extrusion, heading and other metal forming processes use graphite-based lubricants, phosphate coatings, and other potentially hazardous or harmful substances to improve the tribology of the metal forming process. The application of phosphate-based coatings has long been studied to determine if other synthetic ''clean'' lubricants could provide the same degree of protection afforded by phoscoatings and its formulations. So far, none meets the cost and performance objectives provided by phoscoatings as a general aid to the metal forming industry. In as much as phoscoatings and graphite have replaced lead-based lubricants, the metal forming industry has had previous experience with a legislated requirement to change processes. However, without a proactive approach to phoscoating replacement, many metal forming processes could find themselves without a cost effective tribology material necessary for the metal forming process

Kerry Barnett

2003-03-01

22

Advanced numerical models for the thermo-mechanical-metallurgical analysis in hot forging processes  

NASA Astrophysics Data System (ADS)

In the paper a literature review of the numerical modeling of thermo-mechanical-metallurgical evolutions of a metal in hot forging operations is presented. In particular models of multiaxial loading tests are considered for carbon steels. The collected examples from literature regard phases transformations, also martensitic transformations, morphologies evolutions and transformation plasticity phenomena. The purpose of the tests is to show the correlation between the mechanical and the metallurgical behavior of a carbon steel during a combination of several types of loads. In particular a few mechanical tests with heat treatment are analyzed. Furthermore, Ti-6Al-4V titanium alloy is considered. Such material is a multi-phasic alloy, at room temperature made of two main different phases, namely Alpha and Beta, which evolve during both cooling and heating stages. Several numerical applications, conducted using a commercial implicit lagrangian FEM code are presented too. This code can conduct tri-coupled thermo-mechanical-metallurgical simulations of forming processes. The numerical model has been used to carry out a 3D simulation of a forging process of a complex shape part. The model is able to take into account the effects of all the phenomena resulting from the coupling of thermal, mechanical and metallurgical events. As simulation results strongly depend on the accuracy of input data, physical simulation experiments on real-material samples are carried out to characterize material behavior during phase transformation.

Ducato, Antonino; Fratini, Livan; Micari, Fabrizio

2013-05-01

23

Influence of minimum quantity lubrication parameters on tool wear and surface roughness in milling of forged steel  

NASA Astrophysics Data System (ADS)

The minimum quantity of lubrication (MQL) technique is becoming increasingly more popular due to the safety of environment. Moreover, MQL technique not only leads to economical benefits by way of saving lubricant costs but also presents better machinability. However, the effect of MQL parameters on machining is still not clear, which needs to be overcome. In this paper, the effect of different modes of lubrication, i.e., conventional way using flushing, dry cutting and using the minimum quantity lubrication (MQL) technique on the machinability in end milling of a forged steel (50CrMnMo), is investigated. The influence of MQL parameters on tool wear and surface roughness is also discussed. MQL parameters include nozzle direction in relation to feed direction, nozzle elevation angle, distance from the nozzle tip to the cutting zone, lubricant flow rate and air pressure. The investigation results show that MQL technique lowers the tool wear and surface roughness values compared with that of conventional flood cutting fluid supply and dry cutting conditions. Based on the investigations of chip morphology and color, MQL technique reduces the cutting temperature to some extent. The relative nozzle-feed position at 120°, the angle elevation of 60° and distance from nozzle tip to cutting zone at 20 mm provide the prolonged tool life and reduced surface roughness values. This fact is due to the oil mists can penetrate in the inner zones of the tool edges in a very efficient way. Improvement in tool life and surface finish could be achieved utilizing higher oil flow rate and higher compressed air pressure. Moreover, oil flow rate increased from 43.8 mL/h to 58.4 mL/h leads to a small decrease of flank wear, but it is not very significant. The results obtained in this paper can be used to determine optimal conditions for milling of forged steel under MQL conditions.

Yan, Lutao; Yuan, Songmei; Liu, Qiang

2012-05-01

24

Forging; Heat Treating and Testing; Technically Oriented Industrial Materials and Process 1: 5898.05.  

ERIC Educational Resources Information Center

The course provides students with advanced and exploratory experience in the area of plastic deformation of metals and in the changing of the physical characteristics of metals by the controlled application and timed removal of heat. Course content includes goals, specific objectives, safety in forge work, forging tools and equipment, industrial…

Dade County Public Schools, Miami, FL.

25

Efficient process design for closure and healing of voids in open die forging of superhigh C-steel shaft  

NASA Astrophysics Data System (ADS)

In this study, simulation and experimental works are carried out to propose the efficient forging process design for manufacturing workroll made of 1.5wt%C high carbon steel. New forging process design is composed of incremental upsetting, diffusion boding and cogging process for efficient void closure and healing. Since the voids lie along the longitudinal direction of the ingot, the ingot is gradually deformed only in its radial direction during incremental upsetting until void closure takes place. After that, the closed voids are healed by diffusion bonding process in order to assign the strong bonding strength to the closed void and to prevent the re-opening of the closed voids during successive incremental upsetting and cogging process. Experimental works are also carried out to validate the proposed forging process design. In addition, the effect of temperature of diffusion bonding on bonding strength of the closed void is investigated. Finally, the analyses on microstructure at the diffusion-bonded interface and mechanical properties by tensile test are carried out as well. It was found out through simulation and experimental works that the quick void closure takes place by incremental upsetting and the closed void is strongly joined by diffusion bonding. It was confirmed that the process design proposed in this study can be applicable to manufacture the super high carbon workroll with microstructurally soundness.

Kang, Seong-Hoon; Lim, Hyung-Cheol; Lee, Howon; Lee, Young-Seon

2013-05-01

26

Processing and properties of superclean ASTM A508 Cl. 4 forgings  

SciTech Connect

Steels with improved resistance to temper embrittlement are now being produced using ``superclean`` steelmaking technology. This technology involves the use of scrap control, proper electric arc furnace and ladle refining furnace practices to produce steel with very low Mn, Si, P, S and other residual impurities such as Sn, As and Sb. This technology has been applied on a production basis to modified ASTM A508 Cl- 4 material intended for high temperature pressure vessel forgings. Processing and properties of this superclean material are reviewed. In addition, the cleanliness and mechanical properties are compared to conventionally melted A508 Cl. 4 material. The ``superclean`` A508 Cl. 4 mod. was found to meet all specification requirements. In addition, the superclean material was found to possess superior upper shelf CVN properties, a lower FATT{sub 50} and NDTT, along with superior microcleanliness compared to conventional material. Finally, the superclean material was found to be immune to temper embrittlement based on the short-term embrittlement treatments examined.

Hinkel, A.V.; Handerhan, K.J. [Ellwood City Forge, PA (United States); Manzo, G.J. [Ellwood Group Inc., PA (United States). Steel Division; Simkins, G.P. [Westinghouse Electric Corp., Pittsburgh, PA (United States)

1988-12-31

27

Warm multiaxial forging of AISI 1016 steel  

Microsoft Academic Search

In this work, the microstructural evolution in AISI 1016 steel processed by using warm multiaxial forging technique is studied. With increase in multiaxial forging strain, a finer substructure evolved. Structural evolution in pearlite phase is addressed in detail considering the strain paths and strain rate. Pearlitic cementite fragmented into ultrafine particles of about 100–300nm size. Warm multiaxial forging process also

A. K. Padap; G. P. Chaudhari; V. Pancholi; S. K. Nath

2010-01-01

28

Effect of Forging Parameters on Low Cycle Fatigue Behaviour of Al/Basalt Short Fiber Metal Matrix Composites  

PubMed Central

This paper deals with metal matrix composites (MMCs) of Al 7075 alloy containing different weight percentage (2.5, 5, 7.5, and 10) basalt short fiber reinforcement and unreinforced matrix alloy. The samples were produced by the permanent stir casting technique. The casting ingots were cut into blanks to be forged in single stage and double stage, using MN press and graphite-based lubricant. The microstructures and fatigue properties of the matrix alloy and MMC samples were investigated in the as cast state and in the single and double stage forging operations. The microstructure results showed that the forged sample had a uniform distribution of the basalt short fiber throughout the specimens. Evaluation of the fatigue properties showed that the forged samples had higher values than those of the as cast counterparts. After forging, the enhancement of the fatigue strength of the matrix alloy was so significant and high in the case of 2.5 and 5.0?wt. percentage basalt short fiber reinforced MMC, and there was no enhancement in 7.5 and 10?weight percentages short fiber reinforced MMCs. The fracture damage was mainly due to decohesion at the matrix-fiber interface. PMID:24298207

Karthigeyan, R.; Ranganath, G.

2013-01-01

29

New Trends in Forging Technologies  

NASA Astrophysics Data System (ADS)

Limited natural resources increase the demand on highly efficient machinery and transportation means. New energy-saving mobility concepts call for design optimisation through downsizing of components and choice of corrosion resistant materials possessing high strength to density ratios. Component downsizing can be performed either by constructive structural optimisation or by substituting heavy materials with lighter high-strength ones. In this context, forging plays an important role in manufacturing load-optimised structural components. At the Institute of Metal Forming and Metal-Forming Machines (IFUM) various innovative forging technologies have been developed. With regard to structural optimisation, different strategies for localised reinforcement of components were investigated. Locally induced strain hardening by means of cold forging under a superimposed hydrostatic pressure could be realised. In addition, controlled martensitic zones could be created through forming induced phase conversion in metastable austenitic steels. Other research focused on the replacement of heavy steel parts with high-strength nonferrous alloys or hybrid material compounds. Several forging processes of magnesium, aluminium and titanium alloys for different aeronautical and automotive applications were developed. The whole process chain from material characterisation via simulation-based process design to the production of the parts has been considered. The feasibility of forging complex shaped geometries using these alloys was confirmed. In spite of the difficulties encountered due to machine noise and high temperature, acoustic emission (AE) technique has been successfully applied for online monitoring of forging defects. New AE analysis algorithm has been developed, so that different signal patterns due to various events such as product/die cracking or die wear could be detected and classified. Further, the feasibility of the mentioned forging technologies was proven by means of the finite element analysis (FEA). For example, the integrity of forging dies with respect to crack initiation due to thermo-mechanical fatigue as well as the ductile damage of forgings was investigated with the help of cumulative damage models. In this paper some of the mentioned approaches are described.

Behrens, B.-A.; Hagen, T.; Knigge, J.; Elgaly, I.; Hadifi, T.; Bouguecha, A.

2011-05-01

30

Mechanical Properties and Microstructure of Thin Plates of A6061 Wrought Aluminum Alloy Using Rheology Forging Process with Electromagnetic Stirring  

NASA Astrophysics Data System (ADS)

We propose the possibility of fabricating A6061 thin plates using the rheology forging process. Electromagnetic stirring (EMS) is used to fabricate a semi-solid slurry. A thin plate is formed by injecting the slurry into the forging die. When the punch speed used to compress the slurry is low, turbulent flow occurs. When the punch speed is high, laminar flow occurs, and the solid and liquid phases move simultaneously. For a pressure of 150 MPa or below, incomplete filling behavior and cracks occur. For a pressure of 200 MPa or above, a durable formed product can be obtained. However, the differences between the mechanical properties according to the application of EMS and pressure are slight. The microstructure of the slurry without EMS has an unclear distinction between the liquid phase and solid phase. However, the microstructure of the thin plates formed by using this slurry has a clear distinction between the liquid and solid with respect to the spheroid shapes. The tensile strength and elongation for a thin plate formed with a punch speed of 300 mm/s and pressure of 250 MPa with EMS slurry are 169 MPa and 11.0 pct, respectively. After T6 heat treatment, the tensile strength improves to 305 MPa.

Jin, Chul Kyu; Bolouri, Amir; Kang, Chung Gil

2014-06-01

31

On Extrusion Forging and Extrusion Rolling of Thin Metal Sheets  

E-print Network

Sheet metal surfaces with pin-fin features have potential fluid and thermal applications. Extrusion forging process and extrusion rolling process can be used to create such surface features on sheet metals. Extrusion forging process is a metal...

Feng, Zhujian

2013-01-10

32

Thermomechanical processing of microalloyed powder forged steels and a cast vanadium steel  

NASA Astrophysics Data System (ADS)

The effects of controlled rolling on transformation behavior of two powder forged (P/F) microalloyed vanadium steels and a cast microalloyed vanadium steel were investigated. Rolling was carried out in the austenitic range below the recrystallization temperature. Equiaxed grain structures were produced in specimens subjected to different reductions and different cooling rates. The ferrite grain size decreased with increasing deformation and cooling rate. Ferrite nucleated on second phase particles, deformation bands, and on elongated prior austenite grain boundaries; consequently a high fractional ferrite refinement was achieved. Deformation raised the ferrite transformation start temperature while the time to transformation from the roll finish temperature decreased. Cooling rates in the cast steel were higher than in P/F steels for all four cooling media used, and the transformation start temperatures of cast steels were lower than that of P/F steel. Intragranular ferrite nucleation, which played a vital role in grain refinement, increased with cooling rate. Fully bainitic microstructures were formed at higher cooling rates in the cast steel. In the P/F steels inclusions and incompletely closed pores served as sites for ferrite nucleation, often forming a ‘secondary’ ferrite. The rolling schedule reduced the size of large pores and particle surface inclusions and removed interconnected porosity in the P/F steels.

Dogan, B.; Davies, T. J.

1985-09-01

33

Design for Forging.  

National Technical Information Service (NTIS)

Factors that affect the cost of hot impression die forging and information regarding economical design of forged parts for this method of forming are outlined and discussed. Specific technical information regarding shape, temperatures, materials, and dime...

R. Connolly, C. Poli, G. Boothroyd

1979-01-01

34

Simple three-dimensional laser radar measuring method and model reconstruction for hot heavy forgings  

NASA Astrophysics Data System (ADS)

Dimensional measurement of hot heavy forgings is desirable to permit real-time process control, but usually it is inconvenient because of the difficulty in working with very hot workpieces. We present a new three dimensional (3D) measuring approach based on a two-dimensional laser range sensor (TLRS). First, the measurement system is obtained by assembling a TLRS, an axis of rotation, and a servo motor, which rotates the scan plane of the laser ranger sensor and lets the TLRS scan forgings in different planes. Therefore, the coordinates of forging surface points can be obtained in a sensor coordinate system (SCS). According to the transformation matrix between the SCS and measurement coordinate system (MCS), coordinates of points in different SCSs can be transferred into one fixed MCS. Hence the actual 3D models of hot heavy forgings can be reconstructed by using a triangulated irregular network and be optimized by employing improved Delaunay rules. Different parameters of forgings, such as lengths and diameters, can be measured based on the 3D model. The new method is verified by experiments in both the laboratory and the forging workshop. The experimental results indicate that it is much more practical and convenient for the real-time, onsite measurement of hot heavy forgings.

Du, Zhengchun; Du, Yueyang

2012-02-01

35

Forging of Advanced Disk Alloy LSHR  

NASA Technical Reports Server (NTRS)

The powder metallurgy disk alloy LSHR was designed with a relatively low gamma precipitate solvus temperature and high refractory element content to allow versatile heat treatment processing combined with high tensile, creep and fatigue properties. Grain size can be chiefly controlled through proper selection of solution heat treatment temperatures relative to the gamma precipitate solvus temperature. However, forging process conditions can also significantly influence solution heat treatment-grain size response. Therefore, it is necessary to understand the relationships between forging process conditions and the eventual grain size of solution heat treated material. A series of forging experiments were performed with subsequent subsolvus and supersolvus heat treatments, in search of suitable forging conditions for producing uniform fine grain and coarse grain microstructures. Subsolvus, supersolvus, and combined subsolvus plus supersolvus heat treatments were then applied. Forging and subsequent heat treatment conditions were identified allowing uniform fine and coarse grain microstructures.

Gabb, Timothy P.; Gayda, John; Falsey, John

2005-01-01

36

Simulation of 7050 Wrought Aluminum Alloy Wheel Die Forging and its Defects Analysis based on DEFORM  

SciTech Connect

Defects such as folding, intercrystalline cracking and flow lines outcrop are very likely to occur in the forging of aluminum alloy. Moreover, it is difficult to achieve the optimal set of process parameters just by trial and error within an industrial environment. In producing 7050 wrought aluminum alloy wheel, a rigid-plastic finite element method (FEM) analysis has been performed to optimize die forging process. Processing parameters were analyzed, focusing on the effects of punch speed, friction factor and temperature. Meanwhile, mechanism as well as the evolution with respect to the defects of the wrought wheel was studied in details. From an analysis of the results, isothermal die forging was proposed for producing 7050 aluminum alloy wheel with good mechanical properties. Finally, verification experiment was carried out on hydropress.

Huang Shiquan; Yi Youping; Zhang Yuxun [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China)

2010-06-15

37

Phased Array Ultrasonic Inspection of Titanium Forgings  

NASA Astrophysics Data System (ADS)

Aerospace forging inspections typically use multiple, subsurface-focused sound beams in combination with digital C-scan image acquisition and display. Traditionally, forging inspections have been implemented using multiple single element, fixed focused transducers. Recent advances in phased array technology have made it possible to perform an equivalent inspection using a single phased array transducer. General Electric has developed a system to perform titanium forging inspection based on medical phased array technology and advanced image processing techniques. The components of that system and system performance for titanium inspection will be discussed.

Howard, P.; Klaassen, R.; Kurkcu, N.; Barshinger, J.; Chalek, C.; Nieters, E.; Sun, Zongqi; deFromont, F.

2007-03-01

38

Superplastic forging nitride ceramics  

DOEpatents

A process is disclosed for preparing silicon nitride ceramic parts which are relatively flaw free and which need little or no machining, said process comprising the steps of: (a) preparing a starting powder by wet or dry mixing ingredients comprising by weight from about 70% to about 99% silicon nitride, from about 1% to about 30% of liquid phase forming additive and from 1% to about 7% free silicon; (b) cold pressing to obtain a preform of green density ranging from about 30% to about 75% of theoretical density; (c) sintering at atmospheric pressure in a nitrogen atmosphere at a temperature ranging from about 1,400 C to about 2,200 C to obtain a density which ranges from about 50% to about 100% of theoretical density and which is higher than said preform green density, and (d) press forging workpiece resulting from step (c) by isothermally uniaxially pressing said workpiece in an open die without initial contact between said workpiece and die wall perpendicular to the direction of pressing and so that pressed workpiece does not contact die wall perpendicular to the direction of pressing, to substantially final shape in a nitrogen atmosphere utilizing a temperature within the range of from about 1,400 C to essentially 1,750 C and strain rate within the range of about 10[sup [minus]7] to about 10[sup [minus]1] seconds[sup [minus]1], the temperature and strain rate being such that surface cracks do not occur, said pressing being carried out to obtain a shear deformation greater than 30% whereby superplastic forging is effected.

Panda, P.C.; Seydel, E.R.; Raj, R.

1988-03-22

39

Enhancement of Aluminum Alloy Forgings through Rapid Billet Heating  

SciTech Connect

Forging is a manufacturing process in which metal is pressed, pounded or squeezed under great pressure and, often, under high strain rates into high-strength parts known as forgings. The process is typically performed hot by preheating the metal to a desired temperature before it is worked. The forging process can create parts that are stronger than those manufactured by any other metal working process. Forgings are almost always used where reliability and human safety are critical. Forgings are normally component parts contained inside assembled items such airplanes, automobiles, tractors, ships, oil drilling equipment, engines missiles, and all kinds of capital equipment Forgings are stronger than castings and surpass them in predictable strength properties, producing superior strength that is assured, part to part.

Kervick, R.; Blue, C. A.; Kadolkar, P. B.; Ando, T.; Lu, H.; Nakazawa, K.; Mayer, H.; Mochnal, G.

2006-06-01

40

31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. FORGE, ANVIL, POWER FORGE HAMMER (FRONT TO BACK), AND DOORWAY INTO MAIN SHOP-LOOKING SOUTHWEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

41

Electrical heating of forging billets. Final report  

SciTech Connect

Recent and ongoing research concerned with homopolar generators operated in a pulse mode and making use of kinetic energy storage principles has led to the application of these techniques to forging billet heating. Most forging billet heating is done using fuel-fired furnaces, but use of electric induction heating is increasing. The homopolar pulse billet heating (HPBH) process is described and its capabilities are evaluated relative to furnace and induction heating. Conclusions are that applications for this new process will most likely be in the heating of stainless steel and superalloy billets, particularly if present research efforts are successful in reducing costs.

Keith, R.E.; Weldon, W.F.

1982-11-01

42

Technological study of liquid die forging for the aluminum alloy connecting rod of an air compressor  

Microsoft Academic Search

The aluminum alloy connecting rod of an air compressor was manufactured with liquid die forging replacing die casting and hot die forging. Not only were the defects of gas holes, porosity and non-metal inclusions in the die casting eliminated, but also the investment of the forging equipment and the performing process were decreased, and the coefficient of material utilization and

F. Yin; G. X. Wang; S. Z. Hong; Z. P. Zeng

2003-01-01

43

Parameter estimation of power law process  

SciTech Connect

Power law process is an important model in reliability analysis of engineering systems experiencing reliability growth or decay. Existing articles mainly deal with the estimation of the shape parameter. The estimation of the scale parameter is either ignored or dealt with very inefficiently. In this article, we are going to explain why those methods can estimate the shape parameter well, but fail to estimate the scale parameter effectively. It is still open problem if we can obtain an estimate to the scale parameter as good as the one to the shape parameter. We try to explore a new way to improve the estimate of the scale parameter. which will be proven better than the existing methods in theory and practice.

Qiao, H. [Fort Valley State Univ., Fort Valley, GA (United States); Tsokos, C.P. [Univ. of South Florida, Tampa, FL (United States)

1994-12-31

44

Relay based estimation of process model parameters  

Microsoft Academic Search

A set of general expressions is derived from a single symmetrical relay feedback test for estimation of model parameters of lower-order processes. Using the expressions the exact parameters of open loop stable and unstable first order plus time delay (FOPDT) and second order plus time delay (SOPDT) transfer function models may be obtained from simple measurements made on the limit

Somanath Majhi; Lothar Litz

2003-01-01

45

Superplastic forging nitride ceramics  

DOEpatents

The invention relates to producing relatively flaw free silicon nitride ceramic shapes requiring little or no machining by superplastic forging This invention herein was made in part under Department of Energy Grant DE-AC01-84ER80167, creating certain rights in the United States Government. The invention was also made in part under New York State Science and Technology Grant SB1R 1985-10.

Panda, Prakash C. (Ithaca, NY); Seydel, Edgar R. (Ithaca, NY); Raj, Rishi (Ithaca, NY)

1988-03-22

46

Surveillance of industrial processes with correlated parameters  

DOEpatents

A system and method for surveillance of an industrial process. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions.

White, Andrew M. (Skokie, IL); Gross, Kenny C. (Bolingbrook, IL); Kubic, William L. (Sante Fe, NM); Wigeland, Roald A. (Olympia Fields, IL)

1996-01-01

47

Surveillance of industrial processes with correlated parameters  

DOEpatents

A system and method for surveillance of an industrial process are disclosed. The system and method includes a plurality of sensors monitoring industrial process parameters, devices to convert the sensed data to computer compatible information and a computer which executes computer software directed to analyzing the sensor data to discern statistically reliable alarm conditions. The computer software is executed to remove serial correlation information and then calculate Mahalanobis distribution data to carry out a probability ratio test to determine alarm conditions. 10 figs.

White, A.M.; Gross, K.C.; Kubic, W.L.; Wigeland, R.A.

1996-12-17

48

Computer-Aided Design of Manufacturing Chain Based on Closed Die Forging for Hardly Deformable Cu-Based Alloys  

NASA Astrophysics Data System (ADS)

Two copper-based alloys were considered, Cu-1 pct Cr and Cu-0.7 pct Cr-1 pct Si-2 pct Ni. The thermal, electrical, and mechanical properties of these alloys are given in the paper and compared to pure copper and steel. The role of aging and precipitation kinetics in hardening of the alloys is discussed based upon the developed model. Results of plastometric tests performed at various temperatures and various strain rates are presented. The effect of the initial microstructure on the flow stress was investigated. Rheologic models for the alloys were developed. A finite element (FE) model based on the Norton-Hoff visco-plastic flow rule was applied to the simulation of forging of the alloys. Analysis of the die wear for various processes of hot and cold forging is presented as well. A microstructure evolution model was implemented into the FE code, and the microstructure and mechanical properties of final products were predicted. Various variants of the manufacturing cycles were considered. These include different preheating schedules, hot forging, cold forging, and aging. All variants were simulated using the FE method and loads, die filling, tool wear, and mechanical properties of products were predicted. Three variants giving the best combination of forging parameters were selected and industrial trials were performed. The best manufacturing technology for the copper-based alloys is proposed.

Pietrzyk, Maciej; Kuziak, Roman; Pidvysots'kyy, Valeriy; Nowak, Jaros?aw; W?glarczyk, Stanis?aw; Drozdowski, Krzysztof

2013-07-01

49

The occurrence of shear bands in nonisothermal, hot forging of Ti-6AI-2Sn-4Zr-2Mo-0.1Si  

NASA Astrophysics Data System (ADS)

The occurrence of shear bands in nonisothermal, hot forging of Ti-6Al-2Sn-4Zr-2Mo-0. ISi (Ti-6242) was investigated in order to establish the material properties and process parameters which generally lead to shear bands and shear cracks in conventional hot forging of metals. Upset compression tests on cylindrical samples and lateral sidepressing tests on long, round bars were performed to determine the modes by which flow localizes in deformation states ranging from axisymmetric to plane strain. In axisymmetric deformation, it was found that nonisothermal, hot compression leads to chill zones and bands of intense deformation separating the chill zones from the deforming bulk. For plane strain deformation, shear bands were found to initiate along zero extension directions and subsequently localize flow in a manner analogous to the formation and propagation of shear bands in isothermal, hot forging. For both deformation states, it was found that material properties, such as the flow stress dependence on temperature, and process parameters, such as forging speed and die temperature which strongly influence the amount of heat transfer, play critical roles in the flow localization process. A simple model quantifying these effects was developed to predict the occurrence and severity of the shear bands observed in the Ti-6242 alloy hot forged at various temperatures and rates. In addition, the occurrence of shear cracking under certain forging conditions was rationalized in terms of the chilling brought about by nonisothermal, hot forging conditions and the inferior workability of Ti-6242 at temperatures far below the transus temperature.

Semiatin, S. L.; Lahoti, G. D.

1983-01-01

50

Effects of process parameters on hydrothermal carbonization  

NASA Astrophysics Data System (ADS)

In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

Uddin, Md. Helal

51

Nonstationary magnetotelluric data processing with instantaneous parameter  

NASA Astrophysics Data System (ADS)

Nonstationarity in electromagnetic data affects the computation of Fourier spectra and therefore the traditional estimation of the magnetotelluric (MT) transfer functions (TF). We provide a TF estimation scheme based on an emerging nonlinear, nonstationary time series analysis tool, called empirical mode decomposition (EMD) and show that this technique can handle nonstationary effects with which traditional methods encounter difficulties. In contrast to previous works that employ EMD for MT data processing, we argue the advantages of a multivariate decomposition, highlight the possibility to use instantaneous parameters, and define the homogenization of frequency discrepancies between data channels. Our scheme uses the robust statistical estimation of transfer functions based on robust principal component analysis and a robust iteratively reweighted least squares regression with a Huber weight function. The scheme can be applied with and without aid of any number of available remote reference stations. Uncertainties are estimated by iterating the complete robust regression, including the robust weight computation, with a bootstrap routine. We apply our scheme to synthetic and real data (Southern Africa) with and without nonstationary character and compare different processing techniques to the one presented here. As a conclusion, nonstationary noise can heavily affect Fourier-based MT data processing but the presented nonstationary approach is nonetheless able to extract the impedances.

Neukirch, M.; Garcia, X.

2014-03-01

52

Forgeability of Mg–Al–Zn magnesium alloys in hot and warm closed die forging  

Microsoft Academic Search

The paper presents an investigation on the effect of process variables and material condition on forgeability of magnesium wrought alloys of Mg–Al–Zn group, AZ31 and AZ61. The experimental work includes studies of forging capabilities of the alloys in closed-die forging at hot and warm-working temperatures. Forging tests were performed for material both in as-cast and as-worked condition, for two variants

P. Skubisz; J. Si?czak; S. Bednarek

2006-01-01

53

Parameters estimation applied to automatic video processing algorithms validation  

Microsoft Academic Search

An automatic and systematic method to estimate parameters and to validate implementations of video processing algorithms is presented. Correctly adjusting video processing parameters can have a significant impact on the algorithm performance and behavior. Since video processing algorithm parameters are often determined empirically, a new method to automatically estimate parameters is proposed. The method takes advantage of an automatic word

Serge Catudal; Marc-andré Cantin; Yvon Savaria

2005-01-01

54

Prediction of Microstructure in High-Strength Ductile Forging Parts  

SciTech Connect

Governmental, environmental and economic demands call for lighter, stiffer and at the same time cheaper products in the vehicle industry. Especially safety relevant parts have to be stiff and at the same time ductile. The strategy of this project was to improve the mechanical properties of forging steel alloys by employing a high-strength and ductile bainitic microstructure in the parts while maintaining cost effective process chains to reach these goals for high stressed forged parts. Therefore, a new steel alloy combined with an optimized process chain has been developed. To optimize the process chain with a minimum of expensive experiments, a numerical approach was developed to predict the microstructure of the steel alloy after the process chain based on FEM simulations of the forging and cooling combined with deformation-time-temperature-transformation-diagrams.

Urban, M.; Back, A.; Hirt, G. [Institute of Metal Forming (IBF), RWTH Aachen University, Aachen (Germany); Keul, C.; Bleck, W. [Institute of Ferrous Metallurgy (IEHK), RWTH Aachen University, Aachen (Germany)

2010-06-15

55

Prediction of Microstructure in High-Strength Ductile Forging Parts  

NASA Astrophysics Data System (ADS)

Governmental, environmental and economic demands call for lighter, stiffer and at the same time cheaper products in the vehicle industry. Especially safety relevant parts have to be stiff and at the same time ductile. The strategy of this project was to improve the mechanical properties of forging steel alloys by employing a high-strength and ductile bainitic microstructure in the parts while maintaining cost effective process chains to reach these goals for high stressed forged parts. Therefore, a new steel alloy combined with an optimized process chain has been developed. To optimize the process chain with a minimum of expensive experiments, a numerical approach was developed to predict the microstructure of the steel alloy after the process chain based on FEM simulations of the forging and cooling combined with deformation-time-temperature-transformation-diagrams.

Urban, M.; Keul, C.; Back, A.; Bleck, W.; Hirt, G.

2010-06-01

56

Heat Recovery in the Forge Industry  

E-print Network

Department of Energy figures reveal that in 1979 the forging and stamping operations were the primary consumers of energy (27%) within the 'Fabricated Metals Products Industry' (SIC 34). Industrial furnaces utilized by the forging industry often...

Shingledecker, R. B.

1982-01-01

57

Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis  

SciTech Connect

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of the die service life can be achieved by the use of ceramic inserts. The integration of ceramics into the die base plate made of hot-work steel is realised by active brazing, whereby it possible to apply ceramic in region with high wear. It has to be ensured in the design process of ceramic inserts for forging dies that no critical tensile stresses occur in the ceramics. A reliable design of the ceramic inserts is possible only through consideration of brazing and forming process. The development of a Finite-Element-model for the design of forging dies with ceramic inserts is the intention of the work presented in this paper. At first the forging process with a conventional die is analyzed concerning abrasive die wear to identify regions with high wear risk applying a modified Archard model. Based on the results of wear calculation, a forging die with ceramic inserts is investigated in terms of joint stresses at the end of the active brazing process. Subsequently, the forging process considering the residual stresses caused by joining is simulated in order to obtain the die stress in use.

Behrens, B.-A.; Schaefer, F.; Bistron, M. [Institute of Metal Forming and Metal-Forming Machines, Leibniz University of Hannover, An der Universitaet 2, 30823 Garbsen (Germany)

2007-05-17

58

Investigations on Forging Dies with Ceramic Inserts by means of Finite-Element-Analysis  

NASA Astrophysics Data System (ADS)

The tools in hot forging processes are exposed to high thermal and mechanical loadings. Tempering of the tool edge layer occurs as a result of thermal loadings. This leads to a gradual hardness loss of the tool material and increase of wear over forging cycles. Hence, the tool life in hot forging is mainly limited by wear. An extension of the die service life can be achieved by the use of ceramic inserts. The integration of ceramics into the die base plate made of hot-work steel is realised by active brazing, whereby it possible to apply ceramic in region with high wear. It has to be ensured in the design process of ceramic inserts for forging dies that no critical tensile stresses occur in the ceramics. A reliable design of the ceramic inserts is possible only through consideration of brazing and forming process. The development of a Finite-Element-model for the design of forging dies with ceramic inserts is the intention of the work presented in this paper. At first the forging process with a conventional die is analyzed concerning abrasive die wear to identify regions with high wear risk applying a modified Archard model. Based on the results of wear calculation, a forging die with ceramic inserts is investigated in terms of joint stresses at the end of the active brazing process. Subsequently, the forging process considering the residual stresses caused by joining is simulated in order to obtain the die stress in use.

Behrens, B.-A.; Schäfer, F.; Bistron, M.

2007-05-01

59

Advanced rotor forgings for high-temperature steam turbines. Volume 1. Ingot and forging production. Final report  

SciTech Connect

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the conventionally produced forgings, the advanced technology forgings show better tensile ductility and better uniformity along the radial and longitudinal directions. Charpy upper-shelf energy shows about 40% improvement, and no temper embrittlement was found using step-cooled and isothermal-aging treatments. Significant improvement in fracture toughness (K/sub IC/ and J/sub IC/) is realized for these forgings. Low-cycle fatigue life is better at high temperatures because of the absence of nonmetallic inclusions. Creep strength shows slight improvement. However, creep ductility is improved, probably because of low residual elements. The VCD forgings show excellent creep ductility, even with long lives. Both the toughness and creep properties are equal to or better than those of oil-quenched rotors produced by European practices. These improvements are attributed to cleaner steel, better control of ingot solidification, low residual elements (especially very low sulfur content), and the associated reduction of nonmetallic inclusions. These three rotors have been placed in service in three operating power plants in units rated at 520 MW each. Volume 1 of this report covers ingot and forging production, and volume 2 covers mechanical property evaluation.

Swaminathan, V.P.; Steiner, J.E.; Mitchell, A.

1986-05-01

60

Heat treatment of large-scale forgings at the Ural Heavy Machinery Factory  

Microsoft Academic Search

ion scheme dictate special features of the treatment of heavy-duty forgings, which are uncharacteristic for heat treatment of small articles. These factors, and also the presence of micro- and macroliquation, and the development of high compressive stresses in the center of heavy-duty forgings during the cooling process, which affect the phase transformations, make it impossible to compare the results of

P. V. Sklyuev; V. V. Kubachek; N. N. Aleksandrova

1983-01-01

61

Simulation of cold forging under consideration of residual stresses induced by preceding drawing  

NASA Astrophysics Data System (ADS)

Preforming steps may have a significant influence on the subsequent metal flow and damage behaviour in cold forging. Also the residual stress in the final part may be influenced by preforming operations. But, in numerical analyses of cold forging processes the preforming operations e.g. preceding drawing are most of the time neglected. Based on an exemplary cold forging process the present study shows the influence of a prior drawing process on the behavior of subsequent forging. For this purpose an elastic-plastic calculation is done using the commercial software Deform™. It is shown that considering a preceding drawing process has a significant influence on the computed material flow, damage behavior and die load during forging. Examination of the residual stress distribution after forging shows crucial deviations between the results obtained with or without preceding drawing. Further simulation studies show that after drawing there is also an influence of the forging direction related to the drawing direction on the simulation results. To verify the results obtained from the computations, forging trials are performed using primary material manufactured in a drawing operation.

Hatzenbichler, Thomas; Buchmayr, Bruno; Walzl, Alexander

2011-01-01

62

New steel for hot-forging dies  

Microsoft Academic Search

A new die steel of the 5KhNM type has been developed for hot deformation. The steel has better processing and service properties\\u000a than comparable steels used in forging. It has been proposed that the steel initially be produced at the Belarus Metallurgical\\u000a Plant. The new grade of steel will supplement Belarus-made die steels of types 45KhNMFYuTR(BIS1) and 45KhNMF1YuT(BIS2), which\\u000a were

A. B. Steblov; D. V. Lenartovich; E. I. Ponkratin

2006-01-01

63

Transatlantic Perspectives Forging Legitimizing Coalitions  

E-print Network

Transatlantic Perspectives Forging Legitimizing Coalitions: Comparing EU/U.S. Financial Consumer Policy | Tags: Economic & Financial Policy, History What is the role of non-state actors--corporate and civic--in influencing and redirecting regulatory reforms? How do critical junctures like financial

Boyer, Edmond

64

Forging............ Crowding.................... Lagging............ Heeling wide...............  

E-print Network

your dog, Leave your dog, Down, Sit, Call Dog Finish Exercise finished Forging............... Crowding Stand and Exam Glove # ______ Send your dog Take it Finish Exercise finished Forward Stand your dog (full exam) Call your dog to heel Exercise finished Displays fear or resentment

New Hampshire, University of

65

Recursive estimation of parameters in Markov-modulated Poisson processes  

Microsoft Academic Search

A hidden Markov regime is a Markov process that governs the time or space dependent distributions of an observed stochastic process. Recursive algorithms can be used to estimate parameters in mixed distributions governed by a Markov regime. The authors derive a recursive algorithm for estimation of parameters in a Markov-modulated Poisson process also called a Cox point process. By this

Georg Lindgren; U. Hoist

1995-01-01

66

Effect of processing parameters on autoclaved PMR polyimide composites  

NASA Technical Reports Server (NTRS)

A study was conducted to determine the effect of processing parameters on the processability and properties of autoclaved fiber reinforced PMR polyimide composites. Composites were fabricated from commercially available graphite fabric and glass fabric PMR polyimide prepreg materials. Process parameters investigated included degree of resin advancement, heating rate, and cure pressure. Composites were inspected for porosity by ultrasonic C scan and photomicrographic examination. Processing characteristics for each set of process parameters and the effect of process parameters on composite mechanical properties at room temperature and 600 F are described.

Vannucci, R. D.

1977-01-01

67

Measurement and Calculation of Parameters in the Silox Diffusion Process.  

National Technical Information Service (NTIS)

The parameters in the silox diffusion process were determined before and after diffusion. Sheet resistance, diffusion depth, surface concentration, and resistivity were determined for the fabrication of semiconductor devices. These parameters depend on th...

C. J. H. Heijnen, B. H. Vanroy

1983-01-01

68

Processing parameters affecting sorghum noodle qualities  

E-print Network

Processing variables of 100% sorghum noodles were investigated to determine effects on noodle quality. A dough was created by microwave heating a flour with 1 % salt (1 00 g): water (90 ml) mixture to 950C with a microwave. The dough was put through...

Kunetz, Christine Frances

2012-06-07

69

HYDROGEN-ASSISTED FRACTURE IN FORGED TYPE 304L AUSTENITIC STAINLESS STEEL  

SciTech Connect

Austenitic stainless steels generally have good resistance to hydrogen-assisted fracture; however, structural designs for high-pressure gaseous hydrogen are constrained by the low strength of this class of material. Forging is used to increase the low strength of austenitic stainless steels, thus improving the efficiency of structural designs. Hydrogen-assisted racture, however, depends on microstructural details associated with manufacturing. In this study, hydrogen-assisted fracture of forged type 304L austenitic stainless steel is investigated. Microstructural variation in multi-step forged 304L was achieved by forging at different rates and temperatures, and by process annealing. High internal hydrogen content in forged type 304L austenitic stainless steel is achieved by thermal precharging in gaseous hydrogen and results in as much as 50% reduction of tensile ductility.

Switzner, Nathan; Neidt, Ted; Hollenbeck, John; Knutson, J.; Everhart, Wes; Hanlin, R. [University of Missouri-Kansas City] [University of Missouri-Kansas City; Bergen, R. [Precision Metal Products] [Precision Metal Products; Balch, D. K. [Sandia Natl Laboratory] [Sandia Natl Laboratory

2012-09-06

70

Forging the Ideal Liberal LearningForging the Ideal Liberal Learning (Goals of Education)  

E-print Network

1 Forging the Ideal Liberal LearningForging the Ideal Liberal Learning (Goals of Education, Empathy, Courage) (Toward Global Sustainability) Language Education in the 21st Century Forging lectures in 2007 2 ICT (Collaborative Learning) Komaba Active Learning Studio=KALS #12;4 1 ALESS

Miyashita, Yasushi

71

Laser-dispersing of forging tools using AlN-ceramics  

NASA Astrophysics Data System (ADS)

Forging tools for aluminum work pieces show an increased adhesive wear due to cold welding during the forging process. Laser dispersing offers at this point a great potential to fabricate protective layers or tracks with tailored properties that reduce abrasive or adhesive wear at the surface of highly stressed components. Using different process strategies, four metal ceramic compounds applied on two substrate geometries were investigated regarding their structural and mechanical properties and their performance level. The subsequent forging tests have pointed out a positive effect and less adhesive residuals on the laser dispersed tool surface.

Noelke, C.; Luecke, M.; Kaierle, S.; Wesling, V.; Overmeyer, L.

2014-02-01

72

Investigation of laser and process parameters for Selective Laser Erosion  

Microsoft Academic Search

The process of Selective Laser Erosion (SLE) was investigated to study the effects of different process and laser parameters on the process outputs such as surface quality and erosion rate. The SLE process is a direct method to remove material in a layer-by-layer fashion due to high energy densities provided by the laser beam. In addition to its direct use

E. Yasa; J.-P. Kruth

2010-01-01

73

Deformation Mechanisms in Tube Billets from Zr-1%Nb Alloy under Radial Forging  

SciTech Connect

Features of the deformation process by cold radial forging of tube billets from Zr-1%Nb alloy were reconstructed on the basis of X-ray data concerning their structure and texture. The cold radial forging intensifies grain fragmentation in the bulk of billet and increases significantly the latent hardening of potentially active slip systems, so that operation only of the single slip system becomes possible. As a result, in radially-forged billets unusual deformation and recrystallization textures arise. These textures differ from usual textures of {alpha}-Zr by the mutual inversion of crystallographic axes, aligned along the axis of tube.

Perlovich, Yuriy; Isaenkova, Margarita; Fesenko, Vladimir; Krymskaya, Olga [National Research Nuclear University 'Moscow Engineering Physics Institute', Kashirskoe shosse, 31, Moscow, 115409 (Russian Federation); Zavodchikov, Alexander [Perm Research Technological Institute, Hasan Heroes street, 41, Perm, 614990 (Russian Federation)

2011-05-04

74

Effective Parameters in Axial Injection Suspension Plasma Spray Process  

E-print Network

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina; in revised form September 19, 2008) Suspension plasma spray (SPS) is a novel process for producing nano plasma spray (SPS) is an emerging process for spraying small feedstock particles with nano and/or a few

Medraj, Mamoun

75

Efficient moving horizon state and parameter estimation for SMB processes  

Microsoft Academic Search

In this paper, a moving horizon state and parameter estimation scheme for chromatographic simulated moving bed SMB processes is proposed. The simultaneous state and parameter estimation is based on a high-order nonlinear SMB model which incorporates rigorous models of the chromatographic columns and the discrete shiftings of the inlet and outlet ports. The estimation is performed using sparse measurement information:

Achim Küpper; Moritz Diehl; Johannes P. Schlöder; Hans Georg Bock; Sebastian Engell

2009-01-01

76

Effect of microwave processing on water soluble vitamins: Kinetic parameters  

Microsoft Academic Search

The effects of microwave processing on water soluble vitamins (ascorbic acid, niacin, thiamin, and riboflavin) were determined. The kinetic parameters of vitamin degradation reactions for microwave heating were determined for model vitamin systems. The degradation reactions were found to be first?order reactions. The kinetic parameters at different temperatures were also determined.

Zinet Aytanga Okmen; A. Levent Bayindirli

1999-01-01

77

Estimation of parameters in the fractional compound Poisson process  

NASA Astrophysics Data System (ADS)

This paper discusses method-of-moments estimators for parameters in the fractional compound Poisson process and establishes asymptotic normality of estimators. Simulation are presented to illustrate the properties of the estimators.

Wang, Ying; Wang, Dehui; Zhu, Fukang

2014-10-01

78

Effect of processing parameters on reaction bonding of silicon nitride  

NASA Technical Reports Server (NTRS)

Reaction bonded silicon nitride was developed. The relationship between the various processing parameters and the resulting microstructures was to design and synthesize reaction bonded materials with improved room temperature mechanical properties.

Richman, M. H.; Gregory, O. J.; Magida, M. B.

1980-01-01

79

Influence of processing parameters on the quality of soycurd (tofu)  

Microsoft Academic Search

Tofu, a non-fermented soybean curd is a nutritious and digestible product with a high quality protein. Tofu making procedure\\u000a includes soaking of beans, grinding, filtering, boiling, coagulating and moulding. The flavour, quality and the texture of\\u000a tofu produced is significantly influenced by its processing parameters. Studies were carried out on the processing parameters\\u000a like solid content of milk, thermal treatment

C. R. Rekha; G. Vijayalakshmi

80

Estimation of Clustering Parameters Using Gaussian Process Regression  

PubMed Central

We propose a method for estimating the clustering parameters in a Neyman-Scott Poisson process using Gaussian process regression. It is assumed that the underlying process has been observed within a number of quadrats, and from this sparse information the distribution is modelled as a Gaussian process. The clustering parameters are then estimated numerically by fitting to the covariance structure of the model. It is shown that the proposed method is resilient to any sampling regime. The method is applied to simulated two-dimensional clustered populations and the results are compared to a related method from the literature. PMID:25383766

Rigby, Paul; Pizarro, Oscar; Williams, Stefan B.

2014-01-01

81

FORGED PIECES FROM MAGNESIUM ALLOYS AND THEIR UTILIZATION IN AUTOMOTIVE INDUSTRY  

E-print Network

The paper presents an investigation on the effect of process variables and material condition on forgeability of magnesium wrought alloys of Mg-Al-Zn group, AZ31, AZ61 and AZ91. The experimental work includes studies of forging capabilities of the alloys in closed-die forging at hot and warm-working temperatures. Forging tests are performed for material both in as-cast and asworked condition, for two variants of workpiece geometry. The different variants of the workpiece indicated fracture-related problems in forging magnesium alloys in the warm-working temperature regime, which involved interaction between material condition and process variables, and state of stress. By means of numerical calculations it was concluded, that in addition to material condition, a favourable stale of stress, provided by a closed-die, can greatly improving the forgeability of magnesium alloys in the warm-working range.

Miroslav Greger; Radim Kocich; Vlastimil Karas

82

Hypotheses testing for a multidimensional parameter of inhomogeneous Poisson processes  

Microsoft Academic Search

We observe a realization of an inhomogeneous Poisson process whose intensity function depends on an unknown multidimensional parameter. We consider the asymptotic behaviour of the Rao score test for a simple null hypothesis against the multilateral alternative. By using the Edgeworth type expansion (under the null hypothesis) for a vector of stochastic integrals with respect to the Poisson process, we

Kh. Fazli

2008-01-01

83

Determination of SATI Instrument Filter Parameters by Processing Interference Images  

Microsoft Academic Search

This paper presents a method for determination of interference filter parameters such as the effective refraction index and the maximal transmittance wavelength on the basis of image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager instrument by means of data processing. The method employs the radial sections for determination of points from the crests and valleys in the

Atanas Marinov Atanassov

2010-01-01

84

Strength computation of forged parts taking into account strain hardening and damage  

NASA Astrophysics Data System (ADS)

Modern non-linear simulation software, such as FORGE 3 (registered trade mark of TRANSVALOR), are able to compute the residual stresses, the strain hardening and the damage during the forging process. A thermally dependent elasto-visco-plastic law is used to simulate the behavior of the material of the hot forged piece. A modified Lemaitre law coupled with elasticiy, plasticity and thermic is used to simulate the damage. After the simulation of the different steps of the forging process, the part is cooled and then virtually machined, in order to obtain the finished part. An elastic computation is then performed to equilibrate the residual stresses, so that we obtain the true geometry of the finished part after machining. The response of the part to the loadings it will sustain during it's life is then computed, taking into account the residual stresses, the strain hardening and the damage that occur during forging. This process is illustrated by the forging, virtual machining and stress analysis of an aluminium wheel hub.

Cristescu, Michel L.

2004-06-01

85

Sensitivity analysis for process parameters influencing weld quality in robotic GMA welding process  

Microsoft Academic Search

Generally, the quality of a weld joint is strongly influenced by process parameters during the welding process. In order to achieve high quality welds, mathematical models that can predict the bead geometry to accomplish the desired mechanical properties of the weldment should be developed. This paper focuses on development of mathematical models for the selection of process parameters and the

I. S. Kim; Y. J. Jeong; I. J. Son; I. J. Kim; J. Y. Kim; I. K. Kim; Prasad K. D. V. Yaragada

2003-01-01

86

Weak approximation of the Wiener process from a Poisson process: the multidimensional parameter set case  

Microsoft Academic Search

We give an approximation in law of the d-parameter Wiener process by processes constructed from a Poisson process with parameter in Rd. This approximation is an extension of previous results of Stroock (1982, Topics in Stochastic Differential Equations, Springer, Berlin) and Bardina and Jolis (2000, Bernoulli 4 (6)).

Xavier Bardina; Maria Jolis; Carles Rovira

2000-01-01

87

Effects of vacuum plasma spray processing parameters on splat morphology  

Microsoft Academic Search

Several statistical tools (i.e., Gaussian and Weibull distribution analyses, the t-test, and analysis of the variance) were\\u000a used to examine relationships between vacuum plasma spray processing parameters and the morphology of flattened particles\\u000a (splats) on a smooth, polished substrate. Astroloy, a nickel-base powder, was vacuum plasma sprayed onto polished copper substrates\\u000a under various processing conditions. Different flattened particle shape factors,

G. Montavon; S. Sampath; C. C. Berndt; H. Herman; C. Coddet

1995-01-01

88

Development of the technonological process and investigation of the quality of forged-and-welded turbine rotors made on steel 25Kh2NMFA  

Microsoft Academic Search

The quality of the metal of rotors of high-power turbines and generators is a very important factor that determines their\\u000a reliability and service life. The rotor quality, in turn, depends on the correct choice of the material and the process of\\u000a rotor production. The paper concerns the properties of steel 25Kh2NMFA and the choice of an optimum heat treatment for

I. A. Borisov; G. N. Merinov; E. V. Slezkina

1997-01-01

89

Determination of SATI Instrument Filter Parameters by Processing Interference Images  

E-print Network

This paper presents a method for determination of interference filter parameters such as the effective refraction index and the maximal transmittance wavelength on the basis of image processing of a spectrogram produced by Spectrometer Airglow Temperature Imager instrument by means of data processing. The method employs the radial sections for determination of points from the crests and valleys in the spectrograms. These points are involved in the least square method for determination of the centres and radii of the crests and valleys. The use of the image radial sections allows to determine the maximal number of crests and valleys in the spectrogram. The application of the least square fitting leads to determination of the image centers and radii of the crests and valleys with precision higher than one pixel. The nocturnal course of the filter parameters produced by this method is presented and compared with that of the known ones. The values of the filter parameters thus obtained are closer to the laborator...

Atanassov, Atanas Marinov

2010-01-01

90

Parameter estimation of a bivariate compound Poisson process  

Microsoft Academic Search

In this article, we review the concept of a Lévy copula to describe the dependence structure of a bivariate compound Poisson process. In this first statistical approach we consider a parametric model for the Lévy copula and estimate the parameters of the full dependent model based on a maximum likelihood approach. This approach ensures that the estimated model remains in

Habib Esmaeili; Claudia Klüppelberg

2010-01-01

91

Microstructure evolution in a 316L stainless steel subjected to multidirectional forging and unidirectional bar rolling  

NASA Astrophysics Data System (ADS)

The formation of ultrafine-grained structures was studied in a 316L stainless steel during severe plastic deformation. The steel samples were processed up to a total amount of strain of 4 at ambient temperature using two different methods, i.e., multidirectional forging and unidirectional bar rolling. The large strain developed upon cold working resulted mechanical twinning and partial martensitic transformation. The latter was readily developed during multidirectional forging. After straining to the total amount of strain of 4, the austenite fractions comprised approximately- 0.45 as well as 0.15 in the rolled and forged samples, respectively. Both the multidirectional forging and bar rolling led to extensive grain refinement. The uniform microstructures consisting of austenite and ferrite crystallites with the transverse size of 60 nm and 30 nm were evolved at a total amount of strain of 4 in the rolled and forged samples, respectively. The grain refinement by severe plastic deformation was accompanied by an increase for the microhardness to 5380 and 4970 MPa for the forged and rolled samples, respectively.

Odnobokova, M.; Kipelova, A.; Belyakov, A.; Kaibyshev, R.

2014-08-01

92

Parameter Inference in the Ornstein-Uhlenbeck Process  

NASA Astrophysics Data System (ADS)

The Ornstein-Uhlenbeck process has been proposed as a model for the spontaneous activity of a neuron. In this model, the firing of the neuron corresponds to the first passage of the process to a constant boundary, or threshold. While the Laplace transform of the first passage time distribution is available, the real density has not been obtained in any tractable form. We address the problem of estimating the parameters of the process when the only available data from a neuron are the interspike intervals, or the times between firings. In particular, we give an algorithm for computing maximum likelihood estimates (MLEs) and their corresponding confidence regions for three of the five model parameters by numerically inverting the Laplace transform. We also provide an analysis on the reliability of the estimates and their confidence regions when simulated data is used to generate the first passage sample.

Mullowney, Paul; Iyengar, Satish

2007-03-01

93

Effect of Process Parameters on Catalytic Incineration of Solvent Emissions  

PubMed Central

Catalytic oxidation is a feasible and affordable technology for solvent emission abatement. However, finding optimal operation conditions is important, since they are strongly dependent on the application area of VOC incineration. This paper presents the results of the laboratory experiments concerning four most central parameters, that is, effects of concentration, gas hourly space velocity (GHSV), temperature, and moisture on the oxidation of n-butyl acetate. Both fresh and industrially aged commercial Pt/Al2O3 catalysts were tested to determine optimal process conditions and the significance order and level of selected parameters. The effects of these parameters were evaluated by computer-aided statistical experimental design. According to the results, GHSV was the most dominant parameter in the oxidation of n-butyl acetate. Decreasing GHSV and increasing temperature increased the conversion of n-butyl acetate. The interaction effect of GHSV and temperature was more significant than the effect of concentration. Both of these affected the reaction by increasing the conversion of n-butyl acetate. Moisture had only a minor decreasing effect on the conversion, but it also decreased slightly the formation of by products. Ageing did not change the significance order of the above-mentioned parameters, however, the effects of individual parameters increased slightly as a function of ageing. PMID:18584032

Ojala, Satu; Lassi, Ulla; Peramaki, Paavo; Keiski, Riitta L.

2008-01-01

94

Properties of pellets manufactured by wet extrusion\\/spheronization process using ?-carrageenan: Effect of process parameters  

Microsoft Academic Search

The aim of this study was to systematically evaluate the pelletization process parameters of ?-carrageenan-containing formulations.\\u000a The study dealt with the effect of 4 process parameters—screw speed, number of die holes, friction plate speed, and spheronizer\\u000a temperature—on the pellet properties of shape, size, size distribution, tensile strength, and drug release. These parameters\\u000a were varied systematically in a 24 full factorial

Markus Thommes; Peter Kleinebudde

2007-01-01

95

Processing-microstructure relationships for Ti6Al2Sn4Zr2Mo0.1Si  

Microsoft Academic Search

The detailed relationships between thermal-mechanical processing parameters and resulting microstructures for Ti-6Al-2Sn-4Zr-2Mo-0.1 Si (Ti-6242) have been established through compression testing and heat treatment. Beginning with either an equiaxed alpha or Widmanstätten alpha preform microstructure, isothermal compression tests were run at strain rates typical of isothermal forging (10-3 to 10-1 s-1) and conventional forging (1 to 100 s-1). Metallographic investigation of

S. L. Semiatin; J. F. Thomas; P. Dadras

1983-01-01

96

4. FORGE, ANVIL, PEDESTAL GRINDER, AND BELT DRIVES. NOTE WATERWHEEL ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. FORGE, ANVIL, PEDESTAL GRINDER, AND BELT DRIVES. NOTE WATERWHEEL NEEDLE VALVE CASTING HANGING ON THE WALL ABOVE THE FORGE. VIEW TO NORTH. - Santa Ana River Hydroelectric System, SAR-1 Machine Shop, Redlands, San Bernardino County, CA

97

Stainless-steel elbows formed by spin forging  

NASA Technical Reports Server (NTRS)

Large seamless austenitic stainless steel elbows are fabricated by spin forging /rotary shear forming/. A specially designed spin forging tool for mounting on a hydrospin machine has been built for this purpose.

1964-01-01

98

Thermo-Mechanical Processing Parameters for the INCONEL ALLOY 740  

SciTech Connect

In 2000, a Cooperative Research and Development Agreement (CRADA) was undertaken between the Oak Ridge National Laboratory (ORNL) and the Special Metals Corporation (SMC) to determine the mechanical property response of the IN740 alloy to help establish thermo-mechanical processing parameters for the use of this alloy in supercritical and ultra-critical boiler tubes with the potential for other end uses. SMC had developed an alloy, commercially known as INCONEL alloy 740, which exhibited various beneficial physical, mechanical, and chemical properties. As part of SMC's on-going efforts to optimize this alloy for targeted boiler applications there was a need to develop an understanding of the thermo-mechanical response of the material, characterize the resulting microstructure from this processing, and possibly, utilize models to develop the appropriate processing scheme for this product.

Ludtka, G.M.; Smith, G.

2007-11-19

99

Quenching and Cold-Work Residual Stresses in Aluminum Hand Forgings : Contour Method Measurement and FEM Prediction  

Microsoft Academic Search

The cold-compression stress relief process used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings does not fully relieve the stresses. This study measured and predicted the residual stress in 7050-T74 (solution heat treated, quenched, and artificially overaged) and 7050-T7452 (cold compressed prior to aging) hand forgings. The manufacturing process was simulated by finite element analysis. First, a

Michael B. Prime; Mark A. Newborn; John A. Balog

2003-01-01

100

Quality of margarine: fats selection and processing parameters.  

PubMed

Optimum processing conditions on palm oil-based formulations are required to produce the desired quality margarine. As oils and fats contribute to the overall property of the margarine, this paper will review the importance of beta' tending oils and fats in margarine formulation, effects of the processing parameters -- emulsion temperature, flow-rate, product temperature and pin-worker speed -- on palm oil margarines produced and their subsequent behaviour in storage. Palm oil, which contributes the beta' crystal polymorph and the best alternative to hydrogenated liquid fats, and the processing conditions can affect the margarine consistency by influencing the solid fat content (SFC) and the types of crystal polymorph formed during production as well as in storage. Palm oil, or hydrogenated palm oil and olein, in mixture with oils of beta tending, can veer the product to the beta' crystal form. However, merely having beta' crystal tending oils is not sufficient as the processing conditions are also important. The emulsion temperature had no significant effect on the consistency and polymorphic changes of the product during storage, even though differences were observed during processing. The consistency of margarine during storage was high at low emulsion flow-rates and low at high flow rates. The temperature of the scraped-surface tube-cooler is the most important parameter in margarine processing. High temperature will produce a hardened product with formation of beta-crystals during storage. The speed of the pin-worker is responsible for inducing crystallization but, at the same time, destroys the crystal agglomerates, resulting in melting. PMID:16326646

Miskandar, Mat Sahri; Man, Yaakob Che; Yusoff, Mohd Suria Affandi; Rahman, Russly Abd

2005-01-01

101

76 FR 50755 - Heavy Forged Hand Tools From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-457-A-D (Third Review)] Heavy Forged Hand Tools From China Determinations On the...antidumping duty orders on heavy forged hand tools from China would be likely to lead...August 2011), entitled Heavy Forged Hand Tools From China: Investigation...

2011-08-16

102

76 FR 168 - Heavy Forged Hand Tools From China  

Federal Register 2010, 2011, 2012, 2013

...731-TA-457-A-D (Third Review)] Heavy Forged Hand Tools From China AGENCY: United States...antidumping duty orders on heavy forged hand tools from China...antidumping duty orders on heavy forged hand tools from China would be likely to...

2011-01-03

103

Heated Dies for Forging and Friction Studies on a Modified Hydraulic Forge Press.  

National Technical Information Service (NTIS)

A heated die assembly, designed to bolt onto a hydraulic forge press, is described. Novel features of the design include (a) split heater blocks, which contain semi-cylindrical grooves and which bolt in pairs around cartridge heaters, thereby facilitating...

D. J. Abson, F. J. Gurney, T. M. Brown

1972-01-01

104

Assisted Defect Recognition for the Ultrasonic Multizone Inspection of Titanium Forgings  

NASA Astrophysics Data System (ADS)

Titanium aircraft engine disk forgings are imaged at all material depths using the ultrasonic testing (UT) process called multizone inspection. This process results in highly variable background noise from material microstructure. The intention is to ultimately accept or reject the part by examining for the presence of small anomalies in these images in terms of their signal to noise ratio (SNR). This manual approach for calculating SNR is susceptible to inspector subjectivity. Assisted Defect Recognition (ADR) has been developed for the forging inspection and its life cycle from design to validation is discussed, concentrating on its application to the inhomogeneous nature of the forged titanium microstructure. Validation testing results have shown that ADR effectively reduces inspection cycle time, reduces complexity for the operator, and provides precise inspection reproducibility.

Ferro, A. F.; Howard, P. J.

2009-03-01

105

Analysis of hot forging of porous metals  

Microsoft Academic Search

Thermomechanical elastoplastic problems in hot forging of the porous metals have been analysed using the thermoelastoplastic finite element method. This finite element program has been formulated using the yield condition advanced by Lee and Kim and developed using the thermoelastoplastic time integration procedure. A hardening law of non-porous metals as a function of temperature, plastic strain and strain rate is

Heung Nam Han; Yong-gi Lee; Kyu Hwan Oh; Dong Nyung Lee

1996-01-01

106

Forging Inclusive Solutions: Experiential Earth Charter Education  

ERIC Educational Resources Information Center

Forging Inclusive Solutions describes the aims, methodology and outcomes of Inclusive Leadership Adventures, an experiential education curriculum for exploring the Earth Charter. Experiential education builds meaningful relationships, skills, awareness and an inclusive community based on the Earth Charter principles. When we meet people where they…

Hill, Linda D.

2010-01-01

107

Modeling Machining Distortion of Aircraft-Engine Disk Forgings  

NASA Astrophysics Data System (ADS)

Rotating components of aircraft engines are generally manufactured by forging followed by heat treatment. Due to the residual stresses induced during heat treatment, components often distort when material is removed during machining to the final shape. Using trial-and-error approaches, it can be very difficult to develop a sequence of machining operations which will ensure that the final component is produced within the very tight dimensional tolerances required for satisfactory performance in service. The objective of the current work, therefore, was to develop and validate a simulation procedure that can predict distortion during the material removal process. To validate the model, four prototype disks were forged and then heat treated under different conditions. Multiple machining cuts were carried out on the top side of each disk. The distortion at the bottom surface was then measured. The Finite-Element Method (FEM) embodied in the commercial software, DEFORM™-HT, was used to model the four heat-treatment processes. Excellent agreement between the measured distortions and the finite-element predictions was found. The FEM heat-treatment model was shown to be a very useful tool to understand and predict distortion and can thus be used for the design and optimization of heat-treatment and machining processes.

Yin, Yanling; Wu, Wei-Tsu; Srivatsa, Shesh; Semiatin, S. Lee; Gayda, John

2004-06-01

108

Optimisation of shock absorber process parameters using failure mode and effect analysis and genetic algorithm  

NASA Astrophysics Data System (ADS)

The various process parameters affecting the quality characteristics of the shock absorber during the process were identified using the Ishikawa diagram and by failure mode and effect analysis. The identified process parameters are welding process parameters (squeeze, heat control, wheel speed, and air pressure), damper sealing process parameters (load, hydraulic pressure, air pressure, and fixture height), washing process parameters (total alkalinity, temperature, pH value of rinsing water, and timing), and painting process parameters (flowability, coating thickness, pointage, and temperature). In this paper, the process parameters, namely, painting and washing process parameters, are optimized by Taguchi method. Though the defects are reasonably minimized by Taguchi method, in order to achieve zero defects during the processes, genetic algorithm technique is applied on the optimized parameters obtained by Taguchi method.

Mariajayaprakash, Arokiasamy; Senthilvelan, Thiyagarajan; Vivekananthan, Krishnapillai Ponnambal

2013-07-01

109

Analysis of process parameters of micro fluid-jet polishing on the processing effect  

NASA Astrophysics Data System (ADS)

Micro fluid-jet polishing technology is a new kind of ultra-smooth machining method which proposed on the basis of float polishing principle and combined with small tool polishing. This article will use micro jet ultra-smooth machine which developed by ourselves to develop the process experiment for plane elements. In the experiment, the material removal rate and surface roughness are taken as the assessment index, and the orthogonal experiment method is used to study the processing effect of different process parameters, such as the spindle speed, the pressure of the grinding head and the abrasive concentration. On the basis of the experimental results and combined with the micro jet polishing mechanism, the processing effect law of the various process parameters is analyzed. It shows that, the influence of polishing pressure and abrasive concentration on the removal efficiency is single, that is to say, the removal efficiency can be increased either by increasing the polishing pressure or by increasing the concentration of the slurry. However, the influence of the grinding speed on removal efficiency is not simple, the removal efficiency can be increased by increasing the grinding speed in the certain range, if continue to increase, the removal efficiency will decrease. The influence of the process parameters on the roughness is more complex, but it can be summarized grossly as follows: if the roughness is required to reduce quickly, the large polishing pressure and high concentration slurry can be chosen, but it has a large depth of removal; if the roughness is required to reduce and the removal depth is as small as possible, the little polishing pressure and the dilute polishing liquid can be chosen, but it has a long polishing time. So in the actual processing, the process parameters should be adjusted according to different machining needs, to finally reach the optimization.

Wang, Shaozhi; Liu, Jian; Zhang, Linghua

2013-08-01

110

Hot forging of melt quenched powder: Microstructure development and kinetics of densification  

Microsoft Academic Search

Hot powder forging is a new process for making scalable and cost-effective nanocrystalline ceramics. It utilizes powder typically between 5 mum to 25 mum to nucleate very stable crystallite sizes well below 100 nm. These particles superplastically deform at relatively moderate temperature and stress. Hence, rapid densification at high creep rates is achieved with limited grain growth. A novel way

Hrishikesh Keshavan

2006-01-01

111

FATIGUE PERFORMANCE COMPARISON AND LIFE PREDICTION OF FORGED STEEL AND DUCTILE CAST IRON CRANKSHAFTS  

Microsoft Academic Search

The objective of this study was to compare the durability of crankshafts from two competing manufacturing processes, as well as to perform dynamic load and stress analysis, and optimization. The crankshafts used in the study were forged steel and ductile cast iron from a one-cylinder gasoline engine. Strain-controlled monotonic and fatigue tests as well as impact tests were performed on

JONATHAN WILLIAMS; FARZIN MONTAZERSADGH; ALI FATEMI

2007-01-01

112

Mesh Forging: Editing of 3D-Meshes Using Implicitly Defined Occluders  

Microsoft Academic Search

In recent years the ease of use and the flexibility in the editing process shifted into focus in modelling and animation applications. In this spirit we present a 3D mesh editing method that is similar to the simple constrained deformation (scodef) method. We extend this method to the so-called mesh forging paradigm by adding an occluder to the editing environment.

Gerhard H. Bendels; Reinhard Klein

2003-01-01

113

Materials processing with supercritical antisolvent precipitation: process parameters and morphology of tartaric acid  

Microsoft Academic Search

Continuous precipitation with a compressed fluid antisolvent (PCA) has been used to produce fine particles of tartaric acid. Liquid solutions of tartaric acid in acetone, ethanol and methanol\\/ethanol mixtures have been sprayed into supercritical carbon dioxide used as antisolvent. Among the process parameters, pressure, temperature, flow rate of solvent and different nozzles have been tested. Furthermore, the effect of solute

H Kröber; U Teipel

2002-01-01

114

Microstructural Changes during Isothermal Forging of a Co-Cr-Mo Alloy  

NASA Astrophysics Data System (ADS)

Interest has evolved recently in thermomechanical processing of the cast Co-Cr-Mo surgical implant alloys such as Vitallium and Vinertia. Work has shown that the wrought forms of these alloys exhibit much improved properties over their as-cast counterparts. In this paper, the response of as-cast Vinertia to isothermal forging is examined by means of isothermal and isostrain-rate compression testing. The effects of temperature, strain rate, and strain on the breakdown of the as-cast micro-structure are examined in detail. The effects of prior heat treatment on plastic flow and microstructure achieved are also considered. It is shown that the interaction between the carbide phase and the recrystallization induced during hot working governs the degree of homogeneity that can be achieved in the forged product. Control of carbide volume fraction, size, and distribution by appropriate prior processing can lead to a fine grain equiaxed structure with uniformly distributed carbides. The potential offered by isothermal forging for control of the microstructure in this type of alloy is discussed, as well as the limits imposed on the process by the starting material and by the strain gradients expected during the forging of implants.

Immarigeon, J.-P.; Rajan, Krishna; Wallace, W.

1984-02-01

115

Drug recrystallization using supercritical anti-solvent (SAS) process with impinging jets: Effect of process parameters  

NASA Astrophysics Data System (ADS)

The aim of this study is to improve mixing in supercritical anti-solvent process (SAS) with impinging jets in order to form finer particles of sulfathiazole, a poorly water-soluble drug. The influence of several process parameters upon the powder characteristics is studied. Parameters are jets' velocity (0.25 m s-1 to 25.92 m s-1), molar ratio solvent/CO2 (2.5% to 20%), temperature (313 K to 343 K), pressure (10 MPa to 20 MPa) and sulfathiazole concentration in the organic solution (0.5% to 1.8%). Two solvents are used: acetone and methanol. Smaller particles with a more homogeneous morphology are obtained from acetone solutions. For the smallest jets' velocity, corresponding to a non-atomized jet, the stable polymorphic form is obtained, pure or in mixture. At this velocity, pressure is the most influential parameter controlling the polymorphic nature of the powder formed. The pure stable polymorph is formed at 20 MPa. Concerning the particle size, the most influential parameters are temperature and sulfathiazole concentration. The use of impinging jets with different process parameters allows the crystallization of four polymorphs among the five known, and particle sizes are varied. This work demonstrates the studied device ability of the polymorph and the size control. A comparison with the classical SAS process shows that particle size, size distribution and morphology of particles crystallized with impinging jets are different from the ones obtained with classical SAS introduction device in similar operating conditions. Mean particle sizes are significantly smaller and size distributions are narrower with impinging jets device.

Careno, Stéphanie; Boutin, Olivier; Badens, Elisabeth

2012-03-01

116

Optimizing noise control strategy in a forging workshop.  

PubMed

In this paper, a computer program based on a genetic algorithm is developed to find an economic solution for noise control in a forging workshop. Initially, input data, including characteristics of sound sources, human exposure, abatement techniques, and production plans are inserted into the model. Using sound pressure levels at working locations, the operators who are at higher risk are identified and picked out for the next step. The program is devised in MATLAB such that the parameters can be easily defined and changed for comparison. The final results are structured into 4 sections that specify an appropriate abatement method for each operator and machine, minimum allowance time for high-risk operators, required damping material for enclosures, and minimum total cost of these treatments. The validity of input data in addition to proper settings in the optimization model ensures the final solution is practical and economically reasonable. PMID:24934422

Razavi, Hamideh; Ramazanifar, Ehsan; Bagherzadeh, Jalal

2014-01-01

117

Sequential Probability Ratio Tests for the Shape Parameter of a Nonhomogeneous Poisson Process  

Microsoft Academic Search

Sequential probability ratio tests for the shape parameter of one or more nonhomogeneous Poisson processes, with power intensity functions, are provided. The tests can be performed when the scale parameter is an unknown nuisance parameter; the effective loss of not knowing the scale parameter is one observation per process. The resulting tests can be expressed in terms of the maximum

Lee J. Bain; Max Engelhardt

1982-01-01

118

The Elements: Forged in Stars  

NSDL National Science Digital Library

All the stars in the universe, including the Sun, are nuclear furnaces fueled by fusion. Beginning with the fusion of hydrogen and continuing with fusion of successively heavier elements, stars form all the naturally occurring elements heavier than hydrogen and helium. This video segment illustrates the critical role that stars play in creating the elements, and describes the process of nucleosynthesis, in which increasingly heavier elements up through iron are formed, at which point the star collapses and explodes in a supernova, during which elements heavier than iron are created. The segment is three minutes forty-two seconds in length. A background essay and discussion questions are included.

2011-03-28

119

The Elements: Forged in Stars  

NSDL National Science Digital Library

All the stars in the universe, including the Sun, are nuclear furnaces fueled by fusion. Beginning with the fusion of hydrogen and continuing with fusion of successively heavier elements, stars form all the naturally occurring elements heavier than hydrogen and helium. This video segment illustrates the critical role that stars play in creating the elements, and describes the process of nucleosynthesis, in which increasingly heavier elements up through iron are formed, at which point the star collapses and explodes in a supernova, during which elements heavier than iron are created. The segment is three minutes forty-two seconds in length. A background essay and discussion questions are included.

120

Optimization research of process parameters for Laser Direct Rapid Forming metal parts based on genetic algorithm  

Microsoft Academic Search

The optimization research of process parameters for Laser Direct Rapid Forming (LDRF) metal parts, is a research focus of rapid prototyping technology. The article discussed in detail for solving the optimum process parameters of LDRF technology for the selection approach of strategy of genetic algorithm, the quantitative relationship model was established between process parameters of forming pieces and the part

Wang Jianbin; Chen binghuang

2010-01-01

121

76 FR 31585 - Forged Stainless Steel Flanges From India: Notice of Rescission of Antidumping Duty...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-533-809] Forged Stainless Steel Flanges From India: Notice of...antidumping duty order on forged stainless steel flanges from India. The period...antidumping duty order on forged stainless steel flanges from India. See...

2011-06-01

122

The effect of hot isostatic pressing parameters on microstructure and mechanical properties of Eurofer powder HIPed material  

NASA Astrophysics Data System (ADS)

The production of reduced activation ferritic/martensitic (RAFM) steel by powder metallurgy and high isostatic pressing (HIP) offers numerous advantages for different nuclear applications. The objective of this work is to optimise the Eurofer powder HIP process in order to obtain RAFM solid HIPed steel with similar mechanical properties to those of a forged material. Starting from the forged solid Eurofer steel batch, the material is atomized and the Eurofer powder is characterized in terms of granulometry, chemical composition, surface oxides, etc. Different compaction HIP cycle parameters in the temperature range (950-1100 °C) are tested. The chemical composition of the HIPed material is comparable to the initial forged Eurofer. All the obtained materials are fully dense and the microstructure of the compacted material is well martensitic. The prior austenite grain size seems to be constant in this temperature range. The mechanical tests performed at room temperature reveal acceptable hardness, tensile and Charpy impact properties regarding the ITER specification.

Gentzbittel, J. M.; Chu, I.; Burlet, H.

2002-12-01

123

Numerical Investigation of Process Parameters on External Inversion of Thin-Walled Tubes  

NASA Astrophysics Data System (ADS)

In this paper, a computational study of development of external inversion mode of deformation of round-metallic aluminum tubes over a fixed profile die is presented. Inversion mode of deformation is analyzed in detail by using a finite element code FORGE2. The proposed finite element model for this purpose idealizes the deformation as axisymmetric. Six-noded triangular elements are used to discretize the domain. The material is modeled as rigid-viscoplastic. Typical variations of the equivalent strain rate and equivalent strain along the length of the deforming tube are studied to predict the development of inversion mode of deformation. The influence of the friction present at the contact interface between the tube and the die is also examined to suggest a successful inversion of tube. Energy absorbed in overcoming the frictional stresses between the tube-die interfaces is compared with the total energy required in the inversion of tube. A few predicted results which include the geometry of inverted tube load-compression variation during inversion process are compared with their experimental counterparts to validate the computational model.

Gupta, P. K.

2014-08-01

124

On the process parameter of laser tube bending  

Microsoft Academic Search

Laser tube bending is a process in which the laser irradiates the tube surface to induce the thermal stress and bend the tubes. As no hard tooling or external forces is needed during, laser tube bending is a flexible forming process and has potential to deal with materials difficult to bend or thin wall tubes. A formula for bending angle

Nanhai Hao

2010-01-01

125

Effect of flux cored arc welding process parameters on duplex stainless steel clad quality  

Microsoft Academic Search

The main problem faced in duplex stainless steel cladding is the selection of the optimum combination of process parameters for achieving the required quality of clad. This paper highlights an experimental study carried out to analyse the effects of various flux cored arc welding (FCAW) process parameters on important clad quality parameters in duplex stainless steel cladding of low carbon

T. Kannan; N. Murugan

2006-01-01

126

Determination of SATI Instrument Filter Parameters by Processing Interference Images  

Microsoft Academic Search

This paper presents a method for determination of interference filter\\u000aparameters such as the effective refraction index and the maximal transmittance\\u000awavelength on the basis of image processing of a spectrogram produced by\\u000aSpectrometer Airglow Temperature Imager instrument by means of data processing.\\u000aThe method employs the radial sections for determination of points from the\\u000acrests and valleys in the

Atanas Marinov Atanassov

2010-01-01

127

Table 1. Process parameters and their ranges Step Parameters Abbrev. Ranges Units  

E-print Network

of verification. Employing a neural network modeling technique, a process model is established, and response, biocompatibility, and suitability for fabricating high aspect ratio features [1]-[3]. SU-8 is a negative near­UV has led to concerns about defects in SU-8 fabricated microstructures. In an effort to reduce

128

EFFECT OF PROCESS PARAMETERS ON THE GRINDING OF POLYMERIC COMPOSITES  

Microsoft Academic Search

The present paper discusses and compares the results of two similar studies that were carried out in the U.S. and Egypt simultaneously. The objective in both cases was to validate a previously published mathematical model (1-3), which describes the process of grinding polymeric composites by dimensionless numbers. Cylindrical grinding was carried out by means of a precision lathe and a

Sherif D. El Wakil; Nahid Abd; El-Salam Azab

129

A Multiresolution Method for Parameter Estimation of Diffusion Processes  

PubMed Central

Diffusion process models are widely used in science, engineering and finance. Most diffusion processes are described by stochastic differential equations in continuous time. In practice, however, data is typically only observed at discrete time points. Except for a few very special cases, no analytic form exists for the likelihood of such discretely observed data. For this reason, parametric inference is often achieved by using discrete-time approximations, with accuracy controlled through the introduction of missing data. We present a new multiresolution Bayesian framework to address the inference difficulty. The methodology relies on the use of multiple approximations and extrapolation, and is significantly faster and more accurate than known strategies based on Gibbs sampling. We apply the multiresolution approach to three data-driven inference problems – one in biophysics and two in finance – one of which features a multivariate diffusion model with an entirely unobserved component.

Kou, S. C.; Olding, Benjamin P.; Lysy, Martin; Liu, Jun S.

2014-01-01

130

Influence of daughter radionuclides on Purex-process parameters  

Microsoft Academic Search

Experimental and calculated data are presented which concern the limiting influence of239Np,237U,233Pa,234Th,228Th (with daughter radionuclides) on the final decontamination of uranium, plutonium and neptunium from -emitters in Purex-process for NPP fuel reprocessing. It was found, in particular, that in the investigated flowsheet228Th follows neptunium(IV) and233Pa accompanies plutonium. The influence of accumulated daughter -emitters on ionization characteristics of end products in

B. Ya. Zilberman; V. M. Mosyazh; V. A. Starchenko

1990-01-01

131

The Effects of Forming Parameters on Conical Ring Rolling Process  

PubMed Central

The plastic penetration condition and biting-in condition of a radial conical ring rolling process with a closed die structure on the top and bottom of driven roll, simplified as RCRRCDS, were established. The reasonable value range of mandrel feed rate in rolling process was deduced. A coupled thermomechanical 3D FE model of RCRRCDS process was established. The changing laws of equivalent plastic strain (PEEQ) and temperature distributions with rolling time were investigated. The effects of ring's outer radius growth rate and rolls sizes on the uniformities of PEEQ and temperature distributions, average rolling force, and average rolling moment were studied. The results indicate that the PEEQ at the inner layer and outer layer of rolled ring are larger than that at the middle layer of ring; the temperatures at the “obtuse angle zone” of ring's cross-section are higher than those at “acute angle zone”; the temperature at the central part of ring is higher than that at the middle part of ring's outer surfaces. As the ring's outer radius growth rate increases at its reasonable value ranges, the uniformities of PEEQ and temperature distributions increase. Finally, the optimal values of the ring's outer radius growth rate and rolls sizes were obtained. PMID:25202716

Meng, Wen; Zhao, Guoqun; Guan, Yanjin

2014-01-01

132

Optimization of process parameters for the manufacturing of rocket casings: A study using processing maps  

NASA Astrophysics Data System (ADS)

Maraging steels possess ultrahigh strength combined with ductility and toughness and could be easily fabricated and heat-treated. Bulk metalworking of maraging steels is an important step in the component manufacture. To optimize the hot-working parameters (temperature and strain rate) for the ring rolling process of maraging steel used for the manufacture of rocket casings, a systematic study was conducted to characterize the hot working behavior by developing processing maps for ?-iron and an indigenous 250 grade maraging steel. The hot deformation behavior of binary alloys of iron with Ni, Co, and Mo, which are major constituents of maraging steel, is also studied. Results from the investigation suggest that all the materials tested exhibit a domain of dynamic recrystallization (DRX). From the instability maps, it was revealed that strain rates above 10 s-1 are not suitable for hot working of these materials. An important result from the stress-strain behavior is that while Co strengthens ?-iron, Ni and Mo cause flow softening. Temperatures around 1125 °C and strain rate range between 0.001 and 0.1 s-1 are suitable for the hot working of maraging steel in the DRX domain. Also, higher strain rates may be used in the meta-dynamic recrystallization domain above 1075 °C for high strain rate applications such as ring rolling. The microstructural mechanisms identified from the processing maps along with grain size analyses and hot ductility measurements could be used to design hot-working schedules for maraging steel.

Avadhani, G. S.

2003-12-01

133

A stochastic process approach of the drake equation parameters  

NASA Astrophysics Data System (ADS)

The number N of detectable (i.e. communicating) extraterrestrial civilizations in the Milky Way galaxy is usually calculated by using the Drake equation. This equation was established in 1961 by Frank Drake and was the first step to quantifying the Search for ExtraTerrestrial Intelligence (SETI) field. Practically, this equation is rather a simple algebraic expression and its simplistic nature leaves it open to frequent re-expression. An additional problem of the Drake equation is the time-independence of its terms, which for example excludes the effects of the physico-chemical history of the galaxy. Recently, it has been demonstrated that the main shortcoming of the Drake equation is its lack of temporal structure, i.e., it fails to take into account various evolutionary processes. In particular, the Drake equation does not provides any error estimation about the measured quantity. Here, we propose a first treatment of these evolutionary aspects by constructing a simple stochastic process that will be able to provide both a temporal structure to the Drake equation (i.e. introduce time in the Drake formula in order to obtain something like N(t)) and a first standard error measure.

Glade, Nicolas; Ballet, Pascal; Bastien, Olivier

2012-04-01

134

Advances in modeling the effects of selected parameters on the SLS process  

Microsoft Academic Search

Selective laser sintering (SLS) is a leading process for developing rapid prototype objects by selectively fusing layers of powder according to numerically defined cross-sectional geometry. The process has the potential to become an indispensable industrial tool. However, continuous process improvement is necessary. Improved understanding of the parameter effects on the process response is expected to lead to process advances. In

John D. Williams; Carl R. Deckard

1998-01-01

135

Deformation characteristics of isothermally forged UDIMET 720 nickel-base superalloy  

Microsoft Academic Search

The hot deformation behavior of nickel-base superalloy UDIMET 720 in solution-treated conditions, simulating the forging process\\u000a of the alloy, was studied using hot compression experiments. Specimens were deformed in the temperature range of 1000 C to\\u000a 1175 C with strain rates of 10?3 to 1 s?1 and total strain of 0.8. Below 1100 C, all specimens showed flow localization as

H. Monajati; A. K. Taheri; M. Jahazi; S. Yue

2005-01-01

136

ANN and GA-Based Process Parameter Optimization for MIMO Plastic Injection Molding  

Microsoft Academic Search

Determining optimal initial process parameter settings critically influences productivity, quality, and costs of production in the plastic injection molding (PIM) industry. Up to now, most production engineers have either used trial-and-error or Taguchi's parameter design method to determine initial settings for a number of parameters, including melt temperature, injection pressure, injection velocity, injection time, packing pressure, packing time, cooling temperature,

Wen-Chin Chen; Gong-Loung Fu; Pei-Hao Tai; Wei-Jaw Deng; Yang-Chih Fan

2007-01-01

137

A Comparison between the Properties of Solid Cylinders and Tube Products in Multi-Pass Hot Radial Forging Using Finite Element Method  

NASA Astrophysics Data System (ADS)

Radial forging is an open die forging process used for reducing the diameter of shafts, tubes, stepped shafts and axels, and creating internal profiles for tubes such as rifling of gun barrels. In this work, a comprehensive study of multi-pass hot radial forging of short hollow and solid products are presented using 2-D axisymmetric finite element simulation. The workpiece is modeled as an elastic-viscoplastic material. A mixture of Coulomb law and constant limit shear is used to model the die-workpiece and mandrel-workpiece contacts. Thermal effects are also taken in to account. Three-pass radial forging of solid cylinders and tube products are considered. Temperature, stress, strain and metal flow distribution are obtained in each pass through thermo-mechanical simulation. The numerical results are compared with available experimental data and are in good agreement with them.

Abedian, A.; Poursina, M.; Golestanian, H.

2007-05-01

138

FEA Based Tool Life Quantity Estimation of Hot Forging Dies Under Cyclic Thermo-Mechanical Loads  

NASA Astrophysics Data System (ADS)

Hot forging dies are exposed during service to a combination of cyclic thermo-mechanical, tribological and chemical loads. Besides abrasive and adhesive wear on the die surface, fatigue crack initiation with subsequent fracture is one of the most frequent causes of failure. In order to extend the tool life, the finite element analysis (FEA) may serve as a means for process design and process optimisation. So far the FEA based estimation of the production cycles until initial cracking is limited as tool material behaviour due to repeated loading is not captured with the required accuracy. Material models which are able to account for cyclic effects are not verified for the fatigue life predictions of forging dies. Furthermore fatigue properties from strain controlled fatigue tests of relevant hot work steels are to date not available to allow for a close-to-reality fatigue life prediction. Two industrial forging processes, where clear fatigue crack initiation has been observed are considered for a fatigue analysis. For this purpose the relevant tool components are modelled with elasto-plastic material behaviour. The predicted sites, where crack initiation occurs, agree with the ones observed on the real die component.

Behrens, B.-A.; Bouguecha, A.; Schäfer, F.; Hadifi, T.

2011-01-01

139

Modelling the correlation between processing parameters and properties of maraging steels using artificial neural network  

Microsoft Academic Search

An artificial neural network (ANN) model is developed for the analysis and simulation of the correlation between the properties of maraging steels and composition, processing and working conditions. The input parameters of the model consist of alloy composition, processing parameters (including cold deformation degree, ageing temperature, and ageing time), and working temperature. The outputs of the ANN model include property

Z. Guo; W. Sha

2004-01-01

140

DETAIL VIEW OF BLACKSMITH'S FORGE AND WORK AREA ON WEST ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF BLACKSMITH'S FORGE AND WORK AREA ON WEST SIDE OF UPPER TRAM TERMINAL, LOOKING EAST. FORGE IS IN FOREGROUND, WITH THE ANVIL BLOCK JUST TO THE RIGHT AND BEHIND IT. A TRAM CAR IS UPSIDE DOWN TO THE LEFT OF THE FORGE. THE PIPE GOING INTO THE FORGE ON THE RIGHT CARRIED COMPRESSED AIR TO BLOW THE COALS. AT CENTER RIGHT ON THE TRAM TERMINAL ARE THE OPENING AND CLOSING MECHANISMS FOR THE ORE BUCKETS. AT CENTER LEFT IS A BRAKE WHEEL. THE ANCHOR POINTS FOR THE STATIONARY TRAM CABLES ARE JUST BELOW THIS WHEEL. THE FRONT END OF THE TERMINAL IS JUST OFF FRAME ON THE RIGHT. - Keane Wonder Mine, Park Route 4 (Daylight Pass Cutoff), Death Valley Junction, Inyo County, CA

141

Process parameters optimization of injection molding using a fast strip analysis as a surrogate model  

Microsoft Academic Search

Injection molding process parameters such as injection temperature, mold temperature, and injection time have direct influence\\u000a on the quality and cost of products. However, the optimization of these parameters is a complex and difficult task. In this\\u000a paper, a novel surrogate-based evolutionary algorithm for process parameters optimization is proposed. Considering that most\\u000a injection molded parts have a sheet like geometry,

Peng Zhao; Huamin Zhou; Yang Li; Dequn Li

2010-01-01

142

Quenching and Cold-Work Residual Stresses in Aluminum Hand Forgings : Contour Method Measurement and FEM Prediction  

SciTech Connect

The cold-compression stress relief process used to reduce the quench-induced stresses in high-strength aerospace aluminum alloy forgings does not fully relieve the stresses. This study measured and predicted the residual stress in 7050-T74 (solution heat treated, quenched, and artificially overaged) and 7050-T7452 (cold compressed prior to aging) hand forgings. The manufacturing process was simulated by finite element analysis. First, a thermal analysis simulated the quench using appropriate thermal boundary conditions and temperature dependent material properties. Second, a structural analysis used the thermal history and a temperature and strain-rate dependent constitutive model to predict the stresses after quenching. Third, the structural analysis was continued to simulate the multiple cold compressions of the stress relief process. Experimentally, the residual stresses in the forgings were mapped using the contour method, which involved cutting the forgings using wire EDM and then measuring the contour of the cut surface using a CMM. Multiple cuts were used to map different stress components. The results show a spatially periodic variation of stresses that results from the periodic nature of the cold work stress relief process. The results compare favorably with the finite element prediction of the stresses.

Prime, M. B. (Michael B.); Newborn, M. A. (Mark A.); Balog, J. A. (John A.)

2003-01-01

143

Order formation processes of complex systems including different parity order parameters  

NASA Astrophysics Data System (ADS)

In the present study, we focus on the parity of the order parameters and clarify the order formation process in a system including two order parameters. Each order parameter shows different parity under a gauge transformation, namely even and odd order parameters. For example, in a spin-glass model, the even order parameter corresponds to the spin-glass order parameter while the odd one corresponds to the magnetization. We introduce phenomenologically a set of Langevin equations to express the ordering process under a white Gaussian noise. Using two kinds of Fokker-Planck equations, we analyze the order formation process and the entropy production. Furthermore, we show the noise dependence of the onset time.

Hashizume, Yoichiro; Suzuki, Masuo; Okamura, Soichiro

2014-06-01

144

Optimization of processing parameters for laser powder deposition using finite element method  

Microsoft Academic Search

In order to investigate the effects of powder materials and processing parameters on thermal and stress field during laser\\u000a powder deposition (LPD), a finite element model was developed with the help of ANSYS software. The finite element model was\\u000a verified by the comparison between the experimental results and computed results. Then LPD processes with different powder\\u000a materials and processing parameters

Yao Fu; Shuisheng Xie; Xiangyang Xu; Guojie Huang; Lei Cheng; Youfeng He

2010-01-01

145

An Advanced User Interface Approach for Complex Parameter Study Process Specification in the Information Power Grid  

NASA Technical Reports Server (NTRS)

The creation of parameter study suites has recently become a more challenging problem as the parameter studies have now become multi-tiered and the computational environment has become a supercomputer grid. The parameter spaces are vast, the individual problem sizes are getting larger, and researchers are now seeking to combine several successive stages of parameterization and computation. Simultaneously, grid-based computing offers great resource opportunity but at the expense of great difficulty of use. We present an approach to this problem which stresses intuitive visual design tools for parameter study creation and complex process specification, and also offers programming-free access to grid-based supercomputer resources and process automation.

Yarrow, Maurice; McCann, Karen M.; Biswas, Rupak; VanderWijngaart, Rob; Yan, Jerry C. (Technical Monitor)

2000-01-01

146

Probabilistic parameter estimation of activated sludge processes using Markov Chain Monte Carlo.  

PubMed

One of the most important challenges in making activated sludge models (ASMs) applicable to design problems is identifying the values of its many stoichiometric and kinetic parameters. When wastewater characteristics data from full-scale biological treatment systems are used for parameter estimation, several sources of uncertainty, including uncertainty in measured data, external forcing (e.g. influent characteristics), and model structural errors influence the value of the estimated parameters. This paper presents a Bayesian hierarchical modeling framework for the probabilistic estimation of activated sludge process parameters. The method provides the joint probability density functions (JPDFs) of stoichiometric and kinetic parameters by updating prior information regarding the parameters obtained from expert knowledge and literature. The method also provides the posterior correlations between the parameters, as well as a measure of sensitivity of the different constituents with respect to the parameters. This information can be used to design experiments to provide higher information content regarding certain parameters. The method is illustrated using the ASM1 model to describe synthetically generated data from a hypothetical biological treatment system. The results indicate that data from full-scale systems can narrow down the ranges of some parameters substantially whereas the amount of information they provide regarding other parameters is small, due to either large correlations between some of the parameters or a lack of sensitivity with respect to the parameters. PMID:24384542

Sharifi, Soroosh; Murthy, Sudhir; Takács, Imre; Massoudieh, Arash

2014-03-01

147

Evolution of the Ultrasonic Inspection of Heavy Rotor Forgings Over the Last Decades  

NASA Astrophysics Data System (ADS)

All types of heavy forgings that are used in energy machine industry, rotor shafts as well as discs, retaining rings or tie bolts are subject to extensive nondestructive inspections before they are delivered to the customer. Due to the availability of the parts in simple shapes, these forgings are very well suited for full volmetric inspections using ultrasound. In the beginning, these inspections were carried out manually, using straight beam probes and analogue equipment. Higher requirements in reliability, efficiency, safety and power output in the machines have lead to higher requirements for the ultrasonic inspection in the form of more scanning directions, higher sensitivity demands and improved documentation means. This and the increasing use of high alloy materials for ever growing parts, increase the need for more and more sophisticated methods for testing the forgings. Angle scans and sizing technologies like DGS have been implemented, and for more than 15 years now, mechanized and automated inspections have gained importance since they allow better documentation as well as easier evaluation of the recorded data using different views (B- C- or D-Scans), projections or tomography views. The latest major development has been the availability of phased array probes to increase the flexibility of the inspection systems. Many results of the ongoing research in ultrasonic's have not been implemented yet. Today's availability of fast computers, large and fast data storages allows saving RF inspection data and applying sophisticated signal processing methods. For example linear diffraction tomography methods like SAFT offer tools for 3D reconstruction of inspection data, simplifying sizing and locating of defects as well as for improving signal to noise ratios. While such methods are already applied in medical ultrasonic's, they are still to be implemented in the steel industry. This paper describes the development of the ultrasonic inspection of heavy forgings from the beginning up to today at the example of Saarschmiede GmbH explains the difficulties in implementing changes and gives an outlook over the current progression.

Zimmer, A.; Vrana, J.; Meiser, J.; Maximini, W.; Blaes, N.

2010-02-01

148

AIAA-2003-0694 QUANTIFICATION OF PROCESSING PARAMETERS FOR WIND TURBINE  

E-print Network

AIAA-2003-0694 QUANTIFICATION OF PROCESSING PARAMETERS FOR WIND TURBINE BLADES Douglas Cairns, John of processing techniques and can be useful to wind turbine blade manufacturers to prepare processing conditions-3]. This is a consequence of the typical material architectures that are used in wind turbine blades. Figure 1

149

EUV resist simulation based on process parameters of pattern formation reaction  

NASA Astrophysics Data System (ADS)

We simulated the process parameters of a pattern formation reaction that included during-the-exposure and post exposure bake (PEB) processes using an originally developed simulator. From the simulation results, the relationship between process parameters of pattern formation reaction and quencher concentration has been clarified. Moreover, we simulated the present target process parameters of extreme ultraviolet (EUV) resist for breaking the RLS trade-off. In this simulation, the process parameters were calculated from lithographic results (sensitivity, LWR, and CD) using real SEM images. This methodology was used to determine the process parameters required to break the RLS trade-off to obtain the required lithographic target of the EUV resist. We simulated the present lithography performance target using the process parameters of pattern formation reactions. These simulation results showed that a large reaction radius is necessary to break the RLS trade-off. Furthermore, we confirmed that increasing the PEB temperature leads to an improvement in the reaction radius. However, there is a discrepancy between the target radius and the controllable range of reaction radius that can be obtained by varying the PEB temperature.

Sugie, Norihiko; Itani, Toshiro; Kozawa, Takahiro

2014-04-01

150

Short Note Impact of Earthquake Rupture Extensions on Parameter Estimations of Point-Process Models  

Microsoft Academic Search

Online Material: Sensitivity to scaling of the d-parameter and to inhomogeneous background activity, and possible correlation between the largest magnitude and es- timated ?-value. Abstract Stochastic point processes are widely applied to model spatiotemporal earthquake occurrence. In particular, the epidemic type aftershock sequence (ETAS) model has been shown to successfully reproduce the short-term clustering of earth- quakes. An important parameter

S. Hainzl; A. Christophersen; B. Enescu

2008-01-01

151

Effect of stage control parameters on the FIB milling process Joon Hyun Kim a,c  

E-print Network

from a scanned area. One should properly control the main opera- tion parameters of the FIBEffect of stage control parameters on the FIB milling process Joon Hyun Kim a,c , Jin-Hyo Boo b,c , Youn-Jea Kim a,c, a School of Mechanical Engineering, Sungkyunkwan University, Suwon 440-746, South

Boo, Jin-Hyo

152

Control of carbon nanotube stiffness via tunable fabrication process parameters that determine CNT geometry  

E-print Network

This paper presents tunable process parameters that may be used to control the geometry of multi-walled carbon nanotubes (MWCNTs). The results may be used to grow MWCNTs with desired stiffness properties. This is important ...

Cullinan, Michael A. (Michael Arthur)

2008-01-01

153

Effects of formulation, processing and storage parameters on the characteristics and stability of perflubron emulsion.  

PubMed

In this study, the effects of formulation, processing and storage parameters on perflubron (perfluorooctyl bromide; PFOB) emulsions were investigated. Emulsions with varying concentrations of perflubron and egg yolk phospholipid (EYP) were prepared with different processing parameters and placed at different storage temperatures. Their characteristics and stability were compared. The emulsion droplet growth rate was nearly proportional to the perflubron percentage in the range of 15-110% w/v. The initial droplet size of perflubron emulsions was inversely proportional to the concentration of EYP until a certain lower limit of droplet size was reached. The initial droplet size and droplet growth rate of perflubron emulsion were strongly dependent upon the processing parameters. The logarithmic value of the droplet growth rate decreased linearly with l/T in the range of 5-40 degrees C. The formulation and processing parameters are the key variables to be optimized to achieve better emulsion characteristics and stability. PMID:7849938

Ni, Y; Pelura, T J; Sklenar, T A; Kinner, R A; Song, D

1994-01-01

154

Process technology and design parameter impact on SRAM Bit-Cell Sleep effectiveness  

Microsoft Academic Search

SRAM Bit-Cell Sleep technique is extensively used in processors to minimize SRAM leakage power. However, magnitude of leakage power savings from SRAM bit-cell sleep technique is dependent on process technology and various design parameters. This paper analyzes influence of design parameters like VCCMIN_RET, DVS, ITD and NBTI on effectiveness of SRAM bit-cell sleep scheme. Impact of Process Technology on SRAM

Guru Shamanna; B. S. Kshatri; R. Gaurav; Y. S. Tew; P. Marfatia; Y. Raghavendra; V. Naik

2010-01-01

155

The effect of processing parameters on oil content of corn tortilla chips  

E-print Network

THE EFFECT OF PROCESSING PARAMETERS ON OIL CONTENT OF CORN TORTILLA CHIPS A Thesis by PETA ROCK DUDLEY Submitted to the Office of Graduate Studies of Texas ASM University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE August 1993 Major Subject: Food Science and Technology THE EFFECT OF PROCESSING PARAMETERS ON OIL CONTENT OF CORN TORTILLA CHIPS A Thesis by PETA ROCK DUDLEY Approved as to style and content by: LI yd W. Rooney (Chair of Committee...

Dudley, Peta Rock

2012-06-07

156

Optimizing process parameters for selective laser sintering based on neural network and genetic algorithm  

Microsoft Academic Search

Selective laser sintering (SLS) is an attractive rapid prototyping (RP) technology capable of manufacturing parts from a variety\\u000a of materials. However, the wider application of SLS has been limited, due to their accuracy. This paper presents an optimal\\u000a method to determine the best processing parameter for SLS by minimizing the shrinkage. According to the nonlinear and multitudinous\\u000a processing parameter feature

Wang Rong-Ji; Li Xin-hua; Wu Qing-ding; Wang Lingling

2009-01-01

157

Roles of the influential parameters in the incineration process using centrality concept of graph theory  

NASA Astrophysics Data System (ADS)

The dioxin furan is byproducts of the incineration process in which becomes a major concern to the public. In this paper, the role of the influential parameters affecting the Dioxin Furan Emission (DFE) in the incineration process was discussed. A total of seven selected incinerators in Malaysia were considered in the study. The incineration plant was categorized into the type of waste incinerated during the process, i.e. sludge and biomedical waste. Six parameters comprise of temperature, nitrogen oxide, sulphur dioxide, carbon dioxide, oxygen and moisture content were identified as the influential parameters affecting the DFE of the incineration process. Multiple Linear Regression (MLR) models were initially developed to relate the DFE and the influential parameters in each category of incinerators. These models served as the basis for the construction of the graphical models representing the interaction of the influential parameters in the process. Centrality concept was then used on these graphical models to describe the role of the parameters in the process.

Awatif, W. A.; Sabariah, B.; Rashid, M.; Normah, M.

2014-06-01

158

Processing-microstructure relationships for Ti6Al2Sn4Zr2Mo0.1Si  

Microsoft Academic Search

The detailed relationships between thermal-mechanical processing parameters and resulting microstructures for Ti-6Al-2Sn-4Zr-2Mo-0.1\\u000a Si (Ti-6242) have been established through compression testing and heat treatment. Beginning with either an equiaxed alpha\\u000a or Widmanst?tten alpha preform microstructure, isothermal compression tests were run at strain rates typical of isothermal\\u000a forging (10?3 to 10?1 s?1) and conventional forging (1 to 100 s?1). Metallographic investigation of

S. L. Semiatin; J. F. Thomas; P. Dadras

1983-01-01

159

High Temperature, Slow Strain Rate Forging of Advanced Disk Alloy ME3  

NASA Technical Reports Server (NTRS)

The advanced disk alloy ME3 was designed in the HSR/EPM disk program to have extended durability at 1150 to 1250 F in large disks. This was achieved by designing a disk alloy and process producing balanced monotonic, cyclic, and time-dependent mechanical properties. combined with robust processing and manufacturing characteristics. The resulting baseline alloy, processing, and supersolvus heat treatment produces a uniform, relatively fine mean grain size of about ASTM 7, with as-large-as (ALA) grain size of about ASTM 3. There is a long term need for disks with higher rim temperature capabilities than 1250 F. This would allow higher compressor exit (T3) temperatures and allow the full utilization of advanced combustor and airfoil concepts under development. Several approaches are being studied that modify the processing and chemistry of ME3, to possibly improve high temperature properties. Promising approaches would be applied to subscale material, for screening the resulting mechanical properties at these high temperatures. n obvious path traditionally employed to improve the high temperature and time-dependent capabilities of disk alloys is to coarsen the grain size. A coarser grain size than ASTM 7 could potentially be achieved by varying the forging conditions and supersolvus heat treatment. The objective of this study was to perform forging and heat treatment experiments ("thermomechanical processing experiments") on small compression test specimens of the baseline ME3 composition, to identify a viable forging process allowing significantly coarser grain size targeted at ASTM 3-5, than that of the baseline, ASTM 7.

Gabb, Timothy P.; OConnor, Kenneth

2001-01-01

160

Optimizing Friction Stir Welding via Statistical Design of Tool Geometry and Process Parameters  

NASA Astrophysics Data System (ADS)

This article considers optimization procedures for friction stir welding (FSW) in 5083-H321 aluminum alloy, via control of weld process parameters and tool design modifications. It demonstrates the potential utility of the "force footprint" (FF) diagram in providing a real-time graphical user interface (GUI) for process optimization of FSW. Multiple force, torque, and temperature responses were recorded during FS welding using 24 different tool pin geometries, and these data were statistically analyzed to determine the relative influence of a number of combinations of important process and tool geometry parameters on tensile strength. Desirability profile charts are presented, which show the influence of seven key combinations of weld process variables on tensile strength. The model developed in this study allows the weld tensile strength to be predicted for other combinations of tool geometry and process parameters to fall within an average error of 13%. General guidelines for tool profile selection and the likelihood of influencing weld tensile strength are also provided.

Blignault, C.; Hattingh, D. G.; James, M. N.

2012-06-01

161

Optimization of a Cu CMP process modeling parameters of nanometer integrated circuits  

NASA Astrophysics Data System (ADS)

A copper chemical mechanical polishing (Cu CMP) process is reviewed and analyzed from the view of chemical physics. Three steps Cu CMP process modeling is set up based on the actual process of manufacturing and pattern-density-step-height (PDSH) modeling from MIT. To catch the pattern dependency, a 65 nm testing chip is designed and processed in the foundry. Following the model parameter extraction procedure, the model parameters are extracted and verified by testing data from the 65 nm testing chip. A comparison of results between the model predictions and test data show that the former has the same trend as the latter and the largest deviation is less than 5 nm. Third party testing data gives further evidence to support the great performance of model parameter optimization. Since precise CMP process modeling is used for the design of manufacturability (DFM) checks, critical hotspots are displayed and eliminated, which will assure good yield and production capacity of IC.

Wenbiao, Ruan; Lan, Chen; Tianyu, Ma; Jingjing, Fang; He, Zhang; Tianchun, Ye

2012-08-01

162

Modelling of Viscoplastic Behaviour of IN718 Under Hot Forging Conditions  

SciTech Connect

The mechanical properties of IN718 are directly related to microstructure such as grain size and the hardening mechanisms, which are effective during thermomechanical processing and subsequent heat treatment. In this study a set of unified viscoplastic constitutive equations were determined for IN718 from experimental data of hot forging conditions. Techniques were developed to analyse the reliability and consistency of the experimental data derived from different previous publications. In addition to viscoplastic flow of the material, the determined material model can be used to predict the evolution of dislocations, recrystallisation and grain size occurring during thermomechanical processing.

Lin, Y. P.; Lin, J.; Dean, T. A. [Department of Mechanical and Manufacturing Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Brown, P. D. [Rolls-Royce plc, PO Box31, Derby DE24 8BJ (United Kingdom)

2007-04-07

163

Advanced rotor forgings for high-temperature steam turbines. Volume 2. Mechanical property evaluation. Final report. [CrMoV steels  

SciTech Connect

Three advanced steel-melting processes - low-sulfur vacuum silicon deoxidation, electroslag remelting, and vacuum carbon deoxidation (VCD) - were applied to produce three CrMoV (ASTM A470, Class 8) steel forgings for steam turbine application. Ingots weighing about 100 t each were produced using these three processes, and rotors were forged with final weights of about 30 t each. Compared to the conventionally produced forgings, the advanced technology forgings show better tensile ductility and better uniformity along the radial and longitudinal directions. Charpy upper-shelf energy shows about 40% improvement, and no temper embrittlement was found using step-cooled and isothermal-aging treatments. Significant improvement in fracture toughness (K/sub IC/ and J/sub IC/) is realized for these forgings. Low-cycle fatigue life is better at high temperatures because of the absence of nonmetallic inclusions. Creep strength shows slight improvement. However, creep ductility is improved, probably because of low residual elements. The VCD forgings show excellent creep ductility, even with long lives. Both the toughness and creep properties are equal to or better than those of oil-quenched rotors produced by European practices. These improvements are attributed to cleaner steel, better control of ingot solidification, low residual elements (especially very low sulfur content), and the associated reduction of nonmetallic inclusions. These three rotors have been placed in service in three operating power plants in units rated at 520 MW each. Volume 1 of this report covers ingot and forging production, and volume 2 covers mechanical property evaluation. 40 refs., 84 figs., 15 tabs.

Swaminathan, V.P.; Landes, J.D.

1986-05-01

164

The occurrence of shear bands in isothermal, hot forging  

NASA Astrophysics Data System (ADS)

The occurrence of shear bands in isothermal, hot forging of metals has been investigated using a variety of experimental and analytical tools. Isothermal sidepressing tests on Ti-6Al-2Sn-4Zr-2Mo-0. 1Si were conducted at a variety of hot working temperatures and deformation rates to develop a data base on the occurrence of shear bands as a function of material properties and processing conditions. An instability criterion was developed, and the tendency to form shear bands was shown to depend strongly on the ratio of the nondimensional work-hardening (or flow-softening) rate to the strain-rate sensitivity of the flow stress. This analysis and supporting experimental data formed the basis for the development of workability maps, which delineate safe regimes for hot working in terms of strain rate and temperature. Employing a sophisticated computer code, an extensive series of simulations was also run for the sidepressing operation to obtain an idea of the detailed process by which shear bands initiate. These simulations were conducted using actual Ti-6242 material properties as well as hypothetical properties which are representative of those of other metals deformed in the hot working regime. From these simulations, predictions of the influence of flow softening and rate sensitivity on flow localization were made and found to be similar to experimental results and predictions obtained from the instability analysis. However, process simulation gave a more complete insight into the initiation and growth stages in the development of shear bands that was not possible using only the instability analysis.

Semiatin, S. L.; Lahoti, G. D.

1982-02-01

165

Process parameter influence on performance of friction taper stud welds in AISI 4140 steel  

Microsoft Academic Search

Friction taper stud welding is a new variant of friction welding which has been developed from the principles of friction hydro-pillar processing. This paper considers the effect of weld process parameters on weld defects, macrostructure and mechanical properties in AISI 4140 steel. It also presents 3D residual stress data for a typical friction taper stud weld. Applied downwards force, rotational

D. G. Hattingh; D. L. H. Bulbring; A. Els-Botes; M. N. James

2011-01-01

166

A neural network system for the prediction of process parameters in pressure die casting  

Microsoft Academic Search

In this work an artificial intelligent neural network system is developed to generate the process parameters for the pressure die casting process. The scope of this work includes analysing a physical model of the pressure die casting filling stage based on the governing equations of die cavity filling, and the collection of feasible casting data for the training of the

Prasad K. D. V. Yarlagadda; Eric Cheng Wei Chiang

1999-01-01

167

Effective parameters in axial injection suspension plasma spray process of alumina-zirconia ceramics  

E-print Network

Effective parameters in axial injection suspension plasma spray process of alumina- zirconia/CDN Suspension Plasma Spray (SPS) is a novel process for producing nano-structured coatings with metastable plasma spray conditions and resulting coating microstructure and defects. In this study, an alumina/ 8 wt

Medraj, Mamoun

168

Multi-Response Optimization of Process Parameters for Low-Pressure Cold Spray Coating Process Using Taguchi and Utility Concept  

NASA Astrophysics Data System (ADS)

Most of the existing multi-response optimization approaches focus on the subjective and practical know-how of the process. As a result, some confusion and uncertainty are introduced in the overall decision-making process. In this work, an approach based on a Utility theory and Taguchi quality loss function has been applied to the process parameters for low-pressure cold spray process deposition of copper coatings, for simultaneous optimization of more than one response characteristics. In the present paper, two potential response parameters, i.e., coating thickness and coating density, have been selected. Utility values based on these response parameters have been analyzed for optimization using the Taguchi approach. The selected input parameters of powder feeding arrangement, substrate material, air stagnation pressure, air stagnation temperature, and stand-off distance significantly improve the Utility function (raw data) comprising quality characteristics (coating thickness and coating density). The percentage contribution of the parameters to achieve a higher value of Utility function is substrate material (50.03%), stand-off distance (28.87%), air stagnation pressure (6.41%), powder feeding arrangement (4.68%), and air stagnation temperature (2.64%).

Goyal, Tarun; Sidhu, T. S.; Walia, R. S.

2014-01-01

169

Processing parameter effects on solution precursor plasma spray process spray patterns  

Microsoft Academic Search

Solution precursor plasma spray (SPPS) is a promising process for making thermal barrier coatings (TBCs) with improved durability. The improved durability of SPPS TBCs results from the novel microstructural features, (i) absence of splat boundaries, (ii) generation of through-thickness vertical cracks (iii) existence of uniformly distributed porosity. In this process, the coating is built up by the overlapping and stacking

Liangde Xie; Xinqing Ma; Alper Ozturk; Eric H. Jordan; Nitin P. Padture; Baki M. Cetegen; Danny T. Xiao; Maurice Gell

2004-01-01

170

Mechanistic basis for the effects of process parameters on quality attributes in high shear wet granulation.  

PubMed

Three model compounds were used to study the effect of process parameters on in-process critical material attributes and a final product critical quality attribute. The effect of four process parameters was evaluated using design of experiment approach. Batches were characterized for particle size distribution, density (porosity), flow, compaction, and dissolution rate. The mechanisms of the effect of process parameters on primary granule properties (size and density) were proposed. Water amount showed significant effect on granule size and density. The effect of impeller speed was dependent on the granule mechanical properties and efficiency of liquid distribution in the granulator. Blend density was found to increase rapidly during wet massing. Liquid addition rate was the least consequential factor and showed minimal impact on granule density and growth. Correlations of primary properties with granulation bulk powder properties (compaction and flow) and tablet dissolution were also identified. The effects of the process parameters on the bulk powder properties and tablet dissolution were consistent with their proposed link to primary granule properties. Understanding the impact of primary granule properties on bulk powder properties and final product critical quality attributes provides the basis for modulating granulation parameters in order to optimize product performance. PMID:22981985

Badawy, Sherif I F; Narang, Ajit S; LaMarche, Keirnan; Subramanian, Ganeshkumar; Varia, Sailesh A

2012-12-15

171

On selecting a prior for the precision parameter of Dirichlet process mixture models  

USGS Publications Warehouse

In hierarchical mixture models the Dirichlet process is used to specify latent patterns of heterogeneity, particularly when the distribution of latent parameters is thought to be clustered (multimodal). The parameters of a Dirichlet process include a precision parameter ?? and a base probability measure G0. In problems where ?? is unknown and must be estimated, inferences about the level of clustering can be sensitive to the choice of prior assumed for ??. In this paper an approach is developed for computing a prior for the precision parameter ?? that can be used in the presence or absence of prior information about the level of clustering. This approach is illustrated in an analysis of counts of stream fishes. The results of this fully Bayesian analysis are compared with an empirical Bayes analysis of the same data and with a Bayesian analysis based on an alternative commonly used prior.

Dorazio, R. M.

2009-01-01

172

FATIGUE PERFORMANCE COMPARISON AND LIFE PREDICTION OF FORGED STEEL AND DUCTILE CAST IRON CRANKSHAFTS  

E-print Network

1 FATIGUE PERFORMANCE COMPARISON AND LIFE PREDICTION OF FORGED STEEL AND DUCTILE CAST IRON. The crankshafts used in the study were forged steel and ductile cast iron from a one-cylinder gasoline engine fatigue strength than the ductile cast iron, while component tests showed that the forged steel crankshaft

Fatemi, Ali

173

Effects of layer thickness and binder saturation level parameters on 3D printing process  

Microsoft Academic Search

Various parameters, such as binder properties, printing layer thickness, powder size, and binder saturation level, have effects\\u000a on the strength and surface finish of the three-dimensional printing (3D printing) process. The objective of this research\\u000a is to study the effects of two parameters of layer thickness and binder saturation level on mechanical strength, integrity,\\u000a surface quality, and dimensional accuracy in

Mohammad Vaezi; Chee Kai Chua

2011-01-01

174

Taguchi’s optimization of process parameters for production accuracy in ultrasonic drilling of engineering ceramics  

Microsoft Academic Search

This paper presents a study of the effect of process parameters on production accuracy obtained through ultrasonic drilling\\u000a of holes in alumina based ceramics using silicon carbide abrasive. Production accuracy in ultrasonic drilling involves both\\u000a dimensional accuracy (hole oversize) and form accuracy (out-of-roundness and conicity). The parameters considered are workpiece\\u000a material, tool material, grit size of the abrasive, power rating

R. S. Jadoun; Pradeep Kumar; B. K. Mishra

2009-01-01

175

Vacuum plasma spray forming of Astroloy: An investigation of processing parameters  

SciTech Connect

A Taguchi experimental design study was conducted to define relationships between spray parameters and microstructural properties of thermally sprayed deposits (i.e., thickness, porosity level, microhardness, and deposition efficiency) and estimate the influence of the parameters on the spray forming process. In addition, the influence of the substrate morphology on the deposit characteristics (particularly the influence of the spray-angle) were investigated. The influence of the spray parameters and the spray angles on the shapes of the flattened particles have been linked to the coating properties.

Montavon, G.; Coddet, C. [LERMPS-Institut Polytechnique de Sevenans, Belfort (France); Sampath, S.; Herman, H.; Berndt, C.C. [State Univ. of New York, Stony Brook, NY (United States)

1994-12-31

176

Phase Evolution in Fe-Mn-Si Shape Memory Alloys due to Forging Speed  

NASA Astrophysics Data System (ADS)

The objective of this investigation is to compare the crystallographic characteristics of two different compositions of Fe-Mn-Si alloys forged with the newly designed and constructed High Energy Rate Forming (HERF) hammer with conventional hydraulic and mechanical presses. The degree of martensite formation may depend on metal forming conditions. For both of the alloys, one of the specimens was investigated in as "prepared form", the other specimen was investigated after air cooling with homogenization treatment and three specimens were deformed in different velocities after homogenization treatments. The changes which occurred in the transformation parameters of two FeMnSi alloys with different compositions due to the effects of thermal and mechanical procedures have been studied by using X-ray diffraction. In the alloy specimens cooled to different conditions from the high-temperature ? phase region, ??? and ?????? martensitic transformations were observed. The lattice parameters (LP) of fcc ? and hcp ? structures were determined, and changes in forging speed on the LPs were found.

Eskil, Murat; Kanca, Erdogan

2013-09-01

177

TECHNICAL NOTE: Adhesive bonding of microfluidic chips: influence of process parameters  

NASA Astrophysics Data System (ADS)

In this note, the influence of process parameters for adhesive bonding as a versatile approach for the sealing of polymer microfluidic chips is investigated. Specifically, a process chain comprising pre-processing, adhesive transfer as well as post-processing is presented and parameter recommendations are provided. As a device for adhesive transfer, a modified laminator is utilized which transfers thin layers of adhesive onto the chip surface, only via a silicone roll. Using this device and a high temperature (Tg > 100 °C) epoxy adhesive, adhesive layers in the range of 2-4 µm can be reproducibly transferred (CV < 4%). For best bonding results, it is recommended to provide 2.5 µm thin layers of adhesive in combination with a subsequent evacuation step at 10 mbar for 3 h. Further, it is proposed to integrate capture channels near large, featureless areas to compensate for variations in processing and thus prevent clogging of channels.

Riegger, Lutz; Strohmeier, Oliver; Faltin, Bernd; Zengerle, Roland; Koltay, Peter

2010-08-01

178

Intelligent Modeling Combining Adaptive Neuro Fuzzy Inference System and Genetic Algorithm for Optimizing Welding Process Parameters  

NASA Astrophysics Data System (ADS)

Modified 9Cr-1Mo ferritic steel is used as a structural material for steam generator components of power plants. Generally, tungsten inert gas (TIG) welding is preferred for welding of these steels in which the depth of penetration achievable during autogenous welding is limited. Therefore, activated flux TIG (A-TIG) welding, a novel welding technique, has been developed in-house to increase the depth of penetration. In modified 9Cr-1Mo steel joints produced by the A-TIG welding process, weld bead width, depth of penetration, and heat-affected zone (HAZ) width play an important role in determining the mechanical properties as well as the performance of the weld joints during service. To obtain the desired weld bead geometry and HAZ width, it becomes important to set the welding process parameters. In this work, adaptative neuro fuzzy inference system is used to develop independent models correlating the welding process parameters like current, voltage, and torch speed with weld bead shape parameters like depth of penetration, bead width, and HAZ width. Then a genetic algorithm is employed to determine the optimum A-TIG welding process parameters to obtain the desired weld bead shape parameters and HAZ width.

Gowtham, K. N.; Vasudevan, M.; Maduraimuthu, V.; Jayakumar, T.

2011-04-01

179

Analysis of Process Parameters Affecting Spray-Dried Oily Core Nanocapsules Using Factorial Design  

Microsoft Academic Search

The purpose of this work was to optimize the process parameters required for the production of spray-dried oily core nanocapsules\\u000a (NCs) with targeted size and drug yield using a two-level four-factor fractional factorial experimental design (FFED). The\\u000a coded process parameters chosen were inlet temperature (X\\u000a 1), feed flow rate (X\\u000a 2), atomizing air flow (X\\u000a 3), and aspiration rate (X

Tao Zhang; Bi-Botti C. Youan

2010-01-01

180

Parameter estimation by fixed point of function of information processing intensity  

NASA Astrophysics Data System (ADS)

We present a new method of estimating the dispersion of a distribution which is based on the surprising property of a function that measures information processing intensity. It turns out that this function has a maximum at its fixed point. Fixed-point equation is used to estimate the parameter of the distribution that is of interest to us. The main result consists in showing that only part of available experimental data is relevant for the parameters estimation process. We illustrate the estimation method by using the example of an exponential distribution.

Jankowski, Robert; Makowski, Marcin; Piotrowski, Edward W.

2014-12-01

181

The effects of process parameters on injection-molded PZT ceramics part fabrication- compounding process rheology.  

SciTech Connect

Solid solutions of lead-based perovskites are the backbone materials of the piezoelectric components for transducer, actuator, and resonator applications. These components, typically small in size, are fabricated from large sintered ceramic slugs using grinding and lapping processes. These operations increase manufacturing costs and produce a large hazardous waste stream, especially when component size decreases. To reduce costs and hazardous wastes associated with the production of these components, an injection molding technique is being investigated to replace the machining processes. The first step in the new technique is to compound an organic carrier with a ceramic powder. The organic carrier is a thermoplastic based system composed of a main carrier, a binder, and a surfactant. Understanding the rheology of the compounded material is necessary to minimize the creation of defects such as voids or cavities during the injection-molding process. An experiment was performed to model the effects of changes in the composition and processing of the material on the rheological behavior. Factors studied included: the surfactant of the organic carrier system, the solid loading of the compounded material, and compounding time. The effects of these factors on the viscosity of the material were investigated.

Halbleib, Laura L.; Yang, Pin; Mondy, Lisa Ann; Burns, George Robert

2005-05-01

182

Forging an Identity over the Life-Course  

ERIC Educational Resources Information Center

Using a social constructionist approach, this study explores the self-perceptions of young men who, when at school, were classed as boys with social, emotional and behavioural difficulties (SEBD). The aim is to understand how these perceptions were forged throughout the young men's life-courses resulting in changing self-identities. The study also…

Spiteri, Damian

2009-01-01

183

Electronic Portfolios in Teacher Education: Forging a Middle Ground  

ERIC Educational Resources Information Center

At a time when implementation of electronic portfolios (EPs) is expanding, the issues of clarifying their purposes continue to plague teacher education programs. Are student-centered uses of EPs compatible with program assessment and accreditation efforts? Is this an either/or situation, or can a productive middle ground be forged? This article…

Strudler, Neal; Wetzel, Keith

2012-01-01

184

Forging Consensus for Implementing Youth Socialization Policy in Northwest China  

ERIC Educational Resources Information Center

The goal of this article is to examine how the provincial education media in China play a role of forging consensus among local actors responsible for the implementation of new centrally-promulgated youth socialization policy. In doing so, it also explores the tension among three of the Chinese state's claims to legitimacy: economic development,…

Fairbrother, Gregory P.

2011-01-01

185

The Valley Forge Encampment: Epic on the Schuylkill.  

ERIC Educational Resources Information Center

Valley Forge, outside Philadelphia (Pennsylvania), has long been recognized as the site of a great victory of the human spirit. Eleven thousand men including Blacks and Indians resided there during the winter of 1777-78 and triumphed over cold, starvation, nakedness, disease, and uncertainty. The encampment site was unprepared for the tattered,…

Trussell, John B. B., Jr.

186

Family Health and Financial Literacy--Forging the Connection  

ERIC Educational Resources Information Center

Families are at-risk of or experiencing a diminished quality of living and life in current economic times and difficult decisions are required. Health and financial literacy are the basis for wise personal and public decision making. Family and consumer sciences (FCS) professionals can forge connections between health and financial literacy to…

Braun, Bonnie; Kim, Jinhee; Anderson, Elaine A.

2009-01-01

187

Effect of Combustion Air Preheat on a Forged Furnace Productivity  

E-print Network

A basic thermal analysis of a gas fired forge furnace can determine the fuel savings from exhaust energy recovery/combustion air preheat on a furnace operating at a single condition, for example, high fire. What this analysis is not able...

Ward, M. E.; Bohn, J.; Davis, S. R.; Knowles, D.

1984-01-01

188

Forging Attacks on two Authenticated Encryptions COBRA and POET  

E-print Network

Forging Attacks on two Authenticated Encryptions COBRA and POET Mridul Nandi Indian Statistical COBRA [4], based on pseudorandom per- mutation (PRP) blockcipher, and POET [3], based on Almost XOR-Universal (AXU) hash and strong pseudorandom permutation (SPRP), were proposed. Few weeks later, COBRA mode

189

Optimization of LPDC Process Parameters Using the Combination of Artificial Neural Network and Genetic Algorithm Method  

NASA Astrophysics Data System (ADS)

In this article, the low-pressure die-cast (LPDC) process parameters of aluminum alloy thin-walled component with permanent mold are optimized using a combining artificial neural network and genetic algorithm (ANN/GA) method. In this method, an ANN model combining learning vector quantization (LVQ) and back-propagation (BP) algorithm is proposed to map the complex relationship between process conditions and quality indexes of LPDC. The genetic algorithm is employed to optimize the process parameters with the fitness function based on the trained ANN model. Then, by applying the optimized parameters, a thin-walled component with 300 mm in length, 100 mm in width, and 1.5 mm in thickness is successfully prepared and no obvious defects such as shrinkage, gas porosity, distortion, and crack were found in the component. The results indicate that the combining ANN/GA method is an effective tool for the process optimization of LPDC, and they also provide valuable reference on choosing the right process parameters for LPDC thin-walled aluminum alloy casting.

Zhang, Liqiang; Li, Luoxing; Wang, Shiuping; Zhu, Biwu

2012-04-01

190

Evaluation of Tensile Deformation Properties of Friction Stir Processed Pure Copper: Effect of Processing Parameters and Pass Number  

NASA Astrophysics Data System (ADS)

In this work, the tensile behavior of pure copper including ultimate tensile stress, yield stress, and elongation in the specimens friction stir processed under different processing parameters and pass adding was investigated in detail. The effect of strain hardening, grain refinement, and heat input on the tensile properties of these specimens was explained as well. It was observed that, regarding the aforementioned factors, the processing parameters and pass number could have considerable effects on the tensile deformation properties of the pure copper such as 300 and 47% enhancements in elongation and ultimate strength, respectively. It was demonstrated that higher passes resulted in the development of ultrafine grains (up to 700-800 nm) in the specimens. The fracture surface morphology was also used to further support the elongation results.

Barmouz, Mohsen; Besharati Givi, Mohammad Kazem; Jafari, Jalal

2014-01-01

191

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

192

Impacts of process parameters on CIGS solar cells prepared by selenization process with Se Vapor  

Microsoft Academic Search

The CuIn1-xGaxSe2 (CIGS) films are prepared by the selenization process including the deposition of the metal precursors followed by heating the metal precursors in a Se overpressure. The impacts of Se deposition rates on the morphology, grain growth, and atomic ratios of the resulting CIGS films are investigated. The CIGS films prepared at the high Se flow rate exhibit the

Chia-Hua Huang; Y. C. Shih; Wen-Jie Chuang; Chun-Ping Lin

2010-01-01

193

Effects of process parameters on surface roughness in abrasive waterjet cutting of aluminium  

NASA Astrophysics Data System (ADS)

Abrasive waterjet cutting is a novel machining process capable of processing wide range of hard-to-cut materials. Surface roughness of machined parts is one of the major machining characteristics that play an important role in determining the quality of engineering components. This paper shows the influence of process parameters on surface roughness ( R a) which is an important cutting performance measure in abrasive waterjet cutting of aluminium. Taguchi's design of experiments was carried out in order to collect surface roughness values. Experiments were conducted in varying water pressure, nozzle traverse speed, abrasive mass flow rate and standoff distance for cutting aluminium using abrasive waterjet cutting process. The effects of these parameters on surface roughness have been studied based on the experimental results.

Chithirai Pon Selvan, M.; Mohana Sundara Raju, N.; Sachidananda, H. K.

2012-12-01

194

Parameter comparison of two small-scale natural gas liquefaction processes in skid-mounted packages  

Microsoft Academic Search

Two typical types of small-scale natural gas liquefaction process in skid-mounted package were designed and simulated. The key parameters of the two processes were compared, and the matching of the heating and cooling curves in heat exchangers was also analyzed. The results show that the N2–CH4 expander cycle precedes the mixed-refrigerant cycle on the premise of lacking propane pre-cooling. Large

Wen-sheng Cao; Xue-sheng Lu; Wen-sheng Lin; An-zhong Gu

2006-01-01

195

Effect of processing parameters on the microstructure and mechanical properties of Al–steel composite foam  

Microsoft Academic Search

Al–steel composite foams comprise of steel hollow spheres embedded in an aluminum matrix and are processed using a gravity\\u000a casting technique. The effect of processing parameters such as casting temperature and cooling rate on the microstructure\\u000a and mechanical behavior was studied to establish structure–property relationships. Results show that the amount and composition\\u000a of intermetallic phases present in the foam microstructure

L. J. Vendra; J. A. Brown; A. Rabiei

2011-01-01

196

Effects of Melt Pool Variables and Process Parameters in Laser Direct Metal Deposition of Aerospace Alloys  

Microsoft Academic Search

Despite considerable advances in of laser direct metal deposition (LDMD) process optimization, there is rather limited work reported on the effects of melt pool variables on the final deposit characteristics. This article considers the effects of process parameters and melt pool characteristics on the deposition of Inconel 718 powder on a Ti-6Al-4 V thin wall. A 1.5 kW diode laser and LDMD

Kamran Shah; Andrew J. Pinkerton; Ahmad Salman; Lin Li

2010-01-01

197

Effects of process parameters on granules properties produced in a high shear granulator  

Microsoft Academic Search

Results of a study on the influence of process parameters such as impeller speed, granulation time and binder viscosity on granule strength and properties are reported. A high shear granulator (Cyclomix manufactured by Hosokawa Micron B.V., The Netherlands) has been used to produce granules. Calcium carbonate (Durcal) was used as feed powder and aqueous polyethylene glycol (PEG) as the binder.

Nejat Rahmanian; Ayman Naji; Mojtaba Ghadiri

2011-01-01

198

Process parameters optimization for friction stir welding of RDE40 aluminium alloy using Taguchi technique  

Microsoft Academic Search

Taguchi approach was applied to determine the most influential control factors which will yield better tensile strength of the joints of friction stir welded RDE-40 aluminium alloy. In order to evaluate the effect of process parameters such as tool rotational speed, traverse speed and axial force on tensile strength of friction stir welded RDE-40 aluminium alloy, Taguchi parametric design and

A. K. LAKSHMINARAYANAN; V. BALASUBRAMANIAN

2008-01-01

199

Estimating dynamic transmission parameters of the SIR model based on a kernel-based Gaussian process  

NASA Astrophysics Data System (ADS)

In this paper a new approach for estimating parameters used in the SIR model is given. The Gaussian processes is used for modeling fluctuation of the new infected individuals. We introduce a Gaussian kernel for measuring the correlation within the reported new infected individuals. Numerical results show that the proposed method gives stable estimation with respect to noise level of the new infected data.

Indratno, S. W.; Shabrina, A.

2014-02-01

200

Effect of process parameters on the production of nanocrystalline silicon carbide from water glass  

Microsoft Academic Search

Nanocrystalline silicon carbide was synthesized from the precursor prepared by spray drying slurry of water glass and carbon black. The effect of process parameters, such as reaction temperature, reaction time and carbon content, on phase evolution, crystallite size and specific surface of the resulting samples were characterized by XRD, SEM and BET. The results show the powder produced in this

Shunlong Pan; Jingjie Zhang; Yanfeng Yang; Guangzhi Song

2008-01-01

201

Correlation of Selected Cognitive Abilities and Cognitive Processing Parameters: An Exploratory Study.  

ERIC Educational Resources Information Center

This pilot study investigated some relationships between tested ability variables and processing parameters obtained from memory search and visual search tasks. The 25 undergraduates who participated had also participated in a previous investigation by Chiang and Atkinson. A battery of traditional ability tests and several film tests were…

Snow, Richard E.; And Others

202

A neural network approach for selection of powder metallurgy materials and process parameters  

Microsoft Academic Search

The artificial neural network (NN) methodology presented in this paper has been developed for selection of powder and process parameters for Powder Metallurgy (PM) part manufacture. This methodology differs from the statistical modelling of mechanical properties in that it is not necessary to make assumptions regarding the form of the functions relating input and output variables. Employment of a NN

R. P. Cherian; L. N. Smith; P. S. Midha

2000-01-01

203

Influence of the processing parameters of slurries for the deposit of nickelate thick films  

SciTech Connect

Thick films cathodes for Solid Oxide Fuel Cells (SOFC) are prepared by dip-coating slurries made of several lanthanum nickelate oxide powders onto yttria stabilized zirconia (YSZ) substrates. The processing parameters for the slurries preparation and the multilayers coating have been optimized to obtain homogeneous, crack-free, thick and adherent films after heat treatment.

Castillo, S. [CIRIMAT Laboratory, UMR CNRS 5085, Paul Sabatier University, 118 route de Narbonne, 31062 Toulouse cedex 4 (France)], E-mail: castillo@chimie.ups-tlse.fr; Cienfuegos, R.F. [CIRIMAT Laboratory, UMR CNRS 5085, Paul Sabatier University, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Fontaine, M.L. [SINTEF, Pb. 124 Blindern, NO-0314 Oslo (Norway); Lenormand, P. [CIRIMAT Laboratory, UMR CNRS 5085, Paul Sabatier University, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Bacchin, P. [LGC UMR CNRS 5503, Paul Sabatier University, 118 route de Narbonne, 31062 Toulouse cedex 4 (France); Ansart, F. [CIRIMAT Laboratory, UMR CNRS 5085, Paul Sabatier University, 118 route de Narbonne, 31062 Toulouse cedex 4 (France)

2007-12-04

204

Effects of process parameters on solid self-microemulsifying particles in a laboratory scale fluid bed.  

PubMed

The purpose of this study was to select the critical process parameters of the fluid bed processes impacting the quality attribute of a solid self-microemulsifying (SME) system of albendazole (ABZ). A fractional factorial design (2(4-1)) with four parameters (spray rate, inlet air temperature, inlet air flow, and atomization air pressure) was created by MINITAB software. Batches were manufactured in a laboratory top-spray fluid bed at 625-g scale. Loss on drying (LOD) samples were taken throughout each batch to build the entire moisture profiles. All dried granulation were sieved using mesh 20 and analyzed for particle size distribution (PSD), morphology, density, and flow. It was found that as spray rate increased, sauter-mean diameter (D(s)) also increased. The effect of inlet air temperature on the peak moisture which is directly related to the mean particle size was found to be significant. There were two-way interactions between studied process parameters. The main effects of inlet air flow rate and atomization air pressure could not be found as the data were inconclusive. The partial least square (PLS) regression model was found significant (P < 0.01) and predictive for optimization. This study established a design space for the parameters for solid SME manufacturing process. PMID:21284578

Mukherjee, Tusharmouli; Plakogiannis, Fotios M

2012-01-01

205

Optimization of plastics injection molding processing parameters based on the minimization of sink marks  

Microsoft Academic Search

In order to avoid the surface sink marks on the automobile dashboard decorative covers, the combined effects of multi-molding process parameters are analyzed by the combination of orthogonal experiments and Moldflow simulation tests. By this method, it can gain the experiment data which can reflect the overall situation using fewer number of simulation test. Furthermore, the effects degree of different

Zhao Longzhi; Chen Binghui; Li Jianyun; Zhang Shangbing

2010-01-01

206

Optimal adaptive LQG control for systems with finite state process parameters  

Microsoft Academic Search

The situation where a totally observed process yt is generated by a stochastic differential equation whose parameters evolve on a finite set {1,....N} according to a stochastic differential equation is considered. The optimal control law is sought with respect to quadratic loss functions on yt and the control ut. The auxilliary P.D.E. technique of Hijab [1983] is used together with

P. E. Caines; H. F. Chen

1984-01-01

207

Orthogonal experiment and analysis on process parameters of bowl feed polishing (BFP)  

NASA Astrophysics Data System (ADS)

With the development of science and technology, the demand for high-precision product is increasing continuously. Ultra-smooth surface with sub-nanometer roughness has extensive applications in the field of soft X-ray optics, high power laser and laser gyro. Bowl feed polishing (BFP) technology is an effective ultra-smooth surface processing method, but the polishing process of BFP which is affected by a lot of factors is extremely complex and difficult to control. It is important to understand the effect of the process variables such as abrasive particle size, concentration of abrasive particle, speed of polishing pad, acidity and polishing time in the process of BFP. They are very important parameters that must be carefully formulated to achieve desired material removal rates and surface roughness. Using a design of experiment (DOE) approach, this study was performed investigating the main effect of the each parameter during K9 BFP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate and surface roughness is achieved by using the statistical analysis techniques. In the experimental tests, the optimized parameters combination for BFP which were derived from the statistical analysis could be found for material removal rate and better surface roughness through the above experiment results.

Meng, Kai; Wan, Yongjian; Xu, Qinglan; Yang, Yang

2013-08-01

208

EFFECTS OF PROCESS PARAMETERS ON TENSILE STRENGTH OF JUTE FIBER REINFORCED THERMOPLASTIC COMPOSITES  

Microsoft Academic Search

For Environmental concern on synthetic fibers (such as glass, carbon, ceramic fibers, etc.) natural fibers such as flax, hemp, jute, kenaf, etc. are widely used. In this research work, jute fiber reinforced polypropylene matrix composites have been developed by hot compression molding technique with varying process parameters, such as fiber condition (untreated and alkali treated), fiber sizes (1, 2 and

M. M. A. Rashed; M. A. Islam; F. B. Rizvi

2006-01-01

209

Optimization of Process Parameters in CFRP Machining with Diamond Abrasive Cutters  

E-print Network

Optimization of Process Parameters in CFRP Machining with Diamond Abrasive Cutters Aude BOUDELIER.garnier@irccyn.ec-nantes.fr, benoit.furet@irccyn.ec-nantes.fr Keywords: CFRP laminate composite; trimming; diamond abrasive cutter roughness. Feedrate must respect cutting limitations due to CFRP removal mechanisms with abrasive cutters

Paris-Sud XI, Université de

210

Effect of composition and process parameters on elasticity and solidity of foamed food  

Microsoft Academic Search

The objective was to investigate the impact of formulation and process parameters on the ability of food emulsions to form stabilized whipped emulsions under steady-state flow conditions using small-deformation rheological analysis. Three kinds of food emulsions were studied; formulation and operating conditions were modified in order to increase foam solidity which was strongly correlated to the stability of food microstructure.

Rajeev K. Thakur; Ch. Vial; G. Djelveh

2008-01-01

211

The Green-Kubo formula for general Markov processes with continuous time parameter  

E-print Network

The Green-Kubo formula for general Markov processes with continuous time parameter Fengxia Yanga@math.pku.edu.cn (Corresponding author) Abstract Without restriction of reversibility, the Green-Kubo formula for Markov pro in infinite dimensional spaces (irreversible for most cases) are shown to satisfy the Green-Kubo formula

Lu, Tiao

212

Parameter Distributions for Speech Signals Modeled with Spherically-Invariant Random Processes  

E-print Network

for co-channel speech sep- aration and compare to a database of actual speech signals [5]. II. UsingParameter Distributions for Speech Signals Modeled with Spherically-Invariant Random Processes (SIRPs) have been used as a statistical model for speech and shown to better fit mea- sured probability

De Leon, Phillip

213

Determination of a suitable parameter field for the active fluid jet polishing process  

NASA Astrophysics Data System (ADS)

In 2012 a well-known company in the field of high precision optics assigned the University of Applied Sciences Deggendorf to determine a suitable parameter field for the active fluid jet polishing (AFJP) process in order to reach a surface accuracy of at least lambda / 5. The active fluid jet polishing is a relatively new and an affordable sub-aperture polishing process. For a fast and precise identification of the parameter field a considered design of experiment is necessary. The available control variables were the rotational speed of the nozzle, the distance between the test object and the jet, the feed rate, the material of the pin inside the nozzle and the material of the test object itself. In order to reach a significant data density on the one hand and to minimize the number of test runs on the other hand a meander shaped tool path was chosen. At each blank nine paths had been driven whereby at each path another parameter combination was picked. Thus with only one test object nine parameter settings may be evaluated. For the automatized analysis of the tracks a software tool was developed. The software evaluates ten sections which orthogonally intersect the nine tracks on the test-lens. The significant measurement parameters per section are the width and the height of each path as well as the surface roughness within the polished tracks. With the aid of these parameters and further statistical evaluations a suitable parameter field for the goal to find a constant and predictable removal spot was determined. Furthermore up to now over 60 test runs have been successfully finished with nine parameter combinations in each case. As a consequence a test evaluation by hand would be very time-consuming and the software facilitates it dramatically.

Maurer, Roland; Biskup, Heiko; Trum, Christian; Rascher, Rolf; Wünsche, Christine

2013-09-01

214

The effect of shear bands on service properties of ti-6ai-2sn-4zr-2mo-0.1si forgings  

NASA Astrophysics Data System (ADS)

The effect of shear bands on the elevated temperature tensile, creep, and fatigue properties of Ti-6Al-2Sn-4Zr-2Mo-0. ISi (Ti-6242) forgings has been established. Evaluations on forgings containing and not containing shear bands demonstrated that the effect is very small if not negligible in tensile and fatigue loading. For these types of loading, observations were explainable on the basis of the fact that the shear bands are regions of somewhat higher hardness than the remainder of the forging, and, thus, failure tended to nucleate away from the shear bands. In contrast, shear bands had a noticeable effect on stress-rupture properties. The deleterious effects under this type of loading were ascribed to microscopic processes such as enhanced diffusion along shear bands.

Semiatin, S. L.; Lahoti, G. D.

1983-03-01

215

Identification of sensitive parameters in the modeling of SVOC reemission processes from soil to atmosphere.  

PubMed

Semi-volatile organic compounds (SVOCs) are subject to Long-Range Atmospheric Transport because of transport-deposition-reemission successive processes. Several experimental data available in the literature suggest that soil is a non-negligible contributor of SVOCs to atmosphere. Then coupling soil and atmosphere in integrated coupled models and simulating reemission processes can be essential for estimating atmospheric concentration of several pollutants. However, the sources of uncertainty and variability are multiple (soil properties, meteorological conditions, chemical-specific parameters) and can significantly influence the determination of reemissions. In order to identify the key parameters in reemission modeling and their effect on global modeling uncertainty, we conducted a sensitivity analysis targeted on the 'reemission' output variable. Different parameters were tested, including soil properties, partition coefficients and meteorological conditions. We performed EFAST sensitivity analysis for four chemicals (benzo-a-pyrene, hexachlorobenzene, PCB-28 and lindane) and different spatial scenari (regional and continental scales). Partition coefficients between air, solid and water phases are influent, depending on the precision of data and global behavior of the chemical. Reemissions showed a lower variability to soil parameters (soil organic matter and water contents at field capacity and wilting point). A mapping of these parameters at a regional scale is sufficient to correctly estimate reemissions when compared to other sources of uncertainty. PMID:24954563

Loizeau, Vincent; Ciffroy, Philippe; Roustan, Yelva; Musson-Genon, Luc

2014-09-15

216

Meltlets® of Soy Isoflavones: Process Optimization and the Effect of Extrusion Spheronization Process Parameters on Antioxidant Activity  

PubMed Central

In the current research work an attempt was made to develop “Melt in mouth pellets” (Meltlets®) containing 40% herbal extract of soy isoflavones that served to provide antioxidants activity in menopausal women. The process of extrusion–spheronization was optimized for extruder speed, extruder screen size, spheronization speed, and time. While doing so the herbal extract incorporated in the pellet matrix was subjected to various processing conditions such as the effect of the presence of other excipients, mixing or kneading to prepare wet mass, heat generated during the process of extrusion, spheronization, and drying. Thus, the work further investigates the effect of these processing parameters on the antioxidant activity of the soy isoflavone herbal extract incorporated in the formula. Thereby, the antioxidant activity of the soya bean herbal extract, Meltlets® and of the placebo pellets was evaluated using DPPH free radical scavenging assay and total reduction capacity. PMID:24302800

Deshmukh, Ketkee; Amin, Purnima

2013-01-01

217

Modeling of 2D diffusion processes based on microscopy data: parameter estimation and practical identifiability analysis  

PubMed Central

Background Diffusion is a key component of many biological processes such as chemotaxis, developmental differentiation and tissue morphogenesis. Since recently, the spatial gradients caused by diffusion can be assessed in-vitro and in-vivo using microscopy based imaging techniques. The resulting time-series of two dimensional, high-resolutions images in combination with mechanistic models enable the quantitative analysis of the underlying mechanisms. However, such a model-based analysis is still challenging due to measurement noise and sparse observations, which result in uncertainties of the model parameters. Methods We introduce a likelihood function for image-based measurements with log-normal distributed noise. Based upon this likelihood function we formulate the maximum likelihood estimation problem, which is solved using PDE-constrained optimization methods. To assess the uncertainty and practical identifiability of the parameters we introduce profile likelihoods for diffusion processes. Results and conclusion As proof of concept, we model certain aspects of the guidance of dendritic cells towards lymphatic vessels, an example for haptotaxis. Using a realistic set of artificial measurement data, we estimate the five kinetic parameters of this model and compute profile likelihoods. Our novel approach for the estimation of model parameters from image data as well as the proposed identifiability analysis approach is widely applicable to diffusion processes. The profile likelihood based method provides more rigorous uncertainty bounds in contrast to local approximation methods. PMID:24267545

2013-01-01

218

OPTOELECTRONICS. SIGNAL PROCESSING: Tomographic reconstruction of the spatial and energy parameters of laser beams  

NASA Astrophysics Data System (ADS)

A tomographic approach is suggested for the determination of the spatial and energy parameters of laser beams. This approach is based on reconstruction of the center of gravity position, the effective size, the focusing functionals, and the finesse (sharpness) from the brightness of the radiation scattered in the medium in which a light beam is propagating. The integral relationships make it possible to determine the relevant parameters and to bypass the stage of reconstruction of the intensity distribution. The effectiveness of this reconstruction process is investigated in a numerical experiment.

Aksenov, V. P.; Pikalov, V. V.

1990-02-01

219

Bayesian wavelet approaches for parameter estimation and change point detection in long memory processes  

E-print Network

llment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved as to style and content by: Marina Vannucci (Chair of Committee) Je rey D. Hart (Member) Bani K. Mallick (Member) Narasimha Reddy (Member) Michael T. Longnecker (Head of Department... Committee: Dr. Marina Vannucci The main goal of this research is to estimate the model parameters and to detect multiple change points in the long memory parameter of Gaussian ARFIMA(p;d;q) processes. Our approach is Bayesian and inference is done on wavelet...

Ko, Kyungduk

2005-11-01

220

Laser Trimming of CuAlMo Thin-Film Resistors: Effect of Laser Processing Parameters  

NASA Astrophysics Data System (ADS)

This paper reports the effect of varying laser trimming process parameters on the electrical performance of a novel CuAlMo thin-film resistor material. The films were prepared on Al2O3 substrates by direct-current (DC) magnetron sputtering, before being laser trimmed to target resistance value. The effect of varying key laser parameters of power, Q-rate, and bite size on the resistor stability and tolerance accuracy were systematically investigated. By reducing laser power and bite size and balancing this with Q-rate setting, significant improvements in resistor stability and resistor tolerance accuracies of less than ±0.5% were achieved.

Birkett, Martin; Penlington, Roger

2012-08-01

221

Estimation of Temperature Dependent Parameters of a Batch Alcoholic Fermentation Process  

NASA Astrophysics Data System (ADS)

In this work, a procedure was established to develop a mathematical model considering the effect of temperature on reaction kinetics. Experiments were performed in batch mode in temperatures from 30 to 38°C. The microorganism used was Saccharomyces cerevisiae and the culture media, sugarcane molasses. The objective is to assess the difficulty in updating the kinetic parameters when there are changes in fermentation conditions. We conclude that, although the re-estimation is a time-consuming task, it is possible to accurately describe the process when there are changes in raw material composition if a re-estimation of parameters is performed.

de Andrade, Rafael Ramos; Rivera, Elmer Ccopa; Costa, Aline C.; Atala, Daniel I. P.; Filho, Francisco Maugeri; Filho, Rubens Maciel

222

Effects of HVOF Process Parameters on the Properties of Ni-Cr Coatings  

NASA Astrophysics Data System (ADS)

This research examined the influence of processing parameters on the structure of a Ni-50Cr coating applied by high-velocity oxy-fuel spraying onto stainless steel specimens. This type of coating is normally used as protection against heat and corrosion encountered in power plant and marine boilers, and oil refinery heaters. A statistical design of experiments identified fuel and oxygen flow rates and spraying distance as the most influential parameters controlling the in-flight characteristics of the powder particles prior to impact. The effects of these parameters on the porosity level, oxide content, and microhardness of the coatings were then investigated in more detail. These results indicated that the oxide content and hardness of the coatings were dependent on the gas combustion ratio but not on spraying distance. The porosity level and amount of unmelted particles were reduced at the longest spraying distance.

Saaedi, J.; Coyle, T. W.; Arabi, H.; Mirdamadi, S.; Mostaghimi, J.

2010-03-01

223

Investigation of high shear wet granulation processes using different parameters and formulations.  

PubMed

This study compared the granulation processes for different formulations using a laboratory-scale high shear mixer. The effects of critical process parameters (impeller speed, chopper speed and kneading time) on granule characteristics were evaluated. The characteristics of the granules studied included the size distribution, friability and morphological properties. The flow profiles of the wet mass and material deposition during the process were also studied. The results obtained showed that the effect of the impeller speed was determined by the starting material system. On the other hand, chopper speeds from 1200 to 3600 rpm and kneading times from 120 to 240 s had a consistent influence on all formulations. Moreover, it was found that the toroidal flow pattern of the wet mass could be maintained for a longer period and granules with a good spherical shape were obtained by removing the chopper during the last 120 s of the granulation process. In addition, the use of the pregelatinized starch in the formulation also led to a reduction in the wall adhesion of the material. It was concluded that the effectiveness of high shear wet granulation could be improved by choosing a proper combination of starting material and process parameters and by monitoring the mass motion during the process. PMID:18175969

Wang, Siling; Ye, Guanhao; Heng, Paul Wan Sia; Ma, Mingxin

2008-01-01

224

Optimization of Atmospheric Plasma Spray Process Parameters using a Design of Experiment for Alloy 625 coatings  

NASA Astrophysics Data System (ADS)

Alloy 625 is a Ni-based superalloy which is often a good solution to surface engineering problems involving high temperature corrosion, wear, and thermal degradation. Coatings of alloy 625 can be efficiently deposited by thermal spray methods such as Air Plasma Spraying. As in all thermal spray processes, the final properties of the coatings are determined by the spraying parameters. In the present study, a D-optimal experimental design was used to characterize the effects of the APS process parameters on in-flight particle temperature and velocity, and on the oxide content and porosity in the coatings. These results were used to create an empirical model to predict the optimum deposition conditions. A second set of coatings was then deposited to test the model predictions. The optimum spraying conditions produced a coating with less than 4% oxide and less than 2.5% porosity. The process parameters which exhibited the most important effects directly on the oxide content in the coating were particle size, spray distance, and Ar flow rate. The parameters with the largest effects directly on porosity were spray distance, particle size, and current. The particle size, current, and Ar flow rate have an influence on particle velocity and temperature but spray distance did not have a significant effect on either of those characteristics. Thus, knowledge of the in-flight particle characteristics alone was not sufficient to control the final microstructure. The oxidation index and the melting index incorporate all the parameters that were found to be significant in the statistical analyses and correlate well with the measured oxide content and porosity in the coatings.

Azarmi, F.; Coyle, T. W.; Mostaghimi, J.

2008-03-01

225

Crack toughness evaluation of hot pressed and forged beryllium.  

NASA Technical Reports Server (NTRS)

Fracture toughness tests at room temperature were made on three-point loaded beryllium bend specimens cut from hot pressed block and a forged disk. These specimens had plane proportions conforming to ASTM E 399 and covered a thickness range of from 1/32 to 1/2 in. Two sets of bend specimens were tested, one having fatigue cracks and the other 0.5 mil radius notches. One objective of the investigation was the development of techniques to produce fatigue cracks in accordance with the procedures specified in ASTM E 399. This objective was achieved for the hot pressed material. In plane cracks were not consistently produced in the specimens cut from forged stock.

Jones, M. H.; Bubsey, R. T.; Brown, W. F., Jr.

1973-01-01

226

Laser Quenching of Ionic Nitrided Steel: Effect of Process Parameters on Microstructure and Optimization  

NASA Astrophysics Data System (ADS)

The surface properties of 40CrMnMo7 steel have been increased by ionic nitriding thermo chemical treatment followed by laser quenching. Nitriding treatment increases the wear resistance and decreases the wear coefficient, guaranteeing an uniform, though shallow, hardening depth. Combining nitriding with laser quenching has been shown to increase of the hardening depth, while retaining the advantages obtained by the first treatment. In this work the effect of laser quenching parameters on microstructure and mechanical properties of 40CrMnMo7 steel have been investigated and predictive models developed suitable for further optimization of the process. DoE has been exploited to reduce the number of experiments and for evaluating by statistic methods the optimized process parameters.

Colombini, E.; Sola, R.; Parigi, G.; Veronesi, P.; Poli, G.

2014-11-01

227

Changes in some psychophysiological parameters in speech information processing under masking noise effect.  

PubMed

The aim of the present work was to study the influence of masking broad-band (white), impulse and interrupted noise with intensities LAeq 60 and 90 dB(A) on the execution of some psychophysiological tasks. The following parameters were studied: pulse frequency and variation, breathing frequency and variation, vascular tone etc. The psychological tasks model different parts of the operators' activity and include: conduction of mathematical calculations at datum speed; test related to the information processing; complex optional task supplied by Piorkovski's device. After statistical processing of results by Student-Fischer's t test and monofactor dispersion analysis it was established that the masking noise effect was more strongly expressed in the execution of psychophysiological tasks connected with the main memory. Of all tested physiological parameters the changes in the peripheral circulation, expressed in elevated vascular tone of peripheral blood vessels, were the most significant. PMID:9151005

Tsaneva, L; Danev, S; Dinkova, K

1997-03-01

228

Surface-based IRST: a selection process for sensor parameter values  

NASA Astrophysics Data System (ADS)

The parameter values for a Navy's IRST (infrared search and track) sensor are determined by (1) the operational requirements, (2) the available best technology, and (3) past experience with IRST system design. The selection process for the parameter values is illustrated by use of a set of operational requirements representative of the North Sea. Initial values of the optics parameters are determined by use of a design diagram. The approximate sensor parameter values are input to the TEDIS design computer algorithm for optimization. The effectiveness of the false-alarm reduction algorithms will depend on some of the sensor parameter values. The final assessment of these values can therefore be made only after performance testing of the algorithms. The design of a combined radiometer -- IRST testbed, the SIRDAS, is outlined. This system is used for measuring high quality target and clutter data in the potential battlefields. This data is essential for testing and fine-tuning of the all- important false alarm reduction algorithms.

Andresen, Bjorn F.; Ben-David, Oded; Glazer, Shlomo; Roth, Shmuel; Levy, Baruch

1997-08-01

229

OPTICAL DATA PROCESSING. WAVEGUIDES: Parameters of single-mode Ag+ ion-exchange glass waveguides  

NASA Astrophysics Data System (ADS)

An investigation was made of the influence of the Ag+ diffusion conditions on the parameters of planar glass waveguides. The diffusion process had more than one stage, creating two regions with different characteristic dependences of the refractive index on depth (a quasitwo-layer waveguide). Industrial waveguide fabrication conditions were determined for ensuring not only a weak dependence of the effective refractive index of a mode on the waveguide depth, but also low insertion losses.

Lyndin, N. M.; Nurligareev, D. Kh; Sychugov, V. A.; Tishchenko, A. V.

1992-04-01

230

Impact of Earthquake Rupture Extensions on Parameter Estimations of Point-Process Models  

Microsoft Academic Search

Stochastic point-processes are widely applied to model spatio-temporal earthquake occurrence. In particular, the ETAS (Epidemic Type Aftershock Sequence) model has been shown to reproduce successfully the short-term clustering of earthquakes. An important parameter of the model is the ?-value describing the scaling of the aftershock productivity with magnitude of the triggering earthquake according to 10?M. Fitting of the space-dependent ETAS

S. Hainzl; A. Christophersen; B. Enescu

2008-01-01

231

Effects of processing parameters on the temperature field of selective laser melting metal powder  

Microsoft Academic Search

Based on temperature-dependent thermophysical parameters and nonlinear phase transformation from powder to liquid, a three-dimensional\\u000a transient thermal finite model of selective laser melting process is developed. Commercial ANSYS software is used to simulate\\u000a the distribution of the temperature field in selective laser melting. The simulation results show that a lower scan speed,\\u000a higher laser power, and a lower scan interval

Ruidi Li; Yusheng Shi; Jinhui Liu; Huashan Yao; Wenxian Zhang

2009-01-01

232

One-dimensional mathematical model for selecting plasma spray process parameters  

Microsoft Academic Search

A simple, unified, one-dimensional model has been developed to relate the effects of plasma spray parameters on the temperature\\u000a and velocity of the plasma and particles and on the void content in the coating. The torch, spray, and substrate regions in\\u000a a plasma spray process were first modeled independently and then coupled so that the plasma and particle characteristics calculated

S. Das; V. K. Suri; U. Chandra; K. Sampath

1995-01-01

233

Optimization of Atmospheric Plasma Spray Process Parameters using a Design of Experiment for Alloy 625 coatings  

Microsoft Academic Search

Alloy 625 is a Ni-based superalloy which is often a good solution to surface engineering problems involving high temperature\\u000a corrosion, wear, and thermal degradation. Coatings of alloy 625 can be efficiently deposited by thermal spray methods such\\u000a as Air Plasma Spraying. As in all thermal spray processes, the final properties of the coatings are determined by the spraying\\u000a parameters. In

F. Azarmi; T. W. Coyle; J. Mostaghimi

2008-01-01

234

STEAM TREATMENT OF CROP RESIDUES FOR INCREASED RUMINANT DIGESTIBILITY. I. EFFECTS OF PROCESS PARAMETERS *'2  

Microsoft Academic Search

Summary Rice straw, sugar cane bagasse and sugar cane field trash were steam treated at pressures ranging from 7.0 to 42.2 kg\\/cm 2 with and without added chemicals. Aqueous NaOH, NH 3 and urea were additives used at levels of up to 4.5% of dry weight. Effect of processing parameters was measured by an enzymatic in vitro digestibility assay. The

M. R. Hart; G. Walker; R. P. Graham; P. J. Hanni; A. H. Brown; G. O. Kohler

235

Investigation of micro-milling process parameters for surface roughness and milling depth  

Microsoft Academic Search

The main objective of this study is to investigate the micro-milling performance of the AISI H13 with different process parameters\\u000a namely laser power, scan speed, frequency, and fill spacing using 30W fiber laser marking machine and to find the optimal\\u000a operation conditions for minimum surface roughness and maximum milling depth. The 108 different combinations occurred with\\u000a the interaction of each

Ibrahim Etem Saklakoglu; Sefika Kasman

2011-01-01

236

Occurrence of shear bands in isothermal, hot forging  

SciTech Connect

The paper is a continuation of previously reported work on deformation and unstable flow in hot forging and hot torsion. The instability criterion is employed to interpret data and shear band observations. In addition, computer simulations were run to obtain detailed strain, strain rate, and stress histories. This analysis formed the basis for workability maps which delineate safe regimes for hot working in terms of strain rate and temperature. 34 refs.

Semiatin, S.L.; Lahoti, G.D.

1982-02-01

237

Influence of process parameters and equipment on dry foam formulation properties using indomethacin as model drug.  

PubMed

Dry foam technology was developed to overcome insufficient oral bioavailability of poorly soluble and wettable active pharmaceutical ingredients (APIs). It is intended to enable a faster and more efficient dissolution by avoiding API agglomeration and floating of non-wetted API particles. The aim of this study was to investigate the influence of process parameters, such as paste water content and type of equipment used on dry foam morphology, granule characteristics and dissolution behavior of the corresponding tablets using indomethacin as model compound. Multiple analytical methods, namely scanning electron microscopy, X-ray micro-computed tomography and mercury porosimetry, specific surface area analysis and sieve analysis were employed. Dissolution of dry foam formulation tablets was compared to a reference formulation in biorelevant media. Process parameters proved to have a distinct influence on dry foam morphology and granule characteristics, correlations between paste viscosity and pore size distribution could be observed. Dissolution behavior of indomethacin was improved by dry foam technology compared to the reference formulation. Variation of process parameters within the studied ranges did not alter the characteristics of the dry foam formulation dissolution behavior. Therefore, dry foam technology seems a promising future technology with the option of continuous manufacturing. PMID:23891743

Sprunk, Angela; Page, Susanne; Kleinebudde, Peter

2013-10-15

238

Quantitative analysis of beam delivery parameters and treatment process time for proton beam therapy  

SciTech Connect

Purpose: To evaluate patient census, equipment clinical availability, maximum daily treatment capacity, use factor for major beam delivery parameters, and treatment process time for actual treatments delivered by proton therapy systems. Methods: The authors have been recording all beam delivery parameters, including delivered dose, energy, range, spread-out Bragg peak widths, gantry angles, and couch angles for every treatment field in an electronic medical record system. We analyzed delivery system downtimes that had been recorded for every equipment failure and associated incidents. These data were used to evaluate the use factor of beam delivery parameters, the size of the patient census, and the equipment clinical availability of the facility. The duration of each treatment session from patient walk-in and to patient walk-out of the treatment room was measured for 82 patients with cancers at various sites. Results: The yearly average equipment clinical availability in the last 3 yrs (June 2007-August 2010) was 97%, which exceeded the target of 95%. Approximately 2200 patients had been treated as of August 2010. The major disease sites were genitourinary (49%), thoracic (25%), central nervous system (22%), and gastrointestinal (2%). Beams have been delivered in approximately 8300 treatment fields. The use factor for six beam delivery parameters was also evaluated. Analysis of the treatment process times indicated that approximately 80% of this time was spent for patient and equipment setup. The other 20% was spent waiting for beam delivery and beam on. The total treatment process time can be expressed by a quadratic polynomial of the number of fields per session. The maximum daily treatment capacity of our facility using the current treatment processes was estimated to be 133 {+-} 35 patients. Conclusions: This analysis shows that the facility has operated at a high performance level and has treated a large number of patients with a variety of diseases. The use factor of beam delivery parameters varies by disease site. Further improvements in efficiency may be realized in the equipment- and patient-related processes of treatment.

Suzuki, Kazumichi; Gillin, Michael T.; Sahoo, Narayan; Zhu, X. Ronald; Lee, Andrew K.; Lippy, Denise [Departments of Radiation Physics and Radiation Oncology, University of Texas, MD Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); The Proton Therapy Center Houston, Ltd., L.L.P., 1840 Old Spanish Trail, Houston, Texas 77054 (United States)

2011-07-15

239

Display device for indicating the value of a parameter in a process plant  

DOEpatents

An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually. The integrated process status board (24) is at the apex of an information hierarchy that extends through four levels and provides access at each panel to the full display hierarchy. The control room panels are preferably of a modular construction, permitting the definition of inputs and outputs, the man machine interface, and the plant specific algorithms, to proceed in parallel with the fabrication of the panels, the installation of the equipment and the generic testing thereof.

Scarola, Kenneth (Windsor, CT); Jamison, David S. (Windsor, CT); Manazir, Richard M. (North Canton, CT); Rescorl, Robert L. (Vernon, CT); Harmon, Daryl L. (Enfield, CT)

1993-01-01

240

Design practices for uranium purification - Part 1: Process and operating parameters  

SciTech Connect

This paper presents the principles that shall be considered in the design of a uranium purification unit for conversion plants. In addition, the influence of the main variables and operating parameters in the process is presented as well as some recommended values for the design of new plants. The purification unit in conversion plants has the function of removing impurities contained in uranium ore to obtain nuclear-grade uranium hexafluoride (UF{sub 6}). To achieve this purpose, the solvent extraction technique is used. This process may be performed using perforated pulsed columns in three distinct steps: extraction, scrubbing, and stripping. These steps are discussed individually. The precise evaluation of process parameters constitutes a fundamental step in the design of a conversion plant purification unit. The design practices shall therefore consider, as often as possible, greater operational flexibility of the plant so that the unit can produce a final product with very well-defined characteristics, independent from the composition of the material to be purified or from the operational variations that may occur during the industrial product processing.

Braganca, A. Jr.; Cunha, J.W.; Ribas, A.G.; Cuchieratto, P.C.

1991-11-01

241

Workability in forging of powder metallurgy compacts  

Microsoft Academic Search

The power metallurgy (PM) technique is now applied widely to many industries and materials. To obtain more reliable PM products, many secondary processes are applied to PM preforms. The problem of deformation and fracture of PM preforms still needs a considerable amount of investigation.In this work, the effect of the relative density on the forming limit of PM compacts in

M. Abdel-Rahman; M. N. El-Sheikh

1995-01-01

242

Estimation of the soil strength parameters in Tertiary volcanic regolith (NE Turkey) using analytical hierarchy process  

NASA Astrophysics Data System (ADS)

Costly and time consuming testing techniques and the difficulties in providing undisturbed samples for these tests have led researchers to estimate strength parameters of soils with simple index tests. However, the paper focuses on estimation of strength parameters of soils as a function of the index properties. Analytical hierarchy process and multiple regression analysis based methodology were performed on datasets obtained from soil tests on 41 samples in Tertiary volcanic regolith. While the hierarchy model focused on determining the most important index properties affecting on strength parameters, regression analysis established meaningful relationships between strength parameters and index properties. The negative polynomial correlations between the friction angle and plasticity properties, and the positive exponential relations between the cohesion and plasticity properties were determined. These relations are characterized by a regression coefficient of 0.80. However, Terzaghi bearing capacity formulas were used to test the model. It is important to see whether there is any statistically significant relation between the calculated and the observed bearing capacity values for model testing. Based on the model, the positive linear correlation characterized by the regression coefficient of 0.86 were determined between bearing capacity values obtained by direct and indirect methods.

Ersoy, Hakan; Karsli, Melek Betül; Çellek, Seda; Kul, Bilgehan; Baykan, ?dris; Parsons, Robert L.

2013-12-01

243

A Self-Adaptive Parameter Optimization Algorithm in a Real-Time Parallel Image Processing System  

PubMed Central

Aiming at the stalemate that precision, speed, robustness, and other parameters constrain each other in the parallel processed vision servo system, this paper proposed an adaptive load capacity balance strategy on the servo parameters optimization algorithm (ALBPO) to improve the computing precision and to achieve high detection ratio while not reducing the servo circle. We use load capacity functions (LC) to estimate the load for each processor and then make continuous self-adaptation towards a balanced status based on the fluctuated LC results; meanwhile, we pick up a proper set of target detection and location parameters according to the results of LC. Compared with current load balance algorithm, the algorithm proposed in this paper is proceeded under an unknown informed status about the maximum load and the current load of the processors, which means it has great extensibility. Simulation results showed that the ALBPO algorithm has great merits on load balance performance, realizing the optimization of QoS for each processor, fulfilling the balance requirements of servo circle, precision, and robustness of the parallel processed vision servo system. PMID:24174920

Li, Ge; Zhang, Xuehe; Zhao, Jie; Zhang, Hongli; Ye, Jianwei; Zhang, Weizhe

2013-01-01

244

Development of functional adsorbent from PU foam waste via radiation induced grafting I: Process parameter standardization  

NASA Astrophysics Data System (ADS)

Mutual radiation grafting process has been used to covalently link polymer chains of poly(acrylic acid) to polyurethane foam waste using 60Co-gamma radiation source. Various experimental parameters were investigated in order to optimize the grafting process. The grafted samples have been characterized for water-uptake, surface morphology and thermal stability. Grafting extent increased with dose, dose rate and monomer concentration but decreased with increase in density of PU foam. The matrix grafted up to an extent of ˜90% showed uptake capacity of 220 mg/g (0.09 mol of dye/mol of acrylic acid) for a monovalent dye (basic red 29) within 3 h of contact time in a batch process.

Goel, N. K.; Kumar, Virendra; Dubey, K. A.; Bhardwaj, Y. K.; Varshney, L.

2013-01-01

245

Net-Shape Forging of Aerofoil Blade based on Flash Trimming and Compensation methods  

SciTech Connect

In this research, an automatic blade forging die shape optimisation system was developed by using direct compensation and flash trimming algorithms and integrating with the DEFORM 3D software package. To validate the developed system, a 3D blade forging case problem was simulated and optimised with and without the consideration of trimming simulation. The results were compared with actual measurement data of the forged aerofoil blade with excellent results obtained with the fast trimming simulation procedure used.

Lu, B. [Department of Plasticity Forming Engineering, Shanghai Jiao Tong University, Shanghai, 200030 (China); Ou, H. [Department of Mechanical, Materials and Manufacturing Engineering, University of Nottingham, Nottingham, NG7 2RD (United Kingdom); Armstrong, C. G. [School of Mechanical and Aerospace Engineering, Queen's University Belfast, Belfast, BT9 5AH (United Kingdom)

2011-05-04

246

Dynamical model development and parameter identification for an anaerobic wastewater treatment process.  

PubMed

This paper deals with the development and the parameter identification of an anaerobic digestion process model. A two-step (acidogenesis-methanization) mass-balance model has been considered. The model incorporates electrochemical equilibria in order to include the alkalinity, which has to play a central role in the related monitoring and control strategy of a treatment plant. The identification is based on a set of dynamical experiments designed to cover a wide spectrum of operating conditions that are likely to take place in the practical operation of the plant. A step by step identification procedure to estimate the model parameters is presented. The results of 70 days of experiments in a 1-m(3) fermenter are then used to validate the model. PMID:11668442

Bernard, O; Hadj-Sadok, Z; Dochain, D; Genovesi, A; Steyer, J P

2001-11-20

247

Evaluating Processes, Parameters and Observations Using Cross Validation and Computationally Frugal Sensitivity Analysis Methods  

NASA Astrophysics Data System (ADS)

Sensitivity analysis methods are used to identify measurements most likely to provide important information for model development and predictions and therefore identify critical processes. Methods range from computationally demanding Monte Carlo and cross-validation methods, to very computationally efficient linear methods. The methods are able to account for interrelations between parameters, but some argue that because linear methods neglect the effects of model nonlinearity, they are not worth considering when examining complex, nonlinear models of environmental systems. However, when faced with computationally demanding models needed to simulate, for example, climate change, the chance of obtaining fundamental insights (such as important and relationships between predictions and parameters) with few model runs is tempting. In the first part of this work, comparisons of local sensitivity analysis and cross-validation are conducted using a nonlinear groundwater model of the Maggia Valley, Southern Switzerland; sensitivity analysis are then applied to an integrated hydrological model of the same system where the impact of more processes and of using different sets of observations on the model results are considered; applicability to models of a variety of situations (climate, water quality, water management) is inferred. Results show that the frugal linear methods produced about 70% of the insight from about 2% of the model runs required by the computationally demanding methods. Regarding important observations, linear methods were not always able to distinguish between moderately and unimportant observations. However, they consistently identified the most important observations which are critical to characterize relationships between parameters and to assess the worth of potential new data collection efforts. Importance both to estimate parameters and predictions of interest was readily identified. The results suggest that it can be advantageous to consider local sensitivity analysis in model evaluation, possibly as a preliminary step to provide insights that can be used to improve the design of more demanding methods. This can be foreseen as a promising direction of future research where frugal and complex methods are combined to provide insights on model development and model results.

Foglia, L.; Mehl, S.; Hill, M. C.

2013-12-01

248

Enhancement of energy savings through accelerated implementation of high-performance forge furnaces  

NASA Astrophysics Data System (ADS)

Hague International successfully demonstrated under both controlled and actual production conditions that a well designed slot forge furnace equipped with a ceramic recuperator could consume as much as 65% of the fuel normally consumed by a forging furnace. Thus the Department of Energy, entered into a cooperative agreement to accelerate the introduction of Hague International's high efficiency slot forge furnace into the forging industry. This report details the basis of the cooperative agreement and the history of the host sites covered by the agreement. Fifteen (15) host sites participated in the program.

1982-02-01

249

Residual Stresses in 21-6-9 Stainless Steel Warm Forgings  

SciTech Connect

Forging residual stresses are detrimental to the production and performance of derived machined parts due to machining distortions, corrosion drivers and fatigue crack drivers. Residual strains in a 21-6-9 stainless steel warm High Energy Rate Forging (HERF) were measured via neutron diffraction. The finite element analysis (FEA) method was used to predict the residual stresses that occur during forging and water quenching. The experimentally measured residual strains were used to calibrate simulations of the three-dimensional residual stress state of the forging. ABAQUS simulation tools predicted residual strains that tend to match with experimental results when varying yield strength is considered.

Everhart, Wesley A.; Lee, Jordan D.; Broecker, Daniel J.; Bartow, John P.; McQueen, Jamie M.; Switzner, Nathan T.; Neidt, Tod M.; Sisneros, Thomas A.; Brown, Donald W.

2012-11-14

250

75 FR 20859 - Notice of Realty Action, Independence National Historical Park, Pennsylvania and Valley Forge...  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE INTERIOR National Park Service Notice of Realty Action, Independence National Historical Park, Pennsylvania and Valley Forge National Historical Park, Pennsylvania AGENCY: National Park Service,...

2010-04-21

251

Characterization of wet granulation process parameters using response surface methodology. 1. Top-spray fluidized bed.  

PubMed

Randomized full-factorial designs (3(2)) were used to investigate the effects of processing conditions in the top-spray fluidized bed (TSFB) on the granulation of acetaminophen powder (USP) using 5% polyvinylpyrrolidone (w/w) as the binder. Measured granule properties included the following: mean size and size distribution, specific surface area, bulk density, tapped density, flow rate through an orifice, angle of repose, residual moisture content, and percent overs (> 2 mm). The granules were then compressed (500, 1000, 1500 lbs) into tablets (9-mm shallow concave) using an instrumented rotary press and analyzed for both physical properties and drug-release characteristics. All experimental batches were run in triplicate to reduce the possibility of erroneous results and to increase the confidence in the resulting empirical relationships derived using response-surface methodology. Measured responses were then related to process parameters using two-factor and three-factor linear, interactions, and quadratic regression models. These models were used to generate three-dimensional response surfaces for use in the final analyses. Coefficients of determination (R2) ranging from 0.08 to 0.81 were obtained, indicating that only a portion of the variation in the data could be explained by the changes in process parameter settings during granulation and tableting. The best overall model fits were observed for mean granule size, size distribution, bulk density, tapped density, percent drug dissolution, tablet disintegration time, and tablet friability. PMID:7965672

Lipps, D M; Sakr, A M

1994-07-01

252

Beer fermentation: monitoring of process parameters by FT-NIR and multivariate data analysis.  

PubMed

This work investigates the capability of Fourier-Transform near infrared (FT-NIR) spectroscopy to monitor and assess process parameters in beer fermentation at different operative conditions. For this purpose, the fermentation of wort with two different yeast strains and at different temperatures was monitored for nine days by FT-NIR. To correlate the collected spectra with °Brix, pH and biomass, different multivariate data methodologies were applied. Principal component analysis (PCA), partial least squares (PLS) and locally weighted regression (LWR) were used to assess the relationship between FT-NIR spectra and the abovementioned process parameters that define the beer fermentation. The accuracy and robustness of the obtained results clearly show the suitability of FT-NIR spectroscopy, combined with multivariate data analysis, to be used as a quality control tool in the beer fermentation process. FT-NIR spectroscopy, when combined with LWR, demonstrates to be a perfectly suitable quantitative method to be implemented in the production of beer. PMID:24594186

Grassi, Silvia; Amigo, José Manuel; Lyndgaard, Christian Bøge; Foschino, Roberto; Casiraghi, Ernestina

2014-07-15

253

Simulating the effects of bake process parameters on resist thermal reflow  

NASA Astrophysics Data System (ADS)

Producing smaller feature sizes by extending current and near-term lithographic printing tools is a cost-effective strategy for high-volume production of integrated circuits. The hardbake process, as an annealing step to strengthen resist structures, includes a desirable thermal reflow that can facilitate this objective. Thermal reflow of polymer-based resists is a phase-dependent phenomenon in which a polymeric material with recyclable / reversible thermal characteristics experiences dimensional changes through relaxation during thermal cycling at hardbake. Unlike polymer melts, resist reflow is accompanied by a continuous change in the physical state of the resist over a specific temperature range, so it can be described on the basis of the relaxation modulus-temperature relation. Resist behavior during thermal transitions (e.g., glassy, leathery, rubbery plateau, etc.) can effectively be classified into either solid or viscous, depending on whether the resist material is below or above the characteristic glass transition temperature. In general, resist contact hole size can be significantly reduced by optimizing the principal factors driving resist reflow, i.e., temperature-dependent material properties, bake cycle parameters, contact-hole dimensions, and the type of contact array. Recognizable size reduction of the contact hole appears as the resist passes through the leathery state, and its maximum permanent deformation after thermal cycling completely depends on the resist material used. This research focuses on a bake profile of the resist described by the parameters in typical three-stage proximity contact wafer processing. Simulation programs were developed to characterize the primary thermal properties and process parameters affecting the bake profile, and to identify their relative effects on the resist contact-hole response.

Lee, Jae-Won; Feng, Zhaohua; Engelstad, Roxann L.; Lovell, Edward G.

2004-12-01

254

Comparison between 2D and 3D Numerical Modelling of a hot forging simulative test  

SciTech Connect

The paper presents the comparative analysis between 2D and 3D modelling of a simulative experiment, performed in laboratory environment, in which operating conditions approximate hot forging of a turbine aerofoil section. The plane strain deformation was chosen as an ideal case to analyze the process because of the thickness variations in the final section and the consequent distributions of contact pressure and sliding velocity at the interface that are closed to the conditions of the real industrial process. In order to compare the performances of 2D and 3D approaches, two different analyses were performed and compared with the experiments in terms of loads and temperatures peaks at the interface between the dies and the workpiece.

Croin, M.; Ghiotti, A. [DIMEG University of Padova, via Venezia 1 - 35131 Padova (Italy); Bruschi, S. [DIMS University of Trento, via Mesiano 77 - 38050 Trento (Italy)

2007-04-07

255

Optimizing the plasma spray process parameters of yttria stabilized zirconia coatings using a uniform design of experiments  

Microsoft Academic Search

The plasma spray process parameters of yttria stabilized zirconia coatings with respect to deposition efficiency, porosity and microhardness were investigated using a uniform design of experiments. The measured deposition efficiency, porosity and microhardness of the coatings were regressed as the first- to third-order polynomial equations of five investigated process parameters, the arc current, argon flow rate, hydrogen flow rate, spray

J. F. Li; H. L. Liao; C. X. Ding; C. Coddet

2005-01-01

256

Measurements of gas parameters in plasma-assisted supersonic combustion processes using diode laser spectroscopy  

SciTech Connect

We report a procedure for temperature and water vapour concentration measurements in an unsteady-state combustion zone using diode laser absorption spectroscopy. The procedure involves measurements of the absorption spectrum of water molecules around 1.39 {mu}m. It has been used to determine hydrogen combustion parameters in M = 2 gas flows in the test section of a supersonic wind tunnel. The relatively high intensities of the absorption lines used have enabled direct absorption measurements. We describe a differential technique for measurements of transient absorption spectra, the procedure we used for primary data processing and approaches for determining the gas temperature and H{sub 2}O concentration in the probed zone. The measured absorption spectra are fitted with spectra simulated using parameters from spectroscopic databases. The combustion-time-averaged ({approx}50 ms) gas temperature and water vapour partial pressure in the hot wake region are determined to be 1050 K and 21 Torr, respectively. The large signal-to-noise ratio in our measurements allowed us to assess the temporal behaviour of these parameters. The accuracy in our temperature measurements in the probed zone is {approx}40 K. (laser applications and other topics in quantum electronics)

Bolshov, Mikhail A; Kuritsyn, Yu A; Liger, V V; Mironenko, V R [Institute for Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation); Leonov, S B; Yarantsev, D A [Institute of Thermal Physics of Extreme States, Associated Institute of High Temperaturs, Russian Academy of Sciences (Russian Federation)

2009-09-30

257

Response Surface Method for the Rapid Design of Process Parameters in Tube Hydroforming  

SciTech Connect

This paper deals with the optimization of tube hydroforming parameters in order reduce defects which may occur at the end of forming process such as necking and wrinkling. We propose a specific methodology based on the coupling between an inverse method for the rapid simulation of tube hydroforming process, and a Response Surface Method based on diffuse approximation. The response surfaces are built using Moving Least Squares approximations and constructed within a moving region of interest which moves across a predefined discrete grid of authorized experimental designs. An application of hydroforming of a bulge from aluminium alloy 6061-T6 tubing has been utilized to validate our methodology. The final design is validated with ABAQUS Explicit Dynamic commercial code.

Chebbah, M. S.; Hecini, M. [Universite Mohamed Khider, B.P. 145, 07000 Biskra, Algerie (Algeria); Naceur, H. [Universite de Technologie de Compiegne, BP. 20529 - 60205, Compiegne (France); Belouettar, S. [Centre de Recherche Public Henri Tudor, 29 Boulevard J.F. Kennedy L1855 (Luxembourg)

2007-05-17

258

Employment of the covariance matrix in parameter estimation for stochastic processes in cell biology  

NASA Astrophysics Data System (ADS)

The dynamics of movements of biological cells can be described with models from correlated stochastic processes. In order to overcome problems from correlated and insufficient data in the determination of the model parameters of such processes we employ the covariance matrix of the data. Since the covariance suffers itself from statistical uncertainty it is corrected by a renormalization treatment [1]. For the example of normal and fractional Brownian motion, which allows both to access all quantities on full theoretical grounds and to generate data similar to experiment, we discuss our results and those of previous works by Gregory [2] and Sivia [3]. The presented approach has the potential to estimate the aging correlation function of observed cell paths and can be applied to more complicated models.

Preuss, R.; Dieterich, P.

2013-08-01

259

Releasing polysaccharide and protein from yeast cells by ultrasound: selectivity and effects of processing parameters.  

PubMed

A 20 kHz high-intensity ultrasound was employed for the selective release of polysaccharide and protein from yeast cells. While the release of polysaccharide and protein was affected by most of the processing parameters, the release selectivity, which is the ratio of the amount of polysaccharide released to that of protein, designated as T/P value, was only influenced by sonication time, temperature and ionic strength, among which temperature had the greatest influence. The T/P value at 85 °C was a factor of 9.3 of the one at 25 °C. The underlying mechanism of this selectivity is speculated to be thermal denaturation and aggregation of protein within yeast cells at elevated temperatures leading to the decrease of protein release by ultrasound. This finding may be useful in exploring a novel selective process for producing polysaccharide and protein fractions from yeast biomass. PMID:24216066

Zhang, Li; Jin, Yuan; Xie, Yajuan; Wu, Xiaofang; Wu, Tao

2014-03-01

260

Response Surface Method for the Rapid Design of Process Parameters in Tube Hydroforming  

NASA Astrophysics Data System (ADS)

This paper deals with the optimization of tube hydroforming parameters in order reduce defects which may occur at the end of forming process such as necking and wrinkling. We propose a specific methodology based on the coupling between an inverse method for the rapid simulation of tube hydroforming process, and a Response Surface Method based on diffuse approximation. The response surfaces are built using Moving Least Squares approximations and constructed within a moving region of interest which moves across a predefined discrete grid of authorized experimental designs. An application of hydroforming of a bulge from aluminium alloy 6061-T6 tubing has been utilized to validate our methodology. The final design is validated with ABAQUS Explicit Dynamic commercial code.

Chebbah, M. S.; Naceur, H.; Hecini, M.; Belouettar, S.

2007-05-01

261

Cardiac sensitivity in children: sex differences and its relationship to parameters of emotional processing.  

PubMed

In adults, the level of ability to perceive one's own body signals plays an important role for many concepts of emotional experience as demonstrated for emotion processing or emotion regulation. Representative data on perception of body signals and its emotional correlates in children is lacking. Therefore, the present study investigated the cardiac sensitivity of 1,350 children between 6 and 11 years of age in a heartbeat perception task. Our main findings demonstrated the distribution of cardiac sensitivity in children as well as associations with interpersonal emotional intelligence and adaptability. Furthermore, independent of body mass index, boys showed a significantly higher cardiac sensitivity than girls. We conclude that cardiac sensitivity in children appears to show weaker but similar characteristics and relations to emotional parameters as found in adults, so that a dynamic developmental process can be assumed. PMID:24810627

Koch, Anne; Pollatos, Olga

2014-09-01

262

Tailoring Selective Laser Melting Process Parameters for NiTi Implants  

NASA Astrophysics Data System (ADS)

Complex-shaped NiTi constructions become more and more essential for biomedical applications especially for dental or cranio-maxillofacial implants. The additive manufacturing method of selective laser melting allows realizing complex-shaped elements with predefined porosity and three-dimensional micro-architecture directly out of the design data. We demonstrate that the intentional modification of the applied energy during the SLM-process allows tailoring the transformation temperatures of NiTi entities within the entire construction. Differential scanning calorimetry, x-ray diffraction, and metallographic analysis were employed for the thermal and structural characterizations. In particular, the phase transformation temperatures, the related crystallographic phases, and the formed microstructures of SLM constructions were determined for a series of SLM-processing parameters. The SLM-NiTi exhibits pseudoelastic behavior. In this manner, the properties of NiTi implants can be tailored to build smart implants with pre-defined micro-architecture and advanced performance.

Bormann, Therese; Schumacher, Ralf; Müller, Bert; Mertmann, Matthias; de Wild, Michael

2012-12-01

263

Effect of Processing Parameters on the Mechanical Properties of Interstitial Free Steel Subjected to Friction Stir Processing  

NASA Astrophysics Data System (ADS)

In the present work, the effect of friction stir processing parameters on the mechanical properties of an interstitial free steel was studied. Four rotating speeds (800, 1250, 1600, 2000 rpm) and two traverse speeds (31.5 and 63 mm/min) were employed. On both sides of specimens, a nanograin layer with the thickness and nanograins of 150 ?m and 50-100 nm were formed, respectively. For the specimen processed at rotating speed of 1600 rpm and the traverse speed of 31.5 mm/min, the maximum strength was achieved, which was about 80% increase in the strength comparing to that of base material. For constant traverse speed, the increase in the rotation speed from 800 to 1600 rpm led to a decrease in uniform and total elongation of friction stir processed samples. By contrast, when the rotating speed exceeded 1600 rpm, the uniform and total elongation was increased again, while there was a drop in strength. The results of microhardness indicate more than threefold increase in the hardness of the stirred zone comparing to that of base material.

Chabok, A.; Dehghani, K.

2013-05-01

264

Low-dose capsule filling of inhalation products: critical material attributes and process parameters.  

PubMed

The aim of the present work was to identify the material attributes and process parameters of a dosator-nozzle capsule filling machine that are critical in low-fill weight capsule filling for inhalation therapies via hard-gelatin capsules. Twelve powders, mostly inhalation carriers, some fines and one proprietary active pharmaceutical ingredient (API), were carefully characterized and filled into size 3 capsules. Since different process conditions are required to fill capsules with powders that have very different material attributes, the powders were divided into two groups. A design of experiments (DOE) based exclusively on process parameters was developed for each group, to identify the critical material attributes (CMA) and critical process parameters (CPP). The fill weight (4-45 mg) of the group I powders (larger particles, higher density, better flowability and less cohesion) correlated with the nozzle diameter (1.9-3.4mm), the dosing chamber length (2.5-5mm), the powder layer depth (5-12.5mm) and the powder density (bulk and tapped density). The RSDs were acceptable in most cases, even for very low doses. The fill weight (1.5-21 mg) of group II powders (very fine and low dense particles with a particle size <10 ?m, poor flowability and higher cohesion) depended also on the nozzle diameter (1.9-2.8mm), the dosing chamber length (2.5-5mm) and the powder layer depth (5-10mm), albeit in a different way, indicating that for these powders dosator filling was not volumetric. Moreover, frictional (wall friction angle) and powder-flow characteristics (bulk density and basic flowability energy) have an influence on the mass. Thus, in summary, group I and group II powders can be filled successfully via dosator systems at low fill weights. However, the group II powders were more challenging to fill, especially without automated process control. This study is the first scientific qualification of dosator nozzles for low-fill weight (1-45 mg) capsule filling. PMID:25087508

Faulhammer, Eva; Fink, Marlies; Llusa, Marcos; Lawrence, Simon M; Biserni, Stefano; Calzolari, Vittorio; Khinast, Johannes G

2014-10-01

265

Calculating spatial statistics for velocity jump processes with experimentally observed reorientation parameters.  

PubMed

Mathematical modelling of the directed movement of animals, microorganisms and cells is of great relevance in the fields of biology and medicine. Simple diffusive models of movement assume a random walk in the position, while more realistic models include the direction of movement by assuming a random walk in the velocity. These velocity jump processes, although more realistic, are much harder to analyse and an equation that describes the underlying spatial distribution only exists in one dimension. In this communication we set up a realistic reorientation model in two dimensions, where the mean turning angle is dependent on the previous direction of movement and bias is implicitly introduced in the probability distribution for the direction of movement. This model, and the associated reorientation parameters, is based on data from experiments on swimming microorganisms. Assuming a transport equation to describe the motion of a population of random walkers using a velocity jump process, together with this realistic reorientation model, we use a moment closure method to derive and solve a system of equations for the spatial statistics. These asymptotic equations are a very good match to simulated random walks for realistic parameter values. PMID:15868200

Codling, E A; Hill, N A

2005-11-01

266

Micropollutant biotransformation kinetics associate with WWTP process parameters and microbial community characteristics.  

PubMed

The objective of this work was to identify relevant wastewater treatment plant (WWTP) parameters and underlying microbial processes that influence the biotransformation of a diverse set of micropollutants. To do this, we determined biotransformation rate constants for ten organic micropollutants in batch reactors seeded with activated sludge from ten diverse WWTPs. The estimated biotransformation rate constants for each compound ranged between one and four orders of magnitude among the ten WWTPs. The biotransformation rate constants were tested for statistical associations with various WWTP process parameters, amoA transcript abundance, and acetylene-inhibited monooxygenase activity. We determined that (i) ammonia removal associates with oxidative micropollutant biotransformation reaction rates; (ii) archaeal but not bacterial amoA transcripts associate with both ammonia removal and oxidative micropollutant biotransformation reaction rates; and (iii) the activity of acetylene-inhibited monooxygenases (including ammonia monooxygenase) associates with ammonia removal and the biotransformation rate of isoproturon, but does not associate with all oxidative micropollutant biotransformations. In combination, these results lead to the conclusion that ammonia removal and amoA transcript abundance can potentially be predictors of oxidative micropollutant biotransformation reactions, but that the biochemical mechanism is not necessarily linked to ammonia monooxygenase activity. PMID:22938719

Helbling, Damian E; Johnson, David R; Honti, Mark; Fenner, Kathrin

2012-10-01

267

SourceForge.net: Project of the Month  

NSDL National Science Digital Library

SourceForge, described as the most prominent repository of open source software, selects an outstanding contribution to recognize on its Project of the Month Web site. As with all open source projects, the software can be freely downloaded, used, and modified. Examples of past projects of the month include an instant messaging client, a 3D game developing kit, and a tool for porting applications from UNIX to the Macintosh OS X operating system. A description of the project and an interview with the project's creator showcase the software.

2002-01-01

268

Evolving chemometric models for predicting dynamic process parameters in viscose production.  

PubMed

In viscose production, it is important to monitor three process parameters in order to assure a high quality of the final product: the concentrations of H(2)SO(4), Na(2)SO(4) and Z(n)SO(4). During on-line production these process parameters usually show a quite high dynamics depending on the fiber type that is produced. Thus, conventional chemometric models, which are trained based on collected calibration spectra from Fourier transform near infrared (FT-NIR) measurements and kept fixed during the whole life-time of the on-line process, show a quite imprecise and unreliable behavior when predicting the concentrations of new on-line data. In this paper, we are demonstrating evolving chemometric models which are able to adapt automatically to varying process dynamics by updating their inner structures and parameters in a single-pass incremental manner. These models exploit the Takagi-Sugeno fuzzy model architecture, being able to model flexibly different degrees of non-linearities implicitly contained in the mapping between near infrared spectra (NIR) and reference values. Updating the inner structures is achieved by moving the position of already existing local regions and by evolving (increasing non-linearity) or merging (decreasing non-linearity) new local linear predictors on demand, which are guided by distance-based and similarity criteria. Gradual forgetting mechanisms may be integrated in order to out-date older learned relations and to account for more flexibility of the models. The results show that our approach is able to overcome the huge prediction errors produced by various state-of-the-art chemometric models. It achieves a high correlation between observed and predicted target values in the range of [0.95,0.98] over a 3 months period while keeping the relative error below the reference error value of 3%. In contrast, the off-line techniques achieved correlations below 0.5, ten times higher error rates and the more deteriorate, the more time passes by. PMID:22502608

Cernuda, Carlos; Lughofer, Edwin; Suppan, Lisbeth; Röder, Thomas; Schmuck, Roman; Hintenaus, Peter; Märzinger, Wolfgang; Kasberger, Jürgen

2012-05-01

269

Deformation and unstable flow in hot forging of Ti-6Ai-2Sn-4Zr-2Mo-0.1Si  

NASA Astrophysics Data System (ADS)

The stable and unstable plastic flow of Ti-6Al-2Sn-4Zr-2Mo-0.1Si (Ti-6242) has been investigated at temperatures from 816 to 1010 °C (1500 to 1850 °F) and at strain rates from 0.001 to 10 s-1 in order to establish its hot forging characteristics. In hot, isothermal compression, Ti-6242 with an equiaxed a structure deforms stably and has a flow stress which decreases with straining due to adiabatic heating. With a transformed-? microstructure, unstable flow in hot compression is observed and concluded to arise from large degrees of flow softening caused by microstructural modification during deformation and, to a small extent, by adiabatic heating. Both microstructures have a sharp dependence of flow stress on temperature. Using the concepts of thermally-activated processes, it was shown analytically that this dependence is related to the large strain-rate sensitivity of the flow stress exhibited by the alloy. From lateral sidepressing results, the large dependence of flow stress on temperature was surmised to be a major factor leading to the shear bands occurring in nonisothermal forging of the alloy. Shear bands were also observed in isothermal forging. A model was developed to define the effect of material properties such as flow softening rate and strain-rate sensitivity on shear band development and was applied successfully to predict the occurrence of shear bands in isothermal forging.

Semiatin, S. L.; Lahoti, G. D.

1981-10-01

270

Influence of process parameters on properties of Nanostructured Lipid Carriers (NLC) formulation.  

PubMed

Nanostructured lipid carriers (NLC) are stable colloidal formulations with notable advantages for drug delivery systems. Thanks to their physicochemical stability, biocompatibility, biodegradability and controlled drug release, they have received increasing attention for the last several years. The aim of the study was to prepare and characterize nanostructured lipid carriers (NLC). Both, the effect of the process parameters and the effect of the preemulsion composition on the NLC properties were investigated. In the work, different type of surfactants (i.e. decyl glucoside, Poloxamer188, Tween 80, sodium cholate) and their combinations were used to stabilize NLC dispersions. Moreover, several kinds of solid lipids (modified beeswax, gliceryl behenate, cetyl palmitate and berry wax) and liquid lipids (caprilic/capric triglyceride and decyl oleate) were applied. An ultrasonication method using a probe type sonicator was used to obtain NLC, and the time and energy of the process were modified throuhout. The physicochemical properties of the formulations, such as particle size, size distribution, polidispersity index were studied using the dynamic light scattering (DLS) method. The electrophoretic mobility of obtained particles was also measured, using the Zetasizer Nano ZS Malvern Instrument based on the Laser Doppler Velocimetry (LDV) technique. Knowing the value of electrophoretic mobility of particles for given conditions, the zeta potential was determined. The obtained results showed that the process parameters and the composition of the preemulsion had significant impact on the nanoparticles structure. The optimal formulations size ranged between 60 and 80 nm, and the value of their zeta potential was up to -30mV. The stability of these systems was further confirmed by macroscopic observation. PMID:24432330

Laso?, Elwira; Sikora, El?bieta; Ogonowski, Jan

2013-01-01

271

The effect of process parameters on the Liquid Flame Spray generated titania nanoparticles.  

PubMed

Nanoparticles have become important in many applications. It is essential to be able to control the particle size because the properties of nanoparticles change dramatically with particle size. An efficient way to generate nanoparticles is via aerosol processes. In this study we used Liquid Flame Spray consisting of liquid precursor droplets sprayed into a high-speed hydrogen/oxygen flame where they evaporate, vapours react and nucleate to form titania nanoparticles. Using flame methods, also dopants and sensitizers can easily be introduced in order to, e.g. improve the photocatalytic activity of the nanomaterial. To obtain a practical guideline in order to tailor the final nanoparticle size in the process, we have systematically studied the effects of different process parameters on the particle size of titania. Titania is used, e.g. as a photocatalyst, and then both particle size and crystal structure are important when looking at the efficiency. In this work, the generated nanoparticle size has been measured by aerosol instrumentation and the particle morphology has been verified with transmission electron microscopy. In Liquid Flame Spray method, there are several adjustable parameters such as precursor feed rate into the flame; concentration of the precursor; precursor material itself as well as solvent used in the precursor; mass flow of combustion gases and also the mechanical design of the torch used. We used metal organic based titanium precursors in alcohol solvents, predominantly ethanol and 2-propanol. Large differences in particle production between the precursors were found. Differences could also be seen for various solvents. As for precursor feed in the flame, the more mass is introduced the larger the nanoparticles are, i.e. precursor concentration and precursor feed rate have an impact on particle size. A similar phenomenon can be discovered for the combustion gas flow rates. Torch design also plays an important role in controlling the particle size. PMID:17950664

Aromaa, Mikko; Keskinen, Helmi; Mäkelä, Jyrki M

2007-11-01

272

Effect of Electron Beam Freeform Fabrication (EBF3) Processing Parameters on Composition of Ti-6-4  

NASA Technical Reports Server (NTRS)

The Electron Beam Freeform Fabrication (EBF3) process developed at NASA Langley Research Center was evaluated using a design of experiments approach to determine the effect of processing parameters on the composition and geometry of Ti-6-4 deposits. The effects of three processing parameters: beam power, translation speed, and wire feed rate, were investigated by varying one while keeping the remaining parameters constant. A three-factorial, three-level, fully balanced mutually orthogonal array (L27) design of experiments approach was used to examine the effects of low, medium, and high settings for the processing parameters on the chemistry, geometry, and quality of the resulting deposits. Single bead high deposits were fabricated and evaluated for 27 experimental conditions. Loss of aluminum in Ti-6-4 was observed in EBF3 processing due to selective vaporization of the aluminum from the sustained molten pool in the vacuum environment; therefore, the chemistries of the deposits were measured and compared with the composition of the initial wire and base plate to determine if the loss of aluminum could be minimized through careful selection of processing parameters. The influence of processing parameters and coupling between these parameters on bulk composition, measured by Direct Current Plasma (DCP), local microchemistries determined by Wavelength Dispersive Spectrometry (WDS), and deposit geometry will also be discussed.

Lach, Cynthia L.; Taminger, Karen; Schuszler, A. Bud, II; Sankaran, Sankara; Ehlers, Helen; Nasserrafi, Rahbar; Woods, Bryan

2007-01-01

273

Comparison of mechanical and metallurgical properties of hollow and solid forged products  

Microsoft Academic Search

Some mechanical and metallurgical properties of hollow and solid long forged products are compared. The metallurgical properties include such micro- and macro-structural characteristics as the grain size and grain flow patterns. Mechanical evaluation was performed by means of hardness testing. Some theoretical analyses were also carried out. The results indicate that the hollow or mandrel forged products possess better properties.

A. Taherizadeh; A. Najafizadeh; R. Shateri; J. J. Jonas

2006-01-01

274

Comparative assessment of fatigue and fracture behaviour of cast and forged railway wheels  

Microsoft Academic Search

A comparative evaluation of fatigue and fracture behaviour of commercially produced cast and forged rail wheels has been made using specimens extracted from various locations of the wheel quadrant. A systematic investigation in the web and rim regions of the wheel quadrant with various notch orientations showed that the forged material exhibited a better intrinsic resistance to fatigue crack growth

S. TARAFDER; S. S IVAPRASAD; V. R. R ANGANATH

275

Effects of Process Parameters on Ultrasonic Micro-Hole Drilling in Glass and Ruby  

NASA Astrophysics Data System (ADS)

Brittle materials such as ceramics, glasses and oxide single crystals find increasing applications in advanced micro-engineering products. Machining small features in such materials represents a manufacturing challenge. Ultrasonic drilling constitutes a promising technique for realizing simple micro-holes of high diameter-to-depth ratio. The process involves impacting abrasive particles in suspension in a liquid slurry between tool and work piece. Among the process performance criteria, the drilling time (productivity) is one of the most important quantities to evaluate the suitability of the process for industrial applications. This paper summarizes recent results pertaining to the ultrasonic micro-drilling process obtained with a semi-industrial 3-axis machine. The workpiece is vibrated at 40 kHz frequency with an amplitude of several micrometers. A voice-coil actuator and a control loop based on the drilling force impose the tool feed. In addition, the tool is rotated at a prescribed speed to improve the drilling speed as well as the hole geometry. Typically, a WC wire serves as tool to bore 200 ?m diameter micro-holes of 300 to 1,000 ?m depth in glass and ruby. The abrasive slurry contains B4C particles of 1 ?m to 5 ?m diameter in various concentrations. This paper discusses, on the basis of the experimental results, the influence of several parameters on the drilling time. First, the results show that the control strategy based on the drilling force allows to reach higher feed rates (avoiding tool breakage). Typically, a 8 um/s feed rate is achieved with glass and 0.9 ?m/s with ruby. Tool rotation, even for values as low as 50 rpm, increases productivity and improves holes geometry. Drilling with 1 ?m and 5 ?m B4C particles yields similar productivity results. Our future research will focus on using the presented results to develop a model that can serve to optimize the process for different applications.

Schorderet, Alain; Deghilage, Emmanuel; Agbeviade, Kossi

2011-05-01

276

Variation of thermal and mechanical properties of KMPR due to processing parameters  

NASA Astrophysics Data System (ADS)

We present a study of the thermal and mechanical properties of the negative photoresist KMPR and the influence of processing conditions on those properties. The process parameters chosen all relate to the cross-linking level of the photoresist: the UV exposure dose, the baking temperature and the bake length. The stability of KMPR at high temperatures was also examined. The glass transition temperature was measured using dynamic mechanical analysis, with a maximum measured value of 128 °C achieved in our tests. Relating the glass transition temperature to the cross-linking level of the material, exposure doses higher than 2 J cm-2 were shown to have a negligible effect on the cross-linking (for 80 ?m thick films). Using thermogravitmetric analysis, KMPR has been shown to lose significant mass when heated above 200 °C. Young's modulus of KMPR was measured to be between 2.0 GPa for samples hard-baked at 100 °C and 2.7 GPa for samples baked at 150 and 200 °C. Creep behavior for KMPR held under strain was studied for samples prepared under a range of processing temperatures. Finally the thermally-induced cross-linking of unexposed KMPR was studied, with samples post-exposure baked at 150 °C, or 120 °C for at least an hour, cross-linking sufficiently to prevent development.

Reynolds, Matthew; Elias, Anastasia; Elliott, Duncan G.; Backhouse, Christopher; Sameoto, Dan

2012-12-01

277

Scalable Hyper-parameter Estimation for Gaussian Process Based Time Series Analysis  

SciTech Connect

Gaussian process (GP) is increasingly becoming popular as a kernel machine learning tool for non-parametric data analysis. Recently, GP has been applied to model non-linear dependencies in time series data. GP based analysis can be used to solve problems of time series prediction, forecasting, missing data imputation, change point detection, anomaly detection, etc. But the use of GP to handle massive scientific time series data sets has been limited, owing to its expensive computational complexity. The primary bottleneck is the handling of the covariance matrix whose size is quadratic in the length of the time series. In this paper we propose a scalable method that exploit the special structure of the covariance matrix for hyper-parameter estimation in GP based learning. The proposed method allows estimation of hyper parameters associated with GP in quadratic time, which is an order of magnitude improvement over standard methods with cubic complexity. Moreover, the proposed method does not require explicit computation of the covariance matrix and hence has memory requirement linear to the length of the time series as opposed to the quadratic memory requirement of standard methods. To further improve the computational complexity of the proposed method, we provide a parallel version to concurrently estimate the log likelihood for a set of time series which is the key step in the hyper-parameter estimation. Performance results on a multi-core system show that our proposed method provides significant speedups as high as 1000, even when running in serial mode, while maintaining a small memory footprint. The parallel version exploits the natural parallelization potential of the serial algorithm and is shown to perform significantly better than the serial faster algorithm, with speedups as high as 10.

Chandola, Varun [ORNL; Vatsavai, Raju [ORNL

2010-01-01

278

Effect of forging strain rate and deformation temperature on the mechanical properties of warm-worked 304L stainless steel  

Microsoft Academic Search

Stainless steel 304L forgings were produced with four different types of production forging equipment – hydraulic press, mechanical press, screw press, and high-energy rate forging (HERF). Each machine imparted a different nominal strain rate during the deformation. The final forgings were done at the warm working (low hot working) temperatures of 816°C, 843°C, and 871°C. The objectives of the study

N. T. Switzner; C. J. Van Tyne; M. C. Mataya

2010-01-01

279

Optimization of Machining Process Parameters for Surface Roughness of Al-Composites  

NASA Astrophysics Data System (ADS)

Metal matrix composites (MMCs) have become a leading material among the various types of composite materials for different applications due to their excellent engineering properties. Among the various types of composites materials, aluminum MMCs have received considerable attention in automobile and aerospace applications. These materials are known as the difficult-to-machine materials because of the hardness and abrasive nature of reinforcement element-like silicon carbide particles. In the present investigation Al-SiC composite was produced by stir casting process. The Brinell hardness of the alloy after SiC addition had increased from 74 ± 2 to 95 ± 5 respectively. The composite was machined using CNC turning center under different machining parameters such as cutting speed (S), feed rate (F), depth of cut (D) and nose radius (R). The effect of machining parameters on surface roughness (Ra) was studied using response surface methodology. Face centered composite design with three levels of each factor was used for surface roughness study of the developed composite. A response surface model for surface roughness was developed in terms of main factors (S, F, D and R) and their significant interactions (SD, SR, FD and FR). The developed model was validated by conducting experiments under different conditions. Further the model was optimized for minimum surface roughness. An error of 3-7 % was observed in the modeled and experimental results. Further, it was fond that the surface roughness of Al-alloy at optimum conditions is lower than that of Al-SiC composite.

Sharma, S.

2013-10-01

280

Tailoring wet explosion process parameters for the pretreatment of cocksfoot grass for high sugar yields.  

PubMed

The pretreatment of lignocellulosic biomass is crucial for efficient subsequent enzymatic hydrolysis and ethanol fermentation. In this study, wet explosion (WEx) pretreatment was applied to cocksfoot grass and pretreatment conditions were tailored for maximizing the sugar yields using response surface methodology. The WEx process parameters studied were temperature (160-210 °C), retention time (5-20 min), and dilute sulfuric acid concentration (0.2-0.5 %). The pretreatment parameter set E, applying 210 °C for 5 min and 0.5 % dilute sulfuric acid, was found most suitable for achieving a high glucose release with low formation of by-products. Under these conditions, the cellulose and hemicellulose sugar recovery was 94 % and 70 %, respectively. The efficiency of the enzymatic hydrolysis of cellulose under these conditions was 91 %. On the other hand, the release of pentose sugars was higher when applying less severe pretreatment conditions C (160 °C, 5 min, 0.2 % dilute sulfuric acid). Therefore, the choice of the most suitable pretreatment conditions is depending on the main target product, i.e., hexose or pentose sugars. PMID:23709291

Njoku, S I; Ahring, B K; Uellendahl, H

2013-08-01

281

Combustion synthesis and effects of processing parameters on physical properties of {alpha}-alumina  

SciTech Connect

Fine particle porous {alpha}-alumina has been prepared by a wet chemical method of combustion synthesis using an aqueous precursor containing aluminum nitrate (oxidizer) and carbohydrazide, an organic fuel as starting materials. The aluminum nitrate and carbohydrazide were reacted exothermically at 400--600 C. The synthesis of {alpha}-alumina ({alpha}-Al{sub 2}O{sub 3}) was used as a model for understanding the effects of processing parameters on physical properties such as surface area, average pore size, and residual carbon content. The porous powders were characterized using x-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area analysis and elemental analysis. The decomposition of the starting materials was investigated using differential thermal and thermogravimetric analyses (DTA/TGA). It has been shown that the furnace temperature, fuel/oxidizer ratio, and precursor water content can be tailored to produce powders with different physical properties.

Collins, M.V.; Hirschfeld, D.A.; Shea, L.E.

2000-01-04

282

Effects of plasma collection systems and processing parameters on the quality of factor IX concentrate.  

PubMed

Using pilot-scale production of our present factor IX (II and X) concentrate, we have studied the effects of starting plasma source and processing parameter on two in-vitro indicators of product quality - yield and thrombogenic potential. Plasma source did not affect factor IX yield but had a marked effect on thrombogenic potential. Factor IX concentrates produced from plasma derived through centrifugation-based technology showed significantly higher thrombogenic potential than products derived from plasma derived through a filtration-based system. Removal of Cohn fraction I prior to ion-exchange chromatography resulted in a drop in factor IX yield and thrombogenic potential, as did heat treatment to 80 degrees C for 72 h. We conclude that a membrane-filtration-based plasmapheresis system may be the preferred method of plasma procurement for factor IX concentrate production. PMID:2800464

Farrugia, A; Spiers, D; Young, I; Oates, A; Herrington, R; Damianos, F

1989-01-01

283

Fabrication of cylindrical plastic microlens using Er:YAG laser beam: influence of process parameters  

NASA Astrophysics Data System (ADS)

Microlenses are widely used as components of optical device in LCD display, optical interconnection, scanner and others. It is important to fabricate microlens in any kind of form to satisfy any requirement of optical device. Also, the integration of microlens and optical devices is required to save weight, reduce production cost, and get higher accurate alignment. We have developed a novel method to fabricate spherical plastic microlens using Er:YAG laser beam. In this method, laser beam are shot to the surface of an acrylate resin to form microlens on this surface. In this paper, a method to fabricate cylindrical plastic microlens is proposed. Microlenses are fabricated under several conditions, and the influences of process parameters to geometry of microlens will be discussed.

Mochtady, Hery; Yamada, Keiji; Ueda, Takashi; Hosokawa, Akira

2004-10-01

284

Optimization of residual stresses in MMC's through the variation of interfacial layer architectures and processing parameters  

NASA Technical Reports Server (NTRS)

The objective of this work was the development of efficient, user-friendly computer codes for optimizing fabrication-induced residual stresses in metal matrix composites through the use of homogeneous and heterogeneous interfacial layer architectures and processing parameter variation. To satisfy this objective, three major computer codes have been developed and delivered to the NASA-Lewis Research Center, namely MCCM, OPTCOMP, and OPTCOMP2. MCCM is a general research-oriented code for investigating the effects of microstructural details, such as layered morphology of SCS-6 SiC fibers and multiple homogeneous interfacial layers, on the inelastic response of unidirectional metal matrix composites under axisymmetric thermomechanical loading. OPTCOMP and OPTCOMP2 combine the major analysis module resident in MCCM with a commercially-available optimization algorithm and are driven by user-friendly interfaces which facilitate input data construction and program execution. OPTCOMP enables the user to identify those dimensions, geometric arrangements and thermoelastoplastic properties of homogeneous interfacial layers that minimize thermal residual stresses for the specified set of constraints. OPTCOMP2 provides additional flexibility in the residual stress optimization through variation of the processing parameters (time, temperature, external pressure and axial load) as well as the microstructure of the interfacial region which is treated as a heterogeneous two-phase composite. Overviews of the capabilities of these codes are provided together with a summary of results that addresses the effects of various microstructural details of the fiber, interfacial layers and matrix region on the optimization of fabrication-induced residual stresses in metal matrix composites.

Pindera, Marek-Jerzy; Salzar, Robert S.

1996-01-01

285

Property and microstructure evaluation as a function of processing parameters: Large HY-80 steel casting for a US Navy submarine  

Microsoft Academic Search

Processing techniques can significantly alter the properties of a material and can ultimately determine whether a component will perform its function safely. This effort involves the investigation of the processing parameters of HY-80 steel castings; specifically a large HY-80 submarine casting that failed while in service due to improper processing. Samples taken from the failed casting were evaluated in the

John E. Holthaus; Michelle G. Koul; Angela L. Moran

2006-01-01

286

Research on the limiting parameters of the upgrading process for polystyrene wastes coming from packing industries  

NASA Astrophysics Data System (ADS)

During the last years many companies have implanted quality systems to ensure quality for both materials and processes; this new philosophy has arrived to recycling industry on which quality considerations are of maximum relevance. So, some recycling companies, with minimum enterprise projection, have developed quality systems that ensure certain quality levels for materials they offer. Otherwise, we have no data to think about the use of this philosophy to material reception. In the present work, we analyse the different variables that take part on the upgrading process for polystyrene wastes coming from packing industry; we make a differentiation between those parameters related with the material structure and those related with processing conditions. Once we have identified these critical variables they are individually investigated by using different analytical techniques such as differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), thermogravimetrical analysis (TGA) and gas chromatography-mass spectrometry (GC-MS). The use of these techniques has allowed to identify changes on polystyrene characteristics when subjected to certain conditions such as temperature, environmental agents action (mainly UV radiation), presence of small amounts of impurities (mainly PP). This study about high impact polystyrene has allowed to know much more about the critical variables influencing on its characteristics (mechanical, thermal...). Furthermore, we have used and optimized different techniques to evaluate changes on its behaviour. All these studies have established the main aspects to be considered to develop a rigorous quality control process also for material reception and for final material. This study will help recycling companies to define the basis to obtain a quality certificate for upgraded high impact polystyrene.

Parres Garcia, Francisco J.

287

76 FR 5331 - Forged Stainless Steel Flanges From India and Taiwan: Final Results of Sunset Reviews and...  

Federal Register 2010, 2011, 2012, 2013

...A-533-809, A-583-821] Forged Stainless Steel Flanges From India and Taiwan...antidumping duty orders on forged stainless steel flanges from India and Taiwan...duty orders on certain forged stainless steel flanges from India and...

2011-01-31

288

76 FR 31631 - Heavy Forged Hand Tools From China; Scheduling of Expedited Five-Year Reviews Concerning the...  

Federal Register 2010, 2011, 2012, 2013

...731-TA-457-A-D Third Review] Heavy Forged Hand Tools From China; Scheduling of Expedited...Antidumping Duty Orders on Heavy Forged Hand Tools From China. AGENCY: United States...antidumping duty orders on heavy forged hand tools from China would be likely to...

2011-06-01

289

77 FR 39997 - Heavy Forged Hand Tools, Finished or Unfinished, With or Without Handles From the People's...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-570-803] Heavy Forged Hand Tools, Finished or Unfinished, With or...antidumping duty review on heavy forged hand tools, finished or unfinished, with or...United States). \\2\\ See Heavy Forged Hand Tools, Finished or Unfinished, With...

2012-07-06

290

Investigation of critical core formulation and process parameters for osmotic pump oral drug delivery.  

PubMed

Push-pull osmotic pump (PPOP) tablets of a practically insoluble model drug were developed and the effect of various formulation and process parameters on tablet performance was evaluated in order to identify critical factors. The formulation factors such as the viscosity grade of polyethylene oxide as the primary polymer as well as the level and location of osmogen within the bilayer tablets led to a difference in performance of osmotic tablets and hence should be critically evaluated in the design of such dosage forms. Modification of granulation process, i.e., the granulating liquid composition or drying method of granules, did not impact the drug release from the osmotic tablets at the evaluated scale of this study. The influence of varying dose and aqueous solubility of other model drugs (i.e., theophylline, acetaminophen, and verapamil HCl) on the developed PPOP template was also investigated. Results showed that irrespective of the perceived complexity of development and manufacturing of osmotic pumps, the osmotic tablets in this study demonstrated a robust and yet flexible platform in accommodating different types of drug candidates, regardless of solubility, for the dose levels below 25% w/w of the pull layer formulation. PMID:24222269

Missaghi, Shahrzad; Patel, Piyush; Farrell, Thomas P; Huatan, Hiep; Rajabi-Siahboomi, Ali R

2014-02-01

291

Can standard surface EMG processing parameters be used to estimate motor unit global firing rate?  

NASA Astrophysics Data System (ADS)

The relations between motor unit global firing rates and established quantitative measures for processing the surface electromyogram (EMG) signals were explored using a simulation approach. Surface EMG signals were simulated using the reported properties of the first dorsal interosseous muscle in man, and the models were varied systematically, using several hypothetical relations between motor unit electrical and force output, and also using different motor unit firing rate strategies. The utility of using different EMG processing parameters to help estimate global motor unit firing rate was evaluated based on their relations to the number of motor unit action potentials (MUAPs) in the simulated surface EMG signals. Our results indicate that the relation between motor unit electrical and mechanical properties, and the motor unit firing rate scheme are all important factors determining the form of the relation between surface EMG amplitude and motor unit global firing rate. Conversely, these factors have less impact on the relations between turn or zero-crossing point counts and the number of MUAPs in surface EMG. We observed that the number of turn or zero-crossing points tends to saturate with the increase in the MUAP number in surface EMG, limiting the utility of these measures as estimates of MUAP number. The simulation results also indicate that the mean or median frequency of the surface EMG power spectrum is a poor indicator of the global motor unit firing rate.

Zhou, Ping; Zev Rymer, William

2004-06-01

292

Modeling the Influence of Process Parameters and Additional Heat Sources on Residual Stresses in Laser Cladding  

NASA Astrophysics Data System (ADS)

In laser cladding thermal contraction of the initially liquid coating during cooling causes residual stresses and possibly cracks. Preweld or postweld heating using inductors can reduce the thermal strain difference between coating and substrate and thus reduce the resulting stress. The aim of this work is to better understand the influence of various thermometallurgical and mechanical phenomena on stress evolution and to optimize the induction-assisted laser cladding process to get crack-free coatings of hard materials at high feed rates. First, an analytical one-dimensional model is used to visualize the most important features of stress evolution for a Stellite coating on a steel substrate. For more accurate studies, laser cladding is simulated including the powder-beam interaction, the powder catchment by the melt pool, and the self-consistent calculation of temperature field and bead shape. A three-dimensional finite element model and the required equivalent heat sources are derived from the results and used for the transient thermomechanical analysis, taking into account phase transformations and the elastic-plastic material behavior with strain hardening. Results are presented for the influence of process parameters such as feed rate, heat input, and inductor size on the residual stresses at a single bead of Stellite coatings on steel.

Brückner, F.; Lepski, D.; Beyer, E.

2007-09-01

293

Optimization of processing parameters and metrology for novel NCA negative resists for NGL  

NASA Astrophysics Data System (ADS)

It is expected that EUV resists must simultaneously pattern 20-nm half-pitch and below, with an LWR of <1.8 nm, and a sensitivity of 5-20 mJ/cm2. In order to make a resist perform optimally, new resist chemistry is required. One such approach being investigated by us is the development of polymeric non-CAR negative photo resists for sub 16 nm technology which is directly sensitive to radiation without utilizing the concept of chemical amplification (CARs). These resist designs are accomplished by homopolymers which are prepared from monomers containing sulfonium groups. We have achieved 20 nm patterns by e-beam lithography using this system. Here we will discuss in detail process parameters such as: spinning conditions for film thicknesses <50 nm and resulting surface topographies, baking regimes, exposure conditions and protocols on sensitivity, contrast, resolution and LER/LWR. Etch resistance data on these thin films will also be provided. Our results are aimed to provide a clear understanding of how these critical steps in the lithographic imaging process will affect extendibility of the non-CAR resist concept to sub 20 nanoscale features. Photodynamics and EUV exposure data will be covered.

Singh, Vikram; Satyanarayana, V. S. V.; Kessler, Felipe; Scheffer, Francine R.; Weibel, Daniel E.; Sharma, Satinder K.; Ghosh, Subrata; Gonsalves, Kenneth E.

2014-04-01

294

Pod of Ultrasonic Detection of Synthetic Hard Alpha Inclusions in Titanium Aircraft Engine Forgings  

NASA Astrophysics Data System (ADS)

The probability of detection (POD) of inspection techniques is a key input to estimating the lives of structural components such as aircraft engines. This paper describes work conducted as a part of the development of POD curves for the ultrasonic detection of synthetic hard alpha (SHA) inclusions in titanium aircraft engine forgings. The sample upon which the POD curves are to be based contains four types of right circular SHAs that have been embedded in a representative titanium forging, as well as a number of flat bottomed holes (FBHs). The SHAs were of two sizes, ?3 and ?5, with each size including seeds with nominal nitrogen concentrations of both 3 and 17 wt. %. The FBHs included sizes of ?1, ?3, and ?5. This discreteness of the data poses a number of challenges to standard processes for determining POD. For example, at each concentration of nitrogen, there are only two sizes, with 10 inspection opportunities each. Fully empirical, standard methodologies such as â versus a provide less than an ideal framework for such an analysis. For example, there is no way to describe the beam limiting effect whereby the signal no longer increases the flaw grows larger than the beam, one can only determine POD at the two concentration levels present in the block, and confidence bounds tend to be broad because of the limited data available for each case. In this paper, we will describe strategies involving the use of physics-based models to overcome these difficulties by allowing the data from all reflectors to be analyzed by a single statistical model. Included will be a discussion of the development of the physics-based model, its comparison to the experimental data (obtained at multiple sites with multiple operators) and its implications regarding the statistical analysis, whose details will be given in a separate article by Li et al. in this volume.

Thompson, R. B.; Meeker, W. Q.; Brasche, L. J. H.

2011-06-01

295

Optimizing Vacuum Assisted Resin Transfer Moulding (VARTM) Processing Parameters to Improve Part Quality  

NASA Astrophysics Data System (ADS)

The Low Cost Composites (LCC) group at Carleton University is studying out-of-autoclave composite manufacturing processes such as Vacuum Assisted Resin Transfer Moulding (VARTM) and Closed Cavity Bag Moulding (CCBM). These processes are used to produce inexpensive and high performance components for the GeoSurv II, an Unmanned Aerial Vehicle (UAV) being developed at Carleton University. This research has focused on optimizing VARTM processing parameters to reduce the weight and improve the strength and surface finish of GeoSurv II composite components. A simulation was developed to model resin flow through in VARTM infusions and was used to simulate mould filling and resin emptying of the GeoSurv II inverted V-empennage and mission avionics hatch. The resin infusion schemes of these parts were designed to ensure full preform resin saturation, and minimize thickness variations. An experimental study of the effects of the presence of a corner on composite thickness, void content, and strength was conducted. It was found that inside corners result in local increases in thickness and void content due to poor preform compaction. A novel bagging technique was developed to improve corner compaction, and this technique was shown to reduce thickness variability and void content. The strength, void content, and thickness variation were found to be heavily dependent on corner radius, with corner radii greater than 6.4 mm displaying the greatest improvement in performance for the layups considered. The design of the empennage and hatch mould incorporated the results of this study to improve the quality of these components.

Polowick, Christopher

296

Chronic alcohol exposure negatively impacts the physiological and molecular parameters of the renal biotin reabsorption process.  

PubMed

Normal body homeostasis of biotin is critically dependent on its renal recovery by kidney proximal tubular epithelial cells, a process that is mediated by the sodium-dependent multivitamin transporter (SMVT; a product of the SLC5A6 gene). Chronic ethanol consumption interferes with the renal reabsorption process of a variety of nutrients, including water-soluble vitamins. To date, however, there is nothing known about the effect of chronic alcohol feeding on physiological and molecular parameters of the renal biotin reabsorption process. We addressed these issues using rats and transgenic mice carrying the human SLC5A6 (P1P2) 5'-regulatory region as an in vivo model systems of alcohol exposure, and cultured human renal proximal tubular epithelial HK-2 cells chronically exposed to alcohol as an in vitro model of alcohol exposure. The [(3)H]biotin uptake results showed that chronic ethanol feeding in rats leads to a significant inhibition in carrier-mediated biotin transport across both renal brush border and basolateral membrane domains. This inhibition was associated with a marked reduction in the level of expression of SMVT protein, mRNA, and heterogenous nuclear RNA (hnRNA). Furthermore, studies with transgenic mice carrying the SLC5A6 5'-regulatory region showed that chronic alcohol feeding leads to a significant decrease in promoter activity. Studies with HK-2 cells chronically exposed to alcohol again showed a marked reduction in carrier-mediated biotin uptake, which was associated with a significant reduction in promoter activity of the human SLC5A6 5'-regulatory region. These findings demonstrate for the first time that chronic ethanol feeding inhibits renal biotin transport and that this effect is, at least in part, being exerted at the transcriptional level. PMID:21209005

Subramanian, Veedamali S; Subramanya, Sandeep B; Said, Hamid M

2011-03-01

297

Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly- L-lactide (PLLA): Part I. Basic characteristics  

Microsoft Academic Search

Compounds that had neither calcined nor sintered hydroxyapatite (u-HA) particles (particulate size 0.2–20?m, averaging 3.0?m, Ca\\/P=1.69, and containing CO2-3) uniformly distributed in a poly-L-lactide (PLLA, M?v: 400KDa) matrix with a content of 20–50wt% (with 10% increment) were reinforced into composites by a forging process, which was a unique compression molding, and were then machined on a lathe in order to

Y Shikinami; M Okuno

1999-01-01

298

Effects of Process Parameters on Ultrasonic Micro-Hole Drilling in Glass and Ruby  

SciTech Connect

Brittle materials such as ceramics, glasses and oxide single crystals find increasing applications in advanced micro-engineering products. Machining small features in such materials represents a manufacturing challenge. Ultrasonic drilling constitutes a promising technique for realizing simple micro-holes of high diameter-to-depth ratio. The process involves impacting abrasive particles in suspension in a liquid slurry between tool and work piece. Among the process performance criteria, the drilling time (productivity) is one of the most important quantities to evaluate the suitability of the process for industrial applications.This paper summarizes recent results pertaining to the ultrasonic micro-drilling process obtained with a semi-industrial 3-axis machine. The workpiece is vibrated at 40 kHz frequency with an amplitude of several micrometers. A voice-coil actuator and a control loop based on the drilling force impose the tool feed. In addition, the tool is rotated at a prescribed speed to improve the drilling speed as well as the hole geometry. Typically, a WC wire serves as tool to bore 200 {mu}m diameter micro-holes of 300 to 1,000 {mu}m depth in glass and ruby. The abrasive slurry contains B4C particles of 1 {mu}m to 5 {mu}m diameter in various concentrations.This paper discusses, on the basis of the experimental results, the influence of several parameters on the drilling time. First, the results show that the control strategy based on the drilling force allows to reach higher feed rates (avoiding tool breakage). Typically, a 8 um/s feed rate is achieved with glass and 0.9 {mu}m/s with ruby. Tool rotation, even for values as low as 50 rpm, increases productivity and improves holes geometry. Drilling with 1 {mu}m and 5 {mu}m B4C particles yields similar productivity results. Our future research will focus on using the presented results to develop a model that can serve to optimize the process for different applications.

Schorderet, Alain; Deghilage, Emmanuel; Agbeviade, Kossi [Ecole Polytechnique Federale de Lausanne (EPFL), School of Engineering (STI), Mechanical Systems Design Laboratory - LCSM, Station No. 9, CH-1015 Lausanne (Switzerland)

2011-05-04

299

Processing parameters optimization of multiple quality characteristics of open-end rotor spinning process for Bamboo charcoal and CVC blended fibers  

Microsoft Academic Search

In the field of yarn spinning engineering, the importance of the processing parameters taken depends directly on the quality\\u000a characteristics of the yarn. This study aimed to find the optimal processing parameters for an open-end rotor spinning frame\\u000a at work to identify its multiple quality characteristics for yarn. In this study, Bamboo charcoal and cotton 70 %\\/polyester\\u000a 30 % (CVC)

Chung-Feng Jeffrey Kuo; Hsin-Jung Wei; Chang-Chiun Huang; Te-Li Su

2010-01-01

300

Crack toughness evaluation of hot pressed and forged beryllium  

NASA Technical Reports Server (NTRS)

Beryllium fracture toughness test specimens were fatigue cracked using reversed cycling with a compression load two to three times the tension load. In worked beryllium, textures may be produced which result in fatigue cracks that are out of plane with the starter notch. Specimens of hot pressed stock exhibited load displacement records which were nonlinear throughout their course. Fracture specimens of both hot pressed and forged stock showed essentially no reduction of thickness and the fracture surfaces were flat and normal to the load axis. However, the stress intensity factor at maximum load increased with decreasing thickness. Load-displacement and electric potential records for the hot pressed beryllium specimens exhibited several anomalies such as negative residual crack mouth displacements and a decrease in electrical potential with increasing load.

Jones, M. H.; Bubsey, R. T.; Brown, W. F., Jr.

1971-01-01

301

Process Parameters in Resistance Projection Welding for Optical Transmission Device Package  

NASA Astrophysics Data System (ADS)

The effects of main process parameters and electrode materials on joint quality (charging voltage and operating force) were investigated using detailed metallurgical examination and the helium leak test. The electrode materials used for resistance projection welding were brass and Cr-Cu alloy. The TO-Can components (cap and header) were nickel-coated SPCC steel. The results indicated that when the operating pressure increased, the electrode displacement increased, causing expulsion and distortion of the welds. The nugget area increased with the increase of charging voltage; however, it decreased with the increase of operating pressure. Results from the optical microscopy analysis showed that a larger acceptable welding range was achieved by using Cr-Cu electrodes. TO-Can in the acceptable and expulsion range successfully passed the helium leak rate of less than 5 × 10-8 mbar L/s. For commercial purposes, where dimensions have to be exact and without deformation, the TO-Can components produced in the expulsion zone cannot be used.

Huang, Her-Yueh; Tseng, Kuang-Hung

2011-03-01

302

Aqueous HPMCAS coatings: effects of formulation and processing parameters on drug release and mass transport mechanisms.  

PubMed

The major aim of the present work was to study the effects of various formulation and processing parameters on the resulting drug release kinetics from theophylline matrix pellets coated with aqueous hydroxypropyl methylcellulose acetate succinate (HPMCAS) dispersions. The plasticizer content, coating level and curing conditions significantly affected the release patterns in 0.1 M HCl, whereas no major effects were observed in phosphate buffer, pH 7.4. Due to the significant size of the HPMCAS particles (being in the micrometer range), their coalescence was particularly crucial and not complete upon coating. Consequently, at low coating levels continuous water-filled channels connected the bead cores with the release medium through which the drug could rapidly diffuse, resulting in high release rates even at low pH. In contrast, at high coating levels such continuous connections did not exist (due to the increased number of polymer particle layers), and drug release was controlled by diffusion through the macromolecular network resulting in much lower release rates in 0.1 M HCl. Importantly, pellet curing at elevated temperature and ambient relative humidity or exposure to elevated relative humidity at room temperature did not significantly alter the microstructure of the coatings, leading to only slightly decreased drug release rates. In contrast, pellet curing at elevated temperature combined with elevated relative humidity induced significant further polymer particle coalescence, resulting in a change of the underlying drug release mechanism and significantly reduced drug release rates. PMID:16621484

Siepmann, Florence; Siepmann, Juergen; Walther, Mathias; MacRae, Ross; Bodmeier, Roland

2006-07-01

303

Analysis of the non-Markov parameter in continuous-time signal processing  

NASA Astrophysics Data System (ADS)

The use of statistical complexity metrics has yielded a number of successful methodologies to differentiate and identify signals from complex systems where the underlying dynamics cannot be calculated. The Mori-Zwanzig framework from statistical mechanics forms the basis for the generalized non-Markov parameter (NMP). The NMP has been used to successfully analyze signals in a diverse set of complex systems. In this paper we show that the Mori-Zwanzig framework masks an elegantly simple closed form of the first NMP, which, for C1 smooth autocorrelation functions, is solely a function of the second moment (spread) and amplitude envelope of the measured power spectrum. We then show that the higher-order NMPs can be constructed in closed form in a modular fashion from the lower-order NMPs. These results provide an alternative, signal processing-based perspective to analyze the NMP, which does not require an understanding of the Mori-Zwanzig generating equations. We analyze the parametric sensitivity of the zero-frequency value of the first NMP, which has been used as a metric to discriminate between states in complex systems. Specifically, we develop closed-form expressions for three instructive systems: band-limited white noise, the output of white noise input to an idealized all-pole filter,f and a simple harmonic oscillator driven by white noise. Analysis of these systems shows a primary sensitivity to the decay rate of the tail of the power spectrum.

Varghese, J. J.; Bellette, P. A.; Weegink, K. J.; Bradley, A. P.; Meehan, P. A.

2014-02-01

304

Process parameter effects on material removal in magnetorheological finishing of borosilicate glass.  

PubMed

We investigate the effects of processing parameters on material removal for borosilicate glass. Data are collected on a magnetorheological finishing (MRF) spot taking machine (STM) with a standard aqueous magnetorheological (MR) fluid. Normal and shear forces are measured simultaneously, in situ, with a dynamic dual load cell. Shear stress is found to be independent of nanodiamond concentration, penetration depth, magnetic field strength, and the relative velocity between the part and the rotating MR fluid ribbon. Shear stress, determined primarily by the material mechanical properties, dominates removal in MRF. The addition of nanodiamond abrasives greatly enhances the material removal efficiency, with the removal rate saturating at a high abrasive concentration. The volumetric removal rate (VRR) increases with penetration depth but is insensitive to magnetic field strength. The VRR is strongly correlated with the relative velocity between the ribbon and the part, as expected by the Preston equation. A modified removal rate model for MRF offers a better estimation of MRF removal capability by including nanodiamond concentration and penetration depth. PMID:20357881

Miao, Chunlin; Lambropoulos, John C; Jacobs, Stephen D

2010-04-01

305

Method of validating measurement data of a process parameter from a plurality of individual sensor inputs  

DOEpatents

A method for generating a validated measurement of a process parameter at a point in time by using a plurality of individual sensor inputs from a scan of said sensors at said point in time. The sensor inputs from said scan are stored and a first validation pass is initiated by computing an initial average of all stored sensor inputs. Each sensor input is deviation checked by comparing each input including a preset tolerance against the initial average input. If the first deviation check is unsatisfactory, the sensor which produced the unsatisfactory input is flagged as suspect. It is then determined whether at least two of the inputs have not been flagged as suspect and are therefore considered good inputs. If two or more inputs are good, a second validation pass is initiated by computing a second average of all the good sensor inputs, and deviation checking the good inputs by comparing each good input including a present tolerance against the second average. If the second deviation check is satisfactory, the second average is displayed as the validated measurement and the suspect sensor as flagged as bad. A validation fault occurs if at least two inputs are not considered good, or if the second deviation check is not satisfactory. In the latter situation the inputs from each of all the sensors are compared against the last validated measurement and the value from the sensor input that deviates the least from the last valid measurement is displayed.

Scarola, Kenneth (Windsor, CT); Jamison, David S. (Windsor, CT); Manazir, Richard M. (North Canton, CT); Rescorl, Robert L. (Vernon, CT); Harmon, Daryl L. (Enfield, CT)

1998-01-01

306

The effect of process parameters on the surface finish of plasma polymers  

SciTech Connect

The surface finish of plasma polymers deposited in an inductively coupled discharge were measured as a function of gas flow rates. Surface finish was measured both optically and by AFM. The process parameters of the plasma polymerization were found to effect the surface finish. The gases used were trans-2- butene and hydrogen for hydrocarbon polymers. For bromocarbon polymers we added ethylbromide. The smoothest hydrocarbon polymer coatings had an RMS surface finish better than 1 nm. Bumps 200 nm high spaced approximately 1 {mu}m apart grew on the surface of bromocarbon coatings when they were exposed to air. The composition of the bumps was found to be NH{sub 4}Br by XRD and XPS analysis. We believe that nitrogen (from a small leak or desorption) dissociates in the discharge and reacts with hydrogen to form ammonia. The ammonia then reacts with HBr, a dissociation product of ethylbromide, to form NH{sub 4}Br which is dispersed throughout the deposited layer. Humidity facilitates the transport of the NH{sub 4}Br to the surface where it crystallizes. Bump growth was prevented by either dry storage or overcoating with 3 {mu}m of hydrocarbon plasma polymer. Alternatively, the bumps could be washed from the surface with water.

Letts, S.A.; Cook, R.C.; Welch, P.; McEachern, R.; Fearon, E.

1992-12-09

307

Engine Performance of Precision-forged, Electropolished and Machined Blades of Nimonic 80 and 80A Alloys  

NASA Technical Reports Server (NTRS)

An investigation was conducted to determine the effect of electropolishing precision-forged blades and of machining blades from oversize forgings on the engine performance of Nimonic 80 and Nimonic 80A turbine blades. These blades, along with precision-forged blades, were run in a J33-9 turbojet engine. The tests resulted in the following conclusions: (1) Electropolishing of precision-forged blades did not improve engine life relative to the life of nonelectropolished blades. (2) Machining blades from oversize forgings did not improve the engine life of precision-forged blades. (3) The precision-forging and heat-treating practice used in fabricating the blades investigated was such that the surface roughness and oxide penetration was so slight, approximately 0.0005 inch in depth, as to preclude any benefits derived from surface removal by electropolishing or machining.

Sikora, Paul F; Johnston, James R

1955-01-01

308

Effects of different processing parameters on the semisolid microstructure of the AZ91D alloy during partial remelting  

Microsoft Academic Search

The effects of different processing parameters, such as heating rate, isothermal temperature and isothermal holding time, on the semisolid microstructures of the AZ91D alloy during partial remelting had been investigated in the present paper. The experimental result showed that the high heating rate shortened the growth process of renascent recrystal grains in the deformed alloys, which ultimately attributed to refine

J. G. Wang; H. Q. Lin; H. Y. Wang; Q. C. Jiang

2008-01-01

309

The use of grey-based Taguchi methods to determine submerged arc welding process parameters in hardfacing  

Microsoft Academic Search

In this paper, the use of grey-based Taguchi methods for the optimization of the submerged arc welding (SAW) process parameters in hardfacing with considerations of multiple weld qualities is reported. In this new approach, the grey relational analysis is adopted to solve the SAW process with multiple weld qualities. A grey relational grade obtained from the grey relational analysis is

Y. S. Tarng; S. C. Juang; C. H. Chang

2002-01-01

310

The effects of cutting tool geometry and processing parameters on the surface roughness of AISI 1030 steel  

Microsoft Academic Search

In this study, we have investigated the effects of different insert radii of cutting tools, different depths of cut and, different feed rates on the surface quality of the workpieces depending on various processing parameters. Properly, the AISI 1030 steel is processed at a digitally controlled computerised numerical control(CNC) turning lathe without using cooling water with three different insert radii

Hasan Gökkaya; Muammer Nalbant

2007-01-01

311

Optimising FSW process parameters to minimise defects and maximise fatigue life in 5083-H321 aluminium alloy  

Microsoft Academic Search

This paper presents a systematic approach to optimising FSW process parameters (tool rotational speed and feed rate) through consideration of frictional power input. Frictional power governs the tensile strength and the fatigue life in this 5083-H321 alloy through its effect on plastic flow processes in the thermo-mechanically affected zone (TMAZ) of the weld. Although, a close relationship therefore exists between

H. Lombard; D. G. Hattingh; A. Steuwer; M. N. James

2008-01-01

312

Optimization of process parameters for pulsed laser milling of micro-channels on AISI H13 tool steel  

E-print Network

selection Laser milling process a b s t r a c t This paper focuses on understanding the influence of laser. Whenever metals are used, the laser beam heats, melts and vaporizes the metal (metal sublimation), whileOptimization of process parameters for pulsed laser milling of micro-channels on AISI H13 tool

Ozel, Tugrul

313

Optimization of process parameters for foam-mat drying of papaya pulp.  

PubMed

Experiments were carried out to optimize the process parameters for production of papaya powder using foam-mat drying. Papaya pulp was foamed by incorporating methyl cellulose (0.25, 0.5, 0.75 and 1 %, w/w), glycerol-mono-stearate (1, 2, 3 and 4 %, w/w) and egg white (5, 10, 15 and 20 %, w/w) as foaming agents. The maximum stable foam formation was 72, 90 and 125% at 0.75 % methyl cellulose, 3 % glycerol-mono-stearate and 15 % egg white respectively with 9°Brix pulp and whipping time of 20 min. The foamed pulp was dried at air temperature of 60, 65 and 70 °C with foam thickness of 2, 4, 6, 8 and 10 mm in a batch type cabinet dryer. The drying time required for foamed papaya pulp was lower than non-foamed pulp at all selected temperatures. Biochemical analysis results showed a significant reduction in ascorbic acid, ?-carotene and total sugars in the foamed papaya dried product at higher foam thickness (6, 8 and 10 mm) and temperature (65 and 70 °C due to destruction at higher drying temperature and increasing time. There was no significant change in other biochemical constituents such as pH and acidity. The organoleptic and sensory evaluation of the quality attributes of papaya powder obtained from the pulp of 9°Brix added with 3 % glycerol-mono-stearate, whipped for 20 min and dried with a foam thickness of 4 mm at a temperature of 60 °C was found to be optimum to produce the foam-mat dried papaya powder. PMID:25328192

Kandasamy, Palani; Varadharaju, N; Kalemullah, S; Maladhi, D

2014-10-01

314

Development of Processing Parameters for Organic Binders Using Selective Laser Sintering  

NASA Technical Reports Server (NTRS)

This document describes rapid prototyping, its relation to Computer Aided Design (CAD), and the application of these techniques to choosing parameters for Selective Laser Sintering (SLS). The document reviews the parameters selected by its author for his project, the SLS machine used, and its software.

Mobasher, Amir A.

2003-01-01

315

75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...  

Federal Register 2010, 2011, 2012, 2013

...Administration [TA-W-70,376] Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood Forge Division; Currently Known...2, 2009, applicable to workers of Kaiser Aluminum Fabricated Products, LLC, Kaiser...

2010-11-18

316

Experiments in hot-rolling and forging of ductile cast iron  

SciTech Connect

The Bureau of Mines investigated hot-rolling and forging characteristics of experimental ductile iron castings both sand and permanent-mold, made with charges containing up to 70% foundry pig iron and 95% steelmaking pit iron. Between 1550 and 1950/sup 0/F, most castings could be rolled to 90% reduction or forged to 70% reduction without serious cracking. Charge and composition have less bearing on workability than on subsequent properties. Permanent mold castings could be worked as readily as sand castings at 1750 and 1950/sup 0/F. Plasticity improved with temperature. Small billets were also forged cold to 50% reduction without cracking. The feasibility of die-forging and bar-rolling of ductile iron was evaluated in trial tests conducted under a Bureau contract. Although workability and ductility of ductile iron are inferior to those of steel, more advantage could be taken of ductile iron's plasticity to work rough shapes to final dimensions.

Neumeier, L.A.; Betts, B.A.; Crosby, R.L.

1980-01-01

317

Processing of thermal parameters for the assessment of geothermal potential of sedimentary basins  

NASA Astrophysics Data System (ADS)

The growing interest on renewable energy sources is stimulating new efforts aimed at the assessment of geothermal potential in several countries, and new developments are expected in the near future. In this framework, a basic step forward is to focus geothermal investigations on geological environments which so far have been relatively neglected. Some intracontinental sedimentary basins could reveal important low enthalpy resources. The evaluation of the geothermal potential in such geological contexts involves the synergic use of geophysical and hydrogeological methodologies. In sedimentary basins a large amount of thermal and hydraulic data is generally available from petroleum wells. Unfortunately, borehole temperature data are often affected by a number of perturbations which make very difficult determination of the true geothermal gradient. In this paper we addressed the importance of the acquisition of thermal parameters (temperature, geothermal gradient, thermal properties of the rock) and the technical processing which is necessary to obtain reliable geothermal characterizations. In particular, techniques for corrections of bottom-hole temperature (BHT) data were reviewed. The objective was to create a working formula usable for computing the undisturbed formation temperature for specific sedimentary basins. As test areas, we analysed the sedimentary basins of northern Italy. Two classical techniques for processing temperature data from oil wells are customarily used: (i) the method by Horner, that requires two or more measurements of bottom-hole temperatures carried out at the same depth but at different shut-in times te and (ii) the technique by Cooper and Jones, in which several physical parameters of the mud and formation need to be known. We applied both methods to data from a number of petroleum explorative wells located in two areas of the Po Plain (Apenninic buried arc and South Piedmont Basin - Pedealpine homocline). From a set of about 40 wells having two or more temperature measurements at a single depth we selected 18 wells with BHTs recorded at te larger than 3.5 hours; the time span between two measurements varies from 1 to 21 hours. In total 71 couples of BHT-te data are available; the mud circulation time is lower or equal to 4.5 hours. Corrections require the knowledge of thermal parameters. We attempted to remedy the existing deficiency of thermal conductivity data of sedimentary rocks with a series of laboratory measurements on several core samples recovered from wells. Moreover, we developed a model for calculating the thermal conductivity of the rock matrix as a function of mineral composition based on the fabric theory and experimental thermal conductivity data. As the conductivity of clay minerals, which are present in most formations, is poorly defined, we applied an inverse approach, in which mineral conductivities are calculated one by one, on condition that the sample bulk thermal conductivity, the porosity and the amount of each mineral phase are known. Analyses show that formation equilibrium temperatures computed with the Horner method are consistent with those obtained by means of the Cooper and Jones method, which gives on average temperatures lower than 2 C only for shut-in times < 10 hours. The corrected temperatures compared with temperatures measured during drill-stem tests show that the proposed corrections are rather accurate. The two data sets give coherent results and the inferred average geothermal gradient is 21.5 mK/m in the Apenninic buried arc area and 25.2 mK/m in the South Piedmont Basin-Pedealpine homocline area. The problem with the Horner method is that it implicitly assumes no physical property contrast between circulating mud and formation, and that the borehole is infinitesimally thin, i.e. it acts as a line source. This has been criticized by many authors. The accuracy of the predicted temperatures depends on the reliability and accuracy of BHT, shut-in time and mud circulation time, and the error increases with the decrease of the shut-in time. On the ot

Pasquale, V.; Chiozzi, P.; Gola, G.; Verdoya, M.

2009-04-01

318

OPTICAL IMAGE PROCESSING: Effect of the parameters of a wide-aperture acousto-optic filter on the image processing quality  

NASA Astrophysics Data System (ADS)

The properties of wide-aperture paratellurite crystal acousto-optic filters used for optical image processing are studied. The influence of parameters of these filters on the quality of optical imaging in laser and nonmonochromatic light is studied. The spatial resolution of filters is measured upon laser and nonmonochromatic illumination of objects. Filtration is performed in a broad wavelength range at different powers of a control electric signal. The optimisation of the filter parameters for improving its spatial resolution is discussed.

Voloshinov, V. B.; Bogomolov, D. V.

2006-05-01

319

Nine percent nickel steel heavy forging weld repair study. [National Transonic Wind Tunnel fan components  

NASA Technical Reports Server (NTRS)

The feasibility of making weld repairs on heavy section 9% nickel steel forgings such as those being manufactured for the National Transonic Facility fan disk and fan drive shaft components was evaluated. Results indicate that 9% nickel steel in heavy forgings has very good weldability characteristics for the particular weld rod and weld procedures used. A comparison of data for known similar work is included.

Young, C. P., Jr.; Gerringer, A. H.; Brooks, T. G.; Berry, R. F., Jr.

1978-01-01

320

Microstructural evolution of a delta containing nickel-base superalloy during heat treatment and isothermal forging  

E-print Network

, it is clear that the determination of the dominant deformation mechanism was complicated by the significant fraction of ?? present in the material, as ?? precipitates have been observed to inhibit recrystallisation in Udimet 720 when forged > 30?C below its... polycrystalline ?-??-? ternary eutectic Ni-base superalloy, Materials Science and Engineering A, vol. 586, p236–244, 2013 22. H. Monajati, M. Jahazi, S. Yue, A.K. Taheri, Deformation characteristics of isothermally forged Udimet 720 nickel-base superalloy...

Mignanelli, P. M.; Jones, N. G.; Perkins, K. M.; Hardy, M. C.; Stone, H. J.

2014-11-06

321

Forging convictions: the effects of active participation in a clinical trial.  

PubMed

This qualitative study explored non-specific influences on participation in, and outcomes of, a randomised controlled trial. It was nested within a single-blind clinical trial of western acupuncture which compared real acupuncture with two types of placebo control administered to National Health Service (NHS) patients awaiting hip and knee replacement surgery in England. Data collection (2004-2008) was based on narrative-style interviews and participant observation. The results indicate that trial recruitment and retention depend on a set of convictions forged largely as a result of contextual factors peripheral to the intervention, including the friendliness and helpfulness of research centre staff and status of the administering practitioner. These convictions also influence the reporting of the study outcomes, particularly if participants experience uncertainties when choosing an appropriate response. The findings suggest that participants in clinical trials are actively involved in shaping the research process, rather than passive recipients of treatment. Thus the outcomes of trials, notably those involving contact interventions, should be regarded not as matters of fact, but as products of complex environmental, social, interpretive and biological processes. In this paper, we develop and present a 'theory of active research participation' which offers a framework for understanding the impact of non-specific processes in clinical trials. PMID:21636195

Scott, Clare; Walker, Jan; White, Peter; Lewith, George

2011-06-01

322

NOVEL VAPOR-DEPOSITED LUBRICANTS FOR METAL-FORMING PROCESSES  

EPA Science Inventory

The report gives results of a preliminary laboratory study of the feasibility of using vapor-phase lubrication to lubricate industrial metal forging dies. (NOTE: the forging and shaping of metal parts is one of many metal fabricating processes that may generate volatile organic c...

323

FORMING PROCESS OF SCREW SPIKE IN DOUBLE CONFIGURATION  

Microsoft Academic Search

Summary. In this paper technology of screw spikes manufacturing, based on the flashless forging and hot rolling in double configuration, is presented. The forging takes place in closed dies and the obtained workpiece is rolled in its middle part on cross-wedge rolling mill in order to make screw thread. As the result of this process, it is possible to eliminate

COMPLAS VIII; S. Wero?ski; Andrzej Gontarz; Zbigniew Pater

324

Effect of process parameters on porosity distributions in high-pressure die-cast AM50 Mg-alloy  

Microsoft Academic Search

High-pressure die-casting is the preferred manufacturing process for cast Mg-alloy components used for numerous applications. High-pressure die-cast components usually contain micro-porosity that adversely affects their mechanical properties. In this contribution, the effects of three important process parameters, gate velocity, intensification pressure, and melt temperature on the micro-porosity distributions in high-pressure die-cast AM50 Mg-alloy are quantitatively characterized. The amounts of total

S. G. Lee; A. M. Gokhale; G. R. Patel; M. Evans

2006-01-01

325

Effect of direct laser re-melting processing parameters and scanning strategies on the densification of tool steels  

Microsoft Academic Search

The effect of processing parameters and scanning strategies on the processing of H13 tool steel by direct laser re-melting (DLRM) has been investigated. The density of samples produced was significantly increased by the use of a modified knit-scan strategy. The effects of line spacing and scan speed were also studied, with optimum values of 0.10mm and 100–150mm\\/s, respectively, being established.

J. W. Xie; P. Fox; W. O’Neill; C. J. Sutcliffe

2005-01-01

326

Refurbishment of fatigue-cracked generator rotor forgings  

SciTech Connect

In a paper presented at the 1994 IJPGC in Phoenix, AZ, TVA discussed the management of a fleet of fourteen generator rotors which had developed cracks in the axial cooling holes under the retaining rings and in the radial cooling holes in the rotor body. The management consisted of establishing the root cause of the crack initiation and propagation, initially establishing the flaw size distribution by eddy-current testing (ECT), performing reinspection at appropriate intervals, preheating the rotor prior to startup, lowering overspeed trip settings to 105%, confirming overspeed trip response by simulation rather than actual overspeed, and maintaining a spare generator rotor. Since the 1994 paper, one of the rotors developed an electrical liability, forcing its removal from service. While a replacement rotor which was on hand resolved the immediate crisis, the long term options were: (1) operate without a spare, (b) procure a new rotor with substantially improved mechanical properties and slightly improved electrical performance, or (c) refurbish the existing forging. After an exhaustive economic analysis, option C was identified as the most cost effective solution. This paper addresses the 43-inch rotor rehabilitation and rewind that has been successfully executed for less than half the cost of a new replacement rotor, without loss in operating flexibility.

Roberts, B.W.; Zielke, W.; Puri, A.

1996-12-31

327

Laser transmission welding of ABS: Effect of CNTs concentration and process parameters on material integrity and weld formation  

NASA Astrophysics Data System (ADS)

This paper reports a study of the laser transmission welding of polymeric joints composed by two ABS (acrylonitrile/butadiene/styrene) sheets, one transparent (natural ABS) and the other absorbent (filled by different percentages of carbon nanotubes (CNTs)). The objective of this work is to analyze the effect of process parameters and CNTs concentrations on weld formation and mechanical resistance of the weld joints.

Rodríguez-Vidal, E.; Quintana, I.; Gadea, C.

2014-04-01

328

Process parameter selection for optimizing the weld pool geometry in the tungsten inert gas welding of stainless steel  

Microsoft Academic Search

In this paper, the selection of process parameters for obtaining an optimal weld pool geometry in the tungsten inert gas (TIG) welding of stainless steel is presented. Basically, the geometry of the weld pool has several quality characteristics, for example, the front height, front width, back height and back width of the weld pool. To consider these quality characteristics together

S. C Juang; Y. S Tarng

2002-01-01

329

Effect of Some Process Parameters on the Separation of the Dispersed Ferrous Impurities Using Cycled Electromagnetic Filter  

Microsoft Academic Search

Electromagnetic filters (EMFs) can be effectively used for the cleaning of both industrial and domestic disposals such as waste water having low concentration and micron size of dispersed particles that show magnetic characteristics. In this work, we investigated the effect of some parameters of the filtration process, external magnetic field density, size of the filter matrix elements, filter length, filtration

Zehra Y?ld?z; Teymuraz Abbasov; Ayse Sar?mesel?

2010-01-01

330

Parametric study of suspension plasma spray processing parameters on coating microstructures manufactured from nanoscale yttria-stabilized zirconia  

Microsoft Academic Search

A parametric study was conducted to determine the effect of suspension plasma spray (SPS) processing parameters, including plasma torch standoff, suspension injection velocity, injector location, powder loading in the suspension, and torch power, on the final microstructure of coatings fabricated from 80nm diameter yttria-stabilized zirconia (YSZ) powders. Coatings made with different conditions were analyzed via stereology techniques for the amount

Kent VanEvery; Matthew John M. Krane; Rodney W. Trice

331

Optimisation of Lime-Soda process parameters for reduction of hardness in aqua-hatchery practices using Taguchi methods.  

PubMed

This paper presents the optimisation of Lime-Soda process parameters for the reduction of hardness in aqua-hatchery practices in the context of M. rosenbergii. The fresh water in the development of fisheries needs to be of suitable quality. Lack of desirable quality in available fresh water is generally the confronting restraint. On the Indian subcontinent, groundwater is the only source of raw water, having varying degree of hardness and thus is unsuitable for the fresh water prawn hatchery practices (M. rosenbergii). In order to make use of hard water in the context of aqua-hatchery, Lime-Soda process has been recommended. The efficacy of the various process parameters like lime, soda ash and detention time, on the reduction of hardness needs to be examined. This paper proposes to determine the parameter settings for the CIFE well water, which is pretty hard by using Taguchi experimental design method. Orthogonal Arrays of Taguchi, Signal-to-Noise Ratio, the analysis of variance (ANOVA) have been applied to determine their dosage and analysed for their effect on hardness reduction. The tests carried out with optimal levels of Lime-Soda process parameters confirmed the efficacy of the Taguchi optimisation method. Emphasis has been placed on optimisation of chemical doses required to reduce the total hardness using Taguchi method and ANOVA, to suit the available raw water quality for aqua-hatchery practices, especially for fresh water prawn M. rosenbergii. PMID:24749379

Yavalkar, S P; Bhole, A G; Babu, P V Vijay; Prakash, Chandra

2012-04-01

332

Influence of process parameters on electrochemical and physical properties of sputtered iron-doped nickel oxide thin films  

Microsoft Academic Search

The iron-doped nickel oxide films used as oxygen evolution catalysts in the photoelectrochemical production of hydrogen from solar energy were deposited by means of RF reactive magnetron sputtering from a Ni-Fe alloy target in oxygen and argon atmosphere. The effects of processing parameters on the film properties, such as overpotential, composition, surface morphology and preferred orientation, were investigated. The electrochemical

Jin-zhao HUANG; Zhen XU; Hai-ling LI; Guo-hu KANG; Wen-jing WANG

2006-01-01

333

Comparison of pitting fatigue life of ausforged and standard forged AISI M-50 and AISI 9310 spur gears  

NASA Technical Reports Server (NTRS)

Standard forged and ausforged spur gears made of vacuum-induction-melted, consumable-electrode, vacuum-arc-remelted AISI M-50 steel were tested under conditions that produced fatigue pitting. The gears were 8.89 cm (3.5 in.) in pitch diameter and had tip relief. The M-50 standard forged and ausforged test results were compared with each other. They were then compared with results for machined vacuum-arc-remelted AISI 9310 gears tested under identical conditions. Both types of M-50 gears had lives approximately five times that of the 9310 gears. The life at which 10 percent of the M-50 ausforged gears failed was slightly less than that at which the M-50 standard forged gears failed. The ausforged gears had a slightly greater tendency to fail by tooth fracture than did the standard forged gears, most likely because of the better forging and grain flow pattern of standard forged gears.

Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

1975-01-01

334

Parameter estimation and model comparison for stochastic epidemiological processes in a Bayesian framework  

NASA Astrophysics Data System (ADS)

We compare two stochastic epidemiological models in a Bayesian framework, both models performing on the same simulated data set. In some cases of data obtained under one model with specific parameter values the model comparison favours the model not underlying the simulated data.

Mateus, Luis; Stollenwerk, Nico; Zambrini, Jean Claude

2012-09-01

335

Tests for Parameter Instability in Regressions with 1(1) Processes  

Microsoft Academic Search

This article derives the large-sample distributions of Lagrange multiplier (LM) tests for parameter instability against several alternatives of interest in the context of cointegrated regression models. The fully modified estimator of Phillips and Hansen is extended to cover general models with stochastic and deterministic trends. The test statistics considered include the SupF test of Quandt, as well as the LM

Bruce E. Hansen

1992-01-01

336

Processes and parameters involved in modeling radionuclide transport from bedded salt repositories. Final report. Technical memorandum  

Microsoft Academic Search

The parameters necessary to model radionuclide transport in salt beds are identified and described. A proposed plan for disposal of the radioactive wastes generated by nuclear power plants is to store waste canisters in repository sites contained in stable salt formations approximately 600 meters below the ground surface. Among the principal radioactive wastes contained in these canisters will be radioactive

D. E. Evenson; T. A. Prickett; P. A. Showalter

1979-01-01

337

An investigation of transferability of parameter tuning and optimization process for a convective parameterization scheme in the WRF model  

NASA Astrophysics Data System (ADS)

In this study, a number of issues related to uncertainty quantification (UQ) and parameter tuning in climate model were investigated by using the Weather Research and Forecasting (WRF) model. We identified five key input parameters in the new Kain-Fritsch (KF) convective parameterization scheme in WRF to investigate the response and sensitivity of model output to those parameters and to optimize the model performance by reducing the uncertainty of those parameters. Two stochastic importance sampling algorithms were employed and compared to efficiently sample the input parameters. We evaluated the transferability of UQ and parameter tuning across spatial scales, climatic regions/regimes, parameterization schemes, evaluation metrics and sampling methods. Some common features can be seen in all simulations across the Southern Great Plains (SGP) and the North America Monsoon (NAM) region, three model spatial resolutions (i.e. 12km, 25km and 50km), two radiation schemes (RRTMG and CAM), and two sampling methods (MVFSA and DASAMC). We found that the model performance is sensitive to downdraft and entrainment-related parameters and consumption time of Convective Available Potential Energy (CAPE). The spatial pattern of the precipitation is most sensitive to entrainment flux rate. Simulated convective precipitation increases with the decrease of the ratio of downdraft to updraft flux. More stratiform but less convective precipitation is produced with lager CAPE consumption time and this feature is more significant over the NAM region. The simulation using optimal parameters obtained by constraining only precipitation generated positive impact on the other process-level variables. The optimal values for five input parameters are close across different spatial resolutions, radiation schemes, climate regions or using different sampling approaches.

Yan, H.; Qian, Y.; Yang, B.; Lin, G.; Leung, L.; Fu, Q.

2012-12-01

338

Maize-Based Gluten-Free Bread: Influence of Processing Parameters on Sensory and Instrumental Quality  

Microsoft Academic Search

The performance of maize bread with spongy texture is still a technological challenge due to the absence of a natural network\\u000a required for holding the carbon dioxide released during the fermentation process. The objective of this research was to investigate\\u000a the influence of different maize varieties (regional and hybrid), milling process (electric and water mill), formulation and\\u000a processing variables on

Carla Brites; Maria João Trigo; Carla Santos; Concha Collar; Cristina M. Rosell

2010-01-01

339

Observation of pressure gradient and related flow rate effect on the plasma parameters in plasma processing reactor  

SciTech Connect

In industrial plasma processes, flow rate has been known to a key to control plasma processing results and has been discussed with reactive radical density, gas residence time, and surface reaction. In this study, it was observed that the increase in the flow rate can also change plasma parameters (electron temperature and plasma density) and electron energy distribution function in plasma processing reactor. Based on the measurement of gas pressure between the discharge region and the pumping port region, the considerable differences in the gas pressure between the two regions were found with increasing flow rate. It was also observed that even in the discharge region, the pressure gradient occurs at the high gas flow rate. This result shows that increasing the flow rate results in the pressure gradient and causes the changes in the plasma parameters.

Lee, Hyo-Chang; Kim, Aram; Chung, Chin-Wook [Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Moon, Se Youn [Solar Energy Group, LG Electronics Advanced Research Institute, 16 Woomyeon-Dong, Seocho-Gu, Seoul 137-724 (Korea, Republic of)

2011-02-15

340

Effect of process parameters on properties of Al-Si alloys cast by Rapid Slurry Formation (RSF) technique  

NASA Astrophysics Data System (ADS)

Rapid slurry formation is a semi-solid metal forming technique, which is based on a so-called solid enthalpy exchange material (EEM). It is a fascinating technology offering the opportunity to manufacture net-shaped metal components of complex geometry in a single forming operation. At the same time, high mechanical properties can be achieved due to the unique microstructure and flow behaviour. The major process parameters used in the RSF process are rotation speed of the EEM, melt superheat, amount of EEM added (determining fs), and holding time. The process parameters can be well controlled with clear effects on the microstructure. There is a lack of theoretical modelling of the morphological evolution in these two-phase slurries.

Ratke, L.; Sharma, A.; Kohli, D.

2012-01-01

341

Identification of Friction Parameters from the Inverse Analysis of a Direct Extrusion Test  

SciTech Connect

This work proposes to use a special upsetting test and an optimal direct extrusion one performed to identify the constitutive equation of the material behavior and the friction coefficients directly from the load-stroke curves. The proposed friction test has the advantage to permit to take into account contact phenomena corresponding to new specimen surfaces created during a real bulk cold forming process. A lot of numerical simulations are made with the commercial software FORGE2 in order to study the influence of some design and process parameters. Different friction laws will be identified starting from the classical Coulomb and Tresca ones. All the parameter identifications are made using the Inverse Analysis principle.

Adinel, Gavrus; Thien, Pham Duc [LGCGM Laboratory, EA 3913, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France); Henri, Francillette [SCR/CM, UMR 6226, INSA de RENNES, UEB, CS70839, F-35708, Rennes-Cedex 7 (France)

2011-01-17

342

Effect of processing parameter and filler content on tensile properties of multi-walled carbon nanotubes reinforced polylactic acid nanocomposite  

NASA Astrophysics Data System (ADS)

Polymer nanocomposite of multi-walled carbon nanotubes (MWCNT) nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method using the Haake Rheomix internal mixer. In order to obtain the optimal processing parameter, the nanocomposite with 89 wt % of PLA was blended with 10 wt % of LNR and 1 wt % of MWCNTs were mixed with various mixing parameter condition; mixing temperature, mixing speed and mixing time. The optimum processing parameter of the composites was obtained at temperature of 190°C, rotation speed of 90 rpm and mixing time of 14 min. Next, the effect of MWCNTs loading on the tensile properties of nanocomposites was investigated. The nanocomposites were melt blended using the optimal processing parameter with MWCNTs loading of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4 wt %. The result showed that the sample with 3.5 wt % of MWCNTs gave higher tensile strength and Young's modulus. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA nanocomposites. However, the elongation at break decreased with increasing the percentage of MWCNTs.

Ali, Adilah Mat; Ahmad, Sahrim Hj.

2013-05-01

343

Wavelet-Based Parameter Estimation for Polynomial Contaminated Fractionally Differenced Processes  

E-print Network

of estimating the param- eters for a stochastic process using a time series containing a trend component. Trend in models such as fractionally differenced (FD) processes, which exhibit slowly decaying auto- correlations in a model of polynomial trend plus FD noise. Using Daubechies wavelet filters allows for automatic

Percival, Don

344

An intelligent parameter selection system for the direct metal laser sintering process  

Microsoft Academic Search

As one of the promising Rapid Prototyping (RP) processes, the Direct Metal Laser Sintering (DMLS) technique is capable of building prototype parts by depositing and melting metal powders layer by layer. Metal powder can be melted directly to build functional prototype tools. During fabrication, four important resulting properties of interest to the users are: the processing time, mechanical properties, geometric

Y. Ning; J. Y. H. Fuh; Y. S. Wong; H. T. Loh

2004-01-01

345

Effects of processing parameters on consolidation and microstructure of W–Cu components by DMLS  

Microsoft Academic Search

The densification behavior and attendant microstructural characteristics of direct laser sintered submicron W–Cu\\/micron Cu powder system under different processing conditions were investigated in this work. The methods for improving the controllability of laser processing were elucidated. A “linear energy density (LED)”, which was defined by the ratio of laser power to scan speed, was used to tailor the powder melting

Dongdong Gu; Yifu Shen

2009-01-01

346

Powder metallurgy processing of high strength turbine disk alloys  

NASA Technical Reports Server (NTRS)

Using vacuum-atomized AF2-1DA and Mar-M432 powders, full-scale gas turbine engine disks were fabricated by hot isostatically pressing (HIP) billets which were then isothermally forged using the Pratt & Whitney Aircraft GATORIZING forging process. While a sound forging was produced in the AF2-1DA, a container leak had occurred in the Mar-M432 billet during HIP. This resulted in billet cracking during forging. In-process control procedures were developed to identify such leaks. The AF2-1DA forging was heat treated and metallographic and mechanical property evaluation was performed. Mechanical properties exceeded those of Astroloy, one of the highest temperature capability turbine disk alloys presently used.

Evans, D. J.

1976-01-01

347

Validating Mechanistic Sorption Model Parameters and Processes for Reactive Transport in Alluvium  

SciTech Connect

The laboratory batch and flow-through experiments presented in this report provide a basis for validating the mechanistic surface complexation and ion exchange model we use in our hydrologic source term (HST) simulations. Batch sorption experiments were used to examine the effect of solution composition on sorption. Flow-through experiments provided for an analysis of the transport behavior of sorbing elements and tracers which includes dispersion and fluid accessibility effects. Analysis of downstream flow-through column fluids allowed for evaluation of weakly-sorbing element transport. Secondary Ion Mass Spectrometry (SIMS) analysis of the core after completion of the flow-through experiments permitted the evaluation of transport of strongly sorbing elements. A comparison between these data and model predictions provides additional constraints to our model and improves our confidence in near-field HST model parameters. In general, cesium, strontium, samarium, europium, neptunium, and uranium behavior could be accurately predicted using our mechanistic approach but only after some adjustment was made to the model parameters. The required adjustments included a reduction in strontium affinity for smectite, an increase in cesium affinity for smectite and illite, a reduction in iron oxide and calcite reactive surface area, and a change in clinoptilolite reaction constants to reflect a more recently published set of data. In general, these adjustments are justifiable because they fall within a range consistent with our understanding of the parameter uncertainties. These modeling results suggest that the uncertainty in the sorption model parameters must be accounted for to validate the mechanistic approach. The uncertainties in predicting the sorptive behavior of U-1a and UE-5n alluvium also suggest that these uncertainties must be propagated to nearfield HST and large-scale corrective action unit (CAU) models.

Zavarin, M; Roberts, S K; Rose, T P; Phinney, D L

2002-05-02

348

Comparison of time-frequency-based techniques for estimating instantaneous frequency parameters of nonstationary processes  

NASA Astrophysics Data System (ADS)

The aim of this work is to contrast techniques used to estimate two instantaneous frequency parameters of the surface electromyographic (EMG) signal, the instantaneous median frequency and the instantaneous mean frequency, based on their estimation error. Three methods are compared: Cohen class and Cohen-Posch class time- frequency representations are used to compute both the above- mentioned instantaneous frequency parameters, and a cross-time- frequency based technique is adopted to derive the instantaneous mean frequency. The results demonstrate that the algorithm based on Cohen-Posch class transformations leads to a standard deviation of the instantaneous frequency parameters that is smaller than that obtained using Cohen class representations. However, the cross- time-frequency estimation procedure for instantaneous mean frequency produced the smallest standard deviation compared to the other techniques. The algorithms based on Cohen class and Cohen- Posch class transformations often provided a lower bias than the cross-time-frequency based technique. This advantage was particularly evident when the instantaneous mean frequency varies non-linearly within the epochs used to derive the cross-time- frequency representation of the surface EMG signal.

Bonato, Paolo; Erim, Zeynep; Roy, Serge H.; De Luca, Carlo J.

1999-11-01

349

Effect of process parameters on properties of argon–nitrogen plasma for titanium nitride film deposition  

SciTech Connect

In this study, the effect of working pressure and input power on the physical properties and sputtering efficiencies of argon–nitrogen (Ar/N{sub 2}) plasma in direct current magnetron discharge is investigated. The discharge in Ar/N{sub 2} is used to deposit TiN films on high speed steel substrate. The physical plasma parameters are determined by using Langmuir probe and optical emission spectroscopy. On the basis of the different reactions in the gas phase, the variation of plasma parameters and sputtering rate are explained. A prominent change of electron temperature, electron density, ion density, and degree of ionization of Ar is found as a function of working pressure and input power. The results also show that increasing working pressure exerts a negative effect on film deposition rate while increasing input power has a positive impact on the same. To confirm the observed physical properties and evaluate the texture growth as a function of deposition parameters, x-ray diffraction study of deposited TiN films is also done.

Saikia, Partha; Kakati, Bharat [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur-782 402, Kamrup, Assam (India)] [Centre of Plasma Physics, Institute for Plasma Research, Nazirakhat, Sonapur-782 402, Kamrup, Assam (India)

2013-11-15

350

A review of signal processing used in the implementation of the pulse oximetry photoplethysmographic fluid responsiveness parameter.  

PubMed

?POP is a physiological parameter derived from the respiration-induced change in the pulse oximetry plethysmographic (POP) waveform or "pleth." It has been proposed as a proxy for pulse pressure variation used in the determination of the response to intravascular volume expansion in hypovolemic patients. Many studies have now reported on the parameter, and many research groups have constructed algorithms for its computation from the first principles where the implementation details have been described. This review focuses on the signal processing aspects of ?POP, as reported in the literature, and aims to provide a comprehensive summary of the wide-ranging algorithmic strategies that have been attempted in its computation. A search was conducted for articles concerning the use of ?POP as a fluid responsiveness parameter. In particular, articles concerning the correlation between ?POP and pulse pressure variation were targeted. Comments and replies to comments by the authors in which signal processing aspects were discussed were also included in the review. The parameter is first defined, and a history of the early work surrounding pleth-based fluid responsiveness parameters is presented. This is followed by an overview of the signal processing methods used in the reported studies, including details of exclusion criteria, manual filtering (preprocessing), gain change issues, acquisition details, selection of registration periods, averaging methods, physiological influences on the pleth, and comments by the investigators themselves. It is concluded that to develop a robust, fully automated ?POP algorithm for use in the clinical environment, more rigorous signal processing is required. Specifically, signals should be evaluated over significant periods of time, with emphasis on the quality and temporal relevance of the information. PMID:25405691

Addison, Paul S

2014-12-01

351

Microstructural characteristics of aluminum 2024 by cold working in the SIMA process  

Microsoft Academic Search

The SSF (semi-solid forging) is compound forging technology to manufacture near net shaped parts. For SSF, it is necessarily required to prepare a workpiece with a globular microstructure. Amongst several processes to obtain a globular microstructure, the SIMA (strain induced melt activated) process is very simple and advantageous with respect to equipment. This paper presents the influence of effective strain

Jae Chan Choi; Hyung Jin Park

1998-01-01

352

Improved Warm-Working Process For An Iron-Base Alloy  

NASA Technical Reports Server (NTRS)

Warm-working process produces predominantly unrecrystallized grain structure in forgings of iron-base alloy A286 (PWA 1052 composition). Yield strength and ultimate strength increased, and elongation and reduction of area at break decreased. Improved process used on forgings up to 10 in. thick and weighing up to 900 lb.

Cone, Fred P.; Cryns, Brendan J.; Miller, John A.; Zanoni, Robert

1992-01-01

353

Femtosecond laser ablation properties of transparent materials: impact of the laser process parameters on the machining throughput  

NASA Astrophysics Data System (ADS)

High average power, high repetition rate femtosecond lasers with ?J pulse energies are increasingly used for bio-medical and material processing applications. With the introduction of femtosecond laser systems such as the SpiritTM platform developed by High Q Lasers and Spectra-Physics, micro-processing of solid targets with femtosecond laser pulses have obtained new perspectives for industrial applications [1]. The unique advantage of material processing with subpicosecond lasers is efficient, fast and localized energy deposition, which leads to high ablation efficiency and accuracy in nearly all kinds of solid materials. The study on the impact of the laser processing parameters on the removal rate for transparent substrate using femtosecond laser pulses will be presented. In particular, examples of micro-processing of poly-L-lactic acid (PLLA) - bio-degradable polyester and XensationTM glass (Schott) machined with SpiritTM ultrafast laser will be shown.

Matylitsky, V. V.; Hendricks, F.; Aus der Au, J.

2013-03-01

354

Tensile behavior of an austenitic stainless steel subjected to multidirectional forging  

NASA Astrophysics Data System (ADS)

The mechanical behavior of a chromium-nickel austenitic stainless steel with submicrocrystalline structures produced by multidirectional forging (MDF) to a total strain of ~ 4 at temperatures of 700 and 600°C was studied. This processing resulted in the formation of uniform ultrafine grained structure with an average crystallite size of 360 and 300 nm, respectively, and high dislocation density. The tensile tests were carried out in a wide temperature range 20-650°C. At ambient temperature, the yield stress (YS) comprised 900 MPa and 730 MPa in the samples subjected to MDF at 600 and 700°C, respectively. It should be noted that this strength was achieved along with elongations of 16% and 22% in the samples subjected to MDF at 600 and 700°C. The YS decreased and elongation-to-failure tends to increase with increasing test temperature and approaching 235 MPa and 51%, respectively, at 650°C. Effect of temperature on mechanical behavior of stainless steel with submicrocrystalline structure is discussed.

Tikhonova, M.; Sorokopudova, J.; Bondareva, E.; Belyakov, A.; Kaibyshev, R.

2014-08-01

355

Forging Hispanic communities in new destinations: A case study of Durham, NC1  

PubMed Central

The Chicago School of urban sociology and its extension in the spatial assimilation model have provided the dominant framework for understanding the interplay between immigrant social and spatial mobility. However, the main tenets of the theory were derived from the experience of pre-war, centralized cities; scholars falling under the umbrella of the Los Angeles school have recently challenged the extent to which they are applicable to the contemporary urban form, which is characterized by sprawling, decentralized, and multi-nucleated development. Indeed, new immigrant destinations, such as those scattered throughout the American Southeast, are both decentralized and lack prior experience with large scale immigration. Informed by this debate this paper traces the formation and early evolution of Hispanic neighborhoods in Durham, NC, a new immigrant destination. Using qualitative data we construct a social history of immigrant neighborhoods and apply survey and census information to examine the spatial pattern of neighborhood succession. We also model the sorting of immigrants across neighborhoods according to personal characteristics. Despite the many differences in urban form and experience with immigration, the main processes forging the early development of Hispanic neighborhoods in Durham are remarkably consistent with the spatial expectations from the Chicago School, though the sorting of immigrants across neighborhoods is more closely connected to family dynamics and political economy considerations than purely human capital attributes. PMID:24482612

Flippen, Chenoa A.; Parrado, Emilio A.

2013-01-01

356

BIOPHYSICAL PARAMETER ESTIMATION WITH ADAPTIVE GAUSSIAN PROCESSES G. Camps-Valls1  

E-print Network

`encia, Spain. gustavo.camps@uv.es, http://www.uv.es/gcamps ABSTRACT We evaluate Gaussian Processes (GPs was easily obtained due to the use of an im- proper prior, which led to inaccurate predictions and poor

Camps-Valls, Gustavo

357

Improved CD uniformity as a function of developer chemistry and process parameters derived from a statistically designed experiment  

NASA Astrophysics Data System (ADS)

A series of experiments was run to determine the chemical and process effects on CD uniformity for Dynachem's new dyed photoresist, NOVA 2050 AR, when developed with metal ion free and metal ion type developers. The matrix of experiments included variations in spray time and puddle time, but with the constraint that all experiments had the same total time for spray and puddle times. In order to do this type of matrix it was necessary to make an unusual use of a mixture model to devise the experimental design. The design was devised to look at the effects of one-puddle, twopuddle, three-puddle and all-spray processes. Also, the effect of using either metal ion free or metal type developers was examined by running the matrix with Dynalith EPD-85 and DE-3 (0.5%) as respective examples of the two developer types. Before beginning the above matrix the baseline parameters for nozzle position, puddle time, spray time, spray speed, pre-wet time, spray pressure and spray time were determined via a Plackett- Burinan design of experiments. These three studies when compiled and analyzed with the statistical software package, RS-l, served to separate the effects of process parameters and developer type according to their effect on CD uniformity. These results suggest that three-puddle metal ion free develop processes were superior. Graphs will be shown that illustrate which parameters are the most influential concerning CD uniformity. A mathematical model will be presented that will allow the calculation of the standard deviation for CD uniformity with 95% confidence for any given set of spray and puddle times. These data and models will thereby give guidance to the process engineer how to best use developer type and process in order to obtain the best CD uniformity for a 1.0 micron process.

Christensen, Lorna D.; Bell, Ken L.; Acuna, Nadine A.

1990-06-01

358

Plasma and mechanical properties and process parameter selection criteria for laser rapid manufacturing  

Microsoft Academic Search

Laser-based techniques to fabricate parts from non- polymer material have been developed in the past years. These processes are referred to as Solid Freeform Fabrication, Rapid Manufacturing, Positive Shaping, Rapid Tooling, and Near-Net Shape Fabrication. Data concerning the energy transfer from the processing laser beam to the material powder, such as the metal vapor-plasma plume temperature and plume absorption coefficient,

Franz-Josef Kahlen

2000-01-01

359

The effect of process parameters on audible acoustic emissions from high-shear granulation.  

PubMed

Product quality in high-shear granulation is easily compromised by minor changes in raw material properties or process conditions. It is desired to develop a process analytical technology (PAT) that can monitor the process in real-time and provide feedback for quality control. In this work, the application of audible acoustic emissions (AAEs) as a PAT tool was investigated. A condenser microphone was placed at the top of the air exhaust on a PMA-10 high-shear granulator to collect AAEs for a design of experiment (DOE) varying impeller speed, total binder volume and spray rate. The results showed the 10 Hz total power spectral densities (TPSDs) between 20 and 250 Hz were significantly affected by the changes in process conditions. Impeller speed and spray rate were shown to have statistically significant effects on granulation wetting, and impeller speed and total binder volume were significant in terms of process end-point. The DOE results were confirmed by a multivariate PLS model of the TPSDs. The scores plot showed separation based on impeller speed in the first component and spray rate in the second component. The findings support the use of AAEs to monitor changes in process conditions in real-time and achieve consistent product quality. PMID:22564031

Hansuld, Erin M; Briens, Lauren; Sayani, Amyn; McCann, Joe A B

2013-02-01

360

Real-Time Parameter Estimation Method Applied to a MIMO Process and its Comparison with an Offline Identification Method  

NASA Astrophysics Data System (ADS)

An experiment based method is proposed for parameter estimation of a class of linear multivariable systems. The method was applied to a pressure-level control process. Experimental time domain input/output data was utilized in a gray-box modeling approach. Prior knowledge of the form of the system transfer function matrix elements is assumed to be known. Continuous-time system transfer function matrix parameters were estimated in real-time by the least-squares method. Simulation results of experimentally determined system transfer function matrix compare very well with the experimental results. For comparison and as an alternative to the proposed real-time estimation method, we also implemented an offline identification method using artificial neural networks and obtained fairly good results. The proposed methods can be implemented conveniently on a desktop PC equipped with a data acquisition board for parameter estimation of moderately complex linear multivariable systems.

Kaplano?lu, Erkan; ?afak, Koray K.; Varol, H. Selçuk

2009-01-01

361

The effect of process parameters on the thermal conditions during moving mold ESR  

SciTech Connect

Several experimental melts were conducted using a moving mold electroslag remelting furnace. The conditions of electrode immersion depth, slag cap thickness, and melt current were varied. Mold wall temperatures and slag pool temperatures were measured and the heat flux through the mold wall was calculated. The relationships between varying ESR melt parameters and the resultant thermal conditions were examined. The thermal profile of the mold, the heat transfer to the mold coolant total and fractional, and the formation of a slag skin were studied.

Heilman, J.E. [Carpenter Technology Corp., Reading, PA (United States); Damkroger, B.K. [Sandia National Labs., Albuquerque, NM (United States)

1994-09-01

362

Computer prediction of process parameters of two-stage gas carburizing  

Microsoft Academic Search

A computer-aided method based on a simplified mathematical model is described for predicting the time parameters of the two-stage\\u000a boost-diffuse gas carburizing.\\u000a \\u000a The main advantage of the computational algorithm lies in its simplicity. Computer times are much shorter than those required\\u000a for finite difference calculations.\\u000a \\u000a \\u000a \\u000a The required input data are the case depth, the surface carbon content, the chemical composition

T. Réti; M. Réger; M. Gergely

1990-01-01

363

Identification of forged Bank of England £20 banknotes using IR spectroscopy  

NASA Astrophysics Data System (ADS)

Bank of England notes of £20 denomination have been studied using infrared spectroscopy in order to generate a method to identify forged notes. An aim of this work was to develop a non-destructive method so that a small, compact Fourier transform infrared spectrometer (FT-IR) instrument could be used by bank workers, police departments or others such as shop assistants to identify forged notes in a non-lab setting. The ease of use of the instrument is the key to this method, as well as the relatively low cost. The presence of a peak at 1400 cm-1 arising from ?asym (CO32-) from the blank paper section of a forged note proved to be a successful indicator of the note's illegality for the notes that we studied. Moreover, differences between the spectra of forged and genuine £20 notes were observed in the ?(OH) (ca. 3500 cm-1), ?(Csbnd H) (ca. 2900 cm-1) and ?(Cdbnd O) (ca. 1750 cm-1) regions of the IR spectrum recorded for the polymer film covering the holographic strip. In cases where these simple tests fail, we have shown how an infrared microscope can be used to further differentiate genuine and forged banknotes by producing infrared maps of selected areas of the note contrasting inks with background paper.

Sonnex, Emily; Almond, Matthew J.; Baum, John V.; Bond, John W.

2014-01-01

364

Plasma Parameters of SRF Cavities for Radio-Frequency Discharge Processing  

NASA Astrophysics Data System (ADS)

Superconducting radio frequency (SRF) cavities of bulk Niobium are accelerating field-generating components of particle accelerators. Cavities are designed to support TM modes at a resonant frequency, which usually serve as their identifier. RF plasma surface modification dry-etching technology as an alternative to the currently existing wet etching technology requires a different RF coupling regime. The choice of power generator frequency greatly affects the field and plasma parameters distribution over the cavity. These are adjusted by a coaxial centerline antenna to provide for optimum level of plasma sheath uniformity. In the search for best etching conditions, we are opting for radio frequency (13.56 MHz, 100 MHz) and microwave frequency plasma (2.45 GHz) in Ar/Cl2 gas mixture. We have developed five optical probes for simultaneous spectroscopic measurements of the plasma properties at five points inside the cavity. The electron temperature and density measurement at the same set of points will be also measured with a Langmuir probe. The measurement of plasma parameters at different pressure and power for the chosen frequency set with varying chlorine content will be presented.

Upadhyay, Janardan; Popovic, Svetozar; Vuskovic, Lepsha; Valente-Feliciano, Anne-Marie; Phillips, Larry

2012-10-01

365

Effects of processing parameters in thermally induced phase separation technique on porous architecture of scaffolds for bone tissue engineering.  

PubMed

Tissue engineering makes use of 3D scaffolds to sustain three-dimensional growth of cells and guide new tissue formation. To meet the multiple requirements for regeneration of biological tissues and organs, a wide range of scaffold fabrication techniques have been developed, aiming to produce porous constructs with the desired pore size range and pore morphology. Among different scaffold fabrication techniques, thermally induced phase separation (TIPS) method has been widely used in recent years because of its potential to produce highly porous scaffolds with interconnected pore morphology. The scaffold architecture can be closely controlled by adjusting the process parameters, including polymer type and concentration, solvent composition, quenching temperature and time, coarsening process, and incorporation of inorganic particles. The objective of this review is to provide information pertaining to the effect of these parameters on the architecture and properties of the scaffolds fabricated by the TIPS technique. PMID:24425207

Akbarzadeh, Rosa; Yousefi, Azizeh-Mitra

2014-08-01

366

Taguchi's off line method and Multivariate loss function approach for quality management and optimization of process parameters -A review  

NASA Astrophysics Data System (ADS)

Off-line quality control is considered to be an effective approach to improve product quality at a relatively low cost. The Taguchi method is one of the conventional approaches for this purpose. Through this approach, engineers can determine a feasible combination of design parameters such that the variability of a product's response can be reduced and the mean is close to the desired target. The traditional Taguchi method was focused on ensuring good performance at the parameter design stage with one quality characteristic, but most products and processes have multiple quality characteristics. The optimal parameter design minimizes the total quality loss for multiple quality characteristics. Several studies have presented approaches addressing multiple quality characteristics. Most of these papers were concerned with maximizing the parameter combination of signal to noise (SN) ratios. The results reveal the advantages of this approach are that the optimal parameter design is the same as the traditional Taguchi method for the single quality characteristic; the optimal design maximizes the amount of reduction of total quality loss for multiple quality characteristics. This paper presents a literature review on solving multi-response problems in the Taguchi method and its successful implementation in various industries.

Bharti, P. K.; Khan, M. I.; Singh, Harbinder

2010-10-01

367

Influence Of Tool Geometry, Tool Coating And Process Parameters In Thixoextrusion Of Steel  

SciTech Connect

Thixoextrusion could become one possibility to enlarge the complexity of extruded profiles made of steel. Accordingly semi-solid extrusion experiments of X210CrW12 tool steel using round dies of approximately 15 mm diameter were performed in order to achieve first information concerning possible process windows and process limits. For liquid fractions between 38% and 10%, extrusion press velocities from 10 mm/s to 50 mm/s and dies with novel PVD-coatings no complete solidification during extrusion was achieved. However the collected pieces of the extruded bars showed a fine and evenly distributed globular microstructure.

Knauf, Frederik; Hirt, Gerhard [Institute of Metal Forming, RWTH Aachen University, Aachen (Germany); Immich, Philipp; Bobzin, Kirsten [Surface Engineering Institute, RWTH Aachen University, Aachen (Germany)

2007-04-07

368

Testing of New Materials and Computer Aided Optimization of Process Parameters and Clamping Device During Predevelopment of Laser Welding Processes  

NASA Astrophysics Data System (ADS)

The necessity for weight reduction in motor vehicles in order to save fuel consumption pushes automotive suppliers to use materials of higher strength. Due to their excellent crash behavior high strength steels are increasingly applied in various structures. In this paper some predevelopment steps for a material change from a micro alloyed to dual phase and complex phase steels of a T-joint assembly are displayed. Initially the general weldability of the materials regarding pore formation, hardening in the heat affected zone and hot cracking susceptibility is discussed. After this basic investigation, the computer aided design optimization of a clamping device is shown, in which influences of the clamping jaw, the welding position and the clamping forces upon weld quality are presented. Finally experimental results of the welding process are displayed, which validate the numerical simulation.

Weidinger, Peter; Günther, Kay; Fitzel, Martin; Logvinov, Ruslan; Ilin, Alexander; Ploshikhin, Vasily; Hugger, Florian; Mann, Vincent; Roth, Stephan; Schmidt, Michael

369

Experimental investigation of the influence of the FSW plunge processing parameters on the maximum generated force and torque  

Microsoft Academic Search

The paper presents the results of an experimental investigation, done on the friction stir welding (FSW) plunging stage. Previous\\u000a research works showed that the axial force and torque generated during this stage were characteristic for a static qualification\\u000a of a FSW machine. Therefore, the investigation objectives are to better understand the relation between the processing parameters\\u000a and the forces and

Sandra Zimmer; Laurent Langlois; Julien Laye; Régis Bigot

2010-01-01

370

Optimization of pulsed GTA welding process parameters for the welding of AISI 304L stainless steel sheets  

Microsoft Academic Search

Optimization of pulsed gas tungsten arc welding (pulsed GTAW) process parameters was carried out to obtain optimum weld bead\\u000a geometry with full penetration in welding of stainless steel (304L) sheets of 3 mm thickness. Autogenuous welding with square\\u000a butt joint was employed. Design of experiments based on central composite rotatable design was employed for the development\\u000a of a mathematical model correlating

P. K. Giridharan; N. Murugan

2009-01-01

371

Effect of process parameters on the mechanical properties of carbon nitride thin films synthesized by plasma assisted pulsed laser deposition  

Microsoft Academic Search

We present an investigation of the effect of the process parameters, namely deposition pressure and laser intensity, on the growth and mechanical properties of carbon nitride (CN x) thin films synthesized by plasma assisted pulsed laser deposition. Deposition at high remote plasma pressure (200 mTorr) enhances both growth rate and nitrogen incorporation (up to 40 at.?%), but nano-indentation measurements indicate that these

M. Tabbal; P. Mérel; M. Chaker

2004-01-01

372

Modeling and Analysis of Process Parameters for Evaluating Shrinkage Problems During Plastic Injection Molding of a DVD-ROM Cover  

NASA Astrophysics Data System (ADS)

Plastic injection molding plays a key role in the production of high-quality plastic parts. Shrinkage is one of the most significant problems of a plastic part in terms of quality in the plastic injection molding. This article focuses on the study of the modeling and analysis of the effects of process parameters on the shrinkage by evaluating the quality of the plastic part of a DVD-ROM cover made with Acrylonitrile Butadiene Styrene (ABS) polymer material. An effective regression model was developed to determine the mathematical relationship between the process parameters (mold temperature, melt temperature, injection pressure, injection time, and cooling time) and the volumetric shrinkage by utilizing the analysis data. Finite element (FE) analyses designed by Taguchi (L27) orthogonal arrays were run in the Moldflow simulation program. Analysis of variance (ANOVA) was then performed to check the adequacy of the regression model and to determine the effect of the process parameters on the shrinkage. Experiments were conducted to control the accuracy of the regression model with the FE analyses obtained from Moldflow. The results show that the regression model agrees very well with the FE analyses and the experiments. From this, it can be concluded that this study succeeded in modeling the shrinkage problem in our application.

Öktem, H.

2012-01-01

373

Investigation of processing parameters of spray freezing into liquid to prepare polyethylene glycol polymeric particles for drug delivery.  

PubMed

The objective of this study was to investigate the influence of processing parameters on the morphology, porosity, and crystallinity of polymeric polyethylene glycol (PEG) microparticles by spray freezing into liquid (SFL), a new particle engineering technology. Processing parameters investigated were the viscosity and flow rate of the polymer solution, nozzle diameter, spray time, pressure, temperature, and flow rate of the cryogenic liquid. By varying the processing parameters and feed composition, atomization and heat transfer mechanisms were modified resulting in particles of different size distribution, shape, morphology, density, porosity, and crystallinity. Median particle diameter (M50) varied from 25 microm to 600 microm. Particle shape was spherical or elongated with highly irregular surfaces. Granule density was between 0.5 and 1.5 g/mL. In addition to producing particles of pure polymer, drug particles were encapsulated in polymeric microparticles. The encapsulation efficiency of albuterol sulfate was 96.0% with a drug loading of 2.4%, indicating that SFL is useful for producing polymeric microparticles for drug delivery applications. It was determined that the physicochemical characteristics of model polymeric microparticles composed of PEG could be modified for use as a drug delivery carrier. PMID:12916894

Barron, Melisa K; Young, Timothy J; Johnston, Keith P; Williams, Robert O

2003-01-01

374

Relationships Between LRI Process Parameters and Impact and Post-Impact Behaviour of Stitched and Unstitched NCF Laminates  

NASA Astrophysics Data System (ADS)

The general context of the development of out-of-autoclave processes in the aeronautics industry raises the question of the possible links between these new processes and impact behaviour. In this study, a Taguchi table was used in a design of experiment approach to establish possible links. The study focused on the liquid resin infusion process applied to laminates made with stitched or unstitched quadri-axial carbon Non-Crimp Fabric (NCF). On the basis of previous studies and an analysis of the literature, five process parameters were selected (stitching, curing temperature, preform position, number of highly porous media, vacuum level). The impact energy was set at 35 J in order to obtain enough residual dent depth. The parameters analysed during and after impact were: maximum displacement of the impactor, energy absorbed, permanent indentation depth, and delaminated surface. Then, compression after impact tests were performed and the corresponding average stress was measured. The interactions found by statistical analysis show a very high sensitivity to stitching, which was, of course, expected. A very significant influence of curing temperature and a significant influence of preform position were also found on the permanent indentation depth and a physical explanation is provided. Globally, it was demonstrated that the resin infusion process itself did not influence the impact behaviour.

Njionhou, Alvine; Berthet, Florentin; Castanié, Bruno; Bouvet, Christophe

2012-12-01

375

Developing LBM Process Parameters for Ti-6Al-4V Thin Wall Structures and Determining the Corresponding Mechanical Characteristics  

NASA Astrophysics Data System (ADS)

The Laser Beam Melting (LBM) process technology within the family of Additive Manufacturing technology is characterized by its ability to fabricate fully dense 3D structures directly from micro-sized metal powder. With the current state of the art, Ti-6Al-4V has been processed using LBM machine systems constituting a laser with a beam diameter of about 100 ?m. In order to fabricate structures with smaller wall thicknesses, processing of Ti-6Al-4V is attempted on the LBM machine system, Realizer SLM 50 consisting of a laser with a beam diameter 10 ?m. The proposed paper presents the development of process parameters for fabricating fully dense Ti-6Al-4V 3D structures using the LBM machine system, Realizer SLM 50. Further experiments are carried out to determine the wall thickness and mechanical properties achievable using the selected process parameters. Analysis and scientific arguments are presented to explain the influence of building direction and heat treatment on mechanical properties.

Ahuja, Bhrigu; Schaub, Adam; Karg, Michael; Lechner, Michael; Merklein, Marion; Schmidt, Michael

376

Novel Algorithm for Sample Material Parameter Determination using THz Time-Domain Spectrometer Signal Processing  

NASA Astrophysics Data System (ADS)

In our research we have developed a novel sample material parameter determination algorithm which could be used for characterization of very thin flats. Utilizing this algorithm one could find optical properties of the media which are thin enough to cause appearance of the satellite pulses in TDS system signal, transmitted through the flat sample. The algorithm is based on the minimization of the Error function (minimization between the theoretical model of sample transfer function and the experimental data collected with THz pulsed spectrometer). The algorithm was implemented experimentally and tested by means of the test samples characterization. The results of the algorithm implementation were compared with the results of the same test sample studying using terahertz backward-wave oscillator spectroscopy.

Zaytsev, Kirill I.; Gavdush, Arseniy A.; Lebedev, Sergey P.; Yurchenko, Stanislav O.

2014-03-01

377

Primary water stress corrosion cracking of Alloy 600: Effects of processing parameters  

Microsoft Academic Search

Correlations of stress corrosion cracking (SCC) data in deaerated water with temperature, stress, metallography, and processing for laboratory test specimens are presented. Initiation time data show that a low temperature anneal and resulting absence of grain boundary carbides result in a material having increased susceptibility to SCC. Data also show that hot worked and annealed Alloy 600 is more resistant

D. J. Seman; G. L. Webb; R. J. Parrington

1993-01-01

378

Modelling effects of processing parameters on granule porosity in high-shear granulation  

Microsoft Academic Search

When trying to meet final product specifications for porosity of granules made using high-shear granulation there are many choices for the formulation recipe and processing conditions. This paper presents the concept of a Critical Packing State of the primary particles forming a granule and the associated Limiting Binder Ratio, which allows granule consolidation to be modelled. The effect on consolidation

Robert Maxim; Jin Sheng Fu; Matthew Pickles; Agba Salman; Mike Hounslow

2004-01-01

379

Effects of process parameters on warm and electromagnetic hybrid forming of magnesium alloy sheets  

Microsoft Academic Search

As the lightest structural metal, magnesium (Mg) is attracting increasing interest from both the industrial and academic fields. Magnesium alloy parts are mainly processed by die casting due to their poor sheet formability at room temperature. Warm forming is a popular method of forming; Mg alloy sheets produced in this manner show excellent formability around 200–400°C. Electromagnetic forming (EMF) can

Zhenghua Meng; Shangyu Huang; Jianhua Hu; Wei Huang; Zhilin Xia

2011-01-01

380

A parametric study of the effects of process parameters on the assembly of chip scale packages  

Microsoft Academic Search

Chip scale packaging (CSP) technology is developing in response to some of the limitations of flip chip technology. It addresses the concerns and perceived risk associated with handling and assembling bare die while maintaining most of the volumetric packaging and performance merits that flip chip technology offers. The assembly of chip scale packages is not a one step process, but

T. A. Nguty; B. Salam; N. N. Ekere

2000-01-01

381

Can standard surface EMG processing parameters be used to estimate motor unit global firing rate?  

Microsoft Academic Search

The relations between motor unit global firing rates and established quantitative measures for processing the surface electromyogram (EMG) signals were explored using a simulation approach. Surface EMG signals were simulated using the reported properties of the first dorsal interosseous muscle in man, and the models were varied systematically, using several hypothetical relations between motor unit electrical and force output, and

Ping Zhou; William Zev Rymer

2004-01-01

382

Improved Hydrogeophysical Parameter Estimation from Empirical Mode Decomposition Processed Ground Penetrating Radar Data  

E-print Network

Penetrating Radar Data Adrian D. Addison, Bradley M. Battista and Camelia C. Knapp Department of Geological penetrating radar (GPR) as an exploration tool. Improvements in signal processing are expected to further for quantitative analyses. Introduction In the field of hydrogeophysics, ground penetrat- ing radar (GPR) is just

Knapp, Camelia Cristina

383

Effect of Process Parameters on Die Wear Behavior of Aluminum Alloy Rod Extrusion  

Microsoft Academic Search

In this paper, a subroutine that calculates die wear depth based on modified Archard's wear model was developed and then embedded into DEFORM-3D, with which the extrusion process of an aluminum alloy 7075 rod was simulated. Useful information was obtained from the numerical simulation, including interface pressure, the distribution of instantaneous temperature, the required extrusion force and the die wear

Tingting Li; Guoqun Zhao; Cunsheng Zhang; Yanjin Guan; Xuemei Sun; Hengkui Li

2012-01-01

384

Influence of Process Parameters on Microstructure and Mechanical Properties of Friction-Stir-Processed Mg-Gd-Y-Zr Casting  

NASA Astrophysics Data System (ADS)

Mg-10Gd-3Y-0.5Zr (wt pct) casting was subjected to friction stir processing (FSP) at a constant rotation rate of 800 rpm and varied travel speeds of 25, 50, and 100 mm/minute. FSP resulted in the generation of fine-grained microstructure and fundamental dissolution of coarse Mg5(Gd,Y) phase at the grain boundaries, thereby enhancing the tensile properties significantly at both room and elevated temperatures. The grain size of the FSP samples decreased with the increasing travel speed, whereas the microstructure heterogeneity with the banded structure (onion rings) became evident at a higher travel speed. Tensile elongation of the FSP samples increased as the travel speed increased, whereas the highest strengths were obtained at the medium travel speed of 50 mm/minute. Higher strengths and greater elongations were observed for the FSP samples in the transverse direction (TD) than in the longitudinal direction (LD). After post-FSP aging, the strengths of the FSP samples were increased significantly with the TD and LD exhibiting the same strengths; however, the elongation was decreased remarkably with the TD having higher elongation than the LD. A variation of the tensile properties was discussed in detail based on the microstructure heterogeneity and fracture surfaces.

Yang, Q.; Xiao, B. L.; Ma, Z. Y.

2012-06-01

385

Stevia rebaudiana Bertoni as a natural antioxidant/antimicrobial for high pressure processed fruit extract: processing parameter optimization.  

PubMed

Response surface methodology was used to evaluate the optimal high pressure processing treatment (300-500 MPa, 5-15 min) combined with Stevia rebaudiana (Stevia) addition (0-2.5% (w/v)) to guarantee food safety while maintaining maximum retention of nutritional properties. A fruit extract matrix was selected and Listeria monocytogenes inactivation was followed from the food safety point of view while polyphenoloxidase (PPO) and peroxidase (POD) activities, total phenolic content (TPC) and antioxidant capacity (TEAC and ORAC) were studied from the food quality point of view. A combination of treatments achieved higher levels of inactivation of L. monocytogenes and of the oxidative enzymes, succeeding in completely inactivating POD and also increasing the levels of TPC, TEAC and ORAC. A treatment of 453 MPa for 5 min with a 2.5% (w/v) of Stevia succeeded in inactivating over 5 log cycles of L. monocytogenes and maximizing inactivation of PPO and POD, with the greatest retention of bioactive components. PMID:24262555

Barba, Francisco José; Criado, María Nieves; Belda-Galbis, Clara Miracle; Esteve, María José; Rodrigo, Dolores

2014-04-01

386

Development of forging and heat treating practices for AMS 5737 for use at liquid helium temperatures  

SciTech Connect

To achieve a combination of high yield-strength (sigma y), plane-strain fracture-toughness (K/sub IC/) and resistance to galling when turned against austenitic stainless steels in highly-loaded threaded turnbuckles in the M.F.T.F.-B (Mirror Fusion Test Facility), AMS 5737 (Fe-15Cr-25Ni-1Mo-V-Ti-Al-B), a heat-treatable Fe-base superalloy that is slightly-ferromagnetic under high magnetic fields at 4K, was chosen for large (approx. 340 kg) forged turn buckles. This report describes the forging and heat-treatment optimization program that resulted in good sigma y and K/sub IC/ over the 4 to 300K range of service-temperatures and the verification tests run on a pre-production forging and actual production parts.

Dalder, E.N.C. (Lawrence Livermore National Lab., CA); Greenlee, M.

1981-08-10

387

17Oexcess in meteoric water: as a new isotopic parameter to decipher water cycle processes  

Microsoft Academic Search

Classical water stable isotopes (dD and d18O) have been used for more than 50 years with the aim to understand the links between water cycle and climate. They provide information on either temperature or precipitation changes depending on the latitudes. Their combination, in the so-called d-excess, brings some information on climatic conditions occurring during non equilibrium processes along air masses

A. Landais; M. Guillevic; H. Steen-Larsen; F. Vimeux; A. Bouygues; S. Falourd; C. M. Risi; S. Bony

2009-01-01

388

Effects of process parameters on the bead geometry of laser beam butt welded stainless steel sheets  

Microsoft Academic Search

Laser beam welding (LBW) is a field of growing importance in industry with respect to traditional welding methodologies due\\u000a to lower dimension and shape distortion of components and greater processing velocity. Because of its high weld strength to\\u000a weld size ratio, reliability and minimal heat affected zone, laser welding has become important for varied industrial applications.\\u000a With increased use of

K. Manonmani; N. Murugan; G. Buvanasekaran

2007-01-01

389

The influence of Aphanomyces cochlioides on selected physiological processes in sugar beet leaves and yield parameters  

Microsoft Academic Search

Alterations in some physiological processes in source leaves of sugar beet—such as chlorophyll and carbohydrate concentrations,\\u000a stomatal conductance, rate of net photosynthesis and transpiration, and activity of the photosynthetic apparatus during root\\u000a interaction with Aphanomyces cochlioides, were investigated. The influence of time of infection on plant health, yield quality and quantity was also examined. Plants\\u000a were infected at different times

Danuta Cho?uj; Ewa B. Moliszewska

390

Effective Parameters in Axial Injection Suspension Plasma Spray Process of Alumina-Zirconia Ceramics  

Microsoft Academic Search

Suspension plasma spray (SPS) is a novel process for producing nano-structured coatings with metastable phases using significantly\\u000a smaller particles as compared to conventional thermal spraying. Considering the complexity of the system there is an extensive\\u000a need to better understand the relationship between plasma spray conditions and resulting coating microstructure and defects.\\u000a In this study, an alumina\\/8 wt.% yttria-stabilized zirconia was deposited

F. Tarasi; M. Medraj; A. Dolatabadi; J. Oberste-Berghaus; C. Moreau

2008-01-01

391

Evolution of Brightest Cluster Galaxy Structural Parameters in the Last ~6 Gyr: Feedback Processes Versus Merger Events  

NASA Astrophysics Data System (ADS)

We present results on the evolution of the structural parameters of two samples of brightest cluster galaxies (BCGs) in the last 6 Gyr. The nearby sample of BCGs consists of 69 galaxies from the WINGS survey spanning a redshift range of 0.04 < z < 0.07. The intermediate-redshift (0.3 < z < 0.6) sample is formed by 20 BCGs extracted from the Hubble Space Telescope archive. Both samples have similar spatial resolution and their host clusters have similar X-ray luminosities. We report an increase in the size of the BCGs from intermediate to local redshift. However, we do not detect any variation in the Sérsic shape parameter in both samples. These results prove to be robust since the observed tendencies are model independent. We also obtain significant correlations between some of the BCG parameters and the main properties of the host clusters. More luminous, larger, and centrally located BCGs are located in more massive and dominant galaxy clusters. These facts indicate that the host galaxy cluster has played an important role in the formation of their BCGs. We discuss the possible mechanisms that can explain the observed evolution of the structural parameters of the BCGs. We conclude that the main mechanisms that can explain the increase in size and the non-evolution in the Sérsic shape parameter of the BCGs in the last 6 Gyr are feedback processes. This result disagrees with semi-analytical simulation results supporting the idea that merging processes are the main mechanism responsible for the evolution of the BCGs up until the present epoch.

Ascaso, B.; Aguerri, J. A. L.; Varela, J.; Cava, A.; Bettoni, D.; Moles, M.; D'Onofrio, M.

2011-01-01

392

Hyperspectral Data Processing and Mapping of Soil Parameters: Preliminary Data from Tuscany (Italy)  

NASA Astrophysics Data System (ADS)

Hyperspectral imaging has become a very powerful remote sensing tool for its capability of performing chemical and physical analysis of the observed areas. The objective of this study is to retrieve and characterize clay mineral content of the cultivated layer of soils, from both airborne hyperspectral and field spectrometry surveys in the 400-2500 nm spectral range. Correlation analysis is used to examine the possibility to predict the selected property using high-resolution reflectance spectra and images. The study area is located in the Mugello basin, about 30 km north of Firenze (Tuscany, Italy). Agriculturally suitable terrains are assigned mainly to annual crops, marginally to olive groves, vineyards and orchards. Soils mostly belong to Regosols and Cambisols orders. About 80 topsoil samples scattered all over the area were collected simultaneously with the flight of SIM.GA hyperspectral camera from Selex Galileo. The quantitative determination of clay minerals content in soil samples was performed by means of XRD and Rietveld refinement. An ASD FieldSpec spectroradiometer was used to obtain reflectance spectra from dried, crushed and sieved samples under controlled laboratory conditions. Different chemometric techniques (multiple linear regression, vertex component analysis, partial least squares regression and band depth analysis) were preliminarily tested to correlate mineralogical records with reflectance data. A one component partial least squares regression model yielded a preliminary R2 value of 0.65. A similar result was achieved by plotting the absorption peak depth at 2210 versus total clay mineral content (band-depth analysis). A complete hyperspectral geocoded reflectance dataset was collected using SIM.GA hyperspectral image sensor from Selex-Galileo, mounted on board of the University of Firenze ultra light aircraft. The approximate pixel resolution was 0.6 m (VNIR) and 1.2 m (SWIR). Airborne SIM.GA row data were firstly transformed into at-sensor radiance values, where calibration coefficients and parameters from laboratory measurements are applied to non-georeferred VNIR/SWIR DN values. Then, geocoded products are retrieved for each flight line by using a procedure developed in IDL Language and PARGE (PARametric Geocoding) software. When all compensation parameters are applied to hyperspectral data or to the final thematic map, orthorectified, georeferred and coregistered VNIR to SWIR images or maps are available for GIS application and 3D view. Airborne imagery has to be corrected for the influence of the atmosphere, solar illumination, sensor viewing geometry and terrain geometry information, for the retrieval of inherent surface reflectance properties. Then, different geophysical parameters can be investigated and retrieved by means of inversion algorithms. The experimental fitting of laboratory data on mineral content is used for airborne data inversion, whose results are in agreement with laboratory records, demonstrating the possibility to use this methodology for digital mapping of soil properties.

Garfagnoli, F.; Moretti, S.; Catani, F.; Innocenti, L.; Chiarantini, L.

2010-12-01

393

Liquefaction of lignocellulosic biomass: solvent, process parameter, and recycle oil screening.  

PubMed

The liquefaction of lignocellulosic biomass is studied for the production of liquid (transportation) fuels. The process concept uses a product recycle as a liquefaction medium and produces a bio-oil that can be co-processed in a conventional oil refinery. This all is done at medium temperature (? 300 °C) and pressure (? 60 bar). Solvent-screening experiments showed that oxygenated solvents are preferred as they allow high oil (up to 93% on carbon basis) and low solid yields (? 1-2% on carbon basis) and thereby outperform the liquefaction of biomass in compressed water and biomass pyrolysis. The following solvent ranking was obtained: guaiacol>hexanoic acid ? n-undecane. The use of wet biomass results in higher oil yields than dry biomass. However, it also results in a higher operating pressure, which would make the process more expensive. Refill experiments were also performed to evaluate the possibility to recycle the oil as the liquefaction medium. The recycled oil appeared to be very effective to liquefy the biomass and even surpassed the start-up solvent guaiacol, but became increasingly heavy and more viscous after each refill and eventually showed a molecular weight distribution that resembles that of refinery vacuum residue. PMID:24265195

van Rossum, Guus; Zhao, Wei; Castellvi Barnes, Maria; Lange, Jean-Paul; Kersten, Sascha R A

2014-01-01

394

Inheritance scheme for cascading lithography process control parameters technology, layer, and tool  

NASA Astrophysics Data System (ADS)

In today"s highly competitive markets, it is imperative for a manufacturing fab to perform with a high capability to adapt to the latest technologies, while being flexible to change part mix to meet dynamic market demands and at the same time achieve a high throughput to maximize productivity. The ability for a fab to adjust in this multi-part, mixed technology environment requires advanced control mechanisms to ensure that the correct control settings are used for each wafer processed. These circumstances are compelling fabs globally to gain the ability to introduce a multitude of parts with the correct control settings without having to relearn before processing. In this paper the concept of controller state is explored to address these issues by studying mechanisms to predict post-event settings. The concept of inheritance is explored to expand the controller state capability to predict optimized process settings across parts and tools. This paper explores the development and implementation of these mechanisms at Infineon Technologies, Richmond to reduce send-ahead (SAHD) and rework events. The benefits of controller state to handle tool events and part introductions are illustrated using events such as scheduled preventive maintenance, hardware upgrades, porting parts across tools and reintroduction of low runner parts back into production.

Gould, Christopher; Singhal, Abeer; Cui, Yuanting

2005-05-01

395

Photodissociation of singly charged oligonucleotide cations: Arrhenius parameters and identification of nonstatistical processes  

SciTech Connect

The lifetimes of singly charged protonated oligonucleotide cations, d(A){sub 2}, d(A){sub 3}, d(A){sub 4}, and d(A){sub 5}, were measured after UV photoabsorption in a storage ring. Two lifetime components were observed for d(A){sub 3}, d(A){sub 4}, and d(A){sub 5} but only one for d(A){sub 2}. Assuming that the major fragmentation channel is the same for all oligonucleotide cations, namely loss of a protonated adenine base, with similar Arrhenius parameters, then the lifetimes are a result of different final temperatures after photon absorption. Such an analysis provides an activation energy E{sub a} of 0.88 eV and preexponential factor A of 10{sup 10.2} s{sup -1}. Nonstatistical fragmentation was an important channel for all of the oligonucleotide cations, but most so for d(A){sub 2}, the one with the lowest number of neutral adenines.

Liu Bo [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); School of Physics and Information Optoelectronics, Henan University, Kaifeng (China); Hvelplund, Preben; Nielsen, Steen Broendsted [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Tomita, Shigeo [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-0006 (Japan)

2006-11-15

396

Influence of Processing Parameters on Induced Energy, Mechanical and Corrosion Properties of FSW Butt Joint of 7475 AA  

NASA Astrophysics Data System (ADS)

Friction stir welding (FSW), a promising solid state joining process invented at TWI in 1991, was used to join 9 mm thick 7475 aluminum alloy which is considered essentially unweldable by fusion processes. In the present work, the process parameters such as tool rotational speed were varied from 300 to 1000 rpm for a travel speed of 50 mm/min and the influence of process parameters in terms of energy input on microstructure, hardness, tensile strength, and the corrosion property of 7475 aluminum joints was evaluated and analyzed. The maximum tensile strength of FSW joints was obtained at rotational speed of 400 rpm and traverse speed of 50 mm/min (59.2 kJ) which attributed maximum stirred zone area and maximum hardness. The maximum corrosion resistance properties of weld in 3.5% NaCl solution, however, were obtained at rotational speed of 1000 rpm and traverse speed of 50 mm/min. Furthermore, for a given weld, stirred zone showed improved corrosion properties than TMAZ.

Gupta, Rajesh Kumar; Das, Hrishikesh; Pal, Tapan Kumar

2012-08-01

397

31 CFR 370.40 - Can I be held accountable if my negligence contributes to a forged signature?  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Can I be held accountable if my negligence contributes to a forged signature? 370.40 Section 370...Public Debt § 370.40 Can I be held accountable if my negligence contributes to a forged signature? (a)...

2010-07-01

398

Effect of Breadmaking Process on In Vitro Gut Microbiota Parameters in Irritable Bowel Syndrome  

PubMed Central

A variety of foods have been implicated in symptoms of patients with Irritable Bowel Syndrome (IBS) but wheat products are most frequently cited by patients as a trigger. Our aim was to investigate the effects of breads, which were fermented for different lengths of time, on the colonic microbiota using in vitro batch culture experiments. A set of in vitro anaerobic culture systems were run over a period of 24 h using faeces from 3 different IBS donors (Rome Criteria–mainly constipated) and 3 healthy donors. Changes in gut microbiota during a time course were identified by fluorescence in situ hybridisation (FISH), whilst the small -molecular weight metabolomic profile was determined by NMR analysis. Gas production was separately investigated in non pH-controlled, 36 h batch culture experiments. Numbers of bifidobacteria were higher in healthy subjects compared to IBS donors. In addition, the healthy donors showed a significant increase in bifidobacteria (P<0.005) after 8 h of fermentation of a bread produced using a sourdough process (type C) compared to breads produced with commercial yeasted dough (type B) and no time fermentation (Chorleywood Breadmaking process) (type A). A significant decrease of ?-Proteobacteria and most Gemmatimonadetes species was observed after 24 h fermentation of type C bread in both IBS and healthy donors. In general, IBS donors showed higher rates of gas production compared to healthy donors. Rates of gas production for type A and conventional long fermentation (type B) breads were almost identical in IBS and healthy donors. Sourdough bread produced significantly lower cumulative gas after 15 h fermentation as compared to type A and B breads in IBS donors but not in the healthy controls. In conclusion, breads fermented by the traditional long fermentation and sourdough are less likely to lead to IBS symptoms compared to bread made using the Chorleywood Breadmaking Process. PMID:25356771

Costabile, Adele; Santarelli, Sara; Claus, Sandrine P.; Sanderson, Jeremy; Hudspith, Barry N.; Brostoff, Jonathan; Ward, Jane L.; Lovegrove, Alison; Shewry, Peter R.; Jones, Hannah E.; Whitley, Andrew M.; Gibson, Glenn R.

2014-01-01

399

Processing and flammability parameters of bismaleimide and some other thermally stable resin matrices for composites  

NASA Technical Reports Server (NTRS)

The effect of processing variables on the flammability and mechanical properties of state-of-the-art and advanced resin matrices for graphite composites were studied. Resin matrices which were evaluated included state-of-the-art epoxy, phenolic-novolac, phenolic-Xylok, two types of bismaleimides, benzyl, polyethersulfone, and polyphenylsulfone. Comparable flammability and thermochemical data on graphite-reinforced laminates prepared with these resin matrices are presented, and the relationship of some of these properties to the anaerobic char yield of the resins is described.

Kourtides, D. A.

1984-01-01

400

Parameters of the response of the volumetric strain field to the external acting processes  

NASA Astrophysics Data System (ADS)

It is necessary to widen the registration amplitude range by controlling the influence factors on different time scales in order to analyze the properties of the dynamic system, forming the observed data of different-nature geophysical fields. The data on the volumetric strain variations, obtained in the scope of the PBO project (Parkfield, California), make it possible to construct the correct regression model for the external influence tidal and baric factors, as well as for the precipitation factor. The specific features of separation of the deformation components caused by the external sources, including the relation between the baric and tidal influences and the additional component reflecting the deformation process internal dynamics, are considered. The precipitation cumulative series has been considered in order to remove seasonal variations in the time range T ? 10 days. The estimated error of the amplitudes, determined based on the proposed component method, proved to be close to the initial data accuracy. An inhomogeneous complex structure of the geological environment in the zone adjacent to the San Andreas fault could be responsible for the difference in the character of the deformation processes and the response to the external influences at the considered observation points.

Cherepantsev, A. S.

2013-11-01

401

Property Measurement and Processing Parameter Optimization for Polylactide Micro Structure Fabrication by Thermal Imprint  

NASA Astrophysics Data System (ADS)

Polylactide (PLA) is a thermoplastic polymer derived from renewable resources. In this study, we measured the material properties and forming conditions of PLA under the thermal imprint process. The properties of PLA were investigated under various imprint temperatures and imprint times. The results show that increasing the imprint temperature and imprint time results in a progressive rise in Young's modulus and a decrease in elongation at break. Furthermore, if the imprint time exceeds 10 min, crystallinity at imprint temperatures 90 and 110 °C increases visibly. Measurements of rheology properties was performed and the results show viscoelastic behaviors which are combination of irreversible viscous flow and reversible elastic deformation at the temperature of 110-180 °C. The forming conditions of PLA micro structures under thermal imprint technology were studied based on the Taguchi method. The experimental results show that the transfer rate was enhanced to 96.3%. This study therefore contributes to research on the fabrication of biomedical devices using biodegradable polymers produced by the thermal imprint process.

Chang, Fuh-Yu; Teng, Ping-Tun; Tsai, Tsan-Hung

2013-06-01

402

Numerical methods for improving sensitivity analysis and parameter estimation of virus transport simulated using sorptive-reactive processes  

USGS Publications Warehouse

Using one- and two-dimensional homogeneous simulations, this paper addresses challenges associated with sensitivity analysis and parameter estimation for virus transport simulated using sorptive-reactive processes. Head, flow, and conservative- and virus-transport observations are considered. The paper examines the use of (1) observed-value weighting, (2) breakthrough-curve temporal moment observations, and (3) the significance of changes in the transport time-step size. The results suggest that (1) sensitivities using observed-value weighting are more susceptible to numerical solution variability, (2) temporal moments of the breakthrough curve are a more robust measure of sensitivity than individual conservative-transport observations, and (3) the transport-simulation time step size is more important than the inactivation rate in solution and about as important as at least two other parameters, reflecting the ease with which results can be influenced by numerical issues. The approach presented allows more accurate evaluation of the information provided by observations for estimation of parameters and generally improves the potential for reasonable parameter-estimation results. ?? 2004 Elsevier B.V. All rights reserved.

Barth, G.; Hill, M. C.

2005-01-01

403

Influence of process parameters on properties of reactively sputtered tungsten nitride thin films  

SciTech Connect

Tungsten nitride (WN{sub x}) thin films were produced by reactive dc magnetron sputtering of tungsten in an Ar-N{sub 2} gas mixture. The influence of the deposition power on the properties of tungsten nitride has been analyzed and compared with that induced by nitrogen content variation in the sputtering gas. A combined analysis of structural, electrical and optical properties on thin WN{sub x} films obtained at different deposition conditions has been performed. It was found that at an N{sub 2} content of 14% a single phase structure of W{sub 2}N films was formed with the highest crystalline content. This sputtering gas composition was subsequently used for fabricating films at different deposition powers. Optical analysis showed that increasing the deposition power created tungsten nitride films with a more metallic character, which is confirmed with resistivity measurements. At low sputtering powers the resulting films were crystalline whereas, with an increase of power, an amorphous phase was also present. The incorporation of an excess of nitrogen atoms resulted in an expansion of the W{sub 2}N lattice and this effect was more pronounced at low deposition powers. Infrared analysis revealed that in WN{sub x} films deposited at low power, chemisorbed N{sub 2} molecules did not behave as ligands whereas at high deposition power they clearly appeared as ligands around metallic tungsten. In this study, the influence of the most meaningful deposition parameters on the phase transformation reaction path was established and deposition conditions suitable for producing thermally stable and highly crystalline W{sub 2}N films were found.

Addonizio, Maria L.; Castaldo, Anna; Antonaia, Alessandro; Gambale, Emilia; Iemmo, Laura [ENEA, Portici Research Centre, Piazzale E. Fermi 1, I-80055, Portici (Italy)

2012-05-15

404

Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting  

NASA Astrophysics Data System (ADS)

Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Wu, Chun-Jing; Liu, Xue-Feng; Xie, Jian-Xin

2011-02-01

405

Continuous-wave fiber laser cutting of aluminum thin sheets: effect of process parameters and optimization  

NASA Astrophysics Data System (ADS)

One-millimeter-thick Al 1050 sheets were cut using a 2-kW fiber laser operating in continuous-wave (CW) mode. An experimental approach that consisted of fitting the regression models by means of response surface methodology was adopted. The effects of cutting speed, assist gas pressure, and focal position on roughness arithmetic mean value were investigated. The desirability function was applied for the simultaneous optimization of cut quality and operating costs. The full potential of the CW mode high processing speeds and of the better absorptivity of 1-?m laser radiation for highly reflective materials are employed at the same time. Cutting aluminum with fiber laser increases the cutting speed and gives a cut quality comparable with results obtained with CO2 and Nd:YAG lasers that represent the most established laser sources for this application.

Scintilla, Leonardo Daniele

2014-06-01

406

Taurine improves the wound healing process in cutaneous leishmaniasis in mice model, based on stereological parameters  

PubMed Central

Background: Cutaneous Leishmaniasis is a self-limiting disease caused by protozoan parasites of the genus Leishmania, which affects the skin with full-thickness wounds, which are prone to scar formation even after treatment. Taurine (Tu) is one of the most abundant amino acids that has antioxidant and anti-inflammatory effects, which play an important role in the process of wound healing. Herein, we have investigated the effects of Tu on cutaneous Leishmaniasis wounds and L. major promastigotes. Materials and Methods: Eighteen mice were induced with Leishmaniasis wounds (with L. Major) on the base of their tails and divided into three groups, T1: Treated with Tu injection, T2: Treated with Tu gel, and C: No treatment. Treatments were carried out every 24 hours for 21 days. The volume densities of the collagen bundles and vessels, vessel's length density and diameter, and fibroblast populations were estimated by stereological methods. Flow cytometry was used in order to investigate the direct Tu effect on parasites. The Mann-Whitney U test was used and P ? 0.05 was considered to be statistically significant. Results: The numerical density of the fibroblasts, volume density of the collagen bundles, and length densities of the vessels in groups T1 and T2 were significantly higher than in group C (P < 0.05). The fibroblast numerical density of group T1 was higher than that of group T2 (P = 0.02). Incidentally, Tu had no direct effect on L. major parasites according to the flow cytometry analysis. Conclusion: Tu showed the ability to improve the wound healing process and tissue regeneration although it had no direct anti-leishmaniasis effect. PMID:25337534

Ashkani-Esfahani, Soheil; Zarifi, Fariba; Asgari, Qasem; Samadnejad, Asal Zargari; Rafiee, Shima; Noorafshan, Ali

2014-01-01

407

Numerical Simulation of Damage during Forging with Superimposed Hydrostatic Pressure by Active Media  

SciTech Connect

The effective reduction of energy consumption and a reasonable treatment of resources can be achieved by minimizing a component's weight using lightweight metals. In this context, aluminum alloys play a major role. Due to their material-sided restricted formability, the mentioned aluminum materials are difficult to form. The plasticity of a material is ascertained by its maximum forming limit. It is attained, when the deformation causes mechanical damage within the material. Damage of that sort is reached more rapidly, the greater the tensile strength rate in relation to total tension rate. A promising approach of handling these low ductile, high-strength aluminum alloys within a forming process, is forming with a synchronized superposition of comprehensive stress by active media such as by controlling oil pressure. The influence of superimposed hydrostatic pressure on the flow stress was analyzed as well as the formability for different procedures at different hydrostatic pressures and temperature levels. It was observed that flow stress is independent of superimposed hydrostatic pressure. Neither the superimposed pressure has an influence on the plastic deformation, nor does a pressure dependent material hardening due to increasing hydrostatic pressure take place. The formability increases with rising hydrostatic pressure. The relative gain at room temperature and increase of the superimposed pressure from 0 to 600 bar for tested materials was at least 140 % and max. 220 %. Therefore in this paper, based on these experimental observations, it is the intended to develop a numerical simulation in order to predict ductile damage that occurs in the bulk forging process with superimposed hydrostatic pressure based Lemaitre's damage model.

Behrens, B.-A.; Hagen, T.; Roehr, S.; Sidhu, K. B. [Institute for Metal Forming and Metal-Forming Machines, Leibniz University of Hanover, An der Universitaet 2, 30823 Garbsen (Germany)

2007-05-17

408

Numerical Simulation of Damage during Forging with Superimposed Hydrostatic Pressure by Active Media  

NASA Astrophysics Data System (ADS)

The effective reduction of energy consumption and a reasonable treatment of resources can be achieved by minimizing a component's weight using lightweight metals. In this context, aluminum alloys play a major role. Due to their material-sided restricted formability, the mentioned aluminum materials are difficult to form. The plasticity of a material is ascertained by its maximum forming limit. It is attained, when the deformation causes mechanical damage within the material. Damage of that sort is reached more rapidly, the greater the tensile strength rate in relation to total tension rate. A promising approach of handling these low ductile, high-strength aluminum alloys within a forming process, is forming with a synchronized superposition of comprehensive stress by active media such as by controlling oil pressure. The influence of superimposed hydrostatic pressure on the flow stress was analyzed as well as the formability for different procedures at different hydrostatic pressures and temperature levels. It was observed that flow stress is independent of superimposed hydrostatic pressure. Neither the superimposed pressure has an influence on the plastic deformation, nor does a pressure dependent material hardening due to increasing hydrostatic pressure take place. The formability increases with rising hydrostatic pressure. The relative gain at room temperature and increase of the superimposed pressure from 0 to 600 bar for tested materials was at least 140 % and max. 220 %. Therefore in this paper, based on these experimental observations, it is the intended to develop a numerical simulation in order to predict ductile damage that occurs in the bulk forging process with superimposed hydrostatic pressure based Lemaitre's damage model.

Behrens, B.-A.; Hagen, T.; Röhr, S.; Sidhu, K. B.

2007-05-01

409

Floating basaltic lava balloons - constrains on the eruptive process based on morphologic parameters  

NASA Astrophysics Data System (ADS)

The 1998-2001 submarine Serreta eruption brought to science a new challenge. This eruption took place offshore of Terceira Island (Azores), on the so-called Serreta Submarine Ridge, corresponding to a basaltic fissure zone with alkaline volcanism, within a tectonic setting controlled by an hyper-slow spreading rift (the Terceira Rift). The inferred eruptive centers are alignment along a NE-SW direction over an area with depths ranging from 300 to more than 1000 meters. The most remarkable products of this eruption, were large basaltic balloons observed floating at the sea surface. Those balloons, designated as Lava Balloons, are spherical to ellipsoidal structures, ranging from 0.4 up to about 3 m in length, consisting of a thin lava shell enveloping a closed hollow interior, normally formed by a single large vesicle, or a few large convoluted vesicles, that grants an overall density below water density. The cross section of the lava shell usually ranges between 3 and 8 cm and has a distinct layered structure, with different layers defined by different vesicularity, bubble number density and crystal content. The outermost layer is characterized by very small vesicles and high bubble number density whereas the innermost layer has larger vesicles, lower bubble number density and higher crystal content. These observations indicate that the rapidly quenched outer layer preserved the original small vesicles present on the magma at the time of the balloon's formation while the inner layer continued to evolve, producing higher crystal content and allowing time for the expansion of vesicles inward and their efficient coalescence. The outer surface of the balloons exhibits patches of very smooth glassy surface and areas with striation and grooves resulting from small scale fluidal deformation. These surface textures are interpreted as the result of the extrusion process and were produced in a similar manner to the striation found on subaerial toothpaste lavas. Such characteristics are indicative that the outer surface of the balloon quenched as it was being extruded and preserved the scars of a squeeze-up process. On this outer surface, several superficial expansion cracks reveal that after its generation the balloon endured some expansion before reaching the sea surface, most likely due to hydrostatic decompression during its rise. The entire shell of the balloons shows bends and folds resulting from large ductile deformations, also suggesting an origin as an effusive process of squeezing-up a large vesicle through a fissure in a thin lava crust, similarly to the extrusion of a gas filled lava toe. Actually, the volume of the lava shell is not enough to produce all the gas in the balloons interior. More likely, at an earlier stage, degassing of magma as an open system allowed gas to segregate and accumulate to form large vesicles. The development of very large vesicles would be favored by a ponding system such as a lava lake.

Pacheco, J. M.; Zanon, V.; Kueppers, U.

2011-12-01

410

Optimization of processing parameters for As2Se 3 glass for low loss, high strength  

NASA Astrophysics Data System (ADS)

Chalcogenide glasses have been widely studied due to their extraordinary transparency in the infrared (IR) region from 0.5 to 20 ?m. This transparency combined with excellent thermo-mechanical properties, makes them ideal candidate for infrared optics including IR fiber optic applications. However, such non-oxide glasses generally exhibit low mechanical strength, as compared to their oxide counterpart, which are based on covalently bonded metal-oxygen species. In addition to mechanical robustness, low optical loss (hence low impurity content) is required for most IR optical materials, including the one in this study, amorphous arsenic tri-selenide, As2Se3. In this effort, As2Se3 glass was investigated and the impact of the glass purity on material physical properties quantified. Properties evaluated includes chemical composition, structure, thermal, optical and mechanical properties. There are many sources of optical loss in chalcogenide glasses, physical defects, heterogeneous phase(s), and oxide, hydroxide or hydride-containing species. These extrinsic impurities generally come from poor melting profiles, sample preparation or quality/purity of the raw materials. Reduction of intrinsic losses due of the material has also been explored. It was found that an impurity content of 0.1 ppb has to be reached to yield a total reduction of the band at 4.57 ?m. Various methods, such as thermal treatment of the raw material or the addition of impurity-getters in the melt followed by distillation were performed in our lab, to achieve different level of purity in the glass specimens. The role of glass purity on these attributes was compared. The relationship between impurity concentration and mechanical properties of arsenic selenide glass, both in bulk and fiber forms has been investigated. The concentration of oxide-containing impurities embedded in the glassy matrix appeared to have a strong impact on the microhardness of the resulting material. A reduction of ˜60% of the water, oxides and hydroxides content resulted in an increase of 200 MPa of the hardness of the glass system. Moreover, it has been demonstrated that the increase of the hydride (Se-H) content in the material would yield a lower microhardness of the glass. These observations have been correlated with the impact of the impurity concentration on the glass network connectivity. A material with weaker glass connectivity would exhibit smaller resistance to crack initiation. The evolution of the properties and homogeneity of the glass from small batch to preform and the effect of the drawing process have been studied. The results of the processing-related variables on final glass quality will be discussed.

Giroire, Baptiste

411

ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton GIT 2011  

E-print Network

· Forging ­ slug (bulk) is forging ­ flash (extrusion) is waste · Extrusion ­ extrusion (flash) is part ­ billet (bulk) is waste #12;ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2011 10. J.S. Colton © GIT 2011 16 p tfriction Upper bound analysis · Work input by external forces = plastic

Colton, Jonathan S.

412

Effect of Inlet and Outlet Flow Conditions on Natural Gas Parameters in Supersonic Separation Process  

PubMed Central

A supersonic separator has been introduced to remove water vapour from natural gas. The mechanisms of the upstream and downstream influences are not well understood for various flow conditions from the wellhead and the back pipelines. We used a computational model to investigate the effect of the inlet and outlet flow conditions on the supersonic separation process. We found that the shock wave was sensitive to the inlet or back pressure compared to the inlet temperature. The shock position shifted forward with a higher inlet or back pressure. It indicated that an increasing inlet pressure declined the pressure recovery capacity. Furthermore, the shock wave moved out of the diffuser when the ratio of the back pressure to the inlet one was greater than 0.75, in which the state of the low pressure and temperature was destroyed, resulting in the re-evaporation of the condensed liquids. Natural gas would be the subsonic flows in the whole supersonic separator, if the mass flow rate was less than the design value, and it could not reach the low pressure and temperature for the condensation and separation of the water vapor. These results suggested a guidance mechanism for natural gas supersonic separation in various flow conditions. PMID:25338207

Yang, Yan; Wen, Chuang; Wang, Shuli; Feng, Yuqing

2014-01-01

413

Processing, stability, and kinetic parameters of C5a peptidase from Streptococcus pyogenes.  

PubMed

A recombinant streptococcal C5a peptidase was expressed in Escherichia coli and its catalytic properties and thermal stability were subjected to examination. It was shown that the NH2-terminal region of C5a peptidase (Asn32-Asp79/Lys90) forms the pro-sequence segment. Upon maturation the propeptide is hydrolyzed either via an autocatalytic intramolecular cleavage or by exogenous protease streptopain. At pH 7.4 the enzyme exhibited maximum activity in the narrow range of temperatures between 40 and 43 degrees C. The process of heat denaturation of C5a peptidase investigated by fluorescence and circular dichroism spectroscopy revealed that the protein undergoes biphasic unfolding transition with Tm of 50 and 70 degrees C suggesting melting of different parts of the molecule with different stability. Unfolding of the less stable structures was accompanied by the loss of proteolytic activity. Using synthetic peptides corresponding to the COOH-terminus of human complement C5a we demonstrated that in vitro peptidase catalyzes hydrolysis of two His67-Lys68 and Ala58-Ser59 peptide bonds. The high catalytic efficiency obtained for the SQLRANISHKDMQLGR extended peptide compared to the poor hydrolysis of its derivative Ac-SQLRANISH-pNA that lacks residues at P2'-P7' positions, suggest the importance of C5a peptidase interactions with the P' side of the substrate. PMID:12354115

Anderson, Elizabeth T; Wetherell, Michael G; Winter, Laurie A; Olmsted, Stephen B; Cleary, Patrick P; Matsuka, Yury V

2002-10-01

414

Treatment of biodiesel wastewater by adsorption with commercial chitosan flakes: parameter optimization and process kinetics.  

PubMed

The possibility of using commercial chitosan flakes as an adsorbent for the removal of pollutants from biodiesel wastewater was evaluated. The effect of varying the adsorption time (0.5-5 h), initial wastewater pH (2-8), adsorbent dose (0.5-5.5 g/L) and mixing rate (120-350 rpm) on the efficiency of pollutant removal was explored by univariate analysis. Under the derived optimal conditions, greater than 59.3%, 87.9% and 66.2% of the biological oxygen demand (BOD), chemical oxygen demand (COD) and oil & grease, respectively, was removed by a single adsorption. Nevertheless, the remaining BOD, COD and oil & grease were still higher than the acceptable Thai government limits for discharge into the environment. When the treatment was repeated, a greater than 93.6%, 97.6% and 95.8% removal of the BOD, COD and oil & grease, respectively, was obtained. The reusability of commercial chitosan following NaOH washing (0.05-0.2 M) was not suitable, with less than 40% efficiency after just one recycling and declining rapidly thereafter. The adsorption kinetics of all pollutant types by the commercial chitosan flakes was controlled by a mixed process of diffusion and adsorption of the pollutants during the early treatment period (0-1.5 h) and then solely controlled by adsorption after 2 h. PMID:24412591

Pitakpoolsil, Wipawan; Hunsom, Mali

2014-01-15

415

Influences of process parameters and microstructure on the fracture mechanisms of ODS steels  

NASA Astrophysics Data System (ADS)

The present work investigates the impact response of three ODS steels containing 9%Cr and 14%Cr. These steels were produced by hot extrusion in the shapes of a rod and a plate. The 9%Cr ODS steel has a quasi-isotropic microstructure and is given as a reference material. In comparison, the 14%Cr ODS steel has a strong morphological and crystallographic texture given by the process route. The impact behaviour is anisotropic and the fracture energies are higher when the material is tested in the longitudinal direction compared to the transverse direction. Moreover, the 14%Cr ODS steel has a better impact behaviour when it is extruded in the shape of a rod rather than in the shape of a plate. This work focuses on the fracture mechanisms involved in the ductile to brittle transition regime and in the brittle regime of these materials. In the case of the 14%Cr ODS steel, the cleavage facets observed at very low temperature are much larger than the actual size of the grains. Packets of grains with less than 15° of internal misorientation were defined as effective grains for cleavage. In the transition range, the texture enhances intergranular delamination on the 14%Cr rod material. The occurrence of delamination consumes a lot of energy and tends to enhance scattering in impact energies.

Rouffié, A. L.; Wident, P.; Ziolek, L.; Delabrouille, F.; Tanguy, B.; Crépin, J.; Pineau, A.; Garat, V.; Fournier, B.

2013-02-01

416

Characterization of Cracking and Crack Growth Properties of the C5A Aircraft Tie-Box Forging  

NASA Technical Reports Server (NTRS)

Detailed destructive examinations were conducted to characterize the integrity and material properties of two aluminum alloy (7075-T6) horizontal stabilizer tie box forgings removed.from US. Air Force C5A and C5B transport aircraft. The C5B tie box forging was,found to contain no evidence of cracking. Thirteen cracks were found in the CSA,forging. All but one of the cracks observed in the C5A component were located along the top cap region (one crack was located in the bottom cap region). The cracks in the C5A component initiated at fastener holes and propagated along a highly tunneled intergranular crack path. The tunneled crack growth configuration is a likelv result of surface compressive stress produced during peening of the .forging suijace. The tie box forging ,fatigue crack growth, fracture and stress corrosion cracking (SCC) properties were characterized. Reported herein are the results of laboratory air ,fatigue crack growth tests and 95% relative humidity SCC tests conducted using specimens machined from the C5A ,forging. SCC test results revealed that the C5A ,forging material was susceptible to intergranular environmental assisted cracking: the C5A forging material exhibited a SCC crack-tip stress-intensity factor threshold of less than 6 MPadn. Fracture toughness tests revealed that the C5A forging material exhibited a fracture toughness that was 25% less than the C5B forging. The C5A forging exhibited rapid laboratory air fatigue crack growth rates having a threshold crack-tip stress-intensity factor range of less than 0.8 MPa sup m. Detailed fractographic examinations revealed that the ,fatigue crack intergranular growth crack path was similar to the cracking observed in the C5A tie box forging. Because both fatigue crack propagation and SCC exhibit similar intergranular crack path behavior, the damage mechanism resulting in multi-site cracking of tie box forgings cannot be determined unless local cyclic stresses can be quantified.

Piascik, Robert S.; Smith, Stephen W.; Newman, John A.; Willard, Scott A.

2003-01-01

417

Numerical modelling of cyclic plasticity and fatigue damage in cold-forging tools  

Microsoft Academic Search

Industrial cold-forging tools with complex geometry are very likely to be exposed to local plastic deformation near stress concentrating details. The accumulation of plastic deformation resulting from the cyclic loading conditions leads to fatigue damage and eventually to generation of a crack in the surface of the die. To study the effect of die prestressing on fatigue damage development, a

Thomas Ørts Pedersen

2000-01-01

418

A comparative evaluation of the theoretical failure criteria for workability in cold forging  

Microsoft Academic Search

This paper evaluates various theoretical failure criteria pertaining to workability in cold forging reported in the published literature for their reliability and sensitivity in predicting the occurrence of ductile fracture in metalworking. Finite element (FE) simulation of the published upsetting experiments on cylindrical test specimens was performed to determine the threshold values attained by various criteria at the fractured locations,

A Venugopal Rao; N Ramakrishnan; R Krishna kumar

2003-01-01

419

Multiaxial fatigue criterion accounting for anisotropy in forged components , Y. Chastel1  

E-print Network

Multiaxial fatigue criterion accounting for anisotropy in forged components M. Milesi1 , Y. Chastel-olivier.bouchard@ensmp.fr ABSTRACT: Numerical modelling of fatigue behavior for anisotropic structures has become critical for de elementary volume. It can then be used to improve and refine the Papadopoulos fatigue criterion by taking

Boyer, Edmond

420

A Life Study of Ausforged, Standard Forged and Standard Machined AISI M-50 Spur Gears  

NASA Technical Reports Server (NTRS)

Tests were conducted at 350 K (170 F) with three groups of 8.9 cm (3.5 in.) pitch diameter spur gears made of vacuum induction melted (VIM) consumable-electrode vacuum-arc melted (VAR), AISI M-50 steel and one group of vacuum-arc remelted (VAR) AISI 9310 steel. The pitting fatigue life of the standard forged and ausforged gears was approximately five times that of the VAR AISI 9310 gears and ten times that of the bending fatigue life of the standard machined VIM-VAR AISI M-50 gears run under identical conditions. There was a slight decrease in the 10-percent life of the ausforged gears from that for the standard forged gears, but the difference is not statistically significant. The standard machined gears failed primarily by gear tooth fracture while the forged and ausforged VIM-VAR AISI M-50 and the VAR AISI 9310 gears failed primarily by surface pitting fatigue. The ausforged gears had a slightly greater tendency to fail by tooth fracture than the standard forged gears.

Townsend, D. P.; Bamberger, E. N.; Zaretsky, E. V.

1975-01-01

421

POLYCRYSTALLINE MODELLING OF UDIMET 720 FORGING Julien Thbault 1,2  

E-print Network

POLYCRYSTALLINE MODELLING OF UDIMET 720 FORGING Julien Th�bault 1,2 , Denis Solas 2,3 ,Colette Rey is realised from a semi product of Udimet 720. Such technique is able to give us, a realistic description is deduced from the EBSD analysis. At high temperature, the Udimet 720 is constituted by a matrix

Paris-Sud XI, Université de

422

T & I--Metalworking, Forging. Kit No. 55. Instructor's Manual [and] Student Learning Activity Guide.  

ERIC Educational Resources Information Center

An instructor's manual and student activity guide on forging are provided in this set of prevocational education materials which focuses on the vocational area of trade and industry (metalworking). (This set of materials is one of ninety-two prevocational education sets arranged around a cluster of seven vocational offerings: agriculture, home…

Lake, Robert J.

423

The effect of nitrogen on the cold forging properties of 1020 steel  

Microsoft Academic Search

We have studied the effect of nitrogen on the cold forging properties of a low carbon steel as a function of temperature. Five AISI 1020 steels with nitrogen contents from 12 to 180ppm were examined by tensile testing from 25 to 371°C. Yield strength, tensile elongation (ductility), ultimate tensile strength (UTS), strain hardening exponents and strength coefficients were determined. The

T. J. Douthit; C. J. Van Tyne

2005-01-01

424

Social Work and Engineering Collaboration: Forging Innovative Global Community Development Education  

ERIC Educational Resources Information Center

Interdisciplinary programs in schools of social work are growing in scope and number. This article reports on collaboration between a school of social work and a school of engineering, which is forging a new area of interdisciplinary education. The program engages social work students working alongside engineering students in a team approach to…

Gilbert, Dorie J.

2014-01-01

425

Forging the Link between Multicultural Competence and Ethical Counseling Practice: A Historical Perspective  

ERIC Educational Resources Information Center

Recognition of multicultural competence as an essential component of ethical counseling practice is a growing trend. This article presents a historical perspective of salient events that have contributed to forging a link between multicultural competence and ethical behavior. Multicultural counseling is traced from its beginnings to its emergence…

Watson, Zarus E. P.; Herlihy, Barbara Richter; Pierce, Latoya Anderson

2006-01-01

426

Interior of shop, detail of 8,000 pound forging hammer (this ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior of shop, detail of 8,000 pound forging hammer (this hammer was probably manufactured the Chambersburg Engineering Company of Chambersburg, Pennsylvania), looking east - Bethlehem Steel Corporation, South Bethlehem Works, Tool Steel-Electric Furnace Shop, Along Lehigh River, North of Fourth Street, West of Minsi Trail Bridge, Bethlehem, Northampton County, PA

427

Interior of shop, detail of 8,000 pound forging hammer, looking ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Interior of shop, detail of 8,000 pound forging hammer, looking west - Bethlehem Steel Corporation, South Bethlehem Works, Tool Steel-Electric Furnace Shop, Along Lehigh River, North of Fourth Street, West of Minsi Trail Bridge, Bethlehem, Northampton County, PA

428

OREGON STATE UNIVERSITY (OSU) TRAINING RESEARCH ISOTOPE GENERAL ATOMICS (TRIGA) OVERPACK CLOSURE WELDING PROCESS PARAMETER DEVELOPMENT & QUALIFICATION  

SciTech Connect

Spent Nuclear Fuel (SNF) from the Oregon State University (OSU) TRIGA{reg_sign} Reactor is currently being stored in thirteen 55-gallon drums at the Hanford Site's low-level burial grounds. This fuel is soon to be retrieved from buried storage and packaged into new containers (overpacks) for interim storage at the Hanford Interim Storage Area (ISA). One of the key activities associated with this effort is final closure of the overpack by welding. The OSU fuel is placed into an overpack, a head inserted into the overpack top, and welded closed. Weld quality, for typical welded fabrication, is established through post-weld testing and nondestructive examination (NDE); however, in this case, once the SNF is placed into the overpack, routine testing and NDE are not feasible. An alternate approach is to develop and qualify the welding process/parameters, demonstrate beforehand that they produce the desired weld quality, and then verify parameter compliance during production welding. Fluor engineers have developed a Gas Tungsten Arc Welding (GTAW) technique and parameters, demonstrating that weld quality requirements for closure of packaged SNF overpacks are met, using this alternate approach. The following reviews the activities performed for this development and qualification effort.

CANNELL, G.R.

2006-09-11

429

Effect of growth parameters on dislocation generation in InP single crystal grown by the vertical gradient freeze process  

SciTech Connect

The generation and multiplication of dislocations in an indium phosphide (InP) single crystal grown by the vertical gradient freeze (VGF) process is predicted using a crystallographic model. This model couples microscopic dislocation motion and multiplication to macroscopic plastic deformation during the crystal growth process. During growth of an InP crystal, dislocations are generated in the plastically deformed crystal as a result of crystallographic glide caused by excessive thermal stresses. The temperature fields are determined by solving the partial differential equation of heat conduction in a VGF crystal growth system. The effects of growth direction and growth parameters (i.e., imposed temperature gradients, crystal radius and growth rate) on dislocation generation and multiplication in an InP crystal are investigated. Dislocation density patterns on the cross section of an InP crystal are numerically calculated and compared with experimental observations.

Gulluoglu, A.N. (Marmara Univ., Istanbul (Turkey). Dept. of Material Science and Engineering); Tsai, C.T. (Florida Atlantic Univ., Boca Raton, FL (United States). Dept. of Mechanical Engineering)

1999-06-22

430

Effects of Sol-Gel Processing Parameters and Substrates on Crystallization of Potassium Tantalate-Niobate Thin Films  

NASA Astrophysics Data System (ADS)

Potassium tantalate-niobate thin films were prepared from metal-organic compounds by sol-gel processing. Effects of substrates and processing parameters on K(Ta, Nb)O3 thin film growth were studied. The results showed that perovskite phase of K(Ta, Nb)O3 was formed through the reactions of pyrochlore phases, and K(Ta, Nb)O3 thin films with pure perovskite phase can be obtained. The formation mechanism of the perovskite phase of K(Ta, Nb)O3 on SrTiO3 and MgO single crystal substrates was discussed, and the causes that K(Ta, Nb)O3 thin films with pure perovskite structure on single crystal silicon and quartz glass substrates cannot be obtained was detailed.

Bao, Dinghua; Kuang, Anxiang; Gu, Haoshuang

1997-09-01

431

Breath-by-breath pulmonary O2 uptake kinetics: effect of data processing on confidence in estimating model parameters.  

PubMed

To improve the signal-to-noise ratio of breath-by-breath pulmonary O2 uptake (V?O2p) data, it is common practice to perform multiple step transitions, which are subsequently processed to yield an ensemble-averaged profile. The effect of different data-processing techniques on phase II V?O2p kinetic parameter estimates (V?O2p amplitude, time delay and phase II time constant (?V?O2p)] and model confidence [95% confidence interval (CI95)] was examined. Young (n = 9) and older men (n = 9) performed four step transitions from a 20 W baseline to a work rate corresponding to 90% of their estimated lactate threshold on a cycle ergometer. Breath-by-breath V?O2p was measured using mass spectrometry and volume turbine. Mono-exponential kinetic modelling of phase II V?O2p data was performed on data processed using the following techniques: (A) raw data (trials time aligned, breaths of all trials combined and sorted in time); (B) raw data plus interpolation (trials time aligned, combined, sorted and linearly interpolated to second by second); (C) raw data plus interpolation plus 5 s bin averaged; (D) individual trial interpolation plus ensemble averaged [trials time aligned, linearly interpolated to second by second (technique 1; points joined by straight-line segments), ensemble averaged]; (E) 'D' plus 5 s bin averaged; (F) individual trial interpolation plus ensemble averaged [trials time aligned, linearly interpolated to second by second (technique 2; points copied until subsequent point appears), ensemble averaged]; and (G) 'F' plus 5 s bin averaged. All of the model parameters were unaffected by data-processing technique; however, the CI95 for ?V?O2p in condition 'D' (4 s) was lower (P < 0.05) than the CI95 reported for all other conditions (5-10 s). Data-processing technique had no effect on parameter estimates of the phase II V?O2p response. However, the narrowest interval for CI95 occurred when individual trials were linearly interpolated and ensemble averaged. PMID:25063837

Keir, Daniel A; Murias, Juan M; Paterson, Donald H; Kowalchuk, John M

2014-11-01

432

3D Finite Element Analysis of the Effect of Process Parameters on Linear Friction Welding of Mild Steel  

NASA Astrophysics Data System (ADS)

In this work, a 3D numerical model was developed to investigate the complicated thermo-mechanically coupled process of linear friction welding (LFW). The explicit-implicit alternate method was adopted for the first time to simulate LFW mild steel based on the ABAQUS software. To cope with the excessive element distortion, remeshing was conducted at certain calculation time with the help of the HYPERWORKS software. Results show that the interface temperature is quickly increased to near 900 °C within 1 s. With increasing the welding time, the interface temperature reaches a quasi-steady state of about 950 °C and the axial shortening rate keeps almost constant. A final unilateral axial shortening of 2.73 mm was obtained under the experiment condition, which corresponds well to the experiment. Moreover, the effects of processing parameters (oscillation frequency, oscillation amplitude, and friction pressure) on the joint temperature evolution and axial shortening were systematically examined and discussed. These three parameters could be integrated into one factor, i.e., heat input to the interface.

Li, Wenya; Wang, Feifan; Shi, Shanxiang; Ma, Tiejun; Li, Jinglong; Vairis, Achilleas

2014-08-01

433

3D Finite Element Analysis of the Effect of Process Parameters on Linear Friction Welding of Mild Steel  

NASA Astrophysics Data System (ADS)

In this work, a 3D numerical model was developed to investigate the complicated thermo-mechanically coupled process of linear friction welding (LFW). The explicit-implicit alternate method was adopted for the first time to simulate LFW mild steel based on the ABAQUS software. To cope with the excessive element distortion, remeshing was conducted at certain calculation time with the help of the HYPERWORKS software. Results show that the interface temperature is quickly increased to near 900 °C within 1 s. With increasing the welding time, the interface temperature reaches a quasi-steady state of about 950 °C and the axial shortening rate keeps almost constant. A final unilateral axial shortening of 2.73 mm was obtained under the experiment condition, which corresponds well to the experiment. Moreover, the effects of processing parameters (oscillation frequency, oscillation amplitude, and friction pressure) on the joint temperature evolution and axial shortening were systematically examined and discussed. These three parameters could be integrated into one factor, i.e., heat input to the interface.

Li, Wenya; Wang, Feifan; Shi, Shanxiang; Ma, Tiejun; Li, Jinglong; Vairis, Achilleas

2014-11-01

434

Comparison of process parameter optimization using different designs in nanoemulsion-based formulation for transdermal delivery of fullerene  

PubMed Central

This research aims to formulate and to optimize a nanoemulsion-based formulation containing fullerene, an antioxidant, stabilized by a low amount of mixed surfactants using high shear and the ultrasonic emulsification method for transdermal delivery. Process parameters optimization of fullerene nanoemulsions was done by employing response surface methodology, which involved statistical multivariate analysis. Optimization of independent variables was investigated using experimental design based on Box–Behnken design and central composite rotatable design. An investigation on the effect of the homogenization rate (4,000–5,000 rpm), sonication amplitude (20%–60%), and sonication time (30–150 seconds) on the particle size, ?-potential, and viscosity of the colloidal systems was conducted. Under the optimum conditions, the central composite rotatable design model suggested the response variables for particle size, ?-potential, and viscosity of the fullerene nanoemulsion were 152.5 nm, ?52.6 mV, and 44.6 pascal seconds, respectively. In contrast, the Box–Behnken design model proposed that preparation under the optimum condition would produce nanoemulsion with particle size, ?-potential, and viscosity of 148.5 nm, ?55.2 mV, and 39.9 pascal seconds, respectively. The suggested process parameters to obtain optimum formulation by both models yielded actual response values similar to the predicted values with residual standard error of <2%. The optimum formulation showed more elastic and solid-like characteristics due to the existence of a large linear viscoelastic region. PMID:25258528

Ngan, Cheng Loong; Basri, Mahiran; Lye, Fui Fang; Fard Masoumi, Hamid Reza; Tripathy, Minaketan; Karjiban, Roghayeh Abedi; Abdul-Malek, Emilia

2014-01-01

435

Some matters concerned with selecting steam parameters and process-circuit solutions to optimize the parameters of steam turbine equipment and engineering design developments  

NASA Astrophysics Data System (ADS)

The possibility and advantages of increasing steam pressure in the steam-turbine low-pressure loop for combined-cycle power plants are considered. The question about the advisability of developing and manufacturing steam turbines for being used in combined-cycle power units equipped with modern class F gas turbines for supercritical and ultrasupercritical steam parameters is raised.

Kultyshev, A. Yu.; Stepanov, M. Yu.; Polyaeva, E. N.

2014-12-01

436

Development of Alloy and Superalloy Large Shafts by Friction Welding Process  

NASA Astrophysics Data System (ADS)

The aim of this study is to examine the process parameters of superalloy and alloy steel inertia welding using FE simulation and to evaluate the mechanical properties of a welded joint. FE simulation was carried out to optimize the inertia welding process parameters. Disk of rotor shaft and head of exhaust valve spindle are made by the hot closed die forging. Dissimilar inertia welding for large exhaust valve spindle manufacturing composed of the Nimonic 80 A valve head of 540 mm diameter and the SNCrW valve stem of 115 mm diameter, and for large rotor shaft manufacturing composed of the 310 mm diameter disk and the 140 mm diameter shaft were carried out with optimal process parameter conditions obtained simulation result. Inertia friction welded joint part was joined by inertia friction welder, MTI model 400. Mechanical and metallurgical properties of welded joints were evaluated by using microstructure, tensile, hardness and fatigue tests.

Jeong, H. S.; Cho, J. R.; Choi, S. K.; Oh, J. S.; Kim, E. N.

2010-06-01

437

Influence of operational parameters on nitrogen removal efficiency and microbial communities in a full-scale activated sludge process.  

PubMed

To improve the efficiency of total nitrogen (TN) removal, solid retention time (SRT) and internal recycling ratio controls were selected as operating parameters in a full-scale activated sludge process treating high strength industrial wastewater. Increased biomass concentration via SRT control enhanced TN removal. Also, decreasing the internal recycling ratio restored the nitrification process, which had been inhibited by phenol shock loading. Therefore, physiological alteration of the bacterial populations by application of specific operational strategies may stabilize the activated sludge process. Additionally, two dominant ammonia oxidizing bacteria (AOB) populations, Nitrosomonas europaea and Nitrosomonas nitrosa, were observed in all samples with no change in the community composition of AOB. In a nitrification tank, it was observed that the Nitrobacter populations consistently exceeded those of the Nitrospira within the nitrite oxidizing bacteria (NOB) community. Through using quantitative real-time PCR (qPCR), nirS, the nitrite reducing functional gene, was observed to predominate in the activated sludge of an anoxic tank, whereas there was the least amount of the narG gene, the nitrate reducing functional gene. PMID:21924454

Kim, Young Mo; Cho, Hyun Uk; Lee, Dae Sung; Park, Donghee; Park, Jong Moon

2011-11-01

438

Statistical Parameters Effects on Photocatalytic Degradation of Rhodamine 6G Dye with Hexagonal Zinc Oxide Nanorods Synthesized via Solution Process  

NASA Astrophysics Data System (ADS)

Hexagonal-shaped zinc oxide nanorods (HNRs) were synthesized via a wet chemical solution process at low temperature in short refluxing time. The structural and morphological properties of the obtained products were characterized by x-ray diffraction pattern and field emission scanning electron microscopy. The photocatalytic degradation process significantly shows enhanced activity of ZnO-HNRs under UV-Vis light in presence of rhodamine 6G dye (RhB). The effective concentration of ZnO-HNRs shows degradation process of RhB dye and was investigated via standard analytical techniques, optimized and validated by statistical analytical parameters. The statistical constraints give necessary information for establishing analytical procedures to ensure the quality and purity of the results. The absorption spectra were recorded at maximum absorbance ? max 470 nm, 520 nm, and 550 nm for ZnO-HNRs, RhB and ZnO-HNRs-RhB, respectively. Satisfactory data were obtained from UV-Vis spectroscopy, providing more reliable values against many factual variable factors such as concentration, volume, pH, time and temperature, etc.

Wahab, Rizwan; Khan, Farheen

2014-11-01

439

Statistical Parameters Effects on Photocatalytic Degradation of Rhodamine 6G Dye with Hexagonal Zinc Oxide Nanorods Synthesized via Solution Process  

NASA Astrophysics Data System (ADS)

Hexagonal-shaped zinc oxide nanorods (HNRs) were synthesized via a wet chemical solution process at low temperature in short refluxing time. The structural and morphological properties of the obtained products were characterized by x-ray diffraction pattern and field emission scanning electron microscopy. The photocatalytic degradation process significantly shows enhanced activity of ZnO-HNRs under UV-Vis light in presence of rhodamine 6G dye (RhB). The effective concentration of ZnO-HNRs shows degradation process of RhB dye and was investigated via standard analytical techniques, optimized and validated by statistical analytical parameters. The statistical constraints give necessary information for establishing analytical procedures to ensure the quality and purity of the results. The absorption spectra were recorded at maximum absorbance ? max 470 nm, 520 nm, and 550 nm for ZnO-HNRs, RhB and ZnO-HNRs-RhB, respectively. Satisfactory data were obtained from UV-Vis spectroscopy, providing more reliable values against many factual variable factors such as concentration, volume, pH, time and temperature, etc.

Wahab, Rizwan; Khan, Farheen

2014-09-01