Shading aboveground L-joint and lap-joint tests : comparison of white pine and sugar maple test assemblies

Treesearch

Carol A. Clausen; Daniel L. Lindner

2011-01-01

Five-year performance ratings are presented for two types of untreated, uncoated wood joints (L and lap) in aboveground tests under shaded conditions. The effect of shading on moisture entrapment in pine and maple L and lap joints was evaluated in a moderate decay zone (Madison, Wisconsin). Variations were observed between wood species, visual ratings, joint type,...

Microstructure and Mechanical Properties of Friction Stir Welded Aluminum Alloy/Stainless Steel Lap Joints

NASA Astrophysics Data System (ADS)

Ogura, Tomo; Nishida, Taichi; Nishida, Hidehito; Yoshikawa, Syuhei; Yoshida, Takumi; Omichi, Noriko; Fujimoto, Mitsuo; Hirose, Akio

The mechanical properties and interfacial microstructure of an aluminum alloy/stainless steel dissimilar lap joint using friction stir welding (FSW) were characterized. In an FSWed A3003 aluminum alloy-SUS304 steel lap joint, the strength on the advancing side was larger than that at the retreating side. TEM observation indicated that a sound joint can be obtained from the stage of the formation of the amorphous layer owing to the mechanical alloying effects before the formation of intermetallic compounds. This lap joining technique was also successfully applied to A6061-T6 aluminum alloy-grooved SUS304 plates. The maximum tensile strength of the lap joint was approximately the same as that of the base alloy, however, the proof stress of the joint decreased with the dissolution of the β″ phase in the A6061 aluminium alloy, which is caused by the generation of heat during friction stir welding.

Screening Adhesively Bonded Single-Lap-Joint Testing Results Using Nonlinear Calculation Parameters

DTIC Science & Technology

2012-03-01

versus displacement response for single-lap-joints bonded with damage-tolerant adhe- sives, such the polyurea adhesive plotted in Figure 2, is much...displacement response for a single-lap-joint bonded with a polyurea adhesive. Complex x-y plots are commonly fitted using the Levenberg-Marquardt...expected decrease in maximum strength for the polyurea in compar- ison to the epoxy, which could have been obtained using a traditional analysis approach

Ultrasonic guided wave inspection of Inconel 625 brazed lap joints

NASA Astrophysics Data System (ADS)

Comot, Pierre; Bocher, Philippe; Belanger, Pierre

2016-04-01

The aerospace industry has been investigating the use of brazing for structural joints, as a mean of reducing cost and weight. There therefore is a need for a rapid, robust, and cost-effective non-destructive testing method for evaluating the structural integrity of the joints. The mechanical strength of brazed joints depends mainly on the amount of brittle phases in their microstructure. Ultrasonic guided waves offer the possibility of detecting brittle phases in joints using spatio-temporal measurements. Moreover, they offer the opportunity to inspect complex shape joints. This study focused on the development of a technique based on ultrasonic guided waves for the inspection of Inconel 625 lap joints brazed with BNi-2 filler metal. A finite element model of a lap joint was used to optimize the inspection parameters and assess the feasibility of detecting the amount of brittle phases in the joint. A finite element parametric study simulating the input signal shape, the center frequency, and the excitation direction was performed. The simulations showed that the ultrasonic guided wave energy transmitted through, and reflected from, the joints was proportional to the amount of brittle phases in the joint.

The Characteristics of Fatigue Damage in the Fuselage Riveted Lap Splice Joint

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1997-01-01

An extensive data base has been developed to form the physical basis for new analytical methodology to predict the onset of widespread fatigue damage in the fuselage lap splice joint. The results of detailed destructive examinations have been cataloged to describe the physical nature of MSD in the lap splice joint. ne catalog includes a detailed description, e.g., crack initiation, growth rates, size, location, and fracture morphology, of fatigue damage in the fuselage lap splice joint structure. Detailed examinations were conducted on a lap splice joint panel removed from a full scale fuselage test article after completing a 60,000 cycle pressure test. The panel contained a four bay region that exhibited visible outer skin cracks and regions of crack link-up along the upper rivet row. Destructive examinations revealed undetected fatigue damage in the outer skin, inner skin, and tear strap regions. Outer skin fatigue cracks were found to initiate by fretting damage along the faying surface. The cracks grew along the faying surface to a length equivalent to two to three skin thicknesses before penetrating the outboard surface of the outer skin. Analysis of fracture surface marker bands produced during full scale testing revealed that all upper rivet row fatigue cracks contained in a dim bay region grow at similar rates; this important result suggests that fracture mechanics based methods can be used to predict the growth of outer skin fatigue cracks in lap splice structure. Results are presented showing the affects of MSD and out-of-plane pressure loads on outer skin crack link-up.

Multivariate Analysis of High Through-Put Adhesively Bonded Single Lap Joints: Experimental and Workflow Protocols

DTIC Science & Technology

2016-06-01

unlimited. v List of Tables Table 1 Single-lap-joint experimental parameters ..............................................7 Table 2 Survey ...Joints: Experimental and Workflow Protocols by Robert E Jensen, Daniel C DeSchepper, and David P Flanagan Approved for...TR-7696 ● JUNE 2016 US Army Research Laboratory Multivariate Analysis of High Through-Put Adhesively Bonded Single Lap Joints: Experimental

The Growth of Multi-Site Fatigue Damage in Fuselage Lap Joints

NASA Technical Reports Server (NTRS)

Piascik, Robert S.; Willard, Scott A.

1999-01-01

Destructive examinations were performed to document the progression of multi-site damage (MSD) in three lap joint panels that were removed from a full scale fuselage test article that was tested to 60,000 full pressurization cycles. Similar fatigue crack growth characteristics were observed for small cracks (50 microns to 10 mm) emanating from counter bore rivets, straight shank rivets, and 100 deg counter sink rivets. Good correlation of the fatigue crack growth data base obtained in this study and FASTRAN Code predictions show that the growth of MSD in the fuselage lap joint structure can be predicted by fracture mechanics based methods.

Effect of Thread and Rotating Speed on Material Flow Behavior and Mechanical Properties of Friction Stir Lap Welding Joints

NASA Astrophysics Data System (ADS)

Ji, Shude; Li, Zhengwei; Zhou, Zhenlu; Wu, Baosheng

2017-10-01

This study focused on the effects of thread on hook and cold lap formation, lap shear property and impact toughness of alclad 2024-T4 friction stir lap welding (FSLW) joints. Except the traditional threaded pin tool (TR-tool), three new tools with different thread locations and orientations were designed. Results showed that thread significantly affected hook, cold lap morphologies and lap shear properties. The tool with tip-threaded pin (T-tool) fabricated joint with flat hook and cold lap, which resulted in shear fracture mode. The tools with bottom-threaded pin (B-tool) eliminated the hook. The tool with reverse-threaded pin (R-tool) widened the stir zone width. When using configuration A, the joints fabricated by the three new tools showed higher failure loads than the joint fabricated by the TR-tool. The joint using the T-tool owned the optimum impact toughness. This study demonstrated the significance of thread during FSLW and provided a reference to optimize tool geometry.

A Single-Lap Joint Adhesive Bonding Optimization Method Using Gradient and Genetic Algorithms

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III; Finckenor, Jeffrey L.

1999-01-01

A natural process for any engineer, scientist, educator, etc. is to seek the most efficient method for accomplishing a given task. In the case of structural design, an area that has a significant impact on the structural efficiency is joint design. Unless the structure is machined from a solid block of material, the individual components which compose the overall structure must be joined together. The method for joining a structure varies depending on the applied loads, material, assembly and disassembly requirements, service life, environment, etc. Using both metallic and fiber reinforced plastic materials limits the user to two methods or a combination of these methods for joining the components into one structure. The first is mechanical fastening and the second is adhesive bonding. Mechanical fastening is by far the most popular joining technique; however, in terms of structural efficiency, adhesive bonding provides a superior joint since the load is distributed uniformly across the joint. The purpose of this paper is to develop a method for optimizing single-lap joint adhesive bonded structures using both gradient and genetic algorithms and comparing the solution process for each method. The goal of the single-lap joint optimization is to find the most efficient structure that meets the imposed requirements while still remaining as lightweight, economical, and reliable as possible. For the single-lap joint, an optimum joint is determined by minimizing the weight of the overall joint based on constraints from adhesive strengths as well as empirically derived rules. The analytical solution of the sin-le-lap joint is determined using the classical Goland-Reissner technique for case 2 type adhesive joints. Joint weight minimization is achieved using a commercially available routine, Design Optimization Tool (DOT), for the gradient solution while an author developed method is used for the genetic algorithm solution. Results illustrate the critical design variables

Analytical and experimental investigation of fatigue in lap joints

NASA Astrophysics Data System (ADS)

Swenson, Daniel V.; Chih-Chien, Chia; Derber, Thomas G.

A finite element model is presented that can simulate crack growth in layered structures such as lap joints. The layers can be joined either by rivets or adhesives. The crack is represented discretely in the mesh, and automatic remeshing is performed as the crack grows. Because of the connections between the layers, load is transferred to the uncracked layer as the crack grows. This reduces the stress intensity and slows the crack growth rate. The model is used to analyze tests performed on a section of a wing spanwise lap joint. The crack was initiated at a rivet and grown under constant amplitude cyclic loads. Both experimentally observed crack growth rates and the analysis show the retardation that occurs as a result of load transfer between layers. A good correlation is obtained between predicted and observed crack growth rates for the fullly developed through-thickness crack.

A critical examination of stresses in an elastic single lap joint

NASA Technical Reports Server (NTRS)

Cooper, P. A.; Sawyer, J. W.

1979-01-01

The results of an approximate nonlinear finite-element analysis of a single lap joint are presented and compared with the results of a linear finite-element analysis, and the geometric nonlinear effects caused by the load-path eccentricity on the adhesive stress distributions are determined. The results from finite-element, Goland-Reissner, and photoelastic analyses show that for a single lap joint the effect of the geometric nonlinear behavior of the joint has a sizable effect on the stresses in the adhesive. The Goland-Reissner analysis is sufficiently accurate in the prediction of stresses along the midsurface of the adhesive bond to be used for qualitative evaluation of the influence of geometric or material parametric variations. Detailed stress distributions in both the adherend and adhesive obtained from the finite-element analysis are presented to provide a basis for comparison with other solution techniques.

Optimum design of bolted composite lap joints under mechanical and thermal loading

NASA Astrophysics Data System (ADS)

Kradinov, Vladimir Yurievich

A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.

Tensile Shear Properties of the Friction Stir Lap Welded Joints and Material Flow Mechanism Under Pulsatile Revolutions

NASA Astrophysics Data System (ADS)

Hu, Yanying; Liu, Huijie; Du, Shuaishuai

2018-06-01

The aim of the present article is to offer insight into the effects of pin profiles on interface defects, tensile shear properties, microstructures, and the material flow of friction stir lap welded joints. The results indicate that, compared to the lap joints welded by the single threaded plane pin, the three-plane threaded pin, and the triangle threaded pin, the lap joint obtained by the conventional conical threaded pin is characterized by the minimum interface defect. The alternate threads and planes on the pin provide periodical stress, leading to pulsatile material flow patterns. Under the effect of pulsatile revolutions, an asymmetrical flow field is formed around the tool. The threads on the pin force the surrounding material to flow downward. The planes cannot only promote the horizontal flow of the material by scraping, but also provide extra space for the material vertical flow. A heuristic model is established to describe the material flow mechanism during friction stir lap welding under the effect of pulsatile revolutions.

Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

NASA Astrophysics Data System (ADS)

Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

2016-10-01

In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

Initiation and growth of multiple-site damage in the riveted lap joint of a curved stiffened fuselage panel: An experimental and analytical study

NASA Astrophysics Data System (ADS)

Ahmed, Abubaker Ali

As part of the structural integrity research of the National Aging Aircraft Research Program, a comprehensive study on multiple-site damage (MSD) initiation and growth in a pristine lap-joint fuselage panel has been conducted. The curved stiffened fuselage panel was tested at the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration William J. Hughes Technical Center. A strain survey test was conducted to verify proper load application. The panel was then subjected to a fatigue test with constant-amplitude cyclic loading. The applied loading spectrum included underload marker cycles so that crack growth history could be reconstructed from post-test fractographic examinations. Crack formation and growth were monitored via nondestructive and high-magnification visual inspections. Strain gage measurements recorded during the strain survey tests indicated that the inner surface of the skin along the upper rivet row of the lap joint experienced high tensile stresses due to local bending. During the fatigue loading, cracks were detected by eddy-current inspections at multiple rivet holes along the upper rivet row. Through-thickness cracks were detected visually after about 80% of the fatigue life. Once MSD cracks from two adjacent rivet holes linked up, there was a quick deterioration in the structural integrity of the lap joint. The linkup resulted in a 2.87" (72.9-mm) lead fatigue crack that rapidly propagated across 12 rivet holes and crossed over into the next skin bay, at which stage the fatigue test was terminated. A post-fatigue residual strength test was then conducted by loading the panel quasi-statically up to final failure. The panel failed catastrophically when the crack extended instantaneously across three additional bays. Post-test fractographic examinations of the fracture surfaces in the lap joint of the fuselage panel were conducted to characterize subsurface crack initiation and

Detecting severity of delamination in a lap joint using S-parameters

NASA Astrophysics Data System (ADS)

Islam, M. M.; Huang, H.

2018-03-01

The scattering parameters (S-parameters) represent the frequency response of a two-port linear time-invariant network. Treating a lap joint structure instrumented with two piezoelectric wafer active transducers (PWaTs) as such a network, this paper investigates the application of the S-parameters for detecting the severity of delamination in the lap joint. The pulse-echo signal calculated from the reflection coefficients, namely the S 11 and S 22-parameters, can be divided into three signals, i.e. the excitation, resonant, and echo signals, based on their respective time spans. Analyzing the effects of the delamination on the resonant signal enables us to identify the resonance at which the resonant characteristics of the PWaTs are least sensitive to the delamination. Only at this resonance, we found that the reflection coefficients and the amplitude of the first arrival echo signal changed monotonously with the increase of the delamination length. This discovery is further validated by the time-domain pitch-catch signal calculated from the transmission coefficient (i.e. the S 21-parameter). In addition, comparing the pulse-echo signals obtained from both PWaTs enables us to determine the side of the lap joint that the delamination is located at. This work establishes the S-parameters as an effective tool to evaluate the effects of damage on the PWaT resonant characteristics, based on which the PWaT resonance can be selected judiciously for damage severity detection. Correlating the reflection and transmission coefficients also provide addition validations that increase the detection confidence.

Microstructure and mechanical properties of friction stir lap welded Mg/Al joint assisted by stationary shoulder

NASA Astrophysics Data System (ADS)

Ji, Shude; Li, Zhengwei

2017-11-01

Using magnesium alloy as upper sheet, 3 mm-thick AZ31 magnesium alloy and 6061 aluminum alloy were joined using friction stir lap welding assisted by stationary shoulder. The effects of tool rotating speed on cross-sections, microstructure and mechanical properties of Mg/Al lap joints were mainly discussed. Results showed that stationary shoulder contributed to joint formation, by which stir zones (SZ) were characterized by big onion rings after welding. Because of the big forging force exerted by stationary shoulder, the upper region of hook was well bonded. SZ showed much higher hardness because of intermetallic compounds (IMCs). The bonding conditions at the base material (BM)/SZ interface at advancing side and the hook region played important roles on joint lap shear properties. The X-ray diffraction pattern analysis revealed that the main IMCs were Al3Mg2 and Al12Mg17.

Nonlinear Analysis of Bonded Composite Single-LAP Joints

NASA Technical Reports Server (NTRS)

Oterkus, E.; Barut, A.; Madenci, E.; Smeltzer, S. S.; Ambur, D. R.

2004-01-01

This study presents a semi-analytical solution method to analyze the geometrically nonlinear response of bonded composite single-lap joints with tapered adherend edges under uniaxial tension. The solution method provides the transverse shear and normal stresses in the adhesive and in-plane stress resultants and bending moments in the adherends. The method utilizes the principle of virtual work in conjunction with von Karman s nonlinear plate theory to model the adherends and the shear lag model to represent the kinematics of the thin adhesive layer between the adherends. Furthermore, the method accounts for the bilinear elastic material behavior of the adhesive while maintaining a linear stress-strain relationship in the adherends. In order to account for the stiffness changes due to thickness variation of the adherends along the tapered edges, their in-plane and bending stiffness matrices are varied as a function of thickness along the tapered region. The combination of these complexities results in a system of nonlinear governing equilibrium equations. This approach represents a computationally efficient alternative to finite element method. Comparisons are made with corresponding results obtained from finite-element analysis. The results confirm the validity of the solution method. The numerical results present the effects of taper angle, adherend overlap length, and the bilinear adhesive material on the stress fields in the adherends, as well as the adhesive, of a single-lap joint

Early detection and progression of decay in L-joints and lap-joints in a moderate decay hazard zone

Treesearch

Carol A. Clausen; Terry L. Highley; Daniel L. Lindner

2006-01-01

Accelerated test methods are needed to evaluate the initiation and progression of decay in wood exposed aboveground. The relationship between test conditions and initiation of decay, however, is poorly understood. Southern pine and maple L-joints and lap-joints were exposed aboveground in a configuration that encouraged water entrapment at the Valley View Experimental...

Fatigue Damage Monitoring of a Composite Step Lap Joint Using Distributed Optical Fibre Sensors

PubMed Central

Wong, Leslie; Chowdhury, Nabil; Wang, John; Chiu, Wing Kong; Kodikara, Jayantha

2016-01-01

Over the past few decades, there has been a considerable interest in the use of distributed optical fibre sensors (DOFS) for structural health monitoring of composite structures. In aerospace-related work, health monitoring of the adhesive joints of composites has become more significant, as they can suffer from cracking and delamination, which can have a significant impact on the integrity of the joint. In this paper, a swept-wavelength interferometry (SWI) based DOFS technique is used to monitor the fatigue in a flush step lap joint composite structure. The presented results will show the potential application of distributed optical fibre sensor for damage detection, as well as monitoring the fatigue crack growth along the bondline of a step lap joint composite structure. The results confirmed that a distributed optical fibre sensor is able to enhance the detection of localised damage in a structure. PMID:28773496

A Comprehensive Structural Analysis Process for Failure Assessment in Aircraft Lap-Joint Mimics Using Multi-Modal Fusion of NDE Data (Preprint)

DTIC Science & Technology

2012-07-01

plates with dimensions of 254 mm (10") by 76.2 mm (3") with a nominal thickness of 1.6 mm (0.063’’). Two aluminum plates were stacked and riveted to...create a lap-joint mimic test panel. Thus, ten aluminum plates produced five test panels. Prior to stacking and riveting , the aluminum plates of the... riveted region of the panels. 5 Approved for public release; distribution unlimited. Figure 1

Behavior of single lap composite bolted joint under traction loading: Experimental investigation

NASA Astrophysics Data System (ADS)

Awadhani, L. V.; Bewoor, Anand

2018-04-01

Composite bolted joints are preferred connection in the composite structures to facilitate the dismantling for the replacements/ maintenance work. The joint behavior under tractive forces has been studied in order to understand the safety of the structure designed. The main objective of this paper is to investigate the behavior of single-lap joints in carbon fiber reinforced epoxy composites under traction loading conditions. The experiments were designed to identify the effect of bolt diameter, stacking sequence and loading rate on the properties of the joint. The experimental results show that the parameters influence the joint performance significantly.

A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints

NASA Technical Reports Server (NTRS)

Harris, Charles E.; Piascik, Robert S.; Newman, James C., Jr.

1999-01-01

An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.

A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints

NASA Technical Reports Server (NTRS)

Harris, C. E.; Piascik, R. S.; Newman, J. C., Jr.

2000-01-01

An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.

Real-time monitoring of laser welding of galvanized high strength steel in lap joint configuration

NASA Astrophysics Data System (ADS)

Kong, Fanrong; Ma, Junjie; Carlson, Blair; Kovacevic, Radovan

2012-10-01

Two different cases regarding the zinc coating at the lap joint faying surface are selected for studying the influence of zinc vapor on the keyhole dynamics of the weld pool and the final welding quality. One case has the zinc coating fully removed at the faying surface; while the other case retains the zinc coating on the faying surface. It is found that removal of the zinc coating at the faying surface produces a significantly better weld quality as exemplified by a lack of spatters whereas intense spatters are present when the zinc coating is present at the faying surface. Spectroscopy is used to detect the optical spectra emitted from a laser generated plasma plume during the laser welding of galvanized high strength DP980 steel in a lap-joint configuration. A correlation between the electron temperature and defects within the weld bead is identified by using the Boltzmann plot method. The laser weld pool keyhole dynamic behavior affected by a high-pressure zinc vapor generated at the faying surface of galvanized steel lap-joint is monitored in real-time by a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source.

Numerical solutions for heat flow in adhesive lap joints

NASA Technical Reports Server (NTRS)

Howell, P. A.; Winfree, William P.

1992-01-01

The present formulation for the modeling of heat transfer in thin, adhesively bonded lap joints precludes difficulties associated with large aspect ratio grids required by standard FEM formulations. This quasi-static formulation also reduces the problem dimensionality (by one), thereby minimizing computational requirements. The solutions obtained are found to be in good agreement with both analytical solutions and solutions from standard FEM programs. The approach is noted to yield a more accurate representation of heat-flux changes between layers due to a disbond.

Modeling the Influence of Stitching on Delamination Growth in Stitched Warp-Knit Composite Lap Joints

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and analytical study. The experimental study was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation of the debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The strain energy release rates at the debond front were calculated using a finite element-based technique. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches effectively reduced mode I to zero, but had less of an effect on modes II and III.

Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

NASA Astrophysics Data System (ADS)

Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

2016-05-01

Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

Defect features, texture and mechanical properties of friction stir welded lap joints of 2A97 Al-Li alloy thin sheets

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

Chen, Haiyan

1.4 mm 2A97 Al-Li alloy thin sheets were welded by friction stir lap welding using the stirring tools with different pin length at different rotational speeds. The influence of pin length and rotational speed on the defect features and mechanical properties of lap joints were investigated in detail. Microstructure observation shows that the hook defect geometry and size mainly varies with the pin length instead of the rotational speed. The size of hook defects on both the advancing side (AS) and the retreating side (RS) increased with increasing the pin length, leading to the effective sheet thickness decreased accordingly. Electronmore » backscatter diffraction analysis reveals that the weld zones, especially the nugget zone (NZ), have the much lower texture intensity than the base metal. Some new texture components are formed in the thermo-mechanical affected zone (TMAZ) and the NZ of joint. Lap shear test results show that the failure load of joints generally decreases with increasing the pin length and the rotational speed. The joints failed during the lap shear tests at three locations: the lap interface, the RS of the top sheet and the AS of the bottom sheet. The fracture locations are mainly determined by the hook defects. - Highlights: • Hook defect size mainly varies with the pin length of stirring tool. • The proportion of LAGBs and substructured grains increases from NZ to TMAZ. • Weld zones, especially the NZ, have the much lower texture intensity than the BM. • Lap shear failure load and fracture location of joints is relative to the hook defects.« less

Preload Monitoring of Bolted L-Shaped Lap Joints Using Virtual Time Reversal Method.

PubMed

Du, Fei; Xu, Chao; Wu, Guannan; Zhang, Jie

2018-06-13

L-shaped bolt lap joints are commonly used in aerospace and civil structures. However, bolt joints are frequently subjected to loosening, and this has a significant effect on the safety and reliability of these structures. Therefore, bolt preload monitoring is very important, especially at the early stage of loosening. In this paper, a virtual time reversal guided wave method is presented to monitor preload of bolted L-shaped lap joints accurately and simply. In this method, a referenced reemitting signal (RRS) is extracted from the bolted structure in fully tightened condition. Then the RRS is utilized as the excitation signal for the bolted structure in loosening states, and the normalized peak amplitude of refocused wave packet is used as the tightness index (TI A ). The proposed method is experimentally validated by L-shaped bolt joints with single and multiple bolts. Moreover, the selections of guided wave frequency and tightness index are also discussed. The results demonstrate that the relationship between TI A and bolt preload is linear. The detection sensitivity is improved significantly compared with time reversal (TR) method, particularly when bolt loosening is at its embryo stage. The results also show that TR method is an effective method for detection of the number of loosening bolts.

Analytical and experimental study of the vibration of bonded beams with a lap joint

NASA Technical Reports Server (NTRS)

Rao, M. D.; Crocker, M. J.

1990-01-01

A theoretical model to study the flexural vibration of a bonded lap joint system is described in this paper. First, equations of motion at the joint region are derived using a differential element approach. The transverse displacements of the upper and lower beam are considered to be different. The adhesive is assumed to be linearly viscoelastic and the widely used Kelvin-Voight model is used to represent the viscoelastic behavior of the adhesive. The shear force at the interface between the adhesive and the beam is obtained from the simple bending motion equations of the two beams. The resulting equations of motion are combined with the equations of transverse vibration of the beams in the unjointed regions. These are later solved as a boundary value problem to obtain the eigenvalues and eigenvectors of the system. The model can be used to predict the natural frequencies, modal damping ratios, and mode shapes of the system for free vibration. Good agreement between numerical and experimental results was obtained for a system of graphite epoxy beams lap-jointed by an epoxy adhesive.

Support and Development of Workflow Protocols for High Throughput Single-Lap-Joint Testing-Experimental

DTIC Science & Technology

2013-04-01

preparation, and presence of an overflow fillet for a high strength epoxy and ductile methacylate adhesive. A unique feature of this study was the...of expanding adhesive joint test configurations as part of the GEMS program. 15. SUBJECT TERMS single lap joint, adhesion, aluminum, epoxy ... epoxy and ductile methacylate adhesive. A unique feature of this study was the use of untrained GEMS (Gains in the Education of Mathematics and Sci

Fracture and Fatigue Strength Evaluation of Multiple Site Damaged Aircraft Fuselages - Curved Panel Testing and Analysis.

DOT National Transportation Integrated Search

1994-01-01

As the fleet of commercial passenger aircraft is utilized beyond their design lives, flaws have developed at the rivet holes of fuselage lap joints on some aircraft, which can grow and link up into cracks of significant length. Understanding, predict...

Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications Preparation and Testing of Single Lap Joints (Ver. 2.2, Unlimited)

DTIC Science & Technology

2016-04-01

Gerard Chaney, and Charles Pergantis Weapons and Materials Research Directorate, ARL Coatings, Corrosion, and Engineered Polymers Branch (CCEPB...SUBJECT TERMS single lap joint, adhesive, sample preparation, testing, database, metadata, material pedigree, ISO 16. SECURITY CLASSIFICATION OF: 17...temperature/water immersion conditioning test for lap-joint test specimens using the test tubes and convection oven method

Adhesive-bonded double-lap joints. [analytical solutions for static load carrying capacity

NASA Technical Reports Server (NTRS)

Hart-Smith, L. J.

1973-01-01

Explicit analytical solutions are derived for the static load carrying capacity of double-lap adhesive-bonded joints. The analyses extend the elastic solution Volkersen and cover adhesive plasticity, adherend stiffness imbalance and thermal mismatch between the adherends. Both elastic-plastic and bi-elastic adhesive representations lead to the explicit result that the influence of the adhesive on the maximum potential bond strength is defined uniquely by the strain energy in shear per unit area of bond. Failures induced by peel stresses at the ends of the joint are examined. This failure mode is particularly important for composite adherends. The explicit solutions are sufficiently simple to be used for design purposes

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Barclay, D. L.

1980-01-01

Results of an experimental program to develop several types of graphite/polyimide (GR/PI) bonded and bolted joints for lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Tasks accomplished include: a literature survey; design of static discriminator specimens; design allowables testing; fabrication of test panels and specimens; small specimen testing; and standard joint testing. Detail designs of static discriminator specimens for each of the four major attachment types are presented. Test results are given for the following: (1) transverse tension of Celion 3000/PMR-15 laminate; (2) net tension of a laminate for both a loaded and unloaded bolt hole; (3) comparative testing of bonded and co-cured doublers along with pull-off tests of single and double bonded angles; (4) single lap shear tests, transverse tension and coefficient of thermal expansion tests of A7F (LARC-13 amide-imide modified) adhesive; and (5) tension tests of standard single lap, double lap, and symmetric step lap bonded joints. Also, included are results of a finite element analysis of a single lap bonded composite joint.

Monitoring of fatigue damage in composite lap-joints using guided waves and FBG sensors

NASA Astrophysics Data System (ADS)

Karpenko, Oleksii; Khomenko, Anton; Koricho, Ermias; Haq, Mahmoodul; Udpa, Lalita

2016-02-01

Adhesive bonding is being increasingly employed in many applications as it offers possibility of light-weighting and efficient multi-material joining along with reduction in time and cost of manufacturing. However, failure initiation and progression in critical components like joints, specifically in fatigue loading is not well understood, which necessitates reliable NDE and SHM techniques to ensure structural integrity. In this work, concurrent guided wave (GW) and fiber Bragg grating (FBG) sensor measurements were used to monitor fatigue damage in adhesively bonded composite lap-joints. In the present set-up, one FBG sensor was strategically embedded in the adhesive bond-line of a lap-joint, while two other FBGs were bonded on the surface of the adherends. Full spectral responses of FBG sensors were collected and compared at specific intervals of fatigue loading. In parallel, guided waves were actuated and sensed using PZT wafers mounted on the composite adherends. Experimental results demonstrated that time-of-flight (ToF) of the fundamental modes transmitted through the bond-line and spectral response of FBG sensors were sensitive to fatigue loading and damage. Combination of guided wave and FBG measurements provided the desired redundancy and synergy in the data to evaluate the degradation in bond-line properties. Measurements taken in the presence of continuously applied load replicated the in-situ/service conditions. The approach shows promise in understanding the behavior of bonded joints subjected to complex loading.

Bolted Double-Lap Composite Joints Under Mechanical and Thermal Loading

NASA Technical Reports Server (NTRS)

Kradinov, V.; Barut, A.; Madenci, E.; Walker, Sandra P. (Technical Monitor)

2000-01-01

This study concerns the determination of the contact stresses and contact region around bolt holes and the bolt load distribution in single- and double-lap joints of composite laminates with arbitrarily located bolts under general mechanical loading conditions and uniform temperature change. The unknown contact stress distribution and contact region between the bolt and laminates and the interaction among the bolts require the bolt load distribution, as well as the contact stresses, to be as part of the solution. The present method is based on the complex potential theory and the variational formulation in order to account for bolt stiffness, bolt-hole clearance, and finite geometry of the composite laminates.

Effects of simulated lightning on composite and metallic joints

NASA Technical Reports Server (NTRS)

Howell, W. E.; Plumer, J. A.

1982-01-01

The effects of simulated lightning strikes and currents on aircraft bonded joints and access/inspection panels were investigated. Both metallic and composite specimens were tested. Tests on metal fuel feed through elbows in graphite/epoxy structures were evaluated. Sparking threshold and residual strength of single lap bonded joints and sparking threshold of access/inspection panels and metal fuel feed through elbows are reported.

Detection of fastener loosening in simple lap joint based on ultrasonic wavefield imaging

NASA Astrophysics Data System (ADS)

Gooda Sahib, M. I.; Leong, S. J.; Chia, C. C.; Mustapha, F.

2017-12-01

Joints in aero-mechanical structures are critical elements that ensure the structural integrity but they are prone to damages. Inspection of such joints that have no prior baseline data is really challenging but it can be possibly done using the Ultrasonic Propagation Imager (UPI). The feasibility of applying UPI for detection of loosened fastener is investigated in this study. A simple lap joint specimen made by connecting two pieces of 2.5mm thick SAE304 stainless steel plates using five M6 screws and nuts has been used in this study. All fasteners are tightened to 10Nm but one of them is completely loosened to simulate the damage. The wavefield data is processed into ultrasonic wavefield propagation video and a series of spectral amplitude images. The spectral images showed noticeable amplitude difference at the loosened fastener, hence confirmed the feasibility of using UPI for structural joints inspection. A simple contrast maximization method is also introduced to improve the result.

Corrosion Performance of Friction Stir Linear Lap Welded AM60B Joints

NASA Astrophysics Data System (ADS)

Kish, J. R.; Birbilis, N.; McNally, E. M.; Glover, C. F.; Zhang, X.; McDermid, J. R.; Williams, G.

2017-11-01

A corrosion investigation of friction stir linear lap welded AM60B joints used to fabricate an Mg alloy-intensive automotive front end sub-assembly was performed. The stir zone exhibited a slightly refined grain size and significant break-up and re-distribution of the divorced Mg17Al12 (β-phase) relative to the base material. Exposures in NaCl (aq) environments revealed that the stir zone was more susceptible to localized corrosion than the base material. Scanning vibrating electrode technique measurements revealed differential galvanic activity across the joint. Anodic activity was confined to the stir zone surface and involved initiation and lateral propagation of localized filaments. Cathodic activity was initially confined to the base material surface, but was rapidly modified to include the cathodically-activated corrosion products in the filament wake. Site-specific surface analyses revealed that the corrosion observed across the welded joint was likely linked to variations in Al distribution across the surface film/metal interface.

Three-Dimensional Geometric Nonlinear Contact Stress Analysis of Riveted Joints

NASA Technical Reports Server (NTRS)

Shivakumar, Kunigal N.; Ramanujapuram, Vivek

1998-01-01

The problems associated with fatigue were brought into the forefront of research by the explosive decompression and structural failure of the Aloha Airlines Flight 243 in 1988. The structural failure of this airplane has been attributed to debonding and multiple cracking along the longitudinal lap splice riveted joint in the fuselage. This crash created what may be termed as a minor "Structural Integrity Revolution" in the commercial transport industry. Major steps have been taken by the manufacturers, operators and authorities to improve the structural airworthiness of the aging fleet of airplanes. Notwithstanding, this considerable effort there are still outstanding issues and concerns related to the formulation of Widespread Fatigue Damage which is believed to have been a contributing factor in the probable cause of the Aloha accident. The lesson from this accident was that Multiple-Site Damage (MSD) in "aging" aircraft can lead to extensive aircraft damage. A strong candidate in which MSD is highly probable to occur is the riveted lap joint.

Fatigue damage assessment of high-usage in-service aircraft fuselage structure

NASA Astrophysics Data System (ADS)

Mosinyi, Bao Rasebolai

As the commercial and military aircraft fleets continue to age, there is a growing concern that multiple-site damage (MSD) can compromise structural integrity. Multiple site damage is the simultaneous occurrence of many small cracks at independent structural locations, and is the natural result of fatigue, corrosion, fretting and other possible damage mechanisms. These MSD cracks may linkup and form a fatigue lead crack of critical length. The presence of MSD also reduces the structure's ability to withstand longer cracks. The objective of the current study is to assess, both experimentally and analytically, MSD formation and growth in the lap joint of curved panels removed from a retired aircraft. A Boeing 727-232 airplane owned and operated by Delta Air Lines, and retired at its design service goal, was selected for the study. Two panels removed from the left-hand side of the fuselage crown, near stringer 4L, were subjected to extended fatigue testing using the Full-Scale Aircraft Structural Test Evaluation and Research (FASTER) facility located at the Federal Aviation Administration (FAA) William J. Hughes Technical Center. The state of MSD was continuously assessed using several nondestructive inspection (NDI) methods. Damage to the load attachment points of the first panel resulted in termination of the fatigue test at 43,500 fatigue cycles, before cracks had developed in the lap joint. The fatigue test for the second panel was initially conducted under simulated in-service loading conditions for 120,000 cycles, and no cracks were detected in the skin of the panel test section. Artificial damage was then introduced into the panel at selected rivets in the critical (lower) rivet row, and the fatigue loads were increased. Visually detectable crack growth from the artificial notches was first seen after 133,000 cycles. The resulting lead crack grew along the lower rivet row, eventually forming an 11.8" long unstable crack after 141,771 cycles, at which point the

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing.

PubMed

Villegas, Irene F; Palardy, Genevieve

2016-02-11

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.

Ultrasonic Welding of Thermoplastic Composite Coupons for Mechanical Characterization of Welded Joints through Single Lap Shear Testing

PubMed Central

Villegas, Irene F.; Palardy, Genevieve

2016-01-01

This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints. PMID:26890931

Strength of Welded Joints in Tubular Members for Aircraft

NASA Technical Reports Server (NTRS)

Whittemore, H L; Brueggeman, W C

1931-01-01

The object of this investigation is to make available to the aircraft industry authoritative information on the strength, weight, and cost of a number of types of welded joints. This information will, also, assist the aeronautics branch in its work of licensing planes by providing data from which the strength of a given joint may be estimated. As very little material on the strength of aircraft welds has been published, it is believed that such tests made by a disinterested governmental laboratory should be of considerable value to the aircraft industry. Forty joints were welded under procedure specifications and tested to determine their strengths. The weight and time required to fabricate were also measured for each joint.

Structural analysis of Aircraft fuselage splice joint

NASA Astrophysics Data System (ADS)

Udaya Prakash, R.; Kumar, G. Raj; Vijayanandh, R.; Senthil Kumar, M.; Ramganesh, T.

2016-09-01

In Aviation sector, composite materials and its application to each component are one of the prime factors of consideration due to the high strength to weight ratio, design flexibility and non-corrosive so that the composite materials are widely used in the low weight constructions and also it can be treated as a suitable alternative to metals. The objective of this paper is to estimate and compare the suitability of a composite skin joint in an aircraft fuselage with different joints by simulating the displacement, normal stress, vonmises stress and shear stress with the help of numerical solution methods. The reference Z-stringer component of this paper is modeled by CATIA and numerical simulation is carried out by ANSYS has been used for splice joint presents in the aircraft fuselage with three combinations of joints such as riveted joint, bonded joint and hybrid joint. Nowadays the stringers are using to avoid buckling of fuselage skin, it has joined together by rivets and they are connected end to end by splice joint. Design and static analysis of three-dimensional models of joints such as bonded, riveted and hybrid are carried out and results are compared.

Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

NASA Astrophysics Data System (ADS)

Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

2015-11-01

Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

Analysis on the Fracture of Al-Cu Dissimilar Materials Friction Stir Welding Lap Joint

NASA Astrophysics Data System (ADS)

Sun, Hongyu; Zhou, Qi; Zhu, Jun; Peng, Yong

2017-12-01

Friction stir welding (FWS) is regarded as a more plausible alternative to other welding methods for Al-Cu dissimilar joining. However, the structure of an FSW joint is different from others. In this study, lap joints of 6061 aluminum alloy and commercially pure copper were produced by FSW, and the effects of rotation rate on macromorphology, microstructure and mechanical properties were investigated. In addition, a fracture J integral model was used to analyze the effect of microstructure on the mechanical properties. The results revealed that the macrodefect-free joints were obtained at a feed rate of 150 mm/min and 1100 rpm and that the failure load of the joint reached as high as 4.57 kN and only reached 2.91 kN for the 900 rpm, where tunnel defects were identified. Particle-rich zones composed of Cu particles dispersed in an Al matrix, and "Flow tracks" were observed by the EDS. The J integral results showed that the microdefects on the advancing side cause serious stress concentration compared with the microdefects located on the Al-Cu interface, resulting in the fracture of the joints.

Biomimetic-inspired joining of composite with metal structures: A survey of natural joints and application to single lap joints

NASA Astrophysics Data System (ADS)

Avgoulas, Evangelos Ioannis; Sutcliffe, Michael P. F.

2014-03-01

Joining composites with metal parts leads, inevitably, to high stress concentrations because of the material property mismatch. Since joining composite to metal is required in many high performance structures, there is a need to develop a new multifunctional approach to meet this challenge. This paper uses the biomimetics approach to help develop solutions to this problem. Nature has found many ingenious ways of joining dissimilar materials and making robust attachments, alleviating potential stress concentrations. A literature survey of natural joint systems has been carried out, identifying and analysing different natural joint methods from a mechanical perspective. A taxonomy table was developed based on the different methods/functions that nature successfully uses to attach dissimilar tissues (materials). This table is used to understand common themes or approaches used in nature for different joint configurations and functionalities. One of the key characteristics that nature uses to joint dissimilar materials is a transitional zone of stiffness in the insertion site. Several biomimetic-inspired metal-to-composite (steel-to-CFRP), adhesively bonded, Single Lap Joints (SLJs) were numerically investigated using a finite element analysis. The proposed solutions offer a transitional zone of stiffness of one joint part to reduce the material stiffness mismatch at the joint. An optimisation procedure was used to identify the variation in material stiffness which minimises potential failure of the joint. It was found that the proposed biomimetic SLJs reduce the asymmetry of the stress distribution along the adhesive area.

Quiet Short-Haul Research Aircraft Joint Navy/NASA Sea Trials

NASA Technical Reports Server (NTRS)

Queen, S.; Cochrane, J.

1982-01-01

The Quiet Short-Haul Research Aircraft (QSRA) is a flight facility which Ames Research Center is using to conduct a broad program of terminal area and low-speed, propulsive-life flight research. A joint Navy/NASA flight research program used the QSRA to investigate the application of advanced propulsive-lift technology to the naval aircraft-carrier environment. Flight performance of the QSRA is presented together with the results or the joint Navy/NASA flight program. During the joint program, the QSRA operated aboard the USS Kitty Hawk for 4 days, during which numerous unarrested landings and free deck takeoffs were accomplished. These operations demonstrated that a large aircraft incorporating upper-surface-blowing, propulsive-life technology can be operated in the aircraft-carrier environment without any unusual problems.

Experimental characterization and numerical simulation of riveted lap-shear joints using Rivet Element

NASA Astrophysics Data System (ADS)

Vivio, Francesco; Fanelli, Pierluigi; Ferracci, Michele

2018-03-01

In aeronautical and automotive industries the use of rivets for applications requiring several joining points is now very common. In spite of a very simple shape, a riveted junction has many contact surfaces and stress concentrations that make the local stiffness very difficult to be calculated. To overcome this difficulty, commonly finite element models with very dense meshes are performed for single joint analysis because the accuracy is crucial for a correct structural analysis. Anyhow, when several riveted joints are present, the simulation becomes computationally too heavy and usually significant restrictions to joint modelling are introduced, sacrificing the accuracy of local stiffness evaluation. In this paper, we tested the accuracy of a rivet finite element presented in previous works by the authors. The structural behaviour of a lap joint specimen with a rivet joining is simulated numerically and compared to experimental measurements. The Rivet Element, based on a closed-form solution of a reference theoretical model of the rivet joint, simulates local and overall stiffness of the junction combining high accuracy with low degrees of freedom contribution. In this paper the Rivet Element performances are compared to that of a FE non-linear model of the rivet, built with solid elements and dense mesh, and to experimental data. The promising results reported allow to consider the Rivet Element able to simulate, with a great accuracy, actual structures with several rivet connections.

A multi-feature integration method for fatigue crack detection and crack length estimation in riveted lap joints using Lamb waves

NASA Astrophysics Data System (ADS)

He, Jingjing; Guan, Xuefei; Peng, Tishun; Liu, Yongming; Saxena, Abhinav; Celaya, Jose; Goebel, Kai

2013-10-01

This paper presents an experimental study of damage detection and quantification in riveted lap joints. Embedded lead zirconate titanate piezoelectric (PZT) ceramic wafer-type sensors are employed to perform in situ non-destructive evaluation (NDE) during fatigue cyclical loading. PZT wafers are used to monitor the wave reflection from the boundaries of the fatigue crack at the edge of bolt joints. The group velocity of the guided wave is calculated to select a proper time window in which the received signal contains the damage information. It is found that the fatigue crack lengths are correlated with three main features of the signal, i.e., correlation coefficient, amplitude change, and phase change. It was also observed that a single feature cannot be used to quantify the damage among different specimens since a considerable variability was observed in the response from different specimens. A multi-feature integration method based on a second-order multivariate regression analysis is proposed for the prediction of fatigue crack lengths using sensor measurements. The model parameters are obtained using training datasets from five specimens. The effectiveness of the proposed methodology is demonstrated using several lap joint specimens from different manufactures and under different loading conditions.

Chemical conditions inside occluded regions on corroding aircraft aluminum alloys.

PubMed

Lewis, K S; Yuan, J; Kelly, R G

1999-07-30

Corrosion of aluminum alloy structures costs the US Air Force in the order of US$1 x 10(9) annually. Corrosion develops in areas of overlap such as aircraft lap-splice joints and under protective organic coatings. Capillary electrophoresis (CE) has been used to determine the local chemistries at these corrosion sites of solutions that were extracted using a microsampling system. Analysis of the local solution within lap-splice joints from aircraft has been performed in two ways: rehydration of corrosion products and direct microsampling. The solutions collected were analyzed with CE to quantitatively determine the species present during corrosion. The most common ions detected were Cl-, NO2-, NO3-, HCO3-, K+, Al3+, Ca2+, Na+ and Mg2+. Studies of the solution chemistry under local coating defects are required to understand coating failure and develop more durable coatings. A microsampling system and micro pH sensor were developed to extract solution from and measure pH in defects with diameters as small as 170 microns. Actively corroding defects contained high concentrations of Cl-, Al3+, Mg2+, Mn2+ and Cu2+ whereas only trace levels of Mg2+ were found in repassivated defects. The effects of these species on initiation and propagation of corrosion are discussed.

Experimental Investigation and Finite Element Analysis on Fatigue Behavior of Aluminum Alloy 7050 Single-Lap Joints

NASA Astrophysics Data System (ADS)

Zhou, Bing; Cui, Hao; Liu, Haibo; Li, Yang; Liu, Gaofeng; Li, Shujun; Zhang, Shangzhou

2018-03-01

The fatigue behavior of single-lap four-riveted aluminum alloy 7050 joints was investigated by using high-frequency fatigue test and scanning electron microscope (SEM). Stress distributions obtained by finite element (FE) analysis help explain the fatigue performance. The fatigue test results showed that the fatigue lives of the joints depend on cold expansion and applied cyclic loads. FE analysis and fractography indicated that the improved fatigue lives can be attributed to the reduction in maximum stress and evolution of fatigue damage at the critical location. The beneficial effects of strengthening techniques result in tearing ridges or lamellar structure on fracture surface, decrease in fatigue striations spacing, delay of fatigue crack initiation, crack deflection in fatigue crack propagation and plasticity-induced crack closure.

Critical joints in large composite aircraft structure

NASA Technical Reports Server (NTRS)

Nelson, W. D.; Bunin, B. L.; Hart-Smith, L. J.

1983-01-01

A program was conducted at Douglas Aircraft Company to develop the technology for critical structural joints of composite wing structure that meets design requirements for a 1990 commercial transport aircraft. The prime objective of the program was to demonstrate the ability to reliably predict the strength of large bolted composite joints. Ancillary testing of 180 specimens generated data on strength and load-deflection characteristics which provided input to the joint analysis. Load-sharing between fasteners in multirow bolted joints was computed by the nonlinear analysis program A4EJ. This program was used to predict strengths of 20 additional large subcomponents representing strips from a wing root chordwise splice. In most cases, the predictions were accurate to within a few percent of the test results. In some cases, the observed mode of failure was different than anticipated. The highlight of the subcomponent testing was the consistent ability to achieve gross-section failure strains close to 0.005. That represents a considerable improvement over the state of the art.

Computerized evaluation of holographic interferograms for fatigue crack detection in riveted lap joints

NASA Astrophysics Data System (ADS)

Zhou, Xiang

Using an innovative portable holographic inspection and testing system (PHITS) developed at the Australian Defence Force Academy, fatigue cracks in riveted lap joints can be detected by visually inspecting the abnormal fringe changes recorded on holographic interferograms. In this thesis, for automatic crack detection, some modern digital image processing techniques are investigated and applied to holographic interferogram evaluation. Fringe analysis algorithms are developed for identification of the crack-induced fringe changes. Theoretical analysis of PHITS and riveted lap joints and two typical experiments demonstrate that the fatigue cracks in lightly-clamped joints induce two characteristic fringe changes: local fringe discontinuities at the cracking sites; and the global crescent fringe distribution near to the edge of the rivet hole. Both of the fringe features are used for crack detection in this thesis. As a basis of the fringe feature extraction, an algorithm for local fringe orientation calculation is proposed. For high orientation accuracy and computational efficiency, Gaussian gradient filtering and neighboring direction averaging are used to minimize the effects of image background variations and random noise. The neighboring direction averaging is also used to approximate the fringe directions in centerlines of bright and dark fringes. Experimental results indicate that for high orientation accuracy the scales of the Gaussian filter and neighboring direction averaging should be chosen according to the local fringe spacings. The orientation histogram technique is applied to detect the local fringe discontinuity due to the fatigue cracks. The Fourier descriptor technique is used to characterize the global fringe distribution change from a circular to a crescent distribution with the fatigue crack growth. Experiments and computer simulations are conducted to analyze the detectability and reliability of crack detection using the two techniques. Results

Friction stir lap joining of automotive aluminium alloy and carbon-fiber-reinforced plastic

NASA Astrophysics Data System (ADS)

Bang, H. S.; Das, A.; Lee, S.; Bang, H. S.

2018-05-01

Multi-material combination such as aluminium alloys and carbon-fiber-reinforced plastics (CFRP) are increasingly used in the aircraft and automobile industries to enhance strength-to-weight ratio of the respective parts and components. Various processes such as adhesive bonding, mechanical fasteners and laser beam joining were employed to join metal alloy and CFRP sheets. However, long processing time of adhesive bonding, extra weight induced by mechanical fasteners and high operating cost of the laser is major limitations of these processes. Therefore, friction stir welding is an alternative choice to overcome those limitations in joining of CFRP and aluminium alloys. In the present work, an attempt is undertaken to join AA5052 alloy and polyamide 66 CFRP sheets by friction stir lap joining technique using pinned and pin-less tools. The joint qualities are investigated extensively at different joining conditions using two different types of tools and surface ground aluminium sheets. The results show that pin-less tool and surface ground aluminium alloy can provide the suitable joint with maximum joint strength around 8 MPa.

Enhanced Imaging of Corrosion in Aircraft Structures with Reverse Geometry X-ray(registered tm)

NASA Technical Reports Server (NTRS)

Winfree, William P.; Cmar-Mascis, Noreen A.; Parker, F. Raymond

2000-01-01

The application of Reverse Geometry X-ray to the detection and characterization of corrosion in aircraft structures is presented. Reverse Geometry X-ray is a unique system that utilizes an electronically scanned x-ray source and a discrete detector for real time radiographic imaging of a structure. The scanned source system has several advantages when compared to conventional radiography. First, the discrete x-ray detector can be miniaturized and easily positioned inside a complex structure (such as an aircraft wing) enabling images of each surface of the structure to be obtained separately. Second, using a measurement configuration with multiple detectors enables the simultaneous acquisition of data from several different perspectives without moving the structure or the measurement system. This provides a means for locating the position of flaws and enhances separation of features at the surface from features inside the structure. Data is presented on aircraft specimens with corrosion in the lap joint. Advanced laminographic imaging techniques utilizing data from multiple detectors are demonstrated to be capable of separating surface features from corrosion in the lap joint and locating the corrosion in multilayer structures. Results of this technique are compared to computed tomography cross sections obtained from a microfocus x-ray tomography system. A method is presented for calibration of the detectors of the Reverse Geometry X-ray system to enable quantification of the corrosion to within 2%.

Detection of defects in laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration by a real-time spectroscopic analysis

NASA Astrophysics Data System (ADS)

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-05-01

The effect of surface oxide layer existing at the lap-joint faying surface of magnesium sheets is investigated on the keyhole dynamics of the weld pool and weld bead qualities. It is observed that by removing the oxide layer from the faying surface of the lap joint, a high quality weld can be achieved in the laser welding process. However, the presence of an oxide layer deteriorates the quality of the weld by forming pores at the interface of the two overlapped sheets. The purpose of this paper is to identify the correlation between the integrity of the weld and the interaction between the laser and material. A spectroscopy sensor was applied to detect the spectra emitted from a plasma plume during the laser welding of AZ31B magnesium alloy in a zero-gap lap joint configuration. The electron temperature was calculated by applying a Boltzmann plot method based on the detected spectra, and the correlation between the pore formation and the spectral signals was studied. The laser molten pool and the keyhole condition were monitored in real-time by a high speed charge-coupled device (CCD) camera. A green laser was used as an illumination source in order to detect the influence of the oxide layer on the dynamic behavior of the molten pool. Results revealed that the detected spectrum and weld defects had a meaningful correlation for real-time monitoring of the weld quality during laser welding of magnesium alloys.

Lapping slurry

DOEpatents

Simandl, R.F.; Upchurch, V.S.; Leitten, M.E.

1999-01-05

Improved lapping slurries provide for easier and more thorough cleaning of alumina work pieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid. 1 fig.

Lapping slurry

DOEpatents

Simandl, Ronald F.; Upchurch, Victor S.; Leitten, Michael E.

1999-01-01

Improved lapping slurries provide for easier and more thorough cleaning of alumina workpieces, as well as inhibit corrosion of the lapping table and provide for easier cleaning of the lapping equipment. The unthickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, and triethanolamine. The thickened lapping slurry comprises abrasive grains such as diamond abrasive dispersed in a carrier comprising water, glycerine, triethanolamine, a water soluble silicate, and acid.

Abernathy's Lap

NASA Technical Reports Server (NTRS)

1977-01-01

A lap in this instance is not a midriff but a tool for presision.polishing and grinding. During the Saturn V moonbooster program, Marshall Space Flight Center found a need for a better lap. The need arose from the exquisitely precise tolerances required for parts of the launch vehicle's guidance,and control system. So William J. Abernathy, a former Marshall employee, built a better lap; he invented a method for charging aluminum lap plates with diamond powder, then hard-anodizing them. The resulting lap produces a high polish on materials ranging from the softest aluminum to the hardest ceramics. It operates faster, wears longer and requires less reworking. Abernathy got NASA's permission to obtain a personal patent and he formed the one-man Abernathy Laps Co. in Huntsville, which produces a variety of laps. One of Abernathy's customers is Bell Aerospace Textron, Buffalo, which uses the laps to finish polish delicate instrument parts produced for NASA's Viking and other space programs. Says a Bell official: "Time needed (with the Abernathy lap) is a fraction of that required by conventional methods. The result is extremely accurate flatness and surface finish." Abernathy is providing laps for other manufacturing applications and for preparation of metallurgical specimens. The business is small but steady, and Abernathy plans expansion into other markets.

A laboratory study of multiple site damage in fuselage lap splices

DOT National Transportation Integrated Search

1993-12-01

This report details an experimental study that was conducted to explore the causes of : fuselage lap splice multiple site damage (MSD), which has been observed in several : aging aircraft. MSD was partially responsible for the 1988 Aloha Airlines acc...

An evaluation of the lap-shear test for Sn-rich solder/Cu couples: Experiments and simulation

NASA Astrophysics Data System (ADS)

Chawla, N.; Shen, Y.-L.; Deng, X.; Ege, E. S.

2004-12-01

The lap-shear technique is commonly used to evaluate the shear, creep, and thermal fatigue behavior of solder joints. We have conducted a parametric experimental and modeling study, on the effect of testing and geometrical parameters on solder/copper joint response in lap-shear. It was shown that the farfield applied strain is quite different from the actual solder strain (measured optically). Subtraction of the deformation of the Cu substrate provides a reasonable approximation of the solder strain in the elastic regime, but not in the plastic regime. Solder joint thickness has a profound effect on joint response. The solder response moves progressively closer to “true” shear response with increasing joint thickness. Numerical modeling using finite-element analyses were performed to rationalize the experimental findings. The same lap-shear configuration was used in the simulation. The input response for solder was based on the experimental tensile test result on bulk specimens. The calculated shear response, using both the commonly adopted far-field measure and the actual shear strain in solder, was found to be consistent with the trends observed in the lap-shear experiments. The geometric features were further explored to provide physical insight into the problem. Deformation of the substrate was found to greatly influence the shear behavior of the solder.

Lap Shear Testing of Candidate Radiator Panel Adhesives

NASA Technical Reports Server (NTRS)

Ellis, David; Briggs, Maxwell; McGowan, Randy

2013-01-01

During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

Aging Aircraft 2005, The Joint NASA/FAA/DOD Conference on Aging Aircraft, Decision algorithms for Electrical Wiring Interconnect Systems (EWIS)Fault Detection

DTIC Science & Technology

2005-02-03

Aging Aircraft 2005 The 8th Joint NASA /FAA/DOD Conference on Aging Aircraft Decision Algorithms for Electrical Wiring Interconnect Systems (EWIS...SUBTITLE Aging Aircraft 2005, The 8th Joint NASA /FAA/DOD Conference on Aging Aircraft, Decision algorithms for Electrical Wiring Interconnect...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) NASA Langley Research Center, 8W. Taylor St., M/S 190 Hampton, VA 23681 and NAVAIR

Study on Joint Interface and Mechanical Properties of Cu/Pb-Sn/Cu Lap Joint Produced by Friction Stir Soldering Process

NASA Astrophysics Data System (ADS)

Sarkari Khorrami, Mahmoud; Kokabi, Amir Hossein; Movahedi, Mojtaba

2015-05-01

In this work, friction stir soldering (FSS) as a new approach for fabrication of copper/copper lap joints was introduced. This process is principally based on the friction stir processing (FSP) that can be performed using FSP tools with and without pin on the top sheet. In the present study, Pb-Sn foil was used as a solder which would be melted and then extruded in the area between the copper sheets during FSS process. This process was carried out using tools with and without pin at various rotation speeds of 1200, 1400, and 1600 rpm and traverse speed of 32 mm/min. Also, the same joint was fabricated using furnace soldering to compare the mechanical properties obtained with FSS and furnace soldering processes. It was observed that FSS possesses some advantages over the conventional furnace soldering process including the formation of more bond area at the interface corresponding to the higher fracture load of FSS joints compared with furnace soldering one. Moreover, it was concluded that the thickness of intermetallic compounds (IMCs) and the formation of voids at the joint interface were the predominant factor determining the mechanical properties of the FSS joints produced by FSS tool with and without pin, respectively. The microstructural examinations revealed that Cu-Sn IMCs of Cu3Sn and Cu6Sn5 were formed at the joint interface. It was observed that the FSS joint produced by tool with pin experienced the more peak temperature in comparison with that produced by pin-free tool. This may lead to the formation of thicker IMCs at the interface. Of course, the thickness of IMCs can be controlled by choosing proper FSS parameters, especially the rotation speed of the tool.

Low frequency ultrasonic nondestructive inspection of aluminum/adhesive fuselage lap splices

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

Patton, Thadd

1994-01-04

This thesis is a collection of research efforts in ultrasonics, conducted at the Center for Aviation Systems Reliability located at Iowa State University, as part of the Federal Aviation Administration`s ``Aging Aircraft Program.`` The research was directed toward the development of an ultrasonic prototype to inspect the aluminum/adhesive fuselage lap splices found on 1970`s vintage Boeing passenger aircraft. The ultrasonic prototype consists of a normal incidence, low frequency inspection technique, and a scanning adapter that allows focused immersion transducers to be operated in a direct contact manner in any inspection orientation, including upside-down. The inspection technique uses a computer-controlled datamore » acquisition system to produce a C-scan image of a radio frequency (RF) waveform created by a low frequency, broadband, focused beam transducer, driven with a spike voltage pulser. C-scans produced by this technique are color representations of the received signal`s peak-to-peak amplitude (voltage) taken over an (x, y) grid. Low frequency, in this context, refers to a wavelength that is greater than the lap splice`s layer thicknesses. With the low frequency technique, interface echoes of the lap splice are not resolved and gating of the signal is unnecessary; this in itself makes the technique simple to implement and saves considerable time in data acquisition. Along with the advantages in data acquisition, the low frequency technique is relatively insensitive to minor surface curvature and to ultrasonic interference effects caused by adhesive bondline thickness variations in the lap splice.« less

Test results of smart aircraft fastener for KC-135 structural integrity

NASA Astrophysics Data System (ADS)

Schoess, Jeffrey N.; Seifert, Greg

1998-07-01

Hidden and inaccessible corrosion in aircraft structures is the number one logistics problem for the US Air Force, with an estimated maintenance cost in excess of $LR 1.0B per year in 1990-equivalent dollars. The Smart Aircraft Fastener Evaluation (SAFE) system was developed to provide early warning detection of corrosion-related symptoms in hidden locations of aircraft structures. The SAFE system incorporates an in situ measurement approach that measures and autonomously records several environmental conditions within a Hi-Lok aircraft fastener that could cause corrosion. The SAFE system integrates a miniature electrochemical microsensor array and a time-of-wetness sensor with an ultra low power 8-bit microcontroller and 4- Mbyte solid-state FLASH archival memory to measure evidence of active corrosion. A summary of the technical approach and a detailed analysis of the KC-135 lap joint test coupon results are presented.

FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

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

Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.

2015-02-16

Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribemore » welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.« less

Joint Technical Coordinating Group on Aircraft Survivability (JTCG/AS). Bibliography of Joint Aircraft Survivability Reports

DTIC Science & Technology

2000-07-01

PMSG ). Report No.: JTCG/AS-99-D-003 Report Classification: UNCLASSIFIED Title: JTCG/AS Bibliography of Joint Aircraft Survivability Reports and...indicates those approved and not approved for funding by the Principal Members Steering Group ( PMSG ). Report No.: Report Classification: JTCG/AS-97-V-010...demonstrated by additional tests conducted at NWSC/Crane (up to Mach 0.8) and Rockwell International wind tunnel (up to Mach 1/9 and 30,000 feet altitude

Reliability of Step-Lap Bonded Joints

DTIC Science & Technology

1975-04-01

1.5. This P e gives a x f’t equal to .25 and a strength of 5400 (lb/in). Thermal stresses av p were not considered. Experience indicates that for both...a (-~p; ACAro 48 - 2095 -5 49 -2057 0’ 50 -2099 +45,’ j~d P~ FIGURE 35. FULL SCALE STEP-LAP SPECIMEN DRAWING 49 TA?)LE I. PLY OhbW6I40WE~Th a I...11. T464-.- S~w lW- iZ44 ILL A 40 C 4 W AP- I. _Asllll-ýL04-c &FC o W. Ox.-F-fwau". %r IpśX~ -Rt 4 r m 1 - 6-an AV ?t= .C3)-.Zfr.UROA M 0:frca 0 AW

Fatigue Strength and Related Characteristics of Aircraft Joints I : Comparison of Spot-Weld and Rivet Patterns in 24s-t Alclad and 75s-t Alclad

NASA Technical Reports Server (NTRS)

Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

1944-01-01

Report contains detailed results of a number of fatigue tests on spot-welded joints in aluminum alloys. The tests described include: (1) fatigue tests on spot-welded lap joints in sheets of unequal thickness of alclad 24s-t. These tests indicate that the fatigue strength of a spot-welded joint in sheets of two different gages is slightly higher than that of a similar joint in two sheets of the thinner gage but definitely lower than that of a similar joint in two sheets of the thicker gage. (2) Fatigue tests on spot-welded alclad 75s-t spot-welded lap-joint specimens of alclad 75s-t were not any stronger in fatigue than similar specimens of alclad 24s-t. (3) Fatigue tests on lap-joint specimens spot -welded after various surface preparations--these included ac welding wire-brushed surfaces, dc welding wire-brushed surfaces, and dc welding chemically cleaned surfaces. While the ac welds were strongest statically, the dc welds on wire-brushed surfaces were strongest in fatigue. Specimens prepared in this way were very nearly as strong as the best riveted specimens tested for comparison. (4) Fatigue tests on specimens spot-welded with varying voltage so as to include a wide range of static spot-weld strengths. The fatigue strengths were in the same order as the static strengths but showed less range. (author)

Dual beam Nd:YAG laser welding: influence of lubricants to lap joint welding of steel sheets

NASA Astrophysics Data System (ADS)

Geiger, M.; Merklein, M.; Otto, A.; Blankl, A.

2007-05-01

Laser welding is applied in large-volume production since the late eighties and has revolutionized the possibilities of designing and engineering products. Nevertheless, problems appear during application because the operational conditions in industrial environments fluctuate and can influence the welding process negatively. Contaminations, like lubricants and organic solids, are an example of changing conditions in laser beam welding. If a lap joint is welded, these materials have to be removed from the sheets, otherwise pores and surface failures may appear due to keyhole instabilities induced by uncontrolled outgassing. One possibility for solving this problem is the use of two separate laser beams. For producing these two beams several systems are available for all different kind of lasers. A bifocal optic is such a solution for an Nd:YAG laser. By using this system, the laser beam is divided after collimation with a prism. Afterwards the two beams are focussed with a lens to the surface of the sheet and two single spots are produced. If the distance between the two spots is low, one common, elliptical keyhole is created. With this system two different welding strategies are possible. The spots can be oriented parallel or normal to the feed direction. For stabilizing the laser welding of contaminated steel sheets the parallel arrangement is better, because the amount of contamination is nearly the same as in single spot welding but the total volume of the keyhole is greater and so pressure variations due to uncontrolled evaporation of contaminations are lower. In order to prove this theory and to determine the exact effects some investigations were made at the Chair of Manufacturing Technology of the University of Erlangen-Nuremberg. A 4 kW Nd:YAG laser with a beam parameter product of 25 mm*mrad and a focal distance of 200 mm was used to weld two 1 mm DC04 steel sheets together with a lap joint. Between the sheets a deep drawing lubricant, Castrol FST 6, was

Large-Scale Advanced Prop-Fan (LAP)

NASA Technical Reports Server (NTRS)

Degeorge, C. L.

1988-01-01

In recent years, considerable attention has been directed toward improving aircraft fuel efficiency. Analytical studies and research with wind tunnel models have demonstrated that the high inherent efficiency of low speed turboprop propulsion systems may now be extended to the Mach .8 flight regime of today's commercial airliners. This can be accomplished with a propeller, employing a large number of thin highly swept blades. The term Prop-Fan has been coined to describe such a propulsion system. In 1983 the NASA-Lewis Research Center contracted with Hamilton Standard to design, build and test a near full scale Prop-Fan, designated the Large Scale Advanced Prop-Fan (LAP). This report provides a detailed description of the LAP program. The assumptions and analytical procedures used in the design of Prop-Fan system components are discussed in detail. The manufacturing techniques used in the fabrication of the Prop-Fan are presented. Each of the tests run during the course of the program are also discussed and the major conclusions derived from them stated.

Measurement of longitudinal strain and estimation of peel stress in adhesive-bonded single-lap joint of CFRP adherend using embedded FBG sensor

NASA Astrophysics Data System (ADS)

Ning, X.; Murayama, H.; Kageyama, K.; Uzawa, K.; Wada, D.

2012-04-01

In this research, longitudinal strain and peel stress in adhesive-bonded single-lap joint of carbon fiber reinforced plastics (CFRP) were measured and estimated by embedded fiber Bragg grating (FBG) sensor. Two unidirectional CFRP substrates were bonded by epoxy to form a single-lap configuration. The distributed strain measurement system is used. It is based on optical frequency domain reflectometry (OFDR), which can provide measurement at an arbitrary position along FBG sensors with the high spatial resolution. The longitudinal strain was measured based on Bragg grating effect and the peel stress was estimated based on birefringence effect. Special manufacturing procedure was developed to ensure the embedded location of FBG sensor. A portion of the FBG sensor was embedded into one of CFRP adherends along fiber direction and another portion was kept free for temperature compensation. Photomicrograph of cross-section of specimen was taken to verify the sensor was embedded into proper location after adherend curing. The residual strain was monitored during specimen curing and adhesive joint bonding process. Tensile tests were carried out and longitudinal strain and peel stress of the bondline are measured and estimated by the embedded FBG sensor. A two-dimensional geometrically nonlinear finite element analysis was performed by ANSYS to evaluate the measurement precision.

Large-Scale Advanced Prop-Fan (LAP) pitch change actuator and control design report

NASA Technical Reports Server (NTRS)

Schwartz, R. A.; Carvalho, P.; Cutler, M. J.

1986-01-01

In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the high inherent efficiency previously demonstrated by low speed turboprop propulsion systems may now be extended to today's higher speed aircraft if advanced high-speed propeller blades having thin airfoils and aerodynamic sweep are utilized. Hamilton Standard has designed a 9-foot diameter single-rotation Large-Scale Advanced Prop-Fan (LAP) which will be tested on a static test stand, in a high speed wind tunnel and on a research aircraft. The major objective of this testing is to establish the structural integrity of large-scale Prop-Fans of advanced construction in addition to the evaluation of aerodynamic performance and aeroacoustic design. This report describes the operation, design features and actual hardware of the (LAP) Prop-Fan pitch control system. The pitch control system which controls blade angle and propeller speed consists of two separate assemblies. The first is the control unit which provides the hydraulic supply, speed governing and feather function for the system. The second unit is the hydro-mechanical pitch change actuator which directly changes blade angle (pitch) as scheduled by the control.

Shear fracture of jointed steel plates of bolted joints under impact load

NASA Astrophysics Data System (ADS)

Daimaruya, M.; Fujiki, H.; Ambarita, H.; Kobayashi, H.; Shin, H.-S.

2013-07-01

The present study is concerned with the development of a fracture criterion for the impact fracture of jointed steel plates of bolted joints used in a car body, which contributes to crash simulations by CAE. We focus our attention on the shear fracture of the jointed steel plates of lap-bolted joints in the suspension of a car under impact load. Members of lap-bolted joints are modelled as a pair of steel plates connected by a bolt. One of the plates is a specimen subjected to plastic deformation and fracture and the other is a jig subjected to elastic deformation only. Three kinds of steel plate specimens are examined, i.e., a common steel plate with a tensile strength of 270 MPa and high tensile strength steel plates of 440 and 590 MPa used for cars. The impact shear test was performed using the split Hopkinson bar technique for tension impact, together with the static test using a universal testing machine INSTRON 5586. The behaviour of the shear stress and deformation up to rupture taking place in the joint was discussed. The obtained results suggest that a stress-based fracture criterion may be developed for the impact fracture of jointed steel plates of a lap-bolted joint.

Even between-lap pacing despite high within-lap variation during mountain biking.

PubMed

Martin, Louise; Lambeth-Mansell, Anneliese; Beretta-Azevedo, Liane; Holmes, Lucy A; Wright, Rachel; St Clair Gibson, Alan

2012-09-01

Given the paucity of research on pacing strategies during competitive events, this study examined changes in dynamic high-resolution performance parameters to analyze pacing profiles during a multiple-lap mountain-bike race over variable terrain. A global-positioning-system (GPS) unit (Garmin, Edge 305, USA) recorded velocity (m/s), distance (m), elevation (m), and heart rate at 1 Hz from 6 mountain-bike riders (mean±SD age=27.2±5.0 y, stature=176.8±8.1 cm, mass=76.3±11.7 kg, VO2max=55.1±6.0 mL·kg(-1)·min1) competing in a multilap race. Lap-by-lap (interlap) pacing was analyzed using a 1-way ANOVA for mean time and mean velocity. Velocity data were averaged every 100 m and plotted against race distance and elevation to observe the presence of intralap variation. There was no significant difference in lap times (P=.99) or lap velocity (P=.65) across the 5 laps. Within each lap, a high degree of oscillation in velocity was observed, which broadly reflected changes in terrain, but high-resolution data demonstrated additional nonmonotonic variation not related to terrain. Participants adopted an even pace strategy across the 5 laps despite rapid adjustments in velocity during each lap. While topographical and technical variations of the course accounted for some of the variability in velocity, the additional rapid adjustments in velocity may be associated with dynamic regulation of self-paced exercise.

Effect of Pin Length on Hook Size and Joint Properties in Friction Stir Lap Welding of 7B04 Aluminum Alloy

NASA Astrophysics Data System (ADS)

Wang, Min; Zhang, Huijie; Zhang, Jingbao; Zhang, Xiao; Yang, Lei

2014-05-01

Friction stir lap welding of 7B04 aluminum alloy was conducted in the present paper, and the effect of pin length on hook size and joint properties was investigated in detail. It is found that for each given set of process parameters, the size of hook defect on the advancing side shows an "M" type evolution trend as the pin length is increased. The affecting characteristics of pin length on joint properties are dependent on the heat input levels. When the heat input is low, the fracture strength is firstly increased to a peak value and then shows a decrease. When the heat input is relatively high, the evolution trend of fracture strength tends to exhibit a "W" type with increasing the pin length.

Application of lap laser welding technology on stainless steel railway vehicles

NASA Astrophysics Data System (ADS)

Wang, Hongxiao; Wang, Chunsheng; He, Guangzhong; Li, Wei; Liu, Liguo

2016-10-01

Stainless steel railway vehicles with so many advantages, such as lightweight, antirust, low cost of maintenance and simple manufacturing process, so the production of high level stainless steel railway vehicles has become the development strategy of European, American and other developed nations. The current stainless steel railway vehicles body and structure are usually assembled by resistance spot welding process. The weak points of this process are the poor surface quality and bad airtight due to the pressure of electrodes. In this study, the partial penetration lap laser welding process was investigated to resolve the problems, by controlling the laser to stop at the second plate in the appropriate penetration. The lap laser welding joint of stainless steel railway vehicle car body with partial penetration has higher strength and surface quality than those of resistance spot welding joint. The biggest problem of lap laser welding technology is to find the balance of the strength and surface quality with different penetrations. The mechanism of overlap laser welding of stainless steel, mechanical tests, microstructure analysis, the optimization of welding parameters, analysis of fatigue performance, the design of laser welding stainless steel railway vehicles structure and the development of non-destructive testing technology were systematically studied before lap laser welding process to be applied in manufacture of railway vehicles. The results of the experiments and study show that high-quality surface state and higher fatigue strength can be achieved by the partial penetration overlap laser welding of the side panel structure, and the structure strength of the car body can be higher than the requirements of En12663, the standard of structural requirements of railway vehicles bodies. Our company has produced the stainless steel subway and high way railway vehicles by using overlap laser welding technology. The application of lap laser welding will be a big

Dynamic thermal tomography for nondestructive inspection of aging aircraft

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

Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.

1993-11-01

The authors apply dual-band infrared (DBIR) imaging as a dynamic thermal tomography tool for wide area inspection of a Boeing 737 aircraft and several Boeing KC-135 aircraft panels. The analyses are discussed in this report. After flash-heating the aircraft skin, they record synchronized DBIR images every 40 ms, from onset to 8 seconds after the heat flash. They analyze selective DBIR image ratios which enhance surface temperature contrast and remove surface-emissivity clutter. The Boeing 737 and KC-135 aircraft fuselage panels have varying percent thickness losses from corrosion. They established the correlation of percent thickness loss with surface temperature rise (abovemore » ambient) for a partially corroded F-18 wing box structure and several aluminum plates which had 6 to 60% thickness losses at milled flat-bottom hole sites. Based on this correlation, lap splice temperatures rise 1C per 24 {plus_minus} 5% material loss at 0.4 s after the heat flash. They tabulate and map corrosion-related percent thickness loss effects for the riveted Boeing 737, and the riveted Boeing KKC-135. They map the fuselage composite thermal inertia, based on the (inverse) slope of the surface temperature versus inverse square root of time. Composite thermal inertia maps characterized shallow skin defects within the lap splice at early times (< 0.3 s) and deeper skin defects within the lap splice at late times (> 0.4 s). Late time composite thermal inertia maps depict where corrosion-related thickness losses occur (e.g., on the inside of the Boeing 737 lap splice, beneath the galley and the latrine). Lap splice sites on a typical Boeing KC-135 panel with low composite thermal inertia values had high skin-thickness losses from corrosion.« less

Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

NASA Astrophysics Data System (ADS)

Florea, Radu Stefanel

This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone

Sequential lineup laps and eyewitness accuracy.

PubMed

Steblay, Nancy K; Dietrich, Hannah L; Ryan, Shannon L; Raczynski, Jeanette L; James, Kali A

2011-08-01

Police practice of double-blind sequential lineups prompts a question about the efficacy of repeated viewings (laps) of the sequential lineup. Two laboratory experiments confirmed the presence of a sequential lap effect: an increase in witness lineup picks from first to second lap, when the culprit was a stranger. The second lap produced more errors than correct identifications. In Experiment 2, lineup diagnosticity was significantly higher for sequential lineup procedures that employed a single versus double laps. Witnesses who elected to view a second lap made significantly more errors than witnesses who chose to stop after one lap or those who were required to view two laps. Witnesses with prior exposure to the culprit did not exhibit a sequential lap effect.

Bolted joints in graphite-epoxy composites

NASA Technical Reports Server (NTRS)

Hart-Smith, L. J.

1976-01-01

All-graphite/epoxy laminates and hybrid graphite-glass/epoxy laminates were tested. The tests encompassed a range of geometries for each laminate pattern to cover the three basic failure modes - net section tension failure through the bolt hole, bearing and shearout. Static tensile and compressive loads were applied. A constant bolt diameter of 6.35 mm (0.25 in.) was used in the tests. The interaction of stress concentrations associated with multi-row bolted joints was investigated by testing single- and double-row bolted joints and open-hole specimens in tension. For tension loading, linear interaction was found to exist between the bearing stress reacted at a given bolt hole and the remaining tension stress running by that hole to be reacted elsewhere. The interaction under compressive loading was found to be non-linear. Comparative tests were run using single-lap bolted joints and double-lap joints with pin connection. Both of these joint types exhibited lower strengths than were demonstrated by the corresponding double-lap joints. The analysis methods developed here for single bolt joints are shown to be capable of predicting the behavior of multi-row joints.

Non-destructive testing techniques based on nonlinear methods for assessment of debonding in single lap joints

NASA Astrophysics Data System (ADS)

Scarselli, G.; Ciampa, F.; Ginzburg, D.; Meo, M.

2015-04-01

Nonlinear ultrasonic non-destructive evaluation (NDE) methods can be used for the identification of defects within adhesive bonds as they rely on the detection of nonlinear elastic features for the evaluation of the bond strength. In this paper the nonlinear content of the structural response of a single lap joint subjected to ultrasonic harmonic excitation is both numerically and experimentally evaluated to identify and characterize the defects within the bonded region. Different metallic samples with the same geometry were experimentally tested in order to characterize the debonding between two plates by using two surface bonded piezoelectric transducers in pitch-catch mode. The dynamic response of the damaged samples acquired by the single receiver sensor showed the presence of higher harmonics (2nd and 3rd) and subharmonics of the fundamental frequencies. These nonlinear elastic phenomena are clearly due to nonlinear effects induced by the poor adhesion between the two plates. A new constitutive model aimed at representing the nonlinear material response generated by the interaction of the ultrasonic waves with the adhesive joint is also presented. Such a model is implemented in an explicit FE software and uses a nonlinear user defined traction-displacement relationship implemented by means of a cohesive material user model interface. The developed model is verified for the different geometrical and material configurations. Good agreement between the experimental and numerical nonlinear response showed that this model can be used as a simple and useful tool for understanding the quality of the adhesive joint.

Influence of Zn Interlayer on Interfacial Microstructure and Mechanical Properties of TIG Lap-Welded Mg/Al Joints

NASA Astrophysics Data System (ADS)

Gao, Qiong; Wang, Kehong

2016-03-01

This study explored 6061 Al alloy and AZ31B Mg alloy joined by TIG lap welding with Zn foils of varying thicknesses, with the additional Zn element being imported into the fusion zone to alloy the weld seam. The microstructures and chemical composition in the fusion zone near the Mg substrate were examined by SEM and EDS, and tensile shear strength tests were conducted to investigate the mechanical properties of the Al/Mg joints, as well as the fracture surfaces, and phase compositions. The results revealed that the introduction of an appropriate amount of Zn transition layer improves the microstructure of Mg/Al joints and effectively reduces the formation of Mg-Al intermetallic compounds (IMCs). The most common IMCs in the fusion zone near the Mg substrate were Mg-Zn and Mg-Al-Zn IMCs. The type and distribution of IMCs generated in the weld zone differed according to Zn additions; Zn interlayer thickness of 0.4 mm improved the sample's mechanical properties considerably compared to thicknesses of less than 0.4 mm; however, any further increase in Zn interlayer thickness of above 0.4 mm caused mechanical properties to deteriorate.

Strain measurements in composite bolted-joint specimens

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Lightfoot, M. C.; Perry, J. C.

1979-01-01

Strain data from a series of bolted joint tests is presented. Double lap, double hole, double lap, single hole, and open hole tensile specimens were tested and the strain gage locations, load strain responses, and load axial displacement responses are presented. The open hole specimens were gaged to determine strain concentration factors. The double lap, double hole specimens were gaged to determine the uniformity of the strain in the joint and the amount of load transferred past the first bolt. The measurements indicated roughly half the load passed the first bolt to be reacted by the second bolt.

NDE scanning and imaging of aircraft structure

NASA Astrophysics Data System (ADS)

Bailey, Donald; Kepler, Carl; Le, Cuong

1995-07-01

The Science and Engineering Lab at McClellan Air Force Base, Sacramento, Calif. has been involved in the development and use of computer-based scanning systems for NDE (nondestructive evaluation) since 1985. This paper describes the history leading up to our current applications which employ eddy current and ultrasonic scanning of aircraft structures that contain both metallics and advanced composites. The scanning is performed using industrialized computers interfaced to proprietary acquisition equipment and software. Examples are shown that image several types of damage such as exfoliation and fuselage lap joint corrosion in aluminum, impact damage, embedded foreign material, and porosity in Kevlar and graphite epoxy composites. Image analysis techniques are reported that are performed using consumer oriented computer hardware and software that are not NDE specific and not expensive

An artifical corrosion protocol for lap-splices in aircraft skin

NASA Technical Reports Server (NTRS)

Shaw, Bevil J.

1994-01-01

This paper reviews the progress to date to formulate an artificial corrosion protocol for the Tinker AFB C/KC-135 Corrosion Fatigue Round Robin Test Program. The project has provided new test methods to faithfully reproduce the corrosion damage within a lap-splice by accelerated means, the rationale for a new laboratory test environment, and a means for corrosion damage quantification. The approach is pragmatic and the resulting artificial corrosion protocol lays the foundation for future research in the assessment of aerospace alloys. The general means for quantification of corrosion damage has been presented in a form which can be directly applied to structural integrity calculations.

The cyclic fatigue behavior of adhesive joints

NASA Astrophysics Data System (ADS)

Kinloch, A. J.; Toh, T.

1995-06-01

In the last six months we have: (1) Concentrated our efforts on the fatigue failure of carbon-fiber PEEK/AFl63 lap joints, and in particular we have started to predict the life time of single-lap joints under cyclic fatigue loading. The analysis is based on data obtained from double cantilever beam (DCB) fracture mechanics tests; (2) Further, we have been successful in measuring the rate of crack growth in lap joints during fatigue fracture using ultrasonic scanning; (3) Preliminary test data on the static fracture of glass-fiber reinforced poly(phenylene sulphide) (PPS)/AF163 joints have also been studied; and (4) A comparison has been made in computing the critical strain energy release rate G(sub c) for the glass-fiber PPS/AF163 joints based on the compliance method, beam theory and corrected beam theory. The last method accounts for large non-linear deflections and the associated crack root rotations along with the necessary corrections for the increase in stiffness introduced by the presence of end blocks.

Design of a composite wing extension for a general aviation aircraft

NASA Technical Reports Server (NTRS)

Adney, P. S.; Horn, W. J.

1984-01-01

A composite wing extension was designed for a typical general aviation aircraft to improve lift curve slope, dihedral effect, and lift to drag ratio. Advanced composite materials were used in the design to evaluate their use as primary structural components in general aviation aircraft. Extensive wind tunnel tests were used to evaluate six extension shapes. The extension shape chosen as the best choice was 28 inches long with a total area of 17 square feet. Subsequent flight tests showed the wing extension's predicted aerodynamic improvements to be correct. The structural design of the wing extension consisted of a hybrid laminate carbon core with outer layers of Kevlar - layed up over a foam interior which acted as an internal support. The laminate skin of the wing extension was designed from strength requirements, and the foam core was included to prevent buckling. A joint lap was recommended to attach the wing extension to the main wing structure.

F-35 Joint Strike Fighter Aircraft (F-35)

DTIC Science & Technology

2015-12-01

Selected Acquisition Report ( SAR ) RCS: DD-A&T(Q&A)823-198 F-35 Joint Strike Fighter Aircraft (F-35) As of FY 2017 President’s Budget Defense...Acquisition Management Information Retrieval (DAMIR) March 21, 2016 08:47:09 UNCLASSIFIED F-35 December 2015 SAR March 21, 2016 08:47:09 UNCLASSIFIED 2...Document OSD - Office of the Secretary of Defense O&S - Operating and Support PAUC - Program Acquisition Unit Cost F-35 December 2015 SAR March 21

Notebook computer use on a desk, lap and lap support: effects on posture, performance and comfort.

PubMed

Asundi, Krishna; Odell, Dan; Luce, Adam; Dennerlein, Jack T

2010-01-01

This study quantified postures of users working on a notebook computer situated in their lap and tested the effect of using a device designed to increase the height of the notebook when placed on the lap. A motion analysis system measured head, neck and upper extremity postures of 15 adults as they worked on a notebook computer placed on a desk (DESK), the lap (LAP) and a commercially available lapdesk (LAPDESK). Compared with the DESK, the LAP increased downwards head tilt 6 degrees and wrist extension 8 degrees . Shoulder flexion and ulnar deviation decreased 13 degrees and 9 degrees , respectively. Compared with the LAP, the LAPDESK decreased downwards head tilt 4 degrees , neck flexion 2 degrees , and wrist extension 9 degrees. Users reported less discomfort and difficulty in the DESK configuration. Use of the lapdesk improved postures compared with the lap; however, all configurations resulted in high values of wrist extension, wrist deviation and downwards head tilt. STATEMENT OF RELEVANCE: This study quantifies postures of users working with a notebook computer in typical portable configurations. A better understanding of the postures assumed during notebook computer use can improve usage guidelines to reduce the risk of musculoskeletal injuries.

Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Data report

NASA Technical Reports Server (NTRS)

Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

1982-01-01

Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116 K (-250 F), 294 K (70 F) and 561 K (550 F). Joint parameters evaluated are lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Advanced joint concepts were examined to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. The material properties of the high temperature adhesive, designated A7F, used for bonding were established. The bonded joint tests resulted in interlaminar shear or peel failures of the composite and there were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

Dual-band infrared (DBIR) imaging inspections of Boeing 737 and KC-135 aircraft panels

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

Del Grande, N.K.; Dolan, K.W.; Durbin, P.F.

1993-08-27

We apply dual-band infrared (DBIR) imaging as a dynamic thermal tomography tool for wide area inspection of a Boeing 737 aircraft, and several Boeing KC-135 aircraft panels. Our analyses are discussed in this report. After flash-heating the aircraft skin, we record synchronized DBIR images every 40 ms, from onset to 8 seconds after the heat flash. We analyze selective DBIR image ratios which enhance surface temperature contrast and remove surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). The Boeing 737 and KC-135 aircraft fuselage panels have varying percent thickness lossesmore » from corrosion. We established the correlation of percent thickness loss with surface temperature rise (above ambient) for a partially corroded F-18 wing box structure and several aluminum reference panels. Based on this correlation, lap splice temperatures rise 1{degrees}C per 24 {plus_minus} 5 % material loss at 0.4 s after the heat flash. We show tables, charts and temperature maps of typical lap splice material losses for the riveted (and bonded) Boeing 737, and the riveted (but unbonded) Boeing KC-135. We map the fuselage composite thermal inertia, based on the (inverse) slope of the surface temperature versus inverse square root of time. Composite thermal inertia maps characterize shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Late time composite thermal inertia maps depict where corrosion-related thickness losses occur. Lap splice sites on a typical Boeing KC-135 panel with low composite thermal inertia values had high skin-thickness losses from corrosion.« less

Additive manufacturing of tools for lapping glass

NASA Astrophysics Data System (ADS)

Williams, Wesley B.

2013-09-01

Additive manufacturing technologies have the ability to directly produce parts with complex geometries without the need for secondary processes, tooling or fixtures. This ability was used to produce concave lapping tools with a VFlash 3D printer from 3D Systems. The lapping tools were first designed in Creo Parametric with a defined constant radius and radial groove pattern. The models were converted to stereolithography files which the VFlash used in building the parts, layer by layer, from a UV curable resin. The tools were rotated at 60 rpm and used with 120 grit and 220 grit silicon carbide lapping paste to lap 0.750" diameter fused silica workpieces. The samples developed a matte appearance on the lapped surface that started as a ring at the edge of the workpiece and expanded to the center. This indicated that as material was removed, the workpiece radius was beginning to match the tool radius. The workpieces were then cleaned and lapped on a second tool (with equivalent geometry) using a 3000 grit corundum aluminum oxide lapping paste, until a near specular surface was achieved. By using lapping tools that have been additively manufactured, fused silica workpieces can be lapped to approach a specified convex geometry. This approach may enable more rapid lapping of near net shape workpieces that minimize the material removal required by subsequent polishing. This research may also enable development of new lapping tool geometry and groove patterns for improved loose abrasive finishing.

NASA Boeing 737 Aircraft Test Results from 1996 Joint Winter Runway Friction Measurement Program

NASA Technical Reports Server (NTRS)

Yager, Thomas J.

1996-01-01

A description of the joint test program objectives and scope is given together with the performance capability of the NASA Langley B-737 instrumented aircraft. The B-737 test run matrix conducted during the first 8 months of this 5-year program is discussed with a description of the different runway conditions evaluated. Some preliminary test results are discussed concerning the Electronic Recording Decelerometer (ERD) readings and a comparison of B-737 aircraft braking performance for different winter runway conditions. Detailed aircraft parameter time history records, analysis of ground vehicle friction measurements and harmonization with aircraft braking performance, assessment of induced aircraft contaminant drag, and evaluation of the effects of other factors on aircraft/ground vehicle friction performance will be documented in a NASA Technical Report which is being prepared for publication next year.

Subsurface damage distribution in the lapping process.

PubMed

Wang, Zhuo; Wu, Yulie; Dai, Yifan; Li, Shengyi

2008-04-01

To systematically investigate the influence of lapping parameters on subsurface damage (SSD) depth and characterize the damage feature comprehensively, maximum depth and distribution of SSD generated in the optical lapping process were measured with the magnetorheological finishing wedge technique. Then, an interaction of adjacent indentations was applied to interpret the generation of maximum depth of SSD. Eventually, the lapping procedure based on the influence of lapping parameters on the material removal rate and SSD depth was proposed to improve the lapping efficiency.

Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

NASA Astrophysics Data System (ADS)

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-03-01

Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

Bond strength evaluation in adhesive joints using NDE and DIC methods

NASA Astrophysics Data System (ADS)

Poudel, Anish

Adhesive bonding of graphite epoxy composite laminates to itself or traditional metal alloys in modern aerospace and aircraft structural applications offers an excellent opportunity to use the most efficient and intelligent combination of materials available thus providing an attractive package for efficient structural designs. However, one of the major issues of adhesive bonding is the occasional formation of interfacial defects such as kissing or weak bonds in the bondline interface. Also, there are shortcomings of existing non-destructive evaluation (NDE) methods to non-destructively detect/characterize these interfacial defects and reliably predicting the bond shear strength. As a result, adhesive bonding technology is still not solely implemented in primary structures of an aircraft. Therefore, there is a greater demand for a novel NDE tool that can meet the existing aerospace requirement for adhesive bondline characterization. This research implemented a novel Acoustography ultrasonic imaging and digital image correlation (DIC) technique to detect and characterize interfacial defects in the bondline and determine bond shear strength in adhesively bonded composite-metal joints. Adhesively bonded Carbon Fiber Reinforced Plastic (CFRP) laminate and 2024-T3 Aluminum single lap shear panels subjected to various implanted kissing/weak bond defects were the primary focus of this study. Kissing/weak bonds were prepared by controlled surface contamination in the composite bonding surface and also by improperly mixing the adhesive constituent. SEM analyses were also conducted to understand the surface morphology of substrates and their interaction with the contaminants. Morphological changes were observed in the microscopic scale and the chemical analysis confirmed the stability of the contaminant at or very close to the interface. In addition, it was also demonstrated that contaminants migrated during the curing of the adhesive from CFRP substrate which caused a

Dogs lap using acceleration-driven open pumping

PubMed Central

Gart, Sean; Socha, John J.; Vlachos, Pavlos P.; Jung, Sunghwan

2015-01-01

Dogs lap because they have incomplete cheeks and cannot suck. When lapping, a dog’s tongue pulls a liquid column from the bath, suggesting that the hydrodynamics of column formation are critical to understanding how dogs drink. We measured lapping in 19 dogs and used the results to generate a physical model of the tongue’s interaction with the air–fluid interface. These experiments help to explain how dogs exploit the fluid dynamics of the generated column. The results demonstrate that effects of acceleration govern lapping frequency, which suggests that dogs curl the tongue to create a larger liquid column. Comparing lapping in dogs and cats reveals that, despite similar morphology, these carnivores lap in different physical regimes: an unsteady inertial regime for dogs and steady inertial regime for cats. PMID:26668382

Single crystal diamond lapping procedure

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

Grayson, R.A.

A facility capable of resharpening quality cutting edges on single crystal diamond cutting tools was needed as the demand in precision machining of special optical surfaces became a common occurrence here at Lawrence Livermore National Laboratory. A specially constructed lapping machine using an air bearing spindle was built to achieve the required edge quality. The basic design for this lap was taken out of a technical report by W.L. Duke and R.T. Lovell of Oak Ridge Y-12 Plant Union Carbide Corp. We have also purchased two commercially built lapping machines recommended to us by Mr. Cory A. Knottenbelt, formerly ofmore » R.C.A. Diamond Lapping Facility, in Indianapolis, Indiana, now doing state-of-the-art polishing and relapping at LLNL facilities.« less

Probing Emissions of Military Cargo Aircraft: Description of a Joint Field Measurement Program

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

Cheng, Mengdawn; Corporan, E.; DeWitt, M.

2008-01-01

Direct emissions of NOx, volatile organic compounds, and particulate matter (PM) by aircraft contribute to the pollutant levels found in the atmosphere. Aircraft emissions can be injected at the ground level or directly at the high altitude in flight. Conversion of the precursor gases into secondary PM is one of the pathways for the increased atmospheric PM. Atmospheric PM interacts with solar radiation altering atmospheric radiation balance and potentially contributing to global and regional climate changes. Also, direct emissions of air toxics, ozone precursors and PM from aircraft in and around civilian airports and military air bases can worsen localmore » air quality in non-attainment and/or maintenance areas. These emissions need to be quantified. However, the current EPA methods for particle emission measurements from such sources, modified Method 5 and Conditional Test Method 039, are gravimetric-based, and it is anticipated that these methods will not be suitable for current and future generations of aircraft turbine engines, whose particle mass emissions are low. To evaluate measurement approaches for military aircraft emissions, two complementary projects were initiated in 2005. A joint field campaign between these two programs was executed during the first week of October 2005 at the Kentucky Air National Guard (KYANG) base in Louisville, KY. This campaign represented the first in a series of field studies for each program funded by the DoD Strategic Environmental Research and Development Program (SERDP) and provided the basis for cross-comparison of the sampling approaches and measurement techniques employed by the respective program teams. This paper describes the overall programmatic of the multi-year SERDP aircraft emissions research and presents a summary of the results from the joint field campaign.« less

An overview of the joint FAA/NASA aircraft/ground runway friction program

NASA Technical Reports Server (NTRS)

Yager, Thomas J.

1989-01-01

There is a need for information on runways which may become slippery due to various forms and types of contaminants. Experience has shown that since the beginning of all weather aircraft operations, there have been landing and aborted takeoff incidents and/or accidents each year where aircraft have either run off the end or veered off the shoulder of low friction runways. NASA Langley's Landing and Impact Dynamics Branch is involved in several research programs directed towards obtaining a better understanding of how different tire properties interact with varying pavement surface characteristics to produce acceptable performance for aircraft ground handling requirements. One such effort, which was jointly supported by not only NASA and the FAA but by several aviation industry groups including the Flight Safety Foundation, is described.

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Skoumal, D. E.

1980-01-01

Bonded and bolted designs are presented for each of four major attachment types. Prepreg processing problems are discussed and quality control data are given for lots 2W4604, 2W4632 and 2W4643. Preliminary design allowables test results for tension tests and compression tests of laminates are included. The final small specimen test matrix is defined and the configuration of symmetric step-lap joint specimens are shown. Finite element modeling studies of a double lap joint were performed to evaluate the number of elements required through the adhesive thickness to assess effects of various joint parameters on stress distributions. Results of finite element analyses assessing the effect of an adhesive fillet on the stress distribution in a double lap joint are examined.

Listeria monocytogenes uses Listeria adhesion protein (LAP) to promote bacterial transepithelial translocation and induces expression of LAP receptor Hsp60.

PubMed

Burkholder, Kristin M; Bhunia, Arun K

2010-12-01

Listeria monocytogenes interaction with the intestinal epithelium is a key step in the infection process. We demonstrated that Listeria adhesion protein (LAP) promotes adhesion to intestinal epithelial cells and facilitates extraintestinal dissemination in vivo. The LAP receptor is a stress response protein, Hsp60, but the precise role for the LAP-Hsp60 interaction during Listeria infection is unknown. Here we investigated the influence of physiological stressors and Listeria infection on host Hsp60 expression and LAP-mediated bacterial adhesion, invasion, and transepithelial translocation in an enterocyte-like Caco-2 cell model. Stressors such as heat (41°C), tumor necrosis factor alpha (TNF-α) (100 U), and L. monocytogenes infection (10(4) to 10(6) CFU/ml) significantly (P < 0.05) increased plasma membrane and intracellular Hsp60 levels in Caco-2 cells and consequently enhanced LAP-mediated L. monocytogenes adhesion but not invasion of Caco-2 cells. In transepithelial translocation experiments, the wild type (WT) exhibited 2.7-fold more translocation through Caco-2 monolayers than a lap mutant, suggesting that LAP is involved in transepithelial translocation, potentially via a paracellular route. Short hairpin RNA (shRNA) suppression of Hsp60 in Caco-2 cells reduced WT adhesion and translocation 4.5- and 3-fold, respectively, while adhesion remained unchanged for the lap mutant. Conversely, overexpression of Hsp60 in Caco-2 cells enhanced WT adhesion and transepithelial translocation, but not those of the lap mutant. Furthermore, initial infection with a low dosage (10(6) CFU/ml) of L. monocytogenes increased plasma membrane and intracellular expression of Hsp60 significantly, which rendered Caco-2 cells more susceptible to subsequent LAP-mediated adhesion and translocation. These data provide insight into the role of LAP as a virulence factor during intestinal epithelial infection and pose new questions regarding the dynamics between the host stress response

Adhesive properties and adhesive joints strength of graphite/epoxy composites

NASA Astrophysics Data System (ADS)

Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

2017-05-01

The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

A Model for a Single Unmanned Aircraft Systems (UAS) Program Office Managing Joint ISR Capabilities

DTIC Science & Technology

2017-10-01

reduction in manning from the multiple program office structure to the new single program management model. Additional information regarding this...OFFICE MANAGING JOINT ISR CAPABILITIES by Angela E. Burris A Research Report Submitted to the Faculty In Partial Fulfillment of...research paper is to answer how a single management office could provide greater agility for unmanned aircraft systems (UAS); supporting Joint concepts

Full-Scale Testing and Analysis of Curved Aircraft Fuselage Panels.

DOT National Transportation Integrated Search

1993-12-01

The report presents data on (1) residual strength of aircraft panels containing Multiple-Site Damage (MSD) in lap splices, and (2) fatigue strength of panels subjected to cyclic pressure loading. The testing was conducted using the dedicated Aging Ai...

Pressure variation of developed lapping tool on surface roughness

NASA Astrophysics Data System (ADS)

Hussain, A. K.; Lee, K. Q.; Aung, L. M.; Abu, A.; Tan, L. K.; Kang, H. S.

2018-01-01

Improving the surface roughness is always one of the major concerns in the development of lapping process as high precision machining caters a great demand in manufacturing process. This paper aims to investigate the performance of a newly designed lapping tool in term of surface roughness. Polypropylene is used as the lapping tool head. The lapping tool is tested for different pressure to identify the optimum working pressure for lapping process. The theoretical surface roughness is also calculated using Vickers Hardness. The present study shows that polypropylene is able to produce good quality and smooth surface roughness. The optimum lapping pressure in the present study is found to be 45 MPa. By comparing the theoretical and experimental values, the present study shows that the newly designed lapping tool is capable to produce finer surface roughness.

The pressure control technology of the active stressed lap

NASA Astrophysics Data System (ADS)

Li, Ying; Wang, Daxing

2010-10-01

The active stressed lap polishing technology is a kind of new polishing technology that can actively deform the lap surface to become an off-axis asphere according to different lap position on mirror surface and different angle of lap. The pressure of the lap on the mirror is an important factor affecting the grinding efficiency of the optics mirror. The active stressed lap technology using dynamic pressure control solution in the process of polishing astronomical Aspheric Mirror with faster asphericity will provide the advantage like high polishing speed and natural smooth, etc. This article puts emphases on the pressure control technology of the active stressed lap technology. It requires that the active stressed lap keeps symmetrical vertical compression on the mirrors in the process of grinding mirrors. With a background of an active stressed lap 450mm in diameter, this article gives an outline of the pressure control organization, analyzes the principle of pressure control and proposes the limitations of the present pressure control organization and the relevant solutions, designs a digital pressure controller with C32-bit RISC embedded and gives the relevant experimental test result finally.

A Semi-Analytical Method for Determining the Energy Release Rate of Cracks in Adhesively-Bonded Single-Lap Composite Joints

NASA Technical Reports Server (NTRS)

Yang, Charles; Sun, Wenjun; Tomblin, John S.; Smeltzer, Stanley S., III

2007-01-01

A semi-analytical method for determining the strain energy release rate due to a prescribed interface crack in an adhesively-bonded, single-lap composite joint subjected to axial tension is presented. The field equations in terms of displacements within the joint are formulated by using first-order shear deformable, laminated plate theory together with kinematic relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. Based on the adhesive stress distributions, the forces at the crack tip are obtained and the strain energy release rate of the crack is determined by using the virtual crack closure technique (VCCT). Additionally, the test specimen geometry from both the ASTM D3165 and D1002 test standards are utilized during the derivation of the field equations in order to correlate analytical models with future test results. The system of second-order differential field equations is solved to provide the adherend and adhesive stress response using the symbolic computation tool, Maple 9. Finite element analyses using J-integral as well as VCCT were performed to verify the developed analytical model. The finite element analyses were conducted using the commercial finite element analysis software ABAQUS. The results determined using the analytical method correlated well with the results from the finite element analyses.

Structural Features of the Pseudomonas fluorescens Biofilm Adhesin LapA Required for LapG-Dependent Cleavage, Biofilm Formation, and Cell Surface Localization

PubMed Central

Boyd, Chelsea D.; Smith, T. Jarrod; El-Kirat-Chatel, Sofiane; Newell, Peter D.; Dufrêne, Yves F.

2014-01-01

The localization of the LapA protein to the cell surface is a key step required by Pseudomonas fluorescens Pf0-1 to irreversibly attach to a surface and form a biofilm. LapA is a member of a diverse family of predicted bacterial adhesins, and although lacking a high degree of sequence similarity, family members do share common predicted domains. Here, using mutational analysis, we determine the significance of each domain feature of LapA in relation to its export and localization to the cell surface and function in biofilm formation. Our previous work showed that the N terminus of LapA is required for cleavage by the periplasmic cysteine protease LapG and release of the adhesin from the cell surface under conditions unfavorable for biofilm formation. We define an additional critical region of the N terminus of LapA required for LapG proteolysis. Furthermore, our results suggest that the domains within the C terminus of LapA are not absolutely required for biofilm formation, export, or localization to the cell surface, with the exception of the type I secretion signal, which is required for LapA export and cell surface localization. In contrast, deletion of the central repetitive region of LapA, consisting of 37 repeats of 100 amino acids, results in an inability to form a biofilm. We also used single-molecule atomic force microscopy to further characterize the role of these domains in biofilm formation on hydrophobic and hydrophilic surfaces. These studies represent the first detailed analysis of the domains of the LapA family of biofilm adhesin proteins. PMID:24837291

Time-temperature effect in adhesively bonded joints

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.

1981-01-01

The viscoelastic analysis of an adhesively bonded lap joint was reconsidered. The adherends are approximated by essentially Reissner plates and the adhesive is linearly viscoelastic. The hereditary integrals are used to model the adhesive. A linear integral differential equations system for the shear and the tensile stress in the adhesive is applied. The equations have constant coefficients and are solved by using Laplace transforms. It is shown that if the temperature variation in time can be approximated by a piecewise constant function, then the method of Laplace transforms can be used to solve the problem. A numerical example is given for a single lap joint under various loading conditions.

Expression of Surface Protein LapB by a Wide Spectrum of Listeria monocytogenes Serotypes as Demonstrated with Anti-LapB Monoclonal Antibodies

PubMed Central

Boivin, Teela; Elmgren, Cathie; Brooks, Brian W.; Huang, Hongsheng; Pagotto, Franco

2016-01-01

ABSTRACT Protein antigens expressed on the surface of all strains of Listeria monocytogenes and absent from nonpathogenic Listeria spp. are presumably useful targets for pathogen identification, detection, and isolation using specific antibodies (Abs). To seek such surface proteins expressed in various strains of L. monocytogenes for diagnostic applications, we focused on a set of surface proteins known to be involved or putatively involved in L. monocytogenes virulence and identified Listeria adhesion protein B (LapB) as a candidate based on the bioinformatics analysis of whole-genome sequences showing that the gene coding for LapB was present in L. monocytogenes strains and absent from strains of other Listeria spp. Immunofluorescence microscopy (IFM), performed with rabbit polyclonal antibodies against the recombinant LapB protein (rLapB) of L. monocytogenes serotype 4b strain L10521, confirmed expression of LapB on the surface. A panel of 48 mouse monoclonal antibodies (MAbs) to rLaB was generated, and 7 of them bound strongly to the surface of L. monocytogenes cells as demonstrated using IFM. Further characterization of these 7 anti-LapB MAbs, using an enzyme-linked immunosorbent assay (ELISA), revealed that 6 anti-LapB MAbs (M3484, M3495, M3500, M3509, M3517, and M3519) reacted strongly with 46 (86.8%) of 53 strains representing 10 of the 12 serotypes tested (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4ab, 4b, 4d, and 4e). These results indicate that LapB, together with companion anti-LapB MAbs, can be targeted as a biomarker for the detection and isolation of various L. monocytogenes strains from contaminated foods. IMPORTANCE Strains of L. monocytogenes are traditionally grouped into serotypes. Identification of a surface protein expressed in all or the majority of at least 12 serotypes would aid in the development of surface-binding monoclonal antibodies (MAbs) for detection and isolation of L. monocytogenes from foods. Bioinformatics analysis revealed that the gene

Expression of Surface Protein LapB by a Wide Spectrum of Listeria monocytogenes Serotypes as Demonstrated with Anti-LapB Monoclonal Antibodies.

PubMed

Boivin, Teela; Elmgren, Cathie; Brooks, Brian W; Huang, Hongsheng; Pagotto, Franco; Lin, Min

2016-11-15

Protein antigens expressed on the surface of all strains of Listeria monocytogenes and absent from nonpathogenic Listeria spp. are presumably useful targets for pathogen identification, detection, and isolation using specific antibodies (Abs). To seek such surface proteins expressed in various strains of L. monocytogenes for diagnostic applications, we focused on a set of surface proteins known to be involved or putatively involved in L. monocytogenes virulence and identified Listeria adhesion protein B (LapB) as a candidate based on the bioinformatics analysis of whole-genome sequences showing that the gene coding for LapB was present in L. monocytogenes strains and absent from strains of other Listeria spp. Immunofluorescence microscopy (IFM), performed with rabbit polyclonal antibodies against the recombinant LapB protein (rLapB) of L. monocytogenes serotype 4b strain L10521, confirmed expression of LapB on the surface. A panel of 48 mouse monoclonal antibodies (MAbs) to rLaB was generated, and 7 of them bound strongly to the surface of L. monocytogenes cells as demonstrated using IFM. Further characterization of these 7 anti-LapB MAbs, using an enzyme-linked immunosorbent assay (ELISA), revealed that 6 anti-LapB MAbs (M3484, M3495, M3500, M3509, M3517, and M3519) reacted strongly with 46 (86.8%) of 53 strains representing 10 of the 12 serotypes tested (1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4ab, 4b, 4d, and 4e). These results indicate that LapB, together with companion anti-LapB MAbs, can be targeted as a biomarker for the detection and isolation of various L. monocytogenes strains from contaminated foods. Strains of L. monocytogenes are traditionally grouped into serotypes. Identification of a surface protein expressed in all or the majority of at least 12 serotypes would aid in the development of surface-binding monoclonal antibodies (MAbs) for detection and isolation of L. monocytogenes from foods. Bioinformatics analysis revealed that the gene coding for Listeria

C/EBPβ-LAP*/LAP Expression Is Mediated by RSK/eIF4B-Dependent Signalling and Boosted by Increased Protein Stability in Models of Monocytic Differentiation

PubMed Central

Christmann, Martin; Friesenhagen, Judith; Westphal, Andreas; Pietsch, Daniel; Brand, Korbinian

2015-01-01

The transcription factor C/EBPβ plays a key role in monocytic differentiation and inflammation. Its small isoform LIP is associated with proliferation at early premonocytic developmental stages and regulated via mTOR-dependent signalling. During later stages of (pre)monocytic differentiation there is a considerable increase in the large C/EBPβ isoforms LAP*/LAP which inhibit proliferation thus supporting terminal differentiation. Here, we showed in different models of monocytic differentiation that this dramatic increase in the LAP*/LAP protein and LAP/LIP ratio was accompanied by an only modest/retarded mRNA increase suggesting an important role for (post)translational mechanisms. We found that LAP*/LAP formation was induced via MEK/RSK-dependent cascades, whereas mTOR/S6K1 were not involved. Remarkably, LAP*/LAP expression was dependent on phosphorylated eIF4B, an acceleratory protein of RNA helicase eIF4A. PKR inhibition reduced the expression of eIF4B and C/EBPβ in an eIF2α-independent manner. Furthermore, under our conditions a marked stabilisation of LAP*/LAP protein occurred, accompanied by reduced chymotrypsin-like proteasome/calpain activities and increased calpastatin levels. Our study elucidates new signalling pathways inducing LAP*/LAP expression and indicates new alternative PKR functions in monocytes. The switch from mTOR- to RSK-mediated signalling to orchestrate eIF4B-dependent LAP*/LAP translation, accompanied by increased protein stability but only small mRNA changes, may be a prototypical example for the regulation of protein expression during selected processes of differentiation/proliferation. PMID:26646662

Dual resin bonded joints in polyetheretherketone (PEEK) matrix composites

NASA Astrophysics Data System (ADS)

Zelenak, Steve; Radford, Donald W.; Dean, Michael W.

1993-04-01

The paper describes applications of the dual resin (miscible polymer) bonding technique (Smiley, 1989) developed as an alternative to traditional bonding approaches to joining thermoplastic matrix composite subassemblies into structures. In the experiments, the performance of joint geometries, such as those that could be used to assemble large truss structures in space, are investigated using truss joint models consisting of woven carbon fiber/PEEK tubes of about 1 mm wall thickness. Specific process conditions and hand-held hardware used to apply heat and pressure were chosen to simulate a field asembly technique. Results are presented on tube/cruciform double lap shear tests, pinned-pinned tube compression tests, and single lap shear bond tests of joints obtained using the dual resin bonding technique.

Dual-band infrared imaging for quantitative corrosion detection in aging aircraft

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

Del Grande, N.K.

1993-12-31

Aircraft skin thickness-loss from corrosion has been measured using dual-band infrared (DBIR) imaging on a flash-heated Boeing 737 fuselage structure. The authors mapped surface temperature differences of 0.2 to 0.6 C for 5 to 14 % thickness losses within corroded lap splices at 0.4 seconds after the heat flash. The procedure mapped surface temperature differences at sites without surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). They established the correlation of percent thickness loss with surface temperature rise using a partially corroded F-18 wing box and several aluminum panels whichmore » had thickness losses from milled flat-bottom holes. The authors mapped the lap splice composite thermal inertia, (k{rho}c){sup 1/2}, which characterized shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Corrosion invaded the inside of the Boeing 737 lap splice, beneath the galley and the latrine, where they observed ``pillowing`` from volume build-up of corrosion by-products.« less

Dual-band infrared imaging for quantitative corrosion detection in aging aircraft

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

Del Grande, N.K.

1993-11-01

Aircraft skin thickness-loss from corrosion has been measured using dual-band infrared (DBIR) imaging on a flash-heated Boeing 737 fuselage structure. We mapped surface temperature differences of 0.2 to 0.6 {degrees}C for 5 to 14% thickness losses within corroded lap splices at 0.4 seconds after the heat flash. Our procedure mapped surface temperature differences at sites without surface-emissivity clutter (from dirt, dents, tape, markings, ink, sealants, uneven paint, paint stripper, exposed metal and roughness variations). We established the correlation of percent thickness loss with surface temperature rise using a partially corroded F-18 wing box and several aluminum panels which had thicknessmore » losses from milled flat-bottom holes. We mapped the lap splice composite thermal inertia, (kpc){sup {1/2}}, which characterized shallow skin defects within the lap splice at early times (<0.3 s) and deeper skin defects within the lap splice at late times (>0.4 s). Corrosion invaded the inside of the Boeing 737 lap splice, beneath the galley and the latrine, where we observed ``pillowing`` from volume build-up of corrosion by-products.« less

Laparoscopic Skills Are Improved With LapMentor™ Training

PubMed Central

Andreatta, Pamela B.; Woodrum, Derek T.; Birkmeyer, John D.; Yellamanchilli, Rajani K.; Doherty, Gerard M.; Gauger, Paul G.; Minter, Rebecca M.

2006-01-01

Objective: To determine if prior training on the LapMentor™ laparoscopic simulator leads to improved performance of basic laparoscopic skills in the animate operating room environment. Summary Background Data: Numerous influences have led to the development of computer-aided laparoscopic simulators: a need for greater efficiency in training, the unique and complex nature of laparoscopic surgery, and the increasing demand that surgeons demonstrate competence before proceeding to the operating room. The LapMentor™ simulator is expensive, however, and its use must be validated and justified prior to implementation into surgical training programs. Methods: Nineteen surgical interns were randomized to training on the LapMentor™ laparoscopic simulator (n = 10) or to a control group (no simulator training, n = 9). Subjects randomized to the LapMentor™ trained to expert criterion levels 2 consecutive times on 6 designated basic skills modules. All subjects then completed a series of laparoscopic exercises in a live porcine model, and performance was assessed independently by 2 blinded reviewers. Time, accuracy rates, and global assessments of performance were recorded with an interrater reliability between reviewers of 0.99. Results: LapMentor™ trained interns completed the 30° camera navigation exercise in significantly less time than control interns (166 ± 52 vs. 220 ± 39 seconds, P < 0.05); they also achieved higher accuracy rates in identifying the required objects with the laparoscope (96% ± 8% vs. 82% ± 15%, P < 0.05). Similarly, on the two-handed object transfer exercise, task completion time for LapMentor™ trained versus control interns was 130 ± 23 versus 184 ± 43 seconds (P < 0.01) with an accuracy rate of 98% ± 5% versus 80% ± 13% (P < 0.001). Additionally, LapMentor™ trained interns outperformed control subjects with regard to camera navigation skills, efficiency of motion, optimal instrument handling, perceptual ability, and performance

Numerical and Experimental Characterization of a Composite Secondary Bonded Adhesive Lap Joint Using the Ultrasonics method

NASA Astrophysics Data System (ADS)

Kumar, M. R.; Ghosh, A.; Karuppannan, D.

2018-05-01

The construction of aircraft using advanced composites have become very popular during the past two decades, in which many innovative manufacturing processes, such as cocuring, cobonding, and secondary bonding processes, have been adopted. The secondary bonding process has become less popular than the other two ones because of nonavailability of process database and certification issues. In this article, an attempt is made to classify the quality of bonding using nondestructive ultrasonic inspection methods. Specimens were prepared and tested using the nondestructive ultrasonic Through Transmission (TT), Pulse Echo (PE), and air coupled guided wave techniques. It is concluded that the ultrasonic pulse echo technique is the best one for inspecting composite secondary bonded adhesive joints.

Geometrically nonlinear analysis of adhesively bonded joints

NASA Technical Reports Server (NTRS)

Dattaguru, B.; Everett, R. A., Jr.; Whitcomb, J. D.; Johnson, W. S.

1982-01-01

A geometrically nonlinear finite element analysis of cohesive failure in typical joints is presented. Cracked-lap-shear joints were chosen for analysis. Results obtained from linear and nonlinear analysis show that nonlinear effects, due to large rotations, significantly affect the calculated mode 1, crack opening, and mode 2, inplane shear, strain-energy-release rates. The ratio of the mode 1 to mode 2 strain-energy-relase rates (G1/G2) was found to be strongly affected by he adhesive modulus and the adherend thickness. The ratios between 0.2 and 0.8 can be obtained by varying adherend thickness and using either a single or double cracked-lap-shear specimen configuration. Debond growth rate data, together with the analysis, indicate that mode 1 strain-energy-release rate governs debond growth. Results from the present analysis agree well with experimentally measured joint opening displacements.

Debonding of Stitched Composite Joints: Testing and Analysis

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and analytical study. The experimental study was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation ofthe debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The strain energy release rates at the debond front were calculated using a finite element-based technique. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches effectively reduced mode I to zero, but had less of an effect on modes II and III.

Double fillet lap of laser welding of thin sheet AZ31B Mg alloy

NASA Astrophysics Data System (ADS)

Ishak, Mahadzir; Salleh, M. N. M.

2018-05-01

In this paper, we describe the experimental laser welding of thin sheet AZ31B using double fillet lap joint method. Laser welding is capable of producing high quality weld seams especially for small weld bead on thin sheet product. In this experiment, both edges for upper and lower sheets were subjected to the laser beam from the pulse wave (PW) mode of fiber laser. Welded sample were tested their joint strength by tensile-shear strength method and the fracture loads were studied. Strength for all welded samples were investigated and the effect of laser parameters on the joint strength and appearances were studied. Pulsed energy (EP) from laser process give higher effect on joint strength compared to the welding speed (WS) and angle of irradiation (AOI). Highest joint strength was possessed by sample with high EP with the same value of WS and AOI. The strength was low due to the crack defect at the centre of weld region.

Deformation measurement for a rotating deformable lap based on inverse fringe projection

NASA Astrophysics Data System (ADS)

Liao, Min; Zhang, Qican

2015-03-01

The active deformable lap (also namely stressed lap) is an efficient polishing tool in optical manufacturing. To measure the dynamic deformation caused by outside force on a deformable lap is important and helpful to the opticians to ensure the performance of a deformable lap as expected. In this paper, a manual deformable lap was designed to simulate the dynamic deformation of an active stressed lap, and a measurement system was developed based on inverse projected fringe technique to restore the 3D shape. A redesigned inverse fringe has been projected onto the surface of the measured lap, and the deformations of the tested lap become much obvious and can be easily and quickly evaluated by Fourier fringe analysis. Compared with the conventional projection, this technique is more obvious, and it should be a promising one in the deformation measurement of the active stressed lap in optical manufacturing.

Flying qualities and control system characteristics for superaugmented aircraft

NASA Technical Reports Server (NTRS)

Myers, T. T.; Mcruer, D. T.; Johnston, D. E.

1984-01-01

Aircraft-alone dynamics and superaugmented control system fundamental regulatory properties including stability and regulatory responses of the basic closed-loop systems; fundamental high and low frequency margins and governing factors; and sensitivity to aircraft and controller parameters are addressed. Alternative FCS mechanizations, and mechanizational side effects are also discussed. An overview of flying qualities considerations encompasses general pilot operations as a controller in unattended, intermittent and trim, and full-attention regulatory or command control; effective vehicle primary and secondary response properties to pilot inputs and disturbances; pilot control architectural possibilities; and comparison of superaugmented and conventional aircraft path responses for different forms of pilot control. Results of a simple experimental investigation into pilot dynamic behavior in attitude control of superaugmented aircraft configurations with high frequency time laps and time delays are presented.

A lapping apparatus for hard tissue sections.

PubMed

Malcolm, A S

1975-02-01

A Lapping Apparatus is described which enables sections both embedded and unembedded to be ground plano parallel within +/- 1 micron. Sections cemented to steel subplates are retained by a magnetic holder which simplifies loading and unloading. Good surface and edge finish can be obtained and only short lapping times are required.

Study on the Strength of GFRP/Stainless Steel Adhesive Joints Reinforced with Glass Mat

NASA Astrophysics Data System (ADS)

Iwasa, Masaaki

The adhesive strengths of glass fiber reinforced plastics/metal adhesive joints reinforced with glass mat under tensile shear loads and tensile loads were investigated analytically and experimentally. First, the stress singularity parameters of the bonding edges were analyzed by FEM for various types of adhesive joints reinforced with glass mat. The shear stress and normal stress distributions near the bonding edge can be expressed by two stress singularity parameters. Second, tensile shear tests were performed on taper lap joint and taper lap joint reinforced with glass mat and tensile tests were performed on T-type adhesive joint and T-type adhesive joint reinforced with glass mat. The relationships between the loads and the crosshead displacements were measured. We concluded that reinforcing adhesive joints has a greater effect on strength under tensile load than under tensile shear load. The adhesive joints strength reinforced with glass mat can be evaluated by using stress singularity parameters.

Lap-Dissolve Slides

ERIC Educational Resources Information Center

Fine, Leonard W.; And Others

1977-01-01

Discusses the use of lap-dissolve projection to give students pre-laboratory instruction on an upcoming experiment. In this technique, two slide projectors are operated alternately so that one visual image fades away while the next appears on the same screen area. (MLH)

Critical Joints in Large Composite Primary Aircraft Structures. Volume 3: Ancillary Test Results

NASA Technical Reports Server (NTRS)

Bunin, Bruce L.; Sagui, R. L.

1985-01-01

A program was conducted to develop the technology for critical structural joints for composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of a comprehensive ancillary test program are summarized, consisting of single-bolt composite joint specimens tested in a variety of configurations. These tests were conducted to characterize the strength and load deflection properties that are required for multirow joint analysis. The composite material was Toray 300 fiber and Ciba-Geigy 914 resin, in the form of 0.005 and 0.01 inch thick unidirectional tape. Tests were conducted in single and double shear for loaded and unloaded hole configurations under both tensile and compressive loading. Two different layup patterns were examined. All tests were conducted at room temperature. In addition, the results of NASA Standard Toughness Test (NASA RP 1092) are reported, which were conducted for several material systems.

Analysis Concerning the Inspection Threshold for Multi-Site Damage.

DOT National Transportation Integrated Search

1993-12-01

Periodic inspections, at a prescribed interval, for Multi-Site Damage (MS) in longitudinal fuselage lap-joints start when the aircraft has accumulated a certain number of flights, the inspection threshold. The work reported here was an attempt to obt...

Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

DOE PAGES

Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; ...

2014-12-30

We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

Auto Mechanics I. Learning Activity Packets (LAPs). Section D--Suspension.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This document contains six learning activity packets (LAPs) that outline the study activities for the "suspension" instructional area for an Auto Mechanics I course. The six LAPs cover the following topics: wheel bearings, tires and wheels, wheel balancing, suspension system, steering system, and wheel alignment. Each LAP contains a…

Mutation in TOR1AIP1 encoding LAP1B in a form of muscular dystrophy: a novel gene related to nuclear envelopathies.

PubMed

Kayman-Kurekci, Gulsum; Talim, Beril; Korkusuz, Petek; Sayar, Nilufer; Sarioglu, Turkan; Oncel, Ibrahim; Sharafi, Parisa; Gundesli, Hulya; Balci-Hayta, Burcu; Purali, Nuhan; Serdaroglu-Oflazer, Piraye; Topaloglu, Haluk; Dincer, Pervin

2014-07-01

We performed genome-wide homozygosity mapping and mapped a novel myopathic phenotype to chromosomal region 1q25 in a consanguineous family with three affected individuals manifesting proximal and distal weakness and atrophy, rigid spine and contractures of the proximal and distal interphalangeal hand joints. Additionally, cardiomyopathy and respiratory involvement were noted. DNA sequencing of torsinA-interacting protein 1 (TOR1AIP1) gene encoding lamina-associated polypeptide 1B (LAP1B), showed a homozygous c.186delG mutation that causes a frameshift resulting in a premature stop codon (p.E62fsTer25). We observed that expression of LAP1B was absent in the patient skeletal muscle fibres. Ultrastructural examination showed intact sarcomeric organization but alterations of the nuclear envelope including nuclear fragmentation, chromatin bleb formation and naked chromatin. LAP1B is a type-2 integral membrane protein localized in the inner nuclear membrane that binds to both A- and B-type lamins, and is involved in the regulation of torsinA ATPase. Interestingly, luminal domain-like LAP1 (LULL1)-an endoplasmic reticulum-localized partner of torsinA-was overexpressed in the patient's muscle in the absence of LAP1B. Therefore, the findings suggest that LAP1 and LULL1 might have a compensatory effect on each other. This study expands the spectrum of genes associated with nuclear envelopathies and highlights the critical function for LAP1B in striated muscle. Copyright © 2014 Elsevier B.V. All rights reserved.

Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

1988-01-01

Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions.

Auto Mechanics I. Learning Activity Packets (LAPs). Section C--Engine.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This document contains five learning activity packets (LAPs) that outline the study activities for the "engine" instructional area for an Auto Mechanics I course. The five LAPs cover the following topics: basic engine principles, cooling system, engine lubrication system, exhaust system, and fuel system. Each LAP contains a cover sheet…

New design deforming controlling system of the active stressed lap

NASA Astrophysics Data System (ADS)

Ying, Li; Wang, Daxing

2008-07-01

A 450mm diameter active stressed lap has been developed in NIAOT by 2003. We design a new lap in 2007. This paper puts on emphases on introducing the new deforming control system of the lap. Aiming at the control characteristic of the lap, a new kind of digital deforming controller is designed. The controller consists of 3 parts: computer signal disposing, motor driving and force sensor signal disposing. Intelligent numeral PID method is applied in the controller instead of traditional PID. In the end, the result of new deformation are given.

[Sample German LAPS.

ERIC Educational Resources Information Center

Rosenthal, Bianca

Four learning activity packages (LAPS) for use in secondary school German programs contain instructional materials which enable students to improve their basic linguistic skills. The units include: (1) "Grusse," (2) "Ich Heisse...Namen," (3) "Tune into Your Career: Business Correspondence 'Auf Deutch'," and (4) "Understanding German Culture."…

Assembly of Lipopolysaccharide in Escherichia coli Requires the Essential LapB Heat Shock Protein*

PubMed Central

Klein, Gracjana; Kobylak, Natalia; Lindner, Buko; Stupak, Anna; Raina, Satish

2014-01-01

Here, we describe two new heat shock proteins involved in the assembly of LPS in Escherichia coli, LapA and LapB (lipopolysaccharide assembly protein A and B). lapB mutants were identified based on an increased envelope stress response. Envelope stress-responsive pathways control key steps in LPS biogenesis and respond to defects in the LPS assembly. Accordingly, the LPS content in ΔlapB or Δ(lapA lapB) mutants was elevated, with an enrichment of LPS derivatives with truncations in the core region, some of which were pentaacylated and exhibited carbon chain polymorphism. Further, the levels of LpxC, the enzyme that catalyzes the first committed step of lipid A synthesis, were highly elevated in the Δ(lapA lapB) mutant. Δ(lapA lapB) mutant accumulated extragenic suppressors that mapped either to lpxC, waaC, and gmhA, or to the waaQ operon (LPS biosynthesis) and lpp (Braun's lipoprotein). Increased synthesis of either FabZ (3-R-hydroxymyristoyl acyl carrier protein dehydratase), slrA (novel RpoE-regulated non-coding sRNA), lipoprotein YceK, toxin HicA, or MurA (UDP-N-acetylglucosamine 1-carboxyvinyltransferase) suppressed some of the Δ(lapA lapB) defects. LapB contains six tetratricopeptide repeats and, at the C-terminal end, a rubredoxin-like domain that was found to be essential for its activity. In pull-down experiments, LapA and LapB co-purified with LPS, Lpt proteins, FtsH (protease), DnaK, and DnaJ (chaperones). A specific interaction was also observed between WaaC and LapB. Our data suggest that LapB coordinates assembly of proteins involved in LPS synthesis at the plasma membrane and regulates turnover of LpxC, thereby ensuring balanced biosynthesis of LPS and phospholipids consistent with its essentiality. PMID:24722986

Cruise noise of the 2/9 scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

NASA Technical Reports Server (NTRS)

Dittmar, James H.; Stang, David B.

1987-01-01

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak.

Double-Lap Shear Test For Honeycomb Core

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Hodge, Andrew J.

1992-01-01

Double-lap test measures shear strength of panel made of honeycomb core with 8-ply carbon-fiber/epoxy face sheets. Developed to overcome three principal disadvantages of prior standard single-lap shear test: specimen had to be more than 17 in. long; metal face sheets had to be used; and test introduced torque, with consequent bending and peeling of face sheets and spurious tensile or compressive loading of honeycomb.

Dynamic deformation measurement and analysis of active stressed lap using optical method

NASA Astrophysics Data System (ADS)

Zhang, Qican; Su, Xianyu; Liu, Yuankun; Xiang, Liqun

2007-12-01

The active stressed lap is the heart of polishing process. A novel non-contact optical method of dynamic deformation measurement and analysis of an active stressed lap is put forward. This method, based on structured illumination, is able to record full-field information of the bending and rotating stressed lap dynamically and continuously, while its profile is changed under computer control, and restore the whole process of lap deformation varied with time at different position and rotating angle. It has been verified by experiments that this proposed method will be helpful to the opticians to ensure the stressed lap as expected.

Delamination and Stitched Failure in Stitched Composite Joints

NASA Technical Reports Server (NTRS)

Glaessgen, E. H.; Raju, I. S.; Poe, C. C., Jr.

1999-01-01

The effect of stitches on the failure of a single lap joint configuration was determined in a combined experimental and finite element study. The experimental program was conducted to determine debond growth under static monotonic loading. The stitches were shown to delay the initiation of the debond and provide load transfer beyond the load necessary to completely debond the stitched lap joint. The experimentally determined debond length vs. applied load was used as an input parameter in the finite element analysis of both configurations. The strain energy release rates at the debond from were calculated using plate finite elements. Nonlinear fastener elements were used to model the stitches and multipoint constraints were used to model the contact problem. Models of the unstitched configuration showed significant values of modes I and II across the width of the joint and showed that mode III is zero at the centerline but increases near the free edge. Models of the stitched configuration showed that the stitches were effective in reducing mode I to zero, but had less of an effect on modes II and III.

Structural Performance of Inconel 625 Superalloy Brazed Joints

NASA Astrophysics Data System (ADS)

Chen, Jianqiang; Demers, Vincent; Cadotte, Eve-Line; Turner, Daniel; Bocher, Philippe

2017-02-01

The purpose of this work was to investigate tensile and fatigue behaviors of Inconel 625 superalloy brazed joints after transient liquid-phase bonding process. Brazing was performed in a vacuum furnace using a nickel-based filler metal in a form of paste to join wrought Inconel 625 plates. Mechanical tests were carried out on single-lap joints under various lap distance-to-thickness ratios. The fatigue crack initiation and crack growth modes were examined via metallographic analysis, and the effect of local stress on fatigue life was assessed by finite element simulations. The fatigue results show that fatigue strength and endurance limit increase with overlap distance, leading to a relatively large scatter of results. Fatigue cracks nucleated in the high-stressed region of the weld fillets from brittle eutectic phases or from internal brazing cavities. The present work proposes to rationalize the results by using the local stress at the brazing fillet. When using this local stress, all fatigue-obtained results find themselves on a single S- N curve, providing a design curve for any joint configuration in fatigue solicitation.

Critical joints in large composite primary aircraft structures. Volume 2: Technology demonstration test report

NASA Technical Reports Server (NTRS)

Bunin, Bruce L.

1985-01-01

A program was conducted to develop the technology for critical structural joints in composite wing structure that meets all the design requirements of a 1990 commercial transport aircraft. The results of four large composite multirow bolted joint tests are presented. The tests were conducted to demonstrate the technology for critical joints in highly loaded composite structure and to verify the analytical methods that were developed throughout the program. The test consisted of a wing skin-stringer transition specimen representing a stringer runout and skin splice on the wing lower surface at the side of the fuselage attachment. All tests were static tension tests. The composite material was Toray T-300 fiber with Ciba-Geigy 914 resin in 10 mil tape form. The splice members were metallic, using combinations of aluminum and titanium. Discussions are given of the test article, instrumentation, test setup, test procedures, and test results for each of the four specimens. Some of the analytical predictions are also included.

Cruise noise of the 2/9th scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

NASA Technical Reports Server (NTRS)

Dittmar, James H.; Stang, David B.

1987-01-01

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak.

The effect of viscoelasticity on the stress distribution of adhesively single-lap joint with an internal break in the composite adherends

NASA Astrophysics Data System (ADS)

Reza, Arash; Shishesaz, Mohammad

2017-09-01

The aim of this research is to study the effect of a break in the laminated composite adherends on stress distribution in the adhesively single-lap joint with viscoelastic adhesive and matrix. The proposed model involves two adherends with E-glass fibers and poly-methyl-methacrylate matrix that have been adhered to each other by phenolic-epoxy resin. The equilibrium equations that are based on shear-lag theory have been derived in the Laplace domain, and the governing differential equations of the model have been derived analytically in the Laplace domain. A numerical inverse Laplace transform, which is called Gaver-Stehfest method, has been used to extract desired results in the time domain. The results obtained at the initial time completely matched with the results of elastic solution. Also, a comparison between results obtained from the analytical and finite element models show a relatively good match. The results show that viscoelastic behavior decreases the peak of stress near the break. Finally, the effect of size and location of the break, as well as volume fraction of fibers, on the stress distribution in the adhesive layer is fully investigated.

Three-dimensional finite element analyses of the local mechanical behavior of riveted lap joints

NASA Astrophysics Data System (ADS)

Iyer, Kaushik Arjunan

Three-dimensional elastic-plastic finite element models of single and double rivet-row lap joints have been developed to evaluate local distortions and the mechanics of airframe-type 7075-T6 aluminum alloy riveted assemblies. Loading induced distortion features such as the excess assembly compliance, rivet tilt, local in- and out-of-plane slips and stress concentration factors are evaluated as functions of rivet countersinking, rivet material and friction coefficient. Computed features are examined to identify alterations in the proportions of in-plane and out-of-plane load transmission across rivet-panel interfaces and isolate global and lower-order effects present in the complex response of these multi-body assemblies. Analytical procedures are validated by comparing calculated and measured values of excess assembly compliance and local panel bending. Direct out-of-plane load transmission between the rivet heads and panels affects global deformation features such as remote panel bending and local features such as the panel stress concentration factor. The increase in stress concentration due to panel bending is self-limiting owing to decreasing in-plane load bearing with increasing rivet tilt, which is a composite reflection of the basic rivet deformation modes of shear and rotation. Calculations have also been performed to define approximate steady-state fretting fatigue conditions that lead to crack initiation at a panel hole surface in single and double rivet-row assemblies for countersunk and non-countersunk rivets. These account for and isolate effects of interference and clamping forces on fatigue performance by comparing computed circumferential variations of bulk residual stresses, cyclic stress range and mean stress. With interference, a non-countersunk assembly is shown to be as prone to crack initiation as a countersunk assembly. Frictional work due to fretting is evaluated and the physical location of fretting fatigue crack initiation is predicted by

Deformations and strains in adhesive joints by moire interferometry

NASA Technical Reports Server (NTRS)

Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.

1984-01-01

Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.

American Academy of Pediatrics. Restraint use on aircraft. Committee on Injury and Poison Prevention.

PubMed

2001-11-01

Occupant protection policies for children younger than 2 years on aircraft are inconsistent with all other national policies on safe transportation. Children younger than 2 years are not required to be restrained or secured on aircraft during takeoff, landing, and conditions of turbulence. They are permitted to be held on the lap of an adult. Preventable injuries and deaths have occurred in children younger than 2 years who were unrestrained in aircraft during survivable crashes and conditions of turbulence. The American Academy of Pediatrics recommends a mandatory federal requirement for restraint use for children on aircraft. The Academy further recommends that parents ensure that a seat is available for all children during aircraft transport and follow current recommendations for restraint use for all children. Physicians play a significant role in counseling families, advocating for public policy mandates, and encouraging technologic research that will improve protection of children in aircraft.

Role of LAP+CD4+ T cells in the tumor microenvironment of colorectal cancer.

PubMed

Zhong, Wu; Jiang, Zhi-Yuan; Zhang, Lei; Huang, Jia-Hao; Wang, Shi-Jun; Liao, Cun; Cai, Bin; Chen, Li-Sheng; Zhang, Sen; Guo, Yun; Cao, Yun-Fei; Gao, Feng

2017-01-21

To investigate the abundance and potential functions of LAP + CD4 + T cells in colorectal cancer (CRC). Proportions of LAP + CD4 + T cells were examined in peripheral blood and tumor/paratumor tissues of CRC patients and healthy controls using flow cytometry. Expression of phenotypic markers such as forkhead box (Fox)p3, cytotoxic T-lymphocyte-associated protein (CTLA)-4, chemokine CC receptor (CCR)4 and CCR5 was measured using flow cytometry. LAP - CD4 + and LAP + CD4 + T cells were isolated using a magnetic cell-sorting system and cell purity was analyzed by flow cytometry. Real-time quantitative polymerase chain reaction was used to measure expression of cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β. The proportion of LAP + CD4 + T cells was significantly higher in peripheral blood from patients (9.44% ± 3.18%) than healthy controls (1.49% ± 1.00%, P < 0.001). Among patients, the proportion of LAP + CD4 + T cells was significantly higher in tumor tissues (11.76% ± 3.74%) compared with paratumor tissues (3.87% ± 1.64%, P < 0.001). We also observed positive correlations between the proportion of LAP + CD4 + T cells and TNM stage ( P < 0.001), distant metastasis ( P < 0.001) and serum level of carcinoembryonic antigen ( P < 0.05). Magnetic-activated cell sorting gave an overall enrichment of LAP + CD4 + T cells (95.02% ± 2.87%), which was similar for LAP - CD4 + T cells (94.75% ± 2.76%). In contrast to LAP - CD4 + T cells, LAP + CD4 + T cells showed lower Foxp3 expression but significantly higher levels of CTLA-4, CCR4 and CCR5 ( P < 0.01). LAP + CD4 + T cells expressed significantly larger amounts of IL-10 and TGF-β but lower levels of IL-2, IL-4, IL-17 and interferon-γ, compared with LAP - CD4 + T cells. LAP + CD4 + T cells accumulated in the tumor microenvironment of CRC patients and were involved in immune evasion mediated by IL-10 and TGF-β.

Analytical and Numerical Results for an Adhesively Bonded Joint Subjected to Pure Bending

NASA Technical Reports Server (NTRS)

Smeltzer, Stanley S., III; Lundgren, Eric

2006-01-01

A one-dimensional, semi-analytical methodology that was previously developed for evaluating adhesively bonded joints composed of anisotropic adherends and adhesives that exhibit inelastic material behavior is further verified in the present paper. A summary of the first-order differential equations and applied joint loading used to determine the adhesive response from the methodology are also presented. The method was previously verified against a variety of single-lap joint configurations from the literature that subjected the joints to cases of axial tension and pure bending. Using the same joint configuration and applied bending load presented in a study by Yang, the finite element analysis software ABAQUS was used to further verify the semi-analytical method. Linear static ABAQUS results are presented for two models, one with a coarse and one with a fine element meshing, that were used to verify convergence of the finite element analyses. Close agreement between the finite element results and the semi-analytical methodology were determined for both the shear and normal stress responses of the adhesive bondline. Thus, the semi-analytical methodology was successfully verified using the ABAQUS finite element software and a single-lap joint configuration subjected to pure bending.

Preliminary measurement of the noise from the 2/9 scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

NASA Technical Reports Server (NTRS)

Dittmar, J. H.

1985-01-01

Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken into the NASA Lewis 8- by 6-Foot Wind Tunnel. The maximum blade passing tone decreases from the peak level when going to higher helical tip Mach numbers. This noise reduction points to the use of higher propeller speeds as a possible method to reduce airplane cabin noise while maintaining high flight speed and efficiency. Comparison of the SR-7A blade passing noise with the noise of the similarly designed SR-3 propeller shows good agreement as expected. The SR-7A propeller is slightly noisier than the SR-3 model in the plane of rotation at the cruise condition. Projections of the tunnel model data are made to the full-scale LAP propeller mounted on the test bed aircraft and compared with design predictions. The prediction method is conservative in the sense that it overpredicts the projected model data.

The LapSim virtual reality simulator: promising but not yet proven.

PubMed

Fairhurst, Katherine; Strickland, Andrew; Maddern, Guy

2011-02-01

The acquisition of technical skills using surgical simulators is an area of active research and rapidly evolving technology. The LapSim is a virtual reality simulator that currently allows practice of basic laparoscopic skills and some procedures. To date, no reviews have been published with reference to a single virtual reality simulator. A PubMed search was performed using the keyword "LapSim," with further papers identified from the citations of original search articles. Use of the LapSim to develop surgical skills has yielded overall results, although inconsistencies exist. Data regarding the transferability of learned skills to the operative environment are encouraging as is the validation work, particularly the use of a combination of measured parameters to produce an overall comparative performance score. Although the LapSim currently does not have any proven significant advantages over video trainers in terms of basic skills instruction and although the results of validation studies are variable, the potential for such technology to have a huge impact on surgical training is apparent. Work to determine standardized learning curves and proficiency criteria for different levels of trainees is incomplete. Moreover, defining which performance parameters measured by the LapSim accurately determine laparoscopic skill is complex. Further technological advances will undoubtedly improve the efficacy of the LapSim, and the results of large multicenter trials are anticipated.

Large-scale Advanced Prop-fan (LAP) technology assessment report

NASA Technical Reports Server (NTRS)

Degeorge, C. L.

1988-01-01

The technologically significant findings and accomplishments of the Large Scale Advanced Prop-Fan (LAP) program in the areas of aerodynamics, aeroelasticity, acoustics and materials and fabrication are described. The extent to which the program goals related to these disciplines were achieved is discussed, and recommendations for additional research are presented. The LAP program consisted of the design, manufacture and testing of a near full-scale Prop-Fan or advanced turboprop capable of operating efficiently at speeds to Mach .8. An aeroelastically scaled model of the LAP was also designed and fabricated. The goal of the program was to acquire data on Prop-Fan performance that would indicate the technology readiness of Prop-Fans for practical applications in commercial and military aviation.

TGF-β induces surface LAP expression on murine CD4 T cells independent of Foxp3 induction.

PubMed

Oida, Takatoku; Weiner, Howard L

2010-11-24

It has been reported that human FOXP3(+) CD4 Tregs express GARP-anchored surface latency-associated peptide (LAP) after activation, based on the use of an anti-human LAP mAb. Murine CD4 Foxp3(+) Tregs have also been reported to express surface LAP, but these studies have been hampered by the lack of suitable anti-mouse LAP mAbs. We generated anti-mouse LAP mAbs by immunizing TGF-β(-/-) animals with a mouse Tgfb1-transduced P3U1 cell line. Using these antibodies, we demonstrated that murine Foxp3(+) CD4 Tregs express LAP on their surface. In addition, retroviral transduction of Foxp3 into mouse CD4(+)CD25(-) T cells induced surface LAP expression. We then examined surface LAP expression after treating CD4(+)CD25(-) T cells with TGF-β and found that TGF-β induced surface LAP not only on T cells that became Foxp3(+) but also on T cells that remained Foxp3(-) after TGF-β treatment. GARP expression correlated with the surface LAP expression, suggesting that surface LAP is GARP-anchored also in murine T cells. Unlike human CD4 T cells, surface LAP expression on mouse CD4 T cells is controlled by Foxp3 and TGF-β. Our newly described anti-mouse LAP mAbs will provide a useful tool for the investigation and functional analysis of T cells that express LAP on their surface.

LAP degradation product reflects plasma kallikrein-dependent TGF-β activation in patients with hepatic fibrosis.

PubMed

Hara, Mitsuko; Kirita, Akiko; Kondo, Wakako; Matsuura, Tomokazu; Nagatsuma, Keisuke; Dohmae, Naoshi; Ogawa, Shinji; Imajoh-Ohmi, Shinobu; Friedman, Scott L; Rifkin, Daniel B; Kojima, Soichi

2014-01-01

Byproducts of cytokine activation are sometimes useful as surrogate biomarkers for monitoring cytokine generation in patients. Transforming growth factor (TGF)-β plays a pivotal role in pathogenesis of hepatic fibrosis. TGF-β is produced as part of an inactive latent complex, in which the cytokine is trapped by its propeptide, the latency-associated protein (LAP). Therefore, to exert its biological activity, TGF-β must be released from the latent complex. Several proteases activate latent TGF-β by cutting LAP. We previously reported that Camostat Mesilate, a broad spectrum protease inhibitor, which is especially potent at inhibiting plasma kallikrein (PLK), prevented liver fibrosis in the porcine serum-induced liver fibrosis model in rats. We suggested that PLK may work as an activator of latent TGF-β during the pathogenesis of liver diseases in the animal models. However, it remained to be elucidated whether this activation mechanism also functions in fibrotic liver in patients. Here, we report that PLK cleaves LAP between R(58) and L(59) residues. We have produced monoclonal antibodies against two degradation products of LAP (LAP-DP) by PLK, and we have used these specific antibodies to immunostain LAP-DP in liver tissues from both fibrotic animals and patients. The N-terminal side LAP-DP ending at R(58) (R(58) LAP-DP) was detected in liver tissues, while the C-terminal side LAP-DP beginning at L(59) (L(59) LAP-DP) was not detectable. The R(58) LAP-DP was seen mostly in α-smooth muscle actin-positive activated stellate cells. These data suggest for the first time that the occurrence of a PLK-dependent TGF-β activation reaction in patients and indicates that the LAP-DP may be useful as a surrogate marker reflecting PLK-dependent TGF-β activation in fibrotic liver both in animal models and in patients.

Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

NASA Astrophysics Data System (ADS)

Harooni, Masoud

current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two

Machine imparting complex rotary motion for lapping a spherical inner diameter

DOEpatents

Carroll, Thomas A.; Yetter, Harold H.

1986-01-01

An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

Machine imparting complex rotary motion for lapping a spherical inner diameter

DOEpatents

Carroll, T.A.; Yetter, H.H.

1985-01-30

An apparatus for imparting complex rotary motion is used to lap an inner spherical diameter surface of a workpiece. A lapping tool consists of a dome and rod mounted along the dome's vertical axis. The workpiece containing the lapping tool is held in a gimbal which uses power derived from a secondary takeoff means to impart rotary motion about a horizontal axis. The gimbal is rotated about a vertical axis by a take means while mounted at a radially outward position on a rotating arm.

Analysis of bonded joints. [shear stress and stress-strain diagrams

NASA Technical Reports Server (NTRS)

Srinivas, S.

1975-01-01

A refined elastic analysis of bonded joints which accounts for transverse shear deformation and transverse normal stress was developed to obtain the stresses and displacements in the adherends and in the bond. The displacements were expanded in terms of polynomials in the thicknesswise coordinate; the coefficients of these polynomials were functions of the axial coordinate. The stress distribution was obtained in terms of these coefficients by using strain-displacement and stress-strain relations. The governing differential equations were obtained by integrating the equations of equilibrium, and were solved. The boundary conditions (interface or support) were satisfied to complete the analysis. Single-lap, flush, and double-lap joints were analyzed, along with the effects of adhesive properties, plate thicknesses, material properties, and plate taper on maximum peel and shear stresses in the bond. The results obtained by using the thin-beam analysis available in the literature were compared with the results obtained by using the refined analysis. In general, thin-beam analysis yielded reasonably accurate results, but in certain cases the errors were high. Numerical investigations showed that the maximum peel and shear stresses in the bond can be reduced by (1) using a combination of flexible and stiff bonds, (2) using stiffer lap plates, and (3) tapering the plates.

32 CFR 855.20 - Joint-use agreements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Joint-use agreements. 855.20 Section 855.20 National Defense Department of Defense (Continued) DEPARTMENT OF THE AIR FORCE AIRCRAFT CIVIL AIRCRAFT USE OF UNITED STATES AIR FORCE AIRFIELDS Agreements for Civil Aircraft Use of Air Force Airfields § 855.20 Joint-use agreements. An agreement between...

A scan-angle correction for thermal infrared multispectral data using side lapping images

USGS Publications Warehouse

Watson, K.

1996-01-01

Thermal infrared multispectral scanner (TIMS) images, acquired with side lapping flight lines, provide dual angle observations of the same area on the ground and can thus be used to estimate variations in the atmospheric transmission with scan angle. The method was tested using TIMS aircraft data for six flight lines with about 30% sidelap for an area within Joshua Tree National Park, California. Generally the results correspond to predictions for the transmission scan-angle coefficient based on a standard atmospheric model although some differences were observed at the longer wavelength channels. A change was detected for the last pair of lines that may indicate either spatial or temporal atmospheric variation. The results demonstrate that the method provides information for correcting regional survey data (requiring multiple adjacent flight lines) that can be important in detecting subtle changes in lithology.

15 CFR 285.4 - Establishment of laboratory accreditation programs (LAPs) within NVLAP.

Code of Federal Regulations, 2010 CFR

2010-01-01

... legislative actions or to requests from private sector entities and government agencies. For legislatively mandated LAPs, NVLAP shall establish the LAP. For requests from private sector entities and government...

Aircraft to Medicine

NASA Technical Reports Server (NTRS)

1991-01-01

This video discusses how the technology of computer modeling can improve the design and durability of artificial joints for human joint replacement surgery. Also, ultrasound, originally used to detect structural flaws in aircraft, can also be used to quickly assess the severity of a burn patient's injuries, thus aiding the healing process.

Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

NASA Astrophysics Data System (ADS)

Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

Analysis of the stress-strain state in single overlap joints using piezo-ceramic actuators

NASA Astrophysics Data System (ADS)

Pǎltânea, Veronica; Pǎltânea, Gheorghe; Popovici, Dorina; Jiga, Gabriel; Papanicolaou, George

2014-05-01

In this paper is presented a 2D approach to finite element modeling and an analytical calculus of a single lap bonded joint. As adherent material were selected a sheet of wood, aluminum and titanium. For adhesive part were selected Bison Super Wood D3 in case of the wood single lap joint and an epoxy resin type DGEBA-TETA for gluing together aluminum and titanium parts. In the article is described a combined method, which consists in the placement of the piezoelectric actuator inside of the adhesive part, in order to determine the tensile stress in the overlap joint. A comparison between the analytical and numerical results has been achieved through a multiphysics modeling - electrical and mechanical coupled problem. The technique used to calculate the mechanical parameters (First Principal Stress, displacements) was the three-point bending test, where different forces were applied in the mid-span of the structure, in order to maintain a constant displacement rate. The length of the overlap joint was modified from 20 to 50 mm.

Rene 95 brazed joint metallurgical program

NASA Technical Reports Server (NTRS)

Gay, C.; Givens, J.; Mastrorroco, S.; Sterman, A.

1972-01-01

This metallurgical program was specifically conducted for the establishment of material properties required for the design of the LF460 fan. The LF460 lift fan is an advanced 18:1 high thrust to weight single stage design. It has a turbine attached to the outer flowpath of the fan blade tip which minimizes the axial depth of the fan. Advanced lightweight attachment designs are employed in this concept to achieve minimum mass polar moments of inertia which are required for good aircraft flight response control. The design features which are unique to this advanced LF460 lift fan are the 0.010 inch thin Udimet 700 alloy integral tip turbine design, minimum weight braze attachment of the turbine to the fan blade, and the high strength and elevated temperature capability of the Rene'95 alloy for the fan blade. The data presented in this report show that the LF460 fan rotor design is feasible and that the design stresses and margins of safety were more than adequate. Prior to any production application, however, additional stress rupture/shear lap joints should be run in order to establish a firm 1200 F stress rupture curve for the CM50 braze metal.

Influences of Friction Stir Welding Parameters on Microstructural and Mechanical Properties of AA5456 (AlMg5) at Different Lap Joint Thicknesses

NASA Astrophysics Data System (ADS)

Pishevar, M. R.; Mohandesi, J. Aghazadeh; Omidvar, H.; Safarkhanian, M. A.

2015-10-01

Friction stir welding is suitable for joining series 5000 alloys because no fusion welding problems arise for the alloys in this process. The present study examined the effects of double-pass welding and tool rotational and travel speeds for the second-pass welding on the mechanical and microstructural properties of friction stir lap welding of AA5456 (AlMg5)-H321 (5 mm thickness) and AA5456 (AlMg5)-O (2.5 mm thickness). The first pass of all specimens was performed at a rotational speed of 650 rpm and a travel speed of 50 mm/min. The second pass was performed at rotational speeds of 250, 450, and 650 rpm and travel speeds of 25, 50, and 75 mm/min. The results showed that the second pass changed the grain sizes in the center of the nugget zone compared with the first pass. It was observed that the size of the hooking defect of the double-pass-welded specimens was higher than that for the single-pass-welded specimen. The size of the hooking defect was found to be a function of the rotational and travel speeds. The optimal joint tensile shear properties were achieved at a rotational speed of 250 rpm and travel a speed of 75 mm/min.

In vitro modulation of the interaction between HA95 and LAP2beta by cAMP signaling.

PubMed

Martins, Sandra B; Marstad, Anne; Collas, Philippe

2003-09-09

The nuclear envelope mediates key functions by interacting with chromatin. We recently reported an interaction between the chromatin- and nuclear matrix-associated protein HA95 and the inner nuclear membrane integral protein LAP2beta, implicated in initiation of DNA replication (Martins et al. (2003) J. Cell Biol. 160, 177-188). Here, we show that in vitro, interaction between HA95 and LAP2beta is modulated by cAMP signaling via PKA. Exposure of an anti-HA95 immune precipitate from interphase HeLa cells to a mitotic extract promotes ATP-dependent release of LAP2beta from the HA95 complex. This coincides with Ser and Thr phosphorylation of HA95 and LAP2beta. Inhibition of PKA with PKI abolishes phosphorylation of HA95 and dissociation of LAP2beta from HA95, although LAPbeta remains phosphorylated. Antagonizing cAMP signaling in mitotic extract also abolishes the release of LAP2beta from HA95; however, disrupting PKA anchoring to A-kinase anchoring proteins has no effect. Inhibition of CDK activity in the extract greatly reduces LAP2beta phosphorylation but does not prevent LAP2beta release from HA95. Inhibition of PKC, MAP kinase, or CaM kinase II does not affect mitotic extract-induced dissociation of LAP2beta from HA95. PKA phosphorylates HA95 but not LAP2beta in vitro and elicits a release of LAP2beta from HA95. CDK1 or PKC phosphorylates LAP2beta within the HA95 complex, but neither kinase induces LAP2beta release. Our results indicate that in vitro, the interaction between HA95 and LAP2beta is influenced by a PKA-mediated phosphorylation of HA95 rather than by CDK1- or PKC-mediated phosphorylation of LAP2beta. This suggests an additional level of regulation of a chromatin-nuclear envelope interaction in dividing cells.

NASA's F-15B testbed aircraft in flight during the first evaluation flight of the joint NASA/Gulfstream Quiet Spike project

NASA Image and Video Library

2006-08-10

NASA's F-15B testbed aircraft in flight during the first evaluation flight of the joint NASA/Gulfstream Quiet Spike project. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

Melanin targets LC3-associated phagocytosis (LAP): A novel pathogenetic mechanism in fungal disease.

PubMed

Chamilos, Georgios; Akoumianaki, Tonia; Kyrmizi, Irene; Brakhage, Axel; Beauvais, Anne; Latge, Jean-Paul

2016-05-03

Intracellular swelling of conidia of the major human airborne fungal pathogen Aspergillus fumigatus results in surface exposure of immunostimulatory pathogen-associated molecular patterns (PAMPs) and triggers activation of a specialized autophagy pathway called LC3-associated phagocytosis (LAP) to promote fungal killing. We have recently discovered that, apart from PAMPs exposure, cell wall melanin removal during germination of A. fumigatus is a prerequisite for activation of LAP. Importantly, melanin promotes fungal pathogenicity via targeting LAP, as a melanin-deficient A. fumigatus mutant restores its virulence upon conditional inactivation of Atg5 in hematopoietic cells of mice. Mechanistically, fungal cell wall melanin selectively excludes the CYBA/p22phox subunit of NADPH oxidase from the phagosome to inhibit LAP, without interfering with signaling regulating cytokine responses. Notably, inhibition of LAP is a general property of melanin pigments, a finding with broad physiological implications.

Measurement of damping of graphite epoxy composite materials and structural joints

NASA Technical Reports Server (NTRS)

Crocker, Malcolm J.; Rao, Mohan D.; Raju, P. K.; Yan, Xinche

1989-01-01

The damping capacity of graphite epoxy materials and structural joints was evaluated. The damping ratio of different composite specimens and bonded joints were systematically evaluated under normal atmospheric conditions and in a vacuum environment. Free and forced vibration test methods were employed for measuring the damping ratios. The effect of edge support conditions on the damping value of a composite tube specimen was studied by using a series of experiments performed on the specimen with different edge supports. It was found that simulating a free-free boundary conditions by having no constraints at the ends gives the lowest value of the material damping of the composite. The accuracy of the estimation of the damping ratio value was improved by using a curve-fitting technique on the response data obtained through measurement. The effect of outgassing (moisture desorption) on the damping capacity was determined by measuring the damping ratio of the tube specimen in a vacuum environment before and after outgassing had occurred. The effects of high and low temperatures on the damping was also investigated by using a series of experiments on tube and beam specimens. An analytical model to study the vibrations of a bonded lap joint system was formulated. Numerical results were generated for different overlap ratios of the system. These were compared with experimental results. In order to determine the influence of bonded joints on the material damping capacity, experiments were conducted on bonded lap-jointed and double-butt-jointed specimens. These experimental results were compared with simple beam specimens with no joints.

Accelerating the Kill Chain via Future Unmanned Aircraft

DTIC Science & Technology

2007-04-01

Controller JTRS Joint Tactical Radio System Lasercom Laser communications LDHD Low Density High Demand LEO Low Earth Orbit LGB Laser Guided Bomb...published the Unmanned Aircraft Systems Roadmap 2005 that included the terms Unmanned Aircraft System (UAS) and Unmanned Aircraft (UA). This...comprehensive publication used the term Unmanned Aircraft Systems when referring to the entire system and the term Unmanned Aircraft when referring only to the

Aircraft remote sensing of phytoplankton spatial patterns during the 1989 Joint Global Ocean Flux Study (JGOFS) North Atlantic bloom experiment

NASA Technical Reports Server (NTRS)

Yoder, James A.; Hoge, Frank E.

1991-01-01

Mesoscale phytoplankton chlorophyll variability near the Joint Global Ocean Flux study sites along the 20 W meridian at 34 N, 47 N, and 59 N is discussed. The NASA P-3 aircraft and the Airborne Oceanographic Lidar (AOL) system provides remote sensing support for the North Atlantic Bloom Experiment. The principal instrument of the AOL system is the blue-green laser that stimulates fluorescence from photoplankton chlorophyll, the principal photosynthetic pigment. Other instruments on the NASA P-3 aircraft include up- and down-looking spectrometers, PRT-5 for infrared measurements to determine sea surface temperature, and a system to deploy and record AXBTs to measure subsurface temperature structure.

The control panel for the joint NASA/Gulfstream Quiet Spike project, located in the backseat of NASA's F-15B testbed aircraft

NASA Image and Video Library

2006-08-16

The control panel for the joint NASA/Gulfstream Quiet Spike project, located in the backseat of NASA's F-15B testbed aircraft. The project seeks to verify the structural integrity of the multi-segmented, articulating spike attachment designed to reduce and control a sonic boom.

CT114 Lap Belt Arming Key Mod - User Trial

DTIC Science & Technology

2010-05-01

31 (97%) 30 (94%) 1. Ease of use to perform visual 30 (94%) 2. Ease of use to perform free play (push past) check 31 (97%) ’Note I - If a...positive lock of the lap belt. 10. Perform Free Play (Push Past) Check - Press mating ends of lap belt fittings together to demo ability to push beyond...the following items. I 2 3 4 5 6 7 37. Ease-of·use in performing visual check? 0 0 0 0 0 0 0 38. Ease-of·use in performing free play (push past

Auto Mechanics I. Learning Activity Packets (LAPs). Section A--Orientation and Safety.

ERIC Educational Resources Information Center

Oklahoma State Board of Vocational and Technical Education, Stillwater. Curriculum and Instructional Materials Center.

This document contains seven learning activity packets (LAPs) that outline the study activities for the orientation and safety instructional area for an Auto Mechanics I course. The seven LAPs cover the following topics: orientation, safety, hand tools, arc welding, oxyacetylene cutting, oxyacetylene fusion welding, and oxyacetylene braze welding.…

Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

DOE PAGES

Squires, Lile; Lim, Yong Chae; Miles, Michael; ...

2015-03-18

In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its highermore » alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.« less

Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

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

Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lapmore » shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.« less

Large-scale Advanced Prop-fan (LAP) high speed wind tunnel test report

NASA Technical Reports Server (NTRS)

Campbell, William A.; Wainauski, Harold S.; Arseneaux, Peter J.

1988-01-01

High Speed Wind Tunnel testing of the SR-7L Large Scale Advanced Prop-Fan (LAP) is reported. The LAP is a 2.74 meter (9.0 ft) diameter, 8-bladed tractor type rated for 4475 KW (6000 SHP) at 1698 rpm. It was designated and built by Hamilton Standard under contract to the NASA Lewis Research Center. The LAP employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Testing was conducted in the ONERA S1-MA Atmospheric Wind Tunnel in Modane, France. The test objectives were to confirm that the LAP is free from high speed classical flutter, determine the structural and aerodynamic response to angular inflow, measure blade surface pressures (static and dynamic) and evaluate the aerodynamic performance at various blade angles, rotational speeds and Mach numbers. The measured structural and aerodynamic performance of the LAP correlated well with analytical predictions thereby providing confidence in the computer prediction codes used for the design. There were no signs of classical flutter throughout all phases of the test up to and including the 0.84 maximum Mach number achieved. Steady and unsteady blade surface pressures were successfully measured for a wide range of Mach numbers, inflow angles, rotational speeds and blade angles. No barriers were discovered that would prevent proceeding with the PTA (Prop-Fan Test Assessment) Flight Test Program scheduled for early 1987.

78 FR 41277 - Airworthiness Directives; Piper Aircraft, Inc. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-10

... through 4697520. (d) Subject Joint Aircraft System Component (JASC)/Air Transport Association (ATA) of... fluorosilicone (orange) fuel vent valve following Part III of Piper Aircraft, Inc. Mandatory Service Bulletin No... Airworthiness Directives; Piper Aircraft, Inc. Airplanes AGENCY: Federal Aviation Administration (FAA), DOT...

Disbond Detection in Bonded Aluminum Joints Using Lamb Wave Amplitude and Time-of-Flight

NASA Technical Reports Server (NTRS)

Sun, Keun J.; Johnston, Patrick H.

1992-01-01

In recent years, there was a need of developing efficient nondestructive integrity assessment techniques for large area laminate structures, such as detections of disbond, crack, and corrosion in fuselage of an aircraft. Together with the improving tomography and computer technologies, progress has been made in many fields in NDE towards a faster inspection. Ultrasonically, Lamb wave is considered to be a candidate for large area inspections based on its capability of propagating a relatively long distance in thin plates and its media-thickness-dependent propagation properties. Moreover, the occurence of disbonds, corrosion, and even cracks often results in reduction of effective thickness of a laminate. The idea is to assess the condition of a structure by sensing the response of propagating Lamb waves to these flaws over long path length. A series of tests in the sequence of disbond, corrosion, and crack have been done on various types of specimen to investigate the feasibility of this approach. This paper will present some of the test results for disbond detection on aluminum lap splice joints.

Analysis and optimization of surface profile correcting mechanism of the pitch lap in large-aperture annular polishing

NASA Astrophysics Data System (ADS)

Zhang, Huifang; Yang, Minghong; Xu, Xueke; Wu, Lunzhe; Yang, Weiguang; Shao, Jianda

2017-10-01

The surface figure control of the conventional annular polishing system is realized ordinarily by the interaction between the conditioner and the lap. The surface profile of the pitch lap corrected by the marble conditioner has been measured and analyzed as a function of kinematics, loading conditions, and polishing time. The surface profile measuring equipment of the large lap based on laser alignment was developed with the accuracy of about 1μm. The conditioning mechanism of the conditioner is simply determined by the kinematics and fully fitting principle, but the unexpected surface profile deviation of the lap emerged frequently due to numerous influencing factors including the geometrical relationship, the pressure distribution at the conditioner/lap interface. Both factors are quantitatively evaluated and described, and have been combined to develop a spatial and temporal model to simulate the surface profile evolution of pitch lap. The simulations are consistent with the experiments. This study is an important step toward deterministic full-aperture annular polishing, providing a beneficial guidance for the surface profile correction of the pitch lap.

Design fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

1979-01-01

Graphite/polyimide (Gr/PI) bolted and bonded joints were investigated. Possible failure modes and the design loads for the four generic joint types are discussed. Preliminary sizing of a type 1 joint, bonded and bolted configuration is described, including assumptions regarding material properties and sizing methodology. A general purpose finite element computer code is described that was formulated to analyze single and double lap joints, with and without tapered adherends, and with user-controlled variable element size arrangements. An initial order of Celion 6000/PMR-15 prepreg was received and characterized.

Experimental Investigation on High-Cycle Fatigue of Inconel 625 Superalloy Brazed Joints

NASA Astrophysics Data System (ADS)

Chen, Jianqiang; Demers, Vincent; Turner, Daniel P.; Bocher, Philippe

2018-04-01

The high-cycle fatigue performance and crack growth pattern of transient liquid phase-brazed joints in a nickel-based superalloy Inconel 625 were studied. Assemblies with different geometries and types of overlaps were vacuum-brazed using the brazing paste Palnicro-36M in conditions such as to generate eutectic-free joints. This optimal microstructure provides the brazed assemblies with static mechanical strength corresponding to that of the base metal. However, eutectic micro-constituents were observed in the fillet region of the brazed assembly due to an incomplete isothermal solidification within this large volume of filler metal. The fatigue performance increased significantly with the overlap distance for single-lap joints, and the best performance was found for double-lap joints. It was demonstrated that these apparent changes in fatigue properties according to the specimen geometry can be rationalized when looking at the fatigue data as a function of the local stress state at the fillet radii. Fatigue cracks were nucleated from brittle eutectic phases located at the surface of the fillet region. Their propagation occurred through the bimodal microstructure of fillet and the diffusion region to reach the base metal. High levels of crack path tortuosity were observed, suggesting that the ductile phases found in the microstructure may act as a potential crack stopper. The fillet region must be considered as the critical region of a brazed assembly for fatigue applications.

Analysing of critical force effects of aircraft seat belt using truss elements

NASA Astrophysics Data System (ADS)

Klemenc, Marek; Markopoulos, Alexandros; Maršálek, Pavel

2017-07-01

This paper deals with the mathematical modelling of an aircraft seat belt crash test. The main goal is determination of a time course of the reactions in a lap belt anchoring points and their maximum values. This work was created on the basis of practical requirements from industry. Results are going to be reflected in developing a new type of aircraft seats. We mainly focus on the mathematical modelling of dynamic problems using the finite element method (FEM). Derived procedures are implemented in the Python programming language and are verified by several examples. A final calculation algorithm is applied on the analysis of the safety belt. We consider that a seat belt bending stiffness is very small compared to a tensile stiffness, therefore we used a 2D plane truss element.

Transfer of skills on LapSim virtual reality laparoscopic simulator into the operating room in urology.

PubMed

Alwaal, Amjad; Al-Qaoud, Talal M; Haddad, Richard L; Alzahrani, Tarek M; Delisle, Josee; Anidjar, Maurice

2015-01-01

Assessing the predictive validity of the LapSim simulator within a urology residency program. Twelve urology residents at McGill University were enrolled in the study between June 2008 and December 2011. The residents had weekly training on the LapSim that consisted of 3 tasks (cutting, clip-applying, and lifting and grasping). They underwent monthly assessment of their LapSim performance using total time, tissue damage and path length among other parameters as surrogates for their economy of movement and respect for tissue. The last residents' LapSim performance was compared with their first performance of radical nephrectomy on anesthetized porcine models in their 4(th) year of training. Two independent urologic surgeons rated the resident performance on the porcine models, and kappa test with standardized weight function was used to assess for inter-observer bias. Nonparametric spearman correlation test was used to compare each rater's cumulative score with the cumulative score obtained on the porcine models in order to test the predictive validity of the LapSim simulator. The kappa results demonstrated acceptable agreement between the two observers among all domains of the rating scale of performance except for confidence of movement and efficiency. In addition, poor predictive validity of the LapSim simulator was demonstrated. Predictive validity was not demonstrated for the LapSim simulator in the context of a urology residency training program.

77 FR 56993 - Airworthiness Directives; Piper Aircraft, Inc. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-09-17

... for related issues on the stabilator control system. For the attached torque tube, Piper Aircraft, Inc.../document.information/documentID/99861 ; and AC 43-4A, Corrosion Control for Aircraft, at http:// rgl.faa... (assembly P/N 20399) installed. (d) Subject Joint Aircraft System Component (JASC)/Air Transport Association...

78 FR 51121 - Airworthiness Directives; Piper Aircraft, Inc.

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-20

...-7135001 through 28R- 7135254. (d) Subject Joint Aircraft System Component (JASC)/Air Transport Association...-0742; Directorate Identifier 2013-CE-012-AD] RIN 2120-AA64 Airworthiness Directives; Piper Aircraft... Aircraft, Inc. Models PA-28-140, PA- 28-150, PA-28-160, PA-28-180, PA-28R-180, and PA-28R-200 airplanes. AD...

Probabilistic and Possibilistic Analyses of the Strength of a Bonded Joint

NASA Technical Reports Server (NTRS)

Stroud, W. Jefferson; Krishnamurthy, T.; Smith, Steven A.

2001-01-01

The effects of uncertainties on the strength of a single lap shear joint are explained. Probabilistic and possibilistic methods are used to account for uncertainties. Linear and geometrically nonlinear finite element analyses are used in the studies. To evaluate the strength of the joint, fracture in the adhesive and material strength failure in the strap are considered. The study shows that linear analyses yield conservative predictions for failure loads. The possibilistic approach for treating uncertainties appears to be viable for preliminary design, but with several qualifications.

The Analysis of Adhesively Bonded Advanced Composite Joints Using Joint Finite Elements

NASA Technical Reports Server (NTRS)

Stapleton, Scott E.; Waas, Anthony M.

2012-01-01

joint configurations, including double cantilever beam and single lap joints.

The induction of tomato leucine aminopeptidase genes (LapA) after Pseudomonas syringae pv. tomato infection is primarily a wound response triggered by coronatine.

PubMed

Pautot, V; Holzer, F M; Chaufaux, J; Walling, L L

2001-02-01

Tomato plants constitutively express a neutral leucine aminopeptidase (LAP-N) and an acidic LAP (LAP-A) during floral development and in leaves in response to insect infestation, wounding, and Pseudomonas syringae pv. tomato infection. To assess the physiological roles of LAP-A, a LapA-antisense construct (35S:asLapA1) was introduced into tomato. The 35S:asLapA1 plants had greatly reduced or showed undetectable levels of LAP-A and LAP-N proteins in healthy and wounded leaves and during floral development. Despite the loss of these aminopeptidases, no global changes in protein profiles were noted. The 35S:asLapA1 plants also exhibited no significant alteration in floral development and did not impact the growth and development of Manduca sexta and P. syringae pv. tomato growth rates during compatible or incompatible infections. To investigate the mechanism underlying the strong induction of LapA upon P. syringae pv. tomato infection, LapA expression was monitored after infection with coronatine-producing and -deficient P. syringae pv. tomato strains. LapA RNA and activity were detected only with the coronatine-producing P. syringae pv. tomato strain. Coronatine treatment of excised shoots caused increases in RNAs for jasmonic acid (JA)-regulated wound-response genes (LapA and pin2) but did not influence expression of a JA-regulated pathogenesis-related protein gene (PR-1). These results indicated that coronatine mimicked the wound response but was insufficient to activate JA-regulated PR genes.

Aircraft radial-belted tire evaluation

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

1990-01-01

An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

Stress analysis of the cracked-lap-shear specimen - An ASTM round-robin

NASA Technical Reports Server (NTRS)

Johnson, W. S.

1987-01-01

This ASTM Round Robin was conducted to evaluate the state of the art in stress analysis of adhesively bonded joint specimens. Specifically, the participants were asked to calculate the strain-energy-release rate for two different geometry cracked lap shear (CLS) specimens at four different debond lengths. The various analytical techniques consisted of 2- and 3-dimensional finite element analysis, beam theory, plate theory, and a combination of beam theory and finite element analysis. The results were examined in terms of the total strain-energy-release rate and the mode I to mode II ratio as a function of debond length for each specimen geometry. These results basically clustered into two groups: geometric linear or geometric nonlinear analysis. The geometric nonlinear analysis is required to properly analyze the CLS specimens. The 3-D finite element analysis gave indications of edge closure plus some mode III loading. Each participant described his analytical technique and results. Nine laboratories participated.

Stress analysis of the cracked lap shear specimens: An ASTM round robin

NASA Technical Reports Server (NTRS)

Johnson, W. S.

1986-01-01

This ASTM Round Robin was conducted to evaluate the state of the art in stress analysis of adhesively bonded joint specimens. Specifically, the participants were asked to calculate the strain-energy-release rate for two different geometry cracked lap shear (CLS) specimens at four different debond lengths. The various analytical techniques consisted of 2- and 3-dimensional finite element analysis, beam theory, plate theory, and a combination of beam theory and finite element analysis. The results were examined in terms of the total strain-energy-release rate and the mode I to mode II ratio as a function of debond length for each specimen geometry. These results basically clustered into two groups: geometric linear or geometric nonlinear analysis. The geometric nonlinear analysis is required to properly analyze the CLS specimens. The 3-D finite element analysis gave indications of edge closure plus some mode III loading. Each participant described his analytical technique and results. Nine laboratories participated.

The Fundamental Reasons Why Laptop Computers should not be Used on Your Lap.

PubMed

Mortazavi, S A R; Taeb, S; Mortazavi, S M J; Zarei, S; Haghani, M; Habibzadeh, P; Shojaei-Fard, M B

2016-12-01

As a tendency to use new technologies, gadgets such as laptop computers are becoming more popular among students, teachers, businessmen and office workers. Today laptops are a great tool for education and learning, work and personal multimedia. Millions of men, especially those in the reproductive age, are frequently using their laptop computers on the lap (thigh). Over the past several years, our lab has focused on the health effects of exposure to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and Magnetic Resonance Imaging (MRI). Our own studies as well as the studies performed by other researchers indicate that using laptop computers on the lap adversely affects the male reproductive health. When it is placed on the lap, not only the heat from a laptop computer can warm men's scrotums, the electromagnetic fields generated by laptop's internal electronic circuits as well as the Wi-Fi Radiofrequency radiation hazards (in a Wi-Fi connected laptop) may decrease sperm quality. Furthermore, due to poor working posture, laptops should not be used on the lap for long hours.

The Fundamental Reasons Why Laptop Computers should not be Used on Your Lap

PubMed Central

Mortazavi, S.A.R.; Taeb, S.; Mortazavi, S.M.J.; Zarei, S.; Haghani, M.; Habibzadeh, P.; Shojaei-fard, M.B.

2016-01-01

As a tendency to use new technologies, gadgets such as laptop computers are becoming more popular among students, teachers, businessmen and office workers. Today laptops are a great tool for education and learning, work and personal multimedia. Millions of men, especially those in the reproductive age, are frequently using their laptop computers on the lap (thigh). Over the past several years, our lab has focused on the health effects of exposure to different sources of electromagnetic fields such as cellular phones, mobile base stations, mobile phone jammers, laptop computers, radars, dentistry cavitrons and Magnetic Resonance Imaging (MRI). Our own studies as well as the studies performed by other researchers indicate that using laptop computers on the lap adversely affects the male reproductive health. When it is placed on the lap, not only the heat from a laptop computer can warm men’s scrotums, the electromagnetic fields generated by laptop’s internal electronic circuits as well as the Wi-Fi Radiofrequency radiation hazards (in a Wi-Fi connected laptop) may decrease sperm quality. Furthermore, due to poor working posture, laptops should not be used on the lap for long hours. PMID:28144597

Finite Element Modeling of Viscoelastic Behavior and Interface Damage in Adhesively Bonded Joints

DTIC Science & Technology

2012-01-01

eccentricity of the axis of a lap joint gives rise to transverse or peel stresses at the Report Documentation Page Form ApprovedOMB No. 0704-0188...Computers and Structures 29, 1011 (1988). 21 S. Roy and J. N. Reddy, Tire Sci. Technol. 16, 146 (1988). 22 S. Roy and J. N. Reddy, Intl. J. Numer

77 FR 21395 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-10

... would require performing a low frequency eddy current inspection for cracks of the lap joint of the rear...-frequency eddy current inspection of the lap joint for cracks and, depending on findings, repair of the lap... AD: Do a low frequency eddy current (LFEC) inspection for cracks of the lap joint of the rear...

Small molecules targeting LapB protein prevent Listeria attachment to catfish muscle

PubMed Central

Das, Bhaskar; Lawrence, Mark

2017-01-01

Listeria monocytogenes is a Gram-positive foodborne pathogen and the causative agent of listeriosis. L. monocytogenes lapB gene encodes a cell wall surface anchor protein, and mutation of this gene causes Listeria attenuation in mice. In this work, the potential role of Listeria LapB protein in catfish fillet attachment was investigated. To achieve this, boron-based small molecules designed to interfere with the active site of the L. monocytogenes LapB protein were developed, and their ability to prevent L. monocytogenes attachment to fish fillet was tested. Results indicated that seven out of nine different small molecules were effective in reducing the Listeria attachment to catfish fillets. Of these, three small molecules (SM3, SM5, and SM7) were highly effective in blocking Listeria attachment to catfish fillets. This study suggests an alternative strategy for reduction of L. monocytogenes contamination in fresh and frozen fish products. PMID:29253892

Time- and temperature-dependent failures of a bonded joint

NASA Astrophysics Data System (ADS)

Sihn, Sangwook

This dissertation summarizes my study of time- and temperature-dependent behavior of a tubular lap bonded joint to provide a design methodology for windmill blade structures. The bonded joint is between a cast-iron rod and a GFRP composite pipe. The adhesive material is an epoxy containing chopped glass fibers. We proposed a new fabrication method to make concentric and void-less specimens of the tubular joint with a thick adhesive bondline to stimulate the root bond of a blade. The thick bondline facilitates the joint assembly of actual blades. For a better understanding of the behavior of the bonded joint, we studied viscoelastic behavior of the adhesive materials by measuring creep compliance at several temperatures during loading period. We observed that the creep compliance depends highly on the period of loading and the temperature. We applied time-temperature equivalence to the creep compliance of the adhesive material to obtain time-temperature shift factors. We also performed constant-rate of monotonically increased uniaxial tensile tests to measure static strength of the tubular lap joint at several temperatures and different strain-rates. We observed two failure modes from load-deflection curves and failed specimens. One is the brittle mode, which was caused by weakness of the interfacial strength occurring at low temperature and short period of loading. The other is the ductile mode, which was caused by weakness of the adhesive material at high temperature and long period of loading. Transition from the brittle to the ductile mode appeared as the temperature or the loading period increased. We also performed tests under uniaxial tensile-tensile cyclic loadings to measure fatigue strength of the bonded joint at several temperatures, frequencies and stress ratios. The fatigue data are analyzed statistically by applying the residual strength degradation model to calculate statistical distribution of the fatigue life. Combining the time

Failure modes of single and multi-bolted joint in the pultruded fiber reinforced polymer composite members

NASA Astrophysics Data System (ADS)

Kim, S. Y.; Yoo, J. H.; Kim, H. K.; Shin, K. Y.; Yoon, S. J.

2018-06-01

In this paper, we discussed the structural behavior of bolted lap-joint connections in pultruded FRP structural members. Especially, bolted connections in pultruded FRP members are investigated for their failure modes and strength. Specimens with single and multiple bolt-holes are tested in tension under bolt-loading conditions. All of the specimens are instrumented with strain gages and the load-strain responses are monitored. The failed specimens are examined for the cracks and failure patterns. The purpose of this paper is to predict the failure strength by using the ratio of the results obtained by the experiment and the finite element analysis. In the study, several tests are conducted to determine the mechanical properties of pultruded FRP materials before the main experiment. The results are used in the finite element analysis for single and multiple bolted lap-joint specimens. The results obtained by the experiment are compared with the results obtained by the finite element analysis.

Dynamic expression of the LAP family of genes during early development of Xenopus tropicalis.

PubMed

Yang, Qiutan; Lv, Xiaoyan; Kong, Qinghua; Li, Chaocui; Zhou, Qin; Mao, Bingyu

2011-10-01

The leucine-rich repeats and PDZ (LAP) family of genes are crucial for the maintenance of cell polarity as well as for epithelial homeostasis and tumor suppression in both vertebrates and invertebrates. Four members of this gene family are known: densin, erbin, scribble and lano. Here, we identified the four members of the LAP gene family in Xenopus tropicalis and studied their expression patterns during embryonic development. The Xenopus LAP proteins show a conserved domain structure that is similar to their homologs in other vertebrates. In Xenopus embryos, these genes were detected in animal cap cells at the early gastrula stage. At later stages of development, they were widely expressed in epithelial tissues that are highly polar in nature, including the neural epithelia, optic and otic vesicles, and in the pronephros. These data suggest that the roles of the Xenopus LAP genes in the control of cell polarity and morphogenesis are conserved during early development. Erbin and lano show similar expression patterns in the developing head, suggesting potential functional interactions between the two molecules in vivo.

Age of Lunar Meteorite LAP02205 and Implications for Impact-Sampling of Planetary Surfaces

NASA Technical Reports Server (NTRS)

Nyquist, L. E.; Shih, C.-Y.; Reese, Y.; Bogard, D. D.

2005-01-01

We have measured the age of lunar meteorite LAP02205 by the Rb-Sr and Ar-Ar methods. Sm-Nd analyses are in progress. The Rb-Sr and Ar-Ar ages indicate a crystallization age of approx. 3 Ga. Comparing the ages of LAP02205 and other lunar mare basaltic meteorites to mare surface ages based on the density of impact craters shows no significant bias in impact- sampling of lunar mare surfaces. Comparing the isotopic and geochemical data for LAP02205 to those for other lunar mare basalts suggests that it is a younger variant of the type of volcanism that produced the Apollo 12 basalts. Representative impact-sampling of the lunar surface

Effect of Different Connection Modes on Bolt Structural Properties of TC4 Alloy in Selective Laser Melting

NASA Astrophysics Data System (ADS)

Li, Xiaodan; Huang, Shuangjun; Xu, Liang; Hui, Li; Zhou, Song

2017-12-01

The bolt structural properties of selective laser melted (SLM) samples produced from TC4 powder metal has been investigated. Two different connection molds relative to single lap joint and bilateral lap joint as well as two different state of surface quality were considered. Samples and test procedures were designed in accordance with HB 5143 and HB 5287 standard. The results show that there is a strong influence of connection molds on the dynamic behavior of SLM produced TC4. The mechanical properties of bilateral lap joint are better than those of the single lap joint. Meanwhile the fatigue performance of the bilateral lap joint is much stronger than that of the single lap joint which it is a symmetrical structure of the two-shear test on both sides of the force evenly, while the single lap joint is a single shear sample of the uneven force. There are two kinds of fracture form most of which are broken in the first row of screw and a small part in the middle of the connecting plate.

On the water lapping of felines and the water running of lizards

PubMed Central

Aristoff, Jeffrey M; Stocker, Roman; Reis, Pedro M

2011-01-01

We consider two biological phenomena taking place at the air-water interface: the water lapping of felines and the water running of lizards. Although seemingly disparate motions, we show that they are intimately linked by their underlying hydrodynamics and belong to a broader class of processes called Froude mechanisms. We describe how both felines and lizards exploit inertia to defeat gravity, and discuss water lapping and water running in the broader context of water exit and water entry, respectively. PMID:21655444

Validation of a novel basic virtual reality simulator, the LAP-X, for training basic laparoscopic skills.

PubMed

Kawaguchi, Koji; Egi, Hiroyuki; Hattori, Minoru; Sawada, Hiroyuki; Suzuki, Takahisa; Ohdan, Hideki

2014-10-01

Virtual reality surgical simulators are becoming popular as a means of providing trainees with an opportunity to practice laparoscopic skills. The Lap-X (Epona Medical, Rotterdam, the Netherlands) is a novel VR simulator for training basic skills in laparoscopic surgery. The objective of this study was to validate the LAP-X laparoscopic virtual reality simulator by assessing the face and construct validity in order to determine whether the simulator is adequate for basic skills training. The face and content validity were evaluated using a structured questionnaire. To assess the construct validity, the participants, nine expert surgeons (median age: 40 (32-45)) (>100 laparoscopic procedures) and 11 novices performed three basic laparoscopic tasks using the Lap-X. The participants reported a high level of content validity. No significant differences were found between the expert surgeons and the novices (Ps > 0.246). The performance of the expert surgeons on the three tasks was significantly better than that of the novices in all parameters (Ps < 0.05). This study demonstrated the face, content and construct validity of the Lap-X. The Lap-X holds real potential as a home and hospital training device.

Evaluation of High Temperature Properties and Microstructural Characterization of Resistance Spot Welded Steel Lap Shear Joints

NASA Astrophysics Data System (ADS)

Gupta, R. K.; Anil Kumar, V.; Panicker, Paul G.

2016-02-01

Joining of thin sheets (0.5 mm) of stainless steel 304 and 17-4PH through resistance spot welding is highly challenging especially when joint is used for high temperature applications. Various combinations of stainless steel sheets of thickness 0.5 mm are spot welded and tested at room temperature as well as at high temperatures (800 K, 1,000 K, 1,200 K). Parent metal as well as spot welded joints are tested and characterized. It is observed that joint strength of 17-4PH steel is highest and then dissimilar steel joint of 17-4PH with SS-304 is moderate and of SS-304 is lowest at all the temperatures. Joint strength of 17-4PH steel is found to be >80% of parent metal properties up to 1,000 K then drastic reduction in strength is noted at 1,200 K. Gradual reduction in strength of SS-304 joint with increase in temperature from 800 to 1,200 K is noted. At 1,200 K, joint strength of all combinations of joints is found to be nearly same. Microstructural evaluation of weld nugget after testing at different temperatures shows presence of tempered martensite in 17-4PH containing welds and homogenized structure in stainless steel 304 weld.

Imaging flaws in thin metal plates using a magneto-optic device

NASA Technical Reports Server (NTRS)

Wincheski, B.; Prabhu, D. R.; Namkung, M.; Birt, E. A.

1992-01-01

An account is given of the capabilities of the magnetooptic/eddy-current imager (MEI) apparatus in the case of aging aircraft structure-type flaws in 2024-T3 Al alloy plates. Attention is given to images of cyclically grown fatigue cracks from rivetted joints in fabricated lap-joint structures, electrical discharge machining notches, and corrosion spots. Although conventional eddy-current methods could have been used, the speed and ease of MEI's use in these tests is unmatched by such means. Results are displayed in real time as a test piece is scanned, furnishing easily interpreted flaw images.

Biodegradation of international jet A-1 aviation fuel by microorganisms isolated from aircraft tank and joint hydrant storage systems.

PubMed

Itah, A Y; Brooks, A A; Ogar, B O; Okure, A B

2009-09-01

Microorganisms contaminating international Jet A-1 aircraft fuel and fuel preserved in Joint Hydrant Storage Tank (JHST) were isolated, characterized and identified. The isolates were Bacillus subtillis, Bacillus megaterium, Flavobacterium oderatum, Sarcina flava, Micrococcus varians, Pseudomonas aeruginosa, Bacillus licheniformis, Bacillus cereus and Bacillus brevis. Others included Candida tropicalis, Candida albicans, Saccharomyces estuari, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Cladosporium resinae, Penicillium citrinum and Penicillium frequentans. The viable plate count of microorganisms in the Aircraft Tank ranged from 1.3 (+/-0.01) x 104 cfu/mL to 2.2 (+/-1.6) x 104 cfu/mL for bacteria and 102 cfu/mL to 1.68 (+/-0.32) x 103 cfu/mL for fungi. Total bacterial counts of 1.79 (+/-0.2) x 104 cfu/mL to 2.58 (+/-0.04) x 104 cfu/mL and total fungal count of 2.1 (+/-0.1) x 103 cfu/mL to 2.28 (+/-0.5) x 103 cfu/mL were obtained for JHST. Selected isolates were re-inoculated into filter sterilized aircraft fuels and biodegradation studies carried out. After 14 days incubation, Cladosporium resinae exhibited the highest degradation rate with a percentage weight loss of 66 followed by Candida albicans (60.6) while Penicillium citrinum was the least degrader with a weight loss of 41.6%. The ability of the isolates to utilize the fuel as their sole source of carbon and energy was examined and found to vary in growth profile between the isolates. The results imply that aviation fuel could be biodegraded by hydrocarbonoclastic microorganisms. To avert a possible deterioration of fuel quality during storage, fuel pipe clogging and failure, engine component damage, wing tank corrosion and aircraft disaster, efficient routine monitoring of aircraft fuel systems is advocated.

Leucine aminopeptidase, HlLAP, from the ixodid tick Haemaphysalis longicornis, plays vital roles in the development of oocytes.

PubMed

Hatta, Takeshi; Tsuji, Naotoshi; Miyoshi, Takeharu; Islam, M Khyrul; Alim, M Abdul; Yamaji, Kayoko; Anisuzzaman; Fujisaki, Kozo

2010-06-01

Female ixodid ticks are amazing invertebrate animals which efficiently convert a large amount of nutrients derived from their ingested blood meals into eggs. Although oocyte development (vitellogenesis) in ticks is triggered by a blood meal and is assumed to be supported by nutrition derived from ovarian cells connecting oocytes, little is known about the ovarian molecules processing nutrient materials for the vitellogenesis. In this study, we have suggested a putative function of leucine aminopeptidase (HlLAP) in the ovary of parthenogenetic adult ixodid tick Haemaphysalis longicornis regarding a negative output of reproduction following disruption of HlLAP gene by RNA interference. Endogenous HlLAP was shown to be localized in the ovarian cells, including ovarian epithelial and pedicel cells which were assumed to provide nutrients for the developing oocytes. Histological studies demonstrated that a majority of immature oocytes in HlLAP gene knockdown ticks were transformed into abnormal morpho-histological oocytes with vacuolated cytoplasm and/or condensed nucleus. Taken together, a reduction of the numbers of laid eggs in the HlLAP gene knockdown ticks may be due to the degeneration of immature oocytes following deprivation of nutrients such as amino acids supplied not only by midgut HlLAP but also by the ovarian HlLAP. Regulation of the tick molecules involved in nutrient metabolism for the reproduction, including blood digestion and vitellogenesis, would help in controlling the tick population and tick-borne pathogens.

Study on active lap tool influence function in grinding 1.8 m primary mirror.

PubMed

Haitao, Liu; Zhige, Zeng; Fan, Wu; Bin, Fan; Yongjian, Wan

2013-11-01

We present a theoretical modeling method to predict the ring tool influence function (TIF) based on the computer-controlled active lap process. The gap on the lap-grinding layer is considered, and its influence on the ring TIF is analyzed too. The relationship between the shape of the ring TIF and the lap-workpiece rotation speed ratio is discussed in this paper. The recipe for calculating dwell time for axisymmetric fabrication is discussed. The grinding process of a 1.8 m primary mirror is improved based on these results. The grinding process is accomplished after 30 circles of grinding, and the surface shape error is from PV 82 μm RMS 16.4 μm reduced to PV 13.5 μm RMS 2.5 μm.

Bonded joint and method. [for reducing peak shear stress in adhesive bonds

NASA Technical Reports Server (NTRS)

Sainsbury-Carter, J. B. (Inventor)

1974-01-01

An improved joint is described for reducing the peak shear stress in adhesive bonds when adhesives are used to bond two materials which are in a lapped relationship and which differ in value of modulus of elasticity. An insert placed between the adhesive and one of the two materials acts to cushion the discontinuity of material stiffness thereby reducing the peak shear stress in the adhesive bond.

Fast downscaled inverses for images compressed with M-channel lapped transforms.

PubMed

de Queiroz, R L; Eschbach, R

1997-01-01

Compressed images may be decompressed and displayed or printed using different devices at different resolutions. Full decompression and rescaling in space domain is a very expensive method. We studied downscaled inverses where the image is decompressed partially, and a reduced inverse transform is used to recover the image. In this fashion, fewer transform coefficients are used and the synthesis process is simplified. We studied the design of fast inverses, for a given forward transform. General solutions are presented for M-channel finite impulse response (FIR) filterbanks, of which block and lapped transforms are a subset. Designs of faster inverses are presented for popular block and lapped transforms.

Influence of laser beam incidence angle on laser lap welding quality of galvanized steels

NASA Astrophysics Data System (ADS)

Mei, Lifang; Yan, Dongbing; Chen, Genyu; Wang, Zhenhui; Chen, Shuixuan

2017-11-01

Based on the characteristics of laser welded structural parts of auto bodies, the influence of variation in laser beam incidence angle on the lap welding performance of galvanized auto-body sheets was studied. Lap welding tests were carried out on the galvanized sheets for auto-body application at different laser beam incidence angles by using the optimal welding parameters obtained through orthogonal experiment. The effects of incidence angle variation on seam appearance, cross-sectional shape, joint mechanical properties and microstructure of weldments were analyzed. In addition, the main factors influencing the value of incidence angle were investigated. According to the results, the weld seams had a good appearance as well as a fine, and uniform microstructure when the laser beam incidence angle was smaller than the critical incidence angle, and thus they could withstand great tensile and shear loads. Moreover, all tensile-shear specimens were fractured in the base material zone. When the laser beam incidence angle was larger than the critical incidence angle, defects like shrinkage and collapse tended to emerge, thereby resulting in the deteriorated weldability of specimens. Meanwhile, factors like the type and thickness of sheet, weld width as well as inter-sheet gap all had a certain effect on the value of laser beam incidence angle. When the sheet thickness was small and the weld width was narrow, the laser beam incidence angle could be increased appropriately. At the same time, small changes in the inter-sheet gap could greatly impact the value of incidence angle. When the inter-sheet gap was small, the laser beam incidence angle should not be too large.

EEG and ERP profiles in the high alcohol preferring (HAP) and low alcohol preferring (LAP) mice: relationship to ethanol preference.

PubMed

Slawecki, Craig J; Grahame, Nicholas J; Roth, Jennifer; Katner, Simon N; Ehlers, C L

2003-01-31

Neurophysiological measures, such as decreased P300 amplitude and altered EEG alpha activity, have been associated with increased alcoholism risk. The purpose of the present study was to extend the assessment of the neurophysiological indices associated with alcohol consumption to a recently developed mouse model of high ethanol consumption, the first replicate line of high alcohol preferring (HAP-1) and low alcohol preferring (LAP-1) mice. Male HAP-1, LAP-1, and HS mice from the Institute for Behavioral Genetics at the University of Colorado Health Science Center (i.e., HS/Ibg mice) were implanted with cortical electrodes. EEG activity, and event related potentials (ERPs) were then examined. Following electrophysiological assessment, ethanol preference was assessed to examine the relationship between neurophysiological indices and ethanol consumption. EEG analyses revealed that HAPs and HS/Ibgs had greater peak frequency in the 2-4-Hz band and lower peak frequency in the 6-8- and 1-50-Hz bands of the cortical EEG compared to LAPs. Compared to HAPs, LAPs and HS/Ibgs had decreased peak EEG frequency in the 8-16-Hz band. Decreased parietal cortical power from 8 to 50 Hz was associated with high initial ethanol preference in HAP mice. In regards to ERPs, P1 amplitude was greater in HAPs compared to both LAPs and HS/Ibgs and the P3 latency in LAPs was decreased compared to both HAPs and HS/Ibgs. As expected, HAPs consumed more ethanol and had higher ethanol preference than LAPs and HS/Ibgs. There were no significant differences in ethanol intake or preference between HS/Ibgs and LAPs. These data indicate that selective breeding of the HAP and LAP lines has resulted in the divergence of EEG and ERP phenotypes. The differences observed suggest that increased cortical P1 amplitude and altered cortical EEG activity in the 8-50-Hz frequency range may be neurophysiological 'risk factors' associated with high ethanol consumption in mice. Decreased P3 latency in LAPs compared

Characteristics of solder joints under fatigue loads using piezomechanical actuation

NASA Astrophysics Data System (ADS)

Shim, Dong-Jin; Spearing, S. Mark

2003-07-01

Crack initiation and growth characteristics of solder joints under fatigue loads are investigated using piezomechanical actuation. Cracks in solder joints, which can cause failure in microelectronics components, are induced via piezoelectricity in piezo-ceramic bonded joints. Lead-zirconate-titanate ceramic plates and eutectic Sn-Pb solder bonded in a double-lap shear configuration are used in the investigation. Electric field across each piezo-ceramic plate is applied such that shear stresses/strains are induced in the solder joints. The experiments show that cracks initiate in the solder joints around defects such as voids and grow in length until they coalesce with other cracks from adjacent voids. These observations are compared with the similar thermal cycling tests from the literature to show feasibility and validity of the current method in investigating the fatigue characteristics of solder joints. In some specimens, cracks in the piezo-ceramic plates are observed, and failure in the specimens generally occurred due to piezo-ceramic plate fracture. The issues encountered in implementing this methodology such as low actuation and high processing temperatures are further discussed.

Effect of Stitching on Debonding in Composite Structural Elements

NASA Technical Reports Server (NTRS)

Raju, I. S.; Glaessgen, E. H.

2001-01-01

Stitched multiaxial warp knit materials have been suggested as viable alternatives to laminated prepreg materials for large aircraft structures such as wing skins. Analyses have been developed to quantify the effectiveness of stitching for reducing strain energy release rates in skin-stiffener debond, lap joint and sandwich debond configurations. Strain energy release rates were computed using the virtual crack closure technique. In all configurations, the stitches were shown to significantly reduce the strain energy release rate.

Viscoelastic analysis of adhesively bonded joints

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.

1980-01-01

An adhesively bonded lap joint is analyzed by assuming that the adherends are elastic and the adhesive is linearly viscoelastic. After formulating the general problem a specific example for two identical adherends bonded through a three parameter viscoelastic solid adhesive is considered. The standard Laplace transform technique is used to solve the problem. The stress distribution in the adhesive layer is calculated for three different external loads, namely, membrane loading, bending, and transverse shear loading. The results indicate that the peak value of the normal stress in the adhesive is not only consistently higher than the corresponding shear stress but also decays slower.

Multi-Scale Computational Modeling of Ni-Base Superalloy Brazed Joints for Gas Turbine Applications

NASA Astrophysics Data System (ADS)

Riggs, Bryan

, ductile a-Ni phase that formed at the joint interface and a hard, brittle multi-phase centerline eutectic. CrB and Ni3B type borides were identified in the eutectic region via electron probe micro-analysis, and a boron diffusion gradient was observed in the BM adjacent to the joint. The volume fraction of centerline eutectic was found to be highly dependent on the extent of the boron diffusion that occurred during brazing and therefore a function of the primary process parameters; hold time, temperature, FM/BM composition, and joint gap. Thermo-Calc(TM) and DICTRA(TM) simulations were used to model the BM dissolution, isothermal solidification and phase transformations that occurred during brazing to predict the final joint microstructure based on these process parameters. Good agreement was found between experimental and simulated joint microstructures at various joint gaps demonstrating the application of these simulations for brazed joints. However, thermodynamic/kinetic databases available for brazing FMs were limited. A variety of mechanical testing was performed to determine the mechanical properties of CMSX-4/BNi-2 and IN718/BNi-2 brazed joints including small-scale tensile tests, standard-size butt joints and lap shear tests. Small-scale tensile testing provided a novel method for studying microstructure-property relationships in brazed joints and indicated that both joint strength and ductility decrease significantly with an increase in the volume fraction of centerline eutectic. In-situ observations during small-scale testing also showed strain localization and crack initiation occurs around the hard, eutectic phases in the joint microstructure during loading. The average tensile strength for standard-size IN718/BNi-2 butt joints containing a low volume fraction of centerline eutectic was found to be 152.8 ksi approximately 90% of the BM yield strength (˜170 ksi). The average lap shear FM stress was found to decrease from 70 to 20 ksi for IN718/BNi-2 joints and

The Staphylococcus aureus leucine aminopeptidase LAP is localized to the bacterial cytosol and demonstrates a broad substrate range that extends beyond leucine

PubMed Central

Carroll, Ronan K.; Veillard, Florian; Gagne, Danielle T.; Lindenmuth, Jarrod M.; Poreba, Marcin; Drag, Marcin; Potempa, Jan; Shaw, Lindsey N.

2013-01-01

Staphylococcus aureus is a potent pathogen of humans exhibiting a broad disease range, in part, due to an extensive repertoire of secreted virulence factors, including proteases. Recently, we identified the first example of an intracellular protease (leucine aminopeptidase - LAP) that is required for virulence in S. aureus. Disruption of pepZ, the gene encoding LAP, had no affect on the growth rate of bacteria, however, in systemic and localized infection models the pepZ mutant was significantly attenuated in virulence. Recently, a contradictory report has been published, suggesting that LAP is an extracellular enzyme and it is required for growth in S. aureus. Here, we investigate these results and confirm our previous findings that LAP is localized to the bacterial cytosol and is not required for growth. In addition we conduct a biochemical investigation of purified recombinant LAP identifying optimal conditions for enzymatic activity and substrate preference for hydrolysis. Our results show that LAP has a broad substrate range, including activity against the dipeptide cysteine-glycine and that leucine is not the primary target of LAP. PMID:23241672

Material characterization of structural adhesives in the lap shear mode

NASA Technical Reports Server (NTRS)

Sancaktar, E.; Schenck, S. C.

1983-01-01

A general method for characterizing structual adhesives in the bonded lap shear mode is proposed. Two approaches in the form of semiempirical and theoretical approaches are used. The semiempirical approach includes Ludwik's and Zhurkov's equations to describe respectively, the failure stresses in the constant strain rate and constant stress loading modes with the inclusion of the temperature effects. The theoretical approach is used to describe adhesive shear stress-strain behavior with the use of viscoelastic or nonlinear elastic constitutive equations. Two different model adhesives are used in the single lap shear mode with titanium adherends. These adhesives (one of which was developed at NASA Langley Research Center) are currently considered by NASA for possible aerospace applications. Use of different model adhesives helps in assessment of the generality of the method.

Assessment of vitamin D status and serum CrossLaps levels in adults with primary lactose malabsorption.

PubMed

Enko, D; Kriegshäuser, G; Stolba, R; Mangge, H; Brandstetter, D; Mayr, N; Forstner, T; Halwachs-Baumann, G

2016-09-01

Primary adult-type lactose malabsorption (PALM) is a widespread inherited autosomal recessive condition, which is considered to be associated with osteoporosis. This prospective study aimed at assessing the 25-hydroxy-vitamin D (25(OH)D) status and serum CrossLaps levels in individuals with PALM and normal controls. All participants (n=210) underwent genotyping for the LCT C/T-13910 polymorphism, 25(OH)D and CrossLaps measurements and clinical examinations. In addition, the anthropometric data (that is, height, weight and body mass index) were determined. Fifty-five individuals with PALM (that is, LCT C/C-13910 homozygotes) showed lower 25(OH)D (mean: 24.95±10.04 vs 28.59±9.56 ng/ml, P=0.018) and higher CrossLaps serum levels (mean: 0.46±0.31 vs 0.43±0.49 ng/ml, P=0.251) compared with 155 normal controls (that is, LCT C/T-13910 hetero- or T/T-13910 homozygotes). Anthropometric data were similar between PALM probands and controls. Individuals with PALM were found to have lower 25(OH)D and higher CrossLaps serum levels compared with normal controls. In order to preserve life-long bone health, routine 25(OH)D and CrossLaps serum measurements should be performed in individuals with PALM.

Aircraft modifications: Assessing the current state of Air Force aircraft modifications and the implications for future military capability

NASA Astrophysics Data System (ADS)

Hill, Owen Jacob

How prepared is the U.S. Air Force to modify its aircraft fleet in upcoming years? Aircraft modernization is a complex interaction of new and legacy aircraft, organizational structure, and planning policy. This research will take one component of modernization: aircraft modification, and apply a new method of analysis in order to help formulate policy to promote modernization. Departing from previous small-sample studies dependent upon weight as a chief explanatory variable, this dissertation incorporates a comprehensive dataset that was constructed for this research of all aircraft modifications from 1996 through 2005. With over 700 modification programs, this dataset is used to examine changes to the current modification policy using policy-response regression models. These changes include separating a codependent procurement and installation schedule, reducing the documentation requirements for safety modifications, and budgeting for aging aircraft modifications. The research then concludes with predictive models for the F-15 and F-16 along with their replacements: the F-22 and F-35 Joint Strike Fighter.

Research related to variable sweep aircraft development

NASA Technical Reports Server (NTRS)

Polhamus, E. C.; Toll, T. A.

1981-01-01

Development in high speed, variable sweep aircraft research is reviewed. The 1946 Langley wind tunnel studies related to variable oblique and variable sweep wings and results from the X-5 and the XF1OF variable sweep aircraft are discussed. A joint program with the British, evaluation of the British "Swallow", development of the outboard pivot wing/aft tail configuration concept by Langley, and the applied research program that followed and which provided the technology for the current, variable sweep military aircraft is outlined. The relative state of variable sweep as a design option is also covered.

Economics of technological change - A joint model for the aircraft and airline industries

NASA Technical Reports Server (NTRS)

Kneafsey, J. T.; Taneja, N. K.

1981-01-01

The principal focus of this econometric model is on the process of technological change in the U.S. aircraft manufacturing and airline industries. The problem of predicting the rate of introduction of current technology aircraft into an airline's fleet during the period of research, development, and construction for new technology aircraft arises in planning aeronautical research investments. The approach in this model is a statistical one. It attempts to identify major factors that influence transport aircraft manufacturers and airlines, and to correlate them with the patterns of delivery of new aircraft to the domestic trunk carriers. The functional form of the model has been derived from several earlier econometric models on the economics of innovation, acquisition, and technological change.

Investigation on the Effect of Pulsed Energy on Strength of Fillet Lap Laser Welded AZ31B Magnesium Alloys

NASA Astrophysics Data System (ADS)

Salleh, M. N. M.; Ishak, M.; Aiman, M. H.; Idris, S. R. A.; Romlay, F. R. M.

2017-09-01

AZ31B magnesium alloy have been hugely applied in the aerospace, automotive, and electronic industries. However, welding thin sheet AZ31B was challenging due to its properties which is easily to evaporated especially using conventional fusion welding method such as metal inert gas (MIG). Laser could be applied to weld this metal since it produces lower heat input. The application of fiber laser welding has been widely since this type of laser could produce better welding product especially in the automotive sectors. Low power fiber laser was used to weld this non-ferrous metal where pulse wave (PW) mode was used. Double fillet lap joint was applied to weld as thin as 0.6 mm thick of AZ31B and the effect of pulsed energy on the strength was studied. Bond width, throat length, and penetration depth also was studied related to the pulsed energy which effecting the joint. Higher pulsed energy contributes to the higher fracture load with angle of irradiation lower than 3 °

INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS ...

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

INTERIOR OF WEST SPAN LOOKING WEST (SHADOW OF VERTICAL LAPS PLACED ON ZONE III; ASPHALT ZONE IX) - Honey Run Bridge, Spanning Butte Creek, bypassed section of Honey Run Road (originally Carr Hill Road), Paradise, Butte County, CA

Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

1990-01-01

Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces.

75 FR 35356 - Airworthiness Directives; The Boeing Company Model 747-100, 747-200B, and 747-200F Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-22

...-related skin cracks and corrosion of the skin panel lap joints in the fuselage upper lobe, and repair if... inspections of the fuselage skin at the upper lobe skin lap joints for cracks and evidence of corrosion, and... correct fatigue cracking and corrosion in the fuselage upper lobe skin lap joints, which could lead to...

Numerical modelling in friction lap joining of aluminium alloy and carbon-fiber-reinforced-plastic sheets

NASA Astrophysics Data System (ADS)

Das, A.; Bang, H. S.; Bang, H. S.

2018-05-01

Multi-material combinations of aluminium alloy and carbon-fiber-reinforced-plastics (CFRP) have gained attention in automotive and aerospace industries to enhance fuel efficiency and strength-to-weight ratio of components. Various limitations of laser beam welding, adhesive bonding and mechanical fasteners make these processes inefficient to join metal and CFRP sheets. Friction lap joining is an alternative choice for the same. Comprehensive studies in friction lap joining of aluminium to CFRP sheets are essential and scare in the literature. The present work reports a combined theoretical and experimental study in joining of AA5052 and CFRP sheets using friction lap joining process. A three-dimensional finite element based heat transfer model is developed to compute the temperature fields and thermal cycles. The computed results are validated extensively with the corresponding experimentally measured results.

Learning Activity Package, Algebra 93-94, LAPs 12-22.

ERIC Educational Resources Information Center

Evans, Diane

A set of 11 teacher-prepared Learning Activity Packages (LAPs) in beginning algebra, these units cover sets, properties of operations, operations over real numbers, open expressions, solution sets of equations and inequalities, equations and inequalities with two variables, solution sets of equations with two variables, exponents, factoring and…

Learning Activity Package, Physical Science 92, LAPs 1-9.

ERIC Educational Resources Information Center

Williams, G. J.

This set of nine teacher-prepared Learning Activity Packages (LAPs) for individualized instruction in physical science covers the topics of scientific equipment and procedures; measure of time, length, area, and volume; water; oxygen and oxidation; atmospheric pressure; motion; machines; carbon; and light and sound. Each unit contains a rationale…

Determination of L-AP4-bound human mGlu8 receptor amino terminal domain structure and the molecular basis for L-AP4’s group III mGlu receptor functional potency and selectivity

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

Schkeryantz, Jeffery M.; Chen, Qi; Ho, Joseph D.

Here, L-2-Amino-4-phosphonobutyric acid (L-AP4) is a known potent and selective agonist for the Group III mGlu receptors. However, it does not show any selectivity among the individual group III mGlu subtypes. In order to understand the molecular basis for this group selectivity, we solved the first human mGlu8 amino terminal domain (ATD) crystal structures in complex with L-glu and L-AP4. In comparison with other published L-glu-bound mGlu ATD structures, we have observed L-glu binds in a significantly different manner in mGlu1. Furthermore, these new structures provided evidence that both the electronic and steric nature of the distal phosphate of L-AP4more » contribute to its exquisite Group III functional agonist potency and selectivity.« less

iLAP: a workflow-driven software for experimental protocol development, data acquisition and analysis

PubMed Central

2009-01-01

Background In recent years, the genome biology community has expended considerable effort to confront the challenges of managing heterogeneous data in a structured and organized way and developed laboratory information management systems (LIMS) for both raw and processed data. On the other hand, electronic notebooks were developed to record and manage scientific data, and facilitate data-sharing. Software which enables both, management of large datasets and digital recording of laboratory procedures would serve a real need in laboratories using medium and high-throughput techniques. Results We have developed iLAP (Laboratory data management, Analysis, and Protocol development), a workflow-driven information management system specifically designed to create and manage experimental protocols, and to analyze and share laboratory data. The system combines experimental protocol development, wizard-based data acquisition, and high-throughput data analysis into a single, integrated system. We demonstrate the power and the flexibility of the platform using a microscopy case study based on a combinatorial multiple fluorescence in situ hybridization (m-FISH) protocol and 3D-image reconstruction. iLAP is freely available under the open source license AGPL from http://genome.tugraz.at/iLAP/. Conclusion iLAP is a flexible and versatile information management system, which has the potential to close the gap between electronic notebooks and LIMS and can therefore be of great value for a broad scientific community. PMID:19941647

L-Cysteine and L-AP4 microinjections in the rat caudal ventrolateral medulla decrease arterial blood pressure.

PubMed

Takemoto, Yumi

2014-12-01

The thiol amino acid L-cysteine increases arterial blood pressure (ABP) when injected into the cerebrospinal fluid space in conscious rats, indicating a pressor response to centrally acting L-cysteine. A prior synaptic membrane binding assay suggests that L-cysteine has a strong affinity for the L-2-amino-4-phosphonobutyric acid (L-AP4) binding site. The central action of L-cysteine may be vial-AP4 sensitive receptors. The present study investigated cardiovascular responses to L-cysteine and L-ap4 microinjected into the autonomic area of the caudal ventrolateral medulla (CVLM) where inhibitory neurons regulate ABP via pre-sympathetic vasomotor neurons. Both the injection of L-cysteine and L-AP4 in the CVLM sites identified with L-glutamate produced the same depressor and bradycardic responses in urethane-anesthetized rats. Neither a prior antagonist microinjection of MK801 for the N-methyl-D-aspartate (NMDA) receptor nor CNQX for the non-NMDA receptor attenuated the responses to L-cysteine, but the combination of the two receptor blocking with an additional prior injection abolished the response. In contrast, either receptor blockade alone abolished the response to L-AP4, indicating distinct mechanisms between responses to L-cysteine and L-AP4 in the CVLM. The results indicate that the CVLM is a central active site for L-cysteine's cardiovascular response. Central L-cysteine's action could be independent of the L-AP4 sensitive receptors. Cardiovascular regulation may involve endogenous L-cysteine in the CVLM. Further multidisciplinary examinations are required to elaborate on L-cysteine's functional roles in the CVLM. Copyright © 2014 Elsevier B.V. All rights reserved.

Design Methodology for Bonded-Bolted Composite Joints. Volume I. Analysis Derivations and Illustrative Solutions

DTIC Science & Technology

1982-02-01

EXPERIMENTAL EVIDENCE ...... ....... ....... ....... ... 27 2.6 LOAD REDISTRIBUTION DUE TO DISBONDS IN ADHESIVE IN STEPPED-LAP JOINTS...SINGLE FASTENER " . ;39 3.4 LOAD SHARING BETWEEN MULTIRUW FASTENERS.."."..-.."." ൴ 3.5 FAILURE CRITERIA AT FASTENER HOLES . . ... 3.6 EXPERIMENTAL ...PLASTIC C. PERFECTLY ELASTIC THROUGHOUT A. ULL PLSTC SEAR TRS•WITHOUT $1IGN REVERSAL WITHOUT S:IG13 REVERSAL IOR FULLY NEGATIVE QUIVALENT ) (OR FULLY

Viscoelastic analysis of adhesively bonded joints

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.

1981-01-01

In this paper an adhesively bonded lap joint is analyzed by assuming that the adherends are elastic and the adhesive is linearly viscoelastic. After formulating the general problem a specific example for two identical adherends bonded through a three parameter viscoelastic solid adhesive is considered. The standard Laplace transform technique is used to solve the problem. The stress distribution in the adhesive layer is calculated for three different external loads namely, membrane loading, bending, and transverse shear loading. The results indicate that the peak value of the normal stress in the adhesive is not only consistently higher than the corresponding shear stress but also decays slower.

Early evolution of comet 67P studied with the RPC-LAP onboard Rosetta

NASA Astrophysics Data System (ADS)

Miloch, Wojciech; Edberg, Niklas J. T.; Eriksson, Anders I.; Yang, Lei; Paulsson, Joakim J. P.; Wedlund, Cyril Simon; Odelstad, Elias

2016-07-01

The Rosetta mission provides the in-situ measurements of a comet that are closest to a comet's aphelion ever made. The Rosetta Plasma Consortium (RPC) is a set of five instruments on board the spacecraft that specialise in the measurements of the plasma environment of comet 67P. One of the instruments is RPC-LAP, which consists of two Langmuir Probes and can measure the density, temperature, and flow speed of the plasma in the vicinity of the comet. At the early stage of the Rosetta mission, when the spacecraft is far from the nucleus of comet 67P, the ion part of the current-voltage characteristics of RPC-LAP1 is dominated by the photoemission current which surpasses the currents from the dilute solar wind plasma. As Rosetta starts orbiting around the nucleus in September 2014, LAP1 picks up signatures of local plasma density enhancements corresponding to variations of water-group ions observed in the vicinity of the comet. With the help of current-voltage characteristics and the spacecraft potential, we identify and characterise in space and time the entering of this coma-dominated plasma. In particular we determine the transition for entering the ion dominated region characterised by the 6-hour variations in the local plasma density due to the comet rotation. This transition manifests as a steep gradient in the density with respect to the distance to the comet nucleus. We discuss these RPC-LAP results together with the corresponding measurements by other instruments to provide a comprehensive picture of the transition.

Chronic Mammalian Toxicological Effects of LAP Wastewater.

DTIC Science & Technology

1983-06-01

humped back, cyanosis, hyperactivity, ataxia, nasal exudate, chromodacryorrhea, and opisthotonos. All rats receiving LAP had red urine approximately 1...treatment, this animal had a humped appearance and was emaciated; a bloody nasal exudate was also noted. Necropsy revealed marked emphysema and moderate...16 17 9 Pigmentation, focal 0 0 1 0 0 2 Fibrosarcoma , metastatic 1 0 0 2 0 0 Neurilemoma 0 1 0 0 2 0 Duodenum Mineralization, focal 0 0 1 0 0 2

Joint Task Force Two, Test 4.1; B 52 Aircraft Data Book

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

Department 9210

1968-10-01

This volume contains plots of the aircraft position track in the target area. There are also plots of the aircraft altitude above the terrain, normal accelerations, roll angle, pitch angle & slant range from the navigation check points and the targets.

Impaired circulating CD4+ LAP+ regulatory T cells in patients with acute coronary syndrome and its mechanistic study.

PubMed

Zhu, Zheng-Feng; Meng, Kai; Zhong, Yu-Cheng; Qi, Liang; Mao, Xiao-Bo; Yu, Kun-Wu; Zhang, Wei; Zhu, Peng-Fei; Ren, Ze-Peng; Wu, Bang-Wei; Ji, Qin-Wei; Wang, Xiang; Zeng, Qiu-Tang

2014-01-01

CD4(+) latency-associated peptide (LAP)(+) regulatory T cells (Tregs) are a newly discovered T cell subset in humans and the role of these cells in patients with acute coronary syndrome (ACS) has not been explored. We designed to investigate whether circulating frequency and function of CD4(+)LAP(+) Tregs are defective in ACS. One hundred eleven ACS patients (acute myocardial infarction and unstable angina) and 117 control patients were enrolled in the study. The control patients consisted of chronic stable angina (CSA) and chest pain syndrome (CPS). The frequencies of circulating CD4(+)LAP(+) Tregs and the expression of the transmembrane protein glycoprotein-A repetitions predominant (GARP) on CD4(+) T cells were determined by flow cytometry. The function of CD4(+)LAP(+) Tregs was detected using thymidine uptake. Serum interleukin-10 (IL-10) and transforming growth factor-β protein (TGF-β) levels were detected using ELISA and expression of GARP mRNA in peripheral blood mononuclear cells (PBMCs) was measured by real time-polymerase chain reaction. We found ACS patients had a significantly lower frequency of circulating CD4(+)LAP(+) Tregs, and the function of these cells was reduced compared to controls. The expression of GARP in CD4(+) T cells and the serum levels of TGF-β in ACS patients were lower than those of control patients. The serum levels of IL-10 were similar between the two cohorts. A novel regulatory T cell subset, defined as CD4(+)LAP(+) T cells is defective in ACS patients.

32 CFR Attachment 4 to Part 855 - Sample Joint-Use Agreement

Code of Federal Regulations, 2010 CFR

2010-07-01

... facilities for training. f. Air Force-owned airfield pavements made available for use under this Agreement... jointly used by Air Force aircraft will be designed to support the type of military aircraft assigned to... Transportation Safety Board, remove crashed civil aircraft from Air Force-owned pavements or property and shall...

32 CFR Attachment 4 to Part 855 - Sample Joint-Use Agreement

Code of Federal Regulations, 2014 CFR

2014-07-01

... facilities for training. f. Air Force-owned airfield pavements made available for use under this Agreement... jointly used by Air Force aircraft will be designed to support the type of military aircraft assigned to... Transportation Safety Board, remove crashed civil aircraft from Air Force-owned pavements or property and shall...

32 CFR Attachment 4 to Part 855 - Sample Joint-Use Agreement

Code of Federal Regulations, 2011 CFR

2011-07-01

... facilities for training. f. Air Force-owned airfield pavements made available for use under this Agreement... jointly used by Air Force aircraft will be designed to support the type of military aircraft assigned to... Transportation Safety Board, remove crashed civil aircraft from Air Force-owned pavements or property and shall...

32 CFR Attachment 4 to Part 855 - Sample Joint-Use Agreement

Code of Federal Regulations, 2013 CFR

2013-07-01

... facilities for training. f. Air Force-owned airfield pavements made available for use under this Agreement... jointly used by Air Force aircraft will be designed to support the type of military aircraft assigned to... Transportation Safety Board, remove crashed civil aircraft from Air Force-owned pavements or property and shall...

32 CFR Attachment 4 to Part 855 - Sample Joint-Use Agreement

Code of Federal Regulations, 2012 CFR

2012-07-01

... facilities for training. f. Air Force-owned airfield pavements made available for use under this Agreement... jointly used by Air Force aircraft will be designed to support the type of military aircraft assigned to... Transportation Safety Board, remove crashed civil aircraft from Air Force-owned pavements or property and shall...

Automation of disbond detection in aircraft fuselage through thermal image processing

NASA Technical Reports Server (NTRS)

Prabhu, D. R.; Winfree, W. P.

1992-01-01

A procedure for interpreting thermal images obtained during the nondestructive evaluation of aircraft bonded joints is presented. The procedure operates on time-derivative thermal images and resulted in a disbond image with disbonds highlighted. The size of the 'black clusters' in the output disbond image is a quantitative measure of disbond size. The procedure is illustrated using simulation data as well as data obtained through experimental testing of fabricated samples and aircraft panels. Good results are obtained, and, except in pathological cases, 'false calls' in the cases studied appeared only as noise in the output disbond image which was easily filtered out. The thermal detection technique coupled with an automated image interpretation capability will be a very fast and effective method for inspecting bonded joints in an aircraft structure.

Monte Carlo simulation methodology for the reliabilty of aircraft structures under damage tolerance considerations

NASA Astrophysics Data System (ADS)

Rambalakos, Andreas

Current federal aviation regulations in the United States and around the world mandate the need for aircraft structures to meet damage tolerance requirements through out the service life. These requirements imply that the damaged aircraft structure must maintain adequate residual strength in order to sustain its integrity that is accomplished by a continuous inspection program. The multifold objective of this research is to develop a methodology based on a direct Monte Carlo simulation process and to assess the reliability of aircraft structures. Initially, the structure is modeled as a parallel system with active redundancy comprised of elements with uncorrelated (statistically independent) strengths and subjected to an equal load distribution. Closed form expressions for the system capacity cumulative distribution function (CDF) are developed by expanding the current expression for the capacity CDF of a parallel system comprised by three elements to a parallel system comprised with up to six elements. These newly developed expressions will be used to check the accuracy of the implementation of a Monte Carlo simulation algorithm to determine the probability of failure of a parallel system comprised of an arbitrary number of statistically independent elements. The second objective of this work is to compute the probability of failure of a fuselage skin lap joint under static load conditions through a Monte Carlo simulation scheme by utilizing the residual strength of the fasteners subjected to various initial load distributions and then subjected to a new unequal load distribution resulting from subsequent fastener sequential failures. The final and main objective of this thesis is to present a methodology for computing the resulting gradual deterioration of the reliability of an aircraft structural component by employing a direct Monte Carlo simulation approach. The uncertainties associated with the time to crack initiation, the probability of crack detection, the

Diamond machine tool face lapping machine

DOEpatents

Yetter, H.H.

1985-05-06

An apparatus for shaping, sharpening and polishing diamond-tipped single-point machine tools. The isolation of a rotating grinding wheel from its driving apparatus using an air bearing and causing the tool to be shaped, polished or sharpened to be moved across the surface of the grinding wheel so that it does not remain at one radius for more than a single rotation of the grinding wheel has been found to readily result in machine tools of a quality which can only be obtained by the most tedious and costly processing procedures, and previously unattainable by simple lapping techniques.

Ligand-Assisted Protein Structure (LAPS): An Experimental Paradigm for Characterizing Cannabinoid-Receptor Ligand-Binding Domains.

PubMed

Janero, David R; Korde, Anisha; Makriyannis, Alexandros

2017-01-01

Detailed characterization of the ligand-binding motifs and structure-function correlates of the principal GPCRs of the endocannabinoid-signaling system, the cannabinoid 1 (CB1R) and cannabinoid 2 (CB2R) receptors, is essential to inform the rational design of drugs that modulate CB1R- and CB2R-dependent biosignaling for therapeutic gain. We discuss herein an experimental paradigm termed "ligand-assisted protein structure" (LAPS) that affords a means of characterizing, at the amino acid level, CB1R and CB2R structural features key to ligand engagement and receptor-dependent information transmission. For this purpose, LAPS integrates three key disciplines and methodologies: (a) medicinal chemistry: design and synthesis of high-affinity, pharmacologically active probes as reporters capable of reacting irreversibly with particular amino acids at (or in the immediate vicinity of) the ligand-binding domain of the functionally active receptor; (b) molecular and cellular biology: introduction of discrete, conservative point mutations into the target GPCR and determination of their effect on probe binding and pharmacological activity; (c) analytical chemistry: identification of the site(s) of probe-GPCR interaction through focused, bottom-up, amino acid-level proteomic identification of the probe-receptor complex using liquid chromatography tandem mass spectrometry. Subsequent in silico methods including ligand docking and computational modeling provide supplementary data on the probe-receptor interaction as defined by LAPS. Examples of LAPS as applied to human CB2R orthosteric binding site characterization for a biarylpyrazole antagonist/inverse agonist and a classical cannabinoid agonist belonging to distinct chemical classes of cannabinergic compounds are given as paradigms for further application of this methodology to other therapeutic protein targets. LAPS is well positioned to complement other experimental and in silico methods in contemporary structural biology such

Aircraft Design Software

NASA Technical Reports Server (NTRS)

1997-01-01

Successful commercialization of the AirCraft SYNThesis (ACSYNT) tool has resulted in the creation of Phoenix Integration, Inc. ACSYNT has been exclusively licensed to the company, an outcome of a seven year, $3 million effort to provide unique software technology to a focused design engineering market. Ames Research Center formulated ACSYNT and in working with the Virginia Polytechnic Institute CAD Laboratory, began to design and code a computer-aided design for ACSYNT. Using a Joint Sponsored Research Agreement, Ames formed an industry-government-university alliance to improve and foster research and development for the software. As a result of the ACSYNT Institute, the software is becoming a predominant tool for aircraft conceptual design. ACSYNT has been successfully applied to high- speed civil transport configuration, subsonic transports, and supersonic fighters.

Combining FoxP3 and Helios with GARP/LAP markers can identify expanded Treg subsets in cancer patients.

PubMed

Abd Al Samid, May; Chaudhary, Belal; Khaled, Yazan S; Ammori, Basil J; Elkord, Eyad

2016-03-22

Regulatory T cells (Tregs) comprise numerous heterogeneous subsets with distinct phenotypic and functional features. Identifying Treg markers is critical to investigate the role and clinical impact of various Treg subsets in pathological settings, and also for developing more effective immunotherapies. We have recently shown that non-activated FoxP3-Helios+ and activated FoxP3+/-Helios+ CD4+ T cells express GARP/LAP immunosuppressive markers in healthy donors. In this study we report similar observations in the peripheral blood of patients with pancreatic cancer (PC) and liver metastases from colorectal cancer (LICRC). Comparing levels of different Treg subpopulations in cancer patients and controls, we report that in PC patients, and unlike LICRC patients, there was no increase in Treg levels as defined by FoxP3 and Helios. However, defining Tregs based on GARP/LAP expression showed that FoxP3-LAP+ Tregs in non-activated and activated settings, and FoxP3+Helios+GARP+LAP+ activated Tregs were significantly increased in both groups of patients, compared with controls. This work implies that a combination of Treg-specific markers could be used to more accurately determine expanded Treg subsets and to understand their contribution in cancer settings. Additionally, GARP-/+LAP+ CD4+ T cells made IL-10, and not IFN-γ, and levels of IL-10-secreting CD4+ T cells were elevated in LICRC patients, especially with higher tumor staging. Taken together, our results indicate that investigations of Treg levels in different cancers should consider diverse Treg-related markers such as GARP, LAP, Helios, and others and not only FoxP3 as a sole Treg-specific marker.

Live Aircraft Encounter Visualization at FutureFlight Central

NASA Technical Reports Server (NTRS)

Murphy, James R.; Chinn, Fay; Monheim, Spencer; Otto, Neil; Kato, Kenji; Archdeacon, John

2018-01-01

Researchers at the National Aeronautics and Space Administration (NASA) have developed an aircraft data streaming capability that can be used to visualize live aircraft in near real-time. During a joint Federal Aviation Administration (FAA)/NASA Airborne Collision Avoidance System flight series, test sorties between unmanned aircraft and manned intruder aircraft were shown in real-time at NASA Ames' FutureFlight Central tower facility as a virtual representation of the encounter. This capability leveraged existing live surveillance, video, and audio data streams distributed through a Live, Virtual, Constructive test environment, then depicted the encounter from the point of view of any aircraft in the system showing the proximity of the other aircraft. For the demonstration, position report data were sent to the ground from on-board sensors on the unmanned aircraft. The point of view can be change dynamically, allowing encounters from all angles to be observed. Visualizing the encounters in real-time provides a safe and effective method for observation of live flight testing and a strong alternative to travel to the remote test range.

Texture Development in a Friction Stir Lap-Welded AZ31B Magnesium Alloy

NASA Astrophysics Data System (ADS)

Naik, B. S.; Chen, D. L.; Cao, X.; Wanjara, P.

2014-09-01

The present study was aimed at characterizing the microstructure, texture, hardness, and tensile properties of an AZ31B-H24 Mg alloy that was friction stir lap welded (FSLWed) at varying tool rotational rates and welding speeds. Friction stir lap welding (FSLW) resulted in the presence of recrystallized grains and an associated hardness drop in the stir zone (SZ). Microstructural investigation showed that both the AZ31B-H24 Mg base metal (BM) and SZ contained β-Mg17Al12 and Al8Mn5 second phase particles. The AZ31B-H24 BM contained a type of basal texture (0001)<110> with the (0001) plane nearly parallel to the rolled sheet surface and <110> directions aligned in the rolling direction. FSLW resulted in the formation of another type of basal texture (0001)<100> in the SZ, where the basal planes (0001) became slightly tilted toward the transverse direction, and the prismatic planes (100) and pyramidal planes (101) exhibited a 30 deg + ( n - 1) × 60 deg rotation ( n = 1, 2, 3, …) with respect to the rolled sheet normal direction, due to the shear plastic flow near the pin surface that occurred from the intense local stirring. With increasing tool rotational rate and decreasing welding speed, the maximum intensity of the basal poles (0001) in the SZ decreased due to a higher degree of dynamic recrystallization that led to a weaker or more random texture. The tool rotational rate and welding speed had a strong effect on the failure load of FSLWed joints. A combination of relatively high welding speed (20 mm/s) and low tool rotational rate (1000 rpm) was observed to be capable of achieving a high failure load. This was attributed to the relatively small recrystallized grains and high intensity of the basal poles in the SZ arising from the low heat input as well as the presence of a small hooking defect.

Study on Fatigue Performance of Composite Bolted Joints with Bolt-Hole Delamination

NASA Astrophysics Data System (ADS)

Liu, M. J.; Yu, S.; Zhao, Q. Y.

2018-03-01

Fatigue performance of composite structure with imperfections is a challenging subject at present. Based on cohesive zone method and multi-continuum theory, delamination evolution response and fatigue life prediction of a 3D composite single-lap joint with a bolt-hole have been investigated through computer codes Abaqus and Fe-safe. Results from the comparison of a perfect composite bolted joint with another defect one indicates that a relatively small delamination damage around the bolt hole brings about significant degradation of local material performance. More notably, fatigue life of stress concentration region of composite bolted joints is highly sensitive to external loads, as an increase of 67% cyclic load amplitude leads to an decrease of 99.5% local fatigue life in this study. However, the numerical strategy for solving composite fatigue problems is meaningful to engineering works.

Experimental data on single-bolt joints in quasi isotropic graphite/polyimide laminates

NASA Technical Reports Server (NTRS)

Wichorek, G. R.

1982-01-01

Sixteen ply, quasi-isotropic laminates of Celanese Celion 6000/PMR-15 and Celion 6000/LARC-160 with a fiber orientation of (0/45/90/-45) sub 2S were evaluated. Tensile and open hole specimens were tested at room temperature to establish laminate tensile strength and net tensile strength at an unloaded bolt hole. Double lap joint specimens with a single 4.83-mm (0.19 in.) diameter bolt torqued to 1.7 N-m (15 lbf-in.) were tested in tension at temperatures of 116 K (-250F), 297 K (75F), and 589 K (600F). The joint ratios of w/d (specimen width to hole diameter) and e/d (edge distance to hole diameter) were varied from 4 to 6 and from 2 to 4, respectively. The effect of joint geometry and temperature on failure mode and joint stresses are shown. Joint stresses calculated at maximum load for each joint geometry and test temperature are reported. Joint strength in net tension, bearing, and shear out at 116 K (-250F), 297 K (75F), and 589 K (600F) are given for the Celion 6000/PMR-15 and Celion 6000/LARC-160 laminates.

Endovascular management of lap belt-related abdominal aortic injury in a 9-year-old child.

PubMed

Papazoglou, Konstantinos O; Karkos, Christos D; Kalogirou, Thomas E; Giagtzidis, Ioakeim T

2015-02-01

Blunt abdominal aortic trauma is a rare occurrence in children with only a few patients having been reported in the literature. Most such cases have been described in the context of lap belt injuries. We report a 9-year-old boy who suffered lap belt trauma to the abdomen during a high-speed road traffic accident resulting to the well-recognized pattern of blunt abdominal injury, that is, the triad of intestinal perforation, fractures of the lumbar spine, and abdominal aortic injury. The latter presented with lower limb ischemia due to dissection of the infrarenal aorta and right common iliac artery. Revascularization was achieved by endovascular means using 2 self-expanding stents in the infrarenal aorta and the right common iliac artery. This case is one of the few reports of lap belt-related acute traumatic abdominal aortic dissection in a young child and highlights the feasibility of endovascular management in the pediatric population. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints.

PubMed

Askari, Davood; Ghasemi-Nejhad, Mehrdad N

2012-08-01

The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.

Effects of vertically aligned carbon nanotubes on shear performance of laminated nanocomposite bonded joints

PubMed Central

Askari, Davood; Ghasemi-Nejhad, Mehrdad N

2012-01-01

The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests. PMID:27877502

F-35 Joint Strike Fighter Aircraft (F-35)

DTIC Science & Technology

2013-12-01

Critical Design Review; announcing the decision to terminate development of an alternate Helmet Mounted Display System (HMDS); completing the 2nd F-35B...the 100th aircraft from the production facility at Fort Worth, Texas; and resolving lingering technical design shortfalls to include the F-35C...emphasis on: regular design reviews, systems engineering discipline, software development planning with baseline review boards, and focused metrics

Fiber optics for advanced aircraft

NASA Technical Reports Server (NTRS)

Baumbick, Robert J.

1989-01-01

The increased use of composites makes the digital control more susceptible to electromagnetic effects. In order to provide the protection to the digital control additional shielding will be required as well as protective circuitry for the electronics. This results in increased weight and reduced reliability. The advantages that fiber optic technology provides for advanced aircraft applications is recognized. The use of optical signals to carry information between the aircraft and the control module provides immunity from contamination by electromagnetic sources as well as other important benefits such as reduced weight and volume resulting from the elimination of the shielding and the replacement of metal conductors with low weight glass fibers. In 1975 NASA began work to develop passive optical sensors for use with fiber optics in aircraft control systems. The problem now is to choose the best optical sensor concepts and evaluate them for use. In 1985 NASA and DOD entered into a joint program, Fiber Optic Control System Integration (FOCSI), to look at optical technology specifically for use in advanced aircraft systems. The results of this program are discussed. The conclusion of the study indicated that the use of fiber optic technology in advanced aircraft systems is feasible and desirable. The study pointed to a lack of available sensors from vendors capable of operating in the adverse environments of advanced aircraft.

Fiber optics for advanced aircraft

NASA Technical Reports Server (NTRS)

Baumbick, Robert J.

1988-01-01

The increased use of composites makes the digital control more susceptible to electromagnetic effects. In order to provide the protection to the digital control additional shielding will be required as well as protective circuitry for the electronics. This results in increased weight and reduced reliability. The advantages that fiber optic technology provides for advanced aircraft applications is recognized. The use of optical signals to carry information between the aircraft and the control module provides immunity from contamination by electromagnetic sources as well as other important benefits such as reduced weight and volume resulting from the elimination of the shielding and the replacement of metal conductors with low weight glass fibers. In 1975 NASA began work to develop passive optical sensors for use with fiber optics in aircraft control systems. The problem now is to choose the best optical sensor concepts and evaluate them for use. In 1985 NASA and DOD entered into a joint program, Fiber Optic Control System Integration (FOCSI), to look at optical technology specifically for use in advanced aircraft systems. The results of this program are discussed. The conclusion of the study indicated that the use of fiber optic technology in advanced aircraft systems is feasible and desirable. The study pointed to a lack of available sensors from vendors capable of operating in the adverse environments of advanced aircraft.

The Second Joint NASA/FAA/DOD Conference on Aging Aircraft. Pt. 1

NASA Technical Reports Server (NTRS)

Harris, Charles E. (Editor)

1999-01-01

The purpose of the Conference was to bring together world leaders in aviation safety research, aircraft design and manufacturing, fleet operation and aviation maintenance to disseminate information on current practices and advanced technologies that will assure the continued airworthiness of the aging aircraft in the military and commercial fleets. The Conference included reviews of current industry practices, assessments of future technology requirements, and status of aviation safety research. The Conference provided an opportunity for interactions among the key personnel in the research and technology development community, the original equipment manufacturers, commercial airline operators, military fleet operators, aviation maintenance, and aircraft certification and regulatory authorities. Conference participation was unrestricted and open to the international aviation community.

An N-terminal Retention Module Anchors the Giant Adhesin LapA of Pseudomonas fluorescens at the Cell Surface: A Novel Sub-family of Type I Secretion Systems.

PubMed

Smith, T Jarrod; Font, Maria E; Kelly, Carolyn M; Sondermann, Holger; O'Toole, George A

2018-02-05

LapA of Pseudomonas fluorescens Pf0-1 belongs to a diverse family of cell surface associated bacterial adhesins that are secreted via the type-1 secretion system (T1SS). We previously reported that the periplasmic protease LapG cleaves the N-terminus of LapA at a canonical dialanine motif to release the adhesin from the cell surface under conditions unfavorable to biofilm formation, thus decreasing biofilm formation. Here, we characterize LapA as the first type 1 secreted substrate that does not follow the "one-step" rule of T1SS. Rather, a novel N-terminal element, called the retention module (RM), localizes LapA at the cell surface as a secretion intermediate. Our genetic, biochemical, and molecular modeling analysis support a model wherein LapA is tethered to the cell surface through its T1SS outer membrane TolC-like pore, LapE, until LapG cleaves LapA in the periplasm. We further demonstrate this unusual retention strategy is likely conserved among LapA-like proteins, and reveals a new subclass of T1SS ABC transporters involved in transporting this group of surface-associated, LapA-like adhesins. These studies demonstrate a novel cell surface retention strategy used throughout the Proteobacteria and highlight a previously unappreciated flexibility of function for T1SS. Importance. Bacteria have evolved multiple secretion strategies to interact with their environment. For many bacteria, the secretion of cell surface associated adhesins is key for initiating contact with a preferred substratum to facilitate biofilm formation. Our work demonstrates that P. fluorescens uses a previously unrecognized secretion strategy to retain the giant adhesin LapA at its cell surface. Further, we identify likely LapA-like adhesins in various pathogenic and commensal Proteobacteria and provide phylogenetic evidence that these adhesins are secreted by a new subclass of T1SS ABC transporters. Copyright © 2018 American Society for Microbiology.

Effects of surface preparation on the long-term durability of adhesively bonded composite joints

NASA Astrophysics Data System (ADS)

Bardis, Jason Dante

The long-term durability of adhesively bonded composite joints is critical to modern aircraft structures, which are increasingly adopting bonding as an alternative option to mechanical fastening. The effects of the surface preparation of the adherends are critical, affecting initial strength, long-term durability, fracture toughness, and failure modes of bonded joints. In this study, several potential factors are evaluated, with focus on the following: (1) Effects of possible chemical contamination from release fabrics, release films, and peel plies during adherend cure. (2) Chemical and mechanical effects of abrasion on the fracture toughness and failure mode. (3) Characterization of paste and film adhesives. There are several standard test methods used to evaluate specimen fracture, but the majority concentrate on bonded metals and interlaminar composite fracture. Testing concentrated on mode I tests; a custom double cantilever beam specimen was devised and utilized, and two forms of a wedge crack test (traveling and static) were also used. Additionally, single lap shear tests were run to contrast the mode I tests. Non-destructive testing included X-ray photography of crack fronts, energy dispersive spectroscopy and X-ray photoelectron spectroscopy surface chemistry analyses, and scanning electron microscope imaging of prepared surfaces. All mode I test methods tended to be in agreement in the ranking of different surface preparation methods. Test results revealed that release agents deposited on adherend surfaces during their cure cycle prevented proper adhesion. While mechanical abrasion did improve their fracture toughness and lower their contamination greatly, the test values did not reach the levels of samples that were not contaminated before bonding, and the interfacial modes of failure did not always change to desirable modes.

Early Evolution of Comet 67P Studied with the RPC-LAP onboard Rosetta

NASA Astrophysics Data System (ADS)

Miloch, W. J.; Yang, L.; Paulsson, J. J.; Wedlund, C. S.; Odelstad, E.; Edberg, N. J. T.; Koenders, C.; Eriksson, A.

2016-12-01

In-situ measurements within the Rosetta mission allow for studies of the cometary environment at different stages of cometary evolution. The Rosetta Plasma Consortium (RPC) is a set of five instruments on board the spacecraft that specialise in the measurements of plasma environment of comet 67P. One of the instruments is RPC-LAP, which consists of two Langmuir Probes and can measure the density, temperature, and flow speed of the plasma in the vicinity of the comet. At the early stage of the Rosetta mission, when the spacecraft is far from the nucleus of comet 67P, the ion part of the current-voltage characteristics of RPC-LAP1 is dominated by the photoemission current, which surpasses the currents from the dilute solar wind plasma. As Rosetta starts orbiting around the nucleus in September 2014, LAP1 picks up signatures of local plasma density enhancements corresponding to variations of water-group ions observed in the vicinity of the comet. With the help of current-voltage characteristics and the spacecraft potential, we identify and characterise in space and time the entering of this coma-dominated, high-density plasma region. This high-density region is observed at the northern hemisphere of the comet during early activity. The transition manifests as a steep gradient in the density with respect to the distance to the comet nucleus. We discuss these RPC-LAP results together with the corresponding measurements by other instruments to provide a comprehensive picture of the transition. We show that the early cometary plasma can be seen as composed of two distinct regions: an outer region characterised by solar wind plasma and small quantities of pickup ions, and an inner region with enhanced plasma densities.

Associação entre lipid accumulation product (LAP) e hirsutismo na síndrome do ovário policístico.

PubMed

de Oliveira, Flávia Ribeiro; Rezende, Mariana Bicalho; Faria, Nícolas Figueiredo; Dias, Tomás Ribeiro Gonçalves; de Oliveira, Walter Carlos Santos; Rocha, Ana Luiza Lunardi; Cândido, Ana Lúcia

2016-02-01

Polycystic ovary syndrome (PCOS) is the most common endocrine metabolic disorder in women between menarche and menopause. Clinical hyperandrogenism is the most important diagnostic criterion of the syndrome, which manifests as hirsutism in 70% of cases. Hirsute carriers of PCOS have high cardiovascular risk. Lipid accumulation product (LAP) is an index for the evaluation of lipid accumulation in adults and the prediction of cardiovascular risk. The aim of this study was to evaluate the association between LAP and hirsutism in women with PCOS. This was a cross-sectional observational study of a secondary database, which included 263 patients who had visited the Hyperandrogenism Outpatient Clinic from November 2009 to July 2014. The exclusion criteria were patients without Ferriman-Gallwey index (FGI) and/or LAP data. We used the Rotterdam criteria for the diagnosis of PCOS. All patients underwent medical assessment followed by measurement and recording of anthropometric data and the laboratory tests for measurement of the following: thyroid-stimulating hormone, follicle-stimulating hormone, prolactin, total testosterone, sex hormone binding globulin, 17-α-hydroxyprogesterone (follicular phase), glycohemoglobin A1c, and basal insulin. In addition, the subjects underwent lipid profiling and oral glucose tolerance tests. Other laboratory measurements were determined according to clinical criteria. LAP and the homeostatic model assessment index (HOMA-IR) were calculated using the data obtained. We divided patients into two groups: the PCOS group with normal LAP (< 34.5) and the PCOS group with altered LAP (> 34.5) to compare the occurrence of hirsutism. For statistical analysis, we used SPSS Statistics for Windows® and Microsoft Excel programs, with descriptive (frequencies, percentages, means, and standard deviations) and comparative analyses (Student's t-test and Chi-square test). We considered relations significant when the p-value was ≤ 0.05. LAP was high in

Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

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

Mohammadi, J.; Behnamian, Y.; Mostafaei, A., E-mail: amir.mostafaei@gmail.com

2015-03-15

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigatemore » the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

The Introduction of Crystallographic Concepts Using Lap-Dissolve Slide Techniques.

ERIC Educational Resources Information Center

Bodner, George M.; And Others

1980-01-01

Describes a method using lap-dissolve slide techniques with two or more slide projectors focused on a single screen for presenting visual effects that show structural features in extended arrays of atoms, or ions involving up to several hundred atoms. Presents an outline of an introduction to the structures of crystalline solids. (CS)

Microstructure and Fatigue Properties of Ultrasonic Spot Welded Joints of Aluminum 5754 Alloy

NASA Astrophysics Data System (ADS)

Mirza, F. A.; Macwan, A.; Bhole, S. D.; Chen, D. L.

2016-05-01

The purpose of this investigation was to evaluate the microstructural change, lap shear tensile load, and fatigue resistance of ultrasonic spot welded joints of aluminum 5754 alloy for automotive applications. A unique "necklace"-type structure with very fine equiaxed grains was observed to form along the weld line due to the mechanical interlocking coupled with the occurrence of dynamic recrystallization. The maximum lap shear tensile strength of 85 MPa and the fatigue limit of about 0.5 kN (at 1 × 107 cycles) were achieved. The tensile fracture occurred at the Al/Al interface in the case of lower energy inputs, and at the edge of nugget zone in the case of higher energy inputs. The maximum cyclic stress for the transition of fatigue fracture mode from the transverse through-thickness crack growth to the interfacial failure increased with increasing energy input. Fatigue crack propagation was mainly characterized by the formation of fatigue striations, which usually appeared perpendicular to the fatigue crack propagation.

AIRCRAFT MAINTENANCE ENABLED JOINT CONCEPT FOR ENTRY OPERATIONS

DTIC Science & Technology

2017-04-06

approach to manpower consolidation on a scale similar to what Rivet Workforce accomplished in the 1980s and 1990s. A consolidation based on aircraft...Logistics for the AirSea Battle,” Research (Maxwell Air Force Base , Alabama: Air Force Fellows, March 2011), 19. 36 “The Aviationist » Rapid Raptor...USAF A Research Report Submitted to the Faculty In Partial Fulfillment of the Graduation Requirements Advisor: Col Daniel Runyon 6 April 2017

Construct validity of the LapVR virtual-reality surgical simulator.

PubMed

Iwata, Naoki; Fujiwara, Michitaka; Kodera, Yasuhiro; Tanaka, Chie; Ohashi, Norifumi; Nakayama, Goro; Koike, Masahiko; Nakao, Akimasa

2011-02-01

Laparoscopic surgery requires fundamental skills peculiar to endoscopic procedures such as eye-hand coordination. Acquisition of such skills prior to performing actual surgery is highly desirable for favorable outcome. Virtual-reality simulators have been developed for both surgical training and assessment of performance. The aim of the current study is to show construct validity of a novel simulator, LapVR (Immersion Medical, San Jose, CA, USA), for Japanese surgeons and surgical residents. Forty-four subjects were divided into the following three groups according to their experience in laparoscopic surgery: 14 residents (RE) with no experience in laparoscopic surgery, 14 junior surgeons (JR) with little experience, and 16 experienced surgeons (EX). All subjects executed "essential task 1" programmed in the LapVR, which consists of six tasks, resulting in automatic measurement of 100 parameters indicating various aspects of laparoscopic skills. Time required for each task tended to be inversely correlated with experience in laparoscopic surgery. For the peg transfer skill, statistically significant differences were observed between EX and RE in three parameters, including total time and average time taken to complete the procedure and path length for the nondominant hand. For the cutting skill, similar differences were observed between EX and RE in total time, number of unsuccessful cutting attempts, and path length for the nondominant hand. According to the programmed comprehensive evaluation, performance in terms of successful completion of the task and actual experience of the participants in laparoscopic surgery correlated significantly for the peg transfer (P=0.007) and cutting skills (P=0.026). The peg transfer and cutting skills could best distinguish between EX and RE. This study is the first to provide evidence that LapVR has construct validity to discriminate between novice and experienced laparoscopic surgeons.

The Myth of Jointness in Department of Defense Requirements and Major Acquisition Programs

DTIC Science & Technology

2013-06-01

cost between the two was the result of both the need to purchase much smaller quantities for the smaller number of Defense Department aircraft, and...service requirements to reach an agreement on the joint requirements of the new aircraft. The results were borderline disastrous. The second case study...completely wrong. The TFX did not originate as a joint program but was the result of then Secretary of Defense Robert McNamara’s decision to combine

Conventional box model training improves laparoscopic skills during salpingectomy on LapSim: a randomized trial.

PubMed

Akdemir, Ali; Ergenoğlu, Ahmet Mete; Yeniel, Ahmet Özgür; Sendağ, Fatih

2013-01-01

Box model trainers have been used for many years to facilitate the improvement of laparoscopic skills. However, there are limited data available on box trainers and their impact on skill acquisition, assessed by virtual reality systems. Twenty-two Postgraduate Year 1 gynecology residents with no laparoscopic experience were randomly divided into one group that received structured box model training and a control group. All residents performed a salpingectomy on LapSim before and after the training. Performances before and after the training were assessed using LapSim and were recorded using objective parameters, registered by a computer system (time, damage, and economy of motion scores). There were initially no differences between the two groups. The box trainer group showed significantly greater improvement in time (p=0.01) and economy of motion scores (p=0.001) compared with the control group post-training. The present study confirmed the positive effect of low cost box model training on laparoscopic skill acquisition as assessed using LapSim. Novice surgeons should obtain practice on box trainers and teaching centers should make efforts to establish training laboratories.

"Analysis of Van Allen Probes lapping data using Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)"

NASA Astrophysics Data System (ADS)

Gallton, D. A.; Manweiler, J. W.; Gerrard, A. J.; Cravens, T.; Lanzerotti, L. J.; Patterson, J. D.

2017-12-01

The increased frequency of the Van Allen Probes (VAP) lapping events provides a unique opportunity to examine the scaling length and structure of the magnetospheric plasma at microscales. Onboard the probes is the RBSPICE instrument, which is an energetic particle detector capable of observing ions (H+, Hen+, On+) from approximately 7 KeV upwards to values of 1 MeV. Here we provide a correlation analysis of the probes during quiet time lapping events which examines the behavior of the particle populations when the probes are within 1,000 km of separation distance, at a distance greater than 15,000 km from Earth, and where the Kp and AE magnetic indices show minimal geomagnetic activity. The correlation values of the energetic particle distributions are examined and the falloff distances associated with the tail end of the plasma distribution are calculated. We provide an overview of the initial analysis results for H during the quiet time lapping events and a discussion of the causal relationship.

Effect of Viscosity on Fuel Leakage Between Lapped Plungers and Sleeves and on the Discharge from a Pump-Injection System

NASA Technical Reports Server (NTRS)

Rothrock, A M; Marsh, E T

1935-01-01

Test data and analysis show that the rate of fuel leakage between a lapped plunger and sleeve varies directly with the density of the fuel, the diameter of the plunger, the pressure producing the leakage, and the cube of the mean clearance between the plunger and sleeve. The rate varies inversely as the length of the lapped fit and the viscosity of the fuel. With a mean clearance between the plunger and sleeve of 0.0001 inch the leakage amounts to approximately 0.2 percent of the fuel injected with gasoline and as low as 0.01 percent with diesel fuel oils. With this mean clearance an effective seal is obtained when the length of the lap is three times the diameter of the lap. The deformation of the sleeve and plunger under pressure is sufficient to change the rate of leakage appreciably from that which would be obtained if the clearance was constant under pressure.

Evaluation of Margins of Safety in Brazed Joints

NASA Technical Reports Server (NTRS)

Flom, Yury; Wang, Len; Powell, Mollie M.; Soffa, Matthew A.; Rommel, Monica L.

2009-01-01

One of the essential steps in assuring reliable performance of high cost critical brazed structures is the assessment of the Margin of Safety (MS) of the brazed joints. In many cases the experimental determination of the failure loads by destructive testing of the brazed assembly is not practical and cost prohibitive. In such cases the evaluation of the MS is performed analytically by comparing the maximum design loads with the allowable ones and incorporating various safety or knock down factors imposed by the customer. Unfortunately, an industry standard methodology for the design and analysis of brazed joints has not been developed. This paper provides an example of an approach that was used to analyze an AlBeMet 162 (38%Be-62%Al) structure brazed with the AWS BAlSi-4 (Al-12%Si) filler metal. A practical and conservative interaction equation combining shear and tensile allowables was developed and validated to evaluate an acceptable (safe) combination of tensile and shear stresses acting in the brazed joint. These allowables are obtained from testing of standard tensile and lap shear brazed specimens. The proposed equation enables the assessment of the load carrying capability of complex brazed joints subjected to multi-axial loading.

Design, fabrication & performance analysis of an unmanned aerial vehicle

NASA Astrophysics Data System (ADS)

Khan, M. I.; Salam, M. A.; Afsar, M. R.; Huda, M. N.; Mahmud, T.

2016-07-01

An Unmanned Aerial Vehicle was designed, analyzed and fabricated to meet design requirements and perform the entire mission for an international aircraft design competition. The goal was to have a balanced design possessing, good demonstrated flight handling qualities, practical and affordable manufacturing requirements while providing a high vehicle performance. The UAV had to complete total three missions named ferry flight (1st mission), maximum load mission (2nd mission) and emergency medical mission (3rd mission). The requirement of ferry flight mission was to fly as many as laps as possible within 4 minutes. The maximum load mission consists of flying 3 laps while carrying two wooden blocks which simulate cargo. The requirement of emergency medical mission was complete 3 laps as soon as possible while carrying two attendances and two patients. A careful analysis revealed lowest rated aircraft cost (RAC) as the primary design objective. So, the challenge was to build an aircraft with minimum RAC that can fly fast, fly with maximum payload, and fly fast with all the possible configurations. The aircraft design was reached by first generating numerous design concepts capable of completing the mission requirements. In conceptual design phase, Figure of Merit (FOM) analysis was carried out to select initial aircraft configuration, propulsion, empennage and landing gear. After completion of the conceptual design, preliminary design was carried out. The preliminary design iterations had a low wing loading, high lift coefficient, and a high thrust to weight ratio. To make the aircraft capable of Rough Field Taxi; springs were added in the landing gears for absorbing shock. An airfoil shaped fuselage was designed to allowed sufficient space for payload and generate less drag to make the aircraft fly fast. The final design was a high wing monoplane with conventional tail, single tractor propulsion system and a tail dragger landing gear. Payload was stored in

Highly Flexible and Planar Supercapacitors Using Graphite Flakes/Polypyrrole in Polymer Lapping Film.

PubMed

Raj, C Justin; Kim, Byung Chul; Cho, Won-Je; Lee, Won-gil; Jung, Sang-Don; Kim, Yong Hee; Park, Sang Yeop; Yu, Kook Hyun

2015-06-24

Flexible supercapacitor electrodes have been fabricated by simple fabrication technique using graphite nanoflakes on polymer lapping films as flexible substrate. An additional thin layer of conducting polymer polypyrrole over the electrode improved the surface conductivity and exhibited excellent electrochemical performances. Such capacitor films showed better energy density and power density with a maximum capacitance value of 37 mF cm(-2) in a half cell configuration using 1 M H2SO4 electrolyte, 23 mF cm(-2) in full cell, and 6 mF cm(-2) as planar cell configuration using poly(vinyl alcohol) (PVA)/phosphoric acid (H3PO4) solid state electrolyte. Moreover, the graphite nanoflakes/polypyrrole over polymer lapping film demonstrated good flexibility and cyclic stability.

Nuclear lamina genetic variants, including a truncated LAP2, in twins and siblings with nonalcoholic fatty liver disease.

PubMed

Brady, Graham F; Kwan, Raymond; Ulintz, Peter J; Nguyen, Phirum; Bassirian, Shirin; Basrur, Venkatesha; Nesvizhskii, Alexey I; Loomba, Rohit; Omary, M Bishr

2018-05-01

Nonalcoholic fatty liver disease (NAFLD) is becoming the major chronic liver disease in many countries. Its pathogenesis is multifactorial, but twin and familial studies indicate significant heritability, which is not fully explained by currently known genetic susceptibility loci. Notably, mutations in genes encoding nuclear lamina proteins, including lamins, cause lipodystrophy syndromes that include NAFLD. We hypothesized that variants in lamina-associated proteins predispose to NAFLD and used a candidate gene-sequencing approach to test for variants in 10 nuclear lamina-related genes in a cohort of 37 twin and sibling pairs: 21 individuals with and 53 without NAFLD. Twelve heterozygous sequence variants were identified in four lamina-related genes (ZMPSTE24, TMPO, SREBF1, SREBF2). The majority of NAFLD patients (>90%) had at least one variant compared to <40% of controls (P < 0.0001). When only insertions/deletions and changes in conserved residues were considered, the difference between the groups was similarly striking (>80% versus <25%; P < 0.0001). Presence of a lamina variant segregated with NAFLD independently of the PNPLA3 I148M polymorphism. Several variants were found in TMPO, which encodes the lamina-associated polypeptide-2 (LAP2) that has not been associated with liver disease. One of these, a frameshift insertion that generates truncated LAP2, abrogated lamin-LAP2 binding, caused LAP2 mislocalization, altered endogenous lamin distribution, increased lipid droplet accumulation after oleic acid treatment in transfected cells, and led to cytoplasmic association with the ubiquitin-binding protein p62/SQSTM1. Several variants in nuclear lamina-related genes were identified in a cohort of twins and siblings with NAFLD; one such variant, which results in a truncated LAP2 protein and a dramatic phenotype in cell culture, represents an association of TMPO/LAP2 variants with NAFLD and underscores the potential importance of the nuclear lamina in NAFLD

Impact injury to the pregnant female and fetus in lap belt restraint.

DOT National Transportation Integrated Search

1968-12-01

Although it has been well established that the lap (seat) belt offers considerable protection against injury or death in crash environments, there has long been controversy over the injury potential to the pregnant female. This question is of importa...

Forebody/Inlet of the Joint Strike Fighter Tested at Low Speeds

NASA Technical Reports Server (NTRS)

Johns, Albert L.

1998-01-01

As part of a national cooperative effort to develop a multinational fighter aircraft, a model of a Joint Strike Fighter concept was tested in several NASA Lewis Research Center wind tunnels at low speeds over a range of headwind velocities and model attitudes. This Joint Strike Fighter concept, which is scheduled to go into production in 2005, will greatly improve the range, capability, maneuverability, and survivability of fighter aircraft, and the production program could ultimately be worth $100 billion. The test program was a team effort between Lewis and Lockheed Martin Tactical Aircraft Systems. Testing was completed in September 1997, several weeks ahead of schedule, allowing Lockheed additional time to review the results and analysis data before the next test and resulting in significant cost savings for Lockheed. Several major milestones related to dynamic and steady-state data acquisition and overall model performance were reached during this model test. Results from this program will contribute to both the concept demonstration phase and the production aircraft.

Learning Activity Package, Physical Science. LAP Numbers 5, 6, and 7.

ERIC Educational Resources Information Center

Williams, G. J.

These three units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover the physical and chemical properties of water, dehydration of crystals, solutions, acidity, strong and weak bases, neutral properties of salts, amorphous forms of carbon, hydrocarbons, and petroleum products. Each unit contains a…

Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets

NASA Astrophysics Data System (ADS)

Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

2014-08-01

The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

Training Engineers of Joint Programs for the European Aerospace Industry.

ERIC Educational Resources Information Center

Thomas, Jurgen

1985-01-01

Examines topics and issues related to training engineers of joint programs for the European aerospace industry. Forms of cooperation, European educational systems, and skills needed to successfully work as an engineer in a joint program for the European aircraft industry are the major areas addressed. (JN)

Demonstrating damage tolerance of composite airframes

NASA Technical Reports Server (NTRS)

Poe, Clarence C., Jr.

1993-01-01

Commercial transport aircraft operating in the United States are certified by the Federal Aviation Authority to be damage tolerant. On 28 April 1988, Aloha Airlines Flight 243, a Boeing 727-200 airplane, suffered an explosive decompression of the fuselage but landed safely. This event provides very strong justification for the damage tolerant design criteria. The likely cause of the explosive decompression was the linkup of numerous small fatigue cracks that initiated at adjacent fastener holes in the lap splice joint at the side of the body. Actually, the design should have limited the damage size to less than two frame spacings (about 40 inches), but this type of 'multi-site damage' was not originally taken into account. This cracking pattern developed only in the high-time airplanes (many flights). After discovery in the fleet, a stringent inspection program using eddy current techniques was inaugurated to discover these cracks before they linked up. Because of concerns about safety and the maintenance burden, the lap-splice joints of these high-time airplanes are being modified to remove cracks and prevent new cracking; newer designs account for 'multi-site damage'.

Finite element model updating of riveted joints of simplified model aircraft structure

NASA Astrophysics Data System (ADS)

Yunus, M. A.; Rani, M. N. Abdul; Sani, M. S. M.; Shah, M. A. S. Aziz

2018-04-01

Thin metal sheets are widely used to fabricate a various type of aerospace structures because of its flexibility and easily to form into any type shapes of structure. The riveted joint has turn out to be one of the popular joint types in jointing the aerospace structures because they can be easily be disassembled, maintained and inspected. In this paper, thin metal sheet components are assembled together via riveted joints to form a simplified model of aerospace structure. However, to model the jointed structure that are attached together via the mechanical joints such as riveted joint are very difficult due to local effects. Understandably that the dynamic characteristic of the joined structure can be significantly affected by these joints due to local effects at the mating areas of the riveted joints such as surface contact, clamping force and slips. A few types of element connectors that available in MSC NATRAN/PATRAN have investigated in order to presented as the rivet joints. Thus, the results obtained in term of natural frequencies and mode shapes are then contrasted with experimental counterpart in order to investigate the acceptance level of accuracy between element connectors that are used in modelling the rivet joints of the riveted joints structure. The reconciliation method via finiteelement model updating is used to minimise the discrepancy of the initial finite element model of the riveted joined structure as close as experimental data and their results are discussed.

Aircraft and Ground Vehicle Winter Runway Friction Assessment

NASA Technical Reports Server (NTRS)

Yager, Thomas J.

1999-01-01

Some background information is given together with the scope and objectives of a 5-year, Joint Winter Runway Friction Measurement Program between the National Aeronautics & Space Administration (NASA), Transport Canada (TC), and the Federal Aviation Administration (FAA). The primary objective of this effort is to perform instrumented aircraft and ground vehicle tests aimed at identifying a common number that all the different ground vehicle devices would report. This number, denoted the International Runway Friction Index (IRFI), will be related to all types of aircraft stopping performance. The range of test equipment, the test sites, test results and accomplishments, the extent of the substantial friction database compiled, and future test plans will be described. Several related studies have also been implemented including the effects of contaminant type on aircraft impingement drag, and the effectiveness of various runway and aircraft de-icing chemical types, and application rates.

Ground based experiments on the growth and characterization of L-Arginine Phosphate (LAP) crystals

NASA Technical Reports Server (NTRS)

Rao, S. M.; Cao, C.; Batra, A. K.; Lal, R. B.; Mookherji, T. K.

1991-01-01

L-Arginine Phosphate (LAP) is a new nonlinear optical material with higher efficiency for harmonic generation compared to KDP. Crystals of LAP were grown in the laboratory from supersaturated solutions by temperature lowering technique. Investigations revealed the presence of large dislocation densities inside the crystals which are observed to produce refractive index changes causing damage at high laser powers. This is a result of the convection during crystal growth from supersaturated solutions. It is proposed to grow these crystals in a diffusion controlled growth condition under microgravity environment and compare the crystals grown in space with those grown on ground. Physical properties of the solutions needed for modelling of crystal growth are also presented.

Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

NASA Astrophysics Data System (ADS)

Patterson, Erin E.; Hovanski, Yuri; Field, David P.

2016-06-01

This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

The role of haptic feedback in laparoscopic training using the LapMentor II.

PubMed

Salkini, Mohamad W; Doarn, Charles R; Kiehl, Nicholai; Broderick, Timothy J; Donovan, James F; Gaitonde, Krishnanath

2010-01-01

Laparoscopic surgery has become the standard of care for many surgical diseases. Haptic (tactile) feedback (HFB) is considered an important component of laparoscopic surgery. Virtual reality simulation (VRS) is an alternative method to teach surgical skills to surgeons in training. Newer VRS trainers such as the Simbionix Lap Mentor II provide significantly improved tactile feedback. However, VRSs are expensive and adding HFB software adds an estimated cost of $30,000 to the commercial price. The HFB provided by the Lap Mentor II has not been validated by an independent party. We used the Simbionix Lap Mentor II in this study to demonstrate the effect of adding an HFB mechanism in the VRS trainer. The study was approved by the University of Cincinnati Institutional Review Board. Twenty laparoscopically novice medical students were enrolled. Each student was asked to perform three different tasks on the Lap Mentor II and repeat each one five times. The chosen tasks demanded significant amount of traction and counter traction. The first task was to pull leaking tubes enough and clip them. The second task was stretching a jelly plate enough to see its attachments to the floor and cut these attachments. In the third task, the trainee had to separate the gallbladder from its bed on the liver. The students were randomized into two groups to perform the tasks with and without HFB. We used accuracy, speed, and economy of movement as scales to compare the performance between the two groups. The participants also completed a simple questionnaire that highlighted age, sex, and experiences in videogame usage. The two groups were comparable in age, sex, and videogame playing. No differences in the accuracy, the economy, and the speed of hand movement were noticed. In fact, adding HFB to the Lap Mentor II simulator did not contribute to any improvement in the performance of the trainees. Interestingly, we found that videogame expert players tend to have faster and more economic

Design and fabrication of realistic adhesively bonded joints

NASA Technical Reports Server (NTRS)

Shyprykevich, P.

1983-01-01

Eighteen bonded joint test specimens representing three different designs of a composite wing chordwise bonded splice were designed and fabricated using current aircraft industry practices. Three types of joints (full wing laminate penetration, two side stepped; midthickness penetration, one side stepped; and partial penetration, scarfed) were analyzed using state of the art elastic joint analysis modified for plastic behavior of the adhesive. The static tensile fail load at room temperature was predicted to be: (1) 1026 kN/m (5860 1b/in) for the two side stepped joint; (2) 925 kN/m (5287 1b/in) for the one side stepped joint; and (3) 1330 kN/m (7600 1b/in) for the scarfed joint. All joints were designed to fail in the adhesive.

The NASA Ames integral aircraft passenger seat concept - A human engineering approach

NASA Technical Reports Server (NTRS)

Kubokawa, C. C.

1974-01-01

A new NASA Ames concept for an aircraft passenger seat has been under research and development since 1968. It includes many human-factor features that will provide protection to the passenger from vibration, jostle, and high impact. It is comfortable and safer than any of the seats presently in use. An in-depth design, fabrication, and impact analysis was conducted in order to design a seat that will maximize passenger protection in high g impacts (20 g horizontal -Gx, 36 g vertical +Gz, 16 g lateral Gy). The method for absorbing impact energy was accomplished with a combination of stretching stainless steel cables, thread breaking of stitches, hydraulic mechanism and the special Temper Form cushions. The restraint system for the seat consisted of a lap belt and shoulder harness inertia reel combination.

Helios, and not FoxP3, is the marker of activated Tregs expressing GARP/LAP.

PubMed

Elkord, Eyad; Abd Al Samid, May; Chaudhary, Belal

2015-08-21

Regulatory T cells (Tregs) are key players of immune regulation/dysregulation both in physiological and pathophysiological settings. Despite significant advances in understanding Treg function, there is still a pressing need to define reliable and specific markers that can distinguish different Treg subpopulations. Herein we show for the first time that markers of activated Tregs [latency associated peptide (LAP) and glycoprotein A repetitions predominant (GARP, or LRRC32)] are expressed on CD4+FoxP3- T cells expressing Helios (FoxP3-Helios+) in the steady state. Following TCR activation, GARP/LAP are up-regulated on CD4+Helios+ T cells regardless of FoxP3 expression (FoxP3+/-Helios+). We show that CD4+GARP+/-LAP+ Tregs make IL-10 immunosuppressive cytokine but not IFN-γ effector cytokine. Further characterization of FoxP3/Helios subpopulations showed that FoxP3+Helios+ Tregs proliferate in vitro significantly less than FoxP3+Helios- Tregs upon TCR stimulation. Unlike FoxP3+Helios- Tregs, FoxP3+Helios+ Tregs secrete IL-10 but not IFN-γ or IL-2, confirming they are bona fide Tregs with immunosuppressive characteristics. Taken together, Helios, and not FoxP3, is the marker of activated Tregs expressing GARP/LAP, and FoxP3+Helios+ Tregs have more suppressive characteristics, compared with FoxP3+Helios- Tregs. Our work implies that therapeutic modalities for treating autoimmune and inflammatory diseases, allergies and graft rejection should be designed to induce and/or expand FoxP3+Helios+ Tregs, while therapies against cancers or infectious diseases should avoid such expansion/induction.

Helios, and not FoxP3, is the marker of activated Tregs expressing GARP/LAP

PubMed Central

Elkord, Eyad; Abd Al Samid, May; Chaudhary, Belal

2015-01-01

Regulatory T cells (Tregs) are key players of immune regulation/dysregulation both in physiological and pathophysiological settings. Despite significant advances in understanding Treg function, there is still a pressing need to define reliable and specific markers that can distinguish different Treg subpopulations. Herein we show for the first time that markers of activated Tregs [latency associated peptide (LAP) and glycoprotein A repetitions predominant (GARP, or LRRC32)] are expressed on CD4+FoxP3− T cells expressing Helios (FoxP3−Helios+) in the steady state. Following TCR activation, GARP/LAP are up-regulated on CD4+Helios+ T cells regardless of FoxP3 expression (FoxP3+/−Helios+). We show that CD4+GARP+/−LAP+ Tregs make IL-10 immunosuppressive cytokine but not IFN-γ effector cytokine. Further characterization of FoxP3/Helios subpopulations showed that FoxP3+Helios+ Tregs proliferate in vitro significantly less than FoxP3+Helios− Tregs upon TCR stimulation. Unlike FoxP3+Helios− Tregs, FoxP3+Helios+ Tregs secrete IL-10 but not IFN-γ or IL-2, confirming they are bona fide Tregs with immunosuppressive characteristics. Taken together, Helios, and not FoxP3, is the marker of activated Tregs expressing GARP/LAP, and FoxP3+Helios+ Tregs have more suppressive characteristics, compared with FoxP3+Helios− Tregs. Our work implies that therapeutic modalities for treating autoimmune and inflammatory diseases, allergies and graft rejection should be designed to induce and/or expand FoxP3+Helios+ Tregs, while therapies against cancers or infectious diseases should avoid such expansion/induction. PMID:26343373

14 CFR 375.37 - Certain business aviation activities using U.S.-registered foreign civil aircraft.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Passenger ground transportation. (9) Flight planning and weather contract services. (10) An additional... flight crew for that aircraft may collect from the other joint owners of that aircraft a share of the... for the specific flight. (5) Landing fees, airport taxes, and similar assessments. (6) Customs...

14 CFR 375.37 - Certain business aviation activities using U.S.-registered foreign civil aircraft.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Passenger ground transportation. (9) Flight planning and weather contract services. (10) An additional... flight crew for that aircraft may collect from the other joint owners of that aircraft a share of the... for the specific flight. (5) Landing fees, airport taxes, and similar assessments. (6) Customs...

14 CFR 375.37 - Certain business aviation activities using U.S.-registered foreign civil aircraft.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Passenger ground transportation. (9) Flight planning and weather contract services. (10) An additional... flight crew for that aircraft may collect from the other joint owners of that aircraft a share of the... for the specific flight. (5) Landing fees, airport taxes, and similar assessments. (6) Customs...

14 CFR 375.37 - Certain business aviation activities using U.S.-registered foreign civil aircraft.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Passenger ground transportation. (9) Flight planning and weather contract services. (10) An additional... flight crew for that aircraft may collect from the other joint owners of that aircraft a share of the... for the specific flight. (5) Landing fees, airport taxes, and similar assessments. (6) Customs...

14 CFR 375.37 - Certain business aviation activities using U.S.-registered foreign civil aircraft.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Passenger ground transportation. (9) Flight planning and weather contract services. (10) An additional... flight crew for that aircraft may collect from the other joint owners of that aircraft a share of the... for the specific flight. (5) Landing fees, airport taxes, and similar assessments. (6) Customs...

Learning Activity Package, Physical Science. LAP Numbers 8, 9, 10, and 11.

ERIC Educational Resources Information Center

Williams, G. J.

These four units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover nuclear reactions, alpha and beta particles, atomic radiation, medical use of nuclear energy, fission, fusion, simple machines, Newton's laws of motion, electricity, currents, electromagnetism, Oersted's experiment, sound, light,…

Learning Activity Package, Physical Science. LAP Numbers 1, 2, 3, and 4.

ERIC Educational Resources Information Center

Williams, G. J.

These four units of the Learning Activity Packages (LAPs) for individualized instruction in physical science cover measuring techniques, operations of instruments, metric system heat, matter, energy, elements, atomic numbers, isotopes, molecules, mixtures, compounds, physical and chemical properties, liquids, solids, and gases. Each unit contains…

HSCT noise reduction technology development at GE Aircraft Engines

NASA Technical Reports Server (NTRS)

Majjigi, Rudramuni K.

1992-01-01

The topics covered include the following: High Speed Civil Transport (HSCT) exhaust nozzle design approaches; GE aircraft engine (GEAE) HSCT acoustics research; 2DCD non-IVP suppressor ejector; key sensitivities from reference aircraft; acoustic experiments; aero-mixing experimental set-up; fluid shield nozzle; HSCT Mach 2.4 flade nozzle; noise prediction; nozzle concept for GE/Boeing joint test; scale model hot core flow path modified to prevent hub-choking CFL3-D solution; HSCT exhaust nozzle status; and key acoustic technology issues for HSCT's.

HSCT noise reduction technology development at GE Aircraft Engines

NASA Astrophysics Data System (ADS)

Majjigi, Rudramuni K.

1992-04-01

The topics covered include the following: High Speed Civil Transport (HSCT) exhaust nozzle design approaches; GE aircraft engine (GEAE) HSCT acoustics research; 2DCD non-IVP suppressor ejector; key sensitivities from reference aircraft; acoustic experiments; aero-mixing experimental set-up; fluid shield nozzle; HSCT Mach 2.4 flade nozzle; noise prediction; nozzle concept for GE/Boeing joint test; scale model hot core flow path modified to prevent hub-choking CFL3-D solution; HSCT exhaust nozzle status; and key acoustic technology issues for HSCT's.

SRB/SLEEC (Solid Rocket Booster/Shingle Lap Extendible Exit Cone) feasibility study, volume 2. Appendix A: Design study for a SLEEC actuation system

NASA Technical Reports Server (NTRS)

Thompson, D. S.

1986-01-01

The results are presented of a design feasibility study of a self-contained (powered) actuation system for a Shingle Lap Extendible Exit Cone (SLEEC) for Transportation System (STS). The evolution of the SLEEC actuation system design is reviewed, the final design concept is summarized, and the results of the detailed study of the final concept of the actuation system are treated. A conservative design using proven mechanical components was established as a major program priority. The final mechanical design has a very low development risk since the components, which consist of ballscrews, gearing, flexible shaft drives, and aircraft cables, have extensive aerospace applications and a history of proven reliability. The mathematical model studies have shown that little or no power is required to deploy the SLEEC actuation system because acceleration forces and internal pressure from the rocket plume provide the required energies. A speed control brake is incorporated in the design in order to control the rate of deployment.

76 FR 31457 - Airworthiness Directives; Diamond Aircraft Industries GmbH Model DA 42 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-01

... Airworthiness Directives; Diamond Aircraft Industries GmbH Model DA 42 Airplanes AGENCY: Federal Aviation... reportedly found on DA 42 Main Landing Gear (MLG) Damper-to-Trailing Arm joints during standard maintenance... DA 42 Main Landing Gear (MLG) Damper-to-Trailing Arm joints during standard maintenance. Depending on...

The Second Joint NASA/FAA/DoD Conference on Aging Aircraft. Part 2

NASA Technical Reports Server (NTRS)

Harris, Charles E. (Editor)

1999-01-01

The purpose of the Conference was to bring together world leaders in aviation safety research, aircraft design and manufacturing, fleet operation and aviation maintenance to disseminate information on current practices and advanced technologies that will assure the continued airworthiness of the aging aircraft in the military and commercial fleets. The Conference included reviews of current industry practices, assessments of future technology requirements, and status of aviation safety research. The Conference provided an opportunity for interactions among the key personnel in the research and technology development community, the original equipment manufacturers, commercial airline operators, military fleet operators, aviation maintenance, and aircraft certification and regulatory authorities. Conference participation was unrestricted and open to the international aviation community. Appendix B contains the name and addresses of the 623 participants in the Conference.

Induction of polyploidy by nuclear fusion mechanism upon decreased expression of the nuclear envelope protein LAP2β in the human osteosarcoma cell line U2OS.

PubMed

Ben-Shoshan, Shirley Oren; Simon, Amos J; Jacob-Hirsch, Jasmine; Shaklai, Sigal; Paz-Yaacov, Nurit; Amariglio, Ninette; Rechavi, Gideon; Trakhtenbrot, Luba

2014-01-28

Polyploidy has been recognized for many years as an important hallmark of cancer cells. Polyploid cells can arise through cell fusion, endoreplication and abortive cell cycle. The inner nuclear membrane protein LAP2β plays key roles in nuclear envelope breakdown and reassembly during mitosis, initiation of replication and transcriptional repression. Here we studied the function of LAP2β in the maintenance of cell ploidy state, a role which has not yet been assigned to this protein. By knocking down the expression of LAP2β, using both viral and non-viral RNAi approaches in osteosarcoma derived U2OS cells, we detected enlarged nuclear size, nearly doubling of DNA content and chromosomal duplications, as analyzed by fluorescent in situ hybridization and spectral karyotyping methodologies. Spectral karyotyping analyses revealed that near-hexaploid karyotypes of LAP2β knocked down cells consisted of not only seven duplicated chromosomal markers, as could be anticipated by genome duplication mechanism, but also of four single chromosomal markers. Furthermore, spectral karyotyping analysis revealed that both of two near-triploid U2OS sub-clones contained the seven markers that were duplicated in LAP2β knocked down cells, whereas the four single chromosomal markers were detected only in one of them. Gene expression profiling of LAP2β knocked down cells revealed that up to a third of the genes exhibiting significant changes in their expression are involved in cancer progression. Our results suggest that nuclear fusion mechanism underlies the polyploidization induction upon LAP2β reduced expression. Our study implies on a novel role of LAP2β in the maintenance of cell ploidy status. LAP2β depleted U2OS cells can serve as a model to investigate polyploidy and aneuploidy formation by nuclear fusion mechanism and its involvement in cancerogenesis.

Aircraft and ground vehicle friction measurements obtained under winter runway conditions

NASA Technical Reports Server (NTRS)

Yager, Thomas J.

1989-01-01

Tests with specially instrumented NASA B-737 and B-727 aircraft together with several different ground friction measuring devices have been conducted for a variety of runway surface types and wetness conditions. This effort is part of the Joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions, and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow-, and ice-covered runway conditions is discussed together with ground vehicle friction data obtained under similar runway conditions. For the wet, compacted snow- and ice-covered runway conditions, the relationship between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, and surface contaminant-type are discussed. The test results indicate that use of properly maintained and calibrated ground vehicles for monitoring runway friction conditions should be encouraged particularly under adverse weather conditions.

Description of and preliminary tests results for the Joint Damping Experiment (JDX)

NASA Technical Reports Server (NTRS)

Bingham, Jeffrey G.; Folkman, Steven L.

1995-01-01

An effort is currently underway to develop an experiment titled joint Damping E_periment (JDX) to fly on the Space Shuttle as Get Away Special Payload G-726. This project is funded by NASA's IN-Space Technology Experiments Program and is scheduled to fly in July 1995 on STS-69. JDX will measure the influence of gravity on the structural damping of a three bay truss having clearance fit pinned joints. Structural damping is an important parameter in the dynamics of space structures. Future space structures will require more precise knowledge of structural damping than is currently available. The mission objectives are to develop a small-scale shuttle flight experiment that allows researchers to: (1) characterize the influence of gravity and joint gaps on structural damping and dynamic behavior of a small-scale truss model, and (2) evaluate the applicability of low-g aircraft test results for predicting on-orbit behavior. Completing the above objectives will allow a better understanding and/or prediction of structural damping occurring in a pin jointed truss. Predicting damping in joints is quite difficult. One of the important variables influencing joint damping is gravity. Previous work has shown that gravity loads can influence damping in a pin jointed truss structure. Flying this experiment as a GAS payload will allow testing in a microgravity environment. The on-orbit data (in micro-gravity) will be compared with ground test results. These data will be used to help develop improved models to predict damping due to pinned joints. Ground and low-g aircraft testing of this experiment has been completed. This paper describes the experiment and presents results of both ground and low-g aircraft tests which demonstrate that damping of the truss is dramatically influenced by gravity.

Mechanical testing and development of the helical field coil joint for the Advanced Toroidal Facility

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

Nelson, B.E.; Bryan, W.E.; Goranson, P.L.

1985-01-01

The helical field (HF) coil set for the Advanced Toroidal Facility (ATF) is an M = 12, l = 2, constant-ratio torsatron winding consisting of 2 coils, each with 14 turns of heavy copper conductor. The coils are divided into 24 identical segments to facilitate fabrication and minimize the assembly schedule. The segments are connected across through-bolted lap joints that must carry up to 124,000 A per turn for 5 s or 62,500 A steady-state. In addition, the joints must carry the high magnetic and thermal loads induced in the conductor and still fit within the basic 140- by 30-mmmore » copper envelope. Extensive testing and development were undertaken to verify and refine the basic joint design. Tests included assembly force and clamping force for various types of misalignment; joint resistance as a function of clamping force; clamp bolt relaxation due to thermal cycling; fatigue testing of full-size, multiturn joint prototypes; and low-cycle fatigue and tensile tests of annealed CDA102 copper. The required performance parameters and actual test results, as well as the final joint configuration, are presented. 2 refs., 9 figs., 4 tabs.« less

Feasibility, safety, and preliminary efficacy of Low Amplitude Seizure Therapy (LAP-ST): A proof of concept clinical trial in man.

PubMed

Youssef, Nagy A; Sidhom, Emad

2017-11-01

Current pulse amplitude used in clinical ECT may be higher than needed. Reducing pulse amplitude may improve focality of the electric field and thus cognitive adverse effects. Here we examine the feasibility, safety, and whether Low Pulse Amplitude Seizure Therapy (LAP-ST, 0.5-0.6A) minimizes cognitive adverse effects while retaining efficacy. Patients with treatment-resistant primary mood (depressive episodes) or psychotic disorders who were clinically indicated to undergo ECT were offered to be enrolled in an open-label study. The study consisted of a full acute course of LAP-ST under standard anesthesia and muscle relaxation. The primary outcome was feasibility of seizure induction. Clinical outcome measures were: time to reorientation (TRO), Mini Mental State Examination, Montgomery Aberg Depression Scale, and Brief Psychiatric Rating Scale, and Clinical Global Impression Scale. Twenty-two patients consented for enrollment in the study. LAP-ST was feasible, and all patients had seizures in the first session. Participants had a quick orientation with median TRO of 4.5min. Treatment was efficacious for both depressive and psychotic symptoms. Relatively small sample size, non-blinded, and no randomization was performed in this initial proof of concept study. This first human preliminary data of a full course of focal LAP-ST demonstrates that seizure induction is feasible. These results, although preliminary, suggest that the LAP-ST compared to the standard ECT techniques may result in less cognitive side effects, but comparable efficacy. Larger studies are needed to replicate these findings. Copyright © 2017 Elsevier B.V. All rights reserved.

Taxiing, Take-Off, and Landing Simulation of the High Speed Civil Transport Aircraft

NASA Technical Reports Server (NTRS)

Reaves, Mercedes C.; Horta, Lucas G.

1999-01-01

The aircraft industry jointly with NASA is studying enabling technologies for higher speed, longer range aircraft configurations. Higher speeds, higher temperatures, and aerodynamics are driving these newer aircraft configurations towards long, slender, flexible fuselages. Aircraft response during ground operations, although often overlooked, is a concern due to the increased fuselage flexibility. This paper discusses modeling and simulation of the High Speed Civil Transport aircraft during taxiing, take-off, and landing. Finite element models of the airframe for various configurations are used and combined with nonlinear landing gear models to provide a simulation tool to study responses to different ground input conditions. A commercial computer simulation program is used to numerically integrate the equations of motion and to compute estimates of the responses using an existing runway profile. Results show aircraft responses exceeding safe acceptable human response levels.

In-service moisture content of hardboard lap siding in southern Florida

Treesearch

C. Carll; A. Tenwolde; V. Malinauskas; M. Knaebe; P. G. Sotos

1999-01-01

To evaluate the effect of backpriming on in-service performance,hardboard lap siding from one manufacturing plant was exposed on two test buildings in southern Florida for 29 months. The two buildings were identical, except that one had 0.3 m (12-inch) roof overhangs without gutters and the other had gutters but no roof overhangs. Siding installation was the same on...

Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

NASA Technical Reports Server (NTRS)

Khan, Gufran S.; Gubarev, Mikhail; Arnold, William; Ramsey, Brian D.

2009-01-01

This paper establishes a relationship between the polishing process parameters and the generation of mid spatial-frequency error. The consideration of the polishing lap design to optimize the process in order to keep residual errors to a minimum and optimization of the process (speeds, stroke, etc.) and to keep the residual mid spatial-frequency error to a minimum, is also presented.

A Program in Air Transportation Technology (Joint University Program)

NASA Technical Reports Server (NTRS)

Stengel, Robert F.

1996-01-01

The Joint University Program on Air Transportation Technology was conducted at Princeton University from 1971 to 1995. Our vision was to further understanding of the design and operation of transport aircraft, of the effects of atmospheric environment on aircraft flight, and of the development and utilization of the National Airspace System. As an adjunct, the program emphasized the independent research of both graduate and undergraduate students. Recent principal goals were to develop and verify new methods for design and analysis of intelligent flight control systems, aircraft guidance logic for recovery from wake vortex encounter, and robust flight control systems. Our research scope subsumed problems associated with multidisciplinary aircraft design synthesis and analysis based on flight physics, providing a theoretical basis for developing innovative control concepts that enhance aircraft performance and safety. Our research focus was of direct interest not only to NASA but to manufacturers of aircraft and their associated systems. Our approach, metrics, and future directions described in the remainder of the report.

High-power Laser Welding of Thick Steel-aluminum Dissimilar Joints

NASA Astrophysics Data System (ADS)

Lahdo, Rabi; Springer, André; Pfeifer, Ronny; Kaierle, Stefan; Overmeyer, Ludger

According to the Intergovernmental Panel on Climate Change (IPCC), a worldwide reduction of CO2-emissions is indispensable to avoid global warming. Besides the automotive sector, lightweight construction is also of high interest for the maritime industry in order to minimize CO2-emissions. Using aluminum, the weight of ships can be reduced, ensuring lower fuel consumption. Therefore, hybrid joints of steel and aluminum are of great interest to the maritime industry. In order to provide an efficient lap joining process, high-power laser welding of thick steel plates (S355, t = 5 mm) and aluminum plates (EN AW-6082, t = 8 mm) is investigated. As the weld seam quality greatly depends on the amount of intermetallic phases within the joint, optimized process parameters and control are crucial. Using high-power laser welding, a tensile strength of 10 kN was achieved. Based on metallographic analysis, hardness tests, and tensile tests the potential of this joining method is presented.

Delamination failure of multilaminated adhesively bonded joints at low temperatures

NASA Astrophysics Data System (ADS)

Lee, Chi-Seung; Chun, Min-Sung; Kim, Myung-Hyun; Lee, Jae-Myung

2011-08-01

A series of experimental investigations of multilaminated joints adhesively bonded by epoxy/polyurethane (PU) glue were conducted in order to examine the delamination failure characteristics under in-plane shear loading at low temperatures. In order to observe these phenomena, a series of lap-shear tests were carried out at various low temperatures (20 °C, -110 °C and -163 °C) and various adhesion areas (15 mm × 50 mm, 30 mm × 50 mm, 50 mm × 50 mm, 75 mm × 50 mm and 100 mm × 50 mm). The test results were used to investigate the delamination and material characteristics, as well as the material properties, e.g., ultimate shear stress and shear elongation. Furthermore, the dependencies of the characteristics of multilaminated adhesively bonded joints (MABJs) on temperature and adhesion area was analyzed using the stress-strain relationship, and closed form formulas that are functions of the dependent parameters are proposed.

Pathfinder aircraft liftoff on altitude record setting flight of 71,500 feet

NASA Image and Video Library

1997-07-07

The Pathfinder aircraft has set a new unofficial world record for high-altitude flight of over 71,500 feet for solar-powered aircraft at the U.S. Navy's Pacific Missile Range Facility, Kauai, Hawaii. Pathfinder was designed and manufactured by AeroVironment, Inc, of Simi Valley, California, and was operated by the firm under a jointly sponsored research agreement with NASA's Dryden Flight Research Center, Edwards, California. Pathfinder's record-breaking flight occurred July 7, 1997. The aircraft took off at 11:34 a.m. PDT, passed its previous record altitude of 67,350 feet at about 5:45 p.m. and then reached its new record altitude at 7 p.m. The mission ended with a perfect nighttime landing at 2:05 a.m. PDT July 8. The new record is the highest altitude ever attained by a propellor-driven aircraft. Before Pathfinder, the altitude record for propellor-driven aircraft was 67,028 feet, set by the experimental Boeing Condor remotely piloted aircraft.

Investigation of defect rate of lap laser welding of stainless steel railway vehicles car body

NASA Astrophysics Data System (ADS)

Wang, Hongxiao

2015-02-01

In order to resolve the disadvantages such as poor appearance quality, poor tightness, low efficiency of resistance spot welding of stainless steel rail vehicles, partial penetration lap laser welding process was investigated widely. But due to the limitation of processing technology, there will be local incomplete fusion in the lap laser welding seam. Defect rate is the ratio of the local incomplete fusion length to the weld seam length. The tensile shear strength under different defect rate and its effect on the car body static strength are not clear. It is necessary to find the biggest defect rate by numerical analysis of effects of different defect rates on the laser welding stainless steel rail vehicle body structure strength ,and tests of laser welding shear tensile strength.

Evaluation of high temperature structural adhesives for extended service. [supersonic cruise aircraft research

NASA Technical Reports Server (NTRS)

Hill, S. G.

1981-01-01

Eight different Ti-6Al-4V surface treatments were investigated for each of 10 candidate resins. Primers (two for each resin) were studied for appropriate cure and thickness and initial evaluation of bond joints began using various combinations of the adhesive resins and surface treatments. Surface failure areas of bonded titanium coupons were analyzed by electron microscopy and surface chemical analysis techniques. Results of surface characterization and failure analysis are described for lap shear bond joints occurring with adhesive systems consisting of: (1) LARC-13 adhesive, Pasa jell surface treatment; (2) LARC-13 adhesive, 10 volt CAA treatment; (3) PPQ adhesive, 10 volt CAA treatment; and (4) PPQ adhesive, 5 volt CAA treatment. The failure analysis concentrated on the 10,000 hr 505K (450 F) exposed specimens which exhibited adhesive failure. Environmental exposure data being generated on the PPQ-10 volt CAA and the LARC-TPI-10 volt CAA adhesive systems is included.

(40)Ar/(39)Ar Age of Hornblende-Bearing R Chondrite LAP 04840

NASA Technical Reports Server (NTRS)

Righter, K.; Cosca, M.

2015-01-01

Chondrites have a complex chronology due to several variables affecting and operating on chondritic parent bodies such as radiogenic heating, pressure and temperature variation with depth, aqueous alteration, and shock or impact heating. Unbrecciated chondrites can record ages from 4.56 to 4.4 Ga that represent cooling in small parent bodies. Some brecciated chondrites exhibit younger ages (much less than 4 to 4.4 Ga) that may reflect the age of brecciation, disturbance, or shock and impact events (much less than 4 Ga). A unique R chondrite was recently found in the LaPaz Icefield of Antarctica - LAP 04840. This chondrite contains approximately 15% hornblende and trace amounts of biotite, making it the first of its kind. Studies have revealed an equigranular texture, mineral equilibria yielding equilibration near 650-700 C and 250-500 bars, hornblende that is dominantly OH-bearing (very little Cl or F), and high D/H ratios. To help gain a better understanding of the origin of this unique sample, we have measured the (40)Ar/(39)Ar age (LAP 04840 split 39).

Influence of friction stir welding parameters on titanium-aluminum heterogeneous lap joining configuration

NASA Astrophysics Data System (ADS)

Picot, Florent; Gueydan, Antoine; Hug, Éric

2017-10-01

Lap joining configuration for Friction Stir Welding process is a methodology mostly dedicated to heterogeneous bonding. This welding technology was applied to join pure titanium with pure aluminum by varying the rotation speed and the movement speed of the tool. Regardless of the process parameters, it was found that the maximum strength of the junction remains almost constant. Microstructural observations by means of Scanning Electron Microscopy and Energy Dispersive Spectrometry analysis enable to describe the interfacial join and reveal asymmetric Cold Lap Defects on the sides of the junction. Chemical analysis shows the presence of one exclusive intermetallic compound through the interface identified as TiAl3. This compound is responsible of the crack spreading of the junction during the mechanical loading. The original version of this article supplied to AIP Publishing contained an accidental inversion of the authors, names. An updated version of this article, with the authors names formatted correctly was published on 20 October 2017.

A new and specific non-NMDA receptor antagonist, FG 9065, blocks L-AP4-evoked depolarization in rat cerebral cortex.

PubMed

Sheardown, M J

1988-04-13

L(+)-AP4 (2-amino-4-phosphonobutyrate) depolarized slices of rat cerebral cortex, when applied following a 2 min priming application of quisqualate. This response diminishes with time and is not seen after NMDA application. A new selective non-N-methyl-D-aspartate (NMDA) antagonist, 6-cyano-7-nitro-2,3-dihydroxyquinoxaline (FG 9065), inhibits the L(+)-AP4 depolarization. It is argued that the response is mediated indirectly by postsynaptic quisqualate receptors.

Positive correlation between motion analysis data on the LapMentor virtual reality laparoscopic surgical simulator and the results from videotape assessment of real laparoscopic surgeries.

PubMed

Matsuda, Tadashi; McDougall, Elspeth M; Ono, Yoshinari; Hattori, Ryohei; Baba, Shiro; Iwamura, Masatsugu; Terachi, Toshiro; Naito, Seiji; Clayman, Ralph V

2012-11-01

We studied the construct validity of the LapMentor, a virtual reality laparoscopic surgical simulator, and the correlation between the data collected on the LapMentor and the results of video assessment of real laparoscopic surgeries. Ninety-two urologists were tested on basic skill tasks No. 3 (SK3) to No. 8 (SK8) on the LapMentor. They were divided into three groups: Group A (n=25) had no experience with laparoscopic surgeries as a chief surgeon; group B (n=33) had <35 experiences; and group C (n=34) had ≥35 experiences. Group scores on the accuracy, efficacy, and time of the tasks were compared. Forty physicians with ≥20 experiences supplied unedited videotapes showing a laparoscopic nephrectomy or an adrenalectomy in its entirety, and the videos were assessed in a blinded fashion by expert referees. Correlations between the videotape score (VS) and the performances on the LapMentor were analyzed. Group C showed significantly better outcomes than group A in the accuracy (SK5) (P=0.013), efficacy (SK8) (P=0.014), or speed (SKs 3 and 8) (P=0.009 and P=0.002, respectively) of the performances of LapMentor. Group B showed significantly better outcomes than group A in the speed and efficacy of the performances in SK8 (P=0.011 and P=0.029, respectively). Analyses of motion analysis data of LapMentor demonstrated that smooth and ideal movement of instruments is more important than speed of the movement of instruments to achieve accurate performances in each task. Multiple linear regression analysis indicated that the average score of the accuracy in SK4, 5, and 8 had significant positive correlation with VS (P=0.01). This study demonstrated the construct and predictive validity of the LapMentor basic skill tasks, supporting their possible usefulness for the preclinical evaluation of laparoscopic skills.

Research on assessment of bolted joint state using elastic wave propagation

NASA Astrophysics Data System (ADS)

Kędra, R.; Rucka, M.

2015-07-01

The work contains results of experimental investigation of elastic wave propagation in a bolted single-lap joint. Tests were carried out for the excitation perpendicular to the connection plane. In experimental studies, PZT transducers were used for both excitation and registration of ultrasonic waves. The analyses took into account varying contact conditions between the elements of the connection depending on the value of the prestressing force. The influence of loosening/tightening of bolts on the energy dissipation was analysed. The experimental results proved the influence of bolt torque on quantitative characteristics of the signals. To improve the diagnostic possibilities only the initial parts of signals were analysed.

Lipid Accumulation Product (LAP) and Visceral Adiposity Index (VAI) as Markers of Insulin Resistance and Metabolic Associated Disturbances in Young Argentine Women with Polycystic Ovary Syndrome.

PubMed

Abruzzese, Giselle A; Cerrrone, Gloria E; Gamez, Juan M; Graffigna, Mabel N; Belli, Susana; Lioy, Gustavo; Mormandi, Eduardo; Otero, Patricia; Levalle, Oscar A; Motta, Alicia B

2017-01-01

Polycystic ovary syndrome (PCOS) is an endocrine disorder. PCOS women are at high risk of developing insulin resistance (IR) and cardiovascular disorders since young age. We aimed to study the reliability of lipid accumulation product (LAP) and visceral adiposity index (VAI) as markers of metabolic disturbances (MD) associated with IR in young reproductive aged PCOS patients. We also evaluated the association between LAP and VAI and the presence of hyperandrogenism. In a cross-sectional study, 110 PCOS patients and 88 control women (18-35 years old) were recruited. PCOS patients were divided into 2 groups, as hyperandrogenic and non-hyperandrogenic considering the signs of hyperandrogenism (clinical or biochemical). Anthropometric measurements were taken and blood samples collected. Metabolic and anthropometric characteristics and their association with IR and associated MD were evaluated and LAP and VAI were calculated. LAP and VAI were compared with TC/HDL-c and TG/HDL-c to define the best markers of MD in this population. Independently of the phenotype, young PCOS patients showed high IR and dyslipidemia. Both LAP and VAI showed to be more effective markers to assess MD and IR in these young women than TG/HDL-c or TC/HDL-c [cut-off values: LAP: 18.24 (sensitivity: 81.43% specificity: 73.49%), positive predictive value (PPV): 75.0%, negative predictive value (NPV): 77.27%, VAI: 2.19 (sensitivity: 81.16% specificity: 72.15% PPV: 74.65% NPV: 72.22%)]. LAP and VAI are representative markers to assess MD associated with IR in young PCOS patients. All PCOS patients, independently of their androgenic condition, showed high metabolic risk. © Georg Thieme Verlag KG Stuttgart · New York.

How Should the Joint Force Handle the Command and Control of Unmanned Aircraft Systems?

DTIC Science & Technology

2008-11-18

personnel, and control apparatus. Collectively these are the unmanned aircraft system (UAS). The outputs of a UAS can range from full motion video ...reconnaissance aircraft, like the pilotless Predator drone that provides real-time surveillance video to the battlefield.”55 He continued, “While...www.foxnews.com/story/0,2933,351964,00.html [accessed July 7, 2008]. Baldor, Lolita C. Associated Press. “Increased UAV Reliance Evident in 2009 Budget

75 FR 81427 - Airworthiness Directives; The Boeing Company Model 747-200C, -200F, -400, -400D, and -400F Series...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-28

.... This AD results from a structural review of affected skin lap joints for widespread fatigue damage. We are issuing this AD to prevent fatigue cracking in certain lap joints, which could result in rapid... operation beyond 15,000 total flight cycles after doing the proposed modification. Boeing stated that...

75 FR 61977 - Airworthiness Directives; The Boeing Company Model 747-100, 747-200B, and 747-200F Series Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-10-07

... fatigue-related skin cracks and corrosion of the skin panel lap joints in the fuselage upper lobe, and... of corrosion, and related investigative and corrective actions. This AD reduces the maximum interval... and correct fatigue cracking and corrosion in the fuselage upper lobe skin lap joints, which could...

Lap time simulation and design optimisation of a brushed DC electric motorcycle for the Isle of Man TT Zero Challenge

NASA Astrophysics Data System (ADS)

Dal Bianco, N.; Lot, R.; Matthys, K.

2018-01-01

This works regards the design of an electric motorcycle for the annual Isle of Man TT Zero Challenge. Optimal control theory was used to perform lap time simulation and design optimisation. A bespoked model was developed, featuring 3D road topology, vehicle dynamics and electric power train, composed of a lithium battery pack, brushed DC motors and motor controller. The model runs simulations over the entire ? or ? of the Snaefell Mountain Course. The work is validated using experimental data from the BX chassis of the Brunel Racing team, which ran during the 2009 to 2015 TT Zero races. Optimal control is used to improve drive train and power train configurations. Findings demonstrate computational efficiency, good lap time prediction and design optimisation potential, achieving a 2 minutes reduction of the reference lap time through changes in final drive gear ratio, battery pack size and motor configuration.

Performance of lap splices in large-scale column specimens affected by ASR and/or DEF.

DOT National Transportation Integrated Search

2012-06-01

This research program conducted a large experimental program, which consisted of the design, construction, : curing, deterioration, and structural load testing of 16 large-scale column specimens with a critical lap splice : region, and then compared ...

Creation of an Aeronautical Capstone Design Project Program at Ohio State University

DTIC Science & Technology

2014-12-08

Equation 12 below. As Figure 35 shows, a single adhesively bonded lap joint is considered. The epoxy only sees a load in the axial direction. In...lap joint [1] = = ( ) 12 =stress distribution factor = applied load in the axial direction ...Figure 11. The joints are designed to handle the bending loads of horizontal, vertical and angled deployment and are designed to directly load the carbon

Statistical Investigation of the Effect of Process Parameters on the Shear Strength of Metal Adhesive Joints

NASA Astrophysics Data System (ADS)

Rajkumar, Goribidanur Rangappa; Krishna, Munishamaih; Narasimhamurthy, Hebbale Narayanrao; Keshavamurthy, Yalanabhalli Channegowda

2017-06-01

The objective of the work was to optimize sheet metal joining parameters such as adhesive material, adhesive thickness, adhesive overlap length and surface roughness for single lap joint of aluminium sheet shear strength using robust design. An orthogonal array, main effect plot, signal-to-noise ratio and analysis of variance were employed to investigate the shear strength of the joints. The statistical result shows vinyl ester is best candidate among other two polymers viz. epoxy and polyester due to its low viscosity value compared to other two polymers. The experiment results shows that the adhesive thickness 0.6 mm, overlap length 50 mm and surface roughness 2.12 µm for obtained maximum shear strength of Al sheet joints. The ANOVA result shows one of the most significant factors is overlap length which affect joint strength in addition to adhesive thickness, adhesive material, and surface roughness. A confirmation test was carried out as the optimal combination of parameters will not match with the any of the experiments in the orthogonal array.

Device for measuring hole elongation in a bolted joint

NASA Technical Reports Server (NTRS)

Wichorek, Gregory R. (Inventor)

1987-01-01

A device to determine the operable failure mode of mechanically fastened lightweight composite joints by measuring the hole elongation of a bolted joint is disclosed. The double-lap joint test apparatus comprises a stud, a test specimen having a hole, two load transfer plates, and linear displacement measuring instruments. The test specimen is sandwiched between the two load transfer plates and clamped together with the stud. Spacer washers are placed between the test specimen and each load transfer plate to provide a known, controllable area for the determination of clamping forces around the hole of the specimen attributable to bolt torque. The spacer washers also provide a gap for the mounting of reference angles on each side of the test specimen. Under tensile loading, elongation of the hole of the test specimen causes the stud to move away from the reference angles. This displacement is measured by the voltage output of two linear displacement measuring instruments that are attached to the stud and remain in contact with the reference angles throughout the tensile loading. The present invention obviates previous problems in obtaining specimen deformation measurements by monitoring the reference angles to the test specimen and the linear displacement measuring instruments to the stud.

Objective assessment of gynecologic laparoscopic skills using the LapSimGyn virtual reality simulator.

PubMed

Larsen, C R; Grantcharov, T; Aggarwal, R; Tully, A; Sørensen, J L; Dalsgaard, T; Ottesen, B

2006-09-01

Safe realistic training and unbiased quantitative assessment of technical skills are required for laparoscopy. Virtual reality (VR) simulators may be useful tools for training and assessing basic and advanced surgical skills and procedures. This study aimed to investigate the construct validity of the LapSimGyn VR simulator, and to determine the learning curves of gynecologists with different levels of experience. For this study, 32 gynecologic trainees and consultants (juniors or seniors) were allocated into three groups: novices (0 advanced laparoscopic procedures), intermediate level (>20 and <60 procedures), and experts (>100 procedures). All performed 10 sets of simulations consisting of three basic skill tasks and an ectopic pregnancy program. The simulations were carried out on 3 days within a maximum period of 2 weeks. Assessment of skills was based on time, economy of movement, and error parameters measured by the simulator. The data showed that expert gynecologists performed significantly and consistently better than intermediate and novice gynecologists. The learning curves differed significantly between the groups, showing that experts start at a higher level and more rapidly reach the plateau of their learning curve than do intermediate and novice groups of surgeons. The LapSimGyn VR simulator package demonstrates construct validity on both the basic skills module and the procedural gynecologic module for ectopic pregnancy. Learning curves can be obtained, but to reach the maximum performance for the more complex tasks, 10 repetitions do not seem sufficient at the given task level and settings. LapSimGyn also seems to be flexible and widely accepted by the users.

One hundred cases of laparoscopic subtotal hysterectomy using the PK and Lap Loop systems.

PubMed

Erian, John; El-Toukhy, Tarek; Chandakas, Stefanos; Theodoridis, Theo; Hill, Nicholas

2005-01-01

To evaluate the safety and short-term outcomes of laparoscopic subtotal hysterectomy using the PK and Lap Loop systems. Prospective observational study (Canadian Task Force classification II-2). Princess Royal University and Chelsfield Park Hospitals, Kent, UK. One hundred women who underwent laparoscopic subtotal hysterectomy for menorrhagia from February 2003 through July 2004. The procedure was performed using the Plasma Kinetic (PK) system to seal the vascular pedicles and the Lap Loop system to separate the uterus at the level of the internal os. The uterus was removed from the abdominal cavity mainly by morcellation or posterior colpotomy. Of 100 patients, 59 were operated on as outpatients. Mean patient age was 44.6 years, median parity was 2, mean body mass index was 26.8, and mean duration of symptoms was 4 years. Clinically, the uterus was enlarged in 70 patients, and preoperative ultrasound scanning suggested the presence of uterine myomas in 42 patients. In addition to hysterectomy, 47 patients had concomitant pelvic surgery. The mean total operating time was 45.5 minutes, and mean estimated blood loss was 114 mL. The overall major complication rate was 2%; two patients required blood transfusion after surgery. There were no bowel or urinary tract injuries, unintended laparotomy, return to operating room, or anesthetic complications. At follow-up, all patients were satisfied with surgery. Laparoscopic subtotal hysterectomy using the PK and Lap Loop systems for treatment of therapy-resistant menorrhagia is safe, can be performed as an outpatient procedure, and is associated with reduced operating time and high patient satisfaction.

Design, Static Analysis And Fabrication Of Composite Joints

NASA Astrophysics Data System (ADS)

Mathiselvan, G.; Gobinath, R.; Yuvaraja, S.; Raja, T.

2017-05-01

The Bonded joints will be having one of the important issues in the composite technology is the repairing of aging in aircraft applications. In these applications and also for joining various composite material parts together, the composite materials fastened together either using adhesives or mechanical fasteners. In this paper, we have carried out design, static analysis of 3-D models and fabrication of the composite joints (bonded, riveted and hybrid). The 3-D model of the composite structure will be fabricated by using the materials such as epoxy resin, glass fibre material and aluminium rivet for preparing the joints. The static analysis was carried out with different joint by using ANSYS software. After fabrication, parametric study was also conducted to compare the performance of the hybrid joint with varying adherent width, adhesive thickness and overlap length. Different joint and its materials tensile test result have compared.

Improving Critical Thinking Skills Using Learning Model Logan Avenue Problem Solving (LAPS)-Heuristic

ERIC Educational Resources Information Center

Anggrianto, Desi; Churiyah, Madziatul; Arief, Mohammad

2016-01-01

This research was conducted in order to know the effect of Logan Avenue Problem Solving (LAPS)-Heuristic learning model towards critical thinking skills of students of class X Office Administration (APK) in SMK Negeri 1 Ngawi, East Java, Indonesia on material curve and equilibrium of demand and supply, subject Introduction to Economics and…

Ground truth report 1975 Phoenix microwave experiment. [Joint Soil Moisture Experiment

NASA Technical Reports Server (NTRS)

Blanchard, B. J.

1975-01-01

Direct measurements of soil moisture obtained in conjunction with aircraft data flights near Phoenix, Arizona in March, 1975 are summarized. The data were collected for the Joint Soil Moisture Experiment.

Stresses in adhesively bonded joints - A closed-form solution

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.; Aydinoglu, M. N.

1981-01-01

The general plane strain problem of adhesively bonded structures consisting of two different, orthotropic adherends is considered, under the assumption that adherend thicknesses are constant and small in relation to the lateral dimensions of the bonded region, so that they may be treated as plates. The problem is reduced to a system of differential equations for the adhesive stresses which is solved in closed form, with a single lap joint and a stiffened plate under various loading conditions being considered as examples. It is found that the plate theory used in the analysis not only predicts the correct trend for adhesive stresses but gives surprisingly accurate results, the solution being obtained by assuming linear stress-strain relations for the adhesive.

Joint University Program for Air Transportation Research, 1986

NASA Technical Reports Server (NTRS)

Morrell, Frederick R. (Compiler)

1988-01-01

The research conducted under the NASA/FAA sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA and the FAA, one each with the Mass. Inst. of Tech., Ohio Univ., and Princeton Univ. Completed works, status reports, and bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of activities is presented.

Application of slender wing benefits to military aircraft

NASA Technical Reports Server (NTRS)

Polhamus, E. C.

1983-01-01

A review is provided of aerodynamic research conducted at the Langley Research Center with respect to the application of slender wing benefits in the design of high-speed military aircraft, taking into account the supersonic performance and leading-edge vortex flow associated with very highly sweptback wings. The beginning of the development of modern classical swept wing jet aircraft is related to the German Me 262 project during World War II. In the U.S., a theoretical study conducted by Jones (1945) pointed out the advantages of the sweptback wing concept. Developments with respect to variable sweep wings are discussed, taking into account early research in 1946, a joint program of the U.S. with the United Kingdom, the tactical aircraft concept, and the important part which the Langley variable-sweep research program played in the development of the F-111, F-14, and B-1. Attention is also given to hybrid wings, vortex flow theory development, and examples of flow design technology.

76 FR 66207 - Airworthiness Directives; Sikorsky Aircraft Corporation (Sikorsky) Model S-92A Helicopters

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-26

... (RFM) as follows: (a) By making pen and ink changes, insert into the Operating Limitations section... alternative methods of compliance. (d) The Joint Aircraft System/Component (JASC) Code is 7200: Engine...

The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints

PubMed Central

Yang, Jingwei; Cao, Biao; Lu, Qinghua

2017-01-01

The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed. PMID:28772553

The Effect of Welding Energy on the Microstructural and Mechanical Properties of Ultrasonic-Welded Copper Joints.

PubMed

Yang, Jingwei; Cao, Biao; Lu, Qinghua

2017-02-16

The effects of welding energy on the mechanical and microstructural characteristics of ultrasonic-welded pure copper plates were investigated. Complex dynamic recrystallization and grain growth occurred inside the weld zone during ultrasonic welding. At a low welding energy, a thin band of straight weld interfaces was observed and had an ultra-fine grain structure. With an increase in welding energy, the weld interface progressively changed from flat to sinusoidal, and eventually turned into a convoluted wavy pattern, bearing similarities to shear instabilities, as observed in fluid dynamics. The lap shear load of the joints initially increased and then remained stable as the welding energy increased. The tensile characteristics of the joints significantly depended on the development of plastic deformation at the interface. The influence of the microstructure on the hardness was also discussed.

Positive Correlation Between Motion Analysis Data on the LapMentor Virtual Reality Laparoscopic Surgical Simulator and the Results from Videotape Assessment of Real Laparoscopic Surgeries

PubMed Central

McDougall, Elspeth M.; Ono, Yoshinari; Hattori, Ryohei; Baba, Shiro; Iwamura, Masatsugu; Terachi, Toshiro; Naito, Seiji; Clayman, Ralph V.

2012-01-01

Abstract Purpose We studied the construct validity of the LapMentor, a virtual reality laparoscopic surgical simulator, and the correlation between the data collected on the LapMentor and the results of video assessment of real laparoscopic surgeries. Materials and Methods Ninety-two urologists were tested on basic skill tasks No. 3 (SK3) to No. 8 (SK8) on the LapMentor. They were divided into three groups: Group A (n=25) had no experience with laparoscopic surgeries as a chief surgeon; group B (n=33) had <35 experiences; and group C (n=34) had ≥35 experiences. Group scores on the accuracy, efficacy, and time of the tasks were compared. Forty physicians with ≥20 experiences supplied unedited videotapes showing a laparoscopic nephrectomy or an adrenalectomy in its entirety, and the videos were assessed in a blinded fashion by expert referees. Correlations between the videotape score (VS) and the performances on the LapMentor were analyzed. Results Group C showed significantly better outcomes than group A in the accuracy (SK5) (P=0.013), efficacy (SK8) (P=0.014), or speed (SKs 3 and 8) (P=0.009 and P=0.002, respectively) of the performances of LapMentor. Group B showed significantly better outcomes than group A in the speed and efficacy of the performances in SK8 (P=0.011 and P=0.029, respectively). Analyses of motion analysis data of LapMentor demonstrated that smooth and ideal movement of instruments is more important than speed of the movement of instruments to achieve accurate performances in each task. Multiple linear regression analysis indicated that the average score of the accuracy in SK4, 5, and 8 had significant positive correlation with VS (P=0.01). Conclusions This study demonstrated the construct and predictive validity of the LapMentor basic skill tasks, supporting their possible usefulness for the preclinical evaluation of laparoscopic skills. PMID:22642549

75 FR 13046 - Airworthiness Directives; The Boeing Company Model 747-200C, -200F, -400, -400D, and -400F Series...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-18

.... This proposed AD results from a structural review of affected skin lap joints for widespread fatigue damage. We are proposing this AD to prevent fatigue cracking in certain lap joints, which could result in...., Washington, DC 20590, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. For service...

Strength and Performance Enhancement of Bonded Joints by Spatial Tailoring of Adhesive Compliance via 3D Printing.

PubMed

Kumar, S; Wardle, Brian L; Arif, Muhamad F

2017-01-11

Adhesive bonding continues to emerge as a preferred route for joining materials with broad applications including advanced structures, microelectronics, biomedical systems, and consumer goods. Here, we study the mechanics of deformation and failure of tensile-loaded single-lap joints with a compliance-tailored adhesive. Tailoring of the adhesive compliance redistributes stresses and strains to reduce both shear and peel concentrations at the ends of the adhesive that determine failure of the joint. Utilizing 3D printing, the modulus of the adhesive is spatially varied along the bondlength. Experimental strength testing, including optical strain mapping, reveals that the strain redistribution results in a greater than 100% increase in strength and toughness concomitant with a 50% increase in strain-to-break while maintaining joint stiffness. The tailoring demonstrated here is immediately realizable in a broad array of 3D printing applications, and the level of performance enhancement suggests that compliance tailoring of the adhesive is a generalizable route for achieving superior performance of joints in other applications, such as advanced structural composites.

Commercial Aircraft Integrated Vehicle Health Management Study

NASA Technical Reports Server (NTRS)

Reveley, Mary S.; Briggs, Jeffrey L.; Evans, Joni K.; Jones, Sharon Monica; Kurtoglu, Tolga; Leone, Karen M.; Sandifer, Carl E.; Thomas, Megan A.

2010-01-01

Statistical data and literature from academia, industry, and other government agencies were reviewed and analyzed to establish requirements for fixture work in detection, diagnosis, prognosis, and mitigation for IVHM related hardware and software. Around 15 to 20 percent of commercial aircraft accidents between 1988 and 2003 involved inalftfnctions or failures of some aircraft system or component. Engine and landing gear failures/malfunctions dominate both accidents and incidents. The IVI vl Project research technologies were found to map to the Joint Planning and Development Office's National Research and Development Plan (RDP) as well as the Safety Working Group's National Aviation Safety Strategic. Plan (NASSP). Future directions in Aviation Technology as related to IVHlvl were identified by reviewing papers from three conferences across a five year time span. A total of twenty-one trend groups in propulsion, aeronautics and aircraft categories were compiled. Current and ftiture directions of IVHM related technologies were gathered and classified according to eight categories: measurement and inspection, sensors, sensor management, detection, component and subsystem monitoring, diagnosis, prognosis, and mitigation.

Playground slide-related injuries in preschool children: increased risk of lower extremity injuries when riding on laps.

PubMed

Jennissen, Charles A; Koos, Maggie; Denning, Gerene

2018-04-10

The purpose of this study was to better understand the factors associated with playground slide-related injuries in preschool children and to test the hypothesis that riding on laps increases the likelihood of lower extremity injuries. Playground slide-related injuries (product code 1242) in children ≤5 years of age treated in emergency departments from 2002 to 2015 were identified (N = 12,686) using the U.S. Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS). Descriptive and comparative analyses, including chi-square testing and binary logistic regression, were performed. Based on NEISS stratified national sampling estimates, over 350,000 children ≤5 years of age were injured on slides from 2002 to 2015. Overall, 59% of the children were male, and 65% were white. Almost 60% of injuries occurred in parks or other public areas. The most frequent diagnosis was a fracture (36%); lacerations were 19% of the injuries. A higher proportion of musculoskeletal injuries were seen in toddlers < 3 years old as compared to those 3-5 years of age (p < 0.001). Injuries to the lower extremities increased in frequency as age decreased, whereas injuries to the upper extremities and head/neck/face were more common in older preschoolers. Children < 3 years of age were 12 times more likely to be identified from narratives as being on another person's lap at the time of injury. Children identified as being on a lap had an increased odds of injury to the lower extremity than to other body parts (OR 43.0, 95% confidence interval (CI) 32.0-58.0), and of lower leg/ankle fracture than fractures elsewhere (OR 49.5, 95% CI 31.7-77.4). Decreasing age was associated with a higher likelihood of being identified as sliding down on another person's lap and a higher likelihood of lower extremity injuries. Healthcare providers should be mindful of the potential for these slide-related injuries as they can result in a toddler's fracture of

The Joint Winter Runway Friction Measurement Program: NASA Perspective

NASA Technical Reports Server (NTRS)

Yager, Thomas J.

1996-01-01

Some background information is given together with the scope and objectives of the 5-year, Joint National Aeronautics & Space Administration (NASA)/Transport Canada (TC)/Federal Aviation Administration (FAA) Winter Runway Friction Measurement Program. The range of the test equipment, the selected test sites and a tentative test program schedule are described. NASA considers the success of this program critical in terms of insuring adequate ground handling performance capability in adverse weather conditions for future aircraft being designed and developed as well as improving the safety of current aircraft ground operations.

Role of C/EBPβ-LAP and C/EBPβ-LIP in early adipogenic differentiation of human white adipose-derived progenitors and at later stages in immature adipocytes.

PubMed

Lechner, Stefan; Mitterberger, Maria C; Mattesich, Monika; Zwerschke, Werner

2013-01-01

We investigated the role of the major isoforms of CCAAT enhancer binding protein β (C/EBPβ), C/EBPβ-LAP and C/EBPβ-LIP, in adipogenesis of human white adipose-derived stromal/progenitor cells (ASC). C/EBPβ gene expression was transiently induced early in adipogenesis. At later stages, in immature adipocytes, the C/EBPβ mRNA and protein levels declined. The C/EBPβ-LIP protein steady-state level decreased considerably stronger than the C/EBPβ-LAP level and the C/EBPβ-LIP half-life was significantly shorter than the C/EBPβ-LAP half-life. The turn-over of both C/EBPβ-isoforms was regulated by ubiquitin/proteasome-dependent degradation. These data suggest that the protein stability of the C/EBPβ-isoforms is differentially regulated in the course of adipogenesis and in immature adipocytes. Constitutive overexpression of C/EBPβ-LIP had antiadipogenic activity in human ASC. C/EBPβ-LAP, which promotes adipogenesis in mouse 3T3-L1 preadipocytes by directly activating expression of the adipogenic keyregulator PPARγ2, induced the expression of PPARγ2 and of the adipocyte differentiation gene product FABP4 in confluent ASC in the absence of adipogenic hormones. At later stages after hormone cocktail-induced adipogenesis, in immature adipocytes, constitutive overexpression of C/EBPβ-LAP led to reduced expression of PPARγ2 and FABP4, C/EBPα expression was downregulated and the expression of the adipocyte differentiation gene products adiponectin and leptin was impaired. These findings suggest that constitutive overexpression of C/EBPβ-LAP induces adipogenesis in human ASC and negatively regulates the expression of adipogenic regulators and certain adipocyte differentiation gene products in immature adipocytes. We conclude the regulation of both C/EBPβ gene expression and C/EBPβ-LIP and C/EBPβ-LAP protein turn-over plays an important role for the expression of adipogenic regulators and/or adipocyte differentiation genes in early adipogenic differentiation of

Bonded composite to metal scarf joint performance in an aircraft landing gear drag strut. [for Boeing 747 aircraft

NASA Technical Reports Server (NTRS)

Howell, W. E.

1974-01-01

The structural performance of a boron-epoxy reinforced titanium drag strut, which contains a bonded scarf joint and was designed to the criteria of the Boeing 747 transport, was evaluated. An experimental and analytical investigation was conducted. The strut was exposed to two lifetimes of spectrum loading and was statically loaded to the tensile and compressive design ultimate loads. Throughout the test program no evidence of any damage in the drag strut was detected by strain gage measurements, ultrasonic inspection, or visual observation. An analytical study of the bonded joint was made using the NASA structural analysis computer program NASTRAN. A comparison of the strains predicted by the NASTRAN computer program with the experimentally determined values shows excellent agreement. The NASTRAN computer program is a viable tool for studying, in detail, the stresses and strains induced in a bonded joint.

FAA/NASA Joint University Program for Air Transportation Research: 1993-1994

NASA Technical Reports Server (NTRS)

Hueschen, Richard M. (Compiler)

1995-01-01

This report summarizes the research conducted during the academic year 1993-1994 under the NASA/FAA sponsored Joint University Program for Air Transportation Research. The year end review was held at Ohio University, Athens, Ohio, July 14-15, 1994. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology (NGL-22-009-640), Ohio University (NGR-36-009-017), and Princeton University (NGL-31-001-252). Completed works, status reports, and annotated bibliographies are presented for research topics which include navigation, guidance and control theory and practice, aircraft performance, human factors, and expert systems concepts applied to aircraft and airport operations. An overview of the year's activities for each university is also presented.

Face validation of the Simbionix LAP Mentor virtual reality training module and its applicability in the surgical curriculum.

PubMed

Ayodeji, I D; Schijven, M; Jakimowicz, J; Greve, J W

2007-09-01

The goal of our study was to determine expert and referent face validity of the LAP Mentor, the first procedural virtual reality (VR) laparoscopy trainer. In The Netherlands 49 surgeons and surgical trainees were given a hands-on introduction to the Simbionix LAP Mentor training module. Subsequently, a standardized five-point Likert-scale questionnaire was administered. Respondents who had performed over 50 laparoscopic procedures were classified as "experts." The others constituted the "referent" group, representing nonexperts such as surgical trainees. Of the experts, 90.5% (n = 21) judge themselves to be average or above-average laparoscopic surgeons, while 88.5% of referents (n = 28) feel themselves to be less-than-average laparoscopic surgeons (p = 0.000). There is agreement between both groups on all items concerning the simulator's performance and application. Respondents feel strongly about the necessity for training on basic skills before operating on patients and unanimously agree on the importance of procedural training. A large number (87.8%) of respondents expect the LAP Mentor to enhance a trainee's laparoscopic capability, 83.7% expect a shorter laparoscopic learning curve, and 67.3% even predict reduced complication rates in laparoscopic cholecystectomies among novice surgeons. The preferred stage for implementing the VR training module is during the surgeon's residency, and 59.2% of respondents feel the surgical curriculum is incomplete without VR training. Both potential surgical trainees and trainers stress the need for VR training in the surgical curriculum. Both groups believe the LAP Mentor to be a realistic VR module, with a powerful potential for training and monitoring basic laparoscopic skills as well as full laparoscopic procedures. Simulator training is perceived to be both informative and entertaining, and enthusiasm among future trainers and trainees is to be expected. Further validation of the system is required to determine whether

Effect of realistic vehicle seats, cushion length, and lap belt geometry on child ATD kinematics.

DOT National Transportation Integrated Search

2011-12-01

This series of sled tests examined the effect of using real vehicle seats on child ATD performance. Cushion length was varied from production length of 450 mm to a shorter length of 350 mm. Lap belt geometry was set to rear, mid, and forward anchorag...

Multi-Image or Lap-Dissolve Slide Techniques and Visual Images in the Large Lecture Section.

ERIC Educational Resources Information Center

Bodner, George M.; And Others

1984-01-01

Advantages and disadvantages of using multi-image or lap-dissolve (LD) slide techniques in large lecture sections are discussed. Production, use, and evaluation of LD programs are also discussed. Indicates that these programs are an effective way of improving instruction on visually oriented topics. (JN)

Joint University Program for Air Transportation Research, 1987

NASA Technical Reports Server (NTRS)

Morrell, Frederick R. (Compiler)

1989-01-01

The research conducted during 1987 under the NASA/FAA sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of 3 grants sponsored by NASA-Langley and the FAA, one each with the MIT, Ohio Univ., and Princeton Univ. Completed works, status reports, and annotated bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of the year's activities for each university is also presented.

Electromigration and Thermomechanical Fatigue Behavior of Sn0.3Ag0.7Cu Solder Joints

NASA Astrophysics Data System (ADS)

Zuo, Yong; Bieler, Thomas R.; Zhou, Quan; Ma, Limin; Guo, Fu

2017-12-01

The anisotropy of Sn crystal structures greatly affects the electromigration (EM) and thermomechanical fatigue (TMF) of solder joints. The size of solder joint shrinkage in electronic systems further makes EM and TMF an inseparably coupled issue. To obtain a better understanding of failure under combined moderately high (2000 A/cm2) current density and 10-150°C/1 h thermal cycling, analysis of separate, sequential, and concurrent EM and thermal cycling (TC) was imposed on single shear lap joints, and the microstructure and crystal orientations were incrementally characterized using electron backscatter diffraction (EBSD) mapping. First, it was determined that EM did not significantly change the crystal orientation, but the formation of Cu6Sn5 depended on the crystal orientation, and this degraded subsequent TMF behavior. Secondly, TC causes changes in crystal orientation. Concurrent EM and TC led to significant changes in crystal orientation by discontinuous recrystallization, which is facilitated by Cu6Sn5 particle formation. The newly formed Cu6Sn5 often showed its c-axis close to the direction of electron flow.

Electromigration and Thermomechanical Fatigue Behavior of Sn0.3Ag0.7Cu Solder Joints

NASA Astrophysics Data System (ADS)

Zuo, Yong; Bieler, Thomas R.; Zhou, Quan; Ma, Limin; Guo, Fu

2018-03-01

The anisotropy of Sn crystal structures greatly affects the electromigration (EM) and thermomechanical fatigue (TMF) of solder joints. The size of solder joint shrinkage in electronic systems further makes EM and TMF an inseparably coupled issue. To obtain a better understanding of failure under combined moderately high (2000 A/cm2) current density and 10-150°C/1 h thermal cycling, analysis of separate, sequential, and concurrent EM and thermal cycling (TC) was imposed on single shear lap joints, and the microstructure and crystal orientations were incrementally characterized using electron backscatter diffraction (EBSD) mapping. First, it was determined that EM did not significantly change the crystal orientation, but the formation of Cu6Sn5 depended on the crystal orientation, and this degraded subsequent TMF behavior. Secondly, TC causes changes in crystal orientation. Concurrent EM and TC led to significant changes in crystal orientation by discontinuous recrystallization, which is facilitated by Cu6Sn5 particle formation. The newly formed Cu6Sn5 often showed its c-axis close to the direction of electron flow.

An EMAT-based shear horizontal (SH) wave technique for adhesive bond inspection

NASA Astrophysics Data System (ADS)

Arun, K.; Dhayalan, R.; Balasubramaniam, Krishnan; Maxfield, Bruce; Peres, Patrick; Barnoncel, David

2012-05-01

The evaluation of adhesively bonded structures has been a challenge over the several decades that these structures have been used. Applications within the aerospace industry often call for particularly high performance adhesive bonds. Several techniques have been proposed for the detection of disbonds and cohesive weakness but a reliable NDE method for detecting interfacial weakness (also sometimes called a kissing bond) has been elusive. Different techniques, including ultrasonic, thermal imaging and shearographic methods, have been proposed; all have had some degree of success. In particular, ultrasonic methods, including those based upon shear and guided waves, have been explored for the assessment of interfacial bond quality. Since 3-D guided shear horizontal (SH) waves in plates have predominantly shear displacement at the plate surfaces, we conjectured that SH guided waves should be influenced by interfacial conditions when they propagate between adhesively bonded plates of comparable thickness. This paper describes a new technique based on SH guided waves that propagate within and through a lap joint. Through mechanisms we have yet to fully understand, the propagation of an SH wave through a lap joint gives rise to a reverberation signal that is due to one or more reflections of an SH guided wave mode within that lap joint. Based upon a combination of numerical simulations and measurements, this method shows promise for detecting and classifying interfacial bonds. It is also apparent from our measurements that the SH wave modes can discriminate between adhesive and cohesive bond weakness in both Aluminum-Epoxy-Aluminum and Composite-Epoxy-Composite lap joints. All measurements reported here used periodic permanent magnet (PPM) Electro-Magnetic Acoustic Transducers (EMATs) to generate either or both of the two lowest order SH modes in the plates that comprise the lap joint. This exact configuration has been simulated using finite element (FE) models to

TAS: A Transonic Aircraft/Store flow field prediction code

NASA Technical Reports Server (NTRS)

Thompson, D. S.

1983-01-01

A numerical procedure has been developed that has the capability to predict the transonic flow field around an aircraft with an arbitrarily located, separated store. The TAS code, the product of a joint General Dynamics/NASA ARC/AFWAL research and development program, will serve as the basis for a comprehensive predictive method for aircraft with arbitrary store loadings. This report described the numerical procedures employed to simulate the flow field around a configuration of this type. The validity of TAS code predictions is established by comparison with existing experimental data. In addition, future areas of development of the code are outlined. A brief description of code utilization is also given in the Appendix. The aircraft/store configuration is simulated using a mesh embedding approach. The computational domain is discretized by three meshes: (1) a planform-oriented wing/body fine mesh, (2) a cylindrical store mesh, and (3) a global Cartesian crude mesh. This embedded mesh scheme enables simulation of stores with fins of arbitrary angular orientation.

Aircraft vulnerability analysis by modeling and simulation

NASA Astrophysics Data System (ADS)

Willers, Cornelius J.; Willers, Maria S.; de Waal, Alta

2014-10-01

Infrared missiles pose a significant threat to civilian and military aviation. ManPADS missiles are especially dangerous in the hands of rogue and undisciplined forces. Yet, not all the launched missiles hit their targets; the miss being either attributable to misuse of the weapon or to missile performance restrictions. This paper analyses some of the factors affecting aircraft vulnerability and demonstrates a structured analysis of the risk and aircraft vulnerability problem. The aircraft-missile engagement is a complex series of events, many of which are only partially understood. Aircraft and missile designers focus on the optimal design and performance of their respective systems, often testing only in a limited set of scenarios. Most missiles react to the contrast intensity, but the variability of the background is rarely considered. Finally, the vulnerability of the aircraft depends jointly on the missile's performance and the doctrine governing the missile's launch. These factors are considered in a holistic investigation. The view direction, altitude, time of day, sun position, latitude/longitude and terrain determine the background against which the aircraft is observed. Especially high gradients in sky radiance occur around the sun and on the horizon. This paper considers uncluttered background scenes (uniform terrain and clear sky) and presents examples of background radiance at all view angles across a sphere around the sensor. A detailed geometrical and spatially distributed radiometric model is used to model the aircraft. This model provides the signature at all possible view angles across the sphere around the aircraft. The signature is determined in absolute terms (no background) and in contrast terms (with background). It is shown that the background significantly affects the contrast signature as observed by the missile sensor. A simplified missile model is constructed by defining the thrust and mass profiles, maximum seeker tracking rate, maximum

The Effects of Temperature, Humidity and Aircraft Fluid Exposure on T800H/3900-2 Composites Bonded with AF-555M Adhesive

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Hou, Tan-Hung; Lowther, Sharon E.; Thibeault, Sheila A.; Connell, John W.; Blasini, Sheila Roman

2010-01-01

Fiber reinforced resin matrix composites and structural adhesives have found increased usage on commercial and military aircraft in recent years. Due to the lack of service history of these relatively new material systems, their long-term aging performance has not been well established. In this study, single lap shear specimens (SLS) were fabricated by secondary bonding of Scotch-Weld(TradeMark) AF-555M between pre-cured adherends comprised of T800H/3900-2 uni-directional laminates. The adherends were co-cured with wet peel-ply for surface preparation. Each bond-line of the SLS specimen was measured to determine thickness and inspected visually using an optical microscope for voids. A three-year environmental aging plan for the SLS specimens at 82 C (180 F) and 85% relative humidity was initiated. SLS strengths were measured for both controls and aged specimens at room temperature and 82 C. The effect of this exposure on lap shear strength and failure modes to date is reported. In addition, the effects of water, saline water, deicing fluid, JP-5 jet fuel and hydraulic fluid on both the composite material and the adhesive bonds were investigated. The up to date results on the effects of these exposures will be discussed.

Cross-talk between miR-471-5p and autophagy component proteins regulates LC3-associated phagocytosis (LAP) of apoptotic germ cells.

PubMed

Panneerdoss, Subbarayalu; Viswanadhapalli, Suryavathi; Abdelfattah, Nourhan; Onyeagucha, Benjamin C; Timilsina, Santosh; Mohammad, Tabrez A; Chen, Yidong; Drake, Michael; Vuori, Kristiina; Kumar, T Rajendra; Rao, Manjeet K

2017-09-19

Phagocytic clearance of apoptotic germ cells by Sertoli cells is vital for germ cell development and differentiation. Here, using a tissue-specific miRNA transgenic mouse model, we show that interaction between miR-471-5p and autophagy member proteins regulates clearance of apoptotic germ cells via LC3-associated phagocytosis (LAP). Transgenic mice expressing miR-471-5p in Sertoli cells show increased germ cell apoptosis and compromised male fertility. Those effects are due to defective engulfment and impaired LAP-mediated clearance of apoptotic germ cells as miR-471-5p transgenic mice show lower levels of Dock180, LC3, Atg12, Becn1, Rab5 and Rubicon in Sertoli cells. Our results reveal that Dock180 interacts with autophagy member proteins to constitute a functional LC3-dependent phagocytic complex. We find that androgen regulates Sertoli cell phagocytosis by controlling expression of miR-471-5p and its target proteins. These findings suggest that recruitment of autophagy machinery is essential for efficient clearance of apoptotic germ cells by Sertoli cells using LAP.Although phagocytic clearance of apoptotic germ cells by Sertoli cells is essential for spermatogenesis, little of the mechanism is known. Here the authors show that Sertoli cells employ LC3-associated phagocytosis (LAP) by recruiting autophagy member proteins to clear apoptotic germ cells.

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Koumal, D. E.

1979-01-01

The design and evaluation of built-up attachments and bonded joint concepts for use at elevated temperatures is documented. Joint concept screening, verification of GR/PI material, fabrication of design allowables panels, definition of test matrices, and analysis of bonded and bolted joints are among the tasks completed. The results provide data for the design and fabrication of lightly loaded components for advanced space transportation systems and high speed aircraft.

Maneuvering control and configuration adaptation of a biologically inspired morphing aircraft

NASA Astrophysics Data System (ADS)

Abdulrahim, Mujahid

Natural flight as a source of inspiration for aircraft design was prominent with early aircraft but became marginalized as aircraft became larger and faster. With recent interest in small unmanned air vehicles, biological inspiration is a possible technology to enhance mission performance of aircraft that are dimensionally similar to gliding birds. Serial wing joints, loosely modeling the avian skeletal structure, are used in the current study to allow significant reconfiguration of the wing shape. The wings are reconfigured to optimize aerodynamic performance and maneuvering metrics related to specific mission tasks. Wing shapes for each mission are determined and related to the seagulls, falcons, albatrosses, and non-migratory African swallows on which the aircraft are based. Variable wing geometry changes the vehicle dynamics, affording versatility in flight behavior but also requiring appropriate compensation to maintain stability and controllability. Time-varying compensation is in the form of a baseline controller which adapts to both the variable vehicle dynamics and to the changing mission requirements. Wing shape is adapted in flight to minimize a cost function which represents energy, temporal, and spatial efficiency. An optimal control architecture unifies the control and adaptation tasks.

Design criteria for integrated flight/propulsion control systems for STOVL fighter aircraft

NASA Technical Reports Server (NTRS)

Franklin, James A.

1993-01-01

As part of NASA's program to develop technology for short takeoff and vertical landing (STOVL) fighter aircraft, control system designs have been developed for a conceptual STOVL aircraft. This aircraft is representative of the class of mixed-flow remote-lift concepts that was identified as the preferred design approach by the US/UK STOVL Joint Assessment and Ranking Team. The control system designs have been evaluated throughout the powered-lift flight envelope on Ames Research Center's Vertical Motion Simulator. Items assessed in the control system evaluation were: maximum control power used in transition and vertical flight, control system dynamic response associated with thrust transfer for attitude control, thrust margin in the presence of ground effect and hot gas ingestion, and dynamic thrust response for the engine core. Effects of wind, turbulence, and ship airwake disturbances are incorporated in the evaluation. Results provide the basis for a reassessment of existing flying qualities design criteria applied to STOVL aircraft.

Agreement Between VO2peak Predicted From PACER and One-Mile Run Time-Equated Laps.

PubMed

Saint-Maurice, Pedro F; Anderson, Katelin; Bai, Yang; Welk, Gregory J

2016-12-01

This study examined the agreement between estimated peak oxygen consumption (VO 2peak ) obtained from the Progressive Aerobic Cardiovascular Endurance Run (PACER) fitness test and equated PACER laps derived from One-Mile Run time (MR). A sample of 680 participants (324 boys and 356 girls) in Grades 7 through 12 completed both the PACER and the MR assessments. MR time was converted to PACER laps (PACER-MEQ) using previously developed conversion algorithms. Agreement between PACER and PACER-MEQ VO 2peak was examined using Pearson correlations, mean absolute percent error (MAPE), and equivalence testing procedures. Classification agreement based on health-related standards was examined using sensitivity, specificity, and Kappa statistics. Overall agreement between estimated VO 2peak obtained from the PACER and PACER-MEQ was high in boys, r(324) = .79, R 2  = .63, and moderate in girls, r(356) = .57, R 2  = .33. The MAPE for estimates obtained from PACER-MEQ was 10.3% and estimates were deemed equivalent to the PACER (43.1 ± 6.9 mL/kg/min vs. 44.6 ± 0.3 mL/kg/min). Classification agreement as illustrated by sensitivity and specificity ranged from 20.4% to 90.2% and was higher for classifications in the Healthy Fitness Zone (HFZ). Kappa statistics ranged from .14 to .51 and were also higher for the HFZ. Equated PACER laps can be used to obtain equivalent estimates of PACER VO 2peak in groups of adolescents, but some disparities can be found when students' scores are classified into the Needs Improvement Zone.

Performance of lap splices in large-scale column specimens affected by ASR and/or DEF-extension phase.

DOT National Transportation Integrated Search

2015-03-01

A large experimental program, consisting of the design, construction, curing, exposure, and structural load : testing of 16 large-scale column specimens with a critical lap splice region that were influenced by varying : stages of alkali-silica react...

One Size Does Not Fit All: How Acquisition Fails the Joint Force Commander

DTIC Science & Technology

2010-04-02

Campaign Planning and Strategy . The contents of this paper reflect my own personal views and are not necessarily endorsed by the Joint Forces Staff...one-size-fits-all‖ approach has insidiously led to a flawed aircraft acquisition strategy that allows unacceptable risk to combat effectiveness in an...and 78% of the total US tactical aviation fleet. This ―one-size-fits-all‖ approach has insidiously led to a flawed aircraft acquisition strategy

Braking, steering, and wear performance of radial-belted and bias-ply aircraft tires

NASA Technical Reports Server (NTRS)

Yager, Thomas J.; Davis, Pamela A.; Stubbs, Sandy M.; Martinson, Veloria J.

1992-01-01

Preliminary steering, braking, and tread wear performance results from testing of radial-belted and bias-ply aircraft tires at NASA Langley are described. An overview of the joint NASA/FAA/industry START program is presented. Attention is given to the Langley Test Facility, equipment and future activities.

Advanced Methods for Acoustic and Thrust Benefits for Aircraft Engine Nozzles

NASA Technical Reports Server (NTRS)

Morgan, Morris H., III; Gilinsky, Mikhail M.

2000-01-01

The Fluid Mechanics and Acoustics Laboratory (FM&AL) was established At Hampton University in June of 1996. In addition, the FM&AL jointly conducted research with the Central AeroHydrodynamics Institute (TsAGI, Moscow) in Russia under a 2.5 year Civilian Research and Development Foundation (CRDF). The goals of the FM&AL programs are two fold: 1) to improve the working efficiency of the FM&AL team in generating new innovative ideas and in conducting research in the field of fluid dynamics and acoustics, basically for improvement of supersonic and subsonic aircraft engines, and 2) to attract promising minority students to this research and training and, in cooperation with other HU departments, to teach them basic knowledge in Aerodynamics, Gas Dynamics, and Theoretical and Experimental Methods in Aeroacoustics and Computational Fluid Dynamics (CFD). The research at the FM&AL supports reduction schemes associated with the emission of engine pollutants for commercial aircraft and concepts for reduction of observables for military aircraft. These research endeavors relate to the goals of the NASA Strategic Enterprise in Aeronautics concerning the development of environmentally acceptable aircraft. It is in this precise area, where the US aircraft industry, academia, and Government are in great need of trained professionals and which is a high priority goal of the Minority University Research and Education (MUREP) Program, that the HU FM&AL can make its most important contribution. This project already benefits NASA and HU because: First, the innovation, testing, and further development of new techniques for advanced propulsion systems are necessary for the successful attainment of the NASA Long Term Goals in Aeronautics and Space Transportation Technology (ASTT) including Global Civil Aviation, Revolutionary Technology Leaps, Access to Space, R&D Services, and the economic competitiveness of the US Aircraft Industry in the 2 1 st century. Secondly, the joint

Demonstrate a Low Biochemical Oxygen Demand Aircraft Deicing Fluid

DTIC Science & Technology

2013-03-01

Technologies International, LTD for collection and recycling of fluids. Spent fluid, diluted with any water, slush or snow removed from the aircraft or...Resistance Unmated only – some failures Voltage Withstand Testing Unmated only – some failures Plastic Windows Crazing Effect Pass The testing did result...At Joint Base McGuire-Dix-Lakehurst, however, waste PG is currently collected with a vacuum truck and recycled . Factors such as the market demand

Demonstrate a Low Biochemical Oxygen Demand Aircraft Deicing Fluid

DTIC Science & Technology

2013-03-04

Technologies International, LTD for collection and recycling of fluids. Spent fluid, diluted with any water, slush or snow removed from the aircraft or...Resistance Unmated only – some failures Voltage Withstand Testing Unmated only – some failures Plastic Windows Crazing Effect Pass The testing did result...At Joint Base McGuire-Dix-Lakehurst, however, waste PG is currently collected with a vacuum truck and recycled . Factors such as the market demand

Lap-Protector and Circular Stapler Are Useful in Cystogastrostomy for Large Pancreatic Pseudocyst with Severe Infection

PubMed Central

Kadowaki, Yoshihiko; Kurokawa, Takefumi; Tamura, Ryuji; Okamoto, Takahiro; Ishido, Nobuhiro; Mori, Takashi

2010-01-01

Lap-Protector, which is an abdominal wall sealing device, is usually used for wound protection from implantation of malignant cells or pyogenic fluid. A circular stapler is a common easy-to-use device for anastomosis of the digestive tract. We report the case of an infected pancreatic pseudocyst which was treated by surgical procedure using these useful devices. A 69-year-old man was followed up in our hospital after severe acute pancreatitis. He had undergone drainage surgeries twice for intractable pancreatic abscess followed by severe acute pancreatitis. He was admitted to our hospital complaining of loss of appetite, hiccups, and high fever. Computed tomography of the abdomen revealed an infected pancreatic pseudocyst which compressed the gastric wall. Internal drainage into the stomach was performed using Lap-Protector and circular stapler. The patient recovered uneventfully. Recently many endoscopic or laparoscopic procedures in cystogastrostomy are reported; however, a conventional open surgical approach is also important. This easy method may be useful for operative cystogastrostomy. PMID:20805947

Criteria for design of integrated flight/propulsion control systems for STOVL fighter aircraft

NASA Technical Reports Server (NTRS)

Franklin, James A.

1993-01-01

As part of NASA's program to develop technology for short takeoff and vertical landing (STOVL) fighter aircraft, control system designs have been developed for a conceptual STOVL aircraft. This aircraft is representative of the class of mixed-flow remote-lift concepts that was identified as the preferred design approach by the U.S./U.K. STOVL Joint Assessment and Ranking Team. The control system designs have been evaluated throughout the powered-lift flight envelope on the Vertical Motion Simulator (VMS) at Ames Research Center. Items assessed in the control system evaluation were: maximum control power used in transition and vertical flight, control system dynamic response associated with thrust transfer for attitude control, thrust margin in the presence of ground effect and hot-gas ingestion, and dynamic thrust response for the engine core. Effects of wind, turbulence, and ship airwake disturbances are incorporated in the evaluation. Results provide the basis for a reassessment of existing flying-qualities design criteria applied to STOVL aircraft.

ACSYNT - A standards-based system for parametric, computer aided conceptual design of aircraft

NASA Technical Reports Server (NTRS)

Jayaram, S.; Myklebust, A.; Gelhausen, P.

1992-01-01

A group of eight US aerospace companies together with several NASA and NAVY centers, led by NASA Ames Systems Analysis Branch, and Virginia Tech's CAD Laboratory agreed, through the assistance of Americal Technology Initiative, in 1990 to form the ACSYNT (Aircraft Synthesis) Institute. The Institute is supported by a Joint Sponsored Research Agreement to continue the research and development in computer aided conceptual design of aircraft initiated by NASA Ames Research Center and Virginia Tech's CAD Laboratory. The result of this collaboration, a feature-based, parametric computer aided aircraft conceptual design code called ACSYNT, is described. The code is based on analysis routines begun at NASA Ames in the early 1970's. ACSYNT's CAD system is based entirely on the ISO standard Programmer's Hierarchical Interactive Graphics System and is graphics-device independent. The code includes a highly interactive graphical user interface, automatically generated Hermite and B-Spline surface models, and shaded image displays. Numerous features to enhance aircraft conceptual design are described.

Simulation-Based Airframe Noise Prediction of a Full-Scale, Full Aircraft

NASA Technical Reports Server (NTRS)

Khorrami, Mehdi R.; Fares, Ehab

2016-01-01

A previously validated computational approach applied to an 18%-scale, semi-span Gulfstream aircraft model was extended to the full-scale, full-span aircraft in the present investigation. The full-scale flap and main landing gear geometries used in the simulations are nearly identical to those flown on the actual aircraft. The lattice Boltzmann solver PowerFLOW® was used to perform time-accurate predictions of the flow field associated with this aircraft. The simulations were performed at a Mach number of 0.2 with the flap deflected 39 deg. and main landing gear deployed (landing configuration). Special attention was paid to the accurate prediction of major sources of flap tip and main landing gear noise. Computed farfield noise spectra for three selected baseline configurations (flap deflected 39 deg. with and without main gear extended, and flap deflected 0 deg. with gear deployed) are presented. The flap brackets are shown to be important contributors to the farfield noise spectra in the mid- to high-frequency range. Simulated farfield noise spectra for the baseline configurations, obtained using a Ffowcs Williams and Hawkings acoustic analogy approach, were found to be in close agreement with acoustic measurements acquired during the 2006 NASA-Gulfstream joint flight test of the same aircraft.

Long-term, repeated dose in vitro neurotoxicity of the glutamate receptor antagonist L-AP3, demonstrated in rat hippocampal slice cultures by using continuous propidium iodide incubation.

PubMed

Kristensen, Bjarne W; Blaabjerg, Morten; Noraberg, Jens; Zimmer, Jens

2007-05-01

Most in vitro models are only used to assess short-term effects of test compounds. However, as demonstrated here, hippocampal slice cultures can be used for long-term studies. The test compound used was the metabotropic glutamate receptor antagonist, L(+)-2-amino-3-phosphonopropionic acid (L-AP3), which is known to be toxic in vivo after subchronic, but not acute, administration. Degenerative effects were monitored by measuring the cellular uptake of propidium iodide (PI; continuously present in the medium) and lactate dehydrogenase (LDH) leakage, and by using a panel of histological stains. Hippocampal slices, derived from 2-3 day old rats and grown for 3 weeks, were subsequently exposed for the next 3 weeks to 0, 10 or 100microM L-AP3, with PI (2microM) in the culture medium. Exposure to 100microM L-AP3 induced severe toxicity after 4-6 days, shown by massive PI uptake, LDH leakage, changes in MAP2 and GFAP immunostaining, and in Nissl and Timm staining. In contrast, 10microM L-AP3 did not induce detectable neuronal degeneration. Treatment with the NMDA receptor antagonist, MK-801, or the AMPA/KA receptor antagonist NBQX, together with 100microM L-AP3, reduced neurodegeneration down to close to control values. It is concluded that continuous incubation of hippocampal slice cultures with PI is technically feasible for use in studies of inducible neuronal degeneration over time.

Common software and interface for different helmet-mounted display (HMD) aircraft symbology sets

NASA Astrophysics Data System (ADS)

Mulholland, Fred F.

2000-06-01

Different aircraft in different services and countries have their own set of symbology they want displayed on their HMD. Even as flight symbolgy is standardized, there will still be some differences for types of aircraft, different weapons, different sensors, and different countries. As an HMD supplier, we want to provide a system that can be used across all these applications with no changes in the system, including no changes in the software. This HMD system must also provide the flexibility to accommodate new symbology as it is developed over the years, again, with no change in the HMD software. VSI has developed their HMD software to accommodate F-15, F- 16, F-18, and F-22 symbology sets for the Joint Helmet Mounted Cueing System. It also has the flexibility to accommodate the aircraft types and services of the Joint Strike Fighter: Conventional Takeoff and Landing variant for the USAF, Carrier-based Variant for the USN, and the Short Takeoff and Vertical Landing variant for the USMC and U.K. Royal Navy and Air Force. The key to this flexibility is the interface definition. The interface parameters are established at power-on with the download of an interface definition data set. This data set is used to interpret symbology commands from the aircraft OFP during operation and provide graphic commands to the HMD software. This presentation will define the graphics commands, provide an example of how the interface definition data set is defined, and then show how symbology commands produce a display.

Joint stars phased array radar antenna

NASA Astrophysics Data System (ADS)

Shnitkin, Harold

1994-10-01

The Joint STARS phased array radar system is capable of performing long range airborne surveillance and was used during the Persian Gulf war on two E8-A aircraft to fly many around-the-clock missions to monitor the Kuwait and Iraq battlefield from a safe distance behind the front lines. This paper is a follow-on to previous publications on the subject of the Joint STARS antenna and deals mainly with mission performance and technical aspects not previously covered. Radar data of troop movements and armament installations will be presented, a brief review of the antenna design is given, followed by technical discussions concerning the three-port interferometry, gain and sidelobe design approach, cost control, range test implementation and future improvements.

Effect of Zinc Coatings on Joint Properties and Interfacial Reactions in Aluminum to Steel Ultrasonic Spot Welding

NASA Astrophysics Data System (ADS)

Haddadi, F.; Strong, D.; Prangnell, P. B.

2012-03-01

Dissimilar joining of aluminum to steel sheet in multimaterial automotive structures is an important potential application of ultrasonic spot welding (USW). Here, the weldability of different zinc-coated steels with aluminum is discussed, using a 2.5-kW USW welder. Results show that soft hot-dipped zinc (DX56-Z)-coated steel results in better weld performance than hard (galv-annealed) zinc coatings (DX53-ZF). For Al to hard galv-annealed-coated steel welds, lap shear strengths reached a maximum of ~80% of the strength of an Al-Al joint after a 1.0 s welding time. In comparison, welds between Al6111-T4 and hot dipped soft zinc-coated steel took longer to achieve the same maximum strength, but nearly matched the Al-Al joint properties. The reasons for these different behaviors are discussed in terms of the interfacial reactions between the weld members.

Respectability, morality and disgust in the night‐time economy: exploring reactions to ‘lap dance’ clubs in England and Wales

PubMed Central

Hubbard, Phil; Colosi, Rachela

2015-01-01

Abstract The night‐time economy is often described as repelling consumers fearful of the ‘undesirable Others’ imagined dominant within such time‐spaces. In this paper we explore this by describing attitudes towards, and reactions to, one particularly contentious site: the ‘lap dance’ club. Often targeted by campaigners in England and Wales as a source of criminality and anti‐sociality, in this paper we shift the focus from fear to disgust, and argue that Sexual Entertainment Venues (SEVs) are opposed on the basis of moral judgments that reflect distinctions of both class and gender. Drawing on documentary analysis, survey results and interview data collected during guided walks, we detail the concerns voiced by those anxious about the presence of lap dance or striptease clubs in their town or city, particularly the notion that they ‘lower the tone’ of particular streets or neighbourhoods. Our conclusion is that the opposition expressed to lap dance clubs is part of an attempt to police the boundaries of respectable masculinities and femininities, marginalizing the producers and consumers of sexual entertainment through ‘speech acts’ which identify such entertainment as unruly, vulgar and uncivilized. These findings are considered in the light of ongoing debates concerning the relations of morality, respectability and disgust. PMID:27708460

The Fundamentals of Laparoscopic Surgery and LapVR evaluation metrics may not correlate with operative performance in a novice cohort

PubMed Central

Steigerwald, Sarah N.; Park, Jason; Hardy, Krista M.; Gillman, Lawrence; Vergis, Ashley S.

2015-01-01

Background Considerable resources have been invested in both low- and high-fidelity simulators in surgical training. The purpose of this study was to investigate if the Fundamentals of Laparoscopic Surgery (FLS, low-fidelity box trainer) and LapVR (high-fidelity virtual reality) training systems correlate with operative performance on the Global Operative Assessment of Laparoscopic Skills (GOALS) global rating scale using a porcine cholecystectomy model in a novice surgical group with minimal laparoscopic experience. Methods Fourteen postgraduate year 1 surgical residents with minimal laparoscopic experience performed tasks from the FLS program and the LapVR simulator as well as a live porcine laparoscopic cholecystectomy. Performance was evaluated using standardized FLS metrics, automatic computer evaluations, and a validated global rating scale. Results Overall, FLS score did not show an association with GOALS global rating scale score on the porcine cholecystectomy. None of the five LapVR task scores were significantly associated with GOALS score on the porcine cholecystectomy. Conclusions Neither the low-fidelity box trainer or the high-fidelity virtual simulator demonstrated significant correlation with GOALS operative scores. These findings offer caution against the use of these modalities for brief assessments of novice surgical trainees, especially for predictive or selection purposes. PMID:26641071

Joint University Program for Air Transportation Research, 1988-1989

NASA Technical Reports Server (NTRS)

Morrell, Frederick R. (Compiler)

1990-01-01

The research conducted during 1988 to 1989 under the NASA/FAA-sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology, Ohio University, and Princeton University. Completed works, status reports, and annotated bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of the year's activities for each university is also presented.

Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells

PubMed Central

Rezende, Rafael M.; Oliveira, Rafael P.; Medeiros, Samara R.; Gomes-Santos, Ana C.; Alves, Andrea C.; Loli, Flávia G.; Guimarães, Mauro A.F.; Amaral, Sylvia S.; da Cunha, André P.; Weiner, Howard L.; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M.C.

2013-01-01

Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. PMID:22939403

Hsp65-producing Lactococcus lactis prevents experimental autoimmune encephalomyelitis in mice by inducing CD4+LAP+ regulatory T cells.

PubMed

Rezende, Rafael M; Oliveira, Rafael P; Medeiros, Samara R; Gomes-Santos, Ana C; Alves, Andrea C; Loli, Flávia G; Guimarães, Mauro A F; Amaral, Sylvia S; da Cunha, André P; Weiner, Howard L; Azevedo, Vasco; Miyoshi, Anderson; Faria, Ana M C

2013-02-01

Heat shock proteins (Hsps) participate in the cellular response to stress and they are hiperexpressed in inflammatory conditions. They are also known to play a major role in immune modulation, controlling, for instance, autoimmune responses. In this study, we showed that oral administration of a recombinant Lactococcus lactis strain that produces and releases LPS-free Hsp65 prevented the development of experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. This was confirmed by the reduced inflammatory cell infiltrate and absence of injury signs in the spinal cord. The effect was associated with reduced IL-17 and increased IL-10 production in mesenteric lymph node and spleen cell cultures. Hsp65-producing-L. lactis-fed mice had a remarkable increase in the number of natural and inducible CD4+Foxp3+ regulatory T (Treg) cells and CD4+LAP+ (Latency-associated peptide) Tregs - which express the membrane-bound TGF-β - in spleen, inguinal and mesenteric lymph nodes as well as in spinal cord. Moreover, many Tregs co-expressed Foxp3 and LAP. In vivo depletion of LAP+ cells abrogated the effect of Hsp65-producing L. lactis in EAE prevention and worsened disease in medium-fed mice. Thus, Hsp65-L.lactis seems to boost this critical regulatory circuit involved in controlling EAE development in mice. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

STOVL aircraft simulation for integrated flight and propulsion control research

NASA Technical Reports Server (NTRS)

Mihaloew, James R.; Drummond, Colin K.

1989-01-01

The United States is in the initial stages of committing to a national program to develop a supersonic short takeoff and vertical landing (STOVL) aircraft. The goal of the propulsion community in this effort is to have the enabling propulsion technologies for this type aircraft in place to permit a low risk decision regarding the initiation of a research STOVL supersonic attack/fighter aircraft in the late mid-90's. This technology will effectively integrate, enhance, and extend the supersonic cruise, STOVL and fighter/attack programs to enable U.S. industry to develop a revolutionary supersonic short takeoff and vertical landing fighter/attack aircraft in the post-ATF period. A joint NASA Lewis and NASA Ames research program, with the objective of developing and validating technology for integrated-flight propulsion control design methodologies for short takeoff and vertical landing (STOVL) aircraft, was planned and is underway. This program, the NASA Supersonic STOVL Integrated Flight-Propulsion Controls Program, is a major element of the overall NASA-Lewis Supersonic STOVL Propulsion Technology Program. It uses an integrated approach to develop an integrated program to achieve integrated flight-propulsion control technology. Essential elements of the integrated controls research program are realtime simulations of the integrated aircraft and propulsion systems which will be used in integrated control concept development and evaluations. This paper describes pertinent parts of the research program leading up to the related realtime simulation development and remarks on the simulation structure to accommodate propulsion system hardware drop-in for real system evaluation.

Initial Retrieval Validation from the Joint Airborne IASI Validation Experiment (JAIVEx)

NASA Technical Reports Server (NTRS)

Zhou, Daniel K.; Liu, Xu; Smith, WIlliam L.; Larar, Allen M.; Taylor, Jonathan P.; Revercomb, Henry E.; Mango, Stephen A.; Schluessel, Peter; Calbet, Xavier

2007-01-01

The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite, but also included a strong component focusing on validation of the Atmospheric InfraRed Sounder (AIRS) aboard the AQUA satellite. The cross validation of IASI and AIRS is important for the joint use of their data in the global Numerical Weather Prediction process. Initial inter-comparisons of geophysical products have been conducted from different aspects, such as using different measurements from airborne ultraspectral Fourier transform spectrometers (specifically, the NPOESS Airborne Sounder Testbed Interferometer (NAST-I) and the Scanning-High resolution Interferometer Sounder (S-HIS) aboard the NASA WB-57 aircraft), UK Facility for Airborne Atmospheric Measurements (FAAM) BAe146-301 aircraft insitu instruments, dedicated dropsondes, radiosondes, and ground based Raman Lidar. An overview of the JAIVEx retrieval validation plan and some initial results of this field campaign are presented.

Application of a cost/performance measurement system on a research aircraft project

NASA Technical Reports Server (NTRS)

Diehl, J. J.

1978-01-01

The fundamentals of the cost/performance management system used in the procurement of two tilt rotor aircraft for a joint NASA/Army research project are discussed. The contractor's reporting system and the GPO's analyses are examined. The use of this type of reporting system is assessed. Recommendations concerning the use of like systems on future projects are included.

Microstructure and fatigue resistance of high strength dual phase steel welded with gas metal arc welding and plasma arc welding processes

NASA Astrophysics Data System (ADS)

Ahiale, Godwin Kwame; Oh, Yong-Jun; Choi, Won-Doo; Lee, Kwang-Bok; Jung, Jae-Gyu; Nam, Soo Woo

2013-09-01

This study presents the microstructure and high cycle fatigue performance of lap shear joints of dual phase steel (DP590) welded using gas metal arc welding (GMAW) and plasma arc welding (PAW) processes. High cycle fatigue tests were conducted on single and double lap joints under a load ratio of 0.1 and a frequency of 20 Hz. In order to establish a basis for comparison, both weldments were fabricated to have the same weld depth in the plate thickness. The PAW specimens exhibited a higher fatigue life, a gentle S-N slope, and a higher fatigue limit than the GMAW specimens. The improvement in the fatigue life of the PAW specimens was primarily attributed to the geometry effect that exhibited lower and wider beads resulting in a lower stress concentration at the weld toe where cracks initiate and propagate. Furthermore, the microstructural constituents in the heat-affected zone (HAZ) of the PAW specimens contributed to the improvement. The higher volume fraction of acicular ferrite in the HAZ beneath the weld toe enhanced the PAW specimen's resistance to fatigue crack growth. The double lap joints displayed a higher fatigue life than the single lap joints without changing the S-N slope.

[Behaviour of the LAP (leucine-amino-peptidase) in the serum of blood in subjects affected of cirrhosis of the liver in stage ascitical (author's transl)].

PubMed

Pace, M; Fernandes, D

1980-12-01

The AA. have studied behaviour of the LAP (leucine-amino-peptidase) in the serum of blood in subjects affected of cirrhosis of the liver in stage ascitical, of cause toxic-alcoholic excluding about of the casuistry the cirrhosis of the another cause and the cirrhosis that are compled white an obstruction in and extrahepatic standard biliary cirrhosis 1 degree e 2 degree. After the exposition of the casuistry in the registred normality of the test (seric-LAP) in some cases of hepatic-alcoholic cirrhosis, the AA. concluded considering the LAP an indicator only of the obstruction in and extra-hepatic, consistent with hepatic-organ well operating; do not be a secure test to follow development of a chronic hepatitis of any kind, even if in the hepatic disease is present an infiltration and an overturning of the hepatic-lobule, like it is normally in the hepatic alcoholic diseases.

Computational fluid dynamics modeling of transport and deposition of pesticides in an aircraft cabin

PubMed Central

Isukapalli, Sastry S.; Mazumdar, Sagnik; George, Pradeep; Wei, Binnian; Jones, Byron; Weisel, Clifford P.

2015-01-01

Spraying of pesticides in aircraft cabins is required by some countries as part of a disinsection process to kill insects that pose a public health threat. However, public health concerns remain regarding exposures of cabin crew and passengers to pesticides in aircraft cabins. While large scale field measurements of pesticide residues and air concentrations in aircraft cabins scenarios are expensive and time consuming, Computational Fluid Dynamics (CFD) models provide an effective alternative for characterizing concentration distributions and exposures. This study involved CFD modeling of a twin-aisle 11 row cabin mockup with heated manikins, mimicking a part of a fully occupied Boeing 767 cabin. The model was applied to study the flow and deposition of pesticides under representative scenarios with different spraying patterns (sideways and overhead) and cabin air exchange rates (low and high). Corresponding spraying experiments were conducted in the cabin mockup, and pesticide deposition samples were collected at the manikin’s lap and seat top for a limited set of five seats. The CFD model performed well for scenarios corresponding to high air exchange rates, captured the concentration profiles for middle seats under low air exchange rates, and underestimated the concentrations at window seats under low air exchange rates. Additionally, both the CFD and experimental measurements showed no major variation in deposition characteristics between sideways and overhead spraying. The CFD model can estimate concentration fields and deposition profiles at very high resolutions, which can be used for characterizing the overall variability in air concentrations and surface loadings. Additionally, these model results can also provide a realistic range of surface and air concentrations of pesticides in the cabin that can be used to estimate potential exposures of cabin crew and passengers to these pesticides. PMID:25642134

The Joint Strike Fighter (JSF) PHM and the Autonomic Logistic Concept: Potential Impact on Aging Aircraft Problems

DTIC Science & Technology

2003-02-01

and highly intelligent aircraft. A major tenet of this discussion will be that robust information sources provided by the PHM system can and will be...and maintainable (R+M) designed intelligent aircraft which encompasses a comprehensive Prognostics and Health Management (PHM) capability to enhance...hydraulic pump has a 90% chance of failing within the next 10 flight hours. This way, maintenance personnel will be able to make intelligent ,.informed

Agreement between VO[subscript 2peak] Predicted from PACER and One-Mile Run Time-Equated Laps

ERIC Educational Resources Information Center

Saint-Maurice, Pedro F.; Anderson, Katelin; Bai, Yang; Welk, Gregory J.

2016-01-01

Purpose: This study examined the agreement between estimated peak oxygen consumption (VO[subscript 2peak]) obtained from the Progressive Aerobic Cardiovascular Endurance Run (PACER) fitness test and equated PACER laps derived from One-Mile Run time (MR). Methods: A sample of 680 participants (324 boys and 356 girls) in Grades 7 through 12…

Studies of aerodynamic technology for VSTOL fighter/attack aircraft

NASA Technical Reports Server (NTRS)

Nelms, W. P.

1978-01-01

The paper summarizes several studies to develop aerodynamic technology for high performance VSTOL aircraft anticipated after 1990. A contracted study jointly sponsored by NASA-Ames and David Taylor Naval Ship Research and Development Center is emphasized. Four contractors analyzed two vertical-attitude and three horizontal-attitude takeoff and landing concepts with gross weights ranging from about 10433 kg (23,000 lb) to 17236 kg (38,000 lb). The aircraft have supersonic capability, high maneuver performance (sustained load factor 6.2 at Mach 0.6, 3048 m (10,000 ft)) and a 4536 kg (10,000-lb) STO overload capability. The contractors have estimated the aerodynamics and identified aerodynamic uncertainties associated with their concept. Example uncertainties relate to propulsion-induced flows, canard-wing interactions, and top inlets. Wind-tunnel research programs were proposed to investigate these uncertainties.

Systems engineering in a joint program environment: the joint helmet-mounted cueing system

NASA Astrophysics Data System (ADS)

Wilkins, Donald F.

1999-07-01

The Joint Helmet Mounted Cueing System (JHMCS) is a design program involving two airframe companies (Boeing and Lockheed Martin), two services (USAF and USN) and four aircraft platforms: the F-22, the F-16, the F/A-18 and the F-15. Developing equipment requirements for the combined operational and environmental needs of these diverse communities is a significant challenge. In addition, the team is geographically dispersed which presented challenges in communication and coordination. This paper details the lessons learned in producing a cost-effective design within a short development schedule and makes recommendations for future development programs.

Interaction of Aircraft Wakes From Laterally Spaced Aircraft

NASA Technical Reports Server (NTRS)

Proctor, Fred H.

2009-01-01

Large Eddy Simulations are used to examine wake interactions from aircraft on closely spaced parallel paths. Two sets of experiments are conducted, with the first set examining wake interactions out of ground effect (OGE) and the second set for in ground effect (IGE). The initial wake field for each aircraft represents a rolled-up wake vortex pair generated by a B-747. Parametric sets include wake interactions from aircraft pairs with lateral separations of 400, 500, 600, and 750 ft. The simulation of a wake from a single aircraft is used as baseline. The study shows that wake vortices from either a pair or a formation of B-747 s that fly with very close lateral spacing, last longer than those from an isolated B-747. For OGE, the inner vortices between the pair of aircraft, ascend, link and quickly dissipate, leaving the outer vortices to decay and descend slowly. For the IGE scenario, the inner vortices ascend and last longer, while the outer vortices decay from ground interaction at a rate similar to that expected from an isolated aircraft. Both OGE and IGE scenarios produce longer-lasting wakes for aircraft with separations less than 600 ft. The results are significant because concepts to increase airport capacity have been proposed that assume either aircraft formations and/or aircraft pairs landing on very closely spaced runways.

Three-dimensional dynamic thermal imaging of structural flaws by dual-band infrared computed tomography

NASA Astrophysics Data System (ADS)

DelGrande, Nancy; Dolan, Kenneth W.; Durbin, Philip F.; Gorvad, Michael R.; Kornblum, B. T.; Perkins, Dwight E.; Schneberk, Daniel J.; Shapiro, Arthur B.

1993-11-01

We discuss three-dimensional dynamic thermal imaging of structural flaws using dual-band infrared (DBIR) computed tomography. Conventional (single-band) thermal imaging is difficult to interpret. It yields imprecise or qualitative information (e.g., when subsurface flaws produce weak heat flow anomalies masked by surface clutter). We use the DBIR imaging technique to clarify interpretation. We capture the time history of surface temperature difference patterns at the epoxy-glue disbond site of a flash-heated lap joint. This type of flawed structure played a significant role in causing damage to the Aloha Aircraft fuselage on the aged Boeing 737 jetliner. The magnitude of surface-temperature differences versus time for 0.1 mm air layer compared to 0.1 mm glue layer, varies from 0.2 to 1.6 degree(s)C, for simultaneously scanned front and back surfaces. The scans are taken every 42 ms from 0 to 8 s after the heat flash. By ratioing 3 - 5 micrometers and 8 - 12 micrometers DBIR images, we located surface temperature patterns from weak heat flow anomalies at the disbond site and remove the emissivity mask from surface paint of roughness variations. Measurements compare well with calculations based on TOPAX3D, a three-dimensional, finite element computer model. We combine infrared, ultrasound and x-ray imaging methods to study heat transfer, bond quality and material differences associated with the lap joint disbond site.

Application of statistical methods to reveal and remove the causes of welding of coil laps upon annealing of cold-rolled steel strips

NASA Astrophysics Data System (ADS)

Garber, E. A.; Diligenskii, E. V.; Antonov, P. V.; Shalaevskii, D. L.; Dyatlov, I. A.

2017-09-01

The factors of the process of production of cold-rolled steel strips that promote and hinder the appearance of a coil lap welding defect upon annealing in bell-type furnaces are analyzed using statistical methods. The works dealing with this problem are analytically reviewed to reveal the problems to be studied and refined. The ranking of the technological factors according to the significance of their influence on the probability of appearance of this defect is determined and supported by industrial data, and a regression equation is derived to calculate this probability. The process of production is improved to minimize the rejection of strips caused by the welding of coil laps.

Mixed-mode cyclic debonding of adhesively bonded composite joints. M.S. Thesis

NASA Technical Reports Server (NTRS)

Rezaizadeh, M. A.; Mall, S.

1985-01-01

A combined experimental-analytical investigation to characterize the cyclic failure mechanism of a simple composite-to-composite bonded joint is conducted. The cracked lap shear (CLS) specimens of graphite/epoxy adherend bonded with EC-3445 adhesive are tested under combined mode 1 and 2 loading. In all specimens tested, fatigue failure occurs in the form of cyclic debonding. The cyclic debond growth rates are measured. The finite element analysis is employed to compute the mode 1, mode 2, and total strain energy release rates (i.e., GI, GII, and GT). A wide range of mixed-mode loading, i.e., GI/GII ranging from 0.03 to 0.38, is obtained. The total strain energy release rate, G sub T, appeared to be the driving parameter for cyclic debonding in the tested composite bonded system.

LAPS Lidar Measurements at the ARM Alaska Northslope Site (Support to FIRE Project)

NASA Technical Reports Server (NTRS)

Philbrick, C. Russell; Lysak, Daniel B., Jr.; Petach, Tomas M.; Esposito, Steven T.; Mulik, Karoline R.

1998-01-01

This report consists of data summaries of the results obtained during the May 1998 measurement period at Barrow Alaska. This report does not contain any data interpretation or analysis of the results which will follow this activity. This report is forwarded with a data set on magnetic media which contains the reduced data from the LAPS lidar in 15 minute intervals. The data was obtained during the period 15-30 May 1998. The measurement period overlapped with several aircraft flights conducted by NASA as part of the FIRE project. The report contains a summary list of the data obtained plus figures that have been prepared to help visualize the measurement periods. The order of the presentation is as follows: Section 1. A copy of the Statement of Work for the planned activity of the second measurement period at the ARM Northslope site is provided. Section 2. A list of the data collection periods shows the number of one minute data records stored during each hour of operation and the corresponding size (Mbytes) of the one hour data folders. The folder and file names are composed from the year, month, day, hour and minute. The date/time information is given in UTC for easier comparison with other data sets. Section 3. A set of 4 comparisons between the LAPS lidar results and the sondes released by the ARM scientists from a location nearby the lidar. The lidar results show the +/- 1 sigma statistical error on each of the independent 75 m altitude bins of the data. This set of 4 comparisons was used to set and validate the calibration value which was then used for the complete data set. Section 4. A set of false color figures with up to 10 hours of specific humidity measurements are shown in each graph. Two days of measurements are shown on each page. These plots are crude representations of the data and permit a survey which indicates when the clouds were very low or where interesting events may occur in the results. These plots are prepared using the real time sequence

A study of laser surface treatment in bonded repair of composite aircraft structures.

PubMed

Li, Shaolong; Sun, Ting; Liu, Chang; Yang, Wenfeng; Tang, Qingru

2018-03-01

Surface pre-treatment is one of the key processes in bonded repair of aircraft carbon fibre reinforced polymer composites. This paper investigates the surface modification of physical and chemical properties by laser ablation and conventional polish treatment techniques. Surface morphology analysed by laser scanning confocal microscopy and scanning electron microscopy showed that a laser-treated surface displayed higher roughness than that of a polish-treated specimen. The laser-treated laminate exhibited more functional groups in the form of O 1 s/C 1 s atomic ratio of 30.89% for laser-treated and 20.14% for polish-treated as evidenced by X-ray photoelectron spectroscopy observation. Contact angle goniometry demonstrated that laser treatment can provide increased surface free energy and wettability. In the light of mechanical interlocking, molecular bonding and thermodynamics theories on adhesion, laser etching process displayed enhanced bonding performance relative to the polishing surface treatment. These properties resulted in an increased single lap shear strength and a cohesive failure mode for laser etching while an adhesive failure mode occurred in polish-treated specimen.

A study of laser surface treatment in bonded repair of composite aircraft structures

NASA Astrophysics Data System (ADS)

Li, Shaolong; Sun, Ting; Liu, Chang; Yang, Wenfeng; Tang, Qingru

2018-03-01

Surface pre-treatment is one of the key processes in bonded repair of aircraft carbon fibre reinforced polymer composites. This paper investigates the surface modification of physical and chemical properties by laser ablation and conventional polish treatment techniques. Surface morphology analysed by laser scanning confocal microscopy and scanning electron microscopy showed that a laser-treated surface displayed higher roughness than that of a polish-treated specimen. The laser-treated laminate exhibited more functional groups in the form of O 1 s/C 1 s atomic ratio of 30.89% for laser-treated and 20.14% for polish-treated as evidenced by X-ray photoelectron spectroscopy observation. Contact angle goniometry demonstrated that laser treatment can provide increased surface free energy and wettability. In the light of mechanical interlocking, molecular bonding and thermodynamics theories on adhesion, laser etching process displayed enhanced bonding performance relative to the polishing surface treatment. These properties resulted in an increased single lap shear strength and a cohesive failure mode for laser etching while an adhesive failure mode occurred in polish-treated specimen.

A study of laser surface treatment in bonded repair of composite aircraft structures

PubMed Central

Sun, Ting; Liu, Chang; Yang, Wenfeng; Tang, Qingru

2018-01-01

Surface pre-treatment is one of the key processes in bonded repair of aircraft carbon fibre reinforced polymer composites. This paper investigates the surface modification of physical and chemical properties by laser ablation and conventional polish treatment techniques. Surface morphology analysed by laser scanning confocal microscopy and scanning electron microscopy showed that a laser-treated surface displayed higher roughness than that of a polish-treated specimen. The laser-treated laminate exhibited more functional groups in the form of O 1 s/C 1 s atomic ratio of 30.89% for laser-treated and 20.14% for polish-treated as evidenced by X-ray photoelectron spectroscopy observation. Contact angle goniometry demonstrated that laser treatment can provide increased surface free energy and wettability. In the light of mechanical interlocking, molecular bonding and thermodynamics theories on adhesion, laser etching process displayed enhanced bonding performance relative to the polishing surface treatment. These properties resulted in an increased single lap shear strength and a cohesive failure mode for laser etching while an adhesive failure mode occurred in polish-treated specimen. PMID:29657748

Gen. Paul J. Selva > Joint Chiefs of Staff > Article View

Science.gov Websites

aircraft systems and executive officer, Deputy Chief of Staff, Plans and Resources, Headquarters Strategic Facebook on Flickr Joint Chiefs Army Chief of Staff Marine Corps Commandant Chief of Naval Operations Air Force Chief of Staff Chief of National Guard Bureau Biographies Directorates Directorates of Management

Multirole cargo aircraft options and configurations. [economic analysis

NASA Technical Reports Server (NTRS)

Conner, D. W.; Vaughan, J. C., III

1979-01-01

A future requirements and advanced market evaluation study indicates derivatives of current wide-body aircraft, using 1980 advanced technology, would be economically attractive through 2008, but new dedicated airfreighters incorporating 1990 technology, would offer little or no economic incentive. They would be economically attractive for all payload sizes, however, if RD and T costs could be shared in a joint civil/military arrangement. For the 1994-2008 cargo market, option studies indicate Mach 0.7 propfans would be economically attractive in trip cost, aircraft price and airline ROI. Spanloaders would have an even lower price and higher ROI but would have a relatively high trip cost because of aerodynamic inefficiencies. Dedicated airfreighters using propfans at Mach 0.8 cruise, laminar flow control, or cryofuels, would not provide any great economic benefits. Air cushion landing gear configurations are identified as an option for avoiding runway constraints on airport requirements and/or operational constraints are noted.

The joint US-USSR biological satellite program

NASA Technical Reports Server (NTRS)

Souza, K. A.

1979-01-01

The joint US-USSR biological satellite missions carried out in 1975 and 1977 using Cosmos 782 and Cosmos 936 spacecraft, respectively, is reviewed. The experimental equipment and the biological specimens aboard the aircraft are considered, and it is noted that Cosmos 782, unlike Cosmos 936, carried no centrifuges for rats, although it did contain a centrifuge where a variety of biological specimens, including carrot tissue and fruit flies, were subjected to artificial gravity during space flight. The ground control groups, designed for biological experiments under simulated space-conditions, are taken into account. The U.S. experiments aboard the aircraft are described, with attention given to the experiments with rats, fish embryos, plants, and insects. Results of the experiments are noted, including the finding that space flight factors, especially weightlessness, have a measurable effect on the erythropoietic and musculoskeletal systems of rats

The Next Lightweight Fighter: Not Your Grandfather’s Combat Aircraft

DTIC Science & Technology

2013-08-01

devastat- ing Arabian quake in Somalia, which has almost no infrastructure and suffers from ongoing clan warfare. The United States deployed forces to...Kassim, which the quake had virtually leveled. A joint task force based in Djibouti stood up to direct the relief effort, exercising airborne com- mand...the earth prevent low-altitude or dis- tant aircraft from looking into “the next valley” directly. Consequently, many a reconnaissance mission or

Aircraft

DOEpatents

Hibbs, Bart D.; Lissaman, Peter B. S.; Morgan, Walter R.; Radkey, Robert L.

1998-01-01

This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gasses for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well.

Aircraft

DOEpatents

Hibbs, B.D.; Lissaman, P.B.S.; Morgan, W.R.; Radkey, R.L.

1998-09-22

This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing`s top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gases for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well. 31 figs.

Determination of Arsenic Poisoning and Metabolism in Hair by Synchrotron Radiation: The Case of Phar Lap

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

Kempson, Ivan M.; Henry, Dermot A.; U. South Australia)

2010-08-26

Fresh physical evidence about the demise of the racehorse Phar Lap (see photograph) has been gathered from the study of mane hair samples by synchrotron radiation analysis with high resolution X-ray fluorescence (XRF) and X-ray absorption near edge structure (XANES) analyses. The results are indicative of arsenic ingestion and metabolism, and show that the racing champion died from arsenic poisoning.

Joint University Program for Air Transportation Research, 1989-1990

NASA Technical Reports Server (NTRS)

Morrell, Frederick R. (Compiler)

1990-01-01

Research conducted during the academic year 1989-90 under the NASA/FAA sponsored Joint University Program for Air Transportation research is discussed. Completed works, status reports and annotated bibliographies are presented for research topics, which include navigation, guidance and control theory and practice, aircraft performance, human factors, and expert systems concepts applied to airport operations. An overview of the year's activities for each university is also presented.

A structural health monitoring fastener for tracking fatigue crack growth in bolted metallic joints

NASA Astrophysics Data System (ADS)

Rakow, Alexi Schroder

Fatigue cracks initiating at fastener hole locations in metallic components are among the most common form of airframe damage. The fastener hole site has been surveyed as the second leading initiation site for fatigue related accidents of fixed wing aircraft. Current methods for inspecting airframes for these cracks are manual, whereby inspectors rely on non-destructive inspection equipment or hand-held probes to scan over areas of a structure. Use of this equipment often demands disassembly of the vehicle to search appropriate hole locations for cracks, which elevates the complexity and cost of these maintenance inspections. Improved reliability, safety, and reduced cost of such maintenance can be realized by the permanent integration of sensors with a structure to detect this damage. Such an integrated system of sensors would form a structural health monitoring (SHM) system. In this study, an Additive, Interleaved, Multi-layer Electromagnetic (AIME) sensor was developed and integrated with the shank of a fastener to form a SHM Fastener, a new SHM technology targeted at detection of fastener hole cracks. The major advantages of the SHM Fastener are its installation, which does not require joint layer disassembly, its capability to detect inner layer cracks, and its capability to operate in a continuous autonomous mode. Two methods for fabricating the proposed SHM Fastener were studied. The first option consisted of a thin flexible printed circuit film that was bonded around a thin metallic sleeve placed around the fastener shank. The second option consisted of coating sensor materials directly to the shank of a part in an effort to increase the durability of the sensor under severe loading conditions. Both analytical and numerical models were developed to characterize the capability of the sensors and provide a design tool for the sensor layout. A diagnostic technique for crack growth monitoring was developed to complete the SHM system, which consists of the

14 CFR 21.6 - Manufacture of new aircraft, aircraft engines, and propellers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Manufacture of new aircraft, aircraft... Manufacture of new aircraft, aircraft engines, and propellers. (a) Except as specified in paragraphs (b) and (c) of this section, no person may manufacture a new aircraft, aircraft engine, or propeller based on...

NASA aeronautics R&T - A resource for aircraft design

NASA Technical Reports Server (NTRS)

Olstad, W. B.

1981-01-01

This paper discusses the NASA aeronautics research and technology program from the viewpoint of the aircraft designer. The program spans the range from fundamental research to the joint validation with industry of technology for application into product development. Examples of recent developments in structures, materials, aerodynamics, controls, propulsion systems, and safety technology are presented as new additions to the designer's handbook. Finally, the major thrusts of NASA's current and planned programs which are keyed to revolutionary advances in materials science, electronics, and computer technology are addressed.

Development and Evaluation of an Airborne Separation Assurance System for Autonomous Aircraft Operations

NASA Technical Reports Server (NTRS)

Barhydt, Richard; Palmer, Michael T.; Eischeid, Todd M.

2004-01-01

NASA Langley Research Center is developing an Autonomous Operations Planner (AOP) that functions as an Airborne Separation Assurance System for autonomous flight operations. This development effort supports NASA s Distributed Air-Ground Traffic Management (DAG-TM) operational concept, designed to significantly increase capacity of the national airspace system, while maintaining safety. Autonomous aircraft pilots use the AOP to maintain traffic separation from other autonomous aircraft and managed aircraft flying under today's Instrument Flight Rules, while maintaining traffic flow management constraints assigned by Air Traffic Service Providers. AOP is designed to facilitate eventual implementation through careful modeling of its operational environment, interfaces with other aircraft systems and data links, and conformance with established flight deck conventions and human factors guidelines. AOP uses currently available or anticipated data exchanged over modeled Arinc 429 data buses and an Automatic Dependent Surveillance Broadcast 1090 MHz link. It provides pilots with conflict detection, prevention, and resolution functions and works with the Flight Management System to maintain assigned traffic flow management constraints. The AOP design has been enhanced over the course of several experiments conducted at NASA Langley and is being prepared for an upcoming Joint Air/Ground Simulation with NASA Ames Research Center.

Application of Linear Array Imaging Techniques to the Real-Time Inspection of Airframe Structures and Substructures

NASA Technical Reports Server (NTRS)

Miller, James G. (Principal Investigator)

1996-01-01

Current concern for ensuring, the air-worthiness of the aging commercial air fleet has prompted the establishment of broad-agency programs to develop NDT technologies that address specific aging-aircraft issues. One of the crucial technological needs that has been identified is the development of rapid, quantitative systems for depot-level inspection of bonded aluminum lap joints on aircraft. Research results for characterization of disbond and corrosion based on normal-incidence pulse-echo measurement geometries are showing promise, but are limited by the single-site nature of the measurement which requires manual or mechanical scanning to inspect an area. One approach to developing efficient systems may be to transfer specific aspects of current medical imaging technology to the NDT arena. Ultrasonic medical imaging, systems offer many desirable attributes for large scale inspection. They are portable, provide real-time imaging, and have integrated video tape recorder and printer capabilities available for documentation and post-inspection review. Furthermore, these systems are available at a relatively low cost (approximately $50,000 to $200,000) and can be optimized for use with metals with straight-forward modifications.

The Joint Logistics Enterprise Enables Operation United Assistance

DTIC Science & Technology

2016-02-24

Sustainment July–August 2015 JLE U.S. service members board a C-130 Hercules aircraft Oct. 22, 2014, in Dakar, Senegal, to travel to Liberia to...including Liberia , as the “least developed in the world.” With numerous governance challenges, harsh weather, limited infrastructure over a... Liberia with the USARAF G–4, who was also the Joint Forces Com- mand ( JFC) J–4, and 7 personnel from his directorate. Because of the global reach of

World commercial aircraft accidents

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

Kimura, C.Y.

1993-01-01

This report is a compilation of all accidents world-wide involving aircraft in commercial service which resulted in the loss of the airframe or one or more fatality, or both. This information has been gathered in order to present a complete inventory of commercial aircraft accidents. Events involving military action, sabotage, terrorist bombings, hijackings, suicides, and industrial ground accidents are included within this list. Included are: accidents involving world commercial jet aircraft, world commercial turboprop aircraft, world commercial pistonprop aircraft with four or more engines and world commercial pistonprop aircraft with two or three engines from 1946 to 1992. Each accidentmore » is presented with information in the following categories: date of the accident, airline and its flight numbers, type of flight, type of aircraft, aircraft registration number, construction number/manufacturers serial number, aircraft damage, accident flight phase, accident location, number of fatalities, number of occupants, cause, remarks, or description (brief) of the accident, and finally references used. The sixth chapter presents a summary of the world commercial aircraft accidents by major aircraft class (e.g. jet, turboprop, and pistonprop) and by flight phase. The seventh chapter presents several special studies including a list of world commercial aircraft accidents for all aircraft types with 100 or more fatalities in order of decreasing number of fatalities, a list of collision accidents involving commercial aircrafts, and a list of world commercial aircraft accidents for all aircraft types involving military action, sabotage, terrorist bombings, and hijackings.« less

The Combined Effects of Aircraft and Road Traffic Noise and Aircraft and Railway Noise on Noise Annoyance-An Analysis in the Context of the Joint Research Initiative NORAH.

PubMed

Wothge, Jördis; Belke, Christin; Möhler, Ulrich; Guski, Rainer; Schreckenberg, Dirk

2017-08-02

The Noise Related Annoyance Cognition and Health (NORAH) research initiative is one of the most extensive studies on the physiological and psychological long-term effects of transportation noise in Europe. It includes research on the quality of life and annoyance as well as cardiovascular effects, sleep disturbance, breast cancer, blood pressure, depression and the cognitive development of children. Within the realm of the annoyance module of the study approximately 10,000 residents of the Rhine-Main district were surveyed on the combined effects of transportation noise. This included combined noise from aircraft and road traffic noise ( N = 4905), or aircraft and railway noise ( N = 4777). Results show that judgment of the total noise annoyance of participants was strongly determined by the sound source which was judged as more annoying (in this case aircraft noise). To a lesser extent, the average sound pressure level of the two present sources was also of relevance.

The Combined Effects of Aircraft and Road Traffic Noise and Aircraft and Railway Noise on Noise Annoyance—An Analysis in the Context of the Joint Research Initiative NORAH

PubMed Central

Wothge, Jördis; Belke, Christin; Möhler, Ulrich; Guski, Rainer; Schreckenberg, Dirk

2017-01-01

The Noise Related Annoyance Cognition and Health (NORAH) research initiative is one of the most extensive studies on the physiological and psychological long-term effects of transportation noise in Europe. It includes research on the quality of life and annoyance as well as cardiovascular effects, sleep disturbance, breast cancer, blood pressure, depression and the cognitive development of children. Within the realm of the annoyance module of the study approximately 10,000 residents of the Rhine-Main district were surveyed on the combined effects of transportation noise. This included combined noise from aircraft and road traffic noise (N = 4905), or aircraft and railway noise (N = 4777). Results show that judgment of the total noise annoyance of participants was strongly determined by the sound source which was judged as more annoying (in this case aircraft noise). To a lesser extent, the average sound pressure level of the two present sources was also of relevance. PMID:28767095

Reliability aspects of a composite bolted scarf joint. [in wing skin splice

NASA Technical Reports Server (NTRS)

Reed, D. L.; Eisenmann, J. R.

1975-01-01

The design, fabrication, static test, and fatigue test of both tension and compression graphite-epoxy candidates for a wing splice representative of a next-generation transport aircraft was the objective of the reported research program. A single-scarf bolted joint was selected as the design concept. Test specimens were designed and fabricated to represent an upper-surface and a lower-surface panel containing the splice. The load spectrum was a flight-by-flight random-load history including ground-air-ground loads. The results of the fatigue testing indicate that, for this type of joint, the inherent fatigue resistance of the laminate is reflected in the joint behavior and, consequently, the rate of damage accumulation is very slow under realistic fatigue loadings.

Fatigue crack growth in 2024-T3 aluminum under tensile and transverse shear stresses

NASA Technical Reports Server (NTRS)

Viz, Mark J.; Zehnder, Alan T.

1994-01-01

The influence of transverse shear stresses on the fatigue crack growth rate in thin 2024-T3 aluminum alloy sheets is investigated experimentally. The tests are performed on double-edge cracked sheets in cyclic tensile and torsional loading. This loading generates crack tip stress intensity factors in the same ratio as the values computed for a crack lying along a lap joint in a pressurized aircraft fuselage. The relevant fracture mechanics of cracks in thin plates along with the details of the geometrically nonlinear finite element analyses used for the test specimen calibration are developed and discussed. Preliminary fatigue crack growth data correlated using the fully coupled stress intensity factor calibration are presented and compared with fatigue crack growth data from pure delta K(sub I)fatigue tests.

Structural tests and development of a laminar flow control wing surface composite chordwise joint

NASA Technical Reports Server (NTRS)

Lineberger, L. B.

1984-01-01

The dramatic increases in fuel costs and the potential for periods of limited fuel availability provided the impetus to explore technologies to reduce transport aircraft fuel consumption. NASA sponsored the Aircraft Energy Efficiency (ACEE) program beginning in 1976 to develop technologies to improve fuel efficiency. The Lockheed-Georgia Company accomplished under NAS1-16235 Laminar-Flow-Control (LFC) Wing Panel Structural Design and Development (WSSD); design, manufacturing, and testing activities. An in-depth preliminary design of the baseline 1993 LFC wing was accomplished. A surface panel using the Lockheed graphite/epoxy integrated LFC wing box structural concept was designed. The concept was shown by analysis to be structurally efficient and cost effective. Critical details of the surface and surface joint was demonstrated by fabricating and testing complex, concept selection specimens. The Lockheed-Georgia Company accomplishments, Development of LFC Wind Surface Composite Structures (WSCS), are documented. Tests were conducted on two CV2 panels to verify the static tension and fatigue strength of LFC wing surface chordwise joints.

The Joint Damping Experiment (JDX)

NASA Technical Reports Server (NTRS)

Folkman, Steven L.; Bingham, Jeff G.; Crookston, Jess R.; Dutson, Joseph D.; Ferney, Brook D.; Ferney, Greg D.; Rowsell, Edwin A.

1997-01-01

The Joint Damping Experiment (JDX), flown on the Shuttle STS-69 Mission, is designed to measure the influence of gravity on the structural damping of a high precision three bay truss. Principal objectives are: (1) Measure vibration damping of a small-scale, pinjointed truss to determine how pin gaps give rise to gravity-dependent damping rates; (2) Evaluate the applicability of ground and low-g aircraft tests for predicting on-orbit behavior; and (3) Evaluate the ability of current nonlinear finite element codes to model the dynamic behavior of the truss. Damping of the truss was inferred from 'Twang' tests that involve plucking the truss structure and recording the decay of the oscillations. Results are summarized as follows. (1) Damping, rates can change by a factor of 3 to 8 through changing the truss orientation; (2) The addition of a few pinned joints to a truss structure can increase the damping by a factor as high as 30; (3) Damping is amplitude dependent; (4) As gravity induced preloads become large (truss long axis perpendicular to gravity vector) the damping is similar to non-pinjointed truss; (5) Impacting in joints drives higher modes in structure; (6) The torsion mode disappears if gravity induced preloads are low.

The Application of Unmanned Rotary-Wing Aircraft in Tactical Logistics in Support of Joint Operations

DTIC Science & Technology

2013-12-13

Reconnaissance Squadrons with a fixed-wing unmanned aircraft troop or company, and is in the market for an autonomous cargo unmanned rotary-wing...Warwick, Graham. “Sky Patrol.” Aviation Week & Space Technology 174, no. 32 (September 3, 2012): 55. Military & Government Collection, EBSCOhost

Determination of bulk diffusion lengths for angle-lapped semiconductor material via the scanning electron microscope: A theoretical analysis

NASA Technical Reports Server (NTRS)

Vonroos, O.

1978-01-01

A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.

Laser beam propagation through a full scale aircraft turboprop engine exhaust

NASA Astrophysics Data System (ADS)

Henriksson, Markus; Gustafsson, Ove; Sjöqvist, Lars; Seiffer, Dirk; Wendelstein, Norbert

2010-10-01

The exhaust from engines introduces zones of extreme turbulence levels in local environments around aircraft. This may disturb the performance of aircraft mounted optical and laser systems. The turbulence distortion will be especially devastating for optical missile warning and laser based DIRCM systems used to protect manoeuvring aircraft against missile attacks, situations where the optical propagation path may come close to the engine exhaust. To study the extent of the turbulence zones caused by the engine exhaust and the strength of the effects on optical propagation through these zones a joint trial between Germany, the Netherlands, Sweden and the United Kingdom was performed using a medium sized military turboprop transport aircraft tethered to the ground at an airfield. This follows on earlier trials performed on a down-scaled jet-engine test rig. Laser beams were propagated along the axis of the aircraft at different distances relative to the engine exhaust and the spatial beam profiles and intensity scintillations were recorded with cameras and photodiodes. A second laser beam path was directed from underneath the loading ramp diagonally past one of the engines. The laser wavelengths used were 1.5 and 3.6 μm. In addition to spatial beam profile distortions temporal effects were investigated. Measurements were performed at different propeller speeds and at different distances from exhaust nozzle to the laser path. Significant increases in laser beam wander and long term beam radius were observed with the engine running. Corresponding increases were also registered in the scintillation index and the temporal fluctuations of the instantaneous power collected by the detector.

Prediction of fracture toughness and durability of adhesively bonded composite joints with undesirable bonding conditions

NASA Astrophysics Data System (ADS)

Musaramthota, Vishal

Advanced composite materials have enabled the conventional aircraft structures to reduce weight, improve fuel efficiency and offer superior mechanical properties. In the past, materials such as aluminum, steel or titanium have been used to manufacture aircraft structures for support of heavy loads. Within the last decade or so, demand for advanced composite materials have been emerging that offer significant advantages over the traditional metallic materials. Of particular interest in the recent years, there has been an upsurge in scientific significance in the usage of adhesively bonded composite joints (ABCJ's). ABCJ's negate the introduction of stress risers that are associated with riveting or other classical techniques. In today's aircraft transportation market, there is a push to increase structural efficiency by promoting adhesive bonding to primary joining of aircraft structures. This research is focused on the issues associated with the durability and related failures in bonded composite joints that continue to be a critical hindrance to the universal acceptance of ABCJ's. Of particular interest are the short term strength, contamination and long term durability of ABCJ's. One of the factors that influence bond performance is contamination and in this study the influence of contamination on composite-adhesive bond quality was investigated through the development of a repeatable and scalable surface contamination procedure. Results showed an increase in the contaminant coverage area decreases the overall bond strength significantly. A direct correlation between the contaminant coverage area and the fracture toughness of the bonded joint was established. Another factor that influences bond performance during an aircraft's service life is its long term strength upon exposure to harsh environmental conditions or when subjected to severe mechanical loading. A test procedure was successfully developed in order to evaluate durability of ABCJ's comprising severe

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

Sabau, Adrian S; Warren, Charles David; ERDMAN III, DONALD L

Due to its increased use in the automotive and aerospace industries, joining of Carbon Fiber-reinforced Polymer matrix Composites (CFPC) to metals demands enhanced surface preparation and control of surface morphology prior to joining. In this study, surfaces of both composite and aluminum were prepared for joining using a new laser based technique, in which the laser interference power profile was created by splitting the beam and guiding those beams to the sample surface by overlapping each other with defined angles to each other. Results were presented for the overlap shear testing of single-lap joints made with Al 5182 and CFPCmore » specimens whose surfaces prepared by (a) surface abrasion and solvent cleaning; and (b) laser-interference structured surfaces by rastering with a 4 mm laser beam at approximately 3.5 W power. CFPC specimens of T700S carbon fiber, Prepreg T70 epoxy, 4 or 5 ply thick, 0/90o plaques were used. Adhesive DP810 was used to bond Al and CFPC. The bondline was 0.25mm and the bond length was consistent among all joints produced. First, the effect of the laser speed on the joint performance was evaluated by laser-interference structure Al and CFPC surfaces with a beam angle of 3o and laser beam speeds of 3, 5, and 10 mm/s. For this sensitivity study, 3 joint specimens were used per each joint type. Based on the results for minimum, maximum, and mean values for the shear lap strength and maximum load for all the 9 joint types, two joint types were selected for further evaluations. Six additional joint specimens were prepared for these two joint types in order to obtain better statistics and the shear test data was presented for the range, mean, and standard deviation. The results for the single-lap shear tests obtained for six joint specimens, indicate that the shear lap strength, maximum load, and displacement at maximum load for those joints made with laser-interference structured surfaces were increased by approximately 14.8%, 16%, and

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

1981-01-01

The development of several types of graphite/polyimide (GR/PI) bonded and bolted joints is reported. The program consists of two concurrent tasks: (1) design and test of specific built up attachments; and (2) evaluation of standard advanced bonded joint concepts. A data base for the design and analysis of advanced composite joints for use at elevated temperatures (561K (550 deg F)) to design concepts for specific joining applications, and the fundamental parameters controlling the static strength characteristics of such joints are evaluated. Data for design and build GR/PI of lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Results for compression and interlaminar shear strengths of Celion 6000/PMR-15 laminates are given. Static discriminator test results for type 3 and type 4 bonded and bolted joints and final joint designs for TASK 1.4 scale up fabrication and testing are presented.

Novel Ambler class A beta-lactamase LAP-1 and its association with the plasmid-mediated quinolone resistance determinant QnrS1.

PubMed

Poirel, Laurent; Cattoir, Vincent; Soares, Ana; Soussy, Claude-James; Nordmann, Patrice

2007-02-01

The plasmid-mediated quinolone resistance determinant QnrS1 was identified in non-clonally related Enterobacter cloacae isolates in association with a transferable narrow-spectrum beta-lactam resistance marker. Cloning experiments allowed the identification of a novel Ambler class A beta-lactamase, named LAP-1. It shares 62 and 61% amino acid identity with the most closely related beta-lactamases, TEM-1 and SHV-1, respectively. It has a narrow-spectrum hydrolysis of beta-lactams and is strongly inhibited by clavulanic acid and sulbactam and, to a lesser extent, by tazobactam. Association of the blaLAP-1 gene with the qnrS1 gene was identified in E. cloacae isolates from France and Vietnam. These genes were plasmid located and associated with similar insertion sequences but were not associated with sul1-type class 1 integrons, as opposed to the qnrA genes.

Raptors and aircraft

USGS Publications Warehouse

Smith, D.G.; Ellis, D.H.; Johnson, T.H.; Glinski, Richard L.; Pendleton, Beth Giron; Moss, Mary Beth; LeFranc, Maurice N.=; Millsap, Brian A.; Hoffman, Stephen W.

1988-01-01

Less than 5% of all bird strikes of aircraft are by raptor species, but damage to airframe structure or jet engine dysfunction are likely consequences. Beneficial aircraft-raptor interactions include the use of raptor species to frighten unwanted birds from airport areas and the use of aircraft to census raptor species. Many interactions, however, modify the raptor?s immediate behavior and some may decrease reproduction of sensitive species. Raptors may respond to aircraft stimuli by exhibiting alarm, increased heart rate, flushing or fleeing and occasionally by directly attacking intruding aircraft. To date, most studies reveal that raptor responses to aircraft are brief and do not limit reproduction; however, additional study is needed.

Millimeter-Wave Localizers for Aircraft-to-Aircraft Approach Navigation

NASA Technical Reports Server (NTRS)

Tang, Adrian J.

2013-01-01

Aerial refueling technology for both manned and unmanned aircraft is critical for operations where extended aircraft flight time is required. Existing refueling assets are typically manned aircraft, which couple to a second aircraft through the use of a refueling boom. Alignment and mating of the two aircraft continues to rely on human control with use of high-resolution cameras. With the recent advances in unmanned aircraft, it would be highly advantageous to remove/reduce human control from the refueling process, simplifying the amount of remote mission management and enabling new operational scenarios. Existing aerial refueling uses a camera, making it non-autonomous and prone to human error. Existing commercial localizer technology has proven robust and reliable, but not suited for aircraft-to-aircraft approaches like in aerial refueling scenarios since the resolution is too coarse (approximately one meter). A localizer approach system for aircraft-to-aircraft docking can be constructed using the same modulation with a millimeterwave carrier to provide high resolution. One technology used to remotely align commercial aircraft on approach to a runway are ILS (instrument landing systems). ILS have been in service within the U.S. for almost 50 years. In a commercial ILS, two partially overlapping beams of UHF (109 to 126 MHz) are broadcast from an antenna array so that their overlapping region defines the centerline of the runway. This is called a localizer system and is responsible for horizontal alignment of the approach. One beam is modulated with a 150-Hz tone, while the other with a 90-Hz tone. Through comparison of the modulation depths of both tones, an autopilot system aligns the approaching aircraft with the runway centerline. A similar system called a glide-slope (GS) exists in the 320-to-330MHz band for vertical alignment of the approach. While this technology has been proven reliable for millions of commercial flights annually, its UHF nature limits

Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives.

PubMed