Light Assembly Research Articles

Failure detection in automotive light assemblies during vibration endurance testing

As the automotive industry becomes increasingly competitive, parts manufacturers are under extreme pressure to improve the quality of their parts, while at the same time reducing costs. The method currently used to detect failures in automotive light assemblies during vibration endurance testing involves manual inspection only after the test is completed. In most cases, this method does not allow the first onset of failure to be determined. Subsequent damage caused by the ongoing test after the initial failure often obliterates the clues to what failed first, thus diminishing the usefulness of the information collected as input to design improvement iterations. An adaptable, reliable, and low-cost real-time monitoring and diagnostic system that would interrupt the testing operation at the first onset of a failure is desired. This paper describes an accelerometer-based and a microphone-based monitoring system for automotive light assembly failure detection during endurance testing. The vibration and acoustic signal analysis methods are also described. Preliminary results from these two systems show a significant difference between healthy and faulty fog light assemblies, which can be detected. This suggests that there is potential to develop these and potentially other measures for use in an adaptable, reliable, and low-cost real-time monitoring and diagnostic system that would interrupt the testing operation at the first onset of a failure. Further testing is planned to determine the sensitivity of the methods used in this study to detect the earliest onset of failure damage during endurance testing of automotive light assemblies.

Biomechanical shoulder loads and postures in light automotive assembly workers: Comparison between shoulder pain/no pain groups

The number of workplace shoulder compensation claims resulting from musculoskeletal disorders (MSDs) has decreased slightly in recent years, however the median number of days off work remains unchanged, which suggests an increase in injury severity. Little information is available regarding cumulative shoulder exposures, and there is no information on their impact on shoulder pain. Seventy-nine automotive seat frame assembly workers completed a questionnaire about the prevalence and severity of shoulder pain and were videotaped performing assembly tasks. 3DMatch, a posture-matching software program, was used to calculate the peak and cumulative shoulder moments and forces by matching postures seen in the video with predetermined ranges of posture to be used in the biomechanical model. Of the 45.6% who reported shoulder pain, there was a mild correlation of pain severity with posterior shear of the shoulder. There were no significant differences in peak loads between Pain and No Pain groups; however, the No Pain group experienced significantly more cumulative caudal shear. Although there was no difference in percent time spent in different flexed postures between pain groups, those working some jobs may be at an increased risk of developing MSDs based on the amount of time spent in flexed postures, as well as the peak flexion moment acting on the shoulder.

Simulation of Pregnant Workers Performing a Standing Assembly Task

This paper attempts to answer the question: “In what ways can a pregnancy simulator accurately replicate the pregnant condition during a standing light assembly task?” Thirty non-pregnant women performed a standing assembly task, once while wearing a Pregnancy Simulator and once without it. Additionally, four pregnant women participated without wearing the simulator. Data concerning perception of discomfort and the simulator's ability to mimic the pregnant condition were collected. The key areas of inquiry on the questionnaire were, discomfort during trials, the extent to which various body parts were uncomfortable, and the perceived accuracy of the simulator's ability to model the pregnant condition. Subjects reported four pregnancy symptoms as being accurately modeled by the simulator; breathing difficulties, obstructed movement, general fatigue, and body image. However, the results also indicated that the simulator did not adequately replicate the pregnant condition as it related to overall discomfort.

Simulation of Pregnant Workers Performing a Standing Assembly Task

This paper attempts to answer the question: “In what ways can a pregnancy simulator accurately replicate the pregnant condition during a standing light assembly task?” Thirty non-pregnant women performed a standing assembly task, once while wearing a Pregnancy Simulator and once without it. Additionally, four pregnant women participated without wearing the simulator. Data concerning perception of discomfort and the simulator's ability to mimic the pregnant condition were collected. The key areas of inquiry on the questionnaire were, discomfort during trials, the extent to which various body parts were uncomfortable, and the perceived accuracy of the simulator's ability to model the pregnant condition. Subjects reported four pregnancy symptoms as being accurately modeled by the simulator; breathing difficulties, obstructed movement, general fatigue, and body image. However, the results also indicated that the simulator did not adequately replicate the pregnant condition as it related to overall discomfort.

Life cycle and unit-cost analysis for modular reconfigurable flexible light assembly systems

The article presents a decision support methodology for the selection of a modular reconfigurable assembly system using three-dimensional visualization, component-based simulation, efficiency, and economic analysis methodology. During the design and selection of an assembly system, measurement schemes should be established for determining and understanding design effectiveness. Measurements can be classed into two categories: cost and performance. Understanding assembly production costs is the first step towards increasing profits. The authors have developed an analysis method that integrates factory simulation, overall equipment efficiency (OEE), and economic analysis methods. Cost calculation includes life cycle cost (LCC), cost of ownership (COO), commonly used investment evaluation methods, discounted cash flow techniques, net present value (NPV), and internal rate of return (IRR). The idea is to use these integrated analysis methods in the selection and development of a light assembly system. The development is based on selected industrial standards and the authors’ own experience in assembly system design and simulation. The developed TCO (total cost of ownership) methodology is useful in system supplier and end-user communication; ideally, it is used in the assembly system sales process, it helps in trade-off analysis of the system concepts, and it improves system specification.

Precision of measurements of physical workload during standardized manual handling part III: Goniometry of the wrists

Goniometry of the wrist is a feasible method for studying wrist movements in most hand-intensive work. The precision and accuracy of the method per se is good. For the knowledge on validity of field measurements, the size of imprecision is of importance. This study evaluated this condition during standardized circumstances. Six women performed three different hand-intensive work tasks: ‘materials picking’, ‘light assembly’, and ‘heavy assembly’, repeated during three different days. Variance components between-days (within subjects) and between-subjects were derived for positions (flexion/extension and deviation) and movements, including angular velocities, % of time with very low velocity (<1°/s), as well as repetitiveness. For positions, the average standard deviations in the three tasks were, both between-days and between-subjects, 3–4°. For movements, the coefficients of variation of angular velocities were about 10% between-days, and could to a great part be explained by differences in work rate. Between-subjects variability was higher, 20–40%. The variability was larger at low velocities than at high ones. The precision of the measured positions was good, expressed as small between-days and between-subjects variability. For movements, the between-days variability was also small, while there was a larger between-subjects variability. The imprecision of goniometry is consequently lower and comparable with inclinometry but lower than for EMG.

Relationship between leader‐subordinate personality congruence and performance and satisfaction in the UK

PurposeThis study aims to investigate the relationship between leader‐subordinate congruence and performance and satisfaction.Design/methodology/approachData were gathered from 267 leader‐subordinate dyads in a light manufacturing electrical assembly plant in Wales and 82 leader‐subordinate dyads in another, in England, UK. Data on personality of the respondents and their supervisors were gathered using the 16 personality factor test. The absolute difference between the personality score of the respondent and the supervisor for each of the five secondary personality factors were calculated. The absolute differences were then totalled to obtain a total difference score.FindingsAs expected, there was a significant correlation between the difference scores and satisfaction with the supervisor and overall job satisfaction. The results suggest that, if management wishes to improve satisfaction of their subordinates, the personalities of supervisor and subordinate should be similar. The direction of the relationship between difference scores and performance scores in the two companies were in opposite directions to each other. Possible causes and implications for managers are discussed.Originality/valueThis paper establishes that the relationship between congruence and performance is contingent on the nature of work interaction between the leader and the subordinate.

Effect of electric field on the hydrodynamics of fluidized nanoparticles

The effect of electric field on the hydrodynamics of nanoparticles was studied in a fluidized rectangular bed, with electrodes attached to two parallel walls. It was shown that the electric field of the order of 3 times the gravity markedly decreased the bed expansion and increased the solids volume fraction of nanoparticles fluidized by air. In these experiments, a light diode assembly was utilized to infer the local solids volume fractions within a rectangular bed of 10 nm silica particles. These experimental measurements yielded a two dimensional solids volume fraction distribution within the rectangular bed. The experimental results provided some new insights into the distribution of solids within the bed. The agglomerate diameters were computed using a momentum balance with the drag given by the Ergun equation and the empirical Richardson–Zaki method. Both methods yielded agglomerate diameters of the order of 100 μm and showed dependence on the strength of the electric field. The electric field decreased the granular temperature of the nanoparticles.

Quantum Dot Solar Cells Based on CdSe-Assembled Titania Semiconductors

AbstractIn the study, semiconductor quantum dots (QDs) of CdSe nanocrystals have been demonstrated effective as the light energy harvesting assemblies in solar cells. Colloidal CdSe QDs were synthesized by the one-pot approach and linked through a surface modifier onto titania (TiO2) nanoparticles. The TiO2-CdSe composite, while employed as the photoanode in a photoelectrochemical apparatus, exhibited a higher photon-to-electron conversion efficiency (3-fold) than the TiO2 alone, and also a higher stability for photocurrent generation, according to photocurrent transient responses. The optical absorbance and photoluminescence of the CdSe colloid showed a blue shift in the absorption edge with decreasing the particle size (band energy gap shifts from 2.0 to 2.19 eV), suggesting a quantum size effect. The CdSe particle size was determined up to 5 nm by a transmission electron microscopy. A scheme describing the charge carrier rectification for the coupled semiconductor system is proposed.

Harvesting Infrared Photons with Croconate Dyes

Excited-state properties of the croconate dyes were investigated with an aim to utilize them as light harvesting assemblies in the infrared (IR) region (λmax ∼ 865 nm and M−1 c−1 = (1.4−4.2) × 105 M−1 s−1). The excited singlet of the monomeric dye quickly deactivates (lifetime 4−7 ps) without undergoing intersystem crossing to generate triplet. The triplet excited-state produced via triplet–triplet energy transfer method show relatively long life (lifetime 7.2 µs). The dye molecules when deposited as thin film on optically transparent electrodes or on nanostructured TiO2 film form H-aggregates with a blue-shifted absorption maximum around 660 nm. The excitons formed upon excitation of the dye aggregates undergo charge separation at the TiO2 and SnO2 interface. The H-aggregates in the film are photoactive and produce anodic current (IPCE of 1.2% at 650 nm) when employed in a photoelectrochemical cell. Spectroscopic and photoelectrochemical experiments that highlight the usefulness of croconate dyes in IR l...

Guideline threshold limit values (TLVs) for discomfort in repetitive assembly work

AbstractThis study focused on two of the main occupational risk factors associated with work‐related musculoskeletal disorders in light repetitive electronic assembly work, namely repetition and force. Present‐day evaluation techniques are primarily posture based and show low sensitivity with regard to rating repetition and force. A simulated assembly task was conducted to investigate the interactions of risk factors and the suitability of hand activity level (HAL) and TLV values for electronics assembly work. Subjects completed the assembly task for three levels of repetition and force. For each treatment a subjective rating of discomfort was recorded. Repeated measures ANOVA identified repetition and force as highly significant factors in light electronic assembly work ( p &lt; .001, p &lt; .05, respectively). The task was also rated using HAL and normalized peak forces (NPF). This study questioned the ability of TLVs in rating discomfort and amendments to the TLVs are suggested. © 2007 Wiley Periodicals, Inc. Hum Factors Man 17: 423–434, 2007.

SCALE analysis of CLAB decay heat measurements for LWR spent fuel assemblies

A set of decay heat measurements for spent fuel assemblies recently carried out at the Swedish central interim storage facility for spent fuel, CLAB, was analyzed with the SCALE code system. The measurements include a variety of light water reactor assemblies that cover a large burnup range – up to 51 GWd/MTU – and a cooling time domain of interest to spent fuel storage and transportation applications. The results of the analysis show a good agreement between measured and predicted decay heat, with the calculated decay heat in general within the range of the uncertainty of the measured value. The effect of various assembly data on the calculated decay heat is analyzed and discussed. Uncertainties that may arise from various approaches and assumptions in the computational model are identified and examined.

High resolution science with high redshift galaxies

We summarize the high-resolution science that has been done on high redshift galaxies with Adaptive Optics (AO) on the world’s largest ground-based facilities and with the Hubble Space Telescope (HST). These facilities complement each other. Ground-based AO provides better light gathering power and in principle better resolution than HST, giving it the edge in high spatial resolution imaging and high resolution spectroscopy. HST produces higher quality, more stable PSF’s over larger field-of-views in a much darker sky-background than ground-based AO, and yields deeper wide-field images and low-resolution spectra than the ground. Faint galaxies have steadily decreasing sizes at fainter fluxes and higher redshifts, reflecting the hierarchical formation of galaxies over cosmic time. HST has imaged this process in great structural detail to z ≲ 6, and ground-based AO and spectroscopy has provided measurements of their masses and other physical properties with cosmic time. Last, we review how the 6.5 m James Webb Space Telescope (JWST) will measure First Light, reionization, and galaxy assembly in the near–mid-IR after 2013.

Solid-State Pressure-Tolerant Illumination for MBARI's Underwater Low-Light Imaging System

A significant amount of energy is consumed by the typical illumination systems of underwater vehicles. Attempts to utilize more efficient LED illumination underwater have been unsuccessful because the light-emitting diodes (LEDs) were coupled to a standard imaging system and they were not able to generate enough light to adequately illuminate the scene. In cases where the LEDs were grouped together, to provide more scene illumination, the lighting assembly was inefficient in size. The recent availability of high intensity LEDs provides a way to produce efficient and adequate lighting from a compact assembly. This paper covers the development of a deep ocean assembly based on these high intensity LEDs

Full-scale industrial wood floor assembly and structures by welded-through dowels

High-speed dowel rotation welding was used to manufacture a full-scale raised access floor, hence an applicable civil engineering structure, to demonstrate that scaling up of the welding technique is feasible. This was coupled with obtaining a more light weight floor assembly at equal stiffness by maximizing the rigidity of the suspended floor while minimizing the number of timber boards used to build it, and maintaining its vibration frequency high and its level of vibration low. Several assembly and connection combinations of two and three boards linked through welded wood dowels were tried out to determine the resistance of the cross-over joints that had to be used for building the floor. Deformation under 4 points static load of the floor was carried out to determine displacement under load and the floor vibration behaviour was determined using accelerometers. The fundamental first natural frequency measured does satisfy the requirements specified by Eurocode 5 well.

Putting safety first

This article describes the use of digital camera enforcement for improving road safety. The author notes that, while traffic rule following has improved in much of the world, red light violations at signalized intersections is still a major problem in the United States with 95,000 crashes and 1,000 deaths per year being due to such infractions. Products briefly described include stationary speed monitors, red light monitoring, toll enforcement, and mobile speed monitors. Also described is a light assembly tower that attempts to provide an aesthetically pleasing structure in addition to housing the sensors used for data collection. The article also describes a system that includes data redundancy: by collecting both radar and photographic evidence in the form of sixteen successive exposures, infractions can be prosecuted using virtually incontrovertible evidence.

Singlet and Triplet Excited-State Interactions and Photochemical Reactivity of Phenyleneethynylene Oligomers

The rigid rodlike character of phenyleneethynylenes and their ability to communicate charge/excitation energy over long distances have made them useful as molecular linkers in the light energy harvesting assemblies and molecular electronics devices. These linker molecules themselves possess rich photochemistry as evident from the relatively large yields of the excited singlet (0.5-0.66) and triplet (0.4-0.5) states of two model oligomers, 1,4-bis(phenylethynyl)-2,5-bis(hexyloxy)benzene (OPE-1) and 1,4-bis((4-phenylethynyl)phenylethynyl)-2,5-bis(hexyloxy)benzene (OPE-2). In particular, the long-lived triplet excited state is capable of undergoing deactivation by self-quenching processes such as ground-state quenching and triplet-triplet (T-T) annihilation. The T-T annihilation occurs with a nearly diffusion-controlled rate (approximately 2 x 10(9) M(-1) s(-1)), and ground-state quenching occurs with a rate constant of approximately 6 x 10(7) M(-1) s(-1). The electron transfer from the excited OPE-1 and OPE-2 to benzoquinone as characterized from the transient absorption spectroscopy illustrates the ability of these molecules to shuttle the electrons to acceptor moieties. In addition, pulse radiolysis experiments confirm the spectroscopic fingerprint of the cation radical (or "trapped hole") with absorption bands in the 500-600 nm region.

Improved Effector Functions of a Therapeutic Monoclonal Lewis Y-Specific Antibody by Glycoform Engineering

The aim of the present study was to produce glycosylation variants of the therapeutic Lewis Y-specific humanized IgG1 antibody IGN311 to enhance cell-killing effector function. This was achieved via genetic engineering of the glycosylation machinery of the antibody-producing host. Antibody genes were transiently cotransfected with acetyl-glycosaminyltransferase-III genes into human embryonic kidney-EBV nuclear antigen cells. A control wild-type antibody, IGN311wt, was expressed in the same host using identical expression vectors, but without cotransfection of genes for acetyl-glycosaminyltransferase-III expression. Both expression products were purified to homogeneity and characterized. The glyco-engineered expression product (IGN312-Glyco-I) showed a remarkably homogenous N-linked glycosylation pattern consisting of one major hybrid-type, non-fucosylated and agalactosylated form carrying a bisecting GlcNAc-group. Wild-type expression product (IGN311wt) on the other hand was glycosylated by a multitude of different core-fucosylated complex-type structures of variable degrees of galactosylation. Target affinity of the glyco-engineered antibody as well as heavy and light chain assembly were not affected by acetyl-glycosaminyltransferase-III expression. In vitro experiments showed a approximately 10-fold increase of antibody-dependent cellular cytotoxicity of the glyco-engineered antibody using different Lewis Y-positive target cancer cell lines (SK-BR-3, SK-BR-5, OVCAR-3, and Kato-III). Complement-mediated cytotoxicity of IGN312-Glyco-I was 0.4-fold reduced using SK-BR-5 as target cell line. The reduction of complement activation could be prevented and even converted into a slight increase of activity by using a different molecular-biological approach directing the glycosylation towards increased levels of complex N-linked oligosaccharides of bisected, non-fucosylated type, as a result of cotransfection of mannosidase II together with acetyl-glycosaminyltransferase-III.

소형 부품 자동화 조립시스템의 근골격계질환 예방을 위한 인간공학적 개선안 연구

Ergonomic intervention techniques were adopted to assess and control potential risk factors of work-related musculoskeletal disorders(WMSDs) in the automated light assembly manufacturing system. Ten different kinds of assembly workstations implemented with a conveyor system and twelve female workers were observed and evaluated with careful video film analysis. Several close examinations using sets of checklists established by qualified safety and health organizations, such as NIOSH, OSHA, and ANSI, were conducted and every workers and staffs in the site participated in the self-report questionnaires and off-line interviews. Typical risk factors and symptoms of the upper extremity musculoskeletal disorders were found and categorized into specific parts of body. To reduce risk factors of WMSDs and improve system productivity new revised workstation standards, physical dimensions, were suggested accordant with anthropometric characteristics of workers and a heuristic decision strategy of rotating shift work schedules according to work contents has proposed to mitigate cumulative physical stress. Finally, ergonomic programs of entire company to prevent WMSDs were structured.

Decision Support in Concurrent Engineering – The Utility-Based Selection Decision Support Problem

Decisions are an important part of Concurrent Engineering and engineering design in general. Accordingly, more attention should be paid to the means and methods for making these decisions. In this article, a utility-based decision support method for the selection of an engineering design is presented. The utility-based selection decision support problem (u-sDSP) is a synthesized construct that facilitates selection decisions involving trade-offs among multiple, conflicting attributes and mitigation of risk associated with uncertain performance with respect to the attributes considered. The negative impact of unnecessary iterations on the product development cycle is reduced via the assurance of preference-consistent outcomes. Specifically, utility theory provides a mathematically rigorous means of clarifying and capturing designer preferences as well as identifying a preferred alternative in the context of stochastic uncertainty, while the selection decision support problem (DSP) – the construct within which utility theory is employed – facilitates the effective use of engineering judgment for (1) formulating and bounding decisions and (2) establishing a proper context. Application of the u-sDSP is illustrated with an example from rapid prototyping (RP), in which the goal is to select the appropriate technology and material combinations for testing the snap-fit design of a light switch cover plate assembly.