Evaluation of fall arrest harness sizing schemes

OBJECTIVE: This paper evaluated harness sizing schemes and anthropometric criteria for harness design applications. BACKGROUND: Updated harness sizing systems are needed to accommodate diverse populations in the current workforce. METHOD: Three-dimensional torso scan data and human-harness interfaces from 108 women and 108 men were digitally captured. Abounding box approach was employed to quantify the effect of torso shape and size on fall harness fit. RESULTS: A logistic regression model with eight equations was developed and tested to classify more than 96% of participants to the best-fitting size. CONCLUSION: Study outcomes suggested an alternative system of two sizes for women and three sizes for men over the current four-size unisex system. In addition, thigh strap angle and back D ring location could be utilized along with current harness static fit test criteria to further enhance postfall harness fit predictions. APPLICATION: This research could help reduce the risk of worker injury resulting from poor fit, improper size selection, or failure to don the harness properly.     

Sizing and fit of fall-protection harnesses

Full-body fall-protection harnesses have been a critical work-practice control technology for reducing the number of fall-related injuries and fatalities among construction workers; yet, very little is known about the fit of these harnesses to the population that wears them. This study evaluated the fit and sizing efficacy of a harness system. Seventy-two male and 26 female construction workers participated in the study. Their body size-and-shape information was measured while they were suspended (with a harness) and standing (with and without a harness), using a 3-D full-body laser scanner and traditional anthropometric calipers. Fisher's discriminant analysis results did not point to the need for a change in the current sizing selection scheme by body height and weight for end users. However, an integrated redesign of harness components is needed because 40% of subjects did not pass fit-performance criteria in either the standing or suspended condition. A multivariate accommodation analysis has identified 15 representative body models for the 'standard-size' harness design. These models can serve as a useful population to test harness design until a larger survey of the nation's construction workers can be done. Finally, further developments in 3-D shape quantification methods are recommended to improve the harness design process; the point-to-point anthropometric information currently used seems to be insufficient for harness design.     

Sizing and fit of fall-protection harnesses

Full-body fall-protection harnesses have been a critical work-practice control technology for reducing the number of fall-related injuries and fatalities among construction workers; yet, very little is known about the fit of these harnesses to the population that wears them. This study evaluated the fit and sizing efficacy of a harness system. Seventy-two male and 26 female construction workers participated in the study. Their body size-and-shape information was measured while they were suspended (with a harness) and standing (with and without a harness), using a 3-D full-body laser scanner and traditional anthropometric calipers. Fisher's discriminant analysis results did not point to the need for a change in the current sizing selection scheme by body height and weight for end users. However, an integrated redesign of harness components is needed because 40% of subjects did not pass fit-performance criteria in either the standing or suspended condition. A multivariate accommodation analysis has identified 15 representative body models for the 'standard-size' harness design. These models can serve as a useful population to test harness design until a larger survey of the nation's construction workers can be done. Finally, further developments in 3-D shape quantification methods are recommended to improve the harness design process; the point-to-point anthropometric information currently used seems to be insufficient for harness design.     

Estimation of the kinetic energy dissipation in fall-arrest system and manikin during fall impact

Fall-arrest systems (FASs) have been widely applied to provide a safe stop during fall incidents for occupational activities. The mechanical interaction and kinetic energy exchange between the human body and the fall-arrest system during fall impact is one of the most important factors in FAS ergonomic design. In the current study, we developed a systematic approach to evaluate the energy dissipated in the energy absorbing lanyard (EAL) and in the harness/manikin during fall impact. The kinematics of the manikin and EAL during the impact were derived using the arrest-force time histories that were measured experimentally. We applied the proposed method to analyse the experimental data of drop tests at heights of 1.83 and 3.35 m. Our preliminary results indicate that approximately 84-92% of the kinetic energy is dissipated in the EAL system and the remainder is dissipated in the harness/manikin during fall impact. The proposed approach would be useful for the ergonomic design and performance evaluation of an FAS. STATEMENT OF RELEVANCE: Mechanical interaction, especially kinetic energy exchange, between the human body and the fall-arrest system during fall impact is one of the most important factors in the ergonomic design of a fall-arrest system. In the current study, we propose an approach to quantify the kinetic energy dissipated in the energy absorbing lanyard and in the harness/body system during fall impact.     

Development of new shoe sizing system for women based on regression analysis of foot shapes

This study aims to demonstrate a new method of developing a shoe sizing system with a standard fitting for each size for Bangladeshi women based on foot measurements. In this study, bivariate correlation analysis was carried out to determine key foot dimensions of 976 women aged 20 to 60. Simple linear regression analyses of key parameters against foot length (FL) were conducted, and the regression equations assisted in determining grading value and size-fit combinations. Nine sizes with three fittings (narrow, standard, and wide) each were generated where the grading values were 6 mm, 5 mm, 2 mm, and 4 mm for FL, joint girth (JG), joint width (JW), and arch length (AL), respectively. Cross-tabulation analysis verified the sizing system with a coverage rate 94.98% of JG, 88.02% of JW, and 98.77% of AL, where standard fittings covered the maximum number of participants. This study could benefit women in choosing accurate shoe sizes for their feet to ensure proper shoe fitting.Relevance to industryThe proposed new shoe sizing system could assist the footwear industries in manufacturing women's shoes in different sizes with appropriate sizing and grading values, which will provide better fitting than existing systems. In addition, industries could produce shoes with a smaller number of size-fit combinations to accommodate most women's feet.     

Apparel sizing using trimmed PAM and OWA operators

This paper is concerned with apparel sizing system design. One of the most important issues in the apparel development process is to define a sizing system that provides a good fit to the majority of the population. A sizing system classifies a specific population into homogeneous subgroups based on some key body dimensions. Standard sizing systems range linearly from very small to very large. However, anthropometric measures do not grow linearly with size, so they can not accommodate all body types. It is important to determine each class in the sizing system based on a real prototype that is as representative as possible of each class. In this paper we propose a methodology to develop an efficient apparel sizing system based on clustering techniques jointly with OWA operators. Our approach is a natural extension and improvement of the methodology proposed by McCulloch, Paal, and Ashdown (1998), and we apply it to the anthropometric database obtained from a anthropometric survey of the Spanish female population, performed during 2006.     

The Grid Rotation Method and Its Application to the Glove Sizing System

In this article, we propose a grid rotation method for glove sizing to accommodate a greater fraction of the population with a given number of sizes. The method is based on the optimization of two geometric variables, the rotation degree and the number of grid points. Instead of applying a traditional tabulation method to the original samples, we apply the tabulation after rotating the sample points by a certain degree to improve coverage. We further optimize the grid points for the same purpose. Our results demonstrate the effectiveness of the proposed method. For the glove sizing system developed by the proposed grid rotation method, the coverage rate is increased by 2.3% compared to previous work for the same number of glove sizes.     

Evidentialist foundationalist argumentation for multi-agent sensor fusion

In this paper, an approach to evidence-based argumentation called Evidentialist Foundationalist Argumentation (EFA) is formally defined in terms of the ASPIC framework. The EFA framework is then used as the basis for general argument patterns applied to the problem domain of Sensor Fusion. These general Sensor Fusion argument patterns serve as templates for concrete arguments constructed by agents in an in situ Sensor Web. These agents use EFA to solve specific instances of the Decentralized Sensor Fusion problem by strategically sharing evidence from their arguments using a Share on Disagreement protocol. Using real-world data, the performance of this multiagent system is compared to the performance of another multiagent system employing a Kalman Filtering approach. The results are statistically analyzed using omega-squared effect sizes produced by ANOVA with p values <  0.05. The EFA based system is found to outperform the Kalman Filtering system in terms of accuracy with mostly high and medium effect sizes. The Kalman Filtering system is found to outperform the EFA based system in terms of communication costs with mostly low effect sizes.     

The complex method applied to optimal truss configuration

The Complex Method of Box is applied to the determination of optimal member sizes and geometric configuration for minimum weight of 3-dimensional truss structures. Design constraints include bounds on member size, joint coordinates, member stresses, Euler buckling and joint displacements. The displacement method of structural analysis is used and the system is assumed to be linearly elastic. Statically indeterminate structures under multiple loading conditions can be optimized and the sizing as well as the geometric design variables may be linked. Limited topological changes are permitted for designs which have small member forces.The design spaces for sizing and geometric variables are separated. Geometry is modified by the Complex Method and member sizes by stress ratio and a scaling procedure for stiffness.The method is applied to two numerical examples from the literature. Results indicate favourable design improvements and rates of convergence. Substantial additional improvement resulting from member deletion is demonstrated.     

Physically based real-time interactive assembly simulation of cable harness

In this paper, we designed and developed an interactive assembly simulation system of cable harness. First, we establish a real-time physical model of cable harness based on an extension of the mass–spring model. We use various kinds of springs to describe the different properties of the cable harness: linear springs for stretching, bending springs for bending, and torsion springs for geometrical torsion and material twisting. The constraints of connectors and clips on cable harness are both considered. We also associate the elastic coefficients of various springs with the material parameters of the cable. Moreover, we use spherical bounding volume hierarchy and triangular facets for collision detection of cable harness during the assembly simulation. By applying contact forces to both ends of the cable links that collide with the surrounding environment, we obtain the real-time contact response of cable harness. Finally, we apply the proposed model to a cable assembly task. The results show that the proposed model successfully expressed the deformation of the cable harness and the interactive manipulation is computationally efficient.     

Sizing and grading methods with consideration of footwear styles

Sizing and grading are very important in footwear production, directly influencing the fit and comfort of footwear. Currently, the footwear industry relies on traditional sizing and grading systems, which vary around the world. Modern measuring technologies, such as 3D scanning and modeling, are starting to be used in footwear mass production. Sizing and grading of footwear is closely related to the sizing and grading of foot. This study investigates the application of principal component analysis (PCA) in sizing and grading methods and the influence of footwear styles based on 3D foot shapes. Three sizing and grading methods were simulated and evaluated. Results show that, compared to the traditional method, the sizing and grading using PCA method provides less modeling error, hence will result in better fit. Furthermore, the prediction error for various footwear styles are significantly different and the footwear fit near the sole could be achieved easier than instep and ankle region. This indicates that various sizing and grading rules can be applied focusing on different footwear styles in order to develop optimal sizes.Relevance to industryThe proposed new sizing and grading method could benefit the footwear industry since it provides a better fit comparing to the traditional method. The influence of footwear styles on prediction error gives more detailed insights for manufacturers to further understand the fitting result when applying the different sizing and grading methods.     

Optimum buckling design of compression panels using VICONOPT

The structural efficiency of a range of panels under uniaxial compression is investigated using the optimum buckling design program VICONOPT. The design uses very efficient VIPASA analysis to guard against all possible modes of failure, together with a tailored sizing strategy. The panels all have nine blades, zed or hat stiffeners and between three and fifteen design variables, covering traditional design using one size of stiffener and more sophisticated design with five sizes of stiffener. Results show that using two stiffener sizes or two stiffener types in alternate positions across the panel width can produce mass savings of up to 30% compared with traditional design. Convergence on an optimum normally occurs within six sizing cycles, but up to twelve sizing cycles are required for sophisticated designs when the initial configuration is poorly chosen. Computational efficiency and material strength constraints are also considered.     

Sizing and grading for wearable products

Sizing and grading are widely used to create products to fit selected populations. Currently, the sizing and grading rules are derived from anthropometric measures; however past researches have indicated that it is not very accurate. This study proposes a new technique to use principal component analysis (PCA) on 3D surface points for sizing and grading wearable products. The accuracy of the proposed method is illustrated by developing a sizing and grading rule for the feet. After developing a model using the feet data of 60 participants and validating using the feet data of 10 different participants, results showed that sizing and grading using PCA is more accurate than traditional techniques. Compared with traditional foot sizing, PCA based sizing and grading showed an improvement of about 25% in accuracy. In addition, results also indicated that the grading rule derived from PCA loading was better than the proportional grading. This research provides a new direction to consider when developing the sizing and grading rules. It can be extended to calculate the number of sizes and the size increment for various wearable products.     

Development of an automated flexible fixture for planar objects

A three fingered automated flexible fixturing system has been developed to fixture planar objects in a machining process. The fixturing system consists of two computer numerically controlled (CNC) modules, an auxiliary mechanism and a fixturing algorithm. This fixture is designed on the idea of the minimum number of fingers needed to immobilise an object. The fixturing algorithm is developed on the concept of the maximal inscribed circle in a polygon. It offers the flexibility to reconfigure the fingers of the system to accommodate workpieces of different shapes and sizes. A prototype of the system has been successfully built and tested, showing satisfactory performance in mechanical design and automatic control over the configurations of the fingers. Examples are given of the application of the system with objects of different shapes. The system is shown to be flexible, reconfigurable and automatic, capable of fixturing planar objects of different shapes and sizes in the machining process.     

Exploiting dynamic micro-architecture usage in gate sizing

Modern high performance microprocessors incorporate an abundance of replicated structural components. Many of these components often experience substantially lower utilization while executing a diverse pool of applications. To recover energy efficiency from the lower utilization, system architects resort to dynamic voltage frequency scaling (DVFS). In this paper, we demonstrate that dynamic adaptations using DVFS are markedly energy inefficient than techniques that design circuits ground up for lower performance. We propose a novel microarchitecture aware gate sizing and threshold voltage assignment algorithm to mitigate this current limitation. Our technique is the first of its kind that exploits architectural slack in gate sizing, and leverages on-chip redundancy and slack. We evaluate this circuit-architectural co-optimization framework in a superscalar processor by combining standard cell based gate sizing flows with state-of-the-art architectural simulation. Our results show 17-46% improvement in the datapath energy efficiency over traditional circuit designs incorporating DVFS schemes.     

Silk road dance exhibition system based on motion capture

Silk Road dance is an excellent traditional Chinese dance drama, which has high artistic values. This article introduces the virtual performance techniques of Silk Road based on motion capture. First, obtain the dance data using motion capture technique according to the features of dance itself, then establish figure model, finally combines these data to make 3-D animation system to perform Silk Road, meanwhile designs some interfaces to introduce it. This system excavates details of the dance, and can be reference of man-machine interaction and animation production.     

基于PC104的水下航行器导航系统设计

导航系统是水下航行器的重要组成部分,为了实现水下航行器的精确导航,采用了以PC104工控计算机为核心、GPS定位和惯性导航相结合的导航系统的改进方案,给出了导航系统的工作原理及基本硬件组成,介绍了惯性测量单元、GPS、电子罗盘等传感器与主控计算机进行通讯的各个软件模块的功能,并使用了异步卡尔曼滤波器进行数据融合与航位推算;该系统在提高导航精度的同时还具有通用性,可适用于不同类型的水下航行器。     

Development of a framework for truss-braced wing conceptual MDO

The paper describes the development of a multidisciplinary design optimization framework for conceptual design of truss-braced wing configurations. This unconventional configuration requires specialized analysis tools supported by a modular and flexible framework to accommodate different configurations. While the previous framework developed at Virginia Tech was a monolithic Fortran-77 code, the need for more flexibility for complex truss-braced wing configurations was addressed by the development of this new framework, which is based on Phoenix Integration ModelCenter^TM environment. The framework uses updated structural and aerodynamic design modules that enable a more general geometry definition. The new framework, thus, provides a foundation for future design concepts, especially multi-member truss-braced wing configurations. The fuel saving potential of these truss-braced wing configurations is presented by comparing different truss designs with gradually increased level of complexity.     

Truck sizing models for recyclables pick-up

Growing public concerns about the environmental consequences of waste disposal have led to an increase in recycling efforts. In many communities, curbside collection programs have been instituted for collecting recyclables from households for transfer to material recovery facilities. In most programs the cost of collection is the dominant cost. Despite the high cost and environmental importance of collecting recyclables from households, most municipal collection systems are designed and operated without a clear understanding of what factors drive those costs and how they might be reduced. In this paper, models for determining truck configurations, as well as optimal compartment sizes for recyclables collection are developed. Constraints arising from the operation of the trucks are formulated, and solution schemes are presented. In addition, a procedure for optimally partitioning a vehicle used to collect source-separated material is discussed. Several scenario based planning approaches are developed. Use of the truck sizing models as an industry decision tool and the associated benefits of applying the truck sizing models and the solution methodology to a contract based collection program are also discussed.