Identification and sizing of the entirely visible rocks from a 3D surface data segmentation of laboratory rock piles

Once segmentation of 3D surface data of a rock pile has been performed, the next task is to determine the visibility of the surface rocks. A region boundary-following algorithm that accommodates irregularly spaced 3D coordinate data is presented for determining this visibility. We examine 3D surface segmentations of laboratory rock piles and determine which regions in the segmentation correspond to entirely visible rocks, and which correspond to overlapped or partially visible rocks. This is a significant distinction as it allows accurate size determination of entirely visible rocks, separate handling of partially visible rocks, and prevents erroneous bias resulting from mishandling partially visible rocks as smaller entirely visible rocks. Literature review indicates that other rock pile sizing techniques fail to make this distinction. The rock visibility results are quantified by comparison to manual surface classifications of the laboratory piles and the size results are quantified by comparison to the sieve size.     

A high-speed and continuous 3D measurement system

A new system for high-speed and continuous 3D measurement is presented. It is based on the slit-ray projection method. The key component is the image plane constructed by a position-sensitive device (PSD) array that is horizontally un segmented and linear, but vertically numbered. All PSD row elements are attached to their respective analog signal processors. The analog signals are multiplexed and digitized by multiplexers and A/D converters at appropriate sampling intervals and stored in memory. By virtue of this configuration of the image plane, basis data for 3D measurement are acquired during only one scan of the slit ray at high speed in the form of memory addresses and data. Moreover, if we use large capacity and/or dual port memories, we can continuously obtain 3D range data for as many scenes as needed. The trial system has been implemented with a newly designed 128-channel PSD array and has verified our method, enabling us to obtain successive 3D range data at video rates with an error within±0.3%.     

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 a distributed representative human model generation and analysis system (DRHM-GAS): Application to optimization of flight suit and pilot oxygen mask sizing systems

A computerized system is needed for effective determination of the sizing system of a multiple-size product. The present study developed a distributed representative human model generation and analysis system (DRHM-GAS) which can generate various sizing system candidates for a target population using different DRHM generation methods and evaluate the sizing system candidates. A five-step DRHM generation procedure (target population characterization, anthropometric variable selection, key dimension selection, grid formation, and DRHM size determination) was developed and implemented into the DRHM-GAS. A generated sizing system candidate is evaluated in the DRHM-GAS by a set of metrics including multivariate accommodation percentage and the number of sizing categories. The effectiveness of the DRHM-GAS was examined with two case studies of the development of optimal sizing systems for men's flight suit design based on the anthropometric data of US Army pilots and pilot oxygen mask design based on the facial anthropometric data of ROKAF pilots. The DRHM-GAS would be of use for product designers to establish an appropriate sizing system with efficiency.     

Optical microflow cytometer for particle counting, sizing and fluorescence detection

A novel on-chip optical flow cytometer concept is reported for fluorescence detection, enumeration, and sizing of microparticles in a poly-dimethylsiloxane (PDMS) microchip. The detection system integrates a pair of external optical fibers and other optical components for particle counting, sizing and fluorescence analysis in each measurement simultaneously. The scattered light signal indicates the total number and the size of the particles passing through the detection window, whereas the concurrent backward fluorescence signal shows only the number of fluorescence particles. In the experiments, microparticles of four different sizes with diameters ranging from 3.2 to 10.2 μm were discriminated and counted based on the fluorescence and scattered light intensity. The relative percentage of the fluorescence-labeled particles can be analyzed by the ratio of the events of fluorescence signals to forward scattered signals.     

Automated sizing of automotive steering ball joints in parametric CAD environment using expert knowledge and feature-based computer-assisted 3D modelling

Ball joints used in the steering systems of vehicles are exposed to fluctuating loads, which can cause fatal accidents in case of failure. The design of ball joints is an iterative and time-consuming process. Even though the automotive industry is preparing for the era of autonomous self-steering vehicles, parts such as ball joints were not designed using a fully automated parametric design methodology. Recently, parametric design of automotive ball joints based on variable design methodology using knowledge and feature-based computer-assisted-3D modelling methods was studied. However, these studies do not give details of the interactive sizing process within the part and assembly module to determine the final dimensions for avoidance of fatigue failure.This work provides methods and discusses details of the configurable sizing of a ball joint assembly under the boundaries of the developed “parametric design platform”. The platform closes the software gap for the automated reconfiguration and sizing of the ball joint assembly using a three-dimensional (3D) modelling technique. The platform can parametrically change part, material, feature, geometry, assembly and dimension features in a programmable environment. It can also reconfigure the ball joint assembly model considering various structured data conforming to technical standards and reasoning mechanisms with “engineering and geometrical relations” provided in this work, and data gathering along the life cycle of a product. Parameterised 3D solid models and a knowledge base of ball joints are stored in a database, and then an evaluation process within the platform that is capable of sizing ball joints for infinite fatigue-life has been established to verify sizing. It demonstrates the practicability and validity of the automated sizing of a steering ball joint within a configurable design environment and with minimum human expert knowledge and interaction.     

3D standard avatar creation of Korean women in their twenties and thirties by body types for apparel industry

The purposes of this study are to classify body types of Korean women in their twenties and thirties for the creation of the 3D avatars and to propose the representative body size of each body type by analyzing the body size of Korean women in their twenties and thirties, to propose a 3D avatar modeling process design that reflects the body shapes of Korean women in their twenties and thirties, and to present standard 3D avatars of each body type of Korean women in their twenties and thirties which are verified with measurement suitability. The 3D anthropometric data of the Korean Anthropometric Survey (6th Size Korea) conducted in 2010 was used in this study. The collected subjects were 410 Korean women in their twenties and thirties. The 3D avatar modeling process using Maya 2013 was proposed to create the representative 3D avatars show superior measurement suitability. This process includes four steps; Analyzing body size measurements, 2D Image plane design, 3D avatar modeling, and 3D avatar evaluation. The 3D avatars created with this process showed the acceptable range of error. The factor analysis was performed on fifty-five body measurements chosen from the measurements of the 6th Size Korea anthropometric survey. Seven factors were extracted. With the seven extracted factors, body shapes of 406 Korean women in their twenties and thirties are classified into four groups by cluster analysis. The classified groups were named Full & Short, Slim & Short, Full & Tall, and Slim & Tall.     

Development of a particle number and particle mass vehicle emissions inventory for an urban fleet

Motor vehicles are major emitters of gaseous and particulate matter pollution in urban areas, and exposure to particulate matter pollution can have serious health effects, ranging from respiratory and cardiovascular disease to mortality. Motor vehicle tailpipe particle emissions span a broad size range from 0.003 to 10 μm, and are measured as different subsets of particle mass concentrations or particle number count. However, no comprehensive inventories currently exist in the international published literature covering this wide size range. This paper presents the first published comprehensive inventory of motor vehicle tailpipe particle emissions covering the full size range of particles emitted. The inventory was developed for urban South-East Queensland by combining two techniques from distinctly different disciplines, from aerosol science and transport modelling. A comprehensive set of particle emission factors were combined with transport modelling, and tailpipe particle emissions were quantified for particle number (ultrafine particles), PM₁, PM_2.5 and PM₁₀ for light and heavy duty vehicles and buses. A second aim of the paper involved using the data derived in this inventory for scenario analyses, to model the particle emission implications of different proportions of passengers travelling in light duty vehicles and buses in the study region, and to derive an estimate of fleet particle emissions in 2026. It was found that heavy duty vehicles (HDVs) in the study region were major emitters of particulate matter pollution, and although they contributed only around 6% of total regional vehicle kilometres travelled, they contributed more than 50% of the region's particle number (ultrafine particles) and PM₁ emissions. With the freight task in the region predicted to double over the next 20 years, this suggests that HDVs need to be a major focus of mitigation efforts. HDVs dominated particle number (ultrafine particles) and PM₁ emissions; and LDV PM_2.5 and PM₁₀ emissions. Buses contributed approximately 1–2% of regional particle emissions.     

Particle systems for adaptive, isotropic meshing of CAD models

We present a particle-based approach for generating adaptive triangular surface and tetrahedral volume meshes from computer-aided design models. Input shapes are treated as a collection of smooth, parametric surface patches that can meet non-smoothly on boundaries. Our approach uses a hierarchical sampling scheme that places particles on features in order of increasing dimensionality. These particles reach a good distribution by minimizing an energy computed in 3D world space, with movements occurring in the parametric space of each surface patch. Rather than using a pre-computed measure of feature size, our system automatically adapts to both curvature as well as a notion of topological separation. It also enforces a measure of smoothness on these constraints to construct a sizing field that acts as a proxy to piecewise-smooth feature size. We evaluate our technique with comparisons against other popular triangular meshing techniques for this domain.     

Sizing optimization of truss structures using flower pollination algorithm

The recently developed flower pollination algorithm is used to minimize the weight of truss structures, including sizing design variables. The new algorithm can efficiently combine local and global searches, inspired by cross-pollination and self-pollination of flowering plants, respectively. Furthermore, it implements an iterative constraint handling strategy where trial designs are accepted or rejected based on the allowed amount of constraint violation that is progressively reduced as the search process approaches the optimum. This strategy aims to obtain always feasible optimized designs. The new algorithm is tested using three classical sizing optimization problems of 2D and 3D truss structures. Optimization results show that the proposed method is competitive with other state-of-the-art metaheuristic algorithms presented in the literature.     

A computational framework for automating generation of sizing function in assembly meshing via disconnected skeletons

This paper proposes a framework for generating mesh sizing functions for assembly models. Size control is crucial in obtaining a high-quality mesh with a reduced number of elements. The reduction in the number of elements will decrease computation time and memory use during mesh generation and analysis. The framework consists of a background octree lattice for storing the sizing function, a set of source entities for providing sizing information based on geometric information, and an interpolation module for calculating the sizing on the background octree lattice using the source entities. Source entities are generated by performing a detailed systematic study to identify all the geometric factors of an assembly. Disconnected skeletons are extracted and used as tools to measure 3D proximity and 2D proximity, which are two of the geometric factors. The framework facilitates the generation of a variety of meshes with a low computational cost, to meet industry needs. The framework has been tested on many industrial parts, and sizing control on a few typical assemblies has been presented to demonstrate the effectiveness of the proposed framework.     

Freeway traffic estimation within particle filtering framework

This paper formulates the problem of real-time estimation of traffic state in freeway networks by means of the particle filtering framework. A particle filter (PF) is developed based on a recently proposed speed-extended cell-transmission model of freeway traffic. The freeway is considered as a network of components representing different freeway stretches called segments. The evolution of the traffic in a segment is modelled as a dynamic stochastic system, influenced by states of neighbour segments. Measurements are received only at boundaries between some segments and averaged within possibly irregular time intervals. This limits the measurement update in the PF to only these time instants when a new measurement arrives, while in between measurement updates any simulation model can be used to describe the evolution of the particles. The PF performance is validated and evaluated using synthetic and real traffic data from a Belgian freeway. An unscented Kalman filter is also presented. A comparison of the PF with the unscented Kalman filter is performed with respect to accuracy and complexity.     

接触式多关节三维扫描仪研究

论述了拥有自主知识产权的接触式多关节三维扫描仪3DLCS-400的硬件系统和软件系统的基本构成、主要特点和实现方法。在此基础上,研究了接触式三维信息获取中的一些关键技术———数据采集与三维显示的同步、坐标计算和误差校正、三维构型重建。采用基于API函数的异步多线程串行通信和OpenGL三维显示技术,提出了一种修正最小二乘法和基因可变限改进遗传算法相结合的参数标定方法和运用轮廓线的三维散乱数据构型方法。该产品的研制成功填补了国产三维信息获取系统的一个空白。     

Improving fit of bicycle helmet liners using 3D anthropometric data

3D anthropometry has provided much-needed information about the size and shape of the head, which can be used to improve the fit of protective helmets. In this study, a new 3D head scan sizing method was implemented in a reverse engineering approach for bicycle helmet liner dimensioning. The inside liner of a commercially available helmet was modified to improve the fit for a selected size group of 30 participants. The fit of the standard and new liner were assessed and compared, using the Helmet Fit Index (HFI). The HFI scores showed a significant improvement of overall fit (Difference: 11.32 ± 7.82 (μ ± SD), p < 0.0005) and for each of five defined regions of the liner inside surface. The presented methodology for dimensioning helmet liners based on 3D anthropometry proved effective, resulting in improved fit for the end users.     

基于粒子系统与OpenGL的实时雨雪模拟

自然景物的模拟一直是计算机图形学中最具挑战性的问题之一。关于水、云、烟．雨、雪等自然景物的模拟，在计算机游戏、三维动画、影视及广告中有着广泛的应用。自然景观中雨、雪的模拟，可以大大提高三维场景的逼真度，Reeves提出的粒子系统是模拟雨、雪的一种有效的方法。论文在分析粒子系统实现原理的基础上，基于OpenGL提出了一种在大型场景漫游系统中实时模拟雨．雪的方法。基本思想是基于OpenGL的多视口与色彩融合技术，把模拟雨、雪的粒子在一个新的视口中视线有效区域内进行绘制，然后与原视口中的场景一起显示于窗口中。实践证明，该方法实现的雨雪模拟效果比较真实，而且在普通PC上也可以满足一般动画的实时性要求。     

低成本个性化制造原型系统关键技术

传统制造业一般基于大规模生产方式,个性化产品生产成本较高。利用低成本三维扫描、三维打印技术,提出一套低成本的个性化制造原型系统。该系统首先利用深度相机采集个性化几何数据、对数据去噪配准、生成较高质量的重建网格;上传用户信息,进行个性化产品在线设计;最后利用家用三维打印设备或在线三维打印服务进行制作。为了验证提出的方案,实现了眼镜架个性化设计与制造原型系统。     

Towards a mean body for apparel design

This paper focuses on shape average with applications to the apparel industry. Apparel industry uses a consensus sizing system; its major concern is to fit most of the population into it. Since anthropometric measures do not grow linearly, it is important to find prototypes to accurately represent each size. This is done using random compact mean sets, obtained from a cloud of 3D points given by a scanner and applying to the sample a previous definition of mean set. Additionally, two approaches to define confidence sets are introduced. The methodology is applied to data obtained from a real anthropometric survey.     

A new approach to optimization of viscoelastic beams: minimization of the input/output transfer function $\boldsymbol {H}_{\infty }$-norm

A new approach to structural optimization in dynamic regime is presented that is based on the minimization of the \(H_{\infty }\) norm of the transfer function between the external loads and the structural response. The method is successfully applied to the sizing optimization of viscoelastic beams as shown by extensive numerical investigations that are presented in much detail. The abstract nature of the proposed approach makes it applicable to a wide class of dynamical systems including 2D and 3D systems within general topology optimization frameworks that are object of ongoing analysis.     

Skeleton-based computational method for the generation of a 3D finite element mesh sizing function

This paper focuses on the generation of a three-dimensional (3D) mesh sizing function for geometry-adaptive finite element (FE) meshing. The mesh size at a point in the domain of a solid depends on the geometric complexity of the solid. This paper proposes a set of tools that are sufficient to measure the geometric complexity of a solid. Discrete skeletons of the input solid and its surfaces are generated, which are used as tools to measure the proximity between geometric entities and feature size. The discrete skeleton and other tools, which are used to measure the geometric complexity, generate source points that determine the size and local sizing function at certain points in the domain of the solid. An octree lattice is used to store the sizing function as it reduces the meshing time. The size at every lattice-node is calculated by interpolating the size of the source points. The algorithm has been tested on many industrial models, and it can be extended to consider other non-geometric factors that influence the mesh size, such as physics, boundary conditions, etc.Sandia National Laboratory is a multiprogram laboratory operated by the Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy under contract DE-AC04-94AL85000.     

On flow-blocking particle structures in microtubes

Given their small size, microchannels are susceptible to being blocked by small amounts of solid matter. The lifetime of certain microfluidic devices depends on their ability to maintain flow without interruption, and certain microfluidic applications require devices that include the transport of either liquids that may contain impurities or liquids that intentionally contain particles. Under the conditions studied in the present experiments, flow-stopping blockages were observed for the flow of liquids with the surprisingly low volume concentrations of = 0.005–0.056 of polystyrene particles (d_p of the order of tens of microns) through circular microtubes with diameters (D) of the order of 100 m. The quantity of interest is the occurrence of a flow-stopping blockage in the flow of a suspension of hard spheres, over the range of from 0.2 to 0.5 and < 0.06. The percentage of runs for which a blockage did or did not occur versus nominal d_p/D is presented. Given that higher concentrations of particles have been used in many previous studies of suspension flows, the occurrence of blockages at these concentrations was initially unexpected. Based upon the data and the parameters varied in the current study, the blockages are more likely to occur when the nominal particle-to-tube diameter ratios are approximately 0.3–0.4.Research partially supported by Defense Advanced Research Projects Agency (DARPA), Microsystems Technology Office (MTO) Grant#F33615-98-1-2853 and The National Science Foundation under grant No. CTS-0348149