Effects of external light load on posture and foot pressure distribution in young adults: A pilot study

Holding an asymmetrical load, like a rucksack, grocery bag, or travel backpack, is a part of daily and occupational activities. This pilot study was aimed to determine the effects of light, asymmetrical, handheld load on the body posture and foot pressure distribution in young adults. Thirteen young volunteers, free of any injury or pain, took part in the study (aged 21.53 ± 1.10 years). All the study participants were right-handed. An additional load (4 kg, placed in the rucksack) was asymmetrically held in each hand while standing still. For evaluation of the posture and foot pressure distribution, the investigation focused on three positions, i.e., no-load, a rucksack in the right hand, a rucksack in the left hand. We used a surface topography system and force platform for evaluation of the body posture and foot pressure examination, respectively. The results showed that the main changes in the body posture caused by an external load application manifested in trunk imbalance. The trunk was shifted in the direction opposite to the load. Trunk imbalance changes were statistically significant in all three comparisons (p = 0.001). Interestingly, changes in the rotations and lateral deviation seem to be dependent on the hand dominance. Greater foot pressure was observed on the loaded limb (p < 0.01), and highly significant differences were noted between the left and right foot in both loaded postures (p < 0.001). Further research needs to be done to check if lateralization is connected with body posture while holding an external load.     

Optimal design of gear pumps for exhaust gas aftertreatment applications

In this paper an innovative procedure for determining the optimal design of an external spur gear pump for a particular emission reduction application in automobiles has been proposed. The pump forms the main part of a mechatronic system that controls the flow rate of a mixture of urea in water to catalytically reduce emissions in diesel engines. The proposed research proves to be an advance in gear machine design by using a multi-objective based genetic algorithm, to determine the optimal design of the gears and the casing by maximizing the volumetric efficiency, minimizing pressure overshoots, localized cavitation and noise emissions. The research uses HYGESim (HYdraulic GEar machines Simulator) simulation tool, which is being developed by the authors’ research group, for calculating the important performance features of the machine. The best designs for the machine based on enhancement in performance are presented. Results in terms of simulations and tests which validate the effectiveness of the proposed novel design methodology are also presented.     

A new external sorting algorithm with no additional disk space

This paper is concerned with an external sorting algorithm with no additional disk space. The proposed algorithm is a hybrid one that uses Quicksort and special merging process in two distinct phases. The algorithm excels in sorting a huge file, which is many times larger than the available memory of the computer. This algorithm creates no extra backup file for manipulating huge records. For this, the algorithm saves huge disk space, which is needed to hold the large file. Also our algorithm switches to special merging process after the first phase that uses Quicksort. This reduces the time complexity and makes the algorithm faster.     

On power of p systems using sequential and parallel rewriting

A new class of distributed computing models inspired from biology, that of P Systems, was recently introduced by Gh. P[acaron]un. Several variants of P Systems were already shown to be computationally universal, equal in power to Turing Machines. We investigate in this paper the power of computability of P Systems based on rewriting, with cooperation, priorities and external output. It is established that rewriting P Systems with priorities and two membranes is computationally universal, thereby making an improvement in the existing result that RE?RP ₃(Pri). We give a new model in P Systems stressing the importance of parallelism. The power of computability of such models is investigated by comparing them with classic mechanisms in L-Systems: TOL, EOL and ETOL Systems     

A survey of leaning and bracing behaviours in an automotive assembly plant

It is common for workers to use objects within the task environment to externally support themselves, when performing a task. We refer to this as ‘leaning’, when using the contralateral hand for support, or ‘bracing’, when using the trunk, hips or thighs for support. However, currently, ergonomists are unable to predict when these behaviours will occur when performing proactive ergonomic assessments, leading to incorrect estimates of how the jobs will be performed. The purpose of this survey was to quantify the types of external support used by workers during automotive assembly tasks. 250 automotive assembly jobs were observed, and the external support behaviours were documented using a 13-item survey adapted from Jones et al. (2008). We observed that 103 jobs (41.2%) were performed with the use of leaning and/or bracing. Of those, workers leaned, braced, or used both behaviours simultaneously 54.5%, 22.0%, and 23.5% of the time, respectively. Leaning was most prevalent at a height of 150 cm, while bracing was most prevalent at a height of 50 cm. This survey catalogues the leaning and bracing behaviours from a large array of assembly jobs. The trends we have identified can be used by ergonomists to predict whether or not external support is likely to be used by a worker during a certain task.     

VRML与外部程序交互的研究

对VRML与外部程序的各种交互原理进行了研究,并对其中两种高级用户交互方式进行了详细比较。在此基础上,运用该原理在Web页上实现了具有用户动态三维交互功能的弹簧振子仿真模型。     

An application of psychophysical ratings to external force estimation

An estimation of external force applied during hand-intensive work at actual work site has practical restrictions since direct measurement requires much equipment and time. This paper proposes a method that can estimate external forces applied at actual working environment on the basis of results of lab experiment. The psychophysical rating, specifically CR-10 scale developed by G. Borg, is adopted as the major tool to estimate external forces. This study also shows the general shape of the external force distribution for the most oommon and potentially risky hand postures of hand-intensive jobs.     

基于带约束人工蜂群算法和平均Hausdorff距离的重力匹配方法

重力匹配算法是实现重力辅助惯性导航系统的关键技术之一。但是,传统重力匹配方法存在复杂度高、应用范围小等缺陷,一般很难实现精确、快速匹配的效果。将人工蜂群算法用于重力匹配的搜索过程,并将多普勒测速仪提供的速度信息作为限制条件对蜂群搜索过程进行约束。在此基础上,利用平均Hausdorff距离对匹配结果进行筛选,在重力数据库中重力异常精度一定的条件下,可降低误配率。仿真结果表明,该匹配算法在重力特征显著的区域具有较高的匹配率,可以达到精确、快速的匹配定位,从而实现重力辅助导航。     

虚拟现实建立动态场景的研究

随着虚拟现实技术的发展,对虚拟现实场景不仅要求有逼真的效果,同时还要求有生动的交互功能,而VRML(Vitual Reality Modeling Language)与Java的结合是目前常用的交互式虚拟现实技术。文章系统介绍了虚拟现实建模语言VRML,采用JAVA做为脚本建立动态场景的原因并具体介绍了VRML与Java结合建立动态交互场景的两种方式,以及JSAI和EAI的区别。     

2D vertex modeling for the simulation of grain growth and related phenomena

A vertex model for the simulation of grain growth and grain boundary migration is developed and its implementation is explained in detail. The utilization of the model is also exemplified with different setups. In particular, the model was used to study the evolution of magnetically affected grain growth in samples with randomly oriented grains and the effect of the finite mobility of the boundary junctions on boundary migration. These examples emphasize the versatility of the model and illustrate its ample scope. The results of the simulations showed that a magnetic field can effectively affect the evolution of the grain growth kinetics and texture independently of the initial texture since the magnetic field will cause grains, with particular orientations, to have an advantage for their growth. As consequence, the sample will become strongly textured during grain growth. Theoretical considerations for the grain boundary migration with a finite mobility of the triple junctions were also reproduced and confirmed by means of computer simulation. The simulation results showed a very good agreement with the theoretical expectations.