A low-cost real time virtual system for postural stability assessment at home

Background and objective

The degeneration of the balance control system in the elderly and in many pathologies requires measuring the equilibrium conditions very often. In clinical practice, equilibrium control is commonly evaluated by using a force platform (stabilometric platform) in a clinical environment.In this paper, we demonstrate how a simple movement analysis system, based on a 3D video camera and a 3D real time model reconstruction of the human body, can be used to collect information usually recorded by a physical stabilometric platform.

Methods

The algorithm used to reconstruct the human body model as a set of spheres is described and discussed. Moreover, experimental measurements and comparisons with data collected by a physical stabilometric platform are also reported. The measurements were collected on a set of 6 healthy subjects to whom a change in equilibrium condition was stimulated by performing an equilibrium task.

Results

The experimental results showed that more than 95% of data collected by the proposed method were not significantly different from those collected by the classic platform, thus confirming the usefulness of the proposed system.

Conclusions

The proposed virtual balance assessment system can be implemented at low cost (about 500$) and, for this reason, can be considered a home use medical device. On the contrary, astabilometric platform has a cost of about 10,000$ and requires periodical calibration. The proposed system does not require periodical calibration, as is necessary for stabilometric force platforms, and it is easy to use. In future, the proposed system with little integration can be used, besides being an emulator of a stabilometric platform, also to recognize and track, in real time, head, legs, arms and trunk, that is to collect information actually obtained by sophisticated optoelectronic systems.     

Coding warnings without interfering with dismounted soldiers' missions

Objectives

Warnings are an effective way to communicate hazard, yet they can also increase task demand when presented to operators involved in real-world tasks. Furthermore, in military-related tasks warnings are often given in codes to avoid counter-intelligence, which may foster additional working memory load.

Background

Adherence to warnings in the military domain is crucial to promote safety and reduce accidents and injuries. The empirical question arises as to how aspects of coding the warning may interfere with the primary task the individual is currently performing and vice versa.

Method

Six experimental conditions were designed to assess how warning-code storage format, response format, and increasing working memory demand (retention) affected both performance on the primary task and the rate of compliance to warnings, considered here as the secondary task.

Results

Results revealed that the combination of warning-code storage and response format affected compliance rate and the highest compliance occurred when warnings were presented as pictorials and responses were coded verbally. Contrary to the proposed hypotheses, warning storage format did not affect performance on the primary task, which was only affected by the level of working memory demand. Thus, the intra-modal warning storages did not interfere with the visual/spatial nature of the primary operational task. However, increase in working memory demand, by increasing the number of memorized warning codes, had an effect on both compliance rate and primary task performance.

Conclusions

Rather than warning code storage alone, it is the coupling of warning storage and response format that has the most significant effect on compliance.     

云环境下基于强化学习的多目标任务调度算法

针对云计算环境下的多目标任务调度问题,提出一种新的基于Q学习的多目标优化任务调度算法(Multi-objective Task Scheduling Algorithm based on Q-learning,QM TS).该算法的主要思想是:首先,在任务排序阶段利用Q-learning算法中的自学习过程得到更加合理的任务序列;然后,在虚拟机分配阶段使用线性加权法综合考虑任务最早完成时间和计算节点的计算成本,达到同时优化多目标问题的目的;最后,以产生更小的makespan和总成本为目标函数对任务进行调度,得到任务完成后的实验结果.实验结果表明,QMTS算法在使用Q-learning对任务进行排序后可以得到比HEFT算法更小的makespan;并且根据优化多目标调度策略在任务执行过程中减少了makespan和总成本,是一种有效的多目标优化任务调度算法.     

Multi-mode resource constrained project scheduling and contractor selection: Mathematical formulation and metaheuristic algorithms

Contractor selection is a matter of particular attraction for project managers whose aim is to complete projects considering time, cost and quality issues. Traditionally, project scheduling and contractor selection decisions are made separately and sequentially. However, it is usually necessary to satisfy some principles and obligations that impose hard constraints to the problem under consideration. Ignoring this important issue and making project scheduling and contractor selection decisions consecutively may be suboptimal to a holistic view that makes all interrelated decisions in an integrated manner. In this paper, an integrated bi-objective optimization model is proposed to deal with Multi-mode Resource Constrained Project Scheduling Problem (MRCPSP) and Contractor Selection (CS) problem, simultaneously. The objective of the proposed model is to minimize the total costs of the project, and minimize the makespan of the project, simultaneously. To solve the integrated MRCPSP-CS, two multi-objective meta-heuristic algorithms, Non-Dominated Sorting Genetic Algorithm (NSGA-II) and Multi-Objective Particle Swarm Optimization algorithm (MOPSO), are adopted, and 30 test problems of different sizes are solved. The parameter tuning is performed using the Taguchi method. Then, diversification metric (DM), mean ideal distance (MID), quality metric (QM) and number of Pareto solutions (NPS) are used to quantify the performance of meta-heuristic algorithms. Analytic Hierarchy Process (AHP), as a prominent multi-attribute decision-making method, is used to determine the relative importance of performance metrics. Computational results show the superior performance of MOPSO compared to NSGA-II for small-, medium- and large-sized test problems. Moreover, a sensitivity analysis shows that by increasing the number of available contractors, not only the makespan of the project is shortened, but also, the value of NPS in the Pareto front increases, which means that the decision maker(s) can make a wider variety of decisions in a more flexible manner.     

Online scheduling of moldable parallel tasks

In this paper, we study an online scheduling problem with moldable parallel tasks on m processors. Each moldable task can be processed simultaneously on any number of processors of a parallel computer, and the processing time of a moldable task depends on the number of processors allotted to it. Tasks arrive one by one. Upon arrival of each task, the scheduler has to determine both the number of processors and the starting time for the task. Moreover, these decisions cannot be changed in the future. The objective is to attain a schedule such that the longest completion time over all tasks, i.e., the makespan, is minimized. First, we provide a general framework to show that any \(\rho \)-bounded algorithm for scheduling of rigid parallel tasks (the number of processors for a task is fixed a prior) can be extended to yield an algorithm for scheduling of moldable tasks with a competitive ratio of \(4\rho \) if the ratio \(\rho \) is known beforehand. As a consequence, we achieve the first constant competitive ratio, 26.65, for the moldable parallel tasks scheduling problem. Next, we provide an improved algorithm with a competitive ratio of at most 16.74.     

Assessing the ergonomic exposures for drywall workers

Objective

The study was conducted to assess the ergonomic exposures to risk factors that may lead to the reported musculoskeletal injuries (especially back, neck and wrist injuries) of drywall workers.

Methods

A hierarchical taxonomy for construction of drywall panel hanging (drywall panel fitting and installation) was developed with activities defined within the interior wall systems tasks (drywall panel, studs and insulation). Exposures were characterized for the drywall panel work with the PATH (Posture, Activity, Tools, and Handling) work-sampling observation method. Data on working postures were collected for three main body parts: legs, arms and trunk. Activities performed for each task, tools used, and manually handled loads were also recorded for each observation.

Results

The study identified several ergonomic exposures in interior systems construction. Several risk factors were especially prevalent in the drywall panel installation task: awkward body postures such as overhead arm posture, trunk flexion, and handling of heavy drywall panels. Some tasks were observed to have combinations of these musculoskeletal risk factors, such as drywall panel installation, where the workers lifted heavy drywall panels in awkward body postures. In addition, a safety hazard frequently resulted when a worker's foot was poorly supported on a ladder while lifting heavy drywall panels to hang them on the ceiling or upper wall.

Conclusion

The drywall panel installation task poses a severe threat to the safety and musculoskeletal health of the drywall workers. Much of this could be eliminated by reducing the burden of handling heavy and bulky drywall panels.

Relevance to industry

The construction industry is well-documented to have high rates of injury and musculoskeletal disorders. Design of appropriate interventions requires specific knowledge of which tasks and activities involve the highest levels of exposure to relevant factors. Assessment of such factors in drywall panel hanging has provided data that will be useful to evaluate the ergonomics efficacy of future changes in task processes or tools. Feasible solutions appear to exist; effectiveness trials and worker input are needed in order to evaluate whether they could eliminate the observed exposures.     

Prevalence of carpal tunnel syndrome among employees at a poultry processing plant

Objective

To determine prevalence of carpal tunnel syndrome (CTS) among poultry processing employees while taking into account non-occupational factors and assess any association between CTS prevalence and exposure groups.

Methods

Performed a cross-sectional survey to assess CTS (n = 318). A CTS case was defined as an employee with self-reported CTS symptoms, an abnormal hand symptom diagram, and an abnormal nerve conduction study (NCS). Log-binomial regression was used to estimate prevalence ratios.

Results

Three hundred and one participants had sufficient symptom information or NCS data to be classified. 126 (42%) of 301 participants had evidence of CTS. In the adjusted analysis, the highest exposure group had CTS prevalence that was significantly higher than that for the lower exposure group [PR: 1.61; 95% CI = (1.20, 2.17)].

Conclusions

Increasing levels of hand activity and force were associated with increased CTS prevalence among participants. Recommendations were provided to reduce exposure to these risk factors.     

Exploring physical exposures and identifying high-risk work tasks within the floor layer trade

Introduction

Floor layers have high rates of musculoskeletal disorders yet few studies have examined their work exposures. This study used observational methods to describe physical exposures within floor laying tasks.

Methods

We analyzed 45 videos from 32 floor layers using Multimedia-Video Task Analysis software to determine the time in task, forces, postures, and repetitive hand movements for installation of four common flooring materials. We used the WISHA checklists to define exposure thresholds.

Results

Most workers (91%) met the caution threshold for one or more exposures. Workers showed high exposures in multiple body parts with variability in exposures across tasks and for different materials. Prolonged exposures were seen for kneeling, poor neck and low back postures, and intermittent but frequent hand grip forces.

Conclusions

Floor layers experience prolonged awkward postures and high force physical exposures in multiple body parts, which probably contribute to their high rates of musculoskeletal disorders.     

Fault tolerance aware scheduling technique for cloud computing environment using dynamic clustering algorithm

In cloud computing, resources are dynamically provisioned and delivered to users in a transparent manner automatically on-demand. Task execution failure is no longer accidental but a common characteristic of cloud computing environment. In recent times, a number of intelligent scheduling techniques have been used to address task scheduling issues in cloud without much attention to fault tolerance. In this research article, we proposed a dynamic clustering league championship algorithm (DCLCA) scheduling technique for fault tolerance awareness to address cloud task execution which would reflect on the current available resources and reduce the untimely failure of autonomous tasks. Experimental results show that our proposed technique produces remarkable fault reduction in task failure as measured in terms of failure rate. It also shows that the DCLCA outperformed the MTCT, MAXMIN, ant colony optimization and genetic algorithm-based NSGA-II by producing lower makespan with improvement of 57.8, 53.6, 24.3 and 13.4 % in the first scenario and 60.0, 38.9, 31.5 and 31.2 % in the second scenario, respectively. Considering the experimental results, DCLCA provides better quality fault tolerance aware scheduling that will help to improve the overall performance of the cloud environment.

     

Variation in work tasks in relation to pinch grip strength among middle-aged female dentists

Objectives

We aimed to investigate the relationship of task variation during dental work history with pinch grip strength among dentists.

Methods

We measured pinch grip strength among 295 female Finnish dentists aged 45–63 years. Variation in dental work tasks during work history was empirically defined by cluster analysis. Three clusters of task variation emerged: low (most work time in restoration treatment/endodontics), moderate (about 50% in the former and 50% in prosthodontics/periodontics/surgery), and high (variable tasks including administrative duties). Hand radiographs were examined for the presence of OA in the wrist and each joint of the 1–3rd fingers. Information on hand-loading leisure-time activities, and joint pain was obtained by questionnaire. Glove size was used as a proxy for hand size. BMI (kg/m2) was based on measured weight and self-reported height.

Results

Dentists with low variation of work task history had an increased risk of low pinch grip strength in the right hand (OR 2.3, 95% CI 1.2–4.3), but not in the left (1.13, 0.62–2.08), compared to dentists with high task variation, independent of age, hand size, hand-loading leisure-time activities, BMI and symptomatic hand OA.

Conclusion

The dentists with the most hand-loading tasks were at an increased risk of low pinch grip strength, independent of e.g. symptomatic hand OA. It is advisable among dentists to perform as diverse work tasks as possible to reduce the risk of decreased pinch grip strength.