Keeping up-to-date with information technology: Testing a model of technological knowledge renewal effectiveness for IT professionals

In a rapidly changing IT environment, IT professionals need to keep abreast of technological knowledge. We examined how well this is achieved by developing a motivational model of “technological knowledge renewal effectiveness.” We hypothesized that (1) renewal effectiveness was influenced by the IT professional's career orientation, perceived IT dynamism, tolerance of ambiguity, delegation; and (2) that this positively affected both intrinsic and extrinsic job satisfaction. Survey data from 126 IT professionals was used to test the hypotheses. The results generally supported the research model. We discussed the implications of these results in both research and practice.     

Application of the Strain Index in multiple task jobs

Six different methods to calculate the Strain Index (SI) scores for jobs with multiple forces/tasks were developed. Exposure data of 733 subjects from 12 different worksites were used to calculate these SI scores. Results show that using different SI computation methods could result in different SI scores, hence different risk level classifications. However, some simpler methods generated SI scores were comparable to the more complicated composite SI method. Despite differences in the scores between the six different SI computation methods, Spearman rank-order correlation coefficients of 0.61-0.97 were found between the methods. With some confidence, ergonomic practitioners may use simpler methods, depending on their specificity requirement in job evaluations and available resources. Some SI computation methods may tend to over-estimate job risk levels, while others may tend to under-estimate job risk levels, due to different ways used in obtaining the various SI parameters and computations.     

面向DTN无线传感网移动节点的动态资源调度模型的研究

资源调度是无线传感网络中移动节点的核心和富有挑战性的问题。如何提高移动节点资源使用率并取得最大利润是服务商的最终目标。通过非强占优先权排队G/G/1模型,满足不同等级数据QoS,利用线性分段函数使系统成本最小。进而基于成本函数和收益函数模型,求出不同级别信号动态分配比例,从而得出用户与服务商都满意的结果。结果表明,动态资源调度系统,不仅能够保证不同级别数据的QoS要求,也可使服务提供商的利润最大化。     

超立方体网络中任务调度的一个新近似算法

本文研究超立方体中的多处理器任务调度问题,我们研究LDLPT算法并指出为什么这种算法对一些实例具有最差的逼近度,然后提出一种类似装箱算法的新算法-BPA算法,证明该算法和LDLPT算法在相互最差逼近度中具有互补性质,最后,组合这两种算法的基本方法提出了一种求解问题的新算法-CBPA算法,并证明新算法具有比LDLPT算法更好的逼近度。     

A national cross-sectional study in the Danish wood and furniture industry on working postures and manual materials handling

Musculoskeletal disorders constitute a major problem in the wood and furniture industry and identification of risk factors is needed urgently. Therefore, exposures to different work tasks and variation in the job were recorded based on an observation survey in combination with an interview among 281 employees working in wood working and painting departments. A questionnaire survey confirmed high frequencies of symptoms from the musculoskeletal system: The one-year prevalence of symptoms from the low back was 42% and symptoms from the neck/shoulder was 40%. The exposure was evaluated based on: (1) classification of work tasks, (2) work cycle time, (3) manual materials handling, (4) working postures, and (5) variation in die job. Among the employees 47% performed feeding or clearing of machines, 35% performed wood working or painting materials, and 18% performed various other operations. Among the employees 20% had no variation in their job while 44% had little variation. Manual materials handling of 375 different burdens was observed, which most often occurred during feeding or clearing of machines. The weight of burdens lifted was 0·5-87·0 kg, where 2% had a weight of more than 50 kg. Among the lifting conditions 30% were evaluated as implying a risk of injury. An additional risk factor was the high total tonnage lifted per day, which was estimated to range from 132 kg to 58 800 kg. Working postures implied a risk of injury due to prolonged forward and lateral flexions of the neck, which was seen most frequently during wood working or painting materials. These data substantiate the finding that work tasks mainly during feeding or clearing of machines imply a risk of injury to the low back and a risk of injury to the neck and shoulder area mainly during wood working or painting materials. Optimal strategies for job redesign may be worked out by using these data in order to prevent occupational musculoskeletal disorders.     

Characteristics of job rotation in the Midwest US manufacturing sector

Job rotation has been advocated as a suitable intervention to control work-related musculoskeletal disorders. However, little is known regarding the prevalence of job rotation, methods used to identify jobs for rotation or the benefits or limitations of job rotation. A web-based questionnaire was developed to survey job rotation practices from Midwest US manufacturing companies. Results indicated that 42.7% of the companies contacted used job rotation, where the median time for which they had used job rotation was 5 years. Job rotation was used mainly to reduce exposure to risk factors for work-related injuries and to reduce work related injuries, whereas supervisor decisions and ergonomic analyses were used to select jobs for the rotation scheme. Major limitations to successful implementation of job rotation included rotation of individuals with medical restrictions, decreased product quality and lack of jobs to rotate to. These findings suggest that further study is needed to determine if exposure to risk factors is reduced through current efforts.     

一个基于多Agent的PCB装配调度系统

PCB装配调度是一个job shop调度问题。本文针对这一问题设计了一个基于多agent调度系统模型，系统的最大特点是将任务和优先权机制与基于合同网协议和KQML消息的竞标机制两者相结合。     

具有最大作业延迟的生产调度优化算法及仿真

成组作业优化调度问题中的作业根据其加工特点要求可分成若干作业类。同一类的作业连续加工，其后的作业不需要机器设置花费，而不同类的作业连续加工，其后的作业需要机器设置花费。当优化目标是最大作业延迟时，单机成组作业优化调度是HP—hard。本文在利用优化性质的基础上，提出了一种适于大规模优化调度问题的多项式时间算法。仿真实验表明该算法具有良好的性能。     

An agent for selecting optimal order set in EC marketplace

For most small manufacturing companies, the selection and completion of orders placed by buyers are closely linked to the load status of their production lines. The decision to accept an order, or the selection of optimal order set, critically depends on the production schedule when orders exceed production capacity. However, production scheduling is mainly performed by human experts, and small companies lack resources to implement such a task. As a result, most small manufacturers suffer from the difficulty to meet due dates or to make proper decision in accepting new orders. To address this problem, this paper develops an automatic agent that selects an optimal set of orders using commonly available Internet technology. The main engine of the selection agent is based on a typical job shop scheduling model, formulating and implementing it as an Integer Program (IP) model. We also translate IP into Genetic Algorithm (GA) to address its NP-hard problem. We conclude with a suggestion for an agent architecture that tackles Web-based order selection problems.     

基于生产计划排单的遗传算法的优化与应用

ERP是当今国际上先进的企业管理模式,其核心是计划体系,包括主生产计划、采购计划、车间作业计划等。车间作业计划的管理目标是按物料需求计划的要求,按时、按质、按量和低成本地完成加工制造任务。该文探讨了遗传算法在车间作业计划安排中的应用,主要是针对Flow Shop的调度问题,给出了包括建模、编码、选择、交叉、变异和适应性函数等的具体算法,并在最后给出了自适应算法、混合遗传算法等优化算法。经仿真算例分析,该算法取得较理想的效果。