The Cost of Consecutivity in the (5, 7) Cyclic Staffing Problem

The (5, 7) cyclic staffing problem is the problem of finding the least number of workers assigned to a 7 day cyclic schedule, so that sufficient workers are present during day i to meet requirement b_i and each person works a shift of 5 consecutive days and is idle for the other 2. In this paper we derive an expression for the minimal workforce size in the problem in terms of the b_i's. This result is interesting because it shows the extra number of workers needed by insisting that each person's idle days are consecutive.     

Integrated workforce capacity and inventory management under labour supply uncertainty

In a manufacturing environment with volatile demand, inventory management can be coupled with dynamic capacity adjustments for handling the fluctuations more effectively. In this study, we consider the problem of integrated capacity and inventory management under non-stationary stochastic demand and capacity uncertainty. The capacity planning problem is investigated from the workforce planning perspective where the capacity can be temporarily increased by utilising contingent workers from an external labour supply agency. The contingent capacity received from the agency is subject to an uncertainty, but the supply of a certain number of workers can be guaranteed through contracts. There may also be uncertainty in the availability of the permanent and contracted workers due to factors such as absenteeism and fatigue. We formulate a dynamic programming model to make the optimal capacity decisions at a tactical level (permanent workforce size and contracted number of workers) as well as the operational level (number of workers to be requested from the external labour supply agency in each period), integrated with the optimal operational decision of how much to produce in each period. We analyse the characteristics of the optimal policies and we conduct an extensive numerical analysis that helps us provide several managerial insights.     

A formative approach to the strategies analysis phase of cognitive work analysis

Strategies Analysis, the third phase of Cognitive Work Analysis, helps investigators consider the range of ways in which workers can perform control tasks. Most existing approaches to Strategies Analysis identify a limited number of domain-specific strategies. We present a two-phase formative Strategies Analysis method intended to expose the range of strategies possible within a work system and the likelihood that different types of strategies will be selected in different contexts. The first phase, the preparatory phase, identifies generalised constraints that affect the range and selection of strategies, and the categories of strategies that may be applied to any domain. In the second phase, the application phase, investigators use the outputs of the preparatory phase to explore the impact that different work situations, tasks and workers have on the categories of strategies most likely to be adopted.     

A method for assembly line balancing with more than one worker in each station

The typical assembly line is serial with no paralleling of work elements and work stations allowed. The series assumption restricts the least cycle time to be the maximum work element time, thus limiting the production rate.

An alternative way to increase the production rate (hence lowering the cycle time) is by assigning multiple workers to one work station. In this paper we propose the parallel assignment method (PAM) for achieving a higher production rate.

In the first phase of PAM the work elements are assigned to work stations under the multi-stage upper time limits. But as two or more workers are assigned to one station, the operation time of each worker is longer in proportion to the number of workers at the station.

Therefore, in the second phase of PAM work elements are assigned to the workers in each station so that each of the workers may perform shorter work elements where the work element is a minimum rational indivisible work item.

Practical problems which cannot he solved by serial line balancing methods are provided and.solved to explain the effectiveness of PAM.     

Externalizing,Internalizing and Fostering Commitment: The Case of Born-Global Firms in Emerging Economies

This paper examines the HR practices of mature born-global firms from 29 emerging economies. Through an examination of large scale survey data the paper questions the extent to which firm size impacts the employment of temporary workers, the employment of skilled workers and the extent of employee training. Findings suggest that as firm size increases the use of temporary workers decreases, the number of skilled workers increases and the number of employees receiving training also increases. The paper highlights how born-global firms are able to shift away from externalized, market-based approaches towards more internalized, commitment-based approaches in order to survive, adapt and grow.     

A Differentially Private Data Aggregation Method Based on Worker Partition and Location Obfuscation for Mobile Crowdsensing

With the popularity of sensor-rich mobile devices, mobile crowdsensing (MCS) has emerged as an effective method for data collection and processing. However, MCS platform usually need workers’ precise locations for optimal task execution and collect sensing data from workers, which raises severe concerns of privacy leakage. Trying to preserve workers’ location and sensing data from the untrusted MCS platform, a differentially private data aggregation method based on worker partition and location obfuscation (DP-DAWL method) is proposed in the paper. DP-DAWL method firstly use an improved K-means algorithm to divide workers into groups and assign different privacy budget to the group according to group size (the number of workers). Then each worker’s location is obfuscated and his/her sensing data is perturbed by adding Laplace noise before uploading to the platform. In the stage of data aggregation, DP-DAWL method adopts an improved Kalman filter algorithm to filter out the added noise (including both added noise of sensing data and the system noise in the sensing process). Through using optimal estimation of noisy aggregated sensing data, the platform can finally gain better utility of aggregated data while preserving workers’ privacy. Extensive experiments on the synthetic datasets demonstrate the effectiveness of the proposed method.     

Development and application of a worker assignment model to evaluate a lean manufacturing cell

In lean manufacturing environments, cross-training is often used to achieve multi-skilling in order to increase flexibility in meeting fluctuating demand, to create a shared sense of responsibility, and to balance workload between cross-trained workers. This paper presents a model that assigns workers to tasks within a lean manufacturing cell while minimizing net present cost. In determining how to assign workers to tasks, the model addresses production requirements to meet customer demand, skill depth requirements for tasks, varying quality levels based on skill depth, and job rotation to retain skills for a cross-trained workforce. The model generates an assignment of workers to tasks and determines the training necessary for workers to meet skill requirements for tasks and customer demand. While the model can be used in a number of ways, in this paper it is used to generate a worker assignment schedule for cross-trained workers in a dedicated lean manufacturing cell in an electronics assembly plant and to evaluate the effect of increased cross-training on the cell. The resulting worker assignment schedules for the current state and several alternative scenarios for the cell are evaluated using cost results from the optimization model and from a simulation model to assess additional performance metrics. These results demonstrate the usefulness of the worker assignment model and indicate that moderate increases from current cross-training levels are not beneficial for this cell.     

基于人因工程的施工人员安全教育效果优化研究

以人为本地开展施工企业的安全教育工作,针对施工企业施工人员安全教育的现状,从人因工程的角度探究改善安全教育效果不佳的措施。统计工作人员在接受安全教育后15 d内产生不安全行为的类别及次数,并对记录的实验数据进行分析处理,确定保护他人安全意识及规范习惯性不安全行为的安全教育效果不佳。利用得出的结论对工人进行反馈调查,结果表明问题产生的原因主要是人际关系和有针对性的安全操作技术培训强度不够。结合人因工程理论的作业活动分解理论,从安全教育培训方式、工人接受意愿和安全教育效果的保持性等方面提出了相应的改善措施,为施工企业提升施工人员安全教育培训效果提供了新途径。     

Simple models of fatality trends using employment and population data

Simple models of traffic fatalities were developed using only the readily available factors of population size (from the Bureau of the Census estimates and projections) and the size of the potential labor force and the number of unemployed workers (from the Bureau of Labor Statistics estimates based upon household surveys). The fatality trends from 1960 through 1982 appear consistent with changes in the numbers of unemployed workers, employed workers, and people not available for the labor force. The long-term (23-yr) model using employment factors produces an estimate of 45,158 fatalities in 1982 versus the current estimate of 44,000 fatalities which was derived from preliminary State reports. Short-term (1975–1982) annual fatality trends reflect recent sociological changes. A model based upon the number of unemployed workers and the number of employed workers produces an estimate of 44,709 fatalities in 1982, as compared to the State-reported estimate of 44,000 fatalities. A similar model of teenage (15–19 yr old) traffic fatalities produces an estimate of 6679 fatalities in 1982, as compared to the current estimate of 6700. The quantification of the relationship between economic factors and the number of traffic fatalities may be useful in understanding the effects of safety programs and other changes to the driving environment. However, the reader is cautioned on three important points about any modeling analysis. First, a model produces estimates of the effects of variables included in the analysis, but does not imply estimates of the effects of variables left out of the analysis. In particular, these models do not imply that other factors (such as safety programs and improvements) are unrelated to fatality decreases. Second, a model describes the observed coinciding of changes among variables, but does not of itself imply cause and effect. Inferences of causal relationships (between, for example, the economy and fatalities via changes in travel patterns) are made by people—usually subject matter specialists—to explain the model. Third, predictions from the model are the responsibility of the analyst making them. Predictions are especially tenuous when based upon data beyond the range of the historical experience used to create the model.     

A Note on the Evaluation of the Agglomerative Hierarchical Clustering Methods

Behaviormetrika - Recently, a large number of techniques of numerical taxonomy or cluster analysis are proposed and studied by many workers, and the needs for these techniques arise in many fields...     

A two-phase variable neighbourhood search algorithm for assembly line worker assignment and balancing problem type-II: an industrial case study

The assembly line worker assignment and balancing problem type-II (ALWABP-2) occurs when workers and tasks (where task times depend on workers’ skills) are to be simultaneously assigned to a fixed number of workstations with the goal of minimising the cycle time. In this study, a two-phase variable neighbourhood search (VNS) algorithm is proposed to solve the ALWABP-2 due to the NP-hard nature of this problem. In the first phase of the algorithm, a VNS approach is applied to assign tasks to workstations with the aim of minimising the cycle time while in the second phase, a variable neighbourhood descent method is applied to assign workers to workstations. The performance of the proposed algorithm is tested on well-known benchmark instances. In addition, the proposed algorithm has been used to solve a real case study from a consumer electronics company that manufactures LCD TVs. The results show that the algorithm is superior to the methods reported in the literature in terms of its higher efficiency and robustness. Furthermore, the algorithm is easy to implement and significantly improves the performance of the final assembly line for the investigated LCD TV real case study.     

Is radiation protection for the unborn child guaranteed by radiation protection for female workers?

ICRP Publication 88 recommends doses to the embryo and fetus from intakes of radionuclides by the mother for various intake scenarios. Mainly by answering the question 'Is radiation protection for the unborn child guaranteed by radiation protection for female workers?' it has been assessed if the intake scenarios given in ICRP Publication 88 are adequate for radiation protection purposes. This is generally the case, but the consideration of an additional chronic intake scenario for early pregnancy would be helpful. It is demonstrated that following chronic intake by inhalation, for most radionuclides radiation protection for (female) workers is also adequate for protection of the unborn child, considered as a member of the public. However, there are a number of radionuclides for which possible intakes in routine operations should be more restricted (up to 1% of the annual limits on intake for workers in the case of nickel isotopes) to ensure radiation protection for the unborn child.     

Limits of DPUI application associated with the number of particles within actinide aerosols

Dose per unit intake (DPUI) of radionuclides is obtained using International Commission on Radiological Protection (ICRP) models. After inhalation exposure, the first model calculates the fraction of activity deposited within the different regions of the respiratory tract, assuming that the aerosol contains an infinite number of particles. Using default parameters for workers, an exposure to one annual limit of intake (ALI) corresponds to an aerosol of 239PuO2 containing approximately 1 x 10(6) particles. To reach such an exposure, very low particle number might be involved especially for compounds having a high specific activity. This study provides examples of exposures to actinide aerosols for which the number of particles is too low for a standard application of the ICRP model. These examples, which involve physical studies of aerosols collected at the workplace and interpretation of bioassay data, show that the number of particles of the aerosol can be the main limit for the application of DPUI after inhalation exposure.     

A boundary integral method for gravitational fluid flow over a semi-circular obstruction using an interpolative technique

A boundary integral technique is developed to study the behaviour of a steady, two-dimensional free surface flow of an incompressible, irrotational and inviscid fluid over a submerged semi-circular obstruction in the presence of gravity. The solution technique is different to that employed by many of the previous research workers since it involves the application of the Riemann–Hilbert problem in the derivation of the nonlinear boundary integral–differential equations. The boundary integral equations are solved using piecewise constant and linear interpolative techniques for the fluid velocity on both the solid boundary and the free surface for various values of the upstream Froude number and the radius of the semi-circular obstruction. An investigation into the numerical accuracy of the interpolation techniques is employed. It is found that it is difficult to obtain a solution when the non-dimensional radius of the semi-circular obstruction is large and hence a hybrid technique is developed which is capable of computing the free surface profiles for all values of the radius of the semi-circular obstruction. Also by considering the local Froude number we have found that the fluid flow can become subcritical, i.e. the local Froude number is less than unity, in the vicinity just above the obstacle but no waves are found to be present on the free surface.     

A bioassay experience and lessons learned on the internal contamination of (131)I during a maintenance period in a Korean nuclear power plant

During a maintenance period at a Korean nuclear power plant, internal exposure of radiation workers occurred by the inhalation of (131)I that was released into the reactor building from a primary system opening due to defective fuels. The internal activity in radiation workers contaminated by (131)I was immediately measured using a whole body counter (WBC). A whole body counting was performed again a few days later, considering the factors of equilibrium in the body. The intake and the committed effective dose were estimated based on the WBC results. The intake was also calculated by hand, based on both the entrance records to the reactor building, and the counted results of the air concentration for (131)I were compared with the whole body counting results.     

Analysis of radiation workers' dose records in the Korean National Dose Registry

Data are presented on the externally received personal dose equivalent for radiation workers who used the Korea Radioisotope Association's personal monitoring and dose record keeping service since 1984, and provide initial statistics on Korean workers who have been exposed to ionising radiation in different occupations. The total number of workers registered during the period of 1984 to 1999 was 64,518. The number increased steadily and the accumulated dose also increased. The proportion of radiation workers by occupation was 38.4% for nuclear power plants, 20.3% for industrial organisations and 12.4% for non-destructive industry. The annual collective dose of radiation workers was 31.72 man.Sv in 1999. The mean annual dose by sex was 1.49 mSv for males and 0.56 mSv for females and the mean annual dose for a worker was 1.41 mSv with the highest mean dose being received by non-destructive industry (3.53 mSv). Very few workers (0.8%) received more than 20 mSv (2 rem) and only one more than 50 mSv, the legal limit for an annual dose increase. There has been a steady decline in the mean dose since 1984, showing a significant decrease in dose with time (p<0.001). The data showed that radiation protection in Korea was improving, though annual doses were still higher than other countries.     

A Successful Application of Job Enlargement/Enrichment at Toyota

When designing a production system to meet the company desires, the desire of the workers should also be considered. A survey at the Toyota Tsutsumi plant indicated that workers wanted enlarged/enriched jobs. The jobs were enlarged/enriched through a system of cross-training and job rotation. Productivity and quality were improved.     

A review of experimental methods for solid solubility determination in cryogenic systems

Over the past years, there have been a number of serious explosions in air industry, which have resulted in workers injuries and fatalities. At the same time, there has been an increase in the use of air separation products for industrial activities.The quality of air entering an air separation plant is of crucial importance for its safe and reliable operation and the interest in the solubility data of solids in cryogenic liquid solvents is closely connected to the problem of impurities accumulation in the process plant and storage tanks. Such accumulations, especially in liquid oxygen, may cause fouling and blockage in heat exchangers and pipelines and they may eventually cause serious explosions. For this reason the air contaminants composition in liquid oxygen must be determined with great precision.This paper aims at reviewing experimental methods for determining the solubility of solid compounds that may be present in the cryogenic liquefaction processing of air distillation. A review of the literature data on solubility of solids in liquid oxygen and nitrogen is included as well.Emphasis is given to the difficulties in setting-up measuring apparatuses working at extreme conditions, i.e. low compositions and low temperatures.     

Critical factors and paths influencing construction workers’ safety risk tolerances

While workers’ safety risk tolerances have been regarded as a main reason for their unsafe behaviors, little is known about why different people have different risk tolerances even when confronting the same situation. The aim of this research is to identify the critical factors and paths that influence workers’ safety risk tolerance and to explore how they contribute to accident causal model from a system thinking perceptive. A number of methods were carried out to analyze the data collected through interviews and questionnaire surveys. In the first and second steps of the research, factor identification, factor ranking and factor analysis were carried out, and the results show that workers’ safety risk tolerance can be influenced by four groups of factors, namely: (1) personal subjective perception; (2) work knowledge and experiences; (3) work characteristics; and (4) safety management. In the third step of the research, hypothetical influencing path model was developed and tested by using structural equation modeling (SEM). It is found that the effects of external factors (safety management and work characteristics) on risk tolerance are larger than that of internal factors (personal subjective perception and work knowledge & experiences). Specifically, safety management contributes the most to workers’ safety risk tolerance through its direct effect and indirect effect; while personal subjective perception comes the second and can act as an intermedia for work characteristics. This research provides an in-depth insight of workers’ unsafe behaviors by depicting the contributing factors as shown in the accident causal model developed in this research.