The effects of three re-designed models of sewing scissors on hand performance measures, discomfort and usability were investigated, and the results were compared with those of conventional scissors. Adjustments were made to the scissors handle with emphasis on more neutral wrist postures (bent handle - model A), correction of the thumb's position and movements (model B) and reducing hand/finger discomfort (model C) while working with the tool. The results showed some improvements in hand performance, muscular effort, usability and discomfort with model B compared to the conventional model. Better hand performance and usability and lower discomfort were recorded with model C compared to the conventional model. The results suggest that the correction of the thumb's position and movement (model B) or even reduced hand/finger discomfort (model C) are perhaps more important considerations in scissors design than improved wrist posture (model A) for improving users' performance and usability of the tool. 相似文献
Little research to date has focused on understanding employee motivation to share and hide knowledge. Using self‐determination theory, we tested the premise that knowledge sharing and hiding might be differentially motivated and that work design characteristics might influence the motivation to share knowledge with colleagues. In a panel survey of Australian knowledge workers and in a Chinese knowledge‐intensive organization, we asked knowledge workers, using time‐lagged designs, about perceptions of work design, motivation to share knowledge, and self‐reported knowledge sharing and hiding behaviors. Results, largely replicated across both samples, indicated that cognitive job demands and job autonomy were positively related to future reports of knowledge‐sharing frequency and usefulness via autonomous motivation to share knowledge. Unexpectedly, task interdependence was positively related to the three forms of knowledge hiding (evasive and rationalized hiding, and playing dumb) via external regulation to share knowledge. Implications for the design of jobs that motivate knowledge sharing and demotivate knowledge hiding are discussed. 相似文献
This study aims to develop an integrated model - NFPA-68-BRANN model, which can be used to calculate the vent areas of cubic enclosures with obstacles. Seven experiments regarding vented explosion inside the obstructed enclosure are reviewed and applied to check the accuracy of two existing standards, i.e. the NFPA-68 2018 and the BS EN 14994:2007. Accordingly, the parameters to describe the flame development in the NFPA-68 2018 are amended by adopting the Bauwens model. Bayesian Regularization Artificial Neuron Network (BRANN) model presenting the non-linear relationship between the turbulent flame enhancement factor X and its affecting factors is subsequently developed. Eventually, the NFPA-68-BRANN model is generated by incorporating the BRANN model into the modified NFAP-68 2018. The accuracy of the NFPA-68-BRANN model is validated by using a series of the New Baker Test data. 相似文献
Objectives: The purpose of this study is to define a computationally efficient virtual test system (VTS) to assess the aggressivity of vehicle front-end designs to pedestrians considering the distribution of pedestrian impact configurations for future vehicle front-end optimization. The VTS should represent real-world impact configurations in terms of the distribution of vehicle impact speeds, pedestrian walking speeds, pedestrian gait, and pedestrian height. The distribution of injuries as a function of body region, vehicle impact speed, and pedestrian size produced using this VTS should match the distribution of injuries observed in the accident data. The VTS should have the predictive ability to distinguish the aggressivity of different vehicle front-end designs to pedestrians.
Methods: The proposed VTS includes 2 parts: a simulation test sample (STS) and an injury weighting system (IWS). The STS was defined based on MADYMO multibody vehicle to pedestrian impact simulations accounting for the range of vehicle impact speeds, pedestrian heights, pedestrian gait, and walking speed to represent real world impact configurations using the Pedestrian Crash Data Study (PCDS) and anthropometric data. In total 1,300 impact configurations were accounted for in the STS. Three vehicle shapes were then tested using the STS. The IWS was developed to weight the predicted injuries in the STS using the estimated proportion of each impact configuration in the PCDS accident data. A weighted injury number (WIN) was defined as the resulting output of the VTS. The WIN is the weighted number of average Abbreviated Injury Scale (AIS) 2+ injuries recorded per impact simulation in the STS. Then the predictive capability of the VTS was evaluated by comparing the distributions of AIS 2+ injuries to different pedestrian body regions and heights, as well as vehicle types and impact speeds, with that from the PCDS database. Further, a parametric analysis was performed with the VTS to assess the sensitivity of the injury predictions to changes in vehicle shape (type) and stiffness to establish the potential for using the VTS for future vehicle front-end optimization.
Results: An STS of 1,300 multibody simulations and an IWS based on the distribution of impact speed, pedestrian height, gait stance, and walking speed is broadly capable of predicting the distribution of pedestrian injuries observed in the PCDS database when the same vehicle type distribution as the accident data is employed. The sensitivity study shows significant variations in the WIN when either vehicle type or stiffness is altered.
Conclusions: Injury predictions derived from the VTS give a good representation of the distribution of injuries observed in the PCDS and distinguishing ability on the aggressivity of vehicle front-end designs to pedestrians. The VTS can be considered as an effective approach for assessing pedestrian safety performance of vehicle front-end designs at the generalized level. However, the absolute injury number is substantially underpredicted by the VTS, and this needs further development. 相似文献
Incidents involving uncontrolled chemical reactions continue to result in fatality, injury and economic loss. These incidents are often the result of inadequate pressure relief system designs due to a limited knowledge of the chemical reactivity hazard. A safe process design requires knowledge of the chemical reactivity of desired as well as undesired chemical reactions due to upset conditions. Simplified, cost effective methods to relief system sizing are presented by The Design Institute of Emergency Relief Systems (DIERS). They require multiple experiments, and sizing is only valid for the system composition and thermal inertia represented by the small scale experiments. Results are often conservative, especially for gassy systems. Detailed, dynamic computer simulation is highly accurate and can be used for iterative design and multiple scenario evaluation.In this study, an accelerating rate calorimeter (ARC®) and a low thermal inertia calorimeter (automatic pressure tracking adiabatic calorimeter – APTAC™) were used to collect chemical reactivity data for the dicumyl peroxide and toluene system. Results of the pressure relief system sizing using the dynamic simulation method are presented and compared with DIERS simplified methods. 相似文献