Search results

Furniture plays a significant role in daily life. Advanced computational and manufacturing technologies provide new opportunities to create novel, high-performance and customized furniture. This paper aims to enhance furniture design and production by developing a new workflow in which computer graphics, topology optimization and advanced manufacturing are integrated to achieve innovative outcomes.

Workflow development is conducted by exploring state-of-the-art computational and manufacturing technologies to improve furniture design and production. Structural design and fabrication using the workflow are implemented.

An efficient transdisciplinary workflow is developed, in which computer graphics, topology optimization and advanced manufacturing are combined. The workflow consists of the initial design, the optimization of the initial design, the postprocessing of the optimized results and the manufacturing and surface treatment of the physical prototypes. Novel chairs and tables, including flat pack designs, are produced using this workflow. The design and fabrication processes are simple, efficient and low-cost. Both additive manufacturing and subtractive manufacturing are used.

The research outcomes are directly applicable to the creation of novel furniture, as well as many other structures and devices.

A new workflow is developed by taking advantage of the latest topology optimization methods and advanced manufacturing techniques for furniture design and fabrication. Several pieces of innovative furniture are designed and fabricated as examples of the presented workflow.

High-strength martensitic steels having strong hydrogen embrittlement (HE) susceptibility and the metal carbide (MC) nanoprecipitates of microalloying elements such as Nb, V, Ti and Mo in the steel matrix can effectively improve the HE resistance of steels. This paper aims to review the effect of MC nanoprecipitates on the HE resistance of high-strength martensitic steels.

In this paper, the effects of MC nanoprecipitates on the HE resistance of high-strength martensitic steels are systematically described in terms of the types of MC nanoprecipitates, the influencing factors, along with numerical simulations.

The MC nanoprecipitates, which are fine and semicoherent with the matrix, effectively improve the HE resistance of steel through the hydrogen trapping effects and microstructure optimization, but its effect on the HE resistance of steel is controlled by its size, number and distribution state.

This paper summarizes the effects and mechanisms of MC nanoprecipitates on HE performance of high-strength martensitic steel and provides the theoretical basis for corrosion engineers to design high-strength martensitic steels with excellent HE resistance and improve production processes.

Under multiaxial random loading, the material stress–strain response is not periodic, which makes it difficult to determine the direction of the critical plane on the material. Meanwhile, existing methods of constant loading cannot be directly applied to multiaxial random loading; this problem can be solved when an equivalent stress transformation method is used.

First, the Liu-Mahadevan critical plane is introduced into multiaxial random fatigue, which is enabled to determine the material's critical plane position under random loading. Then, an equivalent stress transformation method is proposed which can convert random load to constant load. Meanwhile, the ratio of mean stress to yield strength is defined as the new mean stress influence factor, and a new non-proportional additional strengthening factor is proposed by considering the effect of phase differences.

The proposed model is validated using multiaxial random fatigue test data of TC4 titanium alloy specimens and the results of the proposed model are compared with that based on Miner's rule and BSW model, showing that the proposed method is more accurate.

In this work, a new multiaxial random fatigue life prediction model is proposed based on equivalent stress transformation method, which considers the mean stress effect and the additional strengthening effect. Results show that the predicted fatigue lives given by the proposed model are in well accordance with the tested data.

This study aims to assess the effects of commonly examined police stressors' on the members of a developing country's centralized police department: Turkish National Police (TNP).

This study is based on a data collected through a self‐administered survey among the members of the TNP during the summer of 2005 (n=812). Using multivariate level OLS regression models, predicting effects of commonly examined police stressors on the participants' stress levels are analyzed. Findings are evaluated in comparison to existing literature about police stress.

This study indicates that organizational issues are the most important causes of stress in policing. Besides, it was found that several police stressors, as found for local police departments, might not be having the same effects for larger, centralized police departments.

Modern policing can be a less stressful job if the police organizations take necessary steps towards applying modern management techniques at both macro and micro levels. Demographic differences, danger at work, or workload should not be counted as predictors of stress in policing without a through consideration of organizational matters.

This is the first study empirically and systematically assessing the issue of stress among the members of the TNP. In addition, it is one of the rare studies published in English regarding the issue of police stress in a developing country.

The purpose of this paper is to explore whether male and female police officers report different levels of occupational stress and burnout. Also, the research seeks to examine whether various factors that are purported to influence occupational stress and burnout have differential effects on male and female officers.

Using a sample of police officers working in a large metropolitan department in the Northeast, the paper begins by using t‐tests to make gender comparisons between the average levels of occupational stress and burnout between male and female officers. Next, separate multivariate analyses were run for male and female officers to determine how a set of independent variables measuring the work‐environment, coping mechanisms, and other demographic characteristics affected the measures of occupational stress and burnout.

The findings indicate that male and female officers did not report significantly different levels of occupational stress and burnout. Results of the separate multivariate analyses reveal that, although there are similar predictors of stress and burnout for male and female officers, differences did exist in the models, lending support to the assertion that the female officers may experience unique stressors in the police organization. The multivariate results also indicate that African‐American female officers report significantly higher levels of burnout than other officers.

The current research adds to the knowledge about how levels and predictors of work‐related stress and burnout compare between male and female police officers. The current study is limited by its focus on only one police department located in the Northeast. This may limit the generalizability of the results.

The results of the study have implications for programs and policies that seek to prevent stress and burnout among police officers. The results of the current study indicate that a one‐program‐fits‐all approach may not be the best way for departments to help officers to deal with stress and burnout, since male and female officers may not experience or deal with these issues in a similar fashion.

This paper aims to discuss the precise altitude and velocity tracking control of a hypersonic vehicle, a global adaptive neural backstepping controller was studied based on a disturbance observer (DOB).

The DOB combined with a radial basis function (RBF) neural network (NN) was used to estimate the disturbance terms that are generated by the flexible modes of the hypersonic vehicle system. A global adaptive neural method was introduced to approximate the unknown system dynamics, with robust control terms pulling the system transient states back into the neural approximation domain externally.

The globally uniformly ultimately bounded for all signals of a closed-loop system can be guaranteed by the proposed control algorithm. Additionally, the command filtered backstepping methods can avoid the explosion of the complexity problem caused by the backstepping design process. In addition, the effectiveness of the proposed controller can be verified by the simulation used in this study.

Normally lateral dynamics issue should be discussed in the process of control system designed, the lateral dynamics are not included in the nonlinear dynamic model of hypersonic vehicle used in this paper, merely the longitudinal flight dynamics are discussed in this paper.

The flexible states in rigid modes are considered as the disturbance of the system, which is estimated by structuring DOB with NN approximations. The compensating tracking error and prediction error are used in the update law of RBF NN weight. The differential explosions complexity derived from the backstepping procedure is dealt with by using command filters.

Expanding on earlier research, this paper aims to develop a more complete understanding of military experience as it relates to stress and burnout in law enforcement. The current study examines whether influences on stress and burnout vary between officers with military experience and officers without a military background.

Data for this study were obtained from earlier research on police staff at a Northeastern metropolitan city. A combination of analytic methods, including t‐tests and multivariate regression analysis, were used to explore the effects of variables on stress and burnout among military and non‐military officers.

The results indicate that negative exposures to demanding events influenced burnout for all officers. In contrast, negative exposures affected stress levels for those officers with no military experience. Coping techniques were important predictors of stress and burnout for both groups; however, contrary to expectations, police experience in years was not significant in any model. Demographic controls had no influence on stress and burnout for either group, with the exception of gender, which was a significant predictor of stress only for the non‐military group.

This research has implications for police departments interested in developing group‐based strategies for reducing stress and burnout among officers. The findings are limited in their capacity for wide geographical generalization, however, because this study represents the views of only one department.

In contrast with previous empirical work, the findings here demonstrate that military experience can have a favorable influence on the work outcomes of police officers. This study suggests that officers with military backgrounds are less stressed when faced with demanding situations and that military experience provides female officers with an edge in handling work‐related stressors.

The purpose of this paper is to examine the disparities in stress between rural and urban police officers in China.

Data for this study were collected from a national police university in China in 2017. In total, 608 Chinese police officers were surveyed representing those attending in-service training program in the university.

Results showed that rural police officers exhibited a higher level of somatization compared to their urban counterparts, whereas no rural–urban differences were detected for other stress dimensions – anxiety and depression. Additionally, this study suggests that perceived constraints in resources and training partially mediate the observed rural–urban disparities in somatization.

This study is based on a convenient sample of Chinese police officers, which restricts the generalizability of the results.

To reduce stress among police officers, China needs to make more investments in resources and training programs in its rural policing.

A review of literature reveals that studies comparing police stress between rural and urban areas are rare. Additionally, China, as the largest developing nation in the world, remains under-studied with respect to stress among its police officers.