57 resultados para job characteristics

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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With the emergence and development of positive psychology, happiness has been the focus of academia and business. However, there is no uniform measure of happiness, because of many different theories of happiness, which are not compatible with others. It bounds the further development of happiness theory. It is also the same with the research of work well-being, which refers to the emotional experience and quality of psychological functioning of employee in the workplace. Subjective well-being (SWB) and psychological well-being (PWB) are two major theories of happiness. Prior research has demonstrated the integration of these two theories theoretically, but still needs more empirical support. Besides, in line with the development of positive psychology, a body of knowledge about positive leadership is advocated. Transformational leadership is treated as one kind of positive leadership, since it emphasizes the leader’s motivational and elevating effect on followers. But the extent to which the transformational leadership can enhance work well-being, and what the mechanism is, these are the questions need to be explored. Based on the integration of SWB and PWB, this research tried to investigate the structure, measurement and mechanism of work well-being, and combining with the theory of transformational leadership, this study also tried to investigate the relationship between transformational leadership and work well-being. The structure and measurement of work well-being, the relationships between work well-being and job characteristics (including job resources and job demands), the relationships among transformational leadership, job resources, work well-being and corresponding outcomes, the relationships among transformational leadership, job demands, work well-being and corresponding outcomes, and the relationships among transformational leadership, group job characteristics, group work well-being and corresponding group outcomes were explored by using content analysis, Subject Matter Experts (SMEs) discussion, and structural questionnaire surveys. More than 7000 subjects were surveyed, and Explore Factor Analysis (EFA), Confirm Factor Analysis (CFA), Structural Equation Modeling (SEM), Hierarchical Linear Modeling (HLM) and other statistics methods were used. The following is the major conclusions. Firstly, work well-being is a two high-order factors structure, which includes affective well-being (AWB) and cognitive well-being (CWB). AWB is similar to SWB, and CWB is similar to PWB. Besides, the construct of AWB includes sub-dimensions of positive emotional experience and negative emotional experience. And the construct of CWB consists of work autonomy, personal growth, work competent, and work significance. Secondly, the relationships between job characteristics and AWB and CWB are different. On one hand job demands are directly related to AWB, and are indirectly related to CWB through the full mediation of AWB, on the other job resources are directly related to CWB, and are indirectly related to AWB through the full mediation of CWB, which means AWB and CWB reciprocally influences each other in the model of job demands-resources. These results were concluded as the process model of work well-being. Thirdly, AWB and CWB are positively related to many workplace outcomes, including job satisfaction, group satisfaction, organizational commitment, turnover intention, job performance, organizational citizenship behavior (OCB), and general psychological health and general physiological health. Fourthly, transformational leadership is indirectly related to CWB through the full mediation of job resources, and is related to AWB through the partial mediation of job demands. Meanwhile, transformational leadership is related to many workplace outcomes through the mediation of job characteristics and work well-being. These results implied that transformational leadership is indeed one kind of positive leadership. Fifthly, in the group level, transformational leadership is indirectly related to group CWB through the full mediation of group job resources, and is related to group AWB through the full mediation of group job demands. Group AWB has positive influence on group CWB, but not vice versa. Group job characteristics and group work well-being fully mediate the relationships between transformational leadership and intragroup cooperation and group performance.

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The work-family relations included positive relationship (work-family enrichment) and negative relationship (work-family conflict). Along with the development of positive psychology, the researchers turned their focus from work-family conflict to work-family enrichment. On the other hand, the research between work and family had just started and most attention was fix on work-family conflict. This research based on the skilled workers in manufacturing, and tried to discuss antecedents and the machanism of work-family relations through a series research which include action relation among job characteristics, work-family relations and outcomes of work, and the action relation among job resource、work-family relations、marital adjustment、work outcomes and role salience. This subject made the investigation to the workers who are working in manufacturing through literature research, questionnaire surveys and other methods. In this subject, several statistical techniques such as Explore Factor Analysis(CFA),Structural Equation Modeling(SEM), multiple-group Analysis were used to get the following conclusion: Firstly, work-family enrichment was an independent variable in work-family conflict, which had more extensively influence. Work-family conflict would increase accompany with the increasing of job demand, and it also would enhance negative work outcomes; work-family enrichment was effected by both job demand and job resource, and it made positive influence to positive and negative work outcomes. Secondly, marital adjustment penetrated into work domain through work-family enrichment inner effect mechanism, and influenced the work outcomes. The work→family enrichment and family→work enrichment could facilitate mutually, marital adjustment influenced the work outcome by the reciprocal relationship of work→family enrichment ↔ family→work enrichment. Finally, the family-role salience had directed loop-enhanced effect to organizational commitment and the importance could also enhance the positive function of work→family enrichment to organizational commitment.

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This thesis study the problem of work group effectiveness and group job design according to extensive literature investigation and the analysis of realistic background. The whole research consists of four parts: (1) The evaluation of work group effectiveness, the aim is to search to criteria that can describe and analysis work group, and explore the cognitive dimensions of effectiveness of Chinese subjects; (2) The study on the relationship between group job characteristic and effectiveness, the aim is to find the general correlation between work group characteristic and effectiveness, and try to search the most important core variable; (3) The study on the preference for the way of group work; (4) The study of the relationship between group composition and group effectiveness, try to examine how different approaches of personnel selection influence work results. The results indicate: (1) The evaluation of group effectiveness mainly consists of two dimensions: performance and the employee's attitude and feelings toward the group, so we can use these two dimensions and corresponding criteria as the standard of effectiveness evaluation. (2) According to the analysis of related literature, we can determine work group characteristic from five aspects: job design, the interdependence among members, group composition, organizational background, group process. (3) Experimental study find that different group job characteristics have different relationship models with effectiveness criteria. Job design, the interdependence among group members, group composition have significant correlation relationships with two kinds of effectiveness criteria; organizational background mainly has relationships with satisfaction criteria; group process mainly has relationships with performance criteria. (4) The choice for people to select the way of group work has the consistency, that is people prefer to "Self--managed work groups"; but different groups have the difference, the main group dimension is the difference between group members and group leaders. (5) Work groups which were composed accordingly to interpersonal attraction have higher levels of communication, coordination, group cohesion and job satisfaction than ability--based groups based. But the performance evaluation under these two conditions has no difference. The thesis analysis and discuss the research results, also point out several questions that needed to be explored further and the possible research directions in the future. This study has some reference value in group--level performance appraisal and reward design, the content and method of group--level job design, and personnel selection of group, etc.

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本文研究了圆柱受限空间内的喷雾火焰嫩烧压力振荡的特性。为了更清楚地了解火焰的构造, 首先测量了火焰的温度场,在较大的一次风和二次风变化范围内, 测量了压力的振荡特性。结果表明,火焰的稳定是由回流区完成的, 在较小的一次风燃料当量比和中等的二次风量时, 振荡最强, 达到100Pa左右的量级,其频率为200-230Hz左右,分析表明燃烧室中的振荡是轴向驻波振荡。

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利用特殊设计的等离子体发生器,选择等离子体产生的工艺参数,实现工艺过程的精确控制,在大气压环境下获得了性能稳定的氖气直流层流等离子体射流。与湍流等离子体射流长度较短、径向尺寸较大、工作噪音高等特点相比,层流等离于体射流长度可达到550mm,而且沿整个射流长度其径向尺寸维持不变,工作噪音很小。当气流量为120cm~3/s、弧电流在70-200A的范围时,射流长度随弧电流的增加而增加,热效率起初略有降低然后维持平稳。随气流量的增加,层流等离子体射流的热效率也增加,在弧电流为200A时,可以达到40%。实验中测

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The spherically converging detonation wave was numerically investigated by solving the one-dimensional multi-component Euler equations in spherical coordinates with a dispersion-controlled dissipative scheme. Finite rate and detailed chemical reaction models were used and numerical solutions were obtained for both a spherical by converging detonation in a stoichiometric hydrogen-oxygen mixture and a spherically focusing shock in air. The results showed that the post-shock pressure approximately arises to the same amplitude in vicinity of the focal point for the two cases, but the post-shock temperature level mainly depends on chemical reactions and molecular dissociations of a gas mixture. While the chemical reaction heat plays an important role in the early stage of detonation wave propagation, gas dissociations dramatically affect the post-shock flow states near the focal point. The maximum pressure and temperature, non-dimensionalized by their initial value, are approximately scaled to the propagation radius over the initial detonation diameter. The post-shock pressure is proportional to the initial pressure of the detonable mixture, and the post-shock temperature is also increased with the initial pressure, but in a much lower rate than that of the post-shock pressure.

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The fluid characteristics of gas flows in the micronozzle whose throat height is 20 μm were investigated by the direct simulation Monte Carlo (DSMC) method. In a series of cases, the dependence of mass flux on the pressure difference was gained, and the DSMC's results show good agreement with the experimental data. The comparison of mass flux and the Mach number contours between the DSMC and Navier-Stokes equations adding slip boundary also reveals quantitatively that the continuum model will be invalid gradually even when the average Knudsen number is smaller than 0.01. As one focus of the present paper, the phenomenon of the multiple expansion-compression waves that comes from the nozzle's divergent part was analyzed in detailed.

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Experimental investigations on the ignition and combustion stabilization of kerosene with pilot hydrogen in Mach 2.5 airflows were conducted using two test combustors, with cross sections of 30.5 x 30 and 51 x 70 mm, respectively. Various integrated modules, including the combinations of different pilot injection schemes and recessed cavity flameholders with different geometries, were designed and tested. The stagnation pressure of vitiated air varied within the range of 1.1-1.8 NiPa, while the stagnation temperature varied from 1500 to 1900 K. Specifically, effects of the pilot hydrogen injection scheme, cavity geometry, and combustor scaling on the minimally required pilot hydrogen equivalence ratio were systematically examined. Results indicated that the cavity depth and length had significant effects on the ignition and flameholding, whereas the slanted angle of the aft wall was relatively less important. Two cavities in tandem were shown to be a more effective flameholding mechanism than that with a single cavity. The minimally required pilot hydrogen equivalence ratio for kerosene ignition and stable combustion was found to be as low as 0.02. Furthermore, combustion efficiency of 80% was demonstrated to be achievable for kerosene with the simultaneous use of pilot hydrogen and a recessed cavity to promote the ignition and global burning.

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Modeling study is performed to compare the flow and heat transfer characteristics of laminar and turbulent argon thermal-plasma jets impinging normally upon a flat plate in ambient air. The combined-diffusion-coefficient method and the turbulence-enhanced combined-diffusion-coefficient method are employed to treat the diffusion of argon in the argon-air mixture for the laminar and the turbulent cases, respectively. Modeling results presented include the flow, temperature and argon concentration fields, the air mass flow-rates entrained into the impinging plasma jets, and the distributions of the heat flux density on the plate surface. It is found that the formation of a radial wall jet on the plate surface appreciably enhances the mass flow rate of the ambient air entrained into the laminar or turbulent plasma impinging-jet. When the plate standoff distance is comparatively small, there exists a significant difference between the laminar and turbulent plasma impinging-jets in their flow fields due to the occurrence of a large closed recirculation vortex in the turbulent plasma impinging-jet, and no appreciable difference is found between the two types of jets in their maximum values and distributions of the heat flux density at the plate surface. At larger plate standoff distances, the effect of the plate on the jet flow fields only appears in the region near the plate, and the axial decaying-rates of the plasma temperature, axial velocity and argon mass fraction along the axis of the laminar plasma impinging-jet become appreciably less than their turbulent counterparts.

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The characteristics of low-speed fluid streaks occurring under sheared air-water interfaces were examined by means of hydrogen bubble visualization technique. A critical shear condition under which the streaky structure first appears was determined to be u(tau) approximate to 0.19 cm/s. The mean spanwise streak spacing increases with distance from the water surface owing to merging and bursting processes, and a linear relationship describing variation of non-dimensional spacing <(+)over bar> versus y(+) was found essentially independent of shear stress on the interface. Values of <(+)over bar>, however, are remarkably smaller than their counterparts in the near-wall region of turbulent boundary layers. Though low-speed streaks occur randomly in time and space, the streak spacing exhibits a lognormal probability distribution behavior. A tentative explanation concerning the formation of streaky structure is suggested, and the fact that <(+)over bar> takes rather smaller values than that in wall turbulence is briefly discussed.

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特征分析表明:对原始扰动量的抛物化稳定性方程组(PSE),它在亚超音速区分别具有椭圆和抛物特性,给出PSE特征对马赫数的依赖关系,阐明PSE仅把信息对流-扩散传播特性抛物化,而保留了信息对流-扰动传播特性,因此PSE应称为扩散抛物化稳定性方程(DPSE)。

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A gliding arc discharge plasma and its characteristics are described. Analysis on the production principle of the plasma is presented. Some experimental results about two novel types of the gliding arc plasma generator were obtained. These types of gliding arc plasma are potentially used in chemical industry and environment engineering.

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报道热等离子体射流产生及射流特性的实验研究结果。。采用同一个直流等离子体发生器,工作气体流量小时产生出层流等离子体长射流,射流长度随气体流量或弧电流的增加而明显增加;工作气体流量大时则产生出湍流等离子体短射流,此时射流长度几乎与工作气体流量或弧电流无关;在层流与湍流等离子体射流工况之间,存在一个流动状况不稳定的过渡区,此时等离子体射流的平均长度随气流量的加大而减小,但随弧电流的加大而明显加大。层流等离子体长射流有相当好的刚性。