The long primary double-sided linear induction motor (LIM) has been used in industry. To improve the system efficiency and reduce the drive inverter capacity, the primary parallel connection with segment powered drive...
详细信息
ISBN:
(纸本)9781509012107
The long primary double-sided linear induction motor (LIM) has been used in industry. To improve the system efficiency and reduce the drive inverter capacity, the primary parallel connection with segment powered drive has been adopted in the drives consist of long primary double-sided LIMs. But, the LIMs parameters may vary with the position of the secondary, and it results in the thrust ripple. In this paper, a deduced voltage-current model is derived by simplifying the multi-motor stator flux into an average one and then the equivalent circuit with average parameter is obtained. Besides, this paper proposes a novel direct thrust control (DTC) based thrust feedback control method with thrust observer to eliminate the effects from motor parameters changes and to obtain a stable output thrust during acceleration. The control results verify the effectiveness of the method during the load acceleration.
The electric propulsion (EP) and planetary gravity-assist maneuver (GA) are facilitating deep space exploration. Nevertheless, the low maneuverability makes EP spacecraft necessitate long thrust arcs and susceptible t...
详细信息
In this paper, a novel design of asymmetry bistability for a coupled dielectric elastomer minimum energy structure (DEMES) is presented. The structure can be stable both in the stretched and curved configurations, whi...
详细信息
In this paper, a novel design of asymmetry bistability for a coupled dielectric elastomer minimum energy structure (DEMES) is presented. The structure can be stable both in the stretched and curved configurations, which are induced by the geometry coupling effect of two DEMESs with perpendicular bending axes. The unique asymmetry bistability and fully flexible compact design of the coupled DEMES can enrich the active morphing modes of the dielectric elastomer actuators. A theoretical model of the system's strain energy is established to explain the bistability. Furthermore, a prototype is fabricated to verify the conceptual design. The experimental results show that when the applied voltage is below a critical transition one, the structure behaves as a conventional DEMES, once the applied voltage exceeds the critical voltage, the structure could change from the stretched (curved) configuration to the curved (stretched) configuration abruptly and maintain in a new stable configuration when the voltage is removed. A multi-segment structure with the coupled DEMES is also presented and fabricated, and it displays various voltage-actuated morphings. It indicates that the coupled DEMES and the multi-segment structures can be useful for the soft and shape-shifting robots.
A simplified and effective biomechanical model of the foot is proposed in this work. The geometry of the foot is divided into two segments, the hindfoot and forefoot. The results are very promising, based on graphic r...
详细信息
A simplified and effective biomechanical model of the foot is proposed in this work. The geometry of the foot is divided into two segments, the hindfoot and forefoot. The results are very promising, based on graphic representation of the kinematic parameters during gait motion. The protocol was implemented in a classic gait lab and does not affect the standard procedure, despite the additional kinematic parameters included. This model will provide additional information for clinical diagnosis within lower extremities pathologies.
The manual lifting is a prevalent action during daily life and professional work. So lowback pain is common among these human. Many experts make researches on this subject in various fields with experimental method. I...
详细信息
The manual lifting is a prevalent action during daily life and professional work. So lowback pain is common among these human. Many experts make researches on this subject in various fields with experimental method. In this paper our research and analysis based on classical dynamic method. We simulated the lifting movement in the dynamic multi-segment model and defined θ(the angle between leg and ground) as generalized coordinate. Hence the equations of multi-body system were *** solving these equations, the angular velocity and angular accelerate of hip angle β,β and internal forces and moment of hip Nx, Ny, M were obtained. Especially,analytical solution of θ, was be obtained, it is convenient to further research internal mechanics of lifting o Based on above analysis, the conclusions show that main influence of Nx, Ny, M is the change of angular acceleration θ. The key factor to avoid injure is control the type of smooth lifting.
The conventional view in the standard finance textbooks is that organizational form does not matter for a firm's cost of capital because firm diversification reduces only idiosyncratic risk and not systematic risk...
详细信息
The conventional view in the standard finance textbooks is that organizational form does not matter for a firm's cost of capital because firm diversification reduces only idiosyncratic risk and not systematic risk. In this study, we investigate the effect of global diversification on the ex-ante cost of equity implied by the residual income valuation model (Ohlson, Earnings, book value and dividends in security valuations. Contemporary Accounting Research, 11(2), 661-687, 1995), using a sample of US firms from 1997 to 2019. Employing the empirical approach developed in Easton et al. (Using forecasts of earnings to simultaneously estimate growth and the rate of return on equity investment. Journal of Accounting Research, 40(3), 657-676, 2002), our results suggest that global diversification reduces the cost of equity capital for both single-segment firms and multi-segment firms. Our results highlight the effect of global diversification on the equity risk reduction, which may explain the increasing proliferation of foreign operations among US firms - a trend that neither the cash flow effect nor the capital structure effect proposed in previous studies can explain.
Abstract— We have proposed a new approach to engineering and manufacturing an indoor indicator based on energy-effective super-bright LEDs. In our design, the light from a small number of such LEDs was uniformly redi...
详细信息
Abstract— We have proposed a new approach to engineering and manufacturing an indoor indicator based on energy-effective super-bright LEDs. In our design, the light from a small number of such LEDs was uniformly redistributed using a special light guide. Recently, we developed a multi-segment (40) LED indicator with improved ergonomics and a luminance of up to 4000 cd/m 2 . This indicator is also capable of displaying (apart from the digits) special symbols.
暂无评论