1,299 research outputs found

    Organizational theory: With its applications in biology and ecology

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    Organizations are goal-directed entities which have been designed as deliberately structured and coordinated dynamic systems that connect with the external environment. Organizational theory is the study of structure, function and design of organization. It aims to solve practical problems, maximize production efficiency and make organization better function and develop. Organizational theory contains various aspects. The history, development, and thoughts of organizational theory and its applications in biology and ecology were described in present paper. We held that more studies should be conducted to apply organizational theory in natural sciences as biology and ecology

    On the stability of a laminated beam with structural damping and Gurt–Pipkin thermal law

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    In this paper, we investigate the stabilization of a one-dimensional thermoelastic laminated beam with structural damping coupled with a heat equation modeling an expectedly dissipative effect through heat conduction governed by Gurtin–Pipkin thermal law. Under some assumptions on the relaxation function g, we establish the well-posedness of the problem by using Lumer–Phillips theorem. Furthermore, we prove the exponential stability and lack of exponential stability depending on a stability number by using the perturbed energy method and Gearhart–Herbst–Prüss–Huang theorem, respectively

    Development and Evaluation of History Interest Inventory for Chinese K-12 Students

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    The purpose of this study was to develop and evaluate History Interest Inventory (HII) to measure Chinese K-12 students’ history interest. In this study, data were drawn from two independent samples of a city in Eastern China, and exploratory factor analysis (EFA) and confirmatory facto analysis (CFA) were conducted to reduce instrument size and evaluate the construct validity associated with HII. Furthermore, multiple regression analysis was run to evaluate the weights of each component in predicting students’ achievement. The indices of construct validity and reliability indicated that History Interest Inventory (HII) was an effective and reliable instrument to measure Chinese students’ history interest. To apply this instrument to students from other countries, it is suggested that CFA be conducted with the samples from target countries to check its validity and reliability

    Kernel Free Boundary Integral Method for 3D Stokes and Navier Equations on Irregular Domains

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    A second-order accurate kernel-free boundary integral method is presented for Stokes and Navier boundary value problems on three-dimensional irregular domains. It solves equations in the framework of boundary integral equations, whose corresponding discrete forms are well-conditioned and solved by the GMRES method. A notable feature of this approach is that the boundary or volume integrals encountered in BIEs are indirectly evaluated by a Cartesian grid-based method, which includes discretizing corresponding simple interface problems with a MAC scheme, correcting discrete linear systems to reduce large local truncation errors near the interface, solving the modified system by a CG method together with an FFT-based Poisson solver. No extra work or special quadratures are required to deal with singular or hyper-singular boundary integrals and the dependence on the analytical expressions of Green's functions for the integral kernels is completely eliminated. Numerical results are given to demonstrate the efficiency and accuracy of the Cartesian grid-based method

    Investigation on Remote Monitoring System for Heat-Supply Thermal Characters Based GPRS

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    AbstractWith the strategy requirements of low-carbon and energy-saving, the appropriate auto-control methods become more and more important. Aiming to monitor the thermal characters of the heat exchange station in the real time, the investigation framework in this paper presents an integral solution. We incorporate wireless data gathering from different heat exchange station, sending data to the service through the Internet and managing by sever.Net. We exploit formalization software by three-layer Browser-Server structure to regulate how thermal characters data should be gathered, communicated among concerned parties and interpreted to server/Date Base in decision-making. Meanwhile, the communication among the nodes that form the distributed system is implemented by means of the utilization of wireless networks, and secondary data transmission services (GSM or GPRS) provided by a mobile telephone operator. This monitoring system has been running in good condition and stable operation with lower fault rate and higher credibility data. This system, once fully deployed, can significantly reduce human labor and provide real-time data monitoring to achieve the propose of energy conservation and emission reduction

    Kernel-free boundary integral method for two-phase Stokes equations with discontinuous viscosity on staggered grids

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    A discontinuous viscosity coefficient makes the jump conditions of the velocity and normal stress coupled together, which brings great challenges to some commonly used numerical methods to obtain accurate solutions. To overcome the difficulties, a kernel free boundary integral (KFBI) method combined with a modified marker-and-cell (MAC) scheme is developed to solve the two-phase Stokes problems with discontinuous viscosity. The main idea is to reformulate the two-phase Stokes problem into a single-fluid Stokes problem by using boundary integral equations and then evaluate the boundary integrals indirectly through a Cartesian grid-based method. Since the jump conditions of the single-fluid Stokes problems can be easily decoupled, the modified MAC scheme is adopted here and the existing fast solver can be applicable for the resulting linear saddle system. The computed numerical solutions are second order accurate in discrete â„“2\ell^2-norm for velocity and pressure as well as the gradient of velocity, and also second order accurate in maximum norm for both velocity and its gradient, even in the case of high contrast viscosity coefficient, which is demonstrated in numerical tests

    Annealing evolutionary parallel algorithm analysis of optimization arrangement on mistuned blades with non-linear friction

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    This paper sets up a lumped parameter model of engine bladed disk system when considering the nonlinear friction damping based on mistuned parameters which is obtained from the blade modal experiment. A bladed arrangement optimization method, namely annealing evolutionary algorithm with tabu list is presented which combines the local search ability of SA (simulated annealing) and the global searching ability of GA (genetic algorithm) introducing tabu list as the search memory list. Parallel TAEA (tabu annealing evolutionary algorithm) is presented based on CUDA (Compute Unified Device Architecture) combining GPU (Graphics Processing Unit) and its performance is analyzed. The results show that optimization based on CUDA framework can improve computing speed. At the same time using optimization results can reduce the amplitude of forced vibration response of bladed disk system and make it in the range of allowable engineering

    Effects of stator-rotor interaction on unsteady aerodynamic load of compressor rotor blades

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    In compressor working, unsteady aerodynamic load induced by the interaction of stator-rotor blade rows is the main vibration source of blade high cycle fatigue. It has a direct influence on fatigue strength of compressor blades. Further research on unsteady aerodynamic load has very important significance for improving the service life and reliability of compressor blades. Based on an aero-engine compressor rotor system, three-dimensional flow field model of former stator and downstream rotor is established. With the method of numerical simulation, compressor flow characteristics are solved at different moments. Then the paper analyzes the process of stator-rotor interaction and the distribution law of rotor blade aerodynamic load. In addition, the effects on rotor blade aerodynamic load are discussed at different pressure ratios, rotational speeds and ratios of stator-rotor blade number. The results show unsteady flow field area with lower speed is induced by stator-rotor interaction at rotor blade leading edge. When the overlap space between stator and rotor channels is the maximum, mass flow and static pressure around rotor blade will appear jumping fluctuations. Unsteady aerodynamic load fluctuates periodically, and dominant frequencies are manly at frequency doubling of stator-rotor interaction, especially at one time frequency (1×f0). In the interaction period T, variations of aerodynamic load on pressure and suction surfaces take the contrary trend, magnitude and pulsation amplitude on pressure surface are far greater than that on suction surface. Effects of pressure ratio on pressure and suction surfaces are consistent, and the magnitude of aerodynamic load increases with pressure ratio. Rotational speed and stator-rotor blade number ratio affect the magnitude of aerodynamic load on suction surface more heavily than that on pressure surface. With the increasing of rotational speed, unsteady characteristics of aerodynamic load are enhanced. Besides, pulsation amplitude and peak value of unsteady aerodynamic load reach the maximum when stator-rotor blade number ratio λ=1. This research provides the theoretical basis for dynamics design of aero-engine compressor rotor syste
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