能源补贴的类型、效果和策略

为了扶持尚处于弱势地位的新的能源生产类型和新消费方式,为了帮助承担过重社会责任的企业,有时为了减轻消费者的负担等,往往以国家财政对能源生产、消费进行补贴。恰当的补贴可促进能源生产的创新,引导节能环保的能源消费方式,但过多过长时间的补贴会削弱企业的竞争力。有时为了争抢补贴一哄而上会造成产业畸形发展,使政府和企业陷入被动和困境。对能源消费的多种补贴如长期持续并不断增大,不但不利于节能,还将造成日趋增大的政府赤字,最终影响经济发展和社会稳定。建议能源补贴应向科技研发倾斜、向各类开拓创新的新领域倾斜,对领取补贴的能源生产要以最终商品量考核。补贴量不宜过大、时间不应过长,尽量减少现金补贴、多用减税减负等方法创造更好的经营环境。总之,补贴是一种政府干预市场的行为,应该慎重从事。政府要考虑的不仅是该不该补贴,还要注意补贴的方式、力度、时间以及防止权力寻租和企业骗补等问题。     

Numerical prediction and performance experiment in a deep-well centrifugal pump with different impeller outlet width

The existing research of the deep-well centrifugal pump mainly focuses on reduce the manufacturing cost and improve the pump performance,and how to combine above two aspects together is the most difficult and important topic.In this study,the performances of the deep-well centrifugal pump with four different impeller outlet widths are studied by the numerical,theoretical and experimental methods in this paper.Two stages deep-well centrifugal pump equipped with different impellers are simulated employing the commercial CFD software to solve the Navier-Stokes equations for three-dimensional incompressible steady flow.The sensitivity analyses of the grid size and turbulence model have been performed to improve numerical accuracy.The flow field distributions are acquired and compared under the design operating conditions,including the static pressure,turbulence kinetic energy and velocity.The prototype is manufactured and tested to certify the numerical predicted performance.The numerical results of pump performance are higher than the test results,but their change trends have an acceptable agreement with each other.The performance results indicted that the oversize impeller outlet width leads to poor pump performances and increasing shaft power.Changing the performance of deep-well centrifugal pump by alter impeller outlet width is practicable and convenient,which is worth popularizing in the engineering application.The proposed research enhances the theoretical basis of pump design to improve the performance and reduce the manufacturing cost of deep-well centrifugal pump.     

Numerical simulation and analysis for collapse responses of RC frame structures under earthquake

In this paper, a discrete element model for collapse simulation of RC frame structure is constructed by discretizing the structure into a few elements and spring groups. This model introduces special hysteretic models of connected springs for arbitrary loading path and also takes into account reasonable failure criteria for springs considering coupling effect of shear and axial force. Based on the discrete element model, a computer program is developed to simulate the whole process of RC frame structures from initial state to collapse under earthquakes. Particularly, the contact-impact problem between discrete elements has been treated with effective measures. Then, the program is employed to study the collapse mechanism of a real building in Wenchuan earthquake-hit area; the result of which shows that the simulation program developed based on the new model can realistically simulate the seismic collapse process of RC frame structures.     

离散制造业MES系统作业计划管理模块设计与实现

制造执行MES(Manufacturing Execution System)系统是制造业信息化系统的重要组成部分,是企业全面实现信息化管理的关键。作业计划管理模块是离散制造业MES系统的核心所在。本文以某制造企业(机匣厂)为例,重点介绍了MES系统作业计划管理模块的体系结构,并对作业计划管理模块设计及实现方法、优化排产方法、关键技术等进行了探讨,同时分析了所使用的关键技术。     

Heat flux distribution on circulating fluidized bed boiler water wall

The future of circulating fluidized bed (CFB) combustion technology is in raising the steam parameters to supercritical levels. Understanding the heat flux distribution on the water wall is one of the most important issues in the design and operation of supercritical pressure CFB boilers. In the present paper, the finite element analysis (FEA) method is adopted to predict the heat transfer coefficient as well as the heat flux of the membrane wall and the results are validated by direct measurement of the temperature around the tube. Studies on the horizontal heat flux distribution were conducted in three CFB boilers with different furnace size, tube dimension and water temperature. The results are useful in supercritical pressure CFB boiler design.     

Analysis and experiment on structure parameters for an energy reclaiming suspension

An energy reclaiming suspension is proposed to reclaim vibration energy in the suspension. To study its riding performance and reclaiming energy performance, a hydraulic energy reclaiming device prototype is produced and its mechanical behavior is analyzed and tested according to the hydraulic theory. Theoretical analysis shows that mechanical behavior of the energy reclaiming device is embodied by a viscidity damping parameter and an analogous coulomb damping parameter determined by its structure; their expressions are obtained. Experimental investigation shows that theoretical predictions agree with test results.     

Stability and coupling dynamic behavior of nonlinear journal active electromagnetic bearing rotor system

The stability and coupling dynamic behavior of a journal active electromagnetic bearing rotor system are analyzed. The gyroscopic effect is considered in the rotor model. The system equations are formulated by combining equations for rotor motion and decentralized proportional integral differential (PID) controllers. A method combining the predictor-corrector mechanism and the Netwon-Raphson method is presented to calculate the critical speed at the corresponding Hopf bifurcation point of the system. For periodic motions, a continuation method combining the predictor-corrector mechanism and shooting method is presented. Nonlinear unbalanced periodic motions and their stability margins are obtained using the shooting method and established continuation method for periodic motions. With the change of control parameters, the system local stability and bifurcation behaviors are obtained using the Floquet theory. The numerical examples show that the schemes not only significantly save computing cost, but also have high precision.     

Modeling of specific structure crystallization coupling with dissolution

In this paper, the research framework for specific structure crystallization modeling has been proposed in which four steps are required in order to investigate the rigorous crystallization modeling by thermodynamics. The first is the activity coefficient model of the solution, the second is Solid-Liquid equilibrium, the third and fourth are the dissolution and crystallization kinetics modeling, respectively. Our investigations show that the mechanisms of complex structure formation and microphase transition can be analyzed by combining the dissolution and crystallization kinetics modeling. Moreover, the formation mechanism of the porous KCl has been analyzed, which may provide a reference for the porous structure formation in the advanced material synthesis.     

Polymorphism of pharmaceutical molecules: perspectives on nucleation

Polymorphism is a widespread phenomenon observed in more than half of all drug substances. Various polymorphs frequently possess different physical, chemical, mechanical and thermal properties that can profoundly affect the bioavailability, stability and other performance characteristics of the drug. Accordingly, the elucidation of the relationship between the particular polymorph of a pharmaceutical molecule and its functional properties is crucial to select the most suitable polymorph of the pharmaceutical molecule for development into a drug product. This review briefly introduces recent advances in the discovery and control of the polymorphs of pharmaceutical molecules, in terms of the enhancement of the selective nucleation of a particular polymorph. In the light of this, some cases discussed in the following is to be considered controversial.     

Fast and catalytic pyrolysis of xylan: Effects of temperature and M/HZSM-5 (M= Fe,Zn) catalysts on pyrolytic products

Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of xylan and on-line analysis of pyrolysis vapors. Tests were conducted to investigate the effects of temperature on pyrolytic products, and to reveal the effect of HZSM-5 and M/HZSM-5 (M= Fe, Zn) zeolites on pyrolysis vapors. The results showed that the total yield of pyrolytic products first increased and then decreased with the increase of temperature from 350°C to 900°C. The pyrolytic products were complex, and the most abundant products included hydroxyacetaldehyde, acetic acid, 1-hydroxy-2-propanone, 1-hydroxy-2-butanone and furfural. Catalytic cracking of pyrolysis vapors with HZSM-5 and M/HZSM-5 (M= Fe, Zn) catalysts significantly altered the product distribution. Oxygen-containing compounds were reduced considerably, and meanwhile, a lot of hydrocarbons, mainly toluene and xylenes, were formed. M/HZSM-5 catalysts were more effective than HZSM-5 in reducing the oxygen-containing compounds, and therefore, they helped to produce higher contents of hydrocarbons than HZSM-5.