机房专用精密空调群控管理系统研究

在机房专用精密空调系统中,制冷、制热、加湿和除湿空调系统是独立的运行的,在这种运行机制下,会出现部分能量相互抵消的情况,造成能量的浪费。针对这一问题,需要应用合理的群控管理系统,在控制机房环境的基础上,优化空调运行效果,并实现节能目标。对机房专用精密空调群控管理系统展开了研究,以提高机房专用精密空调的运行水平。

SUBDIVIDING VERBS TO IMPROVE SYNTACTIC PARSING

This paper proposes a new way to improve the performance of dependency parser: subdividing verbs according to their grammatical functions and integrating the information of verb subclasses into lexicalized parsing model. Firstly,the scheme of verb subdivision is described. Secondly,a maximum entropy model is presented to distinguish verb subclasses. Finally,a statistical parser is developed to evaluate the verb subdivision. Experimental results indicate that the use of verb subclasses has a good influence on parsing performance.

Analysis of Effective Working Hours of Automatic Assembly Equipment for Aircraft Assembly Stations

To improve the accuracy of capacity analysis and prediction for the aircraft assembly stations,an approach for calculating the effective working hour(EWH)of automatic assembly equipment is introduced by using the dynamic mixed Weibull distribution(DMWD)model.Firstly,according to the features of aircraft assembling,a DMWD model considering the dynamic reliability of multiple subsystems and their synthetic effects on the whole equipment is established.A typical automatic drilling&riveting machine is selected as the research object,and the dynamic weights of reliability of three subsystems are modeled and solved.Subsequently the unknown parameters of the DMWD model are estimated based on maximum likelihood estimation(MLE)and Newton-Raphson method.Finally,the EWH of an automatic station is defined and modeled by using the solved dynamic reliability function.Based on the experimental study on a real automatic drilling&riveting machine from a wing panel assembly station,it is shown that the proposed DMWD and EWH models could effectively calculate the equipment reliability with full consideration of its multiple subsystems.The DMWD model is more suitable for improving the solution precision of EWH than the traditional three-parameter Weibull distribution.

Automatic Damage Detection of Engineering Ceramics Ground Surface Based on Texture Analysis

Ground textures seriously interfere with the exact identification of grinding damage. The common nondestructive testing techniques for engineering ceramics are limited by their difficulty and cost. Therefore, this paper proposes a global image reconstruction scheme in ground texture surface using Fourier transform (FT). The lines associated with high-energy frequency components in the spectrum that represent ground texture information can be detected by Hough transform (HT), and the corresponding high-energy frequency components are set to zero. Then the spectrum image is back-transformed into the spatial domain image with inverse Fourier transform (IFT). In the reconstructed image, the main ground texture information has been removed, whereas the surface defects information is preserved. Finally, Canny edge detection is used to extract damage image in the reconstructed image. The experimental results of damage detection for the ground texture surfaces of engineering ceramics have shown that the proposed method is effective.

Vibration Analysis and Direct Control of XY Table Automated Assembly Machines

XY table automated assembly machines ensure time saving and quality improving in the electronics industry. Recently, due to the need of higher operation speeds and lighter machines in PCB （Printed Circuit Board） assembly, a challenging problem has arisen which is the table positioning vibration. The high speed with the machine flexibility, make the positioning vibration inevitable although the inner control. The positioning vibration is to be reduced otherwise the machine becomes useless. Firstly, the machine is modeled, the positioning vibration is formulated, and then analyzed. Secondly, using the analysis, three direct control methods are identified to decrease the positioning vibration, they are based on the kinematics, dynamics, and operation of the machine. Thirdly, the methods are examined numerically to evaluate their efficiency. Lastly, the identified methods are discussed to conclude on their application. The results are a real contribution in the vibration control of XY table automated assembly machines, which is classified as industrial knowhow.

Analysis of Cutting Force by End Milling Using Artificial ntelligence

The cutting forces during end milling process by using Genetic Algorithm are investigated in this paper. However, automated CNC （computer numerical control） programming by milling machine is intended to use for special required conditions of programming of tool path length, and analysis of cutting force and optimization of main parameters are presented. Some effective simplification of automated programming is done for cutting force. The cutting force is modelled and analyzed into mathematical simulations in order to optimize the main cutting parameters, also in this case tool path length, it is get as free trajectory. Optimization is carried out by using the Matlab/Genetic Algorithm method that excessively reduce the time and to optimize the main cutting parameters of machining. The number of experiments, measurements and results of cutting force （F~）, are presented in 3D as well as in tables. In order to verify the accuracy of the 3 D simulation with optimization method, the results are compared in experimental and theoretical way. In other word, these results indicate directly that the optimized parameters are capable of machining the workpiece. Achieved results that are presented in this paper may in general help the new researcher as well as manufacturing industries of metal cutting.

The United States： Economic Crisis, Productive Restructuring and the New Precarious Labor Conditions

The contemporary economic crisis should be considered within the framework of the contradictions created by the neoliberal model that was adopted in the mid-1970s, in the United States and throughout much of the world. The changes in the labor market and new forms of workforce exploitation based on deregulation, the increase of off-shoring, and flexible hiring practices have led to ＂new＂ precarious labor conditions. Due to the crisis, the United States labor market has been characterized by four factors： the increase of the unemployment, the unedited growth of the informal sector, a dramatic increase in precarious labor conditions for all workers, especially young people, minorities, and immigrants, and the increasing wage polarization. However, capitalist profit rates have actually substantially increased due to neoliberal policies and the resulting economic crisis. This situation led to a rise in the overexploitation of labor. It has had subsequent effects on unemployment, informal work, precarious labor conditions, and unequal salary distribution, especially in recently created positions. Increased labor flexibility has changed the typical forms of wage employment, and stable employment has been replaced by temporary and part-time employment usually with low wages and without social security and benefits.