PAN基炭纤维经济规模分析

聚丙烯腈 (Polyacrylonitrile缩写为PAN)基炭纤维市场需求旺盛 ,但由于我国PAN基炭纤维生产企业规模小、产品性能低 ,产品占领不了市场 ,企业效益欠佳。通过经济规模方法的分析 ,就国内现有技术状况和两个样本生产线 ,用工程技术法对PAN基炭纤维的经济规模进行分析 ,为我国炭纤维产业化发展提供参考。分析表明 ,国内PAN基炭纤维经济规模的起点为 2 0 0t a～ 2 75t

Calculation method of ship collision force on bridge using artificial neural network

Ship collision on bridge is a dynamic process featured by high nonlinearity and instantaneity. Calculating ship-bridge collision force typically involves either the use of design-specification-stipulated equivalent static load, or the use of finite element method (FEM) which is more time-consuming and requires supercomputing resources. In this paper, we proposed an alternative approach that combines FEM with artificial neural network (ANN). The radial basis function neural network (RBFNN) employed for calculating the impact force in consideration of ship-bridge collision mechanics. With ship velocity and mass as the input vectors and ship collision force as the output vector, the neural networks for different network parameters are trained by the learning samples obtained from finite element simulation results. The error analyses of the learning and testing samples show that the proposed RBFNN is accurate enough to calculate ship-bridge collision force. The input-output relationship obtained by the RBFNN is essentially consistent with the typical empirical formulae. Finally, a special toolbox is developed for calculation efficiency in application using MATLAB software.

Vector modeling of robotic helical milling hole movement and theoretical analysis on roughness of hole surface

To avoid the machine problems of excessive axial force, complex process flow and frequent tool changing during robotic drilling holes, a new hole-making technology (i.e., helical milling hole) was introduced for designing a new robotic helical milling hole system, which could further improve robotic hole-making ability in airplane digital assembly. After analysis on the characteristics of helical milling hole, advantages and limitations of two typical robotic helical milling hole systems were summarized. Then, vector model of helical milling hole movement was built on vector analysis method. Finally, surface roughness calculation formula was deduced according to the movement principle of helical milling hole, then the influence of main technological parameters on surface roughness was analyzed. Analysis shows that theoretical surface roughness of hole becomes poor with the increase of tool speed ratio and revolution radius. Meanwhile, the roughness decreases according to the increase of tool teeth number. The research contributes greatly to the construction of roughness prediction model in helical milling hole.

Method for improving RLS algorithms

The recursive least-square (RLS) algorithm has been extensively used in adaptive identification, prediction, filtering, and many other fields. This paper proposes adding a second-difference term to the standard recurrent formula to create a novel method for improving tracing capabilities. Test results show that this can greatly improve the convergence capability of RLS algorithms.

The Evaluating Method of Technology Innovation Risk

The thesis analyzes risk factors of enterprise＇s technology innovation, adopts the undetermined measuring model to evaluate technology innovation risk and testifies it through an example.

A modeling method of semiconductor fabrication flows with extended knowledge hybrid Petri nets

A modeling method of extended knowledge hybrid Petri nets （EKHPNs）, incorporating object-oriented methods into hybrid Petri nets （HPNs）, was presented and used for the representation ~d modeling of semiconductor wafer fabrication flows. To model the discrete and continuous parts of a complex semiconductor wafer fabrication flow, the HPNs were introduced into the EKHPNs. Object-oriented methods were combined into the EKHPNs for coping with the complexity of the fabrication flow. Knowledge anno- tations were introduced to solve input and output conflicts of the EKHPNs. Finally, to demonstrate the validity of the EKHPN method, a real semiconductor wafer fabrication case was used to illustrate the model- ing procedure. The modeling results indicate that the proposed method can be used to model a complex semiconductor wafer fabrication flow expediently.

Nonlinear stochastic optimal bounded control of hysteretic systems with actuator saturation

A modified nonlinear stochastic optimal bounded control strategy for random excited hysteretic systems with actuator saturation is proposed. First, a controlled hysteretic system is converted into an equivalent nonlinear nonhysteretic stochastic system. Then, the partially averaged Itoe stochastic differential equation and dynamical programming equation are established, respectively, by using the stochastic averaging method for quasi non-integrable Hamiltonian systems and stochastic dynamical programming principle, from which the optimal control law consisting of optimal unbounded control and bang-bang control is derived. Finally, the response of optimally controlled system is predicted by solving the Fokker-Planck-Kolmogorov （FPK） equation associated with the fully averaged Itoe equation. Numerical results show that the proposed control strategy has high control effectiveness and efficiency.

Construction of Mechanized Claw as a Teaching Method in Engineering

The labor market requires, increasingly, an updated and more professional preparation, mainly due to the rapid pace of scientific technical advancement means in the industry. From this point, it is important to encourage the development of the basic techniques of control systems, electronics and communication in order to produce knowledge in the mechatronic field and so apply them to industry. Considering the relevance of this subject, the students of Federal University of Para-Campus Tucumi through the Research Group of Electrical and Mechanical Systems apply their knowledge in multidisciplinary engineering fields in order to generate knowledge from creative techniques using low cost materials, together with the encouragement of social and environmental responsibility which is very important nowadays. At the same time, targeting the needs of the labor market, this work aims to foster in students the skills and requirements through team projects and innovative methods. Therefore, this paper presents a mechanical manipulator, where their operating characteristics are based on industrial robots in the literature, powered by DC （direct current） motors and fully developed from reusable materials. By adding a developed control from the Arduino, prototyping platform with an electronic strategic offers through the internet the long-distance control convenience.

Precision blasting, current status and its prospective

Precision blasting,which is different from traditional control blasting,is regarded as the sign of new development stage of engineering blasting.The definition,connotation,technology system and current situation of its application and development were described briefly.With regard to the prospect of precision blasting,following aspects for further study are recommended:a.A multiple disciplinary study should be developed for a more understanding on the explosive energy release and quantitative blasting design;b.according to the requirements of digital blasting objective,syncretic study of precision blasting and technology should be enhanced;c.numerical simulation was an important tool for optimizing engineering blasting scheme and blasting harmful effects control,a more elaborate precision numerical simulation method should be studied furthermore;d.the modernization and standardization of precision blasting construction should be enhanced.