Analysis on Three -Dimensional Numerical Controlled Last Machining Algorithm

On the basis of applying three dimensional discrete formative technology to describing last surface, working principle of numerical controlled last carving machine is briefly introduced. Then the algorithm of ascertaining milling cutter machining position during the machining process is analyzed in detail. We establish a three dimensional reference frame with spatial analytic geometry and obtain the spatial equation of milling cutter rotary surface. According to last machining character, we put forward a machining algorithm named Minimal Distance Method and is used to calculate the milling cutter machining position. Finally, the glabrous degree of last made by us has reached the conventional demand.     

A new determination method of tool step for 5 axis NC machining

The peculiar non linear error in the 5 axis NC machining is studied. An improved tool step determination method for the 5 axis NC machining is proposed, in which the non linear error is compensated. Both the arc chord error and the non linear error are considered when computing the tool step, and the comprehensive error is taken as the function of the tool path parameter. Due to the difficulty of gaining the derivative of this function and the tool step according to the prescribed tolerance, the secant method is improved to guarantee the real solution locating in the converging range which is adopted to compute the tool step. The implementing example shows that the proposed method can compensate the non linear error effectively with meeting the prescribed tolerance. The exact tool step can be gotten efficiently with the improved secant method.     

Algorithm of Cutter Machining Position during Numerical Controlled Last Carving

Numerical control last making machine is a machine that is used to process shoe last. A new principle of numerical control machining shoe last is put forward aiming at the deficiency of current carving last system. On the basis of the principle, the algorithm of cutter machining position during numerical controlled carving last is analyzed in detail. The complex problem of the calculation of cutter machining positiion is resolved by applying spherical milling cutter that is often used in machining free_curve surface today and taking account of practical situation of the shoe last_making machine. At the same time, the calculation of cutter machining position is realized by program using Visual C++6.0. As a result, the calculation time of cutter machining position is reduced greatly and the efficiency of design is improved. Moreover, the process of carving last is agile and precision of carving last is ensured.     

Applied Data Disposal Technology of Numerical Controlled Last Carving Machine

Necessary technical disposal methods of original last data before carving are introduced in turn.First,data interpolation and smoothness are adopted for removing absent dots and bug dots.Afterwards,all sections of last are rotated and central axis is adjusted because measurement axis and machining axis are not the same.Finally,head and tail of last are designed and appended in order to use clamp to fix last during the machining process.     

Application of at Algorithm in Shoe Last Deformation Design

Deformation design is main content of shoe last CAD system. This paper introduces adaptive tangency (AT) algorithm, which is used to calculate the sectional curve when a known plane section shoe last under a discrete model, and describes its application in shoe last deformation design. Shoe last data can be converted each other in shoe last deformation design, which ensures data format standardized in whole CAD procedure. The detailed algorithm in deformation design is fulfilled and an actual example is given, which shows AT algorithm's application is successful.     

山西北部初终霜冻日特征及其对农业的影响

基于山西北部12个气象站1970～2008年逐日最低气温资料,采用现代气候统计诊断方法计算分析了山西北部霜冻初终日的气候特征,在此基础上,分析了霜冻发生对农业的影响。得出以下主要结论：(1)山西北部霜冻的发生与海拔高度密切相关,海拔越高初霜冻日到来越早、终霜冻日结束越晚;海拔高度对终日的影响>对初日的影响。(2)在山西北部大部分区域,初霜冻日呈现推后的趋势、终霜冻日呈现提前的趋势,但年际间变化大,前后两年相差可达30天以上。(3)山西北部初霜冻日的推后主要是从21世纪开始的;终霜冻日的年代际变化不完全同步,大多数代表站以20世纪90年代为转折点,70和80年代相对偏晚、之后相对偏早。(4)山西北部初霜冻日呈现逐渐推后的变化趋势、终霜冻日呈现逐渐提前的变化趋势使该地春玉米幼苗、成熟后期遭受霜冻危害的可能性大大降低,为当地春玉米提供了有利的生长条件。     

河西走廊东部初、终霜冻日和无霜期变化特征分析

为了引进适宜作物品种,合理调整种植结构,提高农业产业水平。利用1961—2014年河西走廊东部4个气象站初、终霜冻日（最低地温≤0℃）和年气温资料,采用气候诊断方法,对河西走廊东部初、终霜冻日及无霜期的变化进行了研究。结果表明,在时间变化上,初霜冻日显著推迟,终霜冻日显著提早,无霜期显著延长。初、终霜冻日和无霜期时间序列分别存在8~10年、9~11年和9~10年准周期变化。初、终霜冻日和无霜期均发生了气候突变。受海拔高度、地形地势和植被覆盖的影响,在空间分布上,初霜冻日为山区早于荒漠区早于绿洲平原区,终霜冻日为山区晚于荒漠区晚于绿洲平原区,无霜期为山区短于荒漠区短于绿洲平原区。初霜冻日、终霜冻日和无霜期与年气温和海拔显著相关。     

寿光1961—2015年初、终霜日、无霜期变化特征 及对农业的影响

笔者利用寿光市1961—2015年的气候资料,通过对初、终霜日期、无霜期观测资料,利用现代气候诊断分析方法,分析寿光市初、终霜日期、无霜期变化特征,科学评估初、终霜日变化对冬小麦和棉花产量的影响,为寿光农业生产防灾减灾提供参考依据。结果表明,（1）初霜日总体呈推迟趋势,终霜日呈提早趋势,无霜期延长。（2）初霜日呈推迟趋势,气候倾向率为2.23 d/10 a,1991年初霜日发生突变;（3）终霜日呈提前趋势,气候倾向率为-1.35 d/10 a。（4）无霜期日数呈增多趋势,气候倾向率为3.58 d/10 a,1994年无霜期日数发生突变。（5）初霜日和无霜期与小麦和棉花产量呈正相关,终霜日与小麦和棉花产量呈负相关,初霜日推迟比终霜日提前对小麦和棉花的产量贡献大。     

河套灌区脱水青红椒终霜冻气象指标研究

为了更好地开展脱水青红椒终霜冻气象服务,本研究选用脱水青红椒‘茄门’幼苗为试验材料,利用MSX-2F人工模拟霜箱系统模拟自然降温过程,通过测定幼苗的叶温,记录植株冻伤、冻死情况,结合光合作用,综合确定河套灌区脱水青红椒终霜冻指标。结果表明：（1）脱水青红椒幼苗全部冻死的最低温度≤-4℃;（2）脱水青红椒幼苗结冰点的范围为-2.7℃~-3.2℃,过冷却点的范围为-3.4℃~-4.8℃;（3）苗龄越大的脱水青红椒幼苗,耐受冻害的能力越强;（4）脱水青红椒幼苗轻霜冻地表温度指标为-3.5℃,重霜冻地表温度指标为-5.0℃。     

An Expert System Approach to the Computer Aided Design of Intelligent Controllers

The idea for an expert system approach to the computer aided design of intelligent controllers (ESCAD1C) is discussed and the idea of two step modelling of an intelligent controller is presented on the basis of emulating human control behaviours to solve complex problems. The structure, functions and characteristics of ESCADTC system , and the design procedures of intelligent controllers are gived. The knowledge base and simulating functions for designing intelligent controllers are also described.     

State and Prospects of Physics-Based Free-form Surface Modeling

Physics based modeling is one of the keen free form surface modeling method at present, and it should be a practical surface modeling method in the future. In Physics based modeling, the object is viewed as a physics and not a pure geometry model. According to its physics principle and math representation, the physics based models are mainly classified into two types:energy model and dynamic Lagrangian model. The fundamental theory is introduced, and the principle, development and application state of each model is reviewed. To provide designer more naturally design ability and to introduce more flexible geometric modeling methods are the prospect of future researches on physics based free form surface modeling is outlined at last.     

DEVELOPMENT OF COMPUTER AIDED PROCESS PLANNING SUBSYSTEM FOR A CAD/CAPP INTEGRATED SYSTEM

Based on Group Technology, a CAD/CAPP integrated system is developed. This paper mainly covers the research work of the CAPP subsystem. In this subsystem, geometric and manufacturing information is obtained from the CAD data base, modular block programming and full Chinese menu are adopted, process planning is produced with the semi-generative method, and process card involved the operation charts is yielded by printer. The operation is simple and convenient, and the performance is quick. The ? CAPP subsystem is successfully integrated with the CAD subsystem. The subsystem is an advanced CAPP system.     

ERRORS AND COMPENSATION OF FORM CUTTING HELICAL

A method which uses computer to model the form cutting of helical is presented and quantitatively analysed the errors of the ptofile shape and its position from the deviations of manufacturing and installing of the forming cutter and helical movement of the machine tools are quantitatively analysed, the optimum technique is used to revise the adjustable parameters for compensating the error. It is valuable in engineering application.     

FPGA Implementation of Pipelined FFT

A pipelined FFT processor designed for fast and real-time requirements with FPGA is introduced. This FFT processor can be used to real-time frequency analysis and its working frequency can reach to 75 MHz. The leakage error is reduced through multiply the sampled signal by a weighting window. In order to improve FFT's working frequency and economize FPGA resources, an algorithm of 1024-point complex to compute 2048-point real data is adopted. In addition, an approximate algorithm to compute module value of complex number is introduced.     

New Method of Machining Internal Spiral Groove of a Big Lift Angle

There exists muchinterference in machining internal spiral groove with big lift angle and small size, whichis a difficult problem. The design and calculation of tool section is analyzed in this paper while differentcutters are utilized to machine the groove when the tool axis is parallel or skew to that of the work piece. The approximating method of using circular-arc cutter is put forward, which is proved by the calculation and analysis to be a feasible method within range of the permissible error. The digital simulation of machining internal spiral groove which is finished by different methods, such as simulation of tool path, error analysis, verification of the cutter design and so on, has been done through typical software such as the Program files function of I-DEAS and the Manufacturing Module of UG.     

Investigation on Improving Manufacturing Precision of ZC1 Worm

Based on coordinate measrement of tooth surface of ZC1 worm, the deviation function for evaluating tooth surface is established. According to minimal zone principle, the profility of tooth surface of worm is evaluated. The machining errors of the worm are divided into setting error and adjusting error of the machine and tool. By error compensation, the setting error and adjusting error are corrected and the manufacturing precision of the worm is improved.     

Parameter Design for Machining Quenched Internal Helical Gears by EDM

Aiming at the problem of machining quenched internal helical gears, a method and its equipment are discussed and designed, which is used for machining quenched internal helical gears by EDM. Its characteristic and principle are proposed. The modifying design of the electrode gear and the calculating method of its modification coefficients is presented. Analyzing for the error of the machining equipment is done. The results show that this problem can be solved by EDM, the electrode gear is the modification gear of machined gear and the machining accuracy can be improved by controlling errors.     

山西省终霜冻变化及其与春季北太平洋海温的SVD分析

摘 要：利用山西省35个代表站1971-2008年逐年终霜冻资料和美国NCEP/NCAR再分析资料的全球逐月海温格点(2°×2°)资料,采用小波分析、EOF和SVD分解等方法讨论了山西省终霜冻的时空变化特征以及与北太平洋海温的关系。结果表明：山西省终霜冻时空分布不均匀,存在显著的年际和年代际变化特征。山西省终霜冻有提前的趋势。山西省终霜冻异常存在3年、5年、15年的周期;影响终霜冻的春季海温关键区是（20°S~35°N,110~160°E ）,山西省春霜冻与该关键区春季海温是显著的负相关关系,即春季海温关键区海温异常偏高（低）,山西省终霜冻偏早（晚）。     

Concurrent Optimal Design for the Mechanical Product Accuracy and its Mathematical Model

A new method,the concurrent optimal design for the mechanical product accuracy is addressed presented, this method is very suitable to a concurrent engineering context. Differing from the convensional tolerance design method, this method establishes a direct link between product working accuracy and machining precision of the parts. Therefore, in the product design phase,the optimal machining tolerances which satisfy the product working accuracy can be determined. Using this method, the design and manufacturing time and cost can be enormously reduced and product quality can be guaranteed.     

Research on Error Automatic Revised Method of LSI Wafer Honing Process

A new automatic revised method of wafer profile error which uses CCD measuring error,sets up machining data base and carries out a wedge structure for stepless compensating error in honing process is described.Using this technology,a high precision LSI wafers can be obtained.