Effect of Chlorophenoxyacetic Acid Growth-Regulator Sprays on Residues in Canned Apricots and Grapes

SUMMARY— A, gas-liquid chromatographic method coupled with an electron capture detector has been developed for analyzing chlorinated phenoxyacetic acid residues in canned fruits. The technique involves converting the acid to its methyl ester with diazomethane, chromatography on a 5% silicone grease SE-30 column at 210°C, and subsequent detection of the compound by an electron capture detector. As low as 0.02 ppm of the residue could be detected. The method is superior to the calorimetric method because parachlorophenoxyacetic acid (PCPA), 2,4-D, and 2,4,5-T can be separated and quantitatively determined simultaneously. However, separate standard curves are needed for each, because they differ in chlorine content and in sensitivity toward the electron capture detector. Levels of 2,4-D and 2,4,5-T residues in canned apricots, and of PCPA in canned grapes are reported.     

ILC for non-minimum phase system

In this paper we propose a design method of an iterative learning controller (ILC) for a non-minimum phase (NMP) system by model-matching theory. The ILC consists of two learning filters acting on both the previous input signal and the previous error signal. To design the learning filters, we convert the convergence condition of the ILC into the model-matching problem and get the stable and proper learning filter by solving the Nevanlinna's algorithm. To show the usefulness of the proposed algorithm, some design examples are included.     

Adaptive tracking system for a manoeuvring target using images with correlated noises

An effective scheme is proposed for estimating the state parameters of a manoeuvring target from a noisy image sequence, providing the sequence contains correlated noises and the trajectory of the target is disturbed by an unknown acceleration. For the correlated noises, a first-order difference operator is applied to the original image sequence to generate an artificial measurement sequence with only uncorrelated white noises. For the unknown acceleration, a Kalman filter augmented by a semi-Markov process and the bayesian theory is applied to form an adaptive filter. In the proposed tracking system, the filter first generates an artificial measurement at each sampling time from the observation. It then utilizes an artificial measurement sequence up to the current time instance to predict the a posteriori probability of each possible acceleration state. The weighted average of acceleration, where the weight is the a posteriori probability, is applied to derive the optimal estimates of the state parameters. Several computer simulations with external force applied at unknown times are performed to demonstrate the applicability and superiority of the proposed system.     

EFFECT OF CHLORINE TREATMENT ON CUT WATER CRESS AND ONION

Chlorine treatment was evaluated for cut vegetables to reduce microbial populations and improve keeping quality. Water cress and onion were selected because they are representative vegetables having high potential for processing into cut prepared products. Cut water cress had a high initial microbial contamintion of 10^7.5 cfu/g, while cut onion had only 10^1.7 cfu/g. The cut produce was treated by soaking in chlorine solutions of different concentrations at 25C for 1 min. Treatment with ≤100 ppm chlorine effectively reduced the microbial load of the produce without significant quality losses. High concentrations of chlorine resulted in greater microbial proliferation after 7 days, ascorbic acid destruction and significant color change in stored cut vegetables. The effectiveness of chlorine treatment was limited to short-term storage of precut vegetables, and did not provide extended shelf-life.     

考虑蓄满产流机制的流域分布式产汇流模型

洪水预报通常基于降雨径流模拟进行。以山坡水文学理论的蓄满产流机制为出发点,展开了对山区流域降雨径流模拟的研究,以此建立分布式三水源产汇流模型。首先,对研究流域进行离散化,以数字高程数据为基础提取流域的地形数字特征,使离散化坡面单元的数据同时完成自动匹配,实现参数的空间离散化,为模型的应用提供参数支撑。其次,采用水流连续方程和达西公式计算单元坡面内的产流量;以圣维南方程组简化的运动波方程为控制方程,推导出坡面流近似的偏微分方程,利用特征线法对每一单元坡面进行汇流计算。所建分布式水文模型可模拟从非饱和壤中流漫溢到坡面单元上形成饱和坡面流的暴雨径流过程。同时借由马斯京根-康吉法衔接了坡面离散单元水文子过程与主河道的汇合。最后选取美国古德温河流域典型的降雨过程进行次洪过程模拟,采用确定性系数、相关系数来评定模拟精度,结果表明其模拟精度达到了径流过程模拟和作业预报的精度要求。总体来说,所建分布式产汇流模型不但适用于单一坡面的径流分析,且能够应用于一般流域以进行降雨径流过程的模拟,在一定程度上可为防洪调度提供参考依据。     

Jerk-limited feedrate scheduling and optimization for five-axis machining using new piecewise linear programming approach

In this paper, a new computation method and an optimization algorithm are presented for feedrate scheduling of five-axis machining in compliance with both machine drive limits and process limits. Five-axis machine tool with its ability of controlling tool orientation to follow the sculptured surface contour has been widely used in modern manufacturing industry. Feedrate scheduling serving as a kernel of CNC control system plays a critical role to ensure the required machining accuracy and reliability for five-axis machining. Due to the nonlinear coupling effects of all involved drive axes and the saturation limit of servo motors, the feedrate scheduling for multi-axis machining has long been recognized and remains as a critical challenge for achieving five-axis machine tools' full capacity and advantage. To solve the nonlinearity nature of the five-axis feedrate scheduling problems, a relaxation mathematical process is presented for relaxing both the drive motors' physical limitations and the kinematic constraints of five-axis tool motions. Based on the primary optimization variable of feedrate, the presented method analytically linearizes the machining-related constraints, in terms of the machines' axis velocities, axis accelerations and axis jerks. The nonlinear multi-constrained feedrate scheduling problem is transformed into a manageable linear programming problem. An optimization algorithm is presented to find the optimal feedrate scheduling solution for the five-axis machining problems. Both computer implementation and laboratorial experiment testing by actual machine cutting were conducted and presented in this paper. The experiment results demonstrate that the proposed method can effectively generate efficient feedrate scheduling for five-axis machining with constraints of the machine tool physical constraints and limits. Compared with other existing numerical methods, the proposed method is able to find an accurate analytical solution for the nonlinear constrained five-axis feedrate scheduling problems without compromising the efficiency of the machining processes.     

1 100 kV GIS用断路器的设计

介绍了所研制的1 100 kV、50 kA GIS用断路器的技术规范、基本结构及合闸电阻的合理布置;利用商用Maxwell2D,3D软件及专用的程序,对断路器灭弧室的电场分布情况进行了分析,对合闸电阻的热容量进行了计算,并做了相关的试验验证,证明该型断路器的开断性能良好,其所配用的合闸电阻的热容量满足使用要求。     

创造过程的数学模型及其在绘图软件中的应用

本文从心理学出发,对新材料设计、文艺创作等创造过程作了分析,得出创造过程是由材料收集、组合、考察和选择构成。原则上,创造过程可以化为组合优化等数学问题。本文据此建立了创造过程的数学模型。作为一个例子,本文给出了一个可用于美术创作的具体算法。结合机器学习,该算法能根据操作者的审美观将粗略的草图逐渐变得完美,因此,只要有足够好的审美目光,就可以得到足够好的画面。本文提出的创造过程机制也可解释人的其他思维过程、生命的起源和进化等熵减过程     

Development of analysis model for geometric error in turning processes

A finite element model was established for analyzing the geometric errors in turning operations and a two-step analyzing process was proposed.In the first analyzing step,the cutting force and the cutting heat for the cutting conditions were obtained using the AdvantEdge.Also,the deformation of a workpiece was estimated in the second step using the ANSYS.The deformation was analyzed for a 150 mm-long workpiece at three different measuring points,such as 10,70 and 130 mm from a reference point,and the amounts...