抓好技术管理 发挥机械效率——余姚市积极推行联合收割机维修“例保制”

在联合收割机的迅速发展中,满“三包”期限的收割机逐年增多。如何及时抓好这些机车的维修保养(包括配件供应)工作,充分发挥收割机械效益,促进收获机械化,已引起各级农机管理部门的重视。但目前收割机的社会修理能力还很薄弱,农机手们特别担忧在双夏抢收中机车出了故障无人修理。为此,余姚市农机局在总结拖拉机维修“例保制”的基础上。

试论车垓的《丧服》服制诠释

作为两宋创发新义阶段的一大代表人物,车垓在《丧服》诠释上极具特色,所著《内外服制通释》一书极具亮点。作为一部专题考证体著作,《通释》虽然以考证与《丧服》制度有关的各种专题内容为主,但在服制“义例”诠释上,紧紧抓住“义例”概念关键词的词义,第一次对各种“义例”概念进行了详细的学术界定与推阐,第一次增设了“加服”这一类别。在著述方式上,车垓沿袭了汉代以来的治学传统,十分重视礼图的诠释方式,而且立名条目类目分明,涉及面较为全面。就其著述宗旨而言,车垓撰述《通释》的根本目的,在于为满足日常社会人们服丧之需求而提供便利,突显的是其礼俗规制的民间服制色彩,而不是为适应“三礼”学学术研究自身发展的需求。

论反垄断法中的相对经济强势地位

禁止滥用市场支配地位在世界各国的反垄断立法已毋庸置疑,但对于滥用相对经济强势地位的行为是否也应由反垄断法规制仍有疑虑。相对经济强势地位行为本质属性决定了对其滥用加以强制规定的必要性,本文通过考察世界各国反垄断立法对于滥用相对经济强势地位行为的规制,以期引起我国立法对于该行为的关注,并据此设计合理可行的法律规制制度。

Self Adjusting Feedforward Compensation Tracking Control for Proportional Valve Controlled Motor

Aim Aiming at the position tracking control for valve controlled motor electrohydraulic proportional servo systems mainly driving the static load torque, the tracking performance was studied in the presence of the variable gain and deadzone. Methods On the basis of conventional composite control with the deadzone compensation method, a comprehensive control approach with the deadzone and self adjusting feedforward compensation was proposed. Results Experimental results showed that the good tracking performance was achieved for the sinusoidal and constant velocity position tracking under a wide variations of load torque. Conclusion The position tracking accuracy for valve controlled motor electrohydraulic proportional servo systems has been solved by using the comprehensive control approach with the deadzone and self adjusting feedforward compensation.

Precision Point to Point Control of Proportional Valve Controlled Motor with a Time Varying Load

Aim In accordance with the positioning control for valve controlled motor electrohydraulic proportional servo systems driving the static load torque, the positioning performance was studied in the presence of the time? varying deadzone and gain. Methods The large positioning errors caused by the time varying deadzone were significantly reduced by using the dynamic compensation method for the deadzone; and the large overshoot caused by the time varying gain were dramatically reduced by using the three section intelligent control schemes. Results Experimental results demonstrated that the positioning performance of rapid response, high accuracy and smaller or even no overshoot was achieved under a wide variations of load torque. Conclusion The good positioning performance for valve controlled motor servo systems has been achieved in the presence of the time varying deadzone and gain.

Analysis of the Current situation of Syphilis in a Sexually Transmitted Disease Clinic

Objective： To analyze the current situation of syphilis in the sexually transmitted diseases （STDs） clinic, from January 1994 to December 2002 was studied. Methods： All syphilis patients were confirmed by history, physical examination, dark-field microscopy of samples taken from the chancre or satellite lymph nodes,or positive serological tests. Results： From 1994 to 2002, there were 2067 cases of early syphilis, accounting for 20.01% （2067/10330） of all STD cases. The annual proportion of syphilis cases among all STD cases from 1994 to 2002 was 0.57%, 0.53%, 3.54%, 16.20%, 31.29%, 27.88%, 25.63%, 17.11%, 10.48%, respectively. Of 2067 syphilis patients,49.64% （1026/2067） were male and 50.36% （1041/2067） were female. 44.75% （925/2067） of all cases presented with primary syphilis, 44.90% （928/2067） with secondary syphilis, 9.77% （202/2067） with latent syphilis （without any conspicuous clinical signs or symptoms）, and 0.58% （12/2067） with congenital syphilis. The 30-39 year old cohort accounted for the largest proportion, at 37.68% （779/2067） of all syphilis cases. The 20-29 year old cohort also accounted for a large proportion, at 37.20% （769/2067） of all cases,followed by the 40-49 year old cohort, at 17.95% （371/2067）. Syphilis was most prevalent among the unemployed,self-employed laborers, and office workers in decreasing order. The majority of cases were graduates of either primary school, high school, or college. Of all syphilis cases, 87.86% （1816/2067） were married, and 12.14%（251/2067, including children） were unmarried. 76.78% （1587/2067） of all cases were acquired through extramarital intercourse. 14.03% （290/2067） of cases were infected by their spouses. 0.58% （12/2067） of cases were due to vertical transmission. 8.61% （178） of cases were acquired through indirect contact. Conclusion： The proportion of syphilis infection among all STDs remained stable from 1994 to 1995,quickly and dramatically increased from 1996 to 1999,and then gradually tapered down from 2000 to 2002. The incidence of congenital syphilis infections increased throughout the study period.

Method for test case selection and execution of web application regression testing

In order to improve the efficiency of regression testing in web application,the control flow graph and the greedy algorithm are adopted.This paper considers a web page as a basic unit and introduces a test case selection method for web application regression testing based on the control flow graph.This method is safe enough to the test case selection.On the base of features of request sequence in web application,the minimization technique and the priority of test cases are taken into consideration in the process of execution of test cases in regression testing for web application.The improved greedy algorithm is also raised resulting in optimization of execution of test cases.The experiments indicate that the number of test cases which need to be retested is reduced,and the efficiency of execution of test cases is also improved.

Simulating Mechanism of Interaction Between Ports and Cities Based on System Dynamics: A Case of Dalian, China

Port-city system is a complex and integral system, and it can be simulated by system dynamic method, which is used to be employed to solve nonlinear problems. Based on the causality of the every element in the port-city system, the authors analyzed the feedback relation and logical relation among the system variables and system structure. A system-dynamic flow chart and correlation equations were put forward with VENSIM software, the quantitative relation was described, and the model was debugged. The development trend of the main influence factors in port-city system was simulated. By changing the influence degree of each related factor. It is found the parameters values of variables in the model, we studied that： 1） Foreign trade throughput of port play an important role in the development of export-oriented economy. 2） The development of primary industry and secondary industry affects most of the water transportation demand. With the constant increase of tertiary industry proportion in the industrial structure, the demand of national economy for water transportation decreases gradually. 3） Water transportation presents a kind of oversupply development situation, so port construction should properly slow down. 4） With the development of ports, its direct and indirect contribution to urban economy has been continuously increasing, but contribution rate will be continuously decreasing.

Metastatic liver cancer: A rare case

Hemangioperioltoma is a rare tumor especially when it rises in the peritoneal cavity. We present a case of a 60-year-old woman with an isolated recurrent hemangiopericytoma of the liver. The patient presented with a palpable right upper quadrant abdominal mass, which occurred 7 years after undergoing resection of a malignant hemangiopericytoma arising from the greater omentum. She had not followed up 6 mo after surgery. Various imaging studies showed a single large, well-capsulated liver tumor with central necrosis, accompanied by hypervascularity typical of a vascular tumor. Preoperative laboratory HBsAg and anti-HCV workup were both negative. Under the impression of recurrent malignant hemangiopericytoma, right trisegmentectomy was performed to completely resect the tumor. Pathological examination confirmed the diagnosis of recurrent hemangiopericytoma. Even though the incidence of the hemangiopericytoma is relatively low, malignant hemangiopericytoma has a tendency to recur frequently after a long-term disease-free interval. Also, the recurrent hemangiopericytoma is not easily detected early during follow-up until it becomes symptomatic because there are no specific tumor markers, and because of the diversity with regard to site of recurrence. The authors suggest that Positron Emission Tomogram （PET） may be a useful tool for the detection of recurrent hemangioperioltoma. We describe herein some characteristics and behaviors of malignant hemangiopericytoma, particularly after surgical resection.

Location of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus in Tissues of Natural Cases

[ Objective] The aim of this study was to provide a theoretical basis for the prevention and treatment of highly pathogenic porcine reproductive and respiratory syndrome （HP-PRRS）. [Method] Antigen location and histopathological observation in natural cases infected by highly pathogenic porcine reproductive and respiratory syndrome virus （HP-PRRSV） were analyzed by immunohistochemistry and H. E. staining. [Result] The virus antigen mainly existed in epithelial calls, and also a few in mecrophages, lymphocytes and brain nerve cells. [ Conclusion] The cell and tissue tropism of HP-PRRSV strain in natural cases is different from that of previous strains.

Improved control of intelligent excavator using proportional-integral-plus gain scheduling

Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to autonomously dig trenches without human intervention. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control, which is difficult for traditional control algorithm, e.g. PI/PID. A gain scheduling design, based on the true digital proportional-integral-plus (PIP) control methodology, was utilized to regulate the nonlinear joint dynamics. Simulation and initial field tests both demonstrated the feasibility and robustness of proposed technique to the uncertainties of parameters, time delay and load disturbances, with the excavator arm directed along specified trajectories in a smooth, fast and accurate manner. The tracking error magnitudes for oblique straight line and horizontal straight line are less than 20 mm and 50 mm, respectively, while the velocity reaches 9 m/min.

Comparison of two suspension control strategies for multi-axle heavy truck

Two simple and effective control strategies for a multi-axle heavy truck, modified skyhook damping (MSD) control and proportional-integration-derivative (PID) control, were implemented into functional virtual prototype (FVP) model and compared in terms of road friendliness and ride comfort. A four-axle heavy truck-road coupling system model was established using FVP technology and validated through a ride comfort test. Then appropriate passive air suspensions were chosen to replace the rear tandem suspensions of the original truck model for preliminary optimization. The mechanical properties and time lag of dampers were taken into account in simulations of MSD and PID semi-active dampers implemented using MATLAB/Simulink. Through co-simulations with Adams and MATLAB, the effects of semi-active MSD and PID control were analyzed and compared, and control parameters which afforded the best comprehensive performance for each control strategy were chosen. Simulation results indicate that compared with the passive air suspension truck, semi-active MSD control improves both ride comfort and road-friendliness markedly, with optimization ratios of RMS vertical acceleration and RMS tyre force ranging from 10.1% to 44.8%. However, semi-active PID control only reduces vertical vibration of the driver's seat by 11.1%, 11.1% and 10.9% on A, B and C level roads respectively. Both strategies are robust to the variation of road level.

Adenosquamous carcinoma arising within a retrorectal tailgut cyst: Report of a case

Retrorectal, developmental tail gut cysts, include dermoid cysts, rectal duplication cysts and retrorectal cyst-hamartomas. Retrorectal cyst-hamartomas （RCH） are derived from remnants of the tail gut, the most caudal part of the embryonic hincl gut, which normally involutes by the 8^th wk of embryonic development （3-8 mm stage）. They have specific radiological and histopathological features that distinguish them from other similar formations （dermoid cysts, enteric duplication cysts and teratomas）. We report a patient with adenosquamous carcinoma arising within RCH, who underwent complete resection of the cyst through anterior laparotomy, and reached complete （recurrencefree for 14 mo, so far） functional recovery. The cyst was incidentally discovered during hysterectomy 12 years ago. Diagnostic, therapeutic arid histopathological aspects of this rare case are discussed. The mentioned pedod between diagnosis and surgical treatment suggests that RCH, given enough time, can develop malignant degeneration, and should be resected at the time of diagnosis.

Interlayer interference mechanism of multi-seam drainage in a CBM well:An example from Zhucang syncline

Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.

Investigation into the flotation response of refractory molybdenum ore to depressant mixtures:A case study

In this paper, bulk flotation followed by separation was investigated to concentrate purified molybdenite product from Jinduicheng molybdenum ores(Shanxi province, China). The bench scale tests mainly focussed on separation of molybdenite from other sulfide minerals using the new type of depressants.The effect of each single depressant, including organic depressant-modified dextrin(MD), P-Nokes reagent(PN) and sodium trithiocarbonate(ST), and their mixtures on galena, chalcopyrite and other sulfide ores, was examined in turn by changing the concentrations used in cleaner flotation tests. Closed circuit experiments were carried out under the optimal condition and satisfying recovery and grade of molybdenite concentrate could be achieved(86.294% and 53.157%, respectively). A potential reagent regime was developed, with more environmental friendly and more economical advantages due to the introduction of modified dextrin.

Sliding Mode Predictive Control of Main Steam Pressure in Coal-fired Power Plant Boiler

Since the combustion system of coal-fired boiler in thermal power plant is characterized as time varying, strongly coupled, and nonlinear, it is hard to achieve a satisfactory performance by the conventional proportional integral derivative (PID) control scheme. For the characteristics of the main steam pressure in coal-fired power plant boiler, the sliding mode control system with Smith predictive structure is proposed to look for performance and robustness improvement. First, internal model control (IMC) and Smith predictor (SP) is used to deal with the time delay, and sliding mode controller (SMCr) is designed to overcome the model mismatch. Simulation results show the effectiveness of the proposed controller compared with conventional ones.

Distribution and mechanism of gently dipping fractures subjected to river incision: A case study from Nujiang River, China

Gently dipping fractures subjected to river incision are widely distributed on rock slopes.In this paper,a rock slope on the Nujiang River(China)is investigated to study the role of gently dipping fractures in the rock slopes evolution.Detailed field surveys indicate that gentle fractures are concentrated in four main zones.Moreover,the kinematics of the fracture system suggest that the genesis of these fractures can be synthesized into a progressive evolution model.This model indicates that the joints begin with the formation of an array of en echelon cracks that are subjected to continued crack elongation and shearing before ultimately approaching one another and interacting to form a complex joint system.Geomechanical analysis is performed to reveal the mechanisms of this genesis,and three main fracture patterns are identified based on the slope stress and are classified with respect to the slope evolution.Based on the detail field investigations and the evolutionary history of the river valley,we propose that intermittent incision by the river was the main factor contributing to the concentrated distribution of gently dipping joints.

Hybrid internal model control and proportional control of chaotic dynamical systems

A new chaos control method is proposed to take advantage of chaos or avoid it. The hybrid Internal Model Control and Proportional Control learning scheme are introduced. In order to gain the desired robust performance and ensure the system's stability, Adaptive Momentum Algorithms are also developed. Through properly designing the neural network plant model and neural network controller, the chaotic dynamical systems are controlled while the parameters of the BP neural network are modified. Taking the Lorenz chaotic system as example, the results show that chaotic dynamical systems can be stabilized at the desired orbits by this control strategy.

Predictive Functional Controller with a Similar Proportional Integral Optimal Regulator Structure:Comparison with Traditional Predic-tive Functional Controller and Application to Heavy Oil Coking Equipment

By extending the system's state variables,a novel predictive functional controller has been developed.The structure of this controller is similar to that of classical proportional integral(PI)optimal controller and in-cludes a control block that can perform a feed-forward control of future P-step set points.It considers both the state variables and the output errors in its cost function,which results in enhanced control performance compared with traditional state space predictive functional control(TSSPFC)methods that consider only the predictive output er-rors.The predictive functional controller(PFC)has been compared with TSSPFC in terms of tracking ability,dis-turbance rejection,and also based on its application to heavy oil coking equipment.The results obtained show the effectiveness of the controller.