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Search Results: 1 - 10 of 31234 matches for " continuously variable capacity control "
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基于逐级递推回流控制的压缩机负荷连续调节系统研究
王瑶,张进杰,周超,刘雯华
- , 2018, DOI: 10.13543/j.bhxbzr.2018.03.013
Abstract: 针对石化工艺生产中产量变化时压缩机无法连续调节负荷造成的能量浪费问题,设计了一种基于可编程逻辑控制器(PLC)控制的压缩机负荷连续调节电液系统,主要由S7-300 PLC、电液控制阀、液压驱动器和液压动力单元等组成。系统采用局部行程压开进气阀的控制原理,实现了压缩机负荷在0~100%范围的全量程连续调节,并根据实际工艺流程需求设计了逐级递推式的PID控制回路。该系统能够根据后端工艺的需求自动调节压缩机负荷,保证了工艺量的稳定,同时避免了原打回流方式造成的能量浪费。
Abstract:In view of the problem of energy waste caused by the failure of a compressor to continuously adjust its output during a change in a petrochemical process, a continuous regulating electro-hydraulic system based on a programmable logic controller (PLC) has been designed. The main components of the system comprise a S7-300 PLC, electro-hydraulic control valves, hydraulic drivers and a hydraulic power unit. The system adopts releasing the suction valve during a partial stroke as its control principle, and continuous regulation over the range 0-100% can be achieved. In addition, a stage-by-stage recursive PID control method was designed according to the actual process demand. The system can automatically adjust the compressor load according to the demand of the back-end process, thus ensuring the stability of the process quantity, and avoiding any energy waste caused by the original backflow.
Efficiency Evaluation of Continuously Variable Transmissions Including a Planetary Gear Train  [PDF]
A. A?tTaleb, A. Chaaba, M. Sallaou
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.52015
Abstract:

With their advantages, continuously variable transmissions have gained more popularity in the last decade by their use in mechanical transmission systems. The present paper aims to analysis the efficiency of the transmission based on the mechanical efficiency of the planetary gear train integrated in such transmission. In this analysis, we consider the mechanical efficiency of the transmission has been determined considering how the efficiency of the CVT members changes as a function of the operating conditions. The efficiency of the planetary gear train as a function of the configuration, speeds in his three input/output shafts, and also with respect to the power flow type. Results are compared with those obtained from other methods performance evaluation of the transmission, available in the literature.

CVT插电式混合动力汽车经济性控制策略
周云山,贾杰锋,李航洋,,
- , 2016,
Abstract: 针对搭载CVT的插电式混合动力轿车,设计了一种基于动力源外特性曲线和驾驶员踏板操作信号的需求转矩解析方法,在此基础上提出驱动和制动工况下基于瞬时经济性成本最低的能量管理策略,该策略以需求转矩、车速和电池SOC为状态变量,以发动机节气门开度、电机转矩、CVT速比为控制变量.进一步研究了电量消耗阶段有无发动机单独驱动模式对整车能耗经济性的影响.通过自行搭建的前向模型进行仿真,结果表明,电量消耗阶段无发动机单独驱动模式的控制策略具有更强的综合性经济优势.
An analytic method of demand torque was designed for a plug in hybrid electric vehicle equipped with continuously variable transmission (CVT), which is based on the external characteristic curve of the power source and the signal from the driver's operation. Then, energy management strategy minimizing instantaneous economic cost under drive and brake condition was proposed, with the demand torque, vehicle speed and state of charge (SOC) of battery as the state variables, and the throttle opening of the engine, motor torque and speed ratio of CVT as the control variables. Further research was carried out on the influence of whether the engine driving alone is allowed at the charge depleting stage on economic cost. Through simulation with self built forward model, the results have shown that the strategy that does not allow engine driving alone at the charge depleting stage is better in comprehensive economy.
液压机械无级变速器换挡控制策略研究
A Shifting Control Strategy for Hydro-mechanical Continuously Variable Transmission

朱镇,高翔,潘道远,曹磊磊,韩顺,朱彧
- , 2017,
Abstract: 针对一种液压机械无级变速器建立换挡仿真模型。以输出轴的速度降幅度、动载荷系数、最大冲击度和换挡时间作为换挡品质评价指标,以发动机转速、负载转矩、主油路压力和调速阀流量作为影响因素。建立L9(34)正交表,采用极差法确定影响因素各水平的主次和优劣,并预测最佳方案。使用统计学方法分析试验数据,验证仿真结果的正确性。结果表明:采用较低的发动机转速,较小的负载转矩,较小的主油路压力,以及较大的调速阀流量可有效提升变速器器换挡品质。
We build the shifting simulation model of a hydro-mechanical continuously variable transmission (HMCVT). The speed drop amplitude, dynamic load coefficient, maximum degree of shock of output shaft and shifting time are regarded as the shifting quality evaluation indices to establish the engine speed, load torque, pressure of main circuit and flow of speed control valves as factors of influence. An L9(34) orthogonal table is used to determine the primary-secondary and optimal-worst levels of influence factors and to predict the optimum scheme. The simulation datas are calculated by using a statistical method in order to verify the reliability of the simulation results, which show that the shifting quality is improved by the lower engine speed, smaller load torque, lower pressure of main circuit, and the larger flow of speed control valves
Improving Organizational Performance by a Quality Control Circle: A Case of Medication Improvement Team at a Hospital in Taiwan
Su-Chuan Liu,Hsin-Hung Wu,Hsuan-Kai Chen
Information Technology Journal , 2010,
Abstract: n QCC.
基于滑移率反馈控制无级变速器夹紧力优化策略
Optimal Strategy of Clamping Force for Continuously Variable Transmission Based on Slip Ratio Feedback Control

韩玲, 安颖, 董博, 田丽媛, SOHEL Anwar
HAN Ling
, AN Ying, DONG Bo, TIAN Liyuan, SOHEL Anwar

- , 2016, DOI: 10.3969/j.issn.0258-2724.2016.06.005
Abstract: 为了将汽车燃油消耗率降至最低,使发动机稳定在最佳转速区域,对无级变速器(continuously variable transmission,CVT)传统夹紧力控制策略进行了优化.在CVT内部现有传感器装置的基础上,根据滑移率反馈控制方法的总体结构,建立了具有非线性的滑移率动态模型方程,并在设计滑移率反馈控制器过程中,采用分级内、外双环的控制方法,解决夹紧力与速比之间的耦合问题.通过台架试验及CVT整车测试,验证了优化后的夹紧力控制策略的有效性.研究结果表明:在CVT整车百公里急加速、紧急制动以及综合工况下,滑移率反馈控制令整车动力匹配能力优于传统夹紧力控制;夹紧力在满足不发生带轮打滑及使用要求前提下,夹紧力可降低10%,燃油效率总量可提高1%.
: In order to decrease vehicles' fuel consumption rate to the lowest and stabilize the engine running in an optimal rotary speed range, an optimization was made for the traditional clamping force control strategy of the continuously variable transmission (CVT). According to the general structure of the slip ratio feedback control method, a slip ratio dynamic model with nonlinear equations was set up based on measurements from the existing sensor devices inside CVT. For design of the slip ratio feedback controllers, the tight coupling problem between clamping force and speed ratio are solved using a separate inner-and outer-loop control scheme. In addition, bed tests and real tests were conducted to verify the effectiveness of the optimized control strategy for clamping force. The results show that the power matching ability of the CVT vehicle equipped with slip ratio feedback control is superior to that with the traditional clamping force control in all of the 0-100 km/h acceleration test, emergency braking, and comprehensive conditions. Using the slip ratio feedback control, the clamping force can decrease about 10% with non-slip and other application requirements satisfied, and the total fuel efficiency of CVT vehicles can increase 1%
Robust Capacity Control in Revenue Management: A Literature Review  [PDF]
Zheyu Jiang
Open Journal of Business and Management (OJBM) , 2018, DOI: 10.4236/ojbm.2018.62037
Abstract:
Revenue management is one of the classical topics in operations research. In recent 10 years, robust optimization methodology motivated a rapid growing amount of literature on robust revenue management. This stream of research does not rely on strict prior assumptions on distribution of random demand in classical revenue management theory but is capable to maintain tractable and to derive interesting structural properties of optimal solution. In this paper, we first briefly introduce theoretical basis of revenue management and then provide detailed review of literature on robust revenue management. Then potential directions of future research are identified.
Variable Gear Ratio Control Using Vehicle Body Slip Angle  [PDF]
Takahiko Yoshino, Hiromichi Nozaki
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.68046
Abstract:

Vehicles with variable steering characteristics have long been studied and compared with those having typical fixed gear ratio steering, and the variable gear ratio properties are reported to have improved maneuverability and stability in high-speed lane changes and on slippery low-friction road surfaces. However, it is not clear how gear ratios should be set for individual vehicle characteristics. Therefore, the present study has investigated a variable steering gear system using body slip angle feedback for the purpose of improved maneuverability and stability in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range. The results of a driving simulator experiment show that the steering effect improves and maneuverability and stability increase in the critical cornering range and upwards, in excess of the critical limit, and into the countersteer range by applying linear-variable control to the steering ratio from a body slip angle of 5?. This result is seen both in double lane changes, such as in hazard avoidance, and in J-turns with long drifting. Moreover, it shows an improvement in drift controllability through prompt countersteering. Overall, the present system can enhance the driver’s hazard avoidance capability.

Cognitive Congestion Control for Data Portals with Variable Link Capacity  [PDF]
Ershad Sharifahmadian, Shahram Latifi
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2012, DOI: 10.4236/ijcns.2012.58058
Abstract: Network congestion, one of the challenging tasks in communication networks, leads to queuing delays, packet loss, or the blocking of new connections. In this study, a data portal is considered as an application-based network, and a cognitive method is proposed to deal with congestion in this kind of network. Unlike previous methods for congestion control, the proposed method is an effective approach for congestion control when the link capacity and information inquiries are unknown or variable. Using sufficient training samples and the current value of the network parameters, available bandwidth is adjusted to distribute the bandwidth among the active flows. The proposed cognitive method was tested under such situations as unexpected variations in link capacity and oscillatory behavior of the bandwidth. Based on simulation results, the proposed method is capable of adjusting the available bandwidth by tuning the queue length, and provides a stable queue in the network.
Analysis of roll stack deflection in a hot strip mill
Sikdar, Sudipta;John, Shylu;Pandit, Ashwin;Dasu, Raju;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2007, DOI: 10.1590/S1678-58782007000300008
Abstract: predictive models are required to provide the bending set point for bending for the flatness control devices at rolling stands of finishing mill of hot strip mill (hsm). a simple model for roll stack deflection at the finishing mill has been illustrated where a modified misaka?s equation has been used to obtain mean flow-stress. investigation has been performed to understand the effect of width of roll on roll stack deflection. the bending on the deflection has been found to have a positive effect to reduce the amount of the stack deflection. the results from the sensitivity analysis of the roll width on roll deflection are also described.
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