Theoretical Analysis and Numerical Simulation of the Static and Dynamic Characteristics of Hydrostatic Guides Based on Progressive Mengen Flow Controller

The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with moderate load. The static and dynamic characteristics of the guide have been studied by using some theoretical, numerical and experimental approaches, and some methods and measures have been proposed to improve its performances. The hydrostatic guide based on progressive mengen（PM） flow controller is especially suitable for the heavy numerical control（NC） machine tools. However, few literatures about the research on the static and dynamic characteristics of the hydrostatic guides based on PM flow controller are reported. In this paper, the formulae are derived for analyzing the static and dynamic characteristics of hydrostatic guides with rectangle pockets and PM flow controller according to the theory of hydrostatic bearing. On the basis of the analysis of hydrostatic bearing with circular pocket, some equations are derived for solving the static pressure, volume pressure and squeezing pressure which influence the dynamic characteristics of hydrostatic guides with rectangle pocket. The function and the influencing factors of three pressures are clarified. The formulae of amplitude-frequency characteristics and dynamic stiffness of the hydrostatic guide system are derived. With the help of software MATLAB, programs are coded with C＋＋ language to simulate numerically the static and dynamic characteristics of the hydrostatic guide based on PM flow controller. The simulation results indicate that the sensitive oil volume between the outlet of the PM flow controller and the guide pocket has the greatest influence on the characteristics of the guide, and it should be reduced as small as possible when the field working condition is met. Choosing the oil with a greater viscosity is also helpful in improving the dynamic performance of hydrostatic guides. The research work has instructing significance for analyzing and designing the guide with PM flow controller.

4D-Flow MRI在肥厚型心肌病左室流出道血流评估中的价值探索

目的 探索四维血流(four-dimensional flow,4D-Flow)磁共振成像(magnetic resonance imaging,MRI)技术在左心室腔内应用的可行性。材料与方法 本研究为前瞻性、横断面研究,纳入2022年8月至2023年1月于我院接受心脏MRI检查的21例肥厚型心肌病患者,采用3.0 T MRI扫描仪进行二维血流(tow-dimensional flow,2D-Flow)及4D-Flow成像,收集患者一周内进行的超声心动图检查结果。采用组内相关系数(inter-class correlation coefficient,ICC)、变异系数(coefficients of variation,COV)及Bland-Altman分析比较2D-Flow、4D-Flow评估左室流出道峰值流速的可重复性及一致性,并通过Pearson相关性分析探究二者与超声心动图测量结果的关系。结果 2D-Flow和4D-Flow观察者内/观察者间的ICC分别为0.999/0.999和0.995/0.992,COV分别为0.5%/0.5%和2.4%/2.6%。4D-Flow与超声心动图的测量结果呈中度相关,相关系数r值为0.574(P=0.006),但一致性较差,ICC为0.375(P=0.013)。2D-Flow与4D-Flow和超声心动图间无显著的一致性及相关性。结论 4D-Flow技术能够可视化心腔内血流模式,对左室流出道峰值流速的测量具有高度可重复性,且与超声心动图的测量结果具有显著的一致性。

A Genetic Based Fuzzy Q-Learning Flow Controller for High-Speed Networks

For the congestion problems in high-speed networks, a genetic based fuzzy Q-learning flow controller is proposed. Because of the uncertainties and highly time-varying, it is not easy to accurately obtain the complete information for high-speed networks. In this case, the Q-learning, which is independent of mathematic model, and prior-knowledge, has good performance. The fuzzy inference is introduced in order to facilitate generalization in large state space, and the genetic operators are used to obtain the consequent parts of fuzzy rules. Simulation results show that the proposed controller can learn to take the best action to regulate source flow with the features of high throughput and low packet loss ratio, and can avoid the occurrence of congestion effectively.

针对无线控制环境的OpenFlow流表申请优化机制

在无线控制环境下,受限于控制通道的带宽和时延,OpenFlow交换机通过Packet-In消息申请流表的过程耗时较长,这个时段内交换机可能收到同一条流的大量后续报文,并分别产生与首包报文完全相同的Packet-In消息发往控制器,明显浪费网络资源。同时,针对每条流独立发送一个Packet-In报文的方式容易导致控制通道负载以小包为主、包头开销占比过大、网络资源利用率不高的问题。因此,针对无线控制条件下报文粒度Packet-In消息触发和离散化Packet-In消息发送机制存在的问题,提出了一种基于流粒度实现Packet-In消息触发和Packet-In消息聚合发送的方案,并通过仿真试验,验证了方案的效果。

Neuro-Fuzzy Based Interline Power Flow Controller for Real Time Power Flow Control in Multiline Power System

This article investigates the power quality enhancement in power system using one of the most famous series converter based FACTS controller like IPFC (Interline Power Flow Controller) in Power Injection Model (PIM). The parameters of PIM are derived with help of the Newton-Raphson power flow algorithm. In general, a sample test power system without FACTs devices has generated more reactive power, decreased real power, more harmonics, small power factor and poor dynamic performance under line and load variations. In order to improve the real power, compensating the reactive power, proficient power factor and excellent load voltage regulation in the sample test power system, an IPFC is designed. The D-Q technique is utilized here to derive the reference current of the converter and its D.C link capacitor voltage is regulated. Also, the reference voltage of the inverter is arrived by park transformation technique and its load voltage is controlled. Here, a sample 230 KV test power system is taken for study. Further as the conventional PI controllers are designed at one nominal operating point they are not competent to respond satisfactorily in dynamic operating conditions. This can be circumvented by a Fuzzy and Neural network based IPFC and its detailed Simulink model is developed using MATLAB and the overall performance analysis is carried out under different operating state of affairs.

基于 Moldflow 的汽车中控台框架翘曲变形分析及优化

以某汽车中控台框架为研究对象,测量试模样品发现其翘曲变形量超过了装配要求。通过Moldflow软件模拟了该塑件实际的注塑过程,翘曲变形量的模拟值与实测平均值的最大误差为5.98%,发现该塑件翘曲变形的主要因素为冷却不均和收缩不均。本文在原物料中添加质量分数为25%的玻璃纤维以及优化工艺参数后,翘曲变形量的模拟值与初始方案相比降低了86.22%。试模验证表明,优化后的翘曲变形量模拟值与实测平均值的最大误差为4.35%,证明了Moldflow软件模拟分析的准确性。试模后各检测点的最大翘曲变形量降到了1.6 mm以下,较优化之前降低了80%以上,为类似大型复杂注塑件的翘曲变形分析及优化提供了思路。

Binary ABR flow control over ATM networks with uncertainty using discrete-time variable structure controller

A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.

Design of Poiseuille Flow Controllers Using the Method of Inequalities

This paper investigates the use of the method of inequalities （MoI） to design output-feedback compensators for the problem of the control of instabilities in a laminar plane Poiseuille flow. In common with many flows, the dynamics of streamwise vortices in plane Poiseuille flow are very non-normal. Consequently, small perturbations grow rapidly with a large transient that may trigger nonlinearities and lead to turbulence even though such perturbations would, in a linear flow model, eventually decay. Such a system can be described as a conditionally linear system. The sensitivity is measured using the maximum transient energy growth, which is widely used in the fluid dynamics community. The paper considers two approaches. In the first approach, the MoI is used to design low-order proportional and proportional-integral （PI） controllers. In the second one, the MoI is combined with McFarlane and Glover＇s H∞ loop-shaping design procedure in a mixed-optimization approach.

基于Flow Simulation的某发动机涡轮压气机流场与效率分析

涡轮机内部流场对涡轮增压器的性能和效率有着重要影响,采用SolidWorks Flow Simulation模块对某发动机涡轮压气机侧流场和压气效率分析。在六种不同空气体积流量工况下,体积流量为0.29时,压气机效率最高,达到80%左右。模型的建模和流体分析均在SolidWorks环境下,分析效率高,为涡轮增压器设计和优化提供了支撑。

Model Predictive Control Strategy of Multi-Port Interline DC Power Flow Controller

There are issues with flexible DC transmission system such as a lack of control freedom over power flow.In order to tackle these issues,a DC power flow controller(DCPFC)is incorporated into a multi-terminal,flexible DC power grid.In recent years,a multi-port DC power flow controller based on a modular multi-level converter has become a focal point of research due to its simple structure and robust scalability.This work proposes a model predictive control(MPC)strategy for multi-port interline DC power flow controllers in order to improve their steady-state dynamic performance.Initially,the mathematical model of a multi-terminal DC power grid with a multi-port interline DC power flow controller is developed,and the relationship between each regulated variable and control variable is determined;The power flow controller is then discretized,and the cost function and weight factor are built with numerous control objectives.Sub module sorting method and nearest level approximation modulation regulate the power flow controller;Lastly,theMATLAB/Simulink simulation platformis used to verify the correctness of the establishedmathematicalmodel and the control performance of the suggestedMPC strategy.Finally,it is demonstrated that the control strategy possesses the benefits of robust dynamic performance,multiobjective control,and a simple structure.

A new method based on two freedom-degree PD-P flow rate controller for congestion control in computer networks

The rate-based feedback PD-P controller of two freedom-degrees is proposed for the congestion control in computer networks to improve the abilities against disturbance. Moreover, the Dahlin algorithm is used for setting the controller to overcome the adverse effect caused by the propagation delay effectively. The research results show that the proposed scheme not only can make sources respond to the changes of network state more quickly, but also has a good robustness against estimated error of the delay. Then the packet queue level in buffer will be stabilized on the set-point quickly, and the delay and its jitter of the packet queuing will also become smaller. Besides, the flexible bandwidth allotment can be obtained by setting the weight coefficients.

Autonomous Multi-Factor Energy Flows Controller (AmEFC): Enhancing Renewable Energy Management with Intelligent Control Systems Integration

The transition to sustainable energy systems is one of the defining challenges of our time, necessitating innovations in how we generate, distribute, and manage electrical power. Micro-grids, as localized energy hubs, have emerged as a promising solution to integrate renewable energy sources, ensure energy security, and improve system resilience. The Autonomous multi-factor Energy Flow Controller (AmEFC) introduced in this paper addresses this need by offering a scalable, adaptable, and resilient framework for energy management within an on-grid micro-grid context. The urgency for such a system is predicated on the increasing volatility and unpredictability in energy landscapes, including fluctuating renewable outputs and changing load demands. To tackle these challenges, the AmEFC prototype incorporates a novel hierarchical control structure that leverages Renewable Energy Sources (RES), such as photovoltaic systems, wind turbines, and hydro pumps, alongside a sophisticated Battery Management System (BMS). Its prime objective is to maintain an uninterrupted power supply to critical loads, efficiently balance energy surplus through hydraulic storage, and ensure robust interaction with the main grid. A comprehensive Simulink model is developed to validate the functionality of the AmEFC, simulating real-world conditions and dynamic interactions among the components. The model assesses the system’s reliability in consistently powering critical loads and its efficacy in managing surplus energy. The inclusion of advanced predictive algorithms enables the AmEFC to anticipate energy production and consumption trends, integrating weather forecasting and inter-controller communication to optimize energy flow within and across micro-grids. This study’s significance lies in its potential to facilitate the seamless incorporation of RES into existing power systems, thus propelling the energy sector towards a more sustainable, autonomous, and resilient future. The results underscore the potential of such a system to revolutionize energy management practices and highlight the importance of smart controller systems in the era of smart grids.

袋型阻尼密封动力学特性双控制体Bulk Flow模型

为快速准确预测袋型阻尼密封泄漏特性和动力学特性,针对传统单控制体Bulk Flow模型预测精度低、无法预测交叉动力系数的问题,提出了袋型阻尼密封双控制体Bulk Flow模型和动力学特性数值预测方法,并开发了计算程序。首先,依据边界层理论,将袋型密封腔室划分为两个控制体,推导了控制体的连续性、周向动量和能量方程,引入Swamee-Jain和Takahashi方程,计算流体-壁面间和流体-流体间的周向黏性摩擦力;其次,采用牛顿-拉夫森算法和摄动分析法分别求解0阶和1阶控制方程,获得各刚度、阻尼动力特性系数;然后,通过与袋型阻尼密封泄漏量和动力特性系数的实验值、单控制体Bulk Flow模型和非定常计算流体动力学(CFD)数值结果进行比较,验证了模型和方法的准确性和可靠性;最后,研究了转子转速(10 000、15 000、20 000 r/min)和预旋比(0.067、0.724、0.997)对袋型阻尼密封动力学特性的影响。结果表明:所发展的模型和方法具有计算速度快、预测精度高(泄漏量预测误差小于6%,动力特性系数预测误差小于38%)的优点;转子转速和进口预旋的增大均会导致袋型阻尼密封有效阻尼显著减小,穿越频率显著增大,易诱发轴系失稳。

子宫动脉血流频谱联合e-Flow胎盘血流在妊娠期高血压103例中的应用价值

目的研究e-Flow胎盘血流结合子宫动脉血流频谱在妊娠期高血压疾病中的应用价值。方法回顾性分析2021年5月至2023年2月邯郸市中心医院103例纳入时无高血压,后随访出现妊娠期高血压孕妇作为妊娠期高血压组,选择产检正常且无高血压的110例正常孕妇作为健康组。收集妊娠期高血压组未出现高血压时以及健康组的子宫动脉血流频谱和e-Flow胎盘血流数据,获得子宫动脉阻力指数、搏动指数、收缩期峰值与舒张末期流速比值(S/D),舒张早期切迹与胎盘血管图像;采用受试者操作特征曲线(ROC曲线)分析各指标单独以及联合预测妊娠期高血压的价值。结果妊娠期高血压组搏动指数、阻力指数及S/D值高于健康组(P<0.05)。子宫动脉舒张早期切迹存在率方面,妊娠期高血压组相较于健康组更高(P<0.05)。妊娠期高血压组三级绒毛动脉计数少于健康组[(2.34±0.48)个比(4.36±0.53)个,P<0.05]。ROC曲线显示,搏动指数、阻力指数、S/D、三级绒毛动脉计数联合检查对妊娠期高血压的灵敏度、特异度为74.80%、93.30%,预测价值高于单独检查。结论子宫动脉血流频谱联合e-Flow胎盘血流能有效预测妊娠期高血压发生,可作为临床早期疾病评估的有效检查方式。

iFlow彩色血流编码成像技术在下肢动脉硬化闭塞症诊断中的应用价值

目的研究iFlow彩色血流编码成像技术在下肢动脉硬化闭塞症(LEASO)诊断中的应用价值。方法选择2022年3月至2023年10月期间确诊的106例LEASO患者作为本研究的LEASO组,以一般资料与LEASO组匹配且无动脉病变的80例志愿者作为对照组。两组受试者均进行数字减影血管造影(DSA)并采用iFlow彩色血流编码成像技术检测股骨头区域和踝关节区域达峰时间(TTP)、计算踝关节区域与股骨头区域TTP的差值,测量踝肱指数(ABI)。结果两组研究对象年龄、性别、体质量指数、吸烟史、高血压病史、糖尿病史、冠心病史、股骨头区域TTP的比较,差异无统计学意义(P>0.05);LEASO组踝关节区域TTP及TTP差值均高于对照组,差异有统计学意义(P<0.05);LEASO组中不同Rutherford分类患者股骨头区域TTP的比较以及左侧病变患者与右侧病变患者股骨头区域TTP、踝关节区域TTP、TTP差值的比较,差异无统计学意义(P>0.05),Rutherford分类越高,踝关节区域TTP及TTP差值越低(P<0.05);经Pearson检验,LEASO患者的踝关节区域TTP、TTP差值与ABI呈负相关(P<0.05);经受试者工作特征(ROC)曲线分析,踝关节区域TTP、TTP差值对LEASO具有诊断效能;经Delong检验,TTP差值诊断的ROC曲线下面积高于踝关节区域TTP(P<0.05)。结论iFlow彩色血流编码成像技术测定踝关节区TTP及TTP差值是诊断LEASO的量化指标。

Investigation of Real Power Flow Control of AI Based MC-UPFC in FACTS Controllers

The power consumption is rapidly increased due to ASD(Adjustable Speed Drives)and automation in industries and large consumption of electricity in domestic regions increased the concern of the power quality.The quality of the power received in the distribution system is altered because of the losses in the transmission system.The losses in the transmission system are mitigated using the FACTS(Flexible AC Transmission System)controller,among these controllers UPFC(Unified Power Flow Controller)plays a vital role in controlling the shunt and series reactive powers in the bus of the power system.The conventional topology of the UPFC consists of AC-DC converter and energy stored in the DC link and DC-AC converter injected a voltage in series to the bus which is to be controlled.Whereas a new topology based on matrix converter can replace the dual converters and perform the required task.The construction of 2-bus,7-bus and IEEE-14-bus power system is designed and modeled.MC-UPFC(Matrix Converter Based Unified Power Flow Controller)is designed and constructed.The MC-UPFC is the rich topology in the FACTS which is capable of controlling both the transmission parameters simultaneously with the switching technique of direct power control by the smooth sliding control which gives less ripple in the injecting control parameters such as control voltage(Vc)and voltage angle(α).By implementing MC-UPFC the real and reactive power can be controlled simultaneously and independently.The control techniques were designed based on the PID(Proportional Integral Derivative)with sliding surface power control,FLC(Fuzzy Logic Controller)and ANN(Artificial Neural Network)and the performances of Vc andαof the controllers are investigated.Hence the sliding surface and relevant control switching state of the MC can be controlled by the FLC which gives the robust and autonomous decision made in the selection of the appropriate switching state for the effective real power control in the power system.The work has been carried out in the MATLAB Simulink simulator which gives the finest controlling features and simple design procedures and monitoring of the output.

基于Flow-3D的桩林坝不同布置形式对坝基的冲刷侵蚀

桩林坝是一种以桩为基础的竖向格子坝,既有良好的受力条件,又相对节约材料,同时拥有“拦粗排细”的功效,现有桩林坝的研究,多在冲击荷载、拦截固源和调控泥石流性能等方面构建不同布置形式的桩林坝模型。以杨家沟为例,通过野外现场踏勘和数值仿真计算,基于Flow-3D软件开展数值模拟研究,建立不同布置形式(单排桩、双排桩、桩间距、排间距)的桩林坝模型,探讨不同影响因素下桩林坝坝基冲刷侵蚀规律。结果表明:桩林坝的整体设计中桩林不宜过密,桩间距和排间距以2.5 m为宜;单排桩的稳定性较弱,在泥石流冲击下极易发生剪切破坏,且对上游的“固源”作用远不如多排桩,但单排桩的冲刷深度及侵蚀规模均小于多排桩。研究成果对桩林坝的布置形式及冲刷机制提供数据支撑,并为震后泥石流防治工程设计提供参考。

肝硬化患者4D flow MRI血流动力学参数与中医证型的相关性研究

目的探讨肝硬化患者4D flow MRI血流动力学参数与中医证型的相关性。方法将118例肝硬化患者依据中医辨证分为肝气郁结证、湿热蕴结证、肝肾阴虚证、脾肾阳虚证、瘀血阻络证5个证型,所有患者均行门静脉4D flow MRI检查,统计不同证型肝硬化患者分布情况,观察门静脉系统(门静脉主干、脾静脉、肠系膜上静脉)的血流动力学参数,包括血流量、流速、壁剪切力等,比较不同证型患者门静脉血流动力学参数差异。结果肝硬化代偿期以肝气郁结证、湿热蕴结证为主,肝硬化失代偿期以脾肾阳虚、瘀血络阻证为主;A级以肝气郁结证、湿热蕴结证为主,B、C级以瘀血络阻证为主。瘀血络阻证肝硬化患者门静脉主干及脾静脉血流量明显高于肝气郁结证、湿热蕴结证患者(P<0.05);脾肾阳虚证门静脉主干血流量明显高于肝气郁结证肝硬化患者(P<0.05);瘀血络阻证肝硬化患者门静脉主干流速及剪切力较肝气郁结证和湿热蕴结证低。结论肝硬化患者中医辨证分型与门静脉血流动力学参数具有一定相关性,4D flow MRI可为肝硬化的中医辨证提供血流动力学参考。

Beautiful Flow Plus与FUjiⅨ玻璃离子水门汀在牙颈部楔状缺损治疗中的应用效果比较

目的:比较Beautiful Flow Plus与FUjiⅨ玻璃离子水门汀在牙颈部楔状缺损治疗中的应用效果。方法:选取牙颈部楔状缺损患者198例(567颗患牙),根据修复时充填材料不同将患者分为观察组101例289颗患牙(Beautiful Flow Plus修复治疗)和对照组97例278颗患牙(FUjiⅨ玻璃离子水门汀修复治疗)。比较两组患者治疗后1、2年填充体状态及修复成功率。比较两组患者治疗后2年咀嚼功能、美观度评分。记录治疗期间和治疗后2年内患者不良事件发生情况。结果:两组治疗后1年患牙填充体状态良好率及修复成功率比较差异无统计学意义(均P>0.05)。治疗后2年,观察组色泽协调性良好及无边缘着色的牙齿比例高于对照组(均P<0.05)。两组其余充填体状态良好率及修复成功率比较差异无统计学意义(均P>0.05)。治疗后2年,两组干燥咀嚼物X50数值较治疗前降低,且观察组低于对照组(均P<0.05)。治疗后2年,两组患者和医生美观度评分较治疗前升高,且观察组高于对照组(均P<0.05)。在治疗期间和治疗后2年内,两组不良事件总发生率比较差异无统计学意义(P<0.05)。结论:与FUjiⅨ玻璃离子水门汀比较,Beautiful Flow Plus在牙颈部楔状缺损治疗中具有较好的远期美学效果,且有助于改善患者咀嚼功能。

Experimental analysis on adjusting performance of vapor-liquid two-phase flow controller

The vapor-liquid self-adjusting controller is an innovative automatic regulating valve.In order to ensure adjusted objects run safely and economically,the controller automatically adjusts the liquid flux to keep liquid level at a required level according to physical properties of vapor-liquid two-phase fluid.The adjusting mechanics,the controller’s performance and influencing factors of its stability have been analyzed in this paper.The theoretical analysis and successful applications have demonstrated this controller can keep the liquid level steady with good performance.The actual application in industry has shown that the controller can satisfactorily meet the requirement of industrial production and has wide application areas.