The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimen...The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimental setup has been designed and built to control the cylinder position using a programmable logic controller to provide the appropriate motor speed from the AC drive to control the velocity of the hydraulic actuator;the induction motor is driven by an AC drive using a tune proportional-integral-variable frequency drive(TPI-VFD)space vector modulation(SVM)hybrid technology.Theoretically,it was analyzed and simulated by MATLAB,which showed that the starting current was reduced by 81%compared to the traditional system.Also,the settling time of the system decreased to 0.35 s to reach a steady state with a minimum error of 0.03 and an overshoot of 0.3%.On the other hand,the experimental results of the EHSS show that the three-phase induction motor with a closed-loop speed control AC drive with a programmable logic controller PLC based system is the best case for determining the appropriate operating speed.The optimum speed,frequency,and voltage were 1325.3 rpm,46.6 Hz,and 354.16 V.In addition,enhancement is achieved in closed-loop VFD-PLC,where at 6.5 bar pressure and 3.4 LPM flow,the volumetric efficiency after the pump improves to 98.6%while it reaches 96.3%before the cylinder at a flow rate of 3.32 LPM.Finally,in the closed-loop VFD-PLC in the expansion stroke,the rated electrical power consumption of the three-phase IM decreased to 532 W at the speed of 1325.3 rpm,resulting in energy savings of 20.6%.展开更多
针对电力语音通信系统架构老化、协议异构、运维割裂等问题,提出基于IP多媒体子系统(IP Multimedia Subsystem,IMS)的语音接入网融合改造方案,构建统一信令控制、媒体处理与服务质量(Quality of Service,QoS)保障体系。设计端到端架构,...针对电力语音通信系统架构老化、协议异构、运维割裂等问题,提出基于IP多媒体子系统(IP Multimedia Subsystem,IMS)的语音接入网融合改造方案,构建统一信令控制、媒体处理与服务质量(Quality of Service,QoS)保障体系。设计端到端架构,完成多协议信令映射、安全与QoS协同机制,实现控制面集中化与接口能力开放。通过构建实验环境开展高并发性能测试,验证系统在会话控制、媒体传输与资源调度方面的提升效果,结果表明改造方案具备工程可行性与部署价值。展开更多
电信运营商拥有大规模的语音用户数,但是随着OTT(Over The Top)业务的广泛使用,给运营商基础语音业务受到了冲击,每用户通话时长(Minutes Of Usage,MOU)持续降低且收入逐年下降。5G增强通话是基于5G的新一代通话产品,提供超高清、智能...电信运营商拥有大规模的语音用户数,但是随着OTT(Over The Top)业务的广泛使用,给运营商基础语音业务受到了冲击,每用户通话时长(Minutes Of Usage,MOU)持续降低且收入逐年下降。5G增强通话是基于5G的新一代通话产品,提供超高清、智能化、全交互三大能力,以期增加用户黏性并为基础通话业务带来新的潜在增长空间。介绍5G增强通话的业务类型和发展现状,然后从建设原则、网络架构、数据通道信令功能(Data Channel Signaling Function,DCSF)网元建设方案、资源池建设方案、网络安全及可靠性等方面探讨5G增强通话控制面网元DCSF的建设实施方案。展开更多
This paper presents an efficient method of equivalient workstations for modeling and analysis of multistage transfer lines with unreliable machines and finites buffers. The deterministic processing times for discrete ...This paper presents an efficient method of equivalient workstations for modeling and analysis of multistage transfer lines with unreliable machines and finites buffers. The deterministic processing times for discrete parts and random failuse and repair times for machines are assumed. These buffers lead to blockage and starvation in operation due to limited storage capacities and make the problem of modelling and analysis very difficult to treat because they have large state spaces and cannot be decomposed exactly. A single buffer between two reliable workstations is analysed first. Then an equivalent workstation without starvation and blockage is constructed. Thereafter connecting all the equivalent workstations in series we get the equivalent transfer line. A set of preformance measures such as the production rates, efficiencies and average inventory levels are derived in explicit analytical expressions. Finally two numerical examples are given for comparing these calculated results with those of S. B. Gershwin (1987) and C. R. Glasseye & Y. Hong (1993) and illustrating the application of the method in engineering design directly.展开更多
文摘The current study aims to improve the performance of the electrohydraulic servo system(EHSS)by increasing the volumetric efficiency of the pump and reducing electrical power consumption to a minimum value.An experimental setup has been designed and built to control the cylinder position using a programmable logic controller to provide the appropriate motor speed from the AC drive to control the velocity of the hydraulic actuator;the induction motor is driven by an AC drive using a tune proportional-integral-variable frequency drive(TPI-VFD)space vector modulation(SVM)hybrid technology.Theoretically,it was analyzed and simulated by MATLAB,which showed that the starting current was reduced by 81%compared to the traditional system.Also,the settling time of the system decreased to 0.35 s to reach a steady state with a minimum error of 0.03 and an overshoot of 0.3%.On the other hand,the experimental results of the EHSS show that the three-phase induction motor with a closed-loop speed control AC drive with a programmable logic controller PLC based system is the best case for determining the appropriate operating speed.The optimum speed,frequency,and voltage were 1325.3 rpm,46.6 Hz,and 354.16 V.In addition,enhancement is achieved in closed-loop VFD-PLC,where at 6.5 bar pressure and 3.4 LPM flow,the volumetric efficiency after the pump improves to 98.6%while it reaches 96.3%before the cylinder at a flow rate of 3.32 LPM.Finally,in the closed-loop VFD-PLC in the expansion stroke,the rated electrical power consumption of the three-phase IM decreased to 532 W at the speed of 1325.3 rpm,resulting in energy savings of 20.6%.
文摘针对电力语音通信系统架构老化、协议异构、运维割裂等问题,提出基于IP多媒体子系统(IP Multimedia Subsystem,IMS)的语音接入网融合改造方案,构建统一信令控制、媒体处理与服务质量(Quality of Service,QoS)保障体系。设计端到端架构,完成多协议信令映射、安全与QoS协同机制,实现控制面集中化与接口能力开放。通过构建实验环境开展高并发性能测试,验证系统在会话控制、媒体传输与资源调度方面的提升效果,结果表明改造方案具备工程可行性与部署价值。
文摘电信运营商拥有大规模的语音用户数,但是随着OTT(Over The Top)业务的广泛使用,给运营商基础语音业务受到了冲击,每用户通话时长(Minutes Of Usage,MOU)持续降低且收入逐年下降。5G增强通话是基于5G的新一代通话产品,提供超高清、智能化、全交互三大能力,以期增加用户黏性并为基础通话业务带来新的潜在增长空间。介绍5G增强通话的业务类型和发展现状,然后从建设原则、网络架构、数据通道信令功能(Data Channel Signaling Function,DCSF)网元建设方案、资源池建设方案、网络安全及可靠性等方面探讨5G增强通话控制面网元DCSF的建设实施方案。
文摘This paper presents an efficient method of equivalient workstations for modeling and analysis of multistage transfer lines with unreliable machines and finites buffers. The deterministic processing times for discrete parts and random failuse and repair times for machines are assumed. These buffers lead to blockage and starvation in operation due to limited storage capacities and make the problem of modelling and analysis very difficult to treat because they have large state spaces and cannot be decomposed exactly. A single buffer between two reliable workstations is analysed first. Then an equivalent workstation without starvation and blockage is constructed. Thereafter connecting all the equivalent workstations in series we get the equivalent transfer line. A set of preformance measures such as the production rates, efficiencies and average inventory levels are derived in explicit analytical expressions. Finally two numerical examples are given for comparing these calculated results with those of S. B. Gershwin (1987) and C. R. Glasseye & Y. Hong (1993) and illustrating the application of the method in engineering design directly.
