Dynamic analysis and split range control for maximization of operating range of continuous microbial fuel cell

Human development is inherently connected with availability of water and energy.Energy production requires water,whereas water treatment needs energy.On the other hand,microbial fuel cell has capability to produce energy and water simultaneously from waste water or organic matter.In this paper,first principle-based model of variable volume microbial fuel cell is simulated.Hydraulic retention time is selected as the manipulated variable using the study of steady state and dynamic responses.Classical PI and model predictive control strategies are developed for controlling the produced power from the cell,and its performance is tested for servo problem.Settling time for positive and negative set points is found to be 126 and 889 h in case of classical PI and 120 and 750 h in case of linear MPC,respectively along with large increase(three times order of magnitude)in working volume for negative set point.These control challenges are overcome by using split range controller with variable and constant volume microbial fuel cells.The settling time for negative set point is found to be 49 and 21 h for classical PI and linear MPC schemes,respectively,which is significantly lower than using only variable volume microbial fuel cell.Also,there is no increase in the working volume of the constant volume microbial fuel cell.Hence,operating range of the microbial fuel cell is enhanced using split range controller.

Model-Based Split-Range Algorithm for the Temperature Control of a Batch Reactor

In the manufacturing processes of high value-added products in the pharmaceutical, fine chemical polymer and food industry, insufficient control might produce off-grade products. This can cause significant financial losses, or in the pharmaceutical industry, it can result in an unusable batch. In these industries, batch reactors are commonly used, the control of which is essentially a problem of temperature control. In the industry, an increasing number of heating-cooling systems utilising three different temperature levels can be found, which are advantageous from an economic point of view. However, it makes the control more complicated. This paper presents a split-range designing technique using the model of the controlled system with the aim to design a split-range algorithm more specific to the actual sys- tem. The algorithm described provides high control performance when using it with classical PID-based cascade temperature control of jacketed batch reactors;however, it can be used with or as part of other types of controllers, for ex- ample, model-based temperature controllers. The algorithm can be used in the case of systems where only two as well as where three temperature levels are used for temperature control. Besides the switching between the modes of opera- tion and calculating the value of the manipulated variable, one of the most important functions of the split-range algo- rithm is to keep the sign of the gain of the controlled system unchanged. However, with a more system-specific split-range solution, not only can the sign of the gain be kept unchanged, but the gain can also be constant or less de- pendent on the state of the system. Using this solution, the design of the PID controller becomes simpler and can be implemented in existing systems without serious changes.

An Identifier-Based Network Access Control Mechanism Based on Locator/Identifier Split

Legacy IP address-based access control has met many challenges, because the network nodes cannot be identified accurately based on their variable IP addresses. “Locator/Identifier Split” has made it possible to build a network access control mechanism based on the permanent identifier. With the support of “Locator/Identifier Split” routing and addressing concept, the Identifier-based Access Control (IBAC) makes net-work access control more accurate and efficient, and fits for mobile nodes’ access control quite well. Moreover, Self-verifying Identifier makes it possible for the receiver to verify the packet sender’s identity without the third part authentication, which greatly reduces the probability of “Identifier Spoofing”.

延期状态下电子雷管电子控制模块的高过载加载实验

为探究电子雷管内的电子控制模块在延期状态下受冲击载荷时的失效机制,采用分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)对电子雷管试件进行了高过载加载测试,得到了整体电子控制模块和分离出钽电容的其余电子控制模块受不同加载压力时的失效情况。结果显示:钽电容在1.495×10^(5)g过载时出现电压下降现象,且过载越大,短路失效情况越明显;在一定过载范围内,钽电容因其特有的自愈性,可在短时间内回到起始量级;当过载超过临界范围,达到3.848×10^(5)g时,钽电容损坏且无法逆转。模块内其余组件的抗过载能力强于电容,芯片在4.155×10^(5)g过载后检测异常,电阻元件失效发生在4.249×10^(5)g以上过载。

Split源光伏并网逆变器控制策略研究

用于存储可再生能源的并网电源转换系统需满足低成本,高效率和复杂度等要求。使用传统的并网逆变器时,通常需要在前级加入一个升压变换电路,从而造成了两级结构。单级并网逆变器只用一级能量变换就可实现DC-AC并网逆变功能,因此在体积、成本、质量和复杂度等方面均优于两级结构。基于上述分析,研究了Split源逆变器(SSI),作为阻抗网络型逆变器的替代选择。分析了SSI的工作原理,建立了平均状态模型。在此基础上,使用了一种改进的调制策略,结合同步旋转坐标系控制技术,实现了并网模式下SSI的解耦控制。利用Matlab/Simulink搭建的模型进行了仿真实验,结果验证了理论分析的正确性和实用性。

The Coupling of Voltage and Frequecncy Response in Splitting Island and Its Effects on Load-shedding Relays

The voltage and frequency dynamics interact with each other in the island after splitting. The current frequency response model without considering the voltage effect would bring remarkable errors when analyzing the frequency dynamic progress in the island with large-capacity active-power shortage. In this paper, coupling effects of voltage and frequency are studied to indicate that initial reactive-power deficit and load characteristics have strong effects on the coupling effects of the voltage and frequency. Moreover, control effects of currently used under frequency load-shedding relays (UFLS) and under voltage load-shedding relays (UVLS) which are installed and executed independently are examined to find that it would sometimes cause excessive or inadequate control without considering the coupling, suggesting that it is necessary to develop coordinate control methods for voltage and frequency problems.

Generalized Internal Model Robust Control for Active Front Steering Intervention

Because of the tire nonlinearity and vehicle＇s parameters＇uncertainties,robust control methods based on the worst cases,such as H_∞,μsynthesis,have been widely used in active front steering control,however,in order to guarantee the stability of active front steering system（AFS）controller,the robust control is at the cost of performance so that the robust controller is a little conservative and has low performance for AFS control.In this paper,a generalized internal model robust control（GIMC）that can overcome the contradiction between performance and stability is used in the AFS control.In GIMC,the Youla parameterization is used in an improved way.And GIMC controller includes two sections：a high performance controller designed for the nominal vehicle model and a robust controller compensating the vehicle parameters＇uncertainties and some external disturbances.Simulations of double lane change（DLC）maneuver and that of braking on split-μroad are conducted to compare the performance and stability of the GIMC control,the nominal performance PID controller and the H_∞controller.Simulation results show that the high nominal performance PID controller will be unstable under some extreme situations because of large vehicle＇s parameters variations,H_∞controller is conservative so that the performance is a little low,and only the GIMC controller overcomes the contradiction between performance and robustness,which can both ensure the stability of the AFS controller and guarantee the high performance of the AFS controller.Therefore,the GIMC method proposed for AFS can overcome some disadvantages of control methods used by current AFS system,that is,can solve the instability of PID or LQP control methods and the low performance of the standard H_∞controller.

Branch Quality Control of Gas-Liquid Two-Phase Flow Using a Novel T-Junction Type Distributor

In order to eliminate mal-distribution and ensure the side arm to produce desirable gas quality a special distributor is proposed. The experimental distributor mainly consists of a straight through section,a gas extraction line,a liquid extraction line and a side arm branch. A gas orifice and a liquid orifice are mounted at the gas and liquid extraction line respectively to control the outlet gas quality. The diameter of the liquid orifice was set to 2. 50 mm and three gas orifices with different size( dG= 2. 65,5. 00,10. 00 mm) were tested. The experiments were carried out at an air-water two-phase flow loop. The gas superficial velocity ranged from 6. 0 to 20. 0 m /s and the liquid superficial velocity was in the range of 0. 02- 0. 18 m /s. Flow patterns such as wave flow,slug flow and annular flow were observed. The gas quality of the side arm branch was found mainly determined by the flow area ratio of the gas orifice to the liquid orifice and independent of gas and liquid superficial velocity,flow patterns and extraction flux.

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.

Conditional Lot Splitting to Avoid Setups While Reducing Flow Time

Previous research has clearly and consistently shown that flow time advantages accrue from splitting production lots into smaller transfer batches or sub-lots. Less extensively discussed, and certainly undesired, is the fact that lot splitting may dramatically increase the number of setups required, making it impractical in some settings. This paper describes and demonstrates a primary cause of these “extra” setups. It then proposes and evaluates decision rules which selectively invoke lot splitting in an attempt to avoid extra setups. For the closed job shop environment tested, our results indicate that conditional logic can achieve a substantial portion of lot splitting’s flow time improvement while avoiding the vast majority of the additional setups which would be caused by previously tested lot splitting schemes.

分体式自清洗工业废气余热回收装置设计

为解决化纤生产废气余热回收装置运行一段时间后因污垢层积而换热效率下降的问题,提出一种分体式自清洗工业废气余热回收装置。设计了分体式换热器,采用PLC控制刷洗机构、拉板小车和高压喷头,实现了换热翅片管排的自动分合和清洗功能。测试结果显示,分体式自清洗工业废气余热回收装置能维持较高的换热效率,较原有整体式装置效率提升大约5%,清洗时间由10h缩短为2.5h。该余热回收装置可提高能源利用效率,降低生产成本,减少维护时间,为低品位热能回收利用提供了参考。

风险敏感性平均场控制的一个二阶必要条件

本文研究风险敏感性平均场控制的一个二阶必要条件.介绍了一类新的分裂形式的一阶伴随方程,这类方程在分析二阶伴随变量转换时更具有优势.通过构造一类新的二阶伴随变量的转换,证明风险敏感性平均场奇异控制的二阶最大值原理.最后,我们提供了一个解释性例子.

重型装载机械的液压无级变速器自适应传动控制策略研究

液压无级变速器作为重型装载机械传动系统的核心部件,对提高装载机械的工作效率和性能具有关键作用。然而,由于工况的复杂性,单纯的液压无级变速器已然无法满足工作需求。因此,文章首先对机械液压无级变速器进行了分析,阐述了其速比测算方式。在此基础上,通过构建阻力估算模型提出了一种分工况速比自适应控制策略。实验结果表明,阻力估算模型的误差平均值为4.5%,MAE最低为3.17、MAPE最低为12.93%、RMSE最低为1.02。相较于传统策略,分工况策略能够加快机械液压无级变速器的运行速度、缩短装载机械的作业时间并节省燃油。其速比控制误差最低为3.3%,响应时间最短为5.7 s。

多断面多通道互联电网广域失步解列控制系统设计及实施

总结分析了多断面多通道区域互联电网失步振荡时可能存在的多断面失步存在选择性、同一断面不同通道失步不同时以及同一断面上部分通道失步特性不明显等特性,针对现有就地失步解列方案不适应上述特性的问题,采用基于就地装置动作允许命令,利用远方通信构建的广域失步解列系统方法,根据考虑解决现有就地失步解列方案问题、与现有就地失步解列功能的配合、系统防误设计以及异常情况下控制策略处理逻辑等主要设计原则,设计并实施了南方电网广域失步解列控制系统。RTDS仿真试验结果表明,该系统能够正确响应,有选择、快速、可靠地采取既定措施同时解列相关断面,有效解决现有就地失步解列方案的局限性,满足实际系统运行需要。

一种新型分体式换流变压器有载分接开关

近年来发生了数起换流变压器有载分接开关在档位调节过程中爆炸起火的严重事故。针对此问题,提出了一种新型分体式换流变有载分接开关的设计方案,将切换开关部分与变压器本体分离,有效避免分接开关故障影响的扩大。切换开关各触头由真空永磁开关替代且操作机构独立配置,结合内部支路配置的电流采样装置,实现切换过程的监测可控。提出了分体式同步控制逻辑和切换开关分步控制逻辑,实现了分接开关调档过程的状态监测及故障保护。样机的试验结果验证了分体式换流变压器有载分接开关方案的可行性和有效性。

赋能动力学色谱法快速海水提铀研究

作为重要的分离和分析手段,液相色谱法主要应用在分析化学领域,而在核素分离工作中报道十分罕见。本项目基于动力学色谱理论基础,研发出一种脉冲式进样-赋能动力学色谱柱,色谱柱的填料采用粒径为0.2 mm的惰性二氧化硅,柱长为5 m,色谱分离单元约3.06万个。通过改变色谱柱外界条件,分析铀酰离子在色谱柱内的运动情况;通过水浴加热、超声波和外加磁场对色谱柱进行赋能,以提高离子相互分离的效果;在不同进样流速和温度下,研究混合核素的分离情况,得到最佳分离条件及色谱柱的动力学特性。结果表明,样品流速为4.109 mL·min^(−1),色谱柱加热温度为50℃,此时铀酰离子和钠离子的分离因数为1.1854。以最佳分离条件进行海水提铀,得到铀和钠离子的分离因数为α=1.575,实现海水中铀和钠离子分离理论上需要20级。脉冲式进样-赋能动力学色谱柱能够高效快速地实现海水中铀的分离提取。文中采用的创新性方法,还可应用于其他核素的分离研究。

CR-RSMA网络接入控制策略研究

针对多个次用户的速率分割多址接入技术辅助的认知无线电(CR-RSMA,cognitive radio-inspired rate splittingmultipleaccess)网络设计了一种接入控制策略,在主用户实现与正交多址接入(OMA,orthogonal multiple access)相同的中断性能并满足次用户通信服务质量(QoS,quality of service)需求的前提下,让更多的次用户接入主用户频段,并在此基础上最大化次用户吞吐量之和。该策略考虑次用户QoS约束,联合优化次用户发射功率分配因子和接入次用户集合,推导出最优功率分配因子的闭合表达式,进而求得次用户最大通信速率和最小通信时间,在此基础上利用贪婪搜索算法确定最终接入的次用户,最后通过优化时间资源实现所有接入次用户吞吐量之和的最大化。仿真结果表明,该策略相比于非正交多址接入技术辅助的认知无线电(CR-NOMA,cognitive radio-inspired non-orthogonal multiple access)网络在接入用户数和吞吐量方面均表现出更优越的性能。

Review of the development of power system out-of-step splitting control and some thoughts on the impact of large-scale access of renewable energy

Out-of-step oscillation is a very destructive physical phenomenon in power system, which could directly cause big blackout accompanied by serious sociology-economic impacts. Out-of-step splitting control is an indispensable means, which could protect the system from major shocks of out-of-step oscillation. After years of development, it has achieved certain amount of research results. Have the existing methods been able to meet the requirements of out-of-step splitting? What improvements are needed? Under this background, this review is written. It combs the development of out-of-step splitting control technologies and analyzes the technical routes and characteristics of different methods. It points out the contradiction between rapidity and optimality is the biggest technical problem, existing in both the traditional local measurement based out-of-step splitting protection and the wide-area information based out-of-step splitting protection. It further points out that the advantages of the two types of protections can be combined with the unique physical characteristics of the out-of-step center to form a more advantageous splitting strategy. Besides, facing the fact of large-scale renewable energy access to power grid in recent years, this review also analyzes the challenges brought by it and provides some corresponding suggestions. It is hoped to provide some guidance for the subsequent research work.

剖分式直齿锥齿轮的数控加工运动求解

为了实现剖分式直齿锥齿轮的数控加工,基于直齿锥齿轮剖分切齿的刀位求解,结合通用五坐标数控机床,建立立铣刀侧铣加工剖分式直齿锥齿轮的坐标转换关系,推导各坐标系之间的转换矩阵。根据已知的刀轴矢量和刀心坐标,分别求解立铣刀侧铣剖分式直齿锥齿轮时的机床直线运动轨迹、回转运动轨迹的显函数表达式。通过VERICUT软件的切齿加工仿真,初步验证了运动轨迹的正确性。通过实际的齿面加工及齿面检测,进一步验证了立铣刀侧铣加工剖分式直齿锥齿轮数控加工运动求解的正确性。

大型建筑楼宇群分体空调精准智能化管控的研究与设计

本文阐述了针对大型建筑楼宇群分体空调管控现状的研究,结合其分体空调智慧管理系统的精准智能化管控措施,以及其带来的能源节约、成本降低、效率提高等方面的作用。简述其在实际工程中的设计方法与应用效果。