兆瓦级高效紧凑型核动力系统运行特性研究

为研究兆瓦级高效紧凑型核动力系统的运行特性,使用自主开发的热管堆瞬态分析程序TAPIRS(Transient Analysis code for heat Pipe and AMTEC power conversion space Reactor power System)和超临界二氧化碳布雷顿循环的瞬态分析程序SCTRAN/CO_(2)(Super Critical reactors Transient Analysis code/Carbon Dioxide)的耦合程序对其反应性、负荷、冷却水温度和流量等扰动进行了开环动态响应分析,并据此进行了控制系统设计。在此基础上,对线性变负荷、阶梯式变负荷以及甩负荷这三种变负荷运行工况进行了计算分析。结果表明:该核动力系统的转速对扰动的变化较为敏感,需要加以控制;低负荷下旁通会使压缩机流量上升,需对压缩机流量加以控制;系统在控制方案下能以6%FP(Full Power)·min^(−1)的速度实现0%~100%的负荷变动,且可以在任意负荷水平下运行;甩负荷下系统的波动时间变长,但是仍可达到新的稳态进行工作,且各参数处于安全范围内。本研究可为新型核动力系统的概念设计提供参考。

数模—动模混合仿真系统的接口建模与稳定性分析

为满足现代电力系统实时仿真的发展需求,数模-动模混合仿真系统结合实时数字仿真和物理动态模拟仿真的优点,成为现代电力系统研究的重要仿真方法。接口系统是混合仿真系统设计中的核心与难点。为了深入分析混合仿真系统的稳定性,对接口系统各个组成环节进行建模得到系统开环传递函数,分别根据劳斯判据和奈奎斯特判据研究开环传递函数中不同参数对系统稳定性的影响。理论推导表明接口系统中滤波器截止频率、接口延时和阻抗模拟比对系统的稳定性影响较大,并通过所搭建的混合仿真系统进行实验,实验结果表明不同参数对系统的稳定性影响与理论推导一致。

面向开环扫描系统的超声图像畸变校正方法

超声显微成像技术广泛应用于工业无损检测领域。相较于闭环、半闭环扫描系统硬件复杂、成本高,开环扫描系统结构简单、成本低,但由于无反馈机制会导致步进电机的非线性运动引起图像像素错位畸变。因此,消除非线性运动带来的错位畸变是采用开环扫描系统实现高质量超声成像的关键。该文提出集最大值投影法、最大类间方差法和中心坐标校正法于一体的MIP-Otsu-C3M方法,对开环扫描系统获得的硬币回波数据采用最大值投影法获取初始灰度图像,采用最大类间方差法获取感兴趣区域的B扫描图像边缘像素位置,并采用中心坐标校正法成功消除像素错位,解决了超声C扫描图像畸变问题。对消除错位畸变的回波数据进行飞行时间法和傅里叶变换法图像重建,直接获得了非畸变的三维图像和透视图像。该新颖算法也验证了最大值投影法可拓展至图像畸变校正应用。

开式空气循环热泵干燥系统性能仿真分析

为解决能源使用效率低、HCFC/HFC等非环保制冷剂使用等问题,提出了不同于传统干燥技术的以空气为工质的空气循环热泵干燥(ACHPD)系统新技术。建立了数学仿真模型,通过所构建实验台的实验结果进行验证,干燥速率误差在±0.01%以内,系统功率误差在±7%以内。与传统的电加热器干燥(EHD)系统相比,当水质量蒸发率从0.75 kg/h增至3.45 kg/h时,ACHPD系统的节能率达到15%~27%。进气温度由10℃增至40℃和相对湿度由30%增至80%分别使单位除湿能效比(MER)降低约7%和21%。膨胀机效率由0.55增至0.8和压缩机效率由0.4增至0.9会使系统的能效分别降低17%和36%。

A novel control strategy for reproducing the floor motions of high-rise buildings by earthquake-simulating shake tables

To enable the experimental assessment of the seismic performance of full-scale nonstructural elements with multiple engineering parameters(EDPs),a three-layer testbed named Nonstructural Element Simulator on Shake Table(NEST)has been developed.The testbed consists of three consecutive floors of steel structure.The bottom two floors provide a space to accommodate a full-scale room.To fully explore the flexibility of NEST,we propose a novel control strategy to generate the required shake table input time histories for the testbed to track the target floor motions of the buildings of interest with high accuracy.The control strategy contains two parts:an inverse dynamic compensation via simulation of feedback control systems(IDCS)algorithm and an offline iteration procedure based on a refined nonlinear numerical model of the testbed.The key aspects of the control strategy were introduced in this paper.Experimental tests were conducted to simulate the seismic responses of a full-scale office room on the 21^(st)floor of a 42-story high-rise building.The test results show that the proposed control strategy can reproduce the target floor motions of the building of interest with less than 20%errors within the specified frequency range.

船用柴油机SCR系统控制策略试验研究

为降低船用柴油机NO_(x)排放,分析柴油机选择性催化还原(selective catalytic reduction,SCR)后处理系统的开环、闭环控制策略,对不同策略及工况下NO_(x)转化率及NH3泄露进行试验对比。结果表明:采用开环策略,柴油机功率与额定功率的比为75%以上时,NO_(x)转化效率可达到83%,但不同工况下NO_(x)转化率波动超过20%;采用闭环控制策略,不同工况下NO_(x)转化率稳定在85%左右,尾气中NH_(3)的体积分数低于20×10^(-6);闭环控制策略下NO_(x)转化率具有自调整、高稳定性、响应速度快等优势,可降低NO_(x)排放且尾气中NH3的体积分数在规定范围内。

星基GNSS掩星事件预报方法分析

针对全球卫星导航系统(GNSS)星基掩星观测时长通常仅有几十秒,特别是在升星掩星观测中,需要快速实现负高度角卫星信号的捕获跟踪,才能获得及时有效的掩星观测时长的问题,基于先验轨道信息辅助的开环跟踪技术,提出一种基于切线高度的掩星事件快速预报方法,以辅助掩星接收机快速捕获和跟踪GNSS掩星信号,从而保证掩星观测数据质量和有效观测时长:对地球局部曲率中心进行修正,得到更为精准的切线高度;然后设置掩星事件的判决条件,采用极值的方式快速预报出符合阈值的掩星事件;最后对全球内曲率中心和曲率半径进行分析。实验结果表明,曲率中心的修正距离最大值可至45 km,曲率半径波动范围可达到65 km,足以影响掩星探测的准确预报。基于气象、电离层和气候星座观测系统(COSMIC-2)实测数据的仿真结果表明,掩星预报的全球定位系统(GPS)掩星漏报率低于3%,格洛纳斯卫星导航系统(GLONASS)掩星漏报率约14.5%,且预报掩星开始时间大多提前5~10 s;证明基于切线高度的掩星预报方法能够有效地应用于星基掩星事件的预报,以辅助接收机准确捕获和跟踪信号,提升掩星观测资料的数据量和有效观测时长。

ATM Open-Loop Shuffleout网络丢失率新的计算方法

文献 [1]提出了Open LoopShuffleout的ATM交换结构 .它是基于多级自路由、输出排队的Banyan结构 .文献[9]在文献 [1]的基础上构造了多递ATMShuffleout交换结构 .这种Open LoopShuffleout的ATM交换结构的信元丢失率包括三部分 ,其中之一就是网络丢失率πn.文献 [1]计算网络丢失率是在假设任意一级交换单元中每一输出端口的负载相同的前提下进行的 .本文考虑了更一般的情况 ,给出了精确计算网络丢失率的分析模型 ,不仅能够处理随机业务 ,而且还能处理热点业务 .模型分析和仿真的数字结果显示了在热点业务下一些有益的结论 .

Dispersion compensation in an open-loop all-optical chaotic communication system

The optical chaotic communication system using open-loop fiber transmission is studied under strong injection conditions. The optical chaotic communication system with open-loop configuration is studied using fiber transmission under strong injection conditions. The performances of fiber links composed of two types of fiber segments in different dispersion compensation maps are compared by testing the quality of the recovered message with different bit rates and encrypted by chaotic modulation （CM） or chaotic shift keying （CSK）. The result indicates that the performance of the pre-compensation map is always worst. Two types of symmetrical maps are identical whatever the encryption method and bit-rate of message are. For the transmitting and the recovering of message of lower bit rate （1 Gb/s）, the post-compensation map is the best scheme. However, for the message of higher bit rate （2.5 Gb/s）, the parameters in communication system need to be modified properly in order to adapt to the high-speed application. Meanwhile, two types of symmetrical maps are the best scheme. In addition, the CM method is superior to the CSK method for high-speed applications. It is in accordance with the result in a back-to-back configuration system.

Instability of cylinder wake under open-loop active control

Instability of a wake controlled by a streamwise Lorentz force is investigated through a Floquet stability analysis. The streamwise Lorentz force, which is a two-dimensional control input created by an electromagnetic actuator located on the cylinder surface,adjusts the base flow to affect the three-dimensional wake instability and achieve wake stabilization and transition delay. The instability mode at a Reynolds number Re = 300 can be transformed from B to A with N = 1.0, where N is an interaction number representing the strength of the Lorentz force relative to the inertial force in the fluid. The wake flow is Floquet stable when N increases to 1.3. The spanwise perturbation wavelengths are 3.926 D and 0.822 D in the modes A and B, respectively, where D is the cylinder diameter. In addition, the oscillating amplitudes of drag and lift are reduced with the increase in the interaction number. Particle tracing is used to explore the essential physical mechanism for mode transformation. The path lines show that suppression of flow separation hinders the fluid deformation and rotation, leading to the decrease in elliptic and hyperbolic instability regions, which is the material cause of mode transformation.All of the results indicate that wake stabilization and transition delay can be achieved under open-loop active control via the streamwise Lorentz force.

Open-loop frequency response for a chaotic masking system

In this paper, a new numerical simulation approach is proposed for the study of open-loop frequency response of a chaotic masking system. Using Chua＇s circuit and the Lorenz system as illustrative examples, we have shown that one can employ chaos synchronization to separate the feedback network from a chaotic masking system, and then use numerical simulation to obtain the open-loop synchronization response, the phase response, and the amplitude response of a chaotic masking system. Based on the analysis of the frequency response, we have also proved that changing the amplitude of the exciting （input） signal within normal working domain does not influence the frequency response of the chaotic masking system. The new numerical simulation method developed in this paper can be extended to consider the open-loop frequency response of other systems described by differential or difference equations.

Analytical solution for a class of linear quadratic open-loop Nash game with multiple players

In this paper, the Nash equilibria for differential games with multiple players is studied. A method for solving the Riccati-type matrix differential equations for open-loop Nash strategy in linear quadratic game with multiple players is presented and analytical solution is given for a type of differential games in which the system matrixcan be diagonalizable. As the special cases, the Nash equilibria for some type of differential games with particular structure is studied also, and some results in previous literatures are extended. Finally, a numerical example is given to illustrate the effectiveness of the solution procedure.

PERFORMANCE OF A NEW DECODING METHOD USED IN OPEN-LOOP ALL-OPTICAL CHAOTIC COMMUNICATION SYSTEM

A new decoding method with decoder is used in open-loop all-optical chaotic communication system under strong injection condition.The performance of the new decoding method is numerically investigated by comparing it with the common decoding method without decoder.For new decoding method,two cases are analyzed,including whether or not the output of the decoder is adjusted by its input to receiver.The results indicate the decoding quality can be improved by adjusting for the new decoding method.Meanwhile,the injection strength of decoder can be restricted in a certain range.The adjusted new decoding method with decoder can achieve better decoding quality than decoding method without decoder when the bit rate of message is under 5 Gb/s.However,a stronger injection for receiver is needed.Moreover,the new decoding method can broaden the range of injection strength acceptable for good decoding quality.Different message encryption techniques are tested,and the result is similar to that of the common decoding method,indicative of the fact that the message encoded by using Chaotic Modulation(CM) can be best recovered by the new decoding method owning to the essence of this encryption technique.

Chaos Correlation in Open-loop Semiconductor Lasers Scheme Effected by Variable Feedback Time

The effect of optical feedback time （depend on the distance between the front facet of the laser and the external mirror） on the chaos synchronization in open-loop communication system have been investigated. In this system, the dynamics of semiconductor lasers with both the optical feedback and optical injection are coherently coupled with the internal laser field. The synchronization map becomes a cloud of points for some parameters values （no correlation between Master laser ML and Slave laser SL outputs）. It means that the two lasers are decoupled. It can be clearly seen when kf = 0.2, kinj = 0.4 and τ = 1 the correlation between these two laser outputs are in a diagonal line, which implies the excellent correlation between them and verifies their synchronization. It is evident that the synchronization quality of open-loop scheme improves for this value is better than that of the other amounts. Value is better than that of the other amounts.

Experiments on an Open-Loop Cycle Carbon Dioxide Refrigeration System

An open loop cycle carbon dioxide(CO2)refrigeration system is established,and the cooling performances of high-pressure CO2 under different storage conditions(25℃,30℃,and 35℃)are investigated.Moreover,the experimental mass flow rates of CO2 are compared with the theoretical values at different conditions and refrigeration capacities.The results indicate that the storage condition of CO2 has a significant impact on the refrigeration performance,and the mass flow rate of CO2 increases with the increasing storage temperature in a given refrigeration capacity.

虚拟现实在实验动物行为分析中的应用进展

虚拟现实(virtual reality,VR)是一种通过计算机进行场景模拟的新兴技术,近年来已经成为动物行为分析的可靠工具。动物行为对动物生存至关重要。动物行为分析为遗传学、生态学、神经科学、经济学以及机器人科学等领域的科技进步提供了有用信息。动物行为分析可分为刺激独立于动物对刺激的反应的开环研究,以及刺激根据动物的实时运动进行调整的闭环研究。本文首先梳理了动物行为分析的起源、概念和应用领域,回顾了传统技术条件下以视觉刺激为代表的动物行为开环研究的不足;然后以视觉、嗅觉、触觉、听觉刺激为例,分析了虚拟现实技术条件下的动物行为分析系统能够将精确的实验控制与复杂的实验动物行为相结合的可行性,完成了真实物理世界的实验方法无法实现的闭环研究;最后对虚拟现实发展为高级模拟及虚拟动物的前景进行了展望。

应用型地方本科高校闭环开放“三全”协同育人——以湖南理工学院为例

面向现代化强国建设人才支撑需要,应用型地方本科高校的教育工作着力点为培养应用型人才。湖南理工学院为首批国家产教融合发展工程应用型本科规划高校,正在积极研究探索应用型地方本科高校所需的人才培养模式,基于“三全育人”格局和“协同育人”耦合思路,建立“四有”协同育人闭环机制与“六维”协同育人开放体系,实践探索闭环开放“三全”协同育人的有效性。运用模糊综合评价方法,对2019年到2021年“三全”协同育人模式的实施效果进行评价,验证了“三全”协同育人模式的有效性,并对模式现有的不足提出了展望。

具有丢包补偿的GORC-PID算法无线温度控制系统

对于工业过程控制中有线控制存在的布线困难、可拓展性差、维护成本高等问题,本文设计并开发了具有丢包补偿GORC-PID(generalized open-loop response control-PID)算法的无线温度控制系统。以工业上通用的WirelessHART为标准协议,使用无线硬件设备搭建无线通信网络,替代有线通信方式,并以监视与控制通用系统(monitor and control generated system, MCGS)组态软件为控制平台,采用改进的广义开环响应控制(generalized open-loop response control, GORC)与PID控制相结合的控制算法,通过构建的具有丢包补偿的Smith预估器对丢包数据进行估计,得出补偿的估计值,并参与GORC滚动优化中,来实现对温度的实时监测与控制。以高温炉作为研究对象进行实验,结果表明所设计的无线温度控制系统不仅可以有效解决有线过程控制中存在的问题,而且可以解决无线通信过程中的丢包、迟滞等问题,具有良好的工业价值。

基于模型预测的调距桨控制器设计与研究

调距桨属于舰船推进装置,其液压系统用于改变桨叶的螺距角度,使舰船在航行时可以灵活地改变航速、航向。为了解决调距桨达到指定信号时,超调量过大、响应时间过长的问题,对调距桨液压系统进行抽象建立数学模型,采取模型预测控制(MPC)的算法,对系统输出结果和跟踪信号进行分析,实时滚动优化控制器参数,最终设计出基于模型预测的调距桨控制器。在Matlab/Simulink环境下根据调距桨的实际运行工况,选择跟踪信号和阶跃信号两种情形下对MPC和PID控制器进行对比仿真实验。结果表明,MPC比PID控制器具有更好的准确性和响应速度,累积误差明显小于PID控制器。该控制器能够使调距桨快速达到预期响应,航行的及时性得到保证,可满足调距桨控制系统应用要求。

Connections Between Induction Generator Effect and Open-loop Modal Proximity to Cause Sub-synchronous Oscillations in Series-compensated Power System

The induction generator effect(IGE)and the openloop modal proximity(OLMP)are two different reasons why subsynchronous oscillations(SSOs)in a series-compensated power system(SCPS)may occur.The IGE attributes the growing SSOs to negative resistance,while the OLMP explains the SSO mechanism from the standpoint of modal conditions.In this paper,we investigate the connections between the IGE and the OLMP through equivalent RLC circuit and open-loop modal analysis.Our investigation is conducted for two types of seriescompensated power systems where either a synchronous generator or a DFIG is connected at the sending end.The investigation reveals the conditions,in which the IGE and the OLMP may jointly cause the growing SSOs,i.e.,both the IGE and the OLMP can explain why the growing SSOs occur.Furthermore,the investigation indicates that the IGE and the OLMP may be totally irrelevant and lead to growing SSOs separately.This implies that it is possible that in a SCPS,the growing SSOs are only due to the IGE,and the OLMP is non-existent,and vice versa.Hence,when the growing SSOs occurs in a SCPS,examination based on both the IGE and the OLMP should be carefully conducted in order to find if the oscillatory instability is due to the IGE,or the OLMP,or both of them.