Stiffness-damping matching method of an ECAS system based on LQG control

A novel method of matching stiffness and continuous variable damping of an ECAS(electronically controlled air suspension) based on LQG(linear quadratic Gaussian) control was proposed to simultaneously improve the road-friendliness and ride comfort of a two-axle school bus.Taking account of the suspension nonlinearities and target-height-dependent variation in suspension characteristics,a stiffness model of the ECAS mounted on the drive axle of the bus was developed based on thermodynamics and the key parameters were obtained through field tests.By determining the proper range of the target height for the ECAS of the fully-loaded bus based on the design requirements of vehicle body bounce frequency,the control algorithm of the target suspension height(i.e.,stiffness) was derived according to driving speed and road roughness.Taking account of the nonlinearities of a continuous variable semi-active damper,the damping force was obtained through the subtraction of the air spring force from the optimum integrated suspension force,which was calculated based on LQG control.Finally,a GA(genetic algorithm)-based matching method between stepped variable damping and stiffness was employed as a benchmark to evaluate the effectiveness of the LQG-based matching method.Simulation results indicate that compared with the GA-based matching method,both dynamic tire force and vehicle body vertical acceleration responses are markedly reduced around the vehicle body bounce frequency employing the LQG-based matching method,with peak values of the dynamic tire force PSD(power spectral density) decreased by 73.6%,60.8% and 71.9% in the three cases,and corresponding reduction are 71.3%,59.4% and 68.2% for the vehicle body vertical acceleration.A strong robustness to variation of driving speed and road roughness is also observed for the LQG-based matching method.

DEVELOPMENT OF A DATA MINING METHOD FOR LAND CONTROL

Land resources are facing crises of being misused,especially for an intersection area between town and country,and land control has to be enforced.This paper presents a development of data mining method for land control.A vector_match method for the prerequisite of data mining i.e., data cleaning is proposed,which deals with both character and numeric data via vectorizing character_string and matching number.A minimal decision algorithm of rough set is used to discover the knowledge hidden in the data warehouse.In order to monitor land use dynamically and accurately,it is suggested to set up a real_time land control system based on GPS,digital photogrammetry and online data mining.Finally,the means is applied in the intersection area between town and country of Wuhan city,and a set of knowledge about land control is discovered.

Molecular Weight Controllable Degradation of Laminaria japonica Polysaccharides and Its Antioxidant Properties

In this study, molecular weight controllable degradation of algal Laminaria japonica polysaccharides(LPS) was investigated by ultrasound combined with hydrogen peroxide. Three main factors, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C) were chosen for optimizing parameters by employing three-factors, three-levels BBD. The influence of degradation on structure change and antioxidant activities was also investigated. A second-order polynomial equation including molecular weight(Y) of Laminaria japonica polysaccharides and each variable parameter, i.e., ultrasonic power(A), ultrasonic time(B), and H_2O_2 concentration(C), was established: Y=20718.67-4273.13A-4000.38B-1438.75C+2333.25AB+1511.00AC+873.00BC+2838.29A^2 + 2490.79B^2+873.04C^2. The equation regression coefficient value(R^2 = 0.969) indicated that this equation was valid. The value of the adjusted determination coefficient(adjusted R^2 = 0.914) also confirmed that the model was highly significant. The results of selected experimental degradation conditions matched with the predicted value. FT-IR spectra revealed that the structures of LPS before and after degradation were not significantly changed. Antioxidant activities of LPS revealed that low Mws possessed stronger inhibitory than the original polysaccharides. The scavenging effects on superoxide radicals was the highest when IC50 of crude LPS was 4.92 mg mL^(-1) and IC50 of Mw 18.576 KDa was 1.02 mg mL^(-1), which was fourfold higher than initial polysaccharide.

计及静态电压稳定约束的最少发电机优化调度方法

电压稳定控制中的控制数量多,且紧急状态时要求控制措施快速响应。构建一种以最少发电机调整数量为目标的优化调度数学模型,该模型为包含离散变量和连续变量的非线性混合整数规划问题,为快速获得高质量的可行解,提出一种由快速筛选和模型转化组成的阶段式求解方法。利用负荷裕度对发电机有功出力的灵敏度快速筛选出可提高负荷裕度的发电机集合,缩小离散变量的搜索范围;将原问题转化为混合整数线性规划子问题以及非线性规划子问题进行交替求解,得到需要调整的发电机数量及其出力。通过IEEE 118和IEEE 300节点系统进行测试,结果表明所提控制模型和求解方法可有效提高电力系统负荷裕度,减少可行解中包含的发电机调整数量,与分支定界法的对比验证了所提求解方法的快速性和有效性。

面向光伏能量收集应用的实时MPPT预估算法研究

对于环境中存在的各种类型能量源,其往往具有不同的阻抗特性以及输出功率范围。为了提高能量收集系统的能量萃取能力,合理的接口电路设计是关键。基于此,通过对环境中光伏(Photovoltaic,PV)能量源微弱直流特性以及高效率收集和转化的研究,在传统开路电压法(Open-Circuit Voltage,OCV)的基础上,结合输入电压纹波控制,提出了一种可实时最大功率点追踪(Maximum Power Point Tracking,MPPT)的预估算法。该预估算法根据能量源的输出特性,采用了分数开路电压法(Fractional Open-Circuit Voltage,FOCV),并根据纹波大小动态调节变换器的工作模式,实现阻抗匹配。为了尽可能减小因采样带来的能量损失,采用可片上全集成的较小的采样电容,并逐周期的进行开路电压采样和计算,实现了对源功率变化的高精度追踪。仿真结果表明,所提出的追踪算法能够实时监测能量源的状态,具有高的追踪速度和追踪精度,且采样时间仅需100 ns。能量源功率在1μW~10 mW范围内变化时,最短的追踪时间仅需4.37μs,追踪精度可达99.7%。

短线法预制节段梁匹配线形控制测量技术研究

短线匹配法节段梁预制线形控制是悬臂拼装桥梁成桥线形满足设计要求的先决条件。施工时,梁体因几何尺寸、高程等变化而发生角度偏转,导致竖向及水平线形偏离设计要求。通过对节段梁线形控制理论和空间坐标转换方式的研究,给出了节段梁匹配调节精准控制方法和误差分析方法,实现相邻节段之间空间坐标的精准匹配。

基于模糊控制的闪蒸罐PID控制器设计与仿真

PID控制器依照经验进行整定的方式需要花费大量时间和精力,而工业被控对象大都存在随时间变化、非线性等特性,PID控制的效果并不理想。以闪蒸罐压力控制为研究对象设计FUZZY-PID控制器。仿真结果表明:在PID调节后有超调情况下,FUZZY-PID控制器调节时间缩短约341.80 s,超调量减小约4.62%;在PID调节后无超调情况下,FUZZY-PID控制器调节时间缩短约395.60 s。抗干扰实验结果表明:在加入白噪声后,FUZZY-PID控制器与PID控制器控制效果差距不甚明显,都比较稳定,在同一时刻加入脉冲扰动后,FUZZY-PID控制器所需调节时间较PID控制器缩短约70.70 s,调节时间更短,更加稳定。说明相较于传统PID控制器,FUZZY-PID控制器调节时间更短、超调量更小、更加稳定。

基于SORT算法的图像轨迹跟踪混合控制方法

当目标物体被其他物体部分或完全遮挡时,目标的有效特征点数量会逐渐减少,跟踪器无法继续准确地锁定目标,导致目标轨迹中断。为此,文中研究基于SORT算法的图像轨迹跟踪混合控制方法。选取FCOS算法,利用特征金字塔结构,依据检测头层输出的目标分类得分、位置回归结果以及中心度检测图像目标。将目标检测结果作为卡尔曼滤波器的输入,利用离散控制过程系统描述视频图像中的目标运动状态,预测目标轨迹。利用SORT算法控制图像目标检测结果与目标轨迹预测结果进行级联匹配与IoU匹配,输出匹配成功的目标,即图像目标轨迹跟踪结果。实验结果表明,该方法可有效地跟踪视频图像目标轨迹,未出现ID变更情况,轨迹中断占比低于0.2%。

基于防洪-通航协同的长江中游航道整治方法

针对长江中游河段面临的通航和防洪双重问题,分析了长江中游航道治理特点,基于水流连续性方程和运动方程,推导分析了调整型和守护型等传统航道治理措施对水深、水位的影响,提出守护型、调整型和疏浚措施相结合的航道整治方法,分析了其对通航和防洪的影响。结果表明,相对于仅采用传统整治措施,“守、调、疏”相结合的航道整治方法使得航槽水深明显增加、断面水位则明显降低,有利于防洪和通航双重目标的协同实现。

Research on Network Delays of Networked Control Systems

In networked control systems (NCS), the main problem is time delays induced by communication network, which can deteriorate the performance of the systems, even cause the systems instability. If we know the exact network delays, we can compensate for their effect by modifying the parameters of the controller. Hence how to get the knowledge of these delays in the network is critical. This paper analyzed the different characteristics of network delays from sensor to controller and from controller to actuator and presented the methods of online evaluation of these delays. The experiment shows these methods are valid.

Bucket Group Effect of the Composite Multi-bucket Structure

As a novel type of foundation in beach and shallow sea, the bucket structure is especially suitable for complex conditions such as soft clay ground and the worse types of sea environments. In this paper, the bearing capacity of a multi-bucket structure is studied by experiments with a single bucket and four-bucket foundation in a saturated sand layer. Based on the experimental data and numerical analysis results, the bearing capacity behavior and the bucket group effect are compared and analyzed. Furthermore, some influential factors, such as the soil type, the ratio of length to diameter L/D, the ratio of the bucket spacing to the bucket diameter S/D, and the bucket number are introduced and their effects on the multi-bucket structural capacity are investigated. The vertical static capacity adjustment factor is introduced to evaluate the bucket group effects of the multi-bucket foundation.

Design of an Intelligent Usage Parameter Control in ATM Networks

This paper presents the principle of the fuzzy associate memory controlled leaky bucket (FAMLB) and several concepts for Usage Parameter Control (UPC) in ATM networks. The multiplex weight and random fuzzy rules adjustment method in the system architecture are introduced. The conclusions show that the FAMLB is a better dynamic method of UPC than the traditional ones.

节段预制悬臂拼装连续梁线形控制技术与实施

针对悬臂拼装短线法预制、施工、合龙段线形控制难度大、精度要求高的问题,结合郑州东四环快速化工程项目节段预制悬臂拼装连续梁桥施工实例,基于精细化有限元分析与短线法理论,提出了施工线形及多种纠偏措施的主梁线控技术。通过精细化分析与现场实测数据的对比,提出不同的线形纠偏方案,并选取合适方法对悬臂拼装连续梁的线形进行有效控制,最后经过线形控制及纠偏得到良好的合龙线形。研究表明,运用空间三维坐标转换原理,得到理论安装线形,通过有限元施工阶段模拟,可为悬臂拼装节段梁的受力及线形参数提供参考;结合不同方法的特点充分利用各方法的优点共同控制线形变化,有效提高线形控制的精度和灵活性。

论海底大地控制点GNSS/A定位联合平差方法的原理和应用(特邀文章)

为分析海面换能器位置误差对海底大地控制点定位精度的影响规律,我们提出了GNSS声学(GNSS/Acoustic,GNSS/A)定位联合平差(joint adjustment,JA)方法.针对联合平差方法理论证明不足及无深海数据验证的问题,本文进一步阐述了联合平差方法的原理,给出了联合平差方法严密的优越性证明和精度评定公式.最后采用松花湖数据和南海数据进行验证,联合平差方法可以提高传统GNSS/A方法2%~26%的定位精度,展示联合平差方法在湖区和深海区的应用效果.

基于多层连通性模型的动态调控参数优化方法

油田生产优化技术是快速制定高效开发方案的重要基础。为应对老油田多井多层系等复杂开发情况,根据油水井物质守恒方程和Buckley-Leverett前缘推进理论,提出了多层连通性模型动态调控参数优化方法,通过压力求解获得井间流量分布,含水饱和度追踪计算油水动态,采用遗传退火进化算法优化求解连通性参数。矿场实例测试表明,提出的动态调控参数优化方法,与基础方案相比,累计产油增加433.82×104m3,净现值增量44.77%,该方法具有较好的实用性,可为水驱剩余油挖潜,稳油控水等开发方案编制提供支持。

基于深度学习的大电网断面功率快速自动调整方法

由于复杂大电网关键输电断面的功率调整工作量大、重复性高,计算速度难以满足在线辅助决策需求。基于深度学习理论,提出了一种对断面功率调整数据进行特征自学习进而实现大电网断面功率快速自动调整的方法。首先,采用反向等量配对法模拟人工调整操作,构建深度学习所需的海量数据集。然后,在机组灵敏度、调整量等约束条件下筛选出复杂大电网中参与功率调整的有效机组集合。在此基础上,以决定系数为指标构建最优回归模型准确预测出机组出力调整值,从而实现了断面功率的快速自动调整。最后,以中国某实际区域大电网的省间断面功率调整为例对所提方法进行验证。仿真结果表明,最优模型的决定系数和断面功率调整成功率均较为理想,大大缩短了断面功率调整时间,且调整效率不受系统运行方式和断面实际功率与目标功率差值的影响。

单船拖曳可控源电磁数据自适应分频匹配滤波消噪方法

海洋可控源电磁法(MCSEM,Marine Controlled-Source Electromagnetic Method)是一种工业化的主动源海洋电磁勘探方法,近年来在海底油气资源探测中收效显著,通过测量海底地下介质的电阻率变化,能够有效降低地震勘探方法的多解性.MCSEM的工作方式主要有单船拖曳与双船拖曳两类.单船拖曳信号具有强时变特征,近、中、远收发距信号强度变化极大.由于海水环境较为复杂,数据受到洋流、背景场、仪器等多种因素干扰,使得小收发距数据信噪比较高,中、远收发距数据信噪比较低,因此MCSEM数据随机干扰压制方法的研究难点在于适应数据的强时变特征.本文利用发射机数据与接收机数据的时间(空间)和频率对应关系,提出基于正则化条件和衰减函数约束的自适应分频匹配滤波方法.该方法首先通过计算原始接收机数据基频的振幅随偏移距变化(MVO,Magnitude Versus Offset)曲线获取衰减函数,然后利用该衰减函数将发射机所有频点数据进行振幅衰减,减低MCSEM发射机与接收机数据对应振幅的强时变差异,最后利用基于整形正则化条件的自适应匹配滤波方法压制接收机数据中的强振幅随机噪声.模型数据与实际数据的处理结果表明,本文提出的方法能够有效压制MCSEM数据中不同收发距的随机噪声干扰,保护具有强时变特征的接收机数据,提升整体数据质量.

医疗设备全程质量控制管理体系与资源配置的匹配度分析

目的:探讨不同医疗设备全程质量控制管理体系与医疗设备资源配置的匹配度。方法:对广东省内4家医院的医疗设备全程质量控制管理体系(分别标注为管理体系1、管理体系2、管理体系3和管理体系4)采用多阶段分层随机抽样方法进行调研分析,建立医疗设备全程质量控制管理体系与资源配置匹配度指标评价体系,并使用嫡权法确定指标权重,建立耦合度测度模型,计算医疗设备质量控制管理体系与资源配置的匹配度。结果:4种医疗设备质量控制管理体系匹配度从高到低依次为管理体系1(0.5067)、管理体系2(0.4717)、管理体系3(0.4219)和管理体系4(0.3413)。结论:4种类型的医疗设备全程质量控制管理体系中管理体系1与资源配置的匹配度最高,医疗设备得到相对合理的配置。

基于驱替单元的水驱油藏动用状况分类评价方法

针对油田进入特高含水后期阶段,剩余油高度分散,无效循环不断加剧,剩余油和无效循环均赋存于“井间层内”的问题,无论是挖掘剩余油还是治理无效循环,水驱开发调整都必须聚焦于“井间层内”,不断向精细化方向发展。为了精细分析和量化评价水驱油藏动用状况,提出了驱替单元是最小可控单元的概念,分析了驱替单元的5个控制因素,明确了驱替单元与其所属领地的关系。通过研究将含水率和采出程度作为驱替单元分类评价的关键指标,应用含水率和采出程度建立了分类评价标准,并且在数值模拟计算结果的基础上,对每个驱替单元进行分类评价,形成了基于驱替单元的水驱油藏动用状况分类评价方法。应用该方法对实际油藏L区块进行了评价,并对具体井别提出了调整措施,评价结果可有效指导每个最小可控单元注水、堵水、增注、调剖等控制调整措施的实施。

基于倾向性评分匹配方法探讨产时发热对硬膜外自控镇痛产妇母婴结局的影响

目的通过倾向性评分匹配(PSM)方法探讨产时发热对硬膜外自控镇痛(PCEA)产妇母婴结局的影响。方法选取2019年8月—2020年8月遵义市妇幼保健院和湖北省妇幼保健院收治的阴道分娩初产妇600例,均行PCEA,根据产时发热发生情况分为发热组78例和未发热组522例。比较2组临床资料及母婴结局。结果发热组与未发热组体质指数(BMI)、产程、镇痛时长、阴道指检次数、新生儿出生体质量比较,差异有统计学意义(P<0.01);通过PSM 1∶1匹配,发热组与未发热组均为71例,2组临床资料比较,差异无统计学意义(P>0.05)。发热组鼓膜体温在产程进展3 h时出现上升,至4 h起出现产时发热。发热组住院时间长于未发热组,分娩后血清白介素-6(IL-6)水平、抗生素使用率高于未发热组,新生儿出生1 min后Apgar评分低于未发热组(P<0.01);2组产钳、侧切占比,缩宫素使用率、产后出血量、新生儿科入住率、胎儿宫内窘迫综合征发生率比较,差异无统计学意义(P>0.05)。结论基于PSM结果显示,产时发热对PCEA产妇母婴结局有一定影响,可加重母体炎症,增加抗生素使用率,延长住院时间,还会影响新生儿身体状况。