Analysis on the Pressure Fluctuation Law of a Hydraulic Exciting System with a Wave-exciter

A hydraulic exciting system with a wave exciter has been constructed in order to study the hydraulic vibra- tion law. The system consists of an oil source, wave-exciter and oil cylinder, and is controlled by a wave-exciter. The working principle of the hydraulic exciting system and wave exciter has been analyzed, and its excitation process has been illustrated. The law of every pipe＇s pressure fluctuation of the system is obtained by experiment. The theo- retical analysis and experimental data prove that the pipeline pressure periodically changes and the pipeline pressure fluctuation frequency is independently controlled by the excitation frequency of the wave-exciter. Every pipelinc＇s pressure wave is produced by system flow fluctuation and water hammer coupling. The pressure fluctuation rules of the system provide a theoretical basis for the study of the associated liberation system.

Vessel fusion tracking with a dual-frequency high-frequency surface wave radar and calibrated by an automatic identification system

High-frequency surface wave radar（HFSWR） and automatic identification system（AIS） are the two most important sensors used for vessel tracking.The HFSWR can be applied to tracking all vessels in a detection area,while the AIS is usually used to verify the information of cooperative vessels.Because of interference from sea clutter,employing single-frequency HFSWR for vessel tracking may obscure vessels located in the blind zones of Bragg peaks.Analyzing changes in the detection frequencies constitutes an effective method for addressing this deficiency.A solution consisting of vessel fusion tracking is proposed using dual-frequency HFSWR data calibrated by the AIS.Since different systematic biases exist between HFSWR frequency measurements and AIS measurements,AIS information is used to estimate and correct the HFSWR systematic biases at each frequency.First,AIS point measurements for cooperative vessels are associated with the HFSWR measurements using a JVC assignment algorithm.From the association results of the cooperative vessels,the systematic biases in the dualfrequency HFSWR data are estimated and corrected.Then,based on the corrected dual-frequency HFSWR data,the vessels are tracked using a dual-frequency fusion joint probabilistic data association（JPDA）-unscented Kalman filter（UKF） algorithm.Experimental results using real-life detection data show that the proposed method is efficient at tracking vessels in real time and can improve the tracking capability and accuracy compared with tracking processes involving single-frequency data.

Research of Power Take-off System for “Sharp Eagle Ⅱ” Wave Energy Converter

The " Sharp Eagle” device is a wave energy converter of a hinged double floating body. The wave-absorbing floating body hinges on the semi-submerged floating body structure. Under the action of wave, the wave-absorbing floating body rotates around the hinge point, and the wave energy can be converted into kinetic energy. In this paper, the power take-off system of " Sharp Eagle Ⅱ” wave energy converter (the second generation of " Sharp Eagle”) was studied, which adopts the hydraulic type power take-off system. The 0-1 power generation mode was applied in this system to make the " Sharp Eagle Ⅱ” operate under various wave conditions. The principle of power generation was introduced in detail, and the power take-off system was simulated. Three groups of different movement period inputs were used to simulate three kinds of wave conditions, and the simulation results were obtained under three different working conditions. In addition, the prototype of " Sharp Eagle Ⅱ” wave energy converter was tested on land and in real sea conditions. The experimental data have been collected, and the experimental data and simulation results were compared and validated. This work has laid a foundation for the design and application of the following " Sharp Eagle” series of devices.

Analysis on the Meso-scale System Activity and the Structure Characteristics of A Short-time Rainstorm

By using the rainfall data in the regional automatic station,FY-2E satellite data,NCEP reanalysis data,the evolution features and the structure characteristics of a meso-scale convective system(MCS) which happened on May 6 in 2010 in Loudi City of Hunan Province were analyzed.The results showed that MCS was the important influence system for the generation and development of strong precipitation.The equivalent blackbody brightness temperature(TBB) field of satellite inversion could directly reflect the convective activity of cumulus,the precipitation distribution and the intensity characteristics in the rainstorm process.TBB low value belt had the good corresponding relationship with the rainstorm falling zone.The disturbance flow field and the height field which passed Barnes band-pass wave filtering represented that there existed the obvious high-layer anticyclonic circulation and the low-layer cyclonic circulation near the rainstorm zone.The divergence in the high layer and the convergence in the low layer enhanced the occurrence and development of MCS.In addition,the disturbance temperature field revealed the main source of energy which the occurrence and development of strong convective weather needed.

Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

不确定电液伺服系统的时变输出约束自适应滤波控制

针对电液伺服系统位置跟踪控制中存在的输出约束和不确定性问题,提出一种基于正切型时变障碍Lyapunov函数的输出约束自适应滤波控制方法。构造具有时变约束边界的正切型时变障碍Lyapunov函数,通过时变边界函数的参数设置,使系统输出具有较好的瞬态和稳态性能;设计径向基函数(RBF)神经网络及权重自适应学习律,在线逼近由模型不确定性和未知干扰组成的复合干扰,并将逼近值用于反馈控制;采用二阶指令滤波反步法设计状态反馈控制律和误差补偿机制,避免反步设计中“计算爆炸”的问题,同时消除滤波误差,提高系统位置跟踪精度;依据Lyapunov稳定性理论证明闭环系统中所有误差信号的收敛性。仿真结果表明:系统的稳态误差在所提方法下约为3.48×10^(-8)m,相比于其他控制方法,跟踪误差始终约束在时变的约束边界内,跟踪精度和控制性能均得到提升。

矿场压裂停泵水击信号滤波效果评价指标研究

采用水击压力波监测方法进行压裂诊断时,为了准确评价停泵水击压力波信号滤波算法的性能,针对国内某水平井的实测水击信号及其对滤波结果的实际需求,采用倒谱响应分辨率R_(C)和倒频率峰值信噪比R_(QSN)作为水击信号滤波效果的评价指标,以该指标和滤波效果的同步性为基本依据,根据指标对滤波效果的灵敏性评价滤波指标的可靠程度。研究结果表明,高频水击信号的R_(C)和R_(QSN)与井场信号滤波效果正相关,且呈现出良好的灵敏性,因此能够采用倒谱响应分辨率和倒频率峰值信噪比来评价矿场压裂停泵水击压力波高频信号的滤波效果。研究结果为现场信号特征分析、滤波算法优化及滤波模型现场应用的有效性评估提供了技术途径。

液压式波浪能装置发电控制策略试验研究

以一套含有多个发电机组的波浪能发电装置液压系统样机为研究对象,介绍系统组成及运行原理,并通过研发的液压测试平台对两种发电控制策略开展试验研究。首先,对流量控制阀变开度发电控制策略开展试验,结果表明采用该策略可使输出电压在一段时间内趋于稳定,提高发电质量,同时提出两种基于液压测试平台获取比例流量控制阀有效输入电信号的方法。其次,通过在液压系统样机输出端接入多个发电机组实现梯度发电控制策略,数据结果证实可有效提高瞬时输出功率,提升波浪能发电装置在不同波况下的自适应性,同时对在实海况中实现该控制策略的条件进行初步讨论。

流量与含沙量对浮筒网式旋转过滤器水力性能与过滤性能的影响

过滤器是保障微灌系统正常运行的核心设备,而水头损失与过滤效率是评价其性能的2个关键指标。为探明泵前过滤器—浮筒网式旋转过滤器的水力性能和过滤性能,采用方差分析、极差分析、主效应多重比较法对比分析了浮筒网式旋转过滤器在滤网孔径为0.150 mm时,5种不同含沙量、5种不同流量下的水头损失与过滤效率,并确定了试验条件下的最优工况。结果表明:对水头损失而言,流量比含沙量影响大;对过滤效率而言,含沙量的影响更大,且水头损失与过滤效率均随含沙量与流量的增大而增大;最优工况为流量930 L/h、含沙量2.0 g/L,此工况下对应的水头损失为0.281 m,过滤效率为84.01%,可以保证在有良好的过滤效率的同时具有较小的水头损失,从而实现节能减排,高效灌溉的目的。

用于海上风力发电机的改进船载登乘栈桥主动波浪补偿方法

在维修海上风力发电机时发现传统船载登乘栈桥主动波浪补偿系统存在求解精度低、控制响应慢的问题。为此,提出基于Denavit-Hartenburg法的栈桥空间位姿解算方法,并使用参考系转换的方法降低逆运动求解难度;设计前馈Smith预估补偿PID控制器,解决传统PID控制器跟踪动态信号存在的长延时问题;结合船载登乘栈桥的动力学模型,采用Simulink软件进行仿真控制实验。实验结果表明,在低海况且控制系统的延迟时间取0.24 s时,改进后的船载登乘栈桥主动波浪补偿方法使栈桥的最大偏移量减小了79.3%,以平均偏移标准差作为栈桥稳定性评估依据时其稳定性提升了79.6%。由此可见:该补偿方法具有良好的波浪补偿能力,同时还具有快速求解和时间延迟包容性等优点,有利于提高实时补偿系统的整体控制精度和响应速度。

超短波通信系统射频兼容设计与原理性验证

针对超短波通信系统邻近通道工作时对主频干扰与宽带噪声干扰的抑制需求,综合考虑系统收发应用,提出了一种采用捷变频射频滤波技术和射频干扰对消技术的射频兼容工作方法,并研制出射频兼容设备验证样机。经验证测试,该系统可同时抑制主频干扰与宽带噪声干扰,对接收通信中心频率3 MHz外的主频信号实现30 dB的抑制,对接收频点的宽带噪声信号实现不小于45 dB的抑制,有效提升超短波通信链路兼容工作频率间隔和通信效能,也可扩展用于其他类似射频系统内兼容工作设计。

立式板框压滤机驱动系统技术改造

针对HVPF-40型立式板框压滤机运行过程中设备不能连续运行、操作困难、人工劳动强度大等问题,对其系统进行研究分析。通过增加驱动力、调整驱动分布等措施对设备进行局部改造,实现了设备自动化、连续化运行,降低了劳动强度,确保装置安全环保绿色生产。

基于高频方波注入的永磁同步电机控制优化

提出一种利用高频正交方波电压注入静止坐标系的内置式永磁同步电动机无传感器控制的新方案。该方法是对传统高频旋转正弦电压注入法的改进,通过离散高频电流来建立整个信号过程。提出了一种不含低通滤波器的位置估计方法,并减小了高通滤波器引起的相移。该无传感器控制方法受到数字滤波器的不利影响会减少,可以解决当前基于静止坐标系的注入方法的常见缺点。

融合毫米波雷达和惯性传感器的行人定位系统研究

为老年人在发生紧急情况时可以得到及时救援,本文对行人惯性导航进行研究,可以获得行人的实时位置。传统的卫星定位,定位精度较低且受遮挡物影响,不能满足现代城市的室内外定位需求。本文设计了融合毫米波雷达和惯性传感器的行人定位系统,在捷联惯性导航解算基础上采用扩展卡尔曼滤波融合磁力计和毫米波雷达的数据得出最佳估计值。设计了两组不同运动轨迹的测试实验,验证系统的有效性,并通过7次不同运动情况下的重复实验验证了系统的稳定性,该系统在47 m范围内的定位误差在3%以内,在400 m范围内的定位误差在5%以内,基本满足定位需求。

基于噪声抑制的电液位置伺服系统自抗扰控制方法

测量噪声对扩张状态观测器带宽的限制是影响电液伺服系统自抗扰位置控制器性能的关键问题。为此,提出了一种基于噪声抑制扩张状态观测器的改进自抗扰控制方法。建立电液伺服系统非线性模型,通过坐标变换构造链式积分器结构,明确电液伺服系统“总扰动”。引入低通滤波器抑制高频测量噪声,利用滤波后的位置信号构建改进型扩张状态观测器,补偿滤波器导致的相位滞后,分离状态反馈与扰动估计,增加新的扰动估计调节参数,调和观测器高带宽、高估计性能与噪声放大间的矛盾。采用李雅普诺夫稳定性理论证明了闭环系统的稳定性。仿真与试验结果表明,在系统受扰状态下,与传统LADRC相比,本文所提出控制方法扰动抑制能力更强,位置跟踪精度更高,为自抗扰控制器的工程应用提供了参考。

矿用自卸卡车转向蓄能器及蓄能器过滤装置的技术改造

为了减少矿用自卸卡车蓄能器气囊损坏后引起的液压油系统污染和转向系统故障,分析了气囊式蓄能器的内部结构、工作原理及在卡车转向液压系统中的作用,以及对气囊式蓄能器破损后污染液压系统情况;提出了在卡车转向系统与蓄能器之间油路上加装过滤装置的必要性。结果表明:通过在730E卡车转向系统安装过滤装置后,转向系统可以有效地避免因蓄能器气囊损坏后引起的液压油系统污染,同时二次净化了液压系统,减少了卡车转向系统故障,节约了维修成本。

产品液压系统地面循环清洗设备设计及应用

某液电一体结构件的液压系统采用原装进口油滤滤芯作为工艺滤芯进行循环清洗,滤芯消耗量大、成本高、采买及更换时间较长。为实现提质、增效、降本的目的,通过对产品结构分析,发现可采取地面循环的方式实现液压系统循环清洗,经过市场调研、方案设计、方案验证,最终实现了清洗设备的设计及应用。

液压滤中创新型高效过滤介质的设计与性能分析

文章旨在设计一种创新型高效过滤介质用于液压系统中的过滤器,以提高过滤性能和延长设备使用寿命,采用多孔介质的设计理念并结合纳米技术和复合材料制备工艺,制备了一种新型过滤介质,通过试验测试和性能分析验证了该过滤介质在过滤效率、压力损失和使用寿命等方面的显著优势,该研究成果对液压系统的稳定运行和设备维护具有重要意义。

液压凿岩系统对岩土介质冲击性能的仿真分析

凿岩机内部结构的变化使得岩石的吸能效率产生巨大差异。以液压凿岩系统为研究对象,考虑入射纵波能量通过此系统冲击岩土介质的过程,基于波动理论分析应力波的传播特性。建立活塞-钎具-岩土系统的动力学模型,并对其进行显式动力学冲击仿真分析,分别施加矩形入射波和指数入射波,探讨不同入射波形加载条件下能量通过液压凿岩系统传输到岩土介质中的效率。结果表明:指数入射波传播通过系统后的透射波能量较大,进而可得指数波加载条件下对岩土介质的凿击深度更大。该研究为液压凿岩机的冲击性能优化奠定了基础。

液压污染控制系统建模

分析了液压系统污染侵入特点 ,建立了液压污染控制系统通用模型 ,导出了液压油污染控制过程动态方程 ,提出了等效过滤比、等效污染物侵入速率等概念 ,给出了合理选择液压污染控制系统有关参数的公式 ,从而对液压过滤系统的设计和过滤器参数的选择具有指导意义。