海洋液压冲击打桩锤机-液系统联合仿真分析

以近海施工的液压冲击打桩锤为研究对象,基于刚体动力学、牛顿碰撞理论以及液压-气动理论,建立某型海洋打桩锤机械冲击系统和液压系统模型,并通过AMESim和ADAMS软件,建立了打桩锤的虚拟样机,完成了液压冲击打桩锤机-液系统的多次沉桩过程的仿真分析.沉桩仿真结果与现场沉桩记录充分接近,验证了所建立模型仿真分析的合理性.

机-电-液馈能悬挂系统性能分析

馈能是提升坦克装甲车辆悬挂减振性能与减少能量消耗、提高续航能力的有效方案之一,根据机-电-液馈能悬挂系统的工作原理,根据工作原理建立悬挂系统数学模型并搭建流、固、热、磁多场耦合分析模型,分析不同参数对悬挂系统阻尼特性和馈能特性的影响;分析结果表明:机-电-液馈能悬挂系统在正弦激励下具有良好的阻尼特性;旋转液压执行器排量、液压变速/泵/马达排量和少齿差行星齿轮传动比对系统阻尼特性有较大影响,对系统馈能特性影响不大,在不同参数下可达到较高能量回收功率;液压泵/马达容积效率是影响系统馈能特性的关键参数,系统能量回收效率随液压泵/马达容积效率的降低而显著下降,提高液压泵/马达容积效率是保证该系统高能量回收的关键。

典型机-电-液系统测试性建模及诊断策略设计方法

履带式传动装置是车辆的重要组成部分,其健康程度影响车辆性能和驾驶人员安全。为保障履带式传动装置工作性能,以多信号模型为基础,提出履带式传动装置测试性模型与分析方法。首先,建立履带式传动装置基本信号流框图和故障模型,构建整体诊断树;然后,基于测试性软件平台对履带式传动装置测试性模型进行分析、评估。分析结果表明,该方法可以有效地实现履带式传动装置故障诊断,通过反馈修正模型可以提高装置的测试性能力,为实际装置的故障检测提供了理论基础。

薄板绕制高压容器工艺中的压紧力控制及机─液系统设计原则

高压容器变压紧力绕制经实践证实是经济可靠的工艺方法，而准确地调控压紧力是保证工件质量的关键。阐明根据工艺特点采用工业流量伺服阀和蓄能器控制油缸压力可以满足稳定、快速、准确的要求。对液压控制系统进行了分析并得出系统设计的参数选择原则。

Technology of load-sensitivity used in the hydraulic system of an all-hydraulic core rig

The existing hydraulic system always have problems of temperature rise,runningstability and anti-interference of the implementation components,reliability of hydrauliccomponents,maintenance difficulties,and other issues.With high efficiency,energysaving,reliability,easy operating,stable running,anti-interference ability,and other advantages,the load-sensitive hydraulic system is more suitable for coal mine all-hydrauliccore rig.Therefore,for the technical development of the coal mine all-hydraulic core rig,the load-sensitive technology employed by the rig should be of great significance.

Advanced removal of organic and nitrogen from ammonium-rich landfil leachate using an anaerobic-aerobic system

A novel system coupling an up-flow anaerobic sludge blanket(UASB) and sequencing batch reactor(SBR) was introduced to achieve advanced removal of organic and nitrogen from ammonium-rich landfill leachate. UASB could remove 88.1% of the influent COD at a volumetric loading rate of 6.8 kg COD·m-3·d-1. Nitritation–denitritation was responsible for removing 99.8% of NH+4-N and 25% of total nitrogen in the SBR under alternating aerobic/anoxic modes. Simultaneous denitritation and methanogenesis in the UASB enhanced COD and TN removal, and replenished alkalinity consumed in nitritation. For the activated sludge of SBR, ammonia oxidizing bacteria were preponderant in nitrifying population, indicated by fluorescence in situ hybridization(FISH) analysis. The Monod equation is appropriate to describe the kinetic behavior of heterotrophic denitrifying bacteria,with its kinetic parameters determined from batch experiments.

Improved control of intelligent excavator using proportional-integral-plus gain scheduling

Consider the design and implementation of an electro-hydraulic control system for a robotic excavator, namely the Lancaster University computerized and intelligent excavator (LUCIE). The excavator was developed to autonomously dig trenches without human intervention. One stumbling block is the achievement of adequate, accurate, quick and smooth movement under automatic control, which is difficult for traditional control algorithm, e.g. PI/PID. A gain scheduling design, based on the true digital proportional-integral-plus (PIP) control methodology, was utilized to regulate the nonlinear joint dynamics. Simulation and initial field tests both demonstrated the feasibility and robustness of proposed technique to the uncertainties of parameters, time delay and load disturbances, with the excavator arm directed along specified trajectories in a smooth, fast and accurate manner. The tracking error magnitudes for oblique straight line and horizontal straight line are less than 20 mm and 50 mm, respectively, while the velocity reaches 9 m/min.

On the Mechanism of Latex Particles Formation in Polymerization in Heterogeneous Monomer-Water System

Investigations show that in monomer water heterogeneous systems polymerization, located in the interface, can disperse the system. Following polymerization in the density gradient field it is shown that in such systems latex particles are nucleated from monomer microdroplets, containing a certain amount of polymer molecules. It could be considered that, independently of the nature of the monomer itself, polymerization in monomer water statistic heterogeneous systems modulate emulsion polymerization process.

Design of portable and intelligent infuser device for rapid fluid transfusion based on micro-electro-mechanical system

Objective： A novel portable and intelligent fluid resuscitation infuser is proposed in this paper. It satisfies the demands of long time use in harsh environment, such as traffic accident, natural disaster, battlefield, evacuation, pre-hospital emergency and so on. Methods： Miniature linear motor and liquid blood cartridge compose the pump body. It＇s based on the biological impedance method to measure and control, which resolve the disadvantage of traditional infuser device： large power dissipation, big size, AC power supply only and can＇t be use in field. The whole device weights 250 gram and sizes as two mobile phone together Results： Model device experiment shows： six number 7 standard AAA size alkaline batteries will run the pump for approximately 8-10 h at 6 liters per hour; IV bag can be placed at any position of patient, even under the stretcher. Conclusion： It provides accurate and reliable intravenous infusion for fwst-aid treatment in field.

Study on co-simulation model of forging manipulator based on virtual prototyping

Based on the characteristics of integrated virtual prototype technology, the mechanical system sub-model, the hydraulic system sub-model and the control system sub-model of a forging manipula- tor system have been built using a variety of software, and a forging manipulator mtrltidisciplinary co- simulation model has been also built using a method of simulation models interface. Then the simu- lation and experiment are finished, and the result of the experiment is in good agreement with the re- sult of the simulation. It shows that the co-simulation model established can simulate accurately pa- rameter changes in real time during the moving of the forging manipulator such as displacement, ve- locity and pressure flow, which is of important significance for the optimized design of the forging manipulator system to establish the models.

Low-frequency ride comfort of vibratory rollers equipped with cab hydro-pneumatic mounts

Based on the advantages of hydraulic and pneumatic mounts,a new hydro-pneumatic mount(HPM)is proposed to improve the low-frequency ride comfort of vibration rollers.Through the experiment of the vibratory roller,a nonlinear vehicle dynamic model working on off-road soil grounds is then established to assess the HPM's ride comfort in the low-frequency region.Two indices,the power spectral density(PSD)acceleration and root mean square(RMS)acceleration of the operator vibration and cab shaking,are chosen as objective functions in both the frequency and time regions.The research results show that when the cab isolations are equipped with the HPM,the RMS values of the operator's seat,cab's pitch and roll angles are reduced by 35%,42%and 53%;and the maximum PSD of the operator's seat,cab's pitch and roll angles are decreased by 39%,59%and 65%,respectively.Consequently,the characteristics of the nonlinear damper and high-static stiffness of HPM can greatly reduce the operator vibration and cab shaking in the low-frequency region when compared to the vibratory roller's cab using the rubber mounts.

Telemonitoring and hemodynamic monitoring to reduce hospitalization rates in heart failure： a systematic review and meta-analysis of randomized controlled trials and real-world studies

Background Heart failure is a significant problem leading to repeated hospitalizations. Telemonitoring and hemodynamic monitoring have demonstrated success in reducing hospitalization rates, but not all studies reported significant effects. The aim of this systematic review and meta-analysis is to examine the effectiveness of telemonitoring and wireless hemodynamic monitoring devices in reducing hospitalizations in heart failure. Methods ＆ Results PubMed and Cochrane Library were searched up to 1st May 2017 for articles that investigated the effects of telemonitoring or hemodynamic monitoring on hospitalization rates in heart failure. In 31,501 patients （mean age： 68 ± 12 years; 61% male; follow-up 11 ± 8 months）, telemonitoring reduced hospitalization rates with a HR of 0.73 （95% CI： 0.65-0.83; P 〈 0.0001） with significant heterogeneity （I2 = 94%）. These effects were observed in the short-term （≤ 6 months： HR = 0.77, 95% CI： 0.65-0.89; P 〈 0.01） and long-term （≥ 12 months： HR = 0.73, 95% CI： 0.62-0.87; P 〈 0.0001）. In 4831 patients （mean age 66 ± 18 years; 66% male; follow-up 13 ± 4 months）, wireless hemodynamic monitoring also reduced hospitalization rates with a HR of 0.60 （95% CI： 0.53-0.69; P 〈 0.001） with significant heterogeneity （I2 = 64%）.This reduction was observed both in the short-term （HR = 0.55, 95% CI： 0.45-0.68; P 〈 0.001; I2 = 72%） and long-term （HR = 0.64, 95% CI： 0.57-0.72; P 〈 0.001; I2 = 55%）. Conclusions Telemonitoring and hemodynamic monitoring reduce hospitalization in both short- and long-term in heart failure patients

Improvements of drilling fluid processing for cable-suspended electromechanical drills

Deep ice drilling in Polar Regions plays a key role in paleo-climate, microbiological and glaciological researches. For deep ice and subglacial coring the special purpose-built electromechanical cable-suspended drills with bottom-hole circulation are designed and explored. Used at present drilling fluid circulation systems are specified by very high fluid wastes during processing. Measurements in deep drilling projects in Antarctic and Greenland ice sheets showed that 25%-40% of the drilling fluid, pumped into the hole, is retrieved to the surface with cable and drill, and up to 45% of retrieved fluid goes to waste. This leads not only to increasing of the fluid consumption and cost of the project in general but also to severe contamination of air, surface and near-surface snow-firn layers at the drilling site. In order to reduce wastes and environmental impact, it is proposed to modify drilling fluid processing system by avoiding of evaporation and leakages of fluid as far as practicable. Drilling fluid is prepared and pumped into the hole according to predetermined program on semiautomatic mode, and volume and density of blended and pumped into the hole drilling fluid are measured continuously. Components of the drilling fluid are stored and mixed in the special closed containers equipped by pressure relief valves. Separation of drilling fluid from ice cuttings is carried out by two steps: firstly, fluid is separated with hydro extractor and then with thermal separator. To reduce the amount of removed drilling fluid with cable special squeezing collar is installed on the borehole mouth. All these arrangements are able to decrease drilling fluid wastes in many times.

Basic Characteristics of the Hydraulic-Driven Forceps for Force Feedback

A surgical manipulator has widely been used for laparoscopic surgery. It has been chosen mainly for the use in supporting human operations and in robot systems like the da Vinci surgical system. These manipulator systems are suitable for careful work, but they have a few problems. One of the problems is that the manipulator is not equipped with haptic sensing functions. Therefore, the operator must know the advanced techniques for visually detecting the physical contact state during surgical operations. These haptic sensing functions thus need to be incorporated into a surgical manipulator. We have developed hydraulic-driven forceps with a micro bearing and a bellows tube that can convey haptic sense to the operator. This system can measure the small forces acting on the tips of the forceps using Pascal＇s principle. A model of the system is provided from the relationship between the internal pressure of the bellows tube and the refraction angles of the forceps. It was confirmed using this model that the developed system makes it possible to estimate both the strength and the direction of the external force applied to the forceps by measuring the internal pressure of the bellows tube. An operator using a three-dimensional haptic device was able to feel the force response during an experiment in which they used the forceps to hold a blood vessel. This report describes the most appropriate method for letting the operator feel the force conveyed by using our system.

Energy-Saving Design for Hydraulic Tube Bender

Generally speaking, hydraulic control systems can be divided into two different driving concepts. The first one is the well-known hydraulic valve-controlled system and the second one is the pump-controlled system. The former possesses the feature of fast dynamic response. However, the poor energy-saving performance is its major fault. On the contrary, the hydraulic pump-controlled system has the significant advantage of energy-saving which meets the current demand in modem machine design. In this paper, the simulation analysis using MatLab/SimuLink and DSHplus software for a newly developed energy-saving hydraulic tube bender is conducted. Instead of the conventional fixed displacement hydraulic pump, the new hydraulic tube bender utilizes an internal gear pump with AC servomotor as its driving power source. In the new energy-saving hydraulic circuit, the use of conventional pressure relief valve and unloading valve are no longer necessary since the demanded flow-rate and pressure output can be precisely obtained by continuously changing the speed of the AC servomotor. In addition, two closed-loop control schemes using fuzzy sliding-mode controller are adopted and compared. To compare the energy-saving control systems, such as load-sensing control system, constant supply pressure control scheme and conventional hydraulic control scheme. Furthermore, the simulation results also show that the newly developed hydraulic tube bender can save up to 43% of energy consumption in a working cycle as compared to the conventional hydraulic tube bender.

NUMERICAL PREDICTION OF AIRCRAFT HYDRAULIC SYSTEM BASED ON THERMAL DYNAMIC ANALYSIS

A mathematical model of principal elements of the aircraft hydraulic system is presented based on the heat transfer theory. The dynamic heat transfer process of the hydraulic oil and the pump shells within an aircraft hydraulic system are analyzed by the difference method. A kind of means for the prediction to variational trends of the aircraft hydraulic system temperature is provided during operation. The numerical prediction and simulation under the operational conditions are presented for ground trial running and the decelerated operation in flight. Computational results show that there is a good coincidence between the experimental data and the numerical predictions.

广义二次调节及其特征研究

基于液压二次调节系统的基本原理,分析其基本特征,根据机、电、液相似理论,将此概念向机械传动系统和电力传动系统推广,提出了广义二次调节的概念。结合工程实践,以可逆运行的机—电—液系统为例,对广义二次调节概念进行了深入分析,研究了二次调节系统的一般特征。

Modeling and parameter estimation for hydraulic system of excavator's arm

A retrofitted electro-hydraulic proportional system for hydraulic excavator was introduced firstly. According to the principle and characteristic of load independent flow distribution(LUDV) system,taking boom hydraulic system as an example and ignoring the leakage of hydraulic cylinder and the mass of oil in it,a force equilibrium equation and a continuous equation of hydraulic cylinder were set up. Based on the flow equation of electro-hydraulic proportional valve,the pressure passing through the valve and the difference of pressure were tested and analyzed. The results show that the difference of pressure does not change with load,and it approximates to 2.0 MPa. And then,assume the flow across the valve is directly proportional to spool displacement and is not influenced by load,a simplified model of electro-hydraulic system was put forward. At the same time,by analyzing the structure and load-bearing of boom instrument,and combining moment equivalent equation of manipulator with rotating law,the estimation methods and equations for such parameters as equivalent mass and bearing force of hydraulic cylinder were set up. Finally,the step response of flow of boom cylinder was tested when the electro-hydraulic proportional valve was controlled by the step current. Based on the experiment curve,the flow gain coefficient of valve is identified as 2.825×10-4 m3/(s·A) and the model is verified.

A graphic monitoring method for electric power of VVVF hydraulic system

In order to online monitor the running state of variable voltage and variable frequency(VVVF)hydraulic system,this paper presents a graphic monitoring method that fuses the information of variable frequency electric parameters.This paper first analyzes how the voltage and current of the motor stator change with the operation conditions of VVVF hydraulic system.As a result,we draw the relationship between the electric parameters(voltage and current)and power frequency.Then,the signals of the voltage and current are fused as dynamic figures based on the idea of Lissajous figures,and the values of the electric parameters are related to the features of the dynamic figures.Rigorous theoretical analysis establishes the function between the electric power of the variable frequency motor(VFM)and the features of the plotted dynamic figures including area of diagram,area of bounding rectangle,tilt angle,etc.Finally,the effectiveness of the proposed method is verified by two cases,in which the speed of VFM and the load of VVVF hydraulic system are changed.The results show that the increase of the speed of VFM enhances its three-phase electric power,but reduces the tilt angle of the plotted dynamic figures.In addition,as the load of VVVF hydraulic system is increased,the three-phase electric power of VFM and the tilt angle of the plotted dynamic figures are both increased.This paper provides a new way to online monitor the running state of VVVF hydraulic system.

Motion control of thrust system for shield tunneling machine

The thrust hydraulic system of the prototype shield machine with pressure and flow compound control scheme was introduced. The experimental system integrated with proportional valves for study was designed. Dynamics modeling of multi-cylinder thrust system and synchronous control design were accomplished. The simulation of the synchronization motion control system was completed in AMESim and Matlab/Simulink software environments. The experiment was conducted by means of master/slave PID with dead band compensating flow and conventional PID regulating pressure. The experimental results show that the proposed thrust hydraulic system and its control strategy can meet the requirements of tunneling in motion and posture control for the shield machine, keeping the non-synchronous error within ±3 mm.