主被动一体式模拟肺设计与测试

人工模拟肺是呼吸机设计开发和性能测试不可或缺的关键仪器设备.当前国内外模拟肺多数为被动模式,即仅能模拟人体无自主呼吸意识下的被动呼吸功能,且呼吸力学参数固定.针对以上问题,设计了一种呼吸力学参数连续可调的主被动一体式人工模拟肺模型.首先,设计并加工了人工模拟肺的外形结构,开发了基于步进电机的模拟肺驱动系统.其次,设计了基于LabVIEW的上位机控制软件,实现对步进电机的驱动控制和压力、流量信号的反馈处理.最后,搭建整体实验平台,实现了主动呼吸模式下快速呼吸、平静呼吸、深度呼吸这三种人体基本呼吸模式的模拟,测量潮气量与目标潮气量误差在±0.05%以内;设计了基于PID控制的模拟肺顺应性控制方法,实现了被动呼吸模式下不同顺应性时的跟随控制,维持目标顺应性误差在±15%以内.

羊胫骨慢性骨髓炎模型的构建及评价

背景:高原环境会影响骨髓炎患者的免疫功能和代谢状态,导致疾病进程的加速或复杂化。构建有效稳定的慢性骨髓炎动物模型对于慢性骨髓炎的实验研究至关重要。目的:在高原地区建立一种基于羊的慢性骨髓炎模型,以供毒性评估和治疗性研究。方法:15只健康绵羊,将鱼肝油酸钠和金黄色葡萄球菌悬液注射至左侧胫骨中段髓腔内建立慢性骨髓炎模型,采用大体观察、体质量及体温监测、血液感染指标检测、影像学评分及微生物培养等方法进行评估与分析。结果与结论:①造模后所有绵羊在早期均可观察到局部组织肿胀和病腿跛行症状,伴有不同程度的食欲减退现象;造模1周后绵羊体质量出现轻微下降,体温未见明显变化。②造模4 d后红细胞沉降率明显加快(P<0.05),1个月后逐渐恢复正常水平;造模后4 d内白细胞数量出现明显升高的趋势,1周后恢复到正常状态;造模后C-反应蛋白水平明显增加(P<0.05),至实验结束仍显著高于正常水平(P<0.05)。③15只绵羊均有典型骨髓炎的放射学表现,溶骨性病灶的边界模糊不清且形态不规则,呈现出一种低密度透亮区域,其中夹杂着密度增高且分布不均的坏死骨块影像,病变区域皮质骨部分出现了不同程度的骨膜反应现象。④13只绵羊培养出单一金黄色葡萄球菌,另2只绵羊培养出金黄色葡萄球菌和大肠杆菌。提示通过向绵羊胫骨骨髓腔内注入适量的金黄色葡萄球菌菌液,并结合局部植入异物棉线与鱼肝油酸钠,可在高原地区成功构建一种可靠的绵羊胫骨慢性骨髓炎动物模型。

表面修饰人工韧带以促进前交叉韧带重建后腱骨愈合的研究进展

前交叉韧带(anterior cruciate ligament, ACL)损伤在膝关节韧带损伤中最常见,通常为强大暴力所致,其损伤破坏膝关节稳定性,可引起关节软骨的退变及半月板损伤,严重者将发展为骨性关节病。现阶段在关节镜下行前交叉韧带重建(anterior cruciate ligament reconstruction, ACLR)是治疗前交叉韧带(ACL)损伤的金标准,临床上多采用以聚对苯二甲酸乙二醇酯(pET)为材料的LARS(ligament advanced reinforcement system)人工韧带对损伤的前交叉韧带进行手术重建,随访中短期效果较好,但移植物与宿主骨隧道生物愈合较差,难以达到术后移植物真正“韧带化”要求。对人工韧带进行涂层修饰改性可改善其亲水性和生物相容性进而可促进移植物与骨隧道的愈合。本文就对人工韧带行表面修饰以促进ACLR后腱骨愈合的研究进展作一综述。

煤体表面粗糙度对接触角和表面能的影响研究

为有效治理矿尘,改善作业环境,保障作业安全,以煤体表面粗糙度为研究对象,选取哈密褐煤、老公营子褐煤、安阳焦煤和赵固二矿无烟煤,采用非接触方式测量煤体被不同目砂纸打磨后的表面粗糙度,采用座滴法测量煤体表面被去离子水和丙三醇润湿后不同粗糙度的接触角,选用OWRK法计算煤体不同表面粗糙度的表面能,研究煤体表面粗糙度对接触角和表面能的影响。结果表明:随着煤体表面粗糙度逐渐增加,哈密褐煤、老公营子褐煤和赵固二矿无烟煤接触角逐渐减小,煤体表面能逐渐增大,而安阳焦煤接触角逐渐增大,表面能逐渐减小;褐煤呈亲水性,焦煤呈疏水性,无烟煤呈弱亲水性;煤样的变质程度既影响接触角的变化趋势和变化范围,又影响表面能性质;4种煤样的表面能和润湿性随表面粗糙度变化趋势相同,可以从表面能角度分析表面粗糙度影响煤体润湿的结果和规律;表面能与接触角负相关,随着表面能增加,4种煤样的接触角均减小。

基于粗糙度的煤体表面接触角数值模拟研究

煤尘是煤矿的七大灾害之一,它不仅影响作业人员的身心健康,还能致使发生煤尘爆炸。煤的润湿效果对除尘有很大的影响,已有研究表明煤的润湿效果与煤的润湿性、表面粗糙度和表面活性剂等有关。为了有效地解决井下煤尘问题,选取了亲水性的哈密褐煤、疏水性的安阳焦煤和弱亲水性的赵固二矿无烟煤作为研究对象,使用光学接触角形貌联用仪测量3种煤样的均方粗糙度,测定3种煤样的本征接触角,利用COMSOL数值软件构建二维物理模型,设置模拟条件,调整模拟参数,分析对比试验值和模拟值,验证COMSOL数值模拟的可行性,研究了煤体表面粗糙度对煤体表面接触角的影响。结果表明:数值模拟的液滴铺展过程、液滴铺展速度及液滴铺展形态和试验情况类似,但模拟接触角值比试验接触角值大;随着煤体表面粗糙度的增加,褐煤接触角从60.7°降低到50.9°,变化范围在10°左右,焦煤接触角从96.5°增加到112.7°,变化范围在16°左右,无烟煤接触角从89.7°降低到78.3°,变化范围在11°左右;同种表面活性剂对3种煤样接触角的模拟值和试验值具有相同的变化趋势,但模拟值比试验值大。采用数值模拟的方法,研究煤体表面粗糙度对煤体表面接触角的影响具有一定的可行性。煤体表面受粗糙度影响的润湿情况符合Wenzel模型。表面活性剂的存在不改变3种煤样的接触角随表面粗糙度变化的规律。

热害矿井巷道围岩冷水截流降温技术

为了缓解矿井热害问题,提出了向巷道围岩中置入冷水管,通过冷水管截流高温的方法来降低围岩温度。根据相似性原理搭建了高温围岩冷水截流降温实验系统,改变冷水流速、通入时长和围岩温度等进行实验;结合COMSOL模拟分析了冷水管不同管径、不同间距布局对巷道围岩冷水截流降温效果的影响。结果表明:其他条件不变时,围岩降温幅度随着冷水流速,通入时长以及围岩与冷水的温差的增大而增大;模拟实际巷道围岩冷水截流降温,在冷水管管径为10 cm,竖直方向间距为2.5 m时,降温后巷道壁面的平均温度为23.4℃。

柔性夹爪收缩与扩张过程的能耗研究

通过工控机的数据采集系统,结合传感器技术、信号处理技术等,搭建设备建立气体压力、流量等参数的在线测量系统,实现对测控系统的调节和控制。首先,分别采集柔性夹爪在收缩和扩张时不同初始压力下的压力与流量;然后,通过SigmaPlot绘出柔性夹爪压力流量图,并对柔性夹爪流量压力输出特性进行分析;最后,计算其气动功率,研究能耗规律。结果表明:对柔性夹爪进行收缩实验时,给定的初始压力与柔性夹爪产生的压力相差不大,气动功率损耗较小;对柔性夹爪进行扩张实验时,提供的初始压力通过真空发生器间接作用在柔性夹爪上,与柔性夹爪产生的压力相差较大,柔性夹爪达到规定压力时需要提供更大的初始压力;柔性夹爪收缩时比扩张时的气动功率损耗低。

动压轴承的莫顿效应建模和参数分析

首先,对可倾瓦动压轴承进行三维热弹流建模,并通过三维有限元算法求解转子-轴承系统的动力学和热变形,以达到在时域上预测莫顿效应的目的;其次,基于压缩机转子-轴承案例,验证了莫顿效应算法的有效性;最后,对轴承支点偏移系数、轴承间隙和供油温度进行参数分析,结果表明:增大支点偏移系数和轴承间隙可有效抑制莫顿效应,并减小转子的周向温差和振幅;降低供油温度虽可以降低转子的平均温度,但油膜黏度会随之增大,反而加剧了莫顿效应,增大了转子的周向温差和振幅。

基于分段拟合的煤自燃指标气体优选研究

为更加精确地得出煤自燃的临界温度并找出煤自燃各个阶段最优的指标气体,以此提高煤层自燃预测预报的准确性,选取西北某矿2号煤和3号煤典型煤样开展程序升温-气相色谱实验,采用分段直线拟合的方法,得出煤自燃过程中的耗氧速率突变点温度和氧化产物生成量激增点温度,在此基础上采用灰色关联度分析法对煤干裂温度之后的指标气体进行优选。结果表明:2号煤和3号煤的自燃临界温度分别为73.0℃和72.1℃,干裂温度分别为112.6℃和109.8℃;CO适用于2种煤样全温度下的预测预报;φ(C_(2)H_(4))/φ(C_(2)H 6)和C_(2)H_(4)是2号煤干裂温度之后较优的预测预报指标气体;φ(C_(2)H_(4))/φ(C 2H_(6)),C_(2)H_(4)和C_(2)H_(6)是3号煤干裂温度之后较优的预测预报指标气体。

Overall Life Cycle Comprehensive Assessment of Pneumatic and Electric Actuator

Pneumatic actuators and electric actuators have almost been applied to all manufacturing industries. The two kinds of actuators can replace each other in most fields, such as the point to point transmission occasion and some rotating occasions. However, there are very few research results about the advantages and disadvantages of two kinds of actuators under the same working conditions so far. In this paper, a novel comprehensive assessment method, named as overall life cycle comprehensive assessment （OLCCA）, is proposed for comparison and assessment of pneumatic and electric actuators. OLCCA contains mechanical properties evaluation （MPE）, life cycle cost analysis based on users （LCCABOU） and life cycle environmental impact analysis （LCEIA） algorithm in order to solve three difficult problems： mechanical properties assessment, cost analysis and environmental impact assessment about actuators. The mechanical properties evaluation of actuators is a multi-objective optimization problem. The fuzzy data quantification and information entropy methods are combined to establish MPE algorithm of actuators. Two kinds of pneumatic actuators and electric actuators with similar bearing capacity and similar work stroke were taken for example to verify the correctness of MPE algorithm. The case study of MPE algorithm for actuators verified its correctness. LCCABOU for actuators is also set up. Considering cost complex structure of pneumatic actuators, public device cost even method （PDCEM） is firstly presented to solve cost division of public devices such as compressors, aftercooler, receivers, etc. LCCABOU method is also effective and verified by the three groups of pneumatic actuators and electric actuators. Finally, LCEIA model of actuators is established for the environmental impact assessment of actuators. LCEIA data collection method and model establishment procedure for actuators are also put forward. With Simapro 7, LCEIA comparison results of six actuators can be obtained： Fossil fuels are the major environmental factor of pneumatic and electric actuators; Environmental impact of electric actuator is large than one of pneumatic actuator under the similar mechanical properties and working conditions of pneumatic and electric actuators. The results are correct and correspond with the actual mechanical properties of actuators. This paper proposes a comprehensive evaluation method of the actuators, which can solve the critical problem that similar electromechanical products are very difficult to be compared with each other from the angle of performance, cost and environment impact.

Analytical and Experimental Study on Complex Compressed Air Pipe Network

To analyze the working characteristics of complex compressed air networks, numerical methods are widely used which are based on finite element technology or intelligent algorithms. However, the effectiveness of the numerical methods is limited. In this paper, to provide a new method to optimize the design and the air supply strategy of the complex compressed air pipe network, firstly, a novel method to analyze the topology structure of the compressed air flow in the pipe network is initially proposed. A matrix is used to describe the topology structure of the compressed air flow. Moreover, based on the analysis of the pressure loss of the pipe network, the relationship between the pressure and the flow of the compressed air is derived, and a prediction method of pressure fluctuation and air flow in a segment in a complex pipe network is proposed. Finally, to inspect the effectiveness of the method, an experiment with a complex network is designed. The pressure and the flow of airflow in the network are measured and studied. The results of the study show that, the predicted results with the proposed method have a good consistency with the experimental results, and that verifies the air flow prediction method of the complex pipe network. This research proposes a new method to analyze the compressed air network and a prediction method of pressure fluctuation and air flow in a segment, which can predicate the fluctuation of the pressure according to the flow of compressed air, and predicate the fluctuation of the flow according to the pressure in a segment of a complex pipe network.

Optimization Study on a Single-cylinder Compressed Air Engine

The current research of compressed air engine（CAE） mainly focused on simulations and system integrations. However, energy efficiency and output torque of the CAE is limited, which restricts its application and popularization. In this paper, the working principles of CAE are briefly introduced. To set a foundation for the study on the optimization of the CAE, the basic mathematical model of working processes is set up. A pressure-compensated valve which can reduce the inertia force of the valve is proposed. To verify the mathematical model, the prototype with the newly designed pressure-compensated intake valve is built and the experiment is carried out, simulation and experimental results of the CAE are conducted, and pressures inside the cylinder and output torque of the CAE are obtained. Orthogonal design and grey relation analysis are utilized to optimize structural parameters. The experimental and optimized results show that, first of all, pressure inside the cylinder has the same changing tendency in both simulation curve and experimental curve. Secondly, the highest average output torque is obtained at the highest intake pressure and the lowest rotate speed. Thirdly, the optimization of the single-cylinder CAE can improve the working efficiency from an original 21.95% to 50.1%, an overall increase of 28.15%, and the average output torque increases also increases from 22.047 5 N · m to 22.439 N · m. This research designs a single-cylinder CAE with pressure-compensated intake valve, and proposes a structural parameters design method which improves the single-cylinder CAE performance.

Flow Characteristics of Expansion Energy Used Pneumatic Booster

The most common booster is called input pressure reduced （IPR） booster. However, this type of booster has its own shortages, such as its small output flow, when the boosting ratio is higher, the shortage becomes more distinct. Recent research on pneumatic boosters mainly focused on the factors that influence the characteristics of the boosters, some new kinds of pneumatic booster structures were designed, but the efficiency and output flow of these boosters are still not improved sufficiently. In order to improve the output flow of the pneumatic booster, a new kind of booster, expansion energy used （EEU） booster, is proposed. Non-linear differential equations of the pneumatic booster are set up. By using the software MATLAB/Simulink for simulation, the motion characteristics of the pistons, the characteristics of the output flow of the boosters are obtained for analysis of a principle. The principle, which is used to elevate the output flow of the two kinds of boosters, is that the average pressure of the air in the driving chambers of the EEU booster is higher than that of the IPR booster. The simulation and experimental research of the output flow characteristics are done. The simulation and experimental results are in a good accordance. And the simulation and experimental results show that when the air source pressure and the output pressure are set at 0.6 MPa and 0.8 MPa, respectively, with the increase of the terminal pressure of the air in the driving chamber, the output flow of the IPR booster ascends stably. As the terminal pressure of the air in the driving chamber goes up, the output flow of the EEU booster rises, and later it almost remains constant. In addition, with the same terminal pressure, the output flow of the EEU booster is greater than that of the IPR booster, and the difference decreases when the terminal pressure grows. At last, the output pressure is set at 0.8 MPa, under the optimum work state of the EEU booster, the output flow of the two kinds of boosters all declines with the rise of the boosting ratio. Furthermore, the output flow of the EEU booster is higher than that of IPR booster by 95 L/min approximately. The proposed research lays the foundation for optimistic of the EEU booster.

Efficiency Analysis of an Arrayed Liquid Piston Isothermal Air Compression System for Compressed Air Energy Storage

Compressed air energy storage(CAES)is an important technology in the development of renewable energy.The main advantages of CAES are its high energy capacity and environmental friendliness.One of the main challenges is its low energy density,meaning a natural cavern is required for air storage.High-pressure air compression can effectively solve the problem.A liquid piston gas compressor facilitates high-pressure compression,and efficient convective heat transfer can significantly reduce the compression energy consumption during air compression.In this paper,a near isothermal compression method is proposed to increase the surface area and heat exchange by using multiple tube bundles in parallel in the compression chamber in order to obtain high-pressure air using liquid-driven compression.Air compression with a compression ratio of 6.25:1 is achieved by reducing the tube diameter and increasing the parallel tube number while keeping the compression chamber cross-sectional area constant in order to obtain a high-pressure air of 5 MPa.The performances of this system are analyzed when different numbers of tubes are applied.A system compression efficiency of 93.0%and an expansion efficiency of 92.9%can be achieved when 1000 tubes are applied at a 1 minute period.A new approach is provided in this study to achieve high efficiency and high pressure compressed air energy storage.

地震区油气管道的应变与位移检测技术

为了对地震区油气管道所承受的附加应力进行有效检查,提出基于惯性导航技术的应变及位移检测方法,可对油气管道全线进行有效检测,及时发现管道位移和应变集中点。通过使用搭载惯性导航单元的内检测器对管道进行检测,并与地面标记点、里程计进行组合导航数据融合得到精确的管道中心线坐标后,进一步对管道弯曲应变进行计算,可有效查找管道全线的应变变化及位移区域,并能够检测应变及位移变化量。通过牵引试验验证了应变检测的正确性及数据重复性,该方法为地震区长输油气管道的安全运行提供了有效保障。

基于[火用]分析的储罐式压缩空气储能系统的成本优化

压缩空气储能(Compressed air energy storage,CAES)系统的成本问题备受关注,几乎所有CAES系统的研究都以高压空气和热能的形式来储存能量。对于CAES系统,利用地下岩洞或深水水域等天然环境形成的容器,系统的储存成本较低,但也因此对地理环境具有较高要求;而对于更具普适性的储罐式CAES系统,则受限于高压储气罐成本,经济性有待加强。基于[火用]储存成本的分析对储罐式CAES系统成本的优化方法进行研究。提出两种降低储罐式CAES系统成本的策略,一是尽可能多的以热能形式储存[火用];二是将高压空气冷却后储存在低温气罐中。结果表明,与传统的CAES系统相比,采用高温压缩、低温储存的方式,CAES系统储能成本可以降低52%。考虑真实气体效应的影响,最优的储存压力约为21 MPa。

天然气掺氢输送系统氢脆研究进展

天然气掺氢输送不仅能够有效解决弃风弃光、减少温室气体排放问题,还能够实现大规模、低成本的氢气输送,也是实现“双碳”目标的重要方式,但掺入氢气会对现有天然气管道系统及相关输送设备带来氢脆危险。基于天然气掺氢输送系统的结构组成,归纳了氢脆发生的机理,调研了天然气掺氢输送系统的管道及焊缝、阀门、压缩装置、存储装置、终端装置等发生氢脆的研究现状,概述了防止氢脆发生的应对措施,并对天然气掺氢输送系统的发展前景进行了展望。研究结果可为中国天然气掺氢输送的规模化与市场化发展、提高管道输氢技术与装备的研发水平提供参考,促进氢经济的安全发展。

Study on air flow dynamic characteristic of mechanical ventilation of a lung simulator

As an important life support treatment, mechanical ventilation is usually adopted in clinics. With the development of the res-piratory diagnostic and treatment technologies, air flow dynamics of mechanical ventilation is usually referenced in the evaluation of pulmonary status and assessment of respiratory therapy. In order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, in this paper, a new mathematical model of mechanical ventilation system was set up. Furthermore, a prototype mechanical ventilation system for an artificial simulating lung was designed and experimentally studied. Lastly, in order to improve the ventilation efficiency and provide a reference for pulmonary diagnostics, the air flow dynamics of the mechanical ventilation system was illustrated through simulation and experimental studies. The study can be helpful to the optimization of the mechanical ventilation system.

New advances in in-situ thermal desorption technology for contaminated soil

With the development of ecological civilization and economic construction,remediation of contaminated soils has caused more and more concern of scientists and engineers.Situ thermal desorption is a mature and effective technology which is especially suitable for the contaminated soil of relocated chemical plant[1,2],Compared with in-situ chemical oxidation and ectopic thermal desorption,the in-situ thermal desorption has stronger applicability and higher repair efficiency.The main applications of the in-situ thermal desorption technology are semi-volatile and volatile organic pollutants.

Energy conversion characteristics of reciprocating piston quasi- isothermal compression systems using water sprays

Air compressors are vital and have numerous industrial applications. Approximately 8% of the annual operating electricity consumption in industrial countries is constituted by due to the use of air compressors. Because the poor heat transfer to the environment in the rapid compression process, the compression is non-isothermal, the efficiency of compressors is restricted. To improve their efficiency and achieve isothermal compression, this study proposes energy conversion reciprocating piston quasiisothermal compression using a water spray. First, a mathematical model of a reciprocating piston compressor with water sprays was established. Through experimental investigation and simulations, the mathematical model was validated. The energy conversion characteristics of the reciprocating piston compressor were then studied. To reduce compression power and enhance compression efficiency, it was first discovered that the critical parameters were the input pressure of the driving chamber, water spray mass, and compression volume ratio, which were then evaluated thoroughly. The higher the inlet pressure of the driving chamber, the faster the air compression velocity. Additionally, the compression efficiency was elevated as the water spray mass was gradually increased for a given compression volume ratio. When the compression volume ratio was increased from 2 to 3,the compression power increased from 172.7 J/stroke to 294.2 J/stroke and the compression efficiency was enhanced from 37.3%(adiabatic) to 80.6%. This research and its performance analysis can be referred to during the parameter design optimisation of reciprocating piston quasi-isothermal compression systems using water sprays.