Safety and effectiveness of neuromuscular electrical stimulation in cardiac surgery:A systematic review

BACKGROUND Lack of mobilization and prolonged stay in the intensive care unit(ICU)are major factors resulting in the development of ICU-acquired muscle weakness(ICUAW).ICUAW is a type of skeletal muscle dysfunction and a common complication of patients after cardiac surgery,and may be a risk factor for prolonged duration of mechanical ventilation,associated with a higher risk of readmission and higher mortality.Early mobilization in the ICU after cardiac surgery has been found to be low with a significant trend to increase over ICU stay and is also associated with a reduced duration of mechanical ventilation and ICU length of stay.Neuromuscular electrical stimulation(NMES)is an alternative modality of exercise in patients with muscle weakness.A major advantage of NMES is that it can be applied even in sedated patients in the ICU,a fact that might enhance early mobilization in these patients.AIM To evaluate safety,feasibility and effectiveness of NMES on functional capacity and muscle strength in patients before and after cardiac surgery.METHODS We performed a search on Pubmed,Physiotherapy Evidence Database(PEDro),Embase and CINAHL databases,selecting papers published between December 2012 and April 2023 and identified published randomized controlled trials(RCTs)that included implementation of NMES in patients before after cardiac surgery.RCTs were assessed for methodological rigor and risk of bias via the PEDro.The primary outcomes were safety and functional capacity and the secondary outcomes were muscle strength and function.RESULTS Ten studies were included in our systematic review,resulting in 703 participants.Almost half of them performed NMES and the other half were included in the control group,treated with usual care.Nine studies investigated patients after cardiac surgery and 1 study before cardiac surgery.Functional capacity was assessed in 8 studies via 6MWT or other indices,and improved only in 1 study before and in 1 after cardiac surgery.Nine studies explored the effects of NMES on muscle strength and function and,most of them,found increase of muscle strength and improvement in muscle function after NMES.NMES was safe in all studies without any significant complication.CONCLUSION NMES is safe,feasible and has beneficial effects on muscle strength and function in patients after cardiac surgery,but has no significant effect on functional capacity.

All-Electric Subsea Control Systems and the Effects on Subsea Manifold Valves

Subsea development is moving constantly toward simplification,digitalization,and cost-out strategies because the exploration and production of hydrocarbons are moving toward deeper and remote sea water areas.Usage of all-electric subsea technology instead of hydraulic technology is growing and will be the future of subsea systems due to the former’s environmental and functional advantages and reduced costs.The benefits of all-electric subsea systems are health,safety,and environment(HSE)and improved reliability,flexibility,and functionality compared with traditional hydraulic-electrical systems.Existing electrohydraulic technology for a typical subsea system,hydraulic and electric actuators,and subsea manifold valves including valve types and selection philosophy have been reviewed in this paper.Some major worldwide oil companies such as Equinor and Schlumberger have successful experiences with subsea electric actuators.Considering the benefits of all-electric technology especially in terms of cost and HSE,as well as successful experiences of two major oil companies,further research in this area is warranted.One of the gaps in existing reviewed literature is the effect of using all-electric actuators for manifold valves.Thus,three main questions related to electric actuator selection,requirement of safety integrity level(SIL),and effect of using electric actuators on manifold valve selection have been addressed and answered.Forty hydraulic actuated manifold valves from nine past subsea projects in different parts of the world,mainly Africa and Australia,have been selected for the analysis of all-electric actuators.Results show that 93%of the valves require spring-return electric actuators,whereas 7%can be operated with conventional electric actuators without any spring.The manifold valves do not require SIL certification because they are not connected to an emergency shut down system.Introducing the electric actuators to the manifold valve will not change the valve selection philosophy.

Valves replacement operation in treatment of electrical storm induced by rheumatic valves disease

Objective： To present a case of electrical storm （ES） in a female patient with rheumatic valve disease. Methods： A female patient with severe rheumatic valve disease suffered an unexpected ES. She received more than 50 electrical shocks for repeated cardiac arrests due to ES over 16 hours. Then she received beta-blocking agent treatment and had an operation of double valves replacement. Results： ES was suppressed by sympathetic blockade with beta-receptor blocker and finally disappeared after the double pathological valves had been replaced. Conclusion： Increased sympathetic activity plays an important role in the genesis of electrical storm and sympathetic blockade may effectively suppress ES. However, the most important thing in the treatment of ES is to identify and eliminate the underlying cause of ES.

Control Power Source of PV-10 Piezoelectric Crystal Valve

Parameters of the power source used to control PV-10 piezoelectric crystal valve are following DC output voltage： 0 - 120 V, continuously controllable, linear enlargement factor of input direct current voltage： approximate 25 times, the accuracy of DC output voltage： ±5%, manual control and automatic control.

A Study on the Static Characteristics of Typical Composite High Speed On-Off Valves

Natural properties of high speed on-off valves can be described through their on-off behavior and spool movement (static and oscillating) characteristics. High speed on-off valves can be combined with actuators in systems into four typical types of composite valves whose static characteristics are related not only to the structures of the single valves and the composite ones, but also to the PWM control modes. It is proved that the composite valves have similar features as those of servo valves. The nonlinear specific properties of single valves composited can be completely compensated by the suitable PWM control modes.

Structure optimization and flow field simulation of plate type high speed on-off valve

There is a relatively complex flow state inside the high speed on-off valve,which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool,causing cavitation and vortex and other phenomena.These phenomena will affect the stability of the internal flow field of the plate valve and the flow characteristics of the high speed on-off valve.Aiming at the problems of small flow rate and instability of internal flow field,a new spool structure was designed.The flow field models of two-hole and three-hole plate spools with different openings were established,and software ANSYS Workbench was chosen to mesh the model.The standard k−εturbulence model was selected for numerical simulation using FLUENT software.The pressure distribution and velocity distribution under the same pressure and different opening degree were obtained.The structure and parameters of the optimization model were also obtained.The stability analysis of flow field under different pressure was carried out.The results demonstrate that the three-hole spool has a similar flow field change with the two-hole spool,but it does not create a low pressure zone,and the three-hole spool can work stably at 2 MPa or less.This method improves the appearance of low pressure area and oil backflow in the process of high speed opening and closing of spool.The stability of flow field and the flow rate of high speed switch valve are improved.Finally,the products designed in this paper are compared with existing hydraulic valve products.The results show that the three-hole plate type high speed on-off valve designed in this paper maintains the stability of the internal flow field under the condition of 200 Hz and large opening degree,and realizes the increase of flow rate.

TEST METHOD OF HIGH-SPEED ON-OFF VALVE DYNAMIC CHARACTERISTICS

According to the valve port features of high speed on-off valve and its actions, the valve port can be simplified into an a-type half bridge construction. A method that tests the dynamic characteristics of the high speed on-off valve by the output pressure signal of the a-type half bridge is proposed. Having analyzed the factors related to the dynamic characteristics of an a-type half bridge, a rule for designing the outlet chamber＇s volume is worked out. According to the rule, a test stand is built to test the self-developed high-speed on-off valve. From the test results, it can be seen that with the outlet chamber＇s volume controlled by the rule the rise time of the pressure signals driven by signals with different frequencies changes very little. The test results conform to the simulation results, which nroves the correctness of the method.

Research Progress of Electromagnetic Field and Electromagnetic Compatibility of UHVDC Converter Valves

特高压直流换流阀的电磁场和电磁兼容性是其研制过程中的关键问题,国内外学者对此进行了系统研究。中国电力科学研究院成功研制出中国首个具有完全自主知识产权的800 kV/4 750 A特高压直流（ultra high voltage directcurrent,UHVDC）换流阀。针对电磁场和电磁兼容问题,利用三维电场边界元法实现换流阀寄生参数的提取,通过理论计算、数值仿真及试验测试等多种手段,对瞬态电磁干扰等问题提出了解决方案,为换流阀的研制和工程应用提供了必要的技术支撑。总结了上述领域的研究成果,对未来特高压直流换流阀电磁兼容领域的研究课题与解决方案提出了一些建议和设想。

Research on the Characteristics of Pneumatic PCM Control Valve

Based on the flow characteristic equation of air in adiabatic process, the characteristics of modulated on-off valve in a pneumatic pressure control system is analyzed theoretically. The relationship between the parameters and performance of the system is obtained, and it is also observed that the control error is proportional to the on-off period of the valve.

基于小波包分析和优化KNN的电动开度阀故障检测方法

针对以微控制器MCU为控制核心的电动开度阀控制系统难以集成高效且计算量小的故障检测子系统的问题,基于小波包变换和优化K近邻(K-Nearest Neighbor,KNN)算法提出了一种电动开度阀故障检测方法。对阀门振动信号进行小波包变换,计算小波包节点的能量值与其重构信号的时域特征参数。根据Pearson系数筛选出两种与能量强相关的故障特征参数:峰峰值与均方根,并将两者作为KNN算法的样本评价指标;通过对评价指标进行加权优化了KNN算法的距离计算公式,分别在MATLAB和实验样机中进行故障检测测试,对应最高分类准确率分别为92.5%与86.7%。结果表明:实验测试与仿真分析具有较好的一致性,该故障检测方法的优势在于计算量小、故障识别率较高,并能有效地应用于以MCU为核心的电动开度阀控制系统。

华龙一号安注系统电动截止阀可靠性试验及评估研究

作为核反应堆系统中的关键设备,阀门在核反应堆系统中起着至关重要的作用,其可靠性直接决定着核反应堆安全以及人员安全。本文针对华龙一号安注系统电动截止阀,采用3个试验样机开展可靠性试验,通过模拟使用工况下的冷热态寿命试验,获得了该型阀门的典型失效——阀座内漏,并基于试验数据采用小子样试验的半经验评估方法完成了可靠性评估,确定该安注系统电动截止阀全寿期无故障动作360次的可靠度大于0.99。

基于滑模扰动观测器的阀门开度预测控制

针对电动阀门在运行过程中,由于外部干扰、系统参数变化、摩擦力等非重复干扰的影响而难以达到高精度控制的问题,提出一种基于滑模扰动观测器的预测控制方法。通过对阀门驱动原理进行深入研究,构建阀门的数学模型,根据模型中电机电流与总负载扰动的正相关性,以电机电流、阀门转速为输入量,采用滑模扰动观测器对系统总负载扰动进行估计。设计模型预测控制器,对扰动估计值进行补偿,实现对阀门开度控制的准确性,鲁棒性以及对总扰动值跟踪的快速性。理论分析、仿真和试验表明:观测器仅0.001 s便跟踪到了设定值,收敛速度快,阀门开度精度误差在0.2%以内,完全达到控制目标,开度控制效果良好。可充分验证该控制方法在不同的负载扰动下,依然能使电动阀门保持良好的开度控制精度以及抗扰动能力。

核级典型电动截止阀FMECA及试验验证

作为核反应堆系统中的关键能动设备,阀门在核反应堆系统中起着至关重要的作用,其安全性直接决定着核反应堆安全及人员安全。本文针对安注系统电动截止阀,基于使用特点对其开展故障模式、影响及危害性分析(FMECA),找出其结构中潜在的故障模式及其原因与影响,并根据失效分析结果有针对性地开展寿命试验,以激发潜在的故障,验证分析结果并获得该阀最为典型的失效模式。

电动可变配气系统输出协方差控制策略

提出一种针对连续可变气门正时(VVT)的新型电动可变配气系统且基于模型的闭环控制,以提高系统调节速度和控制精度.首先,使用基于新息的自适应卡尔曼滤波参数辨识对电机系统参数进行辨识,利用辨识的参数建立了可变配气系统的控制模型.其次,设计了基于模型的电动可变配气系统控制算法,即输出协方差约束(OCC)算法.最后,验证了该算法的效果,在仿真中对比了OCC算法与比例-积分-微分(PID)算法、线性二次型跟踪(LQT)算法,在台架试验中对比了OCC控制器与PID控制器的控制效果,结果表明:对不同转速下目标相位调节进行仿真,PID算法在转速为1 000、3 000和4 000 r/min下稳态误差均大于OCC算法,LQT算法在转速为3 000 r/min和4 000 r/min下调节速度小于OCC算法,且在变转速下OCC算法相位保持更好,相位偏差更小,说明OCC算法相比PID算法和LQT算法具有更好的转速适应能力.台架试验中,在相位角向上调节时,OCC算法比PID算法响应时间降低了42.8%;在相位角向下调节时,OCC算法比PID算法响应时间降低了75.0%.

±500 kV直流换流阀用饱和电抗器温度场与电场仿真研究

高压直流换流阀饱和电抗器在工作过程中发热量大、电场分布不均匀,使其成为阀厅的安全隐患。为改善饱和电抗器的温升效应,文中以实际±500 kV直流换流阀用饱和电抗器为研究对象,建立了改进的流体场与温度场耦合模型,该仿真模型综合考虑流体传热、空气对流散热、绕组焦耳热和铁心涡流热损耗等实际因素,仿真计算电抗器各部件的温度场分布及其影响因素。现场验证表明该模型计算结果更接近实际工作状况。还建立静电场仿真模型,仿真计算电场畸变情况。温度场结果表明:饱和电抗器的铁心温度最高、环氧树脂次之、冷却水管路温度最低;铁心最高温度可达342 K。提高冷却水入口流速是降低饱和电抗器温度的有效方法,阀塔冷却系统的入水流速设置为1 m/s时可达最佳的冷却效果。环氧树脂、铁心和冷却水管的最高温度均与冷却水入口温度呈线性递增关系,实际工作中应使冷却水的初始温度越低越好。电场结果表明:环氧树脂与铁心交界面处出现明显的电场畸变现象,最大电场强度可达1.26×105 V/m。应在此处采取均压措施以防止电场集中而导致的局部温度过高。文中所得结论可为直流换流阀用饱和电抗器的设计提供参考。

浅水受限区水下油气田开发方案

针对国内浅水油气资源开发环境影响及空间受限等问题,本文提出了国产浅水水下生产系统的总体设计方案。通过对浅水水下生产系统关键设备结构进行分析,提出了一种满足受限区海域开发要求的环境友好型设计思路。结果表明:通过系统和总体布置的设计,国产浅水水下生产系统与深水相比在单体重量、作业方式、维护检修方面更加经济。

恒压腹腔镜手术辅助系统

随着腹腔镜手术在临床上的广泛应用,逐渐暴露出电子气腹机的局限性:一方面气腹机在建立气腹的同时会造成腹腔压力冲击,使体内部分组织受到损伤;另一方面,气腹机调节腹压时容易超调,腹腔压力控制的稳定性不够。针对腹腔镜手术中腹腔压力控制稳定性、柔顺性问题,提出了恒压腹腔镜手术辅助系统:对传统气腹机结构做出改进,用电动调节阀取代原本的多级电磁阀组合结构,实现渐变式流量调节;分析了阀口流量特性并对腹腔建模,提出了渐变式阀门函数,能提前关闭阀门,避免了由阀门滞后带来的腹压超调;最后系统在渐变式恒压控制策略下保证手术过程腹压的稳定。实验表明系统在该策略下能够稳定的工作。

语音阀对气管切开患者肺通气影响的临床研究

目的应用电阻抗成像技术(EIT)和肺功能仪评估佩戴语音阀(SV)对气管切开患者肺通气的影响。方法选取首都医科大学附属北京康复医院呼吸与危重症医学科2023年1月至9月收治的能耐受佩戴SV 30min以上的气管切开患者纳入研究,共39例,应用EIT评估比较佩戴SV前和佩戴SV期间肺通气指标的差异:潮气量阻抗(TIV)、呼气末肺阻抗(EELI)、通气中心(COV)、通气不均一指数(GI)和通气延迟区域(RVD);分别经气管切开套管和佩戴SV经口测试肺功能,比较肺通气指标的差异:潮气量(VT)、分钟通气量(MV)、最大分钟通气量(MVV)、用力肺活量(FVC)、第1秒用力呼气容积(FEV_(1))、第1秒用力呼气容积/用力肺活量(FEV_(1)/FVC)和呼气峰值流速(PEF);应用可穿戴设备观察佩戴SV前和佩戴期间的呼吸频率、血氧饱和度、心率和血压变化,并比较佩戴前后血气分析变化。结果气管切开患者佩戴SV期间其肺复张指标EELI(694.88±138.82)AU、COV(54.28±0.99)%和肺潮气量指标TIV数值(1753.19±527.91)AU较佩戴前显著增加,差异有统计学意义(均P<0.05),反应通气均一性指标GI和RVD差异无统计学意义(均P>0.05);肺功能指标佩戴SV经口测量VT(0.52±0.03)L、MV(11.63±0.55)L/min、MVV(37.01±3.23)L/min和FVC(1.97±0.78)L较经气管切开套管测量显著升高,差异有统计学意义(均P<0.05);佩戴SV前和佩戴期间呼吸频率、血氧饱和度、心率和血压以及佩戴前后血气分析没有明显变化,差异无统计学意义(均P>0.05)。结论SV可以促进气管切开患者肺复张,改善通气功能,可能与SV恢复上气道完整性,增加呼吸做功有关。

加料泵旁通阀PID自动控制系统

作为烟丝生产工艺中的重要环节,添加香糖料可对烟丝质量起到关键性作用。为了保证生产中香糖料的流量控制精度,在加料管路中使用旁通阀PID自动控制。通过实际生产跟踪,加料泵旁通阀PID自动控制系统与电动调节针形阀的配合调控,使料液流量具有更快速、灵敏的调控反应,提高了对加料环节的流量控制。

一种阀门电动执行器智能调试装置的设计

阀门是管道系统中不可缺少的控制部件,随着行业自动化和智能化发展的需求,阀门电动执行器在精确驱动控制阀门开启、关闭或者调节中扮演了重要的角色,为确保阀门与电动执行器功能配合运行完整性和安全性,出厂前需要对阀门进行100%的调试试验。常规的调试装置包含了多个工步,导致工作效率低且安全系数相对较小,因此,为了提高执行器的调试效率,本文设计了一种针对380V交变电流工况下阀门电动执行器调试的智能装置,通过实际生产验证:此装置性能良好,减少了多个工步,节约了大量的调试准备时间,大大提高了阀门产品调试效率。同时,装置具有操作简单、安全系数高、易学易用、使用性强的特点。其兼备的自动计数功能,极大地方便了执行器的寿命试验实施,对类似产品的调试试验具有较大的工程应用价值。