Clinical effectiveness of a pneumatic compression device combined with low-molecular-weight heparin for the prevention of deep vein thrombosis in trauma patients:A single-center retrospective cohort study

BACKGROUND:To investigate the clinical effectiveness of a pneumatic compression device(PCD)combined with low-molecular-weight heparin(LMWH)for the prevention and treatment of deep vein thrombosis(DVT)in trauma patients.METHODS:This study retrospectively analyzed 286 patients with mild craniocerebral injury and clavicular fractures admitted to our department from January 2016 to February 2020.Patients treated with only LMWH served as the control group,and patients treated with a PCD combined with LMWH as the observation group.The incidence of DVT,postoperative changes in the visual analogue scale(VAS)score,and coagulation function were observed and compared between the two groups.Excluding the influence of other single factors,binary logistic regression analysis was used to evaluate the use of a PCD in the patient’s postoperative coagulation function.RESULTS:After excluding 34 patients who did not meet the inclusion criteria,252 patients were were included.The incidence of DVT in the observation group was significantly lower than that in the control group(5.6%vs.15.1%,χ^(2)=4.605,P<0.05).The postoperative VAS scores of the two groups were lower than those before surgery(P<0.05).The coagulation function of the observation group was significantly higher than that of the control group,with a better combined anticoagulant effect(P<0.05).There were no significant differences between the two groups in preoperative or postoperative Glasgow Coma Scale scores,intraoperative blood loss,postoperative infection rate,or length of hospital stay(P>0.05).According to logistic regression analysis,the postoperative risk of DVT in patients who received LMWH alone was 1.764 times that of patients who received LMWH+PCD(P<0.05).The area under the receiver operating characteristic(AUROC)curve of partial thromboplastin time(APTT)and platelet(PLT)were greater than 0.5,indicating that they were the influence indicators of adding PCD to prevent DVT.Excluding the influence of other variables,LMWH+PCD effectively improved the coagulation function of patients.CONCLUSIONS:Compared with LMWH alone,LMWH+PCD could improve blood rheology and coagulation function in patients with traumatic brain injury and clavicular fracture,reduce the incidence of DVT,shorten the length of hospital stay,and improve the clinical effectiveness of treatment.

Jinan Huaneng Pneumatic Components and Devices Company

The Jinan Huaneng Pneumatic Components and Devices Company (Jinan Pneumatic Components Factory) is a large Class-Ⅱ enterprise, with the multiple functions of scientific research and development, production and processing, operation and sales, technical service, import and export, and personnel training. Following the renovation of its key technology in the Seventh

Optimized design of the pneumatic precision seed-metering device for carrots

The small size, light weight, irregular shape, and impurities that characterize seed groups increase clogging tendencies in the traditional seed-metering device thereby making it difficult to achieve high-speed precision seeding. A pneumatic seed-metering device with good seed-filling performance for carrot was designed in this study. By analyzing the movement state of seeds in the device under the theoretical condition, it was concluded that the minimum critical negative pressure value of air chamber was 0.32 kPa, which provided a theoretical basis for simulation and testing. ANSYS 17.0 Software was used to simulate the shape of the seeding plate hole. By comparing the pressure, air flow stability between the suction surface and the plug removal surface of the convection field, it was concluded that the conical hole was optimal. A bench verification test was conducted on the device. The average qualified rate, missing rate, and replaying rate were 81.48%, 4.07%, and 14.45%, respectively, which provided a strong reference for the design of carrot precision seed-metering device.

Parameter optimization and experiment of the negative pressure precision seed-metering device for wheat

In order to ensure the most reasonable distribution of wheat seeds in the field to improve seeding quality and uniformity,a set of negative pressure precision seed-metering device was designed,which shares a hollow shaft.Every seed-metering device can sow two rows of wheat.By the STAR-CCM+,the analysis of nephogram,vectogram and streamline graph showed that more ideal structural parameters of the seed-metering device are 0.5 mm width of the slit sucking seed(WSS),150-200 mm diameter of the seed-metering disc(DSD),2.0 mm axial depth of air chamber in the seed-metering disc(ADS),and arc-shaped cross-section shape of the ring groove sucking seed(CSGS).Single-factor test on the JPS-12 test-bed analyzed the influence of the CSGS,WSS,DSD,and ADS on the qualified index(Iq),multiple index(Imul),miss index(Imiss)and coefficient of variation of qualified seed spacing(CV).Through the orthogonal on the JPS-12 test-bed,it is found that the influence of vacuum negative pressure and seed-metering device shaft speed is significant on the Iq,Imiss and Imul.Based on these,the structural parameters of the seed-metering device were optimized.The DSD is 180 mm,the WSS is 0.7 mm,the ADS is 2.5 mm,and the CSGS is arc-shaped.The optimization seed-metering device was tested on the JPS-12 test-bed.The Iq is 86.66%,the Imiss is 5.09%,the Imul is 8.25%,and the CV is 24.50%.These testing results fully coincide with the standard JB/T 10293-2013 Specifications of single seed drill(precision drill).The seed-metering device meets fully the requirements for wheat precision seeding.

Design and test of an inside-filling pneumatic precision centralized seed-metering device for rapeseed

The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research confirmed that the inside-filling pneumatic precision centralized seed-metering device satisfied the agronomic requirements of rapeseed planting and can be a reference for the development of precision seed metering devices.

Development of Flexible Spherical Actuator with 3D Coordinate Measuring Device

Rehabilitation devices help to recover the physical abilities of patients. This study aims to develop a portable rehabilitation device that is safe to use when?patients are holding it by hands. In a previous study, to realize a home rehabilitation device, a flexible spherical actuator that can provide motion to patients was developed. In this study, to measure the relative position between both handling stages, a 3D coordinate measuring device using three wire-type linear potentiometers and an embedded controller was proposed and tested. In this paper, the spherical actuator with built-in 3D coordinate measuring device is described. The measuring method and experimental results obtained are also presented. The tracking position control of the actuator using the measuring device was carried out. As a result, the position of the handling stages can be successfully controlled using the feedback signal from the tested?measuring device.

Seed guide path planning and parameter optimization for air-suction carrot seed-metering device

To meet the requirement of“zero speed”for precision sowing,the instantaneous speed of seed falling into the seed bed should be equal to the opposite direction of the forward speed of the machine.Through analyzing the principle of seed guiding process,the main influencing factors affecting the contour curve of the seed tube were determined to plan the seed guiding path and realize zero speed seed delivery.With the help of EDEM simulation software,taking the inclination angle of seed tube end,operating speed of the metering disc,and machine’s forward speed as the experimental factors,a single-factor simulation test was conducted with the pass rate,replay rate,and missing seeding rate as experimental indexes.The results of the simulation test showed that the range of inclination angle of the seed tube end was 23°-40°,the range of machine forward speed was 5-9 km/h,and the range of operating speed of the metering disc was 15-40 r/min.The quadratic orthogonal rotation combination test method was carried out using the bench test,and a mathematical regression model was established between experimental factors and experimental indexes to determine the priority order of factors,and the best combination of factors.The test results showed that the pass rate was 93.25%,the replay rate was 2.97%and the missing seeding rate was 3.78%under the condition with the inclination angle of seed tube end of 32.28°,the forward speed of the machine of 6.89 km/h and the operating speed of the metering disc of 28.67 r/min,which can meet the requirements of relevant national standards.

Design and experiment of pneumatic seed clearing mechanism for pin-hole tube wheat plot precision sowing device

For the problem that when wheat is sucked up by the air suction method,the seeds are aligned in a small area,making it difficult for the contact seed cleaning mechanism to clean the seeds.The mechanism of seed cleaning airflow on wheat seed was studied,the flow velocity distribution relationship of the jet section was defined,the mathematical model of the jet velocity of circular and plane sections was established,and the key factors that could have a significant influence on seed cleaning effect were explored.A non-contact positive pressure air flow seed cleaning method was proposed.After theoretical calculations,it is concluded that the core section lengths of the circular section jet and the inline jet are 24.8 mm and 28.8 mm,respectively.The clearing distance is set to 20 mm.Through the single-factor test,the best air tube nozzle shape was clarified as a vertical inline nozzle.The angle of seed cleaning,the air velocity of seed cleaning,and the negative supply pressure were selected as influencing factors,and the seed leakage index,seed reabsorption index,and seed qualification index as the evaluation indicators to conduct a 3-factor 5-horizontal rotation test.A mathematical regression model of influencing factors and evaluation indexes was established to analyze the influence of these factors and indexes.The optimal operation parameters were obtained as the seed cleaning Angle of 19°,the seed cleaning air velocity of 58 m/s,and the negative pressure of 8.5 kPa.Under the optimal parameters,the seed leakage suction index is 8.23%,the seed reabsorption index is 0.33%,and the seed qualification index is 91.44%,which meets the design requirements.

Design and experiment of conical diversion virus-free potato minituber precision seed-metering device

In order to accelerate the development of sowing mechanization of virus-free potato minituber,a conical diversion virus-free potato minituber precision seed-metering Device was designed according to the structural characteristics and agronomic requirements of virus-free potato minituber.The device is mainly composed of conical turntable,transmission shaft,outer baffle of seed-metering Device,baffle,seed outlet,seed cleaning device,type hole,etc.The working principle of conical diversion precision seed-metering device for virus-free potato minituber was expounded,and the stress analysis of virus-free potato minituber in each region was carried out.By EDEM discrete element simulation software,the structure of the type hole is optimized to determine the optimal structure of the type hole and according to the physical characteristics of virus-free potato minituber,the single factor experiments of the effects of length of type hole,cone disc speed and cone disc angle on seed filling performance were completed.The orthogonal regression test was carried out with the length of type hole,cone disc speed,and cone disc angle as the test objects,and the leakage rate and qualified rate as the response indexes.The regression models of leakage rate,replay rate,and qualified rate were established,and the parameters of the regression model were optimized.The optimal parameter combination is that the length of type hole is 33.61 mm,the cone disc speed is 6.35 r/min,and the cone disc angle is 26.59°.Bench test was carried out under the optimal conditions,the leakage rate was 3.80%,the replay rate was 0.80%,and the qualified rate was 95.40%,which was basically consistent with the prediction results of the regression model,and met the requirements of precision sowing of virus-free potato minituber.

气吸式杂交稻单粒排种器研制

针对气力式水稻精量排种器充种不稳定、单粒播种精度不高和播种量大的问题,该研究设计了一种具有矩形吸种孔和辅助充种装置的气吸式杂交稻单粒排种器。根据“吉田优”型杂交稻的长短轴重力分布情况,确定排种盘吸种孔形状;基于CFD-DEM(Computational fluid dynamics,Discrete element method)流固耦合理论,以吸附力为指标,进行5类具有相同面积的吸种孔单因素仿真试验,确定吸附力最大的吸种孔规格为0.8 mm×2.25 mm;以该型吸种孔为基础,选取辅助充种角、工作转速和工作负压为试验因素,以单粒率S、多粒率M和漏播率L为试验指标,开展Box-Bhnken台架试验,对试验结果进行响应曲面分析和多目标优化,得到排种盘辅助充种角为80.90°、工作转速为42.65 r/min、工作负压为621 Pa时,排种器的单粒率为86.91%,漏播率为3.63%。验证试验结果的排种器单粒率为86.36%、漏播率为3.41%,与优化结果吻合。研究结果可为后续气吸式杂交稻单粒排种器的优化设计和直播机整机作业精度的提高提供指导。

气力辅助充种式花生精量排种器设计与试验

针对花生播种向精准、高速方向发展过程中高速作业状态下花生种子充种效果差的问题,设计了一种气力辅助充种式花生精量排种器,重点设计了排种器排种盘结构和气力辅助充种结构。针对颗粒尺寸大、质量大的花生种子,通过对花生种子在排种器中堆积现象与充种时间进行分析,得出花生高速排种充种过程需增强充种性能,从而提高充种效率。通过对花生种子进行充种原理分析,阐明花生种子充种过程中种子与排种器的运动关系与受力关系,分析充种过程影响因素。通过设计带有导种槽的排种盘和带有辅助吹种型孔的辅助充种结构,分析计算排种盘吸种孔、导种槽的关键结构参数以及辅助吹种型孔参数与排列方式。以充种合格率和充种漏充率为指标,进行三因素三水平组合试验,对试验结果进行多元回归分析,以最优目标进行优化,确定排种盘最佳参数组合为排种器吸种负压5.156 kPa、花生高速播种机前进速度8.007 km/h、扰动吹种正压1.149 kPa,此时,花生充种合格率为95.84%、漏充率为4.06%,能够实现花生种子有效充种。

玉米大豆兼用腔盘组合孔式排种盘设计与充种性能试验

针对玉米大豆带状复合种植条件下传统机械式排种器不易实现二者兼用精量排种要求、现有气力式排种器排种速度提高因型孔漏充存在漏播断条等问题,设计了一种具有腔盘组合孔结构的排种盘,分析确定了排种盘关键结构参数,构建了吸附过程和吸运过程力学模型。应用EDEM离散元仿真与台架试验相结合的方法进行了排种盘型式优选试验,结果得出:腔盘组合孔式排种盘具有提高充种室种群定向运移平均速度和增大拖拽充种角的作用,有效抑制了型孔漏充率。以安装优选种盘的玉豆兼用排种器为对象,以机组前进速度和工作负压为试验因素,以漏充率和充种合格率为试验指标,采用二因素全因子试验设计开展了充种性能试验,结果表明:当机组前进速度为4.0~7.0 km/h、工作负压在3.0~4.0 kPa时,玉米和大豆种子漏充率均小于3.6%、充种合格率均不小于96%。田间验证试验表明,在机组前进速度为4.0~7.0 km/h、工作负压为3.0~4.0 kPa条件下,腔盘组合孔式排种盘的排种器播种玉米和大豆漏充率分别不大于3.8%、4.2%;当工作负压为3.0 kPa、机组前进速度为7.0 km/h时,自扰动腔盘组合孔式排种盘相比无扰动平面排种盘,播种玉米和大豆漏充率分别下降14.8、12.6个百分点。

气力式高速精量排种器研究现状及展望

高速作业是当前精量播种技术的发展趋势,气力式精量排种器是实现高速作业的关键技术载体。分析限制气力式排种器作业速度提升的主要因素,提出高速充种技术、稳定清种技术、投种过程种子平稳运动控制技术、排种器平稳驱动技术四项关键技术。综述气力式精量排种器主要类别及特点,梳理国内外气力式排种器研发应用现状,针对提出的四项关键技术分析国内外研究现状,得出稳定充种、有效清种、平稳投种、排种器平稳驱动是有效提升高速作业播种合格率、降低变异系数、保证粒距均匀性的主要技术措施。结合我国的情况分析高速精量播种存在作业速度及效率低、电驱技术及质量监控技术不完善等问题,提出气力式高速精量排种器需要加大自主创新,未来向着高精度、高效率、智能化方向发展。

砂浆颗粒气力输送装置及关键参数研究

为解决砂浆颗粒气力输送过程中物料的输送效率低以及弯管处所受到的磨损较大的问题,提出了基于ANASY FLUENT模块的仿真研究。首先,是对气力输送装置的三维建模,确定合适的输送装置;其次,再对气固混合物在管道中的运动进行受力分析,得到颗粒群在管道中运动的微分方程为后续的仿真进行验证;最后,对砂浆颗粒的水平管道进行不同的气体输入速度研究及对弯管处进行不同弯径比的仿真。通过对比不同气力输送的入口速度对气相和固相在管道中的运动分布以及对比不同弯径的弯管下的气相压力云图,得出了适合砂浆颗粒输送的最佳速度以及最优的弯径比。

智能图书存取机器人设计

为提高图书馆书籍存取效率,设计了一种新型智能图书存取机器人。该机器人主要是由智能识别、循迹移动、准确取书等系统组成,通过智能摄像头、四轮驱动移动平台、五自由度机械臂、气动吸附装置、升降装置等结构的协调工作,精确锁定目标书本并快速取出不同位面的书籍,降低图书管理员的工作强度,帮助读者准确、快速地获取纸质藏书。

矿用卡轨车气动压绳梁的设计

为了解决无极绳牵引卡轨车在使用过程中压绳轮磨损导致的跳绳现象,本文基于部分矿区采用的人工拆除和安装压绳滑轮来防止跳绳的操作步骤,设计开发了一种气动压绳梁装置。该装置通过气动系统与压绳梁结构之间的装置联动,利用气缸的气动力实现压绳梁对于钢丝绳的压紧和放松,再由另外一个气缸完成销子的插拔,从而完成一个工作循环。该装置的使用,可以取代原本涉及人工的部分,提高生产工作的安全保障以及生产效率,在同类型的各个矿区中都可以进行推广使用。

采用螺旋状接地模块的接地装置自动化控制

针对接地装置当中电流泄露不足,跨步电压较大以及装设接地装置时间过长的问题,该文提出结合螺旋状接地模块的接地装置自动化控制模型。通过中央控制单元对接地装置进行自动化控制,并结合气动筒调节接地装置的长度;同时通过将螺旋状接地模块代替传统接地模块的接地装置,以提高接地电流的引流以及泄流的水平。经过实验验证,该办法能够使跨步电压降低,同时降低接地装置控制成本。通过工作人员的接地装置装设对比,该文设计接地装置装设简单,极大提高了接地装置的装设效率。

煤矿井下轨道运输设施中气动控制装置的应用

主要研究了煤矿井下轨道运输安全设施中气动控制装置的应用。通过对煤矿井下轨道运输安全设施现状进行分析,提出了一种新型气动控制装置,旨在提高煤矿井下轨道运输的安全性能。详细介绍了气动控制装置的设计、工作原理以及在实际运输过程中的应用效果等。

基于PLC控制的煤矿识别卡自动装配产线设计

煤矿识别卡产品装配大部分采取人工工序分步骤装配的作业模式,在对现有的识别卡装配工艺进行调研后,总结出一套优化自动装配柔性工艺的措施,并基于此措施开发了一套基于PLC控制的识别卡自动装配产线平台,提升产品的生产效率,彻底解决识别卡产线装配产量不足的问题,极大提升煤矿产品的交付能力。通过分析煤矿识别卡产品自动装配产线平台的来料工装方案,研制了一种识别卡产品自动装配产线平台装置,提出了装配产线机械臂和气动组件装置代替或尽量减少人工作业的装配模式。通过PLC多融合自动控制的技术手段,增加了装配过程环节各工序的视觉检验过程,形成了识别卡产品自动装配产线平台和实际自动装配应用场景。

大口径热量表检定装置常见故障及解决对策

大口径热量表检定装置是对热量表进行量值传递的一种标准装置,由热水流量标准装置、配对温度传感器检定装置、密封性实验设备、压力测量组件等组成。本文介绍了大口径热量表检定装置在运行过程中组成设备出现的问题,重点分析了电子天平、标准表、气动阀门、夹表器等设备发生故障的原因并提出相应的解决对策。