基于霍尔效应的微小压强测量装置的设计与实现     

占宏  乔利国 《湖南农业大学学报(自然科学版)》2015,(1):51-54

针对化工液体的微小压强测量中所存在的测量复杂、精度低的问题，设计一种基于霍尔效应的测量流体微小压强变化的装置。该测量装置通过前端受力装置来承受液体压强的变化而产生一定的位移，并转换成霍尔电动势，经放大调理电路，最后接电压表显示相应的电压值。根据输出电压与液体压强之间的关系即可得到相应深度的压强大小。在实验中，电压表精确到1mV，最小可测量到0.792Pa的压强变化，其测量精度较高。该装置体积小、通用性强，具有较好的应用前景。  相似文献   

沟槽滤棒压降影响因素的因子分析     

戚奇杰  杨皓  曹得坡  宣润泉 《安徽农业科学》2016,(7)

[目的]深入研究沟槽滤棒特征参数及组成材料对滤棒压降的影响。[方法]选取常见的8种不同规格的沟槽滤棒及其主要组成材料为分析对象,采用相关性分析与因子分析,开展9个主要特征参数对沟槽滤棒压降的影响程度研究。[结果]试验表明,影响沟槽滤棒压降的特征参数间存在显著或极显著的相关性,相关系数矩阵中特征值大于1.0的前3个成分的累计贡献率达87.502%;由沟槽滤棒压降影响特征参数的旋转因子载荷矩阵得到3个公因子,总结定义后分别是:丝束总质量因子、单丝线密度/纤维素纸物理特性因子、沟槽特征参数因子。[结论]因子分析得出的公因子影响情况与实际沟槽滤棒生产检验过程中出现的情况基本吻合,进一步证实了沟槽滤棒特征参数对滤棒压降影响的准确性。  相似文献   

不同通风工艺在浅圆仓中应用的研究     

郑明辉  戴云松  王健刚  张志林 《粮食储藏》2016,(4):39-42

在对大豆进行冬季通风作业时,采用正压上行压入式、负压下行吸出式和先负压后正压三种作业方式分阶段进行通风,充分的利用自然冷源,达到降温目的,通过对比三种作业方式的降温效果、水分损耗、降温能耗、人工投入等,并根据粮情,找出最合适的通风方式。  相似文献   

重组减蛋综合征病毒KnobS干酪乳杆菌的构建与表达     

郭建军  袁林  曾静  邱小忠  付锦楠 《华北农学报》2016,(2):81-86

以干酪乳杆菌为传递载体,以开发食品级安全的减蛋综合征病毒疫苗为目标,构建了一个温度敏感型自杀型质粒系统p ORZP-UKD。将该质粒电转化到干酪乳杆菌L.casei中,经过2次升温处理和5-氟尿嘧啶抗性筛选,挑选阳性克隆,采用PCR和SDS-PAGE方法进行鉴定。KnobS基因整合到干酪乳酸杆菌基因组内,并实现融合蛋白KnobS的分泌表达。表明得到了一株具有无任何选择性标记、携带有KnobS表达盒元件的基因组整合的重组干酪乳酸杆菌KnobSΔupp L.casei,且整合的外源基因能够随着细菌的复制而进行表达,为减蛋综合征病毒免疫保护性抗原KnobS疫苗的进一步研制提供了试验数据。  相似文献   

Revisiting the use of hydroxyethyl starch solutions in equine fluid therapy     

K. L. Hepworth-Warren 《Equine Veterinary Education》2021,33(8):436-443

The last decade has led to major shifts in opinions on the use of hydroxyethyl starch (HES) solutions in fluid therapy, specifically in human patients with sepsis. The majority of evidence documenting adverse effects of HES solutions on coagulation and renal health come from studies in people. However, these findings have led to investigation into the safety of HES solutions in veterinary species. While there are now studies investigating the effects of HES solutions on coagulation and renal health in dogs, cats and horses, information regarding long-term follow-up, clinical significance of these changes and use of these solutions in critically ill animals is still lacking. The information presented here serves to review the physiology of oncotic pressure and the rationale behind colloid use, specifically HES solutions. Additionally, the foundation of arguments against the use of HES and the available literature regarding HES use in animals will be summarised.  相似文献   

Quantification of reservoir bags as airway pressure-limiting devices in a nonrebreathing system     

Tamas D. Ambrisko  Arnon Gal  Jesus N. Sarol  Ashley Mitek  Christina Braun 《Veterinary anaesthesia and analgesia》2021,48(2):205-212

ObjectiveTo evaluate the influence of reservoir bag types, volumes and previous use on the peak pressures (Pmax) and the times to develop 30 cmH₂O pressure (P30) within a nonrebreathing system with a closed adjustable pressure-limiting (APL) valve.Study designIn vitro study using three-way factorial design with repeated measure on one factor.SubjectsA total of 75 new anesthesia reservoir bags (five types, three volumes, five bags from each type × volume). The bag types were reusable latex (RL), disposable latex (DL) and three disposable neoprene (DN-1, DN-2 and DN-3).MethodsEach bag was tested three times (treatments): new, after prestretching and 1 week later. The bags were attached to a Bain system and anesthesia machine with closed APL valve and patient port with O₂ flow 2 L minute^–1 until Pmax was reached. The Pmax and time to reach P30 values were determined from recorded pressure traces. General linear mixed model analysis was used to examine the effects of bag type, volume and treatment. One-sided 95% upper prediction limits of Pmax were calculated to test the null hypothesis that predicted Pmax of new bags would be ≥ 50 cmH₂O for each factor combination.ResultsRL bags were the least and DN-3 bags were the most compliant. Prestretching increased compliance in all bag types. Smaller bags of RL, DL and DN-1 were less compliant than larger ones. The predicted Pmax values were < 50 cmH₂O only for DN-3 bags after prestretching. The time to reach P30 was critically low when using 0.5 L bags (median 17 seconds).Conclusions and clinical relevanceTo minimize the risk of barotrauma, highly compliant reservoir bags (e.g. DN-3) are recommended and reusable bags should be avoided. Bags should be prestretched before first use, 0.5 L bags should be avoided and fresh gas flow minimized.  相似文献   

Evaluation of the agreement of two oscillometric blood pressure devices with invasive blood pressure in anaesthetized chimpanzees (Pan troglodytes)     

《Veterinary anaesthesia and analgesia》2021,48(5):688-696

ObjectiveTo evaluate the agreement of two noninvasive blood pressure devices: a human device with the cuff placed on the wrist (Omron R1) and a veterinary device with the cuff placed on the upper brachium (Surgivet Advisor Vital Signs Monitor) with invasive blood pressure (IBP) measurement in anaesthetized chimpanzees.Study designProspective clinical study.AnimalsA convenience sample of 11 adult chimpanzees undergoing anaesthesia for translocation and routine health checks.MethodsSystolic (SAP) and diastolic arterial pressures (DAP) were continuously recorded via a transducer connected to a femoral artery cannula, and at 5 minute intervals from the two oscillometric devices. Agreement was explored using Bland-Altman analysis and bias defined as the mean difference between the two measurement methods. Spearman correlation coefficients were calculated. Significance was set at p < 0.05.ResultsBias and standard deviation for the Surgivet compared with IBP were 8.6 ± 18 for SAP and 8.4 ± 9.9 for DAP, showing a significant underestimation of both variables. Limits of agreement (LOA) were from –27 to 44 for SAP and from –11 to 28 for DAP. Correlation coefficients between the Surgivet and IBP values were 0.86 for SAP and 0.85 for DAP (p < 0.0001). Bias and standard deviation for the Omron compared with the IBP were –21 ± 25 for SAP and –18 ± 15 for DAP, showing a significant overestimation of both variables. LOA were from –70 to –28 for SAP and from –47 to 11 for DAP. Spearman correlation coefficients between the Omron and IBP values were 0.64 for SAP and 0.72 for DAP (p < 0.0001).Conclusions and clinical relevanceAlthough neither device met all the criteria for device validation, the Surgivet presented better agreement with IBP values than the Omron in adult anaesthetized chimpanzees.  相似文献   

离心泵叶轮出口宽度对泵腔内压力脉动分布的影响   总被引：1，自引：0，他引：1  

戴菡葳  刘厚林  丁剑  谈明高  王勇 《排灌机械》2015,(1)

在试验和数值模拟相互验证的基础上,开展叶轮出口宽度对离心泵泵腔内压力脉动分布影响的研究．通过试验和数值计算获得离心泵的外特性、泵腔内静压分布、泵腔内压力脉动分布及泵体表面的压力脉动幅值分布,并进行对比分析,结果表明：前泵腔内静压和压力脉动幅值随出口宽度的增大而增大,随半径的减小而增大;后泵腔内静压和压力脉动随出口宽度和半径的变化不十分明显．综合考虑外特性和压力脉动,在比转数 ns ＝97时叶轮出口宽度与叶轮出口直径之比应小于0.06;为了使压力脉动在泵腔内有效地衰减,出口宽度与前腔间隙的比值在1.81附近时最佳．研究结果可用于指导离心泵叶轮的优化设计．  相似文献   

宽幅高效离心式双圆盘撒肥机设计与试验   总被引：3，自引：0，他引：3  

芦新春  陈书法  杨进  王强 《农机化研究》2015,(8):100-103

为解决现有水旱田撒肥机械作业效率低、撒肥量调节技术落后、施肥均匀性稳定性差等实际问题,设计了一种同轴驱动的离心式双圆盘撒肥机。介绍了整机结构与工作参数,研究设计了撒肥传动系统、撒肥盘结构、排肥量液压调节装置等,并确定了关键结构和参数,同时进行了试验研究。试验结果显示,推肥板推肥角度-20°~30°可调,撒肥幅宽达到50m,总排肥量稳定性变异系数低于6%,施肥均匀性变异系数低于16%。研究结果表明,撒肥机工作性能稳定、撒肥量可控、抛撒均匀,整机设计满足水旱田宽幅高效撒肥作业要求。  相似文献   

自来水电子压力表的设计     

郑振峰 《湖南农机》2015,(3):71-72

文章阐述了一种自来水电子压力表的设计装置,具有压力系数大小实时现实、存储、查询、报警等功能。该系统采用高精度的传感器来检测压力,低温漂的仪表放大器AD620对数据进行放大,通过8位AD转换器件ADC0808进行AD采集和数据变换处理,并可将数值通过串口发送到电脑,实现压力系数的数字化测量。  相似文献