Bubble counter based on photoelectric technique for leakage detection of cryogenic valves

In order to overcome the inconvenience of manual bubble counting, a bubble counter based on photoelectric technique aiming for automatically detecting and measuring minute gas leakage of cryogenic valves is proposed. Experiments have been conducted on a self-built apparatus, testing the performance with different gas inlet strategies (bottom gas-inlet strategy and side gas-inlet strategy) and the influence of gas pipe length (0, 1, 2, 4, 6, 8, 10 m) and leakage rate (around 10, 20, 30, 40 bubbles/min) on first bubble time and bubble rate. A buffer of 110 cm3 is inserted between leakage source and gas pipe to simulate the down- stream cavum adjacent to the valve clack. Based on analyzing the experimental data, experiential parameters have also been summarized to guide leakage detection and measurement for engineering applications. A practical system has already been suc- cessfully applied in a cryogenic testing apparatus for cryogenic valves.

Using acoustic technique to detect leakage in city gas pipelines

For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.

Application of Chemical Tracing Experiment Technique in Leakage Detection of Hydraulic Engineering

[Objective] The research aimed to study the application of chemical tracing experiment technique in leakage detection of hydraulic engineering.[Method] According to the current situation of Sanyuan Western Suburb Reservoir in Xianyang City of Shaanxi Province,three sections （L1,L2 and L3） were set.KI was selected as the chemical tracer to carry out the tracing and detection research.[Result] There was no obvious leakage phenomenon in L1,L2 and L3 sections.The impermeability of rock in some dam abutments was bad.[Conclusion] The leakage reason of Western Suburb Reservoir was that the impermeability of rock in some dam abutments couldn’t satisfy seepage requirement.After the reservoir was put into operation,the water level in front of dam rose,and the ground water level of dam abutment also rose.The penetration water pressure correspondingly increased,and the water content of bank slope at the downstream of dam increased.

Peritoneal fluid indocyanine green test for diagnosis of gut leakage in anastomotic leakage rats and colorectal surgery patients

BACKGROUND Application of indocyanine green(ICG)fluorescence has led to new developments in gastrointestinal surgery.However,little is known about the use of ICG for the diagnosis of postoperative gut leakage(GL).In addition,there is a lack of rapid and intuitive methods to definitively diagnose postoperative GL.AIM To investigate the effect of ICG in the diagnosis of anastomotic leakage in a surgical rat GL model and evaluate its diagnostic value in colorectal surgery patients.METHODS Sixteen rats were divided into two groups:GL group(n=8)and sham group(n=8).Approximately 0.5 mL of ICG(2.5 mg/mL)was intravenously injected postoperatively.The peritoneal fluid was collected for the fluorescence test at 24 and 48 h.Six patients with rectal cancer who had undergone laparoscopic rectal cancer resection plus enterostomies were injected with 10 mL of ICG(2.5 mg/mL)on postoperative day 1.Their ostomy fluids were collected 24 h after ICG injection to identify the possibility of the ICG excreting from the peripheral veins to the enterostomy stoma.Participants who had undergone colectomy or rectal cancer resection were enrolled in the diagnostic test.The peritoneal fluids from drainage were collected 24 h after ICG injection.The ICG fluorescence test was conducted using OptoMedic endoscopy along with a near-infrared fluorescent imaging system.RESULTS The peritoneal fluids from the GL group showed ICG-dependent green fluorescence in contrast to the sham group.Six samples of ostomy fluids showed green fluorescence,indicating the possibility of ICG excreting from the peripheral veins to the enterostomy stoma in patients.The peritoneal fluid ICG test exhibited a sensitivity of 100%and a specificity of 83.3%for the diagnosis of GL.The positive predictive value was 71.4%,while the negative predictive value was 100%.The likelihood ratios were 6.0 for a positive test result and 0 for a negative result.CONCLUSION The postoperative ICG test in a drainage tube is a valuable and simple technique for the diagnosis of GL.Hence,it should be employed in clinical settings in patients with suspected GL.

Investigations of Tracking Phenomena in Silicone Rubber Using Moving Average Current Technique

In the present work, tracking phenomenon in Silicone rubber material has beenstudied under AC and DC voltage, with ammonium chloride as a contaminant. It is observed that thetracking is more severe under the DC voltages. The tracking time is less under negative DC comparedto the positive DC voltage. The tracking mechanism is explained in detail. The leakage currentduring the tracking studies was as measured and the moving average technique was adopted tounderstand the trend in current flow. The leakage current magnitude is high with thermally agedspecimens compared to the virgin specimen, irrespective of the type of applied voltage. It isrealized that the tracking time and the leakage current magnitude shows an inverse relationship.

Efficacy of staple line reinforcement by barbed suture for preventing anastomotic leakage in laparoscopic rectal cancer surgery

BACKGROUND Anastomotic leakage(AL) is a severe complication in rectal cancer surgery.Various methods, including intracorporeal reinforcing suturing, have been used to reduce the incidence of AL. However, little is known about the efficacy of staple-line reinforcement by barbed suture for preventing AL.AIM To evaluate the efficacy of staple-line reinforcement using barbed suture for preventing AL in laparoscopic surgery for rectal cancer.METHODS We retrospectively reviewed the clinical datum of 319 patients undergoing laparoscopic low anterior resection combined with double stapling technique between May 1, 2017 and January 31, 2021. All surgeries were performed by the same surgical team specializing in colorectal surgery. Patients were divided into two groups depending on whether they received reinforcing sutures. Patients’ baseline characteristics did not show any significant difference between the two groups. We analyzed patient-, tumor-, as well as surgery-related variables using univariate and multivariate logistic analyses.RESULTS There were 168 patients in the reinforcing suture group and 151 patients in the non-reinforcing suture group. AL occurred in 25 cases(7.8%). Its incidence was significantly higher in the non-reinforcing suture group than in the reinforcing suture group(4.8% vs 11.3%, P = 0.031). The multivariate analyses demonstrated that the tumor site, tumor size and presence of staple-line reinforcement were independent risk factors for AL. We divided these patients into two risk groups based on the combination of tumor site and tumor size. Patients without any risk factor were assigned to the low-risk group(n = 177), whereas those having one or two risk factors were assigned to the high-risk group(n = 142). In the high-risk group, the AL incidence considerably decreased in the reinforcing suture group compared with that in the non-reinforcing suture group(P = 0.038). Nonetheless, no significant difference was found in the low-risk group between the two groups.CONCLUSION Staple-line reinforcement by barbed suture may decrease the incidence of AL. A large-scale prospective randomized controlled trial is needed for evaluating the efficacy of staple-line reinforcement for preventing AL.

Intramuscular vaccine administrations including the adoption of"Zeta-track technique"&"without aspiration slow injection technique"(ZTT&WASiT):a prospective review

Objective:To review the current literature on the practice of intramuscular injections(IMIs),focusing on immunizations.Methods:The present study comprises 2 reviews,characterized by high-quality evidence,per taining to the deployment of the slow injection technique without aspiration(referred to in this paper as the without-aspiration slow injection technique[WASi T])and combined with the Zeta-track technique(ZTT).The literature review is oriented toward the analysis of 2 features associated with IMIs techniques:safety and pain,integrating new evidence on vaccinee positioning for each muscle site and general relaxation techniques in the multi-parametric analysis.Results:The rigorous and in-depth reviews in the current study reveal the usefulness of including,among the international guidelines for via intramuscular immunizations,the adoption of WASi T only for compliant vaccinees,and in combination with all validated techniques for IMIs,and the use of ZTT limitedly if specific well-developed muscles are indicated.All the technique's limitations are exposed.Conclusions:Future research directions are presented by including the author's study designs to provide indirect evidence for the validity of the rationale of the slow injection technique using scientific methods,and for the conduction of future randomized controlled trials(RCTs)focused on revisiting the adoption of ZTT in a dynamic and integrated immunizations protocol in anterolateral thigh(ALT),ventrogluteal(VG),and also in the deltoid muscle,in the specific cases analyzed.

Low Leakage Power Sequential Circuits Using Multi-Vth at Nano-Scale Transistor

Leakage power is the dominant source of power dissipation for Sub-100 nm VLSI （very large scale integration） circuits. Various techniques were proposed to reduce the leakage power at nano-scale; one of these techniques is MTV （multi-threshold voltage） In this paper, the exact and optimal value of threshold voltage （Vth） for each transistor in any sequential circuit in the design is found, so that the value of the total leakage current in the design is at the minimum. This could be achieved by applying AI （artificial intelligence） search algorithm. The proposed algorithm is called LOAIS （leakage optimization using AI search）. LOAIS exploits the total slack time of each transistor＇s location and their contributions in the leakage current. It is introduced by AI heuristic search algorithms under 22 nm BSIM4 predictive technology model. The proposed approach saves around 80% of the sub-threshold leakage current without degrading the performance of the circuit.

混凝土结构防渗漏施工技术在房屋建筑工程中的应用

在房屋建筑工程中,混凝土结构防渗漏施工技术的应用至关重要,直接影响建筑的整体质量和居住体验。合理应用混凝土结构防渗漏施工技术,能有效解决房屋建筑渗漏问题,提升建筑质量,保障居民安全。基于此,文章首先探讨了研究了房屋建筑容易出现渗漏问题的几个结构部位,然后研究了防渗漏施工技术在房屋建筑工程中的应用以及施工要点,以期能有效预防结构渗漏病害问题的发生。

房屋建筑施工中防渗漏施工技术应用

随着城市化进程的加快,房屋建筑工程的质量问题日益受到关注。在房屋建筑施工过程中,防渗漏施工技术是确保建筑物结构安全、功能完整和居住舒适性的关键环节。论文旨在探讨房屋建筑施工中常用的防渗漏施工技术,包括屋面、地下室、外墙、厨卫间及外门窗等部位的防渗漏措施,并结合实际工作经验和优秀做法,提出相应的施工技术和管控方法,以期为类似工程提供借鉴和参考。综合运用这些技术措施,提升建筑物的防水性能,降低维护成本,延长建筑物的使用寿命,为用户提供更加安全、舒适的生活环境。

形状记忆环氧材料漏电流抑制技术及耐辐照性能提升方法

针对航天器空间可展开结构用形状记忆聚合物材料在空间辐照环境中电荷输运性能发生变化时易产生漏电流,从而造成结构器件劣化、击穿,甚至影响航天器正常运行的问题,从高分子三维网状结构设计角度出发,提出一种形状记忆聚合物辐照感应漏电流抑制方法,实现了形状记忆聚合物的性能提升,能够指导空间可展开结构材料的选型和设计。基于常用的双酚A环氧树脂材料,通过引入不同官能度和配比的固化剂调控其高分子三维网状结构,获得了具有不同热力学性能的形状记忆环氧材料。采用X射线辐照感应电导率在线测试系统,表征不同体系环氧材料在不同辐照功率下的漏电流演变情况。研究结果表明:相较于固化剂官能度为5的形状记忆环氧材料体系,固化剂官能度为6环氧材料体系的X射线辐照感应电导率随固化剂配比变化的幅度减小了约50%,即选择官能度相对较高的固化剂体系环氧材料,能够构建更加致密的高分子三维网状结构,可获得更加稳定的热力学和X射线辐照感应电导性能,更有利于抑制辐照感应漏电流,从而增强了空间展开结构X射线辐照防护效果。

轧钢设备液压系统泄漏问题分析及维修技术探究

液压系统泄漏是轧钢设备生产过程中较为常见的一种设备问题,会严重影响轧钢设备的自动化运行,降低生产效率,提高成本,甚至会造成一定的环境污染。鉴于此,在分析轧钢设备液压系统泄漏类型和泄漏原因的基础上,从维修流程角度对液压系统泄漏维修技术进行探究,并从密封结构选用、振动冲击力度和温度控制两方面提出了针对性的泄漏防控措施。

LNG接收站温室气体甲烷逸散特征与量化

液化天然气(Liquefied Natural Gas,LNG)接收站内有大量的法兰、阀门、开口管、连接件等设备,设备内输送的LNG介质与外界环境温差大,其密封点处容易发生老化变形而引发甲烷泄漏,从而造成环境污染。目前,国内外缺少对LNG接收站设备甲烷逸散浓度与甲烷逸散速率检测及排放量的核算方法,难以准确地对LNG接收站甲烷逸散排放量进行核算。研究对LNG接收站高压泵区、管廊区、罐区等12个检测区域,3243个设备的甲烷逸散浓度进行检测,明确了4类设备及12个区域的泄漏概率,量化了甲烷排放速率,构建了甲烷排放因子,修正了将甲烷逸散浓度换算为甲烷逸散速率的相关方程。结果显示,LNG接收站检测到252个泄漏点,占设备数总量的8%,主要集中在蒸发气(Boil Off Gas,BOG)压缩区、卸船区、高压泵区和罐区。LNG接收站场总排放量为5756.21 kg/a,其中1.17%的设备贡献了约89%的排放量。相较于天然气输气站和压气站,LNG接收站的泄漏概率更大。研究成果为量化LNG接收站设备密封点排放总量及甲烷减排措施的制定提供了参考。

房建工程中的防渗漏施工技术研究

房建工程渗漏问题是建筑工程领域的常见质量通病,不仅影响建筑物的正常使用和美观,而且会加剧建筑构件和装饰材料的老化,降低建筑物的耐久性和安全性,甚至危及人身财产安全。因此,切实加强房建工程的防渗漏施工,提高建筑物的防渗性能,是保障建筑工程质量和安全的重要举措。笔者针对房建工程渗漏的成因进行了系统分析,总结了当前主要的防渗漏施工技术,并结合工程案例,对防渗漏施工技术的实践应用进行了探讨。

市政管道渗漏的预防技术措施研究

针对市政管道常见的渗漏问题,提出了一系列结构优化与材料创新相结合的防渗措施。这些措施有效解决了管道连接薄弱节点泄漏的问题,并实现了整体管网的防渗性能提升。对比实验和现场应用验证表明新型防渗技术不仅可以显著延长管道使用寿命,还能降低维护成本。

铁磁性构件内外侧缺陷重合度与漏磁场信号的关系

基于漏磁检测原理,利用COMSOL有限元仿真软件模拟了含缺陷小管径薄壁管道的漏磁检测信号特征,研究了管壁内外侧都存在缺陷时漏磁场信号的变化情况;同时,采用局部直流磁化及控制变量的方法研究了管壁内外侧缺陷的漏磁场信号分布。结果表明,管道壁厚在超过6 mm时得到的漏磁场信号切向分量的双波峰间峰值差较小,内外侧缺陷的重合度在小于40%时已不易于判定;当缺陷宽度小于2mm时,漏磁场切向分量分布图中的双波峰间峰值差变化较小,从而无法对内侧缺陷参数进行判定。该结果为研究内外侧缺陷的重合度与漏磁信号之间的关系以及薄壁管道的安全评定提供了一定依据。

高压氢气安全储运和泄漏监测研究现状

研究氢气泄漏引发的大气、土壤等环境介质的温变机理,对于提高氢气泄漏监测效率具有重要意义。总结氢气储运现状和面临的主要问题,提出保障氢气输送安全的技术措施和监控策略。结合相关工程实践和理论研究成果,对氢气泄漏的特点、扩散特性、燃爆机理及影响因素进行总结。运用数值仿真模拟高压氢气经过泄漏孔后在大气或土壤中的扩散过程,预测氢气泄漏事故的影响范围,为储运工艺设计、管理优化、安全监测提供指导。

钢结构连廊协同底部幕墙铝板同步提升施工技术研究

近年来,随着整体液压提升技术成熟稳定,多数连体结构均采用整体液压提升的方法进行安装,却给连体结构底部的幕墙铝板安装带来一定的困难。为优化钢结构连体结构底部幕墙铝板安装带来的安全、质量及进度等问题,研发了钢结构连廊协同幕墙铝板同步提升的施工技术。以创智云谷项目高空钢连廊底部幕墙施工为背景,结合铝板安装阶段的选择、铝板吊顶布置、防变形控制措施、铝板吊顶误差及楼板浇筑防漏浆措施等关键技术,在钢连廊整体安装实际施工过程中成功降低安全风险、提升安装质量、加快施工进度,取得了良好的施工效果,可为同类型钢结构整体安装工程提供参考。

一种大容量燃油箱渗漏测试方法及装置

根据某产品燃油箱渗漏问题,研究开发了一种大容量燃油箱渗漏测试方法及装置。该测试方法可有效缩短油箱检测工序时间,简化测试流程,降低测试成本,优化大容量燃油箱渗漏检测的方法。

骨水泥温度梯度灌注技术在经皮椎体后凸成形术中的应用

目的：通过与传统的骨水泥单次灌注技术进行比较,评估骨水泥温度梯度灌注技术在经皮椎体后凸成形术（PKP）治疗骨质疏松性椎体骨折（OVCF）中的临床疗效。方法：收集我院2006年1月~2010年1月共234例行PKP的OVCF患者,根据骨水泥灌注方法的不同分为温度梯度灌注组（采用缓慢、低压、间隔1~2min将骨水泥分次灌注入椎体内）和传统灌注组（采用传统的骨水泥调制好一次性灌注的方法）。温度梯度灌注组：129例患者,160个手术椎体;传统灌注组：105例患者,128个手术椎体。比较术后1周内及末次随访时两组的VAS评分、ODI、伤椎椎体后凸角、伤椎前缘相对高度及骨水泥渗漏率。结果：温度梯度灌注组术后随访25.3±12.2个月;传统灌注组术后随访24.7±11.5个月,两组间差异无显著性（P〉0.05）。温度梯度灌注组：术前VAS评分、ODI、伤椎的椎体后凸角及前缘相对高度分别为7.19±0.94、71.55±7.83、16.66°±8.40°和（62.50±24.64）%;术后为2.18±0.62、28.86±4.71、11.72°±7.81°和（84.50±14.92）%;末次随访时为2.1±1.9、28.79±6.25、11.87°±8.34°和（85.49±12.67）%。传统灌注组：术前VAS评分、ODI、伤椎的椎体后凸角和前缘相对高度分别为7.20±1.07、70.49±9.28、16.97°±9.48°和（61.91±24.84）%;术后为2.25±0.64、28.55±4.46、11.90°±7.42°和（85.09±10.71）%;末次随访时为2.3±2.5、28.51±6.55、11.92°±9.03°和（85.10±14.61）%。两组患者VAS评分、ODI、伤椎的前缘相对高度和椎体后凸角手术后与手术前比较均有统计学差异（P〈0.05）;末次随访时与术后比较无统计学差异（P〉0.05）;两组之间比较术前、术后及末次随访时的上述指标均无统计学差异（P〉0.05）。传统灌注组有9例患者发生骨水泥渗漏,渗漏率8.60%;温度梯度灌注组有3例患者发生骨水泥渗漏,渗漏率2.3%,显著低于传统灌注组的骨水泥渗漏率（P〈0.05）。结论：骨水泥温度梯度灌注技术可以获得满意的影像学及临床效果,并且可以显著降低骨水泥渗漏的发生率。