PHAST＆LEAK软件在原油中转站事故后果评价中的应用

分析了原油中转站的危险特性,以及可能发生的潜在的火灾、爆炸等危险事故。在分析了原油中转站的设备布置、介质的性质以及场站的人员分布情况的基础上,参照国外部分国家采用的个人风险值和社会风险值,运用PHAST＆LEAK软件对原油中转站进行了整体的风险评价,得出了该场站的油气泄漏火灾爆炸风险水平,对该站的安全运营提供了很好的指导作用。

集成PHAST-Visual Studio的岩溶区燃气管道灾害后果定量分析及应用

为科学评估岩溶区燃气管道灾害的后果影响程度,基于管道失效特征确定喷射火和蒸气云爆炸两种典型后果模式,研判适用于岩溶区燃气管道灾害的热辐射和冲击波超压危害准则,从危害面积、伤亡人数、经济损失、环境破坏4个维度提出岩溶区燃气管道灾害后果严重程度的评估模型体系,并结合Visual Studio平台开发“岩溶区燃气管道灾害后果分析软件”。立足岩溶区实际工程案例,结合区域经济社会发展、岩溶自然地质以及燃气管道工程特征,基于PHAST软件仿真分析灾害后果的影响范围,结合危害准则对区内人员、物体提出针对性灾害风险管控措施,并通过引入政府、行业、企业等颁布的标准条例,量化得出灾害后果的影响程度。结果表明:提出的PHAST-Visual Studio集成方法能够弥补以往研究的评估主观性问题,将社会科学思想带入工程风险评价研究,并通过计算机软件编程提高灾害后果分析效率,从而有助于显著控制岩溶区燃气管道灾害后果水平。

Construction and validation of a risk-prediction model for anastomotic leakage after radical gastrectomy: A cohort study in China

Objectives:Anastomotic leakage(AL)stands out as a prevalent and severe complication following gastric cancer surgery.It frequently precipitates additional serious complications,significantly influencing the overall survival time of patients.This study aims to enhance the risk-assessment strategy for AL following gastrectomy for gastric cancer.Methods:This study included a derivation cohort and validation cohort.The derivation cohort included patients who underwent radical gastrectomy at Sir Run Run Shaw Hospital,Zhejiang University School of Medicine,from January 1,2015 to December 31,2020.An evidence-based predictor questionnaire was crafted through extensive literature review and panel discussions.Based on the questionnaire,inpatient data were collected to form a model-derivation cohort.This cohort underwent both univariate and multivariate analyses to identify factors associated with AL events,and a logistic regression model with stepwise regression was developed.A 5-fold cross-validation ensured model reliability.The validation cohort included patients from August 1,2021 to December 31,2021 at the same hospital.Using the same imputation method,we organized the validation-queue data.We then employed the risk-prediction model constructed in the earlier phase of the study to predict the risk of AL in the subjects included in the validation queue.We compared the predictions with the actual occurrence,and evaluated the external validation performance of the model using model-evaluation indicators such as the area under the receiver operating characteristic curve(AUROC),Brier score,and calibration curve.Results:The derivation cohort included 1377 patients,and the validation cohort included 131 patients.The independent predictors of AL after radical gastrectomy included age65 y,preoperative albumin<35 g/L,resection extent,operative time240 min,and intraoperative blood loss90 mL.The predictive model exhibited a solid AUROC of 0.750(95%CI:0.694e0.806;p<0.001)with a Brier score of 0.049.The 5-fold cross-validation confirmed these findings with a calibrated C-index of 0.749 and an average Brier score of 0.052.External validation showed an AUROC of 0.723(95%CI:0.564e0.882;p?0.006)and a Brier score of 0.055,confirming reliability in different clinical settings.Conclusions:We successfully developed a risk-prediction model for AL following radical gastrectomy.This tool will aid healthcare professionals in anticipating AL,potentially reducing unnecessary interventions.

Preoperative neutrophil-to-lymphocyte ratio predicts symptomatic anastomotic leakage in elderly colon cancer patients: Multicenter propensity score-matched analysis

BACKGROUND The neutrophil-to-lymphocyte ratio(NLR),a composite inflammatory biomarker,is associated with the prognosis in patients with colorectal tumors.However,whether the NLR can be used as a predictor of symptomatic postoperative ana-stomotic leakage(AL)in elderly patients with colon cancer is unclear.AIM To assess the role of the NLR in predicting the occurrence of symptomatic AL after surgery in elderly patients with colon cancer.METHODS Data from elderly colon cancer patients who underwent elective radical colectomy with anastomosis at three centers between 2018 and 2022 were retrospectively analyzed.Receiver operating characteristic curve analysis was performed to determine the best predictive cutoff value for the NLR.Twenty-two covariates were matched using a 1:1 propensity score matching method,and univariate and multivariate logistic regression analyses were used to determine risk factors for the development of postoperative AL.RESULTS Of the 577 patients included,36(6.2%)had symptomatic AL.The optimal cutoff value of the NLR for predicting AL was 2.66.After propensity score matching,the incidence of AL was significantly greater in the≥2.66 NLR subgroup than in the<2.66 NLR subgroup(11.5%vs 2.5%;P=0.012).Univariate logistic regression analysis revealed statistically significant correlations between blood transfusion intraoperatively and within 2 d postoper-atively,preoperative albumin concentration,preoperative prognostic nutritional index,and preoperative NLR and AL occurrence(P<0.05);multivariate logistic regression analysis revealed that an NLR≥2.66[odds ratio(OR)=5.51;95%confidence interval(CI):1.50-20.26;P=0.010]and blood transfusion intraoperatively and within 2 d postoperatively(OR=2.52;95%CI:0.88-7.25;P=0.049)were risk factors for the occurrence of symptomatic AL.CONCLUSION A preoperative NLR≥2.66 and blood transfusion intraoperatively and within 2 d postoperatively are associated with a higher incidence of postoperative symptomatic AL in elderly patients with colon cancer.The preoperative NLR has predictive value for postoperative symptomatic AL after elective surgery in elderly patients with colon cancer.

Impact of open hepatectomy on postoperative bile leakage in patients with biliary tract cancer

BACKGROUND Bile leakage is a common and serious complication of open hepatectomy for the treatment of biliary tract cancer.AIM To evaluate the incidence,risk factors,and management of bile leakage after open hepatectomy in patients with biliary tract cancer.METHODS We retrospectively analyzed 120 patients who underwent open hepatectomy for biliary tract cancer from February 2018 to February 2023.Bile leak was defined as bile drainage from the surgical site or drain or the presence of a biloma on imaging.The incidence,severity,timing,location,and treatment of the bile leaks were recorded.The risk factors for bile leakage were analyzed using univariate and multivariate logistic regression analyses.RESULTS The incidence of bile leak was 16.7%(20/120),and most cases were grade A(75%,15/20)according to the International Study Group of Liver Surgery classification.The median time of onset was 5 d(range,1-14 d),and the median duration was 7 d(range,2-28 d).The most common location of bile leakage was the cut surface of the liver(70%,14/20),followed by the anastomosis site(25%,5/20)and the cystic duct stump(5%,1/20).Most bile leaks were treated conservatively with drainage,antibiotics,and nutritional support(85%,17/20),whereas some required endoscopic retrograde cholangiopancreatography with stenting(10%,2/20)or percutaneous transhepatic cholangiography with drainage(5%,1/20).Risk factors for bile leakage include male sex,hepatocellular carcinoma,major hepatectomy,blood loss,and blood transfusion.CONCLUSION Bile leakage is a frequent complication of open hepatectomy for biliary tract cancer.However,most cases are mild and can be conservatively managed.Male sex,hepatocellular carcinoma,major hepatectomy,blood loss,and blood transfusion were associated with an increased risk of bile leak.

Endoscopic ultrasound-guided tissue sampling induced pancreatic duct leak resolved by the placement of a pancreatic stent:A case report

BACKGROUND Pancreatic ductal leaks complicated by endoscopic ultrasonography-guided tissue sampling(EUS-TS)can manifest as acute pancreatitis.CASE SUMMARY A 63-year-old man presented with persistent abdominal pain and weight loss.Diagnosis:Laboratory findings revealed elevated carbohydrate antigen 19-9(5920 U/mL)and carcinoembryonic antigen(23.7 ng/mL)levels.Magnetic resonance imaging of the pancreas revealed an approximately 3 cm ill-defined space-occupying lesion in the inferior aspect of the head,with severe encasement of the superior mesenteric artery.Pancreatic ductal adenocarcinoma was confirmed after pathological examination of specimens obtained by EUS-TS using the fanning method.Interventions and outcomes:The following day,the patient experienced severe abdominal pain with high amylase(265 U/L)and lipase(1173 U/L)levels.Computed tomography of the abdomen revealed edematous wall thickening of the second portion of the duodenum with adjacent fluid collections and a suspicious leak from either the distal common bile duct or the main pancreatic duct in the head.Endoscopic retrograde cholangiopancreatography revealed dye leakage in the head of the main pancreatic duct.Therefore,a 5F 7 cm linear plastic stent was deployed into the pancreatic duct to divert the pancreatic juice.The patient’s abdominal pain improved immediately after pancreatic stent insertion,and amylase and lipase levels normalized within a week.Neoadjuvant chemotherapy was then initiated.CONCLUSION Using the fanning method in EUS-TS can inadvertently cause damage to the pancreatic duct and may lead to clinically significant pancreatitis.Placing a pancreatic stent may immediately resolve acute pancreatitis and shorten the waiting time for curative therapy.When using the fanning method during EUSTS,ductal structures should be excluded to prevent pancreatic ductal leakage.

基于Phast-QRA的某油田拉油点密闭储油罐闪燃事故后果模拟分析

采用Phast-QRA软件对某拉油点密闭储油罐发生的闪燃事故进行事故后果模拟定量分析。根据事故发生时的场景及相关参数通过软件模拟计算出密闭储油罐在发生事故的死亡半径、重伤半径和轻伤半径等参数,模拟计算出事故的最大影响范围和严重程度,提出预防事故的安全技术和管理建议对策措施,为避免同类事故发生提供理论基础,为密闭储油罐的安生产运行提供技术支撑。

基于PHAST软件的输气管道事故后果模拟分析

为保证输气管道的安全平稳运行,基于大孔泄漏模型,利用PHAST软件模拟了不同压力下干气管道、湿气管道的扩散特性、热辐射特性和超压特性,并对危害区域的范围进行分析和探讨。结果表明,随着管输压力的上升,干气管道和湿气管道的扩散范围逐渐增大,压力分别对干气高危区和湿气液池区的影响较大;湿气条件下,不仅发生喷射火,还存在晚期池火事故;虽然湿气条件下的扩散范围较小,但液池积聚的能量较大,造成的热辐射和超压影响超过了干气条件,对地面管道、设备及建筑物的影响更大。研究结果可为应急救援水平的提升提供技术支撑。

基于PHAST的高压烃类注气管道安全防护距离研究

为了确定高压注气管道两侧安全防护距离,确保高压烃类注气管道及站场的本质安全,结合火灾爆炸事故伤害准则,以某伴生气驱试验高压注气管道为研究对象,基于PHAST软件模拟分析管道压力、管径、泄漏孔径及温度对气体泄漏的火灾热辐射距离、爆炸超压距离的影响。结果表明,不同因素对事故后果影响强弱顺序为:管径、温度、压力、泄漏孔径。建议在高压集输管道敷设过程中,应考虑发生泄漏时对周围环境的影响,明确影响范围,充分预留安全距离,初步建议DN25、DN50、DN80、DN100、DN150管道的安全防护距离应分别为35~40,65~75,100~110,127~135,200 m。

基于PHAST的CO_(2)露空管道大规模泄漏与放空模拟

为保障CO_(2)管道大规模泄漏和放空过程安全,防止CO_(2)扩散导致人员或地面生物伤亡,考虑泄漏和放空的情况,利用PHAST软件对CO_(2)管道大规模泄漏和放空时的浓度扩散情况进行数值模拟。以国内外安全标准中规定的安全浓度为研究依据,对CO_(2)泄漏影响范围进行模拟,研究分析得出不同介质相态、阀门开度、天气条件和泄漏放空角度对扩散范围的影响。通过总结模拟结果得到结论——使用垂直立管的计划泄漏放空不需要考虑地面危险浓度范围,全尺寸意外泄漏放空危险浓度范围与介质相态、天气条件和泄漏放空角度相关。

基于PHAST的储气库注采管道泄漏爆炸模拟分析

为提高地下储气库注采集输管道运行作业的安全性,针对管道泄漏爆炸伤亡危害事故的问题,基于储气库作业区现场生产特点,应用事故树法分析管道泄漏爆炸事故的主要影响因素;并采用PHAST软件模拟定量分析了注采气管道运行压力及管输介质对泄漏爆炸事故后果的影响,进行了事故的风险评估。结果表明,在给定的模拟参数下,管道事故的危害范围随管道运行压力升高而递增,气云扩散及爆炸冲击波形成的高危区域均较小;采用湿气输送模式的采气管线发生泄漏时,会造成喷射火及池火灾等多种火灾事故;风险评价曲线可直观地看出该储气库注采集输管道对井站周围企业人员、建筑以及储气库地面作业人员造成的危害。该研究结论可为储气库作业区进行应急预案体系建设及处置能力提升提供参考依据。

基于PHAST的天然气管道泄漏后果危害范围模拟研究

针对天然气管道泄漏引发的事故后果,依据相关计算理论及伤害准则,采用PHAST软件对不同输送压力、泄漏孔径、环境风速、泄漏方向等因素进行分析,确定了不同工况下室内人员及室外人员的伤亡范围。研究表明:影响火灾爆炸事故最严重的因素是泄漏孔径,造成人员伤亡半径的影响大小依次为:火球>喷射火>蒸气云爆炸,事故造成人员伤亡距离室外大于室内。根据国标相关计算公式计算某管线运行工况下的潜在影响半径略低于模拟值,因此国标对潜在影响半径的设置略为保守,该研究结果可为天然气扩散后果的影响因素及危害范围的研究提供参考。

Research on Leak Location Method of Water Supply Pipeline Based on MVMD

At present,the leakage rate of the water distribution network in China is still high,and the waste of water resources caused by water distribution network leakage is quite serious every year.Therefore,the location of pipeline leakage is of great significance for saving water resources and reducing economic losses.Acoustic emission technology is the most widely used pipeline leak location technology.The traditional non-stationary random signal de-noising method mainly relies on the estimation of noise parameters,ignoring periodic noise and components unrelated to pipeline leakage.Aiming at the above problems,this paper proposes a leak location method for water supply pipelines based on a multivariate variational mode decomposition algorithm.This method combines the two parameters of the energy loss coefficient and the correlation coefficient between adjacent modes,and adaptively determines the decomposition mode number K according to the characteristics of the signal itself.According to the correlation coefficient,the effective component is selected to reconstruct the signal and the cross-correlation time delay is estimated to determine the location of the pipeline leakage point.The experimental results show that this method has higher accuracy than the cross-correlation method based on VMD and the cross-correlation method based on EMD,and the average relative positioning error is less than 2.2%.

Choosing the best endoscopic approach for post-bariatric surgical leaks and fistulas:Basic principles and recommendations

Post-surgical leaks and fistulas are the most feared complication of bariatric surgery.They have become more common in clinical practice given the increasing number of these procedures and can be very difficult to treat.These two related conditions must be distinguished and characterized to guide the appropriate treatment.Leak is defined as a transmural defect with communication between the intra and extraluminal compartments,while fistula is defined as an abnormal communication between two epithelialized surfaces.Traditionally,surgical treatment was the preferred approach for leaks and fistulas and was associated with high morbidity with significant mortality rates.However,with the development of novel devices and techniques,endoscopic therapy plays an increasingly essential role in managing these conditions.Early diagnosis and endoscopic therapy initiation after clinical stabilization are crucial to success since clinical success rates are higher for acute leaks and fistulas when compared to late and chronic leaks and fistulas.Several endoscopic techniques are available with different mechanisms of action,including direct closure,covering/diverting or draining.The treatment should be individualized by considering the characteristics of both the patient and the defect.Although there is a lack of high-quality studies to provide standardized treatment algorithms,this narrative review aims to provide a summary of the current scientific evidence and,based on this data and our extensive experience,make recommendations to help choose the best endoscopic approach for the management of post-bariatric surgical leaks and fistulas.

A sutureless technique for securing leaking sclerotomies with viscoelastic substances in 23-gauge microincision vitrectomy surgery

AIM:To introduce and evaluate the clinical efficacy of a new technique,the use of viscoelastic substances(VS)to close leaking sclerotomy in 23G microincision vitrectomy,and to observe its effect on the visual acuity and intraocular pressure(IOP)of patients.METHODS:Patients who underwent 23G vitrectomy in Ningbo Eye Hospital before the use of VS technique(June 2019 to September 2020)and after the use of VS technique(October 2020 to December 2021)were selected as the subjects of this study.The above cases underwent operation by the same surgeon and were retrospectively analyzed.VS technique was used as the alternative to suturing,in which a small amount of VS was injected at the leaking sclerotomy and then gently massaged to confirm leaking sclerotomy closure.RESULTS:A total of 174 eyes were covered in the study,including 84 eyes in the control group(before the use of VS technique)and 90 eyes in the VS technique group.The number of eyes that needed to be sutured decreased considerably from 42.9%in the control group to 3.3%in the VS technique group,and the proportion of subconjunctival hemorrhage at 1-2d after surgery decreased remarkably from 35.7%in the control group to 2.2%in the VS technique group.No substantial differences in the incidence of mean IOP and low IOP were found between 1-2 and 3-20d after surgery in the VS technique group.No major complications associated with VS technique were identified during the study.CONCLUSION:In 23G microincision vitrectomy,VS technique is a safe,simple,and effective method to close leaking sclerotomy.

Negligible Warming Caused by Nord Stream Methane Leaks

Unanticipated sabotage of two underwater pipelines in the Baltic Sea(Nord Stream 1 and 2)happened on 26September 2022.Massive quantities of natural gas,primarily methane,were released into the atmosphere,which lasted for about one week.As a more powerful greenhouse gas than CO_(2),the potential climatic impact of methane is a global concern.Using multiple methods and datasets,a recent study reported a relatively accurate magnitude of the leaked methane at 0.22±0.03 million tons(Mt),which was lower than the initial estimate in the immediate aftermath of the event.Under an energy conservation framework used in IPCC AR6,we derived a negligible increase in global surface air temperature of 1.8×10^(-5)℃ in a 20-year time horizon caused by the methane leaks with an upper limit of 0.25 Mt.Although the resultant warming from this methane leak incident was minor,future carbon release from additional Earth system feedbacks,such as thawing permafrost,and its impact on the methane mitigation pathways of the Paris Agreement,warrants investigation.

A reliability-oriented genetic algorithm-levenberg marquardt model for leak risk assessment based on time-frequency features

Since leaks in high-pressure pipelines transporting crude oil can cause severe economic losses,a reliable leak risk assessment can assist in developing an effective pipeline maintenance plan and avoiding unexpected incidents.The fast and accurate leak detection methods are essential for maintaining pipeline safety in pipeline reliability engineering.Current oil pipeline leakage signals are insufficient for feature extraction,while the training time for traditional leakage prediction models is too long.A new leak detection method is proposed based on time-frequency features and the Genetic Algorithm-Levenberg Marquardt(GA-LM)classification model for predicting the leakage status of oil pipelines.The signal that has been processed is transformed to the time and frequency domain,allowing full expression of the original signal.The traditional Back Propagation(BP)neural network is optimized by the Genetic Algorithm(GA)and Levenberg Marquardt(LM)algorithms.The results show that the recognition effect of a combined feature parameter is superior to that of a single feature parameter.The Accuracy,Precision,Recall,and F1score of the GA-LM model is 95%,93.5%,96.7%,and 95.1%,respectively,which proves that the GA-LM model has a good predictive effect and excellent stability for positive and negative samples.The proposed GA-LM model can obviously reduce training time and improve recognition efficiency.In addition,considering that a large number of samples are required for model training,a wavelet threshold method is proposed to generate sample data with higher reliability.The research results can provide an effective theoretical and technical reference for the leakage risk assessment of the actual oil pipelines.

Progress in the study and treatment of peri-device leak after left atrial appendage closure

For patients with atrial fibrillation with an increased risk of stroke and contraindications to long-term anticoagulation,percutaneous left atrial appendage closure(LAAC)has become an important alternative to long-term oral anticoagulation.Incomplete closure of the LAAC during the procedure leads to faster blood flow in the interstitial space around the device,resulting in peri-device leak(PDL),which is not uncommon.Studies are still inconclusive in determining the incidence,long-term safety,and management of PDL.Therefore,this article reviewed the progress made in the research and treatment of PDL after LAAC.

Surgical treatment of mixed cervical spondylosis with spontaneous cerebrospinal fluid leakage: A case report

BACKGROUND Spontaneous cerebrospinal fluid(CSF)leaks associated with cervical spondylosis are rare.To our knowledge,only a few cases have been reported in which treatment is challenging and varies from case to case.Here,we review the literature and describe the surgical treatment of a 70-year-old woman who presented with a CSF leak due to a cervical spine spur.CASE SUMMARY A 70-year-old female patient who was treated for a cerebral infarction,presented with complains of weakness in the right lower extremity and a feeling of stepping on cotton.The patient underwent regular neck massage and presented with neck and right shoulder pain radiating to the right upper extremity one-month ago.Magnetic resonance imaging showed a strip of leaking cerebrospinal fluid posterior to the C1-4 vertebrae,and computed tomography showed a“sickleshaped”disc prolapse with calcification in C4/5.We chose to perform an anterior cervical discectomy.When the prolapsed C4/5 disc was scraped,clear fluid leakage was observed,and exploration revealed a 1 mm diameter rupture in the anterior aspect of the dura mater,which was compressed continuously with cotton patties,with no significant cerebrospinal fluid leakage after 1 h.CONCLUSION Three months after surgery,the patient was asymptomatic and follow-up imaging demonstrated complete resolution.

LPG储罐泄漏多事故场景下社区居民疏散仿真模拟与优化

为提高社区居民在化工厂多事故场景下应急疏散效率,以大庆市某化工厂和附近社区为例,考虑当地气象环境,利用ALOHA对LPG储罐泄漏事故进行模拟,得到多种事故危害范围和社区各区域可用安全疏散时间.通过Pathfinder构建社区疏散模型,分析了步行疏散、车行疏散和人车协同疏散三种模式下的疏散时间和拥堵状况.最后,通过路网优化和安全出口均衡分配,进行疏散优化模拟.结果表明:路网优化对步行疏散下的疏散效率提升最大为14.7%,安全出口均衡分配对车行疏散下的疏散效率提升最大为10.6%.车行疏散模式下可以在可用安全疏散时间内撤离受灾区域.