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利用Extra.FLV建设教学资源库
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作者 卞龙宝 《中国现代教育装备》 2010年第14期17-17,19,共2页
FLV是当前网络上最流行的视频格式,然而针对FLV格式文件进行剪辑、合并及转换等的操作并不是很方便。本文简单介绍了Extra.FLV软件在建设FLV格式视频教学资源库中的作用。
关键词 FLV视频教学extra.FLV资源库
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基于Extra Tree Classifier的水质安全建模预测
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作者 杨丽佳 陈新房 +1 位作者 赵晗清 汪世伟 《电脑与电信》 2024年第6期57-61,共5页
随着工业化和城市化的快速发展,水质安全问题日益受到关注。本研究利用一个包含7999条数据记录的水质分析数据集,涵盖多种化学物质浓度测量值与安全阈值,以及“是否安全”分类变量,运用Extr aTree Classifier模型进行水质安全建模预测... 随着工业化和城市化的快速发展,水质安全问题日益受到关注。本研究利用一个包含7999条数据记录的水质分析数据集,涵盖多种化学物质浓度测量值与安全阈值,以及“是否安全”分类变量,运用Extr aTree Classifier模型进行水质安全建模预测及数据分析。本研究目的在于提供一个可靠的模型,以帮助决策者和相关部门更好地监测和维护水质安全,从而保障公众健康和环境可持续发展。 展开更多
关键词 水质安全 Lazy Predict extra Tree Classifier k折交叉验证 机器学习
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Protective effects of oleic acid and polyphenols in extra virgin olive oil on cardiovascular diseases
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作者 Yan Lu Jun Zhao +6 位作者 Qiqi Xin Rong Yuan Yu Miao Manli Yang Hui Mo Keji Chen Weihong Cong 《Food Science and Human Wellness》 SCIE CSCD 2024年第2期529-540,共12页
The Mediterranean diet has long been recognized as one of the most effective ways to prevent and improve cardiovascular disease.Extra virgin olive oil(EVOO)is the typical sources of fat in the Mediterranean diet which... The Mediterranean diet has long been recognized as one of the most effective ways to prevent and improve cardiovascular disease.Extra virgin olive oil(EVOO)is the typical sources of fat in the Mediterranean diet which have been shown to have noteworthy nutritional value and positive impact on human health.It is worth noting that EVOO owes its superior nutritional value to its bioactive composition.The main component of EVOO is monounsaturated fatty acids(MUFAs)in the form of oleic acid.Oleic acid accounts for up to 70%-80%of EVOO.Secondly,EVOO contains approximately more than 30 phenolic compounds,of which HT is essential for the protection against cardiovascular diseases.In this review,we focused on the potential mechanisms of oleic acid and polyphenols combat cardiovascular diseases risk in terms of oxidative stress,inflammation,blood pressure,endothelial function and cholesterol.This review might provide a reference for the studies on cardiovascular protective effects of EVOO. 展开更多
关键词 Cardiovascular diseases extra virgin olive oil Oleic acid POLYPHENOLS
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Clinical outcomes in patients diagnosed with extra-nodal Hodgkin lymphoma: a 20-year retrospective analysis of the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database
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作者 Kingsley Nnawuba Anup Kumar Trikannad Ashwini Kumar +3 位作者 Sruthi Vellanki Tochukwu Nzeako Samantha Robinson Hanna Jensen 《Cancer Advances》 2024年第13期1-6,共6页
Background:Hodgkin lymphoma refers to a malignancy of the lymphatic tissue.Extra-nodal Hodgkin lymphoma(ENHL)is a rare variant consisting of Hodgkin lymphoma occurring outside the lymphatic system.Studies investigatin... Background:Hodgkin lymphoma refers to a malignancy of the lymphatic tissue.Extra-nodal Hodgkin lymphoma(ENHL)is a rare variant consisting of Hodgkin lymphoma occurring outside the lymphatic system.Studies investigating the epidemiology associated with ENHL are rare.Methods:618 ENHL cases were analyzed using the National Cancer Institute’s Surveillance,Epidemiology,and End Results(SEER)database(2000–2020).Demographics including sex,race/ethnicity,rural-urban continuum,age group(categorized as adolescent and young adult(AYA)if between years of 15 and 39,and adult if over the age of 40),and living status(alive/deceased)were examined,with survival status as the main outcome.Results:This study included 335 males(54.2%)and 283 females(45.8%).Of this total,47.9%were in the AYA group.In terms of ethnicity the distribution was 12.5%non-Hispanic Black,67.5%non-Hispanic White,5.2%non-Hispanic Asian/Pacific Islander,and 14.9%Hispanic.Bivariate analyses evidenced significant differences in survival by age group with 91.6%in AYA vs.72.4%in adults(P<0.001)alive by the end of the study period.Multivariable analyses identified age as a key predictor of survival,as the AYA patients had a lower odds ratio for death(odds ratio=0.25,P<0.001).In addition,survival outcomes were also impacted by race,with non-Hispanic Blacks showing higher survival probabilities.Regarding treatment,27.0%of patients underwent surgery,with 10.2%receiving post-surgery radiation,reducing odds of mortality(odds ratio=0.32,P=0.046).Conclusion:The background research as such,tends to affirm that these two factors–age and race are quite crucial in the prognosis as well as management of ENHL.Compared to adults,AYA patients had significantly lower odds of death,while non-Hispanic Black individuals exhibited reduced survival probabilities.It should be noted that 27.0%of patients underwent surgery with 10.2%receiving post-operative radiation which led to decrease in mortality rates.Thus,these results reiterate the necessity for tailor-made treatment methods according to demographic characteristics to boost patient outcomes effectively.For better ENHL care,future studies could shed light on these disparities and improve treatment regimens as needed. 展开更多
关键词 Hodgkin lymphoma extra nodal disease SEER cancer survival
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Extra-Axial Anaplastic Pleomorphic Xanthoastrocytoma Mimicking Meningioma: A Case Report with Literature Review
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作者 Kaoutar Stitou Ilias Zahir +5 位作者 Oualid Mohammed Hmamouche Marouane Hammoud Faycal Lakhdar Mohammed Benzagmout Khalid Chakour Mohammed El Faiz Chaoui 《Open Journal of Modern Neurosurgery》 2024年第3期203-211,共9页
Background: A number of meningeal neoplastic lesions may radiologically and clinically simulate meningioma, include hemangiopericytomas, solitary fibrous tumors, schwannomas, hematolymphoid lesions, metastases, and ot... Background: A number of meningeal neoplastic lesions may radiologically and clinically simulate meningioma, include hemangiopericytomas, solitary fibrous tumors, schwannomas, hematolymphoid lesions, metastases, and others very rarely, also may clinically mimic meningiomas. Case Description: We present the case of A 28-year-old male patient, with no notable medical history, who presented with worsening headaches for 3 months, imbalance, and visual deficits, An initial MRI revealed extra-axial lesion involving the right Parieto-occipital, The tumor was hypointense on T1-weighted MR images, hyperintense signals on T2-weightedMR images, and heterogeneously enhanced suggestive of a meningioma, total resection was achieved, and the histopathological analysis confirmed the diagnosis of an angioblastic meningioma. However, 15 months later, the patient presented with the same initial visual complaints. A subsequent MRI showed lesion recurrence, leading to a second surgical intervention. The histopathological analysis confirmed the diagnosis of an anaplastic xanthoastrocytoma. Conclusion: This represents an unusual location for an anaplastic pleomorphic xanthoastrocytoma, which should broaden the differential diagnosis of extra-axial lesions. 展开更多
关键词 Anaplastic Features BRAF extra-Axial High Mitotic Rate High Proliferation Index MENINGEAL Pleomorphic Xanthoastrocytoma
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Analysis of the Risk of Water Breakout in the Bottom Plate of High-Intensity Mining of Extra-Thick Coal Seams
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作者 Shuo Wang Hongdong Kang Xinchen Wang 《Journal of Geoscience and Environment Protection》 2024年第5期81-91,共11页
In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site moni... In order to clarify the danger of water breakout in the bottom plate of extra-thick coal seam mining, 2202 working face of a mine in the west is taken as the research object, and it is proposed to use the on-site monitoring means combining borehole peeping and microseismic monitoring, combined with the theoretical analysis to analyze the danger of water breakout in the bottom plate. The results show that: 1) the theoretically calculated maximum damage depth of the bottom plate is 27.5 m, and its layer is located above the Austrian ash aquifer, which has the danger of water breakout;2) the drill hole peeping at the bottom plate of the working face shows that the depth of the bottom plate fissure development reaches 26 m, and the integrity of the water barrier layer has been damaged, so there is the risk of water breakout;3) for the microseismic monitoring of the anomalous area, the bottom plate of the return air downstream channel occurs in the field with a one-week lag, which shows that microseismic monitoring events may reflect the water breakout of the underground. This shows that the microseismic monitoring events can reflect the changes of the underground flow field, which can provide a reference basis for the early warning of water breakout. The research results can provide reference for the prediction of sudden water hazard. 展开更多
关键词 extra-Thick Coal Seam High-Intensity Mining Microseismic Monitoring Water-Surge Hazard Borehole Peeping
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Novel Soft ComputingModel for Predicting Blast-Induced Ground Vibration in Open-Pit Mines Based on the Bagging and Sibling of Extra Trees Models 被引量:1
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作者 Quang-Hieu Tran Hoang Nguyen Xuan-Nam Bui 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第3期2227-2246,共20页
This study considered and predicted blast-induced ground vibration(PPV)in open-pit mines using bagging and sibling techniques under the rigorous combination of machine learning algorithms.Accordingly,four machine lear... This study considered and predicted blast-induced ground vibration(PPV)in open-pit mines using bagging and sibling techniques under the rigorous combination of machine learning algorithms.Accordingly,four machine learning algorithms,including support vector regression(SVR),extra trees(ExTree),K-nearest neighbors(KNN),and decision tree regression(DTR),were used as the base models for the purposes of combination and PPV initial prediction.The bagging regressor(BA)was then applied to combine these base models with the efforts of variance reduction,overfitting elimination,and generating more robust predictive models,abbreviated as BA-ExTree,BAKNN,BA-SVR,and BA-DTR.It is emphasized that the ExTree model has not been considered for predicting blastinduced ground vibration before,and the bagging of ExTree is an innovation aiming to improve the accuracy of the inherently ExTree model,as well.In addition,two empirical models(i.e.,USBM and Ambraseys)were also treated and compared with the bagging models to gain a comprehensive assessment.With this aim,we collected 300 blasting events with different parameters at the Sin Quyen copper mine(Vietnam),and the produced PPV values were also measured.They were then compiled as the dataset to develop the PPV predictive models.The results revealed that the bagging models provided better performance than the empirical models,except for the BA-DTR model.Of those,the BA-ExTree is the best model with the highest accuracy(i.e.,88.8%).Whereas,the empirical models only provided the accuracy from 73.6%–76%.The details of comparisons and assessments were also presented in this study. 展开更多
关键词 Mine blasting blast-induced ground vibration environmentally friendly blasting peak particle velocity BAGGING extra trees
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基于h-extra边连通度的增强超立方体Qn,3的链路容错性分析
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作者 孙亚莉 张明祖 《新疆大学学报(自然科学版)(中英文)》 CAS 2023年第6期646-653,共8页
并行处理系统的设计和维护在很大程度上依赖于并行处理系统的可靠性评价.h-extra边连通度为评估这些系统在大规模故障链路下的互连网络的容错性和可靠性提供了一个更精确的参数.1991年Tzeng和Wei提出了(n,3)-增强超立方体Q_(n,3).研究了... 并行处理系统的设计和维护在很大程度上依赖于并行处理系统的可靠性评价.h-extra边连通度为评估这些系统在大规模故障链路下的互连网络的容错性和可靠性提供了一个更精确的参数.1991年Tzeng和Wei提出了(n,3)-增强超立方体Q_(n,3).研究了(n,3)-增强超立方体Q_(n,3)的h-extra边连通度,λh(Q_(n,3)),存在一个集中现象.对于整数「(11×2^(n−1))/48」≤h≤2^(n−1)和n≥9,λh(Q_(n,3))的精确值集中在2^(n−1)上. 展开更多
关键词 互连网络 可靠性和链路容错性 集中现象 增强超立方体 h-extra边连通度
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基于VEPPSO-EXTRA混合算法的分布式直接定位技术
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作者 陈志坤 翁一鸣 +1 位作者 彭冬亮 吴美婵 《电子与信息学报》 EI CSCD 北大核心 2023年第2期664-671,共8页
相对于集中式直接定位技术,分布式直接定位算法具有计算复杂度小和通信代价小等优点,但存在定位精度损失的问题。针对于此,该文提出一种基于VEPPSO-EXTRA混合算法的分布式直接定位技术。首先,基于子空间融合的直接定位算法,推导其分布... 相对于集中式直接定位技术,分布式直接定位算法具有计算复杂度小和通信代价小等优点,但存在定位精度损失的问题。针对于此,该文提出一种基于VEPPSO-EXTRA混合算法的分布式直接定位技术。首先,基于子空间融合的直接定位算法,推导其分布式优化的数学模型;其次,基于多种群联合进化的思想,提出一种基于向量评估的并行粒子群算法(VEPPSO)实现全局寻优,由此得到辐射源迭代初始值;最后,引入分布式精确一阶算法(EXTRA)求解最终位置以降低分布式计算带来的精度损失。实验结果表明,相较于现有的分布式直接定位算法,该技术能解决定位精度损失的问题,且其计算复杂度与通信代价低于对应的集中式直接定位算法。 展开更多
关键词 分布式直接定位 传感器网络 基于向量评估的并行粒子群算法 精确1阶算法
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塔里木油田超深层钻井技术进展及难题探讨 被引量:5
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作者 王春生 王哲 +3 位作者 张权 卢俊安 陈凯枫 张超 《钻采工艺》 CAS 北大核心 2024年第2期59-69,共11页
当前,塔里木油田以超深特深层为代表的深地油气资源开发对满足我国经济发展需求和保障能源安全至关重要。经过数十年的探索和实践,塔里木油田创新形成了超深复杂井井身结构设计、超深难钻地层钻井提速、超深大斜度井水平井钻井、超深复... 当前,塔里木油田以超深特深层为代表的深地油气资源开发对满足我国经济发展需求和保障能源安全至关重要。经过数十年的探索和实践,塔里木油田创新形成了超深复杂井井身结构设计、超深难钻地层钻井提速、超深大斜度井水平井钻井、超深复杂地层钻完井液、超深复杂地层固井、高温高压井完整性、超深复杂井井控等一系列超深层钻井技术,保障深地油气勘探获得重大突破并创造多项纪录。伴随超深井数量持续增加,工程地质条件更加复杂,井下环境更加苛刻,超深层钻井过程势必面临新的工程难题和挑战,严重制约深地油气资源安全高效开发。为此,通过概括塔里木油田钻井工程技术发展历程,系统梳理了深地钻井工程技术取得的主要技术进展,并结合新的勘探开发形势与油气开发要求,指出了塔里木油田钻井工程技术从超深层迈入特深层新时期的焦点问题及攻关发展方向,为国内外深地复杂油气井安全高效钻进提供借鉴和参考。 展开更多
关键词 塔里木油田 超深层特深层 高温高压 钻井工程技术
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The relationship between extra connectivity and t/k-diagnosability under the PMC model
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作者 肖志芳 ZHONG Guoxuan +2 位作者 CHEN Jianqi GUO Chen PENG Shuo 《High Technology Letters》 EI CAS 2023年第3期305-309,共5页
It is well-known that connectivity is closely related to diagnosability.If the relationships be-tween them can be established,many kinds of diagnosability will be determined directly.So far,some notable relationships ... It is well-known that connectivity is closely related to diagnosability.If the relationships be-tween them can be established,many kinds of diagnosability will be determined directly.So far,some notable relationships between connectivity and diagnosability had been revealed.This paper in-tends to find out the relationship between extra connectivity and t/k-diagnosability under the PMC(Preparata,Metze,and Chien)model.Then,applying this relationship,the t/k-diagnosability of bijective connection(BC)networks are determined conveniently. 展开更多
关键词 extra connectivity t/k-diagnosability the PMC model
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Primary Extra-Gastrointestinal Stromal Tumors (E-GIST) of the Liver, about Two Cases and Review of the Literature Oncology Hospital Experience at Chu Hassan II in FES
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作者 Oumaima Siyouri Mohammed Ismaili +8 位作者 Khaoula Alaoui Ismaili Imane Stitou Hajar Medyouni Jihane Chouef Lamiae Amaadour Karima Oualla Zineb Benbrahim Samia Arifi Nawfel Mellas 《Journal of Cancer Therapy》 CAS 2023年第3期117-126,共10页
Introduction: Primary extra-gastrointestinal stromal tumors (E-GIST) of the liver are rare. The clinical presentation can range from asymptomatic to bleeding or manifestations of mass effect. Cancer surgery followed b... Introduction: Primary extra-gastrointestinal stromal tumors (E-GIST) of the liver are rare. The clinical presentation can range from asymptomatic to bleeding or manifestations of mass effect. Cancer surgery followed by adjuvant treatment with imatinib is the standard of care. However, in special circumstances, a cytoreductive approach may represent a therapeutic option. We describe here the case of two patients who presented with a painful and protruding epigastric mass, the first case was a localized E-GIST candidate for neoadjuvant treatment with imatinib with complete resection surgery thereafter with very good evolution, and the second is that of an E-GIST of the liver at an advanced stage with an evolution very quick to death. Conclusion: Primary liver E-GIST is a rare condition. Treatment is based on systemic therapy and total resection surgery. However, cytoreductive surgery will be required when complete resection is not possible. 展开更多
关键词 extra GIST Foie IMATINIB
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Left atrium veno-arterial extra corporeal membrane oxygenation as temporary mechanical support for cardiogenic shock:A case report
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作者 Rossana Lamastra David Michael Abbott +6 位作者 Antonella Degani Carlo Pellegrini Roberto Veronesi Stefano Pelenghi Chiara Dezza Giulia Gazzaniga Mirko Belliato 《World Journal of Clinical Cases》 SCIE 2023年第27期6531-6536,共6页
BACKGROUND Veno-arterial extra corporeal membrane oxygenation(VA-ECMO)support is commonly complicated with left ventricle(LV)distension in patients with cardiogenic shock.We resolved this problem by transeptally conve... BACKGROUND Veno-arterial extra corporeal membrane oxygenation(VA-ECMO)support is commonly complicated with left ventricle(LV)distension in patients with cardiogenic shock.We resolved this problem by transeptally converting VAECMO to left atrium veno-arterial(LAVA)-ECMO that functioned as a temporary paracorporeal left ventricular assist device to resolve LV distension.In our case LAVA-ECMO was also functioning as a bridge-to-transplant device,a technique that has been scarcely reported in the literature.CASE SUMMARY A 65 year-old man suffered from acute myocardial injury that required percutaneous stents.Less than two weeks later,noncompliance to antiplatelet therapy led to stent thrombosis,cardiogenic shock,and cardiac arrest.Femorofemoral VA-ECMO support was started,and the patient underwent a second coronary angiography with re-stenting and intra-aortic balloon pump placement.The VA-ECMO support was complicated by left ventricular distension which we resolved via LAVA-ECMO.Unfortunately,episodes of bleeding and sepsis complicated the clinical picture and the patient passed away 27 d after initiating VA-ECMO.CONCLUSION This clinical case demonstrates that LAVA-ECMO is a viable strategy to unload the LV without another invasive percutaneous or surgical procedure.We also demonstrate that LAVA-ECMO can also be weaned to a left ventricular assist device system.A benefit of this technique is that the procedure is potentially reversible,should the patient require VA-ECMO support again.A transeptal LV venting approach like LAVA-ECMO may be indicated over ImpellaTM in cases where less LV unloading is required and where a restrictive myocardium could cause LV suctioning.Left ventricular over-distention is a well-known complication of peripheral VA-ECMO in cardiogenic shock and LAVA ECMO through transeptal cannulation offers a novel and safe approach for treating LV overloading,without the need of an additional percutaneous access. 展开更多
关键词 Left atrium venoarterial extra corporeal membrane oxygenation Shock Case report
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单孔腹腔镜治疗肠套叠中腹内复位与腹外复位的疗效对比 被引量:1
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作者 刘红霞 宋翠萍 +2 位作者 李豪 饶旺 张海洋 《成都医学院学报》 CAS 2024年第1期80-83,88,共5页
目的探讨单孔腹腔镜治疗肠套叠中腹内复位与腹外复位的疗效。方法将新乡医学院第一附属医院2018年10月至2021年11月以彩色多普勒超声仪确诊的81例肠套叠患儿作为研究对象,所有患儿均行单孔腹腔镜治疗,治疗过程中根据复位方法不同分为腹... 目的探讨单孔腹腔镜治疗肠套叠中腹内复位与腹外复位的疗效。方法将新乡医学院第一附属医院2018年10月至2021年11月以彩色多普勒超声仪确诊的81例肠套叠患儿作为研究对象,所有患儿均行单孔腹腔镜治疗,治疗过程中根据复位方法不同分为腹内复位组和腹外复位组。收集患儿临床指标:血便、阵发性哭闹或腹痛、呕吐、腹部包块、肠套叠类型、病程;记录患儿手术时间、术中出血量、住院时间、术后排气/排便时间;记录术后感染、出血、肠黏连、肠梗阻、肠穿孔、复发情况和患儿家属满意度情况。结果腹内复位组、腹外复位组临床特征、肠套叠类型、病程、术中出血量、术后排气/排便时间、住院时间、术后感染、出血、肠黏连、肠梗阻、肠穿孔情况差异均无统计学意义(P>0.05),两组患儿均未复发肠套叠;与腹内复位组相比,腹外复位组手术时间降低、患儿家属满意度增加(P<0.05)。结论单孔腹腔镜治疗肠套叠中腹外复位患儿手术时间短、患儿家属满意度高,值得临床推广。 展开更多
关键词 单孔腹腔镜 肠套叠 腹内复位 腹外复位
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急倾斜深埋巨厚煤层掘巷冲击地压前兆特征及其灾害防治 被引量:1
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作者 来兴平 贾冲 +6 位作者 胥海东 崔峰 刘旭东 王昊 陆长亮 张随林 何仕凤 《煤炭学报》 EI CAS CSCD 北大核心 2024年第1期337-350,共14页
随着冲击地压矿井逐渐向深开采,其巷道掘进伴随的冲击显现愈发强烈。针对巷道掘进过程中的冲击地压有效防治问题,以新疆乌东煤矿急倾斜煤层矿井为例,运用微震监测对巷道掘进的冲击地压时空前兆特征加以分析。结合巷道掘进的应力与能量... 随着冲击地压矿井逐渐向深开采,其巷道掘进伴随的冲击显现愈发强烈。针对巷道掘进过程中的冲击地压有效防治问题,以新疆乌东煤矿急倾斜煤层矿井为例,运用微震监测对巷道掘进的冲击地压时空前兆特征加以分析。结合巷道掘进的应力与能量变化数值模拟分析,揭示巷道掘进的冲击地压发生机理,提出急倾斜巨厚煤层巷道冲击地压防治策略,并完成现场工程实践验证。研究结果表明:急倾斜巨厚煤层巷道掘进的冲击地压发生前第2~5天出现微震总能量极低值,或存在至少4 d的能量潜伏期;冲击地压发生前5 d普遍存在3 d以上的最大能量占比高频波动期。冲击地压发生前存在明显缺震现象,发生位置集中分布在距离掘进工作面较近的微震能量极小值区间范围内,或位于微震能量极值区间附近的微震频次极小值区间范围内,且冲击地压事件位于冲击变形能指数较高区域。急倾斜巨厚煤层水平分段综放开采的坚硬覆岩结构不易破断,使得巷道掘进存在上水平采空区两侧“双翼型”应力集中,掘进工作面前方与巷道底部受顶底板岩层相互挤压的应力集中分布且能量积聚显著,随着巷道掘进深度增加其应力集中与能量积聚进一步增强,容易诱发冲击地压等动力灾害。综合分析形成急倾斜巨厚煤层巷道掘进的工作面爆破卸压、巷道钻孔卸压与补强支护、复杂区域架蓬的冲击地压防治策略。结合冲击地压时空前兆异常为及时加强卸压力度提供时机。通过工作面与巷道卸压使得掘进期间未发生单日累计1×105 J以上微震能量,在对支护优化调整与复杂区域重点防护后,巷道掘进日均微震能量降至2.2 kJ,其1 kJ以上微震事件占比下降且巷道断面整体平整。研究结果为急倾斜巨厚煤层巷道安全掘进提供了科学依据。 展开更多
关键词 急倾斜巨厚煤层 巷道掘进 冲击地压 前兆特征 防治策略
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求解连续Sylvester矩阵方程的E-extra迭代法
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作者 马昌凤 《应用数学》 北大核心 2023年第1期220-229,共10页
本文提出一种求解连续Sylvester方程的E-extra迭代法,分析该方法的收敛性,给出最优参数的选取方法.并通过几个数值实例验证了E-extra迭代法的有效性.
关键词 连续Sylvester方程 E-extra迭代法 收敛性分析 数值实验
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深层碳酸盐岩储层酸压进展与展望 被引量:2
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作者 郭建春 苟波 +4 位作者 陆灯云 刘子豪 肖彬 徐科 任冀川 《钻采工艺》 CAS 北大核心 2024年第2期121-129,共9页
酸压改造是深层碳酸盐岩储层高效勘探开发的技术利器。随着勘探开发逐渐迈向特深层,厘清目前酸压技术发展现状与趋势至关重要。从酸压裂缝起裂与扩展、酸刻蚀水力裂缝与导流能力构建、酸压数值模拟技术3个方面阐释了酸压改造机理;分析... 酸压改造是深层碳酸盐岩储层高效勘探开发的技术利器。随着勘探开发逐渐迈向特深层,厘清目前酸压技术发展现状与趋势至关重要。从酸压裂缝起裂与扩展、酸刻蚀水力裂缝与导流能力构建、酸压数值模拟技术3个方面阐释了酸压改造机理;分析了黏度控制型、生酸时间控制型、H+屏蔽吸附型、非盐酸基型等4类耐高温缓速酸液体系特点;系统梳理了我国深层碳酸盐岩酸压工艺技术发展的4个历程,剖析了目前9000 m以深特深层碳酸岩酸压面临的4个挑战:能否压开储层、地层温度突破酸液体系耐温极限、高温高压测试手段缺乏、储集体靶向沟通难度大。基于此,提出了5个酸压研究展望:特深井破裂压力精准预测、耐220℃多功能酸液体系研发、超高温高压实验平台构建、全在线酸压技术、超临界CO_(2)酸压技术探索,力求实现特深层碳酸盐岩高效立体开发。 展开更多
关键词 深层超深层 特深层 碳酸盐岩 酸压机理 酸液体系 酸压工艺
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基于特级初榨橄榄油两种不同特性的DSC掺假分析方法研究 被引量:1
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作者 魏燕 宋志强 武卫东 《食品与发酵工业》 CSCD 北大核心 2024年第1期183-188,共6页
该文基于油脂物理特性与氧化稳定性2种特性,利用差示扫描量热法(differential scanning calorimetry,DSC)对市面上常见的特级初榨橄榄油(extra virgin olive oil,EVOO)中大豆油掺假问题进行研究。在物理特性方面,采用DSC冷却曲线来分析E... 该文基于油脂物理特性与氧化稳定性2种特性,利用差示扫描量热法(differential scanning calorimetry,DSC)对市面上常见的特级初榨橄榄油(extra virgin olive oil,EVOO)中大豆油掺假问题进行研究。在物理特性方面,采用DSC冷却曲线来分析EVOO掺假。随着大豆油掺假比例升高,油样在-40~-60℃结晶焓值ΔH由EVOO的29.78 J/g减小为40%掺假混合油的6.133 J/g,对EVOO质量比构建的一元回归方程Y=57.556X-28.44(R2=0.997)。在氧化稳定性方面,氧化温度160℃下,不同油样诱导氧化时间随大豆油掺假比例上升逐渐变短,由EVOO的25.8 min逐渐减小为40%掺假混合油的17.8 min,Y=-19.4X+25.64(R^(2)=0.996),掺假模型相关性较好。这2种DSC检验掺假分析方法都能有效鉴别EVOO中大豆油的掺假且各有特点,可根据实际情况选取合适的方法更好处理EVOO掺假问题。 展开更多
关键词 特级初榨橄榄油 大豆油 物理特性 氧化稳定性 差示扫描量热法 掺假鉴定
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四川盆地超深层钻完井技术进展及其对万米特深井的启示 被引量:3
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作者 佘朝毅 《天然气工业》 EI CAS CSCD 北大核心 2024年第1期40-48,共9页
四川盆地超深层海相碳酸盐岩油气资源丰富,是寻找特大型油气田、开拓油气增储上产新领域的重要方向,但超深层钻完井面临地层条件更加复杂、井筒环境更加极端等工程技术挑战。为进一步指导万米特深井的安全高效钻探,通过梳理超深层钻完... 四川盆地超深层海相碳酸盐岩油气资源丰富,是寻找特大型油气田、开拓油气增储上产新领域的重要方向,但超深层钻完井面临地层条件更加复杂、井筒环境更加极端等工程技术挑战。为进一步指导万米特深井的安全高效钻探,通过梳理超深层钻完井技术难点,系统总结了四川盆地超深层钻完井关键技术,并提出了下步钻完井技术的发展建议。研究结果表明:①形成的超深复杂地层三压力预测监测技术精确预测了复杂地层压力系统及地应力场分布,准确刻画断层、裂缝、溶洞等展布规律,结合非常用井身结构拓展技术,提高了井身结构设计应对复杂地层钻探的能力;②形成的钻—测—固—完全过程精细控压技术,解决了超深井、特殊复杂井钻井液安全密度窗口窄导致“溢漏共存”、固井质量低等难题;③研发的高效钻头与大扭矩螺杆、扭力冲击器等抗高温提速工具,解决了深部难钻地层钻井钻头易磨损、破岩效率低的工程难题;④研发的抗高温钻井液体系提升应对高温深井的钻井液技术保障能力,升级第二代韧性水泥,解决了工作液抗高温能力不足等难题,保障超深井建井质量。结论认为,超深层钻完井技术的发展与进步,使得深井钻深能力突破9000 m已经成为现实,形成的关键技术有力地支撑了四川盆地超深层油气资源的高效勘探开发,对于万米特深层科学钻探和油气增储上产新领域拓展具有重要技术支撑作用。 展开更多
关键词 四川盆地 超深层 钻完井技术 技术进展 万米特深井 难题与挑战 发展建议
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Exploration of Traversable Wormholes Sustained by an Extra Spatial Dimension
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作者 Peter K. F. Kuhfittig 《International Journal of Astronomy and Astrophysics》 2023年第3期141-153,共13页
The main goal of this paper is to determine the effect of an extra dimension on a traversable wormhole. Here an earlier study by the author [Phys. Rev. D 98, 064041 (2018)] is extended in several significant ways. To ... The main goal of this paper is to determine the effect of an extra dimension on a traversable wormhole. Here an earlier study by the author [Phys. Rev. D 98, 064041 (2018)] is extended in several significant ways. To begin with, the extra spatial dimension is assumed to be time dependent, while the redshift and shape functions, as well as the extra dimension, are functions of both r and l, the respective radial and extra coordinates;the last of these is therefore a function of r, l, and t. The main objective is to determine the conditions that allow the throat of the wormhole to be threaded with ordinary matter (by respecting the null energy condition) and that the same conditions lead to a violation of the null energy condition in the fifth dimension, which is therefore responsible for sustaining the wormhole. The dependence of the extra dimension on l and t is subject to additional conditions that are subsequently analyzed in this paper. Finally, the extra dimension may be extremely small or even curled up. 展开更多
关键词 Traversable Wormholes extra Spatial Dimension Time Dependence
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