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Control of Unit Power Factor PWM Rectifier
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作者 Meifang Xue Mingzhi He 《Energy and Power Engineering》 2013年第4期121-124,共4页
To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the re... To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reactive current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation. 展开更多
关键词 CONTROL PWM RECTIFIER unit Power factor d q COORDINATES
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The Contribution Margin due to a Limiting Factor in the Presence of Several Sales Options: Actuality Is Not Always As It Appears at the Beginning of the Analysis
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作者 Maria Silvia Avi 《Journal of Modern Accounting and Auditing》 2023年第1期1-22,共22页
The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sal... The analysis of company data useful for economic decisions,if not interpreted in an overall view of the company situation,can lead to wrong conclusions.This is the case when a company has to choose between several sales options for one or more products in the presence of a limiting factor.The continuation of the investigation often denies the initial analysis.Not everything is as it appears,therefore,at the beginning of the deepening of the data useful for economic decisions.As it is well known,the choices of profitability concerning the planning of the sale of company products take place,at least in the majority of cases,through the determination of the contribution margin,i.e.the profitability margin connected to the individual goods/services sold by the companies(selling price net of variable costs).The contribution margin can be determined with four objectives:(1)Determination of the yield of the single product,net of variable costs only.In this case,the margin defines unitary,from net product yield to unitary contribution margin.(2)Determination of the return on total sales of an individual product,net of variable costs.In this hypothesis,reference is made to the first level(or gross)contribution margin.(3)Determination of the ability of the individual product to contribute to the coverage of fixed costs common to the company.This margin is determined net of special product variable and fixed costs.This aggregate is defined as a Level II(or semi-gross)margin.(4)Determination of the useful value in the planning choices in case of presence of scarce productive factors.In this case,it must identify the so-called unitary margin for low factor.Here we will only deal with the problem of the use of the contribution margin in the presence of rare factors.To complete the analysis,below are some very brief considerations regarding,respectively,the unitary,level I,and level II contribution margin in order to better understand where the problem of the most convenient choice of income is located in the event of the presence of rare production factors,especially in an environment characterized by a plurality of sales options. 展开更多
关键词 contribution margin unit contribution margin first level contribution margin second level contribution margin unit Scarce factor contribution margin unit Scarce factor contribution margin in the presence of a plurality of sales options profit
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Risk factors and antibiotic resistance of pneumonia caused by multidrug resistant Acinetobacter baumannii in pediatric intensive care unit 被引量:2
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作者 Xiao-fang Cai Ji-min Sun +1 位作者 Lian-sheng Bao Wen-bin Li 《World Journal of Emergency Medicine》 CAS 2012年第3期202-207,共6页
With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannfi (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannfi (MDRAb) emerging an... With beta-lactam drugs and immunosuppressants widely used, the infection caused by Acinetobacter baumannfi (Ab) has become more and more serious with multidrug resistant Acinetobacter baumannfi (MDRAb) emerging and worsening rapidly. Compared with other patients, the incidence and multidrug resistance of MDRAb are higher in children in pediatric intensive care unit (PICU) because of immune deficiency, severe basic diseases, prolonged hospitalization and invasive operations. Hence it is significant to study the epidemiology and changes of antibacterial susceptibility in order to reduce the incidence of MDRAb in children. A total 115 patients with MDRAb pneumonia and 45 patients with negative MDRAb (NMDRAb) pneumonia who had been treated from January 2009 to August 2011 were studied retrospectively at the PICU of Wuhan Children's Hospital. Clinical data were analyzed with univariate and multivariate Logistic regression. In 176 clinical strains of Acinetobacter baumannfi isolated, there were 128 strains of MDRAb, accounting for 72.73%. Drug susceptibility tests showed that the resistance rates of 13-1actam antibiotics were more than 70% except for cefoperazone sulbactam. The rates to carbapenems were higher than 90%. They were significantly higher than those of NMDRAb. Amikacin, levofloxacin, ciprofloxacin and minocycline had the lowest drug-resistance rates (〈20%). Multivariate Logistic regression revealed that ICU stay, the time of mechanical ventilation, anemia, hypoproteinemia and the use of carbapenems were independent risk factors for MDRAb pneumonia. MDRAb is an important opportunistic pathogen to pneumonia in PICU, and its drug-resistance is severe. It increases significantly the mortality of patients. It is important to take the effective prevention measures for controlling it. 展开更多
关键词 PEDIATRIC Intensive Care unit Multidrug resistance Acinetobacter baumannii PNEUMONIA Risk factor Retrospective study
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Prognostic Factors for Acute Heart Failure (AHF) in the Cardiology Intensive Care Unit (ICU) of the University Hospital Point G (UH Pt G)
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作者 Camara Youssouf Ba Hamidou Oumar +10 位作者 Sangare Ibrahima Toure Karamba Coulibaly Souleymane Sacko Abdoul Karim Coulibaly Alfousseyni Diallo Nouhoum Sidibe Samba Daou Adama Menta Ichaka Diall Ilo Bella Diallo Boubakar Abdoulaye 《World Journal of Cardiovascular Diseases》 2019年第1期42-50,共9页
Background and Aim: The absence of data in our context motivates this study aiming to determine the frequency of AHF at the ICU, assess the in-hospital evolution of the disease and to find out poor prognosis.Material ... Background and Aim: The absence of data in our context motivates this study aiming to determine the frequency of AHF at the ICU, assess the in-hospital evolution of the disease and to find out poor prognosis.Material and Methods: It was an observational and descriptive study covering the time from January 1, 2014 to March 30, 2017 involving all inpatient records in ICU. From January 2014 to December 2017, collected data included those on socio-demographic, history of diseases and physical examination, and some labor dataincluding Pro BNP, serum creatinine, blood ionogram,?cardiac enzymes and blood count. Also data electrocardiography, echocardiography and in-hospital evolution were collected. Statistical Analysis:Statistical analysis was performed using SPSS (IBM Inc) version 18. Results: AHF occured in 47.36% with a mean age of 58.74 ± 18.407 and extremes of 17 and 90 years, women representing 53.1% (sex ratio Male:Female = 0.88). Hypertension and diabetes were the predominant cardiovascular risk factors with respectively 67.4% and 18.4%. At admission?44%, 37.7% and 17.9% of patients were respectively hypertensive,?normotensive and hypotensive. The clinical expression was mainly global heart failure with 42.6% followed by left heart failure and right heart failure with respectively 37% and 20.4%. The coronary syndromes (all forms) was the first cause of ICA with 34% of cases followed by pulmonary embolism and hypertension with respectively 25.3% and 24.1%. Mean hospital stay was 5.61 ± 3.527 days (1 to 25 days). Complications were recorded in 18.5% of patients with cardiogenic shock in half of all cases. In multi-variate analysis, only hypotension at admission was shown to be the independent factor of poor prognosis with p = 0.016 and OR = 4.453 (1.322 - 14.996). Conclusion: As a common manifestation heart failure can be rapidly fatal in presence of collapsus or hypotension at admission. These factors should be accurately managed to reduce mortality, which remains high in our context. 展开更多
关键词 Acute Heart Failure PROGNOSTIC factors CARDIOLOGY INTENSIVE Care unit BAMAKO
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Study of the Frequency of Cardiovascular Diseases and Their Risk Factors in the Emergency Units of Two Hospitals in Dakar (Senegal)
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作者 Pêngd-Wendé Habib Boussé Traore Jean Augustin Diegane Tine +4 位作者 Oumar Bassoum Cheikh Tidiane Mbow Ababacar Diop Abdoul Kane Adama Faye 《Open Journal of Internal Medicine》 2021年第3期123-139,共17页
<strong>Introduction:</strong> Cardiovascular diseases constitute the deadliest pathology in the world with 31% of global mortality in 2018. This is how we felt it necessary to conduct a study on cardiovas... <strong>Introduction:</strong> Cardiovascular diseases constitute the deadliest pathology in the world with 31% of global mortality in 2018. This is how we felt it necessary to conduct a study on cardiovascular diseases in emergency units of Senegal, more precisely in Dakar, in order to know epidemiological profile of these patients. <strong>Methods:</strong> The study setting was the reception and emergency units of the Hôpital de Pikine and Hôpital Principal de Dakar. This was an observational, descriptive cross-sectional study with an analytical aim to search for factors associated with the occurrence of cardiovascular disease. The study ran from January 25th to February 5th, 2018 at the Hôpital de Pikine and from February 25th to March 5th, 2018 at Hôpital Principal de Dakar. The source population consisted of patients over 18 years of age and not in a state of pregnancy, who were been received there and had given their free and informed consent to participate in the survey. A representative sample had drawn and a consecutive recruitment of eligible patients were been carried out. The data collection tools were been based on the WHO STEPwise survey questionnaire. Data collection was been carried out in accordance with ethical rules. <strong>Results:</strong> The study involved 615 patients. The proportions of sedentary lifestyle, low daily consumption of fruits/vegetables, overweight and obesity were 72.4%, 96.4%, 22.7% and 17.3% respectively. This was 55.5% of women who had a waist circumference that corresponded to a high risk of a cardiovascular event and 10.2% for men. 38.9% of patients had blood pressure above 140/90mmhg and 32.2% said they had never controlled their blood pressure in their life. The use of a consultation in a health structure to control his blood pressure was by far the most frequent modality with 61.4%. The proportion of people with cardiovascular disease was 50.1%. Hypertensive flare-ups/hypertensive emergencies were the leading complications diagnosed with 33.33%. Factors associated with the occurrence of cardiovascular disease were sex, age, professional status and body mass index. <strong>Discussion & Conclusion:</strong> The risk factors for cardiovascular disease are highly represented in our emergency units. In addition to the available care offer, the identification of factors associated with the occurrence of cardiovascular diseases in patients who are been seen there will allow targeted preventive actions within this fragile and vulnerable population. All this to help achieve target 3.4 of the Sustainable Development Goals (SDGs) by 2030. Furthermore, according to the associated factors identified, it appears that achieving SDG 8 will greatly contribute to the prevention of cardiovascular disease. This proves the urgency and interest of an integrated multi-ministerial vision in our strategic plans for the prevention against major non-communicable diseases and cardiovascular diseases in particular. 展开更多
关键词 Risk factors Cardiovascular Diseases Emergency units Senegal
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Predictive risk factors for prolonged stay in intensive care unit in patients undergoing coronary artery bypass grafting surgery
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作者 袁忠祥 《外科研究与新技术》 2011年第3期183-184,共2页
Objective To describe the preoperative factors of prolonged intensive care unit length of stay after coronary artery bypass grafting. Methods From 1997 to 2009, 1318 patients underwent isolated CABG in our hospital. R... Objective To describe the preoperative factors of prolonged intensive care unit length of stay after coronary artery bypass grafting. Methods From 1997 to 2009, 1318 patients underwent isolated CABG in our hospital. Retrospective analysis was performed on these cases. Univariate and multivariate analyses 展开更多
关键词 length CABG Predictive risk factors for prolonged stay in intensive care unit in patients undergoing coronary artery bypass grafting surgery LVEF
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ICU护士导尿管相关尿路感染预防知信行现况及影响因素
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作者 张欢 张琦 吕汇颖 《护理研究》 北大核心 2024年第6期1076-1080,共5页
目的:调查重症监护室(ICU)护士导尿管相关尿路感染(CAUTI)预防知信行现况,并分析其影响因素。方法:选取2022年1月在上海交通大学医学院附属第一人民医院ICU工作的临床护士195人作为研究对象,采用一般资料调查表、CAUTI预防培训调查表、C... 目的:调查重症监护室(ICU)护士导尿管相关尿路感染(CAUTI)预防知信行现况,并分析其影响因素。方法:选取2022年1月在上海交通大学医学院附属第一人民医院ICU工作的临床护士195人作为研究对象,采用一般资料调查表、CAUTI预防培训调查表、CAUTI预防知信行量表进行调查。结果:ICU护士在CAUTI知识中留置导尿适应证维度得分为(28.50±3.23)分,知识中CAUTI预防策略维度得分为(58.84±5.34)分,信念维度得分为(24.85±3.52)分,行为维度得分为(21.45±2.59)分;是否参加过培训的情况不同,我院ICU护士的CAUTI预防知识、行为得分不同(P<0.05);科室、工作年限、近3年参加培训的次数不同,我院ICU护士的CAUTI预防知信行得分不同(P<0.05)。结论:我院ICU护士整体的CAUTI预防知信行水平较高,但仍存在不足,医疗机构应扩大培训范围,改变ICU护士的经验性认知,提高ICU护士对于CAUTI的知信行水平。 展开更多
关键词 导尿管相关尿路感染(CAUTI) 知识 信念 行为 重症监护室(ICU) 影响因素 护理
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ICU患者暴露性角膜炎风险评估量表的编制及信效度检验
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作者 厉春林 张雅芝 +2 位作者 周雁荣 刘洪娟 王兰 《护理学杂志》 CSCD 北大核心 2024年第14期37-40,共4页
目的编制ICU患者暴露性角膜炎风险评估量表,并检验其信度和效度。方法基于循证系统查阅文献编制量表初始条目池;通过2轮德尔菲专家函询,形成初始版量表;采用方便抽样法选取298例ICU患者,采用暴露性角膜炎风险评估量表进行调查,对量表信... 目的编制ICU患者暴露性角膜炎风险评估量表,并检验其信度和效度。方法基于循证系统查阅文献编制量表初始条目池;通过2轮德尔菲专家函询,形成初始版量表;采用方便抽样法选取298例ICU患者,采用暴露性角膜炎风险评估量表进行调查,对量表信效度进行检验,并绘制受试者工作特征曲线确定最佳临界值。结果ICU患者暴露性角膜炎风险评估量表包括3个维度、12个条目;2轮函询专家积极系数分别为100%和80.95%,权威系数为0.892、0.888,肯德尔和谐系数为0.364和0.492;量表整体的Cronbach′sα系数为0.834,折半信度为0.795,评定者间信度0.841,内容效度为0.917;最佳临界值为8.5分,受试者工作特征曲线下面积为0.925。结论ICU患者暴露性角膜炎风险评估量具有良好的信效度,可用于ICU患者暴露性角膜炎的风险评估。 展开更多
关键词 重症监护病房 暴露性角膜炎 危险因素 风险评估 量表 信度 效度 重症护理
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我院重症监护室肺部感染菌群特征及影响因素分析
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作者 曾凤 李强 杨健 《中外医学研究》 2024年第24期156-159,共4页
目的:探讨阜宁县人民医院重症监护室(ICU)患者的肺部感染菌的特征及其影响因素。方法:回顾性地分析2021年6月—2023年7月阜宁县人民医院不同科室重症监护室收治的1682例患者的临床资料,统计肺部感染菌的种群分布情况。采用随机数表法从... 目的:探讨阜宁县人民医院重症监护室(ICU)患者的肺部感染菌的特征及其影响因素。方法:回顾性地分析2021年6月—2023年7月阜宁县人民医院不同科室重症监护室收治的1682例患者的临床资料,统计肺部感染菌的种群分布情况。采用随机数表法从感染患者(n=108)和非感染患者(n=1574)中各随机抽取70例患者作为感染组(n=70)与非感染组(n=70),对所选样本采用单因素和多因素logistic回归分析ICU患者肺部感染的重要影响因素。结果:3年内,在1682例ICU患者中,发生肺部病原菌感染者108例。从感染的患者体内共分离出病原菌共计205株,其中革兰氏阴性菌147株(71.7%),阳性菌30株(14.6%),真菌28株(13.7%)。通过单因素和多因素logistic回归分析,ICU患者肺部病原菌感染与多种主要因素有关,其中包括ICU住院时间、广谱抗菌药物使用天数、糖皮质激素应用时间、是否使用气管插管、是否留置尿管气管插管、基础疾病。结论:ICU感染菌群以革兰氏阴性菌为主。引发ICU患者肺部感染的主要因素为ICU住院时间、广谱抗菌药物使用天数、糖皮质激素应用时间、是否使用气管插管、是否留置尿管气管插管、基础疾病种类数。 展开更多
关键词 重症监护室 肺部感染菌群 影响因素
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Predictive risk factors associated with prolonged stay in the intensive care unit for patients undergoing coronary artery bypass grafting surgery
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作者 杨毅 《外科研究与新技术》 2011年第3期178-178,共1页
Objective The rate of post-operative complications has been increased with the changes in patients’age,prolonged duration,more severe and diffused lesions,and more patients with complications in recent years. We try ... Objective The rate of post-operative complications has been increased with the changes in patients’age,prolonged duration,more severe and diffused lesions,and more patients with complications in recent years. We try to identify the risk factors associated with prolonged stay in the intensive care unit (ICU) after coronary artery bypass graft surgery (CABG) . Methods 1623 patients who received CABG surgery in Beijing Anzhen Hospital 展开更多
关键词 CABG Predictive risk factors associated with prolonged stay in the intensive care unit for patients undergoing coronary artery bypass grafting surgery
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新生儿重症监护室患儿再入院现况及影响因素分析
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作者 林颖 廖金花 +2 位作者 滕灵晶 吴丽丽 张芳淼 《护理实践与研究》 2024年第1期37-42,共6页
目的了解新生儿重症监护室(neonatal intensive care unit,NICU)患儿再入院现况及相关影响因素,为危重新生儿后期临床实践提供参考的依据。方法回顾性收集福建省某三级甲等医院2020年8月—2022年7月NICU收治患儿的临床资料,根据纳入条... 目的了解新生儿重症监护室(neonatal intensive care unit,NICU)患儿再入院现况及相关影响因素,为危重新生儿后期临床实践提供参考的依据。方法回顾性收集福建省某三级甲等医院2020年8月—2022年7月NICU收治患儿的临床资料,根据纳入条件、排除条件将发生再入院的224例患儿作为再入院组,采用1:1病例对照研究的方法,选取未发生再入院224例患儿为非再入院组,收集两组患儿入院诊断、性别、出生胎龄、出生体质量、出生身长、生后1 min Apgar评分、是否使用呼吸机、出院时C反应蛋白(CRP)、白细胞、血胆红素水平及母亲分娩方式、母亲年龄、孕产次等方面的资料,采用单因素分析及二元Logistic回归分析NICU患儿再入院的影响因素。结果NICU患儿再入院率为1.75%(224/12816);出院1周内再入院150例(66.96%)、出院1~2周再入院患儿43例(19.20%);再入院主要诊断为新生儿高胆红素血症101例(45.09%)、消化系统疾病35例(15.63%)、呼吸系统疾病34例(15.18%)、围生期感染33例(14.73%);NICU患儿再入院的Logistic逐步回归分析结果显示,胎龄与出院时CRP水平为NICU患儿再入院影响因素。结论胎龄与出生时CRP水平是影响NICU患儿再入院的主要因素,NICU医护人员应综合考虑患儿出生胎龄及出院时的CRP水平,及时解决家长在照护过程中的困难,提醒家长定期随访,尽可能保证其出院时控制CRP水平在正常范围内,以期减少NICU患儿再入院率。 展开更多
关键词 新生儿 新生儿重症监护室 再入院 影响因素 诊断 胎龄
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老年脓毒症患者重症监护室内发生下肢深静脉血栓的危险因素
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作者 牛驰 汪岩 张冉 《血管与腔内血管外科杂志》 2024年第6期646-649,654,共5页
目的探讨老年脓毒症患者重症监护室(ICU)内发生下肢深静脉血栓(DVT)的危险因素。方法收集2020年4月至2021年9月首都医科大学附属北京天坛医院收治的83例老年脓毒症患者的临床资料,根据ICU住院期间是否发生下肢DVT将患者分为DVT组(n=25)... 目的探讨老年脓毒症患者重症监护室(ICU)内发生下肢深静脉血栓(DVT)的危险因素。方法收集2020年4月至2021年9月首都医科大学附属北京天坛医院收治的83例老年脓毒症患者的临床资料,根据ICU住院期间是否发生下肢DVT将患者分为DVT组(n=25)和对照组(n=58)。收集所有患者入住ICU的临床资料,包括年龄、性别、主要疾病、既往病史、化验结果、检查结果、ICU住院期间治疗情况及ICU住院结局等。比较两组患者的临床特征和住院期间治疗情况,采用多因素Logistic回归模型分析老年脓毒症患者ICU内发生下肢深静脉血栓(DVT)的危险因素。结果DVT组患者的糖尿病比例、下肢功能障碍比例、入院时D-二聚体水平升高比例及使用呼吸机的比例均高于对照组患者,差异均有统计学意义(P﹤0.05)。多因素分析结果显示,糖尿病、下肢功能障碍、入院时D-二聚体水平升高及使用呼吸机均是老年脓毒症患者ICU住院期间发生下肢DVT的危险因素(P﹤0.05)。结论糖尿病、下肢功能障碍、入院时D-二聚体水平升高及使用呼吸机均会增加老年脓毒症患者ICU住院期间发生下肢DVT的风险,临床中应对这些患者强化预防和监测。 展开更多
关键词 老年 脓毒症 重症监护室 深静脉血栓 危险因素
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重症监护病房多重耐药菌感染分布情况及影响因素分析 被引量:1
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作者 曾祥泰 张庆英 +2 位作者 逄楠 李艳操 许晓佳 《中国医药科学》 2024年第11期186-190,共5页
目的分析重症监护病房(ICU)患者多重耐药菌(MDRO)感染的分布情况及其危险因素,并提出相关的预防和控制措施。方法本研究以2021年7月至2022年12月汕头市某三级甲等医院ICU收治的1407例患者为对象,回顾性收集其住院期间是否发生MDRO感染,... 目的分析重症监护病房(ICU)患者多重耐药菌(MDRO)感染的分布情况及其危险因素,并提出相关的预防和控制措施。方法本研究以2021年7月至2022年12月汕头市某三级甲等医院ICU收治的1407例患者为对象,回顾性收集其住院期间是否发生MDRO感染,分析MDRO感染发生率和分布情况,并分为MDRO感染组和非MDRO感染组进行比较,采用多因素logistic回归筛选MDRO感染的相关危险因素。结果ICU共有1407例住院患者均接受细菌培养及耐药菌株检测,其中男性患者为880例,女性患者为527例;MDRO感染发生率为18.69%(263/1407)。ICU中MDRO感染菌株主要涉及大肠埃希菌、金黄色葡萄球菌和肺炎克雷伯菌等。多因素分析结果显示,合并心血管病(OR=1.453,95%CI 1.006~2.079)、广谱抗生素使用时长≥1周(OR=1.900,95%CI 1.377~2.620)、使用≥2联抗生素(OR=1.913,95%CI 1.378~2.655)、留置血管内导管(OR=2.456,95%CI 1.416~3.241)与MDRO感染风险增高有关(P<0.05)。结论ICU患者中MDRO的感染发生率相对其他普通病区仍处于较高水平,应针对MDRO感染的特点和相关的高危因素及时采取预防和控制措施,有效降低MDRO的感染发生率。 展开更多
关键词 重症监护病房 多重耐药菌 感染 影响因素
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三相电压型VIENNA整流器建模及稳定性分析 被引量:1
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作者 范家宁 马辉 +2 位作者 何奇 范李平 马晓妍 《电力科学与技术学报》 CAS CSCD 北大核心 2024年第1期243-250,共8页
基于电动汽车直流充电桩的VIENNA型前级整流电路,提出采用小信号方法对VIENNA整流器进行建模。该方法首先通过采用局部线性化技术和状态空间平均法推导dq0坐标系下VIENNA整流器的数学模型,得出相关传递函数矩阵,即VIENNA整流器小信号线... 基于电动汽车直流充电桩的VIENNA型前级整流电路,提出采用小信号方法对VIENNA整流器进行建模。该方法首先通过采用局部线性化技术和状态空间平均法推导dq0坐标系下VIENNA整流器的数学模型,得出相关传递函数矩阵,即VIENNA整流器小信号线性化模型,进而用于控制器的设计;然后,采用频域法分别对电压环、电流环进行设计,利用频域法及根轨迹曲线详细分析各项参数对系统的影响,并利用曲线拟合的方式给出了系统稳定域随各项参数变化的曲线;最后,在实验中验证所提方法的正确性。 展开更多
关键词 VIENNA整流器 小信号建模 单位功率因数 状态平均 稳定性分析
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全麻患者术后麻醉重症监护室中新发下肢深静脉血栓的危险因素 被引量:1
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作者 王晓飞 孙铭阳 张加强 《临床麻醉学杂志》 CAS CSCD 北大核心 2024年第1期56-60,共5页
目的筛选全麻术后转入麻醉重症监护室(AICU)的患者新发下肢深静脉血栓(DVT)的危险因素。方法回顾性收集2022年5—8月择期行全麻下手术后带气管插管转入AICU的患者192例,男105例,女87例,年龄18~85岁,BMI 18~31 kg/m^(2),ASAⅡ或Ⅲ级。收... 目的筛选全麻术后转入麻醉重症监护室(AICU)的患者新发下肢深静脉血栓(DVT)的危险因素。方法回顾性收集2022年5—8月择期行全麻下手术后带气管插管转入AICU的患者192例,男105例,女87例,年龄18~85岁,BMI 18~31 kg/m^(2),ASAⅡ或Ⅲ级。收集患者基线资料、麻醉手术资料及实验室检查资料。根据入AICU 6 h内的超声结果是否有新发DVT将患者分为两组:DVT组和非DVT组。采用多因素Logistic回归分析筛选AICU中患者术后6 h内新发DVT的危险因素及其95%可信区间(CI)。结果全麻术后在AICU新发DVT的患者有64例(33.3%),均为小腿肌间静脉血栓(CMVT)。多因素Logistic回归分析结果显示,术前心律失常(OR=2.236,95%CI 1.011~4.943,P=0.047)、术前血小板计数高(OR=1.006,95%CI 1.002~1.010,P=0.007)、术前D⁃二聚体浓度高(OR=1.203,95%CI 1.046~1.383,P=0.010)、术中低血压(OR=1.010,95%CI 1.002~1.019,P=0.020)和术中应用去甲肾上腺素(OR=3.796,95%CI 1.697~8.492,P=0.001)是全麻术后AICU中患者新发DVT的危险因素;阿司匹林规律服用史(OR=0.176,95%CI 0.060~0.518,P=0.002)是其保护因素。结论术前心律失常、术前血小板计数高、术前D⁃二聚体浓度高、术中低血压及术中应用去甲肾上腺素是全麻手术后AICU患者6 h内新发DVT的危险因素。 展开更多
关键词 下肢深静脉血栓 全麻 麻醉重症监护室 危险因素
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基于故障树法的氯乙烯氧氯化单元失效影响因素分析
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作者 边清 王发亮 刘源 《安全、健康和环境》 2024年第6期1-5,共5页
为解决频繁非计划停工问题,利用故障树分析法,对某氯乙烯装置氧氯化单元的危险性因素进行分析,构建氧氯化单元系统异常故障树,确定了催化剂跑损、旋风分离器故障堵塞等为氧氯化单元失效的主要因素,采取针对性措施后效果良好。
关键词 氯乙烯装置 氧氯化单元 故障树 失效影响因素 长周期
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一种基于因子图的RIMU/GNSS组合导航算法
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作者 胡任祎 史丽楠 +2 位作者 崔莹莹 贺彦峰 陈平 《航天控制》 CSCD 2024年第4期10-15,共6页
针对传统基于滤波方法的RIMU/GNSS组合导航系统因载体大幅度机动条件下滤波结果不稳定的问题,提出了一种基于因子图的估计方法。建立面向冗余惯性导航系统的状态方程与量测方程,并将冗余惯性数据融合至载体坐标系三轴。建立基于因子图... 针对传统基于滤波方法的RIMU/GNSS组合导航系统因载体大幅度机动条件下滤波结果不稳定的问题,提出了一种基于因子图的估计方法。建立面向冗余惯性导航系统的状态方程与量测方程,并将冗余惯性数据融合至载体坐标系三轴。建立基于因子图的数据融合方法,将融合后的惯性数据与卫星信息抽象为因子节点,状态信息抽象为变量节点,构建包括惯性因子与GNSS因子的代价函数并以非线性优化的方式对状态量进行估计。数字仿真证实,因子图方法能有效降低载体的位置误差,且均方根误差明显小于卡尔曼滤波算法。 展开更多
关键词 冗余惯组 因子图 信息融合
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基于K-GRU神经网络的采煤机记忆截割及优化
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作者 安葳鹏 闫鹏皓 +1 位作者 张文博 孙旭旭 《河南理工大学学报(自然科学版)》 CAS 北大核心 2024年第1期96-104,共9页
目的针对采煤机记忆截割不准确、自动化程度不高的问题,方法本文提出一种基于KGRU神经网络的采煤机记忆截割算法,此算法具有更适合处理长时序数据的特点,将算法与采煤机记忆截割结合起来,可以减少采煤过程中滚筒的损坏同时保护工人生命... 目的针对采煤机记忆截割不准确、自动化程度不高的问题,方法本文提出一种基于KGRU神经网络的采煤机记忆截割算法,此算法具有更适合处理长时序数据的特点,将算法与采煤机记忆截割结合起来,可以减少采煤过程中滚筒的损坏同时保护工人生命安全。该算法在深层门控循环单元(GRU)的输入端引入比例因子K,用比例因子K表现不同时刻数据的重要程度,以加强模型对长时序数据的记忆性,进而提高记忆截割精度。在模型训练阶段利用随机搜索算法(RS)对深层K-GRU神经网络的超参数选择进行优化,加快模型训练速度。结果实验中使用Python完成K-GRU模型构建与超参数优化,使用随机搜索算法可以在更短时间内得到超参数最优解,得到超参数epochs为317、batch_size为70的最优解共花费154 s,在最优解情况下计算模型对真实采煤数据预测的误差,得到K-GRU的loss值为0.0467、R2为0.9578、EVS为0.9656、ME为0.0833。结论最终表明,优化后的深层K-GRU模型在解释方差得分、最大误差和可决系数方面均优于SVM、KNN、LSTM、RNN和普通GRU模型,显著提高了采煤机记忆截割的适用性和准确性。 展开更多
关键词 门控循环单元 记忆截割 随机搜索算法 强化因子 采煤机
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“双碳”目标下旅游碳排放影响因素变化规律研究
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作者 宋立 顾至欣 郭剑英 《生态经济》 北大核心 2024年第5期132-137,188,共7页
以旅游碳排放为研究对象,以南京为起点,通过设计四种不同的旅游线路,重点分析交通方式、住宿形式、旅游活动内容等不同旅游环节对碳排放的影响变化规律。研究结果表明,与近郊游相比,省际游交通碳排放最高可达近郊游的18.9倍和73.5倍。... 以旅游碳排放为研究对象,以南京为起点,通过设计四种不同的旅游线路,重点分析交通方式、住宿形式、旅游活动内容等不同旅游环节对碳排放的影响变化规律。研究结果表明,与近郊游相比,省际游交通碳排放最高可达近郊游的18.9倍和73.5倍。在同样选择快捷酒店的情况下,省际游住宿碳排放量是近郊游的8.9倍和13.3倍。随着旅游距离的增加,交通方式碳排放占比逐渐增大。近郊游交通方式碳排放占比为25.4%,而省际游三亚交通碳排放占比高达53.4%,超过了旅游活动所产生的碳排放占比。1次近郊游产生的碳排放所需要的碳汇森林面积约168.8 m2,而省际游青岛和海南三亚所产生的碳排放需要的碳汇森林面积高达1423.77 m2和2948.74 m2,省际游所需碳汇森林面积是近郊游的8.43倍和17.47倍。研究结论对旅游政策的制定、节假日规划以及旅游线路规划具有很好的指导和借鉴作用。 展开更多
关键词 旅游碳排放 “双碳”目标 影响因素 变化规律 能量消耗 单位碳排放
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基于DEMATEL-ISM方法的水电站机组检修作业安全事故致因链分析 被引量:1
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作者 晋良海 张荣昊 +3 位作者 明华军 李钰涵 李晨曦 邹颂香 《水利水电科技进展》 CSCD 北大核心 2024年第1期37-43,51,共8页
针对水电站机组检修作业种类和危险因素多、安全事故频发等问题,通过文献挖掘与专家访谈方式,对水电站机组检修作业安全影响因素类别进行了划分。基于DEMATEL-ISM方法,构建了安全事故致因多层次递阶ISM模型来确定事故致因因素层级,通过... 针对水电站机组检修作业种类和危险因素多、安全事故频发等问题,通过文献挖掘与专家访谈方式,对水电站机组检修作业安全影响因素类别进行了划分。基于DEMATEL-ISM方法,构建了安全事故致因多层次递阶ISM模型来确定事故致因因素层级,通过剖析事故致因因素的中心度和权重,挖掘关键致因因素和推求事故致因链的路径权重,厘定关键致因链。采用该模型对某水电站致因链进行了分析,结果表明,安全检查不到位为关键致因因素,“安全检查不到位→违规作业→设备的问题→粉尘、油漆等有害物质”为关键致因链。 展开更多
关键词 水电站机组检修 DEMATEL-ISM方法 事故致因链 致因因素权重 路径权重
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