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Overexpression of wild-type HRAS drives non-alcoholic steatohepatitis to hepatocellular carcinoma in mice
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作者 Chen Ling Su-Su Liu +9 位作者 Yu-Ya Wang Gui-Tao Huo Yan-Wei Yang Nan Xu Hong Wang Yong Wu Yu-Fa Miao Rui Fu Yu-Wei Zhao Chang-Fa Fan 《Zoological Research》 SCIE CSCD 2024年第3期551-566,共16页
Hepatocellular carcinoma(HCC),a prevalent solid carcinoma of significant concern,is an aggressive and often fatal disease with increasing global incidence rates and poor therapeutic outcomes.The etiology and pathologi... Hepatocellular carcinoma(HCC),a prevalent solid carcinoma of significant concern,is an aggressive and often fatal disease with increasing global incidence rates and poor therapeutic outcomes.The etiology and pathological progression of non-alcoholic steatohepatitis(NASH)-related HCC is multifactorial and multistage.However,no single animal model can accurately mimic the full NASH-related HCC pathological progression,posing considerable challenges to transition and mechanistic studies.Herein,a novel conditional inducible wild-type human HRAS overexpressed mouse model(HRAS-HCC)was established,demonstrating 100%morbidity and mortality within approximately one month under normal dietary and lifestyle conditions.Advanced symptoms of HCC such as ascites,thrombus,internal hemorrhage,jaundice,and lung metastasis were successfully replicated in mice.In-depth pathological features of NASH-related HCC were demonstrated by pathological staining,biochemical analyses,and typical marker gene detections.Combined murine anti-PD-1 and sorafenib treatment effectively prolonged mouse survival,further confirming the accuracy and reliability of the model.Based on protein-protein interaction(PPI)network and RNA sequencing analyses,we speculated that overexpression of HRAS may initiate the THBS1-COL4A3 axis to induce NASH with severe fibrosis,with subsequent progression to HCC.Collectively,our study successfully duplicated natural sequential progression in a single murine model over a very short period,providing an accurate and reliable preclinical tool for therapeutic evaluations targeting the NASH to HCC continuum. 展开更多
关键词 HRAS THBS1 HCC driver factor NASH FIBROSIS Cirrhosis HCC Treatment evaluation
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Serum Concentrations of Angiotensin, C-Reactive Protein, Interleukin-8, and Tumor Necrosis Factor-α in Train Driver Population
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作者 Ziwei Zhu Linxiong Wu +5 位作者 Aihua Liu Mei Zhou Fukai Bao Cuiping Xu Jiaru Yang Hua Zhao 《Open Journal of Immunology》 2016年第1期7-13,共7页
Train drivers are engaged in high-stress job. It may induce sleep, fatigue, and alertness loss at work, and endanger public safety. It’s unclear that cytokines of train driver would be influenced by their job. The re... Train drivers are engaged in high-stress job. It may induce sleep, fatigue, and alertness loss at work, and endanger public safety. It’s unclear that cytokines of train driver would be influenced by their job. The research considers the hypothesis that stressful professions, such as train driver, influence the body’s immune system through the long-time and high-pressure working, and change production of neuro-immune factors. Using enzyme linked immunosorbent assay (ELISA), several neuro-immune factors were assayed among train drivers (N = 82) and health blood donors (N = 80) enrolled in the Yunnan Collaborative Innovation Center for Public Health and Disease Control. The concentrations of angiotensin, C-reactive protein (CRP), interleukin-8 (IL-8), and tumor necrosis factor-alpha (TNF-α) were determined. Kruskal-Wallis test and Dunn’s multiple comparisons test were performed for overall comparison between groups and for pairwise comparison, respectively. Statistical significance level was set at P < 0.05. The profession of train driving was not associated with significant increases or decreases in the systemic levels of inflammatory (CRP, IL-8, and TNF-α), but it was associated with the high expression of angiotensin in vivo. These findings suggest that the job of train driving may not be associated with significant alterations in systemic immune condition, but arouse the level of angiotensin. 展开更多
关键词 Train driver Occupational Stress ANGIOTENSIN C-Reactive Protein INTERLEUKIN-8 Tumor Necrosis factor-Alpha
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一种无桥高增益单级LED驱动电路及其混合控制策略
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作者 刘光清 林维明 陈欣玮 《电机与控制学报》 EI CSCD 北大核心 2024年第1期105-119,共15页
中小功率的LED驱动电源中,传统两级LED驱动电源存在体积大、成本高以及传统Boost PFC电路在低压输入时导通损耗大等问题。为此提出一种由无桥二次型Boost PFC电路和DC-DC LLC电路集成的无桥高增益单级LED驱动电路,实现了高电压增益、功... 中小功率的LED驱动电源中,传统两级LED驱动电源存在体积大、成本高以及传统Boost PFC电路在低压输入时导通损耗大等问题。为此提出一种由无桥二次型Boost PFC电路和DC-DC LLC电路集成的无桥高增益单级LED驱动电路,实现了高电压增益、功率开关器件软开关、一套控制电路和高电路转换效率。针对单级电路在电网输入电压变化引起直流母线电压变动范围大等问题,设计一种适用于所提电路的APWM-PFM混合控制策略,并对混合控制原理和控制过程进行详细分析。最后设计一台200 W的实验样机,在输入电压80~120 Vrms范围内,占空比最大为0.5,最大电压增益为6.7,直流母线电压基于网侧特性和LLC电路特性设计在700 V以内,样机的功率因数值均高于0.990,THD均低于15%。在满载条件下,110 Vrms输入时,样机效率为93.20%,相比于传统无桥PFC,电压增益提高了2.21倍,实现了高电压增益和软开关,有效提升了在低压输入条件下的电路转换效率。仿真和实验结果验证了所提出电路和控制方法的有效性。 展开更多
关键词 LED驱动电路 功率因数校正 高增益Boost与LLC电路集成 混合控制策略 软开关
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基于无源均流的谐振式无桥型Boost LED驱动电源
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作者 史旭 刘雪山 +1 位作者 周群 王春涛 《电源学报》 CSCD 北大核心 2024年第2期369-377,共9页
传统Boost功率因数校正变换器的输出电压必须大于输入电压,在一定程度上限制了其在LED驱动电源中的应用。同时,传统LED驱动电源因输入端整流桥的存在而限制了自身效率的进一步提升。基于谐振式Boost功率因数校正变换器拓扑提出了一种无... 传统Boost功率因数校正变换器的输出电压必须大于输入电压,在一定程度上限制了其在LED驱动电源中的应用。同时,传统LED驱动电源因输入端整流桥的存在而限制了自身效率的进一步提升。基于谐振式Boost功率因数校正变换器拓扑提出了一种无源均流型无桥Boost LED驱动电源,通过引入谐振式电容均流网络,实现了多路均流输出;通过整流桥的去除,进一步提升了系统的效率。最后,搭建了一台效率可达93.64%的140 W实验样机,验证了理论分析的正确性与可行性。 展开更多
关键词 无桥变换器 LED驱动电源 功率因数校正 无源均流
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危险货物运输驾驶人风险倾向分类及识别模型研究
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作者 沈小燕 韩小强 +3 位作者 羊家豪 郭丹 陈煜 董相勇 《安全与环境学报》 CAS CSCD 北大核心 2024年第4期1531-1538,共8页
为合理评估危险货物运输驾驶人驾驶过程中的风险倾向,建立危险货物运输驾驶人风险倾向聚类及辨识体系,以动态监控系统中记录的驾驶人实时违规预警数据为基础,选取可能引发交通冲突的安全关键事件为特征参数,利用探索性因子分析方法实现... 为合理评估危险货物运输驾驶人驾驶过程中的风险倾向,建立危险货物运输驾驶人风险倾向聚类及辨识体系,以动态监控系统中记录的驾驶人实时违规预警数据为基础,选取可能引发交通冲突的安全关键事件为特征参数,利用探索性因子分析方法实现指标降维,提取驾驶人风险倾向主因子,并通过K means算法聚类不同风险倾向的驾驶人,最后基于聚类结果监督训练随机森林模型,辨识未知驾驶人的风险倾向。结果表明,利用选取的8类安全关键事件特征参数,可以将驾驶人风险倾向划分为攻击驾驶倾向、鲁莽驾驶倾向、驾驶分神倾向和驾驶疲劳倾向,且可以识别风险较低的驾驶人,基于随机森林模型的驾驶人风险倾向识别准确率为88.68%,可以较好地实现危险货物运输驾驶人风险倾向辨识。研究结果为危险货物运输驾驶人风险倾向分类及识别提供了方法依据。 展开更多
关键词 安全工程 危险货物运输 驾驶人 风险倾向 安全关键事件(SCEs) 探索性因子分析 随机森林(RF)
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兴隆山典型林分土壤呼吸的空间异质性分析
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作者 凌雷 马成艳 +3 位作者 陈徵尼 仲怡铭 王子乔 王翠英 《兰州大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第1期76-83,共8页
为探明兴隆山森林生态系统典型林分土壤碳呼吸的日变化、月际动态特征及其影响因子,利用LI-8100土壤呼吸测定室对辽东栎林、山杨-白桦混交林、油松林和青杄林土壤呼吸速率(R_(s))进行连续观测,采用指数方程拟合R_(s)对土壤温度(T_(5))... 为探明兴隆山森林生态系统典型林分土壤碳呼吸的日变化、月际动态特征及其影响因子,利用LI-8100土壤呼吸测定室对辽东栎林、山杨-白桦混交林、油松林和青杄林土壤呼吸速率(R_(s))进行连续观测,采用指数方程拟合R_(s)对土壤温度(T_(5))、土壤含水量(W_(5))的响应.结果表明,各林分覆枯落物与裸地的Rs日变化均呈先增加后下降的单峰型曲线,但达到峰值的时间各不相同,各林分R_(s)与T_(5)间均有显著相关性.各林分R_(s)在8月达到峰值,为2.6~7.0μmol/(m^(2)·s),与其土壤性质的表现一致:辽东栎林和杨桦混交林土壤容重较低,具有较高的全氮、全磷及有机质含量,其Rs亦较高,油松林、青杄林表现相反.枯落物对各林分R_(s)的贡献率分别为59.83%(辽东栎林)、41.46%(山杨-白桦混交林)、28.68%(油松林)和11.83%(青杄林),各林分覆枯落物时的Rs明显高于裸地.不同林分Rs的变化特征是水热因子联合效应的结果,R_(s)受T_(5)影响最大,受W_(5)的影响作用相对较小. 展开更多
关键词 典型林分 土壤呼吸速率 驱动因子 兴隆山
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芜湖市公交驾驶员职业倦怠现状及影响因素分析
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作者 崔跃 沈棫华 +2 位作者 王芳 朱文礼 葛文静 《沈阳医学院学报》 2024年第2期141-145,共5页
目的:了解芜湖市公交驾驶员职业倦怠现况,并分析职业倦怠相关影响因素。方法:于2022年9至11月采用一般资料调查表、职业倦怠量表-普适版(MBI-GS)、匹兹堡睡眠质量指数量表(PSQI)对芜湖市1388名公交驾驶员进行问卷调查。采用多因素Logis... 目的:了解芜湖市公交驾驶员职业倦怠现况,并分析职业倦怠相关影响因素。方法:于2022年9至11月采用一般资料调查表、职业倦怠量表-普适版(MBI-GS)、匹兹堡睡眠质量指数量表(PSQI)对芜湖市1388名公交驾驶员进行问卷调查。采用多因素Logistic回归分析影响公交驾驶员职业倦怠的因素,采用Spearman相关性分析探讨公交驾驶员职业倦怠总分及其各维度得分与睡眠质量总分及其各维度得分的相关性。结果:1388名公交驾驶员中,职业倦怠阳性的有642名,占46.3%;存在睡眠障碍的有139名,占10.0%。多因素Logistic回归分析显示公交驾龄长(OR=1.873,95%CI:1.325~2.648)、月收入低(OR=0.376,95%CI:0.158~0.774)、吸烟频率高(OR=1.313,95%CI:1.188~2.163)、饮酒频率高(OR=1.342,95%CI:1.018~1.769)、每周体育锻炼次数少(OR=0.367,95%CI:0.243~0.555)、睡眠质量差(OR=13.110,95%CI:7.284~23.594)是公交驾驶员职业倦怠的影响因素(P<0.05),Spearman相关性分析结果显示公交驾驶员职业倦怠总分及其各维度得分与睡眠质量总分及其各维度得分均呈正相关(r_(s)=0.12~0.83,P<0.01)。结论:芜湖市公交驾驶员职业倦怠问题较严重,一部分驾驶员存在睡眠问题,应引起高度重视并及时采取积极的应对措施。 展开更多
关键词 公交驾驶员 职业倦怠 睡眠质量 影响因素
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一种BCM Boost PFC电路的VCFF控制策略
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作者 刘光清 林维明 《电器与能效管理技术》 2024年第3期7-14,29,共9页
临界导通模式Boost功率因素校正(PFC)电路通常采用恒定导通时间(COT)控制策略,导致开关频率的变化与输入电压、输出功率以及电感有关,轻载下过高的开关频率将影响电路的转换效率,故提出一种谷底计数频率反走(VCFF)控制策略。通过检测MO... 临界导通模式Boost功率因素校正(PFC)电路通常采用恒定导通时间(COT)控制策略,导致开关频率的变化与输入电压、输出功率以及电感有关,轻载下过高的开关频率将影响电路的转换效率,故提出一种谷底计数频率反走(VCFF)控制策略。通过检测MOS管两端电压谷底计数,使电路轻载时工作在断续模式,从而降低开关频率以提升轻载效率。实验结果表明,相比于COT控制策略,所提控制策略能够有效提高轻载效率。输入电压为220 Vrms下,10%~50%负载时效率在0.96以上。 展开更多
关键词 LED驱动电源 Boost功率因素校正电路 临界导通模式 轻载效率
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公共交通噪声性听力损失研究进展
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作者 司文静 李博 马小卫 《中国听力语言康复科学杂志》 2024年第3期270-274,共5页
公共交通噪声是指交通工具运行时产生的妨害人们正常生活和工作的声音。分为机动车噪声、飞机噪声、火车噪声等。一般指机动车辆在城市内交通干线上行驶时产生的噪声。在飞速发展的时代,因公共交通造成的听力损失不容小觑。造成听力损... 公共交通噪声是指交通工具运行时产生的妨害人们正常生活和工作的声音。分为机动车噪声、飞机噪声、火车噪声等。一般指机动车辆在城市内交通干线上行驶时产生的噪声。在飞速发展的时代,因公共交通造成的听力损失不容小觑。造成听力损失的公共交通来源广泛,如公交车、地铁等,听力损失的占比也有初步统计,目前探究的可能影响因素有工龄和身体的健康情况等,可能的机制有声波对内耳机械刺激以及氧化应激等。听力损失的防治也主要是通过管理和保护措施来控制噪声源、切断噪声传播途径和加强个人防护等。本文就近年来公共交通驾驶员噪声性听力损失的特点、机制、防治等进行综述。以期对公共交通驾驶员噪声性听力损失的深入研究及减少我国因公共交通造成的噪声性听力损失的发病率有提供参考。 展开更多
关键词 公共交通驾驶员 噪声性听力损失 影响因素及机制 防治
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An empirical research on driving factors of CSR of foreignfunded enterprises from the perspective of ecological civilization
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作者 LI Wen-long 《Ecological Economy》 2016年第4期336-342,共7页
The significance of the construction of ecological civilization lies not only in the protection and management of the ecological environment in China, but also in the improvement of people's awareness of the prote... The significance of the construction of ecological civilization lies not only in the protection and management of the ecological environment in China, but also in the improvement of people's awareness of the protection of the natural environment and the unique understanding of the relationship between man and man, society and man and nature, the deep analysis of the relationship between between economic development and environmental protection. Taking the ecological civilization as the angle of view, taking 20 foreign-funded enterprises in Hohhot, Baotou, Erdos and Chifeng of Inner Mongolia Autonomous Region as the research object, using the questionnaire method, the basic data of the enterprises are analyzed by mathematical statistics. The conclusion is that the driving factors of the basic social responsibility of the foreign-funded enterprises mainly come from the requirements of relevant laws and regulations. The main driving force of the medium-level corporate responsibility comes from the promotion of corporate brand image, and the main driving force of corporate responsibility comes from obtaining legal business. 展开更多
关键词 ecological civilization foreign-funded enterprises social responsibility driver factors
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基于最佳观感效果的电子后视镜图像处理方法
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作者 曾雨晴 王珺珲 +1 位作者 姚思威 王正家 《湖北工业大学学报》 2024年第2期34-37,共4页
传统玻璃后视镜风阻风噪大,无法接入智能驾驶系统,所以电子后视镜取代传统后视镜已成为趋势。但电子后视镜使用鱼眼摄像机,所显示图像畸变大,无法像玻璃后视镜一样在近距离放大驾驶员所关注的视野,远距离缩小物体以此显示更多视野。通... 传统玻璃后视镜风阻风噪大,无法接入智能驾驶系统,所以电子后视镜取代传统后视镜已成为趋势。但电子后视镜使用鱼眼摄像机,所显示图像畸变大,无法像玻璃后视镜一样在近距离放大驾驶员所关注的视野,远距离缩小物体以此显示更多视野。通过对玻璃视镜放大系数和驾驶员视野角和物距的分析,得出适用于电子后视镜图像放大系数变换的方法,根据此方法对电子后视镜图像进行处理,以此达到显示最佳观感。实验结果证明,变换后的电子后视镜图像各处放大系数与玻璃视镜相差为9.52%,优于市面上仅经过鱼眼矫正的图像显示效果,在司机主观观感上能很好地提供“近距离放大外部环境,远距离更大视野”的功能,提高了驾驶安全性。 展开更多
关键词 鱼眼矫正 电子后视镜 放大系数 商用车驾驶员视野
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Adaptive Continuous Current Source Drivers for 1-MHz Boost PFC Converters 被引量:2
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作者 ZHANG Zhiliang XUPengcheng CAI Wei 《中国电机工程学报》 EI CSCD 北大核心 2012年第27期I0014-I0014,共1页
针对高频功率因数校正(power factor correction,PFC)变换器,提出自适应电流源驱动电路(current source driver,CSD)。由于PFC变换器的占空比在一个输入工频周期内不断变化,半桥结构CSD驱动电路很难应用于PFC场合中。为了解决... 针对高频功率因数校正(power factor correction,PFC)变换器,提出自适应电流源驱动电路(current source driver,CSD)。由于PFC变换器的占空比在一个输入工频周期内不断变化,半桥结构CSD驱动电路很难应用于PFC场合中。为了解决上述问题,提出全桥结构CSD电路。该CSD电路具有连续电感电流,且驱动电流会随着主功率MOSFET开关电流的自适应调整,以实现最优设计。详细给出工作原理、损耗分析和设计优化方法,并进行实验验证。 展开更多
关键词 PFC 驱动器 电流源 自适应 BOOST 变换器 功率MOSFET 功率因数校正
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Analyzing Drivers’ Mental Patterns Using Q-Methodology
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作者 Abbas Sheykhfard Farshid Reza Haghighi +1 位作者 Mostafa Soltaninejad Ali Karji 《Journal of Transportation Technologies》 2020年第2期169-181,共13页
The human factor is the most important cause of road accidents. Investigating the drivers’ mental patterns can lead to a better understanding of the factors that affect drivers to make a mistake and thus increase the... The human factor is the most important cause of road accidents. Investigating the drivers’ mental patterns can lead to a better understanding of the factors that affect drivers to make a mistake and thus increase the likelihood of an accident. In this study, mental patterns of drivers as a human characteristic are determined through a questionnaire survey. To do this, 166 participants (18 - 65 years) were asked to express their opinion on the possible effect of 25 factors on the occurrence of accidents. These factors were selected through the investigation of the accident database during the last three years in different areas of the case study. To analyze the data extracted from the survey, Q-methodology was used. The results of the factor analysis showed that there are 5 mental patterns among the participants. Based on the driver’s opinion, human factors and road conditions were the most and least influential accident-generating items, respectively. The most significant reason for accidents determined by drivers was human errors including 1) unauthorized overtaking, 2) unauthorized speed, 3) driver distractions (such as cell phone), and 4) driver physical disability (such as visual impairment). Moreover, the failure of the vehicle was mostly reported as another influential contributor to accidents. It is worth mentioning that the results of this study can be used to minimize accidents resulted from drivers’ behavioral errors by suggesting strategies for enhancing their performance through new manuals which is a step towards a safer road. 展开更多
关键词 Human factor driver MENTAL Pattern Q-METHODOLOGY factor Analysis QUESTIONNAIRE
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数据要素新动能对制造业高质量发展的影响研究 被引量:9
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作者 田时中 许玉久 范宇翔 《统计与信息论坛》 北大核心 2023年第8期55-66,共12页
研究数据要素新动能对制造业高质量发展的影响效应及作用机理,对于突破传统动力弱化所导致的发展约束,推进经济社会高质量发展具有重要现实意义。基于制造业高质量发展的“驱动力—压力—状态—影响—响应”(DPSIR)评价指标体系,对2008... 研究数据要素新动能对制造业高质量发展的影响效应及作用机理,对于突破传统动力弱化所导致的发展约束,推进经济社会高质量发展具有重要现实意义。基于制造业高质量发展的“驱动力—压力—状态—影响—响应”(DPSIR)评价指标体系,对2008—2019年中国31个省份的制造业高质量发展指数进行熵值处理,运用面板Tobit模型,检验数据要素新动能对制造业高质量发展的影响效应。结果显示:中国制造业高质量发展指数呈现“稳步提升”的发展趋势,子系统差异显著;制造业高质量发展指数呈现“东部地区>西部地区>中部地区”的分布格局,东部地区领先优势较为明显,地区差异呈现“先升后降”的演变趋势。数据要素对中国制造业高质量发展具有显著的促进作用,但区域异质性特征明显,西部地区数据要素新动能对制造业高质量发展具有显著的促进作用,而东部地区和中部地区的影响不显著。全国视角下的财政投入、城镇化发展、外商投资、电力消耗对制造业高质量发展具有正向作用,而工业化水平、技术市场规模、地区开放和科技改进的作用相反。分地区视角下,城镇化水平和电力消耗对东部、中部及西部地区的制造业高质量发展均有正向作用,工业化水平则对三大地区的制造业高质量发展均存在抑制效应,技术市场规模、企业信息化、外商投资、地区开放和科技改进对三大地区的影响皆不相同。最后,从数据要素的权属界定、要素流动、高效利用和安全保护等方面,围绕深化数据要素新动能对制造业高质量发展的促进效应提出相关政策建议。 展开更多
关键词 数据资源 数字经济 经济新动能 数据生产要素 制造业
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Standardized Evaluation of Camera-based Driver State Monitoring Systems
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作者 Renran Tian Keyu Ruan +3 位作者 Lingxi Li Jialiang Le Jeff Greenberg Saeed Barbat 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2019年第3期716-732,共17页
Driver state sensing technologies, such as vehicular systems, start to be widely considered by automotive manufacturers. To reduce the cost and minimize the intrusiveness towards driving, the majority of these systems... Driver state sensing technologies, such as vehicular systems, start to be widely considered by automotive manufacturers. To reduce the cost and minimize the intrusiveness towards driving, the majority of these systems rely on the in-cabin camera(s) and other optical sensors. With their great capabilities in detecting and intervening of driver distraction and inattention,these technologies may become key components in future vehicle safety and control systems. However, to the best of our knowledge,currently, there is no common standard available to objectively compare the performance of these technologies. Thus, it is imperative to develop one standardized process for evaluation purposes.In this paper, we propose one systematic and standardized evaluation process after successfully addressing three difficulties:1) defining and selecting the important influential individual and environmental factors, 2) countering the effects of individual differences and randomness in driver behaviors, and 3) building a reliable in-vehicle driver head motion tracking tool to collect ground-truth motion data. We have collected data on a large scale on a commercial driver state-sensing platform. For each subject, 30 to 40 minutes of head motion data was collected and included variables, such as lighting conditions, head/face features,and camera locations. The collected data was analyzed based on a proposed performance measure. The results show that the developed process can efficiently evaluate an individual camerabased driver state sensing product, which builds a common base for comparing the performance of different systems. 展开更多
关键词 DATA analysis DATA COLLECTION driver state sensing human factorS performance EVALUATION
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Flood Generation Mechanisms and Potential Drivers of Flood in Wabi-Shebele River Basin, Ethiopia
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作者 Fraol Abebe Wudineh Semu Ayalew Moges Belete Berhanu Kidanewold 《Natural Resources》 2022年第1期38-51,共14页
<span style="font-family:""><span style="font-family:Verdana;">Flood is a natural process generated by the interaction of various driving fac</span><span style="font-... <span style="font-family:""><span style="font-family:Verdana;">Flood is a natural process generated by the interaction of various driving fac</span><span style="font-family:Verdana;">tors. Flood peak flows, flood frequency at different return periods, and potential driving forces are analyzed in this study. The peak flow of six gauging stations, with a catchment area ranging from 169 -</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">124,108 km</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> and sufficient observed streamflow data, was selected to develop threshold (3</span><sup><span style="font-family:Verdana;">rd</span></sup><span style="font-family:Verdana;"> quartile) magnitude and frequency (POTF) that occurred over ten years of records. Sixteen Potential climatic, watershed and human driving factors of floods in the study area were identified and analyzed with GIS, Pearson’s correlation, and Principal Correlation Analysis (PCA) to select the most influential factors. Eight of them (MAR, DA, BE, VS, sand, forest AGR, PD) are identified as the most significant variables in the flood formation of the basin. Moreover, mean annual rainfall (MAR), drainage area (DA), and lack of forest cover are explored as the principal driving factors for flood peak discharge in Wabi-Shebele River Basin. Fi</span></span><span style="font-family:""><span style="font-family:Verdana;">nally, the study resulted in regression equations that helped plan and design different infrastructure works in the basin as ungauged catchment empirical</span><span><span style="font-family:Verdana;"> equations to compute Q</span><sub><span style="font-family:Verdana;">MPF</span></sub><span style="font-family:Verdana;">, Q</span><sub><span style="font-family:Verdana;">5</span></sub><span style="font-family:Verdana;">, Q</span><sub><span style="font-family:Verdana;">10</span></sub><span style="font-family:Verdana;">, Q</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;">, and Q</span><sub><span style="font-family:Verdana;">100</span></sub><span style="font-family:Verdana;"> using influential climate, watershed, and human driving factors. The results of these empirical equations are </span></span><span style="font-family:Verdana;">also statistically accepted with a high significance correlation (R</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> > 0.9). 展开更多
关键词 Flood drivers Climate factors Watershed Characteristics Human drivers Principal Correlation Analysis (PCA) Multiple Regression Model
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Factors and Pattern of Injuries Associated with Road Traffic Accidents in Hilly District of Nepal
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作者 Vijaya Laxmi Shrestha Dharma Nand Bhatta +2 位作者 Krishna Man Shrestha Krishna Bahadur GC Sudarshan Paudel 《Journal of Biosciences and Medicines》 2017年第12期88-100,共13页
Introduction: In 21st century, road traffic accidents (RTA) are considered as increasing epidemic of non-communicable disease which is abandoned and needs special attention to prevent them. The aim of this study was t... Introduction: In 21st century, road traffic accidents (RTA) are considered as increasing epidemic of non-communicable disease which is abandoned and needs special attention to prevent them. The aim of this study was to assess the factors and pattern of injuries associated with road traffic accidents. Methods: A cross sectional study was conducted among 112 RTA victims and 56 drivers in Palpa District of Nepal. The association of factors and pattern of injuries with exposure to accidents was assessed using Fisher’s exact test. Bivariate logistic regression examined the association between driving and socio-demographics factors and exposure to road accidents. Results: Of 112 RTA victims, 50% were in the age group of 21 to 40 years and 71.4% were male. Drivers who were in the age less than or equal to 30 years were more likely (OR: 3.6;95% CI: 1.0, 14.3) to expose to an accident than those who were above 30 years. Similarly, those having driving speed less than 40 km/hr were less likely to expose to an accident than those with speed 40 - 60 km/hr (OR: 6.0;95% CI: 0.8, 73.5) and those with speed more than 60 km/hr (OR 7.8;95% CI: 1.0, 100.1). Moreover, the driving experience was also found positively associated (OR: 5.6;95% CI: 1.1, 35.5) with the exposure to an accident. Conclusion: Being in younger age group, male gender, morning time, the driving speed, driving experiences, and driving hours on the road were positively associated with RTA. The efforts should be made to enforce laws in control of speed targeting experienced drivers and those with younger age groups. 展开更多
关键词 Road Traffic Accidents factorS PATTERN of INJURIES driver Prevention and AWARENESS
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面向不平衡数据集的SMOTENC-XGBoost驾驶人交通安全评估模型 被引量:5
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作者 王博文 王景升 吴恩重 《科学技术与工程》 北大核心 2023年第2期831-837,共7页
为深入挖掘驾驶人因素与交通事故之间的关系,提出了一种基于SMOTENC和极端梯度提升(extreme gradient boosting,XGBoost)的驾驶人交通状态优劣分类算法。首先针对交通事故发生与否不平衡的特点,使用SMOTENC算法对数据进行上采样并在采... 为深入挖掘驾驶人因素与交通事故之间的关系,提出了一种基于SMOTENC和极端梯度提升(extreme gradient boosting,XGBoost)的驾驶人交通状态优劣分类算法。首先针对交通事故发生与否不平衡的特点,使用SMOTENC算法对数据进行上采样并在采样过程中加入随机扰动,解决了数据不平衡问题。然后使用Embedded算法结合L1正则化,通过模型评估完成对特征子集的选择。最后使用机器学习的方法将XGBoost算法用于执行数据的特征提取和分类过程。实验表明,在对驾驶人的交通状态进行综合评价的任务上,XGBoost模型的准确率为99.85%,相较于随机森林、支持向量机等对照组模型,提升了1.12%~1.80%。除此之外,使用SMOTENC算法对数据不平衡问题进行处理后,通过混淆矩阵观察到模型对于好坏个体均具备较好的识别能力。 展开更多
关键词 交通安全 XGBoost SMOTENC 驾驶人因素 事故预防
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基于GAM的喀斯特植被覆盖与驱动因素非线性关系分析 被引量:2
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作者 黄琪 彭立 +2 位作者 李赛男 黄紫燕 邓伟 《中国环境科学》 EI CAS CSCD 北大核心 2023年第5期2489-2496,共8页
利用Theil-Sen斜率估计和Mann-Kendall显著性检验对2000~2018年西南五省的归一化植被指数(NDVI)进行研究,探究植被覆盖的时空变化特征.用MK(Mann-Kendall)突变检验寻找NDVI与夜间灯光数据的突变时间点.借助广义可加模型(GAM)对社会经济... 利用Theil-Sen斜率估计和Mann-Kendall显著性检验对2000~2018年西南五省的归一化植被指数(NDVI)进行研究,探究植被覆盖的时空变化特征.用MK(Mann-Kendall)突变检验寻找NDVI与夜间灯光数据的突变时间点.借助广义可加模型(GAM)对社会经济驱动因素,自然驱动因素分别拟合植被覆盖的响应曲线,探究喀斯特地区与非喀斯特地区的非线性响应关系的差异.结果表明:研究区中部、东部的植被恢复效果整体比西部地区好;利用夜间灯光数据作为表征城镇化的替代变量,城镇化与植被覆盖都在2009~2010年之间发生了突变,城镇化的突变时间早于植被覆盖的突变;喀斯特地区有88.54%的植被覆盖增加,其中有48.15%显著增加;非喀斯特地区有80.08%的植被覆盖增加,其中显著增加的占32.34%.喀斯特地区的植被恢复整体要比非喀斯特地区好.植被指数与国内生产总值(GDP)、路网密度、建成区面积等人类影响因素呈现不同的非线性响应关系.整体而言,非喀斯特地区受到的气温影响要比喀斯特地区的大,降雨、土层厚度对喀斯特地区植被恢复的影响更大一些.对比评价喀斯特与非喀斯特地区的植被恢复效果,分区探索植被覆盖变化背后驱动机制的非线性关系,对生态恢复规划等具有启示意义. 展开更多
关键词 喀斯特 植被指数 驱动因子 突变检验 非线性 广义可加模型(GAM)
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负密度制约假说的研究进展
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作者 周刚 乔秀娟 +1 位作者 徐耀粘 江明喜 《植物科学学报》 CAS CSCD 北大核心 2023年第6期759-767,共9页
负密度制约假说被认为是维持热带森林较高生物多样性的重要机制之一,其主要描述由于资源竞争和有害生物侵害,导致同种个体死亡率增加,从而为其他物种提供生存空间和资源,促进物种共存。通过介绍不同气候带影响负密度制约的驱动因子,以... 负密度制约假说被认为是维持热带森林较高生物多样性的重要机制之一,其主要描述由于资源竞争和有害生物侵害,导致同种个体死亡率增加,从而为其他物种提供生存空间和资源,促进物种共存。通过介绍不同气候带影响负密度制约的驱动因子,以及影响负密度制约强度的生物和非生物因子,本文阐述了最近十余年负密度制约相关研究的进展。其次,通过介绍负密度制约的纬度梯度格局及其存在的争议,讨论了负密度制约的理论意义。最后,利用文献计量学分析方法,探讨了负密度制约近年来的发展趋势以及今后的发展方向。 展开更多
关键词 文献计量分析 物种共存理论 驱动因子 纬度梯度 发展趋势
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