期刊文献+
共找到148,024篇文章
< 1 2 250 >
每页显示 20 50 100
985学子焦虑:优绩主义与社会结构下的精英困境
1
作者 朱丽丽 《中国图书评论》 2024年第5期16-28,共13页
从优绩主义理论视角出发,整体性地反思985学子焦虑现象的社会心理与深层机制。根据访谈对象的生命自述,深入剖析功绩主义理念下的自我规训与自我剥削、985高校内部的分层与流动、优绩主义承诺下的希望、努力与落空等各个层面。高校隐形... 从优绩主义理论视角出发,整体性地反思985学子焦虑现象的社会心理与深层机制。根据访谈对象的生命自述,深入剖析功绩主义理念下的自我规训与自我剥削、985高校内部的分层与流动、优绩主义承诺下的希望、努力与落空等各个层面。高校隐形的优绩主义新包装、多元而不多元化的评价体系、985标签的光环与负担、“上”与“下”的隐忧与动力、优绩主义的承诺与失效、普遍性社会结构与985学子焦虑的关联等诸多问题,揭示了985学子焦虑现象应该得到社会更多的关注与重视。我们希望通过深描,讲述优绩主义盛行时代中国精英学子的生命故事及其情感认知,并在“理解他人的理解”中观照写作者自身的生活世界,达到与自己、与他人、与社会、与历史、与世界的沟通与和解。 展开更多
关键词 优绩主义 985学子 焦虑 情感
下载PDF
人工智能背景下Materials Project数据库在计算材料学课程教学中的应用
2
作者 胡学敏 孙孪鸿 +1 位作者 陈晓玉 叶原丰 《科教文汇》 2024年第10期90-94,共5页
该文探讨了在人工智能背景下,Materials Project数据库在计算材料学课程教学中的应用和影响。Materials Project数据库是一个集成了AI和大数据技术的开放获取的材料库,能为学生提供海量的材料晶体结构和物性数据,使教学内容更为丰富,让... 该文探讨了在人工智能背景下,Materials Project数据库在计算材料学课程教学中的应用和影响。Materials Project数据库是一个集成了AI和大数据技术的开放获取的材料库,能为学生提供海量的材料晶体结构和物性数据,使教学内容更为丰富,让学生能通过亲自操作获取和分析数据,深入理解微观结构与物性之间的关系。这一新兴的教学模式不仅提升了学生的科研能力和创新思维能力,还有助于培养具备计算材料专业知识和多学科交叉的复合型人才。总体来说,人工智能时代下,大数据的引入为计算材料学课程带来新的活力,并对未来教育改革和实践产生了积极影响。 展开更多
关键词 人工智能 Materials project数据库 计算材料学教学
下载PDF
Transcriptional regulation in the development and dysfunction of neocortical projection neurons 被引量:1
3
作者 Ningxin Wang Rong Wan Ke Tang 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第2期246-254,共9页
Glutamatergic projection neurons generate sophisticated excitatory circuits to integrate and transmit information among different cortical areas,and between the neocortex and other regions of the brain and spinal cord... Glutamatergic projection neurons generate sophisticated excitatory circuits to integrate and transmit information among different cortical areas,and between the neocortex and other regions of the brain and spinal cord.Appropriate development of cortical projection neurons is regulated by certain essential events such as neural fate determination,proliferation,specification,differentiation,migration,survival,axonogenesis,and synaptogenesis.These processes are precisely regulated in a tempo-spatial manner by intrinsic factors,extrinsic signals,and neural activities.The generation of correct subtypes and precise connections of projection neurons is imperative not only to support the basic cortical functions(such as sensory information integration,motor coordination,and cognition)but also to prevent the onset and progression of neurodevelopmental disorders(such as intellectual disability,autism spectrum disorders,anxiety,and depression).This review mainly focuses on the recent progress of transcriptional regulations on the development and diversity of neocortical projection neurons and the clinical relevance of the failure of transcriptional modulations. 展开更多
关键词 autism spectrum disorders COGNITION DIFFERENTIATION excitatory circuits intellectual disability NEOCORTEX neurodevelopmental disorders projection neuron specification transcriptional regulation
下载PDF
Diagnosis of indirectly driven double shell targets with point-projection hard x-ray radiography
4
作者 Chao Tian Minghai Yu +17 位作者 Lianqiang Shan Fengjuan Wu Bi Bi Qiangqiang Zhang Yuchi Wu Tiankui Zhang Feng Zhang Dongxiao Liu Weiwu Wang Zongqiang Yuan Siqian Yang Lei Yang Zhigang Deng Jian Teng Weimin Zhou Zongqing Zhao Yuqiu Gu Baohan Zhang 《Matter and Radiation at Extremes》 SCIE EI CSCD 2024年第2期50-62,共13页
We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on t... We present an application of short-pulse laser-generated hard x rays for the diagnosis of indirectly driven double shell targets. Coneinserted double shell targets were imploded through an indirect drive approach on the upgraded SG-II laser facility. Then, based on thepoint-projection hard x-ray radiography technique, time-resolved radiography of the double shell targets, including that of their near-peakcompression, were obtained. The backlighter source was created by the interactions of a high-intensity short pulsed laser with a metalmicrowire target. Images of the target near peak compression were obtained with an Au microwire. In addition, radiation hydrodynamicsimulations were performed, and the target evolution obtained agrees well with the experimental results. Using the radiographic images, arealdensities of the targets were evaluated. 展开更多
关键词 double projectION POINT
下载PDF
Accelerated Primal-Dual Projection Neurodynamic Approach With Time Scaling for Linear and Set Constrained Convex Optimization Problems
5
作者 You Zhao Xing He +1 位作者 Mingliang Zhou Tingwen Huang 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2024年第6期1485-1498,共14页
The Nesterov accelerated dynamical approach serves as an essential tool for addressing convex optimization problems with accelerated convergence rates.Most previous studies in this field have primarily concentrated on... The Nesterov accelerated dynamical approach serves as an essential tool for addressing convex optimization problems with accelerated convergence rates.Most previous studies in this field have primarily concentrated on unconstrained smooth con-vex optimization problems.In this paper,on the basis of primal-dual dynamical approach,Nesterov accelerated dynamical approach,projection operator and directional gradient,we present two accelerated primal-dual projection neurodynamic approaches with time scaling to address convex optimization problems with smooth and nonsmooth objective functions subject to linear and set constraints,which consist of a second-order ODE(ordinary differential equation)or differential conclusion system for the primal variables and a first-order ODE for the dual vari-ables.By satisfying specific conditions for time scaling,we demonstrate that the proposed approaches have a faster conver-gence rate.This only requires assuming convexity of the objective function.We validate the effectiveness of our proposed two accel-erated primal-dual projection neurodynamic approaches through numerical experiments. 展开更多
关键词 Accelerated projection neurodynamic approach lin-ear and set constraints projection operators smooth and nonsmooth convex optimization time scaling.
下载PDF
焦虑:985学子的结构性情感与叙事疗愈
6
作者 张钟元 《中国图书评论》 2024年第5期42-55,共14页
每个社会都有其特定的客观结构和情感律动,但随着优绩主义原则占据主流,利益格局变得相对固化,通过教育向上流动的机会变得越发困难。近年来,高校学子的情感基调演变受到广泛关注。焦虑作为一种结构性情感产物,是时代变迁、社会资本、... 每个社会都有其特定的客观结构和情感律动,但随着优绩主义原则占据主流,利益格局变得相对固化,通过教育向上流动的机会变得越发困难。近年来,高校学子的情感基调演变受到广泛关注。焦虑作为一种结构性情感产物,是时代变迁、社会资本、社会时钟和教育机制等社会结构因素同时作用于985学子身上的显著体现,其根源正是对于结构性困境的无能感。本文从焦虑这一结构性情感产物入手,结合其在985学子中的具体呈现,分析这种结构性情感是如何形成和变化的,补充一个观察优绩社会的情感视角,在反思内卷时代的同时,厘清通过叙事能进行何种疗愈,并重建怎样的意义,将叙事纳入青年能动性策略之中,阐述叙事疗愈在这个时代中的重要作用。 展开更多
关键词 焦虑 结构性情感 叙事疗愈 985学子
下载PDF
Two Monte Carlo-based simulators for imaging-system modeling and projection simulation of flat-panel X-ray source
7
作者 Meng-Ke Qi Ting He +7 位作者 Yi-Wen Zhou Jing Kang Zeng-Xiang Pan Song Kang Wang-Jiang Wu Jun Chen Ling-Hong Zhou Yuan Xu 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2024年第7期31-46,共16页
The advantages of a flat-panel X-ray source(FPXS)make it a promising candidate for imaging applications.Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and res... The advantages of a flat-panel X-ray source(FPXS)make it a promising candidate for imaging applications.Accurate imaging-system modeling and projection simulation are critical for analyzing imaging performance and resolving overlapping projection issues in FPXS.The conventional analytical ray-tracing approach is limited by the number of patterns and is not applicable to FPXS-projection calculations.However,the computation time of Monte Carlo(MC)simulation is independent of the size of the patterned arrays in FPXS.This study proposes two high-efficiency MC projection simulators for FPXS:a graphics processing unit(GPU)-based phase-space sampling MC(gPSMC)simulator and GPU-based fluence sampling MC(gFSMC)simulator.The two simulators comprise three components:imaging-system modeling,photon initialization,and physical-interaction simulations in the phantom.Imaging-system modeling was performed by modeling the FPXS,imaging geometry,and detector.The gPSMC simulator samples the initial photons from the phase space,whereas the gFSMC simulator performs photon initialization from the calculated energy spectrum and fluence map.The entire process of photon interaction with the geometry and arrival at the detector was simulated in parallel using multiple GPU kernels,and projections based on the two simulators were calculated.The accuracies of the two simulators were evaluated by comparing them with the conventional analytical ray-tracing approach and acquired projections,and the efficiencies were evaluated by comparing the computation time.The results of simulated and realistic experiments illustrate the accuracy and efficiency of the proposed gPSMC and gFSMC simulators in the projection calculation of various phantoms. 展开更多
关键词 Flat-panel X-ray source(FPXS) Imaging-system modeling projection simulation Monte Carlo-based simulators
下载PDF
Agricultural Investment Project Decisions Based on an Interactive Preference Disaggregation Model Considering Inconsistency
8
作者 Xingli Wu Huchang Liao +1 位作者 Shuxian Sun Zhengjun Wan 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期3125-3146,共22页
Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionm... Agricultural investment project selection is a complex multi-criteria decision-making problem,as agricultural projects are easily influenced by various risk factors,and the evaluation information provided by decisionmakers usually involves uncertainty and inconsistency.Existing literature primarily employed direct preference elicitation methods to address such issues,necessitating a great cognitive effort on the part of decision-makers during evaluation,specifically,determining the weights of criteria.In this study,we propose an indirect preference elicitation method,known as a preference disaggregation method,to learn decision-maker preference models fromdecision examples.To enhance evaluation ease,decision-makers merely need to compare pairs of alternatives with which they are familiar,also known as reference alternatives.Probabilistic linguistic preference relations are employed to account for the presence of incomplete and uncertain information in such pairwise comparisons.To address the inconsistency among a group of decision-makers,we develop a pair of 0-1mixed integer programming models that consider both the semantics of linguistic terms and the belief degrees of decision-makers.Finally,we conduct a case study and comparative analysis.Results reveal the effectiveness of the proposed model in solving agricultural investment project selection problems with uncertain and inconsistent decision information. 展开更多
关键词 Multiple criteria analysis preference disaggregation INCONSISTENCY probability linguistic preference relation investment project selection
下载PDF
Spatial diversion and coordination of flood water for an urban flood control project in Suzhou, China
9
作者 Yu Xu You-peng Xu +2 位作者 Qiang Wang Yue-feng Wang Chao Gao 《Water Science and Engineering》 EI CAS CSCD 2024年第2期108-117,共10页
Suzhou City,located in the Yangtze River Delta in China,is prone to flooding due to a complex combination of natural factors,including its monsoon climate,low elevation,and tidally influenced position,as well as inten... Suzhou City,located in the Yangtze River Delta in China,is prone to flooding due to a complex combination of natural factors,including its monsoon climate,low elevation,and tidally influenced position,as well as intensive human activities.The Large Encirclement Flood Control Project(LEFCP)was launched to cope with serious floods in the urban area.This project changed the spatiotemporal pattern of flood processes and caused spatial diversion of floods from the urban area to the outskirts of the city.Therefore,this study developed a distributed flood simulation model in order to understand this transition of flood processes.The results revealed that the LEFCP effectively protected the urban areas from floods,but the present scheduling schemes resulted in the spatial diversion of floods to the outskirts of the city.With rainstorm frequencies of 10.0%to 0.5%,the water level differences between two representative water level stations(Miduqiao(MDQ)and Fengqiao(FQ))located inside and outside the LEFCP area,ranged from 0.75 m to 0.24 m and from 1.80 m to 1.58 m,respectively.In addition,the flood safety margin at MDQ and the duration with the water level exceeding the warning water level at FQ ranged from 0.95 m to 0.43 m and from 4 h to 22 h,respectively.Rational scheduling schemes for the hydraulic facilities of the LEFCP in extreme precipitation cases were developed ac-cording to food simulations under seven scheduling scenarios.This helps to regulate the spatial flood diversion caused by the LEFCP during extreme precipitation. 展开更多
关键词 Urban flooding Urban flood control project Rainstorm fregue ncy Flood simulation model Suzhou City
下载PDF
显与隐之间:985学子焦虑的传播机制与媒介调适策略——兼论数字青年与新媒介技术的复杂关系
10
作者 张帆 《中国图书评论》 2024年第5期29-41,共13页
深度媒介化社会,日益出现线上线下融合的数字交往形态,作为结构性力量的传播机制,参与社会情感结构的形塑。在985学子焦虑的生成与扩散中,社交媒体展演、媒介的社会氛围渲染和知识社会的信息问题共同发挥作用。985学子则在与媒介关系的... 深度媒介化社会,日益出现线上线下融合的数字交往形态,作为结构性力量的传播机制,参与社会情感结构的形塑。在985学子焦虑的生成与扩散中,社交媒体展演、媒介的社会氛围渲染和知识社会的信息问题共同发挥作用。985学子则在与媒介关系的调适中采用展演、断联与驯化的策略,意图缓释焦虑。985学子焦虑与传播机制双向互构,呈现出“显与隐之间”的矛盾特质。自我披露和自我隐藏的交织折射出数字青年与新媒介技术的复杂关系,反映社会与媒介关系的推进、调适与变革。将“附近”概念和“重建附近”的出路引入新媒介领域,会发现社交媒体已搭建一个融合“远方”和“附近”的第三空间,数字青年“重建附近”的出路可能被数字媒介技术介入后搭建的复杂媒介情境迷惑和抑制。 展开更多
关键词 985学子焦虑 媒介调适 数字青年 “重建附近”
下载PDF
Cascading multi-segment rupture process of the 2023 Turkish earthquake doublet on a complex fault system revealed by teleseismic P wave back projection method
11
作者 Bonan Cao Zengxi Ge 《Earthquake Science》 2024年第2期158-173,共16页
In this study,the vertical components of broadband teleseismic P wave data recorded by China Earthquake Network are used to image the rupture processes of the February 6th,2023 Turkish earthquake doublet via back proj... In this study,the vertical components of broadband teleseismic P wave data recorded by China Earthquake Network are used to image the rupture processes of the February 6th,2023 Turkish earthquake doublet via back projection analysis.Data in two frequency bands(0.5-2 Hz and 1-3 Hz)are used in the imaging processes.The results show that the rupture of the first event extends about 200 km to the northeast and about 150 km to the southwest,lasting~90 s in total.The southwestern rupture is triggered by the northeastern rupture,demonstrating a sequential bidirectional unilateral rupture pattern.The rupture of the second event extends approximately 80 km in both northeast and west directions,lasting~35 s in total and demonstrates a typical bilateral rupture feature.The cascading ruptures on both sides also reflect the occurrence of selective rupture behaviors on bifurcated faults.In addition,we observe super-shear ruptures on certain fault sections with relatively straight fault structures and sparse aftershocks. 展开更多
关键词 2023 Turkish earthquake doublet back projection method cascading segmented rupture process coseismic triggering super-shear ruptures
下载PDF
Economic significance and environmental impacts of the Song Dam Drinking Water Project(SDDWP)in Garhwal Himalaya
12
作者 Vishwambhar Prasad SATI 《Regional Sustainability》 2024年第2期140-152,共13页
With the population growth through natural growth and migration,coupled with the city expansion,it is the fact that Dehradun City in India faces severe water scarcity.Therefore,the Song Dam Drinking Water Project(SDDW... With the population growth through natural growth and migration,coupled with the city expansion,it is the fact that Dehradun City in India faces severe water scarcity.Therefore,the Song Dam Drinking Water Project(SDDWP)is proposed to provide ample drinking water to Dehradun City and its suburban areas.This paper examined economic significance and environmental impacts of the SDDWP in Garhwal Himalaya,India.To conduct this study,we collected data from both primary and secondary sources.There are 12 villages and 3 forest divisions in the surrounding areas of the proposed dam project,of which 3 villages will be fully submerged and 50 households will be affected.For this study,50 heads of the households were interviewed in the 3 submerged villages.The questions mainly focused on economic significance,environmental impacts,and rehabilitation issues of the dam project.The findings of this study indicate that economic significance of the dam project is substantial,including providing ample water for drinking and irrigation,contributing to groundwater recharge,creating job opportunities,and promoting the development of tourism and fisheries in the Doon Valley.In terms of the rehabilitation of the affected people,there are only 50 households in need of rehabilitation.Currently,the arable land of these affected people is not sufficient to sustain their livelihoods.The entire landscape is fragile,rugged,and precipitous;therefore,the affected people are willing to rehabilitate to more suitable areas in the Doon Valley.Moreover,it is essential to provide them with sufficient compensation packages including the compensation of arable land,houses,cash,common property resources,institutions,belongingness,and cultural adaptation.On the other hand,the proposed dam project will have adverse environmental impacts including arable land degradation,forest degradation,loss of fauna and flora,soil erosion,landslides,and soil siltation.These impacts will lead to the ecological imbalances in both upstream and downstream areas.This study suggests that the affected people should be given sufficient compensation packages in all respects.Afforestation programs can be launched in the degraded areas to compensate for the loss of forest in the affected areas. 展开更多
关键词 Water scarcity Rehabilitation issues Song Dam Drinking Water project(SDDWP) Dehradun City Song River BASIN
下载PDF
基于Microsoft Project的建筑施工项目管理分析
13
作者 杨盛华 《中国厨卫》 2024年第7期82-84,共3页
在当前社会经济快速发展的情况下,建设工程数量不断增加,而传统的手工记录方式已经无法满足现代建设工程的需求。因此,采用先进的计算机技术来辅助建筑施工项目管理已成为当今建筑业发展的趋势。Microsoft Project作为一种专业的项目管... 在当前社会经济快速发展的情况下,建设工程数量不断增加,而传统的手工记录方式已经无法满足现代建设工程的需求。因此,采用先进的计算机技术来辅助建筑施工项目管理已成为当今建筑业发展的趋势。Microsoft Project作为一种专业的项目管理软件,具有良好的数据存储和可视化展示功能,可以有效地提高建筑施工项目的质量和效率。文章分析了如何利用Microsoft Project软件进行建筑施工项目管理,并对该方法的应用效果进行评估,以期为今后的建筑施工项目管理提供参考价值。 展开更多
关键词 Microsoft project 建筑施工 项目管理
下载PDF
How do lateral septum projections to the ventral CA1 influence sociability?
14
作者 Dan Wang Di Zhao +12 位作者 Wentao Wang Fengai Hu Minghu Cui Jing Liu Fantao Meng Cuilan Liu Changyun Qiu Dunjiang Liu Zhicheng Xu Yameng Wang Yu Zhang Wei Li Chen Li 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第8期1789-1801,共13页
Social dysfunction is a risk factor for several neuropsychiatric illnesses.Previous studies have shown that the lateral septum(LS)-related pathway plays a critical role in mediating social behaviors.Howeve r,the role ... Social dysfunction is a risk factor for several neuropsychiatric illnesses.Previous studies have shown that the lateral septum(LS)-related pathway plays a critical role in mediating social behaviors.Howeve r,the role of the connections between the LS and its downstream brain regions in social behavio rs remains unclea r.In this study,we conducted a three-chamber test using electrophysiological and chemogenetic approaches in mice to determine how LS projections to ventral CA1(vCA1)influence sociability.Our res ults showed that gamma-aminobutyric acid(GABA)-e rgic neuro ns were activated following social experience,and that social behavio rs were enhanced by chemogenetic modulation of these neurons.Moreover,LS GABAergic neurons extended their functional neural connections via vCA1 glutamatergic pyramidal neurons,and regulating LSGABA→vCA1Gluneural projections affected social behaviors,which were impeded by suppressing LSprojecting vCA1 neuronal activity or inhibiting GABAAreceptors in vCA1.These findings support the hypothesis that LS inputs to the vCA1 can control social prefe rences and social novelty behaviors.These findings provide new insights rega rding the neural circuits that regulate sociability. 展开更多
关键词 chemogenetics GABA receptor GABAergic neurons glutamatergic neurons lateral septum neural excitability neural projection social novelty social preference ventral CA1
下载PDF
Spatial Variation and Trend of Extreme Precipitation in Africa during 1981-2019 and Its Projected Changes at the End of 21st Century
15
作者 Fabien Habiyakare Tong Jiang +3 位作者 Ibrahim Yahaya Daudi Ndabagenga James Kagabo Buda Su 《Journal of Geoscience and Environment Protection》 2024年第3期192-221,共30页
This study comprehensively examines the patterns and regional variation of severe rainfall across the African continent, employing a suite of eight extreme precipitation indices. The analysis extends to the assessment... This study comprehensively examines the patterns and regional variation of severe rainfall across the African continent, employing a suite of eight extreme precipitation indices. The analysis extends to the assessment of projected changes in precipitation extremes using five General Circulation Models (GCMs) from Coupled Model Intercomparison Project Phase 6 (CMIP6) under four Shared Socioeconomic Pathways (SSPs) scenarios at the long-term period (2081-2100) of the 21<sup>st</sup> century. Furthermore, the study investigates potential mechanisms influencing precipitation extremes by correlating extreme precipitation indices with oceanic system indices, specifically Ni?o 3.4 for El Ni?o-Southern Oscillation (ENSO) and Dipole Mode Index (DMI) for the Indian Ocean Dipole (IOD). The findings revealed distinct spatial distributions in mean trends of extreme precipitation indices, indicating a tendency toward decreased extreme precipitation in North Africa, Sahel region, Central Africa and the Western part of South Africa. Conversely, West Africa, East Africa and the Eastern part of South Africa exhibit an inclination toward increased extreme precipitation. The changes in precipitation extreme indices indicate a general rise in both the severity and occurrence of extreme precipitation events under all scenarios by the end of the 21<sup>st</sup> century. Notably, our analysis projects a decrease in consecutive wet days (CWD) in the far-future. Additionally, correlation analysis highlights significant correlation between above or below threshold rainfall fluctuation in East Africa and South Africa with oceanic systems, particularly ENSO and the IOD. Central Africa abnormal precipitation variability is also linked to ENSO with a significant negative correlation. These insights contribute valuable information for understanding and projecting the dynamics of precipitation extreme in Africa, providing a foundation for climate adaptation and mitigation efforts in the region. 展开更多
关键词 Extreme Precipitation Mann-Kendall Trend projections Oceanic System AFRICA
下载PDF
Contractor-Related Factors and Performance of Bridge Construction Projects Implemented by Kenya National Highways Authority (KeNHA) Kenya
16
作者 Joan Anyika Otike Charles Kabubo Victoria Okumu 《Open Journal of Civil Engineering》 2024年第2期214-224,共11页
The performance of bridge projects in Kenya is poor in terms of completion by schedule, cost, and quality (scope). Yet, there is less evidence of empirical research on what factors contribute to this outcome. This stu... The performance of bridge projects in Kenya is poor in terms of completion by schedule, cost, and quality (scope). Yet, there is less evidence of empirical research on what factors contribute to this outcome. This study aimed to bridge this gap by examining the effects of contractor-related factors on the performance of bridge construction projects in Kenya through a case study of the Bridge projects Implemented by the Kenya National Highway Agency (KeNHA). The theory of constraints (TOC) was adopted as its theoretical framework. Descriptive research was used, and the target population was 18 bridge construction projects, which were the units of analysis from 2012 to 2022. In each of these projects, 18 respondents, namely clients, consultants, contractors, engineers, environment and social guards, project managers, stakeholders, subcontractors, technical advisors, and inspectors, were included in a target population of 144 respondents. A census was conducted and a structured questionnaire was administered from which a response rate of 68% was achieved. The information was analyzed using descriptive, correlation, and multiple linear regression analysis. The contractor-related factors considered in the study were staff and management factors. The findings indicated that staff and management factors had a positive and significant outcome on performance of bridge construction projects. The study recommends continuous training and a safe learning environment for staff to improve their skills and performance in future projects. The study also recommends that a special category for bridge contractors be created in Kenya’s National Construction Authority rankings to ensure that only qualified contractors implement the Bridge projects. 展开更多
关键词 Staff Factors Management Factors Performance Bridge projects KeNHA
下载PDF
Computational Quantification of Map Projection Distortion by Fractal Dimension of Coastlines
17
作者 Franklin Lee 《Journal of Applied Mathematics and Physics》 2024年第5期1890-1903,共14页
Maps, essential tools for portraying the Earth’s surface, inherently introduce distortions to geographical features. While various quantification methods exist for assessing these distortions, they often fall short w... Maps, essential tools for portraying the Earth’s surface, inherently introduce distortions to geographical features. While various quantification methods exist for assessing these distortions, they often fall short when evaluating actual geographic features. In our study, we took a novel approach by analyzing map projection distortion from a geometric perspective. We computed the fractal dimensions of different stretches of coastline before and after projection using the divide-and-conquer algorithm and image processing. Our findings revealed that map projections, even when preserving basic shapes, inevitably stretch and compress coastlines in diverse directions. This analysis method provides a more realistic and practical way to measure map-induced distortions, with significant implications for cartography, geographic information systems (GIS), and geomorphology. By bridging the gap between theoretical analysis and real-world features, this method greatly enhances accuracy and practicality when evaluating map projections. 展开更多
关键词 Map projection Distortion COASTLINE Fractal Dimension CARTOGRAPHY Geographic Information Systems
下载PDF
Multi-Criteria Wildfire Risk Hazard Assessment in GIS Environment: Projection for the Future and Impact on RES Projects Installation Planning
18
作者 Aggelos Pallikarakis Flora Konstantopoulou 《Journal of Geoscience and Environment Protection》 2024年第5期242-265,共24页
It is alarming for the fact that Wildfires number, severity and consequently impact have significantly increased during the last years, an aftermath of the Climate Change. One of the most affected areas worldwide is M... It is alarming for the fact that Wildfires number, severity and consequently impact have significantly increased during the last years, an aftermath of the Climate Change. One of the most affected areas worldwide is Mediterranean, due to the unique combination of its type of vegetation and demanding climatic conditions. This research is focused on the Region of Epirus in Greece, an area with significant natural vegetation and a range of geomorphological aspects. In order to estimate the Wildfire Risk Hazard, several factors have been used: geomorphological (slope, aspect, elevation, TWI, Hydrographic network), social (Settlements and landfils, roads, overhead lines and substations), environmental (land cover) and climatic (Fire Weather Index). Through a multi-criteria decision analysis (MCDA) and an analytic hierarchy process (AHP) in a GIS environment, the Wildfire Risk Hazard has been estimated not only for current conditions but also for future projections for the near future (2031-2060) and the far future (2071-2100). The selected case study includes the potential impact of the Wildfires to the installed (or targeted to be installed) RES projects in the studied region. 展开更多
关键词 RES projects Greece Epirus Analytic Hierarchy Process Multi-Criteria Decision Analysis
下载PDF
Hydrologic Response to Future Climate Change in the Dulong-Irra-waddy River Basin Based on Coupled Model Intercomparison Project 6
19
作者 XU Ziyue MA Kai +1 位作者 YUAN Xu HE Daming 《Chinese Geographical Science》 SCIE CSCD 2024年第2期294-310,共17页
Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role... Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role as both a valuable hydro-power resource and an essential ecological passageway.However,the water resources and security exhibit a high degree of vulnerabil-ity to climate change impacts.This research evaluates climate impacts on the hydrology of the Dulong-Irrawaddy River Basin(DIRB)by using a physical-based hydrologic model.We crafted future climate scenarios using the three latest global climate models(GCMs)from Coupled Model Intercomparison Project 6(CMIP6)under two shared socioeconomic pathways(SSP2-4.5 and SSP5-8.5)for the near(2025-2049),mid(2050-2074),and far future(2075-2099).The regional model using MIKE SHE based on historical hydrologic processes was developed to further project future streamflow,demonstrating reliable performance in streamflow simulations with a val-idation Nash-Sutcliffe Efficiency(NSE)of 0.72.Results showed that climate change projections showed increases in the annual precip-itation and potential evapotranspiration(PET),with precipitation increasing by 11.3%and 26.1%,and PET increasing by 3.2%and 4.9%,respectively,by the end of the century under SSP2-4.5 and SSP5-8.5.These changes are projected to result in increased annual streamflow at all stations,notably at the basin’s outlet(Pyay station)compared to the baseline period(with an increase of 16.1%and 37.0%at the end of the 21st century under SSP2-4.5 and SSP5-8.5,respectively).Seasonal analysis for Pyay station forecasts an in-crease in dry-season streamflow by 31.3%-48.9%and 22.5%-76.3%under SSP2-4.5 and SSP5-8.5,respectively,and an increase in wet-season streamflow by 5.8%-12.6%and 2.8%-33.3%,respectively.Moreover,the magnitude and frequency of flood events are pre-dicted to escalate,potentially impacting hydropower production and food security significantly.This research outlines the hydrological response to future climate change during the 21st century and offers a scientific basis for the water resource management strategies by decision-makers. 展开更多
关键词 climate change hydrologic response Coupled Model Intercomparison project 6(CMIP6) MIKE SHE(Système Hydrologique Europeén) Dulong-Irrawaddy River Basin
下载PDF
Projected Changes in the Climate Zoning of Côte d’Ivoire
20
作者 Mamadou Diarrassouba Adama Diawara +6 位作者 Assi Louis Martial Yapo Benjamin Komenan Kouassi Fidèle Yoroba Kouakou Kouadio Dro Touré Tiemoko Dianikoura Ibrahim Koné Arona Diedhiou 《Atmospheric and Climate Sciences》 2024年第1期62-84,共23页
This study assesses the projected changes in the climate zoning of Côte d’Ivoire using the hierarchical classification of principal components (HCPC) method applied to the daily precipitation data of an ensemble... This study assesses the projected changes in the climate zoning of Côte d’Ivoire using the hierarchical classification of principal components (HCPC) method applied to the daily precipitation data of an ensemble of 14 CORDEX-AFRICA simulations under RCP4.5 and RCP8.5 scenarios. The results indicate the existence of three climate zones in Côte d’Ivoire (the coastal, the centre and the north) over the historical period (1981-2005). Moreover, CORDEX simulations project an extension of the surface area of drier climatic zones while a reduction of wetter zones, associated with the appearance of an intermediate climate zone with surface area varying from 77,560 km<sup>2</sup> to 134,960 km<sup>2</sup> depending on the period and the scenario. These results highlight the potential impacts of climate change on the delimitation of the climate zones of Côte d’Ivoire under the greenhouse gas emission scenarios. Thus, there is a reduction in the surface areas suitable for the production of cash crops such as cocoa and coffee. This could hinder the country’s economy and development, mainly based on these cash crops. 展开更多
关键词 Climate projection Climate Zone Principal Component Analysis Hierarchical Classification on Principal Components CORDEX Côte d’Ivoire
下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部