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The relationship between compartment models and their stochastic counterparts:A comparative study with examples of the COVID-19 epidemic modeling 被引量:1
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作者 Ziyu Zhao Yi Zhou +6 位作者 Jinxing Guan Yan Yan Jing Zhao Zhihang Peng Feng Chen Yang Zhao Fang Shao 《Journal of Biomedical Research》 CAS CSCD 2024年第2期175-188,I0016-I0018,共17页
Deterministic compartment models(CMs)and stochastic models,including stochastic CMs and agent-based models,are widely utilized in epidemic modeling.However,the relationship between CMs and their corresponding stochast... Deterministic compartment models(CMs)and stochastic models,including stochastic CMs and agent-based models,are widely utilized in epidemic modeling.However,the relationship between CMs and their corresponding stochastic models is not well understood.The present study aimed to address this gap by conducting a comparative study using the susceptible,exposed,infectious,and recovered(SEIR)model and its extended CMs from the coronavirus disease 2019 modeling literature.We demonstrated the equivalence of the numerical solution of CMs using the Euler scheme and their stochastic counterparts through theoretical analysis and simulations.Based on this equivalence,we proposed an efficient model calibration method that could replicate the exact solution of CMs in the corresponding stochastic models through parameter adjustment.The advancement in calibration techniques enhanced the accuracy of stochastic modeling in capturing the dynamics of epidemics.However,it should be noted that discrete-time stochastic models cannot perfectly reproduce the exact solution of continuous-time CMs.Additionally,we proposed a new stochastic compartment and agent mixed model as an alternative to agent-based models for large-scale population simulations with a limited number of agents.This model offered a balance between computational efficiency and accuracy.The results of this research contributed to the comparison and unification of deterministic CMs and stochastic models in epidemic modeling.Furthermore,the results had implications for the development of hybrid models that integrated the strengths of both frameworks.Overall,the present study has provided valuable epidemic modeling techniques and their practical applications for understanding and controlling the spread of infectious diseases. 展开更多
关键词 compartment models agent-based models compartment-agent mixed models comparative study COVID-19
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Comparative Study of the Reliability and Complexity of Symmetrical and Asymmetrical Cryptosystems for the Protection of Academic Data in the Democratic Republic of Congo
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作者 Mugaruka Buduge Gulain Jeremie Ndikumagenge +2 位作者 Buhendwa Nyenyezi Justin Bulonza Masumbuko Alexis Katho Seba Jacques 《Journal of Information Security》 2024年第3期299-307,共9页
In the digital age, the data exchanged within a company is a wealth of knowledge. The survival, growth and influence of a company in the short, medium and long term depend on it. Indeed, it is the lifeblood of any mod... In the digital age, the data exchanged within a company is a wealth of knowledge. The survival, growth and influence of a company in the short, medium and long term depend on it. Indeed, it is the lifeblood of any modern company. A companys operational and historical data contains strategic and operational knowledge of ever-increasing added value. The emergence of a new paradigm: big data. Today, the value of the data scattered throughout this mother of knowledge is calculated in billions of dollars, depending on its size, scope and area of intervention. With the rise of computer networks and distributed systems, the threats to these sensitive resources have steadily increased, jeopardizing the existence of the company itself by drying up production and losing the interest of customers and suppliers. These threats range from sabotage to bankruptcy. For several decades now, most companies have been using encryption algorithms to protect and secure their information systems against the threats and dangers posed by the inherent vulnerabilities of their infrastructure and the current economic climate. This vulnerability requires companies to make the right choice of algorithms to implement in their management systems. For this reason, the present work aims to carry out a comparative study of the reliability and effectiveness of symmetrical and asymmetrical cryptosystems, in order to identify one or more suitable for securing academic data in the DRC. The analysis of the robustness of commonly used symmetric and asymmetric cryptosystems will be the subject of simulations in this article. 展开更多
关键词 comparative study CRYPTOSYSTEMS Symmetric Encryption asymmetric Encryption
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Quantitative Comparative Study of the Performance of Lossless Compression Methods Based on a Text Data Model
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作者 Namogo Silué Sié Ouattara +1 位作者 Mouhamadou Dosso Alain Clément 《Open Journal of Applied Sciences》 2024年第7期1944-1962,共19页
Data compression plays a key role in optimizing the use of memory storage space and also reducing latency in data transmission. In this paper, we are interested in lossless compression techniques because their perform... Data compression plays a key role in optimizing the use of memory storage space and also reducing latency in data transmission. In this paper, we are interested in lossless compression techniques because their performance is exploited with lossy compression techniques for images and videos generally using a mixed approach. To achieve our intended objective, which is to study the performance of lossless compression methods, we first carried out a literature review, a summary of which enabled us to select the most relevant, namely the following: arithmetic coding, LZW, Tunstall’s algorithm, RLE, BWT, Huffman coding and Shannon-Fano. Secondly, we designed a purposive text dataset with a repeating pattern in order to test the behavior and effectiveness of the selected compression techniques. Thirdly, we designed the compression algorithms and developed the programs (scripts) in Matlab in order to test their performance. Finally, following the tests conducted on relevant data that we constructed according to a deliberate model, the results show that these methods presented in order of performance are very satisfactory:- LZW- Arithmetic coding- Tunstall algorithm- BWT + RLELikewise, it appears that on the one hand, the performance of certain techniques relative to others is strongly linked to the sequencing and/or recurrence of symbols that make up the message, and on the other hand, to the cumulative time of encoding and decoding. 展开更多
关键词 arithmetic Coding BWT Compression Ratio comparative study Compression Techniques Shannon-Fano HUFFMaN Lossless Compression LZW PERFORMaNCE REDUNDaNCY RLE Text Data Tunstall
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Comparative Analysis of the Evolution of Community Space in Chengdu-Chongqing Region: A Case Study of Main Urban Areas in Chengdu and Chongqing
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作者 GAO Wei XIAO Yue +12 位作者 HE Yi GUO Zhenni LENG Qinyi LIU Hong KANG Yichen WANG Zhiye ZHU Zeliang WANG Jiamin ZHOU Xu CHAO Yi DONG Hailong MAO Xiao WANG Chensu 《Journal of Landscape Research》 2017年第5期22-26,共5页
Due to the integrated development between Chengdu and Chongqing,there are a large number of residents flowing into the two cities from their surrounding areas,so community renewal is imminent.Because of the similarity... Due to the integrated development between Chengdu and Chongqing,there are a large number of residents flowing into the two cities from their surrounding areas,so community renewal is imminent.Because of the similarity in the historical and cultural background of the two places,a comparative analysis of the evolution of community space in Chengdu-Chongqing Region enables Chengdu and Chongqing learn from each other and speed up the pace of renewal.This paper analyzed the evolution of community space in main urban areas of Chengdu and Chongqing.Specifically,the evolution of community space in Chengdu and Chongqing went through three stages.The starting time of community renewal in the two places was very close,but the duration of each stage varied.The second stage of Chengdu continued for a longer time,so its renovation and renewal of the community space was more detailed and thorough,and the emphasis and extension direction of the evolution of the community space were different.The evolution of community space in both Chengdu and Chongqing went through"mechanical renewal of demolition and construction—small-scale gradual renewal",but the path of renewal and development of the community space in Chengdu was faster.This paper,from the perspective of the evolution of community space,put forward the framework and content of community renewal in Chengdu and Chongqing based on community development and elaborated the community research content based on community development. 展开更多
关键词 Chengdu-Chongqing region Community space Integrated development comparative analysis
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Study and Identification of Gaultheria yunnanensis Leaves from Different Regions 被引量:1
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作者 刘绍欢 梁光平 +1 位作者 漆珍珍 王世清 《Agricultural Science & Technology》 CAS 2011年第7期958-962,共5页
[Objective] In order to identify and comparatively study leaves of ethnic medicine Gaultheria yunnanensis from different regions of Guizhou.[Method] Characteristics,microscopic,physical and chemical identification wer... [Objective] In order to identify and comparatively study leaves of ethnic medicine Gaultheria yunnanensis from different regions of Guizhou.[Method] Characteristics,microscopic,physical and chemical identification were studied on Gaultheria yunnanensis.[Result] There was no obvious difference in characteristics and microscopic sections among Gaultheria yunnanensis leaves from different regions.Blue fluorescence spots were observed clearly by TLC(Thin Layer Chromatography) test.[Conclusion]The study provided a basis for improvement of the quality standard of the Gaultheria yunnanensis. 展开更多
关键词 Gaultheria yunnanensis comparative study Varieties identification
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The Comparative Study between Metonymy and Metaphor within Cognitive Linguistics
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作者 黄林慧 《海外英语》 2014年第21期231-232,共2页
Both metonymy and metaphor are very important in our cognitive activities, but there are some distinctions and common grounds between them. This paper mainly deals with in what way they distinct in some aspects, while... Both metonymy and metaphor are very important in our cognitive activities, but there are some distinctions and common grounds between them. This paper mainly deals with in what way they distinct in some aspects, while how they are related to each other in other aspects. 展开更多
关键词 METONYMY METaPHOR comparative study
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Comparative Study on the Development Levels of Cold Chain Logistics for Agricultural Products between China and Developed Countries Based on Analytic Hierarchy Process 被引量:4
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作者 周兴建 《Agricultural Science & Technology》 CAS 2012年第5期1110-1114,共5页
By introducing the analytic hierarchy process (AHP), a model is constructed to compare the logistics development level of cold chain for agricultural products between China and other developed countries such as Unit... By introducing the analytic hierarchy process (AHP), a model is constructed to compare the logistics development level of cold chain for agricultural products between China and other developed countries such as United States, Japan and Euro- pean. The paper makes a comparative study on the development levels of agricultural cold chain logistics in China and developed countries from the aspects of the level of cold chain logistics facilities and equipments, the degree of cold chain logistics market-oriented and the capacity of cold chain logistics, then determines the problems of cold chain logistics in China. With the experiences learning from developed countries, some countermeasures are proposed to resolve those problems of cold chain logistics for agricultural products development combining with the national conditions in China. 展开更多
关键词 analytic hierarchy process agricultural products Cold chain logistics comparative study
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The Comparative Study of the Structure of the Chinese and English Simile 被引量:1
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作者 李晓惠 李芳芳 《Sino-US English Teaching》 2006年第4期62-67,共6页
Simile, as a kind of commonly used rhetoric, plays a vital role in people's daily life. The appropriate using of simile can make language much more refine, veracious, and lifelike, can vividly present the person, the... Simile, as a kind of commonly used rhetoric, plays a vital role in people's daily life. The appropriate using of simile can make language much more refine, veracious, and lifelike, can vividly present the person, the thing, the scene and so on to achieve better effects. Simile makes the finishing point in Chinese and English. However, because of the differences on culture, history, geography, customs, expressing ways and so on, there are some structural differences between Chinese and English simile. This paper will carry out the comparative study on the structure of Chinese and English simile. 展开更多
关键词 SIMILE STRUCTURE comparative study
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A Comparative Study on the Tense-Aspect of Auxiliary in English and Chinese
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作者 吴昊兰 《海外英语》 2010年第6X期268-269,271,共3页
The aim of the paper is to give a general comparison about the structural composition of the AUX in English and Chinese mainly from the perspective of tense-aspect.Based on the basic construction of English AUX system... The aim of the paper is to give a general comparison about the structural composition of the AUX in English and Chinese mainly from the perspective of tense-aspect.Based on the basic construction of English AUX system,which includes such elements as Tense,Modal,Perfect aspect,Progressive aspect and Passive,the paper focuses on comparing the syntactic characteristics of tense element in the two languages.The final part of the paper briefly summarized predicted learning problems that Chinese learners of English as well as English learners of Chinese would have in learning English and Chinese respectively. 展开更多
关键词 comparative study aUX TENSE English Chinese problems
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Exploring Nominalization in English Abstracts of Applied Linguistics Research Articles:A Comparative Study Between Chinese and International Journals
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作者 Gong Yingrui Zhao Yibu 《Contemporary Social Sciences》 2024年第4期122-142,共21页
Researchers around the world strive to communicate new knowledge,primarily via publication,with the abstract being crucial in conveying core insights.Previous research has generally analyzed the discourse features of ... Researchers around the world strive to communicate new knowledge,primarily via publication,with the abstract being crucial in conveying core insights.Previous research has generally analyzed the discourse features of abstracts from a macro perspective and often employed either outdated texts,such as those over a decade old,or papers written by authors with lower English academic writing proficiency as research material.In this study,we analyzed forty abstracts from leading journals in applied linguistics,evenly split between Chinese and international journals.It revealed that the use of nominalization in abstracts by Chinese and international scholars showed similarities due to the universal academic requirement for conciseness.However,due to cultural and educational differences,each group differed in their respective language choices and nominalization usage.By analyzing the application of nominalization in different cultural contexts,the results of our study offered practical suggestions for crafting abstracts that effectively convey information,thereby,contributing to the broader academic community. 展开更多
关键词 NOMINaLIZaTION aBSTRaCTS comparative study applied linguistics
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Specialization and Coordination: New Paradigm, Theory, and Path for Regional Development
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作者 Lu Ming Xiang Kuanhu +2 位作者 Li Pengfei Li Jiewei Zhong Yuejun 《China Economist》 2024年第1期76-85,共10页
In its new development stage,China seeks to derive new dynamism from reform and opening up at a higher level to boost consumption and services.This process coincides with a further differentiation of comparative advan... In its new development stage,China seeks to derive new dynamism from reform and opening up at a higher level to boost consumption and services.This process coincides with a further differentiation of comparative advantages across regions.Economic activity and population will continue to concentrate in clusters in coastal and central cities amid a continuous outflow of population from remote areas.Development expansion from coastal to interior regions and from central cities to the periphery will promote a new regional development paradigm of“dual centers and periphery”.Therefore,China’s regional development strategy should follow the new theory of seeking relative equilibrium amid development,identify regions of population inflow and outflow,and explore a new development path of regional specialization and coordination.By deepening market reforms and increasing central government coordination,the country is poised to improve the spatial allocation of resources and unleash institutional dividends in the process of developing a unified national market. 展开更多
关键词 regional development “dual centers-periphery” comparative advantage population migration
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A Comparative Study on Factors Influencing Food Security in China and India
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作者 Shaowen YANG Meixue QIU 《Asian Agricultural Research》 2024年第2期12-15,共4页
This paper analyzes and compares the key factors influencing food security in two populous countries(China and India),and cate-gorizes them into three types:agricultural production,economic development and income leve... This paper analyzes and compares the key factors influencing food security in two populous countries(China and India),and cate-gorizes them into three types:agricultural production,economic development and income level,and income distribution.Using the prevalence of undernourishment as an indicator of food security,the paper empirically tests the degree of impact of various factors on food security in both countries using Tobit regression and Newey regression methods.The study finds that improving the level of economic development can significantly enhance food security in both countriesꎻreducing the Gini coefficient has a significant impact on India,but not on Chinaꎻincreasing the agricultural production per capita has a much greater effect on China than on India.Therefore,both countries should take measures that are both similar and different according to their national conditions to improve their food security level. 展开更多
关键词 Food security Influencing factors comparative study Econometric model
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Comparative study of HFACS and the 24Model accident causation models 被引量:7
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作者 Gui Fu Jia-Lin Cao +1 位作者 Lin Zhou Yuan-Chi Xiang 《Petroleum Science》 SCIE CAS CSCD 2017年第3期570-578,共9页
A comparative study is conducted to compare the theory and application effect of two accident causation models, the human factors analysis and classification system(HFACS) and the accident causation "2-4" model(2... A comparative study is conducted to compare the theory and application effect of two accident causation models, the human factors analysis and classification system(HFACS) and the accident causation "2-4" model(24 Model), as well as to provide a reference for safety researchers and accident investigators to select an appropriate accident analysis method. The two models are compared in terms of their theoretical foundations, cause classifications, accident analysis processes, application ranges, and accident prevention strategies. A coal and gas outburst accident is then analyzed using both models, and the application results are compared. This study shows that both the 24 Model and HFACS have strong theoretical foundations, and they can each be applied in various domains. In addition, the cause classification in HFACS is more practical, and its accident analysis process is more convenient. On the other hand, the 24 Model includes external factors, which makes the cause analysis more systematic and comprehensive. Moreover, the 24 Model puts forward more corresponding measures to prevent accidents. 展开更多
关键词 HFaCS accident causation "2-4" model comparative study Unsafe acts External causes Coaland gas outburst accident
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Study on Regional Culture Inheritance in the Construction of Modern City Parks: A Case Study of Fule Mountain Park in Mianyang City, Sichuan Province 被引量:3
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作者 ZHAO Chunrong FU Juanlin ZHOU Bo 《Journal of Landscape Research》 2013年第5期48-50,共3页
City park, as an everlasting cultural carrier, is an important place for the expression of regional culture. The concept and characteristics of regional culture are summarized, and regional culture inheritance carrier... City park, as an everlasting cultural carrier, is an important place for the expression of regional culture. The concept and characteristics of regional culture are summarized, and regional culture inheritance carrier mainly includes land, garden style, garden building, etc. There are generally six methods: reservation, restoration, inheritance and development, extraction, reappearance, and creation. Taking Fule mountain Park in Mianyang City for example, combination of regional culture and landscape is analyzed. 展开更多
关键词 CITY PaRK regionaL CULTURE INHERITaNCE Case study
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A comparative study of the main factors controlling geohazards induced by 10 strong earthquakes in Western China since the Wenchuan earthquake in 2008 被引量:5
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作者 Chao Peng Zhi-qiang Yin +2 位作者 Xu-jiao Zhang Hai Shao Ming-fei Pang 《China Geology》 CAS CSCD 2023年第1期70-84,共15页
Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geolog... Determining the main controlling factors of earthquake-triggered geohazards is a prerequisite for studying earthquake geohazards and post-disaster emergency response.By studying these factors,the geomorphic and geological factors controlling the nature,condition,and distribution of earthquake-induced geohazards can be analyzed.Such insights facilitate earthquake disaster prediction and emergency response planning.The authors combined field investigations and spatial data analysis to examine geohazards induced by seismic events,examining ten earthquakes including the Wenchuan,Yushu,Lushan events,to elucidate the main control factors of seismic geohazard.The authors observed that seismic geohazard occurrence is usually affected by many factors,among which active nature of the seismogenic fault,seismic peak ground acceleration(PGA),topographic slope and geomorphic height differences,and distance from the fault zone and river system are the most important.Compared with strike-slip earthquakes,thrust earthquakes induce more high-altitude and high-speed remote landslides,which can cause great harm.Slopes of 0°–40°are prone to secondary seismic geohazards,which are mainly concentrated 0–6 km from the river system.Secondary geohazards are not only related to seismogenic fault but also influenced by the associated faults in the earthquake area.The maximum seismic PGA and secondary seismic geohazard number are positively correlated,and the horizontal and vertical ground motions play leading and promoting roles in secondary geohazard formation,respectively.Through the research,the spatial distribution of seismic geohazards is predicted,providing a basis for the formulation of emergency response plans following disasters. 展开更多
关键词 Wenchuan earthquake GEOHaZaRDS Main control factors comparative study Geological disater survey engineering Western China
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A Numerical Study of the Urban Intensity Effect on Fog Evolution in the Beijing-Tianjin-Hebei Region 被引量:5
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作者 LIANG Zhao-Ming GAO Shou-Ting SUN Ji-Song 《Atmospheric and Oceanic Science Letters》 2012年第3期240-245,共6页
The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy p... The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy parameterization-building energy model (UCP- BEM) urban physics scheme. The experiments were designed with a focus on the influence of different urban intensities, which are represented by a different fractional coverage of natural land, buildings, and energy consumption inside buildings in an urban environment. The results of this study indicate that urban areas notably influence fog evolution when natural land is reduced to a small fraction (e.g., less than 10%). Developed land changes fog evolution through urban effects. Higher urban intensity (HUI) generally results in warmer temperatures and lower wind speeds throughout the day, while inhibiting morning specific humidity loss and afternoon specific humidity gain because of the HUI effect on surface heat flux, surface roughness, and surface moisture flux. HUI leads to later and weaker liquid water content formation, with a higher liquid water content base, primarily due to its effect on near surface temperatures. This finding implies that HUI may inhibit the conditions for fog formation. In addition, urban areas with equal natural and developed land coverage seem to greatly enhance the upward surface moisture flux, which is attributed to the combination of a relatively large potential evaporation on developed land and an ample moisture supply from natural land. As a result, the specific humidity increases in the afternoon. 展开更多
关键词 numerical study urban intensity effect FOG the Beijing-Tianjin-Hebei region
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Comparative Study on Spatial Forms of Ancient Waterside Towns Based on Google Earth Pro-Taking the Example of Qingmuchuan,Fenghuang and Houliu in Southern Shaanxi,China 被引量:5
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作者 Mei Yang Zhaoyang Feng 《Journal of Environmental Science and Engineering(B)》 2020年第1期12-22,共11页
The purpose of this study is to address the problem of ancient towns dying out in developing countries,particularly China.Intensifying conflicts between human settlements and the natural environment are described,and ... The purpose of this study is to address the problem of ancient towns dying out in developing countries,particularly China.Intensifying conflicts between human settlements and the natural environment are described,and guidelines are proposed for the development of waterside ancient towns in China’s southern Shaanxi Province in the interest of conserving cultural and natural heritage.The towns of Qingmuchuan,Fenghuang and Houliu were selected as representative examples due to their strong reputation among tourists.They have the characteristics of traditional southern Shaanxi towns,but each has a completely different layout,space and structure.The comparative findings of this research provide a point of reference for establishing guidelines to preserve the integrity of ancient towns worldwide.In this paper,we compare the geographical conditions with the layout and texture of the streets by Google Earth Pro.And we analyze the details of spaces along the river zones,architectural styles and building decorations in order to research the relationship between the natural environment and the human settlement conditions.We note the unfortunate common trend of commercial development steadily taking over the natural environment,particularly the rivers and unique elements of the old towns.Finally,we summarize the similarities and differences of the spatial forms among these towns and put forward proposals for the further development of ancient towns.This research is important for all regions which stand to lose their national treasures.Consequently,measures should be to taken to curtail hyper development before we lose our historicscenery. 展开更多
关键词 Google Earth PRO waterside aNCIENT TOWNS comparative study on spatial forms Qingmuchuan Fenghuang Houliu
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A comparative study on the performances of synthetic diamond made by belt press & cubic press 被引量:1
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作者 Jia Pan~1,Lu Canhua~1,Ye Hongyu~2,Li Zhihong~3 (1.Nanyang Zhongnan Diamond Co.,Ltd.Nanyang,China) (2.Wuhan Wanbang Laser Diamond Tools Co.,Wuhan,China) (3.Industrial Diamond Association of China,Zhengzhou 450013,China ) 《金刚石与磨料磨具工程》 CAS 北大核心 2008年第S1期50-55,共6页
There are mainly two kinds of equipment to produce synthetic diamond,namely belt press & cubic press.It has been customary in the industry to regard synthetic diamond produced by cubic press is inferior to that ma... There are mainly two kinds of equipment to produce synthetic diamond,namely belt press & cubic press.It has been customary in the industry to regard synthetic diamond produced by cubic press is inferior to that made by belt press.With the on-going improvement in technology,know-how & accumulated experiences, perhaps it’ s time for us to review the qualities & performances of synthetic diamond made by the cubic press more objectively.Studies were carried out on the performances of the two kinds of diamond by choosing from top brands & top qualities,with coarser mesh sizes 20/30 & 30/40.Comparisons were made on parameters, such as TI,TTI,PPC,bulk density,compact,roughness and arealight.And the diamonds chosen were used to produce the relevant diamond core drill bits and saw blades,their respective cutting performances such as cutting efficiency,segments consumption were measured and reported in this paper.The report demonstrates that producing the high quality diamond does not depend on the type of presses(Belt or Cubic) but rather on the know-how,technology and what it is made. 展开更多
关键词 comparative study performance synthetic DIaMOND BELT press cubic PRESS
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A Comparative Study of Genetic Algorithm Parameters for the Inverse Problem-based Fault Diagnosis of Liquid Rocket Propulsion Systems 被引量:1
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作者 Erfu Yang Hongjun Xiang +1 位作者 Dongbing Gu Zhenpeng Zhang 《International Journal of Automation and computing》 EI 2007年第3期255-261,共7页
Fault diagnosis of liquid rocket propulsion systems (LRPSs) is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be signi... Fault diagnosis of liquid rocket propulsion systems (LRPSs) is a very important issue in space launch activities particularly when manned space missions are accompanied, since the safety and reliability can be significantly enhanced by exploiting an efficient fault diagnosis system. Currently, inverse problem-based diagnosis has attracted a great deal of research attention in fault diagnosis domain. This methodology provides a new strategy to model-based fault diagnosis for monitoring the health of propulsion systems. To solve the inverse problems arising from the fault diagnosis of LRPSs, GAs have been adopted in recent years as the first and effective choice of available numerical optimization tools. However, the GA has many control parameters to be chosen in advance and there still lack sound theoretical tools to analyze the effects of these parameters on diagnostic performance analytically. In this paper a comparative study of the influence of GA parameters on diagnostic results is conducted by performing a series of numerical experiments. The objective of this study is to investigate the contribution of individual algorithm parameter to final diagnostic result and provide reasonable estimates for choosing GA parameters in the inverse problem-based fault diagnosis of LRPSs. Some constructive remarks are made in conclusion and will be helpful for the implementation of GA to the fault diagnosis practice of LRPSs in the future. 展开更多
关键词 Liquid rocket propulsion systems inverse problem fault diagnosis genetic algorithm comparative study.
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Comparative study of different theories on active earth pressure 被引量:1
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作者 S.P.Yap F.A.Salman S.M.Shirazi 《Journal of Central South University》 SCIE EI CAS 2012年第10期2933-2939,共7页
Determination of distribution and magnitude of active earth pressure is crucial in retaining wall designs. A number of analytical theories on active earth pressure were presented. Yet, there are limited studies on com... Determination of distribution and magnitude of active earth pressure is crucial in retaining wall designs. A number of analytical theories on active earth pressure were presented. Yet, there are limited studies on comparison between the theories. In this work, comparison between the theories with finite element analysis is done using the PLAXIS software. The comparative results show that in terms of distribution and magnitude of active earth pressure, RANKINE's theory possesses the highest match to the PLAXIS analysis. Parametric studies were also done to study the responses of active earth pressure distribution to varying parameters Increasing soil friction angle and wall friction causes decrease in active earth pressure. In contrast, active earth pressure increases with increasing soil unit weight and height of wall. RANK/NE's theory has the highest compatibility to finite element analysis among all theories, and utilization of this theory leads to proficient retaining wall design. 展开更多
关键词 active earth pressure retaining wall PLaXIS comparative study RaNKINE's theory COULOMB's theory
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