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791.
Abstract Xinjiang's oasis agriculture has made enormous strides over past decades. Structural adjustment of oasis agriculture sector has promoted production diversification. Xinjiang's oasis agriculture sector is entering a new era. The era means more adjustments in oasis agricultural and rural economic structure so as to realize the sustainable development of agriculture. By summing and analyzing the main problems in Xinjinag's oasis agricultural structure, such as raising farmer's income, industry structure within agriculture, rural urbanization, pressure coming from market, agricultural environment degradation, puts forward the thinking, director and countermeasures to adjust oasis agricultural structure. 相似文献
792.
《International Journal of Sustainable Engineering》2013,6(3):212-224
Nowadays, many countries are looking towards sustainability as a goal because our world has limited resources and serious environmental impacts. In the construction industry, the process of sustainable selection of structural material is considered one of the keys to achieve more sustainable construction. In this paper, the theories of decision making are utilised to develop an approach for evaluation and ranking the structural materials over their total life based on sustainability criteria using multi-attribute decision-making methods. One of them is Analytical Hierarchy Process which is utilised to build the problem hierarchical structure and assign weights of the predetermined sustainable factors. The other is Technique for Order Preference by Similarity to the Ideal Solution which is utilised to rank the structural materials within both each material life cycle phase and the complete material life cycle phases. The third is the concept of entropy by Shannon to evaluate the weight factor for each phase of material life cycle. The proposed approach presents an objective, systematic and comprehensive method for the sustainable ranking of materials that links between the structural element design and the sustainable selection of materials. 相似文献
793.
Anthropogenic-driven changes with focus on the coastal zone of Mauritius, south-western Indian Ocean
R. Ramessur 《Regional Environmental Change》2002,3(1-3):99-106
Some 44% of the world's population lives within 150 km of the coast and mass migration towards the coast will continue in
the decades ahead. Degrading and exhaustive uses of land, water and other coastal resources and disruption of environmental
processes through degradation of environmental quality and loss of critical terrestrial and aquatic habitats can lead to serious
deleterious impacts on the health and productivity of coastal ecosystems. Following the Arusha Resolution (1993), the Seychelles
Statement (1996) and the Colombo CZM Workshop (1999), the need for integrated coastal zone management has become critical
because of the limited land resources and unproportional domination of coastal areas in the wider Caribbean and Indian Ocean/
Pacific island states. The coastal zone of Mauritius (1,850 km2, 20°S, 58°E, south-western Indian Ocean, 1.12 million inhabitants) was redefined in 1997 in the Environmental Protection
Act of 1991 [Part VII (Act 34)] to include all islets within the Exclusive Economic Zone (EEZ; 1.7 million km2). During the 1980s, the Mauritian economy underwent major structural changes successfully, with a rapid phase of industrialization
diversifying into two major activities, textiles and tourism. Existing reports and data in a common framework have to be synthesized
and organized to fill existing gaps in knowledge with data collection and scientific inquiries, to identify social and economic
drivers and to relate socioeconomic change to demands for environmental resources (land use, water resources, marine systems)
and environmental impacts as proposed under the MERMAID (Mauritius Environmental Resource Management and Industrial Development)
project. Nutrient flux and sediment trace metal contamination studies are currently underway to investigate different watersheds
impacted by agricultural, urban and industrial activities in the north-west of the island. There is a pressing need to integrate
the natural sciences with socioeconomic disciplines as proposed by the International Human Dimensions Program (IHDP) for an
integrated management of coastal zones. Three integrated pilot projects in the Pacific-Indian Ocean and wider Caribbean as
identified by Land Ocean Interaction in the Coastal Zone (LOICZ) in the future, including current status and changes in material
fluxes from drainage basins, transboundary impacts from the ocean and atmospheric inputs, could elucidate the land–sea interactions
and human dimensions of change on small islands. The sustainability of marine resources and the conservation of biological
diversity will depend on a critical understanding of linkages between human activities and ecological responses and upon a
citizenry that assumes ownership of these regions. Case studies would also help in investigating how humans affect transport
pathways and biogeochemical cycles in small island states.
Electronic Publication 相似文献
794.
安徽省土地利用变化及其驱动力分析 总被引:38,自引:5,他引:33
利用GIS技术,基于20世纪,80、90年代中期和2000年三期土地利用数据,分析了安徽省的土地利用变化,土地利用变化在空间上表现为:变化范围广,几乎遍及全省各个角落;西部和南部山区其土地利用变化的幅度相对较小,中部,东部和北部地区变化幅度较大;在合理-巢湖-芜湖-马鞍山一片其变化幅度最大,土地利用变化在数量及时间上表现为:耕地(含水田和旱地)大幅减少,其次为草地和林地,代之以城镇用地,农村建设用地和水域的迅速增加,1987-1995年变化的幅度明显小于1995-2000年的变化幅度,随后运用典型相关分析方法对安徽省90年代中期和2000年之间的土地利用变化的驱动因子进行了统计分析,定量诊断出各驱动因子对安徽省土地利用变化的贡献作用大小,对1987-1995年安徽省土地变更数据进行统计分析,揭示了期间土地利用变化的驱动力。 相似文献
795.
A full probabilistic Explosion Risk Analysis (ERA) is commonly used to establish overpressure exceedance curves for offshore facilities. This involves modelling a large number of gas dispersion and explosion scenarios. Capturing the time dependant build up and decay of a flammable gas cloud size along with its shape and location are important parameters that can govern the results of an ERA. Dispersion simulations using Computational Fluid Dynamics (CFD) are generally carried out in detailed ERA studies to obtain these pieces of information. However, these dispersion simulations are typically modelled with constant release rates leading to steady state results. The basic assumption used here is that the flammable gas cloud build up rate from these constant release rate dispersion simulations would mimic the actual transient cloud build up rate from a time varying release rate. This assumption does not correctly capture the physical phenomena of transient gas releases and their subsequent dispersion and may lead to very conservative results. This in turn results in potential over design of facilities with implications on time, materials and cost of a project.In the current work, an ERA methodology is proposed that uses time varying release rates as an input in the CFD dispersion simulations to obtain the fully transient flammable gas cloud build-up and decay, while ensuring the total time required to perform the ERA study is also reduced. It was found that the proposed ERA methodology leads to improved accuracy in dispersion results, steeper overpressure exceedance curves and a significant reduction in the Design Accidental Load (DAL) values whilst still maintaining some conservatism and also reducing the total time required to perform an ERA study. 相似文献
796.
IntroductionElectronics assembly workers are reported to have a high prevalence of musculoskeletal disorders (MSDs). This study investigated the prevalence of cervical MSDs and the complex relationships between cervical MSDs and individual, physical, psychosocial factors among electronics assembly workers. Methods: In this cross-sectional survey, self-administered questionnaires from 700 workers in electronics manufacturing workshops were analysed. Information concerning musculoskeletal symptoms, personal and work-related factors was collected. Finally, the prevalence of cervical MSDs was computed for different subgroups, and the relationships with different factors were analyzed using logistic regression and structural equation modeling (SEM). Results: The total 12 month prevalence of cervical MSDs among the survey population was 29.4%. Variables of gender, job tenure, twisting head frequently, neck flexion/extension for long time and work required to be done quickly showed significant associations with MSDs in a multivariate logistic regression (P < 0.05). The SEM analysis showed moderate and significant correlations between postural load (γ = 0.279), gender (γ = 0.233) and cervical MSDs, while there were weak but significant correlations between vibration (γ = 0.024), work stress (γ = 0.126), job tenure (γ = 0.024) and cervical MSDs. Both work stress and vibration affected the MSDs indirectly through postural load. Conclusions: The logistic regression results support previous general epidemiological MSD studies, and indicates that individual, physical, and psychosocial factors are related to cervical MSDs. The SEM provides a better approximation of the complexity of the relationship between risk factors and cervical MSDs. Improving awkward postures may be effective ways to control the influence of occupational stressors or vibration on MSDs. Practical Applications: The study is to improve prevention of MSDs among electronics assembly workers and promote their occupational health. 相似文献
797.
798.
为实现通过过程控制和管理提高认知性视觉显示终端(VDT)作业人员可靠性和绩效的目标,应用结构方程模型(SEM)研究作业过程表征方法。构建认知性VDT作业的信息加工过程模型,抽取13个基本认知动素(CT),提出CT概念结构模型假设,设计外显指标测试题项,运用问卷调查样本数据构建结构方程和测量方程;对测量数据与结构方程模型的拟合度进行分析,并训练BP神经网络模式识别模型对作业过程进行还原检验。结果表明:认知性VDT作业过程模型有效,元认知控制其他12个CT的结构关系成立,认知性VDT作业过程可由包括元认知在内的13个基本CT解析。 相似文献
799.
China has witnessed rapid economic development since 1978, and during the time, energy production and consumption developed at a tremendous speed as well. Energy efficiency which can be measured by energy consumption per unit of GDP, however, experienced continuous decrease. Theoretically, the change of energy efficiency can be attributed to industry structural change and technological change. In order to explain the transformation of Chinese energy efficiency, we adopt logarithmic mean Divisia index techni... 相似文献
800.
土地利用/土地覆被变化研究范式的转变 总被引:2,自引:0,他引:2
土地利用/土地覆被变化(LUCC)研究的形成和发展经历了从前科学(无范式)到科学(以范式为标志)的历史过程.认识LUCC研究范式及其转变的内涵和实质对其理论和应用的发展与完善具有极为重要的意义,并有助于提高解释和预测能力.本文以库恩的“范式”和“范式转变”为基本脉络,剖析了LUCC研究中的实证主义范式、科学人文主义范式、结构功能主义范式以及复杂性范式,并指出范式及其转变主要在本体论、认识论和方法论三个层面表现出来.实证主义范式强调决定论以及主客体分离,认为应把经验与逻辑分析作为客观地认识现实的基础,它贯穿1UCC不同发展阶段,在初期发挥了重要作用,至今仍主导着LUCC研究;科学人文主义在科学主义或实证主义的基础上强调了人的主体性,修正了它们的片面性;结构功能主义为我们提供了一种可资参考的系统分析方法,在宏观层面的许多重要理论见解和研究方法,值得LUCC研究者关注和借鉴;复杂性范式强调土地系统的非线性、自组织、连通性等特征,为LUCC研究提供了一种新的科学世界观、认识论和方法论,利用复杂性理论研究具有非线性特征的复杂土地系统,体现了当前LUCC研究的范式转变. 相似文献