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This paper reports a practical constitutive relation for highway subgrade soils. The proposed model is derived based on the laboratory repeated-load testing of four subgrade soils. Statistical parameters generally used in the power model of subgrade permanent strain are expanded into material constants with engineering significance. The constitutional relation reported in this paper can be used in the mechanistic-based pavement design of highway flexible pavements and railroad tracks.  相似文献   
2.
The purpose of this paper is to provide an introduction to the nature and purpose of airport automated people mover (APM) systems. Our objective is to provide a convenient research tool for persons seeking an introduction to the airport APM industry. Included are illustrations of typical system designs; a listing of existing airport APM systems, including a tabular presentation of selected data; an organization and discussion of the history and evolution of the existing systems; and a status report on current developments in the APM industry.  相似文献   
3.
In this paper, we represent a systematic review of stated preference studies examining the extent to which cycle infrastructure preferences vary by gender and by age. A search of online, English-language academic and policy literature was followed by a three-stage screening process to identify relevant studies. We found 54 studies that investigated whether preferences for cycle infrastructure varied by gender and/or by age. Forty-four of these studies considered the extent of separation from motor traffic. The remainder of the studies covered diverse topics, including preferred winter maintenance methods and attitudes to cycle track lighting. We found that women reported stronger preferences than men for greater separation from motor traffic. There was weaker evidence of stronger preferences among older people. Differences in preferences were quantitative rather than qualitative; that is, preferences for separated infrastructure were stronger in some groups than in others, but no group preferred integration with motor traffic. Thus, in low-cycling countries seeking to increase cycling, this evidence suggests focusing on the stronger preferences of under-represented groups as a necessary element of universal design for cycling.  相似文献   
4.
Haritos  Z.  Elliott  A. 《Transportation》1983,12(1):3-20
Transportation - In Canada, transportation regulation has evolved in response to the country's unique economic and demographic conditions—a land mass larger than that of the U.S.A. with...  相似文献   
5.
Based on a comprehensive review of the literature and preliminary testing performed on a subgrade soil, a testing methodology for repeated load testing was established. This testing protocol was verified using data from subgrade soil. The successful application of this testing protocol on the two subgrade soils proves that it can provide consistent, reliable results. A power model was used to fit the accumulated axial strain over load repetitions with the first hundred cycles excluded from the data set. A number of factors influencing the accumulation of permanent deformation were investigated. The results indicate that confining pressure, load frequency and density are relatively minor contributors to deformation accumulation. Moisture content, deviator stress and first cycle freeze-thaw are major factors governing permanent deformation. The effects of stress history resulting from staged loading are dependent upon the level of applied deviator stress. The interpretation of the rich and consistent deformation data derived from this testing protocol provide valuable insights for transportation engineers relative to the design, construction, operation and maintenance strategy of highway subgrades as well as railway roadbeds.  相似文献   
6.
This paper illustrates the value of using an action research methodology to improve understanding of gendered patterns of adoption and non-adoption of Intermediate Means of Transport (IMTs) and similar gender-related transport issues. It presents results from a novel action research project undertaken in five farming villages in southern Ghana, a region where IMT usage is currently low. The participatory action research study not only revealed important issues around differences between stated preferences and actual gendered patterns of adoption and non-adoption in the particular context of southern Ghana, but offers a methodology which may have value in many other gender and transport contexts across sub-Saharan Africa and beyond.  相似文献   
7.
QuanitativelyaccuratePredictionsofquenchinduceddistOnionandresidualstressrelyontheabilitytopredictthemicrosthectUralevolUtionthroughOutthequenchProcess.InlowaIloysteels,cUrrenresearchMshavefOcusedontheformationldneticsoffetrite,pearlite,bainiteandmartensite.However,temPeringcanhavealargeinfluenceondistOnionandresidualstrCss,andeffortstoaccountforthislagbehindthemodelingofthePrimnyphasetransihons.AsafirststeptowardsaccountingfortemPerillg,wehavedevelOpedanintemalstatevariablemodelthatuses…  相似文献   
8.
Coral reef areas are threatened worldwide by growing populations, tourism development, and use of poison and dynamite in fishing in areas adjacent to the reefs. The designation of marine protected areas is one strategy for addressing these problems. Wakatobi National Park, established in Eastern Indonesia in 1996, contains approximately 50,000 ha of coral reefs and a resident population of Sama-Bajo people whose traditions and current livelihoods tie them closely to the sea. The present research, using participatory rural appraisal methods, focused upon the impact of the designation of the Marine Park on their lives and investigated the potential for public participation in park planning and management. The Wakatobi Park Management Plan does not address the needs and interests of local people. Priority should be placed on adaptation of park zoning and protection regulations to accommodate the livelihood requirements of indigenous communities.  相似文献   
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