浅谈需求弹性理论

需求规律反映需求量按照和价格相反的方向变动.需求弹性理论揭示需求量和价格变动之间的数量关系.需求价格弹性的大小对生产者和经营者的价格决策,是十分重要的依据.     

西方经济学中的弹性理论及其应用

本文探讨了西方经济学中的弹性理论及其在经济预测与决策、税收分析、经济立法与仲裁和国际经济领域中的应用及其借鉴价值。     

需求价格弹性理论应用勘误

根据需求价格弹性的大小,可以确定销售者收益与销售产品价格涨落之间的关系。给出反例,证明了当前经济学界对需求价格弹性、价格涨落与收益之间关系的结论有不确切之处,并强调指出在此问题中不可随意使用需求价格弹性的定义式和计算式。     

蛛网理论与弹性理论

D表需求,S表供给,P表价格,则有D＝f（p）,S＝g（p）,在动态情形下与时间t（年代）有关,应为Dt与St。确定均衡价格时,应依据t年代需求与年代t－1时的供给来确定,应有关系f（pt）＝g（pt-1）,由些解出均衡价格pt＝p（t）。一般在f与g均为线性函数时,可用差分方程解出p（t）曲线呈蛛网现象,有收敛、发散与闭封三态。本文第一部分除上述情形予以清晰推演以外,并特别指出当f与g均为非线性时仍有蛛网现象。在动态情形下,引进与时间有关的需求弹性系数,以及供给弹性系数再定义此两者的弹性比率μ（t）＝ED（t）／ES（t）那么,我们在本文第二部分里将指出：在弹性理论下来考察Pt＝P（t）曲线时,可严格得出：依据μ＜1,μ＝1与μ＞1,必有具收敛、封闭与发散三态的蛛网现象。     

浅析需求弹性理论在市场营销中的应用

系统地阐述了在市场营销过程中,必须借用需求弹性理论（主要包括需求的价格弹性、交叉弹性和收入弹性）,并从产品价格、相关产品价格、消费者收入这三种主要因素入手,分析各种因素对产品需求量的影响程度。为制定较为正确的营销策略,在竞争中求得生存和发展。     

经济学中的需求弹性与总收益弹性的关系

在经济学中 ,经常要研究价格、需求量、总收益三者的关系 ,这样就需要计算需求价格弹性和总收益价格弹性。本文导出两者的重要关系 ,从而使这类问题的研究变得更简单 ,反映经济中的量价关系更清晰     

需求价格弹性理论在价格策略中的应用

需求弹性在企业经营中是一个非常重要的问题。本文首先论述了需求弹性的一般含义,由此分析需求弹性在市场预测中的应用和在企业价格决策中的重要性,以及如何制定企业的价格策略。     

需求价格弹性理论及其经济应用

需求价格理论是经济学中的一个重要理论,文章论述了需求价格弹性理论的含义,并通过需求价格弹性理论在实际生活中的应用,指出需求价格弹性理论为政府或企业的定价策略提供了一定依据。     

经济学中的需求弹性与总收益弹性的关系

在经济学中，经常要研究价格、需求量，总收益三者的关系，这样就需求计算需求价格弹性和总收益价格弹性。本文导出两者的重要关系，从而使这类问题的研究变得更简单，反映经济中的量价关系更清晰。     

青藏铁路格拉段货运量预测

分析了青藏铁路格拉段,进出藏运量差异大,存在地区间客货运输的需求差异和季节波动的特殊性.针对格拉段所在经济区域存在大量受运能制约而无法实现的潜在运输需求的特点,在社会货运总量预测中提出了货运诱发系数的概念,用以度量新线建设对社会货运量的带动作用.     

Construction Management Innovation and Practice in Qinghai-Tibet Railway Project

The construction of the Qinghai-Tibet Railway is one of the significant decisions made by the CPC Central Committee and the State Council at the beginning of the new millennium, it is also the landmark project of the China＇ s Western Region Development campaign. The railway will become an economical, high-speed, high capacity, all-weather passageway, which will play an irreplaceable role in the areas it links, in terms of economic prosperity and social advancement, the implementation of the opening up policy, in strengthening unity of different ethnic groups, as well as the wellbeing of all the residents along the way. Since its commencement on June 29^th, 2001, the Golmud-Lhasa Section （G-L Section） of the Qinghai-Tibet railway has been advancing safely and smoothly, with high construction quality. Up to now, the main structures along the whole section are nearly completed, experimental projects in the post-station section are almost concluded （except signal works）, tracks of 743 km have been laid. In 2005, the whole project entered its decisive stage. The goal of this year is： totally complete the sub-track works, nearly complete post-station works, completely link up the whole section. During the construction, three major obstacles must be removed, i.e., permafrost soil, deficient oxygen content in arctic alpine regions, and the fragile ecological environment. Up to now, remarkable achievement has been made in struggling with the three problems, and precious experience of constructing railway on permafrost plateau has been acquired. All the roadbeds, culverts and tunnels are of stable and reliable quality so far.     

The Impact of Climate Warming on Permafrost and Qinghai-Tibet Railway

Global wanning is an inarguable fact. Permafrost is experiencing a change due to climate warming in Qinghai-Tibet Plateau, such as the decreasing of permafrost table, the rising of permafrost temperature, etc. On the basis of analysing the permafrost change under the climate change and engineering action, the thermal regime and spatial distribution of permafrost are predicted for air temperature rising 1℃ and 2.6℃ after 50 years in this paper. The results show that climate change results in the larger change for the thermal regime and spatial distribution of permafrost. Permafrost change will produce the great effect on the Qinghai- Tibet Railway engineering, not only resulting in the decreasing of permafrost table beneath the roadbed, but also resulting in thawing settlement due to the thawing of ground ice near permafrost table. The idea of cooling roadbed and actively protecting permafrost for the Qinghai-Tibet Railway engineering could adjust and control the permafrost thermal state, some better methods are provided to ensure the engineering stability in the areas of warm permafrost and high ice content.     

Experimental Study on Riprap Air-Cooled Roadbed of Qinghai-Tibet Railway

The riprap air-cooled roadbed and common roadbed experimental project were designed and carried on in Qingshuihe test filed, an area of warm permafrost category with the fine frozen soil along Qinghai-Tibet Railway, to decide the temperature field of the roadbed after railway construction. Based on ground temperature variation of natural hole, left and fight shoulder＇ s hole, the maximum thawing depth, and the deformation in these two kinds of roadbed were analysed comparatively. It showed that the riprap air-cooled roadbed had better effect of lowering ground temperature, lifting the maximum frozen-thawing depth obviously and decreasing deformation than that of the common roadbed. Therefore, the riprap air-cooled roadbed was a positive frozen soil protection measure for it effectively decreased ground temperature and protected permafrost.     

Bridge-instead-of-embankment Design Concept for Qinghai-Tibet Railway

The paper gives a brief introduction to the design concept of ＂bridge instead of embankment＂ for Qinghai-Tibet Railway, and illustrates an optimised structure style and corresponding considerations for the bridges built in unsteady frozen ground zone in Qinghai-Tibet Plateau. The dynamic simulation analysis of trairrbridge system fro verifying its safety level and Spedin ride index during operation and Excel VBA programming technology for improving design efficiency are also mentioned in this paper.     

The Features of the Ecological Environment and Protective Solutions along the Qinghai-Tibet Railway

On29June,2001aninaugurationceremonyfortheQuinghai TibetRailway,aprojectattractingworldwideattention,washeldsimultaneouslyattheCityofGolmudinQinghaiprovince,andtheCityofLhasainTibetAutonomousRegion,indicatingthattheconstructionofthesectionfromGolmudtoLhasaoftheQinghai TibetRailwaywasfullytocarryout.ThePlateauofQinghai Tibethasaveryfragileecologicalenvironment.ThestategaveprioritytotheissueoftheecologicalenvironmentalprotectionintheconstructionoftheQinghai TibetRailway.PresidentJiangZh…     

A Roadbed Cooling Approach for the Construction of Qinghai-Tibet Railway

Over one half of the permafrost along the Qinghai-Tibet Railway is ＂warm＂ and approximately 40% ice-rich. Under global warming, the construction of the Qinghai-Tibet Railway needs to consider climate changes over the next 50 - 100 years. Recent estimates indicate that the air temperature on the plateau will increase by 2.2- 2.6℃ by 2050. Thus, the key to the success of the railway construction lies in preventing the permafrost underlying roadbeds from thawing. It has been more than 100 years since the first railway was build over permafrost. A frost damage ratio of greater than 30 % has been reported for all the railroads built in permafrost regions. Based upon the experience and lessons leamed from roadway constructions over permafrost, this paper proposes a more proactive design approach for the construction of the Qinghai-Tibet Railway. This approach focuses on cooling down the roadbed by lowering the ground temperature and is different from the passive method of preventing permafrost from thawing by simply increasing thermal resistance （e. g., increasing embankment height and using insulating materials）. This ＂roadbed cooling＂ design approach is especially relevant to ＂warm＂ and ice-rich permafrost areas. A number of measures can be taken to cool down the roadbed, including proper selection of roadbed material, and configurations to adjust solar radiation, heat convection, and heat conduction patterus in and/or around the roadbed.     

Study and Application of Health Care Measure in Tunnel Construction of Qinghai-Tibet Railway

1Overview FenghuoshanTunnelProjectwasakeycontrol projectinQinghai TibetRailwayconstruction.It wasarailwaytunnelofthehighestelevationintheworldwithrailheadlevel4905mandtotallength1338m.Table1Railwaytunnelofhighaltitudeintheworld TunnelnameGuanjiaotunnelYangbajingtunnelKunlunshantunnelJialiertunnelFenghuoshantunnel Sealevelelevation m36984313450046804905NationalityChinaChinaChinaPeruChina Constructiondecade19782003200218932002TheFenghuoshanwasstyled“lifeforbidden zone”.Itsannualaverag…     

Application and Study on Dynamic Design in Qinghai-Tibet Railway Construction

0Preface Permafrostisasoilmediumwhichisextremely sensitivetotemperatureandsurroundingfactors.Themostessentialdistinctionbetweenpermafrost andotherrockorsoilisthatitcontainsground ice.Whileconstructinganystructureson permafrost,twomajorengineeringproblemsmustbesolved:freezingheaveinflationandthawing settlement.TheGolmud LhasaSectionofQinghai Tibet Railway,withatotallengthof1118km,hasa totaldistanceof632kmrunningonpermafrost,outofwhichabout550kmiscontinuous permafrost,82kmispatchypermafrost,9…     

青藏铁路多年冻土场地波速特性分析

为分析冻土场地波速变化规律,通过现场钻孔波速测试,并结合已有典型场地波速资料,研究了青藏铁路沿线多年冻土场地波速比的经验值及波速变化受控制因素的影响规律。结果表明:多年冻土场地纵横波速比经验参考值可选用1. 5左右;冻土层波速传播规律与地温、土层埋深、土质属性、冻结冰晶含量等诸多因素相关;冻结作用使土体的结构性增强从而冻土体强度增强,冻结状态下土体的波速通常大于未冻结场地土体;多年冻土层波速值随土层深度的增加、地温的降低和冻结土体中冰晶含量的增加而增加。     

青藏铁路钻孔桩施工技术浅谈

在青藏铁路钻孔桩施工过程中，通过使用先进的机械设备和科学合理的施工组织安排，以及重点工序的质量控制，既提高了工作效率，又保证桩基质量、确保了施工工期。简要介绍了钻孔桩施工工艺及工程的质量控制等内容。