首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
If energy conservation were a goal of a federal budget policy maker, such conservation could be achieved by reinvesting the highway trust fund in any of several other alternative federal programs (except criminal justice), especially in railroad and mass transit construction and national health insurance (see Table 1). Total employment would increase in each alternative program examined. For example, if construction monies were shifted from highways to railroads, the energy required for construction would be reduced by about 62 percent and employment would increase by 3.2 percent. By comparing the dollar, energy, and employment requirements of a highway transportation system with such requirements for a railroad transportation system, we obtained detailed information from which we concluded the following: 1) Passenger transport by railroad was much less dollar and energy demanding and required more labor than car transport in 1963. If the dollar savings had been respent in an average way by consumers, the net impact would have been to reduce the energy savings and further increase employment. A similar conclusion was reached in a study of bus substitution for automobiles in urban areas (20). If the marginal substitution effects would have held over the whole range of change, and the dollar savings had been spent on the construction of railways, then about 3.0 billion gallons of gasoline could have been saved annually and 1.2 million new jobs created. 2) Freight transport by railroad was less expensive, in terms of dollar, energy, and labor requirements, than was truck transportation in 1963. If, under a national shift to rail freight, the dollar savings had been absorbed as personal consumption expenditures, a net increase of labor and energy would have ensued. If the dollar savings had been absorbed as a tax and respent on railroad and mass transit construction, about 0.3 billion more gallons of gasoline (energy equivalent) would have been consumed annually and 1.2 million jobs created, under a complete shift to rail. Had there been a full shift from intercity car and truck transportation to transportation by railroad with dollar savings spent on railway construction, 2.7 billion gallons of gasoline (energy equivalent) could have been saved and 2.4 million new jobs could have been created in 1963.  相似文献   

2.
3.
4.
5.
6.
7.
基于涡度相关系统对海南儋州橡胶林生态系统长期定位观测,获取橡胶林生态系统2013年5月-2014年4月有效能、湍流能以及各种气象数据,分析其能量平衡过程以及能量闭合度。结果表明:1)显热通量(H)、潜热通量(LE)、土壤热通量(G)与净辐射通量(Rn)日变化趋势相似,都为单峰型。雨季LE明显大于旱季,不同季节H差异不明显。雨季白天LE远高于HG在数值上与Rn差1~2个数量级,且变化滞后于Rn变化。2)冠层热储量(S)、显热储量(Sa)和潜热储量(Se)变化趋势均为倒“S”型,但S、Se变化趋势与Sa变化趋势相反。橡胶林冠层热储量,Se贡献更大。3)雨季波文比都远<1,即雨季净辐射主要用于潜热输送。旱季波文比较雨季大,平均值为0.8,说明整个旱季水汽传输与显热输送消耗能量比重相当。4)各能量通量分量均表现为净辐射(Rn)>潜热通量(LE)>显热通量(H)>土壤热通量(G)>冠层热储量(S)。雨季潜热通量(LE)所占净辐射比例达76.28%,显热通量仅为15.32%;旱季潜热通量(LE)、显热通量(H)占净辐射通量比例分别为:43.69%、31.74%。5)橡胶林能量不闭合度雨季低于旱季。半小时尺度上旱季不闭合度为33%,雨季不闭合度为24%,全年不闭合度为27%,与中国通量网(ChinaFLUX)研究结果相比,处于中等水平。日尺度全年能量闭合度为13.82%,全年月尺度能量不闭合度为13.41%。  相似文献   

8.
9.
Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited. Some modern schemes incorporate biogeochemical and ecological knowledge and, when coupled with advanced climate and ocean models, will be capable of modeling the biological and physical responses of the Earth system to global change, for example, increasing atmospheric carbon dioxide.  相似文献   

10.
发展绿色能源 |净化城镇空气   总被引:2,自引:0,他引:2  
发展绿色能源一燃料乙醇产业,对实现可持续发展战略,减轻环境污染,特别是城镇的空气污染,节省石油资源,减少石油进口的压力都具有十分重要的战略意义。在我国南方,发展能源甘蔗和燃料乙醇产业,能最大限度地发挥该地区中、南亚热带的区域优势,做到既发展生产又保护了环境。  相似文献   

11.
12.
13.
The male Anna Hummingbird accommodates seasonal changes in energy demands by varying its allocation of time and energy among different activities; total energy expenditures change relatively little. Augmented terrritorial defense during the breeding season is made possible by increased feeding efficiency due to the availability at this time of very nectar-rich flowers.  相似文献   

14.
能源甘蔗——生产燃料酒精的最佳原料   总被引:5,自引:0,他引:5  
能源甘蔗对太阳光能的利用率比其他作物的高,它需用的土地比其他作物的少,其甘蔗产量一般为150-180t·hm-2·年-1,最高达280t·hm-2·年-1,故其发酵糖量高达20.25-29.70t·hm-2·年-1,可产酒精9.06-10.87t(11323-13587L)·hm-2·年-1,高的可达12.08t(15097L)·hm-2·年-1。蔗农乐意种植能源甘蔗,酒精厂愿意收购能源甘蔗。  相似文献   

15.
16.
耦合Schr?dinger-KdV方程具有能量守恒特性.基于四阶平均向量场方法和傅里叶拟谱方法构造了耦合Schr?dinger-KdV方程的高阶保能量格式,并用新格式数值模拟孤立波的行为.结果表明新的高阶格式能较好地模拟耦合Schr?dinger-KdV方程孤立波的演化行为,且精确地保持方程的离散能量守恒特性.  相似文献   

17.
烟叶烘烤能耗与节能途径分析   总被引:4,自引:0,他引:4  
结合烟叶烘烤过程中水分的散失机理,对热风循环烘烤模式的优缺点进行了分析和探讨.指出对现有热风循环烘烤模式进行变革和创新是实现烘烤节能的根本途径。  相似文献   

18.
Energy and the gross national product have grown hand in hand at 3 to 3(1/2) percent a year for almost 40 years. Our energy growth is slowing down and will sentially level off in the 1990's. Our production of oil and gas passed a peak in the early 1970's, and there is no resource base to justify predictions of increased yields. Coal is the only fossil fuel capable of increased production. There are serious doubts that our uranium resources can support a large light-water reactor program. Finding rates for petroleum, natural gas, and uranium are less than half of what they were 20 years ago.  相似文献   

19.
20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号