黄山自然景观成因及边际效应探讨

黄山是中国十大风景名胜之一，以奇特的自然景观著称于世，被誉为“天下第一奇山”，并已被联合国列为世界遗产保护区。黄山是以自然景观为特色的山岳风景区，呈现典型花岗岩峰林地貌，景观类型丰富多样，奇松、怪石、云海、温泉素称“黄山四绝”。以山石地貌为主体的自然景观成因是内、外力综合作用的结果，具有得大独厚的成景条件。自然景观的时空分布特征，反映了自然界普遍存在的边际效应规律，运用自然边际效应的启示，将有助于对旅游资源的发掘、开发和保护工作。     

General equilibrium effects of a supply side GHG mitigation option under the Clean Development Mechanism

The Clean Development Mechanism (CDM) under the Kyoto Protocol to the United Nations Framework Convention on Climate Change is considered a key instrument to encourage developing countries' participation in the mitigation of global climate change. Reduction of greenhouse gas (GHG) emissions through the energy supply and demand side activities are the main options to be implemented under the CDM. This paper analyses the general equilibrium effects of a supply side GHG mitigation option-the substitution of thermal power with hydropower--in Thailand under the CDM. A static multi-sector general equilibrium model has been developed for the purpose of this study. The key finding of the study is that the substitution of electricity generation from thermal power plants with that from hydropower plants would increase economic welfare in Thailand. The supply side option would, however, adversely affect the gross domestic product (GDP) and the trade balance. The percentage changes in economic welfare, GDP and trade balance increase with the level of substitution and the price of certified emission reduction (CER) units.     

动荷载作用下地下岩体洞室应力特征的影响因素分析

用FLAC3D初步分析了动荷载作用下埋深、洞室形状、地应力特征对地下岩体洞室应力特征的影响。分析结果表明:动荷载下,随着埋深的增加,各种洞型应力量值有明显的减小趋势;地应力状态对地形洞室的应力响应有较明显的影响,在自重地应力为主的情况下,洞室拱顶、拱底地最小主应力处于拉应力状态,而构造地应力为主的情况下,洞室拱顶、拱底最小主应力处于压应力状态,且随着侧压系数的增加,洞室的应力由较明显的减小趋势;动荷载作用下,不同断面形状的洞型应力响应有一定区别,圆形洞室应力响应最小,矩形洞室应力响应最大,随埋深、地应力的增加,洞形对洞室应力响应影响减小,当埋深超过300 m后,洞型对应力的影响变化程度不大。     

美国侧面碰撞规程下轿车变形侵入仿真研究

为更好地分析汽车侧面碰撞过程中驾乘人员安全,根据美国联邦机动车安全法规FMVSS214碰撞要求,采用显式有限元分析软件LS-DYNA详细建立了某公司轿车有限元整车模型和可变形移动壁障有限元模型,研究了美国侧面碰撞规程下可变形移动壁障以54 km/h速度撞击轿车侧面的变形侵入过程仿真模拟和轿车侧面车门不同水平级的变形侵入对乘员损伤程度的影响。结果表明:有限元模拟结果与实车碰撞试验结果吻合较好,模型可信;轿车车门中部位置对驾乘人员损伤影响最大,乘员损伤AIS值接近3(严重损伤);参数加权平均变形侵入量能较好的反映车辆侧面碰撞下车身侧围的变形侵入情况。     

The Damping of Off-Central Impact for Selected Industrial Safety Helmets Used in Poland

The paper presents a review of head injury criteria and determines an assessment criterion for test results. Parameters characterizing the protection properties of off-central impacted industrial helmets are chosen and the test stands used in the Central Institute for Labour Protection to test those parameters are presented. The idea of damping 2 selected industrial helmets used in Poland is discussed. The test results of the parameters characterizing the protection properties are compared for damped and not damped helmets.