中国城市环境综合整治定量考核的经验与理论研究

中国城市环境综合整治定量考核制度实质上是建立一种以城市政府为对象的激励机制,以推动城市政府更有效地改善城市环境质量.此项制度实行以来,城市环境质量得以稳定与改善,但其效果、成本等仍需进一步评价,其理论也需进一步探讨.     

用气相色谱法测定低浓度SO2

本文采用气相色谱法测定低浓度SO_2,用简单的仪器和简便的操作技术,可得到满意的定量分析结果。     

区域水环境自净能力的定量评价

根据地震等级和风力等级的计算原理 ,提出了区域水环境自净能力等级的概念。它是描述一个地区水环境自净能力大小的定量指标。自净能力等级越高 ,区域水环境的自净能力越强。该指标从理论和应用方面来说都具有许多优点 ,概念明确 ,简单易行 ,具有重要的现实意义     

长埔——西岭锡矿资源定量评价模型

本文以长埔——西岭锡矿带的76个矿床为基础从中选取17个已知成型矿床,分别用矢量长度法和最优分割法进行地质变量的优化选择与储量等级规模的划分;采用特征分析与逻辑信息法建立锡矿资源半定量和定量评价广义模型;并对该区59个矿化点进行含矿性及可能矿床规模的定量预测评价,筛选出6个找矿靶区。     

本文数据由安吉竹种园风景区提供生态旅游可持续发展的Butler模型定量分析

生态旅游的可持续发展可用Butler模型定量描述，在理想状态下，生态旅游是一个自稳定系统，旅游人数N的增长具有持续性、快速性和有限性、N的增长不会超过环境容量阈值K。增长速率r和单位时间游人的增长量dN/dt与N存在对称关系。r,dN/dt,N与时间t存在内禀的线性关系。利用上述特征，可以对生态旅游的可持续发展进行评估和预测。本文对安吉竹种园生态旅游可持续发展进行了定量分析，结果表明，1994－1997年，景区游人增长方式与Butler增长模型基本相符。1998－2000年，由于假日旅游和广告效应影响，生态旅游的可持续性受到冲击。若不采取措施限制游人的增长，景区的生态旅游将是不可持续的。     

Risk-based quantitative method for determining blast-resistant and defense loads of petrochemical buildings

Petrochemical buildings are usually distributed near chemical installations and have a high risk of explosion because of the concentration of people. In order to effectively design and protect buildings against explosion, it is needed to determine the blast-resistant and defense loads reasonably. Based on the theory of risk, a triangular pyramid explosion risk model was established in this study, which combined the overpressure p, duration t, and frequency f of the explosion scene at the same time. The first principle of “acceptable cumulative frequency” and the key principle of “maximum explosion risk” were formulated. According to this method, the explosion risk of eight leakage units with 10 groups of leakage hole size and three dangerous wind directions were obtained. According to the cumulative explosion frequency curve and the explosion risk curve, blast-resistant and defense loads of the four walls were determined quantitatively. Among the four walls, the explosion overpressure were 44.0–74.5 kPa, and the corresponding duration were 34.1–39.1 ms. The cumulative explosion frequency were 2.11E−5 to 8.58E−5 times annually. The explosion risk value were 3.64E−3 to 5.35E−3 kPa·ms annually. The results indicated that it was of great importance for the calculation of the explosion risk to reasonably divide the leakage unit and determine the leakage frequency. The explosion scene and its frequency, the volume of the obstructed region, and the distance of the explosion source were the key variables that affected the explosive load. The final blast-resistant and defense load values were found in the case of the middle hole size leakage. Blast-resistant and defense loads not only met the risk acceptance standard but also considered the overpressure and the duration of explosion. At present, they have been extensively applied in the blast-resistant design and engineering transformation of buildings in SINOPEC.     

Non-Thermal Effect of Microwave Radiation on Human Brain

Summary This study focuses on an origin of interaction mechanism of microwave radiation with nervous system—quasi-thermal field effect. The microwave field can cause fluctuations and vibration of the charged particles and membranes in tissues. The hypothesis is, that this phenomenon is similar to the effect caused by Brown motion initiated by temperature and results in the same effects without rise in temperature. The electric field of 1 V/cm can introduce disturbance of the thermal equilibrium inside a cell of 10 μm radius, which is equivalent to disturbance produced by temperature rise of 1 K. The hypothesis, that microwave heating should cause an effect independent of the microwave modulation frequency, while field effect depends on modulation frequency, was examined experimentally. The 450 MHz microwave radiation, modulated at 7, 14 and 21 Hz frequencies, power density at the skin 0.16 mW/cm², was applied. The experimental protocol consisted of two series of five cycles of the repetitive microwave exposure at fixed modulation frequencies. Relative changes in EEG theta, alpha and beta rhythms of the group of 13 healthy volunteers were analysed. Analysis of the experimental data shows that: (1) statistically significant changes in EEG rhythms depend on modulation frequency of the microwave field; (2) microwave stimulation causes an increase of the EEG energy level; (3) the effect is most intense at beta1 rhythm and higher modulation frequencies. These findings confirm the quasi-thermal origin of the effect, different from average heating.