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161.
国土空间规划中的承载力反思:概念、理论与实践 总被引:2,自引:0,他引:2
资源环境承载力是国土空间规划的科学基础和约束条件。通过梳理承载力概念、理论和实践应用的发展,指出其在研究应用中存在概念边界模糊、评价偏向于指标计算、承载力传导机制研究不足等问题。国土空间规划体系改革,以及新时代生产生活和发展方式变革对国土空间规划提出了新的要求。支撑空间规划编制的承载力评价应进一步明确承载力的概念内涵、明晰承载力内在机制、构建承载力评价体系;在实践应用中应当根据国土空间规划和空间治理的新变化新需求,支撑空间规划的新目标、切合空间治理的新模式、顺应空间治理的新手段,为确定国土空间开发利用与保护修复的主要指标、战略部署,以及指标约束传递与地域功能传导等提供科学依据。 相似文献
162.
针对目前我国道路交通信号控制机产品存在的质量问题,对信号机生产企业进行深入调研,详细分析信号机发展现状、国内外产品认证制度及信号机强制检测制度等,并结合我国交通信号机产品自身的特点和实际,参考国外产品认证模式、认证流程,提出我国信号机产品以型式试验、初始工厂检查和获证后监督为模式的认证框架体系。信号机产品质量认证框架体系的建立,对提高产品质量,规范行业生产,将发挥积极的促进作用,同时也为我国交通安全产品的质量控制提供了新思路。 相似文献
163.
164.
近年来国家超高压电网的建设发展迅速,使得降低工程运行期间电磁场对环境的影响成为当前重要的研究课题.以钦州、防城港电厂送出500 kV输电线路工程为例,简要分析了工程电磁场及无线电干扰对环境的影响,提出了切实可行的环保措施,以将其带来的负面影响减轻到最低程度. 相似文献
165.
通过理论计算和实际测量,揭示220 kV输电线路下的电磁场强度分布情况.从实际测量结果来看,输电线路下电磁场强度高于环境背景值,但均低于国家标准限值. 相似文献
166.
We studied the factors that enhance food recognition and consumption in young canaries when confronted with adults. In contrast
to previous studies on canaries, in which social transmission of food habits was studied in the context of dyadic interactions
(one juvenile–one adult), we proposed a more realistic framework in which young canaries were studied in the context of triadic
interactions, free or not, with adults of both sexes. We found that during free interactions, the young bird only eats with
a familiar male and that this association enhances the social transmission of seed handling. When the juvenile was separated
from the adults by a transparent partition, it only learned to husk seed if it was present at the feeder at the same time
as a familiar adult acting as a demonstrator. The presence of adults that are familiar but do not act as demonstrators does
not facilitate social transmission of handling. However, the presence of a familiar, demonstrating female had also no effect
on this transmission. Coordination of the actions of the experienced bird and of the naive subject is required for social
transmission to occur. Action coordination does not depend solely on the level of familiarity between partners but also on
the role played by the demonstrator (here, the adult male) that looks after the juvenile during its transition towards independence. 相似文献
167.
Experiments on mixing and dissipation in internal solitary waves over two triangular obstacles 总被引:2,自引:1,他引:1
Chen-Yuan Chen John R.-C. Hsu Ming-Hung Cheng Cheng-Wu Chen 《Environmental Fluid Mechanics》2008,8(3):199-214
A series of laboratory experiments was undertaken in a stratified two-layer fluid to investigate the energetics of the interaction
between an internal solitary wave (ISW) and triangular obstacles, as well as to determine the partitioning of ISW energy and
its subsequent dynamics. The ISW energy was dissipated as a result of internal breaking and turbulent mixing induced by wave
instability. Tests involving different combinations of triangular obstacles in various heights and intervals and ISW of different
amplitudes were performed. The wave features resulting from the interaction of an ISW and double obstacles were found to differ
from those of single obstacle. The incident energy of an ISW was either reflecting back from the obstacles, dissipated through
turbulent mixing, or transmitted over the double obstacles. Reduction in wave energy increased as the intervals between obstacles
reduced. For two obstacles in different heights, energy dissipation was greater in the case with a higher obstacle ahead of
a lower one. However, the overall performance was dependent on the relative height of the obstacles, relative water depth
of the upper and bottom layer, in addition to the intervals between the obstacles. 相似文献
168.
Kaifeng Rao Li Tang Xin Zhang Heyu Xiang Liang Tang Yong Liu Wei Wang Jie Jiang Mei M Yiping Xu Zijian Wang 《环境科学学报(英文版)》2021,33(12):150-159
Environmental impact of pollutants can be analyzed effectively by acquiring fish behavioral signals in water with biological behavior sensors. However, a variety of factors, such as the complexity of biological organisms themselves, the device error and the environmental noise, may compromise the accuracy and timeliness of model predictions. The current methods lack prior knowledge about the fish behavioral signals corresponding to characteristic pollutants, and in the event of a pollutant invasion, the fish behavioral signals are poorly discriminated. Therefore, we propose a novel method based on Bayesian sequential, which utilizes multi-channel prior knowledge to calculate the outlier sequence based on wavelet feature followed by calculating the anomaly probability of observed values. Furthermore, the relationship between the anomaly probability and toxicity is analyzed in order to achieve forewarning effectively. At last, our algorithm for fish toxicity detection is verified by integrating the data on laboratory acceptance of characteristic pollutants. The results show that only one false positive occurred in the six experiments, the present algorithm is effective in suppressing false positives and negatives, which increases the reliability of toxicity detections, and thereby has certain applicability and universality in engineering applications. 相似文献
169.
通过建立缩小比例为25:1的双ZBS2型酒杯塔输电线路模型,对其进行长间隙放电,研究了塔头、避雷线保护角、地面倾斜度等因素对雷击绕击率的影响。结果表明:杆塔对雷电先导具有吸引作用,雷击杆塔附近时,线路绕击率较低,从杆塔到档距中央,绕击率呈现一种先增大后减小的趋势;随着避雷线保护角由正到负变化,绕击概率随之降低;线路绕击概率随地面倾斜角增大,而呈现先增大后减小的趋势。本研究结果可指导企业输配电线路的雷电防护工作,为线路绕击防护装置的研发提供数据支持。 相似文献
170.
目的 研究太赫兹波斜入射均匀非磁化等离子体中的传输特性。方法 根据分层介质中的电磁波传播理论,给出了等离子中太赫兹波的功率反射和透射系数,分析了太赫兹波频率、入射角、等离子体的碰撞频率和电子密度对太赫兹波传输特性的影响。结果 垂直入射时,模型结果与已有文献结果一致;斜入射时,入射角度增大,反射系数增大,透射系数变小。太赫兹波频率增大,反射系数减小,透射系数起初快速增大,而后变得平缓。等离子体的电子密度增大,透射系数减小,碰撞吸收增大,太赫兹波衰减增大。结论 入射角变大,反射率增大。太赫兹波频率较低时,入射角对透射率影响明显。 相似文献