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1.
马永平 《山东理工大学学报(社会科学版)》2002,18(6):26-31
对于公共管理,管制是重要的管理手段。文章用经济学的观点阐述管制政策的效率原理,并在此基础上分析我国土地利用管制政策的效率,最后提出我国管制政策改进的建议和实施的条件。 相似文献
2.
工业的发展在带给人类福音的同时 ,也给江河湖泊、地下水源及海洋造成了污染 ,并对人类的生存与发展构成了严重威胁 相似文献
3.
孙克成 《华北水利水电学院学报(社会科学版)》2002,18(2):102-103
用数学量化的方法 ,分析处理有关数据 ,建构模型。利用模型指导教师在跳远教学中如何处理素质与技术的关系 ,从而使跳远教学具有较科学、量化的评价体系和理论依据。 相似文献
4.
Diane Hope Weixing Zhu Corinna Gries Jacob Oleson Jason Kaye Nancy B. Grimm Lawrence A. Baker 《Urban Ecosystems》2005,8(3-4):251-273
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding
desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well
as for the desert and urban sites separately. Concentrations of both NO3-N and NH4-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO3-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious
surfaces and lawn, whereas soil NH4-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO3-N and NH4-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation
of soil NO3-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic
soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than
factors related to an urban-rural gradient. 相似文献
5.
韩立军 《内蒙古工业大学学报》2002,21(1):50-52
本文给出一类非均匀弦的横向振动的最佳控制,推广了P C Park的结果。这一结果同样适用于同类型振动问题。 相似文献
6.
烹调油烟的免疫毒理学研究进展 总被引:2,自引:0,他引:2
张建华 《绍兴文理学院学报》2003,23(7):75-77
烹调油烟是室内主要空气污染物之一,化学成分复杂,严重影响职业接触人群的健康.对烹调油烟免疫毒性的研究是全面评价其毒性作用的一个重要方面.对近几年来烹调油烟影响机体细胞免疫、体液免疫和巨噬细胞以及NK细胞功能等免疫毒性方面的研究进展作一综述. 相似文献
7.
分析了影响数控火焰切割机加工精度的主要因素,利用开放式数控系统的软件开放性,提出了采用IGCAQBP学习算法的神经网络方法来对包括金属热变形、机械传动误差等非线性因素在内的多种因素造成的加工误差进行误差补偿,设计了嵌入开放式数控系统中的神经网络误差补偿器,给出了实用的补偿器使用方法,并对误差补偿功能进行了扩展,仿真结果和实际应用表明该方法稳定有效。 相似文献
8.
Owing to the extreme quantiles involved, standard control charts are very sensitive to the effects of parameter estimation and non-normality. More general parametric charts have been devised to deal with the latter complication and corrections have been derived to compensate for the estimation step, both under normal and parametric models. The resulting procedures offer a satisfactory solution over a broad range of underlying distributions. However, situations do occur where even such a large model is inadequate and nothing remains but to consider non- parametric charts. In principle, these form ideal solutions, but the problem is that huge sample sizes are required for the estimation step. Otherwise the resulting stochastic error is so large that the chart is very unstable, a disadvantage that seems to outweigh the advantage of avoiding the model error from the parametric case. Here we analyse under what conditions non-parametric charts actually become feasible alternatives for their parametric counterparts. In particular, corrected versions are suggested for which a possible change point is reached at sample sizes that are markedly less huge (but still larger than the customary range). These corrections serve to control the behaviour during in-control (markedly wrong outcomes of the estimates only occur sufficiently rarely). The price for this protection will clearly be some loss of detection power during out-of-control. A change point comes in view as soon as this loss can be made sufficiently small. 相似文献
9.
李如春 《河北理工大学学报(社会科学版)》2003,3(3):83-84
论述投资控制的关键环节,提出投资控制工作的实施要点,阐明投资控制工作的必要性、可行性和重大意义. 相似文献
10.
Angelo Zanella 《Statistical Methods and Applications》1992,1(1):143-160
Summary For technological applications it can be useful to identify some simple physical mechanisms, which, on the basis of the available
knowledge of the production process, may suggest the most appropriate approach to statistical control of the random quantities
of interest. For this purpose the notion of rupture point is introduced firstly. A rupture point is characterized bym randomly arising out of control states, assumed to be mutually exclusive and stochastically independent. Shewhart's control
charts seem to represent the natural statistical tool for controlling a rupture point; however it is shown that they are fully
justified only when the hazard rates attached to the causes of failure are constant. Otherwise, typically in the presence
of time increasing hazard rates, Shewhart's control charts should be completed by a preventive intervention rule (preventive
maintenance). In the second place, the notion of dynamic instability point is introduced, which is specifically characterized
by assuming that the random quantity of interest is ruled by a stochastic differential equation with constant coefficients.
By discretization, developed according to a possibly new approach, it is shown that the former model reduces to an equation
error model, which is among the simplest used in adaptive control, and thus particularly easy to deal with in regard to parameter
estimation and the definition of the optimum control rule. 相似文献