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941.
从城市区划、地震安评和城市建设的监管机制等几个方面讨论市建筑物抗震设防工作中存在的问题及相应对策。 相似文献
942.
Soil quality and sustainable land use in urban-rural marginal area: a case study of Kaifeng 总被引:1,自引:0,他引:1
Soil quality is closely related to the sustainability of environment and development[1], hence people have paid more and more attention to soil quality research in recent years, and have made a thorough inquiry of the definition of soil quality as well as the method and theory of its expression[2-4]. As a zone devoting to most intensive modern agricultural land use, urban-rural marginal area has become a region where intensity of soil quality change is most remarkable. Moreover, with the devel… 相似文献
943.
本文在组合模式和立交模式的基础上提出了预报中、强地震的动态空区法,应用该法对我国大震进行了回顾性检验。结果表明,这一方法比单空区确定地震危险区有重要改进。文中还讨论了由动态空区出现的频次增多、地震共轭条带以及中小地震活动性加剧等判定震源断层的致锁和解锁时间,由此预测未来主震的震级和发震时间。 相似文献
944.
本文列出CT检查与X线摄影的成像原理,及各自优缺点,提示临床正确应用CT检查与X线摄影,使得诊断更加正确有效,并节省患者的的检查费。 相似文献
945.
Orographic effects on monthly-and seasonal-scale low frequency oscillation are investiged in terms of a five-level global spectral model with a triangle truncation at wavenumber 10 that contains relatively full physical parameterization, followed by analysis and comparison of the lowpass filtered data separately obtained from models with and without orography. Results show that remarkable seasonal characteristics are displayed in the orographic forcing-generated low frequency wavetrain on monthly and seasonal scales. It is found that the Northern Hemisphere summer orography-produced tropical heating acts as source of the low-frequency wavetrain for both hemispheres. Besides, the simulations indicate that the orographic wavetrain perturbation can give rise to the anomaly in the equatorial zonal flow, whose transient forcing will cause a new wavetrain in the Southern Hemisphere, thus completing the cross-equatorial propagation of the northern wave in interhemispheric action. 相似文献
946.
Given time-independent monthly mean sea temperature,numerical simulation was done of the path of the tropicalcy clone Forrest and its related physical quantity field in terms of the improved version of the σ-coordinate 10-level primitive equation model for tropical cyclones developed by the Guangzhou Institute of Marine Meteorology.Result ssuggest the similarity between the simulated and observed physical quantity fields except that the simulated path was to the right of the observed,with the deviation increasing with time.Sea and tropical cyclone,in effect,interact mutually.In an attempt to compare the results from coupling and uncoupling experiments,an oceanic mixed layer model was formulated based on experiments with sea response to cyclone and integrated in synchronous coupling with the aforementioned version of tropical cyclones,the computational domain covering the western North Pacific with the coastal configuration involved.The coupling experiment shows that the negative feedback of the interaction between sea and mature cyclone leads to weaker sea response as compared to the uncoupling case.Except for the location of the divergence core of oceanic current,the mixed layer depth and inhomogeneous distribution of sea surface temperature (SST) caused by the cyclone-core position and intensity,the values of the maximum oceanic current,departure of the mixed layer depth and SST drop were smaller in the coupling than in the uncoupling case,and so was the maximum wind near the cyclone core.The path from the coupling run is to the left of the course in the uncoupling experiment but closer to the observed one though remaining somewhat leftward.Even on a scale of less than 3 days,the effects of sea and sea-cyclone interaction on the cyclone were by no means negli-gible. 相似文献
947.
Analysis has been implemented of 1970-1992 tropical Pacific wind stress anomaly and sea surface temperature anomaly (SSTA) datasets, indicating that quasi-biennial oscillation (QBO) of the tropical Pacific WS and SSTA is featured both by a standing and a progressive form, the former emerging in the most intense centers of action and the latter travelling east- or west-ward out of the SSTA sources. Results show that the SSTA is in the warm (cold) phase as zonal component of euqatorial wind stress anomaly gets weakened (reinforced) and the QBO of wind stress anomaly is well related to the El Nino cycle. 相似文献
948.
Qin Wenhan 《Acta Meteorologica Sinica》1995,9(1):78-86
Using data on leaf area density and wind profiles above and within canopies of wheat,rice,soybean and corn,thecenter-of-pressure method (CPM),originally proposed by Thom (1971),is first validated in the field.Aphysically-based model for directly calculating zero-displacement height (d) is derived.The comparison between thefriction velocity (u_*) estimated with CPM and that with eddy correlation technique shows that CPM not only works wellin the field,but also produces more steady and accurate estimates of aerodynamic parameters (which are hardly affectedby atmospheric thermal stability),than those with the widely-used log-profile fitting method in diabatic atmosphere.The results presented in this paper also demonstrate that the ratios of d,z_0 to crop height h usually vary with canopy ar-chitecture,atmospheric stratification and turbulent exchange intensity,and are not just constants as commonly assumedor used.d/h raises with an increase of relative height of the maximum foliage layer and wind extinction coefficientwithin the canopy.Only for crops with short stem and moderate foliage density,can the relations d= 0.64h,z_0=0.08hkeep stable.In addition,for long stem crops or sparse canopies,the fairly large shear stress at the soil surface and the va-riation of the exponent in the relationship between drag coefficient and wind speed undoubtedly influence the accuracyof CPM to a certain extent. 相似文献
949.
NUMERICAL STUDY ON THE INTERANNUAL OSCILLATION OF SEA SURFACE TEMPERATURE IN THE SOUTH CHINA SEA 总被引:5,自引:0,他引:5
A two and a half layer oceanic model of wind-driven, thermodynamical general circulation is appliedto study the interannual oscillation of sea surface temperature (SST) in the South China Sea (SCS). Themodel consists of two active layers: the upper mixed layer (UML) and the seasonal thermocline, with themotionless abyss beneath them. The governing equations which include momentum, continuity and sea.temperature for each active layer, can describe the physics of Boussinseq approximation, reduced gravityand equatorial β-plane. The formulas for the heat flux at the surface and at the interface between twoactive layers are designed on the Haney scheme. The entrainment and detrainment at the bottom of theUML induces vertical transport of mass,momentum and heat, and couples of dynamic andthermodynamic effect.Using leap-frog integrating scheme and the Arakawa-C grid the model is forced bya time-dependent wind anomaly stress pattern obtained from category analysis of COADS. The numerical results indicate that t 相似文献
950.