风浪周期分布与谱宽度的关系

本文通过分析实验室风浪周期分布,发现风浪周期累积概率分布曲线低于Longuet-Higgins理论结果,在小概率周期区域实验结果与理论结果的差异明显。对实验结果进一步分析发现,在谱不是很窄时,在小概率处风浪周期累积概率随谱宽度的增大而降低,这与窄谱假定下的理论结果相反,Longuet-Higgins理论结果在小概率处不便于描述周期分布随谱宽度的变化。根据实验结果提出风浪周期的Weibull分布经验公式,Weibull分布中的参数依赖于谱宽度。     

A Study on the Spectral Form of Nearshore Water Waves

- The spectral form of wind waves is investigated based on the ocean wave data observed at three nearshore stations of Taiwan. In this study, the generalized forms of Pierson-Moskowitz spectrum and JONSWAP spectrum are used to describe the local wave spectrum by selecting suitable spectral form parameters. It is shown that, at a specific site, the similarity of wave spectral form exists. Thus it is possible to use a representative spectral form for a given nearshore region to describe the wave spectrum at this nearshore. On the other hand, the effects of relative water depth on spectral form are examined. The feasibility of two spectral models in finite water depth is evaluated by using the same field wave data.     

应用电性特征研究银川平原地下水水质空间分布规律

以蕴涵丰富地下水系统水循环信息的电性特征为线索,采用电测深法,在分析研究银川平原450 m深度内地下水系统的空间结构的基础上,对平原地下水水质空间分布规律进行了综合研究,为银川平原地下水资源可持续利用战略的制订提供了依据。     

直流电测深法与中心回线瞬变电磁法联合反演

分析了直流电测深法(VES)与中心回线瞬变电磁法(TEM)对地层的响应特征,结果显示:TEM对低阻层反应灵敏,而VES对高阻层具有较高的分辨能力。基于TEM与VES对地层响应特征互补的特点,尝试将TEM与VES数据进行联合反演,模型试算结果表明,联合反演的效果明显比单一方法反演的效果好。     

渤海GNSS-R机载测风试验及其反演结果

对渤海GNSS-R机载试验进行了海面风场反演.结果表明,风速精度优于1 m/s,风向精度优于20°.     

华北地台地热勘探中利用大地电磁测深法(MT)圈定热田范围和探讨地热形成机制

利用大地电磁测深法（MT）反映地质体的电性差异,首先可以确定地质体的空间展布、地质结构和构连;而由于地质体电阻率受地热水影响而降低,进而据此圈定地热水的分布范围;并在此基础上可以进一步探讨地热形成机制。在华北地台地热勘探中MT法取得了较好的勘探效果。     

The origin of accretionary lapilli

Experimental investigations in a recirculating wind tunnel of the mechanisms of formation of accretionary lapilli have demonstrated that growth is controlled by collision of liquid-coated particles, due to differences in fall velocities, and binding as a result of surface tension forces and secondary mineral growth. The liquids present on particle surfaces in eruption plumes are acid solutions stable at 100% relative humidity, from which secondary minerals, e.g. calcium sulphate and sodium chloride, precipitate prior to impact of accretionary lapilli with the ground. Concentric grain-size zones within accretionary lapilli build up due to differences in the supply of particular particle sizes during aggregate growth. Accretionary lapilli do not evolve by scavenging of particles by liquid drops followed by evaporation — a process which, in wind tunnel experiments, generates horizontally layered hemispherical aggregates. Size analysis of particles in the wind tunnel air stream and particles adhering to growing aggregates demonstrate that the aggregation coefficient is highly grain-size dependent. Theoretical simulation of accretionary lapilli growth in eruption plumes predicts maximum sizes in the range 0.7–20 mm for ash cloud thicknesses of 0.5–10 km respectively.     

The upper mantle structure of the yakutian kimberlite province,eastern Russia

Deep seismic sounding in the region of the Mirnyi kimberlite field indicates that the boundary velocity of the uppermost mantle is elevated (v _b=8.6–8.8 km/sec) and extremely variable near the Mir kimberlite pipe. These velocity heterogeneities are probably associated with the kimberlite magmatism and may be useful in the identification of other kimberlite fields.     

Structure and energy transfer of unstable hot star winds

Due to the instability of the radiation line force, the winds of hot, luminous stars should show a pronounced time-dependence resulting from the nonlinear growth of initially small perturbations. Following the method of Owocki, Castor & Rybicki (1988), we describe the time-dependent wind structure obtained with an independently developed code. Under the central assumption ofisothermality, our results are in very good agreement with the ones by Owocki et al. We find that the response of the wind to periodic base perturbations remains largely periodic, at least up tor 2...3R _* , with no clear evidence of stochastic behaviour.In order to test the foregoing assumption of isothermality and to compute the X-ray emission from models of structured winds, we have also incorporated theenergy equation into our simulations. We encountered the numerical problem that all radiative cooling zones collapse because of the oscillatory thermal instability (cf. Langer et al. 1981). We present a method to hinder this collapse by changing the cooling function at low temperatures. The resulting wind showsresolved cooling zones; but, for a supergiant wind relatively close to the star (r 10R _* ), the macroscopic wind structure is very similar to isothermal calculations. Most of the hot material is caused by shell-shell collisions.     

新疆地区夏季平流层低层风场特征分析及数值模拟

利用2017年6—8月的FNL再分析资料分析了新疆地区夏季平流层低层风场的时空演变特征，开展了平流层低层风场的高分辨率数值模拟和检验。结果表明：新疆地区夏季平流层纬向风随时间的变化存在经向差异，同时准零风层开始和结束的时间也存在经向差异，准零风层开始时间南部地区早于北部地区，而准零风层结束时间则相反。整个夏季新疆地区上空的准零风层处于70～40 hPa之间，其高度随时间呈先降低而后升高的变化趋势。准零风层数值模拟结果表明，模拟的准零风层参数与探空资料分析结果相比二者存在一致的变化趋势，准零风层起始高度的平均绝对误差为467 m，该高度对应的风速均方根误差为1.75 m/s。