A numerical investigation of a moderate coastal storm with intense precipitation

Abstract

In this study, the development of a moderate coastal storm with intense precipitation that occurred during 12–14 February 1993 is examined using a high‐resolution version of the Canadian Regional Finite‐element (RFE) model with more realistic physical representations. It is shown that the improved RFE model predicts well the coastal cyclogenesis events and also the distribution and intensity of heavy mixed precipitation (rain and snow) associated with the storm. It is found that the cyclogenesis takes place in response to the low‐level inshore advection of high‐θ_e air from the maritime boundary layer, and the approach of a mid‐level shortwave trough with a warm pool above that is previously associated with a decaying cyclone upstream. More rapid deepening of the cyclone ensues as intense precipitation falls along the warm and cold fronts near the cyclone centre.

Diagnosis of the control and sensitivity simulations reveals that the low‐level inshore warm advection and the propagation of the stratospheric warm pool contribute more significantly to the surface pressure falls during the incipient stage, whereas the mid‐level shortwave trough plays an important role in the cyclogenesis at later stages. Overall, latent heat release accounts for about 50% of the cyclone's total deepening, in agreement with the presence of a moderate baroclinic environment and the generation of intense precipitation.

The diabatic and kinematic structures near the rain‐snow boundary are examined to gain insight into the influence of melting snow on the cyclogenesis. It is shown that the improved RFE model reproduces well the rain‐snow boundary structures as previously observed. Moreover, a thermally indirect circulation (perturbation) can be seen in the vicinity of the rain‐snow boundary. It is found, however, that melting of snow tends to produce a weak negative or negligible impact on the cyclogenesis, as opposed to previous hypotheses.     

基于DTS组件数据的自动抽取

DTS组件是SQL Server提供的实现数据抽取和转换的工具，基于DTS组件，通过ODBC连接多种数据源，能够实现数据的自动抽取，并且提出了该方法的实现原理和部分基于C#的实现代码。     

太阳软X射线观测进展

太阳软x射线观测在太阳物理的研究中，特别在日冕结构、磁场和日冕等离子体活动等物理现象的研究中起着重要的作用。太阳软x射线观测主要有光谱和成像观测两种．随着观测技术、方法和内容的发展，太阳软x射线观测揭示了太阳物理的许多重要的科学现象，并在预报、监测空间天气变化，预警空间灾变天气等方面也有着重要的应用．     

Comparison of Kuqa foreland basin with Persian Gulf Basin in salt tectonics

Compared Kuqa foreland basin with Persian Gulf Basin in development of salt layers, salt tectonics, and the relation between salt tectonics and hydrocarbon, it is concluded that the salt diapirs are relative to hydrocarbon. Searching salt diapirs and related traps in Kuqa foreland basin is important. The forming mechanism of salt tectonic in Kuqa foreland basin is different from that of Hormuz Series, but similar to that of Lower Fars Series/Gachsaran Formation. Inspired by the role of salt tectonics of Lower Fars Series/Gachsaran Formation in hydrocarbon accumulation, the authors considered that the exploration below salt layer should be enforced, and the traps below salt layer in the southern part of the Kuqa foreland basin would be found where salt layer is thicker. On the contrary, the traps should be found both above and below the salt layer in front of the northern mountain where salt layer is thin. The Triassic and Jurassic source rocks are rich in this area with great exploration prospective.     

基于离散小波变换的数字水印技术

提出了一种基于小波分析的简单有效的数字水印嵌入和盲检测的算法。先将嵌入的水印信息加密，然后将加密后的水印信息嵌到相应DWT系数的有效嵌入位中，并使用适当的保真技术，减小图像因嵌入水印引起的失真。通过实验验证，该算法在对嵌入水印后的图像进行有损压缩、剪切、污染、添加各种噪声等处理后，提取出的水印仍表现出了较好的鲁棒性。     

A reconfigurable real-time interpolation beamformer

This paper describes an architecture for a compact real-time time-delay sonar beamformer. The design is based on a time-domain interpolation concept, and includes shading, interpolation, and time-delay functions for up to 64 sensor data inputs. A one card per beam configuration has been achieved. The digital interpolation technique used improves the effective sampling rate by a factor of 128. The beamformer design features 16-bit arithmetic precision, up to approximately a 5-kHz sampling rate for each of the 64 sensor input channels, and adaptability to any type of array, e.g., linear, circular, or arrays with nonequal interelement spacings. A 31-beam beamformer system, performing more than 620-million arithmetic operations a second, is discussed.     

GLONASS卫星位置的动力学改进算法

为了减弱由于广播星历拟合引起的误差,本文提出了一种基于动力学轨道改进的GLONASS卫星位置算法。该算法仅采用GLONASS广播星历信息就能够提高GLONASS卫星位置坐标的计算精度。算例表明,该方法能够有效减弱GLONASS卫星广播星历的拟合误差,卫星位置的精度损失从0.5m降到mm级;外推2-3h,精度损失也仅在cm级水平。     

一种结合UKF与TLS的GPS机动跟踪算法

在GPS接收机产生机动时,运动模型的不匹配会给跟踪算法带来性能损失。本文提出一种机动检测、Unscented Kalman Filter(UKF)以及总体最小二乘(Total Least Square,TLS)相结合的解算方法用于接收机机动的GPS跟踪解算。首先,通过机动检测算法对目标的机动性进行判别,当目标机动较小时,利用UKF的最优检测性能进行跟踪,而当目标机动较大时,结合TLS的强跟踪性能,采用TLS和UKF联合进行跟踪。从而,在不增加方程维数的情况下,实现机动目标的实时、快速跟踪。仿真结果表明该方法对机动目标具有良好的跟踪性能。     

Dim and Small Target Detection Based on Characteristic Spectrum

Dim and small target detection is one of the most challenging issues based on space-based detector. Original space-based detector only uses infrared bands, and the target information is limited in one-band image, so that detection error rate is high. In order to increase the target information, we suppose spectral imaging technology can be applied to the space-based detection system. Use bands of stronger radiation of targets than that of background as detection bands theoretically; the detection bands also can be called as the characteristic bands of targets. On these bases, the paper proposes methods of fuzzy fusion and fusion segmentation to achieve the target detection. Fusion is a combination of images from the characteristic bands, which can eliminate background, restrain noise, and enhance the target. Threshold segmentation and fuzzy algorithm assisted fusion algorithm to complete the final detection. In the simulation experiment, missile plume is considered as the detection target, atmosphere, cloud and jet plume is considered as the detection background, and the advantages of the characteristic spectrum detection and the proposed algorithm are verified from SNR, SCR, ROC curve, and time.     

星载激光光斑影像质心自动提取方法

激光光斑影像的质心提取是卫星激光测高数据处理中的重要环节,对于获得精确的激光指向角有重要的意义。本文总结了灰度重心法、高斯拟合法以及椭圆拟合法3种常用的质心提取方法,在比较其优缺点之后结合高斯曲面拟合法和椭圆拟合法,提出了一种基于高斯阈值的椭圆拟合方法,针对仿真数据进行试验,有较好的精度结果。采用GLAS（geoscience laser altimeter system）的实际激光光斑影像LPA（laser profile array）数据进行试验,发现LPA光斑质心位置变化周期约为1.5 h,幅度最大可达2~3个像素,对应激光指向角变化约9",说明在轨监视激光质心位置变化对于提高激光指向角测量精度非常必要。相关结论可为后续国产卫星激光测高仪足印影像处理提供参考。