OPTIMIZATION OF WEIGHTED HIGH-RESOLUTION RANGE PROFILE FOR RADAR TARGET RECOGNITION

For the recognition of high-resolution range profile （HRRP） in radar, the weighted HRRP can reduce the instability of range cells caused by the attitude change of targets. A novel approach is proposed to optimize the weighted HRRP. In the approach, the separability of weighted HRRPs in different targets is measured by de- signing an objective function, and the weighted coefficients are computed by using the gradient descent method, thus enhancing the influence of stable range cells. Simulation results based on five aircraft models show that the approach can effectively optimize the weighted HRRP and improve the recognition accuracy.

Schemes for synthesizing high-resolution range profile with extended OFDM-MIMO

Two novel schemes are proposed to synthesize high resolution range profile (HRRP) based on co-located multiple-input multiple-output (MIMO) system in the context of the joint radar and communication system. The difference between two schemes is the pattern of selecting pulses, which depends on the demand for the velocity information. The system, a type of frequency diverse array (FDA), takes full advantage of the phase-coded orthogonal frequency division multiplexing (OFDM) signal. Furthermore, the complete discrete form of the phase-coded OFDM echoes is utilized to derive the HRRP processing. The velocity estimation in the second scheme aims to eliminate velocity ambiguity, and high velocity can be retrieved exactly. Meanwhile, the imaging method is investigated with random frequency coding applied to an array. The desired performance of resolving velocity ambiguity and suppressing noise is shown by means of comparisons with previous work. The advantages in the radar imaging and the significance of the work are concluded in the end.

High-Resolution Sequence Stratigraphy of Shallow Lacustrine Delta Front: The Second Member of Sangonghe Formation, Central Junggar Basin

Shallow lacustrine delta front （SLDF） comprises mainly sheetlike subaqueous distributary channels （SDC） formed in shallow, gentle, and tectonically steady slope （Cai and Zhu, 2011）. SDC proves an important hydrocarbon reservoir type in the Daqing oilfield, Changqing oilfield, and the newly discovered Moxizhuang oilfield in Central Junggar Basin. However, SDC tends to prograde quickly and move laterally frequently,

High-resolution central difference scheme for the shallow water equations

A two-dimensional nonoscillatory central difference scheme was extended to the shallow water equations. A high-resolution numerical method for solving the shallow water equations was presented. In order to prevent oscillation, the nonlinear limiter is employed to approximate the discrete slopes. The main advantage of the presented method is simplicity comparable with the upwind schemes. This method does not require Riemann solvers or some form of flux difference splitting methods. Furthermore, the discrete derivatives of flux can be approximated by the component-wise approach and thus the computation of Jacobian can be avoided. The method retains high resolution and high accuracy similar to the upwind results. It is applied to simulating several tests, including circular dam-break problem, shock focusing problem and partial dam-break problem. The results are in good agreement with the numerical results obtained by other methods. The simulated results also demonstrate that the presented method is stable and efficient.

Study on Anti-Disturbance and High-Resolution Shallow Seismic Exploration of Active Faults in Urban Regions

The significance of detection of urban active faults and the general situation concerning detection of urban active faults in the world are briefly introduced. In a brief description of the basic principles of anti-disturbance and high-resolution shallow seismic exploration, the stress is put on the excitation of seismic sources, the performance of digital seismographs, receiving mode and conditions, geometry as well as data acquisition, processing and interpretation in the anti-disturbance and high-resolution shallow seismic exploration of urban active faults. The study indicates that a controlled seismic source with a linear or nonlinear frequency-conversion scanning function and the relevant seismographs must be used in data acquisition, as well as working methods for small group interval, small offset, multi-channel receiving, short-array and high-frequency detectors for receiving are used. Attention should be paid to the application of techniques for static correction of refraction, noise suppressing, high-precision analysis of velocity, wavelet compressing, zero-phasing of wavelet and pre-stacking migration to data processing and interpretation. Finally, some cases of anti-disturbance and high-resolution shallow seismic exploration of urban active faults are present in the paper.

High-resolution crustal velocity imaging using ambient noise recordings from a high-density seismic array:An example from the Shangrao section of the Xinjiang basin,China

A profile of shallow crustal velocity structure(1–2 km) may greatly enhance interpretation of the sedimentary environment and shallow tectonic deformation.Recent advances in surface wave tomography, using ambient noise data recorded with high-density seismic arrays, have improved the understanding of regional crustal structure. As the interest in detailed shallow crustal structure imaging has increased, dense seismic array methods have become increasingly efficient. This study used a high-density seismic array deployed in the Xinjiang basin in southeastern China, to record seismic data, which was then processed with the ambient noise tomography method. The high-density seismic array contained 203 short-period seismometers, spaced at short intervals(～ 400 m). The array collected continuous records of ambient noise for 32 days. Data preprocessing,cross correlation calculation, and Rayleigh surface wave phase-velocity dispersion curve extraction, yielded more than 16,000 Rayleigh surface wave phase-velocity dispersion curves, which were then analyzed using the direct-inversion method. Checkerboard tests indicate that the shear wave velocity is recovered in the study area, at depths of 0–1.4 km,with a lateral image resolution of ～ 400 m. Model test results show that the seismic array effectively images a 50 m thick slab at a depth of 0–300 m, a 150 m thick anomalous body at a depth of 300–600 m, and a 400 m thick anomalous body at a depth of 0.6–1.4 km. The shear wave velocity profile reveals features very similar to those detected by a deep seismic reflection profile across the study area. This demonstrates that analysis of shallow crustal velocity structure provides high-resolution imaging of crustal features.Thus, ambient noise tomography with a high-density seismic array may play an important role in imaging shallow crustal structure.

A Computational Model for Velocity Separation in Shallow Sea

Based on the hydrodynamical feature and the theoretical velocity profiles of tidal flow and wind-induced flow in shallow sea, a computational model is established for the first time, which can separate observed velocity into tidal velocity and wind-induced velocity by use of the least square method. With the model, not only the surface. velocities of tidal. flow and wind-induced flow are obtained, but also the bed roughness height is determined and the wind velocity above the water surface is estimated. For verification of the model, the observed velocity in the Yellow River Estuary and the laboratory test is separated, then it is applied to the Yangtze River Estuary. All the results are satisfactory. The research results show that the model is simple in method, feasible in process and reasonable in result. The model is a valid approach to analysis and computation of field data, and can be applied to separate the observed velocity in shallow sea; at the same time, reasonable boundary conditions of the surface and bottom can be obtained for two- and three-dimensional numerical simulation.

Robust Source Localization in Shallow Water Based on Vector Optimization

Owing to the multipath effect, the source localization in shallow water has been an area of active interest. However, most methods for source localization in shallow water are sensitive to the assumed model of the underwater environment and have poor robustness against the underwater channel uncertainty, which limit their further application in practical engineering. In this paper, a new method of source localization in shallow water, based on vector optimization concept, is described, which is highly robust against environmental factors affecting the localization, such as the channel depth, the bottom reflection coefficients, and so on. Through constructing the uncertainty set of the source vector errors and extracting the multi-path sound rays from the sea surface and bottom, the proposed method can accurately localize one or more sources in shallow water dominated by multipath propagation. It turns out that the natural formulation of our approach involves minimization of two quadratic functions subject to infinitely many nonconvex quadratic constraints. It shows that this problem （originally intractable） can be reformulated in a convex form as the so-called second-order cone program （SOCP） and solved efficiently by using the well-established interior point method, such as the sottware tool, SeDuMi. Computer simulations show better performance of the proposed method as compared with existing algorithms and establish a theoretical foundation for the practical engineering application.

Transformation of Nonlinear Surface Gravity Waves under Shallow-Water Conditions

This article describes transformation of nonlinear surface gravity waves under shallow-water conditions with the aid of the suggested semigraphical method. There are given profiles of surface gravity waves on the crests steepening stages, their leading edges steepening. There are discussed the spectral component influence on the transformation of surface wave profile.

Numerical Simulation of Nonlinear Surface Gravity Waves Transformation under Shallow-Water Conditions

This work considers the problems of numerical simulation of non-linear surface gravity waves transformation under shallow bay conditions. The discrete model is built from non-linear shallow-water equations. Are resulted boundary and initial conditions. The method of splitting into physical processes receives system from three equations. Then we define the approximation order and investigate stability conditions of the discrete model. The sweep method was used to calculate the system of equations. This work presents surface gravity wave profiles for different propagation phases.

邯东断裂浅部特征及第四纪活动性分析

邯东断裂为太行山山前断裂以东的一条隐伏断裂,是华北平原坳陷区内邯郸凹陷的东界断裂,位于邯郸东部新区规划建设范围内。研究其空间分布特征和活动性对于地震危险性评价及城区重大工程项目选址具有重要意义。本文采用浅层地震勘探、钻孔联合剖面探测和年代学测试方法,对邯东断裂的展布特征及第四纪活动性进行系统研究,共布设跨断裂浅层地震勘探测线6条、钻孔联合地质剖面3条。综合分析表明,邯东断裂为一条近NNE-SSE走向的高角度正断层,倾向W,视倾角约50°~75°。断裂上断点埋深南浅北深,最新活动时代为中更新世晚期。中更新世早期,南段与北段相比较为活跃。

华北平原中南部聊城-兰考断裂的第四纪晚期活动性探测——兼论1937年菏泽7.0级地震发震机制

华北平原是中国人口最多、经济最为发达的地区之一,也是受地震灾害影响最为严重的地区之一。对于该地区断裂活动性和大地震发震机制的研究有利于探索板内地震的发震规律、减轻地震灾害所造成的损失。聊城-兰考断裂是华北平原中南部一条重要的隐伏深大断裂。结合浅层地震勘探、钻孔勘探和第四纪测年方法,对聊城-兰考断裂的活动性进行了精细的研究。坝城寺钻孔揭示聊城-兰考断裂南段错断了全新统底界,为全新世早期活动断裂,揭露出该断裂晚更新世以来造成了4次古地震事件,单次事件的垂直位错为1.2±0.2~3.7±0.2 m。根据钻孔揭示的地层落差计算出该断裂晚更新世早期的平均垂直滑动速率约为0.1±0.05 mm/a,晚更新世晚期—全新世中期的平均滑动速率为0.35±0.04 mm/a。根据1937年菏泽7.0级和6(3/4)级地震的等震线和地表破裂分布特征认为,小留-解元集断裂和东明-成武断裂为该地震的发震断裂;聊城-兰考断裂对于该地区应力的积累、地震的发生具有很好的控制和约束作用,为区域控震构造。

基于浅地层剖面的台湾海峡西侧灾害地质识别

随着海洋经济建设的高速发展,特别是沿海建筑、桥梁、风电场等重大工程建设,降低海域灾害地质的风险迫在眉睫。通过以福建省地震风险普查专项在台湾海峡采集的最新高分辨率浅地层剖面数据为依据,结合研究区的历史资料和灾害地质概况,识别了浅层气、麻坑、古河道、潮流沙脊等潜在灾害地质因素,以此绘制了灾害地质平面分布图,同时探讨了在浅地层剖面中识别活动断层的可能性。结果表明:研究区北部的灾害地质因素主要是广泛分布的浅层气,中部主要是活动断层和埋藏古河道,南部主要是分布较广的潮流沙脊活动和频度较高的地震活动。

Ship recognition based on HRRP via multi-scale sparse preserving method

In order to extract the richer feature information of ship targets from sea clutter, and address the high dimensional data problem, a method termed as multi-scale fusion kernel sparse preserving projection(MSFKSPP) based on the maximum margin criterion(MMC) is proposed for recognizing the class of ship targets utilizing the high-resolution range profile(HRRP). Multi-scale fusion is introduced to capture the local and detailed information in small-scale features, and the global and contour information in large-scale features, offering help to extract the edge information from sea clutter and further improving the target recognition accuracy. The proposed method can maximally preserve the multi-scale fusion sparse of data and maximize the class separability in the reduced dimensionality by reproducing kernel Hilbert space. Experimental results on the measured radar data show that the proposed method can effectively extract the features of ship target from sea clutter, further reduce the feature dimensionality, and improve target recognition performance.

浅层地震勘探与钻孔探测揭示的安宁河东支断裂特征

已有资料证实安宁河东支断裂为一条隐伏断裂,为探明其位置、分析其活动性,跨断裂完成了两条高分辫率的浅层勘探剖面。在浅层地震勘探成果的基础上,于断裂两侧各布设了一个钻孔。根据浅层地震、钻孔并结合该区域地质资料,对该断裂的位置、活动性等开展了分析和讨论。结果显示,安宁河东支断裂为走向NNE-SN,倾向E的逆断层,错断埋深约38~42 m的第四系沉积层,为一条具晚更新世活动性的隐伏活动断裂,初步估算其晚更新世滑动速率为0.17 mm/a。

海洋物探方法在海上风电场勘察中的应用研究

在海上风电场建设项目中,需要通过勘察活动掌握海底的地层特点以及各种影响施工活动的不利因素。研究过程采用海洋物探法进行海底勘察,经过对比,选用浅地层剖面探测技术。结合具体的工程项目,沿着东西方向和南北方向,布置间距相同的平行测线,将探测系统部署在船舶上,收集海底的回波信号,利用配套软件工具处理相关数据。结果显示,拟建区域基岩面整体埋深较浅,起伏程度较小,并且海底未发现浅层气、油气管线、输电线缆,仅有一条埋藏古河道。以上情况表明,该区域能够为施工活动提供良好的作业条件。

海上风电场地理信息综合服务关键技术

海上风电作为清洁能源,进行大力开发建设。地理信息在海上风电场建设运维、船舶航行安全方面发挥重要作用,也是海事通航尺度核定测量重要内容。海上风电场地理信息综合服务包含侧扫声呐探测、浅地层剖面探测、多波束水深测量及二三维一体化展示等关键技术。本文以粤东某风电场为例,进行了沉船扫海测量、风机基底探测、礁石浅点探测、电缆数据采集及风电场海域相关要素二三维一体化展示。结果表明,风电场地理信息数据需要结合浅地层剖面仪、侧扫声呐和多波束影像综合分析,提高数据的互补性和可靠性;基于潮汐模型与余水位监控法、海量多波束处理CUBE算法具有应用价值,磁法测量、下潜探摸和水下摄像判读可获取沉船更详细的信息。

银川断陷盆地地壳结构与构造的地震学证据

通过跨银川断陷盆地,完成了一条长68.9 km的高分辨深地震反射探测剖面,首次获得了银川盆地地壳精细结构、地堑型断陷盆地深部断裂系(黄河断裂、银川断裂、贺兰山东麓断裂)特征及深浅构造关系.结果表明:银川断陷盆地上地壳为双程走时8 s(深度约20km)反射面以上的区域,上地壳上部地层层位丰富,地层分段连续性较好,上地壳下部地层分层特征不明显,地质构造简单;下地壳(8～13 s)反射能量较弱,反射同相轴不明显;下地壳下部壳幔过渡带(13 s附近)由一组能量较强、持续时间较长(1.5 s)的反射波组组成,厚度约4.5 km.芦花台断裂、银川断裂分别于12～12.5 km、18～19 km深处交汇于贺兰山东麓断裂,贺兰山东麓断裂于28～29 km深处交汇于黄河断裂,黄河断裂为错断Moho面的深大断裂,银川地堑为以黄河断裂为主,其他断裂为辅组合而成的负花状构造.根据贺兰山东麓断裂和银川断裂的相互关系,认为贺兰山东麓断裂对1739年平罗银川8级地震起主要控制作用.

南海东北部陆坡冷泉系统的浅地层剖面特征与分析

本文通过对南海东北部陆坡区浅地层剖面资料的处理,结合横跨陆坡区的长地震测线,总结了该区浅层气聚集、海底流体运移、泥火山和冷泉活动在浅地层剖面中的特征,并对剖面中出现的声学空白带现象做了分类.研究认为浊反射、增强反射等现象,反映了该区域存在广泛的浅层气聚集.对声学空白带成因的分析,认为窄空白带很可能对应海底流体运移的通道,而宽空白带则可能由沿地层分布的浅层气引起,同时提出了自生碳酸盐岩体散落分布造成声学空白的可能性.我们在南海东北部陆坡区发现了泥火山,并讨论了其运移通道及对BSR的破坏.同时发现研究区水体中存在声学异常体,推断为冷泉羽状流,指示该区存在活动的冷泉.本文依托大量的浅地层剖面数据,对南海东北部陆坡区的冷泉系统有了较全面的认识,对冷泉系统剖面特征的成因进行了初步探讨,可为南海冷泉系统研究的进一步开展提供有益参考.

渤海海峡及周边海域浅地层结构及地层声速的拾取

通过系统分析渤海海峡及周边海域的高分辨率浅地层剖面与3口钻孔的资料,将研究区地层自上而下划分为T0、T1、T2、T3、T4、T5、T6、T7、T8共9个反射界面及SU11、SU12、SU13、SU2、SU3、SU41、SU42、SU43、SU5共9个声学地层单元,SU1地层单元对应全新世海相沉积,其底界为一海进侵蚀面,削蚀对应晚更新世晚玉木冰期陆相沉积的SU2地层单元。SU3地层单元对应晚更新世晚玉木间冰期的海相沉积,通过侵蚀间断面与上覆SU2呈不整合接触。SU41地层单元对应晚更新世早玉木冰期晚期的陆相沉积,SU42地层单元对应晚更新世早玉木亚间冰期的海相沉积,与上覆SU41呈侵蚀不整合接触,SU43地层单元对应晚更新世早玉木冰期早期的陆相沉积,其顶界面为海进侵蚀面,与下伏地层呈不整合接触,SU5对应晚更新世玉木—里斯间冰期的海相沉积。对比分析浅地层剖面地层单元与钻孔沉积地层,确定了研究区海底面之下不同地层单元对应的平均声学速度,为后续的地层层序的研究奠定了基础。研究区"海侵-海退-海侵-海退-高水位"的沉积过程,决定了地层平均声速随深度自下而上呈现由高-低-高-低的变化模式。