Pulse-length-tolerant features and detectors for sector-scan sonar imagery

This paper presents a neural-network-based system to detect small man-made objects in sequences of sector-scan sonar images created using signals of various pulse lengths. The detection of such objects is considered out to ranges of 150 m by using an experimental sector-scan sonar system mounted on a vessel. The sonar system considered in this investigation has three modes of operation to create images over ranges of 200, 400, and 800 m from the vessel using acoustic pulses of a different duration for each mode. After an initial cleaning operation performed by compensating for the motion of the vessel, the imagery is segmented to extract objects for analysis. A set of 31 features extracted from each object is examined. These features consist of basic object size and contrast features, shape moment-based features, moment invariants, and features extracted from the second-order histogram of each object. Optimal sets of 15 features are then selected for each mode and over all modes using sequential forward selection (SFS) and sequential backward selection (SBS). These features are then used to train neural networks to detect man-made objects in each sonar mode. By the addition of a feature describing the sonar's mode of operation, a neural network is trained to detect man-made objects in any of the three sonar modes. The multimode detector is shown to perform very well when compared with detectors trained specifically for each sonar mode setting. The proposed detector is also shown to perform well when compared to a number of statistical detectors based on the same set of features. The proposed detector achieves a 92.4% probability of detection at a mean false-alarm rate of 10 per image, averaged over all sonar mode settings.     

水产试验设计的SAS实施方法

本文通过两个实例讨论水产试验设计的结果数据在ＳＡＳ系统上实施统计分析的方法。实例一考察不同温度和盐度对鲻鱼总孵化百分率的影响的带有４个丢失单元的５×６因子设计，调用ＲＳＲＥＳ过程作二次响应曲面回归分析，结果表明当温度为２７．０４℃、盐度为３１．９５‰可获得最大总孵化百分率９９．０７％；实例二调用ＮＬＩＮ过程拟合罗氏沼虾的生长曲线，由ＳＡＳ系统直接输出实测值对出生天数和预测值对出生天数的重迭散布图。     

黑龙江省四平山金矿床成矿作用及矿床成因：来自矿床地质、地球化学、锆石U-Pb年代学及H-O-S同位素的制约

四平山金矿床位于我国黑龙江省东部的完达山陆缘增生带内,矿体主要赋存于下白垩统四平山组,表现出明显的两阶段成矿作用特征。为进一步确定四平山金矿床的成矿作用及矿床成因,本次研究对其成矿地质特征、地球化学、成矿年代学及成矿物质来源进行了分析。地球化学分析结果表明：成矿花岗斑岩为具有高SiO₂（70.07%~72.93%）、（K₂O+Na₂O）（7.17%~8.42%）质量分数和右倾“海鸥型”稀土配分型式特征的A型花岗岩;含矿层状硅质岩中,Al/（Fe+Al+Mn）<0.32、Fe/Ti >20、(Fe+Mn)/Ti>20,并具有较高Fe₂O₃（0.18%～1.79%）、FeO（0.17%～0.96%）、MnO（0.03%~0.12%）、TiO₂（0.03%~0.04%）、Al₂O₃（0.30%~2.79%）和（K₂O+Na₂O）（0.07%~1.76%）质量分数,指示四平山金矿床形成于活动大陆边缘构造背景下与岩浆活动有关的热水沉积环境。四平山金矿床成矿花岗斑岩锆石U-Pb年龄为（113.5±0.7）Ma。H、O、S同位素分析结果（δD=-182.3‰~-84.0‰、δ¹⁸O_V-SMOW=6.5‰~14.3‰、δ³⁴S=-12.4‰~29.7‰）显示,成矿流体主要为大气降水,成矿物质具有以地层为主的多来源特征。综上,四平山金矿床为形成于燕山晚期活动大陆边缘构造背景下的热水沉积型矿床,太平洋板块持续俯冲造成了区域上大规模的拆沉作用,导致区域构造背景由挤压向伸展发生转换,此时形成的花岗斑岩岩浆运移至地壳浅部岩浆房加热上覆地层,在地壳浅部形成了温度与压力梯度带,促使地表的大气降水沿裂隙进入地层后形成流体循环系统,并不断萃取地层中的Au元素形成含矿流体。在成矿早阶段,当压力驱动含矿流体喷出地表后与地表水相遇快速冷却,成矿物质快速沉淀,形成含矿层状硅质岩和硅质胶结砾岩,并通过交代下伏流纹斑岩形成层状、似层状矿体;在成矿晚阶段,随着岩浆房提供的热动力减弱,含矿流体滞留在裂隙通道中或穿切进入早期固结的含矿层裂隙中,沉淀形成脉状-网脉状矿体。     

川北米仓山南缘典型石墨矿床地球化学特征与成因

文章对比分析了米仓山南缘旺苍-南江石墨矿带东、西2段主要石墨矿床地质及地球化学特征。矿带东段石墨矿体形态以不规则囊状为主,矿石类型以角砾状石墨大理岩型为主,矿体原岩为含有机质碳酸盐岩;矿石的V/Cr、V/(V+Ni)、U/Th平均值分别为0.75、0.42、0.94,稀土元素总量（∑REE）平均84.4μg/g,δEu平均0.65,矿体原岩沉积于贫氧环境。西段石墨矿体以似层状为主,层控特征明显,矿石类型为石墨片岩型,具钒矿化,原岩以含碳质黏土质、泥砂质碎屑岩为主;矿石的V/Cr、V/(V+Ni)、U/Th平均值分别为3.90、0.79、1.93,稀土元素总量（REE）平均124μg/g,δEu平均0.59,矿体原岩沉积于贫氧-缺氧环境。石墨矿δ13C值为-16.0‰～-23.0‰,平均-19.1‰,与有机质相近,显著低于大理岩围岩,表明石墨矿碳质来源以有机碳为主。米仓山南缘石墨矿床成因为沉积-变质型,石墨含矿层位经历了晋宁期-澄江期区域变质及热接触变质等多期变质成矿作用,最终形成晶质石墨矿床,其成矿与罗迪尼亚超大陆汇聚-裂解引发的区域变质-岩浆活动有关。     

Relationship Between Pb-Zn and Au-Ag Mineralization of Kengdenongshe Polymetallic Deposit in Eastern Segment of the Eastern KunlunEI北大核心CSCD

The Kengdenongshe deposit is a newly discovered large Au-Ag-Pb-Zn polymetallic deposit in the eastern Kunlun metallogenic belt, and the genetic relationship between Pb-Zn-rich ore bodies and Au-rich ore bodies in this deposit is controversial. Therefore, comparative studies of mineralization, alteration, and fluid inclusions in the two types of ore bodies were carried out with the statistical analysis of the correlation among ore-forming elements of Au, Ag, Pb and Zn. The results show that, from north to south, the mineralization changes gradually from Pb-Zn-rich to Au-rich with the wall-rock alteration from silicification-epidotization to baritization-marbleization-silicification. In addition, the structures of Pb-Zn-rich ores indicate a hydrothermal sedimentary origin with the late hydrothermal superposition, while those of Au-rich ores show features of hydrothermal origin. Besides, based on the study of fluid inclusions in this mining area, the ore-forming fluid of Pb-Zn-rich ores is low temperature (focus on 150-170°C) and low-medium salinity (1.74%-10.24% NaCleqv), while that of Au-rich ores displays low-medium temperature (manily 130-250°C) with low-medium salinity (0.35%-10.24% NaCleqv). Pb-Zn and Au-Ag show positive correlation (correlation coefficient r>0.25), but Au is poorly correlated with Pb and Zn (correlation coefficient r<0.15). However, to due to the late stage hydrothermal superimposition, Au is rather well correlated with Pb in high grade ores. In summary, there may exist two epochs of mineralization in the Kengdenongshe polymetallic deposit. The early one is Pb-Zn mineralization stage with characteristics of hydrothermal sedimentary origin, and the ore-forming fluid may be derived from the mixture of magmatic water and seawater. While the later one is Au mineralization stage, having characteristics of hydrothermal origin with subsequent hydrothermal superimpositions, and the ore-forming fluid is mainly derived from magmatic water that mixed with meteoric water. © 2018, Science Press. All right reserved.     

An Overview of Researches on Land-Atmosphere Interaction over Semi-Arid Region Under Global Changes

The semi-arid region, as a key part of global land, plays an important role in climate change. In the process of modern climate change, the semi-arid region is significantly affected by local human activities, showing remarkable expansion and obvious decadal variations. In this paper, we summarized the studies of the land-atmosphere interaction in the semi-arid regions in recent years, and major land surface observation plans. We put emphasis on energy balance, water cycle, carbon cycle in land-atmosphere interaction of climate change, and their performance in historical simulation and future prediction. The prediction results illustrate that new character of land-atmosphere interaction will appear as the drying of drylands in the future. Therefore, it is necessary to deepen the understanding of land-atmosphere interaction and move forward energetically on research in regional climate from different aspects.     

Ion Implants as Matrix‐Appropriate Calibrators for Geochemical Ion Probe Analyses

Ion microprobe elemental and isotopic determinations can be precise but difficult to quantify. Error is introduced when the reference material and the sample to be analysed have different compositions. Mitigation of such ‘matrix effects’ is possible using ion implants. If a compositionally homogeneous reference material is available which is ‘matrix‐appropriate’ (i.e., close in major element composition to the sample to be analysed, but having an unknown concentration of the element, E, to be determined) then ion implantation can be used to introduce a known amount of an E isotope, calibrating the E concentration and producing a matrix‐appropriate calibrator. Nominal implant fluences (ions cm^?2) are inaccurate by amounts up to approximately 30%. However, ion implantation gives uniform fluences over large areas; thus, it is possible to ‘co‐implant’ an additional reference material of any bulk composition having known amounts of E, independently calibrating the implant fluence. Isotope ratio measurement standards can be produced by implanting two different isotopes, but permil level precision requires postimplant calibration of the implant isotopic ratio. Examples discussed include (a) standardising Li in melilite; (b) calibrating a ²⁵Mg implant fluence using NIST SRM 617 glass and (c) using Si co‐implanted with ²⁵Mg alongside NIST SRM 617 to produce a calibrated measurement of Mg in Si.     

Petrography and geochemistry of the enriched basaltic shergottite Northwest Africa 2975

We present a study of the petrology and geochemistry of basaltic shergottite Northwest Africa 2975 (NWA 2975). NWA 2975 is a medium‐grained basalt with subophitic to granular texture. Electron microprobe (EMP) analyses show two distinct pyroxene compositional trends and patchy compositional zoning patterns distinct from those observed in other meteorites such as Shergotty or QUE 94201. As no bulk sample was available to us for whole rock measurements, we characterized the fusion crust and its variability by secondary ion mass spectrometer (SIMS) measurements and laser ablation inductively coupled plasma spectroscopy (LA‐ICP‐MS) analyses as a best‐available proxy for the bulk rock composition. The fusion crust major element composition is comparable to the bulk composition of other enriched basaltic shergottites, placing NWA 2975 within that sample group. The CI‐normalized REE (rare earth element) patterns are flat and also parallel to those of other enriched basaltic shergottites. Merrillite is the major REE carrier and has a flat REE pattern with slight depletion of Eu, parallel to REE patterns of merrillites from other basaltic shergottites. The oxidation state of NWA 2975 calculated from Fe‐Ti oxide pairs is NNO‐1.86, close to the QFM buffer. NWA 2975 represents a sample from the oxidized and enriched shergottite group, and our measurements and constraints on its origin are consistent with the hypothesis of two distinct Martian mantle reservoirs: a reduced, LREE‐depleted reservoir and an oxidized, LREE‐enriched reservoir. Stishovite, possibly seifertite, and dense SiO₂ glass were also identified in the meteorite, allowing us to infer that NWA 2975 experienced a realistic shock pressure of ~30 GPa.     

浴场海水中大肠杆菌耐药性及其耐药基因研究

为了解海水浴场中大肠杆菌耐药性状况及其耐药基因分布,以大连星海浴场近岸海水样品为研究对象,分离鉴定得到41株大肠杆菌,采用K-B药敏纸片法检测其对9种常用抗生素的耐药性,并对耐药菌株中的耐药基因进行检测。结果表明:41株受试大肠杆菌菌株对四环素的耐药率最高(46%),而对氨曲南的耐药率最低(5%),大肠杆菌的多重耐药率达到34%。采用PCR方法对41株分离菌株进行四环素耐药基因检测,结果显示,仅四环素耐药基因tetA和tetB被检出,其他4种类型四环素耐药基因未被检出。大肠杆菌基因组与质粒DNA中tetA的检出率分别为34%和29%;tetB的检出率分别为2%和12%。相关性分析结果表明大肠杆菌的四环素耐药表型与四环素耐药基因的阳性检出率显著相关。