218 resultados para 7136-301


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由不同功能UUV组成的异构系统能够实现对水下多个目标的探测和识别,多台UUV的协作机制已经成为当前水下机器人领域的一个热点课题。论文的研究工作依托国家863计划“基于弱通信的多机器人协调控制关键技术研究”等多项课题,面向水下多目标搜索应用背景,针对水下声学通信以及探测、导航传感器的局限性,研究弱通信条件下异构多UUV系统协作机制及实现方法,具体研究内容包括如下几个方面: (1) 构建了异构多UUV系统的体系结构:提出了基于多智能体角色联盟的UUV群体体系结构,使其能够适应多重的使命需求,具有开放性。设计了基于智能体思维结构的UUV个体体系结构,将UUV智能体的思维状态分为个体心智和社会心智两个层次分别实现,更加符合人类社会思维模式。基于面向对象Petri网理论对角色联盟进行建模,能够对角色内部控制逻辑和角色之间协作逻辑进行描述。 (2) 设计了多UUV系统的编队搜索策略:面向多目标搜索应用设计了编队搜索策略,保证搜索区域的连续性,采用基于大地坐标系的队形结构,更易于转弯时的队形控制。提出了基于思维层规划的队形控制方法,将跟随领航者法集成到队形控制任务的规划中,方便在不同任务间的切换,具有通用性。此外,设计了多UUV系统的队形重规划策略。 (3) 研究了多UUV系统的任务分配方法:针对同步搜索中的分布式任务分配问题,提出了动态熟人网方法,该方法对传统熟人网方法进行了改进和扩充,能够满足弱通信条件下任务分配的响应时间、执行时间、可靠性和负载均衡等性能要求,将动态熟人网方法应用于目标识别任务分配问题,仿真结果表明动态熟人网相比传统熟人网具有更好的性能。针对异步搜索中的多目标优化任务分配问题,提出了多蚁群系统(MACS)算法,该算法针对多个目标的不可公度性,对现有蚁群系统(ACS)算法进行了扩展,将MACS方法应用于多目标优化任务分配问题,仿真结果显示MACS算法相比加权法ACS具有更好的性能。 (4) 研究了多UUV系统低成本自主导航方法:提出了基于移动双信标的协作导航方法,采用两台携带高精度导航传感器的主UUV,为数量不限的携带低精度导航传感器的从UUV提供导航信息。设计了基于扩展卡尔曼滤波器的从UUV位置估计算法,该方法能够有效提高从UUV的导航精度,并且适应弱通信条件。 多UUV仿真平台的实验结果验证了本文提出的协作机制及实现方法是正确有效的,能够满足弱通信条件下多目标搜索的实际需求。

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In this dissertation, we investigated two types of traveling ionospheric disturbances (TIDs)/gravity waves (GWs) triggered separately by auroral energy input during super geomagnetic storms and solar terminator (ST) under quiet geomagnetic conditions (kp<3+) using TEC measurements from the global network of GPS receivers. Research into the generation and propagation of TIDs/GWs during storms greatly enhance our understandings on the evolution processes of energy transportation from the high-latitude’s magnetosphere to the low-latitude ionosphere and the conjugated effect of TIDs propagation between the northern and southern hemispheres. Our results revealed that the conjugacy of propagation direction between the northern and southern hemispheres was subject to the influence of Coriolis force. We also figure out the evolution processes of ionospheric disturbances at the global scale. These are important topics that had not been well addressed previously. In addition, we also obtained thee wave structures of medium scale TIDs excited by the solar terminator (ST) moving over the northern America and physical mechanisms involved. Our observations confirm that the ST is a stable and repetitive source of ionospheric wave disturbances and the evidence of solar terminator generated disturbances has been demonstrated experimentally via the GPS TEC measurement. The main researches and results of this dissertation are as follows. First, the global traveling ionospheric disturbances (TIDs) during the drastic magnetic storms of October 29–31, 2003 were analyzed using the Global Position System (GPS) total electron content (TEC) data observed in the Asian-Australian, European and North American sectors. We collected the most comprehensive set of the TEC data from more than 900 GPS stations on the International GNSS Services (IGS) website and introduce here a strategy that combines polynomial fitting and multi-channel maximum entropy spectral analysis to obtain TID parameters. Moreover, in collaboration with my thesis advisor, I have developed an imaging technique of 2-dimensional map of TIDs structures to obtain spatial and temporal maps of large scale traveling ionospheric disturbances (LSTIDs). The clear structures of TEC perturbations map during the passage of TIDs were displayed. The results of our study are summarized as follows: (1) Large-scale TIDs (LSTIDs) and medium-scale TIDs (MSTIDs) were detected in all three sectors after the sudden commencement (SC) of the magnetic storm, and their features showed longitudinal and latitudinal dependences. The duration of TIDs was longer at higher latitudes than at middle latitudes, with a maximum of about 16 h. The TEC variation amplitude of LSTIDs was larger in the North American sector than in the two other sectors. At the lower latitudes, the ionospheric perturbations were more complicated, and their duration and amplitude were relatively longer and larger. (2) The periods and phase speeds of TIDs were different in these three sectors. In Europe, the TIDs propagated southward; in North America and Asia, the TIDs propagated southwestward; in the near-equator region, the disturbances propagated with the azimuth (the angle of the propagation direction of the LSTIDs measured clockwise from due north with 0°) of 210° showing the influence of Coriolis force; in the Southern Hemisphere, the LSTIDs propagated conjugatedly northwestward. Both the southwestward and northeastward propagating LSTIDs are found in the equatorial region. These results mean that the Coriolis effect cannot be ignored for the wave propagation of LSTIDs and that the propagation direction is correlated with the polar magnetic activity. (3) The day (day of year: 301) before the SC (sudden commencement) of magnetic storm, we observed a sudden TEC skip disturbances (±10 TECU). It should be a response for the high flux of proton during the solar flare event, but not the magnetic storms. Next, the most comprehensive and dense GPS network’s data from North-America region were used in this paper to analyze the medium scale traveling ionospheric disturbances (MSTIDs) which were generated by the moving solar terminator during the quiet days in 2005. We applied the multi-channel maximum entropy spectral analysis to calculated TID parameters, and found that the occurrence of ST-MSTIDs depends on the seasonal variations. The results of our study are summarized as follows: (1) MSTIDs stimulated by the moving ST (ST-MSTIDs) are detected at mid-latitudes after the passage of the solar terminator with the life time of 2~3 hours and the variation amplitude of 0.2~0.8 TECU. Spectral analysis indicated that the horizontal wavelength, average period, horizontal phase velocity of the MSTIDs are around 300±150 km,150±80 m/s and 25±15 min, respectively. In addition, ST-MSTIDs have wave fronts elongating the moving ST direction and almost parallel to ST. (2) The statistical results demonstrate that the dusk MSTIDs stimulated by ST is more obvious than the dawn MSTIDs in summer. On the contrary, the more-pronounced dawn MSTIDs occurs in winter. (3) Further analysis indicates that the seasonal variations of ST-MSTIDs occurrence frequency are most probably related to the seasonal differences of the variations of EUV flux in the ionosphere region and recombination process during sunrise and sunset period at mid-latitudes. Statistical study of occurrence characteristics of TIDs using the GPS network in North-American and European during solar maximum, In conclusion, statistical studies of the propagation characteristics of TIDs, which excited by the two common origins including geomagnetic storms and moving solar terminator, were involved with global GPS TEC databasein this thesis. We employed the multichannel maximum entropy spectral analysis method to diagnose the characteristics of propagation and evolvement of ionospheric disturbances, also, the characteristics of their regional distribution and climatological variations were revealed by the statistic analysis. The results of these studies can improve our knowledge about the energy transfer in the solar-terrestrial system and the coupling process between upper and lower atmosphere (thermosphere-ionosphere-mesosphere). On the other hand, our results of the investigation on TIDs generated by particular linear origin such as ST are important for developing ionospheric irregularity physics and modeling the transionosphere radio wave propagation. Besides, the GPS TEC representation of the ST-generated ionospheric structure suggests a better possibility for investigating this phenomenon. Subsequently, there are scientific meaning of the result of this dissertation to deeply discuss the energy transfer and coupling in the ionosphere, as well as realistic value to space weather forecast in the ionosphere region.

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腐殖质的荧光特性被广泛用来解析其在各种天然环境中的来源及分布。由于荧光光谱分析具有灵敏度高,选择性好,且不破坏样品结构的优点,非常适合用来研究腐殖质的结构和官能团等特征。利用三维荧光激发-发射光谱研究了Fluka腐殖酸的荧光光谱特性,结果显示,离子强度(0~0.05mol/LKClO4)对Fluka腐殖酸的三维荧光光谱特性影响非常小,而腐殖酸的浓度(5~100mg/L)和溶液pH(2~12)对其三维荧光光谱特性影响显著。

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氮是引起湖泊水体富营养化的关键营养元素之一。本次工作从贵州两个重要水库(红枫湖和百花湖)采集了未受扰动的沉积物样品性,分析了分层沉积物样品中的总氮,无机交换性氮和固定铵的含量及垂直剖面分布,研究表明,红枫湖和百花湖沉积物中具有较高的全氮含量,平均含量约为沉积物干重的0.36%~0.40%,其垂直分布在埋藏过程中受到成岩作用改造,沉积物交换性氮在沉积物中的赋存受到全氮含量和埋藏环境的双重控制,红枫湖和百花湖沉积物具有较强的吸持固定铵的能力,沉积物固定铵的绝对含量的平均值分别为434.05mg/kg和416.94mg/kg,分别占全氮的13.53%和12.53%。

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重庆城口地区从震旦统到下寒武统发育有丰富的黑色岩系,20世纪末期在该地区黑色岩系中开展了大量的铂族元素(PGE)的找矿工作,但是由于种种原因,关于该地区是否存在PGE矿化异常,还没有得到最终的结论。本次研究在PGE分析方法论证的基础上,进行了大量样品的PGE分析和微量元素分析。主要结论如下:①区域上上震旦统槽区和断块区两套黑色岩系在原始的沉积环境和物源供给上有较大的差异,虽然槽区上震旦统的黑色岩系具有和下寒武统黑色岩系相似但强度较低的V-Cu-Y-Mo—U异常,但基本上不具有明显的PGE-Au-Ag异常。②断块区水井沱组黑色岩系:和平剖面西段新发现的U-V-Mo-PGE异常可能是今后工作的重点,Pt+Pd最高达248.9×10^-9,局部U-V都达到了工业品位。③槽区巴山组硅质岩:四个剖面都揭示了在硅质岩中广泛存在连续的PGE异常,87个碳质硅质岩平均含Pt+Pd 57.2×10^-9,有10个样品Pt+Pd〉100×10^-9,最高达196.5×10^-9;大部分碳质硅质岩都具有不同程度的V-Cu-Y-Mo-Tl-U组合异常,V都达到了独立矿床的品位要求,其中猪草河、燕子河等剖面还存在厚度较大的富矿地段,特别是燕子河剖面,局部还存在REE+Y的高异常,值得深入研究。④城巴地区下寒武统黑色岩系存在广泛的PGE异常,但没有达到PGE的矿化要求,建议加强该地区的钒矿和铀矿勘探研究,PGE可以综合评价。

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报道了一个改进的卡洛斯管溶样等离子体质谱法测定地质样品中铂族元素及Re含量的新方法。将封闭的卡洛斯管置于高压釜中,然后在高压釜中加水,密封在高压釜中的水在高温下产生的外压将会抵消卡洛斯管中由酸产生的内压,这样就可以避免传统的卡洛斯管在高温高压下可能发生爆炸的危险。由此可以加大取样量,降低铂族元素测定过程中的块金效应及检出限,使超低含量铂族元素的测定成为可能。12g样品在75mL卡洛斯管中用35mL王水于320℃溶解15h,基本上可以使各种地质样品中的铂族元素矿物完全溶解。一次溶样可以测定全部铂族元素及Re,全流程空白值极低,国际标样测定结果稳定可靠。

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系统测定了迤纳厂矿床不同类型矿石、围岩和火山角砾岩、岩浆岩的稀土元素组成。研究表明,不同类型矿石均具REE总量高(726X10^6—4633x10^6)、铕正异常(1.邱一5.16)、轻稀土强烈富集[(La/Yb)n=3.98—81.1]等特征,Y/Ho比值(24.4)小于球粒陨石中比值(28),与黑烟囱的比值接近。硅质白云岩及钠长石英斑岩、层状火山角砾岩的稀土特征(稀土总量低,铕负异常,轻重稀土分异不明显等)与矿石完全不同。成矿流体的稀土元素特征与现代大洋中脊热液相似,与裂谷初期的碱性火山岩稀土元素特征较为接近。结合矿床产出的大地构造背景,提出迤纳厂稀土铁铜矿床可能为昆阳裂谷初期碱性火山岩的喷发期间歇,来自地幔富稀土、富挥发份的成矿流体喷流.沉积成矿。

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峨眉山玄武岩分布于云、贵、川三省。在滇黔交界处,二叠世玄武岩因为广泛发育自然铜矿化而具有重要的研究意义。本研究通过地质、地层和地球化学的方法探讨本区出露的峨眉山玄武岩的起源、成因和喷发时代,同时用同位素方法探讨玄武岩铜矿成矿。通过本次研究获得以下成果: 1 探讨了威宁二叠纪玄武岩的成因。通过主量和微量元素地球化学特征研究表明:玄武岩起源于微混染的EMⅡ型富集地幔,岩浆端元矿物为石榴子石二辉橄榄岩。岩浆在上升过程中发生了辉石和橄榄石的分离结晶。微量元素Rb的强烈负异常,表明玄武岩形成后遭到了强烈的热液蚀变。 2 用恢复Rb-Sr古混合线定年方法确定了本区宣威组底部硅质页岩的成岩年龄为255±12 Ma,首次确定了峨眉山玄武岩的喷发上限年龄。 3 玄武岩铜矿石铅同位素组成206Pb/204Pb=18.078~18.923;207Pb/204Pb= 15.463~15.690; 208Pb/204Pb=38.301~39.036。通过Pb同位素比较研究,矿石铅同位素组成与玄武岩岩石铅同位素组成相似,成铜物质可能来源于玄武岩的淋滤。 4 与玄武岩铜矿伴生的沥青和碳质δ13CPDB值变化在-32.3‰ ~-21‰之间,与自然界δC13储库生物成因的碳同位素组成相符,表明其为有机成因。铜矿石中方解石的碳氧同位素表现出明显的特殊性,以富δ18OSMOW和贫δ13CPDB 为特征,δ18OSMOW和δ13CPDB值分别为13.1‰~22.9‰ 和-32.3 ‰ ~ -13.5‰。不同矿床碳同位素组成一致,暗示碳为同一来源,均为有机碳。 5 矿石中石英和方解石中流体包裹体的H-O同位素组成为:δ18O矿物-SMOW,14.3‰ ~18.9‰;δ18O水-SMOW,2.8‰ ~ 7.2‰; δ18D水-SMOW,-63.6‰ ~ -80.6‰。其中流体包裹体均一温度为151 ~ 201℃。研究表明,成矿流体来源于建造水与玄武岩发生强烈的水-岩反应所形成的成矿流体。成矿流体通过对流循环方式从玄武岩中萃取成矿物质,有机质对成矿流体的还原和对成矿物质的吸附作用可能是成矿的重要机制。