共查询到19条相似文献，搜索用时 140 毫秒
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针对双频 P 码和载波相位观测值,提出了一种适用于短基线的模糊度单历元算法。 根据双频线性组合理论,该方法选择两个线性无关的宽巷组合 φ-7,9与 φ4,-5 ,组成相位与 P 码伪距的无几何模型,当观测条件较为理想时,采用直接取整的方法可得到正确的 N-7,9与 N4,-5 ,若 N-7,9的取整误差大于 0.3 周,则设置±1 周的范围,应用最小二乘搜索算法求解 N-7,9 ,而后,以 N4,-5的浮点解为中心,设置±3σN(4,-5)的范围,再次利用最小二乘搜索法求解 N4,-5 。 N4,-5与 N-7,9确定后,可以直接解算出原始模糊度。 理论分析及算例验证表明,该方法不需要已知测站坐标, 成功率高,实现了双差模糊度的单历元解算,解决了高精度动态实时定位的一个关键问题。 相似文献
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战备完好性是衡量武器装备能否担负战备任务的重要战技指标。 针对当前自航水雷战备完好性水平系统性评估需求,适应试验鉴定模式改革背景下评价自航水雷综合保障情况的问题,在对自航水雷寿命任务剖面分析的基础上,对影响其战备完好性的重要参数使用可用度进行了研究,给出了基于专家打分法的评估方法和模型,该方法可有效分析评估自航水雷使用可用度。 相似文献
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一种优化模糊度搜索方法的研究 总被引：1，自引：0，他引：1
对于高精度测量和导航,GPS载波相位整周模糊度的快速求解仍然是一个难点,尤其对于单频接收机。提出一种快速求解整周模糊度的方法,其基本思想采用分步求解,首先应用最小二乘模糊去耦调节法(LAMBDA)搜索出来的模糊度作为初始值,然后应用卫星分组方法降低搜索维数,并应用极大似然准则,构造搜索函数,最后应用最优化原理,搜索出最优的模糊度参数,并从三个方面对其进行检验,即RATIO检验,OVT检验,多项式拟合残差检验。为验证该算法,我们用单频GPS接收机进行了实验,利用本文方法在11 S以内正确确定了模糊度,其基线长误差小于3MM,表明该方法不但可以改进模糊度的搜索速度,而且可以进一步提高其可靠性和成功率。该方法可广泛应用于定向及姿态测量。 相似文献
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基于紊流随机理论的航槽三维流动数学模型 总被引：1，自引：0，他引：1
根据窦国仁的紊流随机理论，建立了一种模拟河口海岸水域中航槽三维流动的数学模型。采用控制体积法导出三维偏微分方程的离散格式；将水压力分解为动水压力和静水压力，用Patankar和Spalding提出的压力校正法求解动水压力，通过求解水位控制方程来得到自由表面；紊流模型采用安国仁提出的紊流随机理论，克服了k—ε模型中采用各向同性紊动粘滞系数的不足，而k—ε模型可作为紊流随机理论的一个特例。该模型计算了各种不同挖深比，各种航槽与水流交角的航槽流速分布，利用该模型计算得到的挖槽中的流速分布与水槽及水池试验资料相吻合。利用该模型可为开敞水域中开挖航槽的选择提供依据。 相似文献
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姜效典 《中国海洋大学学报(自然科学版)》1992,(2)
通过建立完全识别的贴近度模型,解决模糊识别中的首要问题——权重的求解,提高成矿预测的准确性。该方法可在需预测的矿种能建立起模型时使用。 相似文献
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N-S方程的数值解法及其在水波动力学中应用的综述 总被引：7，自引：0，他引：7
对于描述流体运动的基本方程N-S方程,现已开发出了多种不同的数值求解方法。其中以MAC法和VOF法为代表的网格数值方法较为成熟,并被逐渐用于实际工程的水动力研究中：以SPH和MPS为代表的粒子方法则刚刚起步．具有很大的发展空间。针对N-S方程中的能量耗散问题,采用雷诺时均化的方程形式仍是目前解决水动力问题的主要途径,但需要引入相应湍流模型,以封闭方程。本文首先对N-S方程求解方法的发展过程进行简要回顾,对一些重要的计算方法进行评述,简要介绍其在水波动力学中的应用;然后对时均化的N-S方程的主要封闭模式进行总结介绍;最后对数值求解N-S方程的发展趋势进行展望。 相似文献
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采用模糊综合评价法,根据2009年5个月份和2010年6个月份的东极大黄鱼(Larimichthys crocea)养殖区海水水样监测数据,对该养殖区海水水质状况进行了综合评价。结果表明,在年均值的评价中,2009年和2010年养殖区海水水质均为一类水,对一类水的隶属度分别为0.53和0.80,说明2010年的水质状况好于2009年。2010年6个监测月份的评价结果显示,各监测月份水质状况均为一类水质,但各月水质状况对一类水的隶属度值差别较大。4月份和5月份的水质状况对一类水的隶属度在0.5以上,6月份的水质状况对一类水的隶属度最低,仅为0.33,其余监测月份海水水质对一类水的隶属度均小于4、5月份。评价结果与东极大黄鱼养殖区水质的实际状况相符,说明模糊综合评价法适用于养殖区海水水质的评价。 相似文献
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YOKE T. YOON STEVEN R. NEREM MICHAEL M. WATKINS BRUCE J. HAINES GERHARD L. KRUIZINGA 《Marine Geodesy》2013,36(3-4):773-787
We have used GPS carrier phase integer ambiguity resolution to investigate improvements in the orbit determination for the Jason-1 satellite altimeter mission. The technique has been implemented in the GIPSY orbit determination software developed by JPL. The radial accuracy of the Jason-1 orbits is already near 1 cm, and thus it is difficult to detect the improvements gained when the carrier phase ambiguities are resolved. Nevertheless, each of the metrics we use to evaluate the orbit accuracy (orbit overlaps, orbit comparisons, satellite laser ranging residuals, altimeter crossover residuals, orbit centering) show modest improvement when the ambiguities are resolved. We conservatively estimate the improvement in the radial orbit accuracy is at the 10–20% level. 相似文献
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Cycle Slip Detection and Ambiguity Resolution Algorithms for Dual-Frequency GPS Data Processing 总被引：13，自引：0，他引：13
This article investigates the problem of cycle slip detection and ambiguity resolution using dual-frequency GPS data. Several algorithms are proposed and described. F or cycle slip detection, three L1/L2 observable combinations have been integrated to formulate a new algorithm for cycle slip detection. For ambiguity resolution, both widelane and narrowlane ambiguity resolution algorithms are presented, but the focus is on the narrowlane ambiguity resolution. Numerical results are included to evaluate the performance of the proposed algorithms, which have shown that cycle slips can be effectively detected and the narrowlane ambiguities can be resolved almost instantaneously after successful determination of the widelane ambiguities. 相似文献
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Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time. 相似文献
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Precise, long-range GPS kinematic positioning to centimeter accuracy requires that carrier phase ambiguities be resolved correctly during an initialization period, and subsequently to recover the “lost" ambiguities in the event of a cycle slip. Furthermore, to maximize navigational efficiency, ambiguity resolution and carrier phase-based positioning need to be carried out in real-time. Due to the presence of the ionospheric signal delay, satellite orbit errors, and the tropospheric delay, so-called absolute ambiguity resolution “on-the-fly” for long-range applications becomes very difficult, and largely impossible. However, all of these errors exhibit a high degree of spatial and temporal correlation. In the case of short-range ambiguity resolution, because of the high spatial correlation, their effect can be neglected, but their influence will dramatically increase as the baseline length increases. On the other hand, between discrete trajectory epochs, they will still exhibit a large degree of similarity for short time spans. In this article, a method is described in which similar triple-differenced observables formed between one epoch with unknown ambiguities and another epoch with fixed ambiguities can be used to derive relative ambiguity values, which are ordinarily equal to zero (or to the number of cycles that have slipped when loss-of-lock occurred). Because of the temporal correlation characteristics of the error sources, the cycle slips can be recovered using the proposed methodology. In order to test the performance of this algorithm an experiment involving the precise positioning of an aircraft, over distances ranging from a few hundred meters up to 700 kilometres, was carried out. The results indicate that the proposed technique can successfully resolve relative ambiguities (or cycle slips) over long distances in an efficient manner that can be implemented in real-time. 相似文献
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Distance-related errors complicate the resolution of real-time ambiguity in medium–long baseline marine surveys. Therefore, detection and recovery of cycle slips in real time is required to ensure high accuracy of global navigation satellite system positioning and navigation in marine surveys. To resolve this, an improved method was presented, where linear combinations of the triple-differenced (TD) between carriers L1 and L2 were formed for a wide lane and free ionosphere. To overcome severe ill-conditioned problems of the normal equation, the Tikhonov regularization method was used. The construction of a regularized matrix by combining a priori information of known coordinates of reference stations, followed by the determination of the corresponding regularized parameter are suggested. A float solution was calculated for the TD ambiguity. The search cycle slip (TD integer ambiguity) was obtained using the least-squares ambiguity decorrelation adjustment (LAMBDA) method. Using our method, cycle slips of several reference station baselines with lengths of a few hundred to one thousand kilometers were detected in real time. The results were consistent with professional software, with a success rate of 100%. 相似文献