原子钟噪声的蒙特卡络模拟方法

讨论了原子钟噪声的蒙特卡络模拟方法．具体过程是：先产生模拟所需的正态分布随机数，从实际钟的阿仑方差估算出噪声电平，然后用１组递点函数产生高质量的模拟钟时差的随机序列．在对１台商品铯钟进行具体模拟后，给出了真实数据与模拟值的阿仑方差之问的相符程度，最后对实际问题进行了分析．     

Generalized likelihood uncertainty estimation (GLUE) using adaptive Markov Chain Monte Carlo sampling

In the last few decades hydrologists have made tremendous progress in using dynamic simulation models for the analysis and understanding of hydrologic systems. However, predictions with these models are often deterministic and as such they focus on the most probable forecast, without an explicit estimate of the associated uncertainty. This uncertainty arises from incomplete process representation, uncertainty in initial conditions, input, output and parameter error. The generalized likelihood uncertainty estimation (GLUE) framework was one of the first attempts to represent prediction uncertainty within the context of Monte Carlo (MC) analysis coupled with Bayesian estimation and propagation of uncertainty. Because of its flexibility, ease of implementation and its suitability for parallel implementation on distributed computer systems, the GLUE method has been used in a wide variety of applications. However, the MC based sampling strategy of the prior parameter space typically utilized in GLUE is not particularly efficient in finding behavioral simulations. This becomes especially problematic for high-dimensional parameter estimation problems, and in the case of complex simulation models that require significant computational time to run and produce the desired output. In this paper we improve the computational efficiency of GLUE by sampling the prior parameter space using an adaptive Markov Chain Monte Carlo scheme (the Shuffled Complex Evolution Metropolis (SCEM-UA) algorithm). Moreover, we propose an alternative strategy to determine the value of the cutoff threshold based on the appropriate coverage of the resulting uncertainty bounds. We demonstrate the superiority of this revised GLUE method with three different conceptual watershed models of increasing complexity, using both synthetic and real-world streamflow data from two catchments with different hydrologic regimes.     

基于GIS的西平县土地利用变化分析

在遥感和地理信息系统软件支持下,通过2002年的ETM＋和2007年的CBERS遥感图像分析,利用马尔科夫链的元胞自动机模型与构建土地利用适宜性图层,模拟西平县2012年土地利用变化。结果表明：到2012年,西平县城镇及工矿用地将在原有基础上向四周辐射发展,交通运输用地将在原来基础上拓宽,村镇居民点及公路周围的耕地将减少,林地、其他用地也将减少。     

Primary proton spectrum around the knee deduced from the emulsion-chamber data obtained at Mts. Fuji and Kanbala

We have done extensive Monte Carlo simulations using the new simulation codes of CORSIKA and COSMOS to compare with the gamma-family data obtained at Mts. Fuji (3750 m above sea level) and Kanbala (5500 m above sea level). Then, we estimated the primary proton and helium spectra around the knee energy region using a multiple-layered feed-forward neural network as a classifier of primary particle kind. The selection efficiency of proton-induced family events is estimated to be 82%. The flux value of protons at 2×10¹⁵ eV is (5.5±1.5)×10⁻¹⁴ (m⁻² s⁻¹ sr⁻¹ GeV⁻¹). The result suggests heavy-enriched primary composition around the knee region.     

Monte Carlo simulation of scintillation crystal detector for formation element logging

Formation elements logging is a neutron gamma spectroscopy logging technique used to acquire the content of elements and minerals by recording the gamma ray produced by the reaction of neutron and elemental nucleus in the formation. It has a wide usage in discriminating complex lithology and evaluating unconventional reservoir. The Monte Carlo simulation model of formation elements logging tool is established in this paper, with which the effects of tool parameters including the material and length of the scintillation crystal and source spacing on logging responses are modeled. The results show that the energy response of LaBr_3: Ce crystal is better than others, and the detection efficiency increases with the crystal length but decrease with source spacing. The above results may be used as a reference for optimizing the tool structure design.     

应用巢式逆转录聚合酶链反应检测鱼类病毒性出血性败血症病毒(VHSV)

参照鱼类病毒性出血性败血症病毒序列,根据PCR引物设计的原则,设计巢式PCR引物,采用巢式逆转录聚合酶链反应(RT-PCR)方法,对如何快速检测鱼类病毒性出血性败血症病的方法进行了较为系统的研究,并对RT-PCR的反应条件进行了优化.结果表明,巢式RT-PCR扩增获得279bp的特异性片断,阴性对照无扩增条带.巢式RT-PCR扩增出的特异性片段经测序分析,结果证实与报道的序列完全一致.该方法最低可检测出0.1pg的鱼类病毒性出血性败血症病毒RNA.初步建立了VHSV的巢式RT-PCR检测方法,该方法灵敏、特异,可为VHSV的检测提供一个快速、有效的手段.     

植物正构烷烃及其单体氢同位素在古环境研究中的应用

正构烷烃是植物类脂的重要组成部分,主要用来维持叶片表面的水分平衡,其平均碳链长度(ACL)作为植物对水分胁迫程度的生理性反映,与植物进化程度存在表观上的联系。高等植物来源烷烃的ACL高于低等植物和水生藻类,裸子植物高于被子植物,C4植物高于C3植物,因此植物正构烷烃具备粗略的植物分类学意义,并在古环境研究中被广泛应用。在河口和海洋沉积物中主要用来判断水生低等植物和陆地高等植物的相对贡献,在古土壤中则用来区分草本/木本植物的消长变化。植物烷烃中的氢元素主要来自光合作用时吸收的环境水,其δD主要受环境条件和生物化学过程影响,但环境条件、气候状况和植被类型的影响可以在很大程度上相互抵消,使烷烃δD具有记录大气降水δD的潜力,从而可以用来重建大气降水δD并反演气候变化。     

An Improved Perturbation Mechanism for Simulated Annealing Simulation

Simulated annealing (SA) is being increasingly used for the generation of stochastic models of spatial phenomena because of its flexibility to integrate data of diverse types and scales. The major shortcoming of SA is the extensive CPU requirements. We present a perturbation mechanism that significantly improves the CPU speed. Two conventional perturbation mechanisms are to (1) randomly select two locations and swap their attribute values, or (2) visit a randomly selected location and draw a new value from the global histogram. The proposed perturbation mechanism is a modification of option 2: each candidate value is drawn from a local conditional distribution built with a template of kriging weights rather than from the global distribution. This results in accepting more perturbations and in perturbations that improve the variogram reproduction for short scale lags. We document the new method, the increased convergence speed, and the improved variogram reproduction. Implementation details of the method such as the size of the local neighborhood are considered.     

利用马氏过程模拟和预测土壤侵蚀的动态演变─—以安徽省岳西县为例

本文根据安徽省岳西县１９５８－１９８２－１９９２年三个时期的遥感资料所编制的土壤侵蚀图，用点数转化法定量地分析岳西县上述两个阶段侵蚀演变和浸蚀类型之间的相互转化状况，确定相应的初始状态下（１９５８和１９８２）的转移概率矩阵，应用马尔科夫过程摸拟和预测岳西县土壤侵蚀及其格局的动态演变过程和未来演变趋势。     

Stratigraphic analysis and the asymptotic distribution of the coefficient of cross-association

The asymptotic distribution of the coefficient of cross-association between two sequences of nominal data is investigated under the assumption of independent random sampling from a multinomial distribution slightly modified to suit geological applications. This modification is due to merging consecutive strata of the same rock type into one lithological unit, and can be described by a simple Markov chain. A distinction is made between the case in which the theoretical frequencies are known, and the situation where these have to be estimated from the observed data.