天山东段隆升过程的裂变径迹年龄证据及构造意义

东天山基底隆升过程主要发生在新生代之前，白垩纪后该地区没有发生过快速隆升。东天山隆起带构造面貌基本继承了中生代的特征，这与天山西段主要是新生代陆内造山形成的构造地貌明显不同。其原因可能与古生代南天山洋盆自东向西的剪刀状闭合和塔里木板块的斜向碰撞有关。     

遗传模拟退火的BP算法在冲击地压中的应用

冲击地压的预测、预报的研究,大多数仍停留在简单的统计研究和单因素的预测方面,因而,结果也不十分理想。笔者采用多层前向网络对该问题进行数学建模,网络的训练算法采用基于遗传模拟退火的BP优化算法。该算法是在遗传算法中引入模拟退火机制,将其同BP算法结合,形成一个混合的优化算法。新算法既有神经网络的学习能力和鲁棒性,又有遗传算法的强全局随机搜索能力。同时,利用华丰矿冲击地压的实际监测数据,通过遗传算法的主要性能指标对新算法的参数进行了比较研究,得到优化后的一组参数。利用该参数,对冲击地压的神经网络模型的结构、权值和阈值进行了优化,得到了非全连接的优化神经网络模型。最后,利用该模型对华丰矿冲击地压进行了短期最大震级的预报。预测结果的相对误差率平均为 7.84 %,预测效果比较理想。     

一种全局优化的隐式交错网格有限差分算法及其在弹性波数值模拟中的应用

在数值模拟中,隐式有限差分具有较高的精度和稳定性.然而,传统隐式有限差分算法大多由于需要求解大型矩阵方程而存在计算效率偏低的局限性.本文针对一阶速度-应力弹性波方程,构建了一种优化隐式交错网格有限差分格式,然后将改进格式由时间-空间域转换为时间-波数域,利用二范数原理建立目标函数,再利用模拟退火法求取优化系数.通过对均匀模型以及复杂介质模型进行一阶速度-应力弹性波方程数值模拟所得单炮记录、波场快照分析表明:这种优化隐式交错网格差分算法与传统的几种显式和隐式交错网格有限差分算法相比不但降低了计算量,而且能有效的压制网格频散,使弹性波数值模拟的精度得到有效的提高.     

Ensemble Forecast for Tropical Cyclone Based on CNOP-P Method: A Case Study of WRF Model and Two Typhoons

In this paper, we set out to study the ensemble forecast for tropical cyclones. The case study is based on the Conditional Nonlinear Optimal Perturbation related to Parameter (CNOP-P) method and the WRF model to improve the prediction accuracy for track and intensity, and two different typhoons are selected as cases for analysis. We first select perturbed parameters in the YSU and WSM6 schemes, and then solve CNOP-Ps with simulated annealing algorithm for single parameters as well as the combination of multiple parameters. Finally, perturbations are imposed on default parameter values to generate the ensemble members. The whole proposed procedures are referred to as the Perturbed Parameter Ensemble (PPE). We also conduct two experiments, which are control forecast and ensemble forecast, termed Ctrl and perturbed-physics ensemble (PPhyE) respectively, to demonstrate the performance for contrast. In the article, we compare the effects of three experiments on tropical cyclones in aspects of track and intensity, respectively. For track, the prediction errors of PPE are smaller. The ensemble mean of PPE filters the unpredictable situation and retains the reasonably predictable components of the ensemble members. As for intensity, ensemble mean values of the central minimum sea-level pressure and the central maximum wind speed are closer to CMA data during most of the simulation time. The predicted values of the PPE ensemble members included the intensity of CMA data when the typhoon made landfall. The PPE also shows uncertainty in the forecast. Moreover, we also analyze the track and intensity from physical variable fields of PPE. Experiment results show PPE outperforms the other two benchmarks in track and intensity prediction.     

矿物裂变径迹年龄与青藏高原隆升速率研究

本文通过对青藏高原冈底斯花岗岩带中段花岗闪长岩中不同矿物裂变径迹年龄研究表明,青藏高原南部的隆升是分阶段的,从岩体就位到约30Ma为高原缓慢隆升阶段,30Ma-7Ma期间高原隆升速度加快,7Ma以来高原快速隆升;结合已有的有关青藏高原不同地区隆升速率、时限研究成果认为,青藏高原的隆升具有整体性、阶段性、加速性和区域的不均衡性。      

基于目标规划与模拟退火算法的土地利用分区优化方法

以兰州市榆中县为实验区,选取分区适宜性、规划协调性和空间紧凑性作为分区目标,基于目标规划和模拟退火算法对实验区进行土地利用分区优化。结果表明,不同情景下的分区方案能很好地满足决策者设定的目标偏好值;从空间特征分析的结果看,本分区方案较原有分区方案对各个分区目标进行了优化,更好地满足了农业生产、经济发展以及生态保护的要求。     

Apatite fission-track study on the thermo-tectonic history of the Huainan Coalfield in Anhui Province, China： Tectonic implications for the potential coalbed methane resource

Coalbed methane (CBM) is a kind of burgeoning and enormously potential clean energy resource, and the temperature of the thermogenic CBM generation is close to that of the partial annealing zone (PAZ) of apatite fission tracks (AFT). In this study the thermo-tectonic history of the Huainan Coalfield and the potential CBM resource were studied and discussed by using the AFT method. The AFT data indicate that the apparent ages of AFT vary from 45.5 to 199.1 Ma. They are younger than the ages of their host strata (255–1800 Ma) except one sample, and the single-grain ages of AFT can be classified as a single age group for each sample. In combination with the geological setting, modeling results of the AFT ages, average lengths, and the thermal history based on the AFT single-grain ages and length distributions, some preliminary conclusions can be drawn as follows: (1) at least three thermo-tectonic events (in the periods of ∼240, 140 and 80 Ma, respectively) have occurred in the study area since the Late Paleozoic. The occurrence of both the first (during 240–220 Ma) and second (during 160–120 Ma) thermo-tectonic events is possibly responsible for the establishment of the patterns of gas generation and reservoir formation. The second thermo-tectonic event also led to slight accumulation of hydrocarbons and generation of thermogenic gas; (2) the AFT ages of most coal-bearing strata lie between 50 and 70 Ma. They should represent the cooling ages and the ages of inferred uplift and denudation, as well as the possible CBM release history. Therefore, the maximum burial depth of coal-bearing strata and the denudation thickness of the overlying strata are over 3000 and 2000 m in the Upper Cretaceous and Paleogene series, respectively; and (3) subsequently, a spot of secondary biogenic and scarcely thermogenic gas generation occurred due to negligible sedimentation during the Neogene and Quaternary periods. Thus, it can be presumed that subsequent tectonism would destroy the CBM reservoir after its formation in the Huainan Coalfield, especially in its structural development region. These AFT data may be helpful for a better understanding of the thermo-tectonic history of the Huainan Coalfield, as well as of CBM generation, storage and release in the Huainan Coalfield.     

基于改进遗传算法的多约束VRP求解

建立了多约束条件车辆路径问题的数学模型和求解流程.先采用最近插入法生成初始解,然后基于遗传算法和模拟退火算法改进初始解.实验结果表明:结合模拟退火与遗传算法求解车辆路径问题,可以在一定程度上解决遗传算法易"早熟收敛"问题,从而得到更优的解.     

Cretaceous and Cenozoic cooling history across the ultrahigh pressure Tongbai–Dabie belt, central China, from apatite fission-track thermochronology

The crystalline terrane of the Tongbai–Dabie region, central China, comprising the Earth's largest ultrahigh-pressure (UHP) exposure was formed during Triassic collision between the Sino–Korean and Yangtze cratons. New apatite fission-track (AFT) data presented here from the UHP terrane, extends over a significantly greater area than reported in previous studies, and includes the (eastern) Dabie, the Hong'an (northwestern Dabie) and Tongbai regions. The new data yield ages ranging from 44 ± 3 to 142 ± 36 Ma and mean track lengths between 10 and 14.4 μm. Thermal history models based on the AFT data taken together with published ⁴⁰Ar/³⁹Ar, K–Ar, apatite and zircon (U–Th)/He and U–Pb data, exhibit a three-stage cooling pattern that is similar across the study region, commencing with an Early Cretaceous rapid cooling event, followed by a period of relative thermal stability during which rocks remained at temperatures within the AFT partial annealing zone (60–110 °C) and ending with a possible renewed phase of accelerated cooling during Pliocene to Recent time. The first cooling phase followed large-scale transtensional deformation between 140 and 110 Ma and is related to Early Cretaceous eastward tectonic escape and Pacific back arc extension. Between this phase and the subsequent slow cooling phase, a transition period from 120 to 80 Ma (to 70 to 45 Ma along the Tan–Lu fault) was characterised by a relatively low cooling rate (3–5 °C/Ma). This transition is likely related to a tectonic response associated with the mid-Cretaceous subduction of the Izanagi–Pacific plate as well as lithospheric extension and thinning in eastern Asia. The present regional AFT age pattern is therefore basically controlled by the Early Cretaceous rapid cooling event, but finally shaped through active Cenozoic faulting. Following the transition phase the subsequent slow cooling phase pattern implies a net reduction in horizontal compressional stress corresponding to increased extension rates along the continental margin due to the decrease in plate convergence. Modelling of the AFT data suggests a possible Pliocene–Recent cooling episode, which may be supported by increased rates of sedimentation observed in adjacent basins. This cooling phase may be interpreted as a response to the far-field effects of the frontal India–Eurasia collision to the west. Approximate estimates suggest that the total amount of post 120 Ma denudation across the UHP orogen ranged from 2.4 to 13.2 km for different tectonic blocks and ranged from 0.8 to 9.7 km during the Cretaceous to between 1.7 and 3.8 km during the Cenozoic.     

On the reconstruction of structural and functional properties in random heterogeneous media

Flow and transport in porous media is determined by its structure. Beside spatial correlation, especially the connectivity of heterogeneous conductivities is acknowledged to be a key factor. This has been demonstrated for well defined random fields having different topological properties. Yet, it remains an open question which morphological measures carry sufficient information to actually predict flow and transport in porous media. We analyze flow and transport in classical, two-dimensional random fields showing different topology and we determine a selection of structural characteristics including classical two-point statistics, chord-length distribution and Minkowski functions (four-point statistics) including the Euler number as a topological measure. Using the approach of simulated annealing for global optimization we generate analog random fields that are forced to reproduce one or several of theses structural characteristics. Finally we evaluate in how far the generated analogons reproduce the original flow and transport behavior as well as some more elaborate structural characteristics including percolation probabilities and the pair connectivity function. The results confirm that two-point statistics is insufficient to capture functional properties since it is not sensitive to connectivity. In contrast, the combination of Minkowski functions and chord length distributions carries sufficient information to reproduce the breakthrough curve of a conservative solute. Hence, global topology provided by the Euler number together with local clustering provided by the chord length distribution seems to be a powerful condensation of structural complexity with respect to functional properties.