一种新的优化灌溉制度算法——自由搜索

应用现有典型算法求解灌溉制度优化设计模型时,由于各种算法本身存在着不足,可被接受的模型最优解往往不能够被成功搜索到。自由搜索(Free Search,FS)是一种新的优化算法,对其进行了适当改进,针对灌溉制度优化设计模型实例,在不同的可供水量下,应用FS算法对该模型进行求解。结果表明,FS算法表现出良好的稳健性和收敛性;与以往的动态规划逐次逼近法(DPSA)、遗传算法(GA)及混沌算法(CA)对该实例的寻优结果相比,FS算法提高了寻优精度。FS算法原理简单,操作简便,是一种较好的优化灌溉制度的新方法。     

A chemical equilibrium algorithm for highly non-ideal multiphase systems: Free energy minimization

A method is presented for calculating equilibrium phase assemblages in very nonideal systems. It may be applied to any system for which a thermodynamically consistent model of the free energy which satisfies the usual Maxwell relations and convexity criterion is available. The algorithm minimizes the Gibbs free energy by independently choosing stable reaction directions. The procedure is described in detail and various numerical problems encountered and strategies for dealing with them are discussed. It will be shown that the necessary and sufficient conditions for solution phase selection may be derived from the values of the Lagrange multipliers corresponding to constraints on phases that are not present in the system. The method for evaluating the solution phase Lagrangian multipliers and choosing the optimum composition with which to bring the new solution phase into the system involves a separate constrained minimization problem. This method is sufficiently general so that the correct phase assemblage is chosen free from external control. Special procedures for adding and removing phases including solution phases are also described.     

A novel algorithm for designing the layout of additional boreholes

In an exploration project, the placement of additional boreholes is based on the available information and engineering judgment, which may result in a lack of information or redundant information in decision making. This paper presents the use of dynamic multistage sampling to design directional and vertical boreholes to scan the subsurface. For this purpose, the potential collars of boreholes are determined within the survey area, while the imaginary boreholes in the form of cone sides cover the area's lateral surface area, and the concentric cones around the collars change with azimuth and dip angles. The objective function is a criterion used to determine the optimal borehole(s) and update the input borehole database in each stage; this iterative process continues until a stopping condition is satisfied. The presented algorithm was executed and validated on both synthetic and field data from the Eastern Kahang region in Iran. In the synthetic case, five additional boreholes were designated based on high grade and estimation error objectives that intersect two parts of the ore body. Ten proposed additional boreholes in the northeast region of Kahang coincided with the high grade copper mineralization zone.     

水文地质参数识别的连续禁忌搜索改进算法

水文地质参数的正确与否是构建地下水数值模型的根本,而参数寻优结果很大程度上取决于优化算法的选择。禁忌搜索算法是一种广泛应用于组合优化问题的启发式全局寻优算法,但在连续函数优化领域应用比较少。基于上述考虑,本文首先引入求解连续函数优化问题的连续禁忌搜索算法并对其进行改进,进而提出一种连续禁忌搜索改进算法(ICTS),最后将其与地下水模型耦合进行水文地质参数识别。算例研究表明,ICTS算法较其他算法(CTS,SGA,Micro-GA,PSO)求解效率提高1.87～4.64倍,求解精度提高1.08～12.86倍。因此ICTS算法在参数反演计算中求解精度高、收敛速度快、寻优性能强,是一种值得推广的水文地质参数识别方法。     

Enhancement of backtracking search algorithm for identifying soil parameters

In this paper, an enhanced backtracking search algorithm (so-called MBSA-LS) for parameter identification is proposed with two modifications: (a) modifying the mutation of original backtracking search algorithm (BSA) considering the contribution of current best individual for accelerating convergence speed and (b) novelly incorporating an efficient differential evolution (DE) as local search for improving the quality of population. The proposed MBSA-LS is first validated with better performance than the original BSA and some other typical state-of-the-art optimization algorithms on a benchmark of soil parameter identification in terms of effectiveness, efficiency, and robustness. Then, the efficiency of the MBSA-LS is further illustrated by two representative cases: identifying soil parameters from both laboratory tests and field measurements. All comparisons demonstrate that the proposed MBSA-LS algorithm can give accurate results in a short time. Finally, to conveniently solve the problems of parameter identification, a practical tool ErosOpt for parameter identification is developed by integrating the proposed MBSA-LS and some other efficient algorithms for readers to conduct the parameter identification using optimisation algorithms.     

基于模式搜索的微地震速度反演——以渤海K油田为例

无论是井间地震还是水力压裂微地震,都需要知道相对准确的地层速度,笔者提出了一种新的微地震层速度反演方法,即模式搜索算法.首先利用测井资料和地质认识建立初始速度模型,然后拾取射孔记录的地震初至时间.由于有些地震记录激发时间难以确定,因此可利用各地震道之间的时差建立目标函数,最后利用模式搜索算法寻找目标函数最优解.模型试算结果及实际资料的应用都表明,该方法对于参数较少的层状介质模型有比较好的效果,为渤海水力压裂等技术提供一定借鉴意义.     

一种基于数值应力场的强度各向异性边坡稳定性分析方法

提出了一种基于数值应力场下的边坡临界滑动面和临界坡高的分析方法。该分析方法首先利用有限元得到边坡内部较为精确的应力场,再通过在边坡内部模拟类似于链式反应过程中粒子产生和运动规律,在此基础上完成临界滑动面的搜索。主要结论如下：（1）提出了一种基于数值应力场的边坡临界滑动面的搜索方法,该方法可在不对边坡滑动面形状和位置进行干预的情况下完成潜在破坏路径的搜索。（2）通过对算法中区域与边界、激发源、产物扩散路径、路径权值4方面要素进行合理控制,可使算法在具有较高精度的同时又能保证较好的分析效率。（3）算法能较为方便地考虑真实应力条件下地层强度各向异性对边坡稳定性的影响,并能对临界坡高进行很好的分析。（4）通过具体算例对本文算法的计算结果进行验证,将所得结果与PSO和Monte Carlo两种方法得到结果进行对比,对本文方法的可靠性进行了验证,取得了较好的效果。     

An approximate nearest neighbors search algorithm for low-dimensional grid locations

We propose a new algorithm for the problem of approximate nearest neighbors (ANN) search in a regularly spaced low-dimensional grid for interpolation applications. It associates every sampled point to its nearest interpolation location, and then expands its influence to neighborhood locations in the grid, until the desired number of sampled points is achieved on every grid location. Our approach makes use of knowledge on the regular grid spacing to avoid measuring the distance between sampled points and grid locations. We compared our approach with four different state-of-the-art ANN algorithms in a large set of computational experiments. In general, our approach requires low computational effort, especially for cases with high density of sampled points, while the observed error is not significantly different. At the end, a case study is shown, where the ionosphere dynamics is predicted daily using samples from a mathematical model, which runs in parallel at 56 different longitude coordinates, providing sampled points not well distributed that follow Earth’s magnetic field-lines. Our approach overcomes the comparative algorithms when the ratio between the number of sampled points and grid locations is over 2849:1.     

Regional policy in Poland: A search for equity

Polish regional policy and planning has long traditions and post-war socialist policies demonstrate important continuities with the 1930s. Regional policy since 1945 has progressed from sets of individual decisions on reconstruction through more coordinated policies for uniform development, for rational location and for activation of backward regions. Lack of adequate coordination and rigorous accounting, though, often meant excessive concentration of development in existing industrial areas and key urban centres. In the 1960s fashionable growthpole concepts were applied to medium-sized city development without maintaining adequate balance between continued growth in larger cities and new smaller-town development. Reform, long overdue, is required to implement the national spatial plan for the 1990s.     

High-gradient magnetic separation: A search for a matrix material

The magnetic properties and abrasion resistance of selected low-carbon steels were investigated with respect to their suitability as induction matrix materials. Low-remanent ferromagnetic steels and a paramagnetic steel were used in magnetic separation tests with siderite and hematite ores. It was found that recovery and grade for all ferromagnetic materials were equivalent, while recovery for paramagnetic steel was lower, and increased with increasing magnetic induction. However, all investigated steels are less susceptible to hold highly coercive tramp iron which usually causes matrix clogging. Likewise, all selected stainless steels are more abrasion resistant than currently employed matrix materials.     

Bubble-induced porewater mixing: A 3-D model for deep porewater irrigation

Porewater data from vent sites of the northeastern shelf off Sakhalin Island, Sea of Okhotsk, exhibit bottom-water concentrations down to a sediment depth of up to 300 cm. Below this depth, solute concentrations rapidly change due to methanogenesis and anaerobic methane oxidation (AMO). The profile shapes suggest an irrigation-like process that mixes on a meter scale. At these sites active gas emanation into the overlying water column and near-surface gas hydrates are commonly observed. We propose that methane gas bubbles rise through the soft surface sediments and cause mixing of the porewater.Mathematically, the bubble-induced irrigation can be described by eddy diffusion enhancing the diffusive transport of solutes by several orders of magnitude. A 3-D numerical transport-reaction model was developed to investigate the parameters defining the mixing process, such as bubble rise velocity, tube size, tube distribution in the sediment, and ebullition frequency.Model consistency with the field data requires eddy diffusivities ?1 × 10⁵ cm²/a, tube densities of >4 tubes/m² (equivalent to a tube spacing of <40 cm), active gas seepage for more than a few weeks or months, and moderate to low diagenetic reaction rates of solutes. The corresponding methane gas fluxes that are predicted from the results of the model realizations range from 1 × 10³-5 × 10⁵ L/(m² a). Due to bubble mixing, solute fluxes in these sediments are increased by a factor of 3 and the maximum AMO rate by a factor of 7.     

A new search for life on Mars

Developments in spacecraft technology are allowing us to examine the Solar System ever more closely. A European mission is currently being prepared to send a package of highly advanced instruments to Mars to search for any traces of life, past or present.     

基于择多算子的随机搜索法建立数字岩心的新技术

介绍了用于刻画岩心孔隙空间特征的两点概率函数、线性路径函数,提出了建立数字岩心的新方法--基于择多算子的随机搜索法,系统阐述了该方法的建模理论及基于择多算子的孔隙点、骨架点的随机搜索策略,指出搜索孔隙点、骨架点的择多算子的适宜取值区间分别为[9,12]和[4,7]。研究表明,该法进行数字岩心建模不仅可行而且效果良好。它不受岩性地限制;所建数字岩心的孔隙形态及空间分布特征与真实岩心孔隙相似;尽管岩心含有一定数量的孤立孔隙和岩石颗粒,但其规模很小;岩心具有良好的孔隙连通性、各向同性和渗透性,故可用来研究多孔介质中流体的分布和渗流等问题;由于该法建立的数字岩心的连通性随孔隙度的减小而变差,故该法更适于建立大孔隙度岩心。     

A novel genetic algorithm for optimization of conditioning factors in shallow translational landslides and susceptibility mapping

Genetic algorithm (GA) is an effective approach in selecting the best factors without considering all possible combinations in landslide susceptibility mapping (LSM). The approach experienced a local optimal solution for hazard mapping. In this study, we propose a novel genetic algorithm (NGA) for solving the problems of optimal precision in selecting conditioning factors based on the crossover and mutation. In the southwestern part of China, including Wenchuan, Ludshan, and Ludian areas, the findings of this study confirm the applicability of NGA, which has a strong robustness compared to GA obviously. Results indicated that the highest area under curve (AUC) of GA is 93.47, 83.45, and 82.21% in Wenchuan, Lushan, and Ludian, respectively. Cumulative error of the precision (?R) is 3.19, 10.48, and 6.05%, and error of the highest precision (?P) is 0.01, 0.03, and 0.12% for Wenchuan, Lushan, and Ludian, respectively. Compared to the GA, the highest accuracy of NGA is 93.48% (Wenchuan), 83.48% (Lushan), and 82.28% (Ludian). It also revealed that ?R is 0.77, 1.26, and 1.82%, and ?P is 0.00, 0.04, and 0.05% for Wenchuan, Lushan, and Ludian, respectively. By comparing with GA, the novel approach of NGA has stronger robustness and higher accuracy on selecting the optimal conditioning factors of landslide. Additionally, the relationship of landslide occurrence with controlling factors was assessed in every study area. According to the results, lithology, distance to roads, elevation, and slope were regarded as the most effective factors for shallow translational landslides. These factors implied that internal structure and composition of rock, anthropogenic activity, and topography factors posed the main impacts on landslide occurrence. Finally, we implemented landslide susceptibility assessment in three study areas. Results showed that high landslide susceptibility was in the east and northeastern parts of Wenchuan; central region northward of Lushan; and southwest, central region, and west of Ludian.     

The KHOLOD experiment: A search for a new population of radio sources

Published data from long-term observations of a strip of sky at declination ?? ?? 5° carried out at 7.6 cm on the RATAN-600 radio telescope are used to estimate some statistical properties of radio sources. Limits on the sensitivity of the survey due to noise imposed by background sources, which dominates the radiometer sensitivity, are refined. The vast majority of noise due to background sources is associated with known radio sources (for example, from the NVSS with a detection threshold of 2.3 mJy) with normal steep spectra (?? = 0.7?C0.8, S ?? ?? ^??? ), which have also been detected in new deep surveys at decimeter wavelengths. When all such objects are removed from the observational data, this leaves another noise component that is observed to be roughly identical in independent groups of observations. We suggest this represents a new population of radio sources that are not present in known catalogs at the 0.6 mJy level at 7.6 cm. The studied redshift dependence of the number of steep-spectrum objects shows that the sensitivity of our survey is sufficient to detect powerful FRII radio sources at any redshift, right to the epoch of formation of the first galaxies. The inferred new population is most likely associated with low-luminosity objects at redshifts z < 1. In spite of the appearance of new means of carrying out direct studies of distant galaxies, searches for objects with very high redshifts among steep and ultra-steep spectrum radio sources remains an effective method for studying the early Universe.     

A new schedule for copper chemical speciation analysis in soil and water sediment

The speciation of heavy metals is very important to evaluate their environmental impact. This issue has become an interested topic many decades ago and many significative studies were carried out such as direct detecting, calculation with mathematical model represented in recent years as well as Tessier＇s work in 1979, BCR＇s work in 1993, etc. In all of them, the methods recommended by Tessier and BCR are most often used in practical study today. But it should be seen that experimental schedule and agents define these methods including BCR＇s method, which improved on Tessier＇s method, only. In many cases, there always are deviations between analytical results and real content of the speciation. Otherwise, steps of the extraction experiment are always strict and excessive in the experimental process. The method, which is fitting to extract the speciation of bioavailability and easy to assess the effect of metals in the environment, is very anticipant. In this paper, the sequential three steps schedule of speciation analysis of copper in soil and water sediment is discussed as an example based on the comparative results of experimental analysis with the schedules of BCR＇s （mended by Rauret et al. in 1999） and TDPA （diethylenetriamine pentacetic acid） extraction, respectively. The results from sequential three steps method and other methods recommended by prevenient work suggest that the analytical schedule of sequential three steps of separating speciation （the speciation of easy effect to life-form, the speciation available to life-form, and the speciation of no effect to life-form） is valuable for copper speciation analysis in soil and sediment. Because of easy process and saving time to evaluate its availability for life form,     

边坡稳定验算中全面搜索的一种新方法

提出圆弧滑动法中一种新的搜索方法———三向搜索法。圆弧滑动法可以利用其共性而不局限于一些经验假设,在坡顶线及其下部各道坡线间都存在一个安全系数最小的圆弧,针对这些圆弧的寻找,给出了具体办法,并给出几个计算实例。     

A simple model of an irrigation system for oasis fields

In this paper the author considers the irrigation of oasis fields as a system of air-soil-plant, and discusses the simple model's structure, irrigational value and distribution. It is important to ration constructed hydro-resources and to increase the amount yielded by them and to protect the environment.     

Optimizing groundwater development strategies by genetic algorithm: a case study for balancing the needs for agricultural irrigation and environmental protection in northern China

Gaoqing Plain is a major agriculture center of Shandong Province in northern China. Over the last 30 years, the diversion of Yellow River water for intensive irrigation in Gaoqing Plain has led to elevation of the water table and increased evaporation, and subsequently, a dramatic increase in salt content in soil and rapid degradation of crop productivity. Optimal strategies have been explored, that will balance the need to extract sufficient groundwater for irrigation (to ease the pressure on diverting Yellow River water) with the need to improve the local environment by appropriately lowering the water table. Two simulation-optimization models have been formulated and a genetic algorithm (GA) is applied to search for the optimal groundwater development strategies in Gaoqing Plain, while keeping the adverse environmental impacts in check. Compared with the trial-and-error approach of previous studies, the optimization results demonstrate that using an optimization model coupled with a GA search is both effective and efficient. The optimal solutions identified by the GA will provide Gaoqing Plain with the blueprints for developing sustainable groundwater abstraction plans to support local economic development and improve its environmental quality. Li Zheng is currently a visiting scientist in the Mathematical Modeling and Analysis Group, Los Alamos National Laboratory, New Mexico, USA.     

A search for primordial atmospheric-like argon in an iron meteorite

He and Ar were extracted from the Weekeroo Station octahedrite in six heating steps. The Ar isotopic ratios were searched for any indication of an indigenous component with atmospheric-like values. Negative results were obtained.