基于GIS和AI的城市区域内最佳路径算法研究

针对传统Dijkstra算法效率低的特点,从GIS和人工智能的角度提出了一种对传统Dijkstra算法进行优化的方式。首先根据城市交通网络的特点建立了交通网络拓扑图,提出了地名节点和交通节点的概念,并用合理的数据结构存储此交通网络,然后在此基础上使用一种新的启发函数以提高搜索效率,使优化过的Dijkstra算法能用于复杂的交通网络。     

Optimization of artificial ground freezing in tunneling in the presence of seepage flow

Artificial ground freezing is an environmentally friendly technique to provide temporary excavation support and groundwater control during tunnel construction under difficult geological and hydrological ground conditions. Evidently, groundwater flow has a considerable influence on the freezing process. Large seepage flow may lead to large freezing times or even may prevent the formation of a closed frozen soil body. For safe and economic design of freezing operations, this paper presents a coupled thermo-hydraulic finite element model for freezing soils integrated within an optimization algorithm using the Ant Colony Optimization (ACO) technique to optimize ground freezing in tunneling by finding the optimal positions of the freeze pipe, considering seepage flow. The simulation model considers solid particles, liquid water and crystal ice as separate phases, and the mixture temperature and liquid pressure as primary field variables. Through two fundamental physical laws and corresponding state equations, the model captures the most relevant couplings between the phase transition associated with latent heat effect, and the liquid transport within the pores. The numerical model is validated by means of laboratory results considering different scenarios for seepage flow. As demonstrated in numerical simulations of ground freezing in tunneling in the presence of seepage flow connected with the ACO optimization algorithm, the optimized arrangement of the freeze pipes may lead to a substantial reduction of the freezing time and of energy costs.     

Numerical simulation of hydrocarbon migration in tight reservoir based on Artificial Immune Ant Colony Algorithm: A case of the Chang 81 reservoir of the Triassic Yanchang Formation in the Huaqing area,Ordos Basin,China

The hydrocarbon migration in tight reservoirs is a complex process, the fluid flow patterns of which are notably different from those of conventional reservoirs. Therefore, specific mathematical models are needed to simulate the secondary hydrocarbon migrations. This study presents a numerical simulation method based on Artificial Immune Ant Colony Algorithm (AIACA) to simulate the secondary hydrocarbon migrations in tight reservoirs. It consists of three core parts: (1) the release modes of artificial ants based on the intensity of hydrocarbon generation; (2) the wandering patterns of artificial ants under the control of the dynamic field and the distribution of pheromones; (3) the updating modes of pheromones based on the changes in reservoir wettability. The simulation of secondary migration can be realized by the observing the dynamic movements and accumulations of the artificial ants. The method has been tested in the Chang 8₁ tight sandstone reservoir, which is part of the Triassic Yanchang Formation in the Huaqing Area, Ordos Basin in China, and proved to be successful in matching the current data in exploration and development.     

Sediment characteristics and macrofauna distribution along a human-modified inlet in the Gulf of Oristano (Sardinia, Italy)

We studied the spatial variability and within-year temporal changes in hydrological features, grain size composition and chemical characteristics of sediments, as well as macrofaunal assemblages, along a heavily modified inlet in the Gulf of Oristano (western Sardinia, Italy). The inlet connects the Cabras lagoon to the gulf through a series of convoluted creeks and man-made structures, including a dam and fish barriers built in the last three decades. Sediments were muddy and mainly composed of the "non-sortable" fraction (i.e., <8 microm particle size) in all four areas investigated: Lagoon, Creeks, Channel and Seaward. Along the inlet, however, the ratio between the <8 microm and the 8-64 microm fractions was highest in Creeks and Channel, between the fish barriers and the dam, suggesting impaired hydrodynamics. Consistently, steep gradients in water salinity, temperature and dissolved oxygen concentrations were found in proximity to the fish barriers. The whole inlet was characterized by a major organic enrichment of sediments, with up to an annual mean of 33.6% of organic matter and 11.7% of total organic carbon in Seaward due to the presence of seagrass leaf litter. Acid-volatile sulphide and chromium-reduced sulphur concentrations were highest throughout the year in Seaward and Lagoon, respectively, with a peak in summer. Consistently, the whole inlet supported low structured macrofaunal assemblages dominated by few opportunist species, with a relatively lower diversity in Lagoon throughout the year and the highest abundances in Seaward in summer. We infer that the presence of artificial structures along the inlet, such as fish barriers and the dam, impair the lagoon-gulf hydrodynamics, sediment exchange and animal recruitment and colonization. We suggest that the removal of these structures would favour water renewal in the Cabras lagoon, but would also increase the outflow of organic C-bonding fine particles into the gulf with serious consequences for Posidonia oceanica and Cymodocea nodosa seagrass meadows. We conclude that all possible consequences of such initiatives should be carefully considered before any action is taken.     

斜入射条件下地下结构时域地震反应分析初探

通过采用平面波和远场散射波混合透射的应力人工边界条件,得到了地震波斜入射的解析方式,以此为基础建立了地震波斜入射条件下,土体与地下结构动力相互作用的时域计算分析模型。以实际建设的南京地铁某车站结构为研究对象,应用大型通用有限元分析软件ANSYS,进行了地震波斜入射条件下地下结构时域地震反应的计算和分析。初步结果表明:在地震波斜入射的情况下,地下结构的动力反应与地震波垂直入射时有较为明显的差异。     

地下水回灌技术在浅层承压含水层中的实践与探讨

上海地区承压含水层埋深较深,深基坑围护的止水帷幕难以深入到承压含水层底板进行地下水水平向的完全阻隔,减压降水过程势必对周边环境产生一定影响。以上海盛大国际金融中心深基坑回灌试验为依据,表明人工回灌地下水对控制承压水位具有一定效果,并运用数值方法模拟了不同回灌条件下坑外承压水位的变化。     

野生重口裂腹鱼[Schizothorax(Racoma) davidi(Sauvage)]的性腺发育观察与人工繁殖研究

对野生重口裂腹鱼[Schizothorax(Racoma) davidi(Sauvage)]的性腺发育观察与人工繁殖进行了研究。结果表明,重口裂腹鱼雄鱼3龄达到性成熟,而雌鱼5龄以上方达到性成熟,其性腺指数随着年龄增加而显著上升(P<0.05);雌鱼性腺指数、绝对怀卵量和卵径随着年龄和体重增加明显上升(P<0.05orP<0.01)。对24尾5、6龄雌、雄重口裂腹鱼采用二针注射法进行人工催产实验,平均采卵数为1.33万粒和2.02万粒,采精量为25.4ml和34.8ml。其平均卵子受精率和受精卵出膜时间分别为74.2%和77.1%、203h和227h[水温(16.2±0.9)℃],6龄雌鱼受精卵的卵径、卵重均明显高于5龄雌鱼,6龄雌鱼的受精卵孵化率为41.9%,明显高于5龄雌鱼的30.6%(P<0.05orP<0.01),选用年龄较大的雌鱼作为亲鱼,是保证人工繁殖获得良好效果的关键。     

一次火箭人工增雨分析

根据冰晶增长理论和播云条件,完善了以往人工增雨作业指标,提出在有利的天气形势下进行人工增雨作业时,确定水平作业范围的指标为:冷层中冰面饱和区、水汽积分量≥9 mm的区域和水汽垂直输送区的重合区.确定作业高度的指标为:在垂直剖面图上冰面饱和区、水汽垂直输送区和准饱和区的重合区.作业时间应选在水平、垂直指标出现和消失的时间段内.利用MM5中尺度模式的输出结果,以3 h为时间间隔,在0～-30 ℃层之间间隔5 ℃输出计算的各种作业指标预报图和综合图,形成业务化网页.应用作业指标于2007年3月3日在山东省聊城市莘县组织实施了一次火箭人工增雨作业,并对以上指标进行了验证.     

Effects of small external forces on the planar oscillation of a cable connected satellites system

The effects of small external dissipative and disturbing forces on the non-linear planar oscillation of a cable connected satellites system in the central gravitational field of earth have been studied. Typical non-linear oscillation's phenomena arizing from the aforesaid external forces are shown to take place. The presence of these forces enables the application of asymptotic methods of the theory of non-linear oscillations due to Bogoliubov and Mitropolsky to the equation characterizing the non-linear oscillation of the system.     

江南一条中强地震带初探

中元古代(17亿年前后)以来发生发展的江南断裂带,既是一条控岩控矿的古断裂带,也是江南地区一条中强地震带——江南中强地震带。震级43/_4—63/_4级,是铜陵—扬州地震带以南的另一条地震带