Optimal curvature-constrained paths for general directional-cost functions

This paper studies the problem of finding the minimum cost curvature-constrained path between two directed points where the cost at every point along the path depends on the instantaneous direction. This generalises the results obtained by Dubins for curvature-constrained paths of minimum length, commonly referred to as Dubins paths. We show that there always exists a path of the form $\mathcal {C}\mathcal {S}\mathcal {C}\mathcal {S}\mathcal {C}$ or a degeneracy which is optimal, where $\mathcal {C}$ represents an arc of maximum curvature, and $\mathcal {S}$ represents a straight line. This result is also extended to the case where there is not only a directional-cost, but the cost of curved sections are scaled up by a factor w ^C ≥1. The results obtained can be applied to optimising the development of underground mine networks, where the paths need to satisfy a curvature constraint, the cost of development of the tunnel depends on the direction due to the geological characteristics of the ground, and curved sections may incur more cost due to additional support and ventilation.     

Exact algorithm for delay-constrained capacitated minimum spanning tree network

The delay-constrained capacitated minimum spanning tree (DC-CMST) problem of finding several broadcast trees from a source node is discussed. While the traditional CMST problem deals with only the traffic capacity constraint served by a port of the source node, and delay-constrained minimum spanning tree (DCMST) considers only the maximum end-end delay constraint, the DC-CMST problem deals with both the mean network delay and traffic capacity constraints. The DC-CMST problem consists of finding a set of minimum cost spanning trees to link end-nodes to a source node satisfying the traffic requirements at end-nodes and the required mean delay of the network. In the DC-CMST problem, the objective function is to minimise the total link cost. A dynamic programming-based three-phase algorithm that solves the DC-CMST problem is proposed. In the first phase, the algorithm generates feasible solutions to satisfy the traffic capacity constraint. It finds the CMSTs in the second phase, and allocates the optimal link capacities to satisfy the mean delay constraint in the third phase. Performance evaluation shows that the proposed algorithm has good efficiency for any network with less than 30 nodes and light traffic. The proposed algorithm can be applied to any network regardless of its configuration, and used for the topological design of local networks and for efficient routing algorithms capable of constructing least cost broadcast trees.     

Strategic planning of an underground mine with variable cut-off grades

Optimization and Engineering - We present a mixed-integer programming model for solving the long-term planning problem of an underground mine. This model, which establishes the sequence of mining...     

A stochastic optimization formulation for the transition from open pit to underground mining

As open pit mining of a mineral deposit deepens, the cost of extraction may increase up to a threshold where transitioning to mining through underground methods is more profitable. This paper provides an approach to determine an optimal depth at which a mine should transition from open pit to underground mining, based on managing technical risk. The value of a set of candidate transition depths is calculated by optimizing the production schedules for each depth’s unique open pit and underground operations which provide yearly discounted cash flow projections. By considering the sum of the open pit and underground mining portion’s value, the most profitable candidate transition depth is identified. The optimization model presented is based on a stochastic integer program that integrates geological uncertainty and manages technical risk. The proposed approach is tested on a gold deposit. Results show the benefits of managing geological uncertainty in long-term strategic decision-making frameworks. Additionally, the stochastic result produces a 9% net present value increase over a similar deterministic formulation. The risk-managing stochastic framework also produces operational schedules that reduce a mining project`s susceptibility to geological risk. This work aims to approve on previous attempts to solve this problem by jointly considering geological uncertainty and describing the optimal transition depth effectively in 3-dimensions.     

Model-Based Clustering of Nonparametric Weighted Networks With Application to Water Pollution Analysis

Abstract

Water pollution is a major global environmental problem, and it poses a great environmental risk to public health and biological diversity. This work is motivated by assessing the potential environmental threat of coal mining through increased sulfate concentrations in river networks, which do not belong to any simple parametric distribution. However, existing network models mainly focus on binary or discrete networks and weighted networks with known parametric weight distributions. We propose a principled nonparametric weighted network model based on exponential-family random graph models and local likelihood estimation, and study its model-based clustering with application to large-scale water pollution network analysis. We do not require any parametric distribution assumption on network weights. The proposed method greatly extends the methodology and applicability of statistical network models. Furthermore, it is scalable to large and complex networks in large-scale environmental studies. The power of our proposed methods is demonstrated in simulation studies and a real application to sulfate pollution network analysis in Ohio watershed located in Pennsylvania, United States.     

基于贪心遗传的地下物流节点选择规划研究

以国内某地区物流概况为研究背景,结合国内外地下物流系统研究成果,将集合覆盖的思想引入地下物流网络节点选址规划,建立以物流节点数量最少及物流节点转运率最低为优化目标的双层多目标规划模型,并结合贪心算法和遗传算法进行优化求解。研究表明：通过将集合覆盖的思想对城市地下物流系统节点规划进行初步探讨是可行有效的;基于贪心遗传算法进行优化求解,使得该地区地下物流网络节点选择达到全局最优,有效控制了物流节点的数量及节点转运率的大小;地下物流网络节点表现出明显的区域集中性,即服务节点均集中在物流需求点附近,且二级节点服务区域总是邻近某个一级节点。     

Local cost minimization in ant transport networks: from small-scale data to large-scale trade-offs

Transport networks distribute resources and information in many human and biological systems. Their construction requires optimization and balance of conflicting criteria such as robustness against disruptions, transport efficiency and building cost. The colonies of the polydomous Australian meat ant Iridomyrmex purpureus are a striking example of such a decentralized network, consisting of trails that connect spatially separated nests. Here we study the rules that underlie network construction in these ants. We find that a simple model of network growth, which we call the minimum linking model (MLM), is sufficient to explain the growth of real ant colonies. For larger networks, the MLM shows a qualitative similarity with a Euclidean minimum spanning tree, prioritizing cost and efficiency over robustness. We introduce a variant of our model to show that a balance between cost, efficiency and robustness can be also reproduced at larger scales than ant colonies. Remarkably, such a balance is influenced by a parameter reflecting the specific features of the modelled transport system. The extended MLM could thus be a suitable source of inspiration for the construction of cheap and efficient transport networks with non-zero robustness, suggesting possible applications in the design of human-made networks.     

Integral methodology for distribution systems reconfiguration based on optimal power flow using Benders decomposition technique

A new and efficient methodology for distribution network reconfiguration integrated with optimal power flow (OPF) based on a Benders decomposition approach is presented. The objective minimises power losses, balancing load among feeders and subject to constraints such as capacity limit of branches, minimum and maximum power limits of substations or distributed generators, minimum deviation of bus voltages and radial optimal operation of networks. A variant of the generalised Benders decomposition algorithm is applied to solve the problem. The formulation can be embedded under two stages; the first one is the master problem and is formulated as a mixed integer non-linear programming problem. This stage determines the radial topology of the distribution network. The second stage is the slave problem and is formulated as a non-linear programming problem. This stage is used to determine the feasibility of the master problem solution by means of an OPF and provides information to formulate the linear Benders cuts that connect both problems. The model is programmed in GAMS mathematical modeling language. The effectiveness of the proposal is demonstrated through two examples extracted from the specialised literature.     

Intelligent Mining Technology for an Underground Metal Mine Based on Unmanned Equipment

This article analyzes the current research status and development trend of intelligent technologies for underground metal mines in China, where such technologies are under development for use to develop mineral resources in a safe, efficient, and environmentally friendly manner. We analyze and summarize the research status of underground metal mining technology at home and abroad, including some specific examples of equipment, technology, and applications. We introduce the latest equipment and technologies with independent intellectual property rights for unmanned mining, including intelligent and unmanned control technologies for rock-drilling jumbos, down-the-hole (DTH) drills, underground scrapers, underground mining trucks, and underground charging vehicles. Three basic platforms are used for intelligent and unmanned mining: the positioning and navigation platform, information-acquisition and communication platform, and scheduling and control platform. Unmanned equipment was tested in the Fankou Lead-Zinc Mine in China, and industrial tests on the basic platforms of intelligent and unmanned mining were carried out in the mine. The experiment focused on the intelligent scraper, which can achieve autonomous intelligent driving by relying on a wireless communication system, location and navigation system, and data-acquisition system. These industrial experiments indicate that the technology is feasible. The results show that unmanned mining can promote mining technology in China to an intelligent level and can enhance the core competitive ability of China’s mining industry.     

Exact topology discovery algorithm for the capacity and delay constrained loop network

We have developed an exact model and algorithm for the delay-constrained minimum cost loop problem (DC-MCLP) of finding broadcast loops from a source node. While the traditional minimum cost loop problem (MCLP) deals with only the traffic capacity constraint served by a port of source node, the DC-MCLP deals with the mean network delay and traffic capacity constraints simultaneously. The DC-MCLP consists of finding a set of minimum cost loops to link end-user nodes to a source node satisfying the traffic requirements at end-nodes and the required mean delay of the network. In the DC-MCLP, the objective function is to minimise the total link cost. We have formulated the DC-MCLP and proposed an exact algorithm for its solution. The proposed algorithm is composed of two phases: in the first phase, it generates feasible paths to satisfy the traffic capacity constraint; in the second phase it finds the exact loop topology through matching and allocating optimal link capacity to satisfy the mean delay constraint. In addition, we have derived several properties including the memory and time complexity of the proposed algorithm. Performance evaluation shows that the proposed algorithm has good efficiency for networks with less than thirty nodes and light traffic. Our proposed algorithm can be applied to find the broadcast loops for real-time multimedia traffic     

A mixed-integer programming approach to the parallel replacement problem under technological change

The parallel replacement problem under economies of scale (PRES) determines minimum cost replacement policies for each asset in a group of assets that operate in parallel and are subject to fixed and variable purchase costs. We study the mixed-integer programming formulation of PRES under technological change by incorporating capacity gains into the model such that newer, technologically advanced assets have higher capacity than assets purchased earlier. We provide optimal solution characteristics and insights about the economics of the problem and derive associated cutting planes for optimising the problem. Computational experiments illustrate that the inequalities are quite effective in solving PRES under technological change instances.     

The complexity of routing in hierarchical PNNI networks

We study the complexity of computing a route in a hierarchical PNNI network, with H levels of hierarchy, in which N nodes are grouped into clusters at each level. We determine cluster sizes that minimize an upper bound on the total time for all the path computations required to compute a route. Our model casts the problem as a nonlinear convex optimization problem, and employs nonlinear duality theory. We derive explicit closed form upper bounds on the minimum total path computation time, as a function of N, for H=2 and H=3, and show how the upper bound, and the optimal cluster sizes, can be computed for any H. We provide a conjecture on the complexity of PNNI routing for any H, and use this conjecture to determine the limit of the complexity as H→∞. We also prove that the minimum total path computation time is a non-increasing function of H. Our results provide counterexamples to a claim by Van Mieghem that a related top-down hierarchical routing method has lower computational complexity.     

塑卷铵松蜡炸药在小铁山矿的应用

文章针对铵松蜡炸药防潮性能的弱点，改纸卷包装为塑料卷包装，基本解决了防潮难题，并投入井下应用。通过现场应用和对比试试验得出，在小铁山和塑卷馐谣铵松蜡炸药代替价格较高的２岩炸药的结论。     

三山岛金矿辅助斜坡道光面爆破方案研究

采用先施工导硐、后施工光爆层的二次成巷方案,通过合理地优化爆破设计以及多次对现场光面爆破方案进行总结和完善,使得光面爆破在三山岛金矿辅助斜坡道施工中得到成功的应用,提高了斜坡道施工进度,确保了该矿资源开采的安全性.     

复杂环境下楼房倒塌过程的计算机模拟

使用ANSYS/LS-DYNA软件对某厂办公楼爆破拆除过程进行了数值模拟。采用SOLIDl64单元MAT_BRITTLE_DAMAGE材料建立了以钢筋混凝土为主的整体式有限元模型,用MAT_ADD_EROSION关键字控制爆破切口的形成和材料的失效,爆破切口形成过程由"时间"开关控制。模拟了办公楼的爆破拆除倒塌过程、倒塌形成的爆堆和倒塌触地后与周围建筑物的距离及倒塌过程中的整体应力分布等,并与实际爆破效果进行了比较,证明了计算机模拟是合理可行的,对具体实际工程具有一定的指导意义。     

An optimal procedure for solving the hierarchical network design problem

The hierarchical network design problem consists of finding a minimum cost bilevel network that connects all the nodes in a set, created by a loopless main path and a forest. The main path is formed by primary (higher cost) arcs, providing a path between an origin node and a destination node. The forest, built using secondary (lower cost) arcs, connects all the nodes not on the main path, to the path itself. We state and prove some properties of the problem, which allow finding good upper bounds to the solution in polynomial time when the primary costs are proportional to secondary costs. We also propose an O(n⁴) procedure to improve on these bounds. In turn, these bounds are used to significantly reduce the number of nodes and arcs of the problem. Once the problem is reduced, large instances can be solved to optimality. At this stage, we use one of two linear integer optimization formulations. The first and preferred one is based on multicommodity flows, which avoids the formation of subtours. The second formulation avoids subtours by iteratively adding ad hoc constraints. We show some examples and provide computational experiments performed on networks with sizes up to 600 nodes and 14 000 arcs.     

银山铅锌矿中深采矿爆破方法的探讨

简述江西铜业公司银山铅锌矿井下采矿爆破概况及实际效果，指出期所用导爆索一次爆破方法存在问题，分析孔口起爆法与孔底起爆法的爆破作用机理，并比较两种起爆法的优缺点，建立采用非电导爆管雷管分段微差，也底起爆的爆破方案。     

Minimum steering node set of complex networks and its applications to biomolecular networks

Many systems of interests in practices can be represented as complex networks. For biological systems, biomolecules do not perform their functions alone but interact with each other to form so‐called biomolecular networks. A system is said to be controllable if it can be steered from any initial state to any other final state in finite time. The network controllability has become essential to study the dynamics of the networks and understand the importance of individual nodes in the networks. Some interesting biological phenomena have been discovered in terms of the structural controllability of biomolecular networks. Most of current studies investigate the structural controllability of networks in notion of the minimum driver node sets (MDSs). In this study, the authors analyse the network structural controllability in notion of the minimum steering node sets (MSSs). They first develop a graph‐theoretic algorithm to identify the MSS for a given network and then apply it to several biomolecular networks. Application results show that biomolecules identified in the MSSs play essential roles in corresponding biological processes. Furthermore, the application results indicate that the MSSs can reflect the network dynamics and node importance in controlling the networks better than the MDSs.Inspec keywords: molecular biophysics, biocontrol, graph theoryOther keywords: graph‐theoretic algorithm, MSS, minimum driver node sets, structural controllability, network dynamics, network controllability, biological systems, biomolecular networks, complex networks, minimum steering node set     

An Algorithm for Project Cost-Duration Analysis Problem with Quadratic and Convex Cost Functions

Kuhn-Tucker necessary and sufficient conditions for the nonlinear programming problem are applied to the project cost-duration analysis problem for project networks with convex costs. These conditions give an optimality curve for the problem. A solution is optimal if and only if when the values for activities are plotted on their optimality diagram, the values lie on the optimality curve. An algorithm is given here when the cost is convex and quadratic. The algorithm is also generalized to the case when the cost is convex and piecewise quadratic. The algorithm can be used to solve problems with convex cost functions by approximating them by piecewise quadratic functions.     

露天矿山台阶深孔爆破大块成因及解决措施

露天矿台阶深孔爆破大块率高是露天矿山生产过程中普遍存在的一个问题,在白马铁矿采场西帮断层角砾岩和下盘伟晶辉长岩等部位爆破大块率高的情况尤其突出。为此,结合白马铁矿近几年爆破开采情况和地质条件,详细地阐述了大块产生的位置以及采场难爆区域的状况,分析其产生的原因。根据实际条件,从起爆网路,炮孔布置,装药结构,优化难爆部位孔网参数、创造有利爆破条件以及施工与管理等方面,总结出有效降低白马铁矿露天台阶深孔爆破大块率的具体措施和方法。