Optimization-based heuristics for underground mine scheduling

Underground mine production scheduling possesses mathematical structure similar to and yields many of the same challenges as general scheduling problems. That is, binary variables represent the time at which various activities are scheduled. Typical objectives seek to minimize costs or some measure of production time, or to maximize net present value; two principal types of constraints exist: (i) resource constraints and (ii) precedence constraints. In our setting, we maximize “discounted metal production” for the remaining life of an underground lead and zinc mine that uses three different underground methods to extract the ore. Resource constraints limit the grade, tonnage, and backfill paste (used for structural stability) in each time period, while precedence constraints enforce the sequence in which extraction (and backfill) is performed in accordance with the underground mining methods used. We tailor exact and heuristic approaches to reduce model size, and develop an optimization-based decomposition heuristic; both of these methods transform a computationally intractable problem to one for which we obtain solutions in seconds, or, at most, hours for problem instances based on data sets from the Lisheen mine near Thurles, Ireland.     

Creating nanostars with buckyballs

We report creating superradiant quantum nanoplasmas (nanostars) by impacting buckyballs at hypervelocities (v>100 km/s) in an innovative tabletop apparatus. The nanostars are estimated to have ～10 TPa transient pressures and convert ～35% of impact energy into soft-X-ray energy. The ultrahigh-efficiency conversion is proposed to result from Dicke Superradiance of Metastable Innershell Molecular State, originally discovered by the author and his colleagues in 1994. The usage of buckyballs and successful orders-of-magnitude scaling down of the apparatus size and complexity establish an innovative tabletop method for generating, studying, and utilizing matter in planetary or stellar interiors and open doors to numerous unprecedented applications.     

Characteristics of Minimum Fluidization Velocity for Magnetite Powder used in an Air Dense Medium Fluidized Bed for Coal Beneficiation

Accurate determination of minimum fluidization velocity of medium particle is essential for proper designing and operation of an Air Dense Medium Fluidized Bed Separator for coal beneficiation. Significantly different values of minimum fluidization velocity have been obtained from different available correlations. So, it is necessary to develop a suitable correlation for this specific purpose. In this study, the minimum fluidization velocities of different size magnetite powders are investigated in a 15 cm diameter fluidized bed. Three correlations are derived from the fundamental principles for the theoretical prediction of these minimum fluidization velocities. The adequacy and reliability of each of these correlations is tested by adopting a statistical analysis approach and the most suitable correlation is selected. The predictive capability of this selected correlation is verified by using the data available in the literature. The results show that this new correlation is in very well agreement with these experimental data and shown to be applicable for practical purpose. Moreover, this study reveals that the correlation developed from the basic particle properties and bed characteristics can predict more accurate results.     

液罐基础环墙砼开裂的理论计算及成因分析

工业储罐广泛应用于各类石油化工行业。位于广西南宁市某工业区的12个巨型酒精发酵罐在试运营阶段曾发生了基础环墙的群体性开裂,产生大量的竖向裂缝,同时钢液罐与环墙发生较大角度的翘曲,影响了企业的后续生产。为了探究此类工程事故的内在原因,通过现场检测获取发酵罐与基础环墙的各项性能指标,分析了各罐的环墙混凝土强度、裂缝状况、钢筋保护层厚度及罐体垂直度等宏观特性;并以具有代表性的1号发酵罐为例,运用计算机数值模拟以及传统理论方法进行不同工况组合下的承载力验算。分析结果表明:事故由两个方面原因所致,其一是地面标高以上部分的环墙承受填砂侧压而导致;其二是由于环墙内填砂不密实,承载时引起底部钢板的变形而挤推填砂,同时引发罐体底部与环墙发生翘曲,翘曲变形又加大侧推填砂,交互作用下使得环墙的环向拉应力过大而产生竖向裂缝。研究结果可为同类工程的科学研究和设计提供参考。     

Scheme for Controlled Dense Coding via Cavity Decay

A scheme for controlled dense coding via cavity decay is proposed. In the scheme, two degenerate ground states of six-level atoms are used as the storage qubits and the leaky photons act as flying qubits. The system is robust against atomic spontaneous emissions and decoherence of cavity field. And the successful probability is nearly 1 with quantum nondemolition parity detectors and photon detectors, The scheme may be realized based on current technologies.     

五台机器自由作业的稠密时间表

对于五台机器自由作业的稠密时间表，我们证明了一个比值不等式．     

可嵌入建筑设计模型的施工顺序知识

针对以往提出的施工顺序知识表述模式在描述并行时间逻辑方面能力较弱的问题,提出了构件施工状态的概念及14种用来描述构件施工状态间时间关系的区间到区间的时间逻辑,其不仅可以描述施工活动在时间上的前后逻辑,还可以描述并行逻辑.在此基础上,提出了针对单个构件的"状态链"和针对2个构件间的"状态相互作用"的施工顺序规则,并以Express语言描述了两种顺序知识,使它们能够与工业基础类标准兼容,并可以直接嵌入到符合工业基础类标准的建筑设计模型中,使得从建筑设计模型中导出施工顺序成为可能.     

Scanning transitiometry and its applications

Scanning transitiometry combines three state variables (P,V,T) with a heat effect measured in strictly defined thermodynamic conditions. By slowly scanning one of the state variables when the other one is kept constant, the transitiometer permits to determine simultaneously two thermodynamic derivatives, always one is thermal and the other one mechanical. This study presents a number of applications of scanning transitiometry in various fields (dense liquids, supercritical systems, polymers, food systems) and presents results, often impossible to obtain with other known techniques.