含夹层矿体分采过程的数值模拟研究

在鄂西铁矿开采过程中,矿体中可能存在厚度不等的夹层,采用浅孔分采爆破开采工艺,首先剔除废石夹层,再进行落矿回采.根据相关理论,设计了夹层剔除和矿石回采的爆破参数,采用数值模拟方法,模拟爆破剔除夹层废石和矿体回采的过程.研究表明设计的爆破参数能合理爆落设计范围内的岩体,且对顶板围岩不致造成过大的损害.     

A study of gravity flow principles of sublevel caving method in dipping narrow veins

The loss and dilution of ore by sublevel caving mining method is influenced by gravity flow principles of caved granular materials (rocks). Gravity flow of broken rock (muck) in dipping narrow veins is complex. By combined use of dimensional analysis and similitude studies in physical modelling coupled with numerical simulation, this paper reports results of a study of gravity flow of muck in dipping narrow veins on the basis of granular material kinematics and dynamics. By similitude material testing, the paper analyzed the forms of granular motion during the extraction process, studies the impacts of parameters including model thickness and wall roughness on the form and size of the extraction zone. The test results reveal that depending on wall inclination (dip), the axis of granular flow shifts, and the extraction zone is intrusively asymmetric. Also, the greater the distance from the hangingwall of the model and the smoother the wall roughness, the easier the granular ore flows and the greater the volume of the extraction zone. By using PFC\(^{2D}\) modelling, the mechanical mechanism of granular ore flow is analyzed. The model results show that under conditions of dipping narrow veins, the formation and development of the extraction zone are mainly controlled by two mechanisms, namely: the disintegration of the stress arch and the erosion of granular particles. Finally, the study established a mechanistic model of granular flow in dipping narrow veins in sublevel caving mining conditions. By applying the Levenberg-Marquardt nonlinear optimization method the paper defined optimal model parameter values under different experimental conditions.     

TiO2 Electron Transport Bilayer for Highly Efficient Planar Perovskite Solar Cell

In planar perovskite solar cells, it is vital to engineer the extraction and recombination of electron–hole pairs at the electron transport layer/perovskite interface for obtaining high performance. This study reports a novel titanium oxide (TiO₂) bilayer with different Fermi energy levels by combing atomic layer deposition and spin‐coating technique. Energy band alignments of TiO₂ bilayer can be modulated by controlling the deposition order of layers. The TiO₂ bilayer based perovskite solar cells are highly efficient in carrier extraction, recombination suppression, and defect passivation, and thus demonstrate champion efficiencies up to 16.5%, presenting almost 50% enhancement compared to the TiO₂ single layer based counterparts. The results suggest that the bilayer with type II band alignment as electron transport layers provides an efficient approach for constructing high‐performance planar perovskite solar cells.     

基于面向服务架构的分布式开放控制系统

提出了一种基于面向服务架构(SOA)的分布式开放控制系统模型.整个参考模型由设备抽象层、基本控制模块层、服务层和应用层四层组成.各层内部采用面向对象的方法进行设计,各层相对独立,层间的耦合性比较小.服务层包含了所有分布式子系统的服务抽象和封装,以服务的方式供应用层使用.这种控制系统模型,开放性好,各个模块的可重用性强,开发效率高.使用这种框架,成功开发了IC工艺装备中的刻蚀机硅片传输原型系统,而且取得了很好的效果.     

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.     

Strain relaxation in lattice-mismatched epitaxy

Growth of lattice mismatched layers epitaxially on top of each other is a challenge for today's semiconductor industry. For strained layer devices, it requires that the strained layers are not relaxed through the formation of misfit dislocations. For other device applications, such as GaAs on Si, it may be desirable that the overlayers are completely relaxed and all the misfit defects are confined to the lower interfaces. This article investigates the theories on strain relaxation mechanisms in face-centered-cubic (f.c.c.) systems. The tensile layers are found to initially relax through the formation of partial dislocations, at a critical thickness about half the thickness predicted by the conventional model based on the formation of perfect misfit dislocations. This poses a stringent condition on the maximum thickness useful for tensile layer devices. We also explain the difficulties involved in preparing thick strained layers with few threading dislocations and microtwins.     

A circuit modeling of SAGCM avalanche photodiode with additional layer and nonuniform electric field profile

This paper presents a new way to improve the speed of the separated absorption grading charge multiplication avalanche photodiode by adding a new thin charge layer between absorption and grading layers. In this method, we assume a nonuniform electric field in different regions of the structure. In addition, based on carrier rate equations, a circuit model of the proposed structure is extracted. Considering the trade-offs between thicknesses of layers, we try to acquire the optimum structure by setting the physical parameters. Finally, it is shown that, in comparison with the conventional structure, considerable improvements in the gain-bandwidth product and also breakdown voltage are achieved.     

Rigorous electromagnetic analysis of dipole emission in periodically corrugated layers: the grating-assisted resonant-cavity light-emitting diode

We study the grating-assisted light-emitting diode, an LED design for high brightness based on a resonant cavity containing one- or two-dimensionally periodically corrugated layers (grating). We give in detail a generally applicable electromagnetic analysis based on the rigorous coupled-wave theory to calculate the extraction efficiency of spontaneous emission in a periodically corrugated layer structure. This general model is then specified on the grating-assisted resonant-cavity LED, showing simulated efficiencies of more than 40%.     

Improved VGG Model for Road Traffic Sign Recognition

Road traffic sign recognition is an important task in intelligent transportation system. Convolutional neural networks (CNNs) have achieved a breakthrough in computer vision tasks and made great success in traffic sign classification. In this paper, it presents a road traffic sign recognition algorithm based on a convolutional neural network. In natural scenes, traffic signs are disturbed by factors such as illumination, occlusion, missing and deformation, and the accuracy of recognition decreases, this paper proposes a model called Improved VGG (IVGG) inspired by VGG model. The IVGG model includes 9 layers, compared with the original VGG model, it is added max-pooling operation and dropout operation after multiple convolutional layers, to catch the main features and save the training time. The paper proposes the method which adds dropout and Batch Normalization (BN) operations after each fully-connected layer, to further accelerate the model convergence, and then it can get better classification effect. It uses the German Traffic Sign Recognition Benchmark (GTSRB) dataset in the experiment. The IVGG model enhances the recognition rate of traffic signs and robustness by using the data augmentation and transfer learning, and the spent time is also reduced greatly.     

III-nitride core–shell nanowire arrayed solar cells

A solar cell based on a hybrid nanowire–film architecture consisting of a vertically aligned array of InGaN/GaN multi-quantum well core–shell nanowires which are electrically connected by a coalesced p-InGaN canopy layer is demonstrated. This unique hybrid structure allows for standard planar device processing, solving a key challenge with nanowire device integration, while enabling various advantages by the nanowire absorbing region such as higher indium composition InGaN layers by elastic strain relief, more efficient carrier collection in thinner layers, and enhanced light trapping from nano-scale optical index changes. This hybrid structure is fabricated into working solar cells exhibiting photoresponse out to 2.1 eV and short-circuit current densities of ~1 mA cm(-2) under 1 sun AM1.5G. This proof-of-concept nanowire-based device demonstrates a route forward for high-efficiency III-nitride solar cells.     

基于深度神经网络的露天矿岩石爆破效果预测

装载和运输成本占到露天矿运营总成本的50%以上,而爆破后岩石破碎程度直接影响到露天矿装载和运输成本。为了得到爆破参数和岩石破碎度之间的关系,收集了平朔东露天矿爆破参数和岩石破碎度数据,使用图像识别技术大规模收集分析爆破后岩块粒径分布,基于深度神经网络研究分析爆破参数和岩石破碎度之间的关系,建立了适用于东露天矿的爆破参数和破碎度的预测模型,并对爆破参数做敏感性分析,确立了炸药单耗和孔距是主要影响因素,并分别建立了炸药单耗和孔距与岩石破碎度之间的变化关系。研究结果可以指导矿山确定合理的穿孔和爆破参数以得到最佳的岩石破碎度,从而减少露天矿运营总成本。     

Influence Diffusion Model in Multiplex Networks

The problem of influence maximizing in social networks refers to obtaining a set of nodes of a specified size under a specific propagation model so that the aggregation of the node-set in the network has the greatest influence. Up to now, most of the research has tended to focus on monolayer network rather than on multiplex networks. But in the real world, most individuals usually exist in multiplex networks. Multiplex networks are substantially different as compared with those of a monolayer network. In this paper, we integrate the multi-relationship of agents in multiplex networks by considering the existing and relevant correlations in each layer of relationships and study the problem of unbalanced distribution between various relationships. Meanwhile, we measure the distribution across the network by the similarity of the links in the different relationship layers and establish a unified propagation model. After that, place on the established multiplex network propagation model, we propose a basic greedy algorithm on it. To reduce complexity, we combine some of the characteristics of triggering model into our algorithm. Then we propose a novel MNStaticGreedy algorithm which is based on the efficiency and scalability of the StaticGreedy algorithm. Our experiments show that the novel model and algorithm are effective, efficient and adaptable.     

Data mining-based algorithm for storage location assignment in a randomised warehouse

Data mining has long been applied in information extraction for a wide range of applications such as customer relationship management in marketing. In the retailing industry, this technique is used to extract the consumers buying behaviour when customers frequently purchase similar products together; in warehousing, it is also beneficial to store these correlated products nearby so as to reduce the order picking operating time and cost. In this paper, we present a data mining-based algorithm for storage location assignment of piece picking items in a randomised picker-to-parts warehouse by extracting and analysing the association relationships between different products in customer orders. The algorithm aims at minimising the total travel distances for both put-away and order picking operations. Extensive computational experiments based on synthetic data that simulates the operations of a computer and networking products spare parts warehouse in Hong Kong have been conducted to test the effectiveness and applicability of the proposed algorithm. Results show that our proposed algorithm is more efficient than the closest open location and purely dedicated storage allocation systems in minimising the total travel distances. The proposed storage allocation algorithm is further evaluated with experiments simulating larger scale warehouse operations. Similar results on the performance comparison among the three storage approaches are observed. It supports the proposed storage allocation algorithm and is applicable to improve the warehousing operation efficiency if items have strong association among each other.     

A hierarchical approach to analyzing knowledge integration between two fields—a case study on medical informatics and computer science

As a driver in modern science, interdisciplinary research has attracted a lot of attention. Major foci are laid on exploring the relations of multiple involved disciplines as well as the knowledge structure in interdisciplinary field. However, there is still a lack of decomposing the knowledge structure of interdisciplinary field to investigate how knowledge from relevant disciplines is integrated in the field. This study proposes an approach to investigating knowledge integration relationships between two research fields from a perspective of hierarchy. Medical Informatics (MI) and its most relevant field of Computer Science (CS) are chosen in the case study. This study decomposed each keyword network of the two fields into four layers by using the K-core method, then quantified the knowledge integration relationships between different layers of the two fields together. The results present that the MI basic layer shows the strongest knowledge integration with CS, followed by the middle layer, with the detail layer the weakest. And all MI layers have the greatest breadth and strength of knowledge integration with the CS middle layer, followed by the CS marginal layer and detail layer, but with the CS basic layer the weakest. A time series analysis shows that the integration of new CS knowledge into MI is a gradual process without explosive growth and the path of knowledge integration between the two fields were identified. The proposed approach could be applied to deeply understanding the integration of one discipline knowledge by an interdisciplinary field.

     

Transparente Barriereschichten auf flexiblen Polymersubstraten

Transparent permeation barrier layers on flexible polymer substrates This paper reviews different vacuum based technologies for manufacturing transparent permeation barrier layers and layer stacks on flexible polymer substrates. With plasma assisted reactive evaporation, a cost‐efficient, highly productive process for food packaging applications is presented. Reactive dual magnetron sputtering is a technology for the deposition of oxide layers with a very low water vapor and oxygen transmission rate at a reasonable deposition rate. Many groups suggest multilayer stacks for the encapsulation of flexible electronic devices. In this paper, an all‐in‐vacuum inline concept for manufacturing such multilayers is presented. It is based on the combination of reactively sputtered barrier layers with interlayers grown by using a magnetron based PECVD process (Magnetron‐PECVD). Both, process parameters, such as deposition rate and process pressure, and important layer properties, such as morphology and the water vapor and oxygen transmission rate are compared for the different single and multi layer technologies.     

多层岩盐矿爆破切割压裂工艺

多层岩盐矿（含芒硝矿）的开采，普遍采用分层建井回采工艺，即每回采一层盐，均需分别建一组回采井，回采费用高。该文介绍一种新的回采工艺－爆破切割全程裸露盐层，其特点是建一组回采井，采用爆破切割方法，将所有盐层裸露并予以回脂，大大降低回采费用，提高回采速度。     

Planar elastic laminates and their homogenization

Summary The state of stress and deformation of a planar elastic-homogeneous transversely isotropic thick layer in the case of plane and axisymmetric strain respectively is determined in a systematic and uniform manner using integral transforms and transfer matrices. Next, a laminate with an arbitrary number of different layers is considered without any simplifying assumptions. Then we analyze a periodic structure consisting of many thin and identical layer groups by means of a suitable homogenization, where a layer group contains two or more different transversely isotropic homogeneous basic layers. As an example exact closed form solutions for a periodically layered half space are evaluated. The well known result, that a medium which is composed of alternating thin layers of two different elastic-isotropic substances is elastostatically equivalent to a homogeneous transversely isotropic medium is extended to the above mentioned more general case. Further, the in-plane normal stresses which are discontinuous for a finite layering are evaluated in addition to the smeared ones which are continuous and correct only in the limit of a vanishing thickness of the individual layers. The explicit knowledge of the resultant elastic constants (called effective ones) turns out to be dispensable; rather, the effective material parameters (defined in this paper) which are the weighted sums of the material parameters of the basic layers are proved to be relevant. Nevertheless, for the purpose of comparison with some published results the effective elastic constants, especially for a layer group consisting of two different elastic-isotropic substances, are evaluated additionally.Dedicated to Prof. Gallus Rehm on the occasion of his 75th birthday     

A Combined Analytic,Numeric, and Experimental Investigation Performed on NiTi/NiTiCu Bi‐Layer Composites under Tensile Loading

Adjusting mechanical behavior and controlling deformation parameters are significant tasks in designing shape memory components. In this paper, an analytical model describes the deformation behavior of NiTi/NiTiCu bi‐layer composites under tensile loading. Different deformation stages are considered based on single mechanical behavior at each stage. Closed‐form equations are derived for stress–strain variations of bi‐layer composites under uniaxial loading–unloading. Bi‐layer composites made via the diffusion bonding method from single layers of NiTi alloy with a composition of Ti‐50.7 at.% Ni, as an austenitic layer, and Ti‐45 at% Ni‐5 at% Cu, as a martensitic layer, are produced by the vacuum arc remelting technique. The tensile behavior of single‐ and bi‐layers is investigated by using loading–unloading experiments to find the nominal stress–strain curves. Numerical simulations are also done by employing Lagoudas constitutive model to simulate stress–strain diagrams. The solutions of the analytical method presented are validated by using the numerical simulations as well as the experimental results. With regard to the results obtained from the analytical modeling, the numerical simulations, and the experiments, it is evident that the bi‐layer composites with different thickness ratios provide adjustable mechanical behavior that can be considered in different application designs, for example, actuators equipped with shape memory components.

     

Development of a service evolution map for service design through application of text mining to service documents

As digital convergence has proliferated and products have become smarter, various service concepts have emerged based on the capabilities of products. It has become a main concern to illuminate historical changes and status of service concepts according to the utilisation of product elements to provide valuable information for service development. However, a lacuna still remains in the literature regarding a systematic and quantitative approach on this problem. This study proposes a service evolution map as a tool for analysing the evolutionary paths of service concepts based on the utilisation of product elements. The proposed service evolution map consists of two layers with the time dimension: a product element layer for the utilisation of product elements and a service concept layer for the evolutionary paths of service concepts. Based on the service documents describing what the services are, text mining, co-word analysis, and modified formal concept analysis are employed to develop the product element and service concept layers, respectively. A case study of mobile application services is presented to illustrate the proposed approach. This study is expected to be a basis of future research on the interaction between products and services and service concept design based on the creative utilisation of product elements.     

Interpreting strain bursts and size effects in micropillars using gradient plasticity

Size effects and strain bursts that are observed in compression experiments of single crystalline micropillars are interpreted using a gradient plasticity model that can capture the process of sequential slip and heterogeneous yielding of thin material layers. According to in situ experiments during compression sub-grains and significant strain gradients develop, while deformation occurs through slip layers in the gauge region. In the multilayer strain gradient model, the higher order stress is discontinuous across the interface between a plastic layer and an elastic layer, but it becomes continuous across the interface between two plastic layers. Strain bursts occur when two neighboring layers yield. Based on this hypothesis the experimental stress-strain curves with strain bursts observed in micropillars can be fitted by properly selecting the number of layers that yield and the ratio of the internal length over the specimen size; the modulus and the yield stress are obtained from the experimental curves while the hardening modulus evolves during deformation based on the dislocation mechanisms.