Influence of different mining layouts on the mechanical properties of coal

Non-pillar mining,top-coal caving and protected coal seam mining are the most popular mining methods in coal exploitation,and the different mining layouts will change the stress state and failure mechanism of coal in front of the working face.In this paper,mining-induced mechanical behaviors under three mining layouts have been simulated in the laboratory to investigate the effects of mining layouts on the deformation and strength of coal.Furthermore,the coal failure mechanism under different mining layouts is analyzed microscopically.The experimental results indicate that the stage characteristics of the coal deformation are obvious.Under the serial action of non-pillar mining,top-coal caving and protected coal seam mining layouts,the values of radial deformation,volume strain and Poisson's ratio increase,while the peak strength and deformation modulus decrease at the same buried depth,and the peak strength under non-pillar mining,top-coal caving and protected coal seam mining is about 3.0,2.5 and 2.0 times of the initial confining pressure,respectively.The results also indicate that the trend of the coal deformation decreases with the increase of the buried depth under the same mining layout,while the strength and deformation modulus increase,and the failure mechanism under three mining layouts is dominated with shear/tensile failure.

Numerical simulation of spatial distributions of mining-induced stress and fracture fields for three coal mining layouts

In this study, the spatial distributions of stress and fracture fields for three typical underground coal mining layouts, Le, non-pillar mining （NM）, top-coal caving mining （TCM） and protective coal-seam mining （PCM）, are modeled using discrete element software UDEC, The numerical results show that different mining layouts can lead to different mining-induced stress fields, resulting in diverse fracture fields, For the PCM, the mining influenced area in front of the mining faces is the largest, and the stress concentration factor in front of the mining faces is the lowest, The spatial shapes of the mining-induced fracture fields under NM, TCM and PCM differ, and they are characterized by trapezoidal, triangular and tower shapes, respectively, The fractal dimensions of mining-induced fractures of the three mining layouts decrease in the order of PCM, TCM and NM, It is also shown that the PCM can result in a better gas control effect in coal mines with high outburst potential, The numerical results are expected to provide a basis for understanding of mining-induced gas seepage fields and provide a reference for high- efficiency coal mining,

Functional Features and Layouts of Yangzhou Residential Gardens in the Late Qing Dynasty and the Early Republic of China: A Case Study of Residential Gardens of Officials, Merchants and Literati

On the basis of analyzing socio-economic structures, social classes and their relations in the late Qing Dynasty and the early Republic of China, this paper took residential gardens of three principal groups(officials, merchants and literati) for example, analyzed functional features and layouts of the gardens, explored artistic characteristics and cultural connotations of the local residential gardens, so as to provide references for the conservation and construction of historic and cultural cities, design and expression of modern urban livable spaces.

Optimization of Building Layouts to Increase Wind Turbine Power Output in the Built Environment Assumed to Be Installed at Fukushima City and Tsu City in Japan

It is very important to consider proper intelligent integration and locations of renewable energy sources into the built environment for developing smart cities. Wind speed distribution study in the built environment is very essential for analyzing the wind turbine performance located in the built environment. In this work, the building layout like nozzle is proposed and the objective is to optimize the building layout for increasing electrical energy output of wind turbine, assumed to be installed in actual cities of Japan. The wind speed distribution across buildings is numerically simulated by using CFD-ACE+. Wind turbine power output is estimated using the power curve of a real commercial wind turbine and wind speed distribution is simulated using CFD software. The meteorological data of Fukushima city and Tsu city of Japan are utilized for evaluating the wind speed distribution profile across the building and for finding the electrical energy output from wind turbine. The proposed building models, which have the angle between two buildings like nozzle of 90°, 135° and 180°, can provide the wind acceleration at the back of buildings for the wind blowing from the main wind direction and the angle of 135°is optimum building layout. In the case of installing the proposed building model in Fukushima city and Tsu city, the wind energy output in winter season is higher while that in summer season is lower irrespective of the buildings’ angle. The interaction between the change in frequency distribution of wind speed and direction throughout the year and the location of open tip of building model decides the power generation characteristics of the proposed building model.

3D reconstruction method and connectivity rules of fracture networks generated under different mining layouts

In current research,a series of triaxial tests,which were employed to simulate three typical mining layouts(i.e.,top-coal caving,non-pillar mining and protected coal seam mining),were conducted on coal by using MTS815 Flex Test GT rock mechanics test system,and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruction techniques.This work aimed at providing a detail description on the micro-structure and fractureconnectivity characteristics of rupture coal samples under different mining layouts.The results show that:(i)for protected coal seam mining layout,the coal specimens failure is in a compression-shear manner and oppositely,(ii)the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts.By investigating the connectivity features of the generated fractures in the direction ofσ_1,under different mining layouts,it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.

Study on Urban Forest Construction Concepts and Layouts in Taizhou City

Taizhou is an economically-developed port city on the golden coastline of China, characterized by typical coastal and combined green cores, mountains and waters, and special plants. This paper analyzed natural conditions and city features of Taizhou, assessed current construction of local urban forests, and proposed pertinent construction concepts in view of diversifi ed needs of urban development on forest construction. On the basis of the city development, principles of urban forest layout were put forward, and the overall structure of "one core, one belt, two rings, three corridors, four groups, fi ve windows, and multiple bases" was given for the construction of urban forest in coastal landscape cities, in addition, the effect and feasibility of the layout were analyzed.

Air-vent layouts and water-air flow behaviors of a wide spillway aerator

A spillway aerator should guarantee favorable flow conditions in the coupled water-air system even if the aerator is unconventionally wide. Eight air-vent configurations are devised and incorporated into a 35-m wide chute aerator for a generalized study. Computational fluid dynamics(CFD) simulations are performed to explore their effects on water-jet and air-cavity features. The Re-normalisation group(RNG) k-ε turbulence model and the two-fluid model are combined to predict the two-phase flow field. The results demonstrate appreciable influences of the vent layouts on the water-air flow. The air vents stir the air motion and re-distribute the cavity air pressure. Once the vent layout is modified, reciprocal adjustments exist between the jet behavior and air-pressure field in the cavity, thus leading to considerable differences in air-flow rate, jet-trajectory length, vent air-flow distribution across the chute, etc. The large width plays a discernable role in affecting the aerated flow. Telling differences exist between the near-wall region and the central part of the chute. To improve the duct pressure propagation, a gradual augment of the vent area should be assigned towards the chute center. Relative to single-slot vents across the flow, the layouts with segregated vents gain by comparison. A designer should see to it that a vented aerator operates satisfactorily for a given range of flow discharges.

Some possible station layouts and characteristics of evacuated tube transportation

Since Maglev vehicles will run in a closed vacuum tube,the layout of the terminal stations of evacuated tube transportation（ETT） will differ from the traditional railway stations.This paper deals with some possible station layouts of ETT,e.g.,a station with an airlock,a station without an airlock,above ground and underground stations,and stations with either level arrayed or rotation platforms.Then different station layouts are compared,and characteristics of each are analyzed.Finally,a more secure mode for ETT station layouts is suggested,which can be the basis for future ETT station layout and designs.

Wind tunnel investigation of different engine layouts of a blended-wing-body transport

A 2%scale,cruising version of a 450-seat class Blended-Wing-Body(BWB)transport was tested in the China Aerodynamic Research and Development Center’s FL-262.4-by-2.4-meter subsonic wind tunnel.The focus of the wind tunnel test was to investigate the aerodynamic performance of the latest BWB transport design,which would also aid in choosing a final engine arrangement in the three most potential engine integration layouts.The wind tunnel model can be tested with and without the nacelle and has three sets of different nacelle/tail integration positions.Computational Fluid Dynamics(CFD)simulations were performed in engine-aircraft integration design to find appropriate nacelle installing parameters of each layout.The comparison of CFD with experimental results shows good agreement.Wind tunnel measurements indicate that the tail-mounted engine layout produces the minimum drag penalty,while the fuselage-mounted engine layout increases drag the most.Experimental pressure measurement illustrates the effect of nacelle integration on the wing-body surface pressure distribution.This experimental and numerical research provides a reference for future BWB Propulsion-Airframe Integration(PAI)design.

Ensemble machine learning framework for daylight modelling of various building layouts

The application of machine learning(ML)modelling in daylight prediction has been a promising approach for reliable and effective visual comfort assessment.Although many advancements have been made,no standardized ML modelling framework exists in daylight assessment.In this study,625 different building layouts were generated to model useful daylight illuminance(UDI).Two state-of-the-art ML algorithms,eXtreme Gradient Boosting(XGBoost)and random forest(RF),were employed to analyze UDI in four categories:UDI-f(fell short),UDI-s(supplementary),UDI-a(autonomous),and UDI-e(exceeded).A feature(internal finish)was introduced to the framework to better reflect real-world representation.The results show that XGBoost models predict UDI with a maximum accuracy of R^(2)=0.992.Compared to RF,the XGBoost ML models can significantly reduce prediction errors.Future research directions have been specified to advance the proposed framework by introducing new features and exploring new ML architectures to standardize ML applications in daylight prediction.

Influence of yaw damper layouts on locomotive lateral dynamics performance:Pareto optimization and parameter analysis

High-speed locomotives are prone to carbody or bogie hunting when the wheel-rail contact conicity is excessively low or high.This can cause negative impacts on vehicle dynamics performance.This study presents four types of typical yaw damper layouts for a high-speed locomotive(Bo-Bo)and compares,by using the multi-objective optimization method,the influences of those layouts on the lateral dynamics performance of the locomotive;the linear stability indexes under lowconicity and high-conicity conditions are selected as optimization objectives.Furthermore,the radial basis function-based highdimensional model representation(RBF-HDMR)method is used to conduct a global sensitivity analysis(GSA)between key suspension parameters and the lateral dynamics performance of the locomotive,including the lateral ride comfort on straight tracks under the low-conicity condition,and also the operational safety on curved tracks.It is concluded that the layout of yaw dampers has a considerable impact on low-conicity stability and lateral ride comfort but has little influence on curving performance.There is also an important finding that only when the locomotive adopts the layout with opening outward,the difference in lateral ride comfort between the front and rear ends of the carbody can be eliminated by adjusting the lateral installation angle of the yaw dampers.Finally,force analysis and modal analysis methods are adopted to explain the influence mechanism of yaw damper layouts on the lateral stability and differences in lateral ride comfort between the front and rear ends of the carbody.

Numerical modeling of dam-break flood through intricate city layouts including underground spaces using GPU-based SPH method

This paper applies the meshfree Smoothed Particle Hydrodynamics （SPH） method with Graphical Processing Unit （GPU） parallel computing technique to investigate the highly complex 3-D dam-break flow in urban areas including underground spaces. Taking the advantage of GPUs parallel computing techniques, simulations involving more than 107 particles can be achieved. We use a virtual geometric plane boundary to handle the outermost solid wall in order to save considerable video card memory for the GPU computing. To evaluate the accuracy of the new GPU-based SPH model, qualitative and quantitative comparison to a real flooding experiment is performed and the results of a numerical model based on Shallow Water Equations （SWEs） is given with good accuracy. With the new GPU-based SPH model, the effects of the building layouts and underground spaces on the propagation of dambreak flood through an intricate city layout are examined.

Optimization Design of the Multi-Layer Cross-Sectional Layout of An Umbilical Based on the GA-GLM

Marine umbilical is one of the key equipment for subsea oil and gas exploitation,which is usually integrated by a great number of different functional components with multi-layers.The layout of these components directly affects manufacturing,operation and storage performances of the umbilical.For the multi-layer cross-sectional layout design of the umbilical,a quantifiable multi-objective optimization model is established according to the operation and storage requirements.Considering the manufacturing factors,the multi-layering strategy based on contact point identification is introduced for a great number of functional components.Then,the GA-GLM global optimization algorithm is proposed combining the genetic algorithm and the generalized multiplier method,and the selection operator of the genetic algorithm is improved based on the steepest descent method.Genetic algorithm is used to find the optimal solution in the global space,which can converge from any initial layout to the feasible layout solution.The feasible layout solution is taken as the initial value of the generalized multiplier method for fast and accurate solution.Finally,taking umbilicals with a great number of components as examples,the results show that the cross-sectional performance of the umbilical obtained by optimization algorithm is better and the solution efficiency is higher.Meanwhile,the multi-layering strategy is effective and feasible.The design method proposed in this paper can quickly obtain the optimal multi-layer cross-sectional layout,which replaces the manual design,and provides useful reference and guidance for the umbilical industry.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

The study of lithographic variation in resistive random access memory

Reducing the process variation is a significant concern for resistive random access memory(RRAM).Due to its ultrahigh integration density,RRAM arrays are prone to lithographic variation during the lithography process,introducing electrical variation among different RRAM devices.In this work,an optical physical verification methodology for the RRAM array is developed,and the effects of different layout parameters on important electrical characteristics are systematically investigated.The results indicate that the RRAM devices can be categorized into three clusters according to their locations and lithography environments.The read resistance is more sensitive to the locations in the array(~30%)than SET/RESET voltage(<10%).The increase in the RRAM device length and the application of the optical proximity correction technique can help to reduce the variation to less than 10%,whereas it reduces RRAM read resistance by 4×,resulting in a higher power and area consumption.As such,we provide design guidelines to minimize the electrical variation of RRAM arrays due to the lithography process.

Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

GNN Representation Learning and Multi-Objective Variable Neighborhood Search Algorithm for Wind Farm Layout Optimization

With the increasing demand for electrical services,wind farm layout optimization has been one of the biggest challenges that we have to deal with.Despite the promising performance of the heuristic algorithm on the route network design problem,the expressive capability and search performance of the algorithm on multi-objective problems remain unexplored.In this paper,the wind farm layout optimization problem is defined.Then,a multi-objective algorithm based on Graph Neural Network(GNN)and Variable Neighborhood Search(VNS)algorithm is proposed.GNN provides the basis representations for the following search algorithm so that the expressiveness and search accuracy of the algorithm can be improved.The multi-objective VNS algorithm is put forward by combining it with the multi-objective optimization algorithm to solve the problem with multiple objectives.The proposed algorithm is applied to the 18-node simulation example to evaluate the feasibility and practicality of the developed optimization strategy.The experiment on the simulation example shows that the proposed algorithm yields a reduction of 6.1% in Point of Common Coupling(PCC)over the current state-of-the-art algorithm,which means that the proposed algorithm designs a layout that improves the quality of the power supply by 6.1%at the same cost.The ablation experiments show that the proposed algorithm improves the power quality by more than 8.6% and 7.8% compared to both the original VNS algorithm and the multi-objective VNS algorithm.

Analysis on Typical Spatio-temporal Characteristics of Open-cast Mining and Its Countermeasures

In order to deal with the special spatio-temporal environmental changes encountered in the process of open-cast mining,taking Huolinhe No.1 Open-cast Mine as the research object,this paper studied its typical problems in river reconstruction and cultural relics protection.The study focused on eight key core aspects,including the design optimization of the spatial layout of the mining area,the accurate estimation of the mineral resources reserves,the scientific theoretical demonstration of the mining scale,the fine analysis and calculation of the stripping ratio,the comprehensive consideration of the transport distance and efficiency,the accurate judgment of the best time for the implementation of the transformation,the analysis and evaluation of the slope stability,and the overall planning of the production system.The results show that the extracted problem-solving strategies and scheme system for special mining conditions can not only provide specific and practical guidance for Huolinhe No.1 Open-cast Mine,but also serve as a valuable reference and practical reference for other open-cast mine enterprises facing similar challenges.

Study of CEPC performance with different collision energies and geometric layouts

The Circular Electron-Positron CoUider （CEPC） is one of the largest projects planned for high energy physics in China. It would serve first as a Higgs factory and then upgrade to a hadron collider. In this paper we give the 50 km and 100 km design for both single ring and double ring schemes, including Z boson, W boson and Higgs boson, by using an optimized method. Also, we give the potential of CEPC running at the Z and W poles. We analyse the relationship of luminosity with circumference and filling factor, which gives a way to evaluate the choice of geometry, and compare the nominal performances of CEPC-SPPC, LHC and FCC.

Analysis of Municipal Water Supply and Drainage Pipe Design Technology

The quality and safety of residents’water rely heavily on the design of municipal water supply and drainage pipes.Therefore,this paper aims to enhance the optimization of municipal water supply and drainage pipe design by focusing on design requirements,principles,and key elements.Drawing from relevant design optimization experiences,technology advancements,and optimization measures,the research will analyze and consolidate the essential aspects of municipal water supply and drainage pipe design.The goal is to fundamentally elevate the quality standards of these designs,ensuring they meet the criteria for engineering project excellence.Through this comprehensive approach,we aim to contribute to the improvement and sustainability of water supply and drainage systems,safeguarding the well-being of residents.