Stability analysis of longwall top-coal caving face in extra-thick coal seams based on an innovative numerical hydraulic support model

The relationship between support and surrounding rock is of great significance to the control of surrounding rock in mining process.In view of the fact that most of the existing numerical simulation methods construct virtual elements and stress servo control to approximately replace the hydraulic support problem,this paper establishes a new numerical model of hydraulic support with the same working characteristics as the actual hydraulic support by integrating numerical simulation software Rhino,Griddle and FLAC3D,which can realize the simulation of different working conditions.Based on this model,the influence mechanism of the supporting strength of hydraulic support on surrounding rock stress regulation and coal stability in front of the top coal caving face in extra thick coal seam were researched.Firstly,under different support intensity,the abutment pressure of the bearing coal and the coal in front of it presents the “three-stage”evolution characteristics.The influence range of support intensity is 15%–30%.Secondly,1.5 MPa is the upper limit of impact that the support strength can have on the front coal failure area.Thirdly,within a displacement range of 2.76 m from the coal wall,a support strength of1.5 MPa provides optimal control of the horizontal displacement of the coal.

LED-CAVE沉浸式虚拟现实技术在建筑EPC项目中的应用

研究一种基于LED-CAVE的沉浸式虚拟现实技术,结合建筑信息模型(BIM)技术,通过建(构)筑物及其环境的三维BIM模型与五面LED-CAVE显示系统进行整合,实现多人沉浸式的场景漫游功能。通过人机交互逻辑的开发与外部系统集成,应用于建筑EPC项目的设计、采购、施工等各个领域,可以实现方案设计的沉浸式体验与交流,真正实现所见即所得,提升方案设计的效率,加快方案设计的决策,为旧街区的改造提升方案设计提供有效的辅助和指导作用。

Urban Spatial Form Optimization Strategies Based on the Principle of Climate Adaptability of Regional Architecture: A Case Study of Traditional Cave Dwelling Villages in Northern Shaanxi Province

A multitude of climate-adaptive design approaches are embedded in regional architecture,which have a positive impact on addressing the deformed development of urban spatial patterns and the dual challenges of climate and resources.This paper examines the principles of climate adaptability embedded in the site layout and spatial organization characteristics of traditional cave dwelling villages in northern Shaanxi Province.The extracted climate adaptability principles are summarized,and the resulting design strategies that are well-suited to the contemporary urban space form are presented.Through analysis,it can be observed that traditional cave dwelling villages in northern Shaanxi are predominantly situated on south-facing slopes in proximity to water at low altitudes.These villages are characterized by compact building groups and east-west development,which is constrained by the elements of mountains and rivers.A two-level street system is generated,comprising streets parallel to the contour line and roadways perpendicular to the contour line.This results in the formation of a courtyard form enclosed by mountains.Such site layout and spatial organization exhibit excellent climate adaptability with regard to heat,ventilation,and wind storage.In light of the aforementioned considerations,the following urban spatial form design strategies are put forth:①the topographic height difference can be exploited to obtain sufficient sunshine;②the group shape can be optimized in order to reduce building energy consumption;③the best orientation of the building can be chosen to take account of both winter and summer conditions;④the height and length can be combined in order to form natural masking;⑤the D/H ratio of streets and roadways should be controlled to achieve a balance between heat gain and cooling of groups;⑥vents should be set appropriately to optimize group ventilation;⑦climate buffers should be established to increase the level of climate response.

沉浸式技术CAVE在宋韵文化及历史复现上的应用

在有关政策引导下,以CAVE(洞穴状自动虚拟环境)为代表的各类沉浸式技术逐渐进入公共文化教育空间,改进原有单一、单向的展陈模式,辅助传统文化和历史复现。以宋韵文化为例,CAVE系统的应用影响了人们对历史及当下的空间感知和文化认同。人们通过集体观看,在熟悉的现代性“酷”的技术视觉与文化中,认识到个体在历史中的血脉延续性,从而获得沉浸式的文化认同,维续了中华民族这一身份的连贯一致。进而,这一共享的文化认同通过创意产业带动经济发展,将文化价值转化为经济价值。

Analysis of the Application of Span-Bridge Technology for Building Highway Tunnels that Go Over Solutional Caves

This article presents a real engineering project showcasing the application of span-bridge construction technology for building a highway that goes over a solutional cave.An overview of the project and the details of applying this technology in highway construction are provided.Besides,strategies for enhancing its construction quality are also proposed.The objective of this analysis is to improve the safety and quality of similar projects.

Forecasting vulnerability of deep extraction level excavations to drawinduced cave loads

Block and panel caving methods are increasingly used for mining of large and strong orebodies at large depths below the ground surface (>1 km). This paper focuses on the production phase of caving when the extraction level is fully developed and subjected to the weight of overlying caved material. A limit equilibrium solution for estimation of cave loads is critically reviewed and combined with existing empirical tools in order to forecast extraction level performance under cave loading. The analysis results, presented in nomogram form, suggest that the risk of severe squeezing of extraction level tunnels does not increase with cave depths below 500-1000 m due to the beneficial effects of arching. Under normal extraction ratios (ER = ~50%), severe squeezing experienced from cave loads in deep mines appears to be unlikely in all but the weakest rock masses (σcm < 5 MPa, where σcm is the rock mass global strength), even with poor draw control or low drawpoint availability. The likelihood of severe squeezing is greater when large draw areas (HR = 50-75 m, where HR is the hydraulic radius) are combined with low drawpoint availability or poor draw control and locally higher extraction ratios (ER = ~75%), even in better quality rock (σcm = 5-10 MPa). The analysis results are back-analyzed with the extraction level performance before and after a doubling production of rate and draw area at the deep ore zone (DOZ) mine in Indonesia. The extraction level conditions predicted by the nomograms correlate well with the experience at the DOZ, in which extraction level damage increases significantly over the production rampup, accompanied by a significant drop in drawpoint availability.

Stable Carbon Isotope Variations in Cave Percolation Waters and their Implications in Four Caves of Guizhou, China

Monitoring and sampling of main plants, soil CO2, soil water, bedrock, spring water, drip water and its corresponding speleothem were performed at four cave systems of Guizhou, Southwest China, from April 2003 to May 2004, in order to understand stable carbon isotope ratios variations of dissolved inorganic Carbon （DIC） in cave percolation waters （δ13CDIC） and their implications for paleoclimate. Stable carbon isotopic compositions and ions （Ca, Mg, Sr, SO4, CI etc.） were measured for all samples. The results indicate that there are significant differences among the δ13CDIC values from inter-cave, even inter-drip of intra-cave in the four caves. The δ13CDIC values from the Liangfeng Cave （LFC） is lightest among the four caves, where vegetation type overlying the cave is primary forest dominated by tall trees with lighter average δ13C value （-29.9‰）. And there are remarkable differences in δ13CDIC values of different drip waters in the Qixing Cave （QXC） and Jiangjun Cave （JJC）, up to 6.9‰ and 7.8‰, respectively. Further analyses show that the δ13CDIC values in cave drip waters are not only controlled by vegetation biomass overlying the cave, but also hydro-geochemical processes. Therefore, accurate interpreting of δ13C recorded in speleothems cannot be guaranteed if these effects of the above mentioned factors are not taken into consideration.

Distribution of the Ordovician Fluid in the Tahe Oilfield and Dynamic Response of Cave System S48 to Exploitation

The Tahe Oilfield is a complex petroleum reservoir of Ordovician carbonate formation and made up of spatially overlapping fracture-cavity units. The oilfield is controlled by a cave system resulting from structure-karst cyclic sedimentation. Due to significant heterogeneity of the reservoir, the distribution of oil and water is complicated. Horizontally, a fresh water zone due to meteoric water can be found in the north part of the Akekule uplift. A marginal freshening zone caused by water released from mudstone compaction is found at the bottom of the southern slope. Located in a crossformational flow discharge zone caused by centripetal and the centrifugal flows, the main part of the Tahe Oilfield, featuring high salinity and concentrations of CI^- and K^＋＋Na^＋, is favorable for accumulation of hydrocarbon. Three types of formation water in the Tahe Ordovician reservoir are identified： （1） residual water at the bottom of the cave after oil and gas displacement, （2） residual water in fractures/pores around the cave after oil and gas displacement, and （3） interlayer water below reservoirs. The cave system is the main reservoir space, which consists of the main cave, branch caves and depressions between caves. Taking Cave System S48 in the Ordovician reservoir as an example, the paper analyzes the fluid distribution and exploitation performance in the cave system. Owing to evaporation of groundwater during cross-formational flow, the central part of the main cave, where oil layers are thick and there is a high degree of displacement, is characterized by high salinity and Br^- concentration. With high potential and a long stable production period, most wells in the central part of the main cave have a long water-free oil production period. Even after water breakthrough, the water content has a slow or stepwise increase and the hydrochemistral characteristics of the produced water in the central part of the main cave are uniform. From the center to the edge of the main cave, displacement and enrichment of oil/gas become weaker, residual water increases, and the salinity and concentration of Br^- decrease. At the edge of the main cave, although the wells have a high deliverability at the beginning with a short stable production period and water-free production period. After water breakthrough, the pressure and deliverability drop quickly, and the water content rises quickly. The hydrochemistral characteristics of the produced water are relatively uniform. Wells in the branch caves have a relatively low deliverability at the beginning, with a short stable production period. Water breakthrough appears quickly and then the pressure and deliverability drop quickly. The salinity and concentrations of CI^-and K^＋＋Na^＋ are usually fluctuant or descend slowly in the produced water. Wells in low areas of ancient karst have a low deliverability and a short stable production period. The yield drops quickly and the water content is high, while the characteristics of the produced water may vary significantly well to well. The salinity and concentrations of CI^-and K^＋＋Na^＋ in the produced water are usually fluctuant with a precipitous decline.

The first cavefish in the Dinaric Karst?Cave colonization made possible by phenotypic plasticity in Telestes karsticus

Cave animals are an excellent model system for studying adaptive evolution.At present,however,little is known about the mechanisms that enable surface colonizers to survive in the challenging environment of caves.One possibility is that these species have the necessary genetic background to respond with plastic changes to the pressures of underground habitats.To gain insight into this process,we conducted a comparative study with the fish species Telestes karsticus,which occurs in a hydrological system consisting of an interconnected stream and a cave.Results showed that T.karsticus resided year-round and spawned in Sušik cave,making it the first known cavefish in the Dinaric Karst.Cave and surface populations differed in morphological and physiological characteristics,as well as in patterns of gene expression without any evidence of genetic divergence.To test whether observed trait differences were plastic or genetic,we placed adult fish from both populations under light/dark or constant dark conditions.Common laboratory conditions erased all morphometric differences between the two morphs,suggesting phenotypic plasticity is driving the divergence of shape and size in wild fish.Lighter pigmentation and increased fat deposition exhibited by cave individuals were also observed in surface fish kept in the dark in the laboratory.Our study also revealed that specialized cave traits were not solely attributed to developmental plasticity,but also arose from adult responses,including acclimatization.Thus,we conclude that T.karsticus can adapt to cave conditions,with phenotypic plasticity playing an important role in the process of cave colonization.

Distant metastasis of hepatocellular carcinoma to Meckel’s cave and cranial nerves:A case report and review of literature

BACKGROUND Metastasis occurs as a late event in the natural history of hepatocellular carcinoma(HCC),and most patients die of liver failure attributed to the tumor supplanting the liver.Conversely,the brain is a less common metastatic site.CASE SUMMARY We describe a rare case of hepatitis C virus-related multiple HCC metastasizing to the cavernous sinus,Meckel’s cave,and the petrous bone involving multiple cranial nerves in an 82-year-old woman.At admission imaging studies including Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging(MRI)revealed multiple HCC nodules in both right and left lobes.Ultrasound guided biopsy of the left lobe revealed moderately differentiated HCC.Molecular targeted therapy with Lenvatinib(8 mg/d for 94 d,per os)and Ramucirumab(340 mg/d and 320 mg/d,two times by intravenous injection)were administered for 4 mo,resulting in progression of the disease.Three months after the start of molecular target therapy,the patient presented with symptoms of hyperalgesia of the right face and limited abduction of the right eye,indicating disturbances in the right trigeminal and abducens nerves.Brain MRI disclosed a mass involving the cavernous sinus,Meckel’s cave and the petrous bone.Contrast-enhanced MRI with gadolinium-chelated contrast medium revealed a well-defined mass with abnormal enhancement around the right cavernous sinus and the right Meckel’s cave.CONCLUSION The diagnosis of metastatic HCC to the cavernous sinus,Meckel’s cave,and the petrous bone was made based on neurological findings and imaging studies including MRI,but not on histological examinations.Further studies may provide insights into various methods for diagnosing HCC metastasizing to the craniospinal area.

Environmental monitoring in the Kaklik Cave (Denizli, Turkey)

The formation of caves is the special environment of our earth. Caves with dim natural light and lighted hypogean environments, have been found various organism. The Kaklik Cave located tectonic lines and has a very different way of formation when compare with many other same karstic formation caves. The Kaklik Cave is located in the area of Kaklik town in Honaz area and in Denizli province. The cave is one of the 54 cave opened to tourism in Turkey and endanger. In this study the cave climate, hydrol?ogy and biology were studied. The cave has specific species due to this formation, the entrance is wide and open to the sky, that makes the sunlight could go through a very wide area and cause of it is very rich about hydrology, these effects;provide a very high biodiversity to the cave. The cave has very important touristic potential because of the continuously growing travertine, geographical position, availability of access and natural beauties. The wrong artificial lightning badly changes the natural structure of the cave. This artificial lightning causes the biofilm layer and changing on the color of the travertine.

Animal life in the chemoautotrophic ecosystem of the hypogenic groundwater cave of Ayyalon (Israel): A summing up

Seven years after the discovery of the chemoautotrophic sulfidic groundwater site of the Ayyalon cave, its macrofauna can be fully reviewed. It consists of six endemic stygobiont and troglo-biont crustaceans and other arthropods and two species still with unclear status. The taxonomic list is followed by brief discussions on the systematics of the species as well as by a few comments concerning the eventual broader zoogeographical and speleological implications of the Ayyalon faunistic findings, as they appeared in literature.

Research on Tourism Development Strategy of Zhaoqing Seven Star Cave Scenic Area in the Context of Guangdong-Hong Kong-Macao Greater Bay Area

The national strategy of"Guangdong-Hong Kong-Macao Greater Bay Area"has replaced the original Pearl River Delta economic circle.As one of them,the economic development of Zhaoqing City ushered in a historic opportunity.Other cities in Greater Bay Area provide sufficient tourist resources for the development of Zhaoqing’s tourism industry.Under the new situation,Seven Star Cave,the leading scenic spot in Zhaoqing,should firmly grasp the national strategic dividend of the"Guangdong-Hong Kong-Macao Greater Bay Area",accelerate the transformation and upgrading,and enhance the market competitiveness.In this paper,the data are collected by nominal group technique,and are integrated into SWOT matrix for analysis.The development strategy of Zhaoqing Seven Star Cave Scenic Area is obtained by matching internal and external factors.

思维导图在高中英语新知识教学中的实践应用——以Unit 5 A Visit to the Zhoukoudian Caves为例

传统"灌输式"教学模式下,大部分学生采取"死记硬背"的学习方式,且学习效果不甚理想,严重影响了学生学习的积极性,而在基础教育改革深入开展的今天,思维导图现身于高中英语课堂,并取得理想的教学效果。英语作为一门语言学科,要想提高学习效率,就要帮助学生形成合理的知识体系,这样既能够降低学生学习的枯燥性,又能够提高学生学习的效率与质量。为此,笔者以"Unit 5 A Visit to the Zhoukoudian Caves"为例,探究了思维导图在高中英语新知识教学中的实践应用。

Reproductive seasonality of Astyanax mexicanus cavefish

DEAR EDITOR,The characiform fish Astyanax is a well-studied model system for understanding evolutionary development and genomics in cave biology.Nonetheless,considerable gaps remain in our understanding of its field ecology.Here,we conducted a fouryear field study and found that while cavefish spawned yearround,reproductive peaks occurred in January to February.

A Darcy-Law Based Model for Heat and Moisture Transfer in a Hill Cave

A hill can be regarded as an environmental carrier of heat.Water,rocks and the internal moisture naturally pre-sent in such environment constitute a natural heat accumulator.In the present study,the heat and moisture trans-fer characteristics in a representative hill cave have been simulated via a method relying on the Darcy’s law.The simulations have been conducted for both steady and unsteady conditions to discern the influence of permeability and geometric parameters on the thermal and moisture transfer processes.The reliability of the simulation has been verified through comparison of the numerical results with the annual observation data.As revealed by the numericalfindings,the internal temperature of the hill accumulator is proportional to the permeability,outside surface temperature,overground height,underground constant temperature layer depth,and underground tem-perature of the hill,and it is inversely proportional to the horizontal size of the hill.Moreover,in the considered case,the order of magnitude of the permeability of the hill is contained in the range 10-15–10-13,and displays a certain sensitivity to the rainwater seepage.

基于CAVE系统设计的绍兴历史文化街区活化研究

在数字化发展大背景下,传统历史文化街区的保护有了新思路,以绍兴鲁迅故里历史街区的活化项目为依托,对CAVE系统体感游戏设计进行研究探索。分析其整体系统组成和特点优势并且探讨该系统对传统历史文化街区保护改造的影响。通过个案研究,利用虚拟现实技术实现对历史遗存建筑和内部空间的创新发展,最终提出解决文化遗产保护和公众参观服务之间矛盾的有效方案,从而实现提升绍兴世界级古城IP、增加文化和旅游业态体验深度的目的。

一种基于CAVE的交互式全景视频显示方法

为了实现全景视频的沉浸式显示,开发了一个基于CAVE的交互式全景视频显示系统.本系统成功地实现了pgr全景视频文件在CAVE上的播放.首先,将全景视频中的每一帧全景图像映射到一个虚拟球面上;其次,使用五个虚拟相机对该球面的四面及顶面进行拍摄,调整各相机的参数使所得各幅图像覆盖整个球面区域,并能够无缝拼接;最后,将所得五幅图像分别投影到CAVE系统中各投影幕中;另外,实现通过鼠标、手柄等输入设备调整CAVE中各投影幕的画面.

PCCAVE:基于连网PC的廉价CAVE系统

讨论了一个基于 PC的廉价 CAVE系统的实现方法 .FCCAVE使用 4台微机配合中低档的图形显示卡构成图形绘制系统 ,代替 SGI工作站和 Reality Engine高档工作站图形卡 .PCCAVE整体上是一个主从式并行计算结构 ,主节点提供人机交互控制接口 ,从节点接受主节点命令和绘制立体图像 .PCCAVE的通信子系统使用 MPI实现 ,实现了并行计算的同步控制和智能信息代理服务 ,图形子系统以 Direct X和 Open GL 作为底层图形 API.还研究了系统的主要瓶颈和性能指标 .利用该系统实现了浙江大学的校园漫游 .结果表明该系统的许多指标都超越或者接近于 SGI Onyx2 ,具有良好的推广前景和较高的实用价值 .