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 extracti...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.展开更多
With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided m...With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.展开更多
Based on GPS velocity during 1999-2007,GPS baseline time series on large scale during1999-2008 and cross-fault leveling data during 1985-2008,the paper makes some analysis and discussion to study and summarize the mov...Based on GPS velocity during 1999-2007,GPS baseline time series on large scale during1999-2008 and cross-fault leveling data during 1985-2008,the paper makes some analysis and discussion to study and summarize the movement,tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8. 0 Wenchuan earthquake,as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500 km wide,while there was little deformation in Sichuan Basin and Longmenshan fault zone,which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone,and deformation amplitude decreased gradually from far field to near fault zone,and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone,and strain accumulation rate was larger than that of mid-northern segment.Fault locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked,and a 20 km width patch in southwestern segment between 12 km to 22. 5 km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt,which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little,which indicates that vertical activity near the fault was very weak and the fault was tightly locked. According to analyses of GPS and cross-fault leveling data before the Wenchuan earthquake,we consider that the Longmenshan fault is tightly locked from the surface to the deep,and the horizontal and vertical deformation are weak surrounding the fault in relatively small-scale crustal deformation. The process of weak deformation may be slow,and weak deformation area may be larger when large earthquake is coming. Continuous and slow compression deformation across eastern Qinghai-Tibetan Plateau before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large-scale crustal deformation.展开更多
The Funan-Huoqiu area is located in the border tectonic belt between the North China and South China active block regions. By means of seismological and geological surveys and synthetic analysis, evidences of tectonic...The Funan-Huoqiu area is located in the border tectonic belt between the North China and South China active block regions. By means of seismological and geological surveys and synthetic analysis, evidences of tectonic deformation in lower intensity have been found in the area since Late Pleistocene, where small earthquakes are distributed linearly along the main faults, conjugate shear joints are developed in the Upper Pleistocene nearby the faults. In the south of the studied region, fissures with different lengths, widths and directions occurred successively in Gushi, Huoqiu, Funan and other places of the area, in the 1970’s, and the direction of the fissures is approximately consistent with that of the Feizhong fault and Wanglaorenji fault. The authors hold that the clustering of small earthquakes, the conjugate shear joints developed in the Upper Pleistocene, the crumpled deformation of materials on fault plane, and the development of modern surface fissures in the area all reflect that the energy in the crust was slowly released, and that the weak deformation took place in corresponding faults. There was only one destructive earthquake taking place in the area (the Jiangkouji {M_S43/4} earthquake). Altogather, there has been weak activity in the area since the Late Quaternary, and it is mainly shown as a creep-slip.展开更多
文摘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.
基金the Indian Institute of Technology Bombay’s Post-Doctoral Research Program, vide appointment no. AO/Admn1/33/2018 dated 10.Aug’2018 for providing funding
文摘With rapid advancements in Infra-Red (IR) detection techniques, the range from where the IR-guided missiles are able to lock the target aircraft has increased. To avoid the detection and tracking by modern IR-guided missiles, the aircraft and helicopters also demand progress in its stealth techniques. Hence, study of Infra-Red Signature Suppression (IRSS) systems in aircraft and helicopters has become vital even in design stage. Optical blocking (masking) is one of the effective IRSS techniques used to block the Line- Of-Sight (LOS) of the hot engine parts of the exhaust geometry. This paper reviews the various patents on IR signature suppression systems based on the optical blocking method or a combination of IRSS techniques. The performance penalties generated due to installation of various IRSS methods in aircraft and helicopters are also discussed.
基金supported by the National Key R&D Program of China(2018YFC1503606 2017YFC1500502)Earthquake Tracking Task(2019010215)
文摘Based on GPS velocity during 1999-2007,GPS baseline time series on large scale during1999-2008 and cross-fault leveling data during 1985-2008,the paper makes some analysis and discussion to study and summarize the movement,tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8. 0 Wenchuan earthquake,as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500 km wide,while there was little deformation in Sichuan Basin and Longmenshan fault zone,which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone,and deformation amplitude decreased gradually from far field to near fault zone,and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone,and strain accumulation rate was larger than that of mid-northern segment.Fault locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked,and a 20 km width patch in southwestern segment between 12 km to 22. 5 km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt,which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little,which indicates that vertical activity near the fault was very weak and the fault was tightly locked. According to analyses of GPS and cross-fault leveling data before the Wenchuan earthquake,we consider that the Longmenshan fault is tightly locked from the surface to the deep,and the horizontal and vertical deformation are weak surrounding the fault in relatively small-scale crustal deformation. The process of weak deformation may be slow,and weak deformation area may be larger when large earthquake is coming. Continuous and slow compression deformation across eastern Qinghai-Tibetan Plateau before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large-scale crustal deformation.
文摘The Funan-Huoqiu area is located in the border tectonic belt between the North China and South China active block regions. By means of seismological and geological surveys and synthetic analysis, evidences of tectonic deformation in lower intensity have been found in the area since Late Pleistocene, where small earthquakes are distributed linearly along the main faults, conjugate shear joints are developed in the Upper Pleistocene nearby the faults. In the south of the studied region, fissures with different lengths, widths and directions occurred successively in Gushi, Huoqiu, Funan and other places of the area, in the 1970’s, and the direction of the fissures is approximately consistent with that of the Feizhong fault and Wanglaorenji fault. The authors hold that the clustering of small earthquakes, the conjugate shear joints developed in the Upper Pleistocene, the crumpled deformation of materials on fault plane, and the development of modern surface fissures in the area all reflect that the energy in the crust was slowly released, and that the weak deformation took place in corresponding faults. There was only one destructive earthquake taking place in the area (the Jiangkouji {M_S43/4} earthquake). Altogather, there has been weak activity in the area since the Late Quaternary, and it is mainly shown as a creep-slip.
文摘探讨俞募配穴针法联合穴位埋针法治疗风痰闭阻型支气管哮喘的疗效及对血清免疫球蛋白E(Immunoglobin E,IgE)、可溶性二聚体细胞因子(Interferon-γ,IFN-γ)、肺表面活性蛋白(Pulmonary surfactant protein,SP-A)水平影响。方法选取医院收治的风痰闭阻型支气管哮喘患者108例,采用区组随机化原则分为两组各54例。对照组给予穴位埋针法,治疗组在对照组基础上给予俞募配穴针法,两组患者数据观察:对比治疗后临床疗效、哮喘控制测试(Asthma control test,ACT)量表评分、第一秒最大呼气容积(Forced expiratory volume in one second,FEV1)、呼气峰值流速(Peak expiratory,PEF)、用力肺活量(Forced vital capacity,FVC)、临床症状评分及IgE、IFN-γ、SP-A水平、临床治疗安全性及患者满意度。结果经过治疗后,治疗组临床疗效显著较高(P<0.05);两组治疗前ACT评分差异无统计学意义(P>0.05);治疗后两组ACT评分明显升高(P<0.05);且治疗组升高较明显(P<0.05);治疗后两组FEV1、PEF、FVC值明显升高(P<0.05);且治疗组升高较明显(P<0.05);两组治疗前临床症状评分差异无统计学意义(P>0.05);两组治疗后咳嗽、呼吸困难、喘息等症状评分显著降低(P<0.05);且治疗组降低较明显(P<0.05);两组治疗前血清IgE、IFN-γ、SP-A水平无差异(P>0.05);两组治疗后血清IgE显著降低,血清IFN-γ、SP-A水平显著升高(P<0.05);且治疗组改善较明显(P<0.05);治疗组未见治疗不良反应,对照组患者出现1例不良反应,症状为恶心,P>0.05;治疗组治疗满意率高达98.15%(53/54),显著高于对照组的83.33%(45/54),P<0.05。结论采用俞募配穴针法联合穴位埋针法治疗风痰闭阻型支气管哮喘具有较好的治疗效果,能够改善血清IgE、IFN-γ及SP-A水平,且本次治疗安全可靠,患者十分认可,值得在临床上推广应用。
