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Analysis of coal pillar stability(ACPS): A new generation of pillar design software

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International Journal of Mining Science and Technology 2019年第1期29卷 87-91页

作者： Christopher Mark Zach Agioutantis technical support Mine Safety and Health Administration Department of Mining Engineering University of Kentucky

Thirty years ago, the analysis of longwall pillar stability(ALPS) inaugurated a new era in coal pillar *** was the first empirical pillar design technique to consider the abutment loads that arise from full extraction, and the first to be calibrated using an extensive database of longwall mining case *** was followed by the analysis of retreat mining stability(ARMPS) and the analysis of multiple seam stability(AMSS). These methods incorporated other innovations, including the coal mine roof rating(CMRR), the Mark-Bieniawski pillar strength formula, and the pressure arch loading model. They also built upon ever larger case history databases and employed more sophisticated statistical ***, these empirical methods are used in nearly every underground coal mine in the US. However,the piecemeal manner in which these methods have evolved resulted in some weaknesses. For example,in certain situations, it may not be obvious which program is the best to use. Other times the results from the different programs are not entirely consistent with each other. The programs have also not been updated for several years, and some changes were necessary to keep pace with new developments in mining practice. The analysis of coal pillar stability(ACPS) now integrates all three of the older software packages into a single pillar design framework. ACPS also incorporates the latest research findings in the field of pillar design, including an expanded multiple seam case history data base and a new method to evaluate room and pillar panels containing multiple rows of pillars left in place during pillar *** also includes updated guidance and warnings for users and features upgraded help files and graphics.

关键词： Pillar design Ground control Stability Empirical methods

Raindrop Size Distributions in the Zhengzhou Extreme Rainfall Event on 20 July 2021:Temporal-Spatial Variability and Implications for Radar QPE

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Journal of Meteorological Research 2024年第3期38卷 489-503页

作者： Liman CUI Haoran LI Aifang SU Yang ZHANG Xiaona LYU Le XI Yuanmeng ZHANG Henan Key Laboratory of Agrometeorological support and Applied Technique China Meteorological AdministrationZhengzhou450003China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing100081China Henan Meteorological Observatory Zhengzhou450003China

In this study,a regional Parsivel OTT disdrometer network covering urban Zhengzhou and adjacent areas is employed to investigate the temporal-spatial variability of raindrop size distributions(DSDs)in the Zhengzhou extreme rainfall event on 20 July *** rain rates observed by disdrometers and rain gauges from six operational sites are in good agreement,despite significant site-to-site variations of 24-h accumulated rainfall ranging from 198.3 to 624.1 *** Parsivel OTT observations show prominent temporal-spatial variations of DSDs,and the most drastic change was registered at Zhengzhou Station where the record-breaking hourly rainfall of 201.9 mm over 1500-1600 LST(local standard time)was *** hourly rainfall is characterized by fairly high concentrations of large raindrops,and the mass-weighted raindrop diameter generally increases with the rain rate before reaching the equilibrium state of DSDs with the rain rate of about 50 mm h^(−1).Besides,polarimetric radar observations show the highest differential phase shift(K_(dp))and differential reflectivity(Z_(dr))near surface over Zhengzhou Station from 1500 to 1600 *** light of the remarkable temporal-spatial variability of DSDs,a reflectivity-grouped fitting approach is proposed to optimize the reflectivity-rain rate(Z-R)parameterization for radar quantitative precipitation estimation(QPE),and the rain gauge measurements are used for *** results show an increase of mean bias ratio from 0.57 to 0.79 and a decrease of root-mean-square error from 23.69 to 18.36 for the rainfall intensity above 20.0 mm h^(−1),as compared with the fixed Z-R *** study reveals the drastic temporal-spatial variations of rain microphysics during the Zhengzhou extreme rainfall event and warrants the promise of using reflectivity-grouped fitting Z-R relationships for radar QPE of such events.

关键词： extreme rainfall raindrop size distribution radar quantitative precipitation estimation(QPE)

Dynamic Forecasting of Traffic Event Duration in Istanbul:A Classification Approach with Real-Time Data Integration

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Computers, Materials & Continua 2024年第8期80卷 2259-2281页

作者： Mesut Ulu Yusuf Sait Türkan Kenan Menguc Ersin Namlı Tarık Kucukdeniz Occupational health and safety Department Bandirma Onyedi Eylul UniversityBalikesir10200Türkiye Department of Industrial Engineering Istanbul University-CerrahpasaIstanbul34320Türkiye Department of Industrial Engineering Istanbul Technical UniversityIstanbul34467Türkiye

Today,urban traffic,growing populations,and dense transportation networks are contributing to an increase in traffic *** incidents include traffic accidents,vehicle breakdowns,fires,and traffic disputes,resulting in long waiting times,high carbon emissions,and other undesirable *** is vital to estimate incident response times quickly and accurately after traffic incidents occur for the success of incident-related planning and response *** study presents a model for forecasting the traffic incident duration of traffic events with high *** proposed model goes through a 4-stage process using various features to predict the duration of four different traffic events and presents a feature reduction approach to enable real-time data collection and *** the first stage,the dataset consisting of 24,431 data points and 75 variables is prepared by data collection,merging,missing data processing and data *** the second stage,models such as Decision Trees(DT),K-Nearest Neighbour(KNN),Random Forest(RF)and support Vector Machines(SVM)are used and hyperparameter optimisation is performed with *** the third stage,feature selection and reduction are performed and real-time data are *** the last stage,model performance with 14 variables is evaluated with metrics such as accuracy,precision,recall,F1-score,MCC,confusion matrix and *** RF model outperforms other models with an accuracy of 98.5%.The study’s prediction results demonstrate that the proposed dynamic prediction model can achieve a high level of success.

关键词： Traffic event duration forecasting machine learning feature reduction shapley additive explanations(SHAP)

Unsteady aerodynamic noise prediction of contra-rotating open rotor using meshless method

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Chinese Journal of Aeronautics 2024年第8期37卷 144-165页

作者： Zhiliang HONG Meng SU Haitao ZHANG Zerui XU Lin DU Lingfeng CHEN College of safety Science and Engineering Civil Aviation University of ChinaTianjin 300300China Civil Aviation administration of China Beijing 100710China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

The Contra-Rotating Open Rotor(CROR)design confronts significant noise challenges despite being one of the possible options for future green *** efficiently estimate the noise emitted from a CROR,a three-dimensional unsteady prediction model based on the meshless method is *** unsteady wake flow and the aerodynamic load fluctuations on the blade are solved through the viscous vortex particle method,the blade element momentum theory and vortex lattice ***,the acoustic field is obtained through the Farassat’s formulation *** of this method is conducted on a CROR,and a mesh-based method,e.g.,Nonlinear Harmonic(NLH)method,is also employed for *** is found that the presented method is three times faster than NLH method while maintaining a comparable precision.A thorough parametric analysis is also carried out to illustrate the effects of rotational speed,rotor-rotor spacing and rear rotor diameter on the noise *** rotor speed is found to be the most influencing factor,and by optimizing the speed difference between the front and rear rotors,a notable noise reduction can be *** current findings not only contribute to a deeper comprehension of the CROR’s aeroacoustic properties but also offer an effective tool for engineering applications.

关键词： Contra-Rotating Open Rotor(CROR) Aerodynamic noise Blade element momentum theory Viscosity vortex particle method Farassat’s formulation 1A

Corrosion and Scaling Threat in Upstream Oil Operation

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World Journal of Engineering and Technology 2024年第2期12卷 426-437页

作者： Nasir Ullattumpoyil Talal M. Al-Ghamdi Nasser R. Al-Hajri Southern Area technical support Department Saudi Aramco Dhahran KSA

Corrosiveness or scaling is an inherent threat to oil operations. The primary cause for this threat is the presence of water having complex geochemical matrix. Unanticipated water production, particularly if it contains unwanted impurities, can significantly impact hydrocarbon production. The current paper discusses the degree of threat posed to oil operation facilities based on the water characteristics. Methodology involved the collection and analysis of water samples from major sources in oil industry such as groundwater, wellheads and seawater. The parameters tested include geochemical, microbiological and pollutants. The lab data was used to develop scaling and corrosion prediction indices such as Langelier Saturation Index (LSI), Ryznar Stability Index (RSI) and Puckorius Scaling Index (PSI). The study indicated varying water chemistry for different sources. Mixing of those waters may lead to ionic saturation and scaling in different facilities. Presence of the SRB and GAB in some water sources also posed threat to water system by forming fouling and corrosion. Seawater used for offshore oilfields water injection to maintain reservoir pressure and improve oil recovery showed scaling tendency, whereas under different reservoir pressure, it can cause corrosion. Some of the samples also had corrosion residuals such as iron, which indicated active corrosion. Current study showed higher alkalinity with high sulfate for one groundwater sample with presence of active corrosion residuals such as dissolved iron and manganese. The study showed positive value for LSI which indicated supersaturation of the water samples with respect to calcium carbonate (CaCO3) and scale forming. Similarly, for RSI and PSI, the value was below six which confirmed the scaling potential for all the samples. Even though the index value was pointing towards scaling potential, the geochemistry, microbiology and presence of other impurities indicated corrosion threat to the oil and g

关键词： Formation Water Petroleum Reservoirs Groundwater Saturation Indices Corrosiveness

Protecting miners from coal bursts during development above historic mine workings in Harlan County,KY

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International Journal of Mining Science and Technology 2021年第1期31卷 111-116页

作者： Christopher Mark mine safety and health administration PittsburghPA 15236USA

In order to reach a large,untapped reserve of high-quality coal,D8 Cloverlick mine proposed to mine a corridor nearly 600 m deep beneath the Benham Spur of Black Mountain,Kentucky’s highest peak.D8 Cloverlick mine was extracting the Owl seam,but the corridor’s route lay approximately 20 m above century-old mine workings in the C–(Darby)*** to the concern,three serious coal bursts had recently occurred in nearby Owl seam *** of the old workings seemed to indicate that the underlying C–seam had been fully ***,two of the coal bursts had occurred above areas where the C–Seam was also shown as mined *** safety and health administration(MSHA)technical support therefore investigated the records of past mining to better understand the old mine *** conditions observed in current Owl seam workings were also compared with the maps of the old C–seam *** study concluded that the presence of hazardous underlying remnants could not be ruled *** mitigate the burst risk,D8 Cloverlick mine adopted a strategy of stress probe drilling.A self-propelled coal drill was used to auger 11.5-m-long,small diameter holes in advance of *** each hole was drilled,the cuttings were measured to detect the presence of highly stressed *** the crossing was successfully completed without incident.

关键词： Coal bursts Underground mining Room-and-pillar Destressing

Evaluation of Driver-Induced Human Errors in Smart Construction Tower Crane Operations Based on DEMATEL-ISM-MICMAC

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Journal of Applied Mathematics and Physics 2024年第4期12卷 1541-1556页

作者： Jiahao Wang Wen Si School of Business administration Liaoning Technical University Fuxin China

With the advent of Industry 4.0, smart construction sites have seen significant development in China. However, accidents involving digitized tower cranes continue to be a persistent issue. Among the contributing factors, human unsafe behavior stands out as a primary cause for these incidents. This study aims to assess the human reliability of tower crane operations on smart construction sites. To proactively enhance safety measures, the research employs text mining techniques (TF-IDF-Truncated SVD-Complement NB) to identify patterns of human errors among tower crane operators. Building upon the SHEL model, the study categorizes behavioral factors affecting human reliability in the man-machine interface, leading to the establishment of the Performance Shaping Factors (PSFs) system. Furthermore, the research constructs an error impact indicator system for the intelligent construction site tower crane operator interface. Using the DEMATEL method, it analyzes the significance of various factors influencing human errors in tower crane operations. Additionally, the ISM-MICMAC method is applied to unveil the hierarchical relationships and driving-dependent connections among these influencing factors. The findings indicate that personal state, operating procedures, and physical environment directly impact human errors, while personal capability, technological environment, and one fundamental organizational management factor contribute indirectly. .

关键词： Text Mining DEMATEL-ISM-MICMAC Performance Shaping Factors Smart Construction Tower Crane Operator

Porous high-entropy rare-earth phosphate(REPO_(4),RE=La,Sm,Eu,Ce,Pr and Gd)ceramics with excellent thermal insulation performance via pore structure tailoring

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International Journal of minerals,Metallurgy and Materials 2024年第7期31卷 1651-1658页

作者： Peixiong Zhang Enhui Wang Jingjing Liu Tao Yang Hailong Wang Xinmei Hou Institute for Carbon Neutrality University of Science and Technology BeijingBeijing 100083China Liaoning Academy of Materials Shenyang 110000China technical support Center for Prevention and Control of Disastrous Accidents in Metal Smelting University of Science and Technology BeijingBeijing 100083China School of Materials Science Engineering Zhengzhou UniversityZhengzhou 450001China

Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high *** this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4)(HE(6RE_(1/6))PO_(4))ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents(0–60vol%)on this ceramic properties was systematically *** results show that the porous HE(6RE_(1/6))PO_(4)ceramics with 60vol%starch exhibit the lowest thermal conductivity of 0.061 W·m^(-1)·K^(-1)at room temperature and good pore structure stability with a linear shrinkage of approximately1.67%.Moreover,the effect of large regular spherical pores(>10μm)on its thermal insulation performance was discussed,and an optimal thermal conductivity prediction model was *** superior properties of the prepared porous HE(6RE_(1/6))PO_(4)ceramics allow them to be promising insulation materials in the future.

关键词： porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4) ceramics high-entropy strategy pore-forming agent method thermal insulation material thermal conductivity

Tropical Cyclone Monitoring and Analysis Techniques: A Review

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Journal of Meteorological Research 2024年第2期38卷 351-367页

作者： Chuanhai QIAN Ying LI Yinglong XU Xin WANG Zenghai ZHANG Gaozhen NIE Da LIU Shiwen ZHANG Institute for Development and Programme Design China Meteorological AdministrationBeijing 100081 Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081 National Meteorological Centre China Meteorological AdministrationBeijing 100081 National Satellite Meteorological Centre China Meteorological AdministrationBeijing 100081

Tropical cyclones(TCs),including tropical depressions and different categories of typhoons,hurricanes,and cyclonic storms,mostly originate over the oceans in the absence of direct ***,detailed monitoring and analysis of TCs has always been an unsolved *** the recent 20 years,great changes have taken place in domestic and foreign TC monitoring techniques,imposing a significant impact on TC operations and *** new technologies and products gradually emerge to support operations,with improved monitoring *** this paper,the progress on TC monitoring and analysis via meteorological satellites,radars,and airplanes in China and the world is reviewed,compared,and summarized,with special focuses on multisatellite fusion observations,in situ aircraft measurements,and some unconventional observation equipment such as rockets,saildrones,and underwater *** this basis,the paper points out future directions for improving TC monitoring and analysis in aid of better TC forecast and early warning.

关键词： tropical cyclone(TC) monitoring and analysis meteorological satellite aircraft reconnaissance