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Optimal use of mobile cooling units in a deep-level gold mine

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International journal of Mining Science and Technology 2020年第4期30卷 547-553页

作者： h.j.van Staden j.F.van Rensburg h.j.Groenewald Centre for Research and Continued Engineering Development North-West UniversityPretoria 0081South Africa

The South African gold mining sector remains a significant contributor to the country’s *** several challenges that hinder the realisation of South Africa’s full mineral potential,the sector’s sustainability and profitability can be enhanced through implementing operational improvement *** cooling units(MCUs)were identified as a potential focus area for operational *** are used as tertiary or in-stope cooling in hot underground *** this paper,a method was presented to characterise the performance of existing MCUs based on three key performance indicators(KPIs),namely,the wet-bulb temperature ratio(WTR),efficiency and *** strategies were then elected and implemented based on these *** implementation of this method in a South African gold mine attained a reduction in pumped water volumes,reduced operating costs through electricity cost savings and improvements in underground ventilation air temperatures.

关键词： Mobile cooling units Optimisation Mine cooling performance Electricity cost savings Spot cooling

Mass transfer in gas–liquid stirred reactor with various triple-impeller combinations

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Chinese journal of Chemical Engineering 2016年第6期24卷 703-710页

作者： jinjin Zhang Zhengming Gao Yating cai Ziqi cai jie Yang Yuyun Bao State Key Laboratory of Chemical Resource Engineering School of Chemical Engineering Beijing University of Chemical Technology Beijing 100029 China School of Chemical Engineering Shandong University of Technology Zibo 255000 China

The gassed power demand and volumetric mass transfer coefficient （kca） were investigated in a fully baffled, dished-base stirred vessel with a diameter of 0.30 m agitated by five triple-impeller combinations. Six types of impellers （six-half-elliptical-blade disk turbine （hEDT）, four-wide-blade hydrofoil impeller （Wh） pumping down （D） and pumping up （U）, parabolic-blade disk turbine （PDT）, and CBY narrow blade （N） and wide blade （W）） were used to form five combinations identified by PDT ＋ 2CBYN, PDT ＋ 2CBYw, PDT ＋ 2WhD, hEDT ＋ 2WhD and hEDT ＋ 2Who, respectively. The results show that the relative power demand of hEDT ＋ 2Whu is higher than that of other four impeller combinations under all operating conditions. At low superficial gas velocity （uc）, kLa differences among impeller combinations are not obvious. however when UG iS high, PDT ＋ 2WhD shows the best mass transfer performance and hEDT ＋ 2Whu shows the worst mass trans- fer performance under all operating conditions. At high uc and a given power input, the impeller combinations with high agitation speed and big projection cross-sectional area lead to relatively high values of kLa. Based on the experimental data, the regressed correlations of gassed power number with Froude number and gas flow number, and kLa with power consumption and superficial gas velocity are obtained for five different impeller combinations, which could be used as guidance for industrial design.

关键词： Stirred vesselGassed powerMass transferTriple-impeller combinationGas-liquid system

Estimation of the j-resistance curve for Cr2Ni2MoV steel using the modified load separation parameter S_(pb) method

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journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第10期11卷 782-788页

作者： Chen BAO Li-xun cai School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

Based on load separation theory, the load separation parameter Spb method is an effective approach for estimating the j-resistance curve from records of load versus displacement directly, using one sharp cracked specimen and an additional reference blunt cracked specimen. however, the effect of the reference blunt cracked specimen on j-resistance determination was not explicitly considered in past work. In this paper, a modified load separation parameter Spb method was developed to eliminate this effect, and then a unique estimation of instantaneous crack length for one sharp cracked specimen could be obtained. Furthermore, a forced blunting calibration method was also adopted to determine the instantaneous crack length in the load inseparable region, referring to a normalization method. Experiments on steam turbine rotator steel Cr2Ni2MoV were carried out to estimate j-resistance curves using an unloading compliance method. By removing unload and reload data from load-displacement records, the j-resistance curve for the same sharp cracked specimen was estimated using the modified separation parameter Spb method. The results indicate that the modified Spb method completely eliminates the effect of the reference blunt cracked specimen on the instantaneous crack length determination of the sharp cracked specimen. however, different j-resistance curves in a small range of crack extension are present when different blunting coefficients are used in the blunting line equation. The j-resistance curve obtained from the modified Spb method agrees well with that obtained from the compliance method.

关键词： Load separation j-resistance curve Separation parameter Spb Blunt cracked specimen Forced blunting calibration

Optimized silicon fertilization regime weakens cadmium translocation and increases its biotransformation in rice tissues

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The Crop journal 2024年第4期12卷 1041-1053页

作者： Bogui Pan Yixia cai Kunzheng cai jihui Tian Wei Wang College of Natural Resources and Environment South China Agricultural UniversityGuangzhou 510642GuangdongChina Guangdong Provincial Key Laboratory of Eco-Circular Agriculture Guangzhou 510642GuangdongChina Key Laboratory of Tropical Agricultural Environment in South China Ministry of Agriculture and Rural AffairsGuangzhou 510642GuangdongChina College of Agriculture South China Agricultural UniversityGuangzhou 510642GuangdongChina

In acidic paddy fields of South China,rice(Oryza sativa L.)faces the dual challenges of cadmium(Cd)toxicity and silicon(Si)*** previous studies have highlighted the functions of Si application timing and strategies in mitigating Cd-stressed rice,the precise mechanisms underlying the health restoration of Cd-toxic rice and the assurance of grain safety remain *** study explored Cd translocation and detoxification in the shoots of rice regulated by various Si fertilization regimes:Si(T)(all Si added before transplanting),Si(j)(all Si added at jointing),and Si(Tj)(half Si added both before transplanting and at jointing).The findings revealed that the regime of Si(Tj)was more beneficial to rice health and grain safety than Si(T)and Si(j).The osmotic regulators such as proline,soluble sugars,and soluble proteins were significantly boosted by Si(Tj)compared to other Si treatments,and which enhanced membrane integrity,balanced intracellular ph,and increased Cd tolerance of ***,Si(Tj)was more effective than Si(T)and Si(j)on the Cd sequestration in the cell wall,Cd bio-passivation,and the down-regulated expression of the Cd transport *** concentrations of Cd in the xylem and phloem treated with Si(Tj)were reduced ***,Si(Tj)facilitated much more Cd bound with the outer layer proteins of grains,and promoted Cd chelation and complexation by phytic acid,phenolics,and ***,Si(Tj)outperformed Si(T)and Si(j)in harmonizing the phycological processes,inhibiting Cd translocation,and enhancing Cd detoxification in rice *** the split Si application strategy offers potential for reducing Cd toxicity in rice grain.

关键词： Cadmium Silicon Growth stages Translocation and accumulation Rice Safe production

Estimation of j—R Curves for Small-Sized COEC Specimens and Its Application Considering Crack-Tip Cons tr aints

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Acta Mechanica Solida Sinica 2019年第3期32卷 261-276页

作者： G.W.he C.Bao L.X.cai Y.j.Wu Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Engineering Southwest Jiaotong University Chengdu 610031 China

The normalization method has been employed to estimate the j-resistance (j—R) curves for C-shaped outside edge-notched compression (COEC) specimens of SA-508 steel. The COEC specimens present the lowest j—R curves in comparison with other three types of specimens. Based on the j—Q—M met hod, the constraint parame ter Q determined at the mid-plane in the through-thickness direction of the specimen is used to approximately quantify the threedimensional crack-tip constraint for COEC specimens. Combining with the previous experiments on j—R curves, the constraint-coirected j—R curves for SA-508 steel specimens are given, which may be used to predict the fracture toughness of actual cracked components in structural integrity assessment.

关键词： Ductile fracture toughness COEC specimen Dimensionless load separation principle Normalization method Crack-tip constraint j-Q-M method

Civil unmanned aircraft system operation in national airspace: A survey from Air Navigation Service Provider perspective

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Chinese journal of Aeronautics 2021年第3期34卷 200-224页

作者： Zhaoxuan LIU Kaiquan cai Yanbo ZhU School of Electronics and Information Engineering Beihang UniversityBeijing 100083China Aviation Data Communication Corporation Beijing 100083China

Unmanned Aircraft Systems(UASs) have advanced technologically and surged exponentially over recent years. Currently, due to safety concerns, most civil operations of UAS are conducted in low-level uncontrolled area or in segregated controlled airspace. As the industry progresses, both operational and technological capabilities have matured to the point where UASs are expected to gain greater freedom of access to both controlled and uncontrolled airspace. Extensive technical and regulatory surveys have been conducted to enable the expanded operations. however, most surveys are derived from the perspective of UAS own operating mechanism and barely consider interactions of their non-segregated activities with the Air Traffic Management(ATM) system. hence, to fill the gap, this paper presents a survey conducted from the perspective of Air Navigation Service Provider(ANSP), which serves to accommodate these new entrants to the overall national airspace while continuing flight safety and efficiency. The primary objectives of this paper are to:(A) describe what typical ANSP-supplied UAS Traffic Management(UTM) architecture is required to facilitate all types of civil UAS operations;(B) identify three major ANSP considerations on how UAS can be accommodated safely in civil airspace;(C) outline future directions and challenges related with UAS operations for the ANSP.

关键词： Air Navigation Service Provider Airspace Organization and Management Air Traffic Control Air Traffic Management Air traffic service provision Unmanned Aircraft System UAS Traffic Management

Novel method for measuring surface residual stress using flat-ended cylindrical indentation

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Chinese journal of Aeronautics 2024年第8期37卷 486-495页

作者： Guangzhao hAN Lixun cai Xiaokun LIU Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China Zhengzhou Machinery Research Institute Transmission Technology Co. LtdZhengzhou 518115China

Instrumented indentation is a promising technique for estimating surface residual stresses and mechanical properties in engineering *** relative difference between the indentation loads for unstressed and stressed specimens was selected as the key parameter for measuring surface residual stresses in flat-ended cylindrical *** on the equivalent material method and finite element simulations,a dimensionless mapping model with six constants was established between the relative load difference,constitutive model parameters,and normalized residual stress.A novel method for measuring the surface residual stress and constitutive model parameters of metallic material through flat-ended cylindrical indentations was proposed using this model and a mechanical properties determination *** simulations were conducted using numerous elastoplastic materials with different residual stresses to verify the proposed model;good agreements were observed between the predicted residual stresses and those previously applied in finite element ***-ended cylindrical indentation tests were performed on four metallic materials using cruciform specimens subjected to various equibiaxial *** results exhibited good conformance between the stress–strain curves obtained using the proposed method and those from traditional tensile tests,and the absolute differences between the predicted residual stresses and applied stresses were within 40 MPa in most cases.

关键词： Instrumented indentation Residual stress Finite element simulation Equivalent material method Mechanical property

Pore-scale modeling of pore structure properties and wettability effect on permeability of low-rank coal

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International journal of Mining Science and Technology 2023年第5期33卷 573-584页

作者： Xiangjie Qin jianchao cai Gang Wang State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing 102249China State Key Laboratory of Mining Disaster Prevention and Control Cofounded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China

Permeability is a key parameter for coalbed methane *** the absolute permeability of coal has been extensively studied,wettability and pore structure properties continue to challenge the microscopic description of water-gas flow in *** this purpose,we reconstructed the microstructures of low-rank coal using micro-computed tomography(micro-CT)*** geometry and pore-throat parameters are introduced to establish a relationship with absolute permeability.A dual-porosity pore network model is developed to study water-gas displacement under different wetting and pore structure *** show that absolute permeability is significantly affected by pore geometry and can be described using a binary quadratic function of porosity and fractal ***-gas relative permeability varies significantly and the residual gas saturation is lower;the crossover saturation first decreased and then increased with increasing porosity under hydrophobic *** the water relative permeability is lower and a certain amount of gas is trapped in complex pore-throat networks;the crossover saturation is higher under hydrophilic *** with large percolating porosity and well-developed pore networks have high displacement efficiency due to low capillary resistance and avoidance of *** work provides a systematic description of absolute permeability and water-gas relative permeability in coal microstructure for enhanced gas recovery.

关键词： Micro-CT Permeability Wetting condition Pore structure properties Water-gas flow

Review on Optimization of Nuclear Power Development:A Cyber-Physical-Social System in Energy Perspective

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journal of Modern Power Systems and Clean Energy 2022年第3期10卷 547-561页

作者： Xinxin Yang Bin cai Yusheng Xue School of Electrical Engineering Southeast UniversityNanjingChina State Grid Electric Power Research Institute(NARI Group Corporation) NanjingChina State Key Laboratory of Smart Grid Protection and Operation Control NanjingChina

Nuclear power development is a complex issue spanning cyber,physical,and social systems that is essential to achieving energy security and climate *** the ongoing worldwide trend towards carbon neutrality,the positioning of nuclear power in energy mix should be *** paper aims to present a systematic review of current research on optimization of nuclear power *** concept of cyber-physical-social system in energy(CPSSE)is adopted,which provides a suitable perspective and enables the review of relevant studies to achieve some novel *** on the CPSSE,firstly,a research framework is established and the main research elements in optimization are identified,followed by a proposed conceptual risk-based optimization ***,current studies are analyzed and classified into four categories according to the research *** status quo and limitations are *** is found that the research results of nuclear-specific issues have not been well integrated into the optimization of nuclear *** a relatively reliable power supply,nuclear power is capable of maintaining power and electricity adequacy of the whole system,especially in the case of power shortage caused by long-period low output of renewable energy or extreme external *** superiority should not be ignored in the *** critical factors that should be further considered include disruptive technologies,nuclear safety,energy policies,and stakeholder ***,suggestions are given for future research.

关键词： Carbon emission carbon neutrality cyber-physical-social system in energy(CPSSE) comprehensive evaluation dynamic interactive hybrid simulation energy transition multi-objective optimization