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Effects of aggregate size distribution and carbon nanotubes on the mechanical properties of cemented gangue backfill samples under true triaxial compression

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 311-324页

作者： Qian yin Fan Wen zhigang Tao Hai Pu Tianci Deng yaoyao Meng Qingbin Meng Hongwen Jing Bo Meng Jiangyu Wu State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China Key Laboratory of Xinjiang Coal Resources Green Mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China

The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious ***,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of *** mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically *** results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,***,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the ***σ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite ***ε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse *** increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"y-shaped"shear failure,and conjugate shear failure.

关键词： cemented gangue backfill materials particle size distribution true triaxial compression test carbon nanotubes mechanical properties failure modes

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SCHEDULIng WITH REJECTION AND NON-IDENTICAL JOB ARRIVALS

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Journal of Systems Science & Complexity 2007年第4期20卷 529-535页

作者： zhigang CAO yuzhong ZHAng Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China School of Operations Research and Management Science Qufu Normal University Rizhao Shandong 276826 China

In this paper, we address the scheduling problem with rejection and non-identical job arrivals, in which we may choose not to process certain jobs and each rejected job incurs a penalty, Our goal is to minimize the sum of the total penalties of the rejected jobs and the maximum completion time of the processed ones, For the off-line variant, we prove its NP-hardness and present a PTAS, and for the on-line special case with two job arrivals, we design a best possible algorithm with competitive ratio （√5＋1/2） .

关键词： Non-identical job arrival on-line rejection scheduling.

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Many-objective optimization for coordinated operation of integrated electricity and gas network

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Journal of Modern Power Systems and Clean Energy 2017年第3期5卷 350-363页

作者： y.N.KOU J.H.ZHEng zhigang LI Q.H.WU School of Electric Power Engineering South China University of TechnologyGuangzhou 510640China Department of Electrical Engineering and Electronics The University of LiverpoolLiverpool L693GJUK

This paper develops a many-objective optimization model, which contains objectives representing the interests of the electricity and gas networks, as well as the distributed district heating and cooling units, to coordinate the benefits of all parties participated in the integrated energy system(IES). In order to solve the many-objective optimization model efficiently, an improved objective reduction(IOR) approach is proposed, aiming at acquiring the smallest set of objectives. The IOR approach utilizes the Spearman’s rank correlation coefficient to measure the relationship between objectives based on the Pareto-optimal front captured by the multi-objective group search optimizer with adaptive covariance and Lévy flights algorithm, and adopts various strategies to reduce the number of objectives gradually. Simulation studies are conducted on an IES consisting of a modified IEEE 30-bus electricity network and a 15-node gas network. The results show that the many-objective optimization problem is transformed into a bi-objective formulation by the IOR. Furthermore,our approach improves the overall quality of dispatch solutions and alleviates the decision making burden.

关键词： Integrated energy system Gas network Electricity network Many-objective optimization Objective reduction

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Physical characteristics of high-rank coal reservoirs in different coal-body structures and the mechanism of coalbed methane production

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Science China Earth Sciences 2017年第2期60卷 246-255页

作者： ZHAng XiaoDong DU zhigang LI PengPeng School of Energy Science and Engineering Henan Polytechnic University Jiaozuo 454000 China Collaborative Innovation Center of Coalbed Methane (Shale Gas) in Central Plains Economic Zone Jiaozuo 454000 China

The physical characteristics of coal reservoirs are important for evaluating the potential for gas desorption, diffusion, and seepage during coalbed methane （CBM） production, and influence the performance of CBM wells. Based on data from mercury injection experiments, low-temperature liquid nitrogen adsorption, isothermal adsorption, initial velocity tests of methane diffusion, and gas natural desorption data from a CBM field, herein the physical characteristics of reservoirs of high-rank coals with different coal-body structures are described, including porosity, adsorption/desorption, diffusion, and seepage. Geometric models are constructed for these reservoirs. The modes of diffusion are discussed and a comprehensive diffusion-seepage model is constructed. The following conclusions were obtained. First, the pore distribution of tectonically deformed coal is different from that of normal coal. Compared to normal coal, all types of pore, including micropores （〈10 nm）, transitional pores （10-100 nm）, mesopores （100-1000 nm）, and macropores （〉1000 nm）, are more abundant in tectonically deformed coal, especially mesopores and macropores. The increase in pore abundance is greater with increasing tectonic deformation of coal; in addition, the pore connectivity is altered. These are the key factors causing differences in other reservoir physical characteristics, such as adsorption/desorption and diffusion in coals with different coal-body structures. Second, normal and cataclastic coals mainly contain micropores. The lack of macropores and its bad connectivity limit gas desorption and diffusion during the early stage of CBM production. However, the good connectivity of micropores is favorable for gas desorption and diffusion in later gas production stage. Thus, because of the slow decline in the rate of gas desorption, long-term gas production can easily be obtained from these reservoirs. Third, under natural conditions the adsorption/desorption properties of granulated

关键词： High-rank coal Coal-body structure Reservoir physical characteristics Gas production mechanism

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Special Issue on Machine Fault Diagnostics and Prognostics

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Chinese Journal of Mechanical Engineering 2017年第6期30卷 1283-1284页

作者： zhigang Tian Wilson Wang University of Alberta Edmonton Canada Lakehead University Thunder Bay Canada

Machine components and systems, such as gears, bearings, pipes, cutting tools and turbines, may experience various types of faults, such as breakage, crack, pitting, wear, corrosion. If not being properly monitored and treated, such faults can propagate and lead to machinery perfor- mance degradation, malfunction, or even severe compo- nent/system failure. It is significant to reliably detect machinery defects, evaluate their severity, predict the fault propagation trends, and schedule optimized maintenance and inspection activities to prevent unexpected failures. Advances in these areas will support ensuring equipment and production reliability, safety, quality and productivity.

关键词： Special Issue Machine Fault Diagnostics Prognostics

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Influence of rare-earth metal doping on the catalytic performance of CuO-CeO_2 for the preferential oxidation of CO in excess hydrogen

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Journal of Natural Gas Chemistry 2008年第3期17卷 283-287页

作者： zhigang Liu Renxian Zhou Xiaoming Zheng Institute of Catalysis Zhejiang University Hangzhou 310028 Zhejiang China School of Chemistry and Chemical Engineering Hunan University Changsha 410082 Hunan China

Doping of different rare-earth metals （Pr, Nd, y and La） had an evident influence on the catalytic performance of CuO-CeO2 for the preferential oxidation （PROX） of CO in excess hydrogen. As for Pr, the doping enhanced the catalytic activity of CuO-CeO2 for PROX. For example, the CO conversion over the above catalyst for PROX was higher than 99% at 120 °C. Especially, the doping of Pr widened the temperature window by 20 °C over CuO-CeO2 with 99% CO conversion. For Nd, y, and La, the doping depressed the catalytic activity of CuO-CeO2 for PROX. However, the doping of transition metals markedly improved the selectivity of CuO-CeO2 for PROX.

关键词： CuO-CeO2 rare-earth metal doping CO

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Identification of nonlinear multi-degree-of freedom structures based on Hilbert transformation

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Science China(Physics,Mechanics & Astronomy) 2014年第9期57卷 1725-1736页

作者： WU zhigang y.ng Ning y.ng Chao School of Aeronautic Science and Engineering Beijing University of Aeronautics and Astronautics

The modeling method and identified method adapted to multi-degree-of-freedom structures with strucrural nonlinearities are *** component mode synthesis method is used to establish the nonlinear governing equations by extending the connected *** on the modeling method,the Hilbert transform method is applied to identify the nonlinear stiffness of multi-degree-of-freedom *** analysis and identification of a typical folding wing configuration with three freeplay hinges are *** nonlinear governing equation is established based on present methods and the computing results of different stiffness are checked by finite element *** order to illustrate the influence of the nonlinearities,the frequency response characteristics of the structure are analyzed and Hilbert transform is *** Hilbert transform identification method is utilized to identify the nonlinear stiffness of nonlinear hinges in the time domain and several parametric studies are *** addition,the comparison of response is made to illustrate the feasibility of the *** results show that the extending component mode synthesis method in the present work can be used to establish the governing equation with structural *** on the modeling method,the Hilbert transform identified method can be extended to multi-degree-of-freedom structures accurately.

关键词： structural nonlinearity identification Hilbert transformation component mode synthesis method dynamic analysis dynamic response

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Estimation of growth rate of Skeletonema costatum based on relative expression amount of PCNA gene

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Acta Oceanologica Sinica 2008年第6期27卷 149-158页

作者： HE Shany.ng yU zhigang College of Environmental Science and Engineering Zhejiang Gongshang University Hangzhou 310012 China College of Chemistry and Chemical Engineering Ocean University of China Qingdao 266003 China

Partial sequence of Skeletonema costatum proliferating cell nuclear antigen （PCNA） gene was obtained by reverse transcriptase PCR（RT-PCR） and 3＇ rapid amplification of cDNA ends （3＇-RACE） techniques. Based on the obtained PCNA and cytochrome b gene（ Cyt b gene） sequences, a real-time fluorescent quantitative PCR （FQ-PCR） method was developed to detect the expression S. costatum PCNA gene, and this method was applied to study the relationship between the growth rate of S. costatum and the average expression amount of PCNA gene in a single cell. The expression amount of PCNA gene had large variation in cells collected at different culture phases, and the trend was well consistent with the growth rate, which suggested that the expression amount of PCNA gene correlated well with the cell division, and the PCNA could be a promising indicator for the S. costatum cell proliferation. Furthermore, using the PCNA gene as the objective gene and the Cyt b gene as the house-keeping gene, a new method for estimating the in situ growth rate of S. costatum was established by analysis of the relative expression quantity （REQ） of the PCNA gene.

关键词： Skeletonema costatum fluorescent quantitative PCR PCNA growth rate

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Effect of Steam Dilution on the MILD Combustion Characteristics of Methane in a Model Combustor

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Journal of Thermal Science 2023年第2期32卷 822-836页

作者： ZHU Ziru XIOng yan LIU zhigang ZHAng Zhedian Key Laboratory of Advanced Energy and Power Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Moderate or Intense Low-oxygen Dilution(MILD)combustion has low emission potential in gas *** present work has investigated the performance of MILD combustion with parallel-jet burner arrangement in dry and steam-diluted *** combustion tests were conducted in atmospheric pressure at various equivalence ratios from LBO(Lean Blow Out)to near-stoichiometric conditions and steam-to-air mass ratios from 0 to 0.2.A simplified chemical reactors network(CRN)model based on MILD combustion concept has been established to study the effect of steam dilution on different pathways of NO *** experimental results show that under the same adiabatic flame temperature,the reaction zone gradually moves downstream with the increase of steam *** the high steam content(0.2 kg/kg),the reaction zone is widely distributed,and the distribution of reaction intensity in the reaction zone is more *** average lift-off height of reaction zone is proportional to the steam *** the steam content of 0.2 kg/kg,the average lift-off height reaches 2.5 times that of the dry conditions,which brings the risk of *** the adiabatic flame temperature of 1650–1900 K,the emissions of NOxare below 3×10–6(at 15%O2,dry)when the steam content varies from 0 to 0.2 kg/kg,which indicates the ultra-low emissions can be obtained under large changes in steam *** the inlet temperature of 381 K,as the steam content increases,the Prompt NO is dominant in the total NO *** dilution results in a smaller operating range with lower CO *** the steam content reaches 0.2 kg/kg,compared to the dry condition,the carbon monoxide emission increases *** addition,the LBO equivalence ratio of combustion with larger steam content is significantly higher.

关键词： MILD combustion steam dilution chemical reactors network(CRN) NOx emissions

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Synergistic Use of AIRS and MODIS for Dust Top Height Retrieval over Land

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Advances in Atmospheric Sciences 2015年第4期32卷 470-476页

作者： yAO zhigang Jun LI ZHAO Zengliang Beijing Institute of Applied Meteorology Cooperative Institute for Meteorological Satellite Studies University of Wisconsin-Madison

It is nontrivial to extract the dust top height（DTH） accurately from passive instruments over land due to the complexity of the surface conditions. The Moderate Resolution Imaging Spectroradiometer（MODIS） deep blue（DB） algorithm can be used to infer the aerosol optical depth（AOD） over high-reflective surfaces. The Atmospheric Infrared Sounder（AIRS） can simultaneously obtain the DTH and optical depth information. This study focuses on the synergistic use of AIRS observations and MODIS DB results for improving the DTH by using a stable relationship between the AIRS infrared and MODIS DB AODs. A one-dimensional variational（1DVAR） algorithm is applied to extract the DTH from AIRS. Simulation experiments indicate that when the uncertainty of the dust optical depth decreases from 50% to 20%, the improvement of the DTH retrieval accuracy from AIRS reaches 200 m for most of the assumed dust conditions. For two cases over the Taklimakan Desert, the results are compared against Cloud-Aerosol Lidar with Orthogonal Polarization（CALIOP） measurements. The results confirm that the MODIS DB product could help extract the DTH over land from AIRS.

关键词： AIRS MODIS dust height Cloud-Aerosol Lidar with Orthogonal Polarization

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