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Influence of nanosized magnesia on the hydration of borehole-sealing cements prepared using different methods

International Journal of Coal Science & Technology 2023年第4期10卷 343-360页

作者： Quanle Zou Jinfei Zhan Xin Wang Zhen Huang State Key Laboratory of Coal Mine Disaster Dynamics and Control School of Resources and Safety EngineeringChongqing UniversityChongqing 400044China

Gas drainage is an efective technology for gas control in coal mines.A high borehole-sealing quality is the fundamental precondition for efcient gas *** expansibilities of cement pastes used in borehole-sealing processes are critical for the borehole-sealing *** magnesia expansive agents are used to improve the expansibilities of cement pastes and improve the borehole-sealing *** magnetic resonance spectrometry and scanning electron microscopy were adopted to study the efects of nanosized magnesia on the hydration of borehole-sealing cements used with diferent preparation *** results showed that an increase in the mass fraction of the nanosized magnesia promoted cement hydration,and the mass fraction was positively correlated with the promotion *** use of diferent preparation methods did not change the water-phase distribution in the *** using the wet-mixing preparation method,nanosized magnesia promoted the induction,acceleration,and deceleration periods of hydration;when using the dry-mixing preparation method,the nanosized magnesia promoted the induction period of cement hydration,and the promotion efect was less obvious than that seen when using the wet-mixing *** using the wet-mixing preparation method,the nanosized magnesia was uniformly dispersed,thus enlarging the surface area of the reaction,which provided more nucleation sites for the hydration products of the cement and therefore accelerated the hydration *** using the dry-mixing preparation method,the nanosized magnesia powders were dispersed nonuniformly and *** these conditions,only a few nanosized magnesia particles on the surfaces of the aggregated clusters took part in hydration,so only a small number of nucleation sites were provided for the hydration products of *** led to inconsistent hydration of cement pastes prepared using the dry-mixing *** surface porosity of the cement prepared with the wet-mi

关键词： Borehole-sealing cement Nanosized magnesia Preparation method Hydration Morphological analysis Nuclear magnetic resonance relaxation analysis

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Temperature-Dependent Tearing Behavior of Rubber Materials:Characterization and Modeling

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Acta Mechanica Solida Sinica 2024年第2期37卷 316-326页

作者： Qinyuan Yao Feilong Zhang Pan Dong Ziyuan Zhao Yi He Weiguo Li Liming Chen State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China College of Aerospace Engineering Chongqing UniversityChongqing400044China

With the increasingly widespread application of rubber in many fields,there is a growing demand for quantitative characterization of temperature-dependent mechanical properties in high-temperature service *** critical tearing energy is an important criterion for determining whether rubber materials will experience tearing instability,while tear strength is a key parameter for rubber materials to resist *** is necessary to quantitatively characterize their evolution with *** theoretical research mainly relies on fitting a large amount of experimental data,which is not convenient for engineering ***,in this work,a temperature-dependent critical tearing energy model is firstly developed based on the force-heat equivalence energy density *** model considers the equivalent relationship between the critical tearing energy required for crack instability propagation and the thermal energy stored in the rubber *** is demonstrated that our model has higher prediction accuracy when compared to other ***,combining with the Griffith fracture theory,temperature-dependent tear strength models applicable to three different crack modes are separately *** models are validated using experimental data for Mode I opening cracks and ModeⅢtearing cracks,and good consistency is ***,a quantitative analysis of the influence of elastic modulus on tear strength at different temperatures is *** work provides a reliable way for predicting temperature-dependent tearing instability behavior and offers beneficial suggestions for improving the tear strength of rubber materials at different temperatures.

关键词： Temperature-dependent Critical tearing energy Tear strength Rubber Theoretical model

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Interaction and characteristics of furfural residues and polyvinyl chloride in fast co-pyrolysis

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Frontiers of Chemical Science and Engineering 2024年第12期18卷 13-21页

作者： Yue Zhang Moshan Li Erfeng Hu Rui Qu Shuai Li Qingang Xiong State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China State Key Laboratory of Pulp and Paper Engineering South China University of TechnologyGuangzhou 510640China

This study investigated the interaction between the furfural residue and polyvinyl chloride co-pyrolysis using an infrared heating *** analytical techniques including production distribution analysis,thermal behavior,pyrolysis kinetic,simulated distillation and gas chromatography-mass spectrography(GCMS),and X-ray photoelectron spectroscopy were utilized to elucidate the pyrolysis characterization and reaction mechanism during the ***,the yield of co-pyrolysis oil increased from 35.12%at 5℃·s^(–1)to 37.70%at 10℃·s^(-1),but then decreased to 32.07%at 20℃·s^(-1).Kinetic and thermodynamic parameters suggested non-spontaneous and endothermic *** analysis revealed that aromatic hydrocarbons,especially mono-and bi-cyclic ones,are the predominant compounds in the oil due to the presence of H radicals in polyvinyl chloride,suggesting an enhancement in oil ***,the fixed chlorine content increased to 65.11%after co-pyrolysis due to the interaction between inorganic salts in furfural residues and chlorine from polyvinyl chloride.

关键词： infrared heating pyrolysis oil polyvinyl chloride chlorine co-pyrolysis

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Development and application of rock rheological constitutive model considering dynamic stress field and seepage field

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International Journal of Mining Science and Technology 2025年第3期35卷 467-482页

作者： Yian Chen Guangming Zhao Wensong Xu Shoujian Peng Jiang Xu Key Laboratory of Safe and Effective Coal Mining Ministry of Education Anhui University of Science and TechnologyHuainan 232001China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China

The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage *** results demonstrate that the rheological strain of the specimen under increased stress conditions is greater than that under creep conditions,indicating that the dynamic stress field significantly influences the rheological behaviours of *** the rheological tests,the number of small pores in the sandstone decreased,while the number of medium-sized pores increased,forming new seepage *** high initial rheological stress accelerated fracture compression and the closure of seepage channels,resulting in reduction in the permeability of *** on the principles of generalized rheology and the experimental findings,a novel rock rheological constitutive model incorporating both the dynamic stress field and seepage properties has been *** simulations of surrounding rock deformation in geotechnical engineering were carried out using a secondary development version of this model,which confirmed the applicability of the generalized rheological numerical simulation *** results provide theoretical support for the long-term stability evaluation of engineering rock masses and for predicting the deformation of surrounding rock.

关键词： Generalized rheological test Seepage-stress coupling Seepage properties Dynamic stress field Rheological constitutive model

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Fault diagnosis method of link control system for gravitational wave detection

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Journal of Systems Engineering and Electronics 2024年第4期35卷 922-931页

作者： GAO Ai XU Shengnan ZHAO Zichen SHANG Haibin XU Rui School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information TechnologyBeijing 100081China Key Laboratory of Dynamics and Control of Flight Vehicle Ministry of EducationBeijing 100081China

To maintain the stability of the inter-satellite link for gravitational wave detection,an intelligent learning monitoring and fast warning method of the inter-satellite link control system failure is *** from the traditional fault diagnosis optimization algorithms,the fault intelligent learning method pro-posed in this paper is able to quickly identify the faults of inter-satellite link control system despite the existence of strong cou-pling *** constructing a two-layer learning network,the method enables efficient joint diagnosis of fault areas and fault *** simulation results show that the average identification time of the system fault area and fault parameters is 0.27 s,and the fault diagnosis efficiency is improved by 99.8%compared with the traditional algorithm.

关键词： large scale multi-satellite formation gravitational wave detection laser link monitoring fault diagnosis deep learning

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Physical and numerical investigations of target stratum selection for ground hydraulic fracturing of multiple hard roofs

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International Journal of Mining Science and Technology 2024年第5期34卷 699-712页

作者： Binwei Xia Yanmin Zhou Xingguo Zhang Lei Zhou Zikun Ma State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China School of Resources and Safety Engineering Chongqing UniversityChongqing 400044China

Ground hydraulic fracturing plays a crucial role in controlling the far-field hard roof,making it imperative to identify the most suitable target stratum for effective *** experiments are conducted based on engineering properties to simulate the gradual collapse of the roof during longwall top coal caving(LTCC).A numerical model is established using the material point method(MPM)and the strain-softening damage constitutive model according to the structure of the physical *** simulations are conducted to analyze the LTCC process under different hard roofs for ground hydraulic *** results show that ground hydraulic fracturing releases the energy and stress of the target stratum,resulting in a substantial lag in the fracturing of the overburden before collapse occurs in the hydraulic fracturing *** hydraulic fracturing of a low hard roof reduces the lag effect of hydraulic fractures,dissipates the energy consumed by the fracture of the hard roof,and reduces the abutment ***,it is advisable to prioritize the selection of the lower hard roof as the target stratum.

关键词： Target stratum selection Ground hydraulic fracturing Hard roof control Fracture network Material point method

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Micro-characteristics of granite impinged by abrasive water jet from a mineralogical perspective

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Journal of Rock Mechanics and Geotechnical Engineering 2025年第2期17卷 1008-1017页

作者： Zhongtan Li Zhaolong Ge Qinglin Deng Zhe Zhou Lei Liu Jianming Shangguan Chuanfu Shao State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing400044China School of Resources and Safety Engineering Chongqing UniversityChongqing400044China

An abrasive water jet(AWJ)is commonly used to develop deep geothermal resources,such as drilling in hot dry rock(HDR).The influence of rock mineral properties,such as mineral types,mineral contents,and grain size,on the formation of perforation by AWJ is unclear *** this study,we investigate AWJ impacts on three types of granite samples with different mineral fractions using a polarizing microscope and scanning electron microscope(SEM).The results show that when the grain size is doubled,the perforation depth increases by 16.22%under the same type of structure and *** general,fractures are more likely to be created at the position of rough surfaces caused by abrasive impact,and the form of fractures is determined by the mineral *** addition,microstructure analysis shows that transgranular fractures typically pass through large feldspar particles and quartz removal occurs along mineral *** longitudinal extension of perforation depends mainly on the strong kinetic energy of the jet,while the lateral extension is controlled by the *** results contribute to a better understanding of the process involved in the breaking of hard rock by abrasive jets during deep geothermal drilling.

关键词： Abrasive water jet(AWJ) Drilling Hot dry rock(HDR) Perforation Fracture generation Removal mechanism

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On some properties of the Fredholm-type integral algebraic equations

On some properties of the Fredholm-type integral algebraic e...

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作者： Chistyakov, Viktor F. Chistyakova, Elena V. Laboratory for Differential Equations and Control Systems Institute for System Dynamics and Control Theory SB RAS Irkutsk Russia

In this paper, we study systems of Fredholm integral equations with a singular matrix multiplying the leading part. We address the solvability issues of such systems with separable kernels and, similarly to differenti... 详细信息

关键词： Fredholm integral equations

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Design Method for Seismic control Devices Installed on Steel Railway Bridges

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Quarterly Report of RTRI (Railway Technical Research Institute) 2024年第4期65卷 238-244页

作者： Wada, Kazunori Kushiya, Takuma Toyooka, Akihiro Structural Dynamics and Response Control Laboratory Center for Railway Earthquake Engineering Research Steel & Hybrid Structures Laboratory Structure Technology Division Center for Railway Earthquake Engineering Research

Authors have proposed a seismic control device with a bridge collapse prevention function installable in narrow spaces. In this paper, we introduce a method for designing the proposed device. Specifically, we organized the results of the nonlinear response analysis of a single degree of freedom system and proposed a nomogram that can be used to calculate the displacement of the girders and the response ductility factor of the piers in accordance with equipment specifications. By using this method, it is possible to have a rough idea of the specifications to meet the required performance before detailed dynamic analysis is carried out. © 2024 Ken-yusha Inc.. All rights reserved.

关键词： Railroad bridges

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Deep reinforcement learning using least-squares truncated temporal-difference

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CAAI Transactions on Intelligence Technology 2024年第2期9卷 425-439页

作者： Junkai Ren Yixing Lan Xin Xu Yichuan Zhang Qiang Fang Yujun Zeng College of Intelligence Science and Technology National University of Defense TechnologyChangshaChina State Key Laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'anChina

Policy evaluation(PE)is a critical sub-problem in reinforcement learning,which estimates the value function for a given policy and can be used for policy ***,there still exist some limitations in current PE methods,such as low sample efficiency and local convergence,especially on complex *** this study,a novel PE algorithm called Least-Squares Truncated Temporal-Difference learning(LST2D)is *** LST2D,an adaptive truncation mechanism is designed,which effectively takes advantage of the fast convergence property of Least-Squares Temporal Difference learning and the asymptotic convergence property of Temporal Difference learning(TD).Then,two feature pre-training methods are utilised to improve the approximation ability of ***,an Actor-Critic algorithm based on LST2D and pre-trained feature representations(ACLPF)is proposed,where LST2D is integrated into the critic network to improve learning-prediction *** simulation studies were conducted on four robotic tasks,and the corresponding results illustrate the effectiveness of *** proposed ACLPF algorithm outperformed DQN,ACER and PPO in terms of sample efficiency and stability,which demonstrated that LST2D can be applied to online learning control problems by incorporating it into the actor-critic architecture.

关键词： Deep reinforcement learning policy evaluation temporal difference value function approximation

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