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A deoxidation thermodynamic model for 304 stainless steel considering multiple-components coupled reactions

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Journal of Iron and Steel Research International 2024年第1期31卷 74-91页

作者： Yan Yan Guang-hao Shang li-ping Zhang Shao-ying li han-jie Guo School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China Beijing Key Laboratory of Special Melting and Preparation of high-End Metal Materials Beijing100083China henan Jinhui Stainless Steel Industry Group Co. Ltd.Xuchang461500HenanChina Changge Jinhui Recycling Metal R&D Co. Ltd.Xuchang461500HenanChina

A thermodynamic model for predicting the equilibrium oxygens of 304 stainless steel was developed based on the theory of slag-steel equilibrium,the law of mass conservation,and the ion and molecule coexistence *** the developed model,the Fe-Cr-Mn-Si-Al-S-O-melts reaction system and CaO-MgO-CaF_(2)-FeO-MnO-Al_(2)O_(3)-SiO_(2)-Cr2O_(3)slags were *** oxygen contents calculated by the model are in good agreement with experimental results and reference *** equilibrium oxygen contents in 304 stainless steel mainly decrease with increasing binary basicity(w(CaO)/w(SiO_(2)),where w(i)is the mass percentage of component i)and decreasing *** binary basicity at 2.0 while maintaining temperatures lower than 1823 K will keep the oxygen contents in the 304 stainless steel lower than 15×10^(-6).The equilibrium oxygen contents may also be decreased with increasing content of MgO in slags,which is more significant at lower binary ***,a small amount of FeO,MnO,and Al_(2)O_(3)(about 0-2.5 wt.%)in slags has little effect on equilibrium oxygen ***,it is found that the[C]-[O]reaction may occur during refining process but will not significantly affect the equilibrium oxygen contents.

关键词： Complex deoxidation Thermodynamic model Ion and molecule coexistence theory 304 stainless steel Slag-steel reaction

Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PChE straight channel

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Petroleum Science 2024年第2期21卷 1275-1289页

作者： Qian li Zi-jie lin liu Yang Yue Wang Yue li Wei-hua Cai Laboratory of Thermo-Fluid Science and Nuclear Engineering Northeast Electric Power UniversityJilin132000JilinChina School of Energy and Power Engineering Northeast Electric Power UniversityJilin132000JilinChina

The printed circuit heat exchanger(PChE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PChE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 *** simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow *** results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were *** calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So hea

关键词： Printed circuit heat exchanger Vaporization Supercritical methane Pseudo-boiling Micro segment analysis

hydrogen generation from NaBh_(4) for portable proton exchange membrane fuel cell

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Materials Reports(Energy) 2024年第1期4卷 69-78页

作者： Bingxue Sun Xingguo li jie Zheng Beijing National Laboratory for Molecular Sciences(BNLMS) College of Chemistry and Molecular EngineeringPeking UniversityBeijing100871PR China

Sodium borohydride(NaBh_(4)) is considered as the most potential hydrogen storage material for portable proton exchange membrane fuel cells(PEMFC)because of its high theoretical hydrogen ***,the slow and poor kinetic stability of hydrogen generation from NaBh_(4) hydrolysis limits its *** are two main factors influencing the kinetics stability of hydrogen generation from NaBh_(4).One factor is that the alkaline byproducts(NaBO_(2)) of the hydrolysis reaction can increase the ph of the solution,thus inhibiting the reaction *** mainly happens in the NaBh_(4) solution hydrolysis *** factor is that the monotonous increase in reaction temperature leads to uncontrollable and unpredictable hydrolysis rates in the solid NaBh_(4) hydrolysis *** is due to the excess heat generated from this exothermic reaction in the initial reaction of NaBh_(4) *** this perspective,we summarize the latest research progress in hydrogen generation from NaBh_(4) and emphasize the design principles of catalysts for hydrogen generation from NaBh_(4) solution and solid state NaBh_(4).The importance of carbon as catalyst support material for NaBh_(4) hydrolysis is also highlighted.

关键词： NaBh_(4)hydrolysis hydrogen generation Catalyst Kinetics Carbon support materials

Chaotic CS Encryption:An Efficient Image Encryption Algorithm Based on Chebyshev Chaotic System and Compressive Sensing

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Computers, Materials & Continua 2024年第5期79卷 2625-2646页

作者： Mingliang Sun jie Yuan Xiaoyong li Dongxiao liu Key Laboratory of Trustworthy Distributed Computing and Service(BUPT) Ministry of EducationBeijing University of Posts and TelecommunicationsBeijing100876China

Images are the most important carrier of human information. Moreover, how to safely transmit digital imagesthrough public channels has become an urgent problem. In this paper, we propose a novel image encryptionalgorithm, called chaotic compressive sensing (CS) encryption (CCSE), which can not only improve the efficiencyof image transmission but also introduce the high security of the chaotic system. Specifically, the proposed CCSEcan fully leverage the advantages of the Chebyshev chaotic system and CS, enabling it to withstand various attacks,such as differential attacks, and exhibit robustness. First, we use a sparse trans-form to sparse the plaintext imageand then use theArnold transformto perturb the image pixels. After that,we elaborate aChebyshev Toeplitz chaoticsensing matrix for CCSE. By using this Toeplitz matrix, the perturbed image is compressed and sampled to reducethe transmission bandwidth and the amount of data. Finally, a bilateral diffusion operator and a chaotic encryptionoperator are used to perturb and expand the image pixels to change the pixel position and value of the compressedimage, and ultimately obtain an encrypted image. Experimental results show that our method can be resistant tovarious attacks, such as the statistical attack and noise attack, and can outperform its current competitors.

关键词： Image encryption chaotic system compressive sensing arnold transform

hybrid Analytical and Data-Driven Model Based Instance-Transfer Method for Power System Online Transient Stability Assessment

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1664-1675页

作者： Feng li Qi Wang Yi Tang Yan Xu jie Dang School of Electrical Engineering Southeast UniversityNanjing 210000China Center for Power Engineering(CPE) School of Electrical and Electronic EngineeringNanyang Technological UniversitySingapore 639798Singapore Central China Branch of State Grid Corporation of China Wuhan 430077China

Data-driven methods are widely recognized and generate conducive results for online transient stability ***,the tedious and time-consuming process of sample collection is often *** functioning of power systems involves repetitive sample collection due to the constant variations occurring in the operation mode,thereby highlighting the importance of collection *** a means to achieve high sample collection efficiency following the operation mode change,we propose a novel instance-transfer method based on compression and matching strategy,which facilitates the direct acquisition of useful previous samples,used for creating the new sample ***,we present a hybrid model to ensure rationality in the process of sample similarity comparison and selection,where features of analytical modeling with special significance are introduced into data-driven *** the same time,a data-driven method can also be integrated in the hybrid model to achieve rapid error correction of analytical models,enabling fast and accurate post-disturbance transient stability *** a paradigm,we consider a scheme for online critical clearing time estimation,where integrated extended equal area criterion and extreme learning machine are employed as analytical model part and data-driven error correction model part,*** results validate the credible efficacy of the proposed method.

关键词： Critical clearing time extreme learning machine instance-transfer method transient stability assessment

Optimal mining sequence for coal faces under a bedding slope:insight from landslide prevention

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Journal of Mountain Science 2024年第5期21卷 1775-1798页

作者： li Qingmiao ZhAO Jianjun li Zhichao DENG jie ZUO Jing LAI Qiyi State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China

Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.

关键词： Bedding rock landslides Mining-induced deformation Bedding slope stability Underground mining sequences Fractal-based strength reduction method

Electron engineering of nickel phosphide for Ni^(δ+) in electrochemical nitrate reduction to ammonia

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Nano Research 2024年第6期17卷 4864-4871页

作者： jie hu hao huang Miao Yu Shuang Wang Jinping li College of Environmental Science and Engineering Taiyuan University of TechnologyJinzhong 030600China School of Sustainable Energy Materials and Science Jinhua Advanced Research InstituteJinhua 321000China Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization Taiyuan University of TechnologyTaiyuan 030024China

The electrochemical reduction of nitrate to ammonia(ENRA)provides an efficient approach to remove nitrate pollution and achieve ammonia production ***,inspired by bio-enzyme in denitrifying bacteria,a carbon-coated nickel phosphide(NiPC)nanosheet derived from metal-organic frameworks(MOFs)is proposed as an efficient catalyst for *** electron engineering,controllable Ni^(δ+)in nickel phosphide is achieved by regulating the degree of phosphating,which enhances its activity for the hydrogenation of *** the result,Niδ+becomes one of dominating factors determining the efficiency of the ENRA reaction in nickel *** optimal NiPC catalyst exhibits impressive property toward ENRA:Nh_(4)^(+)Faraday efficiency of 96.68%,Nh4+selectivity of 99.04%,and nitrate conversion rate of 90.43%under low nitrate concentration(200 mg·L^(−1)).This work opens a new avenue for the design of next-generation catalysts through electron engineering for ENRA.

关键词： electron engineering transition metal phosphide nitrate reduction ammonia production metal-organic frameworks

Optimal Strategy for Aircraft Pursuit-evasion Games via Self-play Iteration

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Machine Intelligence Research 2024年第3期21卷 585-596页

作者： Xin Wang Qing-Lai Wei Tao li jie Zhang State Key Laboratory of Management and Control for Complex Systems Institute of AutomationChinese Academy of SciencesBeijing100190China School of Artificial Intelligence University of Chinese Academy of SciencesBeijing100049China Institute of Systems Engineering Macao University of Science and TechnologyMacao999078China

In this paper,the pursuit-evasion game with state and control constraints is solved to achieve the Nash equilibrium of both the pursuer and the evader with an iterative self-play *** the condition where the hamiltonian formed by means of Pontryagin’s maximum principle has the unique solution,it can be proven that the iterative control law converges to the Nash equilibrium ***,the strong nonlinearity of the ordinary differential equations formulated by Pontryagin’s maximum principle makes the control policy difficult to figured *** the system dynamics employed in this manuscript contains a high dimensional state vector with *** practical applications,such as the control of aircraft,the provided overload is ***,in this paper,we consider the optimal strategy of pursuit-evasion games with constant constraint on the control,while some state vectors are restricted by the function of the *** address the challenges,the optimal control problems are transformed into nonlinear programming problems through the direct collocation ***,two numerical cases of the aircraft pursuit-evasion scenario are given to demonstrate the effectiveness of the presented method to obtain the optimal control of both the pursuer and the evader.

关键词： Differential games pursuit-evasion games nonlinear control optimal control Nash equilibrium solution

hydrogen-rich surface of MoC catalysts for efficient CO_(2) hydrogenation induced by a coupled hydrogen donator

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Nano Research 2024年第8期17卷 7762-7767页

作者： Dong Xu Si-Yuan Xia Qi-Yuan li jie-Sheng Chen Xin-hao li School of Chemistry and Chemical Engineering Frontiers Science Center for Transformative MoleculesShanghai Jiao Tong UniversityShanghai 200240China

Direct CO_(2) hydrogenation offers an important strategy for promoting the global carbon balance,but high thermodynamic and kinetic stability of CO_(2) has restricted its applicability to only a handful of industrial ***,we introduce a proof-of-concept application of the electron-rich Pt surface to promote hydrogen donation for electron-rich MoC particles acting as hydrogen acceptors,thereby constructing hydrogen-rich surface of MoC active ***,the formed hydrogen-rich and electronrich surface could greatly decrease reaction activation energy to boost the efficient CO_(2) hydrogenation into formic acid over the MoC *** optimized MoC@NC/Pt-0.1(NC:nitrogen-doped carbon)catalyst exhibits a high turnover frequency(TOF)value of 1.2 h^(−1) at a lower temperature of 60℃and a TOF of 24.2 h^(−1) under standard reaction conditions widely used in the literature,exceeding 7 times of MoC@NC catalyst and surpassing the benchmark classical non-noble metal active center-based heterogeneous catalyst.

关键词： electron-rich Pt nanoparticles hydrogen donation hydrogen-rich MoC nanoparticles CO_(2) hydrogenation formic acid