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Measurement of boiling heat transfer coefficient in liquid nitrogen bath by inverse heat conduction method

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第5期10卷 691-696页

作者： Tao JIN jian-ping hong Hao ZHENG Ke TANG Zhi-hua GAN Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

Inverse heat conduction method (IHCM) is one of the most effective approaches to obtaining the boiling heat transfer coefficient from measured results. This paper focuses on its application in cryogenic boiling heat transfer. Experiments were conducted on the heat transfer of a stainless steel block in a liquid nitrogen bath, with the assumption of a 1D conduction condition to realize fast acquisition of the temperature of the test points inside the block. With the inverse-heat conduction theory and the explicit finite difference model, a solving program was developed to calculate the heat flux and the boiling heat transfer coefficient of a stainless steel block in liquid nitrogen bath based on the temperature acquisition data. Considering the oscillating data and some unsmooth transition points in the inverse-heat-conduction calculation result of the heat-transfer coefficient, a two-step data-fitting procedure was proposed to obtain the expression for the boiling heat transfer coefficients. The coefficient was then verified for accuracy by a comparison between the simulation results using this expression and the verifying experimental results of a stainless steel block. The maximum error with a revised segment fitting is around 6%, which verifies the feasibility of using IHCM to measure the boiling heat transfer coefficient in liquid nitrogen bath.

关键词： Inverse heat conduction method (IHCM) Liquid nitrogen bath Boiling heat transfer coefficient

New Exact Solutions and Interactions Between Two Solitary Waves for (3+1)-Dimensional Jimbo-Miwa System

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Communications in Theoretical Physics 2008年第5期49卷 1245-1248页

作者： MA Song-Hua FANG jian-ping hong Bi-Hai ZHENG Chun-Long College of Mathematics and Physics Lishui University Lishui 323000 China

By means of an extended mapping approach and a linear variable separation approach, a new family of exact solutions of the （3＋1）-dimensional Jimbo-Miwa system is derived. Based on the derived solitary wave solution... 详细信息

关键词： (3+1)-dimensional Jimbo-Miwa system exact solutions localized excitations the interactionsbetween two solitary waves

Steel-refractory reactions in lanthanum-,cerium-,and ytrium-added steels

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Journal of Iron and Steel Research International 2024年第6期31卷 1473-1485页

作者： jian Kang hong-po Wang Yu Wang College of Materials Science and Engineering Chongqing UniversityChongqing 400044China The State Key Laboratory of Mechanical Transmissions Chongqing UniversityChongqing 400044China

A systematic experimental study was conducted on the similarities and differences in the reactions between commonly used rare earth elements(REEs)and frequently used refractories in the steelmaking *** results indicate that the reaction behaviors of La,Ce,and Y with MgO,Al_(2)O_(3),and MgO·Al_(2)O_(3) crucibles differed *** consumption rates of La,Ce,and Y in the molten steel were in descending order of La>Ce>Y for smelting with all three kinds of *** the REEs reacted with the crucible,the contents of Mg and Al showed a trend of first increasing and then *** laboratory-scale smelting conditions,the reactions related to REEs were dominated by steel-crucible reactions,and the contact area between the unit mass of molten steel and refractory materials mainly determined the consumption rates of ***-and Ce-crucible reactions generated loose and porous reaction interfaces;however,Y-crucible reactions generated a dense Y_(2)O_(3) layer,dramatically suppressing the consumption rate of *** calculation indicated that the reactions between rare earth and different refractory materials were first-order *** crucible materials significantly affected the product type and morphology of the steel-crucible reaction interfaces,thereby influencing the consumption rate of *** reactions between REEs and refractories must be seriously considered,especially for small-scale smelting.

关键词： Rare earth Inclusion Refractory Thermodynamics Dynamics

Channel assignment and power allocation for throughput improvement with PPO in B5G heterogeneous edge networks

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Digital Communications and Networks 2024年第1期10卷 109-116页

作者： Xiaoming He Yingchi Mao Yinqiu Liu ping ping Yan hong Han Hu The College of Computer and Information Hohai UniversityNanjingChina The Key Laboratory of Water Big Data Technology of Ministry of Water Resources Hohai UniversityNanjing China The School of Computer Science and Engineering Nanyang Technological UniversitySingapore The College of Textile and Clothing Engineering Soochow UniversitySuzhouChina The College of Internet of Things Nanjing University of Posts and TelecomurunicationsNanjingChina

In Beyond the Fifth Generation(B5G)heterogeneous edge networks,numerous users are multiplexed on a channel or served on the same frequency resource block,in which case the transmitter applies coding and the receiver uses interference ***,uncoordinated radio resource allocation can reduce system throughput and lead to user inequity,for this reason,in this paper,channel allocation and power allocation problems are formulated to maximize the system sum rate and minimum user achievable *** the construction model is non-convex and the response variables are high-dimensional,a distributed Deep Reinforcement Learning(DRL)framework called distributed Proximal Policy Optimization(PPO)is proposed to allocate or assign ***,several simulated agents are trained in a heterogeneous environment to find robust behaviors that perform well in channel assignment and power ***,agents in the collection stage slow down,which hinders the learning of other ***,a preemption strategy is further proposed in this paper to optimize the distributed PPO,form DP-PPO and successfully mitigate the straggler *** experimental results show that our mechanism named DP-PPO improves the performance over other DRL methods.

关键词： B5G Heterogeneous edge networks PPO Channel assignment Power allocation Throughput

Adjuvant therapy for hepatocellular carcinoma:Dilemmas at the start of a new era

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World Journal of Gastroenterology 2024年第8期30卷 806-810页

作者： jian-hong Zhong Department of Hepatobiliary Surgery Guangxi Medical University Cancer HospitalNanning 530021Guangxi Zhuang Autonomous RegionChina

Approximately 50%-70%of patients with hepatocellular carcinoma experience recurrence within five years after curative hepatic resection or *** a result,many patients receive adjuvant therapy after curative resection or ablation in order to prolong recurrence-free *** therapy recommended by national guidelines can differ,and guidelines do not specify when to initiate adjuvant therapy or how long to continue *** and other unanswered questions around adjuvant therapies make it difficult to optimize them and determine which may be more appropriate for a given type of *** questions need to be addressed by clinicians and researchers.

关键词： Adjuvant therapy Hepatocellular carcinoma Tumor recurrence Unanswered questions

Coupling analysis method of grouting construction with deformation response of adjacent existing tunnel

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Underground Space 2024年第2期15卷 312-330页

作者： ping-wei jiang Zhi-hong Zhang hong Zheng Jin-kun Huang Key Laboratory of Urban Security and Disaster Engineering of China Ministry of Education Beijing University of TechnologyBeijing 100124China China MCC17 Group Co.LTD MaanshanAnhui 243000China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

In the new tunnel under close distance through the existing tunnel risk source,the grouting scheme developed to compensate for stratum losses is still based on empirical methods,relying on the overburden thickness of existing *** can potentially lead to an excessively high or low probability of uplift of existing *** a coupled deformation analysis method between the grouting construction and adjacent existing tunnels is of great theoretical significance for developing grouting *** order to reasonably limit the design parameters of grouting construction,based on the theory of fluid–solid coupling elastic pore-column expansion and the theory of random media,the calculation method of stratum displacement which simultaneously considers the coexistence of grout compaction expansion and permeability diffusion mode is derived,and the accuracy of the calculation method is verified by engineering *** accuracy of this calculation method was verified through engineering *** with the deformation coordination condition,the existing tunnel is regarded as an elastic Euler-Bernoulli continuous beam,and the finite element coupling balance equation of the interaction between the existing tunnel and the surrounding soil is *** on this,a coupling calculation model of the grouting construction and the deformation response of the adjacent existing tunnel is *** with three times of grouting construction examples in the shield tunneling project of Beijing Metro Line 12 under the existing airport line,the reliability of the coupling calculation model to determine the grouting construction parameters is *** calculation parameters in the coupling calculation model have clear physical meanings,which can provide a theoretical basis for the grouting design of similar risk source projects.

关键词： Grouting Close-range underpass Tunnel Random medium theory Euler-Bernoulli continuous beam

Correlation between fragmented QRS and the short-term prognosis of patients with acute myocardial infarction

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2014年第1期15卷 67-74页

作者： Qin-hui SHENG Chih-Chi HSU jian-ping LI Tao hong Yong HUO Department of Cardiology Peking University First Hospital Beijing 100034 China

This study is aimed to investigate the clinical significance and the short-term prognostic value of frag- mented QRS （fQRS） for patients with acute myocardial infarction （AMI）. Three hundred patients with AMI were tested with retrospective analysis on the patients＇ clinical information, hospitalized treatment, fQRS onset time, location of lesions, and other relevant data, in order to assess the relationship between the presence of fQRS and its prognosis. The rates of malignant cardiac arrhythmia, left ventricular systolic dysfunction （LVSD）, and mortality in the positive fQRS group were 13.6%, 29.2%, and 23.7%, respectively, with all showing a p value 〈0.05. For the ST segment elevation myocardial infarction （STEMI） subgroup, all the rates showed significant differences with a p value 〈0.01, while for the non-STEMI （NSTEMI） subgroup showed no significant differences. In patients with a positive fQRS, there were no differences in malignant cardiac arrhythmia between patients with and without percutaneous coronary in- tervention （PCI）（p〉0.05）. As for the LVSD and mortality, the p values between patients with and without PCI were 0.031 and 0.000, respectively, suggesting statistical significance. The results imply that AMI patients with positive fQRS especially for the patients with STEMI had higher rates of malignant cardiac arrhythmia, LVSD, and mortality than the non-fQRS group. Patients of AMI with positive fQRS, who underwent early revascularization, could lower the incidence of the cardiovascular event. In addition, the presence of fQRS could be used as an indication of early in- tervention treatment for patients.

关键词： Fragmented QRS Acute myocardial infarction Short-term prognosis

Grain refinement of 5A06 aluminum alloy welds caused by tungsten inert gas welding arc characteristics under Ar-He alternating gas supply conditions:a coupled method of water-cooled copper plate test/numerical simulation

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Journal of Iron and Steel Research International 2024年第3期31卷 767-777页

作者： hong-bin Dai jian Miao Jia-xin Lin School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040HeilongjiangChina

The welding arc,as a carrier for the conversion of electrical energy to thermal energy,has a direct impact on the quality of welding by its properties and *** the tungsten inert gas(TIG)welding process under the condition of Ar-He alternating gas supply,the arc is alternately converted between Ar arc and He arc with an alternating gas supply cycle,which has obvious arc change *** FLUENT software was used to numerically simulate the characteristics of the TIG arc under the condition of alternating gas supply,and the arc temperature field,arc pressure,electric potential and current density distribution under the condition of alternating gas supply were *** with the real-time data of arc pressure measured by the water-cooled copper plate with holes,it is proved that the TIG arc has obvious dynamic characteristics under the condition of Ar-He alternating gas *** unique dynamic TIG arc acts on the 5A06 aluminum alloy weld,causing the molten pool to stir,resulting in uniform microstructure and grain refinement at the weld,and thereby improving the mechanical properties of the welded joint.

关键词： Alternating gas supply Grain refinement Numerical simulation Tungsten argon arc morphology Microstructure Mechanical property

Accurate simulations of pure-viscoacoustic wave propagation in tilted transversely isotropic media

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Petroleum Science 2024年第2期21卷 866-884页

作者： Qiang Mao jian-ping Huang Xin-Ru Mu Ji-Dong Yang Yu-jian Zhang Geosciences Department China University of Petroleum(East China)Qingdao266580ShandongChina Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao266207ShandongChina

Forward modeling of seismic wave propagation is crucial for the realization of reverse time migration(RTM) and full waveform inversion(FWI) in attenuating transversely isotropic media. To describe the attenuation and anisotropy properties of subsurface media, the pure-viscoacoustic anisotropic wave equations are established for wavefield simulations, because they can provide clear and stable wavefields. However, due to the use of several approximations in deriving the wave equation and the introduction of a fractional Laplacian approximation in solving the derived equation, the wavefields simulated by the previous pure-viscoacoustic tilted transversely isotropic(TTI) wave equations has low accuracy. To accurately simulate wavefields in media with velocity anisotropy and attenuation anisotropy, we first derive a new pure-viscoacoustic TTI wave equation from the exact complex-valued dispersion formula in viscoelastic vertical transversely isotropic(VTI) media. Then, we present the hybrid finite-difference and low-rank decomposition(HFDLRD) method to accurately solve our proposed pure-viscoacoustic TTI wave equation. Theoretical analysis and numerical examples suggest that our pure-viscoacoustic TTI wave equation has higher accuracy than previous pure-viscoacoustic TTI wave equations in describing q P-wave kinematic and attenuation characteristics. Additionally, the numerical experiment in a simple two-layer model shows that the HFDLRD technique outperforms the hybrid finite-difference and pseudo-spectral(HFDPS) method in terms of accuracy of wavefield modeling.

关键词： Pure-viscoacoustic TTI wave equation Attenuation anisotropy Seismic modeling Low-rank decomposition method