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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 163-178页

作者： Wu Houli Guo Endong Wang Jingyi dai Xin dai Chenxi Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationHarbin 150080China Key Laboratory of Earthquake Disaster Mitigation Ministry of Emergency ManagementHarbin 150080China

As an important part of nonstructural components,the seismic response of indoor water supply pipes deserves much *** paper presents shaking table test research on water supply pipes installed in a full-scale reinforced concrete(RC)frame *** material pipes and different methods for penetrating the reinforced concrete floors are combined to evaluate the difference in seismic *** response spectra and pipe acceleration amplification factors based on test data are discussed and compared with code provisions.A seismic fragility study of displacement demand is conducted based on numerical *** acceleration response and displacement response of different combinations are *** results show that the combination of different pipe materials and different passing-through methods can cause obvious differences in the seismic response of indoor riser pipes.

关键词： water supply pipe different materials shaking table test amplification factor seismic fragility

Heavy Traffic Limit Theorems for a Queue with Poisson ON/OFF Long-range Dependent Sources and General Service Time Distribution

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Acta Mathematicae Applicatae Sinica 2012年第4期28卷 807-822页

作者： Wan-yang dai Department of Mathematics and State Key Laboratory of Novel Software TechnologyNanjing University

In Internet environment, traffic flow to a link is typically modeled by superposition of ON/OFF based sources. During each ON-period for a particular source, packets arrive according to a Poisson process and packet sizes （hence service times） can be generally distributed. In this paper, we establish heavy traffic limit theorems to provide suitable approximations for the system under first-in first-out （FIFO） and work-conserving service discipline, which state that, when the lengths of both ON- and OFF-periods are lightly tailed, the sequences of the scaled queue length and workload processes converge weakly to short-range dependent reflecting Gaussian processes, and when the lengths of ON- and/or OFF-periods are heavily tailed with infinite variance, the sequences converge weakly to either reflecting fractional Brownian motions （FBMs） or certain type of long- range dependent reflecting Gaussian processes depending on the choice of scaling as the number of superposed sources tends to infinity. Moreover, the sequences exhibit a state space collapse-like property when the number of sources is large enough, which is a kind of extension of the well-known Little＇s law for M/M/1 queueing system. Theory to justify the approximations is based on appropriate heavy traffic conditions which essentially mean that the service rate closely approaches the arrival rate when the number of input sources tends to infinity.

关键词： reflecting fractional Brownian motion reflecting Gaussian process long-range dependence queueing process weak convergence

Stresses due to an adhesion crack in T-shaped junction of two orthotropic plates

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Acta Mechanica Sinica 2012年第2期28卷 419-423页

作者： dai-Heng Chen Department of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-ku Tokyo 162-8601 Japan

The general solution of stresses is derived for a T-shaped junction of two thin plates with an adhesion crack. The plates are orthotropic. A shear force is applied on the crack surface. The analysis is based on the supposition that the stresses in each plate can be approximated by a plane stress condition. The results obtained are verified by numerical calculation of FEM.

关键词： Elasticity Crack Thin plate T-shaped Junc-tion Hilbert Problem

Designing nonlinear thermal devices and metamaterials under the Fourier law: A route to nonlinear thermotics

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Frontiers of physics 2021年第5期16卷 107-142页

作者： Gao-Le dai School of Sciences Nantong UniversityNantong226019China

Nonlinear heat transfer can be exploited to reveal novel transport phenomena and thus enhance people’s ability to manipulate heat flux at ***,there has not been a mature discipline called nonlinear thermotics like its counterpart in optics or acoustics to make a systematic summary of relevant *** the current review,we focus on recent progress in an important part of nonlinear heat transfer,i.e.,tailoring nonlinear thermal devices and metamaterials under the Fourier law,especially with temperature-dependent thermal *** will present the basic designing techniques including solving the equation directly and the transformation *** nonlinearity coming from multi-physical effects,and how to calculate effective properties of nonlinear conductive composites using the effective medium theory are also *** on these theories,researchers have successfully designed various functional materials and devices such as the thermal diodes,thermal transistors,thermal memory elements,energy-free thermostats,and intelligent thermal materials,and some of them have also been realized in ***,these phenomenological works can provide a feasible route for the development of nonlinear thermotics.

关键词： nonlinear thermotics thermal metamaterials thermal conduction thermal radiation thermal convection thermo-mechanical effects effective medium theory

Ideal Mixing of Scalar Mesons and Hyperon-Nucleon Interactio~

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Chinese Physics Letters 2010年第6期27卷 40-43页

作者： dai Lian-Rong Department of Physics Liaoning Normal University Dalian 116029

The mixing of scalar mesons is an open problem since their structure is unclear and controversial. By introducing the ideal mixing of scalar mesons, we dynamically investigate the hyperon-nucleon interaction in the ehiral SU （ 3 ） quark model by solving the resonating group method （RGM） equation. The results show that when the ideal mixing of scalar mesons is considered and the mass of a k meson is reduced to near 780 MeV, then the hyperonnucleon scattering data can be reasonably described in the ehiral SU（3） quark model. Hence we find that the experimental mass of the n meson is around 780 MeV, and fo（600） and fo（980） mesons are the ideal mixing of scalar singlet and octet mesons.

关键词： Mixing Models Weight

Flexural rigidity of honeycomb consisting of hexagonal cells

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Acta Mechanica Sinica 2011年第5期27卷 840-844页

作者： dai-Heng Chen Department of Mechanical Engineering Tokyo University of Science1-3 Kagurazaka Shinjuku-kuTokyo 162-8601 Japan

In this study,the flexural rigidity of a honeycomb consisting of regular hexagonal cells is *** is found that the honeycomb bending can not be evaluated by using the equivalent elastic moduli obtained from the in-plane deformation because the moments acting on the inclined cell wall are different for in-plane deformation and bending *** on the fact that the inclined wall is twisted under the condition of the rotation angle in both connection edges being zero,a theoretical technique for calculating the flexural rigidity of honeycombs is proposed,and the validity of the present analysis is demonstrated by numerical results obtained by BFM.

关键词： Honeycomb · Flexural rigidity · Equivalent elastic modulus · Bending · Elasticity

Characterization and catalytic performance of CeO_2-Co/SiO_2 catalyst for Fischer-Tropsch synthesis using nitrogen-diluted synthesis gas over a laboratory scale fixed-bed reactor

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Journal of Natural Gas Chemistry 2008年第1期17卷 17-23页

作者： Xiaoping dai Changchun Yu The Key Laboratory of Catalysis China National Petroleum Corporation China University of Petroleum Beijing 102249 China

The surface species of CO hydrogenation on CeO2-Co/SiO2 catalyst were investigated using the techniques of temperature programmed reaction and transient response method. The results indicated that the formation of H2O and CO2 was the competitive reaction for the surface oxygen species, CH4 was produced via the hydrogenation of carbon species step by step, and C2 products were formed by the polymerization of surface-active carbon species （-CH2-）. Hydrogen assisted the dissociation of CO. The hydrogenation of surface carbon species was the rate-limiting step in the hydrogenation of CO over CeO2-Co/SiO2 catalyst. The investigation of total pressure, gas hourly space velocity （GHSV）, and product distribution using nitrogen-rich synthesis gas as feedstock over a laboratory scale fixed-bed reactor indicated that total pressure and GHSV had a significant effect on the catalytic performance of CeO2-Co/SiO2 catalyst. The removal of heat and control of the reaction temperature were extremely critical steps, which required lower GHSV and appropriate CO conversion to avoid the deactivation of the catalyst. The feedstock of nitrogen-rich synthesis gas was favorable to increase the conversion of CO, but there was a shift of product distribution toward the light hydrocarbon. The nitrogen-rich synthesis gas was feasible for F-T synthesis for the utilization of remote natural gas.

关键词： CeO2-Co/SiO2 catalyst Fischer-Tropsch synthesis surface species reaction condition nitrogen-rich synthesis gas product distribution

Energy-efficient Approach to Minimizing the Energy Consumption in An Extended Job-shop Scheduling Problem

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 1048-1055页

作者： TANG Dunbing dai Min College of Mechanical and Electrical Engineering Nanjing University of Aeronautics & Astronautics Jiangsu Key Laboratory of Precision and Micro-manufacturing Technology Nanjing University of Aeronautics & Astronautics

The traditional production planning and scheduling problems consider performance indicators like time, cost and quality as optimization objectives in manufacturing processes. However, environmentally-friendly factors like energy consumption of production have not been completely taken into consideration. Against this background, this paper addresses an approach to modify a given schedule generated by a production plarming and scheduling system in a job shop floor, where machine tools can work at different cutting speeds. It can adjust the cutting speeds of the operations while keeping the original assignment and processing sequence of operations of each job fixed in order to obtain energy savings. First, the proposed approach, based on a mixed integer programming mathematical model, changes the total idle time of the given schedule to minimize energy consumption in the job shop floor while accepting the optimal solution of the scheduling objective, makespan. Then, a genetic-simulated annealing algorithm is used to explore the optimal solution due to the fact that the problem is strongly NP-hard. Finally, the effectiveness of the approach is performed small- and large-size instances, respectively. The experimental results show that the approach can save 5%-10% of the average energy consumption while accepting the optimal solution of the makespan in small-size instances. In addition, the average maximum energy saving ratio can reach to 13%. And it can save approximately 1%-4% of the average energy consumption and approximately 2.4% of the average maximum energy while accepting the near-optimal solution of the makespan in large-size instances. The proposed research provides an interesting point to explore an energy-aware schedule optimization for a traditional production planning and scheduling problem.

关键词： energy consumption makespan production planning and scheduling job-shop floor different cutting speeds

Single Image Dehazing Based on Combining Dark Channel Prior and Scene Radiance Constraint

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Chinese Journal of Electronics 2016年第6期25卷 1114-1120页

作者： ZENG Liang dai Yongzhen College of Computer National University of Defense Technology

Images captured in foggy or hazy weather conditions often suffer from poor visibility. The dark channel prior method has well solved the single image dehazing problem in nature, but it is invalid when the scene objects are inherently similar to the atmospheric light and no shadow is cast on them. We propose an efficient regularization method by adding a scene radiance constraint and combing the dark channel prior to remove hazes from a single input image. The experiments show that this improved algorithm can deal with various levels of foggy weather conditions, as well as greatly enhance the image's visibility and details. In addition, the recovered haze-free image has little or no halo artifacts.

关键词： Image dehazing Scene radiance constraint Dark channel prior Visibility enhancement Detail augment

Numerical simulation of flow and heat transfer in a random packed bed

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Particuology 2010年第3期8卷 293-299页

作者： Xueyan Guo Ren dai School of Energy and Power Engineering University of Shanghai for Science and Technology S 16Jun Gong Road Shanghai 200093 China

Random packed beds have more complex interior structure than structured beds and are widely used in industry and engineering. CFD simulation was carried out to investigate and analyze the local flow and heat transfer in a 120-sphere random packed bed. 3D Navier-Stokes equation was solved with a finite volume formulation based on the Chimera meshing technique. Investigation was focused on low Reynolds number flow （Re=4.6-56.2）, which typically occurs in packed bed reactors in bio-chemical fields. Detailed temperature field information was obtained. Inhomogeneity of flow and heat transfer due to the non-uniform distribution of void fraction was discussed and analyzed.

关键词： Packed bed Heat transfer Chimera grid Numerical simulation Low Reynolds number