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Analytical solutions of uniform extended dislocations and tractions over a circular area in anisotropic magnetoelectroelastic bimaterials

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Acta Mechanica Sinica 2013年第1期29卷 73-84页

作者： Y.-F. Zhao X.-C. Shang E. Pan dept. of Civil Engineering University of Akron dept. of Applied Mechanics University of Science and Technology

In this paper, we derive the analytical solutions in a three-dimensional anisotropic magnetoelectroelastic bimaterial space subject to uniform extended dislocations and tractions within a horizontal circular area. By virtue of the Stroh formalism and Fourier transformation, the final expression of solutions in the physical domain contains only line integrals over [0, 2π] rather than infinite integrals. As the reduced cases, the half-space and homogeneous full-space solutions can be directly derived from the present solutions. Also, in terms of material domains, the present solutions can be reduced to the piezoelectric, piezomagnetic, purely elastic materials with different symmetries of material prop- erty. To carry out numerical calculations, Gauss quadrature is adopted. In the numerical examples, the effect of different loading locations on the response at the interface is analyzed. It is shown that, when the magnetic traction or electric dislocation is applied, the physical quantities on the interface may not decrease monotonically as the loading area moves away from the interface. The distributions of different in-plane physical quantities on the upper and lower interfaces under various extended horizontal loadings are compared and the differences are discussed. The work presented in this paper can serve as benchmarks for future numerical studies in related research fields.

关键词： Anisotropic bimaterial space. Magnetoelectroe- lastic Extended dislocations Extended tractions Circular loading Analytic solutions

Seismic risk assessment for developing countries: Pakistan as a case study

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Earthquake Engineering and Engineering Vibration 2018年第4期17卷 787-804页

作者： Shaukat A.Khan Kypros Pilakoutas Iman Hajirasouliha Reyes Garcia Maurizio Guadagnini dept. of Civil Engineering Abasyn University dept. of Civil and Structural Engineering The University of Sheffield

Modern Earthquake Risk Assessment（ERA） methods usually require seismo-tectonic information for Probabilistic Seismic Hazard Assessment（PSHA） that may not be readily available in developing countries. To bypass this drawback, this paper presents a practical event-based PSHA method that uses instrumental seismicity, available historical seismicity, as well as limited information on geology and tectonic setting. Historical seismicity is integrated with instrumental seismicity to determine the long-term hazard. The tectonic setting is included by assigning seismic source zones associated with known major faults. Monte Carlo simulations are used to generate earthquake catalogues with randomized key hazard parameters. A case study region in Pakistan is selected to demonstrate the effectiveness of the method. The results indicate that the proposed method produces seismic hazard maps consistent with previous studies, thus being suitable for generating such maps in regions where limited data are available. The PSHA procedure is developed as an integral part of an ERA framework named EQRAM. The framework is also used to determine seismic risk in terms of annual losses for the study region.

关键词： recycled concrete frame-shear wall concealed bracings shaking table test nonlinear time-history responseanalysis

Evaluating location specific strain rates, temperatures,and accumulated strains in friction welds through microstructure modeling

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Defence Technology（防务技术） 2018年第2期14卷 83-92页

作者： Javed Akram Prasad Rao Kalvala Vikas Jindal Mano Misra dept. of Metallurgical Engineering University of Utah dept. of Metallurgical Engineering Indian Institute of Technology(BHU)

A microstructural simulation method is adopted to predict the location specific strain rates, temperatures, grain evolution, and accumulated strains in the Inconel 718 friction welds. Cellular automata based 2D microstructure model was developed for Inconel 718 alloy using theoretical aspects of dynamic recrystallization. Flow curves were simulated and compared with experimental results using hot deformation parameter obtained from literature work. Using validated model, simulations were performed for friction welds of Inconel 718 alloy generated at three rotational speed i.e., 1200, 1500, and1500 RPM. Results showed the increase in strain rates with increasing rotational speed. These simulated strain rates were found to match with the analytical results. Temperature difference of 150 K was noticed from center to edge of the weld. At all the rotational speeds, the temperature was identical implying steady state temperature(0.89 T_m) attainment.

关键词： Microstructure modeling Dynamic recrystallization Friction welding Inconel 718 EBSD Hot deformation Strain map

Seismic fragility assessment of existing sub-standard low strength reinforced concrete structures

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Earthquake Engineering and Engineering Vibration 2015年第3期14卷 439-452页

作者： Sohaib Ahmad Nicolas Kyriakides Kypros Pilakoutas Kyriacos Neocleous Qaiser uz Zaman dept. of Civil and Structural Engineering University of Sheffield dept. of Civil Engineering and Geomatics Cyprus University of Technology dept. of Civil and Environmental Engineering University of Engineering and Technology

An analytical seismic fragility assessment framework is presented for the existing low strength reinforced concrete structures more common in the building stock of the developing *** realistic modelling of such substandard structures,low strength concrete stress-strain and bond-slip capacity models are included in calibrating material *** capacity parameters are generated stochastically to produce building population and cyclic pushover analysis is carried out to capture inelastic *** period values are evaluated corresponding to each displacement step on the capacity curves and used as seismic demand.A modified capacity demand diagram method is adopted for the degrading structures,which is further used to evaluate peak ground acceleration from back analysis considering each point on the capacity curve as performance *** developing fragility curves,the mean values of peak ground acceleration are evaluated corresponding to each performance point on the series of capacity curves.A suitable probability distribution function is adopted for the secant period scatter at different mean peak ground acceleration values and probability of exceedance of limit states is evaluated.A suitable regression function is used for developing fragility curves and regression coefficients are proposed for different confidence *** curves are presented for a low rise pre-seismic code reinforced concrete structure typical of developing countries.

关键词： analytical fragility damage index non-engineered b

A new spatial coherence model and analytical coeffi cients for multi-support response spectrum combination

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Earthquake Engineering and Engineering Vibration 2007年第3期6卷 225-235页

作者：王君杰陈虎 dept. of Bridge Engineering Tongji University

In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination （correlation） coefficients of structural response are developed for multi-support seismic excitations. The coefficients from both the numerical integration and analytical solutions are compared to verify the accuracy of the solutions. It is shown that the analytical expressions of numerical modal combination coefficients are of high accuracy. The results of random responses of an example bridge show that the analytical modal combination coefficients developed in this paper are accurate enough to meet the requirements needed in practice. In addition, the computational efficiency of the analytical solutions of the modal combination coefficients is demonstrated by the response computation of the example bridge. It is found that the time required for the structural response analysis by using the analytical modal combination coefficients is less than 1/20 of that using numerical integral methods.

关键词： multi-support seismic excitations spatial coherence model modal combination coefficients computational efficiency power spectrum density

Feasibility Study of R134a/R404a Cascade Heat Pump Cycle in Heat Pump Dryers with Electrical Heaters at Low Temperatures

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Journal of Thermal Science 2015年第5期24卷 463-467页

作者： Ji Woo Jeong Young Lim Lee dept. of Mechanical Engineering Kongju National University dept. of Mechanical and Automotive Engineering Kongju National University

Heat pump cycles have been widely applied to dryers for their high efficiency. However, low–efficiency electrical heaters are often used during early drying stage for frozen foods or winter since a standard heat pump cycle cannot operate at low temperature. This study introduced cascade heat pumps replacing electrical heaters to improve dryer performance at low temperatures. Experiments were performed to examine changes in performance of the cascade heat pump dryers in relation to ambient temperature, low-stage cycle mass flow rate, and high-stage cycle mass flow rate. The results showed a significant improvement in low-temperature dryer performance with the introduction of cascade heat pump cycles.

关键词： Cascade cycle R134a/R404a Heat pump dryer COP Energy efficiency

Effect of Oxygen Concentration and Annealing Theatment on the Optical Properties of the Transparent Conductive CdIn_2O_4 Thin Films

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Journal of Materials Science & Technology 1998年第2期14卷 161-166页

作者： Bin WU Changyong CHEN and Shibin ZHANG(Physics dept., Lanzhou University, Lanzhou 730000, China)Wanlu WANG and Kejun LIAO(Applied Physics dept., Chongqing University, Chongqing 400044, China) Physics dept. Lanzhou University Lanzhou 730000 China Applied Physics dept. Chongqing University Chongqing 400044 China

Transparent conductive cadmium indium oxide films (CdIn2O4) were prepared by r.f. reactive sputtering from Cd-In alloy targets under an Ar-O2 atmosphere. Electrical conductivity of the order of 105Ω-1.m-1 and the optical transmission as high as 94% are easily attained by postdeposition annealing treatment. The effects of oxygen concentration in the reactive gas mixture and post-deposition annealing treatment on the optical transmittance as well as optical parameters, such as refractive index (n), extinction coefficient (k), real part (ε') and imaginary part (ε') of the dielectric constant, were studied in the visible and near-infrared region. The highfrequency dielectric constant ε∞ the plasma frequency ωP, and the conduction band effective mass mc of different samples were also investigated

关键词： Thin Effect of Oxygen Concentration and Annealing Theatment on the Optical Properties of the Transparent Conductive CdIn2O4 Thin Films

Biodegradation of Leather Waste by Enzymatic Treatment

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过程工程学报 2006年第3期6卷 462-465页

作者： Muhammad Nauman Aftab Abdul Hameed Ikram-ul-Haq 陈润生 dept. Biol. Sci. Quaid-i-Azam Univ.IslamabadPakistan Bioinformatics LabInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China Graduate University of Chinese Academy of SciencesBeijing 100049China dept. Biol. Sci. Quaid-i-Azam Univ.IslamabadPakistan dept. botany Government College Univ.LahorePakistan Bioinformatics Lab Institute of BiophysicsChinese Academy of SciencesBeijing 100101China

The treatment of shavings,trimmings and splits of leather waste from tanneries has a potential to generate value-added products. In this study enzymatic treatment of leather waste was performed. This method utilizes alkaline protease produced by Bacillus subtilis in our laboratory by submerged fermentation. Optimum conditions of pH,time duration,temperature and concentration of enzyme were determined for maximum degradation of leather waste. The amount of degradation was measured by the release of amino acid hydroxyproline. Amino acid composition in the hydrolysate obtained by the enzyme hydrolysis was determined. This relative simple biotreatment of leather waste may provide a practical and economical solution.

关键词： leather waste biodegadation Bacillus subtilis alkaline protease

Novel implementation of homogenization method to predict effective properties of periodic materials

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Acta Mechanica Sinica 2013年第4期29卷 550-556页

作者： Geng-Dong Cheng Yuan-Wu Cai Liang Xu dept. of Engineering Mechanics Dalian University of Technology

Representative volume element （RVE） method and asymptotic homogenization （AH） method are two widely used methods in predicting effective properties of pe- riodic materials. This paper develops a novel implementa- tion of the AH method, which has rigorous mathematical foundation of the AH method, and also simplicity as the RVE method. This implementation can be easily realized using commercial software as a black box, and can use all kinds of elements available in commercial software to model unit cells with rather complicated microstructures, so the model may remain a fairly small scale. Several examples were car- fled out to demonstrate the simplicity and effectiveness of the new implementation.

关键词： Effective property ~ Periodic material - Homog-enization ~ RVE method