检索结果-南通市图书馆

ACOUSTIC REFLECTION FROM A BAFFLED ELASTIC/PIEZOELECTRIC PLATE

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2002年第2期15卷 156-162页

作者： Zhao Hanzhong (department of mechanics,Huazhong University of Science and Technology,{2.,{3.) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

A finite difference/boundary integral procedure to determine theacoustic reflected pressure from a fluid-loaded bi-laminated plate isdescribed. The bi-laminate is composed of a piezoelectric layer andan elastic layer in contact with the fluid, and is held by anacoustically hard baffle. In the numerical model, the fluid pressureat fluid/solid interface is replaced by a continuum of point sourcesweighted by the normal acceleration of the elastic plate, and thegoverning equation system is solved in the solid domain.

关键词： acoustic reflection baffled palte finite difference boundary integral

LAMINATED PIEZOELECTRIC PLATE FOR ACTIVE UNDERWATER ACOUSTIC CONTROL

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2001年第4期14卷 306-311页

作者： Zhao Hanzhong (department of mechanics,Huazhong University of Science and Technology,{2.,{3.) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The pressure reflected from a bi-laminated piezoelectric plate hasbeen determined using the Thomson-Haskell matrix method. The plate iscomposed of a piezoelectric layer with grounded vacuum and An elasticlayer in contact with the fluid. An incident plane wave in the fluidmedium strikes the plate at dif- Ferent angles. The required electricpotential across the piezoelectric layer to cancel the reflectionfrom the Fluid/elastic boundary has been determined for thepiezoelectric material PZT-5 at various thickness parame- Ters andincident frequencies.

关键词： underwater acoustic control laminated piezoelectric plate acousticscattering acoustic radiation

LAMINATED VISCOELASTIC PLATE WITH INCLUSIONS FOR PASSIVE UNDER-WATER ACOUSTIC CONTROL

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2002年第1期15卷 23-29页

作者： Zhao Hanzhong (department of mechanics,Huazhong University of Science and Technology,{2.,{3.) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The effectiveness of a fluid-loaded sandwiched viscoelastic layerin suppressing acoustic scat- tering and radiation has been estimatedusing the Thomson-Haskell matrix method. The GU (Gaunaurd andUberall) resonance theory has been adopted to handle three types ofviscoelastic substrates with air -filled in- Clusions. The effects ofthe varying thickness of the substrates, the volume fractions of theinclusions and fre- Quencies of incident waves have been studied todetermine the optimal strategies of signal reduction. In theInvestigation, the monopole resonance phenomena of the inclusionshave been taken into account.

关键词： underwater acoustic control laminated viscoelastic plate air-filledinclusion

Analysis on cohesive crack opening displacement considering the strain softening effect

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2.& ZHAO Xiqiang3.1. mechanics department, Shandong University of Technology, Zibo 2.5049, {2. 2. Civil Engineering department, Dalian University of Technology, Dalian 11602., {2. 3. Mathematics department, Ocean University of {2., Qingdao 2.6071, {2. mechanics department Shandong University of Technology Zibo China Civil Engineering department Dalian University of Technology Dalian China Mathematics department Ocean University of China Qingdao China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

ACOUSTIC REFLECTION FROM A PERIODIC ELASTIC/PIEZOELECTRIC PLATE

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2003年第4期16卷 321-326页

作者： Zhao Hanzhong (department of mechanics,Huazhong University of Science and Technology,{2.,{3.) department of mechanics Huazhong Univ. of Sci./Technology Wuhan 430074 China

The acoustic reflected pressure from a periodic elastic/piezoelectric laminated plate is studied for the purpose of acoustic reflection control.A finite difference/boundary integral procedure to determine the reflected pressure from the fluid-loaded plate is *** the numerical model,a Green's function in the form of infinite sum is employed and a boundary integral is performed to replace the fluid pressure at fluid/solid interface by a continuum of point sources weighted by the normal acceleration of the elastic *** equation system is then solved only in the solid *** is demonstrated that an appropriate applied voltage potential across the piezoelectric layer has the effect of cancelling the fundamental propagating mode,and there,is no reflection for frequencies up to the cut-off frequency of the next propagating mode if the fundamental mode has been eliminated.

关键词： acoustic reflection periodic plate finite difference boundary integral

Direct CP violation in hadronic B decays

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,mechanics & Astronomy) 2006年第3期49卷 357-366页

作者： HONG Bihai1,2.& Lü Caidian3.1. department of Physics, Lishui University, Lishui 3.0}000,{3. 2. department of Physics, Shanghai Jiaotong University, Shanghai 2.003., {3. 3. Institute of High Energy Physics, Beijing 100049,{3. department of Physics Lishui University Lishui China department of Physics Shanghai Jiaotong University Shanghai China Institute of High Energy Physics Beijing China

There are different approaches for the hadronic B decay calculations, recently. In this paper, we upgrade three of them, namely factorization, QCD factorization and the perturbative QCD approach based on kT factorization, using new parameters and full wave functions. Although they get similar results for many of the branching ratios, the direct CP asymmetries predicted by them are different, which can be tested by recent experimental measurements of B factories.

关键词： CP violation hadronic B decay factorization.

Spectral anomalies and spectral switches of partially coherent and polychromatic light diffracted at an aperture

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,mechanics & Astronomy) 2004年第1期47卷 24-35页

作者： Lü Baida1, 3.& PAN Liuzhan1, 2.1. Institute of Laser Physics and Chemistry, Sichuan University, Chengdu 610064, china 2. {3. of Physics, Luoyang Normal College, Luoyang 47102., china 3. State Key Laboratory of Laser Technology, Huazhong University of Science and Technology, {3., china Correspondence should be addressed to L Baida (email: badalu@***) Received July 10, 2.03 Institute of Laser Physics and Chemistry Sichuan University Chengdu China State Key Laboratory of Laser Technology Huazhong University of Science and Technology Wuhan China department of Physics Luoyang Normal College Luoyang China

Based on the propagation theory of partially coherent light in the space-frequency domain, the anomalous spectral behavior and spectral switches in the far field of partially coherent and polychromatic light diffracted at an aperture are studied. It is shown that, as compared with spatially fully coherent and polychromatic light whose spectral anomalies are induced only by aperture diffraction, the spectral anomalies and spectral switches of partially coherent and polychromatic light depend on the aperture diffraction, spatial correlationβ and bandwidth of the original spectrum. Detailed numerical calculations are made to illustrate the behavior of spectral switches of partially coherent and polychromatic light, and the results for spatially fully coherent and polychromatic light are treated as a special case ofβ=1 and included in our theory.

关键词： spectral anomaly spectral switch partially coherent and polychromatic light far field aperture diffraction

GREEN'S FUNCTIONS FOR A 2. ANISOTROPIC MEDIUM WITH A HYPERBOLIC BOUNDARY

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2000年第1期13卷 17-24页

作者： Hu Yiantai Huang Yuying Chen Chuanyao (department of mechanics,Huazhong University of Science and Technology,{2.,{3.) department of mechanics Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

By using Stroh's formalism and the conformal mapping technique,this paper derives simple exphcit Green's functions of a piezoelectric anisotropic body with a free or fixed hyperbolic *** corresponding elastic fields in the medium are obtained,*** particular,degenerated solutions of an ex- ternal crack from those of a hyperbolic problem are analysed in *** the singular stress fields and the fracture mechanics parameters are *** solutions obtained are valid not only for plane and antiplane problems but also for the coupled ones between inplane and outplane deformations.

关键词： Stroh's formalism conformal mapping Green's functions external crack stress intensity factors

Influence of moisture content and time on the mechanical behavior of polymer material

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2004年第5期47卷 595-607页

作者： ZHENG Gaofei1, 2. KANG Yilan1, SHENG Jing3. QIN Qinghua1, WANG Huaiwen1 & FU Donghui1 1. department of mechanics, Tianjin University, Tianjin 3.0072. {2. {3., Tianjin Polytechnic University, Tianjin 3.0160, {2. 3. department of Material Engineering, Tianjin University, Tianjin 3.0072. {2. Correspondence should be addressed to Kang Yilan department of mechanics Tianjin University Tianjin China department of mechanics Tianjin Polytechnic University Tianjin China department of Material Engineering Tianjin University Tianjin China

The effects of moisture content and time on mechanical behavior of polymer materials are investigated both theoretically and experimentally in this paper. An equivalence relationship between time intervals and the moisture content for polymer nylon-6 has been established by way of experimental observation and measured results. The relationship shows that there exists equivalence between moisture and service time in affecting mechanical properties. In other words, an increase in moisture can be replaced by prolonging acting time in producing the same effect on material properties. Consequently, a moisture-time superposition principle is presented based on the experimental results and the analogy of temperature-time superposition principle. Numerical results such as stress-strain curves with different moisture contents are presented to verify the applicability and correctness. The proposed method appears very promising in study on the effect of moisture content on mechanical behavior of polymer materials.

关键词： equivalence relationship of moisture-time, moisture content, mechanical properties, shift function.