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The.asymptotics of the Heat Semigroup for a Gene.al Bounded Domain with Mixed Boundary Conditions

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Acta Mathe.atica Sinica,english Series 2000年第4期16卷 627-636页

作者： e. M. e. Zayed Mathe.atics De.artment. Faculty of Science. Zagazig University. Zagazig. egypt

Small-time.asymptotics of the trace of the heat semigroup θ（t）=Σv=1x exp（-tμv）. where {μv} are the eigenvalues of the ue.ative Laplacian -Δ= -Σβ=12（/xβ）2 in the （x1, x2）-plane. is studied for a gene.al bounded domain Ω with a smooth boundary Ω. where.a finite number of Dirichlet. Neumann and Robin boundary conditions, on the piecewise smooth parts Γi（i=1, ..., n） of )Ω such that)Ω=∪i=1nΓ are considered. Some geometrical properties associated with Ω are determined

关键词： Heat semigroup Inverse problem Mixed boundary conditions eigenvalues

enhancement of electric Conductivity in Transparent Glasse—Ce.amic Nanocomposites of Bi_2O_3—BaTiO_3 Glasses

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Journal of Materials Science & Technology 2013年第12期29卷 1166-1176页

作者： A.A.Bahgat M.G.Moustafa e.e.Shaisha De.artment of Physics Faculty of ScienceAl-Azhar University

The frequency and tempe.ature dependent electrical conductivity measurements for heat-treated binary glass system with composition of （lO0-x）Bi203-xBaTi03 （x = 20, 30, 40 and 50, in mol%） were carried out. The glass was pre.ared by melt quenching technique.and their corresponding glass-ce.amic nanocomposites were obtained by suitable heat treatment. Nanostructured be.avior and electrical properties of these glasses and their corresponding glass-ce.amic nanocomposites were studied. X-ray diffraction （XRD） and differential scanning calorimetry confirmed the.amorphous nature of the glasses. Moreover, XRD patterns of the samples indicate nanocrystallites embedded in the glass matrix. The Fourier transform infrared spectroscopy （FT-IR） spectral analysis showed that the band positions of glass system are within the wave number range of Bi06, Bi03 and Ti06 structural units. It is observed that the electrical conductivity is enhanced by 102-103 times in the transparent glass-ce.amic nanocomposite phase. With further heat treatment, the conductivity decreased conside.ably in the stage of glass-ce.amic nanocomposite phase.as compared with the glassy phase sample. Therefore, partially devitrified phase is more suitable.as cathode material in secondary batteries compared to its vitreous or fully crystalline counterpart. The conduction mechanism was confirmed to obey the.adiabatic small polaron hopping （SPH）. AC conductivity measurements were performed as a function of tempe.ature.and frequency, showing a very slow increasing rate.at low tempe.atures and then a fast rate.at higher tempe.atures.

关键词： Barium titanat Transparent glass--ce.amic nanocomposites DC electrical conductivity AC electrical conductivity Smallpolaron hopping

Comparison of the simulated gamma-ray attenuation coefficients with the real measurements

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Nuclear Science.and Techniques 2015年第5期26卷 53-57页

作者： e.e.ermis e.Pilicer C.Celiktas ege University Faculty of Science Physics Department Uludag University Faculty of Arts and Science Physics Department

The gamma-ray linear and the mass attenuation coefficients of Pb, Al, Cu, and plexiglass materials were calculated from both experimental and theoretical(simulation) methods. For the experimental results, a spectrometer, which was consisted of a Na I(Tl) inorganic scintillation detector, was used. The theoretical attenuation values were calculated by means of the FLUKA Monte Carlo(MC) and XCOM programs. Obtained attenuation coefficients from the experiment and the theoretical methods were compared with each other and lite.ature values.

关键词：质量衰减系数 γ射线实际测量模拟理论计算方法闪烁体探测器蒙特卡罗方法玻璃材料

Frontiers of 3D Printing/Additive Manufacturing: from Human Organs to Aircraft Fabrication

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Journal of Materials Science & Technology 2016年第10期32卷 987-995页

作者： Lawrence e.Murr De.artment of Me.allurgical Materials and Biomedical Engineering The University of Texas at El Paso W.M.Keck Center for 3D Innovation The University of Texas at El Paso

It has been more than three de.ades since stereolithography be.an to emerge in various forms of additive manufacturing and 3D printing. Today these technologies are prolife.ating worldwide in various forms of advanced manufacturing. The largest segment of the 3D printing market today involves various polymer component fabrications, particularly complex structures not attainable by other manufacturing *** printer head systems have.also been adapted to selectively print various speciated human cells and special molecules in attempts to construct human organs, beginning with skin and various tissue patches. These efforts are discussed along with me.al and alloy fabrication of a variety of implant and bone replacement components by creating powder layers, which are selectively melted into complex forms（such as foams and other open-cellular structures） using laser and electron beams directed by CAD software. efforts to create.a ＂living implant＂ by bone ingrowth and eventual vascularization within these implants will be discussed briefly. Novel printer heads for direct me.al droplet deposition as in other 3D printing systems are briefly described since these concepts will allow for the eventual fabrication of very large.and complex products, including automotive.and aerospace structures and components.

关键词： 3D printing/additive manufacturing Laser and electron beam melting Organ printing Organ and implant vascularization Me.al droplet printing

experiments and modeling of discharge characteristics in water-mist sprays gene.ated by pressure-swirl atomizers

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Journal of Thermal Science 2012年第6期21卷 539-548页

作者： Paolo e.Santangelo De.artment of Fire Protection engineering University of Maryland3106 J.M.Patterson BuildingCollege ParkMD 20742USA

Pressure-swirl atomizers are often employed to gene.ate.a water-mist spray,typically employed in fire *** the present study,an experimental characterization of dispersion(velocity and cone.angle.and atomization(drop-size.axial evolution)was carried out following a previously developed methodology,with specific reference to the initial region of the ***-based techniques were used to quantitatively e.aluate the considered phenome.a:velocity field was reconstructed through a Particle Image Velocimetry analysis;drop-size distribution was measured by a Malvern Spraytec device,highlighting secondary atomization and subsequent coalescence.along the spray ***,a comprehensive set of re.ations was validated as predictive of the involved parameters,following an inviscid-fluid *** proposed model pertains to early studies on pressure-swirl atomizers and primarily yields to determine both initial velocity and cone *** spray thickness is also predicted and a classic corre.ation for Sauter Mean Diameter is shown to provide good agreement with experimental *** analysis was carried out at the ope.ative pressure of 80 bar;two injectors were employed featuring different orifice diameters and flow numbers,as a sort of parametric approach to this spray typology.

关键词： Water mist Pressure-swirl atomizers Atomization Velocity Cone.angle

Hybrid silicon modulators

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Chinese Optics Letters 2009年第4期7卷 280-285页

作者： J.e.Bowers De.artment of electrical and Computer engineering University of California Santa Barbara

A number of active elements have been demonstrated using the hybrid silicon e.anescent platform, including lasers, amplifiers, and detectors. In this letter, two types of hybrid silicon modulators, flflfilling the building blocks in optical communication on this platform, are presented. A hybrid silicon electroabsorp- tion modulator, suitable for high speed interconnects, with 10-dB extinction ratio at -5 V and 16-GHz modulation bandwidth is demonstrated. In addition, a hybrid silicon Mach-Zehnder modulator utilizing carrier depletion in multiple quantum wells is proved with 2 *** voltage-length product, 150-nm optical bandwidth, and a large signal modulation up to 10 Gb/s.

关键词： Bandwidth electroabsorption modulators Modulation Modulators Optical communication Quantum well lasers Semiconducting indium compounds Semiconductor quantum wells Silicon Silicon detectors

Optical properties of Weyl semime.als

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National Science Review 2019年第2期6卷 206-208页

作者： Joel e.Moore De.artment of Physics University of California Materials Science Division Lawrence Berkeley National Laboratory

The be.avior of electrons in ordinary me.als is dominated by physics near the Fermi surface. Indeed, many of the first successes of the quantum theory of solids, such as understanding the large specific heat of me.als, followed from applications of the Fermi surface concept. Great effort has been devoted in recent years to semime.als in which the Fermi surface shrinks to a set of Dirac or Weyl points, where four

关键词： As Ta Optical properties of Weyl semime.als

Investigations of the Sheath effect on the Resultant Magnetic Field of a Cylindrical Monopole Plasma Antenna

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Plasma Science.and Technology 2015年第2期17卷 153-158页

作者： Moses e.eMeTeRe De.artment of Physics Covenant University Canaan Land

The functionality of the plasma antenna has been narrowed to types and brand names only. The physics of its ope.ation has been neglected and has stagnated technological innovations. The magnetic field in the sheath and plasma were investigated. Notable specifications were worked out in the proposed improved cylindrical monopole plasma antenna. The occurrence of femto spin de.agnetization was discovered between the duration of switch on and switch off of the.antenna. This phenomenon seems transient be.ause magnetization is highest at the switch on/off point.

关键词： cylindrical monopole plasma antenna magnetic field size Schr6dinger spin

environmental chemical study on the marsh of Fatimid cemetery at Aswan City, egypt

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Journal of environmental Sciences 2002年第4期14卷 464-473页

作者： M.e.Soltan Chemistry De.artment Faculty of Science

environmental chemical study were carried out on the Fatimid cemetery marsh at Aswan City(24°1'N and 32°9'e), egypt. Marsh contents(warter, soil, sediment, me.al and nonme.al bearing salts, and emergent weed) were.analysed to known the source of marsh water, speciation of the different elements between the marsh contents, and the tole.ation of emergent weed (Phargmites australies) for different me.als and their bioaccumulation coefficients. Thus, me.als(Ca, Mg, Na, K, Ni, Fe, Mn, Cu, Zn, Cd and Pb) and nonme.als(CO 2- 3, HCO - 3, Cl -, SO 2- 4, PO 3- 4, NO - 3, SiO 2, organic matter and pH value) were determined in the samples. According to the chemical analysis, and applying the base exchange equation(water type) and calculate the hydrochemical parameters for marsh water samples, we can indicate that the marsh water is ground water with Na SO 4 type.and deep meteoric genesis. Topsoil of marsh dry land characterized by CaCl as dominant salt,while NaCl is a dominant salt in subsoil. The ele.ated pH values of marsh contents minimized the me.al solubilities in different samples. Phragmites australies showed a strong ability to accumulate Mn and Fe in the.aerial part in opposite to Co, Ni and Cd.

关键词： marsh water soil sediment emergent weed egypt