Calculation of the stress intensity factor for arbitrary finite cracked body by using the boundary weight function method

The state of thermal stresses for a periodic two-layered elastic space weakened by an interface thermally insulated Griffith crack and loaded by concentrated line heat sources is investigated. The analysis is performed within the framework of the homogenized model with microlocal parameters. The stress intensity factors at the crack tips are determined. Two examples of the application of the results obtained are detailed.     

GaAs-GaAlAs heterostructure single-mode channel-waveguide cutoff modulator and modulator array

A GaAs single-mode channel-waveguide cutoff modulator that utilizes a GaAs-GaAlAs heterostructure and a linear array of such modulators are reported for the first time. We have measured a cutoff voltage as low as 9.0 V and an extinction ratio greater than 20 dB at an optical wavelength of 1.3 μm in a basic modulator that utilized a GaAs-Ga0.93Al0.07As heterostructure with a 0.9 μm thick GaAs epitaxial layer together with a ridge channel 2.5 mm in length and 5.0 μm in width. We have also succeeded in the realization of a high packing density (500 channels/cm) linear array of such cutoff modulators in the same GaAs substrate with equally satisfactory results. An RF bandwidth of 2.5 GHz has also been measured with the elementary modulator of such array. As in the case for LiNbO3substrates, the GaAs-based integrated optic modules that result from integration of such cutoff modulator arrays, microlens arrays, and planar acoustooptic or electrooptic Bragg diffraction grating arrays in a common substrate may be used to perform multiport switching, computing, and RF signal processing.     

A new process of fabricating inverted-staggered tri-layer thin-filmtransistors

A new method of fabricating a-Si:H TFT with etching-stop structure has been proposed. Only one plasma-enhanced chemical vapor deposition is required in this new method and a PH₃/H₂ plasma treatment during the deposition has been used to form the TFT contact and thus saved another plasma deposition. With this method, a TFT of 500 Å active layer has been fabricated successfully. The drain current and saturation mobility of this device is 2.4×10^-7 A and 0.1 cm²/V sec, respectively, which is comparable to the conventional fabricating method. The plasma treatment will also form an additional leakage path on the TFT top surface and increase the TFT subthreshold slope. However, a current of less than 1 pA at V_G=-2.4 V can still be obtained. The possible mechanism of the contact formation by the plasma treatment is also discussed     

Advances in software engineering

Software is the key technology in applications as diverse as accounting, hospital management, aviation, and nuclear power. Application advances in different domains such as these-each with different requirements-have propelled software development from small batch programs to large, real-time programs with multimedia capabilities. To cope, software's enabling technologies have undergone tremendous improvement in hardware, communications, operating systems, compilers, databases, programming languages, and user interfaces, among others. In turn, those improvements have fueled even more advanced applications. Improvements in VLSI technology and multimedia, for example, have resulted in faster, more compact computers that significantly widened the range of software applications. Database and user interface enhancements, on the other hand, have spawned more interactive and collaborative development environments. Such changes have a ripple effect on software development processes as well as on software techniques and tools. In this article, we highlight software development's crucial methods and techniques of the past 30 years     

Field theoretical treatment of H-plane waveguide junctionswith anisotropic medium

A method based on the equivalence principle and cavity field expansions is used to analyze an H-plane waveguide junction containing an anisotropic (ferrite or composite ferrite) post. Using the equivalence principle, magnetic surface currents are introduced at the imaginary boundaries chosen between the central region of the junction and the waveguides. The electric displacement in the junction can be completely expressed in terms of a solenoidal set. On the other hand, the magnetic induction in the junction must be expressed in terms of a solenoidal set and an irrotational set. Continuing the tangential magnetic field at the imaginary boundaries leads to a matrix equation, the unknowns of which are the amplitudes of the scattered waveguide modes. Using this method, H-plane waveguide junctions with ferrite and composite ferrite posts are considered. The numerical results show excellent agreement with previously published experimental and theoretical results     

Service-oriented smart home applications: composition, code generation, deployment, and execution

A smart home usually has a variety of devices or home appliance, instead of designing software for a specific home, this paper proposes a service-oriented framework with a set of ontology systems to support service and device publishing, discovery of devices and their services, composition of control software using existing control services that wrap devices, deployment, and execution of the composed service in an computing environment, monitoring the execution, and recovery from device failure. The ontology systems specify semantic information about devices, services, and workflows used in various smart home, and users can compose and recompose services for their specific needs. New devices, workflows, and services can be added into ontology. Most of the steps in this process can be automated including code generation. For example, service composition will be carried out in three steps: abstract workflow design, function construction, and device discovery, and different codes can be generated for different computing platforms such as Java and Open Services Gateway initiative environments. In this way, a variety of smart home can be constructed rapidly using the framework by discovery and composition using existing services and workflows. This paper illustrates this framework using a media control example to illustrate the ontology, discovery, composition, deployment, execution, monitoring, and recovery.     

An SVD-based image watermarking in wavelet domain using SVR and PSO

The paper presents a novel blind watermarking scheme for image copyright protection, which is developed in the discrete wavelet transform (DWT) and is based on the singular value decomposition (SVD) and the support vector regression (SVR). Its embedding algorithm hides a watermark bit in the low–low (LL) subband of a target non-overlap block of the host image by modifying a coefficient of U component on SVD version of the block. A blind watermark-extraction is designed using a trained SVR to estimate original coefficients. Subsequently, the watermark bit can be computed using the watermarked coefficient and its corresponding estimate coefficient. Additionally, the particle swarm optimization (PSO) is further utilized to optimize the proposed scheme. Experimental results show the proposed scheme possesses significant improvements in both transparency and robustness, and is superior to existing methods under consideration here.     

Preparation and thermotropic properties of copoly(4,4′-biphenylene sebacate-co-eicosanedioate)s

Summary A series of thermotropic copoly(4,4-biphenylene sebacate-co-eicosanedioate)s were prepared by melt polycondensation of 4,4-biphenylene diacetate, sebacic acid and eicosanedioic acid. Their thermal transitions and liquid crystalline properties were investigated by DSC and polarized micrrocope. The copolyesters were found to exhibit a smectic phase, but no nematic phase was observed upon cooling. The smectic-isotropic transition temperature decreased as the content of eicosanedioate unit increased, and the corresponding transition heat did not change to a great extent. However, the crystalline-smectic transition temperature showed an eutectic behavior, and the crystalline-smectic transition heat was depressed considerably after copolymerization. The X-ray diffraction data of the copolyesters after thermal treatment were measured and compared with the thermal properties measured by DSC.     

Nonlinear response of electron-phonon interaction inn-type nondegenerate piezoelectric semiconductors

The nonlinear response of the electron-phonon interaction in nondegenerate piezoelectric semiconductors such asn-type InSb in the presence of a dc magnetic fieldB directed along the propagation of acoustic waves has been studied by using a quantum mechanical treatment. The effect of electron scattering in solids has been taken into consideration, so the electron relaxation time cannot be neglected. The nonlinear nature of the energy band is corrected for, using the Heisenberg equation of motion. It is found that the nonlinear response is proportional to a nonlinear longitudinal conductivity tensor _zzz when acoustic waves propagate parallel to the [111] direction for both piezoelectric and deformation-potential couplings. Numerical calculations for _zzz of n-type InSb at low temperatures are presented. Results show that the nonlinear response decreases rapidly with the sound frequency, and decreases slowly with the dc magnetic field and temperature. Therefore, the electron relaxation time and the nonparabolicity of energy bands play important roles for the electron-phonon interaction due to the piezoelectric and deformation-potential couplings in the microwave region.     

Epigallocatechin-3-Gallate-Loaded Liposomes Favor Anti-Inflammation of Microglia Cells and Promote Neuroprotection

Microglia-mediated neuroinflammation is recognized to mainly contribute to the progression of neurodegenerative diseases. Epigallocatechin-3-gallate (EGCG), known as a natural antioxidant in green tea, can inhibit microglia-mediated inflammation and protect neurons but has disadvantages such as high instability and low bioavailability. We developed an EGCG liposomal formulation to improve its bioavailability and evaluated the neuroprotective activity in in vitro and in vivo neuroinflammation models. EGCG-loaded liposomes have been prepared from phosphatidylcholine (PC) or phosphatidylserine (PS) coated with or without vitamin E (VE) by hydration and membrane extrusion method. The anti-inflammatory effect has been evaluated against lipopolysaccharide (LPS)-induced BV-2 microglial cells activation and the inflammation in the substantia nigra of Sprague Dawley rats. In the cellular inflammation model, murine BV-2 microglial cells changed their morphology from normal spheroid to activated spindle shape after 24 h of induction of LPS. In the in vitro free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, EGCG scavenged 80% of DPPH within 3 min. EGCG-loaded liposomes could be phagocytized by BV-2 cells after 1 h of cell culture from cell uptake experiments. EGCG-loaded liposomes improved the production of BV-2 microglia-derived nitric oxide and TNF-α following LPS. In the in vivo Parkinsonian syndrome rat model, simultaneous intra-nigral injection of EGCG-loaded liposomes attenuated LPS-induced pro-inflammatory cytokines and restored motor impairment. We demonstrated that EGCG-loaded liposomes exert a neuroprotective effect by modulating microglia activation. EGCG extracted from green tea and loaded liposomes could be a valuable candidate for disease-modifying therapy for Parkinson’s disease (PD).