Shape sensitivity analysis with design-dependent loadings—equivalence between continuum and discrete derivatives

The purpose of this paper is twofold: (1) showing equivalence between continuum and discrete formulations in sensitivity analysis when a linear velocity field is used and (2) presenting shape sensitivity formulations for design-dependent loadings. The equations for structural analysis are often composed of the stiffness part and the applied loading part. The shape sensitivity formulations for the stiffness part were well-developed in the literature, but not for the loading part, especially for body forces and surface tractions. The applied loads are often assumed to be conservative or design-independent. In shape design problems, however, the applied loads are often functions of design variables. In this paper, shape sensitivity formulations are presented when the body forces and surface tractions depend on shape design variables. Especially, the continuum–discrete (C–D) and discrete–discrete (D–D) approaches are compared in detail. It is shown that the two methods are theoretically and numerically equivalent when the same discretization, numerical integration, and linear design velocity fields are used. The accuracy of sensitivity calculation is demonstrated using a cantilevered beam under uniform pressure and an arch dam crown cantilever under gravity and hydrostatic loading at the upstream face of the structure. It is shown that the sensitivity results are consistent with finite difference results, but different from the analytical sensitivity due to discretization and approximation errors of numerical analysis.     

Loss of Nckx3 Exacerbates Experimental DSS-Induced Colitis in Mice through p53/NF-κB Pathway

Inflammatory bowel diseases (IBDs) comprises a range of chronic inflammatory conditions of the intestinal tract. The incidence and prevalence of IBDs are increasing worldwide, but the precise etiology of these diseases is not completely understood. Calcium signaling plays a regulatory role in cellular proliferation. Nckx3, a potassium-dependent Na⁺/Ca²⁺ exchanger, is not only expressed in the brain but also in the aortic, uterine, and intestinal tissues, which contain abundant smooth muscle cells. This study investigated the role of Nckx3 in intestinal inflammation. Microarray analyses revealed the upregulation of the innate immune response-associated genes in the duodenum of Nckx3 knockout (KO) mice. The Nckx3 KO mice also showed an increase in IBD- and tumorigenesis-related genes. Using dextran sodium sulfate (DSS)-induced experimental colitis mice models, the Nckx3 KO mice showed severe colitis. Furthermore, the pathways involving p53 and NF-κB signaling were significantly upregulated by the absence of Nckx3. Overall, Nckx3 plays a critical role in the innate immune and immune response and may be central to the pathogenesis of IBD.     

Estimation of Mass Transport Parameters of Organic Compounds through High Density Polyethylene Geomembranes Using a Modifield Double-Compartment Apparatus

A modified double-compartment apparatus (MDCA) is used to estimate mass transport parameters of organic compounds through high density polyethylene (HDPE) geomembranes and to investigate the effects of aging and external tension of HDPE geomembranes on the mass transport of organic compounds. A developed one-dimensional partition–diffusion mass transport model successfully explains the mass transport of the organic compounds through the HDPE geomembranes in a dilute aqueous solution–geomembrane system. Similar to batch immersion tests, the HDPE–water partition coefficient (KHDPE–W) values of organic compounds are found to have close relationships with the octanol–water partition coefficient and the aqueous solubility; furthermore, the diffusion coefficient (D) values decrease with the increase of their molecular diameter. For HDPE geomembranes served in the landfill liner for 5 years and stretched by 8% of their initial length, KHDPE–W values for organic compounds increase by 5–58%, D values for organic compounds increase by 10–86%, and breakthrough times are faster, indicating more amounts of organic compounds may break through the HDPE geomembrane in fields than expected. The mass transport parameters from MDCA tests could be used with those from batch immersion tests interchangeably after mass loss and immobilization of organic compounds in MDCA tests are considered.     

Synthesis of nano-sized spherical barium-strontium ferrite particles

Magnetic recording media requires good particle dispersion, a smooth surface, and small interparticle interaction to make an adequate signal-to-noise ratio (SNR). Well dispersed 50-60 nm sized spherical barium-strontium ferrite (S-Ba/Sr-Fe) nanoparticles were successfully prepared with 40 nm sized hematite precursor particles and BaCO/sub 3//SrCO/sub 3/ colloid. The coercivity and saturation magnetizations of S-Ba/Sr-Fe nano-particles were 1568 Oe and 48.6 emu/g, respectively. In order to evaluate magnetic interaction, magnetic tape was prepared using an Eiger mill with binder and organic solvent. /spl Delta/M measurement showed the S-Ba/Sr-Fe nanoparticles in the tape had negative magnetic particle-to-particle interaction.     

Synthesis of Resonator Filters With Arbitrary Topology Using Hybrid Method

This paper presents a new synthesis method for resonator filters of arbitrary topology using an evolutionary hybrid method. This method consists of a Levenberg-Marquardt algorithm for a local optimizer and genetic algorithm for a global optimizer, respectively. Unlike the conventional hybrid method in which the local optimization is performed after finding appropriate initial values from global optimization, the local optimizer in the proposed method is used as a genetic-algorithm operator to prevent trapping in local minima of the cost function. This method can provide fast convergence and good accuracy to find the final solution from initial population generated by a random number and the known value for the filters with stringent requirements. In addition, multiple coupling matrices to meet the given requirement can be obtained from the initial population based on a random number. Resonator filters with asymmetric eight-pole configurations for single and dual passbands are synthesized using the current method for validation. Excellent agreement between the response computed from characteristic polynomials and the response computed from couplings is obtained from the proposed method.     

The Doherty Power Amplifier With On-Chip Dynamic Bias Control Circuit for Handset Application

A monolithic-microwave integrated-circuit Doherty power amplifier (PA) with an on-chip dynamic bias control circuit for cellular handset application has been designed and implemented. To improve the linearity and efficiency in the operation power ranges, the base and collector biases of the amplifiers, except the drive amplifier of the main path, are controlled according to the average output power. The base biases are controlled using the on-chip circuit and collector biases by the dc/dc chip to reduce the average dc consumption power. The power-added efficiency (PAE) is improved approximately 6% by the base dynamic bias control, and approximately 14% by the collector/base dynamic control from the class AB at Pout=16 dBm, respectively. If the dc/dc converter efficiency is 100%, the PAE could be improved approximately 17.5% from class AB, reaching to 29.2% at Pout=16 dBm. In the intermediate power level from 22 to 28 dBm, the PAE is over 34.3%. The average current consumption of the PA with the dynamic bias control is 22.5 mA in urban and 37.3 mA in suburban code-division multiple-access environments, which are reduced by 36%-46.7%, compared to the normal operation. The adjacent channel power ratio is below 47.5 dBc, and the PAE at the maximum power is approximately 43.3% in the dynamic bias operations     

Highly linear and low noise 2.4 GHz RF front-end circuits using transformer and vertical NPN BJT

The proposed RF front-end circuits consist of a low noise amplifier using an on-chip transformer and a downconversion mixer using a parasitic vertical bipolar junction transistor and have been implemented in 0.18 mum deep n-well CMOS process. A gain of 33 dB, an IIP3 of -12 dBm, and a DSB noise figure of 4.5 dB have been achieved while consuming 5 mW from a 1.8 V supply     

Thermal Investigation of GaN-Based Laser Diode Package

We investigated thermal behavior of GaN-based laser diode (LD) packages as a function of cooling systems, die attaching materials, chip loading conditions, and optical performances. The electrical thermal transient technique was employed for the thermal measurement of junction temperature and thermal resistance of LD packages. The results demonstrate that the total thermal resistance of LD packages is controlled mainly by the packaging design rather than the chip structure itself. Significant changes in thermal resistance with input current were observed under a natural cooling system because of the sensitive change in the heat transfer coefficient with the change in temperature. Employment of PbSn as a die attachment was more advantageous over the Ag-paste in the thermal behavior of LD packages. The LD package with epi-down structure resulted in the lower thermal resistance compared to one with epi-up structure. A continuous increase in junction temperature was measured after lasing. It was attributed to an increase in the thermal resistance of LD when it took the optical power into an account. Effective input power was decreased by the lasing and led to high thermal resistance values.     

Photonic Technologies for Quantum Information Processing

The last several years have seen tremendous progress toward practical optical quantum information processing, including the development of single- and entangled-photon sources and high-efficiency photon counting detectors, covering a range of wavelengths. We review some of the recent progress in the development of these photonic technologies. PACS: 03.67.-a, 42.50.Dv, 42.65.Lm, 78.67.Hc, 85.60.Gz     

Acoustic monitoring of HV equipment with optical fiber sensors

This paper presents the preliminary results on the application of optical fiber sensor (OFS) for the measurements of discharging signals in insulating oil. An all-optical-fiber-sensing system using a Mach-Zehnder interferometry technique was constructed. It was found that the pressure wave produced by discharges at the needle-sphere electrodes could be detected by OFS, which was compared with signals from a current probe and PZT sensor. By comparing amplitudes of acoustic signal measured by OFS, a correlation between acoustic and electrical discharge signals was observed.