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T he thermal performance of Liquid-cooled plate (LCP) can be improved by using different kinds of materials and coolants. Suitable and effective coolant can bring better cooling capacity to cope with the impact of high temperature on IGBT chips, and improve the safety and service life of new energy metallurgical loaders. In this context, the recent progress of the effects of traditional coolants, nano-fluids, ethylene glycol and oil on the heat transfer capacity of the liquid cooling plate is reviewed in detail. Nanofluids have been identified as the most prominent cooling method at present because of their good thermal conductivity. In addition, the considerations and advantages and disadvantages of using different coolants are discussed in depth. [ABSTRACT FROM AUTHOR]

Polyamines play an important role in stress response. In the pathway of polyamines synthesis, S-adenosylmethionine decarboxylase (SAMDC) is one of the key enzymes. In this study, a full length cDNA of SAMDC (AhSAMDC) was isolated from peanut (Arachis hypogaea L.). Phylogenetic analysis revealed high sequence similarity between AhSAMDC and SAMDC from other plants.In peanut seedlings exposed to sodium chloride (NaCl), the transcript level of AhSAMDC in roots was the highest at 24 h that decreased sharply at 72 and 96 h after 150 mM NaCl treatment. However, the expression of AhSAMDC in peanut leaves was significantly inhibited, and the transcript levels in leaves were not different compared with controlThese results implied the tissue‐specific and time-specific expression of AhSAMDC. The physiological effects and functional mechanism of AhSAMDC were further evaluated by overexpressing AhSAMDC in tobaccos. The transgenic tobacco lines exhibited higher germination rate and longer root length under salt stress. Reduced membrane damage, higher antioxidant enzyme activity, and higher proline content were also observed in the transgenic tobacco seedlings. What's more, AhSAMDC also led to higher contents of spermidine and spermine, which can help to scavenge reactive oxygen species.Together, this study suggests that AhSAMDC enhances plant resistance to salt stress by improving polyamine content and alleviating membrane damage [ABSTRACT FROM AUTHOR]

Background and purpose: Accumulated failures in Alzheimer's disease (AD) clinical trials have highlighted an urgent need to identify additional biomarkers involved in AD. Recently, mounting evidence reported that autoantibodies are ubiquitous in human sera. However, it is unknown whether autoantibodies are upregulated in amyloid‐tau biomarker‐confirmed AD. Methods: A total of 40 subjects with mild dementia (Clinical Dementia Rating = 1) were stratified into AD (n = 16) and non‐AD (n = 24) groups according to their cerebrospinal fluid levels of tau and Aβ42. Their sera were collected and analyzed using a microarray containing > 1600 potential human autoantigens. Autoantibodies that were present exclusively in the AD group were identified and selected using the penetrance‐based fold change method with the following criteria: penetrance fold change(AD) ≥ 2, frequency(AD) ≥ 15% and frequency(non‐AD) = 0%. Results: All controls and samples passed the quality control criteria and were further used for biomarker analysis. Six autoantibodies with elevated responses to the following autoantigens were found exclusively in the AD group: nucleosome assembly protein 1‐like 3 (31.3%, 5/16 subjects) and microtubule‐associated protein 4, pantothenic acid kinase 3, phosphoinositide‐3‐kinase regulatory subunit 1, protein tyrosine phosphatase type IVA member 1 and SRY (sex‐determining region Y)‐box 15 (all 18.8%, 3/16 subjects). Conclusions: Although some identified autoantigens are linked to AD and cognitive dysfunction, the increased autoantibody levels have not been reported in AD. Autoantibodies may provide deeper insights into the pathogenesis of AD and serve as diagnostic biomarkers; their corresponding antigens can be further studied to assess their potential as therapeutic targets. [ABSTRACT FROM AUTHOR]

The hot compression test was conducted in Gleeble-1 500D to study the hot flow stress behavior of AA6 111 aluminum alloy belonging to Al-Mg-Si series, at the deformation temperatures ranging from 350 to 500 °C and strain rates ranging from 0,01 s-1 to 1 s-1. And how the flow stress change with variation of strain, temperature and strain rate was investigated. The results show that flow stress increases with decreasing temperature and increasing strain rate; the AA6 111 is positive stain rate sensitive material; the main softening mechanism is dynamic recovery. Furthermore, constitutive equation considering the effect of strain was obtained based on Arrhenius equation. The predicted flow stress values well agree with the experimental results with some little aberration. The coefficient of association can be as high as 0,9 954, which shows high reference value for industry and simulation analysis. [ABSTRACT FROM AUTHOR]

A Ka combined horn antenna with low cross-polarization is presented in this paper. The antenna consists of an edge-slotted waveguide linear array, a metallic-grid plane in the horn throat and a horn. The effects of metallic-grid and single-ridged waveguide to the cross-polarization are analyzed. Three kinds of 62-element Taylor linear array at Ka band are fabricated and measured and the measured cross-polarization level is less than -35dB in operating bandwidth. The proposed antennas are benefit for fabrication and fixation with low cross-polarization and can be extensively used in radar and communication systems. [ABSTRACT FROM AUTHOR]

A new type of rat-race coupler, based on electromagnetic bandgap (EBG)-loaded half-mode substrate integrated waveguide (HMSIW) and composite right/left-handed (CRLH) HMSIW, has been proposed and investigated comprehensively. It consists of three sections of EBG-loaded HMSIWs with 90° phase delay and one section of CRLH HMSIW with −90° phase advance. Due to the evanescent-mode of EBG-loaded HMSIW and the backward behavior of the CRLH HMSIW in the left-handed region, the size of such a miniaturized rat-race coupler is reduced about 65.7% in comparison with its conventional counterpart. The rat-race coupler with the central frequency of 5.5 GHz has been designed and fabricated so as to validate our method, and its good performance is demonstrated by both simulated and measured results. [ABSTRACT FROM AUTHOR]

One-directional weakly conditionally stable finite-difference time-domain (WCS-FDTD) method is extended to solve electromagnetic problems in linear dispersive media by virtue of piecewise linear recursive convolution (PLRC) technique. This proposed method provides similar accuracy to PLRC alternating direction implicit (ADI) FDTD approach, yet consumes less computational time and less memory. This proposed method is particularly suitable for solving problems in linear dispersive materials with fine features along two spatial directions. [ABSTRACT FROM PUBLISHER]

The authors present a novel compact wideband pattern-reconfigurable antenna with alternate reflector and radiator. The proposed antenna consists of a pair of step-shape patches, four switches and a coplanar waveguide feeding line. By setting the switches ON or OFF, the two step-shape patches can alternately switch between the radiator and the reflector. As a result, the proposed antenna is able to provide two-directional radiation patterns whose main beams are roughly directed in opposing directions from 3.7 to 6 GHz. Compared with other current pattern-reconfigurable antennas, the proposed antenna exhibits advantages of better back-to-front radiation ratio, more compact antenna size and wider operating band. In this investigation, the optimised size of the proposed antenna is 20 × 20 mm², which equates to 0.25 × 0.25λ²0 (λ0 is the wavelength at the low edge of the operating frequency band). In addition, the time-domain characteristics of the proposed antenna are presented and analysed. The antenna shows a good time-domain performance. Measured results are presented. [ABSTRACT FROM AUTHOR]

PIN diodes are used to electronically switch a rectangular microstrip antenna between the optimal radiation state and the low radar cross section (RCS) state in this paper. A useful loading circuit is proposed. The circuit is connected between the patch and the ground plane of the antenna at each loading position. The loading positions of the circuit are determined by studying magnitude distributions of the induced electricfield and analyzing statistically how many times that the maximum electricfield occurs in each area for each discussed incident angle. PIN diodes are equivalent to capacitances and resistances when diodes are reverse-biased and forward-biased, respectively. When the antenna is not in service and excited by an incident plane wave, obvious RCS reduction is realized. In addition, the radiation performances are well maintained when the antenna is in service for transmitting or receiving signals. [ABSTRACT FROM AUTHOR]

In this paper, the application of reflected group delay in the design of the output antenna for a 5.8 GHz magnetron is presented. For a radial direction output magnetron, the external quality factor (Qe) is mainly determined by the output antenna. In order to facilitate the output antenna design, we firstly calculate the cold cavity spectrum and the electric field distribution in the anode cavity by simulation. Then the relation between reflected group delay and external quality factor has been derived through equivalent circuit of the magnetron. Moreover, the required reflected group delay is obtained according to the derivation. And the optimum position of output antenna connecting with vane is determined. The sample magnetron has 49.2% output efficiency in hot cavity test [ABSTRACT FROM AUTHOR]

A defected ground structure (DGS) is used to suppress mutual coupling between elements in a microstrip array and eliminate the scan blindness in an infinite phased array. Two kinds of DGSs, namely back-to-back U-shaped and dumbbell-shaped DGSs, are analysed and compared. The analysis indicates that the back-to-back U-shaped DGS is better at suppressing propagation of surface waves in microstrip substrate. A two-element microstrip array with back-to-back U-shaped DGS is designed and the array characteristics against different element distances are studied. The results show that the degree of the mutual coupling suppression is increased when the element distance is reduced. However, compared with the traditional array, a higher gain and lower side lobes are obtained when a larger element spacing is selected. The scan blindness of an infinite microstrip phased array in E-plane is studied by simulation, and the calculation demonstrates that the scan blindness can be eliminated by applying a back-to-back U-shaped DGS to the infinite phased array. [ABSTRACT FROM AUTHOR]

A modified three-step three-dimensional (3-D) locally 1-D finite-difference time-domain (LOD-FDTD) method with reduction of numerical dispersion is introduced by virtue of parameter optimisation. Both theoretical and numerical studies of the unconditional stability of this proposed method are also presented. The numerical dispersion behaviour is investigated by comparison with the original LOD-FDTD method. The reduction of numerical dispersion error and the improved numerical accuracy can be observed from the numerical phase velocity computations under various time steps, spatial resolutions and frequencies. Numerical examples are included to illustrate the validity and improved accuracy of this proposed method. [ABSTRACT FROM AUTHOR]

The TM 0 surface mode in an infinitely long parallel-plate waveguide filled with a double-positive (DPS) and epsilon-negative (ENG) metamaterial bi-layer is studied. With proper constitutive parameters and thicknesses of the two layers, the slow-wave factor (SWF) for such a parallel-plate waveguide can tend to infinity as the frequency decreases. A 2-D cavity based on the DPS-ENG bi- layer waveguide is constructed and studied to evaluate the radiation ability of its corresponding patch antenna. Based on the cavity model analysis of patch antennas, we show that good efficiency for broadside radiation of such a cavity-based rectangular patch antenna can be achieved when one layer of the cavity is shielded (or partially shielded) by PEC boundaries. Taking practical loss and dispersion into consideration, a miniaturized cavity-based rectangular patch antenna is proposed as an example. With the super-slow TM 0 surface mode excited in the bi-layer by a simple coaxial line feeding, the antenna has a dimension of only 0.107γ0 0 x 0.129γ0 x 0.045γ0. The patch antenna produces broadside radiation, and fairly good radiation efficiency is achieved. The PEC-Partially-Shielded-ENG-Cavity based rectangular patch antenna with a further miniaturization but reduced radiation efficiency is also discussed. [ABSTRACT FROM AUTHOR]

This paper applies a meshless method based on radial basis function (RBF) collocation to solve three-dimensional scalar Helmholtz equation in rectangular coordinates and analyze the eigenvalues of spherical resonant cavity. The boundary conditions of spherical cavity are deduced. The RBF interpolation method and the collocation procedure are applied to the Helmholtz and boundary condition equations, and their discretization matrix formulations are obtained. The eigenvalues of spherical resonant cavity with natural conformal node distribution are computed by the proposed method. Their results are agreement with the analytic solution. [ABSTRACT FROM AUTHOR]

In this paper, a body-worn planar monopole antenna is proposed for body-centric wireless communications systems (BWCS) working at the frequency around 2.45 GHz. The effect of human body in the near vicinity of the antenna on the antenna performance is also investigated. Based on the body-worn monopole antenna, a simple body-worn MIMO system is developed to improve the capacity of BWCS. The effect of mutual coupling between elements on capacity is also considered. The studies show that the capacity of data transmission is improved when MIMO system is adopted. [ABSTRACT FROM AUTHOR]

In this work we investigate three different artificial ground planes for microstrip antenna design, which are useful for different applications. The three different ground plane configurations studied include: (i) conventional dielectric substrate backed by a perfect conductor; (ii) a loop type of artificial magnetic conductor (AMC); and a spiral-type of AMC. Both the loop and spiral types of AMCs tend to lower the resonant frequency of the microstrip patch antenna (MPA), as compared to that of the dielectric substrate, for the linearly polarized case. However, the spiral AMC can be used to realize circular polarization as well, at a different frequency band, hence, is useful for designing dual-band dual-polarization microstrip antennas. [ABSTRACT FROM AUTHOR]

A novel design of epsilon-negative (ENG) material which can exhibit negative permittivity at two nearby bands is presented in this paper. With the unit shape as an unsealed rectangle frame, the components of this ENG material are two folded wires with different dimensions. Each folded-wire structure can achieve electric resonance at a certain frequency band by appropriately adjusting its dimensions. Its electromagnetic properties are then retrieved to demonstrate that the dual-band electric resonances can be obtained in our sample. With the aid of numerical simulation, the transmission property of the proposed dual-band epsilon-negative material is further investigated. And the result shows that the stop band for each folded wire (permittivity ε < 0) is easily adjusted by changing the designing parameters, without influence on the other nearby resonance frequency. It provides an advancement of dual-band and low mutual coupling resonances design. It is also promising that our approach will be effective to make this kind of dual-band ENG material applied into the areas of reconfigurable antennas and their arrays. [ABSTRACT FROM AUTHOR]

This paper proposes the conception of envelope time reversal (TR). Using different frequencies for signal modulation and demodulation, we give the theoretic derivation of one novel frequencydifference method, which demonstrates excellent TR focusing characteristic for envelope signal. In the following experiment, we carry out envelope TR on 100 MHz, 300 MHz and 500 MHz baseband signals separately. Being consistent with theoretic derivation, the experiment result verifies the feasibility of envelope TR. [ABSTRACT FROM AUTHOR]

Interfacial and electrical properties of atomic-layer-deposited HfO2 gate dielectric on epitaxial GaAs (epi-GaAs)/Ge and bulk GaAs substrates have been investigated. Atomic layer deposition provides a unique opportunity to integrate high quality gate dielectrics on epi-GaAs. The cross-sectional transmission electron microscopy of a HfO2/III-V gate stack shows a similar interfacial layer thickness for HfO2 on bulk p-GaAs and epi-GaAs substrates. However, X-ray photoelectron spectroscopy shows a Ga oxide-rich interfacial layer after postdeposition annealing at 500°C for films grown on epi-GaAs. Although the epi-GaAs surface is rough with nanoscale features, the electrical properties of the HfO2 gate dielectric deposited on epi-GaAs are comparable with bulk p-GaAs-based devices. The Au/HfO2/epi-GaAs gate stack shows a low frequency dispersion (13%), hysteresis voltage (0.72 V), and a leakage current density of 2.1 X 10-3 A cm-2 at VFB + 1 V (where FB is flatband) for an equivalent oxide thickness of 1.4 nm. [ABSTRACT FROM AUTHOR]

Some new and simple correlations have been introduced to predict impact sensitivities of various nitro energetic compounds. The correlations are based on the atomic numbers of C, H, N, O, and other amending factors, which are determined by the effect of the connective positions of groups to impact sensitivity. The predicted impact sensitivities for 196 energetic compounds are compared with the latest empirical computations presented by Keshavarz. Root mean square (rms) of deviation from experimental data is 37 cm, which is lower than that obtained from Keshavarz's computation (44 cm) [25,26]. [ABSTRACT FROM AUTHOR]

A compact H-shaped defected ground structure (DGS) is applied to reduce the mutual coupling between array elements and eliminate the scan blindness in a microstrip phased array design. The proposed DGS is inserted between the adjacent E-plane coupled elements in the array to suppress the pronounced surface waves. A two-element array is measured and the results show that a reduction in mutual coupling of 12 dB is obtained between elements at the operation frequency of the array. The scan properties of microstrip phased arrays with and without DGS are studied by the waveguide simulator method. The analysis indicates that the scan blindness of the microstrip phased array can be well eliminated because of the effect of the proposed DGS. Meanwhile, the active patterns of the array centre element in 7×3 element arrays with and without the H-shaped DGS are simulated, and the results agree with those obtained by the waveguide simulator method. [ABSTRACT FROM AUTHOR]

A technique is developed for the far field pattern analysis of reflectarrays, which is called 'element-in-array pattern' analysis technique. The technique rigorously takes the effects of mutual coupling between elements and the surrounding array environment into account by extracting the scattered fields of the element aperture in a realistic array configuration. Numerical results validate its accuracy and effectiveness. [ABSTRACT FROM AUTHOR]