A high figure of merit localized surface plasmon sensor based on a gold nanograting on the top of a gold planar film

We investigate the sensitivity and figure of merit （FOM） of a localized surface plasmon （LSP） sensor with gold nanograting on the top of planar metallic film. The sensitivity of the localized surface plasmon sensor is 317 nm/RIU, and the FOM is predicted to be above 8, which is very high for a localized surface plasmon sensor. By employing the rigorous coupled-wave analysis （RCWA） method, we analyze the distribution of the magnetic field and find that the sensing property of our proposed system is attributed to the interactions between the localized surface plasmon around the gold nanostrips and the surface plasmon polarition on the surface of the gold planar metallic film. These findings are important for developing high FOM localized surface plasmon sensors.

Figure of Merit Analysis of a Hybrid Solar-geothermal Power Plant

Figure of merit analysis is a general methodology used to evaluate whether a hybrid power plant could produce more power than two stand-alone power plants. In this paper, the assessment methodology using figure of merit analysis was re-examined for a hybrid solar-geothermal power plant. A new definition of the figure of merit was introduced specifically for a solar boosted geothermal plant to include both the technical and economic factors. The new definition was then applied in a case study of a hypothetical demonstration hybrid solar-geothermal power plant in Australia. The power plant was considered to have a typical net power output of 2.2 MW with a solar energy fraction of 27%. The analysis was performed to compare the power output and capital cost of the hybrid plant with the state-of-the-art (SoA) and existing stand-alone solar and geothermal plants. Based on the new definition, the hybrid plant was found to generally outperform the two existing stand-alone plants. Moreover, at an ambient temperature of 5 °C, the hybrid plant was found to outperform the SoA stand-alone plants when the geothermal temperature was greater than 150 °C. For geothermal temperature of 180 °C on the other hand, the hybrid plant outperformed the SoA stand-alone plants at ambient temperatures lower than 33 °C.

Investigating the Potential of Quasi-One-Dimensional Organic Crystals of TTT(TCNQ)2 for Thermoelectric Applications

The purpose of this paper is to present the results of investigations on quasi-one-dimensional organic crystals of tetrathiotetracene-tetracyanoquinodi- methane (TTT(TCNQ)2) from the prospective of thermoelectric applications. The calculations were performed after analytical expressions, obtained in the frame of a physical model, more detailed than the model presented earlier by authors. The main Hamiltonian of the model includes the electronic and phonon part, electron-phonon interactions and the impurity scattering term. In order to estimate the electric charge transport between the molecular chains, the physical model was upgraded to the so-called three-dimen- sional (3D) physical model. Numeric computations were performed to determine the electrical conductivity, Seebeck coefficient, thermal conductivity, thermoelectric power factor and thermoelectric figure-of-merit as a function on charge carrier concentrations, temperatures and impurity concentrations. A detailed analysis of charge-lattice interaction, consisting of the exploration of the Peierls structural transition in TCNQ molecular chains of TTT(TCNQ)2 was performed. As result, the critical transition temperature was determined. The dispersion of renormalized phonons was examined in detail.

High Thermoelectric Figure of Merit of Ag8SnS6 Component Prepared by Electrodeposition Technique

A new thermoelectric material Ag8SnS6, with ultra-low thermal conductivity in thin film shape, is prepared on indium tin oxide coated g/ass （ITO） substrates using a chemical process via the electrodeposition technique. The structural, thermal and electrical properties are studied and presented in detail, which demonstrate that the material is of semiconductor type, orthorhombic structure, with a band gap in the order of 1.56eV and a free carrier concentration of 1.46 × 10^17 cm-3. The thermal conductivity, thermal diffusivity, thermal conduction mode, Seebeck coefficient and electrical conductivity are determined using the photo-thermal deflection technique combined with the Boltzmann transport theory and Cahill＇s model, showing that the AgsSnS6 material has a low thermal conductivity of 3.8 Wm - 1K- 1, high electrical conductivity of 2.4 × 10^5 Sm- 1, Seebeck coefficient of -180μVK-1 and a power factor of 6.9mWK-2m-1, implying that it is more efficient than those obtained in recently experimental investigations for thermoelectric devices.

Design of multilayer cellular neural network based on memristor crossbar and its application to edge detection

Memristor with memory properties can be applied to connection points(synapses)between cells in a cellular neural network(CNN).This paper highlights memristor crossbar-based multilayer CNN(MCM-CNN)and its application to edge detection.An MCM-CNN is designed by adopting a memristor crossbar composed of a pair of memristors.MCM-CNN based on the memristor crossbar with changeable weight is suitable for edge detection of a binary image and a color image considering its characteristics of programmablization and compactation.Figure of merit(FOM)is introduced to evaluate the proposed structure and several traditional edge detection operators for edge detection results.Experiment results show that the FOM of MCM-CNN is three times more than that of the traditional edge detection operators.

The effect of pH on stability and thermal performance of graphene oxide and copper oxide hybrid nanofluids for heat transfer applications:Application of novel machine learning technique

This paper investigates the effects of pH on stability and thermal properties of copper oxide(CuO),graphene oxide(GO),and their hybrid nanofluid(HNF)at different mixing ratios.Initially,sol-gel and Hummer’s method was employed for the synthesis of CuO and GO nanoparticles(NPs),and they are characterized with various techniques.The effects of two different surfactants were analyzed on nanofluid’s(NF’s)stability at different pH values.The properties like thermal conductivity(TC)and viscosity(VST)of NFs were measured at different volume concentration(0.1 vol%to 1.0 vol%)and temperature range of 30-60℃,respectively.The TC and VST of GO/CuO(50:50)HNF are higher than that of GO/CuO(20:80).The figure of merit(FOM)is determined for the studied HNFs.The correlations were presented to calculate the TC as well as VST of HNFs.Two modern novel machine learning-based ensemble approaches were employed for predictive model development for TC and VST of considered HNFs.The comparison of prognostic models with Taylor’s diagram revealed that Bayesian optimized support vector machine(BoASVM)was superior to Bayesian optimized boosted regression trees(BoA-BRT)for both TC and VST models.

Thermoelectric signature of Majorana zero modes in a T-typed double-quantum-dot structure

The thermoelectric effect of the system is theoretically investigated,by coupling Majorana zero mode to the T-typed double-quantum-dot-structure in different ways.It is found that when a single Majorana zero mode is coupled to one of the quantum dots(QDs),the thermoelectric efficiency is suppressed due to the leakage of Majorana zero modes into the QDs.When the Majorana zero mode is coupled to QD2,the suppression of the thermoelectric efficiency is more serious than that of QD1.Furthermore,when two Majorana zero modes are introduced simultaneously,suppression of the thermoelectric effect still takes place.We believe that such results can be candidates for the detection of Majorana bound states and help us understand the role of Majorana zero mode in thermoelectricity.

热电材料及其高压合成

着重分析了高压合成技术在方钴矿、Bi_(2)Te_(3)基、SnSe基、PbTe基、Mg_(2)Si基等典型热电材料的制备及性能调控中的应用,阐释了该技术在推动热电材料发展的独到之处,对高压合成技术在热电材料领域今后的研究发展方向进行了展望。

垂直氮化镓沟槽栅极场效应管的优化设计

在传统的氮化镓沟槽栅极场效应管的基础上,通过引入AlGaN层,在异质结界面处形成二维电子气减小器件的导通电阻,并对漂移层的厚度和掺杂浓度进行讨论,使用TCAD软件对器件进行设计优化。最终优化后的漂移层厚度为6μm,掺杂浓度为5×10^(16)cm^(-3)。器件获得了较低的导通电阻R_(on)=0.47 mΩ·cm^(2),较高的击穿电压V_(BR)=2880 V和品质因子FOM=17.6 GW·cm^(-2)。结果显示出了沟槽栅极垂直氮化镓场效应管在高压大电流应用场景下的优势。

空位有序双钙钛矿A2BX6的弹性和热电性质的第一性原理研究

卤化物钙钛矿在热电应用中表现出了巨大的潜力。准确了解卤化物钙钛矿的热电传输性质对于进一步提高热电设备的应用效率至关重要。本研究采用了Perdew-Burke-Ernzerhof(PBE)和修正的Becke Johnson(mBJ)交换关联泛函探究了卤化物双钙钛矿Rb_(2)SnI6、Rb_(2)PdI6和Cs_(2)PtI6的弹性和热电性质。通过对这些材料的力学稳定性、有效质量、塞贝克系数、功率因子和热电品质因数的研究,我们发现,这三种化合物都是力学稳定的,并且具有可塑性。这些化合物是窄带隙半导体,具有简并的带边结构,结合低的载流子有效质量使得它们具有热电应用潜力。Cs_(2)PtI6在空穴掺杂在500 K温度下可以达到0.76 mV·K^(−1)的高塞贝克系数。由于高塞贝克系数和最大功率因子,Rb_(2)SnI6、Rb_(2)PdI6和Cs_(2)PtI6在p型掺杂下具有高的热电品质因数,分别为0.91、0.96和0.98。总体而言,我们的研究为卤化物钙钛矿的热电性能提供了新的见解,为这些化合物的实验合成提供了有价值的参考。

石墨炔材料热电输运特性及调控的研究进展

石墨炔是一种由sp和sp^(2)碳原子构成的碳基纳米结构材料,具有丰富的碳化学键、特殊的电子结构和优异的半导体性能,可作为低温型热电材料,在热电材料领域具有良好的应用前景。从第一性原理计算的角度,综述了石墨炔的热电输运特性研究进展,阐述了其微观机理,分析了不同调控方式对石墨炔热电输运特性的影响。可为石墨炔在热电领域的应用提供理论借鉴和参考。

具有微型倾斜栅场板的高频AlGaN/GaN HEMT器件结构研究

较小的器件尺寸可以帮助GaN基HEMT实现更高的频率特性,但会使器件内部电场集聚,引起击穿电压降低,严重限制器件的高频功率特性。为了解决上述问题,采用微型倾斜栅场板,可以在保持频率特性的情况下提升器件的击穿电压。通过对具有不同关键参数(既倾斜角度)的AlGaN/GaN HEMT进行仿真分析,系统研究不同倾斜角度对器件特性的影响。研究发现击穿电压(V_(BK))随着倾斜角度的减小而增大;电流截止频率(f_(T))和最大振荡频率(f_(max))均随着倾斜角度的减小而降低。JFOM(JFOM=f_(T)·V_(BK))随着倾斜角度的减小先增大后降低,具有26.6°倾斜角度的器件的JFOM最大,达到了11.13THz V。通过大信号仿真,发现具有最优倾斜角度的器件工作在深AB类状态时,器件的最大增益、饱和输出功率密度、功率附加效率(PAE)分别为12.90dB、5.62W/mm、52.56%。

Enhanced thermoelectric figure of merit at near room temperature in n-type binary silver telluride nanoparticles

In the present study,we have synthesized Ag2Te nanoparticles using the hydrothermal method and showed significant improvement in the thermoelectric properties compared to the bulk Ag2Te sample.Ag2Te nanoparticles showed the highest figure of merit(zT)of 1.37 at 373 K,which is the highest zT reported for this undoped material.This high zT in Ag2Te nanoparticles is mainly due to about~2 times higher electrical conductivity(1967 S/cm)and subsequently~2 times lower thermal conductivity(0.53 W/(m$K))as compared to the bulk Ag2Te sample.The higher electrical conductivity in Ag2Te nanoparticles can be accredited for two reasons(i)better mobility of the charge carrier and(ii)increased carrier concentration.The low thermal conductivity is associated with the enhanced scattering of phonons at the interface of the Ag2Te nanoparticles.

新月十字架纳米结构中多Fano共振的产生和高FOM共振

金属表面等离激元具有许多新颖的光学特性和重要的应用,并且也是当今研究的热点。本文采用有限元方法研究了由新月和十字架组成的新月十字架纳米结构。通过改变结构参数来打破结构对称性,可以产生新的等离激元磁模式和多重Fano共振。同时,通过对称地改变两棒之间的夹角,FOM值可以达到61。我们的结构在多波长传感器、超灵敏生物传感器、表面增强光谱和慢光传输等领域有着重要的应用。

Synthesis and Thermoelectric Properties of Polyaniline

Electrical conductivity and seebeck coefficient at different temperatures,and thermal conductivity at room temperature for various doped polyaniline (PAn) samples were measured,and the thermoelectric figure of merit ZT was calculated.The effects of preparation methods and temperature on thermoelectric properties were discussed.The results show that the electrical conductivity and the seebeck coefficient of PAn are strongly dependent on the preparation conditions and temperature.The electrical conductivity becomes larger and the seebeck coefficient becomes smaller as PAn molecular weight increases.Redoping by organic acid and HCl results in an increase in both electrical conductivity and Seebeck coefficient of PAn,and therefore ZT value.The electrical conductivity increases and the seebeck coefficient decreases as the temperature increases when T<T d (dedoping temperature).The decreasing of the electrical conductivity and increasing of the seebeck coefficient take place by dedoping when T>T d.The thermal conductivity is lower,and insensitive to the sample preparation conditions.

Modeling of Testability Requirement Based on Generalized Stochastic Petri Nets

Testability design is an effective way to realize the fault detection and isolation.Its important step is to determine testability figures of merits(TFOM).Firstly,some influence factors for TFOMs are analyzed,such as the processes of system operation,maintenance and support,fault detection and isolation and so on.Secondly,a testability requirement analysis model is built based on generalized stochastic Petri net(GSPN).Then,the system's reachable states are analyzed based on the model,a Markov chain isomorphic with Petri net is constructed,a state transition matrix is created and the system's steady state probability is obtained.The relationship between the steady state availability and testability parameters can be revealed and reasoned.Finally,an example shows that the proposed method can determine TFOM,such as fault detection rate and fault isolation rate,effectively and reasonably.

Determination of F,S(total),and Cl in the Calcite Rich Limestone and Marbles by WD-XRF Spectrometry

Determining the contents of F,S(total),and Cl in the studied samples of the limestone and marbles with high calcite contents was carried out by the nondestructive method of WDXRFS(Wavelength Dispersive X-ray Fluorescence Spectrometry).All measurements were performed in a vacuum condition using a WDXRF spectrometer S8 TIGER(Bruker AXS,Germany).The studied samples have wide ranges of F,S(total),and Cl contents,and high concentration of calcite(89.5%-99%).Main objective of this research is to develop WDXRF(WD X-ray fluorescence)technique for the determination of F,S(total),and Cl.The calculated values of the ILD(instrumental limit of the detection)were within the interval from 3 for S(total)to 37 for F mg/kg.The repeatability was found to be satisfactory with the relative standard deviations lower than 7%.

Physical properties of ternary thallium chalcogenes Tl2MQ3（M = Zr, Hf; Q = S, Se, Te） via ab-initio calculations

We have reported a first principles study of structural, mechanical, electronic, and thermoelectric properties of the monoclinic ternary thallium chalcogenes Tl2MQ3(M = Zr, Hf;Q = S, Se, Te). The electronic band structure calculations confirm that all compounds exhibit semiconductor character. Especially, Tl2ZrTe3 and Tl2HfTe3 can be good candidates for thermoelectric materials, having narrow band gaps of 0.169 eV and 0.21 eV, respectively. All of the compounds are soft and brittle according to the second-order elastic constant calculations. Low Debye temperatures also support the softness. We have obtained the transport properties of the compounds by using rigid band and constant relaxation time approximations in the context of Boltzmann transport theory. The results show that the compounds could be considered for room temperature thermoelectric applications(ZT ~ 0.9).

The Role of PZT in Flexible 1-3 Piezoelectric Composite for Smart Structure

Piezoelectric composite materials have the ability to perform both sensing and actuating functions.It is a viable candidate for smart actuation in underwater noise controlling with its higher coupling factor and lower acoustic impedance, when the piezoelectric rods are inclined to control its both the shear and the compression damping characteristics.In this paper, a simple physical model of 1-3 piezoelectric composite is advanced for maximizing the electromechanical coupling factor,the acoustic impedance,and the hydrophone figure of merit.

Performance analysis of surface plasmon resonance sensor with high-order absentee layer

A surface plasmon resonance （SPR） sensor with a high-order absentee layer on the top of metallic film is proposed. The performance of the SPR sensor with NaCl, MgO, TiO2 or AlAs high-order absentee layer is analyzed theoretically. The results indicate that the sensitivity and the full width at half maximum of those SPR sensors decrease with the increasing of the order of absentee layer, but the variation of the figure of merit （FOM） depends on the refractive index of absentee layer. By improving the order of absentee layer with high-refractive-index, the FOM of the SPR sensor can be enhanced. The maximum value of FOM for the SPR sensor with high-order TiO2 （or AlAs） absentee layer is 1.059% （or 2.587%） higher than the one with one-order absentee layer. It is believed the proposed SPR sensor with high-order absentee layer will be helpful for developing the high-performance SPR sensors.