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This work investigates the working of an inverter and a ring oscillator using symmetrical junction nonaligned double gate field effect transistors (NADGFETs). The performance of the circuits was investigated with two dielectric (k) materials, i.e., silicon dioxide (low-$k,k=3.9$) and hafnium dioxide (high-$k,k=24$), into the device’s gate oxide. Simulations were performed in the TCAD Sentaurus Sdevice mixed-mode environment, and the circuit’s response is analyzed as a function of supply voltage, load capacitance and temperature. Additionally, this work evaluates the effect of changes in device parameters on the performance of inverter and oscillator configuration. Using the graphical method, the optimal supply voltage of the inverter was determined, with a 0.66V optimal supply, the propagation delay of the inverter with low-k and high-k materials was 6.1ps and 7.5ps, respectively. The inverters’ power delay product with low-k materials is 45.38 aJ and with high-k materials, it is 70.37 aJ. For a better insight into the nonaligned double gate devices’ performance, a 5-stage ring oscillator was simulated. The oscillator circuit gives an output voltage/oscillation frequency of 1.18 V/67 GHz and 1.205V/44 GHz, with low-k and high-k materials, respectively, at 1.0V supply. The oscillator with low-k gate oxide shows a 34.3% increase in oscillation frequency. From the results, it can be concluded that the nonaligned devices with low-k gate oxide will give an improved response in low-power and high-frequency applications.

Primary dysmenorrhea is a common gynecological complaint among young women that is related to an autonomic nervous system (ANS) disturbance. Acupuncture is one of several therapeutic approaches for primary dysmenorrhea, since it can modulate ANS function. The heart rate variability (HRV) parameters such as high frequency (HF), low frequency (LF) and LF/HF ratio are generally accepted tools to assess ANS activity. The purpose of this study was to investigate the effects of acupuncture applied at Hegu (LI4) and Sanyinjiao (SP6) points on HRV of women with primary dysmenorrhea during the late luteal phase. The experimental design was a crossover and patient-blinded procedure. All subjects participated in Sham (SA) and Real Acupuncture (RA) procedure, separated by one month, in a crossover sequence. The participants included 38 women (mean age 22.3 years; weight 53.8 kg; height 162.6 cm). HRV measurement was 15 min before and 15 min after an acupuncture procedure. The RA procedure was performed at two bilateral acupoints, but needles were inserted subcutaneously to the acupuncture points for the SA procedure. The RA induced a significant decrease in LF/HF ratio and a significant increase in the HF power, while SA treatment caused a significant increase only in the HF power. Manual acupuncture at bilateral acupoints of LI4 and SP6 may play a role in dysmenorrhea treatment with autonomic nervous system involvement.

We provide the nonparametric estimators of the infinitesimal coefficients of the second-order continuous-time models with discontinuous sample paths of jump-diffusion models. Under the mild conditions, we obtain the weak consistency and the asymptotic normality of the estimators. A Monte Carlo experiment demonstrates the better small-sample performance of these estimators. In addition, the estimators are illustrated empirically through stock index of Shanghai Stock Exchange in high frequency data.

With the continuous strengthening of application requirements, neutron sources are becoming more and more compact, integrated and mobile. There are challenges in two aspects. The first is to achieve high transmission efficiency of high beam current physically, the second is to achieve integration and miniaturization technically. The coupling of RFQ and DTL is a feasible way. A preliminary study on the key physical problems in the RFQ-DTL coupled cavity has been accomplished. For the beam dynamics, the compact matching of RFQ and DTL was studied for the coupled cavity. Taking the compact physical design of the RFQ-DTL for deuterium ion beam of 30 mA with the energy of 11 MeV without MEBT as an example, we studied the smooth transition of the phase advance per unit length, the ability of RFQ transition cell to rotate beam in the transverse phase space, the transverse and longitudinal acceptance optimization of DTL. The RFQ and DTL can be matched transversely and longitudinally after removing MEBT, and the transmission efficiency is 98.7%. For direct coupling of four-vane RFQ and CH-DTL, we studied the realization of the coupling, the factors affecting the field amplitude ratio, the tuning of the cavity, and the influence of the superimposed field on the beam transmission. The field amplitude ratio between RFQ and CH-DTL is from 16.5 to 36.2. Under the influence of the superimposed field, the difference in normalized RMS emittance is less than 1%. We have designed, constructed and cold-test the 750 MHz model cavity. The normalized electric field coefficients measured and simulated are basically in agreement.

Piezoelectric cantilever is suitable as an actuator for micro-flapping-wing aircraft. Higher resonant frequency brings about stronger flight energy, and the flight amplitude can be compensated by displacement–amplification mechanism, such as lever. To obtain a higher resonant frequency, straight piezoelectric bimorph was rolled into spiral-shaped piezoelectric bimorph with identical effective length in this study, which is verified in COMSOL simulations. Simulation results show that compared with the straight piezoelectric bimorph, the spiral-shaped piezoelectric bimorph with two turns has higher inherent frequencies (from 204.79 Hz to 504.84 Hz in terms of axial oscillation mode, and from 319.77 Hz to 704.48 Hz in terms of tangential torsional mode). The spiral-shaped piezoelectric bimorph is fabricated by a precise laser cutting process and consists of two turns with effective length of 60 mm, width of 2.5 mm, and thickness of 1.6 mm, respectively. With the excitation voltage of 100 Vpp applying an electric field across the thickness of the bimorph, the tip displacement of the actuator in the axial oscillation and tangential torsional modes are 85 $\mu$m and 15 $\mu$m, respectively.

Traditionally, magnetic component design has been based on power frequency transformers with sinusoidal excitation. However, the movement towards higher density integrated circuits means that reductions in the size of magnetic components must be achieved by operating at higher frequencies, mainly through nonsinusoidal switching circuits. As this trend continues, computing tools are required to carry out designs of magnetic components that also allow evaluation of the high frequency losses in these components. A computer design package is described here that implements a robust transformer design methodology allowing customizable transformer geometries. The concept of a critical frequency is a vital part of this methodology. In addition, the winding choice at high frequencies is optimized to give the most accurate results for the best possible speed. This paper includes a description of the software design processes used and describes the main aspects that were incorporated into the system.

A new unity gain buffer architecture is presented for on-chip CMOS mixed signal applications. The proposed two-stage common source active load (CSAL) buffer with source feedback offers improved performance compared to previously published source follower and source-coupled differential-pair-based unity gain buffers. A 90-nm CMOS design ($V_{\mathrm{\text{dd}}}$ equals 1.2V) of the buffer has the following performance parameters. With $C_{\mathrm{\text{in}}}$/$C_L$ of 10 fF/250 fF, $f{}_{-3\mathrm{\text{dB}}}$ is 4.4GHz, low frequency gain is 0.16dB, maximum input range within 2% gain variation is 260mV, total harmonic distortion (THD) is $-$63.3dB, offset error (input offset minus output offset) is 26mV, and 1.06mW power consumption. The active load, low gain amplifiers eliminate stability issues and any need for compensation capacitors. The architecture facilitates a relatively large input/output voltage swing while keeping transistors operating in the saturation region, making it suitable for submicron technologies with low rail voltages.

Intensive utilization of Induction Heating (IH) innovations can be seen in numerous areas such as manufacturing industries, domestic or house hold and medicinal applications. The development of high switching frequency switches has encouraged the structure of high frequency inverters which are the key component of IH technology. Controlling the power output in a high frequency inverter for IH application is relatively complicated. This paper focuses on designing and developing a typical series resonance inverter and control it by FPGA-based controller. A MOSFET switch-based DC to AC converter is designed and Zero Voltage Switching (ZVS)-based switching strategy is accomplished to acquire less stress on switching devices and greater conversion efficiency. In this technique, secondary switched capacitor cell was proposed for resonant inverter of high frequency. To optimize the performance of the proposed inverter, the FPGA-based control system is implemented. Higher power density is the greatest advantage of this topology. The experimental and simulation model of the proposed series resonant inverter (SRI) for heating applications is developed and simulated using MATLAB/Simulink software.

The prediction of the spatial mean-square pressure distribution within enclosed high-frequency broadband sound fields is computationally intensive if determined on a frequency-by-frequency basis. Recently an energy-intensity boundary element method (EIBEM) has been formally developed. This method employs uncorrelated broadband directional energy sources to expeditiously predict such pressure distributions. The source directivity accounts for local correlation effects and specular reflection. The method is applicable to high modal density fields, but not restricted to the usual low-absorption, diffuse, and quasi-uniform assumptions. The approach can accommodate fully specular reflection, or any combination of diffuse and specular reflection. This boundary element method differs from the classical version in that element size is large compared to an acoustic wavelength and equations are not solved on a frequency-by-frequency basis. In the earlier EIBEM, the source strength and directivity associated with the energy sources, distributed over enclosure boundaries, were determined in an iterative manner and the directivity was limited to three terms of a Fourier expansion. Here, the original method is improved by eliminating the iteration and allowing for an unlimited number of terms in the Fourier expansion of the directivity function. For verification, the improved EIBEM is compared to experimental measurements and exact analytical solutions; excellent agreement is obtained.

Nonlinear processes in quantum well infrared photodetectors (QWIP) are reviewed. Being an intersubband dipole transition based photoconductor, the nonlinear behaviors in QWIPs are caused by both the (extrinsic) photoconductive transport mechanism and (intrinsic) nonlinear optical processes. Extrinsic nonlinearity leads to a degradation of QWIP performance at high incident power or low operating temperatures. Some intrinsic nonlinear QWIP properties are useful in applications, such as in autocorrelation of short pulses by two-photon absorption. The general area of QWIP nonlinear properties has not been extensively investigated. We point out some directions for further studies and hope to stimulate more research activities.

Novel devices such as Double Gate (DG), Triple Gate (TG) or FinFET, Pi-Gate (PG) and Omega-Gate SOI MOSFETs are potential candidates for achieving the performance predictions of the International Roadmap of the Semiconductor Industry Association. In this paper, we analyzed the DG, TG and PG in comparison with the Single Gate (SG) SOI MOSFET using the commercial 3D numerical simulator SILVACO in the DC and AC regimes from subthreshold region to strong inversion and saturation regions. In the DC regime, multiple gate devices are superior to SG device from micrometer down to nanometer scale lengths. In the AC regime, the advantages of the multiple gate devices over SG devices are significant especially when the channel length reduces below 100 nm. For the first time, we have shown the great interest and potential of these multiple gate devices for high frequency analog applications.

Blast wave induced a frequency spectrum and large deformation of the brain tissue. In this study, new material parameters for the brain material are determined from the experimental data pertaining to these large strain amplitudes and wide frequencies ranging (from 0.01 Hz to 10 MHz) using genetic algorithms. Both hyperelastic and viscoelastic behavior of the brain are implemented into 2D finite element models and the dynamic responses of brain are evaluated. The head, composed of triple layers of the skull, including two cortical layers and a middle dipole sponge-like layer, the dura, cerebrospinal fluid (CSF), the pia mater and the brain, is utilized to assess the effects of material model. The results elucidated that frequency ranges of the material play an important role in the dynamic response of the brain under blast loading conditions. An appropriate material model of the brain is essential to predict the blast-induced brain injury.

A wavelet-decomposed Rayleigh–Ritz model for 2D plate vibration analyses is proposed in this work. For an elastically-supported rectangular plate under Love–Kirchhoff theory, 2D Daubechies wavelet scale functions are used as the admissible functions for analyzing the flexural displacement in an extremely large frequency range. For constructing the mass and stiffness matrices of the system, the 2D wavelet connection coefficients are deduced. It is shown that by inheriting the versatility of the Rayleigh–Ritz approach and the superior fitting ability of the wavelets, the proposed method allows reaching very high frequencies. Validations are carried out in terms of both eigen-frequencies and the forced vibration responses for cases which allow analytical solutions. Effects of the wavelet parameters on the calculation accuracy and convergence are also studied.

Lead–free Sr${}_{1-x}$Ca_xTiO₃ ($x=0,0.4$) ceramics were synthesized via a solid state reaction technique at room temperature. The effects of ionic substitutions in A-sites between strontium and calcium on the structural and dielectric properties were investigated. XRD technique was used to identify the crystal structure and to demonstrate the phase purity. SEM observations have shown homogeneous morphologies for all samples. Dielectric measurements were investigated for a wide range of frequency (100Hz–1GHz) and temperature (25${}^{\circ }$C–250${}^{\circ }$C). Strontium substitution by calcium has not only led to a decrease in the dielectric permittivity value, but also to the loss tangent value by a considerable factor. Interesting values of the quality factor and the quite constant value ${\epsilon }^{\prime }\sim 200$ in extended frequency and temperature ranges show that SCT ceramic could be a real candidate for the development of monolithic ceramic capacitors dedicated to high-frequency lead-free components and/or to extremely high-temperature environments.

Regenerator is a key component for all regenerative cryocoolers. 4K regenerative cryocoolers can be applied to provide cooling for low temperature superconductors, space and military infrared detectors, and medical examination etc. Stirling type pulse tube cryocoolers (SPTC), one type of regenerative cryocoolers, operate at high frequencies. As a result, SPTCs have the advantage of compact structure and low weight compared with G-M type pulse tube cryocoolers operating at low frequencies. However, as the frequency increase the thermal penetration depth of helium gas in the regenerator is greatly reduced which makes the heat transfer between the gas and the regenerator worse. In order to improve the heat transfer efficiency, regenerator materials with smaller hydraulic diameters are used. Therefore the flow resistance between the gas and the regenerator material will increase leading to larger pressure drop from the hot end to the cold end of the regenerator. The cooling performance is deteriorated due to the decreased pressure ratio (maximum pressure divided by minimum pressure) at the cold end. Also, behavior of helium at 4K deviates remarkably from that of ideal gas which has a significant influence both the flow and heat transfer characteristic within a regenerator. In this paper numerical simulation on the behavior of a 4K regenerator at high frequency is carried out to provide guidance for the optimization of the flow and heat transfer performance within a regenerator. Thermodynamic analysis of effect of the non-ideal gas behavior of helium at 4K on 4K regenerator at high frequency is investigated.

We study the application of a B-splines Finite Element Method (FEM) to time-harmonic scattering acoustic problems. The infinite space is truncated by a fictitious boundary and second-order Absorbing Boundary Conditions (ABCs) are applied. The truncation error is included in the exact solution so that the reported error is an indicator of the performance of the numerical method, in particular of the size of the pollution error. Numerical results performed with high-order basis functions (third or fourth order) showed no visible pollution error even for very high frequencies. To prove the ability of the method to increase its accuracy in the high frequency regime, we show how to implement a high-order Padé-type ABC on the fictitious outer boundary. The above-mentioned properties combined with exact geometrical representation make B-Spline FEM a very promising platform to solve high-frequency acoustic problems.

In this paper, we report the progress of several studies conducted in the Matsuki laboratory, including the developments of implanted functional electrical stimulation (FES) systems, functional hyperthermia, transcutaneous power-signal supply systems for an implantable total artificial heart, power supply systems for a rechargeable cardiac pacemaker, and temperature control for an SMA artificial anal sphincter. In the section on the implanted FES system, we describe the safety and high-performance rehabilitation of lost motor function. Duplex communication between a mounted system and implanted devices is an essential technology in meeting this goal. In the section on the real-time internal radiation dose measurement system, we describe the wireless communication system, and a circuit that obtains radiation dose data.

In this paper, we report the progress of several researches in Matsuki laboratory. We approached various researches, which contain developments of implanted FES system, functional hyperthermia, transcutaneous power-signal supply system for implantable total artificial heart, power supply system for a rechargeable cardiac pacemaker, and temperature control for SMA artificial anal sphincter. In the chapter of the implanted FES system, we aimed to reach for higher power output of the implantable secondary coil. The output power is enough to drive the IC system of nervous stimulation. In the chapter of the functional hyperthermia system, we examined heat characteristics of heat elements with various volumes to adjust to the size of each tumor tissue. The heat characteristics show a saturation tendency with an increase of the element volume.

A new-type high frequency broadband acoustic transducer was put forward in this article. Two methods which are composite materials and multi-mode coupled vibration have been used to expand the bandwidth of a high frequency acoustic transducer. With the help of ANSYS software, we get the vibration characteristic of the piezoelectric vibrator by building and analyzing the mode of piezoelectric vibrator. Then, we confirm the optimal design scheme of the piezoelectric sensitive element according to the simulation results. The simulation results show that the -3 db bandwidth of this transducer can reach 340KHz to 420KHz and its maximal transmitting sound level can reach 147.8 dB. It can expand the bandwidth of the transducer effectively.