Analytic theory for current-voltage characteristic of a nanowire radial p-i-n diode

In this article, process of current flow in a nanowire radial p-i-n diode has been considered in detail. It has been shown that cylindrical geometry of the structure gives rise to specific asymmetry of the concentration distribution for current carriers injected to the i-layer, which is opposite to asymmetry that is due to inequality of carriers’ mobilities. This specific asymmetry rises with bringing the i-layer nearer to the nanowire center. Together with that, decrease of the current density in a “long” p-i-n diode and its increase in a “short” p-i-n diode take place (at given forward voltage). And variation of radial thickness of the i-layer demonstrates maximums in the current density at the thickness close to the bipolar diffusion length.

The effect of the chuck shape on the wafer topography in back grinding of wafer with outer rim

Back Grinding of Wafer with Outer Rim (BGWOR) is a novel method for carrier-less thinning of silicon wafers. Silicon wafers are widely used in integrated circuits (ICs). The topography of the wafer will not only directly affect the efficiency of subsequent processing of semiconductor devices, but correspondingly affect the performance and life of these devices. However, there are few studies on the shape of the ground wafer in BGWOR. In this paper, the mathematical model of the wafer topography in BGWOR was developed. With this model, the radial thickness and total thickness variation (TTV) of a wafer under different parameters, including inclination angles and radii of grinding wheel for dressing chuck, were simulated by MATLAB. Inclination angles and radii of grinding wheels for the dressing chuck had a great influence on the radial thickness and TTV of a wafer in the BGWOR. Lastly, the pilot experiments were conducted to validate the theoretical model of grinding topography and TTV of the wafer in BGWOR. To enhance the flatness of the ground wafer, it is essential to control the shape of the dressing chuck. The research results are helpful to the optimization of the dressing process of the chuck in the BGWOR.

A Preliminary Validation of a New Surgical Procedure for the Treatment of Primary Bladder Neck Obstruction Using a Computational Modeling Approach

A new surgical procedure for the treatment of primary bladder neck obstruction with maintenance of anterograde ejaculation is proposed. In place of monolateral or bilateral bladder neck incision, associated with a loss of ejaculation rate of up to 30%, the new surgical procedure consists of laser drilling the bladder neck with a number of holes and without muscle fiber disruption. The effect of this novel procedure has been studied numerically, with a simplified two-dimensional numerical model of the internal urethral sphincter, varying the position and the number of holes in the fibrotic region of the urethral tissue. Results show an improvement of the urethral sphincter opening by increasing the number of holes, ranging from about 6% to 16% of recovery. Moreover, a non-aligned position of holes positively influences the opening recovery. The concentrations of maximum principal strain and stress have been registered in the proximity of the interface between the physiologic and diseased sphincter, and in those regions where the radial thickness is significantly thinner. The effects on the first five patients have been included in the study, showing improvement in micturition, lower urinary tract symptoms, sustained ejaculatory function, and quality of life.

Once again about the indivisibility of the scattered inductance of the transformer

Purpose. The purpose of the article is to show the inadequacy of the traditional T-shaped equivalent circuit for modeling transformer operations with saturated core. The aim is to point out the unreasonableness of the separation of the transformer leakage inductance into components. The aim is also to explain the need to apply the П-shaped transformer equivalent circuits to transformers with two and three windings with finite radial thickness. Methodology. Analysis of magnetic fields in the transformer window and simulation of transient processes in equivalent circuits of the transformer using a preprocessor ATPDraw to the program ATP. Findings. The unfoundedness of the well-known T-shaped transformer equivalent circuit is shown. Differences in the processes in the core legs and yokes when transformer is connected to the network and during short circuits of the windings are noted. Equivalent circuits of a transformer with two and three windings of finite thickness are proposed, reproducing these differences. Originality. The absence of physical meaning in dividing the transformer leakage inductance into components is stated. The advantages of the П-shaped equivalent circuit are shown when calculating inrush currents accompanying the transformer switching to the network on its inner and outer windings. Practical value. We show theoretical insolvency and practical unsuitability of the Т-shaped equivalent circuit for studying transformer operations accompanied by saturation of the magnetic circuit. Advantages of the П-shaped equivalent circuit are clarified.

Studies of Radial and Thickness Acoustic Resonance Modes of a Piezoceramic with Mixed Polarization Geometry

In this study, the Pb(Zr0.65Ti0.35)O3 (PZT) structure was produced by the solid state reaction method, and a new polarization geometry was used to obtain the radial and thickness modes in cylindrical samples with more efficiency. The polarization procedure was investigated by varying the temperature from 30°C to 80°C. The experimental excitation of radial and thickness modes was observed, and a comparative study was performed with numerical simulations. The comparative analysis of the acoustic response of the cylindrical PZT samples under theoretical and experimental conditions was validated by COMSOL Multiphysics® software. The new polarization geometry technique was used to generate radial thickness and acoustic mixed modes with more efficiency. The results show that the resonance frequency and antiresonance, as well as the impedance mode and phase angle are well adjusted, showing the validation of the technique presented between the theoretical and experimental measurements.

A Method for Reducing Cogging Torque of Integrated Propulsion Motor

How to reduce the cogging torque of the integrated propeller motor is an important means to improve its noise performance because cogging torque is one of the key factors causing torque ripple. We proposed a method to reduce the cogging torque by optimizing the size of the Halbach array’s auxiliary pole. First, an analytical model for the airgap magnetic field of Halbach array based on different dimensions (including the circumference ratio and the radial thickness) of the auxiliary pole is given. Then the finite element method is used to verify the analytical model. On the basis, we calculated the cogging torque of different size of auxiliary poles as sample data by combining different circumference ratio and radial thickness. Furthermore, using the two-variable single-objective neural network genetic optimization algorithm based on Backpropagation (BP), we obtain the optimal size of the auxiliary pole. Finally, comparing the motor cogging torque and torque ripple before and after optimization indicated that the cogging torque and torque ripple are effectively reduced after optimizing the size of the auxiliary pole.

Loss of Cln5 leads to altered Gad1 expression and deficits in interneuron development in mice

The Finnish-variant late infantile neuronal ceroid lipofuscinosis, also known as CLN5 disease, is caused by mutations in the CLN5 gene. Cln5 is strongly expressed in the developing brain and expression continues into adulthood. CLN5, a protein of unknown function, is implicated in neurodevelopment but detailed investigation is lacking. Using Cln5−/− embryos of various ages and cells harvested from Cln5−/− brains we investigated the hitherto unknown role of Cln5 in the developing brain. Loss of Cln5 results in neuronal differentiation deficits and delays in interneuron development during in utero period. Specifically, the radial thickness of dorsal telencephalon was significantly decreased in Cln5−/− mouse embryos at embryonic day 14.5 (E14.5), and expression of Tuj1, an important neuronal marker during development, was down-regulated. An interneuron marker calbindin and a mitosis marker p-H3 showed down-regulation in ganglionic eminences. Neurite outgrowth was compromised in primary cortical neuronal cultures derived from E16 Cln5−/− embryos compared with WT embryos. We show that the developmental deficits of interneurons may be linked to increased levels of the repressor element 1-silencing transcription factor, which we report to bind to glutamate decarboxylase (Gad1), which encodes GAD67, a rate-limiting enzyme in the production of gamma-aminobutyric acid (GABA). Indeed, adult Cln5−/− mice presented deficits in hippocampal parvalbumin-positive interneurons. Furthermore, adult Cln5−/− mice presented deficits in hippocampal parvalbumin-positive interneurons and showed age-independent cortical hyper excitability as measured by electroencephalogram and auditory-evoked potentials. This study highlights the importance of Cln5 in neurodevelopment and suggests that in contrast to earlier reports, CLN5 disease is likely to develop during embryonic stages.

Entropy Generation and Thermoelastic Damping in the In-plane Vibration of Microring Resonators

Thermoelastic damping is a critical issue for designing very high quality factor microresonators. This paper derives the entropy generation, associated with the irreversibility in heat conduction, that is used for ring resonators in in-plane vibration and presents an analytical model of thermoelastic damping according to heat increments calculated by entropy theory. We consider the heat flow only in radial thickness of the ring and obtain a complex temperature field that is out of phase with the mechanical stress. The thermoelastic dissipation is calculated in the perspective of heat increments that appear due to entropy generation. The analytical model is validated by comparing with an LR (Lifshitz and Roukes) model, finite-element method and measurement. The accuracy of the present model is found to be very high for different ambient temperatures and structures. The effects of structure dimensions and vibration frequencies on entropy generation and thermoelastic damping is investigated for ring resonators under in-plane vibration.

Hydrostatic Pressure and Built-In Electric Field Effects on the Donor Impurity States in Cylindrical Wurtzite GaN/AlxGa1−xN Quantum Rings

Within the framework of the effective mass approximation, the ground-state binding energy of a hydrogenic impurity is investigated in cylindrical wurtzite GaN/AlxGa1-xNstrained quantum ring (QR) by means of a variational approach, considering the influence of the applied hydrostatic pressure along the QR growth direction and the strong built-in electric field (BEF) due to the piezoelectricity and spontaneous polarization. Numerical results show that the donor binding energy for a central impurity increases inchmeal firstly as the QR radial thickness(ΔR)decreases gradually and then begins to drop quickly. In addition, the donor binding energy is an increasing (a decreasing) function of the inner radius (height). It is also found that the donor binding energy increases almost linearly with the increment of the applied hydrostatic pressure. Moreover, we also found that impurity positions have an important influence on the donor binding energy. The physical reasons have been analyzed in detail.

Nano Napier Steel Second Ring for SI Applications

Piston top compression rings utilized in North American Spark Ignition (SI) passenger car and light truck engines have undergone a significant migration driven by desire to reduce axial height, mass, radial thickness, wear, incidence of risk of foundry defects and to enable utilization of a consistent, global material independent of manufacturing location. Second rings utilized in similar applications are now in the earlier stages of a similar migration. This paper will present product development of an innovative steel second ring including engine testing (blowby, and lube oil consumption via radiometric tracer method), supplemented by simulation modeling utilizing MIT code, including several more conventional ring cross sectional alternatives.