Ramp Parameters Research Articles

Optimization of electrothermal response of GAAFET using Taguchi's approach and an artificial neural network

This work aims to propose a numerical optimization of the electrothermal behavior of a gate-all-around field effect transistor (GAAFET). The electrothermal model is composed of semiconductor equations coupled with heat conduction equations. The finite element method was adopted for the discretization of equations describing the electrothermal model. The effects of geometric and electrical parameters such as gate length (Lg), oxide thickness (tox), nanowire radius (R), trap density (Nt), ramp parameter (α),gate voltage (Vg), and drain voltage (Vd) were analyzed based on a Taguchi L27(37) orthogonal array. Optimization of the control factors was performed. Multiple linear and nonlinear regressions, as well as an artificial neural network, were used. Numerical analysis revealed that the overall optimal drain current and peak temperature device reach the maximum drain current with lower temperature. The analysis of variance shows that the maximum contribution (39 % for the drain current and 36 % for Tmax) is occupied by the ramp coefficient (α) while the other parameters have a small contribution (less than 3 %) to optimize the performance of the GAAFET transistor. The statistical analysis reveals that the developed artificial neural network model is efficient for the prediction of the electrical and thermal characteristics of the GAAFET transistor. The results of this study are promising for advancing our understanding of these innovative transistor technologies, enabling them to be efficiently integrated into the next generation of electronic products.

Global Model Selection via Solution Paths for Robust Support Vector Machine.

Robust support vector machine (RSVM) using ramp loss provides a better generalization performance than traditional support vector machine (SVM) using hinge loss. However, the good performance of RSVM heavily depends on the proper values of regularization parameter and ramp parameter. Traditional model selection technique with gird search has extremely high computational cost especially for fine-grained search. To address this challenging problem, in this paper, we first propose solution paths of RSVM (SPRSVM) based on the concave-convex procedure (CCCP) which can track the solutions of the non-convex RSVM with respect to regularization parameter and ramp parameter respectively. Specifically, we use incremental and decremental learning algorithms to deal with the Karush-Khun-Tucker violating samples in the process of tracking the solutions. Based on the solution paths of RSVM and the piecewise linearity of model function, we can compute the error paths of RSVM and find the values of regularization parameter and ramp parameter, respectively, which corresponds to the minimum cross validation error. We prove the finite convergence of SPRSVM and analyze the computational complexity of SPRSVM. Experimental results on a variety of benchmark datasets not only verify that our SPRSVM can globally search the regularization and ramp parameters respectively, but also show a huge reduction of computational time compared with the grid search approach.

Finding Nano-Ötzi: Cryo-Electron Tomography Visualization Guided by Learned Segmentation.

Cryo-electron tomography (cryo-ET) is a new 3D imaging technique with unprecedented potential for resolving submicron structural details. Existing volume visualization methods, however, are not able to reveal details of interest due to low signal-to-noise ratio. In order to design more powerful transfer functions, we propose leveraging soft segmentation as an explicit component of visualization for noisy volumes. Our technical realization is based on semi-supervised learning, where we combine the advantages of two segmentation algorithms. First, the weak segmentation algorithm provides good results for propagating sparse user-provided labels to other voxels in the same volume and is used to generate dense pseudo-labels. Second, the powerful deep-learning-based segmentation algorithm learns from these pseudo-labels to generalize the segmentation to other unseen volumes, a task that the weak segmentation algorithm fails at completely. The proposed volume visualization uses deep-learning-based segmentation as a component for segmentation-aware transfer function design. Appropriate ramp parameters can be suggested automatically through frequency distribution analysis. Furthermore, our visualization uses gradient-free ambient occlusion shading to further suppress the visual presence of noise, and to give structural detail the desired prominence. The cryo-ET data studied in our technical experiments are based on the highest-quality tilted series of intact SARS-CoV-2 virions. Our technique shows the high impact in target sciences for visual data analysis of very noisy volumes that cannot be visualized with existing techniques.

Influence of plasma inhomogeneity and ohmic heating on the nonlinear absorption of intense laser pulse in collisional magnetized plasma

AbstractThe nonlinear absorption in the interaction of an intense laser pulse with a collisional magnetized plasma is studied by considering the effects of plasma inhomogeneity, ohmic heating, and ponderomotive force. For this purpose, we obtain the plasma electron density, the effective dielectric permittivity, and the wave equation using the Maxwell and hydrodynamic equations and solve this equation by the Runge–Kutta numerical method. The results are shown that by increasing the plasma inhomogeneity, the inverse bremsstrahlung absorption coefficient is increased, and also the density ramp parameter and its sign can affect more the absorption coefficient than the temperature ramp parameter . However, when the initial electron density and temperature increase, the laser field amplitude and the absorption coefficient are increased and the spatial damping rate of the laser pulse becomes highly peaked inside the plasma. It is shown by increasing laser pulse energy, the nonlinear bremsstrahlung absorption coefficient is decreased significantly. The results also indicate that by increasing the external magnetic field, the dielectric permittivity is decreased while the laser energy spatial damping, and the absorption coefficient are increased. Moreover, it is found that by considering the ohmic heating effect, the electrons absorb further energy from the fields and consequently the nonlinear absorption is increased.

Research on Aggregation Flexibility Method of AC/DC Distribution Network Considering Flexibility Balance and Its Application

The large number of connected renewable energy sources has greatly increased the flexibility demand in the system. At the same time, the ac/dc active distribution network (ADN) will also become the main form of the future distribution network. Therefore, it is very meaningful to study how the ac/dc ADN aggregates flexibility and participates in the dispatching of the transmission network as a flexibility resource. To this end, this article aggregates the ac/dc ADN into a virtual generator with ramp and power parameters. In particular, the flexibility in the ac/dc ADN is subdivided into ramp and power flexibility and incorporated into the aggregation model. Then, an energy-based flexibility cost function is constructed for the aggregated distribution network. Therefore, without relying on the electricity market, the distribution network can be used as a flexible resource to participate in the flexible dispatching of the transmission network. Finally, the effectiveness of the proposed method and model is verified by several case studies.

Optimization method of power supply mode and connected to external power grid of CZ railway traction station

Aiming at the problem of long slopes and weak power grids along the railway in high altitude mountainous areas, an optimization method of power supply mode and access to external power grid of CZ railway traction station is proposed. First, combined with the terrain and altitude along the railway and the characteristics of the regional power grid, a sample library of the power supply mode and access to external power grid of CZ railway traction station is designed. Secondly, combined with the train operation diagram and line ramp parameters, the full-day periodic load of each power supply arm is simulated. Then, according to the sample library, a “source-net-load” integrated simulation model is constructed in Simulink. Then, the three-phase voltage unbalance evaluation model of the power system is constructed in combination with relevant standards. Finally, the optimal wiring scheme is selected by using the evaluation model and the simulated voltage unbalance index.

Muscle velocity recovery cycles in myopathy

ObjectiveTo understand the pathophysiology of myopathies by using muscle velocity recovery cycles (MVRC) and frequency ramp (RAMP) methodologies. Methods42 patients with quantitative electromyography (qEMG) and biopsy or genetic verified myopathy and 42 healthy controls were examined with qEMG, MVRC and RAMP, all recorded from the anterior tibial muscle. ResultsThere were significant differences in the motor unit potential (MUP) duration, the early and late supernormalities of the MVRC and the RAMP latencies in myopathy patients compared to controls (p < 0.05 apart from muscle relatively refractory period (MRRP)). When dividing into subgroups, the above-mentioned changes in MVRC and RAMP parameters were increased for the patients with non-inflammatory myopathy, while there were no significant changes in the group of patients with inflammatory myopathy. ConclusionsThe MVRC and RAMP parameters can discriminate between healthy controls and myopathy patients, more significantly for non-inflammatory myopathy. MVRC differences with normal MRRP in myopathy differs from other conditions with membrane depolarisation. SignificanceMVCR and RAMP may have a potential in understanding disease pathophysiology in myopathies. The pathogenesis in non-inflammatory myopathy does not seem to be caused by a depolarisation of the resting membrane potential but rather by the change in sodium channels of the muscle membrane.

Rate and noise-induced tipping working in concert.

Rate-induced tipping occurs when a ramp parameter changes rapidly enough to cause the system to tip between co-existing, attracting states. We show that the addition of noise to the system can cause it to tip well below the critical rate at which rate-induced tipping would occur. Moreover, it does so with significantly increased probability over the noise acting alone. We achieve this by finding a global minimizer in a canonical problem of the Freidlin-Wentzell action functional of large deviation theory that represents the most probable path for tipping. This is realized as a heteroclinic connection for the Euler-Lagrange system associated with the Freidlin-Wentzell action and we find it exists for all rates less than or equal to the critical rate. Its role as the most probable path is corroborated by direct Monte Carlo simulations.

TRAP: Traffic-Based Adaptive Ramp Packing for Blind Cancellation in Autonomous Vehicles

Autonomous Vehicles (AVs) rely on a set of radar sensors used to map surrounding environment. Most commonly used radar sensors for AVs use Frequency Modulated Continuous Wave (FMCW) ramps for object parameter (i.e., range and relative velocity) estimation. Due to large bandwidth requirement of FMCW radar, only a limited number of AVs can be operated in the available spectrum. Consequently, the co-existence of large number of AVs may lead to the problem of radar-to-radar interference, also referred to as radar blindness. Moreover, the problem becomes more severe in the higher traffic scenarios. In this work, we propose a Traffic-based Adaptive Ramp Packing (TRAP) scheme, which adapts radar range and assigns FMCW ramp parameters on the basis of inter-vehicular distance among AVs. Specifically, TRAP scheme allows to make effective use of the available time-frequency resource, and enables to pack more ramps in the dense traffic scenarios. Further, it is shown that adaptive radar range adoption may provide significantly more number of ramps in the given bandwidth. Furthermore, through simulation results, it is shown that TRAP significantly reduces the blind probability against state-of-the-art fixed range schemes.

The Role of Frontal Thrusts in Tsunami Earthquake Generation

ABSTRACT The frontal sections of subduction zones are the source of a poorly understood hazard: “tsunami earthquakes,” which generate larger-than-expected tsunamis given their seismic shaking. Slip on frontal thrusts is considered to be the cause of increased wave heights in these earthquakes, but the impact of this mechanism has thus far not been quantified. Here, we explore how frontal thrust slip can contribute to tsunami wave generation by modeling the resulting seafloor deformation using fault-bend folding theory. We then quantify wave heights in 2D and expected tsunami energies in 3D for both thrust splays (using fault-bend folding) and down-dip décollement ruptures (modeled as elastic). We present an analytical solution for the damping effect of the water column and show that, because the narrow band of seafloor uplift produced by frontal thrust slip is damped, initial tsunami heights and resulting energies are relatively low. Although the geometry of the thrust can modify seafloor deformation, water damping reduces these differences; tsunami energy is generally insensitive to thrust ramp parameters, such as fault dip, geological evolution, sedimentation, and erosion. Tsunami energy depends primarily on three features: décollement depth below the seafloor, water depth, and coseismic slip. Because frontal ruptures of subduction zones include slip on both the frontal thrust and the down-dip décollement, we compare their tsunami energies. We find that thrust ramps generate significantly lower energies than the paired slip on the décollement. Using a case study of the 25 October 2010 Mw 7.8 Mentawai tsunami earthquake, we show that although slip on the décollement and frontal thrust together can generate the required tsunami energy, &amp;lt;10% was contributed by the frontal thrust. Overall, our results demonstrate that the wider, lower amplitude uplift produced by décollement slip must play a dominant role in the tsunami generation process for tsunami earthquakes.

Statistical impact of wind-speed ramp events on turbines, via observations and coupled fluid-dynamic and aeroelastic simulations

Abstract. Via 11 years of high-frequency measurements, we calculated the probability space of expected offshore wind-speed ramps, recasting it compactly in terms of relevant load-driving quantities for horizontal-axis wind turbines. A statistical ensemble of events in reduced ramp-parameter space (ramp acceleration, mean speed after ramp, upper-level shear) was created to capture the variability of ramp parameters and also allow connection of such to ramp-driven loads. Constrained Mann-model (CMM) turbulence simulations coupled to an aeroelastic model were made for each ensemble member, for a single turbine. Ramp acceleration was found to dominate the maxima of thrust-associated loads, with a ramp-induced increase of 45 %–50 % for blade-root flap-wise bending moment and tower-base fore–aft moment, plus ∼ 3 % per 0.1 m/s2 of bulk ramp-acceleration magnitude. The ensemble of ramp events from the CMM was also embedded in large-eddy simulation (LES) of a wind farm consisting of rows of nine turbines. The LES uses actuator-line modeling for the turbines and is coupled to the aeroelastic model. The LES results indicate that the ramps, and the mean acceleration associated with them, tend to persist through the farm. Depending on the ramp acceleration, ramps crossing rated speed lead to maximum loads, which are nearly constant for the third row and further downwind. Where rated power is not achieved, the loads primarily depend on wind speed; as mean winds weaken within the farm, ramps can again have U &lt; Vrated. This leads to higher loads than pre-ramp conditions, with the distance where loads begin to increase depending on inflow Umax⁡ relative to Vrated. For the ramps considered here, the effect of turbulence on loads is found to be small relative to ramp amplitude that causes Vrated to be exceeded, but for ramps with Uafter &lt; Vrated, the combination of ramp and turbulence can cause load maxima. The same sensitivity of loads to acceleration is found in both the CMM-aeroelastic simulations and the coupled LES.

Electromagnetic field and three‐phase lag in a compressed rotating isotropic homogeneous micropolar thermo‐viscoelastic half‐space

Using a thermal shock of the ramp type, the authors constructed a unique mathematical three‐phase‐lag scheme in a compressed rotating isotropic homogeneous micropolar thermo‐viscoelastic medium. The model is applied to solve an issue of an exactly performing half‐space exposed to defined boundary circumstances with an electromagnetic field. Normal mode analysis and Lame's potentials methods were used to obtain the analytical answers. The authors were interested in studying the effect of the initial stress, ramp time, magnetic field, and rotation on distributing, displacement, temperature, and stress, as well as induced electric and magnetic distribution. The findings showed that the impact of the viscous, ramp parameter, rotation, phase lag, magnetic field, and initial stress on the micropolar thermo‐viscoelastic medium is distinct.

Early detection of evolving critical illness myopathy with muscle velocity recovery cycles

ObjectiveTo investigate the sensitivity of muscle velocity recovery cycles (MVRCs) for detecting altered membrane properties in critically ill patients, and to compare this to conventional nerve conduction studies (NCS) and quantitative electromyography (qEMG). MethodsTwenty-four patients with intensive care unit acquired weakness (ICUAW) and 34 healthy subjects were prospectively recruited. In addition to NCS (median, ulnar, peroneal, tibial and sural nerves) and qEMG (biceps brachii, vastus medialis and anterior tibial muscles), MVRCs with frequency ramp were recorded from anterior tibial muscle. ResultsMVRC and frequency ramp parameters showed abnormal muscle fiber membrane properties with up to 100% sensitivity and specificity. qEMG showed myopathy in 15 patients (63%) while polyneuropathy was seen in 3 (13%). Decreased compound muscle action potential (CMAP) amplitude (up to 58%) and absent F-waves (up to 75%) were frequent, but long duration CMAPs were only seen in one patient with severe myopathy. ConclusionsAltered muscle fiber membrane properties can be detected in patients with ICUAW not yet fulfilling diagnostic criteria for critical illness myopathy (CIM). MVRCs may therefore serve as a tool for early detection of evolving CIM. SignificanceCIM is often under-recognized by intensivists, and large-scale longitudinal studies are needed to determine its incidence and pathogenesis.

Rotational Effect on the Propagation of Waves in a Magneto-Micropolar Thermoelastic Medium

The present paper aims to explore how the magnetic field, ramp parameter, and rotation affect a generalized micropolar thermoelastic medium that is standardized isotropic within the half-space. By employing normal mode analysis and Lame’s potential theory, the authors could express analytically the components of displacement, stress, couple stress, and temperature field in the physical domain. They calculated such manners of expression numerically and plotted the matching graphs to highlight and make comparisons with theoretical findings. The highlights of the paper cover the impacts of various parameters on the rotating micropolar thermoelastic half-space. Nevertheless, the non-dimensional temperature is not affected by the rotation and the magnetic field. Specific attention is paid to studying the impact of the magnetic field, rotation, and ramp parameter of the distribution of temperature, displacement, stress, and couple stress. The study highlighted the significant impact of the rotation, magnetic field, and ramp parameter on the micropolar thermoelastic medium. In conclusion, graphical presentations were provided to evaluate the impacts of different parameters on the propagation of plane waves in thermoelastic media of different nature. The study may help the designers and engineers develop a structural control system in several applied fields.

Response of ramp-type heating in a monoclinic generalized thermoelastic material

PurposeThe two-dimensional deformation of a homogeneous, thermally conducting, monoclinic material has been studied by using Laplace and Fourier transforms technique. A linear temperature ramping function is used to more realistically model: thermal loading of the half-space surface. The general solution obtained is applied to a specific problem of a half-space subjected to ramp-type heating and loading. The displacements, stresses and temperature distribution so obtained in the physical domain are computed numerically and illustrated graphically. The comparison for Lord-Shulman (L-S), Green and Lindsay (G–L), Green and Naghdi (G–N) and Chandrasekharaiah and Tzou (CTU) theories have been shown graphically to estimate the effect of ramping parameter of heating for an insulated and temperature gradient boundaries.Design/methodology/approachThe design of the study is eigenvalue approachFindingsHomogeneous, thermally conducting monoclinic material has been taken under consideration to study the effect of linear temperature ramping parameter on temperature and normal displacement field. It is observed that magnitude of field quantities is large near the point of application of source for the non-dimensional values of time in all the four models. The numerical values for the field quantities are computed graphically for a wide range of values of finite pulse rise-time in the two situations t0 < t, t0 > t for generalized thermoelasticity theories.Originality/value(1) Governing equations for homogeneous, t0 thermally conducting, monoclinic material are described and solved. (2) Eigen value approach is used to solve the problem. (3) The effect of ramping parameter of heating has been studied for various models of the thermoelasticity to show the comparision between them.

Polarization preservation of polarized deuteron beams in the electron ion collider at Brookhaven National Laboratory

The physics program at the future electron ion collider (EIC) calls for polarized neutron beams at high energies. The best neutron carriers are $^{3}\mathrm{He}$ nuclei and deuterons. Both neutron carriers are expected to be utilized by the spin physics program in the EIC. Owing to the small magnetic moment anomaly of a deuteron particle, significantly higher magnetic fields are required for spin rotation, so that full Siberian snakes are not feasible. However, the resonance strengths are weak, and the number of resonances is small. It is possible to deal with individual resonances using conventional methods such as a betatron tune jump and vertical ac dipole for intrinsic depolarizing resonances, and a weak partial snake for imperfection resonances. This study employed a realistic magnet ramp rate and parameters (both transverse and longitudinal emittances, as well as realistic lattices) to show that it is possible to accelerate polarized deuterons beyond 100 GeV/n. This paper summarizes the details of the feasibility of a polarized deuteron beam for the future EIC at Brookhaven National Laboratory.

Effect of magnetic field and three-phase-lag in a rotating micropolar thermo-viscoelastic half-space homogeneous isotropic material

This paper is devoted to three-phase-lag theory of thermo-elasticity to study the effects of rotation, ramp parameter and magnetic field in a micropolar generalized thermo-viscoelastic medium. By employing normal mode analysis and Lame’s potential theory, the analytical expressions for the displacement components, stresses components, couple stress and temperature field are obtained in the physical domain. Numerical examples are displayed to illustrate the effects of magnetic field, rotation and ramp parameter on the results. When there is no phase-lag effects, the results of the current paper are reduced to exactly the same results available in the literature. However, the magnetic field and rotation have no effect on the non-dimensional temperature. The results indicate that the effect of magnetic field, rotation, ramp parameter, viscous and Phase-lag on the micropolar thermo-viscoelastic medium are very pronounced.

Rotation and Phase-Lag Effects in a Micropolar Thermo-viscoelastic Half-Space

The aim of the present paper is to study the effects of rotation and three-phase-lag parameters in a micropolar generalized thermo-viscoelastic medium. By employing normal mode analysis, the analytical expressions for the displacement components, stresses and temperature field are obtained in the physical domain. These expressions are also calculated numerically, and corresponding graphs are plotted to illustrate and compare theoretical results. The effects of rotation, ramp and viscous parameters are also studied. Some particular cases of interest have been deduced from the present investigation.

Effect of potential ramp in the potentiodynamic stage of anodization on morphology of nanostructured TiO2 developed on Ti6Al4V alloy

Ti6Al4V titanium alloy samples, having disc shape of Ø16 x 3 mm, and an initial microrough morphology, were anodized in a custom built electrochemical cell having two electrode configuration, in 1M H3PO4 + 0.5 wt% HF electrolyte, anodization potential of 20 V, and anodization time of 30 min. The anodization potential was applied with different potential ramps (0.025, 0.05, 0.1, 0.2, 0.5, and 1 V/s). The modified surface morphology was evaluated using scanning electron microscopy (SEM). Our results show efficient synthesis of ordered nanotubular TiO2 layers on flat, microrough surfaces of two-phase Ti6Al4V alloy, and the importance of potential ramp parameter’s optimization. Potential ramps of 0.025, 0.05, and 0.1 V/s lead to development of continuous, uniform, self-ordered nanotubular TiO2 layers, with internal diameters in 25-110 nm range, and layer thickness in 150-400 nm range. Potential ramps of 0.2 and 0.5 V/s lead also to development of self-ordered nanotubular TiO2 layers, with internal diameters in 30-115 nm range, and layer thickness in 250-450 nm range, but the layers are discontinuous.

Response of fractional ordered micropolar thermoviscoelastic half-space with diffusion due to ramp type mechanical load

• Interactions caused by mechanical shock in micropolar diffusive medium are studied. • Problem has been modeled in context of generalized fractional thermoelasticity. • Laplace and Fourier transforms are used to solve the problem. • Effects of fractional parameter, micropolarity and diffusion are noticed. The current manuscript is devoted to scrutinize the effects of fractional parameter, micropolarity and diffusion on the interactions caused by a ramp type mechanical shock in a generalized thermo-viscoelastic solid half-space. The medium is assumed to be unstrained and unstressed initially and has uniform temperature. The problem has been modeled by employing the fractional generalization of the Lord–Shulman theory to carry the investigation. The governing equations in xz -plane are handled with an analytical–numerical technique based on Laplace–Fourier transforms. Expressions for displacement, stresses, temperature and mass concentration in the physical domain are obtained using a numerical inversion technique. The problem is illustrated by computing the numerical values of the field variables for a magnesium crystal like material. Comparisons of the physical quantities are shown in figures to study the effects of fractional parameter, micropolarity, diffusion and ramp parameter. Some particular cases of interest have also been inferred from the present problem.