Accurate and efficient 3D analytic ion implantation model based on Legendre polynomials

Computationally efficient ion implantation modeling has become the essential tool for efficient and accurate CMOS design as aggressive scaling of devices continues. Specifically, computationally efficient two-dimensional (2-D) analytical models are often more attractive than physically-based Monte Carlo simulations since the latter are expensive in terms of computational time. Here we present new computational-efficient analytical models to simulate one-dimensional (1-D) and 2-D impurity and damage profiles. Legendre polynomials are used as basis functions in view of their orthogonality and good interpolation property. Conventional superposition approaches for 2-D implant modeling are explained and the shortcomings are analyzed. A dose splitting approach is incorporated in the new 2-D model to account for the nonlinear dc-channeling effect as implantation-induced damage accumulates. Good agreement with a physically-based and experimentally verified Monte Carlo simulator (UT-MAR-LOWE with TOMCAT) has been obtained for both impurity and damage profiles with a 50/spl times/ reduction of computational time for medium-energy implants.

This paper presents new analytical models for computing the blocking performance of translucent optical networks with sparsely located optical-electrical-optical regeneration nodes. Due to physical layer impairments such as noise and crosstalk, there is a maximum distance [called the transmission reach (TR)] that optical signals can travel before they have to be regenerated. Regeneration nodes that are allocated to a lightpath can also be used for wavelength conversion besides mitigating PLIs. The quality of transmission of a lightpath is satisfied if the length of each segment between two allocated regeneration nodes is less than the TR. We develop analytical models to estimate the call blocking probability for two typical regeneration node allocation policies. The first policy allocates regeneration nodes when the lightpath needs either regeneration or wavelength conversion, while the other allocation policy allocates regenerators only for signal regeneration. The analytical models strike a balance between computational complexity and prediction accuracy. The models are validated using extensive simulation results for a variety of network topologies and parameters.

The declining conventional hydrocarbon resource and increase in energy demand has encouraged the development of unconventional gas resources. One specific type of unconventional gas is the natural gas hydrate. The substantial size of the hydrate resource is a motivating factor in its development. In the early phases of development of hydrate reservoirs data is limited and a large number of sensitivity studies are required. Efficient and accurate analytical models are suitable for such sensitivity studies. One of such solutions is presented in this work. An analytical solution is developed to model rate of gas generation and hydrate recovery when gas is produced from an inclined hydrate-capped gas reservoir where the geothermal gradient is accounted for. As a result of the difference in temperature within the hydrate column, the size of the decomposing area increases with continued production. Development of the analytical model of this work is based on a material balance equation that is combined with the solution for the temperature of the decomposed zone and hydrate equilibrium curve. The three equations are solved simultaneously for the gas generation rate. To validate the assumptions made in the development of the analytical model, a numerical simulator was used. The effects of different reservoir parameters on the reservoir performance were investigated by performing sensitivity analysis. The sensitivity results show how a steeper reservoir that extends closer to the base of permafrost leads to less recovery, or how a thicker hydrate cap could maintain the reservoir pressure for a longer time. The model developed in this study can be used as an approximate engineering tool to evaluate the role of hydrates in improving the productivity and extending the life of tilted hydrate-capped gas reservoirs.

Analytical modeling and simulative investigation are the driving thrust for the performance analysis of very large scale integrated (VLSI) circuits and systems. Contemporary and accurate analytical models are essential for comprehensively understanding the circuit behavior and development of new models. In the present work, motivationally subthreshold region of operation is investigated for on-chip system comprising of driver-interconnect-load using advanced numerical method based finite-difference timedomain (FDTD) technique for the first time. Integrated circuits operating in subthreshold region are of preeminent significance for several highly demanding portable e-gadgets in low power regime and consequently investigated in the present paper. The driver current under subthreshold region are defined by exponential current model. Practical CMOS gate has been incorporated for the accurate modeling of driver gate. Technology node considered is 22nm. It has been investigated that the proposed analytical model for subthreshold region of operation using FDTD technique is highly accurate with respect to SPICE simulation results.

Analytical method for modal analysis of submerged electric motor stator

Efficient genetic based topological mapping using analytical models for on-chip networks

An accurate analytical model of MOSFET without any fitting parameters is proposed which can work from DC-10f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> . The non-quasi-static (NQS) behavior is described by solving the continuity equation and drift-diffusion equation under small signal excitation, and the channel length modulation effect, the overlap capacitance and the junction capacitance are analytically modeled based on physical analysis. The proposed model is validated with the DC and small signal data of 180nm MOSFET which f <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> is 100GHz obtained by TCAD simulations and it is in great agreement with the data up to 1THz.

Nanosecond output pulse and high efficiency are achieved in high-voltage pulsed power supplies (HVPPSs) by applying silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors ( <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s), whose switching speed and switching loss are two vital characteristic parameters. However, the existing research on switching characteristics of SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s is mainly based on the double pulse test circuits with inductive loads, which is not suitable for assessing the devices in HVPPSs with resistive loads. Besides, some simplified analytical methods in HVPPSs lead to poor precision. To accurately predict the switching behavior of SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s in HVPPSs for guiding the design of gate driving circuits and power loops, this article proposes an accurate analytical model considering parasitic inductances, nonlinear parasitic capacitances, transfer characteristic, and output characteristics of SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s. High-precision fitting of transfer characteristic is realized by using the Gaussian function. Besides, the dynamic parasitic gate-drain capacitance is measured by experiment, and three-dimensional curve fitting is performed on the output characteristics to exactly represent <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -resistance. Furthermore, switching speed and switching loss can be directly calculated according to the solved state variables. Finally, the analytical model is verified by experiment, and the effects of gate driving circuits and power loops on switching characteristics are researched in detail.

Multicast communication is one of the most important collective communication operations and is highly demanded in telecommunication environments and scalable parallel and distributed computing systems. In this paper, we consider the issue of supporting multicast in the widely used a three-stage Clos network or /spl upsi/(m,n,r) network. We improve a previously proposed analytical model (Yang and Wang 1998) for the blocking probability of the /spl upsi/(m,n,r) multicast network by introducing more reasonable assumptions based on the properties of multicast communication and the Clos network. We also compare the improved analytical model with the simulation results under three typical routing control strategies. As can be seen, the improved model matches better with the simulation results and further confirms that a /spl upsi/(m,n,r) network with a comparable cost to a permutation network is almost nonblocking for multicast connections.

A reliable and accurate analytical model is desired for the printed circuit board (PCB) with IC package to predict the system response due to loadings such as shock and vibration simulation or even with thermal effect. This work addresses the procedure of model verification by the adoption of experimental modal analysis (EMA) to validate the finite element (FE) model constructed by FE commercial software. The PCB with one package adhered with the heating pad to emulate the heat effect is first considered for completely free boundary condition. The refined FE model of the PCB consists of detail components, such as the chip, substrate, compound and solder balls. The thermal effect on the PCB is simulated to conduct the temperature field analysis as well as the thermal stress. The modal analysis on the PCB with the heating in steady state is then performed to obtain the structural modal parameters, i.e. natural frequencies and mode shapes. The EMA is also carried out to determine the system modal properties that are used to update the analytical FE model. Through the comparison of frequency response functions and modal parameters between the analytical FE model and the real PCB structure, the refined FE model can be verified for material properties and thermal boundary conditions. The same procedure for model verification is then conducted via both EMA and FEA on the PCB in the fixed boundary that complies with the test fixture for the random vibration test of JEDEC specification. The verified equivalent FE model of the PCB can then be adopted to perform spectrum response analysis accordingly.

When a conductive plate moves above a Halbach magnetic source, a magnetic field will be created in the air gap. This field induces eddy currents in the plate and creates drag and lift forces simultaneously. This phenomenon may be applied into eddy current brakes, couplings or magnetic levitation systems. In this paper, by utilizing the derived analytical field solutions of the Maxwell equations with magnetic scalar potential and magnetic field strength, the 3D lift and drag forces, and the flux density distribution in the air gap are predicted and analysed in the steady-state condition. Calculation results produced by analytical model are compared with those from the 3D finite element method. A prototype of the disk-type permanent magnetic eddy-current coupling has been manufactured to validate the accuracy of the 3D analytical model. The results confirm that, compared with 2D analytical model from the papers that had already published, the results calculated by the 3D analytical model have a higher accuracy in performance analysis. Finally, the characteristics of different kinds of magnet arrays are compared based on the proposed model, and several main problems are analysed and discussed.

PurposeThe purpose of this study is to propose an analytical model with consideration of the permeability of soft-magnetic materials, which can predict the magnetic field distribution more accurately and facilitate the initial design and parameter optimization of the machine.Design/methodology/approachThis paper proposes an analytical model of stator yokeless radial flux dual rotor permanent magnet synchronous machine (SYRFDR-PMSM) with the consideration of magnetic saturation of soft-magnetic material. The analytical model of SYRFDR-PMSM is divided into seven regions along the radial direction according to the different excitation source and magnetic medium, and the iron permeability in each region is considered based on the Maxwell–Fourier method and Cauchy’s product theorem. The magnetic vector potential of each region is obtained by the Laplace’s or Poisson’s equation, and the magnetic field solution is determined using the boundary conditions of adjacent regions.FindingsThe inner and outer air-gap flux density, flux linkage, output torque, etc., of SYRFDR-PMSM are predicted by analytical model, resulting in good agreement with that of finite element model. Additionally, the SYRFDR-PMSM prototype is manufactured and the correctness of analytical model is further verified by experiments on no-load back electromotive force and current–torque curve. Reasonable design of the slot opening width and pole arc coefficient can improve the average output torque and reduce output torque ripple.Research limitations/implicationsThe analytical model proposed in this paper assumes that the permeability of soft-magnetic material is a fixed value. However, the actual iron’s permeability varies nonlinearly; thus, the prediction results of the analytical model will have some deviations from the actual machine.Originality/valueThe main contribution of this paper is to propose an accurate magnetic field analytical model of SYRFDR-PMSM. It takes into account the permeability of soft-magnetic material and slot opening, which can quickly and accurately predict the electromagnetic performance of SYRFDR-PMSM. It can provide assistance for the initial design and optimization of SYRFDR-PMSM.

This paper considers the high-rate performance of source coding for noisy discrete symmetric channels with random index assignment (IA). Accurate analytical models are developed to characterize the expected distortion performance of vector quantization (VQ) for a large class of distortion measures. It is shown that when the point density is continuous, the distortion can be approximated as the sum of the source quantization distortion and the channel-error induced distortion. Expressions are also derived for the continuous point density that minimizes the expected distortion. Next, for the case of mean squared error distortion, a more accurate analytical model for the distortion is derived by allowing the point density to have a singular component. The extent of the singularity is also characterized. These results provide analytical models for the expected distortion performance of both conventional VQ as well as for channel-optimized VQ. As a practical example, compression of the linear predictive coding parameters in the wideband speech spectrum is considered, with the log spectral distortion as performance metric. The theory is able to correctly predict the channel error rate that is permissible for operation at a particular level of distortion.

Multimedia decoders mapped onto MPSoC platforms exhibit degraded video quality when the critical system resources such as buffer and processor frequency are constrained. Hence, it is essential for system designers to find the appropriate mix of resources, living within the constraints, for a desired output video quality. A naive approach to do this would be to run expensive system simulations of the decoder tasks mapped onto a model of the underlying MPSoC architecture. This turns out to be inefficient when the input video library set has a large number of video clips. We propose a fast hybrid simulation framework to quantitatively estimate decoded video quality in the context of an MPEG-2 decoder. Here, the workload of simulation heavy tasks are estimated using accurate analytical models. The workload of other light (but difficult to analytically model) tasks are obtained from system simulations. This framework enables the system designer to perform a fast trade-off analysis of the system resources in order to choose the optimal combination of resources for the desired video quality. When compared to a naive system simulation approach, the hybrid simulation-based framework shows speed-up factors of about 5× for motion and 8× for still videos. The results obtained using this framework highlight important trade-offs such as the decoded video quality (measured in terms of the peak signal to noise ratio (PSNR)) vs buffer size and PSNR vs processor frequency.

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