一种可变门极电阻的大功率IGBT驱动

通过分析大功率IGBT寄生参数及主功率回路寄生参数对IGBT驱动的影响,提出了一种基于可变门板电阻的驱动电路,提高了驱动模块的产品兼容性,实现了驱动器对IGBT开关特性的精确控制,有效抑制开关过程中由于di/dt引起的电压尖峰.最后在Sabor中搭建了型号为FZ1500R33HE3的大功率IGBT的仿真模型,并进行仿真分析;通过搭建实物平台进行了双脉冲实验.仿真和实验结果表明,该驱动电路具有可行性.     

一种基于多阈值保护的大功率IGBT驱动

通过分析VCE检测电路的传递函数,合理配置检测电路电气参数,根据IGBT发生短路时的特点,提出了一种基于多阈值过流保护和变电阻式软关断的大功率IGBT驱动保护策略,实现了驱动器对IGBT有效控制,并抑制开关过程中由于di/dt引起的电压尖峰.最后在Sabor中搭建了型号为FZ1500R33HE3的大功率IGBT的仿真模型,进行仿真分析,并搭建实物平台进行了短路保护实验.仿真和实验结果表明该驱动电路具有可行性.     

Design of switching sequences for controllability realization of switched linear systems

In this paper, we study the problem of designing switching sequences for controllability of switched linear systems. Each controllable state set of designed switching sequences coincides with the controllable subspace. Both aperiodic and periodic switching sequences are considered. For the aperiodic case, a new approach is proposed to construct switching sequences, and the number of switchings involved in each designed switching sequence is shown to be upper bounded by d(d-d₁+1). Here d is the dimension of the controllable subspace, , where (A_i,B_i) are subsystems. For the periodic case, we show that the controllable subspace can be realized within d switching periods.     

Tool-path generation of planar NURBS curves

It has been widely used in CAD field for many years and gradually applied in CAM area with the prevalence of NURBS interpolator equipped in CNC controllers. But few of them provide the tool radius compensation function. In order to achieve the goal of generating tool-path, an algorithm was presented to offset NURBS curves by an optimum process for CAD/CAM systems in this paper. NURBS format is ideal for HSM applications, but not all NURBS outputs are equal and standard. Basically, there are two different ways to generate NURBS tool-paths; one is to fit a NURBS curve to the conventional tool-path output, the other one is to generate a NURBS tool-path from the start. The main targets for the tool-path of this paper are: (1) To keep a constant distance d between progenitor curve C(t) and offset curve C_d(t) on the normal direction of C(t); (2) to alternate the order k of the basis function in offset curve C_d(t); (3) to oscillate the number of control points of offset curve C_d(t) and compare it with progenitor curve C(t). In order to meet the tolerance requirements as specified by the design, this study offsets the NURBS curves by a pre-described distance d. The principle procedure consists of the following steps: (1) construct an evaluating bound error function; (2) sample offset point-sequenced curves based on first derivatives; (3) give the order of NURBS curve and number of control points to compute all initial conditions and (4) optimize the control points by a path searching algorithm.     

Prediction of the moment capacity of reinforced concrete slabs in fire using artificial neural networks

In this study, the application of artificial neural networks (ANN) to predict the ultimate moment capacity of reinforced concrete (RC) slabs in fire is investigated. An ANN model is built, trained and tested using 294 data for slabs exposed to fire. The data used in the ANN model consists of seven input parameters, which are the distance from the extreme fiber in tension to the centroid of the steel on the tension side of the slab (d′), the effective depth (d), the ratio of previous parameters (d′/d), the area of reinforcement on the tension face of the slab (A_s), the fire exposure time (t), the compressive strength of the concrete (f_cd), and the yield strength of the reinforcement (f_yd). It is shown that ANN model predicts the ultimate moment capacity (M_u) of RC slabs in fire with high degree of accuracy within the range of input parameters considered. The moment capacities predicted by ANN are in line with the results provided by the ultimate moment capacity equation. These results are important as ANN model alleviates the problem of computational complexity in determining M_u.     

Perceptrons of large weight

A threshold gate is a linear combination of input variables with integer coefficients (weights). It outputs 1 if the sum is positive. The maximum absolute value of the coefficients of a threshold gate is called its weight. A degree-d perceptron is a Boolean circuit of depth 2 with a threshold gate at the top and any Boolean elements of fan-in at most d at the bottom level. The weight of a perceptron is the weight of its threshold gate.For any constant d ≥ 2 independent of the number of input variables n, we construct a degree-d perceptron that requires weights of at least \(n^{\Omega (n^d )} \); i.e., the weight of any degree-d perceptron that computes the same Boolean function must be at least \(n^{\Omega (n^d )} \). This bound is tight: any degree-d perceptron is equivalent to a degree-d perceptron of weight \(n^{O(n^d )} \). For the case of threshold gates (i.e., d = 1), the result was proved by Håstad in [2]; we use Håstad’s technique.     

Improved quantum ripple-carry addition circuit

A serious obstacle to large-scale quantum algorithms is the large number of elementary gates, such as the controlled-NOT gate or Toffoli gate. Herein, we present an improved linear-depth ripple-carry quantum addition circuit, which is an elementary circuit used for quantum computations. Compared with previous addition circuits costing at least two Toffoli gates for each bit of output, the proposed adder uses only a single Toffoli gate. Moreover, our circuit may be used to construct reversible circuits for modular multiplication, Cx mod M with x < M, arising as components of Shor’s algorithm. Our modular-multiplication circuits are simpler than previous constructions, and may be used as primitive circuits for quantum computations.     

Theory of the in-circuit observation of VLSICs using autocorrelation functions

A method of formation of an autocorrelation function (ACF) as applied to the problem of observation of interior points of processor VLSICs is considered. As elementary events for the synthesis of empirical ACF values, the antecedently determined vectors z _ξ,t = x _η,t ∪ x _ω,t and y _{λ,t + τ} are used; the setting for them is performed by an integrated circuit control automat. It is shown that the principle of statistical control using ACF in asymptotics is more definite than linear signature analysis or condition vector counting.     

Electrical performance of static induction transistor with transverse structure

A novel static induction transistor with transverse surface gate structure was designed and successfully fabricated in this paper. Its basic electrical characteristics and frequency performance was investigated in depth. The optimum technological parameters such as source-gate space and epitaxial layer thickness for obtaining excellent frequency performance and high blocking voltage capacity were represented and discussed in detail. The main advantage of this work is that the performances of device were improved with simple structure and technological processes. The experimental and simulated results demonstrate the trans-conductance g_m and gate-source breakdown voltage BV_GS of the transverse type SIT increase from 60 to 87 ms and 20 to 26 V, respectively, in addition to obtaining higher than 100 MHz operating frequency under relatively simple technology processes compared with those of traditional vertical SIT.     

Optimal controls for stochastic systems with singular noise

Stochastic control systems of the form dx₁ = f(t, x, u_t)dt + g(t, x)db_t (0 t 1), with g singular and general cost, are discussed. It is shown that there is an optimal relaxed control u that depends on the past of x and the driving process b. Nonstandard methods are used.     

Microwave noise modeling for PHEMT using artificial neural network technique

An improved noise model for pseudomorphic high electron mobility transistors (PHEMT) based on the combination of the artificial neural network (ANN) and conventional equivalent circuit modeling technique is presented. The frequency dispersion of the gate noise model parameter P, drain noise model parameter R, and the correlation coefficient C have been taken into account by using an ANN model. The influence of the gate leakage current can be accommodated by using the proposed noise model. The noise model parameters are determined directly from on wafer noise parameters measurement based on the noise correlation matrix technique. Good prediction for noise parameters and significant improvements of the accuracy of noise parameters are obtained up to 26 GHz for 2 × 40 μm gate width (number of gate fingers × unit gate width) 0.25 μm Double Heterojunction δ‐doped PHEMTs over a wide range of bias points. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

32-site microelectrode modified with Pt black for neural recording fabricated with thin-film silicon membrane

Multi-electrode array is an important tool in the study of neural-network,cognition,remembrance,as well as brain-computer-interface,etc.Fork-like 32-site microelectrodes are developed with silicon.By use of integrated circuit technology,the length of the electrodes,the area of the recording sites,as well as the spaces between the sites are closely controlled.SiO2/SiNx/SiO2composite dielectric membrane and Pt black are introduced to improve the characteristics of the electrodes.The whole thickness of the thin-film probe was 21μm.By combining the modifying process with the micro-fabrication method,this kind of silicon based microelectrode satisfies high-density recording and the performance characterization is evaluated by test in vitro and in vivo.     

Synthetic Sequence Design for Signal Location Search

We present a new approach to identify the locations of critical DNA or RNA sequence signals which couples large-scale synthesis with sophisticated designs employing combinatorial group testing and balanced Gray codes. Experiments in polio and adenovirus demonstrate the efficiency and generality of this procedure. In this paper, we give a new class of consecutive positive group testing designs, which offer a better tradeoff of cost, resolution, and robustness than previous designs for signal search. Let n denote the number of distinct regions in a sequence, and d the maximum number of consecutive positives regions which can occur. We propose a design which improves on the consecutive-positive group testing designs of Colbourn. Our design completely identifies the boundaries of the positive region using t tests, where t≈log₂(1.27n/d)+0.5log₂(log₂(1.5n/d))+d.     

Adaptive stabilization of uncertain nonholonomic systems by state and output feedback

In this paper, adaptive state feedback and output feedback control strategies are presented for a class of nonholonomic systems in chained form with drift nonlinearity and parametric uncertainties. Both control laws are developed using state scaling and backstepping techniques. In particular, novel adaptive switching is proposed to overcome the uncontrollablity problem associated with x₀(t₀)=0. Observer-based output feedback design is developed when only partial system states are measurable, and a filtered observer rather than the traditional linear observer is used to handle the technical problem due to the presence of unavailable states in the regressor matrix. The proposed control strategies can steer the system globally converge to the origin, while the estimated parameters maintain bounded.     

On the joint nonlinear filtering-smoothing of diffusion processes

The smoothing of diffusions dx_t = f(x_t) dt + σ(x_t) dw_t, measured by a noisy sensor dy_t = h(x_t) dt + dv_t, where w_t and v_t are independent Wiener processes, is considered in this paper. By focussing our attention on the joint p.d.f. of (x_τ x_t), 0 ≤ τ < t, conditioned on the observation path {y_s, 0 ≤ s ≤ t}, the smoothing problem is represented as a solution of an appropriate joint filtering problem of the process, together with its random initial conditions. The filtering problem thus obtained possesses a solution represented by a Zakai-type forward equation. This solution of the smoothing problem differs from the common approach where, by concentrating on the conditional p.d.f. of x_τ alone, a set of ‘forward and reverse’ equations needs to be solved.     

Influence of dielectric material near tunnel junction on analog/RF and linearity figure of merits in hetero dielectric (HG) TFET: A detailed study

In this work, the effect of dielectric material near the source region on analog/RF and linearity figure of merits in hetero gate TFET (HG-TFET) are investigated through Technology Computer Aided Design device simulator. The various dielectric materials considered in this study are SiO₂, Al₂O₃, and HfO₂. The several RF/analog metrics studied in this work are transconductance (g_m), output conductance (g_d), gain (g_m/g_d), gate capacitance, cut-off frequency, and gain frequency product. Furthermore, the various linearity parameters discussed are higher order derivative of g_m (g_m2 and g_m3), voltage intercept points (VIP2 and VIP3), 3rd-order input intercept power, and 3rd-order intermodulation power for different high-k dielectric near the source region in HG-TFET. Results reveal that RF/analog performance is improved, whereas, the linearity characteristic is suppressed in HG-TFET using HfO₂ as the gate dielectric near the source.     

An orthogonal analysis method for decoupling the nozzle geometrical parameters of microthrusters

This paper proposes an orthogonal analysis method for decoupling the multiple nozzle geometrical parameters of microthrusters, thus an reconfigured design can be implemented to generate a proper thrust. In this method, the effects of various nozzle geometrical parameters, including throat width W _t , half convergence angle θ _in , half divergence angle θ _out , exit-to-throat section ratio W _e /W _t and throat radius of the curvature R _t /W _t , on the performance of microthrusters are sorted by range analysis. Analysis results show that throat width seriously affects thrust because range value of 67.53 mN is extremely larger than the range value of other geometry parameters. For average specific impulse (ASI), the range value of exit-to-throat section ratio W _e /W _t and half divergence angle θ _out are 4.82 s and 3.72 s, respectively. Half convergence angle with the range value of 0.39 s and throat radius with 0.32 s have less influence on ASI compared with exit-to-throat section ratio and half divergence angle. When increasing the half convergence angle from 10° to 40° and throat radius of the curvature from 3 to 9, average specific impulse initially decreases and then increases. A MEMS solid propellant thruster (MSPT) with the reconfigured geometrical parameters of nozzle is fabricated to verify the feasibility of the proposed method. The thrust of the microthruster can reach 25 mN. Power is estimated to be 0.84 W. This work provides design guideline to reasonably configure geometry parameters of microthruster.     

Planar split dual gate MOSFET

A new planar split dual gate （PSDG） MOSFET device, its characteristics and experimental results, as well as the three dimensional device simulations, are reported here for the first time. Both theoretical calculation and 3D simulation, as well as the experiment data, show that the two independent split dual gates can provide dynamical control of the device characteristics, such as threshold voltage （Vt） and sub-threshold swing （SS）, as well as the device saturated current. The PSDG MOSFET transistor leakage current （loft） can be reduced as much as 78% of the traditional single gate MOSFET. The PSDG is fabricated and fully compatible with our conventional 0.18 μm logic process flow.     

Construction of high degree resilient S-boxes with improved nonlinearity

We present a simple method to use an [n−d−1,m,t+1] code to construct an n-input, m-output, t-resilient function with degree d>m and nonlinearity ²n−1−²n−⌈(d+1)/2⌉−(m+1)²n−d−1. For any fixed values of parameters n,m,t and d, with d>m, the nonlinearity obtained by our construction is higher than the nonlinearity obtained by Cheon in Crypto 2001.