Stronger Security Proofs for RSA and Rabin Bits

The RSA and Rabin encryption functions are respectively defined as E _N (x) = x ^e mod N and E _N (x) = x ² mod N , where N is a product of two large random primes p , q and e is relatively prime to φ (N) . We present a simpler and tighter proof of the result of Alexi et al. [ACGS] that the following problems are equivalent by probabilistic polynomial time reductions: (1) given E _N (x) find x; (2) given E _N (x) predict the least-significant bit of x with success probability 1/2 + 1/poly(n) , where N has n bits. The new proof consists of a more efficient algorithm for inverting the RSA/ Rabin function with the help of an oracle that predicts the least-significant bit of x . It yields provable security guarantees for RSA message bits and for the RSA random number generator for modules N of practical size. Received 12 July 1996 and revised 8 January 1999     

Investigation of the Mθ/G/1/m system with service regime switchings and threshold blocking of the input flow

The M^θ/G/1/m queueing system with the group arrival of customers, switchings of service regimes, and threshold blocking of the flow of customers is studied. The input flow is blocked if, at the instant of the successive customer service start, the number of customers in the system exceeds specified threshold level h. If, at instant t of the customer service start, number of customers in the system ξ(t) satisfies the condition h_i < x(t) \leqslant h_{i + 1} (i = [`(1,r)] )h_i < \xi (t) \leqslant h_{i + 1} (i = \overline {1,r} ), then the service time for this customer corresponds to distribution function F _i (t). At 1 ≤ ξ(t) ≤ h = h ₁, the service time for a customer is distributed according to law F(t) (basic service time). The Laplace transforms for the distribution of the number of customers in the system on the busy period and for the distribution function of the busy period are found, the mean length of the busy period (including the case m = ∞) is determined and formulas for the ergodic distribution of the number of customers in the system (including the case m = ∞) are obtained. An effective algorithm for calculation of the ergodic distribution is proposed. The recurrence relations of the algorithm are not explicitly dependent on m.     

Detailed study about influence of oxygen on trap properties in SiOxNy by the thermally stimulated current and maximum entropy method

The trap amount depending on trap energy levels [N_t(E_t)] in various silicon oxynitride films were investigated. Using the thermally stimulated current and the maximum entropy method, we determined N_t(E_t) with very high energy resolution. In N_t(E_t), many E_t were observed between 1.2 and 1.6 eV. Interestingly, their amounts significantly depended on the film compositions. The influence of oxygen on N_t(E_t) is also discussed.     

Space-charge-limited currents in insulators containing traps distributed in energy

The transition from the ohmic current to space-charge-limited current (SCLC) strongly depends on the presence of traps in insulators. Generally these traps are not localized at a single energy, rather they are distributed in energy. To account for the effect of the distribution of traps around a single energy, say E_t, on SCLC, we propose a new distribution which broadly encompasses all the characteristics of the Gaussian distribution and at the same time is amenable to usual methods of analysis. The proposed distribution function is

$\text{N}{}^{\mathrm{E}}\text{= N}{}^0\text{exp}\text{[(E?E}{}^{\mathrm{t}}\text{)/kT}{}^{\mathrm{t}}\text{]}\text{{exp[(E?E}{}^{\mathrm{t}}\text{)/kT}{}^{\mathrm{t}}\text{+1}}{}_2$

where T_t is the characteristic temperature of the distribution. Applying the Regional Approximation Method the current-voltage characteristics for shallow as well as deep traps are obtained with the proposed distribution.     

Sur une méthode de A. Papoulis,pour l’extrapolation d’un signal

Let: Cbe a set, x a function of t ∈ C, Ea subset of C, x_E the restriction of x to E;it is particularly important to look for nontrivial cases, where the data (C, E, x_E)completely determines the a priori unknown x. A. Papoulis has discovered a case of this kind resulting in an algorithm for extrapolating; he suggests to utilize the latter for signals with finite total energy and limited bandwidth. The author introduces this algorithm in the theory of spaces with reproducing kernels; he examines the particular case where these spaces are imbedded in a L₂-space and discusses possibility of application to signals with finite total energy and limited bandwidth.     

高低频不同电压条件下腔室内CCP冷等离子体源的仿真分析

等离子体的状态的变化特征,特别是在双频情况下,是PECVD工艺设备的一项重要指标,这促使人们用不同的方法对它们进行研究。本文使用CFD-ACE 商业软件建立了二维流体模型对N2等离子体进行仿真。首先在高频13.56MHz,高频电压300V,低频电压0V的条件下描述了等离子体,特别是在鞘层部位的电势、电子数量密度、氮自由基和电子温度,分布的基本特征。在此基础上,讨论了高频电压分别是200V,300V,400V时及低频0.3MHz,低频电压分别是500V,600V,700V时对等离子体密度的影响。结论表明,在电极表面形成了约3mm厚的鞘层,在鞘层内电势和电子温度随时间和空间变化较大,而在非鞘层区域内电势跟随电极电压的变化而变化,但几乎不随空间变化,电子温度也只在很小的范围内变化。氮自由基的数量密度也受射频电压的调制,但相对变化很小。等离子体密度仅在鞘层区域内随时间发生变化,所以通过比较主等离子体区参数可以看出,等离子体的密度随着高频电压升高,随低频电压的升高略有下降,同时x方向和y方向的均匀性将会发生变化。因此,在其他条件不变的情况下需要选择合适的高低频电压来获得高密度和均匀性均合乎要求的等离子体。     

High-Speed Array Multipliers Based on On-the-Fly Conversion

A new on-the-fly conversion algorithm is proposed, and high-speed array multipliers with the on-the-fly conversion are presented. The new on-the-fly conversion logic is used to speed up carry-propagate addition at the last stage of multiplication, and provides constant delay independent of the number of input bits. In this paper, the multiplication architecture and the on-the-fly conversion algorithm are presented and discussed in detail. The proposed architecture has multiplication time of (n + 1)t_FA, where n is the number of input bits and t_FA is the delay of a full adder. According to our comparative performance evaluation, the proposed architecture has shorter delay and requires less area than the conventional array multiplier with on-the-fly conversion.     

Low frequency noise characterization in 0.13 μm p-MOSFETs. Impact of scaled-down 0.25, 0.18 and 0.13 μm technologies on 1/f noise

This paper presents an experimental analysis of the noise measurements performed in 0.13 μm technology p-MOS transistors operating from weak to strong inversion in ohmic and saturation regimes. The 1/f noise origin is interpreted in terms of carrier number with correlated mobility fluctuations. The contribution of the access resistance noise is noticed for large overdrive voltages. The slow oxide trap density N_t(E_F) and the Coulomb scattering noise parameter α_s have been extracted. Then the 1/f noise level in the three scaled-down p-MOSFETs generations (0.25, 0.18 and 0.13 μm) is compared. The variation of the noise parameter values is discussed with respect to the technology node. The highest oxide trap density is obtained for the thinnest gate oxide. It is concluded that the oxide thinning should lead to noise reduction only if the product t_ox². N_t is taken into consideration. This trend will be significant in future scaled-down MOSFETs.     

A Distributed Algorithm for Dynamic Channel Allocation

Recent demand for mobile telephone service has been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remains limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraint between adjacent channels in the spectrum. Channel allocation schemes provide a flexible and efficient access to bandwidth in wireless and mobile communication systems. In this paper, we present an efficient distributed algorithm for dynamic channel allocation based upon mutual exclusion model, where the channels are grouped by the number of cells in a cluster and each group of channels cannot be shared concurrently within the cluster. We discuss the algorithm and prove its correctness. We also show that the algorithm requires at most (worst case) O(N _gN _n logN _n) messages, where N _g is the number of groups and N _n is the number of neighbors. This is compared to Choy's algorithm which requires O(N _g ²N _n), where N _g is the number of groups and N _n is the number of neighboring cells in the system. We report our algorithm's performance with several channel systems using different types of call arrival patterns. Our results indicate that significant low denial rate, low message complexity and low acquisition time can be obtained using our algorithm.     

Reliability of ultrathin nitrided oxides grown in low pressure N2O ambient

The influence of N₂O oxynitridation and oxidation pressure on reliability of ultrathin gate oxides from 4 down to 2.5 nm thickness was investigated. A set of different oxidation parameters was applied during oxide growth which comprised oxidation pressure and N₂O partial pressure during rapid thermal oxidation. The reliability of the oxides was tested by constant voltage stress. Evaluation of the resulting times to soft breakdown (t_sbd) for different stress voltages allows to predict a supply (gate) voltage V^10y,max providing an oxide lifetime of 10 years. For this extrapolation, t_sbd was assumed to increase exponentially as stress voltage is reduced. The slope of the extrapolation is found to become steeper as oxides become thinner, which implies higher V^10y,max and thus higher reliability for thinner oxides as under an assumption of a uniform slope for all thicknesses. Further, the results of this extrapolation demonstrate that oxidation in N₂O containing ambient can improve oxide reliability for ultrathin gate oxides.     

On the recombination of electrons and holes at traps with finite relaxation time

Shockley and Read[1] and Hall[2] (SRH) theory for electron hole recombination at traps is modified to include the effect of a finite time of relaxation before the captured electron or hole settles to the ground state. The modified expression for the recombination rate retains all the essential features of SRH theory and includes two additional effects: at low levels of injection lifetime shows a temperature dependence of the type τ = τ_n0+C_ne^?ΔE_n/kT and at high injection the recombination rate saturates at an upper value N_t/δt where δt is relaxation time and N_t is density of traps.     

Stationary characteristics of the Mθ/G/1/m system with the threshold functioning strategy

The M^θ/G/1 queueing system with the group arrival of customers, switchings of service regimes, and threshold blocking of the flow of customers is considered. The input flow is blocked if, at the instant of the beginning of the service of a successive customer, the number of customers in the system exceeds given threshold level h. If, at instant t of the beginning of the service of the customer, the number of customers in the system satisfies the condition h _i < ɛ(t) ≤ h _{i + 1} h_i < e(t) \leqslant h_{i + 1} (i = [`(1,r)] )h_i < \varepsilon (t) \leqslant h_{i + 1} (i = \overline {1,r} ), then, the service time of this customer is associated with distribution function F _i (t). When 1 ≤ ɛ(t) ≤ h = h ₁, the service time of the customer is distributed according to law F(t) (the basic service regime). For the case of a single switching (r = 1), the mean duration of the busy period intervals with the absence and presence of the input flow blocking, the probability of customer service, and the stationary characteristics of the queue are determined. The character of the dependences of the mean busy period duration and the probability of service on parameters m and h is investigated. For the case m = ∞, some problems of optimal synthesis of systems with given characteristics and the problem of minimization of the service cost are solved.     

A genetic algorithm for reliability-oriented task assignment with k/spl tilde/ duplications in distributed systems

A distributed system is a collection of processor-memory pairs connected by communication links. The reliability of a distributed system can be expressed using the distributed program reliability, and distributed system reliability analysis. The computing reliability of a distributed system is an NP-hard problem. The distribution of programs & data-files can affect the system reliability. The reliability-oriented task assignment problem, which is NP-hard, is to find a task distribution such that the program reliability or system reliability is maximized. For example, efficient allocation of channels to the different cells can greatly improve the overall network throughput, in terms of the number of calls successfully supported. This paper presents a genetic algorithm-based reliability-oriented task assignment methodology (GAROTA) for computing the k/spl tilde/-DTA reliability problem. The proposed algorithm uses a genetic algorithm to select a program & file assignment set that is maximal, or nearly maximal, with respect to system reliability. Our numerical results show that the proposed algorithm may obtain the exact solution in most cases, and the computation time seems to be significantly shorter than that needed for the exhaustive method. When the proposed method fails to give an exact solution, the deviation from the exact solution is very small. The technique presented in this paper would be helpful for readers to understand the correlation between task assignment reliability, and distributed system topology.     

Optimum Linear Constellation Precoding for Space Time Wireless Systems

Space Time Constellation Rotating Codes (STCRs) achieve a rate of 1 symbol/s/Hz and enjoy a diversity N _tN_r for arbitrary number of transmit and receive antennas N _t and N _r over quasi static fading channels. Optimum Unitary STCRs based on Algebraic design tools, which achieve the upper bound on coding gain for all linear precoders over Quadrature Amplitude Modulation (QAM) and Pulse Amplitude Modulation (PAM), are known only when the number of transmit antennas is power of two. In this paper we design optimum unitary LCPs for even number of transmit antennas. We also present some unitary precoders for odd number of transmit antennas which clearly out-perform the existing unitary non-optimum precoders. Performance results corroborate our analysis. Manav R. Bhatnagar was born in Moradabad, India in 1976. He did his B.E. in Electronics in 1997 and Master of Technology in Communications Engineering in 2005 from Indian Institute of Technology Delhi, India. He has worked as lecturer in Moradabad Institute of Technology, Moradabad, India from 1998--2003. He is currently pursuing PhD from Indian Institute of Technology Delhi, India. His research interests include Routing in Optical Networks, Signal Processing in Wireless Communications and Image Processing. He is a member of the IEEE. R Vishwanath was born in Hyderabad, India in 1982. He did his B.E. in Electronics and Communications Engineering from Birla Institute of Technology, Ranchi, India in 2002 and Master of Technology in Communications Engineering in 2005 from Indian Institute of Technology Delhi, India. Currently he is pursuing PhD from Indian Institute of Technology Delhi, India. His research interests include Routing in Optical Networks, Signal Processing, Wireless Communications and Image Processing. He is a member of the IEEE.     

Time-dependent dielectric breakdown of SiO2 films in a wide electric field range

We have performed time dependent dielectric breakdown measurement of SiO₂ films in the electric field (E_OX) range 7–13.5 MV/cm and evaluated the electric field dependence of intrinsic lifetime, using both area and temperature dependences of oxide lifetime. We have evaluated the electric field dependence of time to breakdown (t_BD) below 125°C, because the activation energy of intrinsic lifetime changes at 125°C t_BD of 7.1 and 9.6 nm oxides is not proportional to exp(E_OX) but proportional to exp(1/E_OX). This suggests that the breakdown mechanism of 9.6 and 7.1 nm oxides is the same and adheres to the anode hole injection model. However, the breakdown mechanism of 4.0 nm oxides is not the same as that of 7.1 and 9.6 nm oxides. The slope of log(t_BD) versus 1/E_OX plot in 4.0 nm oxide increases with decreasing oxide fields. The intrinsic lifetime in the positive gate bias decreases with increasing oxide thicknesses in the range of electric fields employed in the present experiment.     

Study of electrically active defects in n-GaN layer

Deep level defects in both p⁺/n junctions and n-type Schottky GaN diodes are studied using the Fourier transform deep level transient spectroscopy. An electron trap level was detected in the range of energies at E_c−E_t=0.23–0.27 eV with a capture cross-section of the order of 10⁻¹⁹–10⁻¹⁶ cm² for both the p⁺/n and n-type Schottky GaN diodes. For one set of p⁺/n diodes with a structure of Au/Pt/p⁺–GaN/n–GaN/n⁺–GaN/Ti/Al/Pd/Au and the n-type Schottky diodes, two other common electron traps are found at energy positions, E_c−E_t=0.53–0.56 eV and 0.79–0.82 eV. In addition, an electron trap level with energy position at E_c−E_t=1.07 eV and a capture cross-section of σ_n=1.6×10⁻¹³ cm² are detected for the n-type Schottky diodes. This trap level has not been previously reported in the literature. For the other set of p⁺/n diodes with a structure of Au/Ni/p⁺–GaN/n–GaN/n⁺–GaN/Ti/Al/Pd/Au, a prominent minority carrier (hole) trap level was also identified with an energy position at E_t−E_v=0.85 eV and a capture cross-section of σ_n=8.1×10⁻¹⁴ cm². The 0.56 eV electron trap level observed in n-type Schottky diode and the 0.23 eV electron trap level detected in the p⁺/n diode with Ni/Au contact are attributed to the extended defects based on the observation of logarithmic capture kinetics.     

Subpicosecond Domain Switching in Discrete Regions of Pb(Zr0.35Ti0.65)O3 Thick Films

The time dependence of the domain switching current density, J_sw(t), under pulsed voltages on a ferroelectric parallel‐plate capacitor is the consequence of region‐by‐region polarization reversals across the film. As the distributive coercive voltage of domain nucleation increases from zero to the maximum applied voltage during the capacitor charging time, J_sw(t) is proportional to the domain switching speed at each time. By transforming the spatially inhomogeneous domain nucleation distribution into a temporal distribution of coercive fields (E_c), a local lnJ_sw versus E_c^?1 plot is derived for each domain, following the Merz equation. This provides insight into the independent domain switching dynamics at different nucleation sites in Pb(Zr_0.35Ti_0.65)O₃ thick films over a large current range. Although the activation field of the slope of the lnJ_sw(t) versus E_c^?1 plot varies with film area and temperature, all the plots extrapolate to a single point (J₀, E₀) from which the ultimate domain switching current density of J₀ =1.4 × 10⁸ A cm^?2 at the highest field of E₀ = 0.20‐0.25 MV cm^?1 is derived. Unexpectedly, J₀ and E₀ are independent of the film thickness and area, after correction for a small interfacial‐layer effect. This analysis provides rigorous evidence for nucleation rate‐limited domain switching with a subpicosecond nucleation time and the relative unimportance of domain forward‐growth time across film thicknesses between 0.14 and 2 μm. This work paves the way to improve the efficiency of ferroelectric thick‐film functionality in electronic and optoelectronic devices with ultrafast clock rates.     

A novel analytical model of the vertical breakdown voltage on impurity concentration in top silicon layer for SOI high voltage devices

A novel analytical model of the vertical breakdown voltage (V_{B , V} ) on impurity concentration (N_d ) in top silicon layer for silicon on insulator high voltage devices is first presented in this article. Based on an effective ionisation rate considering the multiplication of threshold energy ε_T in the electron, a new formula of silicon critical electric field E_{S , C} on N_d is derived by solving a 2D Poisson equation, which increases with the increase in N_d especially at higher impurity concentration, and reaches up to 68.8?V/µm with N_d  = 1 × 10¹⁷?cm^?3 and 157.2?V/µm with N_d  = 1 × 10¹⁸?cm^?3 from the conventional about 30?V/µm, respectively. A new physical concept of critical energy ε_B is introduced to explain the mechanism of variable high E_{S , C} with heavy impurity concentration. From the E_{S , C} , the expression of V_{B , V} is obtained, which is improved with the increasing N_d due to the enhanced E_{S , C}. V_{B , V} with a dielectric buried layer thickness (t_I ) of 2?µm increases from 428?V of 1 × 10¹⁷?cm^?3 to 951?V of 1 × 10¹⁸?cm^?3. The dependence of N_d and top silicon layer thickness (t_S ) for an optimised device is discussed. 2D simulations and some experimental results are in good agreement with the analytical results.     

Outage performance of orthogonal space–time block code transmission in opportunistic decode‐and‐forward cooperative networks

Outage performance is analyzed for opportunistic decode‐and‐forward cooperative networks employing orthogonal space–time block codes. The closed‐form expressions of diversity order and the end‐to‐end outage probability at high signal‐to‐noise ratio regime are derived for arbitrary relay number (K) and antenna configuration (N antennas at the source and each relay, N_D antennas at the destination) under independent but not necessarily identical Rayleigh fading channels. The analysis is carried out in terms of the availability of the direct link between the source and the destination. It is demonstrated that the diversity order is min{N, N_D} ⋅ KN if the direct link is blocked, and if the direct link is available, the diversity order becomes min{N, N_D} ⋅ KN + NN_D. Simulation and numerical results verify the analysis well. Copyright © 2011 John Wiley & Sons, Ltd.     

A New Paradigm for Materials Discovery: Heuristics‐Assisted Combinatorial Chemistry Involving Parameterization of Material Novelty

The combinatorial chemistry (combi‐chem) of inorganic functional materials has not yet led to the discovery of commercially interesting materials, in contrast to the many successful discoveries of heterogeneous catalysts leading to commercialization. Novel materials for practical use are likely hidden in the multicompositional search space that contains an infinite number of possible stoichiometries, as well as a large number of well‐known materials. To discover new, inorganic luminescent materials (phosphors) from the SrO‐CaO‐BaO‐La₂O₃‐Y₂O₃‐Si₃N₄‐Eu₂O₃ search space, heuristics optimization strategies, such as the non‐dominated‐sorting genetic algorithm (NSGA) and particle swarm optimization (PSO) are coupled with high‐throughput experimentation (HTE) in such a manner that the experimental evaluation of fitness functions for the NSGA and PSO is accomplished by the HTE. The proposed strategy also involves the parameterization of the material novelty to avoid systematically a futile convergence on well‐known, already‐established materials. Although the process starts with random compositions, we finally converge on a novel, single‐phase, yellow‐green‐emitting luminescent material, La_4–xCa_xSi₁₂O_3+xN_18?x:Eu²⁺, that has strong potential for practical use in white light‐emitting diodes (WLEDs).