Analytical V TH and S models for (DMG–GC–stack) surrounding-gate MOSFET

This article presents an analytical model of surface potential, threshold voltage and subthreshold swing for a new structure of surrounding-gate MOSFET by combining dual-material gate, graded channel and gate stack. By comparison with published results, it is shown that the new MOSFET structure can improve the immunity of CMOS-based devices in the nanoscale regime against short-channel effects.     

Reduction of Power Fluctuation in ECMA-368 Ultra Wideband Communication Systems Using Multilayer Perceptron Neural Networks

ECMA-368 Ultra Wideband (UWB) wireless communication Standard adopts Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) technology to transmit information with high data rate (480 Mbits/s). However, the high Peak to Average Power Ratio of MB-OFDM UWB signals, limits the power efficiency of the high power amplifier due to nonlinear distortion. In order to avoid this drawback, an efficient scheme based on multilayer perceptron, artificial neural networks is proposed. The neural network is adjusted by using active constellation extension technique which provides satisfactory results. This proposed solution gives good performance compared to previously available methods with much lower complexity, without iterations, good bit error rate and no increase in transmitted signal power and bandwidth.     

对连续搅拌反应釜的变量结构观察器线性反馈控制的开发(英文)

This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors(CSTR).A variable structure observer is constructed to estimate the whole process state variables.This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors.The observer is coupled with a nonlinear controller,designed based on input-output linearization for controlling the reactor temperature.The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem.Finally,computer simulations are developed for showing the performance of the proposed approach.     

Aluminium clusters for molecular hydrogen storage and the corresponding alanes as fuel alternatives: A structural and energetic analysis

Bare and hydrogenated aluminium clusters Al_n (n = 5–7) are studied using density functional theory in order to evaluate the ability to store molecular hydrogen and to estimate the energy release upon combustion with the aim to understand these species as alternative fuel resources. Six sequential molecular hydrogenations are considered and are shown to occur without or very low activation barriers. The H₂ molecule uses its occupied σ orbital to react with an appropriate electron-deficient site of the cluster; this is generally followed by H migration leading to the favoured geometry. The combustion process produces alumina (Al₂O₃), water and a significant quantity of energy. The exothermicity seems to be largely independent of cluster size but it depends instead on the stored hydrogen quantity.     

Cooperative driving: an ant colony system for autonomous intersection management

Autonomous intersection management (AIM) is an innovative concept for directing vehicles through the intersections. AIM assumes that the vehicles negotiate the right-of-way. This assumption makes the problem of the intersection management significantly different from the usually studied ones such as the optimization of the cycle time, splits, and offsets. The main difficulty is to define a strategy that improves the traffic efficiency. Indeed, due to the fact that each vehicle is considered individually, AIM faces a combinatorial optimization problem that needs quick and efficient solutions for a real time application. This paper proposes a strategy that evacuates vehicles as soon as possible for each sequence of vehicle arrivals. The dynamic programming (DP) that gives the optimal solution is shown to be greedy. A combinatorial explosion is observed if the number of lanes rises. After evaluating the time complexity of the DP, the paper proposes an ant colony system (ACS) to solve the control problem for large number of vehicles and lanes. The complete investigation shows that the proposed ACS algorithm is robust and efficient. Experimental results obtained by the simulation of different traffic scenarios show that the AIM based on ACS outperforms the traditional traffic lights and other recent traffic control strategies.     

Application of Microprobe Analysis to the Reconstruction and Characterization of Dendritic Structures

The electron probe microanalyzer (EPMA or “microprobe”) is a powerful tool for nondestructive chemical analysis of solid materials. The work presented in this article proofs the concept of reconstructing three-dimensional (3-D) dendritic structures in steel based on 5 two-dimensional (2-D) EPMA concentration maps. The EPMA measurements are focused on the concentration distribution of Mn, which has a distinct microsegregation tendency in steel. Because the concentration maps must be taken from different depths of the investigated sample, serial sectioning of the sample is required for each microprobe measurement. These measured concentration maps are processed with a commercial software tool to smooth and to merge the maps, as well as to consider the temperature gradient that occurred during solidification on the microsegregation pattern. Afterward, the concentration maps are stored in a 3-D array, and the neighboring array entries with the same predefined threshold concentration value are connected with surfaces to build a 3-D dendritic structure. Because the concentration of certain alloying elements in the solid phase increases during the solidification process, it is possible to visualize the dendritic growth by increasing the solid fraction. Finally, a simple correlation was used to relate the specific surface area to the solid volume fraction of the dendrites. The obtained 3-D structures can be used for subsequent investigations in finite-element (FE) or computational fluid dynamics (CFD) simulation tools.     

Successive Spray Deposition of P3HT/PCBM Organic Photoactive Layers: Material Composition and Device Characteristics

Controlling the active layer composition in organic electronic devices represents one of the major challenges in their fabrication. In particular, the composition of mixed donor/acceptor active layers for photosensitive device applications is known to strongly influence device performance. Here, an alternative approach for the preparation of organic heterojunction photoactive layers by successive spray deposition of the donor material, poly(3‐hexylthiophene) (P3HT), and acceptor material, [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM), is reported. Optical absorption spectra, X‐ray reflectivity, and cross‐sectional transmission electron microscopy investigations are used to indicate the penetration of PCBM into a previously deposited P3HT layer and the spontaneous formation of a bulk heterojunction (BHJ) within the active layer, which provides the large interfacial area needed for efficient exciton dissociation. It is shown that organic photodiodes composed of photoactive layers prepared using this fabrication method exhibit a performance comparable to conventional BHJ devices in which the active layer is rigorously blended in advance. Moreover, separate handling of the individual materials and their deposition from distinct solutions enables an enhanced control of the active layer composition and hence increases the ability of tuning device characteristics.     

Stability,magnetic, electronic,elastic, thermodynamic,optical, and thermoelectric properties of Co2TiSn,Co2ZrSn and Co2HfSn Heusler alloys from calculations using generalized gradient approximation techniques

Structural, magnetic, electronic, elastic, thermodynamic, optical, and thermoelectric properties of full-Heusler alloys Co₂YSn (Y?=?Ti; Zr; Hf) were determined using density functional theory-based WIEN2k code within GGA and GGA?+?U approximations for exchange correlation functions. The calculated formation energies and elastic parameters demonstrate the stability of these alloys. It was also observed that the studied compounds have a ductile structure and exhibit anisotropic behavior. The magnetic moment of these systems is equal to 2 μ_B, which conforms to the Slater–Pauling rule. In addition, the half-metallic ferrimagnetic behavior and good bandgap in the minority spin are showed for all compounds. The optical properties are systematically studied by computing the optical parameters. The existence of bandgaps with minimal energy loss in IR and visible regions makes these materials suitable candidates for optoelectronic devices. The thermoelectric properties of these systems were also examined in terms of temperature and chemical potential.

     

A blind digital audio watermarking scheme based on EMD and UISA techniques

In this paper, a new perceptual spread spectrum audio watermarking scheme is discussed. The watermark embedding process is performed in the Empirical Mode Decomposition (EMD) domain, and the hybrid watermark extraction process is based on the combination of EMD and ISA (Independent Subspace Analysis) techniques, followed by the generic detection system, i.e. inverse perceptual filter, predictor filter and correlation based detector. Since the EMD decomposes the audio signal into several oscillating components–the intrinsic mode functions (IMF)–the watermark information can be inserted in more than one IMF, using spread spectrum modulation, allowing hence the increase of the insertion capacity. The imperceptibility of the inserted data is ensured by the use of a psychoacoustical model. The blind extraction of the watermark signal, from the received watermarked audio, consists in the separation of the watermark from the IMFs of the received audio signal. The separation is achieved by a new proposed under-determined ISA method, here referred to as UISA. The proposed hybrid watermarking system was applied to the SQAM (Sound Quality Assessment Material) audio database (Available at http://sound.media.mit.edu/mpeg4/audio/sqam/) and proved to have efficient detection performances in terms of Bit Error Rate (BER) compared to a generic perceptual spread spectrum watermarking system. The perceptual quality of the watermarked audio was objectively assessed using the PEMO-Q (Tool for objective perceptual assessment of audio quality) algorithm. Also, using our technique, we can extract the different watermarks without using any information of original signal or the inserted watermark. Experimental results exhibit that the transparency and high robustness of the watermarked audio can be achieved simultaneously with a substantial increase of the amount of information transmitted. A reliability of 1.8 10^???4 (against 1.5 10^???2 for the generic system), for a bit rate of 400 bits/s, can be achieved when the channel is not disturbed.