Probabilistic optimization for FPGA board level routing problems

Field programmable gate arrays (FPGAs) are an enabling technology in circuit designs. We consider the board-level multi-terminal net assignment in the FPGA-based logic emulation. A novel probabilistic optimization method is devised for solving the net assignment problem. The approach incorporates randomized rounding, genetic algorithm, and solution-improvement strategies. Experimental results demonstrate promising performance.     

Vapor‐Based Multicomponent Coatings for Antifouling and Biofunctional Synergic Modifications

A general concept is introduced featuring an ideal multifunctional surface that can avoid fouling problems while allowing the installed groups to perform with the high efficacy and accuracy necessary for delivering cascading and spontaneous biological activities. The idea is realized by using a direct synthesis of a multicomponent coating containing the two functionalities of 4‐methyl‐propiolate and 4‐N‐maleimidomethyl that is achieved via chemical vapor deposition copolymerization on various substrates. The novel coating can simultaneously perform specific bio‐orthogonal reactions, including the azide‐alkyne click reaction and a thiol‐maleimide coupling reaction. In the study, azide‐terminated polyethylene glycols are first immobilized on the methyl propiolate groups to impart an antifouling property, while bioactivity is enabled by tethering biotinylated thiols or Cys‐Arg‐Glu‐Asp‐Val (CREDV) peptides on the maleimide groups. The induced antifouling properties and bioactivities are confirmed by quartz crystal microbalance and cell culture studies. Finally, precisely manipulated endothelial cells, namely, human umbilical vein endothelial cells and bovine arterial endothelial cells, are observed on a complex stent substrate and on confined areas of the poly(methyl methacrylate) substrates.     

Privacy‐preserving multireceiver ID‐based encryption with provable security

Multireceiver identity (ID) based encryption and ID‐based broadcast encryption allow a sender to use the public identities of multiple receivers to encrypt messages so that only the selected receivers or a privileged set of users can decrypt the messages. It can be used for many practical applications such as digital content distribution, pay‐per‐view and multicast communication. For protecting the privacy of receivers or providing receiver anonymity, several privacy‐preserving (or anonymous) multireceiver ID‐based encryption and ID‐based broadcast encryption schemes were recently proposed, in which receiver anonymity means that nobody (including any selected receiver), except the sender, knows who the other selected receivers are. However, security incompleteness or flaws were found in these schemes. In this paper, we propose a new privacy‐preserving multireceiver ID‐based encryption scheme with provable security. We formally prove that the proposed scheme is semantically secure for confidentiality and receiver anonymity. Compared with the previously proposed anonymous multireceiver ID‐based encryption and ID‐based broadcast encryption schemes, the proposed scheme has better performance and robust security. Copyright © 2012 John Wiley & Sons, Ltd.     

Geometrical Effects on the Performance of Coaxial-Waveguide Gyrotron Traveling-Wave Amplifiers

This theoretical investigation examines the feasibility of improving the stability of the coaxial-waveguide gyrotron traveling-wave tube (gyro-TWT) by selecting the geometrical parameter C, i.e., the ratio of the outer radius to the inner radius. The effects of the geometrical parameter C on the start-oscillation currents of oscillation modes are analyzed to determine the optimum operating conditions. Simulation results indicate that the coaxial gyro-TWT with distributed wall losses can be stably operated at a higher beam current by optimizing C. Additionally, the saturated behaviors of the operating TE₀₁ mode are evaluated for several C values to investigate the geometrical effects on the amplification of the coaxial gyro-TWT. Moreover, performance of the fundamental harmonic coaxial gyro-TWT achieved with the optimized C value is predicted under stable operating conditions.     

HfAlON n-MOSFETs incorporating low-work function gate using ytterbium silicide

The authors have fabricated low-temperature fully silicided YbSi/sub 2-x/-gated n-MOSFETs that used an HfAlON gate dielectric with a 1.7-nm EOT. After a 600 /spl deg/C rapid thermal annealing, these devices displayed an effective work function of 4.1 eV and a peak electron mobility of 180 cm/sup 2//V/spl middot/s. They have additional merit of a process compatible with current very large scale integration fabrication lines.     

A comparison of different paging mechanisms for mobile IP

This paper proposes two Individual paging schemes, then presents a comparative analysis on the signaling cost functions of Mobile IP (MIP) with different paging protocols and paging schemes and investigates constructing optimal paging areas using discrete system model as a mobility model. In wireless mobile Internet, mobile hosts often visit foreign networks that might be far away from their home networks and the occurrences of their inter-domain movement are relatively rare. In this scenario, our analytical results show that paging, particularly individual paging, can significantly improve the total signaling cost of MIP. We show that Domain paging can bring about considerable cost saving compared to FA (Foreign Agent) paging. Our results also demonstrate the significant advantages of Individual Paging over Static Aggregate Paging. The results show that specifying the optimal paging area size is critical in saving signaling cost of MIP with paging support. Hung Tuan Do received the B.E. degree in Electrical Engineeing and Computer Science from Hanoi University of Technology, Vietnam, and the M.E. and the Ph.D. both from Gunma University, Japan. His research interests include Mobility Management, Wireless Internet and Mobile Ad hoc Networks. Yoshikuni Onozato is a Professor with Gunma University. His research interests are in satellite systems, computer communication networks and distributed computing systems and span the entire spectrum from the design and performance evaluation of these systems to their implementation. He is a member of IEEE, ACM, IPSJ, ORSJ and IEICE.     

Solution‐Processed HafSOx and ZircSOx Inorganic Thin‐Film Dielectrics and Nanolaminates

New thin‐film dielectrics and nanolaminates have been synthesized via aqueous‐solution deposition of Hf and Zr sulfates, where facile gelation and vitrification of the precursor solution have been achieved without organic additives. X‐ray reflectivity, imaging, and metal‐insulator‐metal capacitor performance reveal that smooth, atomically dense films are readily produced by spin coating and modest thermal treatment (T < 325 °C). Dielectric characteristics include permittivities covering the range of 9–12 with breakdown fields up to 6 MV cm^–1. Performance as gate dielectrics is demonstrated in field‐effect transistors exhibiting small gate‐leakage currents and qualitatively ideal device performance. The low‐temperature processing, uniformity, and pore‐free nature of the films have also allowed construction of unique, high‐resolution nanolaminates exhibiting individual layers as thin as 3 nm.     

Design of node configuration for all-optical multi-fiber networks

It is cost-effective to install multiple fibers in each link of an all-optical network, because the cost of fibers is relatively low compared with the installation cost. The resulting network can provide a large capacity for good quality of service, future growth, and fault tolerance. If a node has more incoming/outgoing fibers, it requires larger optical switches. Using the current photonic technology, it is difficult to realize large optical switches. Even if they can be realized, they are expensive. To overcome this problem, we design a node configuration for all-optical networks. We exploit the flexibility that, to establish a lightpath across a node, we can select any one of the available channels in the incoming link and any one of the available channels in the outgoing link. As a result, the proposed node configuration requires significantly smaller optical switches while it can result in nearly the same blocking probability as the existing one. We demonstrate that a good network design is to adopt the proposed node configuration and slightly more fibers in each link, so that the network requires small optical switches while it has a small blocking probability     

Tunable Band‐Selective UV‐Photodetectors by 3D Self‐Assembly of Heterogeneous Nanoparticle Networks

Accurate detection of ultraviolet radiation is critical to many technologies including wearable devices for skin cancer prevention, optical communication systems, and missile launch detection. Here, a nanoscale architecture is presented for band‐selective UV‐photodetectors, which features unique tunability and miniaturization potential. The device layout relies on the 3D integration of ultraporous layers of tailored nanoparticles. By tailoring the transmittance window between the indirect band gap of TiO₂ nanoparticles and the sharp edge of the direct band gap of ZnO, a band‐selective photoresponse is achieved with tunable bandwidth to less than 30 nm and photo‐ to dark‐current ratios of several millions at a light intensity of 86 μW cm^?2 and operation bias of 1 V. The potential of this integrated morphology is shown by fabrication of the first inherent UVA photodetector with selectivity against the edge of the UVB and visible light of nearly 60 times. This tunable architecture and nanofabrication approach are compatible with state‐of‐the micromachining technologies and provide a flexible solution for the engineering of wearable band‐selective photodetectors.     

Effective Work Function Engineering of TaxCy Metal Gate on Hf-Based Dielectrics

This letter reports the engineering of effective work function (EWF) for tantalum carbide (TaC) metal gate on high-k gate dielectrics. The dependence of EWF on Si concentration in HfSiO as well as nitridation techniques is revealed. The EWF was extracted by both terraced oxide and terraced high-k techniques with the bulk and interface charges taken into account. The incorporation of Si in Hf-based dielectrics results in an increase of EWF, while the presence of N tends to decrease the EWF. Plasma nitridation is found to be more effective in lowering the EWF than a thermal nitridation. The phenomena can be explained by the modification of TaC/high-k interface dipole moment, which arises from the electronegativity difference for various interface bonds. Based on the above findings, we proposed a novel approach to reduce the EWF of TaC on HfSiON by using a thin HfO₂ cap layer after optimizing the nitridation. The MOSFET results show that this technique is able to achieve a lower V_t without degrading the device performance