Secure Handover Authentication Protocol Based on Bilinear Pairings

Handover authentication protocol enables a mobile node to switch from one base station to another without loss or interruption of service when the node exits the transmission area of his or her current base station. This paper proposes a secure prime-order handover authentication protocol based on bilinear pairings. The proposed protocol adapts the concept of pseudonyms to provide user anonymity and user unlinkability. It withstands well-known security threats and achieves mutual authentication, user unlinkability. A batch signature verification mechanism to verify a mass of signatures is presented in our scheme. We also prove that our scheme is secure under random oracle.     

Mixed Broadcast Techniques of Leisure Information in Vehicular Ad-Hoc Networks

Telecommunication Systems - Vehicle-to-vehicle communication and probabilistic broadcast are important means for information dissemination in vehicular ad-hoc networks (VANETs). In contrast to...     

Nanoporous platinum counter electrodes by glancing angle deposition for dye-sensitized solar cells

We report an effective way to produce nanoporous Pt counter electrodes of dye-sensitized solar cells by the glancing-angle deposition (GLAD) technique. By controlling the orientation of the substrate relative to the incident Pt vapor flux during the deposition, nanoporous films composed of inclined nm-scale columns were produced through the self-shadowing effect. Pt counter electrodes having varied nanoporous structures were characterized for their morphological and electrochemical properties, and were subjected to device studies to establish the correlation with DSSC characteristics/performances. The results suggest that the nanoporous GLAD Pt electrodes can effectively enhance active surface areas, the catalytic ability and charge exchange at the Pt/electrolyte interface of a DSSC. As a result, the quantum efficiency, short-circuit current, and power conversion efficiency of the DSSC can be enhanced by up to 12–13% with using the nanoporous GLAD Pt counter electrodes.     

Understanding the relationship between intensity and gratifications of Facebook use among adolescents and young adults

Facebook is a well-known computer-mediated communication platform considered popular among adolescents and young adults. New media scholars have coined the term “intensity of Facebook use” (IFU) for the concept that measures the emotional and affective attitude towards Facebook use among young people. IFU is an important service use concept that has been positively linked with the different psychosocial outcomes of student well-being. However, only a limited amount of the prior literature has investigated the relationship between IFU and different Facebook uses and gratifications (U&G). The existing literature suggests inconsistent findings with a sole emphasis on young adults. To address these gaps, the present study has investigated the differential role of different Facebook U&G among adolescents and young adults in predicting IFU. A total of three cross-sectional data sets (N = 373, 107, 105) represented adolescents and university-attending young-adult Facebook users. The study results suggest that process U&G do and content U&G do not play any significant role in predicting IFU. Adolescents and young adults differ in their sought Facebook U&G. In addition to this, cultural differences were observed in the sought Facebook U&G and their differential role in predicting IFU.     

Characterization and modeling of static and cyclic relaxation in nonconductive adhesives

Adhesive interconnections are considered to be attractive alternatives to lead or lead-free solder interconnects because of their lower processing temperatures and extendability to fine pitch applications. However, reliability issues, such as moisture-induced delamination and viscoelastic relaxation of the adhesive in both steady-state and cyclic loading, continue to pose a challenge to widespread implementation. To date, the static and cyclic relaxation characteristics of nonconductive adhesives (NCAs) are yet to be understood. This paper attempts to provide insights into this static and cyclic relaxation behavior through experimental characterization and modeling. The viscoelastic property of a typical NCA material was characterized, and a simulation program with integrated circuit emphasis (SPICE) modeling program was used to model the cyclic relaxation behavior. The modeling results were successfully validated with a series of experiments. This showed that cyclic relaxation of the adhesive can be successfully modeled using linear-viscoelastic property. The phenomenon of slower relaxation of the adhesive under cyclic loading than that in static loading suggests that accelerated reliability testing used in solder-joint fatigue durability investigations may not be directly applicable to the adhesive interconnections. A rework methodology applicable to adhesive interconnects using cyclic loading has also been proposed.     

Electrodeposition of CuIn1−xGaxSe2 solar cells with a periodically-textured surface for efficient light collection

The photoresponse of CuIn_1?xGa_xSe₂ (CIGS) solar cells is improved using a periodically-textured structure as an antireflection layer. The CIGS absorber layers were prepared by one-step electrodeposition from an aqueous solution containing 12 mM CuSO₄, 25 mM In₂(SO₄)₃, 28 mM Ga₂(SO₄)₃, and 25 mM SeO₂. The electrodeposited CIGS films exhibit the (112)-preferred orientation of the chalcopyrite structures and feature improved film stoichiometry after the selenization process. In addition, the lower bandgap value of 0.97 eV is caused by the discrepancy of the reduction potentials for each constituent, resulting in insufficient Ga content in the deposited films. Using self-assembled silica nanoparticles as the etching mask, periodically-textured structures can be easily formed on an indium tin oxide (ITO)-coated soda lime glass to achieve a low average reflection (<10.5%) in a wide wavelength and incident angle range. With the periodic textured structures suppressing light reflections from the front surface, the photogenerated current in the semi-transparent CIGS solar cells made with transparent conducting electrodes is 1.82 times higher than they otherwise would be.     

Novel multilayered Ti/TiN diffusion barrier for Al metallization

A novel, multilayered Ti/TiN diffusion barrier is proposed and successfully applied for Al metallization. The multilayered Ti/TiN structure is effective in enhancing the barrier properties since the very thin Ti layer inserted into titanium nitride (TiN) barrier can cause disruption of the TiN columnar growth and reduction of open grain boundaries resulting in retarded interdiffusion between metal and silicon. Multilayered Ti/TiN films are deposited sequentially by sputtering without breaking vacuum. It is found that TiN grain boundaries are discontinuous when a Ti layer is inserted into TiN. Multilayered Ti/TiN has a better barrier performance than single-layer TiN in Al metallization. However, the barrier performance is related to the number and thickness of the inserted Ti layers, because increasing titanium will enhance chemical reactions between Al and barrier layers, and produce more titanium-aluminum compounds. The total thickness of introduced Ti layers should be reduced to improve barrier performance.     

Broad-band MMICs based on modified loss-compensation method using 0.35-/spl mu/m SiGe BiCMOS technology

Using the concept of loss compensation, novel broad-band monolithic microwave integrated circuits (MMICs), including an amplifier and an analog multiplier/mixer, with LC ladder matching networks in a commercial 0.35-mum SiGe BiCMOS technology are demonstrated for the first time. An HBT two-stage cascade single-stage distributed amplifier (2-CSSDA) using the modified loss-compensation technique is presented. It demonstrates a small-signal gain of better than 15 dB from dc to 28 GHz (gain-bandwidth product=157 GHz) with a low power consumption of 48 mW and a miniature chip size of 0.63 mm² including testing pads. The gain-bandwidth product of the modified loss-compensated CSSDA is improved approximately 68% compared with the conventional attenuation-compensation technique. The wide-band amplifier achieves a high gain-bandwidth product with the lowest power consumption and smallest chip size. The broad-band mixer designed using a Gilbert cell with the modified loss-compensation technique achieves a measured power conversion gain of 19 dB with a 3-dB bandwidth from 0.1 to 23 GHz, which is the highest gain-bandwidth product of operation among previously reported MMIC mixers. As an analog multiplier, the measured sensitivity is better than 3000 V/W from 0.1 to 25 GHz, and the measured low-frequency noise floor and corner frequency can be estimated to be 20 nV/sqrt(Hz) and 1.2 kHz, respectively. The mixer performance represents state-of-the-art result of the MMIC broad-band mixers using commercial silicon-based technologies     

Image steganographic scheme based on pixel-value differencing and LSB replacement methods

In order to improve the capacity of the hidden secret data and to provide an imperceptible stego-image quality, a novel steganographic method based on least-significant-bit (LSB) replacement and pixel-value differencing (PVD) method is presented. First, a different value from two consecutive pixels by utilising the PVD method is obtained. A small difference value can be located on a smooth area and the large one is located on an edged area. In the smooth areas, the secret data is hidden into the cover image by LSB method while using the PVD method in the edged areas. Because the range width is variable, and the area in which the secret data is concealed by LSB or PVD method are hard to guess, the security level is the same as that of a single using the PVD method of the proposed method. From the experimental results, compared with the PVD method being used alone, the proposed method can hide a much larger information and maintains a good visual quality of stego-image.     

Fabrication of antireflection structures on TCO film for reflective liquid crystal display

The cholesteric liquid crystals display (ChLCD) is one kind of reflective liquid crystal display, the antireflective layer on its transparent conduction oxides (TCO) film is needed for good contrast and color performance. In this study, the finite difference time domain (FDTD) simulation and nanoimprinting fabrication of AR structures on the TCO film are developed. Finally, the reflectance of AR structures on TCO film is just half of the original film, and this result is useful for the reflective ChLCD product commercialized in the future.