A Steganography-Based Optical Image Encryption System Using RGB Channel Integration

An optical image encryption system with adaptive steganography using red, green, and blue (RGB) channel integration is proposed. The optical image encryption system employs a double random phase encoding algorithm to encrypt and decrypt color images. The RGB channel in a color image is first integrated into a large grayscale image. Then the integrated image is encrypted by two random phase masks. The secret data is then embedded into the encrypted image with a specific hiding sequence generated by the zero-LSB (least significant bits) sorting technique which is a content-dependent and low distortion data embedding method. Experimental results show that the proposed method has a good performance in both hiding capacity and decrypted image quality.     

Engineering a Nanoscale Al‐MOF‐Armored Antigen Carried by a “Trojan Horse”‐Like Platform for Oral Vaccination to Induce Potent and Long‐Lasting Immunity

Vaccination via the oral administration of an antigen faces many challenges, including gastrointestinal (GI) proteolysis and mucosal barriers. To limit GI proteolysis, a biomimetically mineralized aluminum‐based metal–organic framework (Al‐MOF) system that is resistant to ambient temperature and pH and can act synergistically as a delivery vehicle and an adjuvant is synthesized over a model antigen ovalbumin (OVA) to act as armor. To overcome mucosal barriers, a yeast‐derived capsule is used to carry the Al‐MOF‐armored OVA as a “Trojan Horse”‐like transport platform. In vitro experiments reveal that the mineralization of Al‐MOFs forms an armor on OVA that protects against highly acidic and degradative GI conditions. However, the mineralized Al‐MOFs can gradually disintegrate in a phosphate ion‐containing simulated intracellular fluid, slowly releasing their encapsulated OVA. In vivo studies reveal that the “Trojan Horse”‐like transport platform specifically targets intestinal M cells, favoring the transepithelial transport of the Al‐MOF‐armored OVA, followed by subsequent endocytosis in local macrophages, ultimately accumulating in mesenteric lymph nodes, yielding long‐lasting, high‐levels of mucosal S‐IgA and serum IgG antibodies. Such an engineered delivery platform may represent a promising strategy for the oral administration of prophylactic or therapeutic antigens for vaccination.     

Rear‐Passivated Ultrathin Cu(In,Ga)Se2 Films by Al2O3 Nanostructures Using Glancing Angle Deposition Toward Photovoltaic Devices with Enhanced Efficiency

In this work, for the first time, the addition of aluminum oxide nanostructures (Al₂O₃ NSs) grown by glancing angle deposition (GLAD) is investigated on an ultrathin Cu(In,Ga)Se₂ device (400 nm) fabricated using a sequential process, i.e., post‐selenization of the metallic precursor layer. The most striking observation to emerge from this study is the alleviation of phase separation after adding the Al₂O₃ NSs with improved Se diffusion into the non‐uniformed metallic precursor due to the surface roughness resulting from the Al₂O₃ NSs. In addition, the raised Na concentration at the rear surface can be attributed to the increased diffusion of Na ion facilitated by Al₂O₃ NSs. The coverage and thickness of the Al₂O₃ NSs significantly affects the cell performance because of an increase in shunt resistance associated with the formation of Na₂Se_X and phase separation. The passivation effect attributed to the Al₂O₃ NSs is well studied using the bias‐EQE measurement and J–V characteristics under dark and illuminated conditions. With the optimization of the Al₂O₃ NSs, the remarkable enhancement in the cell performance occurs, exhibiting a power conversion efficiency increase from 2.83% to 5.33%, demonstrating a promising method for improving ultrathin Cu(In,Ga)Se₂ devices, and providing significant opportunities for further applications.     

Temperature-Aware Task Allocation and Scheduling for Embedded Multiprocessor Systems-on-Chip (MPSoC) Design

Temperature affects not only the performance but also the power, reliability, and cost of the embedded system. This paper proposes a temperature-aware task allocation and scheduling algorithm for MPSoC embedded systems. Thermal-aware heuristics are developed, and a temperature-aware floorplanning tool is used to reduce the peak temperature and achieve a thermally even distribution while meeting real time constraints. The paper investigates both power-aware and thermal-aware approaches to the task allocation and scheduling. The experimental results show that the thermal-aware approach outperforms the power-aware schemes in terms of maximal and average temperature reductions. To the best of our knowledge, this is the first MPSoC task allocation and scheduling algorithm that takes temperature into consideration.

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Quadrature Oscillators with Grounded Capacitors and Resistors Using FDCCIIs

Two current‐mode and/or voltage‐mode quadrature oscillator circuits each using one fully‐differential second‐generation current conveyor (FDCCII), two grounded capacitors, and two (or three) grounded resistors are presented. In the proposed circuits, the current‐mode quadrature signals have the advantage of high‐output impedance. The oscillation conditions and oscillation frequencies are orthogonally (or independently) controllable. The current‐mode and voltage‐mode quadrature signals can be simultaneously obtained from the second proposed circuit. The use of only grounded capacitors and resistors makes the proposed circuits ideal for integrated circuit implementation. Simulation results are also included.     

ECVBA traffic‐smoothing scheme for VBR media streams

We propose an effective and efficient traffic‐smoothing called the efficient changes and variability bandwidth allocation (ECVBA) scheme. This algorithm not only minimizes the peak rate of a stream but also increases the likelihood of successful VBR stream transmission. The main benefit is that it can immediately release bandwidth to other sites in the network. Copyright © 2002 John Wiley & Sons, Ltd.     

Upgrading service availability of optical networks: A labor force perspective

Service availability is an important issue in optical networks. Much research attention has been drawn to the provisioning of reliable connections achieved by approaches such as routing and wavelength assignment and by protection and restoration mechanisms. In contrast, the research on upgrading networks to meet new or dynamic demands of service availability based on network upgrading process has been comparatively lacking. In this paper, we address this issue by upgrading service availability from the perspective of labor forces for network maintenance. Our approach is premised on the assumption that the time period for fixing an optical link can be reduced by using more network resources of labor forces. To model this concept, we conduct Amdahl's law, a well‐known theorem in parallel computing, to describe human teamwork. To show the effectiveness of this concept, we propose mixed integer linear programming aiming at either maximizing service availability under limited labor forces or minimizing labor forces for predetermined service availability. In addition, a heuristic algorithm for upgrading service availability is presented. Our experimental results show that our network upgrading process can improve service availability optimally with a fixed number of forces and the proposed heuristic algorithm can effectively save computation time.     

Utilization of self-injection Fabry–Perot laser diode for long-reach WDM-PON

In this investigation we propose and demonstrate a wavelength widely tunable laser source employing a self-injected Fabry–Perot laser diode (FP-LD) for long-reach wavelength-division-multiplexed passive optical network (WDM-PON). By using a tunable bandpass filter and an optical circulator inside the gain cavity, a stable and single-longitudinal-mode (SLM) laser output is achieved. Besides, the proposed laser sources are directly modulated at 2.5 Gb/s for both downlink and uplink transmissions of 85 km single mode fiber (SMF) in PON without dispersion compensation.     

Swarm intelligence‐based anycast routing protocol in ubiquitous networks

As digital devices with communication capability become more pervasive, we are entering the era of ubiquitous computing, as predicted by Mark Weiser. In ubiquitous environments, distributed context management servers are deployed everywhere to provide information and computing resources for users anytime and anywhere. Smart handheld computing devices with context‐aware applications may retrieve context information from the nearest server. This study investigates the problem of routing packets to the nearest server in a ubiquitous environment. An anycast routing protocol based on swarm intelligence, referred to as ARPSI, is proposed to route packets dynamically to a nearby server in a mobile, ad hoc, wireless network. Based on swarm intelligence, ARPSI is able to find a short path to a neighboring server efficiently and quickly. Simulations are conducted to evaluate the performance of ARPSI and our simulation results show that ARPSI achieves a higher packet delivery ratio, shorter routing path to anycast servers, and lower control packet overhead than the AODV‐based anycast protocol (A‐AODV) protocol. Copyright © 2009 John Wiley & Sons, Ltd.     

Fullerene Additives Convert Ambipolar Transport to p‐Type Transport while Improving the Operational Stability of Organic Thin Film Transistors

Many high charge carrier mobility (μ) active layers within organic field‐effect transistor (OFET) configurations exhibit non‐linear current–voltage characteristics that may drift with time under applied bias and, when applying conventional equations for ideal FETs, may give inconsistent μ values. This study demonstrates that the introduction of electron deficient fullerene acceptors into thin films comprised of the high‐mobility semiconducting polymer PCDTPT suppresses an undesirable “double‐slope” in the current–voltage characteristics, improves operational stability, and changes ambipolar transport to unipolar transport. Examination of other high μ polymers shows general applicability. This study also shows that one can further reduce instability by tuning the relative electron affinity of the polymer and fullerene by creating blends containing different fullerene derivatives and semiconductor polymers. One can obtain hole μ values up to 5.6 cm² V^–1 s^–1 that are remarkably stable over multiple bias‐sweeping cycles. The results provide a simple, solution‐processable route to dictate transport properties and improve semiconductor durability in systems that display similar non‐idealities.