Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process

ABSTRACT: One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods.     

Analytical synthesis of general high-order voltage/current transfer functions using CCIIs

This paper proposes two circuit structures to realize general high-order voltage and current transfer functions using second-generation current conveyors (CCIIs). The proposed general high-order voltage/current-mode circuit structures are designed based on an analytical synthesis method. The nth-order voltage-mode transfer function requires 2n+1 CCIIs, 2n+2 grounded resistors and n grounded capacitors. The nth-order current-mode transfer function requires 2n+2 CCIIs, 2n+2 grounded resistors and n grounded capacitors. The voltage-mode third-order allpass, lowpass and highpass filters and the current-mode third-order notch, lowpass and highpass filters that are derived out from the proposed high-order voltage and current-mode circuit structures are simulated to verify the synthesis methods.     

Failure modes and effects analysis for high-power GaN-based light-emitting diodes package technology

In this study, nondestructive test is developed to analyze the structure failure of LED package. The relationship between thermal resistance analysis and LED package failure structure is build with T3Ster thermal transient tester and scanning electron microscope (SEM). The failure LED device with defect in the attaching layer and gap between LED chip and copper are designed advisedly. The failure factors of LED package have been measured with thermal resistance analysis and SEM cross-section images. The thermal dissipation performance of LED with defect in the attaching layer is indicated by thermal resistance analysis combined with SEM cross-section images. The blister in attaching layer results in 4.4 K/W additional thermal resistance. The gap between LED chip and copper also makes high additional thermal resistance with 8.6 K/W. Different failures of LED packages are indicated obviously using thermal transfer analysis. The LED package failure structure such as interface defect between solder and cup-shaped copper is able to forecast without destructive measurement.     

High Input Impedance Voltage-Mode Universal Biquadratic Filter with Three Inputs and Six Outputs Using Three DDCCs

A new high input impedance voltage-mode universal biquadratic filter with three input terminals and six output terminals is presented. The proposed circuit uses three plus-type differential difference current conveyors (DDCCs), three resistors, and two grounded capacitors. The proposed circuit can realize all the standard filter functions, namely, lowpass, bandpass, highpass, notch, and allpass, simultaneously, without component matching conditions. The proposed circuit still offers the features of high input impedance, using only grounded capacitors, and orthogonal controllability of resonance angular frequency and quality factor.     

SmartMote: An Adaptive Update Mechanism for Wireless Ad-Hoc Sensor Network

This paper describes a novel update mechanism for large wireless ad-hoc sensor networks (WASNs). In wireless sensor networks, the nodes may have to be reprogrammed, especially for design-implement-test iterations. Manually reprogramming is a very cumbersome work, and may be infeasible if nodes of the network are unreachable. In addition, replacing the executed application on a node by transmitting the complete program image is inefficient for small changes in the code either. It consumes a lot of bandwidth and time. Therefore, an on-the-fly update mechanism is required. This paper exploits programmable packets to update sensor behaviors. To reduce the code transferred and power consumption, a group management architecture is developed. This architecture helps reduce power consumption and increase node number that control by Leader Node in WASNs. The proposed update mechanism, SmartMote, has been implemented on the Tmote-based Octopus II sensor node. Performance evaluation as well as measurement is conducted in the paper to illustrate the significance of the proposed mechanism.     

Heterogeneous Vehicle Navigation Platform Combined with Mobile RFID Using MIMO System

In a mobile Radio Frequency Identification (RFID) system, the RFID tag is attached to a mobile object such as a vehicle, a human etc. The information is more difficult to detect than in the case where the tag is attached to a stationary object. The RFID reader and back-end database both help to automatically record and store the vehicle driver information and real time status of a tracked geographic information system (GIS), and they cooperate to synchronize the information flow and monitor. In this paper, the Kalman filter (KF) has been implemented as the primary integration scheme of the global positioning system (GPS) and inertial navigation systems (INS) for many land vehicle navigation and positioning applications. It also includes estimating the state of dynamic systems, almost all systems have some dynamic component, and determine how to best use a given set of vehicle sensors for modeling a high performance analysis by using the KF algorithm.     

A new authentication based cheating prevention scheme in Naor–Shamir’s visual cryptography

Visual cryptography (VC), first presented by Naor and Shamir, is a variant of secret sharing, thus it also called visual secret sharing. It can be widely used in many applications such as encrypting large data efficiently. In the literature, the problem of cheating is under consideration in secret sharing. Recently, Horng et al. pointed out that cheating is possible in k-out-of-n VC schemes, and presented two kinds of the cheating prevention schemes for protecting honest participants. One of them is the authentication based cheating prevention scheme. In this paper, we analyze the definition of cheating prevention and propose a new authentication based cheating prevention scheme. This scheme is constructed with Naor–Shamir’s VC scheme. Finally, we give the security analysis to prove that the proposed scheme is immune to cheating.     

Characterization of protein immobilization on nanoporous gold using atomic force microscopy and scanning electron microscopy

Nanoporous gold (NPG), made by dealloying low carat gold alloys, is a relatively new nanomaterial finding application in catalysis, sensing, and as a support for biomolecules. NPG has attracted considerable interest due to its open bicontinuous structure, high surface-to-volume ratio, tunable porosity, chemical stability and biocompatibility. NPG also has the attractive feature of being able to be modified by self-assembled monolayers. Here we use scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize a highly efficient approach for protein immobilization on NPG using N-hydroxysuccinimide (NHS) ester functionalized self-assembled monolayers on NPG with pore sizes in the range of tens of nanometres. Comparison of coupling under static versus flow conditions suggests that BSA (Bovine Serum Albumin) and IgG (Immunoglobulin G) can only be immobilized onto the interior surfaces of free standing NPG monoliths with good coverage under flow conditions. AFM is used to examine protein coverage on both the exterior and interior of protein modified NPG. Access to the interior surface of NPG for AFM imaging is achieved using a special procedure for cleaving NPG. AFM is also used to examine BSA immobilized on rough gold surfaces as a comparative study. In principle, the general approach described should be applicable to many enzymes, proteins and protein complexes since both pore sizes and functional groups present on the NPG surfaces are controllable.     

Using Sorted Switching Median Filter to remove high-density impulse noises

We propose a novel Sorted Switching Median Filter (i.e. SSMF) for effectively denoising extremely corrupted images while preserving the image details. The center pixel is considered as “uncorrupted” or “corrupted” noise in the detecting stage. The corrupted pixels that possess more noise-free surroundings will have higher processing priority in the SSMF sorting and filtering stages to rescue the heavily noisy neighbors. Five noise models are considered to assess the performance of the proposed SSMF algorithm. Several extensive simulation results conducted on both grayscale and color images with a wide range (from 10% to 90%) of noise corruption clearly show that the proposed SSMF substantially outperforms all other existing median-based filters.     

High output impedance current-mode first-order allpass networks with four grounded components and two CCIIs

Eight current-mode first-order allpass networks using second-generation current conveyors (CCII) are presented. Each of the proposed circuits employs two CCIIs, two grounded capacitors and two grounded resistors. The networks offer high output impedances. Experimental results are also included.