Spectral Filtering in OCT System Implemented by Mechanically Induced Long-Period Fiber Grating

A spectral filtering method that can enhance the axial resolution and suppress sidelobes of the point spread function in Optical Coherence Tomography (OCT) system is demonstrated. A mechanically induced long-period fiber grating (MLPG) is used to tailor the spectral shape of a homemade Er-doped fiber amplified spontaneous emission (ASE) source. By using a MLPG, the high and narrow characteristic peak, centered at 1533 nm, of the ASE source was fairly well removed, which enabled us to use a broader spectral bandwidth of the source. The experimental results show that the proposed spectral filtering method can suppress the sidelobes in the axial point spread function up to 5.4 dB and thus enhance the axial resolution of an OCT system by four times. The OCT images of an extracted human premolar taken with and without the spectral filtering are presented and compared with each other.     

Fully‐Inkjet‐Printed Ag‐Coil/NiZn‐Ferrite for Flexible Wireless Power Transfer Module: Rigid Sintered Ceramic Body into Flexible Form

Despite the material performances being superior to those of organic materials, inorganic materials are typically excluded for use in flexible and deformable electronic systems because of their rigid nature and the requirement for high processing temperature. This work presents a novel method of utilizing rigid NiZn‐ferrite films in a flexible platform and offers an opportunity to realize a flexible wireless power transfer (WPT) module. Inkjet printing is introduced in this study since it can coat NiZn‐ferrite films as well as pattern inductor coils for WPTs. A thermochemically inert buffer layer is selected based on a thermodynamic analysis and is introduced as a buffer layer for the NiZn‐ferrite to prevent chemical reaction between the ferrite film and the substrate and ensure that the ferrite film can be easily separated from the substrate during a high‐temperature sintering process. A Ag‐inductor coil is printed on the NiZn‐ferrite layer, and then the entire layer is embedded into polydimethylsiloxane, which renders the WPT module flexible. The flexibility of the WPT module is characterized by a bending test, and the structural and magnetic properties are also investigated. The performance of the flexible WPT module is demonstrated by transmitting wireless power to a light emitting diode.     

Modified leaky LMS algorithm for channel estimation in DS-CDMAsystems

A simple adaptive least mean square (LMS) type algorithm for channel estimation is developed based on certain modifications to finite-impulse response (FIR) Wiener filtering. The proposed algorithm is nearly blind since it does not require any training sequence or channel statistics, and it can be implemented using only noise variance knowledge. A condition guaranteeing the convergence of the algorithm and theoretical mean square error (MSE) values are also derived. Computer simulation results demonstrate that the proposed algorithm can yield a smaller MSE than existing techniques, and that its performance is close to that of optimal Wiener filtering     

Hidden Markov Model Based Localization Using Array Antenna

We present a hidden Markov model (HMM) based localization using array antenna. In this method, we use the eigenvector spanning signal subspace as a location dependent feature. The eigenvector does not depend on received signal strength but on direction of arrival of incident signals. As a result, the eigenvector is robust to fading and noise. In addition, the eigenvector is unique to the environment of propagation due to indoor reflection and diffraction of the radio wave. The conventional localization method based on fingerprinting does not take previous information into account. In our proposal algorithm with HMM, we take previous state of estimation into account by comparing the eigenvector obtained during observation with the one stored in the database. The database has the eigenvector obtained at each reference point according to setting in advance. In an indoor environment represented in a quantized grid, we design the transition probability due to previous estimated position. Because of this, target’s movable range is obtained. In addition, we use maximum likelihood estimation method based on statics of correlation values. The correlation value is an indicator of pattern matching in a fingerprinting method. The most likely trajectory is calculated by Viterbi algorithm with above mentioned probabilities. The experimental results show that the localization accuracy is improved owing to the use of HMM.     

Engineering Materials for Electrochemical Sweat Sensing

Human sweat contains vast physiological information, which has been a promising resource for on-body and real-time health monitoring. Wearable sweat sensors have recently attracted an ever-increasing interest due to their promising capabilities for continuously tracking changes in health status. However, the commercialization of sweat sensors is seriously hindered by drawbacks of materials including high manufacturing and consumables costs, complex integration technology, as well as limited electrochemical signal transduction. In this review, sweat sensing principles are elaborately interpreted, and the latest advances in functional materials for biomarkers sensing in sweat are systematically summarized. Subsequently, the complex structure–activity relationships between various functional materials and sensing capabilities are further elucidated by coupling chemical structures, geometrics, electrochemical properties, and approaches for materials manufacturing. Furthermore, the integration of each component into sensing device for sweat detection and analysis is also discussed. Finally, challenges and opportunities for wearable sweat sensors are delineated in the development of future personalized and predictive healthcare.     

Novel isothiocyanate transposition in 2-alkyliminothiazoles: a simple solution for regiochemical problem

Novel alkyl/aryl transposition in the reaction of 2-iminothiazoles with alkyl/aryl isothiocyanates was found out, and the reaction was very easy to handle and gave good to excellent chemical yields. Moreover, transposition reaction provided a simple but excellent solution for regiochemical problems in 2-iminothiazole synthesis.     

Traveling wave solutions for the combustion model of a shear flow in a cylinder

We establish traveling wave solutions for the combustion model of a shear flow in a cylinder. We study two cases: the infinite Lewis number and an arbitrary Lewis number. For the infinite Lewis number, we establish the existence of traveling wave fronts for both non‐minimal and minimal speeds. For an arbitrary Lewis number, we establish the uniform bounds and exponential decay rates. Copyright © 2015 John Wiley & Sons, Ltd.     

A local synchronization-based wireless system for power efficient ad-hoc networks

In a scalable ad-hoc network, which is deployed in a large area with many nodes, it is difficult to maintain global time synchronization among all nodes in a whole network. Considering this problem, a local synchronization-based system is presented to discover neighboring nodes in a scalable wireless network. With the proposed system, a whole ad-hoc network is composed of several subgroups and local time synchronization is maintained within each subgroup. For the proposed system, the transmitter and receiver operations of a node are presented to discover neighboring nodes. The most important parameter for power consumption is the duty cycle of a node, defined as the ratio between the receiver turn-on time and total considered time. The duty cycles of the proposed system and cyclic quorum-based power management (CQPM) are compared by analysis. In addition, the power consumptions of the proposed system and CQPM are compared by simulation. The results show that the proposed system can reduce the power consumption of a node significantly in a scalable ad-hoc network.