Distance transform algorithm for measuring nanofiber diameter

This paper describes a new distance transform method used for measuring fiber diameter in electrospun nanofiber webs. In this algorithm, the effect of intersection is eliminated, which brings more accuracy to the measurement. The method is tested by a series of simulated images with known characteristics as well as some real webs obtained from electrospinning of PVA. Our method is compared with the distance transform method. The results obtained by our method were significantly better than the distance transform, indicating that the new method could successfully be used to measure electrospun fiber diameter.     

A mathemathical model for the calculation of the concentration at the outlet of an ozone generator

A mathematical model was generated to predict the composition of the outlet gas of ozone generators. In order to make the modelling possible it was important to predict the occurrence time and the exact location of each individual discharge zone. This was done by connecting a specially constructed ozone generator, which would locate the discharge zones, to a nanosecond pulse generator which would impose regular occurrence times for discharge columns. The experimental and theoretical outlet concentrations of this ozone generator were compared. The result was an excellent match which justified the assumptions made in the model. The mathematical model was also used to study the effect of different factors affecting the production of ozone.     

Synthesis and characterization of exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposite via miniemulsion atom transfer radical polymerization: an activators generated by electron transfer approach

Exfoliated poly(styrene‐co‐methyl methacrylate) nanocomposites were synthesized using activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP). Miniemulsion polymerization was used for its abundant advantages to encapsulate inorganic materials and eliminate organic solvents from products for environmentally friendly purposes. Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, which is an effective surfactant at higher temperatures, was used to stabilize the miniemulsion system. Successful miniemulsion AGET ATRP was carried out by using 4,4'‐dinonyl‐2,2'‐bipyridine (dNbPy) as a hydrophobic ligand. Formation of monodispersed droplets and particles with sizes in the range of 200nm was examined by dynamic light scattering (DLS). Conversion and molecular weight study were also carried out using gravimetry and gel permeation chromatography, respectively. By adding clay content, a decrease in the conversion and molecular weight of the nanocomposites are observed. However, an increase in the PDI values of nanocomposites was observed by the addition of nanoclay content. Thermogravimetric analysis results demonstrate that thermal stability of all the nanocomposites in comparison with the neat copolymer increases. Differential scanning calorimetry results show that T_g decreases by increasing clay content. Monodisperse distribution of spherical shape particles with sizes in the range of ∼ 200 nm was demonstrated by using scanning electron microscopy images of nanocomposite containing 1 wt% of nanoclay, which is more compiled with DLS results. Transmission electron microscopy results shows well‐dispersed exfoliated clay layers in the polymer matrix of PSMNM 1, which is coincidence with X‐ray diffraction data. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Application of the PSO–SVM model for recognition of control chart patterns

Control chart patterns are important statistical process control tools for determining whether a process is run in its intended mode or in the presence of unnatural patterns. Accurate recognition of control chart patterns is essential for efficient system monitoring to maintain high-quality products. This paper introduces a novel hybrid intelligent system that includes three main modules: a feature extraction module, a classifier module, and an optimization module. In the feature extraction module, a proper set combining the shape features and statistical features is proposed as the efficient characteristic of the patterns. In the classifier module, a multi-class support vector machine (SVM)-based classifier is proposed. For the optimization module, a particle swarm optimization algorithm is proposed to improve the generalization performance of the recognizer. In this module, it the SVM classifier design is optimized by searching for the best value of the parameters that tune its discriminant function (kernel parameter selection) and upstream by looking for the best subset of features that feed the classifier. Simulation results show that the proposed algorithm has very high recognition accuracy. This high efficiency is achieved with only little features, which have been selected using particle swarm optimizer.     

A novel low-power full-adder cell for low voltage

This paper presents a novel low-power majority function-based 1-bit full adder that uses MOS capacitors (MOSCAP) in its structure. It can work reliably at low supply voltage. In this design, the time-consuming XOR gates are eliminated. The circuits being studied are optimized for energy efficiency at 0.18-μm CMOS process technology. The adder cell is compared with seven widely used adders based on power consumption, speed, power-delay product (PDP) and area efficiency. Intensive simulation runs on a Cadence environment and HSPICE show that the new adder has more than 11% in power savings over a conventional 28-transistor CMOS adder. In addition, it consumes 30% less power than transmission function adder (TFA) and is 1.11 times faster.     

A New Construction of Signature Waveforms for Multi-rate Multi-cell QS-CDMA Systems

In this paper, we propose a new construction of signature waveform sets based on Generalized Loosely Synchronization (GLS) sets and different chip waveforms. The new signature sets are applied into the multi-rate multi-cell quasi-synchronous CDMA (QS-CDMA) system where each cell is assigned with a GLS set; different users in the same cell are assigned with different GLS sequences in the same GLS set; user’s different streams are assigned with the same GLS sequence but different chip waveforms. According to the properties of GLS sets, the inter-cell interference (ICI) and the multi-user interference (MUI) in the same cell can be reduced significantly. The interferences among different streams of the same user are handled by an optimal (or suboptimal) multi-stream detector(s), notice that the multi-stream detector mentioned here is also named as multi-user detector in other references. We compare the performance of the multi-rate multi-cell QS-CDMA system employing the proposed sets with that of multi-rate system employing well-known concatenated orthogonal/PN sets and that of single-rate system employing GLS sets. The results show that the multi-rate system employing the proposed sets can achieve significant interference reduction. Meanwhile the performance of multi-rate system is similar to that of single-rate system due to the inclusion of multi-user detection.

Analytical EVM, BER, and TD performances of the OFDM systems in the presence of jointly nonlinear distortion and IQ imbalance

The orthogonal frequency-division multiplexing (OFDM) systems are highly sensitive to the nonlinear distortions introduced by the high-power amplifier at the transmitter and to the in-phase and quadrature (IQ) imbalance of the down converter at the receiver. In this paper, the joint effects of these impairments on the performance of the OFDM systems with M signal points quadrature amplitude modulation (M-QAM) are investigated. Moreover, the analytical formulations for the error vector magnitude, the bit error rate, and the total degradation performances of the M-QAM-OFDM systems in additive white Gaussian noise channels as a function of the output back off and IQ imbalance parameters are derived. The computer simulation results confirm the accuracy and validity of our proposed analytical approach.     

Cramer–Rao bound and minimum variance unbiased estimator for joint sampling clock offset and channel taps in MC‐CDMA systems

Exact closed‐form expressions of the Cramer–Rao bound (CRB) for joint sampling clock offset and channel taps are obtained in multi‐carrier code division multiple access systems. CRB is undoubtedly the most well known variance's bound to determine. It provides a benchmark against which we can compare the performance of any unbiased estimator. Furthermore, minimum variance unbiased (MVU) estimator for these parameters is proposed. Moreover, maximum likelihood (ML) and least‐squares estimators for joint sampling clock offset and channel taps are presented. Best linear unbiased estimator is also introduced just for channel taps. The performances of the estimators are compared through simulation results with the proposed CRB. Our results show the better performances of MVU and ML estimators with more computational complexity compared with the others. Copyright © 2008 John Wiley & Sons, Ltd.     

Dynamically anchored conferencing handoff for dual-mode cellular/WLAN handsets

In this paper we consider vertical handoff for enterprise-based dual-mode (DM) cellular/WLAN handsets. When the handset roams out of WLAN coverage, the DM's cellular interface is used to maintain the call by anchoring it through an enterprise PSTN gateway/PBX. Soft handoff can be achieved in this case if the gateway supports basic conference bridging, since a new leg of the call can be established to the conference bridge while the existing media stream path is active. Unfortunately this requires that all intra-enterprise calls be routed through the gateway when the call is established. In this paper we consider a SIP based architecture to perform conferenced dual-mode handoff and propose a much more scalable mechanism for short-delay environments, whereby active calls are handed off into the conference bridge prior to the initiation of the vertical handoff. Results are presented which are taken from a dual-mode handset testbed, from analytic models, and from simulations which characterize the scalability of the proposed mechanism. Mohammed Smadi received the B.Eng and Mgmt and M.A.Sc degrees in Computer Engineering from McMaster University in Hamilton, Ontario, Canada. Mohammed received an NSERC doctoral award in 2005 and is currently a Ph.D. student at the Wireless Networking Group at McMaster University. Terence D. Todd received the B.A.Sc, M.A.Sc and Ph.D. degrees in Electrical Engineering from the University of Waterloo, Waterloo, Ontario, Canada. While at Waterloo he spent 3 years as a Research Associate with the Computer Communications Networks Group (CCNG). He is currently a Professor of Electrical and Computer Engineering at McMaster University in Hamilton, Ontario, Canada. Professor Todd spent 1991 on research leave in the Distributed Systems Research Department at AT&T Bell Laboratories in Murray Hill, NJ. He also spent 1998 on research leave at The Olivetti and Oracle Research Laboratory in Cambridge, England. While at ORL he worked on the piconet project which was an early embedded wireless network testbed. Dr. Todd’s research interests include metropolitan/local area networks, wireless communications and the performance analysis of computer communication networks and systems. He is a past Editor of the IEEE/ACM Transactions on Networking and currently holds the NSERC/RIM/CITO Chair on Pico-Cellular Wireless Internet Access Networks. Dr. Todd is a Professional Engineer in the province of Ontario and a member of the IEEE. Vytas Kezys was born in Hamilton, Canada in 1957. He received the B.Eng. degree in Electrical Engineering from McMaster University, Canada, in 1979. From 1979 to 1998, Mr. Kezys was involved in radar and communications research as Principal Research Engineer at the Communications Research Laboratory, McMaster University. While at McMaster, his research activities included array signal processing for low-angle tracking radar, radar signal processing, and smart antennas for wireless communications. Mr. Kezys was founder and President of TalariCom Inc., a start-up company that developed cost effective smart antenna technologies for broadband wireless access applications. Currently, Mr. Kezys is Director of Advanced Products at Research in Motion in Waterloo, Canada. Vahid S. Azhari received his B.S. and M.S. from the Department of Electrical and Computer Engineering, IUST and University of Tehran, Iran, in 2000 and 2003 respectively. His M.S. research focused on designing scheduling algorithms for switch fabrics. He also worked for two years for the Iranian Telecommunication Research Centre on developing software for SDH switches. He is currently pursuing his Ph.D. degree at the Wireless Networking Laboratory, McMaster University, Canada. His main area of research includes handoff management in integrated wireless networks, WLAN deployment techniques, and wireless mesh networks. Dongmei Zhao received the Ph.D. degree in Electrical and Computer Engineering from the University of Waterloo, Waterloo, Ontario, Canada in June 2002. Since July 2002 she has been with the Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada where she is an assistant professor. Dr. Zhao’s research interests include modeling and performance analysis, quality-of-service provisioning, access control and admission control in wireless cellular networks and integrated cellular and ad hoc networks. Dr. Zhao is a member of the IEEE.     

Improving the functionality of biodegradable food packaging materials via porous nanomaterials

Non-biodegradability and disposal problems are the major challenges associated with synthetic plastic packaging. This review article discusses a new generation of biodegradable active and smart packaging based on porous nanomaterials (PNMs), which maintains the quality and freshness of food products while meeting biodegradability requirements. PNMs have recently gained significant attention in the field of food packaging due to their large surface area, peculiar structures, functional flexibility, and thermal stability. We present for the first time the recently published literature on the incorporation of various PNMs into renewable materials to develop advanced, environmentally friendly, and high-quality packaging technology. Various emerging packaging technologies are discussed in this review, along with their advantages and disadvantages. Moreover, it provides general information about PNMs, their characterization, and fabrication methods. It also briefly describes the effects of different PNMs on the functionality of biopolymeric films. Furthermore, we examined how smart packaging loaded with PNMs can improve food shelf life and reduce food waste. The results indicate that PNMs play a critical role in improving the antimicrobial, thermal, physicochemical, and mechanical properties of natural packaging materials. These tailor-made materials can simultaneously extend the shelf life of food while reducing plastic usage and food waste.