A zero-cost, real-time, Windows signal laboratory

This paper introduces a Windows-based signal capture, display, and waveform synthesis package called “Win-eLab”. The software is able to run on a conventional desktop or laptop with no additional hardware, and can perform real-time Fourier analysis on audio-frequency signals. This paper is intended as an introduction to Win-eLab, aimed at motivating further use of it in both teaching and self-directed learning contexts. The use of the software to familiarize students with the concept of “laboratory” instrumentation is discussed, as well as the usefulness of a simultaneous time-domain/frequency-domain display for understanding signals, particularly in signal processing and communications systems courses. It is anticipated that applications may extend beyond electrical & electronic engineering – for example, as an aid to understanding mechanical vibrations, acoustics, and in other discipline areas

Exit chart analysis of parallel data convolutional codes

We recently proposed a new class of turbo-like codes called parallel data convolutional codes (PDCCs). The distinct characteristics of PDCCs include parallel data input bits and a self-iterative soft-in/soft-out a posteriori probability(APP) decoder. In this paper, we analyse this turbolike code by means of the extrinsic information transfer chart (EXIT chart). Our results show that the threshold Eb/N0 point for a rate 1/2 8-state PDCC is 0.6 dB, which is the same as the threshold point for a punctured rate 1/2 16-state parallel concatenated convolutional code (turbo code)

Error resilience analysis of wireless image transmission using JPEG, JPEG 2000 and JPWL

The wireless extension of the JPEG 2000 standard formally known as JPWL is the newest international standard for still image compression. Different from all previous standards, this new standard was created specifically for wireless imaging applications. This paper examines the error resilience performance of the JPEG, JPEG 2000 and JPWL standards in combating multi-path and fading impairments in Rayleigh fading channels. Comprehensive objective and subjective results are presented in relation to the error resilience performance of these three standards under various conditions. The major findings in this paper reveal that a CRC approach is not a viable option for protecting wireless image data when not used in conjunction with an efficient retransmission strategy. In addition, the Reed-Solomon error correction codes in JPWL provide strong protection for wireless image transmission. However, any stronger protection beyond RS(64,32) yields diminishing returns

Throughput and fairness of multiple TCP connections in wireless networks

TCP suffers from poor throughput performance in wireless networks. Furthermore, when multiple TCP connections compete at the base station, link errors and congestion lead to serious unfairness among the connections. Although the issue of TCP performance in wireless networks has attracted significant attention, most reports focus only on TCP throughput and assume that there is only a single connection in a congestion-free network. This paper studies the throughput and fairness of popular improvement mechanisms (the Snoop [8] and ELN [5]) and TCP variants with multiple TCP connections. Simulation results show that the improvement mechanisms under investigation are effective to improve TCP throughput in a wireless network. However, they cannot provide fairness among multiple TCP connections. From the studies presented, it is concluded that mechanisms to enhance TCP fairness are needed in wireless network

A Robust Method for Tuning Photoacoustic Gas Detectors

Detection of gases in industrial contexts is of great importance for ensuring safety in storage and transport, so as to limit atmospheric pollution and precisely control industrial and agricultural processes. Although chemical sensors are in widespread use, solid-state infrared detectors for gas sensing promise numerous advantages over conventional catalytic detectors in terms of sensitivity, calibration requirements, and lifetime. The laser-modulation photoacoustic approach is an alternative. Compared to other approaches, it provides more precise measurements with a stable zero baseline, as well as having significantly less complicated optics than cavity ringdown approaches. One enduring problem, though, is the relatively long time required to make photoacoustic measurements. The key contribution of this paper to the industrial context is twofold: first, we show how a sensitive dual-buffer acoustic resonator may be fabricated using 3D printing, and secondly we describe a method for localizing the peak absorption more rapidly than stepping a laser through the gas absorption profile. Modelling of the proposed approach demonstrates its potential, and the expected results are confirmed using an extensive experimental setup for the detection of methane in air

Capture and playback of computer screen contents and accompanying audio

Computer screen contents and accompanying audio are captured by a method, embodiments of which are implemented by a specialized apparatus. Embodiments of the method include capturing an image of the computer screen contents at predetermined time intervals and determining one or more changes between a current captured image and a previous captured image. The method also includes modifying color data associated with a changed region of the current captured image and encoding the modified color data for the changed region

On uniqueness for time harmonic anisotropic Maxwell's equations with piecewise regular coefficients

We are interested in the uniqueness of solutions to Maxwell's equations when the magnetic permeability $\mu$ and the permittivity $\varepsilon$ are symmetric positive definite matrix-valued functions in $\mathbb{R}^{3}$. We show that a unique continuation result for globally $W^{1,\infty}$ coefficients in a smooth, bounded domain, allows one to prove that the solution is unique in the case of coefficients which are piecewise $W^{1,\infty}$ with respect to a suitable countable collection of sub-domains with $C^{0}$ boundaries. Such suitable collections include any bounded finite collection. The proof relies on a general argument, not specific to Maxwell's equations. This result is then extended to the case when within these sub-domains the permeability and permittivity are only $L^\infty$ in sets of small measure.Comment: 9 pages, 4 figure

Microwave technique for liquid water detection in icing applications

The partial melting of ingested ice crystals can lead to ice accretion in aircraft compressors, but accurately measuring the relatively small fraction of liquid water content in such flows is challenging. Probe-based methods for detecting liquid water content are not suitable for deployment within turbofan engines, and thus alternatives are sought. Recent research has described approaches based on passive microwave sensing. We present here an approach based on active microwave transmission and reflection, employing a vector network analyzer. Utilization of both transmission and reflection provides additional data over and above emission or transmission only, and permits a more controllable environment than passive sensing approaches. The paper specifically addresses the question of whether such an approach is viable within the context of representative icing wind tunnel and engine flow conditions. A quasi-thermal equilibrium approach is presented herein to estimate the melting ratio during microwave analysis of samples at 0 °C. Experimental results using microwaves in the 2.45GHz region are presented, and post-processing methods investigated. This is followed by an investigation of detection limits for ice accretion in the sub-gram range. The results indicate the potential of the technique, with a number of avenues evident for further research

West Nile Virus–associated Flaccid Paralysis

The causes and frequency of acute paralysis and respiratory failure with West Nile virus (WNV) infection are incompletely understood. During the summer and fall of 2003, we conducted a prospective, population-based study among residents of a 3-county area in Colorado, United States, with developing WNV-associated paralysis. Thirty-two patients with developing paralysis and acute WNV infection were identified. Causes included a poliomyelitislike syndrome in 27 (84%) patients and a Guillain-Barré–like syndrome in 4 (13%); 1 had brachial plexus involvement alone. The incidence of poliomyelitislike syndrome was 3.7/100,000. Twelve patients (38%), including 1 with Guillain-Barré–like syndrome, had acute respiratory failure that required endotracheal intubation. At 4 months, 3 patients with respiratory failure died, 2 remained intubated, 25 showed various degrees of improvement, and 2 were lost to followup. A poliomyelitislike syndrome likely involving spinal anterior horn cells is the most common mechanism of WNV-associated paralysis and is associated with significant short- and long-term illness and death

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT