Multichannel FSK experiment using an optical amplifier repeater and wavelength tunable direct detection receiver

A four channel direct detection FDM operating at 565 Mbit/s with a channel spacing of 12 GHz which achieves a receiver sensitivity of -40 dBm is reported. A laser preamplifier is used to overcome the optical processing loss of the channel selective filter.<>     

Terminals for a high-speed optical pulse code modulation communication system: II. Optical multiplexing and demultiplexing

Techniques are described for optically multiplexing and demultiplexing individual pulse code modulation channels in order to develop the terminal capability for a high-capacity optical communication system. It is shown that, using these techniques, an information capacity in excess of 10¹⁰bit/s can be achieved on the output beam of a single laser.     

A novel orthogonal modulation format of D8PSK/ASK with differential bi-phase encoding and its application in a label switching optical network

The principle of a novel orthogonal modulation format of differential 8-level phase-shift keying amplitude-shift keying (D8PSK/ASK) with differential bi-phase encoding (DBC) is introduced. Based on it, an optical labeling scheme, in which the payload is 100 Gbit/s D8PSK signal and the label is 10 Gbit/s DBC-ASK signal, is proposed and simulated. The results are compared with other current schemes, and the effects of transmission range, modulation extinction ratio (ER) and received power on system performance are analyzed, respectively. The results show that the spectrum efficiency and bit error rate (BER) are improved greatly, and when the modulation ER is increased to 11 dB, the balanced performance between the payload and label is achieved.     

Self-adaptive source separation. II. Comparison of the direct,feedback, and mixed linear network

For pt.I see ibid., vol.45, p.918-26 (1997). Macchi and Moreau (1997) investigated stability and convergence of a new direct linear adaptive neural network intended for separating independent sources when it is controlled by the well-known Herault-Jutten algorithm. In this second part, we study the corresponding feedback adaptive network. For two globally sub-Gaussian sources, the network achieves quasi-convergence in the mean square sense toward a separating state. A novel mixed adaptive direct/feedback network that is free of implementation constraints is investigated from the points of view of stability and convergence and compared with the direct and feedback networks. The three networks have the same (low) complexity. The mixed one achieves the best trade-off between convergence speed and steady-state separation performance, independently of the specific mixture     

Part I: A computer program for the simulation of telecommunication systems: application to optical transmission systems

The conception and analysis of optical transmission systems employing various optical devices (semiconductor lasers, optical fibre, optical amplifiers, photo-diodes,…) require the support supplied by simulation software dedicated to the new components. The objective of thecnet/ipsis collaboration is to respond to this need. In this first article we present the simulation tools which characterize the quality of a digital transmission system, as well as the modelling of the optical elements. In order to show its full range of capabilities in the optical domain, a second article describes the results obtained from the simulation of digital transmission system using wavelength multiplexing.     

Transport Properties of Bulk Thermoelectrics: An International Round-Robin Study, Part II: Thermal Diffusivity, Specific Heat, and Thermal Conductivity

For bulk thermoelectrics, improvement of the figure of merit ZT to above 2 from the current values of 1.0 to 1.5 would enhance their competitiveness with alternative technologies. In recent years, the most significant improvements in ZT have mainly been due to successful reduction of thermal conductivity. However, thermal conductivity is difficult to measure directly at high temperatures. Combined measurements of thermal diffusivity, specific heat, and mass density are a widely used alternative to direct measurement of thermal conductivity. In this work, thermal conductivity is shown to be the factor in the calculation of ZT with the greatest measurement uncertainty. The International Energy Agency (IEA) group, under the implementing agreement for Advanced Materials for Transportation (AMT), has conducted two international round-robins since 2009. This paper, part II of our report on the international round-robin testing of transport properties of bulk bismuth telluride, focuses on thermal diffusivity, specific heat, and thermal conductivity measurements.     

IPTV Systems, Standards and Architectures: Part II - IPTV Architectures for Cable Systems: An Evolutionary Approach

IPTV systems are beginning to be deployed by telcos, to compete with cable and other television service providers. While cable network spectral bandwidths are larger than their wireline equivalents, bandwidth-consuming services such as HDTV are quickly filling this spectrum, prompting cable operators to consider video switching options as a means to increase programming capacity. This article examines the cable video network architecture, and in particular new emerging technologies that can provide cable networks with the means to transition to an IPTV architecture.     

The role of bond graph modeling and simulation in mechatronics systems: An integrated software tool: CAMP-G, MATLAB–SIMULINK

One of the main and most challenging steps in the design and analysis of a mechatronics system is to generate a computer model. This paper explores the fundamental theory, the methodology and the process from conceptual ideas to practical realization. Using a multienergetic approach that allows the modeling of interdisciplinary models, it explores the theory and method to automate the process of the generation of the differential equations and how to automate the derivation of transfer functions. The approach is discussed for linear and non-linear systems. The generation of a computer model takes new dimensions when that model contains mixed energy domains such as electromechanical, electrohydraulic, thermo-fluid, and electronic control systems all together. These are typical of mechatronics applications. This paper explores the bond graph technique as a modeling tool to generate state space models or non-linear models together with software tools. CAMP-G (Computer Aided Modeling Program with Graphical input) has been developed in order to generate computer models automatically and have them integrated with MATLAB–SIMULINK as simulation tools. Several aspects of mechatronics systems design have been investigated in order to focus on which areas the bond graph modeling technique can help engineers in the process of creating mechatronics systems from scratch. Towards this end, the paper deals with computer-generated models of sensors, actuators, and multidisciplinary complex physical systems.     

西藏WLAN网络优化工作研究——以西藏某高校WLAN网络优化为例

WLAN是各运营商全业务发展策略的重要组成部分,也是西藏自治区建设宽带城市最经济有效的方式。WLAN网络规模不断扩大,为保证用户使用的感知度,对WLAN网络优化工作提出了更高的要求。首先,文章总结了WLAN网络测试的主要指标及标准值。其次,论述了对WLAN网络的优化应综合考虑覆盖、容量、质量3方面影响,并区分不同场景给出优化方案。最后,以西藏某高校WLAN网络为例进行案例分析。     

Element pattern of an axial dipole in a cylindrical phased array, Part II: Element design and experiments

The design and construction of a cylindrical array of axial dipoles is described. Dipole pattern amplitude measurements performed over practical scan and frequency ranges show excellent agreement with theoretically predicted results. Dipole pattern phase, feed line effects and radiator match are also discussed. These results provide strong evidence of the correctness of the analysis and numerical results presented in Part I of this paper, and furnish a firm basis for accurate prediction of array performance.     

Development of an integrated hardware and software platform for the rapid detection of cerebral aneurysm rupture

A cerebral aneurysm is defined as a weakened portion of an artery in the brain. Rupture of a cerebral aneurysm leads to subarachnoid hemorrhage (SAH). A significant number of patients with SAH are initially misdiagnosed and subjected to the risks associated with aneurysm re-rupture. Traditional detection methods recommended by physicians include computed tomography (CT) scan, lumbar puncture and angiography. Unfortunately, the CT scan is ineffective after 12 h, and angiography is best suited for those cases of finding the aneurysm before surgery. Physicians may therefore rely on lumbar puncture to develop a quick and objective evaluation by assessing xanthochromia. Bilirubin in the cerebrospinal fluid, resulting from the chemical decomposition of whole blood, is an indicator of hemorrhage. This metabolite can be detected after lumbar puncture, by differentiating its optical signature in the spinal fluid. In cases of traumatic spinal tap, bilirubin needs to be distinguished from whole blood. We introduce a diagnostic system based on visible spectroscopy to quickly and objectively assess low blood-volume SAH. The system integrates innovative hardware and a powerful software interface. We explore an algorithm that accounts for the noise and distortion from blood in the cerebrospinal fluid. We introduce a portable, user-friendly hardware platform composed of specific components designed for their sensitivity and specificity.     

Process modeling and simulation for Hg1-xCdxTe. Part II: Self-diffusion,interdiffusion, and fundamental mechanisms of point-defect interactions in Hg1-xCdxTe

The Hg_0.8Cd_0.2Te type-conversion, Hg self-diffusion and interdiffusion processes are analyzed in the context of a first order reaction kinetics approach. Sets of nonlinear, stiffly coupled continuity equations are presented which describe the underlying physics, and their solutions model the observed macroscopic behavior. It is demonstrated that the Frenkel pair mechanism interactions dominated by the cation sublattice, in conjunction with basic diffusive and drift properties of the ionized point defects, comprise the basic processes which effect all macroscopic phenomena discussed. Existing experimental results are reviewed and apparent discrepancies discussed. Use is made of the Stanford University mercury cadmium telluride process simulator to provide quantitative and insightful examples of important results.     

自动处方软件的开发及应用——以新生儿肠外营养开方软件为例

开发这款新生儿肠外营养(PN)开方软件是为了辅助临床医生根据不同新生儿的情况高效准确地制订肠外营养治疗方案。该软件通过归纳新生儿肠外营养处方涉及的药品,设置相应药品模板,自动产生PN处方和计算处方营养成分配比,标记超出参考范围的指标。该软件不仅为临床医生制订治疗方案提供依据,同时还提高了开方的准确性和效率,保证了新生儿监护病区肠外营养的用药安全。     

The intercomparison of a black and white and a color display: an example of the use of receiver operating characteristic curves

A black and white display was compared to a color display using the heated object spectrum with the aim of verifying which display was better for the detection of small abnormalities in a reasonably complicated background. Receiver operating characteristic curves with location (LROC) were generated for each type of display for each observer. The data were analyzed by taking the LROC curves in pairs, for each observer, fitting I binary ROC curve using a model, and using both parametric and nonparametric statistical tests for the paired differences. It was found, in this study, that the black and white display was significantly "better" than the color display. There was no significant difference in the time required to make a decision between the two displays. The technique of using paired ROC curves is suggested as being an appropriate and powerful test for intercomparing different imaging procedures and techniques in medicine.     

Langmuir–Blodgett films of indandione-l,3 pyridinium betaine. II: Molecular structure and properties of monolayers; simulation and optical absorption data

The molecular structure and optical properties of a monolayer at the air/water interface of novel amphiphilic derivatives of indandione-1,3 pyridinium betaine (IPB) with different lengths of the aliphatic tail, namely C_1lIPB and C₁₇IPB, have been studied using optical absorption techniques and computer simulation approaches. The compression π-A isotherm of the C₁₇IPB monolayer and computer simulation of its molecular structure show that there may exist two energetically stable molecular configurations, one with antiparallel orientation of the dipole moments of the C₁₇IP ‘heads’ in the low-pressure region at π = 5–32 mN m^?1 and the second (after a distinct phase transition at π = 33 mN m^?1) with parallel orientation of the dipoles, with different tilt angles and areas per molecule. For C₁₁IPB only the first structural phase is observable. The compression-induced changes in spectral characteristics of the two structural phases go in diametrically opposite directions. In the low-pressure phase compression induces a red shift and an increase in intensity of the S₁ absorption band, while in the high pressure phase a blue shift and a decrease in the intensity of this band are observed. These spectral changes correlate reproducibly with the compression π-A isotherms. Measurements of absorption dichroism confirm the change in the tilt angle at the phase transition pressure. The compression-induced spectral changes have been substantiated by the results of quantum chemical calculations.     

Performance of channel coded noncoherent systems: modulation choice, information rate, and Markov chain Monte Carlo detection

This paper investigates performance of channel coded noncoherent systems over block fading channels. We consider an iterative system where an outer channel code is serially concatenated with an inner modulation code amenable to noncoherent detection. We emphasize that, in order to obtain near-capacity performance, the information rates of modulation codes should be close to the channel capacity. For certain modulation codes, a single-input single-output (SISO) system with only one transmit antenna may outperform a dual-input and single-output (DISO) system with two transmit antennas. This is due to the intrinsic information rate loss of these modulation codes compared to the DISO channel capacity. We also propose a novel noncoherent detector based on Markov Chain Monte Carlo (MCMC). Compared to existing detectors, the MCMC detector achieves comparable or superior performance at reduced complexity. The MCMC detector does not require explicit amplitude or phase estimation of the channel fading coefficient, which makes it an attractive candidate for high rate communication employing quadrature amplitude modulation (QAM) and for multiple antenna channels. At transmission rates of 1 ~ 1.667 bits/sec/Hz, the proposed SISO systems employing 16QAM and MCMC detection perform within 1.6-2.3 dB of the noncoherent channel capacity achieved by optimal input.