Modeling default behavior in the presence of information and its application to the route choice problem

A new approach for modeling default behavior is presented and applied to route choice behavior in the presence of information. It is based on the assumption that drivers follow their usual behavior pattern and modify it only if the information received differs substantially from their existing perceptions and knowledge. Default behavior is linked to the interactions between existing knowledge and new information. These interactions are modeled through measures of compatibility, and several measures are suggested and analyzed. The approximate-reasoning model, which was earlier suggested for modeling discrete choices made in the presence of information, is adapted to handle default behavior. The model is briefly presented and its implementation and calibration are discussed. Default behavior is implemented by discounting existing knowledge when it does not agree with the new information, and by discounting the new information when it does not significantly differ from existing knowledge. A small case study is conducted using a driver simulator to collect data from two types of drivers: familiar and unfamiliar. The results obtained provide interesting insights on the choice behavior of the sample population, and support a default type of behavior among the familiar drivers. ©1999 John Wiley & Sons, Inc.     

Visual tracking of hands, faces and facial features of multiple persons

This paper presents an integrated approach for tracking hands, faces and specific facial features (eyes, nose, and mouth) in image sequences. For hand and face tracking, we employ a state-of-the-art blob tracker which is specifically trained to track skin-colored regions. In this paper we extend the skin color tracker by proposing an incremental probabilistic classifier, which can be used to maintain and continuously update the belief about the class of each tracked blob, which can be left-hand, right hand or face as well as to associate hand blobs with their corresponding faces. An additional contribution of this paper is related to the employment of a novel method for the detection and tracking of specific facial features within each detected facial blob which consists of an appearance-based detector and a feature-based tracker. The proposed approach is intended to provide input for the analysis of hand gestures and facial expressions that humans utilize while engaged in various conversational states with robots that operate autonomously in public places. It has been integrated into a system which runs in real time on a conventional personal computer which is located on a mobile robot. Experimental results confirm its effectiveness for the specific task at hand.     

混合MIDC馈入下的工频变化量阻抗方向保护动作特性分析

交流电网故障引发线路换相换流器高压直流(Line Commutated Converter High Voltage Direct Current,LCC-HVDC)换相失败,改变了原有交流电网工频变化量方向保护动作特性。针对这一问题,建立了由电压源换流器高压直流(Voltage Source Converter HVDC,VSC-HVDC)系统与LCC-HVDC系统组成的混合多馈入直流(bybrid multi-infeed HVDC,HMIDC)输电系统模型,并与馈入同一交流电网的单条LCC-HVDC的交直流系统进行对比分析。结合分析工频变化量方向保护原理的特点,定量分析了在两种不同输电结构,同一换相失败情况下的等值工频变化量阻抗特性。基于PSCAD/EMTDC对两种不同结构的直流输电系统,以同一故障引发换相失败进行仿真分析,验证了理论分析的准确性和有效性。表明该HMIDC系统能改善LCC-HVDC换相失败对工频变化量方向保护的影响;理论分析方法为电网直流规划提供了评估依据。     

How Successful are Energy Efficiency Investments? A Comparative Analysis for Classification & Performance Prediction

Computational Economics - Increasing the financial institutions’ deployment of capital in energy efficiency investments remains still a challenge. The present article is intended to...     

Noise reduction capability of hybrid flax fabric-reinforced polypropylene-based composites

In recent years, natural fiber polymer composites have demonstrated great potential for reducing noise. This study reports sound transmission loss (STL) of hybrid flax fabric-reinforced polypropylene composites. The STL values were determined by the BSWA impedance tube and evaluated by ISO 10534 standard test procedure in the frequency range of 64 to 1600 Hz. Measurements show that the STL per areal density of flax/polypropylene is two times higher compared to aluminum. A noteworthy result is that upon hybridization with 13% carbon fibers (carbon-flax/polypropylene), the STL per areal density increases by 2.4 times. This study also presents the finite element (FE) simulation of sound transmission through the composites. Good agreement between FE predicted and experimentally measured STL is obtained. Moreover, parametric sensitivity studies are performed using the developed FE model to examine the effect of possible variation in the mechanical properties of the natural fiber composites on the STL performance. It is found that within 15% variation, no significant effect on STL is obtained and that STL is only sensitive to the in-plane elastic moduli.     

Generation of soliton and bound soliton pulses in mode-locked erbium-doped fiber laser using graphene film as saturable absorber

We report an observation of soliton and bound-state soliton in passive mode-locked fibre laser employing graphene film as a passive saturable absorber (SA). The SA was fabricated from the graphene flakes, which were obtained from electrochemical exfoliation process. The graphene flakes was mixed with polyethylene oxide solution to form a polymer composite, which was then dried at room temperature to produce a film. The film was then integrated in a laser cavity by attaching it to the end of a fibre ferrule with the aid of index matching gel. The fibre laser generated soliton pulses with a 20.7 MHz repetition rate, 0.88 ps pulse width, 0.0158 mW average output power, 0.175 pJ pulse energy and 18.72 W peak power at the wavelength of 1564 nm. A bound soliton with pulse duration of ~1.04 ps was also obtained at the pump power of 110.85 mW by carefully adjusting the polarization of the oscillating laser. The formation of bound soliton is due to the direct pulse to pulse interaction. The results show that the proposed graphene-based SA offers a simple and cost efficient approach of generating soliton and bound soliton in mode-locked EDFL set-up.     

Depth-of-Interaction Compensation Using a Focused-Cut Scintillator for a Pinhole Gamma Camera

Preclinical SPECT offers a powerful means to understand the molecular pathways of drug interactions in animal models by discovering and testing new pharmaceuticals and therapies for potential clinical applications. A combination of high spatial resolution and sensitivity are required in order to map radiotracer uptake within small animals. Pinhole collimators have been investigated, as they offer high resolution by means of image magnification. One of the limitations of pinhole geometries is that increased magnification causes some rays to travel through the detection scintillator at steep angles, introducing parallax errors due to variable depth-of-interaction in scintillator material, especially towards the edges of the detector field of view. These parallax errors ultimately limit the resolution of pinhole preclinical SPECT systems, especially for higher energy isotopes that can easily penetrate through millimeters of scintillator material. A pixellated, focused-cut (FC) scintillator, with its pixels laser-cut so that they are collinear with incoming rays, can potentially compensate for these parallax errors and thus improve the system resolution. We performed the first experimental evaluation of a newly developed focused-cut scintillator. We scanned a Tc-99m source across the field of view of pinhole gamma camera with a continuous scintillator, a conventional "straight-cut" (SC) pixellated scintillator, and a focused-cut scintillator, each coupled to an electron-multiplying charge coupled device (EMCCD) detector by a fiber-optic taper, and compared the measured full-width half-maximum (FWHM) values. We show that the FWHMs of the focused-cut scintillator projections are comparable to the FWHMs of the thinner SC scintillator, indicating the effectiveness of the focused-cut scintillator in compensating parallax errors.     

Study of performance parameter optimisation of resorption cogeneration utilising heat and mass recovery

In the present scenario, one of the global issues is energy crisis, and it is found that effective utilisation of low-grade waste heat energy as potential solution to this crisis, which could be easily used with the cogeneration plant. In this work, an attempt is made to implement a mass and heat recovery system with a basic resorption cogeneration unit. Low-grade solar energy is utilised by the expansion machine and ammonia resorption unit, and the plant produces a dual output of cooling effect and electricity. The problem of variation reaction rate is sorted out by introducing a buffer prior to the expansion machine; similarly, the deficiency of chemisorption is overcome by a pair of resorption cycles. Under various operating conditions, six resorption pairs were analysed and it was found that the SrCl₂–MnCl₂ pair to be the best pair. Exergy analyses were made using the equation solver.     

Recent progress in silicon-based solid-state solar cells

Silicon (Si)-based solar cells constitute about 90% of the photovoltaic (PV) market, and a drastic reduction in module cost and significant improvement in PV performance have been observed since its first inception in 1941. This article aims to present the comprehensive review of prominent advancements enacted in Si solar cells after the year 2000. Monocrystalline Si solar cell has been the matured technology with the record efficiency (η) of 26.6% achieved so far. As the drive to push η around 30% Schokley–Quiesser limit is foreseeable in the near future, PV community is actively striving to fabricate efficient yet cost-effective devices. Polycrystalline Si solar cells contain small-sized grains, and efforts are underway to enhance the η beyond 21.9% by controlling the recombination at grain boundaries, optimising the passivated interfaces and deposition process. Thin-film amorphous Si technology proffers low-cost fabrication process and η of 13.6% has been recorded for a multijunction solar cell. Employment of sophisticated nanowire-based light trapping schemes and dopant-free carrier-selective layers along with the development of hybrid solar cells of organic and Si materials are among the emerging research trends for Si solar cells.