50,246 research outputs found

    Solving congestion (when we must not build roads, increase spending, lose votes, damage the economy or harm the environment, and will never find equilibrium)

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    An account of the development of transport and traffic policy over the last 30 years, with suggestions for the future constraints and objective

    Compensation of the skin effect in low-frequency potential drop measurements

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    Potential drop measurements are routinely used in the non-destructive evaluation of component integrity. Potential drop measurements use either direct current (DC) or alternating current (AC), the latter will have superior noise performance due to the ability to perform phase sensitive detection and the reduction of flicker noise. AC measurements are however subject to the skin effect where the current is electromagnetically constricted to the surface of the component. Unfortunately, the skin effect is a function of magnetic permeability, which in ferromagnetic materials is sensitive to a number of parameters including stress and temperature, and consequently in-situ impedance measurements are likely to be unstable. It has been proposed that quasi-DC measurements, which benefit from superior noise performance, but also tend to the skin-effect independent DC measurement, be adopted for in-situ creep measurements for power station components. Unfortunately, the quasi-DC measurement will only tend to the DC distribution and therefore some remnant sensitivity to the skin effect will remain. This paper will present a correction for situations where the remnant sensitivity to the skin effect is not adequately suppressed by using sufficiently low frequency; the application of particular interest being the in-situ monitoring of the creep strain of power station components. The correction uses the measured phase angle to approximate the influence of the skin effect and allow recovery of the DC-asymptotic value of the resistance. The basis of the correction, that potential drop measurements are minimum phase is presented and illustrated on two cases; the creep strain sensor of practical interest and a conducting rod as another common case to illustrate generality. The correction is demonstrated experimentally on a component where the skin effect is manipulated by application of a range of elastic stresses

    Chasing the Chatbots: Directions for Interaction and Design Research

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    Big tech-players have been successful in pushing the chatbots forward. Investments in the technology are growing fast, as well as the number of users and applications available. Instead of driving investments towards a successful diffusion of the technology, user-centred studies are currently chasing the popularity of chatbots. A literature analysis evidences how recent this research topic is, and the predominance of technical challenges rather than understanding users’ perceptions, expectations and contexts of use. Looking for answers to interaction and design questions raised in 2007, when the presence of clever computers in everyday life had been predicted for the year 2020, this paper presents a panorama of the recent literature, revealing gaps and pointing directions for further user-centred research

    Science and Technology Development and Promotion in the Private Sector: Some Issues and Recommendations for Policy Research

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    This article is part of the seminar on “Science Technology Policies in the Philippines" jointly sponsored by PIDS and DOST on May 5, 1989. It emphasizes the need for scientific research specifically the need for dissemination and utilization of information technology.science and technology, information technology (IT), technological innovation

    Science and Technology Development and Promotion in the Private Sector: Some Issues and Recommendations for Policy Research

    Get PDF
    This article is part of the seminar on “Science Technology Policies in the Philippines" jointly sponsored by PIDS and DOST on May 5, 1989. It emphasizes the need for scientific research specifically the need for dissemination and utilization of information technology.science and technology, information technology (IT), technological innovation

    Rumpel-Leede phenomenon in a hypertensive patient due to mechanical trauma: a case report.

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    In this report, we present an interesting case of a patient with Rumpel-Leede phenomenon, a rare occurrence that can result in significant delays in medical treatment. This phenomenon is characterized by the presence of a petechial rash that results from acute dermal capillary rupture. In our patient, it occurred secondary to raised pressure in the dermal vessels caused by repeated inflation of a sphygmomanometer cuff. Contributory factors in Rumpel-Leede phenomenon include prevalent conditions such as diabetes mellitus, hypertension, thrombocytopenia, chronic steroid use, antiplatelets, and anticoagulants.A 58-year-old Russian woman with diabetes and hypertension presented to our hospital with a non-ST elevation myocardial infarction, and she subsequently developed a petechial rash on her distal upper limbs. A vasculitic screen was performed, with normal results.Given the timing and distribution of the rash, it was felt that this was an example of Rumpel-Leede phenomenon in a susceptible individual. This is an important diagnosis to be aware of in patients with vascular risk factors presenting for acute medical care who subsequently develop a petechial rash

    A facile route to a novel aza-crown ether incorporating three thiophene moieties

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    The preparation of the first of a novel type of large thiophene-containing aza-crown ether is reported. The macrocycle is synthesised by linking a 3,4-dialkoxythiophene moiety with two 3-hydroxythiophene units and ring closure is effected by reaction with piperazine via the Mannich reaction
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