Die Welt 1250-1500: vormoderne Verflechtungen von Dschingis Khan bis Christoph Columbus

The period between 1250 and 1500 was decisive for modern world history. For the first time a worldwide commercial system arose, which included large parts of Asia, Africa and Europe. On the other the Mongol expansion and the Black Death affected large parts of the Old World. China started with a maritime expansion but later gave up this policy. In the world of Islam new major emires were created. This article gives a survey of the heterogeneous yet strongly interconnected world of the period which is known in Europe as the Late Middle Ages

LOAD NOISE INCREASE OF TRANSFORMERS BY LOAD HARMONICS

Electrical power and distribution transformers in field operation regularly show significant deviation in the load noise level in comparison to the sound measurements in the test field of the manufacturer where controlled and standardised measurement conditions apply. The main reason therefore are (a) the changed acoustical ambient conditions on-site caused by sound reflection and diffraction effects of nearby obstacles; (b) changed structural and acoustical resonances, and (c) the different principal operation conditions on-site. Whereas at the factory tests a pure sinusoidal current with short-circuited secondary winding is applied for load noise determination, transformers on-site operate at changed load power factors (phase angle between voltage and load-current), loading beyond the rated power (overload, partial load) as well as harmonics in the load-current. Harmonic components in the power grid are caused primarily by nonlinear loads and by the nonlinear transfer characteristic of the power grid. Any electrical device which shows a nonlinear consumption of active power or a nonlinear change of the source impedance draws a distorted current waveform even if the supply voltage is sinusoidal. With the growing use of electrical and electronic devices, distorted waveforms in power supply grid by harmonics have been largely increased within the past years. Devices like variable speed drives, six-pulse bridge rectifiers used in power electronics, and discharge lamps draw a non-sinusodial but pulsating current. Whereas most electric devices generate solely odd harmonics, some devices with fluctuating power consumption generate odd, even and also interharmonic currents [1]. Load noise is generated by electromagnetic forces acting on transformer windings. The forces are proportional to the square of the load-current (Section 2.2). This quadratic response behaviour generates winding vibrations at frequencies beyond the power frequency. In case of harmonics in the load-current, the resulting magnetic force and noise components have harmonics as well- with a more complex frequency spectrum. The related increase of the load noise level must be considered in the estimation of the total noise level of transformers under real load conditions. The question arise how to predict the resulting noise level at these loading conditions to guarantee the maximum allowed sound level at the transformer site as requested by legislative regulations or the owners specification. Starting from basic principles, we describe and quantify the generation of harmonics in winding forces, winding vibrations and load noise of electrical transformers caused by load harmonics. A calculation scheme for a fast and practically accurate estimation of the increase in the load noise level for a given load spectrum presented. The effects of A-weighting and frequency-dependent sound radiation efficiency of transformers to the total noise level are discussed. Finally, three practical examples are given

LOAD NOISE INCREASE OF TRANSFORMERS BY LOAD HARMONICS

Electrical power and distribution transformers in field operation regularly show significant deviation in the load noise level in comparison to the sound measurements in the test field of the manufacturer where controlled and standardised measurement conditions apply. The main reason therefore are (a) the changed acoustical ambient conditions on-site caused by sound reflection and diffraction effects of nearby obstacles; (b) changed structural and acoustical resonances, and (c) the different principal operation conditions on-site. Whereas at the factory tests a pure sinusoidal current with short-circuited secondary winding is applied for load noise determination, transformers on-site operate at changed load power factors (phase angle between voltage and load-current), loading beyond the rated power (overload, partial load) as well as harmonics in the load-current. Harmonic components in the power grid are caused primarily by nonlinear loads and by the nonlinear transfer characteristic of the power grid. Any electrical device which shows a nonlinear consumption of active power or a nonlinear change of the source impedance draws a distorted current waveform even if the supply voltage is sinusoidal. With the growing use of electrical and electronic devices, distorted waveforms in power supply grid by harmonics have been largely increased within the past years. Devices like variable speed drives, six-pulse bridge rectifiers used in power electronics, and discharge lamps draw a non-sinusodial but pulsating current. Whereas most electric devices generate solely odd harmonics, some devices with fluctuating power consumption generate odd, even and also interharmonic currents [1]. Load noise is generated by electromagnetic forces acting on transformer windings. The forces are proportional to the square of the load-current (Section 2.2). This quadratic response behaviour generates winding vibrations at frequencies beyond the power frequency. In case of harmonics in the load-current, the resulting magnetic force and noise components have harmonics as well- with a more complex frequency spectrum. The related increase of the load noise level must be considered in the estimation of the total noise level of transformers under real load conditions. The question arise how to predict the resulting noise level at these loading conditions to guarantee the maximum allowed sound level at the transformer site as requested by legislative regulations or the owners specification. Starting from basic principles, we describe and quantify the generation of harmonics in winding forces, winding vibrations and load noise of electrical transformers caused by load harmonics. A calculation scheme for a fast and practically accurate estimation of the increase in the load noise level for a given load spectrum presented. The effects of A-weighting and frequency-dependent sound radiation efficiency of transformers to the total noise level are discussed. Finally, three practical examples are given

Evaluation eines multimedialen Expertensystems für Laienhelfer

One of the most important lacks in preclinical care of emergency victims is insufficient quality of Basic Life Support provided by layhelpers. Outcome of emergency patients could be significantly enhanced by improving BLS skills of the public. This work evaluated an expert system for mobile multimedia devices consisting of a decision making aid component and a direct instruction progam part. The use of the expert system significantly improved quality of BLS provided by layhelpers

Über die Bedeutung von Kapitaleinkommen für die Einkommensverteilung Österreichs

(no abstract available

Ohne Priorität für Kampf gegen Arbeitslosigkeit keine Entspannung auf dem Arbeitsmarkt. Zur neuen WIFO-Prognose

Die neue Wirtschaftsprognose des WIFO erwartet für das Jahr 2021 einen sehr bescheidenen Anstieg der Wirtschaftsleistung (BIP) um 1,5 Prozent bis 2,3 Prozent – trotz des tiefen Einbruchs im Jahr 2020. Österreich hinkt auch im europäischen Vergleich nach, besonders gegenüber Deutschland. Das liegt nicht an Warenexport und Güterproduktion, sondern am hohen Anteil des Tourismus, am schlechten Pandemie-Management und an den ungenügenden Maßnahmen der Regierung gegen die sozialen Folgen der Krise. Die Forderung nach einer mutigen Arbeitsmarkt- und Investitionsoffensive bleibt dringend

Metaphorical Visualization: Mapping Data to Familiar Concepts

We present a new approach to visualizing data that is well-suitedfor personal and casual applications. The idea is to map the data toanother dataset that is already familiar to the user, and then relyon their existing knowledge to illustrate relationships in the data.We construct the map by preserving pairwise distances or by maintaining relative values of specific data attributes. This metaphoricalmapping is very flexible and allows us to adapt the visualization toits application and target audience. We present several exampleswhere we map data to different domains and representations. Thisincludes mapping data to cat images, encoding research interestswith neural style transfer and representing movies as stars in thenight sky. Overall, we find that although metaphors are not as accurate as the traditional techniques, they can help design engagingand personalized visualizations.<br/