55 research outputs found
Oscylacje na ciekłej elektrodzie galowej
No full textDas Phänomen des pulsierenden Quecksilberherzens ist seit etwa 200 Jahren bekannt. In
einem kürzlich erschienenen Artikel konnten wir eine vollständige Erklärung dieses faszinierenden
Phänomens liefern, in der wir uns ausschließlich auf das Phänomen der Elektrokapillarität stützen.
Ausgehend von den Ergebnissen zum pulsierenden Quecksilberherz untersuchten wir das
Galliumsystem. Es war anzunehmen, daß auch in diesem System sichtbare Oszillationen
hervorgerufen werden können, deren ursächliches Zustandekommen ebenso mithilfe der
Elektrokapillarität erklärt werden kann. Dennoch mußten die Oszillationsbedingungen gänzlich
andere sein, da Gallium (und seine Verbindungen) andere elektrochemische Potentiale ausbildet als
Quecksilber. Mit der Zugrundelegung der Theorie der Elektrokapillarität gelang es, die
Bedingungen für das pulsierende Galliumherz unter verschiedenen Bedingungen zu finden und eine
befriedigende Erklärung der Vorgänge mithilfe der Elektrokapillarität zu geben. Darüber hinaus
fanden wir unerwartet eine völlig neue Oszillationsart, deren Zustandekommen keinerlei weitere
Elektroden erfordert. Dieses eigenartige, vielleicht als „Eigenoszillation“ zu bezeichnende
Phänomen, wird in naher Zukunft untersucht werden.The phenomenon of the so-called beating mercury heart is known since about 200 years.
We recently inspected it and gave a satisfying explanation by using only the phenomenon
of electrocapillarity. Turning out from this phenomenon of the beating mercury heart we
examined the gallium system. Complying with the terms from the known system it was to be
expected to obtain visible electrocapillaric caused oscillation likewise. Nevertheless the terms
of obtaining oscillations needed to be completely different because of the rearranged
electrochemical potential from gallium compared to the electrochemical potential from
mercury. Applying the base of electrocapillarity it succeed to find out the terms of oscillation from the beating gallium heart under various preconditions and to give a satisfying explanation
by using the phenomenon of electrocapillarity. Moreover there was discovered a new sort of
oscillation without use of any additional electrode material. These peculiar “self-driven
oscillations” will have to be examined in the near future.Zjawisko oscylacji kropli rtęci znane jako „bijącego serce rtęci” zaobserwowano już prawie
200 lat temu. W pracy podjęto udaną próbę scharakteryzowania, w podobny sposób zachowania się
ciekłego galu w wodnych roztworach różnych elektrolitów o różnych stężeniach. W układzie
pomiarowym zastosowano elektrodę platynową jako elektrodę polaryzującą, natomiast jako
elektrody pomocnicze stosowano aluminium, platynę lub czerń platynową. Krzywe polaryzacyjne
analizowano za pomocą odpowiednio zaprogramowanego komputera. Krzywa elektrokapilarna,
wykazuje maksimum w potencjale ładunku zerowego, a określonym wartościom potencjałów
polaryzacji towarzyszą oscylacje potencjału elektrody galowej, w dużym stopniu analogiczne do
znanych oscylacji kropli rtęci. Oscylacje kropli galowej wykazują większą częstotliwość w
porównaniu z rtęcią, a towarzyszący im tzw. potencjał ciszy jest zbliżony do potencjału ładunku
zerowego galu. Zjawisko to zostało wytłumaczone zróżnicowaną gęstością ładunku wewnątrz
elektrody i w otaczającym ją elektrolicie. Powoduje to cykliczne ładowanie-rozładowanie tak
wytworzonego kondensatora kulistego, co uwidocznione jest w cyklicznych impulsach
potencjałowych, których kształt zależy od rodzaju i stężenia elektrolitu.Zadanie pt. Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę
Nierenarterienstenose: Intervention oder medikamentöse Behandlung?
No full textBackground and objective: Angioplasty in patients with renal artery stenosis aims at reducing blood pressure and at improving kidney function. Its efficacy has however been questioned by recent published data. It was the aim of this retrospective study to compare angioplasty with medical treatment in an unselected patient population. Methods: Data on 109 patients were retrospectively anlysed. This cohort included all those patients admitted to the Lippe-Detmold Hospital between 1992 and 2008 for renal artery stenosis. The data included blood pressure, creatinine-based calculated glomerular filtration rate (cGFR), any renal dialysis, cardiovascular risk factors, events and survival time after transluminal renal angioplasty or drug treatment, respectively. Results: Patients who had undergone angioplasty were younger (p = 0.04), had less cardiovascular co-morbidity (p < 0.01), but a higher degree of stenosis (p < 0.01). After a median follow-up of 32.5 (angioplasty) and 36.0 months (drug treatment), respectively, a significant decrease of cGFR was recorded in drug treated patients (- 16.2 ml/min, 95%, CI - 25.7 to - 6.7) but not in the angioplasty group (- 4.5 ml/min, 95%, CI - 13.5 to 4.5). There were no other significant differences were not observed. Conclusion: Younger patients with a high degree of renal artery stenosis but without generalized atherosclerosis more frequently underwent angioplasty in clinical practice. The smaller post-angioplasty reduction in the loss of renal function in this group needs to be validated in a prospective, randomized study
A Genetic Algorithm with Tournament Selection for Automated Testing of Satellite On-board Image Processing
No full textIn the satellite domain, on-board image processing technologies are subject to extremely strict requirements with respect to reliability and accuracy in hard real-time. In this paper, we address the problem of automatically selecting test cases from a huge input domain that are specifically tailored to provoke mission-critical behavior of satellite on-board image processing applications. Due to the large input domain of such applications, it is infeasible to exhaustively execute all possible test cases. Moreover, the high number of input parameters and complex computations make it difficult to find specific test cases that cause mission-critical behavior. To overcome this problem, we define a test approach that is based on a genetic algorithm combined with input parameter partitioning. We partition the input parameters into equivalence classes to automatically generate a reduced search space with complete coverage of the input domain. Based on the reduced search space, we run a genetic algorithm to automatically select test cases that provoke worst case execution times and inaccurate results of the satellite on-board image processing application. For this purpose, we define a two-criteria fitness function and evaluate two different selection methods with a case study from the satellite domain. We show the efficiency of our test approach on experimental results from the Fine Guidance System of the ESA medium-class mission PLATO
Automated Test Generation for Satellite On-Board Image Processing
No full textOn-board image processing technologies in the satellite domain are subject to extremely strict requirements with respect to reliability and accuracy in hard realtime. Due to their large input domain, it is infeasible to exhaustively execute all possible test cases. Furthermore, because of their complex computations, it is difficult to find specific test cases that provoke mission-critical behavior.
To overcome these problems, we first define a test approach that efficiently and systematically captures the input domain of satellite on-board image processing applications. We present a dedicated partitioning into equivalence classes for each input parameter. As a result, our approach systematically reduces the number of test cases. Moreover, we define novel multidimensional coverage criteria to assess a given test suite for its coverage on the input domain. We present a test generation algorithm that automatically inserts missing test cases into the given test suite based on our multidimensional coverage criteria. This results in a reasonably small test suite that covers the whole input domain of satellite on-board image processing applications.
Second, we define a test approach that automatically searches for test cases that are specifically tailored to provoke mission-critical behavior of satellite on-board image processing applications. For that, we present a novel genetic algorithm. We define a two-criteria fitness function that is based on the execution time and mathematical accuracy of the application under test. Therefore, our algorithm automatically selects test cases that provoke worse execution times and inaccurate results of the satellite on-board image processing application.
We investigate the efficiency of our approaches on the PLAnetary Transits and Oscillation of stars (PLATO) Fine Guidance System (FGS) algorithm. This is a satellite on board algorithm that calculates the high-precision attitude of the spacecraft. The experimental results show that our first approach efficiently and systematically generates a test suite. This suite completely covers the input domain with respect to our multidimensional coverage criteria. This test suite has a higher error-detection capability than a randomly generated test suite. Therefore, our test approach increases the test efficiency and quality. Furthermore, our genetic algorithm automatically finds test cases that provoke longer execution times and less accurate results when using the generated test suite from the first approach as search space than using a randomly generated test suite. Hence, our genetic approach improves a given test suite to support robustness testing.
As a summary, the combination of our approaches increases the efficiency and effectiveness of the test process for satellite image processing applications
Analysis of cell to module losses and UV radiation hardness for passivated emitter and rear cells and modules
No full textThis work presents an experimental analysis and analytical modeling of cell to module losses for passivated emitter and rear cells (PERC), which enables to build a PERC solar module with a record efficiency of 20.2%. Further, it examines the ultraviolet radiation hardness of solar modules employing crystalline silicon (c-Si) solar cells featuring dielectric passivation layers.
Passivated emitter and rear cells are on the transition to mass production and expected to become the dominating c-Si solar cell technology in terms of market share in the next few years. Thus, it is of major importance to implement these high efficiency PERC into high efficiency solar modules. When transferring solar cells into a solar module additional recombination, optical, and resistive losses reduce the power of the solar module compared to the power of the solar cell, termed cell to module losses. In this work we study the individual recombination, optical, and resistive characteristics of various cell and module test samples. Based on our experimental results we develop an analytical model that allows to simulate the cell to module losses and reproduces the measurement results of test modules within the measurement uncertainty. We show that a reduction of the cell to module losses requires an adaptation of both, the solar cell as well as the solar module components. We employ the analytical model to improve the cell's front metalization, cell interconnection, light harvesting and cell spacing to reduce the cell to module losses for passivated emitter and rear cells and build an industrial like 60-cell sized solar module with a record power conversion efficiency of 20.2%.
Besides the efficiency, the long-term reliability of solar modules is crucial and a performance degradation of new promising technologies can impair their importance for the industry. The application of new metalization pastes that enable to contact lowly doped emitters, increases the spectral response of a PERC in the UV wavelength range. This requires the application of new encapsulation materials with enhanced UV transmittance for PERC solar modules. We report on the UV radiation hardness of solar modules featuring PERC with various silicone nitride passivation layers and employing different encapsulation polymers. Our results reveal that employing polymers with increased UV transparency results in a solar module power loss of 14%. We show that the degradation in module power is due to a reduction of the module's open circuit voltage. This loss is related to an increased charge carrier recombination in the cell, which we ascribe to a degradation of the amorphous silicon nitride (SiN) surface passivation. We develop a novel analytical model to describe the effect of high energetic photons on the solar module performance with a critical energy to deteriorate the surface passivation
Decision - Making At The End Of Life and The Incompetent Patient: A Comparative Approach
No full textThis article adopts a comparative approach to assessing the manner in which decisions to withdraw/withhold life-prolonging treatment are made in relation to previously competent patients without a legally effective advance directive or a proxy decision-maker, considering the approaches adopted by the courts in England & Wales and Germany: the best interests and ‘presumed will’ approaches respectively. Due to the inherent drawbacks associated with each approach it is concluded that the best way forward would be for both jurisdictions to adopt a mixed approach, allowing the autonomy model to temper the best interests approach, recognising that the patient is an individual rather than simply an object of concern. A précis of this article was published in the French journal Risques & Qualité en Milieu de Soins in its section ‘Dans la presse internationale,’ December 2004
Equivalence Class Definition for Automated Testing of Satellite On-Board Image Processing
No full textOn-board image processing technologies in the satellite domain are subject to strict requirements with respect to reliability and accuracy in hard real-time. Due to the large input domain of such processing technologies it is impracticable or even impossible to execute all possible test cases. As a solution we define a novel test approach that efficiently and systematically captures the input domain of satellite on-board image processing applications. We first partition each input parameter into equivalence classes. Based on these equivalence classes we define multidimensional coverage criteria to assess the coverage of a given test suite on the whole input domain. Finally, our test generation algorithm automatically inserts missing but relevant test cases into the given test suite such that our multidimensional coverage criteria are satisfied. As a result we get a reasonably small test suite that covers the complete input domain. We demonstrate the effectiveness of our approach with experimental results from the ESA medium-class mission PLATO
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