Search results for "VOLTAGE"

Performance assessment of field deployed multi-crystalline PV modules in Nordic conditions

2019

This paper presents an investigation of data monitoring quality and evaluation of performance degradation of four different multi-crystalline silicon (mc-Si) photovoltaic (PV) modules installed in the higher latitude conditions in southern Norway. Degradation of each module has been investigated in terms of degradation of short-circuit current (I SC ), open-circuit voltage (V OC ), fill factor (FF) and maximum power (P MPP ). The analysis for the period of monitoring data from 2014 to 2018 show no considerable module degradation compared to the standard degradation rate of all parameters. The statistical analysis of I SC shows an average degradation of 0.17% for all modules. Spectral correc…

A new analytical solar cell I–V curve model

2011

Abstract A simple mathematical equation that can represent empirical I–V curves of individual solar cells, systems of solar cells and modules has been found. The basic model is determined by four parameters: the open circuit voltage, the short circuit current and two shape parameters. With the four parameters determined, the complete current–voltage curve, the fill factor and the maximum power point are given by simple analytical functions. The model is valid both in the positive and the negative (dark condition) voltage range. Several simple examples demonstrate some of the potential of the model. Due to its mathematical simplicity, it is suggested that the model will be suitable for analy…

A low cost and easy re-configurable instrument for power quality survey

2004

In this document the development of a low cost and user friendly PC-based instrument for power quality measurement is proposed, according to IEC 61000-4-7 and standard IEC 61000-4-30. It is an easily re-configurable instrument able to measure harmonics, interharmonics and amplitude disturbances and supply unbalance. In order to verify its accuracy, the instrument has been tested according standard test procedures, by means of a built-up calibration test bench.

On the methodologies for the calibration of static electricity meters in the presence of harmonic distortion

2010

This paper is focused on the problems related to the calibration of static electricity meters with nonsinusoidal test waveforms. This is an up-to-date issue since the harmonic distortion levels are ever increasing, especially in low-voltage power systems, and in such conditions the performances of the modern static electricity meters can be negatively affected, depending on the implemented measurement algorithm. Thus it is important to test the meters with nonsinusoidal waveforms. The paper analyzes the problems related to both the choice of the test signals to be used for calibration and the implemented metric, with a particular focus on the reactive energy meters. The analysis is supporte…

Inhibitoren der Korrosion 28 (1). 2-Aminopyrimidin (2-AP) als an Inhibitor der the Korrosion des Kupfers in Salzlösungen unter Sauerstoff

1982

2-Aminopyrimidin ist der z. Z. beste Inhibitor der Korrosion von Kupfer unter Standardbedingungen. Mit den aus der Oberflache der Kupferprobe austretenden oder gebildeten Cu1+-Ionen baut sich eine Schutzschicht auf. Die Ausbildung dieser Deckschicht wird studiert als Funktion: (a) der Konzentration an 2-AP und der Cu2+-Ionen, (b) der Stromungsgeschwindigkeit und (c) in Abhangigkeit von der Art der Anionen im korrosiven Medium. Ruhepotential-Zeit-Messungen, Strom-Spannungskurven, Polarisationswiderstandskurven und Halteversuche, ohne und mit 2-AP sowie ohne und mit Cu2+-Ionen vermitteln einen Einblick in den Aufbau der Deckschicht. Inhibiors of corrosion 28 (1). 2-Aminopyrimidine (2-AP) as a…

Realizzazione di un banco di misura e di un modello in Simulink per la ricerca e la caratterizzazione di reti di accoppiamento per la trasmissione di…

2010

Campagna di misure sulla rete elettrica dell’isola di Favignana per la caratterizzazione di reti di accoppiamento per la trasmissione di segnali su c…

2010

Two Structurally Distinct Pathways for the Voltage-Sensing S4 Helices

2010

In voltage-dependent ion channels, the movement of the voltage-sensing S4 helices produces gating currents. The charge displaced as a function of the membrane potential (Q-V) is well described by a sequential two-state Boltzmann relation, indicating that there are at least two steps of gating charge movement from their Resting state to the Active state. In addition, it has been shown that at a maintained positive potential, the S4 helices of voltage-gated Na, Ca and K channels and the voltage sensitive phosphatase Ci-VSP, undergo a slower secondary conformational transition stabilizing the sensor in a Relaxed (inactivated) state. From the Relaxed state, the Q-V relation exhibits a strong sh…

Nonlinear conductance and heterogeneity of voltage-gated ion channels allow defining electrical surface domains in cell membranes

2015

Abstract The membrane potential of a cell measured by typical electrophysiological methods is only an average magnitude and experimental techniques allowing a more detailed mapping of the cell surface have shown the existence of spatial domains with locally different electric potentials and currents. Electrical potentials in non-neural cells are regulated by the nonlinear conductance of membrane ion channels. Voltage-gated potassium channels participate in cell hyperpolarization/depolarization processes and control the electrical signals over the cell surface, constituting good candidates to study basic biological questions on a more simplified scale than the complex cell membrane. These ch…

Origin of impulse initiation in the slowly adapting stretch receptor of the crayfish

1974

Characteristic for the crayfish stretch receptor is a gradual decrease in axon diameter up to a stretch of axon about 350 μm away from the soma-axon border. In response to depolarizing currents applied at different positions along the axon this stretch of axon can be localized as the most excitable membrane region. When depolarizing current steps of 10–25 nA intensity are injected into the soma the first impulse is always triggered in the soma (due to sudden rise in the membrane potential) while the second impulse originates at the axon region of highest escitability. As the intensity of the stimulus is increased the site of impulse initiation along the axon shifts nearer to the receptor so…