scholarly journals Regular and Irregular Performance Variation of Module String and Occurred Conditions for Potential Induced Degradation-Affected Crystalline Silicon Photovoltaic Power Plants

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4230 ◽  
Author(s):  
Jingsheng Huang ◽  
Yaojie Sun ◽  
He Wang ◽  
Junjun Zhang
Keyword(s):  
Power Plants ◽  
Crystalline Silicon ◽  
Sufficient Conditions ◽  
Ethyl Vinyl ◽  
Climate Conditions ◽  
Photovoltaic Power ◽  
Performance Variation ◽  
Current Voltage ◽  
Almost All ◽  
Necessary And Sufficient

Potential induced degradation (PID) leads to power degradation, and reduces durability and reliability of solar modules. However, this problem has not been thoroughly solved so far. The results from interlaboratory and field study show contradictory fault phenomenon for PID. In this paper, PID of crystalline silicon photovoltaic power plants distributed in various climate conditions was investigated. These photovoltaic power plants consist of two types of crystalline silicon solar modules, which cover almost all kinds of front glass, ethyl vinyl acetate (EVA) and backsheet available commercially. It was found that only a few of power plants were affected by PID. By measuring current voltage characteristics of PID-affected solar modules, the real faults phenomenon was uncovered and classified into regular and irregular power degradation in a module string. The results obtained in this work show that the negative potential caused by high system voltage and stacking faults are necessary and sufficient conditions for PID occurrence for the first time. The anomalous power degradation is related to the stacking fault, which appears randomly during the crystal growth.

scholarly journals REDUCING CLIMATE CHANGE BY INSTALLING A NEW PHOTOVOLTAIC POWER PLANT IN BULGARIA

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Plamen Tsankov
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Crystalline Silicon ◽  
Electrical Power ◽  
Operating Characteristics ◽  
Pv System ◽  
Photovoltaic Materials ◽  
Photovoltaic Power ◽  
Copper Indium ◽  
Simultaneous Testing

Three new roof-mounted 10 kWp grid-connected photovoltaic (PV) power plants have been constructed in the Technology Park at the Technical University of Gabrovo, Bulgaria, as part of a project "Competence Center – Intelligent Mechatronic, Eco, and Energy Saving Systems and Technologies". Three different PV modules types have been used: monocrystalline silicon (mono-Si), cadmium telluride (CdTe), and copper indium gallium selenide (CIGS). New three power plants, together with the existing amorphous silicon and poly-crystalline silicon photovoltaic power plants at the TU-Gabrovo enhanced simultaneous testing of five different photovoltaic materials. A small 500 Wp mono-Si photovoltaic thermal hybrid solar collectors (PVT) PV system has also been constructed. The power plants feature a monitoring system for the meteorological and electrical operating parameters, which measures, displays, and stores data on solar radiation, temperature, wind speed, currents, voltages, and electrical power of each power plant. PV plants components' technical characteristics are given in the paper. The schemes describing the basic wiring diagram, disposition of the three PV subsystems on the roof of the building at the technology center have also been presented. The initial comparative software data for monitoring of meteorological and electrical operating characteristics of the three different types of PV subsystems are shown as well. According to the specific ecological equivalent of energy resources and energy for the region of Bulgaria, the data are presented on the saved CO2 emissions from the avoided production and transmission of electricity owing to the operation of photovoltaic power plants.

scholarly journals XVI. Functions of positive and negative type, and their connection the theory of integral equations

1909 ◽  
Vol 209 (441-458) ◽  
pp. 415-446 ◽  
Keyword(s):  
Continuous Function ◽  
Early Stage ◽  
Sufficient Conditions ◽  
Slight Modification ◽  
Negative Type ◽  
Original Plan ◽  
Definition Of ◽  
Almost All ◽  
Necessary And Sufficient

The present memoir is the outcome of an attempt to obtain the conditions under which a given symmetric and continuous function k ( s, t ) is definite, in the sense of Hilbert. At an early stage, however, it was found that the class of definite functions was too restricted to allow the determination of necessary and sufficient conditions in terms of the determinants of § 10. The discovery that this could be done for functions of positive or negative type, and the fact that almost all the theorems which are true of definite functions are, with slight modification, true of these, led finally to the abandonment of the original plan in favour of a discussion of the properties of functions belonging to the wider classes. The first part of the memoir is devoted to the definition of various terms employed, and to the re-statement of the consequences which follow from Hilbert’s theorem.

scholarly journals Certain results on invariant submanifolds of an almost Kenmotsu $$(\kappa ,\mu ,\nu )$$-space

2021 ◽  
Author(s):  
Mehmet Atc̣eken
Keyword(s):  
Sufficient Conditions ◽  
Riemannian Curvature ◽  
Invariant Submanifold ◽  
Totally Geodesic ◽  
Ambient Manifold ◽  
Riemannian Curvature Tensor ◽  
Nullity Distribution ◽  
Invariant Submanifolds ◽  
Almost All ◽  
Necessary And Sufficient

AbstractIn the present paper, we study invariant submanifolds of almost Kenmotsu structures whose Riemannian curvature tensor has $$(\kappa ,\mu ,\nu )$$ ( κ , μ , ν ) -nullity distribution. Since the geometry of an invariant submanifold inherits almost all properties of the ambient manifold, we research how the functions $$\kappa ,\mu $$ κ , μ and $$\nu $$ ν behave on the submanifold. In this connection, necessary and sufficient conditions are investigated for an invariant submanifold of an almost Kenmotsu $$(\kappa ,\mu ,\nu )$$ ( κ , μ , ν ) -space to be totally geodesic under some conditions.

Mass distribution for toral eigenfunctions via Bourgain’s de-randomization

2019 ◽  
Vol 71 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Andrea Sartori
Keyword(s):  
Mass Distribution ◽  
Sufficient Conditions ◽  
Planck Scale ◽  
Necessary And Sufficient Conditions ◽  
Random Waves ◽  
Limiting Distributions ◽  
Flat Torus ◽  
Almost All ◽  
Necessary And Sufficient

Abstract We study the mass distribution of Laplacian eigenfunctions at Planck scale for the standard flat torus $\mathbb{T}^2=\mathbb{R}^2/\mathbb{Z}^2$. By averaging over the ball centre, we use Bourgain’s de-randomization to compare the mass distribution of toral eigenfunctions to the mass distribution of random waves in growing balls around the origin. We then classify all possible limiting distributions and their variances. Moreover, we show that, even in the ‘generic’ case, the mass might not equidistribute at Planck scale. Finally, we give necessary and sufficient conditions so that the mass of ‘generic’ eigenfunctions equidistributes at Planck scale in almost all balls.

scholarly journals Cone exchange transformations and boundedness of orbits

2009 ◽  
Vol 30 (5) ◽  
pp. 1311-1330 ◽  
Author(s):  
PETER ASHWIN ◽  
AREK GOETZ
Keyword(s):  
Sufficient Conditions ◽  
Point Of View ◽  
Unique Ergodicity ◽  
Interval Exchange ◽  
Ergodic Properties ◽  
Interval Exchange Transformations ◽  
Piecewise Isometries ◽  
Almost All ◽  
Necessary And Sufficient ◽  
Negative Flux

AbstractWe introduce a class of two-dimensional piecewise isometries on the plane that we refer to as cone exchange transformations (CETs). These are generalizations of interval exchange transformations (IETs) to 2D unbounded domains. We show for a typical CET that boundedness of orbits is determined by ergodic properties of an associated IET and a quantity we refer to as the ‘flux at infinity’. In particular we show, under an assumption of unique ergodicity of the associated IET, that a positive flux at infinity implies unboundedness of almost all orbits outside some bounded region, while a negative flux at infinity implies boundedness of all orbits. We also discuss some examples of CETs for which the flux is zero and/or we do not have unique ergodicity of the associated IET; in these cases (which are of great interest from the point of view of applications such as dual billiards) it remains an outstanding problem to find computable necessary and sufficient conditions for boundedness of orbits.

A general form of the covering principle and relative differentiation of additive functions. II

1946 ◽  
Vol 42 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A. S. Besicovitch
Keyword(s):  
Complete Solution ◽  
Sufficient Conditions ◽  
Additive Functions ◽  
General Measure ◽  
General Sense ◽  
Measure Function ◽  
Concentric Circles ◽  
Almost All ◽  
Necessary And Sufficient ◽  
Convergent Sequences

In my paper under the same title, to which I shall refer in future as I‡, I generalized the Vitali covering principle from the case of Lebesgue measure to the case of any non-negative additive function. This allowed me to establish the relative differentiation of additive functions. The convergent sequences of sets in this generalized form of the covering principle were restricted to sequences of concentric circles, and therefore the differentiation arrived at was that in the symmetrical sense. In the present paper, I extend the principle to the case of any regular convergent sequences of covering sets; and then establish the relative differentiation of additive functions in the general sense, and in particular the differentiation of indefinite integrals with respect to any measure function. This problem has a complete solution. It is established that indefinite integrals are differentiable at almost all points. In the case of the general measure function, it is not true that the derivative is equal to the integrand at almost all points, but necessary and sufficient conditions are given under which this is true.

CORRECT DIAGNOSIS OF ALMOST ALL FAULTY UNITS IN A MULTIPROCESSOR SYSTEM

1998 ◽  
Vol 08 (04) ◽  
pp. 473-481 ◽  
Author(s):  
K. THULASIRAMAN ◽  
ANINDYA DAS ◽  
KAIYUAN HUANG ◽  
VINOD K. AGARWAL
Keyword(s):  
Correct Diagnosis ◽  
Sufficient Conditions ◽  
Free State ◽  
Multiprocessor System ◽  
New Class ◽  
Diagnosable System ◽  
Almost All ◽  
Necessary And Sufficient ◽  
Open Question

In a t/t-diagnosable system, all faulty units can be located to within a set of no more than t units as long as the number of faulty units present does not exceed t. Furthermore, a unique doubtful unit can be identified; in other words, all faulty units, except possibly for one, can be correctly identified in a t/t-diagnosable system. An open question is "Is t/t-diagnosability necessary for correctly identifying all but one faulty unit?" In this paper, we address the above question and provide an answer. We establish necessary and sufficient conditions for correct diagnosis of all except possibly one faulty unit. In addition, we show that the fault-free state is indistinguishable from a faulty state in a t/t-diagnosable system and propose a remedy. These considerations result in the definition and characterization of a new class of systems called t/-1 diagnosable systems.

scholarly journals Perfect Orderings on Finite Rank Bratteli Diagrams

2014 ◽  
Vol 66 (1) ◽  
pp. 57-101 ◽  
Author(s):  
S. Bezuglyi ◽  
J. Kwiatkowski ◽  
R. Yassawi
Keyword(s):  
Dynamical Systems ◽  
Finite Rank ◽  
Sufficient Conditions ◽  
The Other ◽  
Bratteli Diagram ◽  
Incidence Matrices ◽  
Bratteli Diagrams ◽  
Topological Dynamical Systems ◽  
Almost All ◽  
Necessary And Sufficient

AbstractGiven a Bratteli diagram B, we study the set 𝒪B of all possible orderings on B and its subset PB consisting of perfect orderings that produce Bratteli–Vershik topological dynamical systems (Vershik maps). We give necessary and sufficient conditions for the ordering ω to be perfect. On the other hand, a wide class of non-simple Bratteli diagrams that do not admit Vershik maps is explicitly described. In the case of finite rank Bratteli diagrams, we show that the existence of perfect orderings with a prescribed number of extreme paths constrains significantly the values of the entries of the incidence matrices and the structure of the diagram B. Our proofs are based on the new notions of skeletons and associated graphs, defined and studied in the paper. For a Bratteli diagram B of rank k, we endow the set 𝒪B with product measure μ and prove that there is some 1 ≤ j ≤ k such that μ-almost all orderings on B have j maximal and j minimal paths. If j is strictly greater than the number of minimal components that B has, then μ-almost all orderings are imperfect.

The extinction time of a general birth and death process with catastrophes

1986 ◽  
Vol 23 (04) ◽  
pp. 851-858 ◽  
Author(s):  
P. J. Brockwell
Keyword(s):  
Laplace Transform ◽  
Size Distribution ◽  
Sufficient Conditions ◽  
Necessary And Sufficient Conditions ◽  
Death Process ◽  
Extinction Time ◽  
Birth And Death Process ◽  
Different Types ◽  
The Laplace Transform ◽  
Necessary And Sufficient

The Laplace transform of the extinction time is determined for a general birth and death process with arbitrary catastrophe rate and catastrophe size distribution. It is assumed only that the birth rates satisfyλ0= 0,λj> 0 for eachj> 0, and. Necessary and sufficient conditions for certain extinction of the population are derived. The results are applied to the linear birth and death process (λj=jλ, µj=jμ) with catastrophes of several different types.

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