cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Monitoring of Photovoltaic Soiling and Assessment of Soiling Losses Characterization Strategies
Creators: name: Vardanyan, R.R.
name: Badalyan, N.K.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1388-1391
description: The accumulation of dust and other environmental contaminants on the photovoltaic (PV) modules, also known as PV module soiling, is a significant environmental influence reducing the output of the PV power plant. This problem is substantial for countries with low yearly precipitations level and dusty climates. In this paper, the influence of soiling on the performance of PV modules during a year in Yerevan (Armenia) is investigated. Two PV modules were tested, one of which is regularly cleaned with the use of a specially developed automated cleaning system, while the other is left to the soil naturally. The short circuit current, output power, and efficiency losses of two PV modules were measured. The measured data shows that the characterization of soiling losses by measuring the power losses is beneficiary since the output power is the main operational parameter of the PV module. The measurement of shirt circuit current is simpler, but it is not recommended use due to the dependence of short circuit current on the homogeneity of soiling. Meantime, if necessary, the measurement of the efficiency of a soiled PV module can be realized for indication of the amount of efficiency reduction due to the soiling.
1 MW PV System at Munich Trade Fair Centre - 25 Years of Successful Operation
Creators: name: Becker, G.
name: Flade, F.
name: Giesler, B.
name: Schiebelsberger, B.
name: Weber, W.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1392-1395
description: A 1 MW photovoltaic rooftop system was built in 1997 on northern six roofs of the Munich Trade Fair Centre. At the time of its construction, it was the world’s largest roof-mounted PV system - with an installed rated output of the modules of 1016 kW, see Figure 1. In November 2022, the system will be in operation for 25 years, the average specific yield is 1032 kWh/kW until the end of 2021. The system consists of 7812 modules (thickness of the solar cells: 280 μm to 300 μm) of 130 W each and a central inverter. Extensive evaluations were carried out annually, a lot of operational experience was gained. Thus, measures for an excellent long-term behaviour are regular reports (logfile, monthly / quarterly reports), functional checks e.g. efficiency, MPP control, insulation resistance) and yearly (or often) onsite inspections.
Assessment on Truck Transport Management practices in Ethiopian Ministry of National Defense Logistics Main Department
Creators: name: Abadi, Tsegay
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2016

description: The objective of this study is to critically assess truck transportation management practice and finding the major shortcomings of the transport services in MoND logistics main department. The study used descriptive research design in both quantitative and qualitative approach. Primary data were collected through questionnaire, interview as well as field observation. Purposive sampling technique for7interviewees and simple random sampling technique used for 186 respondents asked in the open and cloth ended questionnaire. In addition, secondary data, such as annuals evaluation reports, quarterly and monthly reports, plans, and other relevant documents of MoND-Logistics assessed and other documents like; journals, articles, research papers, was used. Methodologically, this study is in accordance to the nature of the data required and designed to be descriptive. Statistical package for Social Science Software (SPSS) was applied to present data and to get the required analysis results for study. The researcher also presents the results by using descriptive statistics such as mean, standard deviation, charts, tables and other related statistical data presentation techniques. The major finding of the study indicates that, there are empty trips or underutilization of vehicles and limited utilizing modern technologies such as global positioning system, radio frequency identification The required professional competency of managers and drivers to carry out their duties and responsibilities is at good level but not at the higher professional competence level. Since the department lacks comprehensive approaches on undertaking appropriate on the job training for both managers and subordinates and problem of establishing a liaison with governmental marketing organizations and other stakeholders in order to find market for those empty trips. Keywords: Descriptive Research, Transport Management practices
Mitigating the Influence of Clipping Variability on Performance Ratio Calculations of PV Systems
Creators: name: Koumpli, E.
name: Blakesley, J.C.
name: Koutsourakis, G.
name: West, C.
name: Muller, J.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1396-1400
description: The most established applied guarantee for solar photovoltaic (PV) system performance assessment is the calculated performance ratio (PR). PR values are usually reported monthly and annually and are compared to modelled PR. Negative deviations cause significant concerns as to the root of the observed underperformance and can lead to heavy financial penalties. One of the reasons of PR calculation variability is due to the uncertainty of oversizing losses of PV systems. Oversizing loss can be exaggerated by actual weather conditions resulting in excess “clipping” for a given reporting period that negatively impacts the PR, if not corrected. In this work, the influence of weather induced clipping variability on PR calculations is presented and a methodology is demonstrated to reduce such variability when calculating PR. The sensitivity of such metric is also tested for varying levels of under-performance for simulated systems with high DC:AC of 1.6. The clipping corrected PR is found to “correct” calculated annual PRs nder variable weather datasets amongst 6 tested locations by an average of 7%, with a maximum of 20% for systems in very sunny locations and with high DC:AC ratios.
Mapa organizací s oprávněním provádět archeologický výzkum
Creators: name: Pajdla, Petr
Publisher: name: Zenodo
Year: 2022
Subjects: archaeology
licensed organizations
application

description: Poster about the map web application presenting data on organizations licenced to conduct archaeological fieldwork activities in the Czech Republic. The application is part of the research infrastructure Archaeological Information System of the Czech Republic (AIS CR). The app can be reached here: https://oao.aiscr.cz/. Abstract (Czech) Mapová aplikace poskytuje přehled platných oprávnění provádět archeologický
 výzkum na území České republiky ve smyslu zákona č. 20/1987 Sb., o státní
 památkové péči. Organizací s oprávněním provádět archeologický výzkum (OAO) v
 současnosti existuje více než sto a jejich územní působnost může být vymezena
 různě, od celého území České republiky až po působnost jen v jednotlivých
 katastrálních územích. Prezentovaná mapová aplikace nabízí možnost po kliknutí
 do mapy vyhledat OAO, které v dané oblasti působí na základě dat o proběhlých
 archeologických akcích z AMČR či polygonu územního rozsahu působnosti dané
 organizace. Dále je možné prohlíet územní působnosti jednotlivých OAO
 individuálně v mapovém rozhraní spolu s detaily z oprávnění MK ČR a dohody s AV
 ČR. Nástroj je součástí Archeologického informačního systému ČR.
Performance Evaluation and Operational Faults Analysis for PV System Protection and Safety Standard Improvement
Creators: name: Zenebe, T.M.
name: Kebede, L.
name: Midtgård, O.M.
name: Völler, S.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1370-1376
description: With increased interest in utilizing PV (photovoltaic) systems, several studies are recently focusing on ensuring their reliability and safety. Contrary to the conventional power system, research showed that existing PV systems protection and safety standards have not fully addressed PV systems protection and safety challenges. This paper aims to find gaps in PV system protection and safety standards by evaluating the performance of the existing PV system and operational faults through qualitative methods and literature review. The qualitative approach included interviewing solar experts with six to twenty-two years of experience in the PV sector in Africa and Nordic countries. As per the interviewees, the PV system works as desired if the existing standards and rules are applied appropriately. However, the literature review has shown that faults like hotspots, degradation, and arc faults are difficult to detect during regular operation. Therefore, an accurate system is needed to follow up and undertake detailed performance analyses. Besides, in the protection and safety standards designing a way of gathering detailed information that enables the PV system operator or owners to know the exact status of the PV system shall be a mandate. Data-driven methods and regular infrared imaging could fill the gap.
Deterministic radiative coupling between plasmonic nanoantennas and semiconducting nanowire quantum dots
Creators: name: Jeannin, Mathieu
name: Rueda-Fonseca, Pamela
name: Bellet-Amalric, Edith
name: Kheng, Kuntheak
name: Nogues, Gilles
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We report on the deterministic coupling between single semiconducting nanowire quantum dots emitting in the visible and plasmonic Au nanoantennas. Both systems are separately carefully characterized through microphotoluminescence and cathodoluminescence. A two-step realignment process using cathodoluminescence allows for electron beam lithography of Au antennas near individual nanowire quantum dots with a precision of 50 nm. A complete set of optical properties are measured before and after antenna fabrication. They evidence both an increase of the NW absorption, and an improvement of the quantum dot emission rate up to a factor two in presence of the antenna.
Phosphorene and Doped Monolayers Interfaced TiO$_2$ with Type-II Band Alignments: Novel Excitonic Solar Cells
Creators: name: Zhou, Liujiang
name: Zhang, Jin
name: Zhuo, Zhiwen
name: Kou, Liangzhi
name: Ma, Wei
name: Shao, Bin
name: Du, Aijun
name: Meng, Sheng
name: Frauenheim, Thomas
Publisher: name: arXiv
Year: 2015
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Phosphorene, a new elemental two dimensional (2D) material recently isolated by mechanical exfoliation, holds the feature of a direct band gap of around 2.0 eV, overcoming graphene's weaknesses (zero band gap) to realize the potential application in optoelectronic devices. Constructing van der Waals heterostructures is an efficient approach to modulate the band structure, to advance the charge separation efficiency, and thus to optimize the optoelectronic properties. Here, we theoretically investigated three type-II heterostructures based on perfect phosphorene and its doped monolayers interfaced with TiO$_2$(110) surface. Doping in phosphorene has a tunability on built-in potential, charge transfer, light absorbance, as well as electron dynamics, which helps to optimize the light absorption efficiency. Three excitonic solar cells (XSCs) based on the phosphorene$-$TiO$_2$ heterojunctions have been proposed, which exhibit high power conversion efficiencies dozens of times higher than conventional solar cells, comparable to MoS$_2$/WS$_2$ XSC. The nonadiabatic molecular dynamics within the time-dependent density functional theory framework shows ultrafast electron transfer time of 6.1$-$10.8 fs, and slow electron$-$hole recombination of 0.58$-$1.08 ps, yielding $>98\%$ quantum efficiency for charge separation, further guaranteeing the practical power conversion efficiencies in XSC.
Impact of Large Format Solar Panels on the Balance of System Costs of Photovoltaic Power Plants
Creators: name: Berrian, D.
name: Linder, J.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1377-1382
description: New large-size photovoltaic (PV) modules with a power rating exceeding 500Wp have been introduced to the PV market recently. These large format PV panels, known as M10 made of 182mm cell-size, and M12 made of 210mm cell-size, are expected to dominate the PV module market share in the coming years due to their high-power output. We benchmarked - in terms of the balance of system (BoS) costs - the new format PV modules to the current dominated PV module size (M6) in the market, which is made of 166mm cell size. Based on an existing large-scale utility PV plant, we modeled the power, energy yield as well as the involved costs for the three PV module formats mentioned earlier. Both large formats PV modules have shown a significant BoS costs saving up to 6% for approx. 50MWp PV project in comparison to the current mainstream PV modules. Interestingly, we did not find a noticeable difference in terms of BoS costs between M10 and M12 sizes, although the M12 PV module size usually has a higher power rating than M10 PV modules.
Comparison of Soiling Measurement Approaches in Solar PV Plants
Creators: name: Rodriguez, P.
name: Aristizabal, H.
name: Muñoz, J.
name: Sinha, S.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1383-1387
description: Soiling is a key system loss that could be minimised during the operational phase of a Solar PV system to improve its performance. Therefore, accurately measuring, monitoring and analysing soiling data at PV plants, especially in arid, semiarid and air polluted environments, gains importance. In this study we aim to understand how different variables such as ambient and PV module temperature, rainfall, relative humidity and solar angle, impact the soiling measurements obtained by the calibrated cells (CC) and optical sensors (OS) of two PV plants located in Mexico. We analyse how the output data from each of these two measurement approaches should be treated and analysed according to the variables that impact such measurement. The analysis performed shows no correlation between the selected variables and the Soiling Ratio (SR) obtained with the CC and OS. The dispersion of SR obtained with the CC was significatively higher than the OS, which seems to be mainly due to the variation in the irradiance measured by the CC through the day, and thus, filtering the data by irradiance reduces the difference of the SR measured with the two different devices.
The Critical Factors Affecting Supply Chain Management in the Brewery Industry
Creators: name: Demmissie, Daniel
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2016

description: The major objective of this study was to explore the Critical Factors Affecting Supply Chain Management in Brewery Manufacturing firms in Ethiopia. The research design was used to investigate the factors that affect the supply chain management in brewery industry in Ethiopia. Hence, this study used quantitative and qualitative research design (a mixed research). The relationship of factors, production scale and product quality has a less correlation with supply chain integration (r=0.341) and a moderate correlation with customer focus and innovation (r= 0.479) and a strong correlation with marketing and distribution (r = 0.724). The chi-square for the factor called production scale and product quality was 3.379 and the significant level was 0.066 (insignificant). The factor called supply chain integration had a chi-square test of 3.379 (sig: 0.066) and indicates insignificant value. The chai-square result of customer focus and innovation showed as 5.586 with sig blow 0.05 (0.018) indicated customer focus and innovation was a determinant factor that had a relationship in the supply chain management important in Ethiopia brewery industry. A very low chi-square result was registered on marketing and distribution and it was expressed as marketing and distribution was not a determinant factor. The breweries companies in Ethiopia may identify the portfolio of key initiatives that will help transform their traditional supply chain into a demand- driven value network Key Words: Key Words: Organizational performance, Supplier, Supplier Relation Management
Estimation of Soil Pressures Based on the Pressures in the Hydraulic System for a Legged Forestry Machine
Creators: name: Beiser, Sebastian
name: Geimer, Marcus
Publisher: name: Karlsruher Institut für Technologie (KIT)
Year: 2022
Subjects: portal advancing mechanism
soil pressure
simulation
hydraulics

description: Harvesting operations with wheeled forestry machines can bring great harm to wet soils due to the machine weight and wheel slip. Factors such as the reduction of wheel slip, machine weight and total area affected by forestry machines are crucial in protecting soils. The accurate measurement of the pressure introduced by forestry machines to the soil, without harming the structure of the ground nor making assumptions of the tire or ground behavior, poses a challenge. Within this article a method to calculate the contact soil pressure, of a portal advancing mechanism for sensitive soils is presented. The results are then further evaluated based on simulative results. B y using the kinematics of the legged machine, it becomes possible to determine the soil pressure without making rough assumptions of the legs or the ground. The kinematic allows to measure the forces of the hydraulic actuators that are holding the legs in position. Through this, a direct calculation of the force which is transferred to the ground can be made. To determine the forces of the hydraulic actuators in a movement cycle, a coupled simulation of the kinematic and hydraulic system is set up. Using the determined pressures in the cylinders the exerted force on the ground is calculated. The developed calculation method has been set up in such a manner that the results can easily be compared to real world test data in future studies. In addition, the effects of this particular legged forestry machine on the ground will be compared to other machine types under the consideration, that with this new concept no slip is expected. Using this approach, the soil pressure and the impact on the ground of a legged forestry machine can be evaluated in an early stage of development.
Path integral quantization of the relativistic Hopfield model
Creators: name: Belgiorno, F.
name: Cacciatori, S. L.
name: Piazza, F. Dalla
name: Doronzo, M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The path integral quantization method is applied to a relativistically covariant version of the Hopfield model, which represents a very interesting mesoscopic framework for the description of the interaction between quantum light and dielectric quantum matter, with particular reference to the context of analogue gravity. In order to take into account the constraints occurring in the model, we adopt the Faddeev-Jackiw approach to constrained quantization in the path integral formalism. In particular we demonstrate that the propagator obtained with the Faddeev-Jackiw approach is equivalent to the one which, in the framework of Dirac canonical quantization for constrained systems, can be directly computed as the vacuum expectation value of the time ordered product of the fields. Our analysis also provides an explicit example of quantization of the electromagnetic field in a covariant gauge and coupled with the polarization field, which is a novel contribution to the literature on the Faddeev-Jackiw procedure.
description: 16 pages
Non-viscous Regularization of the Davey-Stewartson Equations: Analysis and Modulation Theory
Creators: name: Guo, Yanqiu
name: Hacinliyan, Irma
name: Titi, Edriss S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Analysis of PDEs (math.AP)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: In the present study we are interested in the Davey-Stewartson equations (DSE) that model packets of surface and capillary-gravity waves. We focus on the elliptic-elliptic case, for which it is known that DSE may develop a finite-time singularity. We propose three systems of non-viscous regularization to the DSE in variety of parameter regimes under which the finite blow-up of solutions to the DSE occurs. We establish the global well-posedness of the regularized systems for all initial data. The regularized systems, which are inspired by the $α$-models of turbulence and therefore are called the $α$-regularized DSE, are also viewed as unbounded, singularly perturbed DSE. Therefore, we also derive reduced systems of ordinary differential equations for the $α$-regularized DSE by using the modulation theory to investigate the mechanism with which the proposed non-viscous regularization prevents the formation of the singularities in the regularized DSE. This is a follow-up of the work of Cao, Musslimani and Titi on the non-viscous $α$-regularization of the nonlinear Schrödinger equation.
A Facility Test to Generate Data from Real PV Systems Affected by Faults and Validate Fault Detection and Diagnosis Algorithms
Creators: name: Maugeri, G.
name: Rossetti, A.
name: Urciuoli, V.
name: Bombelli, D.
name: Guastella, S.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1364-1369
description: The use of Machine Learning (ML) techniques in various application domains--in computer safety systems or within industrial processes--has proven benefits from an economic and efficiency standpoint. With these methods applied to datasets from monitoring systems, in real-time, it is possible to reduce the time to recognize faults, restore normal operation quickly, and avoid serious or permanent malfunctions, which would lead to longer downtime and higher repair costs. In the photovoltaic (PV) sector, the automatic fault detection through algorithms employing ML approaches can provide important clues to maintenance operators for subsequent troubleshooting phase, enabling them to optimize repair time and costs. However, developing models for the detection and diagnosis of faults is far from trivial and numerous challenges must be faced. One of the most difficulties for the development, validation and optimization of Failure Detection and Diagnosis (FDD) algorithms, lies in accessing the historical production datasets of PV plants in which there are enough failure events for the training and tests of ML algorithms. Furthermore, the FDD algorithms need to be ready in handling data that may be affected by communication errors, uncalibrated sensors, or other factors that can affect the PV performances (shadings, grid interruptions, ecc). Within this work we are presenting an experimental Test Facility for the simulation of faults in PV systems, to generate large datasets from real PV systems that are affected by faults. A characterization of the main fault conditions that can occur in photovoltaic systems is presented, illustrating how the electrical parameter evolves in the specific fault. The real-field PV data generated by the RSE PV Facility Test allows having historical PV data with several separated failure events appropriately labeled for training and testing of ML algorithms. Within this work we are presenting an experimental Test Facility for the simulation of faults in PV systems, to generate large datasets from real PV systems that are affected by faults. A characterization of the main fault conditions that can occur in photovoltaic systems is presented, illustrating how the electrical parameter evolves in the specific fault. The real-field PV data generated by the RSE PV Facility Test allows having historical PV data with several separated failure events appropriately labeled for training and testing of ML algorithms.
Superconductivity vs bound state formation in a two-band superconductor with small Fermi energy -- applications to Fe-pnictides/chalcogenides and doped SrTiO3
Creators: name: Chubukov, Andrey V
name: Eremin, Ilya
name: Efremov, Dmitri V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We analyze the interplay between superconductivity and the formation of bound pairs of fermions (BCS-BEC crossover) in 2D models of interacting fermions with small Fermi energy EF and weak attractive interaction, which extends to energies well above EF. The 2D case is special because one has to distinguish between bound state formation and superconductivity already at weak coupling. We briefly review the situation in the one-band model and then consider two different two-band models: the one with a hole and an electron band, and the one with two electron bands. In each case we obtain the bound state energy 2 E0 for two fermions in a vacuum and solve the set of coupled equations for the pairing gaps and the chemical potentials to obtain the onset temperature of the pairing, Tins and the quasiparticle dispersion. We then compute the superfluid stiffness and obtain the actual Tc. We show that, at EF >> E0 the behavior of both two-band models is BCS-like in the sense that Tc almost coincides with Tins and both are much smaller than EF. At EF < E0, the two models behave differently: in the model with two electron bands, Tins ~E0/log(E0/EF) and Tc ~EF << Tins. In between Tins and Tc the system displays preformed pair behavior. In the model with a hole and an electron band, Tins ~ Tc and both remain finite at EF=0 The preformed pair behavior still exists in this model because Tc is numerically smaller than Tins. For both models we re-express Tins in terms of the fully renormalized two-particle scattering amplitude by extending to two-band case the method pioneered by Gorkov and Melik-Barkhudarov back in 1961. We apply our results to to Nb-doped SrTiO3 and to Fe-pnictides and Fe-chalcogenides, particularly to FeSe, in which superconducting gap is comparable to the Fermi energy.
description: 25 pp, 14 figures, submitted to PRB
Филологические науки,Выпуск 1 (64) 2022
Creators: name: АО «КазУМОиМЯ им.Абылай хана»
Publisher: name: АО «КазУМОиМЯ им.Абылай хана»
Year: 2022

description: Филологические науки,Выпуск 1 (64) 2022
Experimental Observations about the Cloud Enhancement Phenomenon on PV Strings
Creators: name: Lappalainen, K.
name: Valkealahti, S.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1354-1358
description: Due to the cloud enhancement (CE) phenomenon, irradiance on partly cloudy days can considerably exceed the expected clear sky irradiance. Although CE is a well-known phenomenon, its effects on the operation of photovoltaic (PV) power systems have not been studied comprehensively based on electrical measurements. In this paper, the characteristics of CE events are analysed based on irradiance measurements and by examining the operation of three PV strings based on current–voltage curves measured under CE conditions. The highest measured irradiances were about 1450 W/m2 while the theoretical clear sky maximum irradiance is about 900 W/m2. It means that the highest measured irradiance was about 1.7 times the expected clear sky irradiance. Correspondingly, the highest measured powers exceeded the highest theoretical clear sky powers. Although the measured maximum power point (MPP) powers exceeded the nominal standard test conditions MPP power, the MPP voltages were typically lower than the nominal MPP voltage. The reason for this is that during the CE events, temperature was typically much higher than in standard test conditions. The experimental results of this study show that CE events do not cause problematic increase of PV system operating voltages and confirm the findings of earlier simulation studies.
Two-dimensional dispersion of magnetostatic volume spin waves
Creators: name: Buijnsters, F. J.
name: van Tilburg, L. J. A.
name: Fasolino, A.
name: Katsnelson, M. I.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The dipolar (magnetostatic) interaction dominates the behavior of spin waves in magnetic films in the long-wavelength regime. In an in-plane magnetized film, volume modes exist with a negative group velocity (backward volume magnetostatic spin waves), in addition to the forward surface-localized mode (Damon-Eshbach). Inside the film of finite thickness $L$, the volume modes have a nontrivial spatial dependence, and their two-dimensional dispersion relations $ω(\mathbf{k})$ can be calculated only numerically. We present explicit perturbative expressions for the profiles and frequencies of the volume modes, taking into account an in-plane applied field and uniaxial anisotropy, for the regimes $\lVert \mathbf{k}L \rVert \gg 1$ and $\lVert \mathbf{k}L \rVert \ll 1$, which together provide a good indication of the behavior of the modes for arbitrary wavevector $\mathbf{k}$. Moreover, we derive a very accurate semianalytical expression for the dispersion relation $ω(\mathbf{k})$ of the lowest-frequency mode that is straightforward to evaluate using standard numerical routines. Our results are useful to quickly interpret and control the excitation and propagation of spin waves in (opto-)magnetic experiments.
description: 16 pages, 8 figures
One Year Performance Assessment of Silicon Hetero-Junction Solar Modules on Horizontal Single Axis Tracker
Creators: name: Maugeri, M.
name: Sanz Martinez, A.
name: Setien, E.
name: Todaro, L.
name: Mignonac, A.
name: Demofonti, G.
name: Guastella, S.
name: Virtuani, A.
name: Guillerez, S.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1359-1363
description: The deployment of single-axis tracker bifacial PV systems is attracting the interest of several PV operators particularly targeting the utility-scale market segment. The main driver is the lowest Levelized cost of electricity (LCOE) achievable by this solution due to the increased energy yield. This paper presents the results of one full year of monitoring data from a pilot PV system realized in the framework of the H2020 European project, GOPV. The PV pilot plant is installed in Cadarache (France) and consists of bifacial half-cell silicon heterojunction (HJT) PV modules combined with Horizontal Single Axis Trackers (HSAT), east-west sun tracking. This work compares the monthly gain of the energy yield of the bifacial HJT technology, installed both on a tilted fixed structure and on a HSAT tracker, with a PERC monofacial technology installed on tilted fixed structure, which serves as a reference system. The results highlight that, compared to the benchmark technology, the energy yield of the bifacial HJT on a fixed structure can achieve an average of 15% gain on annual basis, and the HJT bifacial on HSAT can exceed 35% during the summer months. This study also includes insights from the experience gathered in one year of activity on the influence of wind parameters on tracking yield.
Adoption of crop diversification by specialized grain farmers in south-western France: evidence from a choice-modelling experiment
Creators: name: Ridier, Aude
name: Roussy, Caroline
name: Chaib, Karim
name: Ridier, Aude
name: Roussy, Caroline
name: Chaib, Karim
Publisher: name: Unknown
Year: 2021
Subjects: subject: Agricultural and Food Policy
subject: Crop Production/Industries
subject: Farm Management
subject: Adoption
subject: Farmer preferences
subject: Crop diversification
subject: Choice modelling

description: Farming systems in developed countries have highly specialized to reach economies of scale. In addition to their low economic resilience, specialized agricultural systems face more and more agronomic problems such as yield stagnancy or pest and pathogen resistance. Crop diversification is a lever to overcome these problems and to reduce chemical inputs. But the adoption of diversification crops remains low and heterogeneous, due to both monetary and non-monetary determinants. Unobservable determinants such as the perception of crop characteristics might explain this heterogeneity. The paper proposes an evaluation of farmers’ preferences for these characteristics with a choice modelling conducted among 71 specialized grain farmers of south-western France. A random parameter logit model interacting crop attributes with farms’ individual characteristics show that, in addition to monetary attributes, crop traits such as the level of nitrogen restitution and the positive effect of the diversification crop on pest management influence adoption. It shows an even stronger impact of these agronomic attributes when soil and agronomic conditions are constraining. Moreover, demand for crop diversification is influenced by the performance of the farm’s main crop and by the type of marketing contract adopted, which suggests cross effects with risk management strategies.
Cloud-Based Decision Support System for Operation and Maintenance in Photovoltaic Systems
Creators: name: Livera, A.
name: Garcia Franquelo, J.
name: Gonzalez Bernal, R.
name: Georghiou, G.E.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1339-1344
description: A decision support system (DSS) is proposed in this work for providing recommendations of actionable decisions to resolve underperformance issues in photovoltaic (PV) systems. The proposed cloud-based DSS incorporates functionalities for data quality, PV system modeling, problem detection, energy loss breakdown, incidents criticality evaluation and operation and maintenance (O&M) recommendations. It was benchmarked experimentally using historical field data from a 10.09 MWp PV power plant in the Mediterranean region. The results demonstrated the DSS’s capabilities for automated detection of failures and performance losses and categorization into different fault causes. Over the 1-year evaluation period, the detected underperformance incidents accounted for 2100 MWh (or 14.30% of the total energy production) of lost energy. Given the DSS recommendations, approximately 7% of lost energy production could be recovered by performing field mitigation activities (e.g., corrective actions).
Soiling Detection on Photovoltaic Modules Using Hyperspectral Imaging and Machine Learning Algorithms
Creators: name: Turek, M.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1345-1349
description: The automated remote detection of the state of PV power plants plays an increasing role for costoptimized plant monitoring. Ideally, it yields additional information explaining observed power yield fluctuations by going beyond the data provided by the electrical inverter without requiring any direct access to the power plant locations. To this end, optical and electro-optical inspection techniques play an important role in the monitoring and maintenance of PV power plants. In our work, we present a proof-of-concept based on lab-samples showing that the combination of hyper-spectral imaging techniques together with machine learning approaches can detect and classify soiling on glass surfaces. We demonstrate a workflow including a) the acquisition of the high-dimensional spectral data, where each pixel of the image carries an entire reflection spectrum, b) the dimensionality reduction of the extended spectral data-set using principal component analysis, and c) a comparison of supervised classification and unsupervised clustering algorithms. As a result, we find that our workflow can identify surface-regions of PV modules with increased soiling. Applying a numerical cross-validation, we find recall and precision metrics well above 90% for the supervised classifiers. Although the unsupervised clustering approaches are naturally showing a lower predictive power, they nevertheless can be used to distinguish soiling-free surfaces from surfaces covered with soiling.
The Influente of System Layout and Operating Conditions on PV System Degradation
Creators: name: Vidal De Oliveira, A.K.
name: Buerhop-Lutz, C.
name: Peters, I.M.
name: Rüther, R.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Operation, Performance and Maintenance of PV Systems

description: 8th World Conference on Photovoltaic Energy Conversion; 1350-1353
description: This paper compares performance data of two installed PV systems with the same type of multicrystalline, p-type silicon PV module in two different climatic and installation conditions. The analysis was carried out on a 17.64kWp portion of a roof-top PV plant installed in 2013 in the Lisbon area, in Portugal (38.7°N; 9.3°W) and on a ground mounted 2.35 kWp system installed in 2016 at the Fotovoltaica-UFSC Solar Energy Research Laboratory in Florianópolis -SC (27.4°S, 48.4°W). The modules of both plants are installed with a tilt of 20° in a region close to the coast. The analysis showed that, overall, the Brazilian system presented higher performance rations (PR) than the system installed in Portugal (around 20% more than Portugal’s PR). The curtailments that the Portugal’s system suffers in high-irradiance months, the soiling and the high temperatures in these periods are among the possible explanations for the higher system losses. The data analysis also showed the effects of shadowing on Brazilian’s system and Potential Induced Degradation (PID) that affected the system installed in Portugal. Although the Brazilian site is characterized by a hot and humid climate, it did not show the same degradation patterns, due to the lower voltages that the modules in Brazil are subjected to, because it is a system with one string with 10 modules (around 301 VMPP), while the Portugal system has strings with 24 modules in series (around 727.2 VMPP). The results showed that the degradation behavior of a PV installation is determined by several factors, including environmental conditions and especially the layout of the installation. These findings lead to a more accurate understanding of different climatic and layout related degradation mechanisms of PV modules, therefore having a significant contribution for the design of reliable PV systems.
Cloud Flow Centring in Sky and Satellite Images for Deep Solar Forecasting
Creators: name: Paletta, Q.
name: Arbod, G.
name: Lasenby, J.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Solar Resource and Forecasting

description: 8th World Conference on Photovoltaic Energy Conversion; 1325-1330
description: In solar energy, most of the short-term spatiotemporal variability can be attributed to the displacement of clouds over solar facilities. To accelerate the expansion of this variable source of energy, sky cameras and satellites have been used as complementary perspectives on the cloud cover to better anticipate its impact on the local energy generation. Recently, machine learning (ML) algorithms have shown considerable potential at modelling cloud movements from observations (e.g., high forecast skill, quantifiable uncertainty, improved interpretability). In addition to optimising the network architecture, data-centric methods have been used to facilitate model learning. For instance, representing the scene with polar coordinates centred on the region of interest (the sun in sky images or a solar site in satellite observations) significantly improves predictions. In this paper, we propose to further augment this method by consistently centring the polar representation on the incoming flow of clouds using an optical flow algorithm. Although flow centring images might benefit predictions in particular contexts such as low data availability settings, the method is hindered by the breaking up of some critical spatial features and the difficulty in generating accurate optical flow in highly changing cloud aspect conditions. In these conditions, increasing the temporal resolution of observations would facilitate the calculation of cloud motion vectors. In addition, predicting the clear-sky index instead of the absolute irradiance level could facilitate the integration of daily and yearly solar variability into the modelling when the estimation of the sun position is hindered by flow centring.
Future Weather Data Analysis for Solar Heating and Cooling
Creators: name: Schmidli, J.
name: Carbonell, D.
name: Biba, C.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Solar Resource and Forecasting

description: 8th World Conference on Photovoltaic Energy Conversion; 1331-1335
description: To tackle the challenges of global warming, efficient design of renewable energy systems is needed. To achieve this goal there is a need of accurate simulations considering uncertainties such as future solar resources. Within the present paper, some of the impacts of future weather scenarios on solar heating and cooling are evaluated. Transient simulations are carried out for different future scenarios to evaluate the impact of the weather data on the energetic efficiency of a PV heat pump system delivering heating, cooling, domestic hot water, and electricity to a multi-family residential building. The system efficiency of different future scenarios is assessed based on the grid purchase ratio. The results show that the overall grid purchase ratio is likely to decrease in the future for the location of Zurich Switzerland, which is mainly caused by an increase in cooling demand during summer due to rising temperatures that come together with high irradiation.
Operation Analysis of Concentrated Photovolatic/Thermal for Heating Crude Oil
Creators: name: Gao, D.
name: Long, W.
name: Liu, Q.
name: Guo, J.
name: Cui, W.
name: Wang, H.
name: Yang, H.
Publisher: name: WIP
Year: 2022
Subjects: PV Systems Engineering, Integrated/Applied PV
Concentrators, TPV

description: 8th World Conference on Photovoltaic Energy Conversion; 1336-1338
description: Because the flowability of crude oil is worse at ambient temperature, it is usually heated to about 50 ℃ during transportation. It is important to develop an effective method heating crude oil. In this paper, an operation analysis of concentrated photovoltaic/thermal (CPV/T) for heating crude oil in Urumqi is carried out for the first time. The viability of CPV/T for heating crude oil was evaluated. It is found that the CPV/T system has a better capacity utilization because it can generate electricity and heat simultaneously during full-year operation, particularly in summer.
Quantum gate optimisation in stoichiometric rare-earth ensembles
Creators: name: Pearce, Matthew
Publisher: name: The Australian National University
Year: 2022

description: This thesis is an investigation into implementing quantum computing in stoichiometric rare-earth systems, with the crystal EuCl3 6D2O used as an example system. In a stoichiometric satellite system, a crystal stoichiometric in one rare-earth species is doped with a second rare-earth. The ions around a dopant experience shifts in their optical and hyperfine transition frequencies uniquely determined by their location relative to the dopant. This creates an ensemble of identical spin clusters with strong and consistent local interactions between ions in spin clusters. Ensembles of ions in the unique positions around the dopant can be used as qubits, enabling the creation of small quantum systems of 5-10 high-quality qubits for use in a small quantum processor. This thesis investigates the conditions necessary for implementation of a quantum processor in EuCl3 6D2O and other stoichiometric rare-earth systems. The primary factors explored in this thesis are the manipulation of system parameters and the implementation and optimisation of quantum gates in EuCl3 6D2O to minimise gate error. The quantum gate error of EuCl3 6D2O with Gaussian pulse shapes was first explored. It was determined that the oscillator strengths of EuCl3 6D2O are too unequal to be able to perform low error quantum operations at zero-field. The use of applied magnetic fields to manipulate the oscillator strengths and hyperfine splittings of EuCl3 6D2O was explored. It was found that broad magnetic field regions exist in which the parameters of EuCl3 6D2O can be manipulated to be closer to an ideal L system. Through the application of an 8T field, it was found that a three-qubit bit-flip error correction sequence could potentially be implemented with an error as low as 0.022. The optimisation of the optical pulses used to perform quantum gates in EuCl3 6D2O was investigated. It was determined that standard Gaussian pulses were sufficient to perform gates of a sufficiently low error for quantum error correction. Simulations of a NOT gate on an inhomogeneously broadened ensemble were performed with both a compensated pulse sequence and direct rotations. It was determined that compensated pulses do not reduce gate error over direct pulses in EuCl3 6D2O. The use of arbitrary pulse shapes was investigated and it was determined that a reduction of approximately 37% in gate error could be achieved by using optimised pulses of arbitrary shape. It was determined that the quantum gate error in europium systems is fundamentally limited by the size of the europium hyperfine splittings relative to the optical coherence time. The rare-earth species erbium and holmium were proposed for computing due to their large hyperfine structure, and it was established that there is potential for up to a 100-fold reduction in quantum gate error by moving to these host ions.