920 research outputs found
New algorithm for energy dispatch scheduling of grid-connected solar photovoltaic system with battery storage system
Purpose. In last decade the problem of energy management system (EMS) for electric network has received special attention from academic researchers and electricity companies. In this paper, a new algorithm for EMS of a photovoltaic (PV) grid connected system, combined to an storage system is proposed for reducing the character of intermittence of PVs power which infect the stability of electric grid. In simulation model, the PV system and the energy storage system are connected to the same DC bus, whereas EMS controls the power flow from the PV generator to the grid based on the predetermined level of PV power. In the case where the PV power is less than the predefined threshold, energy is stored in the batteries banc which will be employed in the peak energy demand (PED) times. Otherwise, it continues to feed the principal grid. The novelty of the proposed work lies in a new algorithm (smart algorithm) able to determine the most suitable (optimal) hours to switching between battery, Solar PVs, and principal grid based on historical consumption data and also determine the optimal amount of storage energy that be injected during the peak demand. Methods. The solution of the problem was implemented in the Matlab R2010a Platform and the simulation conducted on Laptop with a 2.5 GHz processor and 4 GB RAM. Results. Simulation results show that the proposed model schedules the time ON/OFF of the switch in the most optimal way, resulting in absolute control of power electric path, i.e. precise adaptation at the peak without compromising consumers comfort. In addition, other useful results can be directly obtained from the developed scheme. Thus, the results confirm the superiority of the proposed strategy compared to other improved techniques.Мета. В останнє десятиліття проблемі системи енергоменеджменту (СЕМ) для електричної мережі приділялася особлива увага з боку науковців та електроенергетичних компаній. У цій роботі пропонується новий алгоритм для СЕМ фотоелектричної (ФЕ) системи, підключеної до мережі, об'єднаної з системою накопичення енергії для зменшення характеру переривчастості потужності ФЕ системи, що впливає на стабільність електричної мережі. У розрахунковій моделі ФЕ система та система накопичення енергії підключені до однієї і тієї ж шини постійного струму, тоді як СЕМ керує потоком потужності від ФЕ генератора до мережі на основі заздалегідь визначеного рівня потужності ФЕ. У тому випадку, коли потужність ФЕ менше заздалегідь визначеного порогу, енергія накопичується в батареях акумуляторів, що буде використано в часи пікового попиту на енергію. В іншому випадку ФЕ продовжує живити основну мережу. Новизна запропонованої роботи полягає в новому алгоритмі (розумному алгоритмі), здатному визначити найбільш підходящі (оптимальні) години для перемикання між акумулятором, сонячними ФЕ та основною мережею на основі даних про історію споживання, а також визначити оптимальну величину енергії накопичення, що вводиться під час пікового попиту. Методи. Розв‘язання задачі було реалізовано на платформі Matlab R2010a, а моделювання проведено на ноутбуці з процесором 2,5 ГГц та 4 ГБ оперативної пам'яті. Результати. Результати моделювання показують, що запропонована модель найоптимальніше планує час увімкнення/вимкнення вимикача, що призводить до абсолютного контролю потужності шляху електроенергії, тобто точної адаптації на піку без шкоди для комфорту споживачів. Крім того, з розробленої схеми можна безпосередньо отримати інші корисні результати. Таким чином, результати підтверджують перевагу запропонованої стратегії порівняно з іншими вдосконаленими методами
Ad- and desorption of Rb atoms on a gold nanofilm measured by surface plasmon polaritons
Hybrid quantum systems made of cold atoms near nanostructured surfaces are
expected to open up new opportunities for the construction of quantum sensors
and for quantum information. For the design of such tailored quantum systems
the interaction of alkali atoms with dielectric and metallic surfaces is
crucial and required to be understood in detail. Here, we present real-time
measurements of the adsorption and desorption of Rubidium atoms on gold
nanofilms. Surface plasmon polaritons (SPP) are excited at the gold surface and
detected in a phase sensitive way. From the temporal change of the SPP phase
the Rubidium coverage of the gold film is deduced with a sensitivity of better
than 0.3 % of a monolayer. By comparing the experimental data with a Langmuir
type adsorption model we obtain the thermal desorption rate and the sticking
probability. In addition, also laser-induced desorption is observed and
quantified.Comment: 9 pages, 6 figure
The role of Mie scattering in the seeding of matter-wave superradiance
Matter-wave superradiance is based on the interplay between ultracold atoms
coherently organized in momentum space and a backscattered wave. Here, we show
that this mechanism may be triggered by Mie scattering from the atomic cloud.
We show how the laser light populates the modes of the cloud, and thus imprints
a phase gradient on the excited atomic dipoles. The interference with the atoms
in the ground state results in a grating, that in turn generates coherent
emission, contributing to the backward light wave onset. The atomic recoil
'halos' created by the scattered light exhibit a strong anisotropy, in contrast
to single-atom scattering
Absorption from Finite-size Microperforated Panels at Arbitrary Incidence Angles
A rigid microperforated panel combined with a finite-depth air space can absorb sound effectively. Various studies of these systems have been performed and it has been found that hole configuration and backing depth are the primary factors that determine their absorption. However, the effects of panel flexibility and the finite size of the supported membrane segments have not been considered as extensively. In this present work, a two-dimensional model for arbitrary incidence angles was used to predict the sound absorption of an infinite array of finite-size, flexible microperforated panels. The absorption of various microperforated panels was measured in standing wave tubes and compared to predictions to verify the model at normal incidence. The effects of two different types of backing spaces, i.e., segmented and unsegmented, were compared. It was found that the segmented backing space is approximately locally reacting: as a result, the absorption at low frequencies is larger than that for the unsegmented backing space case. It was also found that the absorption from an array of finite-size microperforated panels can be successfully predicted with a knowledge of the panel’s physical material properties (e.g., flexural stiffness, loss factor, and mass per unit area) and hole configuration (e.g., hole size, film thickness, and number of holes per unit area)
Experimental perspectives for systems based on long-range interactions
The possibility of observing phenomena peculiar to long-range interactions,
and more specifically in the so-called Quasi-Stationary State (QSS) regime is
investigated within the framework of two devices, namely the Free-Electron
Laser (FEL) and the Collective Atomic Recoil Laser (CARL). The QSS dynamics has
been mostly studied using the Hamiltonian Mean-Field (HMF) toy model,
demonstrating in particular the presence of first versus second order phase
transitions from magnetized to unmagnetized regimes in the case of HMF. Here,
we give evidence of the strong connections between the HMF model and the
dynamics of the two mentioned devices, and we discuss the perspectives to
observe some specific QSS features experimentally. In particular, a dynamical
analog of the phase transition is present in the FEL and in the CARL in its
conservative regime. Regarding the dissipative CARL, a formal link is
established with the HMF model. For both FEL and CARL, calculations are
performed with reference to existing experimental devices, namely the
FERMI@Elettra FEL under construction at Sincrotrone Trieste (Italy) and the
CARL system at LENS in Florence (Italy)
Molecular Characterization of Glycopeptide-Resistant Enterococci from Hospitals of the Picardy Region (France)
We studied 138 glycopeptide-resistant enterococci (GRE) strains, consisting of 131 glycopeptide-resistant Enterococcus faecium (GREfm) and 7 glycopeptide-resistant Enterococcus faecalis (GREfs). The GREfm strains were resistant to penicillin, ampicillin, vancomycin, and teicoplanin, while the GREfs strains were only resistant to vancomycin and teicoplanin. The van A gene was the only glycopeptide determinant present in all GRE isolates investigated. Genes coding for Hyl and Hyl+ Esp were detected in 39 (29.8%) and 92 (70.2%) of the 131 GREfm isolates, respectively. Three of the 7 GREfs were positive for gelE+asa 1 genes, 3 for gel E gene, and 1 for asa 1 gene. The genetic relationship between the 138 GRE was analyzed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). GREfm isolates were clustered in a single genogroup (pulsotype A), and GREfs were clustered in six genogroups (pulsotypes B-G). Among the isolates investigated by MLST, only 18 PCR products were sequenced (12 E. faecium and 6 E. faecalis), and 9 sequence types (STs) were identified
Convergent activation of two-pore channels mediated by the NAADP-binding proteins JPT2 and LSM12
The second messenger nicotinic acid adenine dinucleotide phosphate (NAADP) evokes calcium ion (Ca2+) release from endosomes and lysosomes by activating two-pore channels (TPCs) on these organelles. Rather than directly binding to TPCs, NAADP associates with proteins that indirectly confer NAADP sensitivity to the TPC complex. We investigated whether and how the NAADP-binding proteins Jupiter microtubule-associated homolog 2 (JPT2) and like-Sm protein 12 (LSM12) contributed to NAADP-TPC-Ca2+ signaling in human cells. Biochemical and functional analyses revealed that recombinant JPT2 and LSM12 both bound to NAADP with high affinity and that endogenous JPT2 and LSM12 independently associated with TPC1 and TPC2. On the basis of knockout and rescue analyses, both NAADP-binding proteins were required to support NAADP-evoked Ca2+ signaling and contributed to endolysosomal trafficking of pseudotyped coronavirus particles. These data reveal that the NAADP-binding proteins JPT2 and LSM12 convergently regulate NAADP-evoked Ca2+ release and function through TPCs
Experiences that \u201creach the heart\u201d. Taking part in a whole body dissection course at the University of Malta
This article summarizes the activities of the four-week whole body dissection course the main authors participated in in August 2016 at the dissection hall of the University of Malta (UoM). Our team comprised 10 second-year medicine students from University of Palermo chosen among who had passed the Human Anatomy exam brilliantly. The need to move to the UoM to take part in such activity derives from the lack of practice approach in Italian schools of medicine, focused mostly on the theoretical studies, neglecting practical experience. The heart dissection reveal itself as a huge opportunity to finally apply our anatomical knowledge, improving it and enabling us to compare images took from books to the actual organ. We had the chance to handle a real heart, to appreciate its weight and consistence. We took part in coronary artery courses focusing on their functions within the heart machinery.This article summarizes the activities of the four-week whole body dissection course the main authors partecipated in August 2016 at the dissection hall of the University of Malta (UoM). Our team comprised 10 second-year medicine students from University of Palermo chosen among who had passed the Human Anatomy exam brilliantly. The need to molve to the UoM to take part in such activity derives from the lack of practice approach in Italian schools of medicine, focused mostly on the theoretical studies, neglecting practical experience. The heart dissection reveal itself as a huge opportunity to finally apply our anatomical knowledge, improving it and enabling us to compare image took from books to the actual organ. We had the chance to handle a real heart, to appreciate its weight and consistence. We took part in coronary artery courses focusing on their functions within the heart machinery
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