397 research outputs found
War and Peace in Russia\u27s Realms: A&S 100 with Karen Petrone
No full textLater this spring, Professor Karen Petrone will begin teaching a new 7-week class as part of this year\u27s Passport to the World Program: Reimagining Russia’s Realms. The class, A&S: 100 - War & Peace in Russia\u27s Realms will explore the Russian and Soviet experience of World War I, the Russian Civil War, and World War II through literature, film, and history. Additionally, students will have the opportunity to discover Russian author Leo Tolstoy’s surprisingly influential role in the development of the non-violent resistance movement.
Petrone, the chair of the Department of History, hopes to help students analyze how Russian memories of past wars shape the country today. This topic is one Petrone is already quite familiar with—so much so in fact she\u27s written a book on the subject: The Great War in Russian Memory. The course also offers a unique opportunity for students to learn about Russia\u27s past through its connection to a series of other classes and a play that students will have the opportunity to see at the end of the semester
Distributed Maximum Power Point Tracking: Challenges and Commercial Solutions
No full textU ovom članku opisane su suvremene napredne tehnike za distribuirano postizanje maksimalne snage fotonaponskih sustava. Moderne aplikacije fotonaponskih sustava u urbanom smislu i održivoj mobilnosti zahtijevaju pravilno suočavanje s nedostacima uslijed djelomičnog zasjenjenja i različitih orijentacija ćelija fotonaponskog izvora. Razmatraju se najnovije arhitekture predložene u literaturi te su objašnjene njihove prednosti i nedostaci. Naposljetku, izloženi su trenutno dostupni proizvodi na tržištu te je dan pregled njihovih karakteristika i područja primjene.In this paper the state of the art of distributed maximum power point techniques for photovoltaic systems is discussed. Modern applications of photovoltaic systems in urban context and to sustainable mobility require the proper facing of drawbacks due to partial shading and different orientations of the cells the photovoltaic source is made of. The latest architectures proposed in literature are reviewed and their points of strength and weakness are discussed. Finally, the products that are currently available on the market are presented and their fields of application and features are overviewed
Early Detection of Photovoltaic Panel Degradation through Artificial Neural Network
No full textIn this paper, an artificial neural network (ANN) is used for isolating faults and degradation phenomena occurring in photovoltaic (PV) panels. In the literature, it is well known that the values of the single diode model (SDM) associated to the PV source are strictly related to degradation phenomena and their variation is an indicator of panel degradation. On the other hand, the values of parameters that allow to identify the degraded conditions are not known a priori because they can be different from panel to panel and are strongly dependent on environmental conditions, PV technology and the manufacturing process. For these reasons, to correctly detect the presence of degradation, the effect of environmental conditions and fabrication processes must be properly filtered out. The approach proposed in this paper exploits the intrinsic capability of ANN to map in its architecture two effects: (1) the non-linear relations existing among the SDM parameters and the environmental conditions, and (2) the effect of the degradation phenomena on the I−V curves and, consequently, on the SDM parameters. The ANN architecture is composed of two stages that are trained separately: one for predicting the SDM parameters under the hypothesis of healthy operation and the other one for degraded condition. The variation of each parameter, calculated as the difference of the output of the two ANN stages, will give a direct identification of the type of degradation that is occurring on the PV panel. The method was initially tested by using the experimental I−V curves provided by the NREL database, where the degradation was introduced artificially, later tested by using some degraded experimental I−V curves.Photovoltaic Materials and Device
Osteoclast activity around loaded and unloaded implants: a histological study in the beagle dog.
No full textThe mechanisms of bone loss around dental implants are poorly understood. The osteoclast is the most important bone-resorbing cell. Humoral factors seem able to stimulate the differentiation of osteoclasts from mononuclear phagocytes. Bacterial lipopolysaccharides seem to be directly involved in inflammatory bone loss by stimulation of the survival and fusion of preosteoclasts. Excessive load seems to be able to cause bone loss. The aim of this paper was to evaluate the presence and number of osteoclasts in peri-implant bone in control (unloaded) and test (loaded) implants in order to determine if loading per se could be a contributing factor in peri-implant bone resorption. Forty-eight implants were inserted in the mandibles of 4 beagle dogs. After 3 months, a prosthetic superstructure was inserted on 24 implants, whereas in 24 implants only the healing screws were positioned. Twenty-four implants (12 test and 12 control) were retrieved at 6 months, and 24 implants (12 test and 12 control) were retrieved at 12 months. All implants were osseointegrated. The number of osteoclasts found in the crestal bone in the first 3 mm from the implant surface was evaluated. The mean number of osteoclasts were the following: control implants (6 months), 5.66 +/- 0.81; control implants (12 months), 2.55 +/- 1.05; test implants (6 months), 5.25 +/- 1.55; and test implants (12 months), 2.5 +/- 1.0. No statistically significant differences were observed between the control and test implants. According to our data, loading does not seem to have a relevant importance on the osteoclast activation in peri-implant bone
Ab-initio molecular dynamics and hybrid explicit-implicit solvation model for aqueous and nonaqueous solvents: GFP chromophore in water and methanol solution as case study
No full textSolute–solvent interactions are proxies for understanding how the electronic density of a chromophore interacts with the environment in a more exhaustive way. The subtle balance between polarization, electrostatic, and non-bonded interactions need to be accurately described to obtain good agreement between simulations and experiments. First principles approaches providing accurate configurational sampling through molecular dynamics may be a suitable choice to describe solvent effects on solute chemical–physical properties and spectroscopic features, such as optical absorption of dyes. In this context, accurate energy potentials, obtained by hybrid implicit/explicit solvation methods along with employing nonperiodic boundary conditions, are required to represent bulk solvent around a large solute–solvent cluster. In this work, a novel strategy to simulate methanol solutions is proposed combining ab initio molecular dynamics, a hybrid implicit/explicit flexible solvent model, nonperiodic boundary conditions, and time dependent density functional theory. As case study, the robustness of the proposed protocol has been gauged by investigating the microsolvation and electronic absorption of the anionic green fluorescent protein chromophore in methanol and aqueous solution. Satisfactory results are obtained, reproducing the microsolvation layout of the chromophore and, as a consequence, the experimental trends shown by the optical absorption in different solvents
Exploring the Franck-Condon region of a photoexcited charge transfer complex in solution to interpret femtosecond stimulated Raman spectroscopy: excited state electronic structure methods to unveil non-radiative pathways
No full textWe present electronic structure methods to unveil the non-radiative pathways of photoinduced charge transfer (CT) reactions that play a main role in photophysics and light harvesting technologies. A prototypical π-stacked molecular complex consisting of an electron donor (1-chloronaphthalene, 1ClN) and an electron acceptor (tetracyanoethylene, TCNE) was investigated in dichloromethane solution for this purpose. The characterization of TCNE:π:1ClN in both its equilibrium ground and photoinduced low-lying CT electronic states was performed by using a reliable and accurate theoretical-computational methodology exploitingab initiomolecular dynamics simulations. The structural and vibrational time evolution of key vibrational modes is found to be in excellent agreement with femtosecond stimulated Raman spectroscopy experiments [R. A. Mathieset al.,J. Phys. Chem. A, 2018,122, 14, 3594], unveiling a correlation between vibrational fingerprints and electronic properties. The evaluation of nonadiabatic coupling matrix elements along generalized normal modes has made possible the interpretation on the molecular scale of the activation of nonradiative relaxation pathways towards the ground electronic state. In particular, two low frequency vibrational modes such as the out of plane bending and dimer breathing and the TCNE central CC stretching play a prominent role in relaxation phenomena from the electronic CT state to the ground state one
Application of inertial motion unit-based kinematics to assess the effect of boot modifications on ski jump landings—a methodological study
No full textBiomechanical studies of winter sports are challenging due to environmental conditions which cannot be mimicked in a laboratory. In this study, a methodological approach was developed merging 2D video recordings with sensor-based motion capture to investigate ski jump landings. A reference measurement was carried out in a laboratory, and subsequently, the method was exemplified in a field study by assessing the effect of a ski boot modification on landing kinematics. Landings of four expert skiers were filmed under field conditions in the jump plane, and full body kinematics were measured with an inertial motion unit (IMU)-based motion capture suit. This exemplary study revealed that the combination of video and IMU data is viable. However, only one skier was able to make use of the added boot flexibility, likely due to an extended training time with the modified boot. In this case, maximum knee flexion changed by 36◦ and maximum ankle flexion by 13◦, whereas the other three skiers changed only marginally. The results confirm that 2D video merged with IMU data are suitable for jump analyses in winter sports, and that the modified boot will allow for alterations in landing technique provided that enough time for training is given
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