925 research outputs found
Properties of (GaIn)O over the whole range
Using density-functional ab initio theoretical techniques, we study
(GaIn)O in both its equilibrium structures (monoclinic
and bixbyite) and over the whole range of composition. We establish
that the alloy exhibits a large and temperature-independent miscibility gap. On
the low- side, the favored phase is isostructural with -GaO;
on the high- side, it is isostructural with bixbyite InO. The
miscibility gap opens between approximately 15\% and 55\% In content for the
bixbyite alloy grown epitaxially on InO, and 15\% and 85\% In content
for the free-standing bixbyite alloy. The gap, volume and band offsets to the
parent compound also exhibit anomalies as function of . Specifically, the
offsets in epitaxial conditions are predominantly type-B staggered, but have
opposite signs in the two end-of-range phases.Comment: 7 pages, 4 figure
Structure and gap of low- (GaIn)O alloys
We study the electronic and local structural properties of pure and
In-substituted -GaO using density functional theory (DFT). Our
main result is that the structural energetics of In in GaO causes most
sites to be essentially inaccessible to In substitution, thus reducing the
maximum In content in thi to somewhere between 12 and 25 \% in this phase. We
also find that the gap variation with doping is essentially due to "chemical
pressure", i.e. volume variations with doping.Comment: 4 pages, 3 figure
From the extraction of currently fulfilled requirements to value curves: a case-study in the field of harvesting machines for shell fruits and lessons learnt in engineering design
The market for agricultural machinery is characterized by products with a high degree of maturity in the product life cycle. Consequently, current improvements in new machinery are predominantly incremental and new projects basically use solutions that are already consolidated. This makes this domain appropriate for benchmarking existing systems and envisioning new value propositions. The present paper deals primarily with the former and uses the value curves as a means to structure the comparison among different families of technical systems; in particular, harvesting machines for shell fruits from the ground surface, e.g., chestnuts, walnuts, and hazelnuts, were investigated here. The process of building value curves requires the identification of currently fulfilled requirements. Despite the attention paid by engineering design research to requirements, a structured process is lacking to extract relevant information and create value curves or other representations useful for benchmarking. The present paper approaches this problem and presents how the authors have individuated relevant knowledge for characterizing different categories of harvesting machines. Namely, after an extensive search of the scientific literature and patents, a critical review of existing machines, aimed at individuating their functioning principles, architecture, and attitude in fulfilling specific design requirements, was performed. Then, existing machines were classified in 8 main categories, and their strengths and weaknesses were identified with reference to 11 competing factors. The consequent construction of value curves enabled the identification of possible points of intervention by hypothesizing possible future evolutions of such machinery, both in a structural and in a value-based perspective. Limitations about the repeatability of the followed approach and possible repercussions on design research are discussed
Lightning performance evaluation of Italian 150 kV sub-transmission lines
A significant majority of overhead transmission lines' (OHLs) outages is due to backflashovers caused by direct lightning strikes: the realistic assessment of the lightning performance is thus an important task. The paper presents the analysis of the lightning performance of an existing 150kVItalian OHL, namely, its backflashover rate (BFOR), carried out by means of anATP-EMTP-based Monte Carlo procedure. Among other features, the procedure makes use of a simplified pi-circuit for line towers' grounding system, allowing a very accurate reproduction of transient behaviours at a very low computational cost. Tower grounding design modifications, aimed at improving the OHL lightning performance, are also proposed and discussed
Biochemical characterization of a multi-drug resistant HIV-1 subtype AG reverse transcriptase: antagonism of AZT discrimination and excision pathways and sensitivity to RNase H inhibitors
We analyzed a multi-drug resistant (MR) HIV-1 re-
verse transcriptase (RT), subcloned from a patient-
derived subtype CRF02
AG, harboring 45 amino acid
exchanges, amongst them four thymidine analog
mutations (TAMs) relevant for high-level AZT (azi-
dothymidine) resistance by AZTMP excision (M41L,
D67N, T215Y, K219E) as well as four substitutions
of the AZTTP discrimination pathway (A62V, V75I,
F116Y and Q151M). In addition, K65R, known to an-
tagonize AZTMP excision in HIV-1 subtype B was
present. Although MR-RT harbored the most signif-
icant amino acid exchanges T215Y and Q151M of
each pathway, it exclusively used AZTTP discrimi-
nation, indicating that the two mechanisms are mu-
tually exclusive and that the Q151M pathway is ob-
viously preferred since it confers resistance to most
nucleoside inhibitors. A derivative was created, ad-
ditionally harboring the TAM K70R and the rever-
sions M151Q as well as R65K since K65R antago-
nizes excision. MR-R65K-K70R-M151Q was compe-
tent of AZTMP excision, whereas other combinations
thereof with only one or two exchanges still pro-
moted discrimination. To tackle the multi-drug resis-
tance problem, we tested if the MR-RTs could still be
inhibited by RNase H inhibitors. All MR-RTs exhibited similar sensitivity toward RNase H inhibitors be-
longing to different inhibitor classes, indicating the
importance of developing RNase H inhibitors further
as anti-HIV drugs
ESA SENTINEL 2 IMAGERY AND GBGEOAPP: INTEGRATED TOOLS FOR THE DEOSAI NATIONAL PARK MANAGEMENT PLAN
Deosai plateau, in the Gilgit-Baltistan Province of Pakistan, for its average elevation of 4,114 meters, is the second highest plateau in the world after Changtang Tibetan Plateau. Two biogeographically important mountain ranges merge in Deosai: the Himalayan and Karakorum–Pamir highlands. The Deosai National Park, with its first recognition in 1993, encompasses an area of about 1620 km2, with the altitude ranging from 3500 to 5200 meters a.s.l. It is known and visited by tourists for the presence of brown bear, but a large number of species of fauna and flora leave, and can be seen during the summer season. This high-altitude ecosystem is particularly fragile and can be considered a sentinel for the effects of climate changes.
Due to its geographic position and high altitude, the area of Deosai has never been studied in all its ecosystem components, producing high resolution maps. The first land cover map of Deosai with 10 meters of resolution is discussed in this study. This map has been obtained from Sentinel-2 imagery and improved through the new tool developed in this study: the GBGEOApp. This application for mobile has been done with three main ambitions: the validation of the new land cover map, its improvement with land use information, and the collection of new data in the field. On the basis of the results, the use of the GBGEOApp, as a tool for validation and increasing of environmental data collection, seems to be completely applicable involving the local technicians in a process of data sharing
Arthrobacter sp. Inoculation Improves Cactus Pear Growth, Quality of Fruits, and Nutraceutical Properties of Cladodes
A study was undertaken to determine the effects of a strain of Arthrobacter sp., a Plant Growth-Promoting Bacteria (PGPB), on plant phenology and qualitative composition of Opuntia ficus-indica (L.) Mill. fruits and cladodes. The strain was inoculated in soil, and its effects on cactus pear plants were detected and compared to nontreated plants. Compared to the latter, the treatment with bacteria promoted an earlier plant sprouting (2 months before the control) and fruitification, ameliorating fruit quality (i.e., improved fresh and dry weight: + 24% and + 26%, respectively, increased total solid content by 30% and polyphenols concentrations by 22%). The quality and quantity of monosaccharides of cladodes were also increased by Arthrobacter sp. with a positive effect on their nutraceutical value. In summer, the mean values of xylose, arabinose, and mannose were significantly higher in treated compared to not treated plants (+ 3.54; + 7.04; + 4.76 mg/kg d.w. respectively). A similar trend was observed in autumn, when the cladodes of inoculated plants had higher contents, i.e., 33% xylose, 65% arabinose, and 40% mannose, respect to the controls. In conclusion, Arthrobacter sp. plays a role in the improvement of nutritional and nutraceutical properties of cactus pear plants due to its capabilities to promote plant growth. Therefore, these results open new perspectives in PGPB application in the agro-farming system as alternative strategy to improve cactus pear growth, yield, and cladodes quality, being the latter the main by-product to be utilized for additional industrial uses
Developing fiber lasers with Bragg reflectors as deep sea hydrophones
The present paper will discuss the work in progress at the Department of Physics of the University of Pisa in collaboration
with the IFAC laboratory of CNR in Florence to develop pressure sensors with outstanding sensitivity
in the acoustic and ultrasonic ranges. These devices are based on optically-pumped fiber lasers, where the
mirrors are Bragg gratings written into the fiber core
Near real-time analysis of active distribution networks in a Digital Twin framework. A real case study
The growth of distributed generation and the need of increasing Distribution Network (DN) resilience is encouraging Distribution System Operators (DSO) to increase awareness about the real-time status of the network as well as to actively manage flexible energy resources for improving system performances. In this context, Digital Twin (DT) is an enabling technology for a low-cost distributed framework that supports DN management. DT in the power system can be exploited taking advantage of the successful experiences in other sectors (e.g., smart manufacturing and building automation). This article presents a real case study of a DT development and its integration with an existing DN. The DT system architecture is based on the recent standards whilst main DT components have been originally developed, enabling near real-time services such as data collection, state estimation, and flexibility calculator. The individual performances of the integrated tools and the reliability of DT were tested and validated during one month of continuous operation. During the operation, good service continuity and accuracy performances were reported. Results from the flexibility calculator show the effectiveness of the proposed strategies that can improve the energy efficiency of the DN by increasing local self-consumption of Renewable Energy Sources (RES) production
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