992 research outputs found
A new coupling solution for G3-PLC employment in MV smart grids
This paper proposes a new coupling solution for transmitting narrowband multicarrier power line communication (PLC) signals over medium voltage (MV) power lines. The proposed system is based on an innovative PLC coupling principle, patented by the authors, which exploits the capacitive divider embedded in voltage detecting systems (VDS) already installed inside the MV switchboard. Thus, no dedicated couplers have to be installed and no switchboard modifications or energy interruptions are needed. This allows a significant cost reduction of MV PLC implementation. A first prototype of the proposed coupling system was presented in previous papers: it had a 15 kHz bandwidth useful to couple single carrier PSK modulated PLC signals with a center frequency from 50–200 kHz. In this paper, a new prototype is developed with a larger bandwidth, up to 164 kHz, thus allowing to couple multicarrier G3-PLC signals using orthogonal frequency division multiplexing (OFDM) digital modulation. This modulation ensures a more robust communication even in harsh power line channels. In the paper, the new coupling system design is described in detail. A new procedure is presented for tuning the coupling system parameters at first installation in a generic MV switchboard. Finally, laboratory and in-field experimental test results are reported and discussed. The coupling performances are evaluated measuring the throughput and success rate in the case of both 18 and 36 subcarriers, in one of the different tone masks standardized for the FCC-above CENELEC band (that is, from 154.6875–487.5 kHz). The experimental results show an efficient behavior of the proposed coupler allowing a two-way communication of G3-PLC OFDM signals on MV networks
Discontinuous transition in electrolyte flow through charge-patterned nanochannels
We investigate the flow of an electrolyte through a rigid nanochannel
decorated with a surface charge pattern. Employing lattice Boltzmann and
dissipative particle dynamics methods, as well as analytical theory, we show
that the electro-hydrodynamic coupling leads to two distinct flow regimes. The
accompanying discontinuous transition between slow, ionic, and fast, Poiseuille
flows is observed at intermediate ion concentrations, channel widths, and
electrostatic coupling strengths. These findings indicate routes to design
nanochannels containing a typical aqueous electrolyte that exhibit a digital
on/off flux response, which could be useful for nanofluidics and ionotronic
applications.Comment: 6 pages, 6 figure
A Pre-Protostellar Core in L1551
Large field surveys of NH3, C2S, 13CO and C18O in the L1551 dark cloud have
revealed a prolate, pre-protostellar molecular core (L1551-MC) in a relatively
quiescent region to the northwest of the well-known IRS 5 source. The kinetic
temperature is measured to be 9K, the total mass is ~2Msun, and the average
particle density is 10^4-10^5 cm^(-3). L1551-MC is 2.25' x 1.11' in projection
oriented at a position angle of 133deg. The turbulent motions are on the order
of the sound speed in the medium and contain 4% of the gravitational energy,
E_{grav}, of the core. The angular momentum vector is projected along the major
axis of L1551-MC corresponding to a rotational energy of 2.5E-3(sin
i)^(-2)|E_{grav}|. The thermal energy constitutes about a third of |E_{grav}|
and the virial mass is approximately equal to the total mass. L1551-MC is
gravitationally bound and in the absence of strong, ~160 microgauss, magnetic
fields will likely contract on a ~0.3 Myr time scale. The line profiles of many
molecular species suggest that the cold quiescent interior is surrounded by a
dynamic, perhaps infalling envelope which is embedded within the ambient
molecular gas of L1551.Comment: 27 pages, 7 figures, ApJ accepte
Financial Services Modernization: A Cure for Problem Banks?
On February 5, 1991, after consulting federal financial regulatory agencies and other interested governmental parties, the Department of the Treasury transmitted to Congress its report: Modernizing the Financial System: Recommendations for Safer, More Competitive Banks. The Treasury Report concludes that four major problems confront the U.S. banking system: (1) reduced bank competitiveness and financial strength, caused by outdated legal restrictions that prevent banks from responding to changing financial markets and technology; (2) the overextension of deposit insurance, resulting in excessive exposure for taxpayers and weakened market discipline for banks; (3) a fragmented regulatory system that has created duplicative rules and has often failed to produce decisive remedial action; and (4) an undercapitalized deposit insurance fund. To address these problems, the Treasury Report recommends four fundamental legislative reforms: (1) to increase bank competitiveness, Congress should authorize nation-wide banking, new financial activities for banks, and commercial ownership of banks; (2) to reduce taxpayer exposure and increase market discipline, Congress should reduce the scope of deposit insurance, require a link between regulatory supervision and capital strength, and require risk-based insurance premiums for deposit insurance; (3) to reduce duplicative rules and produce decisive remedial action, Congress should streamline the federal regulatory system; and (4) to recapitalize the Bank Insurance Fund, Congress should adopt a funding plan based on contributions from the banking industry, rather than from the Treasury and the taxpayers. After a very basic historical review of past attempts to reform the banking industry, this Article focuses on the less publicized portions of the Treasury recommendations in an attempt to identify some of the issues that would remain unsettled, even if the proposals are enacted into law
Galactosylsphingamides : new α-GalCer analogues to probe the F’-pocket of CD1d
Invariant Natural Killer T-cells (iNKT-cells) are an attractive target for immune response modulation, as upon CD1d-mediated stimulation with KRN7000, a synthetic alpha-galactosylceramide, they produce a vast amount of cytokines. Here we present a synthesis that allows swift modification of the phytosphingosine side chain by amidation of an advanced methyl ester precursor. The resulting KRN7000 derivatives, termed alpha-galactosylsphingamides, were evaluated for their capacity to stimulate iNKT-cells. While introduction of the amide-motif in the phytosphingosine chain is tolerated for CD1d binding and TCR recognition, the studied alpha-galactosylsphingamides showed compromised antigenic properties
Brown rotting fungus closely related to Pseudomerulius curtisii (Boletales) recorded for the first time in South America.
In the region of Santa Maria, Southern Brazil, we have analyzed morphologically and molecularly
some interesting brown-rotting mushroom specimens closely related to Pseudomerulius curtisii.
Except for minor differences in morphology and ITS sequence similarity, collections have
corresponded to P. curtisii by basidiospore size and shape, the kind of hyphal system, the
macromorphology, the slightly unpleasant pungent spicy smell turning stronger upon drying and,
particularly, by the highly supported and closely related clade after phylogenetic analysis. Perhaps
due the rarity in nature, morphological data are not abundant in literature and appears to be
somewhat incomplete to discordant for the species, so we provide a more detailed description and
illustrations from collected specimens
An interface protection system based on an embedded metrology system platform
The aim of this work is to present an interface protection system (IPS) for Distributed Generators (DG) and Energy Storage Systems (ESS). The new prototype of IPS guarantees standard protection requirements, in terms of both voltage and frequency measurement accuracies and trip times. Moreover, it has the additional functionalities of implementing a communication link between the Distribution System Operator (DSO) and the DG and ESS Inverter. The new IPS is based on a smart meter platform with an integrated power line communication modem. Moreover, it has also an integrated metrology section. Experimental tests will show how this last feature allows a significant reduction of the measurement data access time allowing an improvement of trip time accuracy
Characterization of DC series arc faults in PV systems based on current low frequency spectral analysis
This work presents an experimental study focused on the characterization of series arc faults in direct current (DC) photovoltaic (PV) systems. The aim of the study is to identify some relevant characteristics of arcing current, which can be obtained by means of low frequency spectral analysis of current signal. On field tests have been carried out on a real PV system, in accordance with some tests requirements of UL 1699B Standard for protection devices against PV DC arc faults. Arcing and non-arcing current signals are acquired and compared and the behavior of a set of indicators proposed by authors is analyzed. Different measurement equipment have been used, in order to study the impact of both measurement transducers and data acquisition systems on proposed indicators effectiveness. Presented results show that the considered indicators are suitable for detecting the arc presence even with commercial devices normally used for smart metering applications
Brown rotting fungus closely related to Pseudomerulius curtisii (Boletales) recorded for the first time in South America
In the region of Santa Maria, Southern Brazil, we have analyzed morphologically and molecularly some interesting brown-rotting mushroom specimens closely related to Pseudomerulius curtisii. Except for minor differences in morphology and ITS sequence similarity, collections have corresponded to P. curtisii by basidiospore size and shape, the kind of hyphal system, the macromorphology, the slightly unpleasant pungent spicy smell turning stronger upon drying and, particularly, by the highly supported and closely related clade after phylogenetic analysis. Perhaps due the rarity in nature, morphological data are not abundant in literature and appears to be somewhat incomplete to discordant for the species, so we provide a more detailed description and illustrations from collected specimens
Not every edible orange milkcap is Lactarius deliciosus: first record of Lactarius quieticolor (sect. Deliciosi) from Brazil
The natural distribution of species of Lactarius sect. Deliciosi is mainly in the northern hemisphere, where they grow in ectomycor-rhizal symbiosis mainly with conifers. Several species in this sec-tion are regionally well known and appreciated due to their culinary use. In South America, there is limited knowledge of their presence and harvesting, while their culinary value remains underexploited. Recently, field campaigns in pine plantations in southern Brazil revealed wide presence of Lactarius sect. Deliciosi species. Morpho-logical and molecular identification approaches confirmed that all Brazilian collections correspond to one European species, Lactarius quieticolor. Fruiting bodies occurred in plantations of Pinus taeda and/or P. elliottii, on acidic soils, and under humid climate with mild to hot summers. A review of edibility and organoleptic properties confirmed both L. quieticolor and its commonly misapplied name, L. deliciosus, in South America as edible and of high quality. Several other L. sect. Deliciosi species are less appreciated or with unknown palatability. Due to low potential for long-distance dispersal, an ecto-mycorrhizal partner switch from European to North American pine species is proposed, which may have happened in South America for both allochthonous symbiotic partners. There is still a possibility that other combinations were established, including combinations with less valuable species from L. sect. Deliciosi
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