1,428 research outputs found
OPEN ACCESS AND MISSING MARKETS IN ARTISANAL FISHING
This paper combines a model of open access fisheries exploitation with a distance-based approach to missing labor and product markets. The model generates predictions about the circumstances under which exploitation increases or decreases with distance. An econometric model is estimated with survey data from artisanal fishing households in Minahasa, Indonesia. The results can be used to assess the impacts of improved transportation infrastructure on fishery exploitation.Marketing,
A Search for Low Surface Brightness Structure Around Compact Narrow Emission Line Galaxies
As the most extreme members of the rapidly evolving faint blue galaxy
population at intermediate redshift, the compact narrow emission line galaxies
(CNELGs) are intrinsically luminous (-22 < M_B < -18) with narrow emission
linewidths (30 < \sigma < 125 km/s). Their nature is heavily debated: they may
be low-mass starbursting galaxies that will fade to present-day dwarf galaxies
or bursts of star formation temporarily dominating the flux of more massive
galaxies, possibly related to in situ bulge formation or the formation of cores
of galaxies. We present deep, high-quality (~0.6 - 0.8 arcsec) images with CFHT
of 27 CNELGs. One galaxy shows clear evidence for a tidal tail; the others are
not unambiguously embedded in galactic disks. Approximately 55% of the CNELGS
have sizes consistent with local dwarfs of small-to-intermediate sizes, while
45% have sizes consistent with large dwarfs or disks galaxies. At least 4
CNELGs cannot harbor substantial underlying disk material; they are
low-luminosity galaxies at the present epoch (M_B > -18). Conversely, 15 are
not blue enough to fade to low-luminosity dwarfs (M_B > -15.2). The majority of
the CNELGs are consistent with progenitors of intermediate-luminosity dwarfs
and low-luminosity spiral galaxies with small disks. CNELGs are a heterogeneous
progenitor population with significant fractions (up to 44%) capable of fading
into today's faint dwarfs (M_B > -15.2), while 15 to 85% may only experience an
apparently extremely compact CNELG phase at intermediate redshift but remain
more luminous galaxies at the present epoch.Comment: 16 pages, 14 figures, emulateapj, published in Ap
Active utilization of a full DC-Link voltage in multilevel converter
© 2018 IEEE. Multilevel inverter technology has emerged recently as a very important alternative in the area of high-power medium-voltage energy conversion. Multilevel inverter reduces the inductors and filters size, whilst improving the output power quality. However, the main drawback of the multi-level inverter topologies is that they utilizes only ≤ 50% of the input dc-bus voltage, i.e. they require two times the peak of ac output voltage. For example, the nominal input voltage of the NPC, ANPC and Flying Capacitor is 800 V dc . This high dc-link voltage not only requires higher voltage components (both active and passive) but also prompts to use an additional front-end boost dc-dc converter. Considering these aspects, this paper presents a novel technique to extend the input dc-bus voltage utilization in any conventional multilevel inverter from ≤ 50% to ≤ 100%. The novel technique utilizes an additional T-type module (consist of four active switches), which is inserted just before the two dc-link capacitor forming a new grounding point. The novel method not only reduces the input voltage requirement and voltage stress, but also increases the output voltage levels of the inverter. In general, this technique can be implemented to any multilevel inverter. An example of implementation of 5L inverter from the conventional 3-Level T-type inverter is discussed and validated. Measurement results shows that the new Dual T-type inverter has a flat efficiency « 99 % over a wide range of load
Chemically Active Wetting
Wetting of liquid droplets on passive surfaces is ubiquitous in our daily
lives, and the governing physical laws are well-understood. When surfaces
become active, however, the governing laws of wetting remain elusive. Here we
propose chemically active wetting as a new class of active systems where the
surface is active due to a binding process that is maintained away from
equilibrium. We derive the corresponding non-equilibrium thermodynamic theory
and show that active binding fundamentally changes the wetting behavior,
leading to steady, non-equilibrium states with droplet shapes reminiscent of a
pancake or a mushroom. The origin of such anomalous shapes can be explained by
mapping to electrostatics, where pairs of binding sinks and sources correspond
to electrostatic dipoles along the triple line. This is an example of a more
general analogy, where localized chemical activity gives rise to a multipole
field of the chemical potential. The underlying physics is relevant for cells,
where droplet-forming proteins can bind to membranes accompanied by the
turnover of biological fuels
Diastereoselective synthesis of optically active (2R,5R)-hexanediol
Erworben im Rahmen der Schweizer Nationallizenzen (http://www.nationallizenzen.ch)Diastereoselective reduction of diketones with Lactobacillus kefir DSM 20587 was examined. The reduction of both oxo-functions proceeded highly diastereoselectively. (2R,5R)-Hexanediol 3 was produced starting from (2,5)-hexanedione 1 in quantitative yields with enantiomeric excess >99% and diastereomeric excess >99%. The reaction conditions were optimized: maximum yield of (2R,5R)-hexanediol was reached at pH 6, 30°C and with equal amounts of substrate and cosubstrate. The applicability of the system in fed-batch experiments was demonstrated. The feed specific biomass concentration required to reach maximal yield and selectivity in fed-batch mode was determined
Analysis and design of a novel six-switch five-level active boost neutral point clamped inverter
This paper presents an analysis and design of
a new boost type six-switch five-level Active Neutral Point
Clamped (ANPC) inverter based on switched/flying capacitor
technique with self-voltage balancing. Compared to major
conventional 5-level inverter topologies, such as, Neutral
Point Clamped (NPC), Flying Capacitor (FC), Cascaded Hbridge (CHB) and Active NPC (ANPC) topologies, the new
topology reduces the dc-link voltage requirement by 50%.
Whilst reducing the dc-link voltage requirement, the number
and the size of the active and passive components are also
reduced without compromising the reactive power capability.
The analysis shows that the proposed topology is suitable
for wide range of power conversion applications (for
example, rolling mills, fans, pumps, marine appliances,
mining, tractions, and most prominently grid-connected
renewable energy systems). Experimental results from a 1.2-
kVA prototype justifies the concept of the proposed inverter
with a conversion efficiency of around 97.5% ± 1% for a wide
load range
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