Determination of compressor in-stall characteristics from engine surge transients

A technique for extracting the in-stall pumping characteristics for an axial flow compressor operating in an engine system environment is developed. The technique utilizes a Hybrid computer simulation of the compressor momentum equation into which actual transient data are used to provide all terms but the desired compressor characteristic. The compressor force characteristic as a function of corrected flow and speed result from the computation. The critical problem of data filtering is addressed. Results for a compressor operating in a turbofan engine are presented and comparison is made with the conventional compressor map. The relationship of the compressor surge characteristic with its rotating stall characteristic is explored. Initial interpretation of the measured results is presented

Endpoint thermodynamics of an atomic Fermi gas subject to a Feshbach resonance

The entropy and kinetic, potential, and interaction energies of an atomic Fermi gas in a trap are studied under the assumption of thermal equilibrium for finite temperature. A Feshbach resonance can cause the fermions to pair into diatomic molecules. The entropy and energies of mixtures of such molecules with unpaired atoms are calculated, in relation to recent experiments on molecular Bose-Einstein condensates produced in this manner. It is shown that, starting with a Fermi gas of temperature $T= 0.1 T_F^0$, where $T_F^0$ is the non-interacting Fermi temperature, an extremely cold degenerate Fermi gas of temperature $T \lesssim 0.01 T_F^0$ may be produced without further evaporative cooling. This requires adiabatic passage of the resonance, subsequent sudden removal of unpaired atoms, and adiabatic return. We also calculate the ratio of the interaction energy to the kinetic energy, a straightforward experimental signal which may be used to determine the temperature of the atoms and indicate condensation of the molecules.Comment: 12 pages, 5 figure

Sympterygia acuta, Bignose Fanskate

The Bignose Fanskate (Sympterygia acuta) is a small (to 62 cm total length) skate that occurs in the Southwest Atlantic from Rio de Janeiro, Brazil to Bahía Blanca, Buenos Aires, Argentina. It inhabits the continental shelf from inshore to 188 m depth. It is captured in intense largely unmanaged demersal trawl fisheries throughout its geographic range. It is one of the most commercially important species and the wings are sold mainly to Asian markets at high prices. In southern Brazil, research trawl catchper-unit-effort revealed a decline in biomass of 74.5% between 1974 and 2005, equivalent to a population reduction of >83% scaled over three generations (40.5 years). This species is a target of the longline fishery in Uruguay, but now it is uncommonly captured in research trawl surveys there. Further, in Argentina, total skate landings have peaked and are declining as a result of overfishing. Overall, due to intense and largely managed trawl fisheries that operate throughout its geographic and depth range, it is suspected that the Bignose Fanskate has undergone a population reduction of >80% over the past three generations (40.5 years), and it is assessed as Critically Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Centro Nacional Pesquisa E Conservação Da Biodiversidad; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; Urugua

Atlantoraja cyclophora, Eyespot Skate

The Eyespot Skate (Atlantoraja cyclophora) is a small (to 74 cm total length) skate that occurs in the Southwest Atlantic from Rio de Janeiro, Brazil to San Matías Gulf, Argentina. It inhabits the continental shelf from inshore to 100 m depth, and occasionally to 320 m. It is captured in intensive and largely unmanaged demersal trawl fisheries which operate throughout its geographic and depth range. In southern Brazil there are no time-series of abundance, but fisheries there are intense and it is suspected that they are leading to population reduction. In Uruguay, research trawl catch-per-uniteffort of this species declined 82% from 1,910 kg/hr in 2004–2013 to 343 kg/hr from 2013 to 2017, equivalent to a >95% population reduction scaled over three generations (40.5 years). In the Rio del Plata Estuary, the landings of coastal rays including this species was low until the mid-1990s, but increased retention led to substantial increases in landings which peaked in 2008, followed by a decline. In Argentina, reported landings of skates in general increased from 900 t in 1993 to a peak of 28,000 t in 2007, and then declined to 24,000 t in 2009–2010. Overall, due to intense and increasing fishing pressure across its range, decreasing abundance, and its relatively slow life history, it is suspected that the Eyespot Skate has undergone a population reduction of 50–79% over the past three generations (40.5 years), and it is assessed as Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Faria, V.. Universidade Federal Do Ceara; BrasilFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; Urugua

Atlantoraja castelnaui, Spotback Skate

The Spotback Skate (Atlantoraja castelnaui) is a medium-sized (to 147 cm total length) skate that occurs in the Southwest Atlantic from Rio de Janeiro, Brazil, to Buenos Aires, Argentina. It inhabits the continental shelf and upper slope from inshore to 300 m depth. It is captured in intense and largely unmanaged demersal trawl fisheries throughout its geographic range. Two lines of evidence indicate a population reduction. First, in Santa Catarina State, Brazil, catch-per-unit-effort (CPUE) declined by an estimated 54% between 1974 and 1981. Second, a 75% decline in CPUE was estimated from 1994 to 1999 in Rio Grande do Sul, Brazil. Both declines are consistent with a population reduction of >99% over three generation lengths (48 years). This large skate has a slow life history, and many skates with similar characteristics have undergone severe population reductions and face increased extinction risk. It is highly susceptible to exploitation and does not have any refuge from fishing at depth. Overall, due to declining abundance from intense and largely unmanaged fishing through most of its range combined with its large size and presumed late age-at-maturity (and therefore high sensitivity to fishing pressure), it is suspected that the Spotback Skate has undergone a population reduction of >80% over the past three generation lengths (48 years), and it is assessed as Critically Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Faria, V.. Universidade Federal Do Ceara; BrasilFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Direccion Nacional de Recursos Acuaticos ; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Pseudobatos horkelii, Brazilian Guitarfish

The Brazilian Guitarfish (Pseudobatos horkelii) is a small (to 138 cm total length) shark-like ray that occurs in the Southwest Atlantic from Rio de Janeiro, Brazil, to northern Argentina. It is demersal on soft substrates of the continental shelf inshore to 150 m depth. It is captured in intense and largely unmanaged commercial and artisanal demersal trawl, gillnet, longline, and beach seine fisheries throughout its geographic range. There are three estimates of population reduction. First, in Rio Grande do Sul, total landings increased from 842 t in 1975 to 1,804 t in 1984 and then declined continuously to 157 t in 2001, the equivalent of a >99% reduction over three generations (55.5 years). Second, the average research trawl catch-per-unit-effort of Brazilian Guitarfish in southern Brazil over the years 1993 to 1999 was 17% of that observed during 1975 to 1986, also the equivalent of a >99% reduction over three generations. Fisheries remain intense and unmanaged there. Third, in Uruguay, this guitarfish is captured frequently in gillnets and longlines, is landed, and is sometimes targeted, and it is also captured in artisanal trawl fisheries. Catches from research trawls there in the 1980s and early 1990s were on average around 1,400 kg/hr, and between 2013 and 2017 were only 480 kg/hr, the equivalent of a >92% reduction over three generations. In Argentina, it is suspected that intense and inadequately managed gillnet fishing pressure has led to declines in abundance there as well. Overall, due to intense and inadequately managed fishing pressure throughout its range, and steep population declines, it is inferred that the Brazilian Guitarfish has undergone a population reduction of >80% over the past three generations (55.5 years), and it is assessed as Critically Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Martins, M. F.. Universidade Federal Do Rio Grande.; BrasilFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Atlantoraja platana, La Plata skate

The La Plata Skate (Atlantoraja platana) is a medium-sized (to 91 cm total length) skate that occurs in the Southwest Atlantic from Espírito Santo, Brazil to Chubut, Argentina. It inhabits clay, mud, and sand substrates on the continental shelf and upper slope from inshore to 320 m depth. This skate is captured in intensive and largely unmanaged demersal trawl fisheries throughout its range. In southern Brazil, this skate is subjected to intense industrial and artisanal fishing pressure and it is suspected that this has led to declines in abundance there. In Argentina, reported landings of skates in general increased from 900 t in 1993 to a peak of 28,000 t in 2007, and then declined to 24,000 t in 2009–2010. It is smaller-bodied than the Critically Endangered congeneric Spotback Skate (Atlantoraja castelnaui), and by comparison is suspected to be less sensitive to fishing pressure. Although it is still common in catches, the combination of widespread intensive fishing pressure across its range, inadequate management measures, its high catchability, and declines in reported overall skate catches, it is suspected that the La Plata Skate has undergone a population reduction of 50–79% over the past three generations (40.5 years), and it is assessed as Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Faria, V.. Universidade Federal Do Ceara; BrasilFil: Montealegre-Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos ; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Myliobatis ridens, Shortnose Eagle Ray

The Shortnose Eagle Ray (Myliobatis ridens) is a medium-sized (to 70 cm disc width) ray that occurs in the Southwest Atlantic from Santa Catarina, Brazil, to Buenos Aires Province, Argentina. It inhabits inshore bays and estuaries at depths of 5-47 m. It is captured in intense and largely unmanaged artisanal gillnet and beach seine fisheries throughout much of its geographic range. The meat from this species may be consumed or sold locally or discarded. In Rio Grande do Sul, beach seine and drifting gillnet fisheries are intense and capture this species in relatively high numbers. Eagle rays, in general, declined in that state by 91% in research trawls between 1974 and 2005. Gillnets are used in Argentina to target elasmobranchs, including eagle rays, and it is suspected that declines have occurred there due to overfishing. Overall, due to the level of intense and largely unmanaged fisheries that operate throughout its range, its lack of refuge at depth, its unproductive life history, and noted declines in eagle rays in general, it is suspected that the Shortnose Eagle Ray has undergone a population reduction of >80% over the past three generations (18 years), and it is assessed as Critically Endangered A2bd.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Psammobatis bergi, Blotched Sandskate

The Blotched Sandskate (Psammobatis bergi) is a small (to 61 cm total length) skate that occurs in the Southwest Atlantic from Rio de Janeiro, Brazil to the northern San Jorge Gulf, Chubut, Argentina. It inhabits the inner continental shelf at depths of 10-80 m. It is caught in demersal trawl fisheries, which are intense in parts of its range. It is typically discarded dead where caught. Its continued common presence in trawls and its small size suggest that it may have a productive enough life history to withstand fishing pressure and the population is suspected to be stable. Therefore, the Blotched Sandskate is assessed as Least Concern.Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi

Narcine brasiliensis, Lesser Numbfish

The Lesser Numbfish (Narcine brasiliensis) is a small (to 45 cm total length) ray that occurs in the Southwest Atlantic from southern Brazil to Buenos Aires Province, Argentina. It is benthic on soft substrates of the continental shelf at depths of 6?60 m. It is captured in intense and largely unmanaged commercial and artisanal trawl and beach seine fisheries throughout much of its geographic range. A population reduction is suspected from the peak and subsequent declines in reported ray landings from the Rio del Plata area. This species is discarded when caught and discard survival rates are unknown, but are suspected to be variable based on the injuries of captured individuals. Although this ray is subject to high fishing pressure across its range, it is still observed commonly in fisheries despite this pressure. It is suspected that the Lesser Numbfish has undergone a population reduction of 20-29% over the past three generations (26 years), and it is assessed as Near Threatened (nearly meeting Vulnerable A2d).Fil: Pollom, R.. University Fraser Simon; CanadáFil: Barreto, R.. Instituto Chico Mendes de Conservacao Da Biodiversidade; BrasilFil: Charvet, P.. Universidade Federal do Paraná; BrasilFil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); ArgentinaFil: Cuevas, J. M.. Wildlife Conservation Society; Estados UnidosFil: Faria, V.. Universidade Federal Do Ceara; BrasilFil: Herman, K.. Georgia Aquarium; Estados UnidosFil: Marcante, F.. Universidade Federal Do Rio Grande.; BrasilFil: Montealegre Quijano, S.. Universidade Federal de Sao Paulo; BrasilFil: Motta, F.. Universidade Federal de Sao Paulo; BrasilFil: Paesch, L.. Dirección Nacional de Recursos Acuáticos; UruguayFil: Rincon, G.. Universidade Federal Do Maranhao.; Brasi