Motor control for a brushless DC motor

This invention relates to a motor control system for a brushless DC motor having an inverter responsively coupled to the motor control system and in power transmitting relationship to the motor. The motor control system includes a motor rotor speed detecting unit that provides a pulsed waveform signal proportional to rotor speed. This pulsed waveform signal is delivered to the inverter to thereby cause an inverter fundamental current waveform output to the motor to be switched at a rate proportional to said rotor speed. In addition, the fundamental current waveform is also pulse width modulated at a rate proportional to the rotor speed. A fundamental current waveform phase advance circuit is controllingly coupled to the inverter. The phase advance circuit is coupled to receive the pulsed waveform signal from the motor rotor speed detecting unit and phase advance the pulsed waveform signal as a predetermined function of motor speed to thereby cause the fundamental current waveform to be advanced and thereby compensate for fundamental current waveform lag due to motor winding reactance which allows the motor to operate at higher speeds than the motor is rated while providing optimal torque and therefore increased efficiency

Seasonal contrasts in the diel vertical distribution, feeding behavior, and grazing impact of the copepod Temora Longicornis in Long Island Sound

We studied diel variability in vertical distribution, feeding behavior and grazing impact of female Temora longicornis in Long Island Sound on seven cruises from March to July. T. longicornis usually performed diel vertical migration characterized by deep residence during the day and ascent to near-surface waters at night for variable periods. The pattern of diel migration was independent of either the vertical distribution or relative abundance of chlorophyll in the water column. There was no clear evidence linking the amplitude of vertical migration to food concentration. Rather, the amplitude of migration decreased toward the end of the season probably due to animals avoiding warm waters (\u3e 17°C) near the surface. Gut pigment content showed diel variation characterized by maximum values during the nighttime. However, the estimated mean ingestion rate from the nighttime period was significantly greater than that of the daytime period in only 2 of 11 comparisons indicating that this copepod usually fed throughout the day at about the same rate. The shape of the diel curve was usually similar for females at 5 and 20 m. Usually there was no difference in gut content of females with depth even when differences in chlorophyll with depth were pronounced. Therefore, the diel variability in gut content was unlikely to result from continuous feeding in a vertically stratified food environment. Short-term (hourly) changes in chlorophyll concentration could not entirely account for changes in gut content over a diel cycle. We estimate that female T. longicornis removed daily \u3c 1–34% of the phytoplankton stock and \u3c 1–49% of the primary production in Long Island Sound. Estimates of daily carbon rations indicate that a herbivorous diet can satisfy the metabolic requirements and support egg production of T. longicornis throughout most of its season

Distribution, Abundance, and Biomass of the Macrozooplankton of Kaneohe Bay, Oahu, Hawaii 1966-1971

Many hundreds of zooplankton samples have been collected in Kaneohe Bay during the years 1950 through 1970, but data from the various studies completed during this interval are not generally available. This report makes available enumeration data from about 300 zooplankton samples collected between December 1966 and March 1971. A general feature of zooplankton distribution and abundance in the bay is that highest total zooplankton abundances are found in the eutrophic southeastern basin, but only a few species have their greatest abundance there. Most species abundances change along an environmental gradient. Spatial abundance patterns for the 19 most important macrozooplankton taxa are discussed. The data presented in this report are compared to results of studies completed by Hiatt (1951) and Piyakarnchana (1965). During the twentyyear period of 1950-1970, total zooplankton abundance seems to have increased somewhat, presumably as a result of eutrophication, but there have been few changes in zooplankton species composition. The only change is that macrocopepods have become less common in the southern sector of the bay and the pelagic tunicate, Oikopleura longicauda, has become more abundant

Seascape Connectivity of Gulf Sturgeon \u3ci\u3eAcipenser oxyrinchus desotoi\u3c/i\u3e Population Units Across the Northern Gulf of Mexico

Critical habitat was designated in 2003 for federally threatened anadromous Gulf sturgeon to aid in population recovery. This study examined overwintering Gulf sturgeon spatial use and movement through critical habitat monitored by the Ship Island acoustic array from 2011 to 2015. Previous studies observed western population Gulf sturgeon (Pearl and Pascagoula rivers) overwintering near the ends and within the passes of the barrier islands of the Mississippi Sound, USA. Recent telemetry studies detected eastern population fish (Escambia, Blackwater, Yellow, and Choctawhatchee rivers) overwintering as far west as Mobile Bay, Alabama; however, this study is the first to observe eastern population fish overwintering in western population critical habitat associated with the Ship Island array. Use of overwintering habitat was compared using mean active days detected and rate of travel to and from the array. There was no significant difference in mean active days of population units on the array; however, travel rate to the array from natal drainages was significantly different, with eastern population individuals traveling at a faster rate compared to western population individuals. Post hoc tests indicated that individuals from the Blackwater River had a significantly higher travel rate compared to Pascagoula River individuals. We documented large-scale seascape connectivity among population units of Gulf sturgeon across the northern Gulf of Mexico. Although large-scale seascape connectivity promotes mixing among population units and an exchange of marine nutrients into riverine environments, large-scale migration poses an issue for endangered species such as Gulf sturgeon, as there is greater risk of bycatch mortality and size-specific predation

Should coronary artery bypass graft surgery patients with mild or moderate aortic stenosis undergo concomitant aortic valve replacement? A decision analysis approach to the surgical dilemma

ObjectivesThis study utilizes Markov decision analysis to assess the relative benefits of prophylactic aortic valve replacement (AVR) at the time of coronary artery bypass graft surgery (CABG). Multiple sensitivity analyses were also performed to determine the variables that most profoundly affect outcome.BackgroundThe decision to perform CABG or concomitant CABG and AVR (CABG/AVR) in asymptomatic patients who need CABG surgery but have mild to moderate aortic stenosis (AS) is not clear-cut.MethodsWe performed Markov decision analysis comparing long-term, quality-adjusted life outcomes of patients with mild to moderate AS undergoing CABG versus CABG/AVR. Age-specific morbidity and mortality risks with CABG, CABG/AVR, and AVR after a prior CABG were based on the Society of Thoracic Surgeons national database (n = 1,344,100). Probabilities of progression to symptomatic AS, valve-related morbidity, and age-adjusted mortality rates were obtained from available published reports.ResultsFor average AS progression, the decision to replace the aortic valve at the time of elective CABG should be based on patient age and severity of AS measured by echocardiography. For patients under age 70 years, an AVR for mild AS is preferred if the peak valve gradient is >25 to 30 mm Hg. For older patients, the threshold increases by 1 to 2 mm Hg/year, so that an 85-year-old patient undergoing CABG should have AVR only if the gradient exceeds 50 mm Hg. The AS progression rate also influences outcomes. With slow progression (<3 mm Hg/year), CABG is favored for all patients with AS gradients <50 mm Hg; with rapid progression (>10 mm Hg/year), CABG/AVR is favored except for patients >80 years old with a valve gradient <25 mm Hg.ConclusionsThis study provides a decision aid for treating patients with mild to moderate AS requiring CABG surgery. Predictors of AS progression in individual patients need to be better defined

The Role of Lipids During Embryonic Development of the Euphausiids Euphausia Pacifica and Thysanoessa Spinifera

To understand the role of lipids during early embryogenesis, major lipid classes together with individual fatty acid and sterol composition were determined in embryos from multiple developmental stages of the euphausiids Euphausia pacifica and Thysanoessa spinifera. Average lipid content in embryos of E. pacifica and T. spiniferafrom the earliest stage (multicell) were 4.45 and 3.69 µg embryo-1,respectively. During development, the lipid content decreased at similar rates in the embryos of both species. In contrast to many crustacean eggs, phospholipids were the dominant lipid class in all embryonic stages, with decreasing concentrations seen during development. Individual fatty acids and sterols showed selective utilization during early developmental stages. The dominant fatty acids were 16:0 and 16:1ω7 and 20:5ω3, with most polyunsaturated fatty acids preferentially metabolized throughout early stages. An exception was 22:6ω3, which remained near constant through all stages. Cholesterol was the dominant sterol (\u3e82% of total sterols) in embryos, with only minor changes during development. The appearance of algal sterols and fatty alcohols, including phytol, in T. spinifera embryos suggests that considerable amounts of algal lipids are directly allocated to eggs during vitellogenesis. Despite the substantial changes in lipid amount and composition during embryo development, the presence of phospholipids as the dominate lipid store acts to moderate changes in egg-sinking rate for both species until the late (early and late limb-bud) stages of development

Survival, Growth and Reproduction of Non-Native Nile Tilapia II: Fundamental Niche Projections and Invasion Potential in the Northern Gulf of Mexico

Understanding the fundamental niche of invasive species facilitates our ability to predict both dispersal patterns and invasion success and therefore provides the basis for better-informed conservation and management policies. Here we focus on Nile tilapia (Oreochromis niloticus Linnaeus, 1758), one of the most widely cultured fish worldwide and a species that has escaped local aquaculture facilities to become established in a coastal-draining river in Mississippi (northern Gulf of Mexico). Using empirical physiological data, logistic regression models were developed to predict the probabilities of Nile tilapia survival, growth, and reproduction at different combinations of temperature (14 and 30°C) and salinity (0–60, by increments of 10). These predictive models were combined with kriged seasonal salinity data derived from multiple long-term data sets to project the species\u27 fundamental niche in Mississippi coastal waters during normal salinity years (averaged across all years) and salinity patterns in extremely wet and dry years (which might emerge more frequently under scenarios of climate change). The derived fundamental niche projections showed that during the summer, Nile tilapia is capable of surviving throughout Mississippi\u27s coastal waters but growth and reproduction were limited to river mouths (or upriver). Overwinter survival was also limited to river mouths. The areas where Nile tilapia could survive, grow, and reproduce increased during extremely wet years (2–368%) and decreased during extremely dry years (86–92%) in the summer with a similar pattern holding for overwinter survival. These results indicate that Nile tilapia is capable of 1) using saline waters to gain access to other watersheds throughout the region and 2) establishing populations in nearshore, low-salinity waters, particularly in the western portion of coastal Mississippi