429 research outputs found

    Distributed control system for parallel-connected DC boost converters

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    The disclosed invention is a distributed control system for operating a DC bus fed by disparate DC power sources that service a known or unknown load. The voltage sources vary in v-i characteristics and have time-varying, maximum supply capacities. Each source is connected to the bus via a boost converter, which may have different dynamic characteristics and power transfer capacities, but are controlled through PWM. The invention tracks the time-varying power sources and apportions their power contribution while maintaining the DC bus voltage within the specifications. A central digital controller solves the steady-state system for the optimal duty cycle settings that achieve a desired power supply apportionment scheme for a known or predictable DC load. A distributed networked control system is derived from the central system that utilizes communications among controllers to compute a shared estimate of the unknown time-varying load through shared bus current measurements and bus voltage measurements.https://digitalcommons.mtu.edu/patents/1138/thumbnail.jp

    Agent-based microgrid architecture for generation following protocols

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    A system for predicting power and loads over a single, relatively short time horizon. More specifically, a system comprising a Storage Agent (S-agent) Cohort within a grid control society, wherein the system expands G and L intra-cohort protocols to allow the S-cohort to participate in power management of the grid by scheduling storage components in source or load roles as determined by the time-varying state of the power imbalance and by the risk-adjusting capacity margin relationship between the G and L cohorts.https://digitalcommons.mtu.edu/patents/1145/thumbnail.jp

    Answer to the universe| [Short stories]

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    Vasopressin Antagonism in Heart Failure

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    Treatment of chronic heart failure (HF) is based on interference with the renin-angiotensin-aldosterone system and the adrenergic nervous system. Diuretics are used in volume-expanded patients. Insights from clinical trials and registries establish the need to consider correcting both cardiac loading conditions and nonload-related biological factors if HF therapy is to be optimized. Arginine vasopressin (AVP) represents a potentially attractive target for therapy in both acute and chronic HF. Excessive AVP secretion could contribute to both systolic and diastolic wall stress via V1a- and V2-mediated effects on the peripheral vasculature and on water retention. Arginine vasopressin also may directly and adversely affect myocardial function due to the effect of V1a activation on myocardial contractility and cell growth. Last, AVP may contribute to hyponatremia, a powerful predictor of poor outcome in HF. The development of effective nonpeptide antagonists to both the V1a and V2 receptors for AVP now allows for testing the hypotheses that interfering with AVP-mediated signaling could be beneficial in HF. This review summarizes the theoretical rationale for further development of such therapy, reviews the status of current compounds under development, and suggests key issues that need to be addressed as these agents undergo further clinical testing

    A systematic review of Futsal literature

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    This document systematically reviews literature to provide a summary of evidence based research related to the sport of futsal. The review draws on diverse subjects including coaching, physiological, psychological, technical and tactical elements of the sport as well as reviewing subjects relating to the development of futsal. The methodology included a scoping study and review protocol to systematically review 601 documents relating to futsal; 44 of these documents were reviewed in the study. The review aims to provide a resource for fellow researchers, to study the sport and encourage further English language studies in futsal. To that end, gaps in the literature are highlighted by the researchers, and therefore this document acts as a guide for further study

    The world at their feet: a combined historical ranking of nations competing in football and futsal

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    Some elite football players (e.g. Cristiano Ronaldo, Lionel Messi, Neymar and Andres Iniesta) endorse the benefits of futsal and express how it has helped them to develop as football players. This has contributed to an increase in futsal development activity, in some countries, leading to interest into the relationship between the two sports. A lack of research exists to explain the developmental relationship between the two sports, aside from anecdotal evidence from players, coaches and media commentators, some of whom acclaim futsal for its role in developing elite footballers. This study investigates the relationship which exists between the two sports, by providing the first ever combined historical rank of nations competing in futsal and football. The results highlight the most successful nations as well as a 'select group' that appear to be in an advantageous position to develop in future. It also provides indicative evidence as to the relationship between the two sports and recommends that both sports may be able to benefit from a more collaborative approach to development

    A Parameter Study of the Dust and Gas Temperature in a Field of Young Stars

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    We model the thermal effect of young stars on their surrounding environment in order to understand clustered star formation. We take radiative heating of dust, dust-gas collisional heating, cosmic-ray heating, and molecular cooling into account. Using Dusty, a spherical continuum radiative transfer code, we model the dust temperature distribution around young stellar objects with various luminosities and surrounding gas and dust density distributions. We have created a grid of dust temperature models, based on our modeling with Dusty, which we can use to calculate the dust temperature in a field of stars with various parameters. We then determine the gas temperature assuming energy balance. Our models can be used to make large-scale simulations of clustered star formation more realistic.Comment: 29 pages, 19 figures. Submitted to Ap

    Impact of anthropogenic disturbance on the chemistry of a small urban pond

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    Mirror Lake, one of the scenic locations on The Ohio State University\u27s campus, experiences an intense bioturbation event as part of an annual tradition revolving around the rivalry football game against the University of Michigan. This tradition involves thousands of students jumping into the lake over one night in the week leading up to the football game. Water samples were collected from several locations in the lake before, during, and after the Mirror Lake Jump to determine the impact of this event on lake water chemistry. There were significant and systematic increases in the concentrations of Na+, K+, Cl−, total nitrogen, ammonia, and dissolved organic carbon (DOC) associated with the jump, especially in the eastern side of the lake where most of the students entered. Over the 3-h period from 10 p.m. to 1 a.m. on the eastern side of the lake, Na+, K+, and Cl− concentrations increased by about 2–4 ppm, 1.5–3 ppm, and 4–6 ppm, respectively. The total nitrogen concentration increased about five to six fold, from 450–500 ppb to 2300–2800 ppb over the height of the event on the eastern side of the lake. Similar increases were observed for DOC, increasing from 3.6 to 18 ppm. This DOC increase was coincident with a 5‰ shift in δ13C, from a mean of around −28‰ in the early hours of the evening to a maximum of −23‰, implying a large influx of isotopically heavy carbon into the lake. Ammonia concentrations varied substantially from year to year, but always showed a systematic increase in concentration during the event. Smaller changes in major ion and nutrient concentrations were observed in the middle and western side of the lake, where fewer students entered the lake. The changes in concentration and the timing and spatial distribution of these changes are primarily attributed to anthropogenic input from jumpers in the form of bodily fluids (e.g., evaporated sweat, sebum and urine). Over a single night, these anthropogenic event inputs represent roughly 10% of the annual nitrogen budget of the lake, emphasizing the direct impact humans can have on urban water bodies on short time scales

    Dual Vasopressin Receptor Antagonism to Improve Congestion in Patients With Acute Heart Failure:Design of the AVANTI Trial

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    Background: Loop diuretics are the main treatment for patients with acute heart failure, but are associated with neurohormonal stimulation and worsening renal function and do not improve long-term outcomes. Antagonists to arginine vasopressin may provide an alternative strategy to avoid these effects. The AVANTI study will investigate the efficacy and safety of pecavaptan, a novel, balanced dual-acting V1a/V2 vasopressin antagonist, both as adjunctive therapy to loop diuretics after admission for acute heart failure, and later as monotherapy. Methods and Results: AVANTI is a double-blind, randomized phase II study in 571 patients hospitalized with acute heart failure and signs of persistent congestion before discharge. In part A, patients will receive either pecavaptan 30 mg/d or placebo with standard of care for 30 days. In part B, eligible patients will continue treatment or receive pecavaptan or diuretics as monotherapy for another 30 days. The primary end points for part A are changes in body weight and serum creatinine; for part B, changes in body weight and blood urea nitrogen/creatinine ratio. Conclusions: This study will provide the first evidence that a balanced V1a/V2 antagonist may safely enhance decongestion, both as an adjunct to loop diuretics and as an alternative strategy
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