658 research outputs found

    Implementation of wavelet-based robust differential control for electric vehicle application

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    This research letter presents the modeling and simulation of electronic differential, employing a novel wavelet controller for two brushless dc motors. The proposed controller uses discrete wavelet transform to decompose the error between actual and reference speed. Error signal that is actually given by the electronic differential based on throttle and steering angle is decomposed into frequency components. Numerical simulation results are provided for both wavelet and proportional-integral-derivate controllers. In comparison, the proposed wavelet control technique provides greater stability and ensures smooth control of the two back driving wheels

    Torsion cycles as non-local magnetic sources in non-orientable spaces

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    Non-orientable spaces can appear to carry net magnetic charge, even in the absence of magnetic sources. It is shown that this effect can be understood as a physical manifestation of the existence of torsion cycles of codimension one in the homology of space.Comment: 17 pages, 4 figure

    Nonexistence of marginally trapped surfaces and geons in 2+1 gravity

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    We use existence results for Jang's equation and marginally outer trapped surfaces (MOTSs) in 2+1 gravity to obtain nonexistence of geons in 2+1 gravity. In particular, our results show that any 2+1 initial data set, which obeys the dominant energy condition with cosmological constant \Lambda \geq 0 and which satisfies a mild asymptotic condition, must have trivial topology. Moreover, any data set obeying these conditions cannot contain a MOTS. The asymptotic condition involves a cutoff at a finite boundary at which a null mean convexity condition is assumed to hold; this null mean convexity condition is satisfied by all the standard asymptotic boundary conditions. The results presented here strengthen various aspects of previous related results in the literature. These results not only have implications for classical 2+1 gravity but also apply to quantum 2+1 gravity when formulated using Witten's solution space quantization.Comment: v3: Elements from the original two proofs of the main result have been combined to give a single proof, thereby circumventing an issue with the second proof associated with potential blow-ups of solutions to Jang's equation. To appear in Commun. Math. Phy

    Evolving Lorentzian Wormholes

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    Evolving Lorentzian wormholes with the required matter satisfying the Energy conditions are discussed. Several different scale factors are used and the corresponding consequences derived. The effect of extra, decaying (in time) compact dimensions present in the wormhole metric is also explored and certain interesting conclusions are derived for the cases of exponential and Kaluza--Klein inflation.Comment: 10 pages( RevTex, Twocolumn format), Two figures available on request from the first author. transmission errors corrected

    Estimated Lifetime Benefit of Combined RAAS and SGLT2 Inhibitor Therapy in Patients with Albuminuric CKD without Diabetes

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    Background and objectives: Despite high rates of complications in patients with CKD without diabetes, the implementation of proven therapies in this group remains low. Expressing the clinical benefitofatherapyin terms of extra years free from the disease or death may facilitate implementation. We estimated lifetime survival free of kidney failure for patients with albuminuric CKD without diabetes treated with the combination therapy of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and sodium-glucose cotransporter-2 (SGLT2) inhibitors relative to patients not treated. Design, setting, participants, & measurements: We used trial-level estimates of the effect of treatment with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (ramipril/benazepril; n=690) and SGLT2 inhibitors (dapagliflozin; n=1398) compared with placebo to derive the effect of combination therapy versus no treatment. Using this effect, we estimated treatment effect of combination therapy to the active treatment group of patients with albuminuric CKD without diabetes participating in the Dapagliflozin and Prevention of Adverse Outcomes in Chronic Kidney Disease (DAPA-CKD) trial (n=697) and projected eventfree and overall survival for those treated and not treated with combination therapy. We also performed our calculations anticipating lower adherence and less pronounced benefits than were observed in the clinical trials. The primary outcome was a composite of doubling of serum creatinine, kidney failure, or death. Results: The aggregate estimated hazard ratio comparing combination therapy with angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and SGLT2 inhibitor versus no treatment for the primary end point was 0.35 (95% confidence interval, 0.30 to 0.41). For a 50-year-old patient until the age of 75 years, the estimated survival free from the primary composite end point was 17.0 (95% confidence interval, 12.4 to 19.6) years with the combination therapy and 9.6 years (95% confidence interval, 8.4 to 10.7) with no treatment with any of these agents, corresponding to a gain in eventfree survival of 7.4 (95% confidence interval, 6.4 to 8.7) years. When assuming lower adherence and less pronounced efficacy of combination therapy, the gain in eventfree survival ranged from 5.3 years (95% confidence interval, 4.4 to 6.1) to 5.8 years (95% confidence interval, 4.8 to 6.8). Conclusions: Treatment with the combination of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and SGLT2 inhibitor in patients with albuminuric CKD without diabetes is expected to substantially increase kidney failure–free survival. Clinical Trial registry name and registration number: Benazepril for Advanced Chronic Renal Insufficiency, NCT00270426, and a Study to Evaluate the Effect of Dapagliflozin on Renal Outcomes and Cardiovascular Mortality in Patients with Chronic Kidney Disease (Dapa-CKD), NCT03036150

    The Limits of Special Relativity

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    The Special Theory of Relativity and the Theory of the Electron have had an interesting history together. Originally the electron was studied in a non relativistic context and this opened up the interesting possibility that lead to the conclusion that the mass of the electron could be thought of entirely in electromagnetic terms without introducing inertial considerations. However the application of Special Relativity lead to several problems, both for an extended electron and the point electron. These inconsistencies have, contrary to popular belief not been resolved satisfactorily today, even within the context of Quantum Theory. Nevertheless these and subsequent studies bring out the interesting result that Special Relativity breaks down within the Compton scale or when the Compton scale is not neglected. This again runs contrary to an uncritical notion that Special Relativity is valid for point particles.Comment: 13 pages,Te

    Effects of newer kidney protective agents on kidney endpoints provide implications for future clinical trials

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    Doubling of serum creatinine (equivalent to a 57% decline in the estimated glomerular filtration rate (eGFR)) is an accepted component of a composite kidney endpoint in clinical trials. Smaller declines in eGFR (40%, 50%) have been applied in several recently conducted clinical trials. Here, we assessed the effects of newer kidney protective agents on endpoints including smaller proportional declines in eGFR to compare relative event rates and the magnitude of observed treatment effects. We performed a post hoc analysis of 4401 patients in the CREDENCE, 4304 in the DAPA-CKD, 5734 in the FIDELIO-DKD, and 3668 in the SONAR trials, which assessed the effects of canagliflozin, dapagliflozin, finerenone and atrasentan in patients with chronic kidney disease. Effects of active therapies versus placebo on alternative composite kidney endpoints incorporating different eGFR decline thresholds (40%, 50%, or 57% eGFR reductions from baseline) with kidney failure or death due to kidney failure were compared. Cox-proportional hazards regression models were used to assess and compare treatment effects. During follow-up, event rates were higher for endpoints incorporating smaller versus larger eGFR decline thresholds. Compared to the treatment effects on kidney failure or death due to kidney failure, the magnitude of relative treatment effects was generally similar when considering composite endpoints incorporating smaller declines in eGFR. Hazard ratios for the four interventions ranged from 0.63 to 0.82 for the endpoint incorporating 40% eGFR decline and 0.59 to 0.76 for the endpoint incorporating 57% eGFR decline. Clinical trials incorporating a 40% eGFR decline in a composite endpoint would require approximately half the number of participants compared to a 57% eGFR decline with equivalent statistical power. Thus, in populations at high risk of CKD progression, the relative effects of newer kidney protective therapies appear generally similar across endpoints based on varying eGFR decline thresholds.</p

    Plant Growth Optimization by Vegetable Production System in HI-SEAS Analog Habitat

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    The Vegetable Production System (Veggie) is a scientific payload designed to support plant growth for food production under microgravity conditions. The configuration of Veggie consists of an LED lighting system with modular rooting pillows designed to contain substrate media and time-release fertilizer. The pillows were designed to be watered passively using capillary principles but have typically been watered manually by the astronauts in low-Earth orbit (LEO). The design of Veggie allows cabin air to be drawn through the plant enclosure for thermal and humidity control and for supplying CO2 to the plants. Since its delivery to the International Space Station (ISS) in 2014, Veggie has undergone several experimental trials by various crews. Ground unit testing of Veggie was conducted during an 8-month Mars analog study in a semi-contained environment of a simulated habitat located at approximately 8,200 feet (2,500 m) elevation on the Mauna Loa volcano on the Island of Hawaii. The Hawaii Space Exploration Analog and Simulation (HI-SEAS) offered conditions (habitat, mission, communications, etc.) intended to simulate a planetary exploration mission. This paper provides data and analyses to show the prospect for optimized use of the current Veggie design for human habitats. Lessons learned during the study may provide opportunities for updating the system design and operational parameters for current Veggie experiments being conducted onboard the ISS and for payloads on future deep space missions
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