Review of alternative fuels data bases

Based on an analysis of the interaction of fuel physical and chemical properties with combustion characteristics and indicators, a ranking of the importance of various fuel properties with respect to the combustion process was established. This ranking was used to define a suite of specific experiments whose objective is the development of an alternative fuels design data base. Combustion characteristics and indicators examined include droplet and spray formation, droplet vaporization and burning, ignition and flame stabilization, flame temperature, laminar flame speed, combustion completion, soot emissions, NOx and SOx emissions, and the fuels' thermal and oxidative stability and fouling and corrosion characteristics. Key fuel property data is found to include composition, thermochemical data, chemical kinetic rate information, and certain physical properties

Multiple-scale turbulence modeling of boundary layer flows for scramjet applications

As part of an investigation into the application of turbulence models to the computation of flows in advanced scramjet combustors, the multiple-scale turbulence model was applied to a variety of flowfield predictions. The model appears to have a potential for improved predictions in a variety of areas relevant to combustor problems. This potential exists because of the partition of the turbulence energy spectrum that is the major feature of the model and which allows the turbulence energy dissipation rate to be out of phase with turbulent energy production. The computations were made using a consistent method of generating experimentally unavailable initial conditions. An appreciable overall improvement in the generality of the predictions is observed, as compared to those of the basic two-equation turbulence model. A Mach number-related correction is found to be necessary to satisfactorily predict the spreading rate of the supersonic jet and mixing layer

A mathematical model of a large open fire

A mathematical model capable of predicting the detailed characteristics of large, liquid fuel, axisymmetric, pool fires is described. The predicted characteristics include spatial distributions of flame gas velocity, soot concentration and chemical specie concentrations including carbon monoxide, carbon dioxide, water, unreacted oxygen, unreacted fuel and nitrogen. Comparisons of the predictions with experimental values are also given

Optimal controllers design for voltage control in Off-grid hybrid power system

Generally, for remote places extension of grid is uneconomical and difficult. Off-grid hybrid power systems (OGHPS) has  renewable energy sources integrated with conventional sources. OGHPS is very significant as it is the only source of electric supply for remote areas. OGHPS under study  has Induction generator (IG) for wind power generation, Photo-Voltaic source with inverter, Synchronous generator (SG) for Diesel Engine (DE) and load. Over-rated PV-inverter has capacity to supply reactive power.  SG of  DE  has Automatic voltage regulator for excitation control to regulate terminal voltage. Load and IG demands reactive power, causes reactive power imbalance hence voltage fluctuations in OGHPS. To manage reactive power for voltage control, two control structures with Proportional–Integral controller(PI), to control  inverter reactive power and  SG excitation by automatic voltage regulator are incorporated.  Improper tuning of controllers lead  to oscillatory and sluggish response. Hence in this test system both controllers need to be tune optimally. This paper proposes novel intelligent computing algorithm , Enhanced Bacterial forging algorithm (EBFA) for optimal reactive power controller for voltage control in OGHPS. Small signal model of OGHPS with proposed controller is  tested for different disturbances. simulation results  are compared  with conventional  method , proved the effectiveness of EBFA

Acute kidney injury in patients hospitalized with COVID-19 in HIMS, Hassan

Background: There is a growing need to understand the risk factors and prevalence of AKI in COVID-19 patients to better manage and prevent the condition. HIMS, Hassan is a hospital in India that has been treating COVID-19 patients since the onset of the pandemic. This study aimed to determine the prevalence of acute kidney injury (AKI) in COVID-19 patients admitted to a hospital in HIMS, Hassan, and to identify the associated risk factors. Methods: The study is a retrospective cohort study that investigates the clinical characteristics and laboratory parameters of hospitalized COVID-19 patients who met the inclusion criteria in HIMS teaching hospital, Hassan. 300 patients were included, and descriptive statistical analysis was performed using mean with standard deviation (SD) for continuous variables and proportions and percentages for categorical variables. Results: Out of 300 patients, 68% had AKI. The age distribution was similar between the two groups, with the highest proportion of patients in the age group of 40-49 years. The proportion of AKI was higher among males than females, but the difference was not statistically significant. The need for ICU admission, mechanical ventilation, and dialysis was strongly associated with AKI. Patients with comorbidities such as DM and DM+HTN were at a higher risk of developing AKI. Laboratory parameters such as D-dimer, LDH, ferritin, urea, creatinine, SGOT, SGPT, Neutrophils / Lymphocytes ratio, and chloride levels were significantly different between the two groups. Conclusions: These findings highlight the importance of monitoring patients with comorbidities closely and implementing preventive measures to reduce the incidence of AKI in COVID-19 patients

A SURVEY ON ENCRYPTION ALGORITHMS AND PROTOCOLS IN SMART CARD FOR USER CENTRIC OWNERSHIP MODEL

User Centric Ownership Model (UCOM) enables the smart card users to install/delete application they prefer in their smart card. UCOM provides smart card users to have any number of applications installed on their smart cards. Though UCOM provides flexibility for the smart card users, it lacks centralized authority. UCOM creates major problem if the user has more than one application installed in his/her smart card.  Smart card may contain applications from the provider that may interrupt the proper working of the neighbor applications.  Smart card user may hack his way to a known aboutapplication through a smart card simulator. Thus, there is no security for an application in the smart card for UCOM model. This survey paper includes background and motivation about the available encryption algorithms for smart cards such as RSA, ECC, AES, DES, T-DES, ECDSA and the smart card protocols which can be used to overcome the problem of security for the applications in smart card for UCOM model

Long term flux variations in Cen X-3: clues from flux dependent orbital modulation and pulsed fraction

We have investigated the long term flux variation in Cen X-3 using orbital modulation and pulsed fraction in different flux states using observations made with the All Sky Monitor and the Proportional Counter Array on board the Rossi X-ray Timing Explorer. In the high state, the eclipse ingress and egress are found to be sharp whereas in the intermediate state the transitions are more gradual. In the low state, instead of eclipse ingress and egress, the lightcurve shows a smooth flux variation with orbital phase. The orbital modulation of the X-ray lightcurve in the low state shows that the X-ray emission observed in this state is from an extended object. The flux dependent orbital modulations indicate that the different flux states of Cen X-3 are primarily due to varying degree of obscuration. Measurement of the pulsed fraction in different flux states is consistent with the X-ray emission of Cen X-3 having one highly varying component with a constant pulsed fraction and an unpulsed component and in the low state, the unpulsed component becomes dominant. The observed X-ray emission in the low state is likely to be due to scattering of X-rays from the stellar wind of the companion star. Though we can not ascertain the origin and nature of the obscuring material that causes the aperiodic long term flux variation, we point out that a precessing accretion disk driven by radiative forces is a distinct possibility.Comment: 10 pages, 5 figures. Paper accepted for publication in MNRA

The Combinatorial World (of Auctions) According to GARP

Revealed preference techniques are used to test whether a data set is compatible with rational behaviour. They are also incorporated as constraints in mechanism design to encourage truthful behaviour in applications such as combinatorial auctions. In the auction setting, we present an efficient combinatorial algorithm to find a virtual valuation function with the optimal (additive) rationality guarantee. Moreover, we show that there exists such a valuation function that both is individually rational and is minimum (that is, it is component-wise dominated by any other individually rational, virtual valuation function that approximately fits the data). Similarly, given upper bound constraints on the valuation function, we show how to fit the maximum virtual valuation function with the optimal additive rationality guarantee. In practice, revealed preference bidding constraints are very demanding. We explain how approximate rationality can be used to create relaxed revealed preference constraints in an auction. We then show how combinatorial methods can be used to implement these relaxed constraints. Worst/best-case welfare guarantees that result from the use of such mechanisms can be quantified via the minimum/maximum virtual valuation function

Costs of streamlined HIV care delivery in rural Ugandan and Kenyan clinics in the SEARCH Studys.

OBJECTIVES/DESIGN:As antiretroviral therapy (ART) rapidly expands in sub-Saharan Africa using new efficient care models, data on costs of these approaches are lacking. We examined costs of a streamlined HIV care delivery model within a large HIV test-and-treat study in Uganda and Kenya. METHODS:We calculated observed per-person-per-year (ppy) costs of streamlined care in 17 health facilities in SEARCH Study intervention communities (NCT: 01864603) via micro-costing techniques, time-and-motion studies, staff interviews, and administrative records. Cost categories included salaries, ART, viral load testing, recurring goods/services, and fixed capital/facility costs. We then modeled costs under three increasingly efficient scale-up scenarios: lowest-cost ART, centralized viral load testing, and governmental healthcare worker salaries. We assessed the relationship between community-specific ART delivery costs, retention in care, and viral suppression. RESULTS:Estimated streamlined HIV care delivery costs were $291/ppy. ART ($117/ppy for TDF/3TC/EFV [40%]) and viral load testing ($110/ppy for 2 tests/year [39$51/ppy), recurring costs ($5/ppy), and fixed costs ($7/ppy). Optimized ART scale-up with lowest-cost ART ($100/ppy), annual viral load testing ($24/ppy), and governmental healthcare salaries ($27/ppy), lowered streamlined care cost to$163/ppy. We found clinic-to-clinic heterogeneity in retention and viral suppression levels versus streamlined care delivery costs, but no correlation between cost and either retention or viral suppression. CONCLUSIONS:In the SEARCH Study, streamlined HIV care delivery costs were similar to or lower than prior estimates despite including viral load testing; further optimizations could substantially reduce costs further. These data can inform global strategies for financing ART expansion to achieve UNAIDS 90-90-90 targets