Multi-Scale Hydrologic Evaluation Of The National Water Model Streamflow Data Assimilation

Streamflow predictions derived from a hydrologic model are subjected to many sources of errors, including uncertainties in meteorological inputs, representation of physical processes, and model parameters. To reduce the effects of these uncertainties and thus improve the accuracy of model prediction, the United States (U.S.) National Water Model (NWM) incorporates streamflow observations in the modeling framework and updates model-simulated values using the observed ones. This updating procedure is called streamflow data assimilation (DA). This study evaluates the prediction performance of streamflow DA realized in the NWM. We implemented the model using WRF-Hydro® with the NWM modeling elements and assimilated 15-min streamflow data into the model, observed during 2016–2018 at 140 U.S. Geological Survey stream gauge stations in Iowa. In its current DA scheme, known as nudging, the assimilation effect is propagated downstream only, which allows us to assess the performance of streamflow predictions generated at 70 downstream stations in the study domain. These 70 locations cover basins of a range of scales, thus enabling a multi-scale hydrologic evaluation by inspecting annual total volume, peak discharge magnitude and timing, and an overall performance indicator represented by the Kling–Gupta efficiency. The evaluation results show that DA improves the prediction skill significantly, compared to open-loop simulation, and the improvements increase with areal coverage of upstream assimilation points

Evaluation of a naturally derived waste brown oil extract for demulsification of crude oil emulsion

Conventional methods of eliminating water from crude oil such as the chemical injection have both economic and environmental impacts; thus, this study proposed an economic and environmentally friendly demulsifier. The bottle test method was used to study the performance of the natural extract and commercial demulsifier on a crude oil sample. The GC-MS profile of the extract was in agreement with previous reports on composition of oil extracted from rice bran using hexane, ultrasound assisted extraction and conventional solvent extraction with ethanol. Varying degrees of saturated and unsaturated fatty acids as well as retention times as observed, was a function of total time of scanning, according to NIST08 library of mass spectra. The performance of the demulsifier was expressed in terms of percentage of water separated from 100 ml samples of the oil samples. For both the demulsifiers, the performance increased with increase in volume of the demulsifier, separation time and operating temperature. The extracted demulsifier performed better than the chemical demulsifier under all the experimental conditions adopted in this study. Based on the parametric evaluation, it was observed the results from software corroborated the results obtained from experiments in terms of the observations of the combined effect of temperature and volume which showed the most significant influence on demulsification of the emulsified crude. The highest efficiency of the bio-demulsifier was obtained with a volume of 5 mL of the extract, at a temperature of 70�C and separation time of 60 min

Thermal Conductivity and Viscosity Of Al2o3 Nanofluids for Different Based Ratio of Water and Ethylene Glycol Mixture

In the thermal engineering applications, suspension of nanoparticles in conventional fluid has positive potential in enhancing the convective heat transfer performance. The evaluation of thermo-physical properties is essential to investigate the forced convection heat transfer of nanofluids. Hence, the present study reports the analysis on thermal conductivity and dynamic viscosity for Al2O3 nanoparticle dispersed in a different volume ratio of water (W) and ethylene glycol (EG) mixture. The Al2O3 nanofluids are formulated using the two-step method for three different base mixtures with volume ratio of 40:60, 50:50 and 60:40 (W:EG). The measurement of thermal conductivity and viscosity were performed using KD2 Pro Thermal Properties Analyzer and Brookfield LVDV-III Rheometer; respectively for temperature from 30 to 70 °C and volume concentration of 0.2–1.0%. The average thermal conductivity enhancement of Al2O3 nanofluids in the three base ratios varied from 2.6 to 12.8%. The nanofluids have better enhancement as the percentage of ethylene glycol increases. Meanwhile, the average dynamic viscosity enhanced up to 50% for 60:40 (W:EG). The enhancement of viscosity for nanofluids decreased with the increment percentage of ethylene glycol. The properties enhancement of the Al2O3 nanofluids is significantly influenced by the concentration, temperature, and based ratio

An Experimental Investigation of Leak Rate Performance of a Subscale Candidate Elastomer Docking Space Seal

A novel docking seal was developed for the main interface seal of NASA s Low Impact Docking System (LIDS). This interface seal was designed to maintain acceptable leak rates while being exposed to the harsh environmental conditions of outer space. In this experimental evaluation, a candidate docking seal assembly called Engineering Development Unit (EDU58) was characterized and evaluated against the Constellation Project leak rate requirement. The EDU58 candidate seal assembly was manufactured from silicone elastomer S0383-70 vacuum molded in a metal retainer ring. Four seal designs were considered with unique characteristic heights. The leak rate performance was characterized through a mass point leak rate method by monitoring gas properties within an internal control volume. The leakage performance of the seals were described herein at representative docking temperatures of -50, +23, and +50 C for all four seal designs. Leak performance was also characterized at 100, 74, and 48 percent of full closure. For all conditions considered, the candidate seal assemblies met the Constellation Project leak rate requirement

Role Of Embolic Protection In Transcatheter Aortic Valve Replacement: Results From The Deflect I Study

Utilization of a cerebral protection device during transcatheter aortic valve replacement (TAVR) will reduce the rate of periprocedural stroke as well as the occurrence and volume of new lesions on diffusion weighted magnetic resonance imaging (DW-MRI), which may serve as a potential surrogate endpoint for clinical studies. The DEFLECT I study is a prospective, multi-center, single arm study that aims to demonstrate the safety and performance of the TriGardTM Embolic Deflection Device (EDD) (Keystone Heart, Caesarea Business Park, Israel), among patients undergoing TAVR. Primary endpoints were device performance and in-hospital device-related safety. A powered secondary endpoint was the number and volume of new DW-MRI brain lesions. Of the 20 consecutive patients enrolled, the device performed as intended with complete vessel coverage until completion of the valve implant in 80% of cases. The hierarchical composite in-hospital procedure-related major adverse cardiac and cerebrovascular (MACCE) event rates was 10% due to 2/20 major disabling strokes, which occurred the day after the procedure following urgent surgery for a failed TAVR implant and a cardiac arrest due to loss of pacer capture. Compared with historical controls, the number of new ischemic brain lesions detected on DW-MRI were similar (70% vs. 76%); however, patients undergoing TAVR with the TriGardTM EDD device demonstrated a 94% reduction in the maximum lesion volume, a 94% reduction in maximum total lesion volume, and a 65% reduction in mean lesion volume compared with historical controls. An angiographic sub-study demonstrated that the only clinical factor associated with the maintenance of device coverage throughout the procedure was anchorage of the upper stabilizer in the innominate artery. The DEFLECT I study established proof of concept of the TriGardTM device and justifies further evaluation in a planned randomized clinical trial

Evaluation of the impact of recycled concrete aggregates on the durability of concrete

The building industry has one of the most significant contributions to global warming due to the production of building materials, transportation, building activities and demolition of structures. When the buildings and structures reach the end of their life-span, they are commonly demolished, and debrice is landfield or backfilled if it is evaluated as non-contaminated inert construction and demolition waste (CDW). Implementation of circularity of material and circular economy can significantly reduce pollution and reduce the need for natural resources and opening of new CDW landfills. The use of recycled concrete aggregates (RCA) is one of the possibilities, how to reduce the depletion of raw materials for concrete production. Concrete is the most used building material worldwide, and aggregates constitute 70% of its volume. RCA can replace a certain amount of natural aggregates (NA), and concrete will still perform as required. Aim of this master thesis will be the evaluation of RCA itself, concrete with RCA and its durability performance, particularly freeze-thaw resistance, chloride migration coefficient, resistance to water under pressure and shrinkage. Performance of concrete with two different amounts of RCA will be compared to reference concrete with NA

A population pharmacokinetic model of gentamicin in paediatric oncology patients to facilitate improved therapeutic drug monitoring

To ensure the safe and effective dosing of gentamicin in children, therapeutic drug monitoring (TDM) is recommended. TDM utilizing Bayesian forecasting software is recommended but is unavailable, as no population model that describes the pharmacokinetics of gentamicin in pediatric oncology patients exists. This study aimed to develop and externally evaluate a population pharmacokinetic model of gentamicin to support personalized dosing in pediatric oncology patients. A nonlinear mixed-effect population pharmacokinetic model was developed from retrospective data. Data were collected from 423 patients for model building and a further 52 patients for external evaluation. A two-compartment model with first-order elimination best described the gentamicin disposition. The final model included renal function (described by fat-free mass and postmenstrual age) and the serum creatinine concentration as covariates influencing gentamicin clearance (CL). Final parameter estimates were as follow CL, 5.77 liters/h/70 kg; central volume of distribution, 21.6 liters/70 kg; peripheral volume of distribution, 13.8 liters/70 kg; and intercompartmental clearance, 0.62 liter/h/70 kg. External evaluation suggested that current models developed in other pediatric cohorts may not be suitable for use in pediatric oncology patients, as they showed a tendency to overpredict the observations in this population. The final model developed in this study displayed good predictive performance during external evaluation (root mean square error, 46.0%; mean relative prediction error, -3.40%) and may therefore be useful for the personalization of gentamicin dosing in this cohort. Further investigations should focus on evaluating the clinical application of this model

Facile Synthesis of Ordered Mesoporous Orthorhombic Niobium Oxide (T-Nb2_2O5_5) for High-Rate Li-Ion Storage with Long Cycling Stability

Herein, we describe the synthesis and evaluation of hierarchical mesoporous orthorhombic niobium oxide (T-Nb$_2$O$_5$) as an anode material for rechargeable lithium-ion batteries (LIB). The as-synthesized material addresses key challenges such as beneficial porous structure, poor rate capability, and cycling performance of the anode for Li-ion devices. The physicochemical characterization results reveal hierarchical porous nanostructure morphology with agglomerated particles and a 20 to 25 nm dimension range. Moreover, the sample has a high specific surface area (~65 m$^2$ g$^{−1}$) and pore volume (0.135 cm3 g$^{−1}$). As for the application in Li-ion devices, the T-Nb$_2$O$_5$ delivered an initial discharging capacity as high as 225 mAh g$^{−1}$ at 0.1 A g$^{−1}$ and higher rate capability as well as remarkable cycling features (~70% capacity retention after 300 cycles at 250 mA g$^{−1}$) with 98% average Coulombic efficiency (CE). Furthermore, the scan rate-dependent charge storage mechanism of the T-Nb$_2$O$_5$ electrode material was described, and the findings demonstrate that the electrode shows an evident and highly effective pseudocapacitive Li intercalation behaviour, which is crucial for understanding the electrode process kinetics. The origin of the improved performance of T-Nb$_2$O$_5$ results from the high surface area and mesoporous structure of the nanoparticles

Energy Efficiency of a Chiller using R410A or R32

An advanced simulation model of a packaged air cooled water chiller was developed. The nominal cooling capacity of the chiller is about 70 kW at 35°C dry bulb outdoor air temperature, and it consists of a single refrigerating circuit with two identical scroll compressors. The compressor was characterised by its experimental performance curve according to EN 12900 for both R410A and R32. Off-the-shelf copper tubes and louvered aluminium fins were considered for the condenser and typical brazed plate configurations for the evaporator. The finned coil condenser and the brazed plate heat exchanger evaporator were modelled by an elementary finite volumes technique, previously validated in other papers; for each volume the heat transfer coefficient and the pressure drop were calculated using semi-empirical correlations chosen among the most accurate ones available in the open literature. The aim of the paper is to compare the performance of R410A with that of R32 which is considered as a possible HFC substitute with lower GWP (675 instead of 2088). The condenser was optimised for R410A and R32 independently with regard to the number of internal circuits according to the so-called Performance Evaluation Criteria [1], without changing the overall heat exchanger dimensions. An analysis of the seasonal efficiency for each finned coil circuitry configuration (both with the same compressors) was carried out in terms of European Seasonal Energy Efficiency Ratio (ESEER) calculated according to the EN 14825 specifications for water chillers. We were able to conclude from that modelling work, that R32 system efficiency performance is acceptable as alternative to R410 for water chillers and further simulation analyses will include evaluating HFO blends