Ribosome flow model with positive feedback

PubMed Central

Margaliot, Michael; Tuller, Tamir

2013-01-01

Eukaryotic mRNAs usually form a circular structure; thus, ribosomes that terminatae translation at the 3′ end can diffuse with increased probability to the 5′ end of the transcript, initiating another cycle of translation. This phenomenon describes ribosomal flow with positive feedback—an increase in the flow of ribosomes terminating translating the open reading frame increases the ribosomal initiation rate. The aim of this paper is to model and rigorously analyse translation with feedback. We suggest a modified version of the ribosome flow model, called the ribosome flow model with input and output. In this model, the input is the initiation rate and the output is the translation rate. We analyse this model after closing the loop with a positive linear feedback. We show that the closed-loop system admits a unique globally asymptotically stable equilibrium point. From a biophysical point of view, this means that there exists a unique steady state of ribosome distributions along the mRNA, and thus a unique steady-state translation rate. The solution from any initial distribution will converge to this steady state. The steady-state distribution demonstrates a decrease in ribosome density along the coding sequence. For the case of constant elongation rates, we obtain expressions relating the model parameters to the equilibrium point. These results may perhaps be used to re-engineer the biological system in order to obtain a desired translation rate. PMID:23720534

Hydraulic characteristics of the New River in the New River Gorge National River, West Virginia

USGS Publications Warehouse

Wiley, J.B.; Appel, David H.

1989-01-01

Traveltime, dispersion, water-surface and streambed profiles, and cross-section data were collected for use in application of flow and solute-transport models to the New River in the New River Gorge National River, West Virginia. Dye clouds subjected to increasing and decreasing flow rates (unsteady flow) showed that increasing flows shorten the cloud and decreasing flows lengthen the cloud. After the flow rate was changed and the flow was again steady, traveltime and dispersion characteristics were determined by the new rate of flow. Seven stage/streamflow relations identified the general changes of stream geometry throughout the study reach. Channel cross sections were estimated for model input. Low water and streambed profiles were developed from surveyed water surface elevations and water depths. (USGS)

Oil field management system

DOEpatents

Fincke, James R.

2003-09-23

Oil field management systems and methods for managing operation of one or more wells producing a high void fraction multiphase flow. The system includes a differential pressure flow meter which samples pressure readings at various points of interest throughout the system and uses pressure differentials derived from the pressure readings to determine gas and liquid phase mass flow rates of the high void fraction multiphase flow. One or both of the gas and liquid phase mass flow rates are then compared with predetermined criteria. In the event such mass flow rates satisfy the predetermined criteria, a well control system implements a correlating adjustment action respecting the multiphase flow. In this way, various parameters regarding the high void fraction multiphase flow are used as control inputs to the well control system and thus facilitate management of well operations.

U.S. EPA CSO CAPSTONE REPORT: CONTROL SYSTEM OPTIMIZATION

EPA Science Inventory

An optimized combined sewer overflow (CSO) requires a storage treatment system because storm flow in the combined sewer system is intermittent and highly variable in both pollutant concentration and flow rate. Storage and treatment alternatives are strongly influenced by input...

About influence of input rate random part of nonstationary queue system on statistical estimates of its macroscopic indicators

NASA Astrophysics Data System (ADS)

Korelin, Ivan A.; Porshnev, Sergey V.

2018-05-01

A model of the non-stationary queuing system (NQS) is described. The input of this model receives a flow of requests with input rate λ = λdet (t) + λrnd (t), where λdet (t) is a deterministic function depending on time; λrnd (t) is a random function. The parameters of functions λdet (t), λrnd (t) were identified on the basis of statistical information on visitor flows collected from various Russian football stadiums. The statistical modeling of NQS is carried out and the average statistical dependences are obtained: the length of the queue of requests waiting for service, the average wait time for the service, the number of visitors entered to the stadium on the time. It is shown that these dependencies can be characterized by the following parameters: the number of visitors who entered at the time of the match; time required to service all incoming visitors; the maximum value; the argument value when the studied dependence reaches its maximum value. The dependences of these parameters on the energy ratio of the deterministic and random component of the input rate are investigated.

Effect of Processing Parameters on Plastic Flow and Defect Formation in Friction-Stir-Welded Aluminum Alloy

NASA Astrophysics Data System (ADS)

Zeng, X. H.; Xue, P.; Wang, D.; Ni, D. R.; Xiao, B. L.; Ma, Z. Y.

2018-07-01

The effect of processing parameters on material flow and defect formation during friction stir welding (FSW) was investigated on 6.0-mm-thick 2014Al-T6 rolled plates with an artificially thickened oxide layer on the butt surface as the marker material. It was found that the "S" line in the stir zone (SZ) rotated with the pin and stayed on the retreating side (RS) and advancing side (AS) at low and high heat inputs, respectively. When the tool rotation rate was extremely low, the oxide layer under the pin moved to the RS first and then to the AS perpendicular to the welding direction, rather than rotating with the pin. The material flow was driven by the shear stresses produced by the forces at the pin-workpiece interface. With increases of the rotation rate, the depth of the shoulder-affected zone (SAZ) first decreased and then increased due to the decreasing shoulder friction force and increasing heat input. Insufficient material flow appeared in the whole of the SZ at low rotation rates and in the bottom of the SZ at high rotation rates, resulting in the formation of the "S" line. The extremely inadequate material flow is the reason for the lack of penetration and the kissing bonds in the bottom of the SZ at extremely low and low rotation rates, respectively.

Effect of Processing Parameters on Plastic Flow and Defect Formation in Friction-Stir-Welded Aluminum Alloy

NASA Astrophysics Data System (ADS)

Zeng, X. H.; Xue, P.; Wang, D.; Ni, D. R.; Xiao, B. L.; Ma, Z. Y.

2018-04-01

The effect of processing parameters on material flow and defect formation during friction stir welding (FSW) was investigated on 6.0-mm-thick 2014Al-T6 rolled plates with an artificially thickened oxide layer on the butt surface as the marker material. It was found that the "S" line in the stir zone (SZ) rotated with the pin and stayed on the retreating side (RS) and advancing side (AS) at low and high heat inputs, respectively. When the tool rotation rate was extremely low, the oxide layer under the pin moved to the RS first and then to the AS perpendicular to the welding direction, rather than rotating with the pin. The material flow was driven by the shear stresses produced by the forces at the pin-workpiece interface. With increases of the rotation rate, the depth of the shoulder-affected zone (SAZ) first decreased and then increased due to the decreasing shoulder friction force and increasing heat input. Insufficient material flow appeared in the whole of the SZ at low rotation rates and in the bottom of the SZ at high rotation rates, resulting in the formation of the "S" line. The extremely inadequate material flow is the reason for the lack of penetration and the kissing bonds in the bottom of the SZ at extremely low and low rotation rates, respectively.

Complete liquefaction methods and apparatus

DOEpatents

Turner, Terry D.; Wilding, Bruce M.

2013-10-15

A method and apparatus are described to provide complete gas utilization in the liquefaction operation from a source of gas without return of natural gas to the source thereof from the process and apparatus. The mass flow rate of gas input into the system and apparatus may be substantially equal to the mass flow rate of liquefied product output from the system, such as for storage or use.

An Ejector Air Intake Design Method for a Novel Rocket-Based Combined-Cycle Rocket Nozzle

NASA Astrophysics Data System (ADS)

Waung, Timothy S.

Rocket-based combined-cycle (RBCC) vehicles have the potential to reduce launch costs through the use of several different air breathing engine cycles, which reduce fuel consumption. The rocket-ejector cycle, in which air is entrained into an ejector section by the rocket exhaust, is used at flight speeds below Mach 2. This thesis develops a design method for an air intake geometry around a novel RBCC rocket nozzle design for the rocket-ejector engine cycle. This design method consists of a geometry creation step in which a three-dimensional intake geometry is generated, and a simple flow analysis step which predicts the air intake mass flow rate. The air intake geometry is created using the rocket nozzle geometry and eight primary input parameters. The input parameters are selected to give the user significant control over the air intake shape. The flow analysis step uses an inviscid panel method and an integral boundary layer method to estimate the air mass flow rate through the intake geometry. Intake mass flow rate is used as a performance metric since it directly affects the amount of thrust a rocket-ejector can produce. The design method results for the air intake operating at several different points along the subsonic portion of the Ariane 4 flight profile are found to under predict mass flow rate by up to 8.6% when compared to three-dimensional computational fluid dynamics simulations for the same air intake.

Using recorded sound spectra profile as input data for real-time short-term urban road-traffic-flow estimation.

PubMed

Torija, Antonio J; Ruiz, Diego P

2012-10-01

Road traffic has a heavy impact on the urban sound environment, constituting the main source of noise and widely dominating its spectral composition. In this context, our research investigates the use of recorded sound spectra as input data for the development of real-time short-term road traffic flow estimation models. For this, a series of models based on the use of Multilayer Perceptron Neural Networks, multiple linear regression, and the Fisher linear discriminant were implemented to estimate road traffic flow as well as to classify it according to the composition of heavy vehicles and motorcycles/mopeds. In view of the results, the use of the 50-400 Hz and 1-2.5 kHz frequency ranges as input variables in multilayer perceptron-based models successfully estimated urban road traffic flow with an average percentage of explained variance equal to 86%, while the classification of the urban road traffic flow gave an average success rate of 96.1%. Copyright © 2012 Elsevier B.V. All rights reserved.

Characterization of bedload transport in steep-slope streams

NASA Astrophysics Data System (ADS)

Mettra, F.; Heyman, J.; Ancey, C.

2012-04-01

Large fluctuations in the sediment transport rate are observed in rivers, particularly in mountain streams at intermediate flow rates. These fluctuations seem to be, to some degree, correlated to the formation and migration of bedforms. Today the central question is still how to understand and account for the strong bedload variability. Recent experimental studies shed new light on the processes. The objective of this presentation is to show some of our results. To understand the behavior and the origins of sediment transport rate fluctuations in the case of steep-slope streams, we conducted laboratory experiments in a 3-m long, 8-cm wide, transparent flume. The experimental parameters are the flume inclination, flow rate and sediment input rate. Well-sorted natural gravel (8.5 mm mean diameter) were used. We focused on two-dimensional flows and incipient bedforms (i.e., for flow rates just above the threshold of incipient motion). A technique based on accelerometers was developed to record every particle passing through the flume outlet (more specifically, we measured the vibrations of a metallic slab, which was impacted by the falling particles). Analysis of bedload transport rates was then possible on all time scales. Moreover, the bed and flow were monitored using 2 cameras. We computed bed elevation, water depth and erosion/deposition at high temporal and spatial rates from camera shots (one image per second during several hours or days). In our laboratory experiments, the fluctuations of the sediment rate were large even for steady flow conditions involving well-sorted particles. Time series exhibited fluctuations at all scales and displayed long range correlations with a Hurst exponent close to 0.8. The results were compared for different input solid discharges. The main bedforms observed in our flume were anti-dunes migrating upstream. Bedform formation and propagation showed intermittency with pulses (high activity) followed by long sequences of low activity. We tried to interpret our results (bedform behavior, bed scouring) in terms of sediment outflow rate.

Microfluidic oscillators with widely tunable periods

PubMed Central

Kim, Sung-Jin; Yokokawa, Ryuji; Takayama, Shuichi

2013-01-01

We present experiments and theory of a constant flow-driven microfluidic oscillator with widely tunable oscillation periods. This oscillator converts two constant input-flows from a syringe pump into an alternating, periodic output-flow with oscillation periods that can be adjusted to between 0.3 s to 4.1 h by tuning an external membrane capacitor. This capacitor allows multiple adjustable periods at a given input flow-rate, thus providing great flexibility in device operation. Also, we show that a sufficiently large external capacitance, relative to the internal capacitance of the microfluidic valve itself, is a critical requirement for oscillation. These widely tunable microfluidic oscillators are envisioned to be broadly useful for the study of biological rhythms, as on-chip timing sources for microfluidic logic circuits, and other applications that require variation in timed flow switching. PMID:23429765

The combined use of MODFLOW and precipitation-runoff modeling to simulate groundwater flow in a diffuse-pollution prone watershed.

PubMed

Elçi, A; Karadaş, D; Fistikoğlu, O

2010-01-01

A numerical modeling case study of groundwater flow in a diffuse pollution prone area is presented. The study area is located within the metropolitan borders of the city of Izmir, Turkey. This groundwater flow model was unconventional in the application since the groundwater recharge parameter in the model was estimated using a lumped, transient water-budget based precipitation-runoff model that was executed independent of the groundwater flow model. The recharge rate obtained from the calibrated precipitation-runoff model was used as input to the groundwater flow model, which was eventually calibrated to measured water table elevations. Overall, the flow model results were consistent with field observations and model statistics were satisfactory. Water budget results of the model revealed that groundwater recharge comprised about 20% of the total water input for the entire study area. Recharge was the second largest component in the budget after leakage from streams into the subsurface. It was concluded that the modeling results can be further used as input for contaminant transport modeling studies in order to evaluate the vulnerability of water resources of the study area to diffuse pollution.

Minimum data requirement for neural networks based on power spectral density analysis.

PubMed

Deng, Jiamei; Maass, Bastian; Stobart, Richard

2012-04-01

One of the most critical challenges ahead for diesel engines is to identify new techniques for fuel economy improvement without compromising emissions regulations. One technique is the precise control of air/fuel ratio, which requires the measurement of instantaneous fuel consumption. Measurement accuracy and repeatability for fuel rate is the key to successfully controlling the air/fuel ratio and real-time measurement of fuel consumption. The volumetric and gravimetric measurement principles are well-known methods for measurement of fuel consumption in internal combustion engines. However, the fuel flow rate measured by these methods is not suitable for either real-time control or real-time measurement purposes because of the intermittent nature of the measurements. This paper describes a technique that can be used to find the minimum data [consisting of data from just 2.5% of the non-road transient cycle (NRTC)] to solve the problem concerning discontinuous data of fuel flow rate measured using an AVL 733S fuel meter for a medium or heavy-duty diesel engine using neural networks. Only torque and speed are used as the input parameters for the fuel flow rate prediction. Power density analysis is used to find the minimum amount of the data. The results show that the nonlinear autoregressive model with exogenous inputs could predict the particulate matter successfully with R(2) above 0.96 using 2.5% NRTC data with only torque and speed as inputs.

Laboratory-based observations of capillary barriers and preferential flow in layered snow

NASA Astrophysics Data System (ADS)

Avanzi, F.; Hirashima, H.; Yamaguchi, S.; Katsushima, T.; De Michele, C.

2015-12-01

Several evidences are nowadays available that show how the effects of capillary gradients and preferential flow on water transmission in snow may play a more important role than expected. To observe these processes and to contribute in their characterization, we performed observations on the development of capillary barriers and preferential flow patterns in layered snow during cold laboratory experiments. We considered three different layering (all characterized by a finer-over-coarser texture in grain size) and three different water input rates. Nine samples of layered snow were sieved in a cold laboratory, and subjected to a constant supply of dyed tracer. By means of visual inspection, horizontal sectioning and liquid water content measurements, the processes of ponding and preferential flow were characterized as a function of texture and water input rate. The dynamics of each sample were replicated using the multi-layer physically-based SNOWPACK model. Results show that capillary barriers and preferential flow are relevant processes ruling the speed of liquid water in stratified snow. Ponding is associated with peaks in LWC at the boundary between the two layers equal to ~ 33-36 vol. % when the upper layer is composed by fine snow (grain size smaller than 0.5 mm). The thickness of the ponding layer at the textural boundary is between 0 and 3 cm, depending on sample stratigraphy. Heterogeneity in water transmission increases with grain size, while we do not observe any clear dependency on water input rate. The extensive comparison between observed and simulated LWC profiles by SNOWPACK (using an approximation of Richards Equation) shows high performances by the model in estimating the LWC peak over the boundary, while water speed in snow is underestimated by the chosen water transport scheme.

Effect of turbulent flow on an atmospheric-pressure AC powered gliding arc discharge

NASA Astrophysics Data System (ADS)

Kong, Chengdong; Gao, Jinlong; Zhu, Jiajian; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan

2018-06-01

A high-power gliding arc (GA) discharge was generated in a turbulent air flow driven by a 35 kHz alternating current electric power supply. The effects of the flow rate on the characteristics of the GA discharge were investigated using combined optical and electrical diagnostics. Phenomenologically, the GA discharge exhibits two types of discharge, i.e., glow type and spark type, depending on the flow rates and input powers. The glow-type discharge, which has peak currents of hundreds of milliamperes, is sustained at low flow rates. The spark-type discharge, which is characterized by a sharp current spike of several amperes with duration of less than 1 μs, occurs more frequently as the flow rate increases. Higher input power can suppress spark-type discharges in moderate turbulence, but this effect becomes weak under high turbulent conditions. Physically, the transition between glow- and spark-type is initiated by the short cutting events and the local re-ignition events. Short cutting events occur owing to the twisting, wrinkling, and stretching of the plasma columns that are governed by the relatively large vortexes in the flow. Local re-ignition events, which are defined as re-ignition along plasma columns, are detected in strong turbulence due to increment of the impedance of the plasma column and consequently the internal electric field strength. It is suggested that the vortexes with length scales smaller than the size of the plasma can penetrate into the plasma column and promote mixing with surroundings to accelerate the energy dissipation. Therefore, the turbulent flow influences the GA discharges by ruling the short cutting events with relatively large vortexes and the local re-ignition events with small vortexes.

Dynamical systems characterization of inertial effects of fluid flow in a curved artery model under pulsatile flow forcing

NASA Astrophysics Data System (ADS)

Leggiero, Michael; Bulusu, Kartik V.; Plesniak, Michael W.

2013-11-01

The main objective of this study was to examine inertial effects in a 180-degree model of curved arteries under pulsatile inflow conditions. Two-component, two-dimensional particle image velocimetery (2C-2D PIV) data were acquired upstream of and at several cross-sectional locations in the curved artery model. A blood-analog fluid comprised of 71% saturated sodium iodide solution, 28% glycerol and 1% distilled water (by volume) was subjected to multi-harmonic pulsatile inflow functions. First, signal time-lag was quantified by cross-correlating the input (voltage-time) supplied to a programmable pump and the output PIV (flow rate-time) measurements. The experiment was then treated as a linear, time-invariant system, and frequency response was estimated for phase shifts across a certain spectrum. Input-output signal dissimilarities were attributable to intrinsic inertial effects of flow. By coupling pressure-time and upstream flow rate-time measurements, the experiment was modeled using system identification methods. Results elucidate the role of inertial effects in fluid flow velocity measurements and the effect of these delays on secondary flow structure detection in a curved artery model. Supported by the NSF Grant No. CBET- 0828903 and GW Center for Biomimetics and Bioinspired Engineering.

Radiation beam calorimetric power measurement system

DOEpatents

Baker, John; Collins, Leland F.; Kuklo, Thomas C.; Micali, James V.

1992-01-01

A radiation beam calorimetric power measurement system for measuring the average power of a beam such as a laser beam, including a calorimeter configured to operate over a wide range of coolant flow rates and being cooled by continuously flowing coolant for absorbing light from a laser beam to convert the laser beam energy into heat. The system further includes a flow meter for measuring the coolant flow in the calorimeter and a pair of thermistors for measuring the temperature difference between the coolant inputs and outputs to the calorimeter. The system also includes a microprocessor for processing the measured coolant flow rate and the measured temperature difference to determine the average power of the laser beam.

Discharge Characterization of 40 cm-Microwave ECR Ion Source and Neutralizer

NASA Technical Reports Server (NTRS)

Foster, John E.; Patterson, Michael J.; Britton, Melissa

2003-01-01

Discharge characteristics of a 40 cm, 2.45 GHz Electron Cyclotron Resonance (ECR) ion thruster discharge chamber and neutralizer were acquired. Thruster bulk discharge plasma characteristics were assessed using a single Langmuir probe. Total extractable ion current was measured as a function of input microwave power and flow rate. Additionally, radial ion current density profiles at the thruster.s exit plane were characterized using five equally spaced Faraday probes. Distinct low and high density operating modes were observed as discharge input power was varied from 0 to 200 W. In the high mode, extractable ion currents as high as 0.82 A were measured. Neutralizer emission current was characterized as a function of flow rate and microwave power. Neutralizer extraction currents as high as 0.6 A were measured.

What Controls Sediment Retention in an Emerging Delta?

NASA Astrophysics Data System (ADS)

Keogh, M.; Kolker, A.

2016-12-01

What controls sediment retention in an emerging delta? Here, we examine the effects of river discharge and flow velocity on sediment retention rate, using a developing crevasse splay in the Lower Mississippi Delta as a study location. With a controlled discharge that ranges from 28 to 280 m3/s, Davis Pond Freshwater Diversion connects the Mississippi River to the adjacent wetland, allowing river water, sediment, and nutrients to flow into the marsh. Although Davis Pond was primarily designed to regulate salinity within Barataria Basin rather than to build land, a new crevasse splay has recently emerged at the mouth of the diversion's outfall channel. Short (5 cm) sediment cores were collected at 22 locations around the Davis Pond receiving basin in spring 2015, fall 2015, and spring 2016. All cores were analyzed for sediment geotechnical parameters including organic content, bulk density, and grain size. Sediment input into the receiving basin was calculated using a ratings curve. Activity of the radioisotope beryllium-7 was used to calculate rates of sediment accumulation and retention. We find that while sediment input is greater during high flow, rate of retention is greater during low flow. This is likely due to the increase in flow velocity that accompanies high discharge, which retains sediment in suspension and leads to more throughput of material. Furthermore, the diversion operation regime of sustained low flow punctuated by short-duration high discharge events has increased soil bulk density, mineral sediment accumulation, and marsh platform elevation. River diversions such as Davis Pond mimic the land-building processes of natural crevasse splays and provide a promising method to restore deltaic wetlands worldwide.

Statistical validation and an empirical model of hydrogen production enhancement found by utilizing passive flow disturbance in the steam-reformation process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson, Paul A.; Liao, Chang-hsien

2007-11-15

A passive flow disturbance has been proven to enhance the conversion of fuel in a methanol-steam reformer. This study presents a statistical validation of the experiment based on a standard 2{sup k} factorial experiment design and the resulting empirical model of the enhanced hydrogen producing process. A factorial experiment design was used to statistically analyze the effects and interactions of various input factors in the experiment. Three input factors, including the number of flow disturbers, catalyst size, and reactant flow rate were investigated for their effects on the fuel conversion in the steam-reformation process. Based on the experimental results, anmore » empirical model was developed and further evaluated with an uncertainty analysis and interior point data. (author)« less

Apparatus and method for combusting low quality fuel

DOEpatents

Brushwood, John Samuel; Pillsbury, Paul; Foote, John; Heilos, Andreas

2003-11-04

A gas turbine (12) capable of combusting a low quality gaseous fuel having a ratio of flammability limits less than 2, or a heat value below 100 BTU/SCF. A high quality fuel is burned simultaneously with the low quality fuel to eliminate instability in the combustion flame. A sensor (46) is used to monitor at least one parameter of the flame indicative of instability. A controller (50) having the sensor signal (48) as input is programmed to control the relative flow rates of the low quality and high quality fuels. When instability is detected, the flow rate of high quality fuel is automatically increased in relation to the flow rate of low quality fuel to restore stability.

Advanced two-stage compressor program design of inlet stage

NASA Technical Reports Server (NTRS)

Bryce, C. A.; Paine, C. J.; Mccutcheon, A. R. S.; Tu, R. K.; Perrone, G. L.

1973-01-01

The aerodynamic design of an inlet stage for a two-stage, 10/1 pressure ratio, 2 lb/sec flow rate compressor is discussed. Initially a performance comparison was conducted for an axial, mixed flow and centrifugal second stage. A modified mixed flow configuration with tandem rotors and tandem stators was selected for the inlet stage. The term conical flow compressor was coined to describe a particular type of mixed flow compressor configuration which utilizes axial flow type blading and an increase in radius to increase the work input potential. Design details of the conical flow compressor are described.

Fire effects on water quality: a synthesis of response regulating factors among contrasting ecosystems

Treesearch

Katherine J. Elliott; James M. Vose

2006-01-01

The key components of watershed processes are inputs in precipitation, interactions of vegetation, soil and water including evapotranspiration (water yield), overland flow (erosion), and storage and filtering (nutrients), and outputs in streamflow. Fire effects occur at the vegetation-soil interface and can result in altering overland flow and infiltration rate of...

Three dimensional flow computations in a turbine scroll

NASA Technical Reports Server (NTRS)

Hamed, A.; Ghantous, C. A.

1982-01-01

The compressible three dimensional inviscid flow in the scroll and vaneless nozzle of radial inflow turbines is analyzed. A FORTRAN computer program for the numerical solution of this complex flow field using the finite element method is presented. The program input consists of the mass flow rate and stagnation conditions at the scroll inlet and of the finite element discretization parameters and nodal coordinates. The output includes the pressure, Mach number and velocity magnitude and direction at all the nodal points.

Real-time flood forecasts & risk assessment using a possibility-theory based fuzzy neural network

NASA Astrophysics Data System (ADS)

Khan, U. T.

2016-12-01

Globally floods are one of the most devastating natural disasters and improved flood forecasting methods are essential for better flood protection in urban areas. Given the availability of high resolution real-time datasets for flood variables (e.g. streamflow and precipitation) in many urban areas, data-driven models have been effectively used to predict peak flow rates in river; however, the selection of input parameters for these types of models is often subjective. Additionally, the inherit uncertainty associated with data models along with errors in extreme event observations means that uncertainty quantification is essential. Addressing these concerns will enable improved flood forecasting methods and provide more accurate flood risk assessments. In this research, a new type of data-driven model, a quasi-real-time updating fuzzy neural network is developed to predict peak flow rates in urban riverine watersheds. A possibility-to-probability transformation is first used to convert observed data into fuzzy numbers. A possibility theory based training regime is them used to construct the fuzzy parameters and the outputs. A new entropy-based optimisation criterion is used to train the network. Two existing methods to select the optimum input parameters are modified to account for fuzzy number inputs, and compared. These methods are: Entropy-Wavelet-based Artificial Neural Network (EWANN) and Combined Neural Pathway Strength Analysis (CNPSA). Finally, an automated algorithm design to select the optimum structure of the neural network is implemented. The overall impact of each component of training this network is to replace the traditional ad hoc network configuration methods, with one based on objective criteria. Ten years of data from the Bow River in Calgary, Canada (including two major floods in 2005 and 2013) are used to calibrate and test the network. The EWANN method selected lagged peak flow as a candidate input, whereas the CNPSA method selected lagged precipitation and lagged mean daily flow as candidate inputs. Model performance metric show that the CNPSA method had higher performance (with an efficiency of 0.76). Model output was used to assess the risk of extreme peak flows for a given day using an inverse possibility-to-probability transformation.

Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System.

PubMed

Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui

2016-01-20

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input-output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy.

Energy Productivity of the High Velocity Algae Raceway Integrated Design (ARID-HV)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attalah, Said; Waller, Peter M.; Khawam, George

The original Algae Raceway Integrated Design (ARID) raceway was an effective method to increase algae culture temperature in open raceways. However, the energy input was high and flow mixing was poor. Thus, the High Velocity Algae Raceway Integrated Design (ARID-HV) raceway was developed to reduce energy input requirements and improve flow mixing in a serpentine flow path. A prototype ARID-HV system was installed in Tucson, Arizona. Based on algae growth simulation and hydraulic analysis, an optimal ARID-HV raceway was designed, and the electrical energy input requirement (kWh ha-1 d-1) was calculated. An algae growth model was used to compare themore » productivity of ARIDHV and conventional raceways. The model uses a pond surface energy balance to calculate water temperature as a function of environmental parameters. Algae growth and biomass loss are calculated based on rate constants during day and night, respectively. A 10 year simulation of DOE strain 1412 (Chlorella sorokiniana) showed that the ARID-HV raceway had significantly higher production than a conventional raceway for all months of the year in Tucson, Arizona. It should be noted that this difference is species and climate specific and is not observed in other climates and with other algae species. The algae growth model results and electrical energy input evaluation were used to compare the energy productivity (algae production rate/energy input) of the ARID-HV and conventional raceways for Chlorella sorokiniana in Tucson, Arizona. The energy productivity of the ARID-HV raceway was significantly greater than the energy productivity of a conventional raceway for all months of the year.« less

The Formation of Ethane from Carbon Dioxide under Cold Plasma

NASA Astrophysics Data System (ADS)

Zhang, Xiu-ling; Zhang, Lin; Dai, Bin; Gong, Wei-min; Liu, Chang-hou

2001-04-01

Pulsed-corona plasma has been used as a new method for ethane dehydrogenation at low temperature and normal pressure using carbon dioxide as an oxidant in this paper. The effect of carbon dioxide content in the feed, power input, and flow rate of the reactants on the ethane dehydrogenation has been investigated. The experimental results show that the conversion of ethane increases with the increase in the amount of carbon dioxide in the feed. The yield of ethylene and acetylene decreases with the increase in the yield of carbon monoxide, indicating that the increased carbon dioxide leads to the part of ethylene and acetylene being oxidized to carbon monoxide. Power input is primarily an electrical parameter in pulsed-corona plasma, which plays an important role in reactant conversion and product formation. When the power input reaches 16 W, ethane conversion is 41.0% and carbon dioxide conversion is 26.3%. The total yield of ethylene and acetylene is 15.6%. The reduced flow rate of feed improves the conversion of ethane, carbon dioxide and the yield of acetylene, and induces carbon deposit as well.

Development of a miniature microwave electron cyclotron resonance plasma ion thruster for exospheric micro-propulsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dey, Indranuj, E-mail: indranuj@aees.kyushu-u.ac.jp; Toyoda, Yuji; Yamamoto, Naoji

A miniature microwave electron cyclotron resonance plasma source [(discharge diameter)/(microwave cutoff diameter) < 0.3] has been developed at Kyushu University to be used as an ion thruster in micro-propulsion applications in the exosphere. The discharge source uses both radial and axial magnetostatic field confinement to facilitate electron cyclotron resonance and increase the electron dwell time in the volume, thereby enhancing plasma production efficiency. Performance of the ion thruster is studied at 3 microwave frequencies (1.2 GHz, 1.6 GHz, and 2.45 GHz), for low input powers (<15 W) and small xenon mass flow rates (<40 μg/s), by experimentally measuring the extractedmore » ion beam current through a potential difference of ≅1200 V. The discharge geometry is found to operate most efficiently at an input microwave frequency of 1.6 GHz. At this frequency, for an input power of 8 W, and propellant (xenon) mass flow rate of 21 μg/s, 13.7 mA of ion beam current is obtained, equivalent to an calculated thrust of 0.74 mN.« less

Concept of modernization of input device of oil and gas separator

NASA Astrophysics Data System (ADS)

Feodorov, A. B.; Afanasov, V. I.; Miroshnikov, R. S.; Bogachev, V. V.

2017-10-01

The process of defoaming in oil production is discussed. This technology is important in oil and gas fields. Today, the technology of separating the gas fraction is based on chemical catalysis. The use of mechanical technologies improves the economics of the process. Modernization of the separator input device is based on the use of long thin tubes. The chosen length of the tubes is two orders of magnitude larger than the diameter. The separation problem is solved by creating a high centrifugal acceleration. The tubes of the input device are connected in parallel and divide the input stream into several arms. The separated fluid flows are directed tangentially into the working tubes to create a vortex motion. The number of tubes connected in parallel is calculated in accordance with the flow rate of the fluid. The connection of the working tubes to the supply line is made in the form of a flange. This connection allows carrying out maintenance without stopping the flow of fluid. An important feature of this device is its high potential for further modernization. It is concerned with the determination of the parameters of the tubes and the connection geometry in the construction of a single product.

Computer code for preliminary sizing analysis of axial-flow turbines

NASA Technical Reports Server (NTRS)

Glassman, Arthur J.

1992-01-01

This mean diameter flow analysis uses a stage average velocity diagram as the basis for the computational efficiency. Input design requirements include power or pressure ratio, flow rate, temperature, pressure, and rotative speed. Turbine designs are generated for any specified number of stages and for any of three types of velocity diagrams (symmetrical, zero exit swirl, or impulse) or for any specified stage swirl split. Exit turning vanes can be included in the design. The program output includes inlet and exit annulus dimensions, exit temperature and pressure, total and static efficiencies, flow angles, and last stage absolute and relative Mach numbers. An analysis is presented along with a description of the computer program input and output with sample cases. The analysis and code presented herein are modifications of those described in NASA-TN-D-6702. These modifications improve modeling rigor and extend code applicability.

Desagregation des debits mensuels en debits journaliers

NASA Astrophysics Data System (ADS)

Ypou, Tanou Ya Kouassi

A good estimate of the historical natural flow of water in a water system, allows an appropriate management of reservoirs of hydroelectric plants. This management is a guarantee for efficient planning of hydropower production. The reconstruction of the real natural inputs with quality features for the periods before and after the impoundment of reservoirs is sought by HQ. The implementation of a good quality daily historical data from monthly data remains a major concern both for HQ and for the scientific community. Beyond the benefits of mastering simulations of the basin's hydrological behavior in water systems, this study allows the establishment of appropriate measures to protect the population and the various properties located in riparian areas of water systems. The main objective of the study is the breakdown of monthly flows in daily flows. This study is in the business context of HQ. To reconstruct the historical supply of water systems, HSAMI and HYDROTEL models are used. Different methods have been used by HQ to constitute the daily historical rates. So far, a good quality of the reconstituted daily data analysis illustrates the serious discrepancies and errors in those series. Several previous studies in the literature have attempted to reconstruct the daily flow rates from historical monthly series, but as explained in the report, these different approaches have results that do not represent the reality of HQ's water systems. Clearly the methods are not effective in the operational framework of Hydro-Quebec. This report presents an optimized use based on the approach HSAMI and HYDROTEL models in order to transform the flow of rain for the reconstruction of natural flow series. This approach is applied to Outardes's and Saint-Maurice's water systems with the weather and physical field data available. Input the hydrological data are validated by a process of analyzing data quality, specific flow and evaporation parameters. Input the metrological data has been analysis by Statistics, climate and water for weather series criteria. An automatic calibration of the two models is made with the Matlab software. The results of the calibration of Outardes's and Saint-Maurice's water systems are presented in this report. The modeling of ground conditions is made for input data needs of different models using the features included in the models are generally presented in this report and in particularly the model for HYDROTEL and PHYSITEL. The historical simulation flows is performed using meteorological data and physical field data on the periods of 1965 to 2014. Based on the quality of input data available and the goal of generating daily historical supply series using monthly series of natural inputs, the quality criteria have been defined to qualify the model to choose. Indeed, the quality criteria for comparing the two models are the criterion of NSE and KGE. Analysis of the results led to the conclusion that the HYDROTEL model is most appropriate in the operational framework of HQ to disaggregate monthly historical series of daily flows in series. The HYDROTEL model enabled to disaggregate monthly debits daily flows. The daily discharges simulated ponds Beaumont, Vermillion, La tuque are presented and analyzed in this report. Keywords: disaggregation, natural flow, HYDROTEL, HSAMI, data reconstruction .

Theory for source-responsive and free-surface film modeling of unsaturated flow

USGS Publications Warehouse

Nimmo, J.R.

2010-01-01

A new model explicitly incorporates the possibility of rapid response, across significant distance, to substantial water input. It is useful for unsaturated flow processes that are not inherently diffusive, or that do not progress through a series of equilibrium states. The term source-responsive is used to mean that flow responds sensitively to changing conditions at the source of water input (e.g., rainfall, irrigation, or ponded infiltration). The domain of preferential flow can be conceptualized as laminar flow in free-surface films along the walls of pores. These films may be considered to have uniform thickness, as suggested by field evidence that preferential flow moves at an approximately uniform rate when generated by a continuous and ample water supply. An effective facial area per unit volume quantitatively characterizes the medium with respect to source-responsive flow. A flow-intensity factor dependent on conditions within the medium represents the amount of source-responsive flow at a given time and position. Laminar flow theory provides relations for the velocity and thickness of flowing source-responsive films. Combination with the Darcy-Buckingham law and the continuity equation leads to expressions for both fluxes and dynamic water contents. Where preferential flow is sometimes or always significant, the interactive combination of source-responsive and diffuse flow has the potential to improve prediction of unsaturated-zone fluxes in response to hydraulic inputs and the evolving distribution of soil moisture. Examples for which this approach is efficient and physically plausible include (i) rainstorm-generated rapid fluctuations of a deep water table and (ii) space- and time-dependent soil water content response to infiltration in a macroporous soil. ?? Soil Science Society of America.

Impact of material heterogeneity on solute transport behavior in the unsaturated zone of the Calcaire de Beauce aquifer (France)

NASA Astrophysics Data System (ADS)

Viel, Emelie; Coquet, Yves

2016-04-01

Since a few decades, the Calcaire de Beauce aquifer is contaminated with nitrate. The nitrate dynamics in the aquifer and in the surface soil are quite well understood, but its transport through the vadose zone remains largely unknown. When models fail to simulate nitrate concentrations in wells, preferential flow or physical non-equilibrium transport in soil and in the vadose zone is usually put forward to explain this failure. To study transport processes in the vadose zone of the Calcaire de Beauce aquifer, undisturbed cores (30 cm length and 20 cm diameter) have been taken below the deepest soil horizon. At the field scale, the vadose zone is composed of powdery limestone spatially very heterogeneous, and including a variable amount of coarse elements. Two columns were selected: column "6" is made of very fine homogeneous limestone whereas column "8" is very heterogeneous with a large proportion of coarse elements. Elution experiments have been performed on both columns. A tracer (Br- or DFBA) in a solution of 5 mM CaCl2 was spread as a pulse on the top of the column with a rainfall simulator. Input flow rate was kept constant for steady state cases, or suddenly closed for flux interruption cases. Outflow was collected as a function of time for tracer concentration measurement. The collected fractions were analyzed by HPLC (High-performance liquid chromatography) with a UV detector. Three types of experiments took place: • For steady state experiments, three rainfall rates, respectively 4, 8, and 16 mm/h, have been used to study the occurrence of immobile water in the columns. The tracer was injected during 120 min followed by CaCl2 tracer-free solution at same flow rate. • For flux-interruption experiments, only the 4 and 8 mm/h rainfall rates were used. The tracer was injected during 120 min, input and output fluxes were then stopped and restarted seven days later with the same flow rate. • For drainage experiments, only the 4 and 8 mm/h rainfall rates were used as well. The tracer was injected during 120 min, input flux was stopped while output flux continued to occur under the -25 cm matric head bottom boundary condition. Flux restarted seven days later with the same flow rate or another flow rate. STANMOD was used for each BTC to estimate transport parameters assuming steady state flux. The standard CDE was suitable for column 6 steady-state experiments, but the MIM had to be used to describe properly the BTCs of column 8. In this column, the immobile water fraction represented 38 %. Flux interruption experiments showed that the form of the BTC for Column 6 was not disturbed for the 4 and 8 mm/h input flux, whereas the form of BTC for Column 8 had significantly changed with a visible steeper increase after an interruption time compared to the corresponding steady state experiment. This difference of behavior could be related to the difference in limestone material. The immobile water fraction was found to be significant only for columns made of heterogeneous limestone.

The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

NASA Astrophysics Data System (ADS)

Wang, H. L.; Han, W.; Xu, M.

2011-12-01

Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

Analogue experiments as benchmarks for models of lava flow emplacement

NASA Astrophysics Data System (ADS)

Garel, F.; Kaminski, E. C.; Tait, S.; Limare, A.

2013-12-01

During an effusive volcanic eruption, the crisis management is mainly based on the prediction of lava flow advance and its velocity. The spreading of a lava flow, seen as a gravity current, depends on its "effective rheology" and on the effusion rate. Fast-computing models have arisen in the past decade in order to predict in near real time lava flow path and rate of advance. This type of model, crucial to mitigate volcanic hazards and organize potential evacuation, has been mainly compared a posteriori to real cases of emplaced lava flows. The input parameters of such simulations applied to natural eruptions, especially effusion rate and topography, are often not known precisely, and are difficult to evaluate after the eruption. It is therefore not straightforward to identify the causes of discrepancies between model outputs and observed lava emplacement, whereas the comparison of models with controlled laboratory experiments appears easier. The challenge for numerical simulations of lava flow emplacement is to model the simultaneous advance and thermal structure of viscous lava flows. To provide original constraints later to be used in benchmark numerical simulations, we have performed lab-scale experiments investigating the cooling of isoviscous gravity currents. The simplest experimental set-up is as follows: silicone oil, whose viscosity, around 5 Pa.s, varies less than a factor of 2 in the temperature range studied, is injected from a point source onto a horizontal plate and spreads axisymmetrically. The oil is injected hot, and progressively cools down to ambient temperature away from the source. Once the flow is developed, it presents a stationary radial thermal structure whose characteristics depend on the input flow rate. In addition to the experimental observations, we have developed in Garel et al., JGR, 2012 a theoretical model confirming the relationship between supply rate, flow advance and stationary surface thermal structure. We also provide experimental observations of the effect of wind the surface thermal structure of a viscous flow, that could be used to benchmark a thermal heat loss model. We will also briefly present more complex analogue experiments using wax material. These experiments present discontinuous advance behavior, and a dual surface thermal structure with low (solidified) vs. high (hot liquid exposed at the surface) surface temperatures regions. Emplacement models should tend to reproduce these two features, also observed on lava flows, to better predict the hazard of lava inundation.

GUI for Computational Simulation of a Propellant Mixer

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Richter, Hanz; Barbieri, Enrique; Granger, Jamie

2005-01-01

Control Panel is a computer program that generates a graphical user interface (GUI) for computational simulation of a rocket-test-stand propellant mixer in which gaseous hydrogen (GH2) is injected into flowing liquid hydrogen (LH2) to obtain a combined flow having desired thermodynamic properties. The GUI is used in conjunction with software that models the mixer as a system having three inputs (the positions of the GH2 and LH2 inlet valves and an outlet valve) and three outputs (the pressure inside the mixer and the outlet flow temperature and flow rate). The user can specify valve characteristics and thermodynamic properties of the input fluids via userfriendly dialog boxes. The user can enter temporally varying input values or temporally varying desired output values. The GUI provides (1) a set-point calculator function for determining fixed valve positions that yield desired output values and (2) simulation functions that predict the response of the mixer to variations in the properties of the LH2 and GH2 and manual- or feedback-control variations in valve positions. The GUI enables scheduling of a sequence of operations that includes switching from manual to feedback control when a certain event occurs.

A modification of the finite-difference model for simulation of two dimensional ground-water flow to include surface-ground water relationships

USGS Publications Warehouse

Ozbilgin, M.M.; Dickerman, D.C.

1984-01-01

The two-dimensional finite-difference model for simulation of groundwater flow was modified to enable simulation of surface-water/groundwater interactions during periods of low streamflow. Changes were made to the program code in order to calculate surface-water heads for, and flow either to or from, contiguous surface-water bodies; and to allow for more convenient data input. Methods of data input and output were modified and entries (RSORT and HDRIVER) were added to the COEF and CHECKI subroutines to calculate surface-water heads. A new subroutine CALC was added to the program which initiates surface-water calculations. If CALC is not specified as a simulation option, the program runs the original version. The subroutines which solve the ground-water flow equations were not changed. Recharge, evapotranspiration, surface-water inflow, number of wells, pumping rate, and pumping duration can be varied for any time period. The Manning formula was used to relate stream depth and discharge in surface-water streams. Interactions between surface water and ground water are represented by the leakage term in the ground-water flow and surface-water mass balance equations. Documentation includes a flow chart, data deck instructions, input data, output summary, and program listing. Numerical results from the modified program are in good agreement with published analytical results. (USGS)

The wire-mesh sensor as a two-phase flow meter

NASA Astrophysics Data System (ADS)

Shaban, H.; Tavoularis, S.

2015-01-01

A novel gas and liquid flow rate measurement method is proposed for use in vertical upward and downward gas-liquid pipe flows. This method is based on the analysis of the time history of area-averaged void fraction that is measured using a conductivity wire-mesh sensor (WMS). WMS measurements were collected in vertical upward and downward air-water flows in a pipe with an internal diameter of 32.5 mm at nearly atmospheric pressure. The relative frequencies and the power spectral density of area-averaged void fraction were calculated and used as representative properties. Independent features, extracted from these properties using Principal Component Analysis and Independent Component Analysis, were used as inputs to artificial neural networks, which were trained to give the gas and liquid flow rates as outputs. The present method was shown to be accurate for all four encountered flow regimes and for a wide range of flow conditions. Besides providing accurate predictions for steady flows, the method was also tested successfully in three flows with transient liquid flow rates. The method was augmented by the use of the cross-correlation function of area-averaged void fraction determined from the output of a dual WMS unit as an additional representative property, which was found to improve the accuracy of flow rate prediction.

Modeling of Ice Flow and Internal Layers Along a Flow Line Through Swiss Camp in West Greenland

NASA Technical Reports Server (NTRS)

Wang, W. L.; Zwally, H. Jay; Abdalati, W.; Luo, S.; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

An anisotropic ice flow line model is applied to a flow line through Swiss Camp (69.57 N, 49.28 W) in West Greenland to estimate the dates of internal layers detected by Radio-Echo Sounding measurements. The effect of an anisotropic ice fabric on ice flow is incorporated into the steady state flow line model. The stress-strain rate relationship for anisotropic ice is characterized by an enhancement factor based on the laboratory observations of ice deformation under combined compression and shear stresses. By using present-day data of accumulation rate, surface temperature, surface elevation and ice thickness along the flow line as model inputs, a very close agreement is found between the isochrones generated from the model and the observed internal layers with confirmed dates. The results indicate that this part of Greenland ice sheet is primarily in steady state.

Fast gradient separation by very high pressure liquid chromatography: reproducibility of analytical data and influence of delay between successive runs.

PubMed

Stankovicha, Joseph J; Gritti, Fabrice; Beaver, Lois Ann; Stevensona, Paul G; Guiochon, Georges

2013-11-29

Five methods were used to implement fast gradient separations: constant flow rate, constant column-wall temperature, constant inlet pressure at moderate and high pressures (controlled by a pressure controller),and programmed flow constant pressure. For programmed flow constant pressure, the flow rates and gradient compositions are controlled using input into the method instead of the pressure controller. Minor fluctuations in the inlet pressure do not affect the mobile phase flow rate in programmed flow. There producibilities of the retention times, the response factors, and the eluted band width of six successive separations of the same sample (9 components) were measured with different equilibration times between 0 and 15 min. The influence of the length of the equilibration time on these reproducibilities is discussed. The results show that the average column temperature may increase from one separation to the next and that this contributes to fluctuation of the results.

Method and apparatus for simultaneous determination of fluid mass flow rate, mean velocity and density

DOEpatents

Hamel, William R.

1984-01-01

This invention relates to a new method and new apparatus for determining fluid mass flowrate and density. In one aspect of the invention, the fluid is passed through a straight cantilevered tube in which transient oscillation has been induced, thus generating Coriolis damping forces on the tube. The decay rate and frequency of the resulting damped oscillation are measured, and the fluid mass flowrate and density are determined therefrom. In another aspect of the invention, the fluid is passed through the cantilevered tube while an electrically powered device imparts steady-state harmonic excitation to the tube. This generates Coriolis tube-damping forces which are dependent on the mass flowrate of the fluid. Means are provided to respond to incipient flow-induced changes in the amplitude of vibration by changing the power input to the excitation device as required to sustain the original amplitude of vibration. The fluid mass flowrate and density are determined from the required change in power input. The invention provides stable, rapid, and accurate measurements. It does not require bending of the fluid flow.

Effect of isolated fractures on accelerated flow in unsaturated porous rock

USGS Publications Warehouse

Su, Grace W.; Nimmo, John R.; Dragila, Maria I.

2003-01-01

Fractures that begin and end in the unsaturated zone, or isolated fractures, have been ignored in previous studies because they were generally assumed to behave as capillary barriers and remain nonconductive. We conducted a series of experiments using Berea sandstone samples to examine the physical mechanisms controlling flow in a rock containing a single isolated fracture. The input fluxes and fracture orientation were varied in these experiments. Visualization experiments using dyed water in a thin vertical slab of rock were conducted to identify flow mechanisms occurring due to the presence of the isolated fracture. Two mechanisms occurred: (1) localized flow through the rock matrix in the vicinity of the isolated fracture and (2) pooling of water at the bottom of the fracture, indicating the occurrence of film flow along the isolated fracture wall. These mechanisms were observed at fracture angles of 20 and 60 degrees from the horizontal, but not at 90 degrees. Pooling along the bottom of the fracture was observed over a wider range of input fluxes for low‐angled isolated fractures compared to high‐angled ones. Measurements of matrix water pressures in the samples with the 20 and 60 degree fractures also demonstrated that preferential flow occurred through the matrix in the fracture vicinity, where higher pressures occurred in the regions where faster flow was observed in the visualization experiments. The pooling length at the terminus of a 20 degree isolated fracture was measured as a function of input flux. Calculations of the film flow rate along the fracture were made using these measurements and indicated that up to 22% of the flow occurred as film flow. These experiments, apparently the first to consider isolated fractures, demonstrate that such features can accelerate flow through the unsaturated zone and should be considered when developing conceptual models.

TACT1, a computer program for the transient thermal analysis of a cooled turbine blade or vane equipped with a coolant insert. 1. Users manual

NASA Technical Reports Server (NTRS)

Gaugler, R. E.

1978-01-01

A computer program to calculate transient and steady state temperatures, pressures, and coolant flows in a cooled, axial flow turbine blade or vane with an impingement insert is described. Coolant side heat transfer coefficients are calculated internally in the program, with the user specifying either impingement or convection heat transfer at each internal flow station. Spent impingement air flows in a chordwise direction and is discharged through the trailing edge and through film cooling holes. The ability of the program to handle film cooling is limited by the internal flow model. Sample problems, with tables of input and output, are included in the report. Input to the program includes a description of the blade geometry, coolant supply conditions, outside thermal boundary conditions, and wheel speed. The blade wall can have two layers of different materials, such as a ceramic thermal barrier coating over a metallic substrate. Program output includes the temperature at each node, the coolant pressures and flow rates, and the inside heat-transfer coefficients.

Computer program for design analysis of radial-inflow turbines

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1976-01-01

A computer program written in FORTRAN that may be used for the design analysis of radial-inflow turbines was documented. The following information is included: loss model (estimation of losses), the analysis equations, a description of the input and output data, the FORTRAN program listing and list of variables, and sample cases. The input design requirements include the power, mass flow rate, inlet temperature and pressure, and rotational speed. The program output data includes various diameters, efficiencies, temperatures, pressures, velocities, and flow angles for the appropriate calculation stations. The design variables include the stator-exit angle, rotor radius ratios, and rotor-exit tangential velocity distribution. The losses are determined by an internal loss model.

Development and analysis of closed cycle circulator elements. Final report 31 Jul 978-31 May 1980

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shih, C.C.; Karr, G.R.; Perkins, J.F.

1980-05-01

A series of experiments with various flow rates of laser gas and coolants under several levels of energy inputs has been conducted on the Army Closed Cycle Circulator for pulsed EDL to collect sufficient data for flow calibration and coefficient determination. Verification of the theoretical models depicting the functions of the heat exchangers in maintaining the thermal balance in the flow through the steady and transient states are made through comparison with results of the experimental analysis.

Minimal vascular flows cause strong heat sink effects in hepatic radiofrequency ablation ex vivo.

PubMed

Lehmann, Kai S; Poch, Franz G M; Rieder, Christian; Schenk, Andrea; Stroux, Andrea; Frericks, Bernd B; Gemeinhardt, Ole; Holmer, Christoph; Kreis, Martin E; Ritz, Jörg P; Zurbuchen, Urte

2016-08-01

The present paper aims to assess the lower threshold of vascular flow rate on the heat sink effect in bipolar radiofrequency ablation (RFA) ex vivo. Glass tubes (vessels) of 3.4 mm inner diameter were introduced in parallel to bipolar RFA applicators into porcine liver ex vivo. Vessels were perfused with flow rates of 0 to 1,500 ml/min. RFA (30 W power, 15 kJ energy input) was carried out at room temperature and 37°C. Heat sink effects were assessed in RFA cross sections by the decrease in ablation radius, area and by a high-resolution sector planimetry. Flow rates of 1 ml/min already caused a significant cooling effect (P ≤ 0.001). The heat sink effect reached a maximum at 10 ml/min (18.4 mm/s) and remained stable for flow rates up to 1,500 ml/min. Minimal vascular flows of ≥1 ml/min cause a significant heat sink effect in hepatic RFA ex vivo. A lower limit for volumetric flow rate was not found. The maximum of the heat sink effect was reached at a flow rate of 10 ml/min and remained stable for flow rates up to 1,500 ml/min. Hepatic inflow occlusion should be considered in RFA close to hepatic vessels. © 2016 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

Simulation of two-dimensional adjustable liquid gradient refractive index (L-GRIN) microlens

NASA Astrophysics Data System (ADS)

Le, Zichun; Wu, Xiang; Sun, Yunli; Du, Ying

2017-07-01

In this paper, a two-dimensional liquid gradient refractive index (L-GRIN) microlens is designed which can be used in adjusting focusing direction and focal spot of light beam. Finite element method (FEM) is used to simulate the convection diffusion process happening in core inlet flow and cladding inlet flow. And the ray tracing method shows us the light beam focusing effect including the extrapolation of focal length and output beam spot size. When the flow rates of the core and cladding fluids are held the same between the internal and external, left and right, and upper and lower inlets, the focal length varied from 313 μm to 53.3 μm while the flow rate of liquids ranges from 500 pL/s to 10,000 pL/s. While the core flow rate is bigger than the cladding inlet flow rate, the light beam will focus on a light spot with a tunable size. By adjusting the ratio of cladding inlet flow rate including Qright/Qleft and Qup/Qdown, we get the adjustable two-dimensional focus direction rather than the one-dimensional focusing. In summary, by adjusting the flow rate of core inlet and cladding inlet, the focal length, output beam spot and focusing direction of the input light beam can be manipulated. We suppose this kind of flexible microlens can be used in integrated optics and lab-on-a-chip system.

"Hot-wire" microfluidic flowmeter based on a microfiber coupler.

PubMed

Yan, Shao-Cheng; Liu, Zeng-Yong; Li, Cheng; Ge, Shi-Jun; Xu, Fei; Lu, Yan-Qing

2016-12-15

Using an optical microfiber coupler (MC), we present a microfluidic platform for strong direct or indirect light-liquid interaction by wrapping a MC around a functionalized capillary. The light propagating in the MC and the liquid flowing in the capillary can be combined and divorced smoothly, keeping a long-distance interaction without the conflict of input and output coupling. Using this approach, we experimentally demonstrate a "hot-wire" microfluidic flowmeter based on a gold-integrated helical MC device. The microfluid inside the glass channel takes away the heat, then cools the MC and shifts the resonant wavelength. Due to the long-distance interaction and high temperature sensitivity, the proposed microfluidic flowmeter shows an ultrahigh flow rate sensitivity of 2.183 nm/(μl/s) at a flow rate of 1 μl/s. The minimum detectable change of the flow rate is around 9 nl/s at 1 μl/s.

Simulative method for determining the optimal operating conditions for a cooling plate for lithium-ion battery cell modules

NASA Astrophysics Data System (ADS)

Smith, Joshua; Hinterberger, Michael; Hable, Peter; Koehler, Juergen

2014-12-01

Extended battery system lifetime and reduced costs are essential to the success of electric vehicles. An effective thermal management strategy is one method of enhancing system lifetime increasing vehicle range. Vehicle-typical space restrictions favor the minimization of battery thermal management system (BTMS) size and weight, making their production and subsequent vehicle integration extremely difficult and complex. Due to these space requirements, a cooling plate as part of a water-glycerol cooling circuit is commonly implemented. This paper presents a computational fluid dynamics (CFD) model and multi-objective analysis technique for determining the thermal effect of coolant flow rate and inlet temperature in a cooling plate-at a range of vehicle operating conditions-on a battery system, thereby providing a dynamic input for one-dimensional models. Traditionally, one-dimensional vehicular thermal management system models assume a static heat input from components such as a battery system: as a result, the components are designed for a set coolant input (flow rate and inlet temperature). Such a design method is insufficient for dynamic thermal management models and control strategies, thereby compromising system efficiency. The presented approach allows for optimal BMTS design and integration in the vehicular coolant circuit.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, Robert F.; Dietrich, Daniel D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

Plasma Indicator Dispersion in Arteries of the Human Leg

PubMed Central

Bassingthwaighte, James B.

2010-01-01

Indicator-dilution curves were recorded from the femoral and dorsalis pedis arteries of five normal men after injections of indocyanine green into the superior vena cava or thoracic aorta. By considering the femoral curves as inputs to a mathematically linear system and the dorsalis pedis curves as outputs, transfer functions (the distribution of transit times) for the arterial segment between these sites were obtained in terms of a four-parameter model, the lagged normal density curve, over a sixfold range of flow rates. The parameters of the spread (dispersion) of 57 transfer functions were proportional to the mean transit time. The mean difference between transit time and appearance time was 0.30 t̄; the square root of the variances was 0.18 t̄. These linear relationships suggest that flow rate has no significant influence on dispersion and that, since no transition from laminar to turbulent flow was apparent, arterial flow characteristics were not significantly changed over a wide range of flow rates. The secondary implication is that the rate of spatial longitudinal spreading of indicator with distance traveled is primarily a function of the geometry of the arterial system, not of the rate of flow, and, therefore, that the spatial distribution at any instant is a function of this rate and of the distance traveled through the system. PMID:5330717

CATALYTIC RECOMBINER FOR A NUCLEAR REACTOR

DOEpatents

King, L.D.P.

1960-07-01

A hydrogen-oxygen recombiner is described for use with water-boiler type reactors. The catalyst used is the wellknown platinized alumina, and the novelty lies in the structural arrangement used to prevent flashback through the gas input system. The recombiner is cylindrical, the gases at the input end being deflected by a baffle plate through a first flashback shield of steel shot into an annular passage adjacent to and extending the full length of the housing. Below the baffle plate the gases flow first through an outer annular array of alumina pellets which serve as a second flashback shield, a means of distributing the flowing gases evenly and as a means of reducing radiation losses to the walls. Thereafter the gases flow inio the centrally disposed catalyst bed where recombination is effected. The steam and uncombined gases flow into a centrally disposed cylindrical passage inside the catalyst bod and thereafter out through the exit port. A high rate of recombination is effected.

Prediction of Flow Stress in Cadmium Using Constitutive Equation and Artificial Neural Network Approach

NASA Astrophysics Data System (ADS)

Sarkar, A.; Chakravartty, J. K.

2013-10-01

A model is developed to predict the constitutive flow behavior of cadmium during compression test using artificial neural network (ANN). The inputs of the neural network are strain, strain rate, and temperature, whereas flow stress is the output. Experimental data obtained from compression tests in the temperature range -30 to 70 °C, strain range 0.1 to 0.6, and strain rate range 10-3 to 1 s-1 are employed to develop the model. A three-layer feed-forward ANN is trained with Levenberg-Marquardt training algorithm. It has been shown that the developed ANN model can efficiently and accurately predict the deformation behavior of cadmium. This trained network could predict the flow stress better than a constitutive equation of the type.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pak, S.; Sites, J.R.

A Kaufman-type broad beam ion source, used for sputtering and etching purposes, has been operated with Ar, Kr,O/sub 2/ and N/sub 2/ gas inputs over a wide range of beam energies (200-1200 eV) and gas flow rates (1-10 sccm). The maximum ion beam current density for each gas saturates at about 2.5 mA/sq. cm. as gas flow is increased. The discharge threshold voltage necessary to produce a beam and the beam efficiency (beam current/molecular current), however, varied considerably. Kr had the lowest threshold and highest efficiency, Ar next, then N/sub 2/ and O/sub 2/. The ion beam current varied onlymore » weakly with beam energy for low gas flow rates, but showed a factor of two increase when the gas flow was higher.« less

Users manual for updated computer code for axial-flow compressor conceptual design

NASA Technical Reports Server (NTRS)

Glassman, Arthur J.

1992-01-01

An existing computer code that determines the flow path for an axial-flow compressor either for a given number of stages or for a given overall pressure ratio was modified for use in air-breathing engine conceptual design studies. This code uses a rapid approximate design methodology that is based on isentropic simple radial equilibrium. Calculations are performed at constant-span-fraction locations from tip to hub. Energy addition per stage is controlled by specifying the maximum allowable values for several aerodynamic design parameters. New modeling was introduced to the code to overcome perceived limitations. Specific changes included variable rather than constant tip radius, flow path inclination added to the continuity equation, input of mass flow rate directly rather than indirectly as inlet axial velocity, solution for the exact value of overall pressure ratio rather than for any value that met or exceeded it, and internal computation of efficiency rather than the use of input values. The modified code was shown to be capable of computing efficiencies that are compatible with those of five multistage compressors and one fan that were tested experimentally. This report serves as a users manual for the revised code, Compressor Spanline Analysis (CSPAN). The modeling modifications, including two internal loss correlations, are presented. Program input and output are described. A sample case for a multistage compressor is included.

Multiobjective Optimization of Atmospheric Plasma Spray Process Parameters to Deposit Yttria-Stabilized Zirconia Coatings Using Response Surface Methodology

NASA Astrophysics Data System (ADS)

Ramachandran, C. S.; Balasubramanian, V.; Ananthapadmanabhan, P. V.

2011-03-01

Atmospheric plasma spraying is used extensively to make Thermal Barrier Coatings of 7-8% yttria-stabilized zirconia powders. The main problem faced in the manufacture of yttria-stabilized zirconia coatings by the atmospheric plasma spraying process is the selection of the optimum combination of input variables for achieving the required qualities of coating. This problem can be solved by the development of empirical relationships between the process parameters (input power, primary gas flow rate, stand-off distance, powder feed rate, and carrier gas flow rate) and the coating quality characteristics (deposition efficiency, tensile bond strength, lap shear bond strength, porosity, and hardness) through effective and strategic planning and the execution of experiments by response surface methodology. This article highlights the use of response surface methodology by designing a five-factor five-level central composite rotatable design matrix with full replication for planning, conduction, execution, and development of empirical relationships. Further, response surface methodology was used for the selection of optimum process parameters to achieve desired quality of yttria-stabilized zirconia coating deposits.

Investigation of a liquid-fed water resistojet plume

NASA Technical Reports Server (NTRS)

Manzella, D. H.; Carney, L. M.

1989-01-01

Measurements of mass flux and flow angle were taken throughout the forward flow region of the exhaust of a liquid-fed water resistojet using a quartz crystal microbalance (QCM). The resistojet operated at a mass flow rate of 0.1 g/s with a power input of 330 Watts. Measured values were compared to theoretical predictions obtained by employing a source flow approximation. Excellent agreement between predicted and measured mass flux values was attained; however, this agreement was highly dependent on knowledge of nozzle flow conditions. Measurements of the temperature at which the exhaust condensed on the QCM were obtained as a function of incident mass flux.

A micromixer with consistent mixing performance for a wide range of flow rates.

PubMed

Goovaerts, Robert; Van Assche, Tom; Sonck, Marc; Denayer, Joeri; Desmet, Gert

2015-02-01

A micromixer with consistent mixing performance for a wide range of flow rates is presented. The mixer makes use of internally moving elements, i.e. steel balls that are located in dedicated mixing chambers. Movement is induced by a rotating magnetic field. To get better insight in differences between active and passive mixing, we studied a mixer that can operate in both regimes. A mixing performance study for a range of flow rates along with pressure drop data is presented. The response of the moving elements in regard to the magnetic field is shown experimentally and shows the limitations of earlier modeling studies. Lastly, the estimated power input on the fluids was calculated and allows for a comparison with more well-known convective-type mixers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fluidic angular velocity sensor

NASA Technical Reports Server (NTRS)

Berdahl, C. M. (Inventor)

1986-01-01

A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

NASA Technical Reports Server (NTRS)

Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

1982-01-01

A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

Numerical modeling of rapidly varying flows using HEC-RAS and WSPG models.

PubMed

Rao, Prasada; Hromadka, Theodore V

2016-01-01

The performance of two popular hydraulic models (HEC-RAS and WSPG) for modeling hydraulic jump in an open channel is investigated. The numerical solutions are compared with a new experimental data set obtained for varying channel bottom slopes and flow rates. Both the models satisfactorily predict the flow depths and location of the jump. The end results indicate that the numerical models output is sensitive to the value of chosen roughness coefficient. For this application, WSPG model is easier to implement with few input variables.

An integrated vegetated ditch system reduces chlorpyrifos loading in agricultural runoff.

PubMed

Phillips, Bryn M; Anderson, Brian S; Cahn, Michael; Rego, Jessa L; Voorhees, Jennifer P; Siegler, Katie; Zhang, Xuyang; Budd, Robert; Goh, Kean; Tjeerdema, Ron S

2017-03-01

Agricultural runoff containing toxic concentrations of the organophosphate pesticide chlorpyrifos has led to impaired water body listings and total maximum daily load restrictions in California's central coast watersheds. Chlorpyrifos use is now tightly regulated by the Central Coast Regional Water Quality Control Board. This study evaluated treatments designed to reduce chlorpyrifos in agricultural runoff. Initial trials evaluated the efficacy of 3 different drainage ditch installations individually: compost filters, granulated activated carbon (GAC) filters, and native grasses in a vegetated ditch. Treatments were compared to bare ditch controls, and experiments were conducted with simulated runoff spiked with chlorpyrifos at a 1.9 L/s flow rate. Chlorpyrifos concentrations and toxicity to Ceriodaphnia dubia were measured at the input and output of the system. Input concentrations of chlorpyrifos ranged from 858 ng/L to 2840 ng/L. Carbon filters and vegetation provided the greatest load reduction of chlorpyrifos (99% and 90%, respectively). Toxicity was completely removed in only one of the carbon filter trials. A second set of trials evaluated an integrated approach combining all 3 treatments. Three trials were conducted each at 3.2 L/s and 6.3 L/s flow rates at input concentrations ranging from 282 ng/L to 973 ng/L. Chlorpyrifos loadings were reduced by an average of 98% at the low flow rate and 94% at the high flow rate. Final chlorpyrifos concentrations ranged from nondetect (<50 ng/L) to 82 ng/L. Toxicity to C. dubia was eliminated in 3 of 6 integrated trials. Modeling of the ditch and its components informed design alterations that are intended to eventually remove up to 100% of pesticides and sediment. Future work includes investigating the adsorption capacity of GAC, costs associated with GAC disposal, and real-world field trials to further reduce model uncertainties and confirm design optimization. Trials with more water-soluble pesticides such as neonicotinoids are also recommended. Integr Environ Assess Manag 2017;13:423-430. © 2016 SETAC. © 2016 SETAC.

Culvert Analysis Program Graphical User Interface 1.0--A preprocessing and postprocessing tool for estimating flow through culvert

USGS Publications Warehouse

Bradley, D. Nathan

2013-01-01

The peak discharge of a flood can be estimated from the elevation of high-water marks near the inlet and outlet of a culvert after the flood has occurred. This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks on trees or buildings. When combined with the cross-sectional geometry of the channel upstream from the culvert and the culvert size, shape, roughness, and orientation, the high-water marks define a water-surface profile that can be used to estimate the peak discharge by using the methods described by Bodhaine (1968). This type of measurement is in contrast to a “direct” measurement of discharge made during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a streamgage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the streamgage, resulting in more accurate computation of high flows. The Culvert Analysis Program (CAP) (Fulford, 1998) is a command-line program written in Fortran for computing peak discharges and culvert rating surfaces or curves. CAP reads input data from a formatted text file and prints results to another formatted text file. Preparing and correctly formatting the input file may be time-consuming and prone to errors. This document describes the CAP graphical user interface (GUI)—a modern, cross-platform, menu-driven application that prepares the CAP input file, executes the program, and helps the user interpret the output

Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure

NASA Technical Reports Server (NTRS)

Ouazzani, Jalil; Rosenberger, Franz

1990-01-01

A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

Rationale choosing interval of a piecewise-constant approximation of input rate of non-stationary queue system

NASA Astrophysics Data System (ADS)

Korelin, Ivan A.; Porshnev, Sergey V.

2018-01-01

The paper demonstrates the possibility of calculating the characteristics of the flow of visitors to objects carrying out mass events passing through checkpoints. The mathematical model is based on the non-stationary queuing system (NQS) where dependence of requests input rate from time is described by the function. This function was chosen in such way that its properties were similar to the real dependencies of speed of visitors arrival on football matches to the stadium. A piecewise-constant approximation of the function is used when statistical modeling of NQS performing. Authors calculated the dependencies of the queue length and waiting time for visitors to service (time in queue) on time for different laws. Time required to service the entire queue and the number of visitors entering the stadium at the beginning of the match were calculated too. We found the dependence for macroscopic quantitative characteristics of NQS from the number of averaging sections of the input rate.

Method and apparatus for smart battery charging including a plurality of controllers each monitoring input variables

DOEpatents

Hammerstrom, Donald J.

2013-10-15

A method for managing the charging and discharging of batteries wherein at least one battery is connected to a battery charger, the battery charger is connected to a power supply. A plurality of controllers in communication with one and another are provided, each of the controllers monitoring a subset of input variables. A set of charging constraints may then generated for each controller as a function of the subset of input variables. A set of objectives for each controller may also be generated. A preferred charge rate for each controller is generated as a function of either the set of objectives, the charging constraints, or both, using an algorithm that accounts for each of the preferred charge rates for each of the controllers and/or that does not violate any of the charging constraints. A current flow between the battery and the battery charger is then provided at the actual charge rate.

Closed Loop Two-Phase Thermosyphon of Small Dimensions: a Review of the Experimental Results

NASA Astrophysics Data System (ADS)

Franco, Alessandro; Filippeschi, Sauro

2012-06-01

A bibliographical review on the heat and mass transfer in gravity assisted Closed Loop Two Phase Thermosyphons (CLTPT) with channels having a hydraulic diameter of the order of some millimetres and input power below 1 kW is proposed. The available experimental works in the literature are critically analysed in order to highlight the main results and the correlation between mass flow rate and heat input in natural circulation loops. A comparison of different experimental apparatuses and results is made. It is observed that the results are very different among them and in many cases the experimental data disagree with the conventional theory developed for an imposed flow rate. The paper analyses the main differences among the experimental devices and try to understand these disagreements. From the present analysis it is evident that further systematic studies are required to generate a meaningful body of knowledge of the heat and mass transport mechanism in these devices for practical applications in cooling devices or energy systems.

Active combustion flow modulation valve

DOEpatents

Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

2013-09-24

A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

Miniature piezo electric vacuum inlet valve

DOEpatents

Keville, R.F.; Dietrich, D.D.

1998-03-24

A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability is disclosed. The low power (<1.6 watts), high pulse rate (<2 milliseconds), variable flow inlet valve is utilized for mass spectroscopic applications or other applications where pulsed or continuous flow conditions are needed. The inlet valve also has a very minimal dead volume of less than 0.01 std/cc. The valve can utilize, for example, a 12 Vdc input/750 Vdc, 3 mA output power supply compared to conventional piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three. 6 figs.

Processes and rates of sediment and wood accumulation in the headwater streams of the Oregon Coast Range, U.S.A.

Treesearch

C. L. May; R. E. Gresswell

2003-01-01

Abstract - Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low-order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was...

Aircraft Engine Sump Fire Mitigation, Phase 2

NASA Technical Reports Server (NTRS)

Rosenlieb, J. W.

1978-01-01

The effect of changes in the input parameters (air leakage flow rate and temperature and lubricating oil inlet flow rate and temperature) over a specified range on the flammability conditions within an aircraft engine bearing sump was investigated. An analytical study was performed to determine the effect of various parameters on the generation rate of oil vapor from oil droplets in a hot air stream flowing in a cylindrical tube. The ignition of the vapor-air mixture by an ignition source was considered. The experimental investigation demonstrated that fires would be ignited by a spark ignitor over the full range of air and oil flow rates and air temperatures evaluated. However, no fires could be ignited when the oil inlet temperature was maintained below 41.7 K (290 F). The severity of the fires ignited were found to be directly proportional to the hot air flow rate. Reasonably good correlation was found between the mixture temperature in the sump at the ignitor location and the flammability limits as defined by flammability theory; thus a fairly reliable experimental method of determining flammable conditions within a sump was demonstrated. The computerized mathematical model shows that oil droplet size and air temperature have the greatest influence on the generation rate of oil vapor.

On-site SiH4 generator using hydrogen plasma generated in slit-type narrow gap

NASA Astrophysics Data System (ADS)

Takei, Norihisa; Shinoda, Fumiya; Kakiuchi, Hiroaki; Yasutake, Kiyoshi; Ohmi, Hiromasa

2018-06-01

We have been developing an on-site silane (SiH4) generator based on use of the chemical etching reaction between solid silicon (Si) and the high-density H atoms that are generated in high-pressure H2 plasma. In this study, we have developed a slit-type plasma source for high-efficiency SiH4 generation. High-density H2 plasma was generated in a narrow slit-type discharge gap using a 2.45 GHz microwave power supply. The plasma’s optical emission intensity distribution along the slit was measured and the resulting distribution was reflected by both the electric power distribution and the hydrogen gas flow. Because the Si etching rate strongly affects the SiH4 generation rate, the Si etching behavior was investigated with respect to variations in the experimental parameters. The weight etch rate increased monotonically with increasing input microwave power. However, the weight etch rate decreased with increasing H2 pressure and an increasing plasma gap. This reduction in the etch rate appears to be related to shrinkage of the plasma generation area because increased input power is required to maintain a constant plasma area with increasing H2 pressure and the increasing plasma gap. Additionally, the weight etch rate also increases with increasing H2 flow rate. The SiH4 generation rate of the slit-type plasma source was also evaluated using gas-phase Fourier transform infrared absorption spectroscopy and the material utilization efficiencies of both Si and the H2 gas for SiH4 gas formation were discussed. The main etch product was determined to be SiH4 and the developed plasma source achieved a SiH4 generation rate of 10 sccm (standard cubic centimeters per minute) at an input power of 900 W. In addition, the Si utilization efficiency exceeded 60%.

Simulation of ground-water flow in glaciofluvial aquifers in the Grand Rapids area, Minnesota

USGS Publications Warehouse

Jones, Perry M.

2004-01-01

A calibrated steady-state, finite-difference, ground-waterflow model was constructed to simulate ground-water flow in three glaciofluvial aquifers, defined in this report as the upper, middle, and lower aquifers, in an area of about 114 mi2 surrounding the city of Grand Rapids in north-central Minnesota. The calibrated model will be used by Minnesota Department of Health and communities in the Grand Rapids area in the development of wellhead protection plans for their water supplies. The model was calibrated through comparison of simulated ground-water levels to measured static water levels in 351 wells, and comparison of simulated base-flow rates to estimated base-flow rates for reaches of the Mississippi and Prairie Rivers. Model statistics indicate that the model tends to overestimate ground-water levels. The root mean square errors ranged from +12.83 ft in wells completed in the upper aquifer to +19.10 ft in wells completed in the middle aquifer. Mean absolute differences between simulated and measured water levels ranged from +4.43 ft for wells completed in the upper aquifer to +9.25 ft for wells completed in the middle aquifer. Mean algebraic differences ranged from +9.35 ft for wells completed in the upper aquifer to +14.44 ft for wells completed in the middle aquifer, with the positive differences indicating that the simulated water levels were higher than the measured water levels. Percentage errors between simulated and estimated base-flow rates for the three monitored reaches all were less than 10 percent, indicating good agreement. Simulated ground-water levels were most sensitive to changes in general-head boundary conductance, indicating that this characteristic is the predominant model input variable controlling steady-state water-level conditions. Simulated groundwater flow to stream reaches was most sensitive to changes in horizontal hydraulic conductivity, indicating that this characteristic is the predominant model input variable controlling steady-state flow conditions.

Development and Characterization of a Rate-Dependent Three-Dimensional Macroscopic Plasticity Model Suitable for Use in Composite Impact Problems

NASA Technical Reports Server (NTRS)

Goldberg, Robert K.; Carney, Kelly S.; DuBois, Paul; Hoffarth, Canio; Rajan, Subramaniam; Blankenhorn, Gunther

2015-01-01

Several key capabilities have been identified by the aerospace community as lacking in the material/models for composite materials currently available within commercial transient dynamic finite element codes such as LS-DYNA. Some of the specific desired features that have been identified include the incorporation of both plasticity and damage within the material model, the capability of using the material model to analyze the response of both three-dimensional solid elements and two dimensional shell elements, and the ability to simulate the response of composites composed with a variety of composite architectures, including laminates, weaves and braids. In addition, a need has been expressed to have a material model that utilizes tabulated experimentally based input to define the evolution of plasticity and damage as opposed to utilizing discrete input parameters (such as modulus and strength) and analytical functions based on curve fitting. To begin to address these needs, an orthotropic macroscopic plasticity based model suitable for implementation within LS-DYNA has been developed. Specifically, the Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic plasticity model with a non-associative flow rule. The coefficients in the yield function are determined based on tabulated stress-strain curves in the various normal and shear directions, along with selected off-axis curves. Incorporating rate dependence into the yield function is achieved by using a series of tabluated input curves, each at a different constant strain rate. The non-associative flow-rule is used to compute the evolution of the effective plastic strain. Systematic procedures have been developed to determine the values of the various coefficients in the yield function and the flow rule based on the tabulated input data. An algorithm based on the radial return method has been developed to facilitate the numerical implementation of the material model. The presented paper will present in detail the development of the orthotropic plasticity model and the procedures used to obtain the required material parameters. Methods in which a combination of actual testing and selective numerical testing can be combined to yield the appropriate input data for the model will be described. A specific laminated polymer matrix composite will be examined to demonstrate the application of the model.

Spacelab uplink/downlink data flow and formats

NASA Technical Reports Server (NTRS)

Kandefer, F.

1978-01-01

The results of an analysis of the Spacelab (SL) data uplink/downlink structure and those data system elements associated with the support of this data flow are presented. Specific objectives of this report are to present the results of the following analyses: (1) operations of the SL high rate multiplexer, including format structure, data rates, format combinations, format switching, etc.; (2) operations of SL data recorders to include the definition of modes, data rates and forms; (3) operations of the high rate demultiplexer as described above; (4) potential experiment data formats defining formatting parameters to be considered in decommutation analysis; (5) SL computer input/output (I/O) decommutation channels, including the definition of structure, quantity and use of this I/O data; (6) detailed requirements of the data quality monitoring philosophy for this function.

Quantitative characterization of arc discharge as vacuum interface

DOE PAGES

Huang, S.; Zhu, K.; Lu, Y. R.; ...

2014-12-19

An arc discharge with channel diameters of 3 mm and 6 mm and lengths between 30mm and 60mm was experimentally investigated for its potential to function as plasma window, i.e., interface vacuum regions of different pressures. In this study, electron temperature of the plasma channel measured spectroscopically varied in the range of 7000K to 15000K, increasing with discharge current while decreasing with gas flow rate. The plasma window had a slightly positive I-V characteristics over the whole range of investigated current 30A–70 A. Measurements of pressure separation capability, which were determined by input current, gas flow rate, discharge channel diameter,more » and length, were well explained by viscosity effect and “thermal-block” effect. The experimental results of global parameters including temperature, gas flow rate, and voltage had a good agreement with the simulation results calculated by an axis-symmetry Fluent-based magneto-hydrodynamic model.« less

File-based data flow in the CMS Filter Farm

NASA Astrophysics Data System (ADS)

Andre, J.-M.; Andronidis, A.; Bawej, T.; Behrens, U.; Branson, J.; Chaze, O.; Cittolin, S.; Darlea, G.-L.; Deldicque, C.; Dobson, M.; Dupont, A.; Erhan, S.; Gigi, D.; Glege, F.; Gomez-Ceballos, G.; Hegeman, J.; Holzner, A.; Jimenez-Estupiñán, R.; Masetti, L.; Meijers, F.; Meschi, E.; Mommsen, R. K.; Morovic, S.; Nunez-Barranco-Fernandez, C.; O'Dell, V.; Orsini, L.; Paus, C.; Petrucci, A.; Pieri, M.; Racz, A.; Roberts, P.; Sakulin, H.; Schwick, C.; Stieger, B.; Sumorok, K.; Veverka, J.; Zaza, S.; Zejdl, P.

2015-12-01

During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.

Real-air data reduction procedures based on flow parameters measured in the test section of supersonic and hypersonic facilities

NASA Technical Reports Server (NTRS)

Miller, C. G., III; Wilder, S. E.

1972-01-01

Data-reduction procedures for determining free stream and post-normal shock kinetic and thermodynamic quantities are derived. These procedures are applicable to imperfect real air flows in thermochemical equilibrium for temperatures to 15 000 K and a range of pressures from 0.25 N/sq m to 1 GN/sq m. Although derived primarily to meet the immediate needs of the 6-inch expansion tube, these procedures are applicable to any supersonic or hypersonic test facility where combinations of three of the following flow parameters are measured in the test section: (1) Stagnation pressure behind normal shock; (2) freestream static pressure; (3) stagnation point heat transfer rate; (4) free stream velocity; (5) stagnation density behind normal shock; and (6) free stream density. Limitations of the nine procedures and uncertainties in calculated flow quantities corresponding to uncertainties in measured input data are discussed. A listing of the computer program is presented, along with a description of the inputs required and a sample of the data printout.

Spray Characteristics of a Hybrid Twin-Fluid Pressure-Swirl Atomizer

NASA Technical Reports Server (NTRS)

Durham, M. J.; Sojka, P. E.; Ashmore, C. B.

2004-01-01

The spray performance of a fuel injection system applicable for use in main combustion chamber of an oxidizer-rich staged combustion (ORSC) cycles is presented. The experimental data reported here include mean drop size and drop size distribution, spray cone half-angle, and momentum rate (directly related to spray penetration). The maximum entropy formalism, MEF, method to predict drop size distribution is applied and compared to the experimental data. Geometric variables considered include the radius of the injector inlet orifice plate through which oxidizer flows (&) and the exposed length from the fuel inlet to the injector exit plane (L2). Operating conditions that were varied include the liquid mass flow rate and air mass flow rate. For orifices B and C there is a significant dependence of D3Z on both the air and liquid mass flow rates, as well as on L2. For the A orifice, the momentum rate of the air flow appears to exceed a threshold value above which a constant D32 is obtained. Using the MEF method, a semi-analytical process was developed to model the spray distribution using two input parameters (q = 0.4 and Dso). The momentum rate of the spray is directly related to the air and liquid mass flow rates. The cone half angle of the spray ranges from 25 to 17 degrees. The data resulting from this project will eventually be used to develop advanced rocket systems.

REMOVAL OF SLIGHTLY HEAVY GASES FROM A VALLEY BY CROSSWINDS

EPA Science Inventory

Wind-tunnel experiments made to determine how rapidly dense gas is removed from a topographical depression by a crosswind are reported. he density and flow rate of the gas (input at the bottom of a V-shaped valley in otherwise homogeneous, flat terrain)were together sufficiently ...

Artificial neural networks modelling the prednisolone nanoprecipitation in microfluidic reactors.

PubMed

Ali, Hany S M; Blagden, Nicholas; York, Peter; Amani, Amir; Brook, Toni

2009-06-28

This study employs artificial neural networks (ANNs) to create a model to identify relationships between variables affecting drug nanoprecipitation using microfluidic reactors. The input variables examined were saturation levels of prednisolone, solvent and antisolvent flow rates, microreactor inlet angles and internal diameters, while particle size was the single output. ANNs software was used to analyse a set of data obtained by random selection of the variables. The developed model was then assessed using a separate set of validation data and provided good agreement with the observed results. The antisolvent flow rate was found to have the dominant role on determining final particle size.

Mathematical Model for a Simplified Calculation of the Input Momentum Coefficient for AFC Purposes

NASA Astrophysics Data System (ADS)

Hirsch, Damian; Gharib, Morteza

2016-11-01

Active Flow Control (AFC) is an emerging technology which aims at enhancing the aerodynamic performance of flight vehicles (i.e., to save fuel). A viable AFC system must consider the limited resources available on a plane for attaining performance goals. A higher performance goal (i.e., airplane incremental lift) demands a higher input fluidic requirement (i.e., mass flow rate). Therefore, the key requirement for a successful and practical design is to minimize power input while maximizing performance to achieve design targets. One of the most used design parameters is the input momentum coefficient Cμ. The difficulty associated with Cμ lies in obtaining the parameters for its calculation. In the literature two main approaches can be found, which both have their own disadvantages (assumptions, difficult measurements). A new, much simpler calculation approach will be presented that is based on a mathematical model that can be applied to most jet designs (i.e., steady or sweeping jets). The model-incorporated assumptions will be justified theoretically as well as experimentally. Furthermore, the model's capabilities are exploited to give new insight to the AFC technology and its physical limitations. Supported by Boeing.

Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network.

PubMed

Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

2016-06-30

The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002-0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C-550 °C) and strain rates (0.01-10 s -1 ). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network

PubMed Central

Shakiba, Mohammad; Parson, Nick; Chen, X.-Grant

2016-01-01

The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002–0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C–550 °C) and strain rates (0.01–10 s−1). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress. PMID:28773658

Managing fish habitat for flow and temperature extremes ...

EPA Pesticide Factsheets

Summer low flows and stream temperature maxima are key drivers affecting the sustainability of fish populations. Thus, it is critical to understand both the natural templates of spatiotemporal variability, how these are shifting due to anthropogenic influences of development and climate change, and how these impacts can be moderated by natural and constructed green infrastructure. Low flow statistics of New England streams have been characterized using a combination of regression equations to describe long-term averages as a function of indicators of hydrologic regime (rain- versus snow-dominated), precipitation, evapotranspiration or temperature, surface water storage, baseflow recession rates, and impervious cover. Difference equations have been constructed to describe interannual variation in low flow as a function of changing air temperature, precipitation, and ocean-atmospheric teleconnection indices. Spatial statistical network models have been applied to explore fine-scale variability of thermal regimes along stream networks in New England as a function of variables describing natural and altered energy inputs, groundwater contributions, and retention time. Low flows exacerbate temperature impacts by reducing thermal inertia of streams to energy inputs. Based on these models, we can construct scenarios of fish habitat suitability using current and projected future climate and the potential for preservation and restoration of historic habitat regimes th

Predictive onboard flow control for packet switching satellites

NASA Technical Reports Server (NTRS)

Bobinsky, Eric A.

1992-01-01

We outline two alternate approaches to predicting the onset of congestion in a packet switching satellite, and argue that predictive, rather than reactive, flow control is necessary for the efficient operation of such a system. The first method discussed is based on standard, statistical techniques which are used to periodically calculate a probability of near-term congestion based on arrival rate statistics. If this probability exceeds a present threshold, the satellite would transmit a rate-reduction signal to all active ground stations. The second method discussed would utilize a neural network to periodically predict the occurrence of buffer overflow based on input data which would include, in addition to arrival rates, the distributions of packet lengths, source addresses, and destination addresses.

The UK waste input-output table: Linking waste generation to the UK economy.

PubMed

Salemdeeb, Ramy; Al-Tabbaa, Abir; Reynolds, Christian

2016-10-01

In order to achieve a circular economy, there must be a greater understanding of the links between economic activity and waste generation. This study introduces the first version of the UK waste input-output table that could be used to quantify both direct and indirect waste arisings across the supply chain. The proposed waste input-output table features 21 industrial sectors and 34 waste types and is for the 2010 time-period. Using the waste input-output table, the study results quantitatively confirm that sectors with a long supply chain (i.e. manufacturing and services sectors) have higher indirect waste generation rates compared with industrial primary sectors (e.g. mining and quarrying) and sectors with a shorter supply chain (e.g. construction). Results also reveal that the construction, mining and quarrying sectors have the highest waste generation rates, 742 and 694 tonne per £1m of final demand, respectively. Owing to the aggregated format of the first version of the waste input-output, the model does not address the relationship between waste generation and recycling activities. Therefore, an updated version of the waste input-output table is expected be developed considering this issue. Consequently, the expanded model would lead to a better understanding of waste and resource flows in the supply chain. © The Author(s) 2016.

Field Measurements of the 1983 Royal Gardens Lava Flows, Kilauea Volcano, and 1984 Mauna Loa Lava Flow, Hawaii

NASA Technical Reports Server (NTRS)

Fink, J.; Zimbelman, J.

1985-01-01

Theoretical models used in the remote determination of lava flow rheology and compositions rely on estimates of such geometric and flow parameters as volume flow rates, levee heights, and channel dimensions, as well as morphologic and structural patterns on the flow surfaces. Quantitative measures of these variables are difficult to obtain, even under optimum conditions. Detailed topographic profiles across several Hawaiian lava flows that were carefully monitored by the U.S. Geological Survey during their emplacement in 1983 were surveyed in order to test various flow emplacement models. Twenty two accurate channel cross sections were constructed by combining these profiles with digitized pre-flow topographic measurements. Levee heights, shear zone widths, and flow depths could then be read directly from the cross sections and input into the models. The profiles were also compared with ones constructed for some Martian lava flows.

An Approximate Axisymmetric Viscous Shock Layer Aeroheating Method for Three-Dimensional Bodies

NASA Technical Reports Server (NTRS)

Brykina, Irina G.; Scott, Carl D.

1998-01-01

A technique is implemented for computing hypersonic aeroheating, shear stress, and other flow properties on the windward side of a three-dimensional (3D) blunt body. The technique uses a 2D/axisymmetric flow solver modified by scale factors for a, corresponding equivalent axisymmetric body. Examples are given in which a 2D solver is used to calculate the flow at selected meridional planes on elliptic paraboloids in reentry flight. The report describes the equations and the codes used to convert the body surface parameters into input used to scale the 2D viscous shock layer equations in the axisymmetric viscous shock layer code. Very good agreement is obtained with solutions to finite rate chemistry 3D thin viscous shock layer equations for a finite rate catalytic body.

Model modifications for simulation of flow through stratified rocks in eastern Ohio

USGS Publications Warehouse

Helgesen, J.O.; Razem, A.C.; Larson, S.P.

1982-01-01

A quasi three-dimensional groundwater flow model is being used as part of a study to determine impacts of coal-strip mining on local hydrologic systems. Modifications to the model were necessary to simulate local hydrologic conditions properly. Perched water tables required that the method of calculating vertical flow rate be changed. A head-dependent spring-discharge function and a head-dependent stream aquifer-interchange function were added to the program. Modifications were also made to allow recharge from precipitation to any layer. The modified program, data deck instructions, and sample input and output are presented. (USGS)

A dynamic plug flow reactor model for a vanadium redox flow battery cell

NASA Astrophysics Data System (ADS)

Li, Yifeng; Skyllas-Kazacos, Maria; Bao, Jie

2016-04-01

A dynamic plug flow reactor model for a single cell VRB system is developed based on material balance, and the Nernst equation is employed to calculate cell voltage with consideration of activation and concentration overpotentials. Simulation studies were conducted under various conditions to investigate the effects of several key operation variables including electrolyte flow rate, upper SOC limit and input current magnitude on the cell charging performance. The results show that all three variables have a great impact on performance, particularly on the possibility of gassing during charging at high SOCs or inadequate flow rates. Simulations were also carried out to study the effects of electrolyte imbalance during long term charging and discharging cycling. The results show the minimum electrolyte flow rate needed for operation within a particular SOC range in order to avoid gassing side reactions during charging. The model also allows scheduling of partial electrolyte remixing operations to restore capacity and also avoid possible gassing side reactions during charging. Simulation results also suggest the proper placement for cell voltage monitoring and highlight potential problems associated with setting the upper charging cut-off limit based on the inlet SOC calculated from the open-circuit cell voltage measurement.

Simulation of Runoff Hydrograph on Soil Surfaces with Different Microtopography Using a Travel Time Method at the Plot Scale

PubMed Central

Zhao, Longshan; Wu, Faqi

2015-01-01

In this study, a simple travel time-based runoff model was proposed to simulate a runoff hydrograph on soil surfaces with different microtopographies. Three main parameters, i.e., rainfall intensity (I), mean flow velocity (v m) and ponding time of depression (t p), were inputted into this model. The soil surface was divided into numerous grid cells, and the flow length of each grid cell (l i) was then calculated from a digital elevation model (DEM). The flow velocity in each grid cell (v i) was derived from the upstream flow accumulation area using v m. The total flow travel time through each grid cell to the surface outlet was the sum of the sum of flow travel times along the flow path (i.e., the sum of l i/v i) and t p. The runoff rate at the slope outlet for each respective travel time was estimated by finding the sum of the rain rate from all contributing cells for all time intervals. The results show positive agreement between the measured and predicted runoff hydrographs. PMID:26103635

Simulation of Runoff Hydrograph on Soil Surfaces with Different Microtopography Using a Travel Time Method at the Plot Scale.

PubMed

Zhao, Longshan; Wu, Faqi

2015-01-01

In this study, a simple travel time-based runoff model was proposed to simulate a runoff hydrograph on soil surfaces with different microtopographies. Three main parameters, i.e., rainfall intensity (I), mean flow velocity (vm) and ponding time of depression (tp), were inputted into this model. The soil surface was divided into numerous grid cells, and the flow length of each grid cell (li) was then calculated from a digital elevation model (DEM). The flow velocity in each grid cell (vi) was derived from the upstream flow accumulation area using vm. The total flow travel time through each grid cell to the surface outlet was the sum of the sum of flow travel times along the flow path (i.e., the sum of li/vi) and tp. The runoff rate at the slope outlet for each respective travel time was estimated by finding the sum of the rain rate from all contributing cells for all time intervals. The results show positive agreement between the measured and predicted runoff hydrographs.

Active Flow Control and Global Stability Analysis of Separated Flow Over a NACA 0012 Airfoil

NASA Astrophysics Data System (ADS)

Munday, Phillip M.

The objective of this computational study is to examine and quantify the influence of fundamental flow control inputs in suppressing flow separation over a canonical airfoil. Most flow control studies to this date have relied on the development of actuator technology, and described the control input based on specific actuators. Taking advantage of a computational framework, we generalize the inputs to fundamental perturbations without restricting inputs to a particular actuator. Utilizing this viewpoint, generalized control inputs aim to aid in the quantification and support the design of separation control techniques. This study in particular independently introduces wall-normal momentum and angular momentum to the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. By closely studying different variables, the influence of the wall-normal and angular momentum injections on separated flow is identified. As an example, open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at alpha = 6° and 9° with Re = 23,000 is examined with large-eddy simulations. For the shallow angle of attack alpha = 6°, the small recirculation region is primarily affected by wall-normal momentum injection. For a larger separation region at alpha = 9°, it is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Reducing the size of the separated flow region significantly impacts the forces, and in particular reduces drag and increases lift on the airfoil. It was found that the influence of flow control on the small recirculation region (alpha = 6°) can be sufficiently quantified with the traditional coefficient of momentum. At alpha = 9°, the effects of wall-normal and angular momentum inputs are captured by modifying the standard definition of the coefficient of momentum, which successfully characterizes suppression of separation and lift enhancement. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With the modified coefficient of momentum, this single value is able to categorize controlled flows into separated, transitional, and attached flows. With inadequate control input (separated flow regime), lift decreased compared to the baseline flow. Increasing the modified coefficient of momentum, flow transitions from separated to attached and accordingly results in improved aerodynamic forces. Modifying the spanwise spacing, it is shown that the minimum modified coefficient of momentum input required to begin transitioning the flow is dependent on actuator spacing. The growth (or decay) of perturbations can facilitate or inhibit the influence of flow control inputs. Biglobal stability analysis is considered to further analyze the behavior of control inputs on separated flow over a symmetric airfoil. Assuming a spanwise periodic waveform for the perturbations, the eigenvalues and eigenvectors about a base flow are solved to understand the influence of spanwise variation on the development of the flow. Two algorithms are developed and validated to solve for the eigenvalues of the flow: an algebraic eigenvalue solver (matrix based) and a time-stepping algorithm. The matrix based approach is formulated without ever storing the matrices, creating a computationally memory efficient algorithm. Increasing the Reynolds number to Re = 23,000 over a NACA 0012 airfoil, the time-stepper method is implemented due to rising computational cost of the matrix-based method. Stability analysis about the time-averaged flow is performed for spanwise wavenumbers of beta = 1/c, 10pi/ c and 20pi/c, which the latter two wavenumbers are representative of the spanwise spacing between the actuators. The largest spanwise wavelength (beta = 1/c) contained unstable modes that ranged from low to high frequency, and a particular unstable low-frequency mode corresponding to a frequency observed in the lift forces of the baseline large-eddy simulation. For the larger spanwise wavenumbers, beta = 10pi/ c (Lz/c = 0.2) and 20pi/c (Lz/c = 0.1), low-frequency modes were damped and only modes with f > 5were unstable. These results help us gain further insight into the influence of the flow control inputs. In conclusion, it was shown that the influence of wall-normal and angular momentum inputs on fully separated flow can adequately be described by the modified coefficient of momentum. Through further analysis and the development of a biglobal stability solver, spanwise spacing effects observed in the flow control study can be explained. The findings from this study should aid in the development of more intelligently designed flow control strategies and provide guidance in the selection of flow control actuators.

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 3. Generator routines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.; Argo, R.S.

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. The various input parameters required in the analysis are compiled in data systems. The data are organized and preparedmore » by various input subroutines for utilization by the hydraulic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System, a storage and retrieval system for model input and output data, including graphical interpretation and display is described. This is the third of four volumes of the description of the CIRMIS Data System.« less

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 1. Initialization, operation, and documentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. The various input parameters required in the analysis are compiled in data systems. The data are organized and preparedmore » by various input subroutines for use by the hydrologic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System, a storage and retrieval system for model input and output data, including graphical interpretation and display is described. This is the first of four volumes of the description of the CIRMIS Data System.« less

Peak expiratory flow profiles delivered by pump systems. Limitations due to wave action.

PubMed

Miller, M R; Jones, B; Xu, Y; Pedersen, O F; Quanjer, P H

2000-06-01

Pump systems are currently used to test the performance of both spirometers and peak expiratory flow (PEF) meters, but for certain flow profiles the input signal (i.e., requested profile) and the output profile can differ. We developed a mathematical model of wave action within a pump and compared the recorded flow profiles with both the input profiles and the output predicted by the model. Three American Thoracic Society (ATS) flow profiles and four artificial flow-versus-time profiles were delivered by a pump, first to a pneumotachograph (PT) on its own, then to the PT with a 32-cm upstream extension tube (which would favor wave action), and lastly with the PT in series with and immediately downstream to a mini-Wright peak flow meter. With the PT on its own, recorded flow for the seven profiles was 2.4 +/- 1.9% (mean +/- SD) higher than the pump's input flow, and similarly was 2.3 +/- 2.3% higher than the pump's output flow as predicted by the model. With the extension tube in place, the recorded flow was 6.6 +/- 6.4% higher than the input flow (range: 0.1 to 18.4%), but was only 1.2 +/- 2.5% higher than the output flow predicted by the model (range: -0.8 to 5.2%). With the mini-Wright meter in series, the flow recorded by the PT was on average 6.1 +/- 9.1% below the input flow (range: -23.8 to 2. 5%), but was only 0.6 +/- 3.3% above the pump's output flow predicted by the model (range: -5.5 to 3.9%). The mini-Wright meter's reading (corrected for its nonlinearity) was on average 1.3 +/- 3.6% below the model's predicted output flow (range: -9.0 to 1. 5%). The mini-Wright meter would be deemed outside ATS limits for accuracy for three of the seven profiles when compared with the pump's input PEF, but this would be true for only one profile when compared with the pump's output PEF as predicted by the model. Our study shows that the output flow from pump systems can differ from the input waveform depending on the operating configuration. This effect can be predicted with reasonable accuracy using a model based on nonsteady flow analysis that takes account of pressure wave reflections within pump systems.

STEADY-STATE DESIGN OF VERTICAL WELLS FOR LIQUIDS ADDITION AT BIOREACTOR LANDFILLS

EPA Science Inventory

This paper presents design charts that a landfill engineer can use for the design of a vertical well system for liquids addition at bioreactor landfills. The flow rate and lateral and vertical zones of impact of a vertical well were estimated as a function of input variables su...

10 CFR 431.192 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

..., and which has a rated primary voltage between 601 V and 34.5 kV. No-load loss means those losses that... no-load loss, 55 °C for load loss of liquid-immersed distribution transformers at 50 percent load... input. Excitation current or no-load current means the current that flows in any winding used to excite...

10 CFR 431.192 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., and which has a rated primary voltage between 601 V and 34.5 kV. No-load loss means those losses that... no-load loss, 55 °C for load loss of liquid-immersed distribution transformers at 50 percent load... input. Excitation current or no-load current means the current that flows in any winding used to excite...

10 CFR 431.192 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., and which has a rated primary voltage between 601 V and 34.5 kV. No-load loss means those losses that... no-load loss, 55 °C for load loss of liquid-immersed distribution transformers at 50 percent load... input. Excitation current or no-load current means the current that flows in any winding used to excite...

10 CFR 431.192 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

..., and which has a rated primary voltage between 601 V and 34.5 kV. No-load loss means those losses that... no-load loss, 55 °C for load loss of liquid-immersed distribution transformers at 50 percent load... input. Excitation current or no-load current means the current that flows in any winding used to excite...

Evaluation of Water Year 2011 Glen Canyon Dam Flow Release Scenarios on Downstream Sand Storage along the Colorado River in Arizona

USGS Publications Warehouse

Wright, Scott A.; Grams, Paul E.

2010-01-01

This report describes numerical modeling simulations of sand transport and sand budgets for reaches of the Colorado River below Glen Canyon Dam. Two hypothetical Water Year 2011 annual release volumes were each evaluated with six hypothetical operational scenarios. The six operational scenarios include the current operation, scenarios with modifications to the monthly distribution of releases, and scenarios with modifications to daily flow fluctuations. Uncertainties in model predictions were evaluated by conducting simulations with error estimates for tributary inputs and mainstem transport rates. The modeling results illustrate the dependence of sand transport rates and sand budgets on the annual release volumes as well as the within year operating rules. The six operational scenarios were ranked with respect to the predicted annual sand budgets for Marble Canyon and eastern Grand Canyon reaches. While the actual WY 2011 annual release volume and levels of tributary inputs are unknown, the hypothetical conditions simulated and reported herein provide reasonable comparisons between the operational scenarios, in a relative sense, that may be used by decision makers within the Glen Canyon Dam Adaptive Management Program.

[Cointegration test and variance decomposition for the relationship between economy and environment based on material flow analysis in Tangshan City Hebei China].

PubMed

2015-12-01

The material flow account of Tangshan City was established by material flow analysis (MFA) method to analyze the periodical characteristics of material input and output in the operation of economy-environment system, and the impact of material input and output intensities on economic development. Using econometric model, the long-term interaction mechanism and relationship among the indexes of gross domestic product (GDP) , direct material input (DMI), domestic processed output (DPO) were investigated after unit root hypothesis test, Johansen cointegration test, vector error correction model, impulse response function and variance decomposition. The results showed that during 1992-2011, DMI and DPO both increased, and the growth rate of DMI was higher than that of DPO. The input intensity of DMI increased, while the intensity of DPO fell in volatility. Long-term stable cointegration relationship existed between GDP, DMI and DPO. Their interaction relationship showed a trend from fluctuation to gradual ste adiness. DMI and DPO had strong, positive impacts on economic development in short-term, but the economy-environment system gradually weakened these effects by short-term dynamically adjusting indicators inside and outside of the system. Ultimately, the system showed a long-term equilibrium relationship. The effect of economic scale on economy was gradually increasing. After decomposing the contribution of each index to GDP, it was found that DMI's contribution grew, GDP's contribution declined, DPO's contribution changed little. On the whole, the economic development of Tangshan City has followed the traditional production path of resource-based city, mostly depending on the material input which caused high energy consumption and serous environmental pollution.

Understanding virtual water flows: A multiregion input-output case study of Victoria

NASA Astrophysics Data System (ADS)

Lenzen, Manfred

2009-09-01

This article explains and interprets virtual water flows from the well-established perspective of input-output analysis. Using a case study of the Australian state of Victoria, it demonstrates that input-output analysis can enumerate virtual water flows without systematic and unknown truncation errors, an issue which has been largely absent from the virtual water literature. Whereas a simplified flow analysis from a producer perspective would portray Victoria as a net virtual water importer, enumerating the water embodiments across the full supply chain using input-output analysis shows Victoria as a significant net virtual water exporter. This study has succeeded in informing government policy in Australia, which is an encouraging sign that input-output analysis will be able to contribute much value to other national and international applications.

Refinement and evaluation of the Massachusetts firm-yield estimator model version 2.0

USGS Publications Warehouse

Levin, Sara B.; Archfield, Stacey A.; Massey, Andrew J.

2011-01-01

The firm yield is the maximum average daily withdrawal that can be extracted from a reservoir without risk of failure during an extended drought period. Previously developed procedures for determining the firm yield of a reservoir were refined and applied to 38 reservoir systems in Massachusetts, including 25 single- and multiple-reservoir systems that were examined during previous studies and 13 additional reservoir systems. Changes to the firm-yield model include refinements to the simulation methods and input data, as well as the addition of several scenario-testing capabilities. The simulation procedure was adapted to run at a daily time step over a 44-year simulation period, and daily streamflow and meteorological data were compiled for all the reservoirs for input to the model. Another change to the model-simulation methods is the adjustment of the scaling factor used in estimating groundwater contributions to the reservoir. The scaling factor is used to convert the daily groundwater-flow rate into a volume by multiplying the rate by the length of reservoir shoreline that is hydrologically connected to the aquifer. Previous firm-yield analyses used a constant scaling factor that was estimated from the reservoir surface area at full pool. The use of a constant scaling factor caused groundwater flows during periods when the reservoir stage was very low to be overestimated. The constant groundwater scaling factor used in previous analyses was replaced with a variable scaling factor that is based on daily reservoir stage. This change reduced instability in the groundwater-flow algorithms and produced more realistic groundwater-flow contributions during periods of low storage. Uncertainty in the firm-yield model arises from many sources, including errors in input data. The sensitivity of the model to uncertainty in streamflow input data and uncertainty in the stage-storage relation was examined. A series of Monte Carlo simulations were performed on 22 reservoirs to assess the sensitivity of firm-yield estimates to errors in daily-streamflow input data. Results of the Monte Carlo simulations indicate that underestimation in the lowest stream inflows can cause firm yields to be underestimated by an average of 1 to 10 percent. Errors in the stage-storage relation can arise when the point density of bathymetric survey measurements is too low. Existing bathymetric surfaces were resampled using hypothetical transects of varying patterns and point densities in order to quantify the uncertainty in stage-storage relations. Reservoir-volume calculations and resulting firm yields were accurate to within 5 percent when point densities were greater than 20 points per acre of reservoir surface. Methods for incorporating summer water-demand-reduction scenarios into the firm-yield model were developed as well as the ability to relax the no-fail reliability criterion. Although the original firm-yield model allowed monthly reservoir releases to be specified, there have been no previous studies examining the feasibility of controlled releases for downstream flows from Massachusetts reservoirs. Two controlled-release scenarios were tested—with and without a summer water-demand-reduction scenario—for a scenario with a no-fail criterion and a scenario that allows for a 1-percent failure rate over the entire simulation period. Based on these scenarios, about one-third of the reservoir systems were able to support the flow-release scenarios at their 2000–2004 usage rates. Reservoirs with higher storage ratios (reservoir storage capacity to mean annual streamflow) and lower demand ratios (mean annual water demand to annual firm yield) were capable of higher downstream release rates. For the purposes of this research, all reservoir systems were assumed to have structures which enable controlled releases, although this assumption may not be true for many of the reservoirs studied.

A mixed-unit input-output model for environmental life-cycle assessment and material flow analysis.

PubMed

Hawkins, Troy; Hendrickson, Chris; Higgins, Cortney; Matthews, H Scott; Suh, Sangwon

2007-02-01

Materials flow analysis models have traditionally been used to track the production, use, and consumption of materials. Economic input-output modeling has been used for environmental systems analysis, with a primary benefit being the capability to estimate direct and indirect economic and environmental impacts across the entire supply chain of production in an economy. We combine these two types of models to create a mixed-unit input-output model that is able to bettertrack economic transactions and material flows throughout the economy associated with changes in production. A 13 by 13 economic input-output direct requirements matrix developed by the U.S. Bureau of Economic Analysis is augmented with material flow data derived from those published by the U.S. Geological Survey in the formulation of illustrative mixed-unit input-output models for lead and cadmium. The resulting model provides the capabilities of both material flow and input-output models, with detailed material tracking through entire supply chains in response to any monetary or material demand. Examples of these models are provided along with a discussion of uncertainty and extensions to these models.

Effects of uncertainties in hydrological modelling. A case study of a mountainous catchment in Southern Norway

NASA Astrophysics Data System (ADS)

Engeland, Kolbjørn; Steinsland, Ingelin; Johansen, Stian Solvang; Petersen-Øverleir, Asgeir; Kolberg, Sjur

2016-05-01

In this study, we explore the effect of uncertainty and poor observation quality on hydrological model calibration and predictions. The Osali catchment in Western Norway was selected as case study and an elevation distributed HBV-model was used. We systematically evaluated the effect of accounting for uncertainty in parameters, precipitation input, temperature input and streamflow observations. For precipitation and temperature we accounted for the interpolation uncertainty, and for streamflow we accounted for rating curve uncertainty. Further, the effects of poorer quality of precipitation input and streamflow observations were explored. Less information about precipitation was obtained by excluding the nearest precipitation station from the analysis, while reduced information about the streamflow was obtained by omitting the highest and lowest streamflow observations when estimating the rating curve. The results showed that including uncertainty in the precipitation and temperature inputs has a negligible effect on the posterior distribution of parameters and for the Nash-Sutcliffe (NS) efficiency for the predicted flows, while the reliability and the continuous rank probability score (CRPS) improves. Less information in precipitation input resulted in a shift in the water balance parameter Pcorr, a model producing smoother streamflow predictions, giving poorer NS and CRPS, but higher reliability. The effect of calibrating the hydrological model using streamflow observations based on different rating curves is mainly seen as variability in the water balance parameter Pcorr. When evaluating predictions, the best evaluation scores were not achieved for the rating curve used for calibration, but for rating curves giving smoother streamflow observations. Less information in streamflow influenced the water balance parameter Pcorr, and increased the spread in evaluation scores by giving both better and worse scores.

Sources of nitrogen and phosphorous to northern San Francisco Bay

USGS Publications Warehouse

Hager, Stephen W.; Schemel, Laurence E.

1992-01-01

We studied nutrient sources to the Sacramento River and Suisun Bay (northern San Francisco Bay) and the influence which these sources have on the distributions of dissolved inorganic nitrogen (DIN) and dissolved reactive phosphorus (DRP) in the river and bay. We found that agricultural return flow drains and a municipal wastewater treatment plant were the largest sources of nutrients to the river during low river flow. The Sutter and Colusa agricultural drains contributed about 70% of the transport of DIN and DRP by the river above Sacramento (about 20% of the total transport by the river) between August 8 and September 26, 1985. Further downstream, the Sacramento Regional Wastewater Treatment Plant discharged DIN and DRP at rates that were roughly 70% of total DIN and DRP transport by the river at that time. Concentrations at Rio Vista on the tidal river below the Sacramento plant and at the head of the estuary were related to the reciprocals of the river flows, indicating the importance of dilution of the Sacramento waste by river flows. During very dry years, elevated DIN and DRP concentrations were observed in Suisun Bay. We used a steady-state, one-dimensional, single-compartment box model of the bay, incorporating terms for advection, exchange, and waste input, to calculate a residual rate for all processes not included in the model. We found that the residual for DIN was related to concentrations of chlorophylla (Chla). The residual for DRP was also related to Chla at high concentrations of Chla, but showed significant losses of DRP at low Chla concentrations. These losses were typically equivalent to about 80% of the wastewater input rate.

Salinity-gradient energy driven microbial electrosynthesis of hydrogen peroxide

NASA Astrophysics Data System (ADS)

Li, Xiaohu; Angelidaki, Irini; Zhang, Yifeng

2017-02-01

Hydrogen peroxide (H2O2) as a strong oxidant, is widely used in various chemical industries and environmental remediation processes. In this study, we developed an innovative method for cost-effective production of H2O2 by using a microbial reverse-electrodialysis electrolysis cell (MREC). In the MREC, electrical potential generated by the exoelectrogens and the salinity-gradient between salt and fresh water were utilized to drive the high-rate H2O2 production. Operational parameters such as air flow rate, pH, cathodic potential, flow rate of salt and fresh water were investigated. The optimal H2O2 production was observed at salt and fresh water flow rate of 0.5 mL min-1, air flow rate of 12-20 mL min-1, cathode potential of -0.485 ± 0.025 V (vs Ag/AgCl). The maximum H2O2 accumulated concentration of 778 ± 11 mg L-1 was obtained at corresponding production rate of 11.5 ± 0.5 mg L-1 h-1. The overall energy input for the synthesis process was 0.45 ± 0.03 kWh kg-1 H2O2. Cathode potential was the key factor for H2O2 production, which was mainly affected by the air flow rate. This work for the first time proved the potential of MREC as an efficient platform technology for simultaneous electrosynthesis of valuable chemicals and utilization of salinity-gradient energy.

Evaluating the Mn/Ca Ratio of Foraminiferal Calcite Determined by Flow-Through ICP-MS as a Proxy for Terrigenous Input, Upwelling, and Carbon Rain Rate

NASA Astrophysics Data System (ADS)

Klinkhammer, G. P.; Mix, A. C.; Benway, H. M.; Haley, B. A.

2004-12-01

The Mn/Ca ratio of the biogenic calcite preserved in deep-sea sediments has potential as a tracer of terrestrial input, upwelling, and carbon rain rate over geologic time scales. The basis for this potential lies in features of the Mn cycle in the oceans, which are well known. Manganese is a biogeochemically reactive element, but has a lower affinity for dissolved oxygen and organic matter than iron, making it more stable over short time scales, and less affected by speciation. Depth profiles of Mn in oligotrophic ocean waters show a sharp contrast between low concentrations in deep water (0.20 nM) and relatively high concentrations in the mixed layer (2-5 nM). Mn oxides are stable in high oxygen environments but reduced in the suboxic conditions found in the oxygen minimum zone (OMZ). This behavior makes the intermediate water to surface water concentration ratio of Mn sensitive to the intensity of the OMZ, an artifact of the carbon rain rate, and dust/river input. In sediments, suboxic dissolution is balanced by the formation of carbonate making Mn highly reactive during early diagenesis. These features of the Mn cycle in seawater make the Mn/Ca ratio of foraminifera an attractive paleoproxy, but only if the primary signature can be recovered after diagenetic alteration. Recently our laboratory developed a flow-through extraction system that gives us fresh insight into this problem by making it possible to separate mineral phases associated with the foraminiferal fraction by differences in their solubilities. This paper examines foraminiferal Mn/Ca ratios in core tops and down core records from the eastern equatorial Pacific determined with this new technique. We access the potential of flow-through Mn/Ca by comparing its record to those of Mg/Ca and stable isotopes.

Very high pressure liquid chromatography using fully porous particles: quantitative analysis of fast gradient separations without post-run times.

PubMed

Stankovich, Joseph J; Gritti, Fabrice; Stevenson, Paul G; Beaver, Lois Ann; Guiochon, Georges

2014-01-10

Using a column packed with fully porous particles, four methods for controlling the flow rates at which gradient elution runs are conducted in very high pressure liquid chromatography (VHPLC) were tested to determine whether reproducible thermal conditions could be achieved, such that subsequent analyses would proceed at nearly the same initial temperature. In VHPLC high flow rates are achieved, producing fast analyses but requiring high inlet pressures. The combination of high flow rates and high inlet pressures generates local heat, leading to temperature changes in the column. Usually in this case a post-run time is input into the analytical method to allow the return of the column temperature to its initial state. An alternative strategy involves operating the column without a post-run equilibration period and maintaining constant temperature variations for subsequent analysis after conducting one or a few separations to bring the column to a reproducible starting temperature. A liquid chromatography instrument equipped with a pressure controller was used to perform constant pressure and constant flow rate VHPLC separations. Six replicate gradient separations of a nine component mixture consisting of acetophenone, propiophenone, butyrophenone, valerophenone, hexanophenone, heptanophenone, octanophenone, benzophenone, and acetanilide dissolved in water/acetonitrile (65:35, v/v) were performed under various experimental conditions: constant flow rate, two sets of constant pressure, and constant pressure operation with a programmed flow rate. The relative standard deviations of the response factors for all the analytes are lower than 5% across the methods. Programming the flow rate to maintain a fairly constant pressure instead of using instrument controlled constant pressure improves the reproducibility of the retention times by a factor of 5, when plotting the chromatograms in time. Copyright © 2013 Elsevier B.V. All rights reserved.

Pitot tube calculations with a TI-59

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, K.

Industrial plant and stack analysis dictates that flow measurements in ducts be accurate. This is usually accomplished by running a traverse with a pitot tube across the duct or flue. A traverse is a series of measurements taken at predetermined points across the duct. The values of these measurements are calculated into point flow rates and averaged. A program for the Texas Instruments TI-59 programmable calculator follows. The program will perform calculations for an infinite number of test points, both with the standard (combined impact type) pitot tube and the S-type (combined reverse type). The type of tube is selectedmore » by inputting an indicating valve that triggers a flag in the program. To use the standard pitot tube, a 1 is input into key E. When the S-type is used, a zero is input into key E. The program output will note if the S-type had been used. Since most process systems are not at standard conditions (32/sup 0/F, 1 atm) the program will take this into account.« less

Inert gas thrusters

NASA Technical Reports Server (NTRS)

Kaufman, H. R.; Robinson, R. S.

1979-01-01

Inert gas thrusters considered for space propulsion systems were investigated. Electron diffusion across a magnetic field was examined utilizing a basic model. The production of doubly charged ions was correlated using only overall performance parameters. The use of this correlation is therefore possible in the design stage of large gas thrusters, where detailed plasma properties are not available. Argon hollow cathode performance was investigated over a range of emission currents, with the positions of the inert, keeper, and anode varied. A general trend observed was that the maximum ratio of emission to flow rate increased at higher propellant flow rates. It was also found that an enclosed keeper enhances maximum cathode emission at high flow rates. The maximum cathode emission at a given flow rate was associated with a noisy high voltage mode. Although this mode has some similarities to the plume mode found at low flows and emissions, it is encountered by being initially in the spot mode and increasing emission. A detailed analysis of large, inert-gas thruster performance was carried out. For maximum thruster efficiency, the optimum beam diameter increases from less than a meter at under 2000 sec specific impulse to several meters at 10,000 sec. The corresponding range in input power ranges from several kilowatts to megawatts.

The effect of CNC and manual laser machining on electrical resistance of HDPE/MWCNT composite

NASA Astrophysics Data System (ADS)

Mohammadi, Fatemeh; Farshbaf Zinati, Reza; Fattahi, A. M.

2018-05-01

In this study, electrical conductivity of high-density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) composite was investigated after laser machining. To this end, produced using plastic injection process, nano-composite samples were laser machined with various combinations of input parameters such as feed rate (35, 45, and 55 mm/min), feed angle with injection flow direction (0°, 45°, and 90°), and MWCNT content (0.5, 1, and 1.5 wt%). The angle between laser feed and injected flow direction was set via either of two different methods: CNC programming and manual setting. The results showed that the parameters of angle between laser line and melt flow direction and feed rate were both found to have statistically significance and physical impacts on electrical resistance of the samples in manual setting. Also, maximum conductivity was seen when the angle between laser line and melt flow direction was set to 90° in manual setting, and maximum conductivity was seen at feed rate of 55 mm/min in both of CNC programming and manual setting.

Air-flow regulation system for a coal gasifier

DOEpatents

Fasching, George E.

1984-01-01

An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter. This control arrangement provides at least a factor of 5 improvement in air-flow regulation for a coal gasifier in which air is supplied by a reciprocating compressor through a surge tank.

Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

NASA Astrophysics Data System (ADS)

Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

2009-05-01

Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

The Flow Engine Framework: A Cognitive Model of Optimal Human Experience

PubMed Central

Šimleša, Milija; Guegan, Jérôme; Blanchard, Edouard; Tarpin-Bernard, Franck; Buisine, Stéphanie

2018-01-01

Flow is a well-known concept in the fields of positive and applied psychology. Examination of a large body of flow literature suggests there is a need for a conceptual model rooted in a cognitive approach to explain how this psychological phenomenon works. In this paper, we propose the Flow Engine Framework, a theoretical model explaining dynamic interactions between rearranged flow components and fundamental cognitive processes. Using an IPO framework (Inputs – Processes – Outputs) including a feedback process, we organize flow characteristics into three logically related categories: inputs (requirements for flow), mediating and moderating cognitive processes (attentional and motivational mechanisms) and outputs (subjective and objective outcomes), describing the process of the flow. Comparing flow with an engine, inputs are depicted as flow-fuel, core processes cylinder strokes and outputs as power created to provide motion. PMID:29899807

Rapid oxidation of geothermal arsenic(III) in streamwaters of the eastern Sierra Nevada

USGS Publications Warehouse

Wilkie, J.A.; Hering, J.G.

1998-01-01

Arsenic redox cycling was examined in source waters of the Los Angeles Aqueduct, specifically at Hot Creek, a tributary of the Owens River. Elevated arsenic concentrations in Hot Creek result from geothermal inputs. Total arsenic and As(III) concentrations were determined in the creek and in hot spring pools along its banks. Samples were processed in the field using anion-exchange columns to separate inorganic As(III) and As(V) species. Downstream of the geothermal inputs, decreasing contributions of As(III) to total arsenic concentrations indicated rapid in-stream oxidation of As(III) to As(V) with almost complete oxidation occurring within 1200 m. Based on assumed plug flow transport and a flow velocity of about 0.4 m/s, the pseudo- first-order half-life calculated for this reaction was approximately 0.3 h. Conservative transport of total dissolved arsenic was observed over the reach. Pseudo-first-order reaction rates determined for As(III) oxidation in batch studies conducted in the field with aquatic macrophytes and/or macrophyte surface matter were comparable to the in-stream oxidation rate observed along Hot Creek. In batch kinetic studies, oxidation was not observed after sterile filtration or after the addition of antibiotics, which indicates that bacteria attached to submerged macrophytes are mediating the rapid As(III) oxidation reaction.Arsenic redox cycling was examined in source waters of the Los Angeles Aqueduct, specifically at Hot Creek, a tributary of the Owens River. Elevated arsenic concentrations in Hot Creek result from geothermal inputs. Total arsenic and As(III) concentrations were determined in the creek and in hot spring pools along its banks. Samples were processed in the field using anion-exchange columns to separate inorganic As(III) and As(V) species. Downstream of the geothermal inputs, decreasing contributions of As(III) to total arsenic concentrations indicated rapid in-stream oxidation of As(III) to As(V) with almost complete oxidation occurring within 1200 m. Based on assumed plug flow transport and a flow velocity of about 0.4 m/s, the pseudo-first-order half-life calculated for this reaction was approximately 0.3 h. Conservative transport of total dissolved arsenic was observed over the reach. Pseudo-first-order reaction rates determined for As(III) oxidation in batch studies conducted in the field with aquatic macrophytes and/or macrophyte surface matter were comparable to the in-stream oxidation rate observed along Hot Creek. In batch kinetic studies, oxidation was not observed after sterile filtration or after the addition of antibiotics, which indicates that bacteria attached to submerged macrophytes are mediating the rapid As(III) oxidation reaction.

Modeling of Critically-Stratified Gravity Flows: Application to the Eel River Continental Shelf, Northern California

NASA Astrophysics Data System (ADS)

Scully, Malcolm E.

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Flow distribution in parallel microfluidic networks and its effect on concentration gradient

PubMed Central

Guermonprez, Cyprien; Michelin, Sébastien; Baroud, Charles N.

2015-01-01

The architecture of microfluidic networks can significantly impact the flow distribution within its different branches and thereby influence tracer transport within the network. In this paper, we study the flow rate distribution within a network of parallel microfluidic channels with a single input and single output, using a combination of theoretical modeling and microfluidic experiments. Within the ladder network, the flow rate distribution follows a U-shaped profile, with the highest flow rate occurring in the initial and final branches. The contrast with the central branches is controlled by a single dimensionless parameter, namely, the ratio of hydrodynamic resistance between the distribution channel and the side branches. This contrast in flow rates decreases when the resistance of the side branches increases relative to the resistance of the distribution channel. When the inlet flow is composed of two parallel streams, one of which transporting a diffusing species, a concentration variation is produced within the side branches of the network. The shape of this concentration gradient is fully determined by two dimensionless parameters: the ratio of resistances, which determines the flow rate distribution, and the Péclet number, which characterizes the relative speed of diffusion and advection. Depending on the values of these two control parameters, different distribution profiles can be obtained ranging from a flat profile to a step distribution of solute, with well-distributed gradients between these two limits. Our experimental results are in agreement with our numerical model predictions, based on a simplified 2D advection-diffusion problem. Finally, two possible applications of this work are presented: the first one combines the present design with self-digitization principle to encapsulate the controlled concentration in nanoliter chambers, while the second one extends the present design to create a continuous concentration gradient within an open flow chamber. PMID:26487905

User's Guide for Mixed-Size Sediment Transport Model for Networks of One-Dimensional Open Channels

USGS Publications Warehouse

Bennett, James P.

2001-01-01

This user's guide describes a mathematical model for predicting the transport of mixed sizes of sediment by flow in networks of one-dimensional open channels. The simulation package is useful for general sediment routing problems, prediction of erosion and deposition following dam removal, and scour in channels at road embankment crossings or other artificial structures. The model treats input hydrographs as stepwise steady-state, and the flow computation algorithm automatically switches between sub- and supercritical flow as dictated by channel geometry and discharge. A variety of boundary conditions including weirs and rating curves may be applied both external and internal to the flow network. The model may be used to compute flow around islands and through multiple openings in embankments, but the network must be 'simple' in the sense that the flow directions in all channels can be specified before simulation commences. The location and shape of channel banks are user specified, and all bedelevation changes take place between these banks and above a user-specified bedrock elevation. Computation of sediment-transport emphasizes the sand-size range (0.0625-2.0 millimeter) but the user may select any desired range of particle diameters including silt and finer (<0.0625 millimeter). As part of data input, the user may set the original bed-sediment composition of any number of layers of known thickness. The model computes the time evolution of total transport and the size composition of bed- and suspended-load sand through any cross section of interest. It also tracks bed -surface elevation and size composition. The model is written in the FORTRAN programming language for implementation on personal computers using the WINDOWS operating system and, along with certain graphical output display capability, is accessed from a graphical user interface (GUI). The GUI provides a framework for selecting input files and parameters of a number of components of the sediment-transport process. There are no restrictions in the use of the model as to numbers of channels, channel junctions, cross sections per channel, or points defining the cross sections. Following completion of the simulation computations, the GUI accommodates display of longitudinal plots of either bed elevation and size composition, or of transport rate and size composition of the various components, for individual channels and selected times during the simulation period. For individual cross sections, the GUI also allows display of time series of transport rate and size composition of the various components and of bed elevation and size composition.

Effect of Energy Input on the Characteristic of AISI H13 and D2 Tool Steels Deposited by a Directed Energy Deposition Process

NASA Astrophysics Data System (ADS)

Park, Jun Seok; Park, Joo Hyun; Lee, Min-Gyu; Sung, Ji Hyun; Cha, Kyoung Je; Kim, Da Hye

2016-05-01

Among the many additive manufacturing technologies, the directed energy deposition (DED) process has attracted significant attention because of the application of metal products. Metal deposited by the DED process has different properties than wrought metal because of the rapid solidification rate, the high thermal gradient between the deposited metal and substrate, etc. Additionally, many operating parameters, such as laser power, beam diameter, traverse speed, and powder mass flow rate, must be considered since the characteristics of the deposited metal are affected by the operating parameters. In the present study, the effect of energy input on the characteristics of H13 and D2 steels deposited by a direct metal tooling process based on the DED process was investigated. In particular, we report that the hardness of the deposited H13 and D2 steels decreased with increasing energy input, which we discuss by considering microstructural observations and thermodynamics.

Thermodynamic Modeling of a Solid Oxide Fuel Cell to Couple with an Existing Gas Turbine Engine Model

NASA Technical Reports Server (NTRS)

Brinson, Thomas E.; Kopasakis, George

2004-01-01

The Controls and Dynamics Technology Branch at NASA Glenn Research Center are interested in combining a solid oxide fuel cell (SOFC) to operate in conjunction with a gas turbine engine. A detailed engine model currently exists in the Matlab/Simulink environment. The idea is to incorporate a SOFC model within the turbine engine simulation and observe the hybrid system's performance. The fuel cell will be heated to its appropriate operating condition by the engine s combustor. Once the fuel cell is operating at its steady-state temperature, the gas burner will back down slowly until the engine is fully operating on the hot gases exhausted from the SOFC. The SOFC code is based on a steady-state model developed by The U.S. Department of Energy (DOE). In its current form, the DOE SOFC model exists in Microsoft Excel and uses Visual Basics to create an I-V (current-voltage) profile. For the project's application, the main issue with this model is that the gas path flow and fuel flow temperatures are used as input parameters instead of outputs. The objective is to create a SOFC model based on the DOE model that inputs the fuel cells flow rates and outputs temperature of the flow streams; therefore, creating a temperature profile as a function of fuel flow rate. This will be done by applying the First Law of Thermodynamics for a flow system to the fuel cell. Validation of this model will be done in two procedures. First, for a given flow rate the exit stream temperature will be calculated and compared to DOE SOFC temperature as a point comparison. Next, an I-V curve and temperature curve will be generated where the I-V curve will be compared with the DOE SOFC I-V curve. Matching I-V curves will suggest validation of the temperature curve because voltage is a function of temperature. Once the temperature profile is created and validated, the model will then be placed into the turbine engine simulation for system analysis.

Effect of human activities on overall trend of sedimentation in the lower Yellow River, China.

PubMed

Jiongxin, Xu

2004-05-01

The Yellow River has been intensively affected by human activities, particularly in the past 50 years, including soil-water conservation in the upper and middle drainage basin, flood protection in the lower reaches, and flow regulation and water diversion in the whole drainage basin. All these changes may impact sedimentation process of the lower Yellow River in different ways. Assessing these impacts comprehensively is important for more effective environmental management of the drainage basin. Based on the data of annual river flow, sediment load, and channel sedimentation in the lower Yellow River between 1950 and 1997, the purpose of this paper is to analyze the overall trend of channel sedimentation rate at a time scale of 50 years, and its formative cause. It was found in this study that erosion control measures and water diversion have counteractive impacts on sedimentation rate in the lower Yellow River. Although both annual river flow and sediment decreased, there was no change in channel sedimentation rate. A regression analysis indicated that the sedimentation in the lower Yellow River decreased with the sediment input to the lower Yellow River but increased with the river flow input. In the past 30-40 years, the basin-wide practice of erosion and sediment control measures resulted in a decline in sediment supply to the Yellow River; at the same time, the human development of water resources that required river flow regulation and water diversion caused great reduction in river flow. The former may reduce the sedimentation in the lower Yellow River, but the reduction of river flow increased the sedimentation. When their effects counterbalanced each other, the overall trend of channel sedimentation in the lower Yellow River remained unchanged. This fact may help us to better understand the positive and negative effects of human activities in the Yellow River basin and to pay more attention to the negative effect of the development of water resources. The results of this study demonstrate that, if the overuse of river water cannot be controlled, the reduction of channel sedimentation in the lower Yellow River cannot be realized through the practice of erosion and sediment control measures.

A note on scrap in the 1992 U.S. input-output tables

USGS Publications Warehouse

Swisko, George M.

2000-01-01

Introduction A key concern of industrial ecology and life cycle analysis is the disposal and recycling of scrap. One might conclude that the U.S. input-output tables are appropriate tools for analyzing scrap flows. Duchin, for instance, has suggested using input-output analysis for industrial ecology, indicating that input-output economics can trace the stocks and flows of energy and other materials from extraction through production and consumption to recycling or disposal. Lave and others use input-output tables to design life cycle assessment models for studying product design, materials use, and recycling strategies, even with the knowledge that these tables suffer from a lack of comprehensive and detailed data that may never be resolved. Although input-output tables can offer general guidance about the interdependence of economic and environmental processes, data reporting by industry and the economic concepts underlying these tables pose problems for rigorous material flow examinations. This is especially true for analyzing the output of scrap and scrap flows in the United States and estimating the amount of scrap that can be recycled. To show how data reporting has affected the values of scrap in recent input-output tables, this paper focuses on metal scrap generated in manufacturing. The paper also briefly discusses scrap that is not included in the input-output tables and some economic concepts that limit the analysis of scrap flows.

A geometry package for generation of input data for a three-dimensional potential-flow program

NASA Technical Reports Server (NTRS)

Halsey, N. D.; Hess, J. L.

1978-01-01

The preparation of geometric data for input to three-dimensional potential flow programs was automated and simplified by a geometry package incorporated into the NASA Langley version of the 3-D lifting potential flow program. Input to the computer program for the geometry package consists of a very sparse set of coordinate data, often with an order of magnitude of fewer points than required for the actual potential flow calculations. Isolated components, such as wings, fuselages, etc. are paneled automatically, using one of several possible element distribution algorithms. Curves of intersection between components are calculated, using a hybrid curve-fit/surface-fit approach. Intersecting components are repaneled so that adjacent elements on either side of the intersection curves line up in a satisfactory manner for the potential-flow calculations. Many cases may be run completely (from input, through the geometry package, and through the flow calculations) without interruption. Use of the package significantly reduces the time and expense involved in making three-dimensional potential flow calculations.

Energy efficient continuous flow ash lockhopper

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr. (Inventor); Suitor, Jerry W. (Inventor); Dubis, David (Inventor)

1989-01-01

The invention relates to an energy efficient continuous flow ash lockhopper, or other lockhopper for reactor product or byproduct. The invention includes an ash hopper at the outlet of a high temperature, high pressure reactor vessel containing heated high pressure gas, a fluidics control chamber having an input port connected to the ash hopper's output port and an output port connected to the input port of a pressure letdown means, and a control fluid supply for regulating the pressure in the control chamber to be equal to or greater than the internal gas pressure of the reactor vessel, whereby the reactor gas is contained while ash is permitted to continuously flow from the ash hopper's output port, impelled by gravity. The main novelty resides in the use of a control chamber to so control pressure under the lockhopper that gases will not exit from the reactor vessel, and to also regulate the ash flow rate. There is also novelty in the design of the ash lockhopper shown in two figures. The novelty there is the use of annular passages of progressively greater diameter, and rotating the center parts on a shaft, with the center part of each slightly offset from adjacent ones to better assure ash flow through the opening.

File-Based Data Flow in the CMS Filter Farm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andre, J.M.; et al.

2015-12-23

During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes aremore » also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.« less

Test-Retest Repeatability of Myocardial Blood Flow Measurements using Rubidium-82 Positron Emission Tomography

NASA Astrophysics Data System (ADS)

Efseaff, Matthew

Rubidium-82 positron emission tomography (PET) imaging has been proposed for routine myocardial blood flow (MBF) quantification. Few studies have investigated the test-retest repeatability of this method. Same-day repeatability of rest MBF imaging was optimized with a highly automated analysis program using image-derived input functions and a dual spillover correction (SOC). The effects of heterogeneous tracer infusion profiles and subject hemodynamics on test-retest repeatability were investigated at rest and during hyperemic stress. Factors affecting rest MBF repeatability included gender, suspected coronary artery disease, and dual SOC (p < 0.001). The best repeatability coefficient for same-day rest MBF was 0.20 mL/min/g using a six-minute scan-time, iterative reconstruction, dual SOC, resting rate-pressure-product (RPP) adjustment, and a left atrium image-derived input function. The serial study repeatabilities of the optimized protocol in subjects with homogeneous RPPs and tracer infusion profiles was 0.19 and 0.53 mL/min/g at rest and stress, and 0.95 for stress / rest myocardial flow reserve (MFR). Subjects with heterogeneous tracer infusion profiles and hemodynamic conditions had significantly less repeatable MBF measurements at rest, stress, and stress/rest flow reserve (p < 0.05).

Initial testing of a 3D printed perfusion phantom using digital subtraction angiography

NASA Astrophysics Data System (ADS)

Wood, Rachel P.; Khobragade, Parag; Ying, Leslie; Snyder, Kenneth; Wack, David; Bednarek, Daniel R.; Rudin, Stephen; Ionita, Ciprian N.

2015-03-01

Perfusion imaging is the most applied modality for the assessment of acute stroke. Parameters such as Cerebral Blood Flow (CBF), Cerebral Blood volume (CBV) and Mean Transit Time (MTT) are used to distinguish the tissue infarct core and ischemic penumbra. Due to lack of standardization these parameters vary significantly between vendors and software even when provided with the same data set. There is a critical need to standardize the systems and make them more reliable. We have designed a uniform phantom to test and verify the perfusion systems. We implemented a flow loop with different flow rates (250, 300, 350 ml/min) and injected the same amount of contrast. The images of the phantom were acquired using a Digital Angiographic system. Since this phantom is uniform, projection images obtained using DSA is sufficient for initial validation. To validate the phantom we measured the contrast concentration at three regions of interest (arterial input, venous output, perfused area) and derived time density curves (TDC). We then calculated the maximum slope, area under the TDCs and flow. The maximum slope calculations were linearly increasing with increase in flow rate, the area under the curve decreases with increase in flow rate. There was 25% error between the calculated flow and measured flow. The derived TDCs were clinically relevant and the calculated flow, maximum slope and areas under the curve were sensitive to the measured flow. We have created a systematic way to calibrate existing perfusion systems and assess their reliability.

Continuous extraction of organic materials from water

USGS Publications Warehouse

Goldberg, M.C.; DeLong, L.; Kahn, L.

1971-01-01

A continuous liquid solvent extractor, designed to utilize organic solvents that are heavier than water, is described. The extractor is capable of handling input rates up to 2 liters per hour and has a 500-ml. extractant capacity. Extraction efficiency is dependent upon the p-value, the two solvent ratios, rate of flow of the aqueous phase, and rate of reflux of the organic phase. Extractors can be serially coupled to increase extraction efficiency and, when coupled with a lighter-than-water extractor, the system will allow the use of any immiscible solvent.

Paper recycling framework, the "Wheel of Fiber".

PubMed

Ervasti, Ilpo; Miranda, Ruben; Kauranen, Ilkka

2016-06-01

At present, there is no reliable method in use that unequivocally describes paper industry material flows and makes it possible to compare geographical regions with each other. A functioning paper industry Material Flow Account (MFA) that uses uniform terminology and standard definitions for terms and structures is necessary. Many of the presently used general level MFAs, which are called frameworks in this article, stress the importance of input and output flows but do not provide a uniform picture of material recycling. Paper industry is an example of a field in which recycling plays a key role. Additionally, terms related to paper industry recycling, such as collection rate, recycling rate, and utilization rate, are not defined uniformly across regions and time. Thus, reliably comparing material recycling activity between geographical regions or calculating any regional summaries is difficult or even impossible. The objective of this study is to give a partial solution to the problem of not having a reliable method in use that unequivocally describes paper industry material flows. This is done by introducing a new material flow framework for paper industry in which the flow and stage structure supports the use of uniform definitions for terms related to paper recycling. This new framework is termed the Detailed Wheel of Fiber. Copyright © 2016 Elsevier Ltd. All rights reserved.

A vectorized code for calculating laminar and turbulent hypersonic flows about blunt axisymmetric bodies at zero and small angles of attack

NASA Technical Reports Server (NTRS)

Kumar, A.; Graves, R. A., Jr.

1980-01-01

A user's guide is provided for a computer code which calculates the laminar and turbulent hypersonic flows about blunt axisymmetric bodies, such as spherically blunted cones, hyperboloids, etc., at zero and small angles of attack. The code is written in STAR FORTRAN language for the CDC-STAR-100 computer. Time-dependent, viscous-shock-layer-type equations are used to describe the flow field. These equations are solved by an explicit, two-step, time asymptotic, finite-difference method. For the turbulent flow, a two-layer, eddy-viscosity model is used. The code provides complete flow-field properties including shock location, surface pressure distribution, surface heating rates, and skin-friction coefficients. This report contains descriptions of the input and output, the listing of the program, and a sample flow-field solution.

Electromagnetically-Actuated Reciprocating Pump for High-Flow-Rate Microfluidic Applications

PubMed Central

Ke, Ming-Tsun; Zhong, Jian-Hao; Lee, Chia-Yen

2012-01-01

This study presents an electromagnetically-actuated reciprocating pump for high-flow-rate microfluidic applications. The pump comprises four major components, namely a lower glass plate containing a copper microcoil, a middle PMMA plate incorporating a PDMS diaphragm with a surface-mounted magnet, upper PMMA channel plates, and a ball-type check valve located at the channel inlet. When an AC current is passed through the microcoil, an alternating electromagnetic force is established between the coil and the magnet. The resulting bi-directional deflection of the PDMS diaphragm causes the check-valve to open and close; thereby creating a pumping effect. The experimental results show that a coil input current of 0.4 A generates an electromagnetic force of 47 mN and a diaphragm deflection of 108 μm. Given an actuating voltage of 3 V and a driving frequency of 15 Hz, the flow rate is found to be 13.2 mL/min under zero head pressure conditions. PMID:23201986

St. Lawrence River Freeze-Up Forecast Procedure.

ERIC Educational Resources Information Center

Assel, R. A.

A standard operating procedure (SOP) is presented for calculating the date of freeze-up on the St. Lawrence River at Massena, N.Y. The SOP is based on two empirical temperature decline equations developed for Kingston, Ontario, and Massena, N.Y., respectively. Input data needed to forecast freeze-up consist of the forecast December flow rate and…

Interbasin groundwater flow and groundwater interaction with surface water in a lowland rainforest, Costa Rica: A review

NASA Astrophysics Data System (ADS)

Genereux, David P.; Jordan, Michael

2006-04-01

This paper reviews work related to interbasin groundwater flow (naturally occurring groundwater flow beneath watershed topographic divides) into lowland rainforest watersheds at La Selva Biological Station in Costa Rica. Chemical mixing calculations (based on dissolved chloride) have shown that up to half the water in some streams and up to 84% of the water in some riparian seeps and wells is due to high-solute interbasin groundwater flow (IGF). The contribution is even greater for major ions; IGF accounts for well over 90% of the major ions at these sites. Proportions are highly variable both among watersheds and with elevation within the same watershed (there is greater influence of IGF at lower elevations). The large proportion of IGF found in water in some riparian wetlands suggests that IGF is largely responsible for maintaining these wetlands. δ 18O data support the conclusions from the major ion data. Annual water and major ion budgets for two adjacent watersheds, one affected by IGF and the other not, showed that IGF accounted for two-thirds of the water input and 92-99% of the major ion input (depending on the major ion in question) to the former watershed. The large (in some cases, dominating) influence of IGF on watershed surface water quantity and quality has important implications for stream ecology and watershed management in this lowland rainforest. Because of its high phosphorus content, IGF increases a variety of ecological variables (algal growth rates, leaf decay rate, fungal biomass, invertebrate biomass, microbial respiration rates on leaves) in streams at La Selva. The significant rates of IGF at La Selva also suggest the importance of regional (as opposed to small-scale local) water resource planning that links lowland watersheds with regional groundwater. IGF is a relatively unexplored and potentially critical factor in the conservation of lowland rainforest.

Skylab extravehicular mobility unit thermal simulator

NASA Technical Reports Server (NTRS)

Hixon, C. W.; Phillips, M. A.

1974-01-01

The analytical methods, thermal model, and user's instructions for the Skylab Extravehicular Mobility Unit (SEMU) routine are presented. This digital computer program was developed for detailed thermal performance predictions of the SEMU on the NASA-JSC Univac 1108 computer system. It accounts for conductive, convective, and radiant heat transfer as well as fluid flow and special component characterization. The program provides thermal performance predictions for a 967 node thermal model in one thirty-sixth (1/36) of mission time when operated at a calculating interval of three minutes (mission time). The program has the operational flexibility to: (1) accept card or magnetic tape data input for the thermal model describing the SEMU structure, fluid systems, crewman and component performance, (2) accept card and/or magnetic tape input of internally generated heat and heat influx from the space environment, and (3) output tabular or plotted histories of temperature, flow rates, and other parameters describing system operating modes.

Noble gas storage and delivery system for ion propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

2001-01-01

A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

Eruption mass estimation using infrasound waveform inversion and ash and gas measurements: Evaluation at Sakurajima Volcano, Japan

NASA Astrophysics Data System (ADS)

Fee, David; Izbekov, Pavel; Kim, Keehoon; Yokoo, Akihiko; Lopez, Taryn; Prata, Fred; Kazahaya, Ryunosuke; Nakamichi, Haruhisa; Iguchi, Masato

2017-12-01

Eruption mass and mass flow rate are critical parameters for determining the aerial extent and hazard of volcanic emissions. Infrasound waveform inversion is a promising technique to quantify volcanic emissions. Although topography may substantially alter the infrasound waveform as it propagates, advances in wave propagation modeling and station coverage permit robust inversion of infrasound data from volcanic explosions. The inversion can estimate eruption mass flow rate and total eruption mass if the flow density is known. However, infrasound-based eruption flow rates and mass estimates have yet to be validated against independent measurements, and numerical modeling has only recently been applied to the inversion technique. Here we present a robust full-waveform acoustic inversion method, and use it to calculate eruption flow rates and masses from 49 explosions from Sakurajima Volcano, Japan. Six infrasound stations deployed from 12-20 February 2015 recorded the explosions. We compute numerical Green's functions using 3-D Finite Difference Time Domain modeling and a high-resolution digital elevation model. The inversion, assuming a simple acoustic monopole source, provides realistic eruption masses and excellent fit to the data for the majority of the explosions. The inversion results are compared to independent eruption masses derived from ground-based ash collection and volcanic gas measurements. Assuming realistic flow densities, our infrasound-derived eruption masses for ash-rich eruptions compare favorably to the ground-based estimates, with agreement ranging from within a factor of two to one order of magnitude. Uncertainties in the time-dependent flow density and acoustic propagation likely contribute to the mismatch between the methods. Our results suggest that realistic and accurate infrasound-based eruption mass and mass flow rate estimates can be computed using the method employed here. If accurate volcanic flow parameters are known, application of this technique could be broadly applied to enable near real-time calculation of eruption mass flow rates and total masses. These critical input parameters for volcanic eruption modeling and monitoring are not currently available.

Parallel pulse processing and data acquisition for high speed, low error flow cytometry

DOEpatents

van den Engh, Gerrit J.; Stokdijk, Willem

1992-01-01

A digitally synchronized parallel pulse processing and data acquisition system for a flow cytometer has multiple parallel input channels with independent pulse digitization and FIFO storage buffer. A trigger circuit controls the pulse digitization on all channels. After an event has been stored in each FIFO, a bus controller moves the oldest entry from each FIFO buffer onto a common data bus. The trigger circuit generates an ID number for each FIFO entry, which is checked by an error detection circuit. The system has high speed and low error rate.

The use of three-parameter rating table lookup programs, RDRAT and PARM3, in hydraulic flow models

USGS Publications Warehouse

Sanders, C.L.

1995-01-01

Subroutines RDRAT and PARM3 enable computer programs such as the BRANCH open-channel unsteady-flow model to route flows through or over combinations of critical-flow sections, culverts, bridges, road- overflow sections, fixed spillways, and(or) dams. The subroutines also obstruct upstream flow to simulate operation of flapper-type tide gates. A multiplier can be applied by date and time to simulate varying numbers of tide gates being open or alternative construction scenarios for multiple culverts. The subroutines use three-parameter (headwater, tailwater, and discharge) rating table lookup methods. These tables may be manually prepared using other programs that do step-backwater computations or compute flow through bridges and culverts or over dams. The subroutine, therefore, precludes the necessity of incorporating considerable hydraulic computational code into the client program, and provides complete flexibility for users of the model for routing flow through almost any affixed structure or combination of structures. The subroutines are written in Fortran 77 language, and have minimal exchange of information with the BRANCH model or other possible client programs. The report documents the interpolation methodology, data input requirements, and software.

Building and Characterizing Volcanic Landscapes with a Numerical Landscape Evolution Model and Spectral Techniques

NASA Astrophysics Data System (ADS)

Richardson, P. W.; Karlstrom, L.

2016-12-01

The competition between constructional volcanic processes such as lava flows, cinder cones, and tumuli compete with physical and chemical erosional processes to control the morphology of mafic volcanic landscapes. If volcanic effusion rates are high, these landscapes are primarily constructional, but over the timescales associated with hot spot volcanism (1-10 Myr) and arcs (10-50 Myr), chemical and physical erosional processes are important. For fluvial incision to occur, initially high infiltration rates must be overcome by chemical weathering or input of fine-grained sediment. We investigate lava flow resurfacing, using a new lava flow algorithm that can be calibrated for specific flows and eruption magnitude/frequency relationships, into a landscape evolution model to complete two modeling experiments to investigate the interplay between volcanic resurfacing and fluvial incision. We use a stochastic spatial vent distribution calibrated from the Hawaiian eruption record to resurface a synthetically produced ocean island. In one experiment, we investigate the consequences of including time-dependent channel incision efficiency. This effectively mimics the behavior of transient hydrological development of lava flows. In the second experiment, we explore the competition between channel incision and lava flow resurfacing. The relative magnitudes of channel incision versus lava flow resurfacing are captured in landscape topography. For example, during the shield building period for ocean islands, effusion rates are high and the signature of lava flow resurfacing dominates. In contrast, after the shield building phase, channel incision begins and eventually dominates the topographic signature. We develop a dimensionless ratio of resurfacing rate to erosion rate to characterize the transition between these processes. We use spectral techniques to characterize volcanic features and to pinpoint the transition between constructional and erosional morphology on modeled landscapes and on the Big Island of Hawaii.

Providing pressure inputs to multizone building models

DOE PAGES

Herring, Steven J.; Batchelor, Simon; Bieringer, Paul E.; ...

2016-02-13

A study to assess how the fidelity of wind pressure inputs and indoor model complexity affect the predicted air change rate for a study building is presented. The purpose of the work is to support the development of a combined indoor-outdoor hazard prediction tool, which links the CONTAM multizone building simulation tool with outdoor dispersion models. The study building, representing a large office block of a simple rectangular geometry under natural ventilation, was based on a real building used in the Joint Urban 2003 experiment. A total of 1600 indoor model flow simulations were made, driven by 100 meteorological conditionsmore » which provided a wide range of building surface pressures. These pressures were applied at four levels of resolution to four different building configurations with varying numbers of internal zones and indoor and outdoor flow paths. Analysis of the results suggests that surface pressures and flow paths across the envelope should be specified at a resolution consistent with the dimensions of the smallest volume of interest, to ensure that appropriate outputs are obtained.« less

On-chip cell sorting via patterned magnetic traps

NASA Astrophysics Data System (ADS)

Byvank, Tom; Prikockis, Michael; Chen, Aaron; Miller, Brandon; Chalmers, Jeffrey; Sooryakumar, Ratnasingham

2015-03-01

Due to their importance in research for the diagnosis and treatment of cancer, numerous schemes have been developed to sort rare cell populations, e.g., circulating tumor cells (CTCs), from a larger ensemble of cells. Here, we improve upon a previously developed microfluidic device (Lab Chip 13, 1172, (2013)) to increase throughput and sorting purity of magnetically labeled cells. The separation mechanism involves controlling magnetic forces by manipulating the magnetic domain structures of embedded permalloy microdisks with weak external fields. These forces move labeled cells from the input flow stream into an adjacent buffer flow stream. Such magnetically activated transfer separates the magnetic entities from their non-magnetic counterparts as the two flow streams split apart and move toward their respective outputs. Purity of the magnetic output is modulated by the withdrawal rate of the non-magnetic output relative to the inputs. A proof of concept shows that CTCs from metastatic breast cancer patients can be sorted, recovered from the device, and confirmed as CTCs using separate immunofluorescence staining and analysis. With further optimizations, the channel could become a useful device for high purity final sorting of enriched patient cell samples.

Investigation of a continuous heating/cooling technique for cardiac output measurement.

PubMed

Ehlers, K C; Mylrea, K C; Calkins, J M

1987-01-01

Cardiac output is frequently measured to assess patient hemodynamic status in the operating room and intensive care unit. Current research for measuring cardiac output includes continuous sinusoidal heating and synchronous detection of thermal signals. This technique is limited by maximum heating element temperatures and background thermal noise. A continuous heating and cooling technique was investigated in vitro to determine if greater thermal signal magnitudes could be obtained. A fast responding thermistor was employed to measure consecutive ejected temperature plateaus in the thermal signal. A flow bath and mechanical ventricle were used to simulate the cardiovascular system. A thermoelectric module was used to apply heating and cooling energy to the flow stream. Trials encompassing a range of input power, input frequency, and flow rate were conducted. By alternating heating and cooling, thermal signal magnitude can be increased when compared to continuous heating alone. However, the increase was not sufficient to allow for recording in all patients over the expected normal range of cardiac output. Consecutive ejected temperature plateaus were also measured on the thermal signal and ejection fraction calculations were made.

Net Surface Flux Budget Over Tropical Oceans Estimated from the Tropical Rainfall Measuring Mission (TRMM)

NASA Astrophysics Data System (ADS)

Fan, Tai-Fang

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Magneto - Optical Imaging of Superconducting MgB2 Thin Films

NASA Astrophysics Data System (ADS)

Hummert, Stephanie Maria

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Open Markov Processes and Reaction Networks

NASA Astrophysics Data System (ADS)

Swistock Pollard, Blake Stephen

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Boron Carbide Filled Neutron Shielding Textile Polymers

NASA Astrophysics Data System (ADS)

Manzlak, Derrick Anthony

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Parallel Unstructured Grid Generation for Complex Real-World Aerodynamic Simulations

NASA Astrophysics Data System (ADS)

Zagaris, George

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Polymeric Radiation Shielding for Applications in Space: Polyimide Synthesis and Modeling of Multi-Layered Polymeric Shields

NASA Astrophysics Data System (ADS)

Schiavone, Clinton Cleveland

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Processing and Conversion of Algae to Bioethanol

NASA Astrophysics Data System (ADS)

Kampfe, Sara Katherine

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

The Development of the CALIPSO LiDAR Simulator

NASA Astrophysics Data System (ADS)

Powell, Kathleen A.

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Exploring a Novel Approach to Technical Nuclear Forensics Utilizing Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Peeke, Richard Scot

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Production of Cyclohexylene-Containing Diamines in Pursuit of Novel Radiation Shielding Materials

NASA Astrophysics Data System (ADS)

Bate, Norah G.

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Development of Boron-Containing Polyimide Materials and Poly(arylene Ether)s for Radiation Shielding

NASA Astrophysics Data System (ADS)

Collins, Brittani May

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Magnetization Dynamics and Anisotropy in Ferromagnetic/Antiferromagnetic Ni/NiO Bilayers

NASA Astrophysics Data System (ADS)

Petersen, Andreas

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Fodder Resource Uses and Assessment of Nitrogen Flows on Livestock Farming with Crop Production

NASA Astrophysics Data System (ADS)

Shirahase, Kyoko; Kobayashi, Hisashi

With understanding the livestock farming on cattle breeding practiced increasing of self-production of fodders by the farmland's operation as “Livestock Farming with crop production”, we investigated the utilizations of actual fodder resources and farmland for two selected different types of livestock farming systems: “Multiple Type” which practices cattle raising with fodder cultivation, and “Grazing Type” which practices grazing and fodder cultivation with similar feed self-sufficiency rates. We also prepared and compared material and nitrogen flow of both livestock farming systems. The amount of nitrogen flow is clearly different between the two types though feed self-sufficiency rates are at similar level. Moreover, we defined “Internal Nitrogen Rate (INR)” which indicates the rate of internal nitrogen use to total nitrogen use in cattle raising, “Internal Nitrogen Circulation Rate (NCR)” which indicates the ratio of nitrogen amount in internal circulation to the nitrogen amount introduced from outside, and Nitrogen Outflow Potential (Op), which is the balance of nitrogen amount between input to farmlands and uptake by plants, and analyzed the balance of the amounts of nitrogen flows in both livestock farming type. It is suggested that “Grazing type”, which had the values of relatively high NCR and absolutely low Op, was the livestock farming type with high rates of nitrogen procurement from the interregional farming and low risk of nitrogen outflow.

Mixing and solid-liquid mass-transfer rates in a creusot-loire uddeholm vessel: A water model case study

NASA Astrophysics Data System (ADS)

Nyoka, M.; Akdogan, G.; Eric, R. H.; Sutcliffe, N.

2003-12-01

The process of mixing and solid-liquid mass transfer in a one-fifth scale water model of a 100-ton Creusot-Loire Uddeholm (CLU) converter was investigated. The modified Froude number was used to relate gas flow rates between the model and its protoype. The influences of gas flow rate between 0.010 and 0.018 m3/s and bath height from 0.50 to 0.70 m on mixing time were examined. The results indicated that mixing time decreased with increasing gas flow rate and increased with increasing bath height. The mixing time results were evaluated in terms of specific energy input and the following correlation was proposed for estimating mixing times in the model CLU converter: T mix=1.08Q -1.05 W 0.35, where Q (m3/s) is the gas flow rate and W (tons) is the model bath weight. Solid-liquid mass-transfer rates from benzoic acid specimens immersed in the gas-agitated liquid phase were assessed by a weight loss measurement technique. The calculated mass-transfer coefficients were highest at the bath surface reaching a value of 6.40 × 10-5 m/s in the sprout region. Mass-transfer coefficients and turbulence parameters decreased with depth, reaching minimum values at the bottom of the vessel.

Microfluidic chemostat and turbidostat with flow rate, oxygen, and temperature control for dynamic continuous culture.

PubMed

Lee, Kevin S; Boccazzi, Paolo; Sinskey, Anthony J; Ram, Rajeev J

2011-05-21

This work reports on an instrument capable of supporting automated microscale continuous culture experiments. The instrument consists of a plastic-PDMS device capable of continuous flow without volume drift or evaporation. We apply direct computer controlled machining and chemical bonding fabrication for production of fluidic devices with a 1 mL working volume, high oxygen transfer rate (k(L)a≈0.025 s(-1)), fast mixing (2 s), accurate flow control (±18 nL), and closed loop control over temperature, cell density, dissolved oxygen, and pH. Integrated peristaltic pumps and valves provide control over input concentrations and allow the system to perform different types of cell culture on a single device, such as batch, chemostat, and turbidostat continuous cultures. Continuous cultures are demonstrated without contamination for 3 weeks in a single device and both steady state and dynamically controlled conditions are possible. © The Royal Society of Chemistry 2011

Liquid metal enabled pump

PubMed Central

Tang, Shi-Yang; Khoshmanesh, Khashayar; Sivan, Vijay; Petersen, Phred; O’Mullane, Anthony P.; Abbott, Derek; Mitchell, Arnan; Kalantar-zadeh, Kourosh

2014-01-01

Small-scale pumps will be the heartbeat of many future micro/nanoscale platforms. However, the integration of small-scale pumps is presently hampered by limited flow rate with respect to the input power, and their rather complicated fabrication processes. These issues arise as many conventional pumping effects require intricate moving elements. Here, we demonstrate a system that we call the liquid metal enabled pump, for driving a range of liquids without mechanical moving parts, upon the application of modest electric field. This pump incorporates a droplet of liquid metal, which induces liquid flow at high flow rates, yet with exceptionally low power consumption by electrowetting/deelectrowetting at the metal surface. We present theory explaining this pumping mechanism and show that the operation is fundamentally different from other existing pumps. The presented liquid metal enabled pump is both efficient and simple, and thus has the potential to fundamentally advance the field of microfluidics. PMID:24550485

Aerodynamic heating on AFE due to nonequilibrium flow with variable entropy at boundary layer edge

NASA Technical Reports Server (NTRS)

Ting, P. C.; Rochelle, W. C.; Bouslog, S. A.; Tam, L. T.; Scott, C. D.; Curry, D. M.

1991-01-01

A method of predicting the aerobrake aerothermodynamic environment on the NASA Aeroassist Flight Experiment (AFE) vehicle is described. Results of a three dimensional inviscid nonequilibrium solution are used as input to an axisymmetric nonequilibrium boundary layer program to predict AFE convective heating rates. Inviscid flow field properties are obtained from the Euler option of the Viscous Reacting Flow (VRFLO) code at the boundary layer edge. Heating rates on the AFE surface are generated with the Boundary Layer Integral Matrix Procedure (BLIMP) code for a partially catalytic surface composed of Reusable Surface Insulation (RSI) times. The 1864 kg AFE will fly an aerobraking trajectory, simulating return from geosynchronous Earth orbit, with a 75 km perigee and a 10 km/sec entry velocity. Results of this analysis will provide principal investigators and thermal analysts with aeroheating environments to perform experiment and thermal protection system design.

Reconstruction of an input function from a dynamic PET water image using multiple tissue curves

NASA Astrophysics Data System (ADS)

Kudomi, Nobuyuki; Maeda, Yukito; Yamamoto, Yuka; Nishiyama, Yoshihiro

2016-08-01

Quantification of cerebral blood flow (CBF) is important for the understanding of normal and pathologic brain physiology. When CBF is assessed using PET with {{\\text{H}}2} 15O or C15O2, its calculation requires an arterial input function, which generally requires invasive arterial blood sampling. The aim of the present study was to develop a new technique to reconstruct an image derived input function (IDIF) from a dynamic {{\\text{H}}2} 15O PET image as a completely non-invasive approach. Our technique consisted of using a formula to express the input using tissue curve with rate constant parameter. For multiple tissue curves extracted from the dynamic image, the rate constants were estimated so as to minimize the sum of the differences of the reproduced inputs expressed by the extracted tissue curves. The estimated rates were used to express the inputs and the mean of the estimated inputs was used as an IDIF. The method was tested in human subjects (n  =  29) and was compared to the blood sampling method. Simulation studies were performed to examine the magnitude of potential biases in CBF and to optimize the number of multiple tissue curves used for the input reconstruction. In the PET study, the estimated IDIFs were well reproduced against the measured ones. The difference between the calculated CBF values obtained using the two methods was small as around  <8% and the calculated CBF values showed a tight correlation (r  =  0.97). The simulation showed that errors associated with the assumed parameters were  <10%, and that the optimal number of tissue curves to be used was around 500. Our results demonstrate that IDIF can be reconstructed directly from tissue curves obtained through {{\\text{H}}2} 15O PET imaging. This suggests the possibility of using a completely non-invasive technique to assess CBF in patho-physiological studies.

Study of cryogenic propellant systems for loading the space shuttle. Part 2: Hydrogen systems

NASA Technical Reports Server (NTRS)

Steward, W. G.

1975-01-01

Computer simulation studies of liquid hydrogen fill and vent systems for the space shuttle are studied. The computer programs calculate maximum and minimum permissible flow rates during cooldown as limited by thermal stress considerations, fill line cooldown time, pressure drop, flow rates, vapor content, vent line pressure drop and vent line discharge temperature. The input data for these programs are selected through graphic displays which schematically depict the part of the system being analyzed. The computed output is also displayed in the form of printed messages and graphs. Digital readouts of graph coordinates may also be obtained. Procedures are given for operation of the graphic display unit and the associated minicomputer and timesharing computer.

Dimensionless numbers in additive manufacturing

NASA Astrophysics Data System (ADS)

Mukherjee, T.; Manvatkar, V.; De, A.; DebRoy, T.

2017-02-01

The effects of many process variables and alloy properties on the structure and properties of additively manufactured parts are examined using four dimensionless numbers. The structure and properties of components made from 316 Stainless steel, Ti-6Al-4V, and Inconel 718 powders for various dimensionless heat inputs, Peclet numbers, Marangoni numbers, and Fourier numbers are studied. Temperature fields, cooling rates, solidification parameters, lack of fusion defects, and thermal strains are examined using a well-tested three-dimensional transient heat transfer and fluid flow model. The results show that lack of fusion defects in the fabricated parts can be minimized by strengthening interlayer bonding using high values of dimensionless heat input. The formation of harmful intermetallics such as laves phases in Inconel 718 can be suppressed using low heat input that results in a small molten pool, a steep temperature gradient, and a fast cooling rate. Improved interlayer bonding can be achieved at high Marangoni numbers, which results in vigorous circulation of liquid metal, larger pool dimensions, and greater depth of penetration. A high Fourier number ensures rapid cooling, low thermal distortion, and a high ratio of temperature gradient to the solidification growth rate with a greater tendency of plane front solidification.

Revisiting Maxwell’s accommodation coefficient: A study of nitrogen flow in a silica microtube across all flow regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lei, Wenwen, E-mail: wlei@physics.usyd.edu.au; McKenzie, David R., E-mail: d.mckenzie@physics.usyd.edu.au

2014-12-15

Gas flows have been studied quantitatively for more than a hundred years and have relevance in modern fields such as the control of gas inputs to processes, the measurement of leak rates and the separation of gaseous species. Cha and McCoy have derived a convenient formula for the flow of an ideal gas applicable across a wide range of Knudsen numbers (Kn) that approaches the Navier–Stokes equations at small Kn and the Smoluchowski extension of the Knudsen flow equation at large Kn. Smoluchowski’s result relies on the Maxwell definition of the tangential momentum accommodation coefficient α, recently challenged by Aryamore » et al. We measure the flow rate of nitrogen gas in a smooth walled silica tube across a wide range of Knudsen numbers from 0.0048 to 12.4583. We find that the nitrogen flow obeys the Cha and McCoy equation with a large value of α, unlike carbon nanotubes which show flows consistent with a small value of α. Silica capillaries are therefore not atomically smooth. The flow at small Kn has α=0.91 and at large Kn has α close to one, consistent with the redefinition of accommodation coefficient by Arya et al., which also resolves a problem in the literature where there are many observations of α of less than one at small Kn and many equal to one at large Kn. Silica capillaries are an excellent choice for an accurate flow control system. - Highlights: • First experimental study on flow rate across all flow regimes in a well-defined microtube. • Extend Cha and McCoy theory for molecular flow regime. • Demonstrate the Maxwell accommodation coefficient is different in the slip and molecular flow regimes.« less

Nitrogen attenuation in the Connecticut River, northeastern USA; a comparison of mass balance and N2 production modeling approaches

USGS Publications Warehouse

Smith, T.E.; Laursen, A.E.; Deacon, J.R.

2008-01-01

Two methods were used to measure in-stream nitrogen loss in the Connecticut River during studies conducted in April and August 2005. A mass balance on nitrogen inputs and output for two study reaches (55 and 66 km), at spring high flow and at summer low flow, was computed on the basis of total nitrogen concentrations and measured river discharges in the Connecticut River and its tributaries. In a 10.3 km subreach of the northern 66 km reach, concentrations of dissolved N2 were also measured during summer low flow and compared to modeled N2 concentrations (based on temperature and atmospheric gas exchange rates) to determine the measured "excess" N2 that indicates denitrification. Mass balance results showed no in-stream nitrogen loss in either reach during April 2005, and no nitrogen loss in the southern 55 km study reach during August 2005. In the northern 66 km reach during August 2005, however, nitrogen output was 18% less than the total nitrogen inputs to the reach. N2 sampling results gave an estimated rate of N2 production that would remove 3.3% of the nitrogen load in the river over the 10.3 km northern sub-reach. The nitrogen losses measured in the northern reach in August 2005 may represent an approximate upper limit for nitrogen attenuation in the Connecticut River because denitrification processes are most active during warm summer temperatures and because the study was performed during the annual low-flow period when total nitrogen loads are small. ?? 2008 Springer Science+Business Media B.V.

Impact of multi-resolution analysis of artificial intelligence models inputs on multi-step ahead river flow forecasting

NASA Astrophysics Data System (ADS)

Badrzadeh, Honey; Sarukkalige, Ranjan; Jayawardena, A. W.

2013-12-01

Discrete wavelet transform was applied to decomposed ANN and ANFIS inputs.Novel approach of WNF with subtractive clustering applied for flow forecasting.Forecasting was performed in 1-5 step ahead, using multi-variate inputs.Forecasting accuracy of peak values and longer lead-time significantly improved.

Relative contribution of hemlock pollen to the phosphorus loading of the clear lake ecosystem near Minden, Ontario

Treesearch

Hugh H. Banks; James E. Nighswander

2000-01-01

The forest stand composition within the terrestrial watershed of a small lake on the southern Precambrian Shield was assessed. Total phosphorus inputs from the terrestrial watersheds were obtained for two sub inflows by measuring flow rates and phosphorus concentrations. Direct aerial phosphorus fallout was estimated from nearby sites sampled by the Ontario Ministry of...

Water injected fuel cell system compressor

DOEpatents

Siepierski, James S.; Moore, Barbara S.; Hoch, Martin Monroe

2001-01-01

A fuel cell system including a dry compressor for pressurizing air supplied to the cathode side of the fuel cell. An injector sprays a controlled amount of water on to the compressor's rotor(s) to improve the energy efficiency of the compressor. The amount of water sprayed out the rotor(s) is controlled relative to the mass flow rate of air inputted to the compressor.

Data flow language and interpreter for a reconfigurable distributed data processor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurt, A.D.; Heath, J.R.

1982-01-01

An analytic language and an interpreter whereby an applications data flow graph may serve as an input to a reconfigurable distributed data processor is proposed. The architecture considered consists of a number of loosely coupled computing elements (CES) which may be linked to data and file memories through fully nonblocking interconnect networks. The real-time performance of such an architecture depends upon its ability to alter its topology in response to changes in application, asynchronous data rates and faults. Such a data flow language enhances the versatility of a reconfigurable architecture by allowing the user to specify the machine's topology atmore » a very high level. 11 references.« less

Orbiter thermal pressure drop characteristics for shuttle orbiter thermal protection system components: High density tile, low density tile, densified low density tile, and strain isolation pad

NASA Technical Reports Server (NTRS)

Lawing, P. L.; Nystrom, D. M.

1980-01-01

Pressure drop tests were conducted on available samples of low and high density tile, densified low density tile, and strain isolation pads. The results are presented in terms of pressure drop, material thickness and volume flow rate. Although the test apparatus was only capable of a small part of the range of conditions to be encountered in a Shuttle Orbiter flight, the data serve to determine the type of flow characteristics to be expected for each material type tested; the measured quantities also should serve as input for initial venting and flow through analysis.

Thermal transpiration in zeolites: A mechanism for motionless gas pumps

NASA Astrophysics Data System (ADS)

Gupta, Naveen K.; Gianchandani, Yogesh B.

2008-11-01

We explore the use of a naturally occurring zeolite, clinoptilolite, for a chip-scale, thermal transpiration-based gas pump. The nanopores in clinoptilolite enable the required free-molecular flow, even at atmospheric pressure. The pump utilizes a foil heater located between zeolite disks in a plastic package. A 2.3mm thick zeolite disk generates a typical gas flow rate of 6.6×10-3 cc/min-cm2 with an input power of <300mW/cm2. The performance is constrained by imperfections in clinoptilolite, which provide estimated leakage apertures of 10.2-13.5μm/cm2 of flow cross section. The transient response of the pump is studied to quantify nonidealities.

Helicon double layer thruster operation in a low magnetic field mode

NASA Astrophysics Data System (ADS)

Harle, T.; Pottinger, S. J.; Lappas, V. J.

2013-02-01

Direct thrust measurements are made of a helicon double layer thruster operating in a low magnetic field mode. The relationship between the imposed axial magnetic field and generated thrust is investigated for a radio frequency input power range 200-500 W for propellant flow rates of 16.5 and 20 sccm (0.46 and 0.55 mg s-1) of argon. The measured thrust shows a strong dependence on the magnetic field strength, increasing by up to a factor of 5 compared with the minimum thrust level recorded. A peak thrust of 0.4-1.1 mN depending on thruster operating conditions is obtained. This increase is observed to take place over a small range of peak magnetic field strengths in the region of 70-110 G. The magnitude of the thrust and the corresponding magnitude of the magnetic field at which the peak thrust occurs is shown to increase with increasing input power for a given propellant flow rate. The ion current determined using a retarding field energy analyser and the electron number density found using a microwave resonator probe both correlate with the observed trend in thrust as a function of applied magnetic field.

The Role of Small Impoundments on Flow Alteration Within River Networks

NASA Astrophysics Data System (ADS)

Brogan, C. O.; Keys, T.; Scott, D.; Burgholzer, R.; Kleiner, J.

2017-12-01

Numerous water quality and quantity models have been established to illustrate the ecologic and hydrologic effects of large reservoirs. Smaller, unregulated ponds are often assumed to have a negligible impact on watershed flow regimes even though they overwhelmingly outnumber larger waterbodies. Individually, these small impoundments impart merely a fraction of the flow alteration larger reservoirs do; however, a network of ponds may act cumulatively to alter the flow regime. Many models have attempted to study smaller impoundments but rely on selectively available rating curves or bathymetry surveys. This study created a generalized process to model impoundments of varying size across a 58 square mile watershed exclusively using satellite imagery and publicly available information as inputs. With information drawn from public Army Corps of Engineers databases and LiDAR surveys, it was found that impoundment surface and drainage area served as useful explanatory variables, capable of predicting both pond bathymetry and outlet structure area across the 37 waterbodies modeled within the study area. Working within a flow routing model with inputs from the Chesapeake Bay HSPF model and verified with USGS gauge data, flow simulations were conducted with increasing number of impoundments to quantify how small ponds affect the overall flow regime. As the total impounded volume increased, simulations showed a notable reduction in both low and peak flows. Medium-sized floods increased as the network of ponds and reservoirs stabilized the catchment's streamflow. The results of this study illustrate the importance of including ponded waters into river corridor models to improve downstream management of both water quantity and quality.

Development of Flow and Heat Transfer Models for the Carbon Fiber Rope in Nozzle Joints of the Space Shuttle Reusable Solid Rocket Motor

NASA Technical Reports Server (NTRS)

Wang, Q.; Ewing, M. E.; Mathias, E. C.; Heman, J.; Smith, C.; McCool, Alex (Technical Monitor)

2001-01-01

Methodologies have been developed for modeling both gas dynamics and heat transfer inside the carbon fiber rope (CFR) for applications in the space shuttle reusable solid rocket motor joints. Specifically, the CFR is modeled using an equivalent rectangular duct with a cross-section area, friction factor and heat transfer coefficient such that this duct has the same amount of mass flow rate, pressure drop, and heat transfer rate as the CFR. An equation for the friction factor is derived based on the Darcy-Forschheimer law and the heat transfer coefficient is obtained from pipe flow correlations. The pressure, temperature and velocity of the gas inside the CFR are calculated using the one-dimensional Navier-Stokes equations. Various subscale tests, both cold flow and hot flow, have been carried out to validate and refine this CFR model. In particular, the following three types of testing were used: (1) cold flow in a RSRM nozzle-to-case joint geometry, (2) cold flow in a RSRM nozzle joint No. 2 geometry, and (3) hot flow in a RSRM nozzle joint environment simulator. The predicted pressure and temperature history are compared with experimental measurements. The effects of various input parameters for the model are discussed in detail.

Quantitative identification of riverine nitrogen from point, direct runoff and base flow sources.

PubMed

Huang, Hong; Zhang, Baifa; Lu, Jun

2014-01-01

We present a methodological example for quantifying the contributions of riverine total nitrogen (TN) from point, direct runoff and base flow sources by combining a recursive digital filter technique and statistical methods. First, we separated daily riverine flow into direct runoff and base flow using a recursive digital filter technique; then, a statistical model was established using daily simultaneous data for TN load, direct runoff rate, base flow rate, and temperature; and finally, the TN loading from direct runoff and base flow sources could be inversely estimated. As a case study, this approach was adopted to identify the TN source contributions in Changle River, eastern China. Results showed that, during 2005-2009, the total annual TN input to the river was 1,700.4±250.2 ton, and the contributions of point, direct runoff and base flow sources were 17.8±2.8%, 45.0±3.6%, and 37.2±3.9%, respectively. The innovation of the approach is that the nitrogen from direct runoff and base flow sources could be separately quantified. The approach is simple but detailed enough to take the major factors into account, providing an effective and reliable method for riverine nitrogen loading estimation and source apportionment.

Experimental Investigation of A Heat Pipe-Assisted Latent Heat Thermal Energy Storage System

NASA Astrophysics Data System (ADS)

Tiari, Saeed; Mahdavi, Mahboobe; Qiu, Songgang

2016-11-01

In the present work, different operation modes of a latent heat thermal energy storage system assisted by a heat pipe network were studied experimentally. Rubitherm RT55 enclosed by a vertical cylindrical container was used as the Phase Change Material (PCM). The embedded heat pipe network consisting of a primary heat pipe and an array of four secondary heat pipes were employed to transfer heat to the PCM. The primary heat pipe transports heat from the heat source to the heat sink. The secondary heat pipes transfer the extra heat from the heat source to PCM during charging process or retrieve thermal energy from PCM during discharging process. The effects of heat transfer fluid (HTF) flow rate and temperature on the thermal performance of the system were investigated for both charging and discharging processes. It was found that the HTF flow rate has a significant effect on the total charging time of the system. Increasing the HTF flow rate results in a remarkable increase in the system input thermal power. The results also showed that the discharging process is hardly affected by the HTF flow rate but HTF temperature plays an important role in both charging and discharging processes. The authors would like to acknowledge the financial supports by Temple University for the project.

Systems Analysis and Design for Decision Support Systems on Economic Feasibility of Projects

NASA Astrophysics Data System (ADS)

Balaji, S. Arun

2010-11-01

This paper discuss about need for development of the Decision Support System (DSS) software for economic feasibility of projects in Rwanda, Africa. The various economic theories needed and the corresponding formulae to compute payback period, internal rate of return and benefit cost ratio of projects are clearly given in this paper. This paper is also deals with the systems flow chart to fabricate the system in any higher level computing language. The various input requirements from the projects and the output needed for the decision makers are also included in this paper. The data dictionary used for input and output data structure is also explained.

Evaluation of pulsed streamer corona experiments to determine the O* radical yield

NASA Astrophysics Data System (ADS)

van Heesch, E. J. M.; Winands, G. J. J.; Pemen, A. J. M.

2008-12-01

The production of O* radicals in air by a pulsed streamer plasma is studied by integration of a large set of precise experimental data and the chemical kinetics of ozone production. The measured data comprise ozone production, plasma energy, streamer volume, streamer length, streamer velocity, humidity and gas-flow rate. Instead of entering input parameters into a kinetic model to calculate the end products the opposite strategy is followed. Since the amount of end-products (ozone) is known from the measurements the model had to be applied in the reverse direction to determine the input parameters, i.e. the O* radical concentration.

The effect of visualizing the flow of multimedia content among and inside devices.

PubMed

Lee, Dong-Seok

2009-05-01

This study introduces a user interface, referred to as the flow interface, which provides a graphical representation of the movement of content among and inside audio/video devices. The proposed interface provides a different frame of reference with content-oriented visualization of the generation, manipulation, storage, and display of content as well as input and output. The flow interface was applied to a VCR/DVD recorder combo, one of the most complicated consumer products. A between-group experiment was performed to determine whether the flow interface helps users to perform various tasks and to examine the learning effect of the flow interface, particularly in regard to hooking up and recording tasks. The results showed that participants with access to the flow interface performed better in terms of success rate and elapsed time. In addition, the participants indicated that they could easily understand the flow interface. The potential of the flow interface for application to other audio video devices, and design issues requiring further consideration, are discussed.

Characterization of local fluid flow in 3D porous construct characterized by Fourier domain Doppler optical coherence tomography

NASA Astrophysics Data System (ADS)

Bagnaninchi, P. O.; Yang, Y.; El Haj, A.; Hinds, M. T.; Wang, R. K.

2007-02-01

In order to achieve functional tissue with the correct biomechanical properties it is critical to stimulate mechanically the cells. Perfusion bioreactor induces fluid shear stress that has been well characterized for two-dimensional culture where both simulation and experimental data are available. However these results can't be directly translated to tissue engineering that makes use of complex three-dimensional porous scaffold. Moreover, stimulated cells produce extensive extra-cellular matrix (ECM) that alter dramatically the micro-architecture of the constructs, changing the local flow dynamic. In this study a Fourier domain Doppler optical coherent tomography (FD-DOCT) system working at 1300nm with a bandwidth of 50nm has been used to determine the local flow rate inside different types of porous scaffolds used in tissue engineering. Local flow rates can then be linearly related, for Newtonian fluid, to the fluid shear stress occurring on the pores wall. Porous chitosan scaffolds (\\fgr 1.5mm x 3mm) with and without a central 250 μm microchannel have been produced by a freeze-drying technique. This techniques allow us to determine the actual shear stress applied to the cells and to optimise the input flow rate consequently, but also to relate the change of the flow distribution to the amount of ECM production allowing the monitoring of tissue formation.

A study to estimate the fate and transport of bacteria in river water from birds nesting under a bridge.

PubMed

Nayamatullah, M M M; Bin-Shafique, S; Sharif, H O

2013-01-01

To investigate the effect of input parameters, such as the number of bridge-dwelling birds, decay rate of the bacteria, flow at the river, water temperature, and settling velocity, a parametric study was conducted using a water quality model developed with QUAL2Kw. The reach of the bacterial-impaired section from the direct droppings of bridge-nesting birds at the Guadalupe River near Kerrville, Texas was estimated using the model. The concentration of Escherichia coli bacteria were measured upstream, below the bridge, and downstream of the river for one-and-a-half years. The decay rate of the indicator bacteria in the river water was estimated from the model using measured data, and was found to be 6.5/day. The study suggests that the number of bridge-dwelling birds, the decay rate, and flow at the river have the highest impact on the fate and transport of bacteria. The water temperature moderately affects the fate and transport of bacteria, whereas, the settling velocity of bacteria did not show any significant effect. Once the decay rates are estimated, the reach of the impaired section was predicted from the model using the average flow of the channel. Since the decay rate does not vary significantly in the ambient environment at this location, the length of the impaired section primarily depends on flow.

Biofiltration of air contaminated by styrene: Effect of nitrogen supply, gas flow rate, and inlet concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorio, H.; Bibeau, L.; Heitz, M.

2000-05-01

The biofiltration process is a promising technology for the treatment of dilute styrene emissions in air. The efficiency of this process is however strongly dependent upon various operational parameters such as the filter bed characteristics, nutrient supplies, input contaminant concentrations, and gas flow rates. The biofiltration of air containing styrene vapors was therefore investigated, employing a novel biomass filter material, in two identical but separate laboratory scale biofiltration units (units 1 and 2), both biofilters being initially inoculated with a microbial consortium. Each biofilter was irrigated with a nutrient solution supplying nitrogen in one of two forms; i.e., mainly asmore » ammonia for unit 1 and exclusively as nitrate for unit 2. The experimental results have revealed that greater styrene elimination rates are achieved in the biofilter supplied with ammonia as the major nitrogen source in comparison to the lesser elimination performance obtained with the nitrate provided biofilter. However, in achieving the high styrene removal rates in the ammonia supplied biofilter, the excess of biomass accumulates on the filtering pellets and causes progressive clogging of the filter media. Furthermore, the effectiveness of nitrate supply as the sole nitrogen nutrient form, on reducing or controlling the biomass accumulation in the filter media in comparison to ammonia, could not be satisfactorily demonstrated because the two biofilters operated with very different styrene elimination capacities. The monitoring of the carbon dioxide concentration profile through both biofilters revealed that the ratio of carbon dioxide produced to the styrene removed was approximately 3/1, which confirms the complete biodegradation of removed styrene, given that some of the organic carbon consumed is also used for the microbial growth. The effects of the most important design parameters, namely styrene input concentrations and gas flow rates, were investigated for each nutrient solution.« less

Teasing apart the effects of natural and constructed green ...

EPA Pesticide Factsheets

Summer low flows and stream temperature maxima are key drivers affecting the sustainability of fish populations. Thus, it is critical to understand both the natural templates of spatiotemporal variability, how these are shifting due to anthropogenic influences of development and climate change, and how these impacts can be moderated by natural and constructed green infrastructure. Low flow statistics of New England streams have been characterized using a combination of regression equations to describe long-term averages as a function of indicators of hydrologic regime (rain- versus snow-dominated), precipitation, evapotranspiration or temperature, surface water storage, baseflow recession rates, and impervious cover. Difference equations have been constructed to describe interannual variation in low flow as a function of changing air temperature, precipitation, and ocean-atmospheric teleconnection indices. Spatial statistical network models have been applied to explore fine-scale variability of thermal regimes along stream networks in New England as a function of variables describing natural and altered energy inputs, groundwater contributions, and retention time. Low flows exacerbate temperature impacts by reducing thermal inertia of streams to energy inputs. Based on these models, we can construct scenarios of fish habitat suitability using current and projected future climate and the potential for preservation and restoration of historic habitat regimes th

Estimation and impact assessment of input and parameter uncertainty in predicting groundwater flow with a fully distributed model

NASA Astrophysics Data System (ADS)

Touhidul Mustafa, Syed Md.; Nossent, Jiri; Ghysels, Gert; Huysmans, Marijke

2017-04-01

Transient numerical groundwater flow models have been used to understand and forecast groundwater flow systems under anthropogenic and climatic effects, but the reliability of the predictions is strongly influenced by different sources of uncertainty. Hence, researchers in hydrological sciences are developing and applying methods for uncertainty quantification. Nevertheless, spatially distributed flow models pose significant challenges for parameter and spatially distributed input estimation and uncertainty quantification. In this study, we present a general and flexible approach for input and parameter estimation and uncertainty analysis of groundwater models. The proposed approach combines a fully distributed groundwater flow model (MODFLOW) with the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm. To avoid over-parameterization, the uncertainty of the spatially distributed model input has been represented by multipliers. The posterior distributions of these multipliers and the regular model parameters were estimated using DREAM. The proposed methodology has been applied in an overexploited aquifer in Bangladesh where groundwater pumping and recharge data are highly uncertain. The results confirm that input uncertainty does have a considerable effect on the model predictions and parameter distributions. Additionally, our approach also provides a new way to optimize the spatially distributed recharge and pumping data along with the parameter values under uncertain input conditions. It can be concluded from our approach that considering model input uncertainty along with parameter uncertainty is important for obtaining realistic model predictions and a correct estimation of the uncertainty bounds.

CIRMIS Data system. Volume 2. Program listings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (OWNI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologicmore » systems, model the transport of released radionuclides through the hydrologic systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. The various input parameters required in the analysis are compiled in data systems. The data are organized and prepared by various input subroutines for utilization by the hydraulic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required.The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System is a storage and retrieval system for model input and output data, including graphical interpretation and display. This is the second of four volumes of the description of the CIRMIS Data System.« less

Assessment of effectiveness of geologic isolation systems. CIRMIS data system. Volume 4. Driller's logs, stratigraphic cross section and utility routines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Friedrichs, D.R.

1980-01-01

The Assessment of Effectiveness of Geologic Isolation Systems (AEGIS) Program is developing and applying the methodology for assessing the far-field, long-term post-closure safety of deep geologic nuclear waste repositories. AEGIS is being performed by Pacific Northwest Laboratory (PNL) under contract with the Office of Nuclear Waste Isolation (ONWI) for the Department of Energy (DOE). One task within AEGIS is the development of methodology for analysis of the consequences (water pathway) from loss of repository containment as defined by various release scenarios. Analysis of the long-term, far-field consequences of release scenarios requires the application of numerical codes which simulate the hydrologicmore » systems, model the transport of released radionuclides through the hydrologic systems to the biosphere, and, where applicable, assess the radiological dose to humans. The various input parameters required in the analysis are compiled in data systems. The data are organized and prepared by various input subroutines for use by the hydrologic and transport codes. The hydrologic models simulate the groundwater flow systems and provide water flow directions, rates, and velocities as inputs to the transport models. Outputs from the transport models are basically graphs of radionuclide concentration in the groundwater plotted against time. After dilution in the receiving surface-water body (e.g., lake, river, bay), these data are the input source terms for the dose models, if dose assessments are required. The dose models calculate radiation dose to individuals and populations. CIRMIS (Comprehensive Information Retrieval and Model Input Sequence) Data System is a storage and retrieval system for model input and output data, including graphical interpretation and display. This is the fourth of four volumes of the description of the CIRMIS Data System.« less

Parallel pulse processing and data acquisition for high speed, low error flow cytometry

DOEpatents

Engh, G.J. van den; Stokdijk, W.

1992-09-22

A digitally synchronized parallel pulse processing and data acquisition system for a flow cytometer has multiple parallel input channels with independent pulse digitization and FIFO storage buffer. A trigger circuit controls the pulse digitization on all channels. After an event has been stored in each FIFO, a bus controller moves the oldest entry from each FIFO buffer onto a common data bus. The trigger circuit generates an ID number for each FIFO entry, which is checked by an error detection circuit. The system has high speed and low error rate. 17 figs.

A compositional framework for reaction networks

NASA Astrophysics Data System (ADS)

Baez, John C.; Pollard, Blake S.

Reaction networks, or equivalently Petri nets, are a general framework for describing processes in which entities of various kinds interact and turn into other entities. In chemistry, where the reactions are assigned ‘rate constants’, any reaction network gives rise to a nonlinear dynamical system called its ‘rate equation’. Here we generalize these ideas to ‘open’ reaction networks, which allow entities to flow in and out at certain designated inputs and outputs. We treat open reaction networks as morphisms in a category. Composing two such morphisms connects the outputs of the first to the inputs of the second. We construct a functor sending any open reaction network to its corresponding ‘open dynamical system’. This provides a compositional framework for studying the dynamics of reaction networks. We then turn to statics: that is, steady state solutions of open dynamical systems. We construct a ‘black-boxing’ functor that sends any open dynamical system to the relation that it imposes between input and output variables in steady states. This extends our earlier work on black-boxing for Markov processes.

Geochemistry of manganese, iron, uranium, lead-210 and major ions in the Susquehanna River

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, D.M.

1976-01-01

The change in water composition accompanying a change in discharge of large streams and the Susquehanna River results from the change in the proportions of the total flow composed of type waters of constant composition. This change in the flow proportions is due to the different hydrologic responses to precipitation inputs of basins underlain by different single rock types. The in-river precipitation of mine-drainage-injected Mn and Fe was studied at a pH of approximately 7. For Mn the removal from solution appears to be first order. The rate constant is 10/sup 3/ times greater than the extrapolated autocatalytic rate constantmore » of previous laboratory experiments. The study of the removal of Fe from solution yields a first order rate constant consistent with previous laboratory experiments. Lead-210 was used as a natural tracer to study the fate of trace metals.« less

Self-regulated cooling flows in elliptical galaxies and in cluster cores - Is exclusively low mass star formation really necessary?

NASA Technical Reports Server (NTRS)

Silk, J.; Djorgovski, S.; Wyse, R. F. G.; Bruzual A., G.

1986-01-01

A self-consistent treatment of the heating by supernovae associated with star formation in a spherically symmetric cooling flow in a cluster core or elliptical galaxy is presented. An initial stellar mass function similar to that in the solar neighborhood is adopted. Inferred star-formation rates, within the cooling region - typically the inner 100 kpc around dominant galaxies at the centers of cooling flows in XD clusters - are reduced by about a factor of 2, relative to rates inferred when the heat input from star formation is ignored. Truncated initial mass functions (IMFs) are also considered, in which massive star formation is suppressed in accordance with previous treatments, and colors are predicted for star formation in cooling flows associated with central dominant elliptical galaxies and with isolated elliptical galaxies surrounded by gaseous coronae. The low inferred cooling-flow rates around isolated elliptical galaxies are found to be insensitive to the upper mass cutoff in the IMF, provided that the upper mass cutoff exceeds 2 M solar mass. Comparison with observed colors favors a cutoff in the IMF above 1 M solar mass in at least two well-studied cluster cooling flows, but a normal IMF cannot be excluded definitively. Models for NGC 1275 support a young (less than about 3 Gyr) cooling flow. As for the isolated elliptical galaxies, the spread in colors is consistent with a normal IMF. A definitive test of the IMF arising via star formation in cooling flows requires either UV spectral data or supernova searches in the cooling-flow-centered galaxies.

Numerical Investigation of the Influence of the Input Air Irregularity on the Performance of Turbofan Jet Engine

NASA Astrophysics Data System (ADS)

Novikova, Y.; Zubanov, V.

2018-01-01

The article describes the numerical investigation of the input air irregularity influence of turbofan engine on its characteristics. The investigated fan has a wide-blade, an inlet diameter about 2 meters, a pressure ratio about 1.6 and the bypass ratio about 4.8. The flow irregularity was simulated by the flap input in the fan inlet channel. Input of flap was carried out by an amount of 10 to 22,5% of the input channel diameter with increments of 2,5%. A nonlinear harmonic analysis (NLH-analysis) of NUMECA Fine/Turbo software was used to study the flow irregularity. The behavior of the calculated LPC characteristics repeats the experiment behavior, but there is a quantitative difference: the calculated efficiency and pressure ratio of booster consistent with the experimental data within 3% and 2% respectively, the calculated efficiency and pressure ratio of fan duct - within 4% and 2.5% respectively. An increasing the level of air irregularity in the input stage of the fan reduces the calculated mass flow, maximum pressure ratio and efficiency. With the value of flap input 12.5%, reducing the maximum air flow is 1.44%, lowering the maximum pressure ratio is 2.6%, efficiency decreasing is 3.1%.

γ-Fe2O3 nanoparticles filled polyvinyl alcohol as potential biomaterial for tissue engineering scaffold.

PubMed

Ngadiman, Nor Hasrul Akhmal; Idris, Ani; Irfan, Muhammad; Kurniawan, Denni; Yusof, Noordin Mohd; Nasiri, Rozita

2015-09-01

Maghemite (γ-Fe2O3) nanoparticle with its unique magnetic properties is recently known to enhance the cell growth rate. In this study, γ-Fe2O3 is mixed into polyvinyl alcohol (PVA) matrix and then electrospun to form nanofibers. Design of experiments was used to determine the optimum parameter settings for the electrospinning process so as to produce elctrospun mats with the preferred characteristics such as good morphology, Young's modulus and porosity. The input factors of the electrospinnning process were nanoparticles content (1-5%), voltage (25-35 kV), and flow rate (1-3 ml/h) while the responses considered were Young's modulus and porosity. Empirical models for both responses as a function of the input factors were developed and the optimum input factors setting were determined, and found to be at 5% nanoparticle content, 35 kV voltage, and 1 ml/h volume flow rate. The characteristics and performance of the optimum PVA/γ-Fe2O3 nanofiber mats were compared with those of neat PVA nanofiber mats in terms of morphology, thermal properties, and hydrophilicity. The PVA/γ-Fe2O3 nanofiber mats exhibited higher fiber diameter and surface roughness yet similar thermal properties and hydrophilicity compared to neat PVA PVA/γ-Fe2O3 nanofiber mats. Biocompatibility test by exposing the nanofiber mats with human blood cells was performed. In terms of clotting time, the PVA/γ-Fe2O3 nanofibers exhibited similar behavior with neat PVA. The PVA/γ-Fe2O3 nanofibers also showed higher cells proliferation rate when MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was done using human skin fibroblast cells. Thus, the PVA/γ-Fe2O3 electrospun nanofibers can be a promising biomaterial for tissue engineering scaffolds. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Network Flow Analysis of the Nitrogen Metabolism in Beijing, China.

PubMed

Zhang, Yan; Lu, Hanjing; Fath, Brian D; Zheng, Hongmei; Sun, Xiaoxi; Li, Yanxian

2016-08-16

Rapid urbanization results in high nitrogen flows and subsequent environmental consequences. In this study, we identified the main metabolic components (nitrogen inputs, flows, and outputs) and used ecological network analysis to track the direct and integral (direct + indirect) metabolic flows of nitrogen in Beijing, China, from 1996 to 2012 and to quantify the structure of Beijing's nitrogen metabolic processes. We found that Beijing's input of new reactive nitrogen (Q, which represents nitrogen obtained from the atmosphere or nitrogen-containing materials used in production and consumption to support human activities) increased from 431 Gg in 1996 to 507 Gg in 2012. Flows to the industry, atmosphere, and household, and components of the system were clearly largest, with total integrated inputs plus outputs from these nodes accounting for 31, 29, and 15%, respectively, of the total integral flows for all paths. The flows through the sewage treatment and transportation components showed marked growth, with total integrated inputs plus outputs increasing to 3.7 and 5.2 times their 1996 values, respectively. Our results can help policymakers to locate the key nodes and pathways in an urban nitrogen metabolic system so they can monitor and manage these components of the system.

Computer program for calculating laminar, transitional, and turbulent boundary layers for a compressible axisymmetric flow

NASA Technical Reports Server (NTRS)

Albers, J. A.; Gregg, J. L.

1974-01-01

A finite-difference program is described for calculating the viscous compressible boundary layer flow over either planar or axisymmetric surfaces. The flow may be initially laminar and progress through a transitional zone to fully turbulent flow, or it may remain laminar, depending on the imposed boundary conditions, laws of viscosity, and numerical solution of the momentum and energy equations. The flow may also be forced into a turbulent flow at a chosen spot by the data input. The input may contain the factors of arbitrary Reynolds number, free-stream Mach number, free-stream turbulence, wall heating or cooling, longitudinal wall curvature, wall suction or blowing, and wall roughness. The solution may start from an initial Falkner-Skan similarity profile, an approximate equilibrium turbulent profile, or an initial arbitrary input profile.

Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA

USGS Publications Warehouse

May, Christine L.; Gresswell, Robert E.

2003-01-01

Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low-order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand-replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low-order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain.

Control and Optimization of Regenerative Power Flow in 21st Century Airlifters

DTIC Science & Technology

2001-12-01

Figure 3.14. 32 R,=50 Li V , Input Voltage Respose Output Voltage Response’ vaAvB< 40V AVណ t t Figure 3.14. Time domain constraints for the converter...as it will influence the rate of rise of the current pulse. In the current work, L is limited to Self -inductance of the entire assembly is found under

Application of unsteady flow rate evaluations to identify the dynamic transfer function of a cavitatingVenturi

NASA Astrophysics Data System (ADS)

Marie-Magdeleine, A.; Fortes-Patella, R.; Lemoine, N.; Marchand, N.

2012-11-01

This study concerns the simulation of the implementation of the Kinetic Differential Pressure (KDP) method used for the unsteady mass flow rate evaluation in order to identify the dynamic transfer matrix of a cavitatingVenturi. Firstly, the equations of the IZ code used for this simulation are introduced. Next, the methodology for evaluating unsteady pressures and mass flow rates at the inlet and the outlet of the cavitatingVenturi and for identifying the dynamic transfer matrix is presented. Later, the robustness of the method towards measurement uncertainties implemented as a Gaussian white noise is studied. The results of the numerical simulations let us estimate the system linearity domain and to perform the Empirical Transfer Function Evaluation on the inlet frequency per frequency signal and on the chirp signal tests. Then the pressure data obtained with the KDP method is taken and the identification procedure by ETFE and by the user-made Auto-Recursive Moving-Average eXogenous algorithms is performed and the obtained transfer matrix coefficients are compared with those obtained from the simulated input and output data.

Urban rivers as conveyors of hydrocarbons to sediments of estuarine areas: source characterization, flow rates and mass accumulation.

PubMed

Mauad, Cristiane R; Wagener, Angela de L R; Massone, Carlos G; Aniceto, Mayara da S; Lazzari, Letícia; Carreira, Renato S; Farias, Cássia de O

2015-02-15

Aliphatic (n-C12-n-C40, unresolved complex mixture, resolved peaks) and aromatic hydrocarbons (46 PAH) were investigated in suspended particulate matter (SPM) sampled over eleven months in six of the major rivers and two channels of the Guanabara Bay Basin. PAH flow rates of the most contaminated rivers, the contribution to the PAH sediment load of the receiving bay, and the main sources of hydrocarbons were determined. PAH (38) ranged from 28 ng L(-1) to 11,514 ng L(-1). Hydrocarbon typology and statistical evaluation demonstrated contribution of distinct sources in different regions and allowed quantification of these contributions. Total flow rate for the five major rivers amounts to 3 t year(-1) and responds for 30% of the total PAH annual input into the northern area of the Guanabara Bay. For the first time PAH mass deposited in the bay sediments has been estimated and shall serve as base for decision making and source abatement. Copyright © 2014 Elsevier B.V. All rights reserved.

Conversion of carbon dioxide to carbon monoxide by pulse dielectric barrier discharge plasma

NASA Astrophysics Data System (ADS)

Wang, Taobo; Liu, Hongxia; Xiong, Xiang; Feng, Xinxin

2017-01-01

The conversion of carbon dioxide (CO2) to carbon monoxide (CO) was investigated in a non-thermal plasma dielectric barrier discharge (DBD) reactor, and the effects of different process conditions on the CO2 conversion were investigated. The results showed that the increase of input power could optimize the conversion of CO2 to CO. The CO2 conversion and CO yield were negatively correlated with the gas flow rate, but there was an optimum gas flow rate, that made the CO selectivity best. The carrier gas (N2, Ar) was conducive to the conversion of CO2, and the effect of N2 as carrier gas was better than Ar. The conversion of CO2 to CO was enhanced by addition of the catalyst (5A molecular sieve).

Modelling the Flow Stress of Alloy 316L using a Multi-Layered Feed Forward Neural Network with Bayesian Regularization

NASA Astrophysics Data System (ADS)

Abiriand Bhekisipho Twala, Olufunminiyi

2017-08-01

In this paper, a multilayer feedforward neural network with Bayesian regularization constitutive model is developed for alloy 316L during high strain rate and high temperature plastic deformation. The input variables are strain rate, temperature and strain while the output value is the flow stress of the material. The results show that the use of Bayesian regularized technique reduces the potential of overfitting and overtraining. The prediction quality of the model is thereby improved. The model predictions are in good agreement with experimental measurements. The measurement data used for the network training and model comparison were taken from relevant literature. The developed model is robust as it can be generalized to deformation conditions slightly below or above the training dataset.

Leakage current-induced effects in the silicon microstrip and gas electron multiplier readout chain and their compensation method

NASA Astrophysics Data System (ADS)

Zubrzycka, W.; Kasinski, K.

2018-04-01

Leakage current flowing into the charge sensitive amplifier (CSA) is a common issue in many radiation detection systems as it can increase overall system noise, shift a DC baseline or even lead a recording channel to instability. The commonly known leakage current contributor is a detector, however other system components like wires or an input protection circuit may become a serious problem. Compensation of the leakage current resulting from the electrostatic discharge (ESD) protection circuit by properly sizing its components is possible only for a narrow temperature range. Moreover, the leakage current from external sources can be significantly larger. Many applications, especially High Energy Physics (HEP) experiments, require a fast baseline restoration for high input hit rates by applying either a low-value feedback resistor or a high feedback resistance combined with a pulsed reset circuit. Leakage current flowing in the feedback in conjunction with a large feedback resistance supplied with a pulsed reset results in a significant voltage offset between the CSA input and output which can cause problems (e.g. fake hits or instability). This paper shows an issue referred to the leakage current of the ESD protection circuit flowing into the input amplifier. The following analysis and proposed solution is a result of the time and energy readout ASIC project realization for the Compressed Baryonic Matter (CBM) experiment at FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. This chip is purposed to work with microstrip and gaseous detectors, with high average input pulses frequencies (250 kHit/s per channel) and the possibility to process input charge of both polarities. We present measurements of the test structure fabricated in UMC 180 nm technology and propose a solution addressing leakage current related issues. This work combines the leakage current compensation capabilities at the CSA level with high, controllable value of the amplifier feedback resistor independent of the leakage current level and polarity. The simulation results of the double, switchable, Krummenacher circuit-based feedback application in the CSA with a pulsed reset functionality are presented.

Hepatic function imaging using dynamic Gd-EOB-DTPA enhanced MRI and pharmacokinetic modeling.

PubMed

Ning, Jia; Yang, Zhiying; Xie, Sheng; Sun, Yongliang; Yuan, Chun; Chen, Huijun

2017-10-01

To determine whether pharmacokinetic modeling parameters with different output assumptions of dynamic contrast-enhanced MRI (DCE-MRI) using Gd-EOB-DTPA correlate with serum-based liver function tests, and compare the goodness of fit of the different output assumptions. A 6-min DCE-MRI protocol was performed in 38 patients. Four dual-input two-compartment models with different output assumptions and a published one-compartment model were used to calculate hepatic function parameters. The Akaike information criterion fitting error was used to evaluate the goodness of fit. Imaging-based hepatic function parameters were compared with blood chemistry using correlation with multiple comparison correction. The dual-input two-compartment model assuming venous flow equals arterial flow plus portal venous flow and no bile duct output better described the liver tissue enhancement with low fitting error and high correlation with blood chemistry. The relative uptake rate Kir derived from this model was found to be significantly correlated with direct bilirubin (r = -0.52, P = 0.015), prealbumin concentration (r = 0.58, P = 0.015), and prothrombin time (r = -0.51, P = 0.026). It is feasible to evaluate hepatic function by proper output assumptions. The relative uptake rate has the potential to serve as a biomarker of function. Magn Reson Med 78:1488-1495, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Stopping dynamics of a steady uniform granular flow over a rough incline

NASA Astrophysics Data System (ADS)

Deboeuf, Stéphanie; Saingier, Guillaume; Thiruvalluvar, Nitharshini; Lagrée, Pierre-Yves; Popinet, Stéphane; Staron, Lydie

2017-06-01

Granular material flowing on complex topographies are ubiquitous in industrial and geophysical situations. Even model granular flows are difficult to understand and predict. Recently, the frictional rheology μ(I) -describing the ratio of the shear stress to the normal stress as a function of the inertial number I, that compares inertial and confinement effects- allows unifying different configurations of granular flows. However it does not succeed in describing some phenomenologies, such as creep flow, deposit height, … Is it attributable to the rheology, to non-local effects, ...? Here, we consider a thin layer of grains flowing steadily and uniformly on a rough incline, when the input mass flow rate is suddenly stopped. We focus on the arrest dynamics by using both experimental and numerical approaches. We measure the height and surface velocities of the granular layer during the long-time stopping dynamics and we compare our experimental results with computations of depthaveraged equations for a fluid of rheology μ(I).

An in vitro test bench reproducing coronary blood flow signals.

PubMed

Chodzyński, Kamil Jerzy; Boudjeltia, Karim Zouaoui; Lalmand, Jacques; Aminian, Adel; Vanhamme, Luc; de Sousa, Daniel Ribeiro; Gremmo, Simone; Bricteux, Laurent; Renotte, Christine; Courbebaisse, Guy; Coussement, Grégory

2015-08-07

It is a known fact that blood flow pattern and more specifically the pulsatile time variation of shear stress on the vascular wall play a key role in atherogenesis. The paper presents the conception, the building and the control of a new in vitro test bench that mimics the pulsatile flows behavior based on in vivo measurements. An in vitro cardiovascular simulator is alimented with in vivo constraints upstream and provided with further post-processing analysis downstream in order to mimic the pulsatile in vivo blood flow quantities. This real-time controlled system is designed to perform real pulsatile in vivo blood flow signals to study endothelial cells' behavior under near physiological environment. The system is based on an internal model controller and a proportional-integral controller that controls a linear motor with customized piston pump, two proportional-integral controllers that control the mean flow rate and temperature of the medium. This configuration enables to mimic any resulting blood flow rate patterns between 40 and 700 ml/min. In order to feed the system with reliable periodic flow quantities in vivo measurements were performed. Data from five patients (1 female, 4 males; ages 44-63) were filtered and post-processed using the Newtonian Womersley's solution. These resulting flow signals were compared with 2D axisymmetric, numerical simulation using a Carreau non-Newtonian model to validate the approximation of a Newtonian behavior. This in vitro test bench reproduces the measured flow rate time evolution and the complexity of in vivo hemodynamic signals within the accuracy of the relative error below 5%. This post-processing method is compatible with any real complex in vivo signal and demonstrates the heterogeneity of pulsatile patterns in coronary arteries among of different patients. The comparison between analytical and numerical solution demonstrate the fair quality of the Newtonian Womersley's approximation. Therefore, Womersley's solution was used to calculate input flow rate for the in vitro test bench.

PRELIMINARY DESIGN ANALYSIS OF AXIAL FLOW TURBINES

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1994-01-01

A computer program has been developed for the preliminary design analysis of axial-flow turbines. Rapid approximate generalized procedures requiring minimum input are used to provide turbine overall geometry and performance adequate for screening studies. The computations are based on mean-diameter flow properties and a stage-average velocity diagram. Gas properties are assumed constant throughout the turbine. For any given turbine, all stages, except the first, are specified to have the same shape velocity diagram. The first stage differs only in the value of inlet flow angle. The velocity diagram shape depends upon the stage work factor value and the specified type of velocity diagram. Velocity diagrams can be specified as symmetrical, zero exit swirl, or impulse; or by inputting stage swirl split. Exit turning vanes can be included in the design. The 1991 update includes a generalized velocity diagram, a more flexible meanline path, a reheat model, a radial component of velocity, and a computation of free-vortex hub and tip velocity diagrams. Also, a loss-coefficient calibration was performed to provide recommended values for airbreathing engine turbines. Input design requirements include power or pressure ratio, mass flow rate, inlet temperature and pressure, and rotative speed. The design variables include inlet and exit diameters, stator angle or exit radius ratio, and number of stages. Gas properties are input as gas constant, specific heat ratio, and viscosity. The program output includes inlet and exit annulus dimensions, exit temperature and pressure, total and static efficiencies, flow angles, blading angles, and last stage absolute and relative Mach numbers. This program is written in FORTRAN 77 and can be ported to any computer with a standard FORTRAN compiler which supports NAMELIST. It was originally developed on an IBM 7000 series computer running VM and has been implemented on IBM PC computers and compatibles running MS-DOS under Lahey FORTRAN, and DEC VAX series computers running VMS. Format statements in the code may need to be rewritten depending on your FORTRAN compiler. The source code and sample data are available on a 5.25 inch 360K MS-DOS format diskette. This program was developed in 1972 and was last updated in 1991. IBM and IBM PC are registered trademarks of International Business Machines. MS-DOS is a registered trademark of Microsoft Corporation. DEC VAX, and VMS are trademarks of Digital Equipment Corporation.

ITS component specification. Appendix B, Input data flows for components

DOT National Transportation Integrated Search

1997-11-01

The objective of the Polaris Project is to define an Intelligent Transportation Systems (ITS) architecture for the state of Minnesota. This appendix defines the input data flows for each component of the Polaris Physical Architecture.

Culvert analysis program for indirect measurement of discharge

USGS Publications Warehouse

Fulford, Janice M.; ,

1993-01-01

A program based on the U.S. Geological Survey (USGS) methods for indirectly computing peak discharges through culverts allows users to employ input data formats used by the water surface profile program (WSPRO). The program can be used to compute discharge rating surfaces or curves that describe the behavior of flow through a particular culvert or to compute discharges from measurements of upstream of the gradually varied flow equations and has been adapted slightly to provide solutions that minimize the need for the user to determine between different flow regimes. The program source is written in Fortran 77 and has been run on mini-computers and personal computers. The program does not use or require graphics capability, a color monitor, or a mouse.

Hydrogeology and Simulated Ground-Water Flow in the Salt Pond Region of Southern Rhode Island

USGS Publications Warehouse

Masterson, John P.; Sorenson, Jason R.; Stone, Janet R.; Moran, S. Bradley; Hougham, Andrea

2007-01-01

The Salt Pond region of southern Rhode Island extends from Westerly to Narragansett Bay and forms the natural boundary between the Atlantic Ocean and the shallow, highly permeable freshwater aquifer of the South Coastal Basin. Large inputs of fresh ground water coupled with the low flushing rates to the open ocean make the salt ponds particularly susceptible to eutrophication and bacterial contamination. Ground-water discharge to the salt ponds is an important though poorly quantified source of contaminants, such as dissolved nutrients. A ground-water-flow model was developed and used to delineate the watersheds to the salt ponds, including the areas that contribute ground water directly to the ponds and the areas that contribute ground water to streams that flow into ponds. The model also was used to calculate ground-water fluxes to these coastal areas for long-term average conditions. As part of the modeling analysis, adjustments were made to model input parameters to assess potential uncertainties in model-calculated watershed delineations and in ground-water discharge to the salt ponds. The results of the simulations indicate that flow to the salt ponds is affected primarily by the ease with which water is transmitted through a glacial moraine deposit near the regional ground-water divide, and by the specified recharge rate used in the model simulations. The distribution of the total freshwater flow between direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds is affected primarily by simulated stream characteristics, including the streambed-aquifer connection and the stream stage. The simulated position of the ground-water divide and, therefore, the model-calculated watershed delineations for the salt ponds, were affected only by changes in the transmissivity of the glacial moraine. Selected changes in other simulated hydraulic parameters had substantial effects on total freshwater discharge and the distribution of direct ground-water discharge and ground-water-derived surface-water (streamflow) discharge to the salt ponds, but still provided a reasonable match to the hydrologic data available for model calibration. To reduce the uncertainty in predictions of watershed areas and ground-water discharge to the salt ponds, additional hydrogeologic data would be required to constrain the model input parameters that have the greatest effect on the simulation results.

In-line wear monitor. Final report, July 1988-April 1989

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pieper, K.A.; Taylor, I.J.

This report describes construction and test results of an in-line monitor for critical ferrous and nonferrous metal debris in turbine engine lubrication systems. The in-line wear monitor (ILWM) uses the X-ray fluorescence principle for detecting metal debris on a continuous basis while the engine is running. The sensor portion of the system is engine mounted and contains a radioactive X-ray source, a flow cell to direct the oil across an X-ray permeable window, a proportional counter X-ray detector and its associated preamplifier and amplifier electronics. The data acquisition electronics is mounted on the airframe and contains a microprocessor based systemmore » for inputting pulses from the sensor, classifying and counting them according to energy bands, and analyzing the data and outputting metal concentration values to the engine monitoring system. The sensor portion of the system is designed to fit on a TF41 turbine engine in place of a tube between the oil tank and the oil pump. A TF41 engine monitoring system has been modified to accept the new signals from the ILWM on spare inputs so that none of the existing functions were disturbed. The ILWM has been flow tested at various flow rates, concentration levels, oil temperatures, and aerations. The wear monitor detected iron, copper, and both iron and copper together with less than 2 ppm one sigma statistical uncertainty for 30 minute count times over the 0-50 ppm range. There was no significant effect of flow rate or aeration on accuracy. The system is developed to the point that it can be tested in an actual flight environment.« less

The effect of river pulsing on sedimentation and nutrients in created riparian wetlands.

PubMed

Nahlik, Amanda M; Mitsch, William J

2008-01-01

Sedimentation under pulsed and steady-flow conditions was investigated in two created flow-through riparian wetlands in central Ohio over 2 yr. Hydrologic pulses of river water lasting for 6 to 8 d were imposed on each wetland from January through June during 2004. Mean inflow rates during pulses averaged 52 and 7 cm d(-1) between pulses. In 2005, the wetlands received a steady-flow regime of 11 cm d(-1) with no major hydrologic fluctuations. Thirty-two sediment traps were deployed and sampled once per month in April, May, June, and July for two consecutive years in each wetland. January through March were not sampled in either year due to frozen water surfaces in the wetlands. Gross sedimentation (sedimentation without normalizing for differences between years) was significantly greater in the pulsing study period (90 kg m(-2)) than in the steady-flow study period (64 kg m(-2)). When normalized for different hydrologic and total suspended solid inputs between years, sedimentation for April through July was not significantly different between pulsing and steady-flow study periods. Sedimentation for the 3 mo that received hydrologic pulses (April, May, and June) was significantly lower during pulsing months than in the corresponding steady-flow months. Large fractions of inorganic matter in collected sediments indicated that allochthonous inputs were the main contributor to sedimentation in these wetlands. Organic matter fractions of collected sediments were consistently greater in the steady-flow study period (1.8 g kg(-1)) than in the pulsed study period (1.5 g kg(-1)), consistent with greater primary productivity in the water column during steady-flow conditions.

Vibration Power Flow In A Constrained Layer Damping Cylindrical Shell

NASA Astrophysics Data System (ADS)

Wang, Yun; Zheng, Gangtie

2012-07-01

In this paper, the vibration power flow in a constrained layer damping (CLD) cylindrical shell using wave propagation approach is investigated. The dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumption. With these equations, the dynamic responses of the system under a line circumferential cosine harmonic exciting force is obtained by employing the Fourier transform and the residue theorem. The vibration power flows inputted to the system and transmitted along the shell axial direction are both studied. The results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer can obviously restrict the exciting force from inputting power flow into the base shell especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order, can rapidly attenuate the vibration power flow transmitted along the base shell axial direction.

Computer program for aerodynamic and blading design of multistage axial-flow compressors

NASA Technical Reports Server (NTRS)

Crouse, J. E.; Gorrell, W. T.

1981-01-01

A code for computing the aerodynamic design of a multistage axial-flow compressor and, if desired, the associated blading geometry input for internal flow analysis codes is presented. Compressible flow, which is assumed to be steady and axisymmetric, is the basis for a two-dimensional solution in the meridional plane with viscous effects modeled by pressure loss coefficients and boundary layer blockage. The radial equation of motion and the continuity equation are solved with the streamline curvature method on calculation stations outside the blade rows. The annulus profile, mass flow, pressure ratio, and rotative speed are input. A number of other input parameters specify and control the blade row aerodynamics and geometry. In particular, blade element centerlines and thicknesses can be specified with fourth degree polynomials for two segments. The output includes a detailed aerodynamic solution and, if desired, blading coordinates that can be used for internal flow analysis codes.

Documentation of a computer program to simulate stream-aquifer relations using a modular, finite-difference, ground-water flow model

USGS Publications Warehouse

Prudic, David E.

1989-01-01

Computer models are widely used to simulate groundwater flow for evaluating and managing the groundwater resource of many aquifers, but few are designed to also account for surface flow in streams. A computer program was written for use in the US Geological Survey modular finite difference groundwater flow model to account for the amount of flow in streams and to simulate the interaction between surface streams and groundwater. The new program is called the Streamflow-Routing Package. The Streamflow-Routing Package is not a true surface water flow model, but rather is an accounting program that tracks the flow in one or more streams which interact with groundwater. The program limits the amount of groundwater recharge to the available streamflow. It permits two or more streams to merge into one with flow in the merged stream equal to the sum of the tributary flows. The program also permits diversions from streams. The groundwater flow model with the Streamflow-Routing Package has an advantage over the analytical solution in simulating the interaction between aquifer and stream because it can be used to simulate complex systems that cannot be readily solved analytically. The Streamflow-Routing Package does not include a time function for streamflow but rather streamflow entering the modeled area is assumed to be instantly available to downstream reaches during each time period. This assumption is generally reasonable because of the relatively slow rate of groundwater flow. Another assumption is that leakage between streams and aquifers is instantaneous. This assumption may not be reasonable if the streams and aquifers are separated by a thick unsaturated zone. Documentation of the Streamflow-Routing Package includes data input instructions; flow charts, narratives, and listings of the computer program for each of four modules; and input data sets and printed results for two test problems, and one example problem. (Lantz-PTT)

A novel miniature dynamic microfluidic cell culture platform using electro-osmosis diode pumping.

PubMed

Chang, Jen-Yung; Wang, Shuo; Allen, Jeffrey S; Lee, Seong Hyuk; Chang, Suk Tai; Choi, Young-Ki; Friedrich, Craig; Choi, Chang Kyoung

2014-07-01

An electro-osmosis (EOS) diode pumping platform capable of culturing cells in fluidic cellular micro-environments particularly at low volume flow rates has been developed. Diode pumps have been shown to be a viable alternative to mechanically driven pumps. Typically electrokinetic micro-pumps were limited to low-concentration solutions (≤10 mM). In our approach, surface mount diodes were embedded along the sidewalls of a microchannel to rectify externally applied alternating current into pulsed direct current power across the diodes in order to generate EOS flows. This approach has for the first time generated flows at ultra-low flow rates (from 2.0 nl/s to 12.3 nl/s) in aqueous solutions with concentrations greater than 100 mM. The range of flow was generated by changing the electric field strength applied to the diodes from 0.5 Vpp/cm to 10 Vpp/cm. Embedding an additional diode on the upper surface of the enclosed microchannel increased flow rates further. We characterized the diode pump-driven fluidics in terms of intensities and frequencies of electric inputs, pH values of solutions, and solution types. As part of this study, we found that the growth of A549 human lung cancer cells was positively affected in the microfluidic diode pumping system. Though the chemical reaction compromised the fluidic control overtime, the system could be maintained fully functional over a long time if the solution was changed every hour. In conclusion, the advantage of miniature size and ability to accurately control fluids at ultra-low volume flow rates can make this diode pumping system attractive to lab-on-a-chip applications and biomedical engineering in vitro studies.

A novel miniature dynamic microfluidic cell culture platform using electro-osmosis diode pumping

PubMed Central

Chang, Jen-Yung; Wang, Shuo; Allen, Jeffrey S.; Lee, Seong Hyuk; Chang, Suk Tai; Choi, Young-Ki; Friedrich, Craig; Choi, Chang Kyoung

2014-01-01

An electro-osmosis (EOS) diode pumping platform capable of culturing cells in fluidic cellular micro-environments particularly at low volume flow rates has been developed. Diode pumps have been shown to be a viable alternative to mechanically driven pumps. Typically electrokinetic micro-pumps were limited to low-concentration solutions (≤10 mM). In our approach, surface mount diodes were embedded along the sidewalls of a microchannel to rectify externally applied alternating current into pulsed direct current power across the diodes in order to generate EOS flows. This approach has for the first time generated flows at ultra-low flow rates (from 2.0 nl/s to 12.3 nl/s) in aqueous solutions with concentrations greater than 100 mM. The range of flow was generated by changing the electric field strength applied to the diodes from 0.5 Vpp/cm to 10 Vpp/cm. Embedding an additional diode on the upper surface of the enclosed microchannel increased flow rates further. We characterized the diode pump-driven fluidics in terms of intensities and frequencies of electric inputs, pH values of solutions, and solution types. As part of this study, we found that the growth of A549 human lung cancer cells was positively affected in the microfluidic diode pumping system. Though the chemical reaction compromised the fluidic control overtime, the system could be maintained fully functional over a long time if the solution was changed every hour. In conclusion, the advantage of miniature size and ability to accurately control fluids at ultra-low volume flow rates can make this diode pumping system attractive to lab-on-a-chip applications and biomedical engineering in vitro studies. PMID:25379101

Kinetic Characteristics of Hydrogen Transfer Through Palladium-Modified Membrane

NASA Astrophysics Data System (ADS)

Petriev, I. S.; Frolov, V. Yu.; Bolotin, S. N.; Baryshev, M. G.; Kopytov, G. F.

2018-01-01

The paper deals with hydrogen transfer through Pd-23%Ag alloy membrane, the surface of which is modified by the electrolytic deposition of highly dispersed palladium. The dependence between the density of hydrogen flow and its excess pressure on the input surface of membrane is well approximated by the first-order curve. This fact indicates that the process of hydrogen permeability is defined by its dissociation on the input surface. Activation energy of this process is 47.9 kJ/mol which considerably exceeds that of the process of hydrogen transfer through palladium (22-30 kJ/mol). This confirms the fact that the chemisorption is a rate-controlling step of the hydrogen transfer through membrane.

An efficient user-oriented method for calculating compressible flow in an about three-dimensional inlets. [panel method

NASA Technical Reports Server (NTRS)

Hess, J. L.; Mack, D. P.; Stockman, N. O.

1979-01-01

A panel method is used to calculate incompressible flow about arbitrary three-dimensional inlets with or without centerbodies for four fundamental flow conditions: unit onset flows parallel to each of the coordinate axes plus static operation. The computing time is scarcely longer than for a single solution. A linear superposition of these solutions quite rigorously gives incompressible flow about the inlet for any angle of attack, angle of yaw, and mass flow rate. Compressibility is accounted for by applying a well-proven correction to the incompressible flow. Since the computing times for the combination and the compressibility correction are small, flows at a large number of inlet operating conditions are obtained rather cheaply. Geometric input is aided by an automatic generating program. A number of graphical output features are provided to aid the user, including surface streamline tracing and automatic generation of curves of curves of constant pressure, Mach number, and flow inclination at selected inlet cross sections. The inlet method and use of the program are described. Illustrative results are presented.

Doppler flowmeter

DOEpatents

Karplus, H.H.B.; Raptis, A.C.

1981-11-13

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

Doppler flowmeter

DOEpatents

Karplus, Henry H. B.; Raptis, Apostolos C.

1983-01-01

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

A probabilistic model of debris-flow delivery to stream channels, demonstrated for the Coast Range of Oregon, USA

Treesearch

Daniel J. Miller; Kelly M. Burnett

2008-01-01

Debris flows are important geomorphic agents in mountainous terrains that shape channel environments and add a dynamic element to sediment supply and channel disturbance. Identification of channels susceptible to debris-flow inputs of sediment and organic debris, and quantification of the likelihood and magnitude of those inputs, are key tasks for characterizing...

Quantification of Skeletal Blood Flow and Fluoride Metabolism in Rats using PET in a Pre-Clinical Stress Fracture Model

PubMed Central

Tomlinson, Ryan E.; Silva, Matthew J.; Shoghi, Kooresh I.

2013-01-01

Purpose Blood flow is an important factor in bone production and repair, but its role in osteogenesis induced by mechanical loading is unknown. Here, we present techniques for evaluating blood flow and fluoride metabolism in a pre-clinical stress fracture model of osteogenesis in rats. Procedures Bone formation was induced by forelimb compression in adult rats. 15O water and 18F fluoride PET imaging were used to evaluate blood flow and fluoride kinetics 7 days after loading. 15O water was modeled using a one-compartment, two-parameter model, while a two-compartment, three-parameter model was used to model 18F fluoride. Input functions were created from the heart, and a stochastic search algorithm was implemented to provide initial parameter values in conjunction with a Levenberg–Marquardt optimization algorithm. Results Loaded limbs are shown to have a 26% increase in blood flow rate, 113% increase in fluoride flow rate, 133% increase in fluoride flux, and 13% increase in fluoride incorporation into bone as compared to non-loaded limbs (p < 0.05 for all results). Conclusions The results shown here are consistent with previous studies, confirming this technique is suitable for evaluating the vascular response and mineral kinetics of osteogenic mechanical loading. PMID:21785919

Flow separation in a computational oscillating vocal fold model

NASA Astrophysics Data System (ADS)

Alipour, Fariborz; Scherer, Ronald C.

2004-09-01

A finite-volume computational model that solves the time-dependent glottal airflow within a forced-oscillation model of the glottis was employed to study glottal flow separation. Tracheal input velocity was independently controlled with a sinusoidally varying parabolic velocity profile. Control parameters included flow rate (Reynolds number), oscillation frequency and amplitude of the vocal folds, and the phase difference between the superior and inferior glottal margins. Results for static divergent glottal shapes suggest that velocity increase caused glottal separation to move downstream, but reduction in velocity increase and velocity decrease moved the separation upstream. At the fixed frequency, an increase of amplitude of the glottal walls moved the separation further downstream during glottal closing. Increase of Reynolds number caused the flow separation to move upstream in the glottis. The flow separation cross-sectional ratio ranged from approximately 1.1 to 1.9 (average of 1.47) for the divergent shapes. Results suggest that there may be a strong interaction of rate of change of airflow, inertia, and wall movement. Flow separation appeared to be ``delayed'' during the vibratory cycle, leading to movement of the separation point upstream of the glottal end only after a significant divergent angle was reached, and to persist upstream into the convergent phase of the cycle.

A Design Methodology for Optoelectronic VLSI

DTIC Science & Technology

2007-01-01

current gets converted to a CMOS voltage level through a transimpedance amplifier circuit called a receiver. The output of the receiver is then...change the current flowing from the diode to a voltage that the logic inputs can use. That circuit is called a receiver. It is a transimpedance amplifier ...incorpo- rate random access memory circuits, SRAM or dynamic RAM (DRAM). These circuits use weak internal analog signals that are amplified by sense

Characterization of Modified Tapioca Starch Solutions and Their Sprays for High Temperature Coating Applications

PubMed Central

Naz, M. Y.; Sulaiman, S. A.; Ariwahjoedi, B.; Shaari, Ku Zilati Ku

2014-01-01

The objective of the research was to understand and improve the unusual physical and atomization properties of the complexes/adhesives derived from the tapioca starch by addition of borate and urea. The characterization of physical properties of the synthesized adhesives was carried out by determining the effect of temperature, shear rate, and mass concentration of thickener/stabilizer on the complex viscosity, density, and surface tension. In later stage, phenomenological analyses of spray jet breakup of heated complexes were performed in still air. Using a high speed digital camera, the jet breakup dynamics were visualized as a function of the system input parameters. The further analysis of the grabbed images confirmed the strong influence of the input processing parameters on full cone spray patternation. It was also predicted that the heated starch adhesive solutions generate a dispersed spray pattern by utilizing the partial evaporation of the spraying medium. Below 40°C of heating temperature, the radial spray cone width and angle did not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The discharge coefficient, mean flow rate, and mean flow velocity were significantly influenced by the load pressure but less affected by the temperature. PMID:24592165

Role of modern climate and hydrology in world oil preservation

NASA Astrophysics Data System (ADS)

Szatmari, Peter

1992-12-01

The accumulation of oil requires a favorable source, a reservoir, good seal-rock quality, and suitably timed thermal history and structuring. The accumulated oil, especially its light fractions, may be subsequently removed by hydrologically controlled processes such as water washing, biodegradation, and tilting of the oil-water contact. These processes are dependent on the climate. In regions that have become increasingly cold or dry during late Cenozoic time, low rainfall, low ground-water flow rates, and low input of nutrients and microorganisms have protected the oil; in warm or temperate rainy climates, high flow rates and high input of nutrients and microorganisms have led to partial or total removal of oil. Thus, most of the rich (>500 000 barrels/day) oil provinces on land are in cold or dry regions, where water is recharged in highlands that receive little rain (<500 mm/yr), such as Texas, Oklahoma, Wyoming, Alaska's North Slope, California, Algeria, Libya, Egypt, the Middle East, the Volga-Ural basin, and western Siberia. Where upland recharge areas are warm or temperate and rainy, as in the eastern United States, western Europe, sub-Saharan Africa, Brazil, India, and most of China, rich oil provinces on land (outside young deltas) are rare, and biodegradation is widespread.

Simulation of a 20-ton LiBr/H{sub 2}O absorption cooling system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wardono, B.; Nelson, R.M.

The possibility of using solar energy as the main heat input for cooling systems has led to several studies of available cooling technologies that use solar energy. The results show that double-effect absorption cooling systems give relatively high performance. To further study absorption cooling systems, a computer code was developed for a double-effect lithium bromide/water (LiBr/H{sub 2}O) absorption system. To evaluate the performance, two objective functions were developed including the coefficient of performance (COP) and the system cost. Based on the system cost, an optimization to find the minimum cost was performed to determine the nominal heat transfer areas ofmore » each heat exchanger. The nominal values of other system variables, such as the mass flow rates and inlet temperatures of the hot water, cooling water, and chilled water, are specified as commonly used values for commercial machines. The results of the optimization show that there are optimum heat transfer areas. In this study, hot water is used as the main energy input. Using a constant load of 20 tons cooling capacity, the effects of various variables including the heat transfer ares, mass flow rates, and inlet temperatures of hot water, cooling water, and chilled water are presented.« less

Integrated Geothermal-CO2 Storage Reservoirs: FY1 Final Report

DOE Data Explorer

Buscheck, Thomas A.

2012-01-01

The purpose of phase 1 is to determine the feasibility of integrating geologic CO2 storage (GCS) with geothermal energy production. Phase 1 includes reservoir analyses to determine injector/producer well schemes that balance the generation of economically useful flow rates at the producers with the need to manage reservoir overpressure to reduce the risks associated with overpressure, such as induced seismicity and CO2 leakage to overlying aquifers. This submittal contains input and output files of the reservoir model analyses. A reservoir-model "index-html" file was sent in a previous submittal to organize the reservoir-model input and output files according to sections of the FY1 Final Report to which they pertain. The recipient should save the file: Reservoir-models-inputs-outputs-index.html in the same directory that the files: Section2.1.*.tar.gz files are saved in.

Calibration, Data Acquisition, and Post Analysis of Turbulent Fluid Flow in a Calibration Jet Using Hot-wire Anemometry

NASA Technical Reports Server (NTRS)

Moreno, Michelle

2004-01-01

The Turbine Branch concentrates on the following areas: Computational Fluid Dynamics (CFD), and implementing experimental procedures to obtain physical modeling data. Hot-wire Anemometry is a valuable tool for obtaining physical modeling data. Hot-wire Anemometry is likely to remain the principal research tool for most turbulent air/gas flow studies. The Hot-wire anemometer consists of a fine wire heated by electric current. When placed in a fluid stream, the hot-wire loses heat to the fluid by forced convection. In forced convection, energy transfer is due to molecular motion imposed by an extraneous force moving fluid parcels. When the hot-wire is in "equilibrium", the rate of heat input to the wire is equal to the rate of heat loss at the wire ends. The equality between heat input and heat loss is the basis for King s equation, which relates the electrical parameters of the hot-wire to the flow parameters of the fluid. Hot-wire anemometry is based on convective heat transfer from a heated wire element placed in a fluid flow. Any change in the fluid flow condition that affects the heat transfer from the heated element will be detected virtually instantaneously by a constant-temperature Hot-wire anemometry system. The system implemented for this research is the IFA 300. The system is a fully-integrated, thermal anemometer-based system that measures mean and fluctuating velocity components in air, water, and other fluids. It also measures turbulence and makes localized temperature measurements. A constant-temperature anemometer is a bridge and amplifier circuit that controls a tiny wire at constant temperature. As a fluid flow passes over the heated sensor, the amplifier senses the bridge off-balance and adjusts the voltage to the top of the bridge, keeping the bridge in balance. The voltage on top of the bridge can then be related to the velocity of the flow. The bridge voltage is sensitive to temperature as well as velocity and so the built-in thermocouple circuit can be attached to a thermocouple that can measure the fluid temperature. Additional information is included in the original extended abstract.

High-Performance Nanocomposites Designed for Radiation Shielding in Space and an Application of GIS for Analyzing Nanopowder Dispersion in Polymer Matrixes

NASA Astrophysics Data System (ADS)

Auslander, Joseph Simcha

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Time-Resolved Magneto-Optical Imaging of Superconducting YBCO Thin Films in the High-Frequency AC Current Regime

NASA Astrophysics Data System (ADS)

Frey, Alexander

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Use of Remote Sensing to Identify Essential Habitat for Aeschynomene virginica (L.) BSP, a Threatened Tidal Freshwater Wetland Plant

NASA Astrophysics Data System (ADS)

Mountz, Elizabeth M.

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Silver-Polyimide Nanocomposite Films: Single-Stage Synthesis and Analysis of Metalized Partially-Fluorinated Polyimide BTDA/4-BDAF Prepared from Silver(I) Complexes

NASA Astrophysics Data System (ADS)

Abelard, Joshua Erold Robert

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Multifunctional Polymer Synthesis and Incorporation of Gadolinium Compounds and Modified Tungsten Nanoparticles for Improvement of Radiation Shielding for use in Outer Space

NASA Astrophysics Data System (ADS)

Harbert, Emily Grace

We begin by defining the concept of `open' Markov processes, which are continuous-time Markov chains where probability can flow in and out through certain `boundary' states. We study open Markov processes which in the absence of such boundary flows admit equilibrium states satisfying detailed balance, meaning that the net flow of probability vanishes between all pairs of states. External couplings which fix the probabilities of boundary states can maintain such systems in non-equilibrium steady states in which non-zero probability currents flow. We show that these non-equilibrium steady states minimize a quadratic form which we call 'dissipation.' This is closely related to Prigogine's principle of minimum entropy production. We bound the rate of change of the entropy of a driven non-equilibrium steady state relative to the underlying equilibrium state in terms of the flow of probability through the boundary of the process. We then consider open Markov processes as morphisms in a symmetric monoidal category by splitting up their boundary states into certain sets of `inputs' and `outputs.' Composition corresponds to gluing the outputs of one such open Markov process onto the inputs of another so that the probability flowing out of the first process is equal to the probability flowing into the second. Tensoring in this category corresponds to placing two such systems side by side. We construct a `black-box' functor characterizing the behavior of an open Markov process in terms of the space of possible steady state probabilities and probability currents along the boundary. The fact that this is a functor means that the behavior of a composite open Markov process can be computed by composing the behaviors of the open Markov processes from which it is composed. We prove a similar black-boxing theorem for reaction networks whose dynamics are given by the non-linear rate equation. Along the way we describe a more general category of open dynamical systems where composition corresponds to gluing together open dynamical systems.

Multi-metric calibration of hydrological model to capture overall flow regimes

NASA Astrophysics Data System (ADS)

Zhang, Yongyong; Shao, Quanxi; Zhang, Shifeng; Zhai, Xiaoyan; She, Dunxian

2016-08-01

Flow regimes (e.g., magnitude, frequency, variation, duration, timing and rating of change) play a critical role in water supply and flood control, environmental processes, as well as biodiversity and life history patterns in the aquatic ecosystem. The traditional flow magnitude-oriented calibration of hydrological model was usually inadequate to well capture all the characteristics of observed flow regimes. In this study, we simulated multiple flow regime metrics simultaneously by coupling a distributed hydrological model with an equally weighted multi-objective optimization algorithm. Two headwater watersheds in the arid Hexi Corridor were selected for the case study. Sixteen metrics were selected as optimization objectives, which could represent the major characteristics of flow regimes. Model performance was compared with that of the single objective calibration. Results showed that most metrics were better simulated by the multi-objective approach than those of the single objective calibration, especially the low and high flow magnitudes, frequency and variation, duration, maximum flow timing and rating. However, the model performance of middle flow magnitude was not significantly improved because this metric was usually well captured by single objective calibration. The timing of minimum flow was poorly predicted by both the multi-metric and single calibrations due to the uncertainties in model structure and input data. The sensitive parameter values of the hydrological model changed remarkably and the simulated hydrological processes by the multi-metric calibration became more reliable, because more flow characteristics were considered. The study is expected to provide more detailed flow information by hydrological simulation for the integrated water resources management, and to improve the simulation performances of overall flow regimes.

Efficient “Communication through Coherence” Requires Oscillations Structured to Minimize Interference between Signals

PubMed Central

Akam, Thomas E.; Kullmann, Dimitri M.

2012-01-01

The ‘communication through coherence’ (CTC) hypothesis proposes that selective communication among neural networks is achieved by coherence between firing rate oscillation in a sending region and gain modulation in a receiving region. Although this hypothesis has stimulated extensive work, it remains unclear whether the mechanism can in principle allow reliable and selective information transfer. Here we use a simple mathematical model to investigate how accurately coherent gain modulation can filter a population-coded target signal from task-irrelevant distracting inputs. We show that selective communication can indeed be achieved, although the structure of oscillatory activity in the target and distracting networks must satisfy certain previously unrecognized constraints. Firstly, the target input must be differentiated from distractors by the amplitude, phase or frequency of its oscillatory modulation. When distracting inputs oscillate incoherently in the same frequency band as the target, communication accuracy is severely degraded because of varying overlap between the firing rate oscillations of distracting inputs and the gain modulation in the receiving region. Secondly, the oscillatory modulation of the target input must be strong in order to achieve a high signal-to-noise ratio relative to stochastic spiking of individual neurons. Thus, whilst providing a quantitative demonstration of the power of coherent oscillatory gain modulation to flexibly control information flow, our results identify constraints imposed by the need to avoid interference between signals, and reveal a likely organizing principle for the structure of neural oscillations in the brain. PMID:23144603

Drift-Scale Coupled Processes (DST and THC Seepage) Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

E. Gonnenthal; N. Spyoher

The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [153447]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THCmore » Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: (1) Performance Assessment (PA); (2) Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); (3) UZ Flow and Transport Process Model Report (PMR); and (4) Near-Field Environment (NFE) PMR. The work scope for this activity is presented in the TWPs cited above, and summarized as follows: continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are required to fully document and address the requirements of the TWPs.« less

Drift-Scale Coupled Processes (DST and THC Seepage) Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

E. Sonnenthale

The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) 2000 [1534471]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M&O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THCmore » seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: Performance Assessment (PA); Near-Field Environment (NFE) PMR; Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); and UZ Flow and Transport Process Model Report (PMR). The work scope for this activity is presented in the TWPs cited above, and summarized as follows: Continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are required to fully document and address the requirements of the TWPs.« less

TACT 1: A computer program for the transient thermal analysis of a cooled turbine blade or vane equipped with a coolant insert. 2. Programmers manual

NASA Technical Reports Server (NTRS)

Gaugler, R. E.

1979-01-01

A computer program to calculate transient and steady state temperatures, pressures, and coolant flows in a cooled axial flow turbine blade or vane with an impingement insert is described. Coolant-side heat transfer coefficients are calculated internally in the program, with the user specifying either impingement or convection heat transfer at each internal flow station. Spent impingement air flows in a chordwise direction and is discharged through the trailing edge and through film cooling holes. The ability of the program to handle film cooling is limited by the internal flow model. Input to the program includes a description of the blade geometry, coolant-supply conditions, outside thermal boundary conditions, and wheel speed. The blade wall can have two layers of different materials, such as a ceramic thermal barrier coating over a metallic substrate. Program output includes the temperature at each node, the coolant pressures and flow rates, and the coolant-side heat transfer coefficients.

Stokes Approach to Preferential Flow at the Darcy-Scale

NASA Astrophysics Data System (ADS)

Germann, Peter; Bogner, Christina

2017-04-01

Preferential Flow in soils is fast, limited to infiltration and occupies but a small portion of porosity. However, how fast is it, how much water is involved, what is its flow rate, and how far is it carried? Supported with numerous measurements a Stokes approach to preferential flow provides the answers at the operational Darcy-scale. The approach to preferential flow in permeable media (pm) stresses momentum dissipation during viscous flow. Thus, a laminar water film percolates through a pm. The dynamic film is initially determined by the thickness F (m) and the specific contact area L (m2 m-3) per unit volume of the medium. Input to the medium's surface is a pulse with volume flux density q (ms-1) that starts and ends at times TB and TE. A specific pulse and the intrinsic properties of a pm determine F and L. A water content wave (WCW) envelops the spatio-temporal evolution of a water film. A WCW is completely described with a set of analytical relationships that are based on F, L, and the water's viscosity. The approach is an extension of Hagen-Poiseuille's law of flow in concentric conduits. It also evolves seamlessly from extending Darcy's law into non-saturated pm. Experimental determination of F and L follows either from drainage flow or from rapid soil moisture recordings during the passing of a WCW, for instance, with TDR-equipment. Parameters from numerous infiltration experiments in the field, in soil columns, in sand boxes, and lysimeters demonstrate the approach's broad applicability, thus framing the spatio-temporal extensions, velocities and volume flux densities of preferential flows. The specific contact area L is considered the locus of water, heat, particle and solute transfer between a WCW and the sessile parts of a pm. A recent analysis of delayed Br-breakthrough with respect to drainage flow supports the feasibility of the Stokes approach to preferential flow at the Darcy-scale. A perspective of modeling sequences of input pulses will conclude the presentation.

Calculation of inviscid surface streamlines and heat transfer on shuttle type configurations. Part 2: Description of computer program

NASA Technical Reports Server (NTRS)

Dejarnette, F. R.; Jones, M. H.

1971-01-01

A description of the computer program used for heating rate calculation for blunt bodies in hypersonic flow is given. The main program and each subprogram are described by defining the pertinent symbols involved and presenting a detailed flow diagram and complete computer program listing. Input and output parameters are discussed in detail. Listings are given for the computation of heating rates on (1) a blunted 15 deg half-angle cone at 20 deg incidence and Mach 10.6, (2) a blunted 70 deg slab delta wing at 10 deg incidence and Mach 8, and (3) the HL-10 lifting body at 20 deg incidence and Mach 10. In addition, the computer program output for two streamlines on the blunted 15 deg half-angle cone is listed. For Part 1, see N71-36186.

Modular GIS Framework for National Scale Hydrologic and Hydraulic Modeling Support

NASA Astrophysics Data System (ADS)

Djokic, D.; Noman, N.; Kopp, S.

2015-12-01

Geographic information systems (GIS) have been extensively used for pre- and post-processing of hydrologic and hydraulic models at multiple scales. An extensible GIS-based framework was developed for characterization of drainage systems (stream networks, catchments, floodplain characteristics) and model integration. The framework is implemented as a set of free, open source, Python tools and builds on core ArcGIS functionality and uses geoprocessing capabilities to ensure extensibility. Utilization of COTS GIS core capabilities allows immediate use of model results in a variety of existing online applications and integration with other data sources and applications.The poster presents the use of this framework to downscale global hydrologic models to local hydraulic scale and post process the hydraulic modeling results and generate floodplains at any local resolution. Flow forecasts from ECMWF or WRF-Hydro are downscaled and combined with other ancillary data for input into the RAPID flood routing model. RAPID model results (stream flow along each reach) are ingested into a GIS-based scale dependent stream network database for efficient flow utilization and visualization over space and time. Once the flows are known at localized reaches, the tools can be used to derive the floodplain depth and extent for each time step in the forecast at any available local resolution. If existing rating curves are available they can be used to relate the flow to the depth of flooding, or synthetic rating curves can be derived using the tools in the toolkit and some ancillary data/assumptions. The results can be published as time-enabled spatial services to be consumed by web applications that use floodplain information as an input. Some of the existing online presentation templates can be easily combined with available online demographic and infrastructure data to present the impact of the potential floods on the local community through simple, end user products. This framework has been successfully used in both the data rich environments as well as in locales with minimum available spatial and hydrographic data.

Slope-Area Computation Program Graphical User Interface 1.0—A Preprocessing and Postprocessing Tool for Estimating Peak Flood Discharge Using the Slope-Area Method

USGS Publications Warehouse

Bradley, D. Nathan

2012-01-01

The slope-area method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the cross-sectional geometry of the stream, estimates of channel roughness, and a mathematical model that balances the total energy of the flow between cross sections. This is in contrast to a “direct” measurement of discharge during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a gage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the stream gage, resulting in more accurate computation of high flows. The Slope-Area Computation program (SAC; Fulford, 1994) is an implementation of the slope-area method that computes a peak-discharge estimate from inputs of water-surface slope (from surveyed HWMs), channel geometry, and estimated channel roughness. SAC is a command line program written in Fortran that reads input data from a formatted text file and prints results to another formatted text file. Preparing the input file can be time-consuming and prone to errors. This document describes the SAC graphical user interface (GUI), a crossplatform “wrapper” application that prepares the SAC input file, executes the program, and helps the user interpret the output. The SAC GUI is an update and enhancement of the slope-area method (SAM; Hortness, 2004; Berenbrock, 1996), an earlier spreadsheet tool used to aid field personnel in the completion of a slope-area measurement. The SAC GUI reads survey data, develops a plan-view plot, water-surface profile, cross-section plots, and develops the SAC input file. The SAC GUI also develops HEC-2 files that can be imported into HEC–RAS.

3-D numerical evaluation of density effects on tracer tests.

PubMed

Beinhorn, M; Dietrich, P; Kolditz, O

2005-12-01

In this paper we present numerical simulations carried out to assess the importance of density-dependent flow on tracer plume development. The scenario considered in the study is characterized by a short-term tracer injection phase into a fully penetrating well and a natural hydraulic gradient. The scenario is thought to be typical for tracer tests conducted in the field. Using a reference case as a starting point, different model parameters were changed in order to determine their importance to density effects. The study is based on a three-dimensional model domain. Results were interpreted using concentration contours and a first moment analysis. Tracer injections of 0.036 kg per meter of saturated aquifer thickness do not cause significant density effects assuming hydraulic gradients of at least 0.1%. Higher tracer input masses, as used for geoelectrical investigations, may lead to buoyancy-induced flow in the early phase of a tracer test which in turn impacts further plume development. This also holds true for shallow aquifers. Results of simulations with different tracer injection rates and durations imply that the tracer input scenario has a negligible effect on density flow. Employing model cases with different realizations of a log conductivity random field, it could be shown that small variations of hydraulic conductivity in the vicinity of the tracer injection well have a major control on the local tracer distribution but do not mask effects of buoyancy-induced flow.

Effect of a dual inlet channel on cell loading in microfluidics.

PubMed

Yun, Hoyoung; Kim, Kisoo; Lee, Won Gu

2014-11-01

Unwanted sedimentation and attachment of a number of cells onto the bottom channel often occur on relatively large-scale inlets of conventional microfluidic channels as a result of gravity and fluid shear. Phenomena such as sedimentation have become recognized problems that can be overcome by performing microfluidic experiments properly, such as by calculating a meaningful output efficiency with respect to real input. Here, we present a dual-inlet design method for reducing cell loss at the inlet of channels by adding a new " upstream inlet " to a single main inlet design. The simple addition of an upstream inlet can create a vertically layered sheath flow prior to the main inlet for cell loading. The bottom layer flow plays a critical role in preventing the cells from attaching to the bottom of the channel entrance, resulting in a low possibility of cell sedimentation at the main channel entrance. To provide proof-of-concept validation, we applied our design to a microfabricated flow cytometer system (μFCS) and compared the cell counting efficiency of the proposed μFCS with that of the previous single-inlet μFCS and conventional FCS. We used human white blood cells and fluorescent microspheres to quantitatively evaluate the rate of cell sedimentation in the main inlet and to measure fluorescence sensitivity at the detection zone of the flow cytometer microchip. Generating a sheath flow as the bottom layer was meaningfully used to reduce the depth of field as well as the relative deviation of targets in the z-direction (compared to the x-y flow plane), leading to an increased counting sensitivity of fluorescent detection signals. Counting results using fluorescent microspheres showed both a 40% reduction in the rate of sedimentation and a 2-fold higher sensitivity in comparison with the single-inlet μFCS. The results of CD4(+) T-cell counting also showed that the proposed design results in a 25% decrease in the rate of cell sedimentation and a 28% increase in sensitivity when compared to the single-inlet μFCS. This method is simple and easy to use in design, yet requires no additional time or cost in fabrication. Furthermore, we expect that this approach could potentially be helpful for calculating exact cell loading and counting efficiency for a small input number of cells, such as primary cells and rare cells, in microfluidic channel applications.

Quantifying the fate of agricultural nitrogen in an unconfined aquifer: Stream-based observations at three measurement scales

NASA Astrophysics Data System (ADS)

Gilmore, Troy E.; Genereux, David P.; Solomon, D. Kip; Solder, John E.; Kimball, Briant A.; Mitasova, Helena; Birgand, François

2016-03-01

We compared three stream-based sampling methods to study the fate of nitrate in groundwater in a coastal plain watershed: point measurements beneath the streambed, seepage blankets (novel seepage-meter design), and reach mass-balance. The methods gave similar mean groundwater seepage rates into the stream (0.3-0.6 m/d) during two 3-4 day field campaigns despite an order of magnitude difference in stream discharge between the campaigns. At low flow, estimates of flow-weighted mean nitrate concentrations in groundwater discharge ([NO3-]FWM) and nitrate flux from groundwater to the stream decreased with increasing degree of channel influence and measurement scale, i.e., [NO3-]FWM was 654, 561, and 451 µM for point, blanket, and reach mass-balance sampling, respectively. At high flow the trend was reversed, likely because reach mass-balance captured inputs from shallow transient high-nitrate flow paths while point and blanket measurements did not. Point sampling may be better suited to estimating aquifer discharge of nitrate, while reach mass-balance reflects full nitrate inputs into the channel (which at high flow may be more than aquifer discharge due to transient flow paths, and at low flow may be less than aquifer discharge due to channel-based nitrate removal). Modeling dissolved N2 from streambed samples suggested (1) about half of groundwater nitrate was denitrified prior to discharge from the aquifer, and (2) both extent of denitrification and initial nitrate concentration in groundwater (700-1300 µM) were related to land use, suggesting these forms of streambed sampling for groundwater can reveal watershed spatial relations relevant to nitrate contamination and fate in the aquifer.

Attributing uncertainty in streamflow simulations due to variable inputs via the Quantile Flow Deviation metric

NASA Astrophysics Data System (ADS)

Shoaib, Syed Abu; Marshall, Lucy; Sharma, Ashish

2018-06-01

Every model to characterise a real world process is affected by uncertainty. Selecting a suitable model is a vital aspect of engineering planning and design. Observation or input errors make the prediction of modelled responses more uncertain. By way of a recently developed attribution metric, this study is aimed at developing a method for analysing variability in model inputs together with model structure variability to quantify their relative contributions in typical hydrological modelling applications. The Quantile Flow Deviation (QFD) metric is used to assess these alternate sources of uncertainty. The Australian Water Availability Project (AWAP) precipitation data for four different Australian catchments is used to analyse the impact of spatial rainfall variability on simulated streamflow variability via the QFD. The QFD metric attributes the variability in flow ensembles to uncertainty associated with the selection of a model structure and input time series. For the case study catchments, the relative contribution of input uncertainty due to rainfall is higher than that due to potential evapotranspiration, and overall input uncertainty is significant compared to model structure and parameter uncertainty. Overall, this study investigates the propagation of input uncertainty in a daily streamflow modelling scenario and demonstrates how input errors manifest across different streamflow magnitudes.

Slugging Flow of Water Draining from the Bottom of a Non-Vented Container

DOE Office of Scientific and Technical Information (OSTI.GOV)

Charles W. Solbrig

2010-06-01

Experiments were run to observe the behavior of water exiting through an orifice at the bottom of an non-vented container. Initially, the container is nearly full of water with a small air space on top. Once the orifice was uncovered, the slugging rate and the drain rate of the water leaving the container were measured. Upon initially opening the orifice, water drains out until the air pressure above the water reduces enough that the air pressure drop from inside to outside of the container supports the water column and the water stops flowing. Air then enters the container through themore » orifice forming a bubble, which grows until it detaches and bubbles through the water to reach the air space. Once the bubble enters, this added air increases the pressure in the air space enough to allow the water to start flowing out again. This cycle of flow out, flow stoppage, air inflow, and bubble breakoff continues over and over until the hole is closed or the container empties. This is referred to as the “slugging cycle.” A mechanism is proposed to describe the slugging cycle which is modeled analytically. This paper presents the description of the experiments, data obtained, the mechanistic model, and comparison of the model to the experimental data. The model predicts outflow rates close to experimental values. Flow rates from non-vented containers are more than 10 to 20 less than vented containers. The bubbles which must enter the container periodically to increase the internal air pressure stop the water flow momentarily so are responsible for this large decrease in flow rate. Swirl induced in the non-vented container causes the flow rates to increase by a factor of two. The flow rate out of a non-vented container is independent of water height which is in direct contrast to a vented container where the flow rate is proportional to the square root of the water height. The constant rate is due to the container pressure. The higher the water level, the lower the air pressure is in the container. This analytical model requires input of the bubble size. The volume recommended is the volume of a cylinder with the base of the orifice area and length of 3.3 cm. Slugging rate varies only a small amount falling in the range to 2 to 4 cycles/sec. Preliminary work with other containers indicates larger containers, larger orifices and nozzle exit shapes produce higher specific flow rates. The standard multiphase flow equations could not be used to analyze this situation because the two phases are not interpenetrating. Instead one phase must fully stop before the other can flow. Interpenetrating phases allow can pass one another each affecting the other with friction and virtual mass. An interesting observation: The negative air pressure in the container is observable. It equals the water height.« less

Optimizing model: insemination, replacement, seasonal production, and cash flow.

PubMed

DeLorenzo, M A; Spreen, T H; Bryan, G R; Beede, D K; Van Arendonk, J A

1992-03-01

Dynamic programming to solve the Markov decision process problem of optimal insemination and replacement decisions was adapted to address large dairy herd management decision problems in the US. Expected net present values of cow states (151,200) were used to determine the optimal policy. States were specified by class of parity (n = 12), production level (n = 15), month of calving (n = 12), month of lactation (n = 16), and days open (n = 7). Methodology optimized decisions based on net present value of an individual cow and all replacements over a 20-yr decision horizon. Length of decision horizon was chosen to ensure that optimal policies were determined for an infinite planning horizon. Optimization took 286 s of central processing unit time. The final probability transition matrix was determined, in part, by the optimal policy. It was estimated iteratively to determine post-optimization steady state herd structure, milk production, replacement, feed inputs and costs, and resulting cash flow on a calendar month and annual basis if optimal policies were implemented. Implementation of the model included seasonal effects on lactation curve shapes, estrus detection rates, pregnancy rates, milk prices, replacement costs, cull prices, and genetic progress. Other inputs included calf values, values of dietary TDN and CP per kilogram, and discount rate. Stochastic elements included conception (and, thus, subsequent freshening), cow milk production level within herd, and survival. Validation of optimized solutions was by separate simulation model, which implemented policies on a simulated herd and also described herd dynamics during transition to optimized structure.

Timescales of AMOC decline in response to fresh water forcing

NASA Astrophysics Data System (ADS)

Jackson, Laura C.; Wood, Richard A.

2017-12-01

The Atlantic meridional overturning circulation (AMOC) is predicted to weaken over the coming century due to warming from greenhouse gases and increased input of fresh water into the North Atlantic, however there is considerable uncertainty as to the amount and rate of AMOC weakening. Understanding what controls the rate and timescale of AMOC weakening may help to reduce this uncertainty and hence reduce the uncertainty surrounding associated impacts. As a first step towards this we consider the timescales associated with weakening in response to idealized freshening scenarios. Here we explore timescales of AMOC weakening in response to a freshening of the North Atlantic in a suite of experiments with an eddy-permitting global climate model (GCM). When the rate of fresh water added to the North Atlantic is small (0.1 Sv; 1 Sv =1× 10^6 m^3 /s), the timescale of AMOC weakening depends mainly on the rate of fresh water input itself and can be longer than a century. When the rate of fresh water added is large (≥ 0.3 Sv) however, the timescale is a few decades and is insensitive to the actual rate of fresh water input. This insensitivity is because with a greater rate of fresh water input the advective feedbacks become more important at exporting fresh anomalies, so the rate of freshening is similar. We find advective feedbacks from: an export of fresh anomalies by the mean flow; less volume import through the Bering Strait; a weakening AMOC transporting less subtropical water northwards; and anomalous subtropical circulations which amplify export of the fresh anomalies. This latter circulation change is driven itself by the presence of fresh anomalies exported from the subpolar gyre through geostrophy. This feedback has not been identified in previous model studies and when the rate of freshening is strong it is found to dominate the total export of fresh anomalies, and hence the timescale of AMOC decline. Although results may be model dependent, qualitatively similar mechanisms are also found in a single experiment with a different GCM.

Applicability of empirical data currently used in predicting solid propellant exhaust plumes

NASA Technical Reports Server (NTRS)

Tevepaugh, J. A.; Smith, S. D.; Penny, M. M.; Greenwood, T.; Roberts, B. B.

1977-01-01

Theoretical and experimental approaches to exhaust plume analysis are compared. A two-phase model is extended to include treatment of reacting gas chemistry, and thermodynamical modeling of the gaseous phase of the flow field is considered. The applicability of empirical data currently available to define particle drag coefficients, heat transfer coefficients, mean particle size, and particle size distributions is investigated. Experimental and analytical comparisons are presented for subscale solid rocket motors operating at three altitudes with attention to pitot total pressure and stagnation point heating rate measurements. The mathematical treatment input requirements are explained. The two-phase flow field solution adequately predicts gasdynamic properties in the inviscid portion of two-phase exhaust plumes. It is found that prediction of exhaust plume gas pressures requires an adequate model of flow field dynamics.

Analysis of material flow in a utillzation technology of low grade manganese ore and sulphur coal complementary

NASA Astrophysics Data System (ADS)

Wang, Bo-Zhi; Deng, Biao; Su, Shi-Jun; Ding, Sang-Lan; Sun, Wei-Yi

2018-03-01

Electrolytic manganese is conventionally produced through low-grade manganese ore leaching in SO2, with the combustion of high sulfur coal. Subsequently the coal ash and manganese slag, produced by the combustion of high sulfur coal and preparation of electrolytic manganese, can be used as raw ingredients for the preparation of sulphoaluminate cement. In order to realize the `coal-electricity-sulfur-manganese-building material' system of complementary resource utilization, the conditions of material inflow and outflow in each process were determined using material flow analysis. The material flow models in each unit and process can be obtained by analyzed of material flow for new technology, and the input-output model could be obtained. Through the model, it is possible to obtain the quantity of all the input and output material in the condition of limiting the quantity of a substance. Taking one ton electrolytic manganese as a basis, the quantity of other input material and cements can be determined with the input-output model. The whole system had thusly achieved a cleaner production level. Therefore, the input-output model can be used for guidance in practical production.

Presentation of 3D Scenes Through Video Example.

PubMed

Baldacci, Andrea; Ganovelli, Fabio; Corsini, Massimiliano; Scopigno, Roberto

2017-09-01

Using synthetic videos to present a 3D scene is a common requirement for architects, designers, engineers or Cultural Heritage professionals however it is usually time consuming and, in order to obtain high quality results, the support of a film maker/computer animation expert is necessary. We introduce an alternative approach that takes the 3D scene of interest and an example video as input, and automatically produces a video of the input scene that resembles the given video example. In other words, our algorithm allows the user to "replicate" an existing video, on a different 3D scene. We build on the intuition that a video sequence of a static environment is strongly characterized by its optical flow, or, in other words, that two videos are similar if their optical flows are similar. We therefore recast the problem as producing a video of the input scene whose optical flow is similar to the optical flow of the input video. Our intuition is supported by a user-study specifically designed to verify this statement. We have successfully tested our approach on several scenes and input videos, some of which are reported in the accompanying material of this paper.

Variation in watershed nitrogen input and export across the Willamette River Basin

NASA Astrophysics Data System (ADS)

Goodwin, K. E.; Compton, J. E.; Sobota, D. J.

2011-12-01

Nitrogen (N) export from watersheds is influenced by hydrology, land use/cover, and the timing and spatial arrangement of N inputs and removal within basins. We examined the relationship between N input and watershed N export for 25 monitoring stations between 1996 and 2006 within the Willamette River Basin, western Oregon USA. We hypothesized that N export would be strongly correlated with N inputs, and that much of the N inputs comes from agricultural activities located in lowland portions of the basin. We also expected that N export would be strongly seasonal, reflecting the Mediterranean climate of the region. We found a wide range of export from the monitored WRB sub-basins, ranging from 1 to nearly 70 kg N ha-1 yr-1. Lower per unit area N export reflected a high proportion of watershed area in the predominantly forested Cascade Mountains, while the higher N export basins had a greater proportion of agricultural areas, particularly areas dominated by cultivated crops with high N requirements. Export of N varied greatly from year to year (up to nearly 200%), responding to interannual changes in precipitation and runoff. Export was strongly seasonal, with at least 50%, and often 75%, of the N export occurring during the fall and winter months. Snowmelt dominated Cascade Mountain streams tended to maintain flow and N export during the summer, compared with the basins draining Coast-Range and valley areas, which have less snow and spring rain inputs to maintain summer flow. Agricultural N inputs of synthetic and manure fertilizer were strongly correlated with N export from the sub-basins. Across the WRB, N export appears to be more strongly related to fertilizer application rates, as opposed to agricultural areas, indicating the importance of specific crops and crop practices as opposed to considering all agricultural lands the same in analyses of watershed N dynamics. This reinforces the need for careful tracking of N inputs to inform water quality monitoring and management. Annual N export was strongly driven by precipitation and runoff, suggesting that changes in hydrology will have important effects on N export downstream and to coastal areas in the future.

Characteristics of an Electron Cyclotron Resonance Plasma Source for the Production of Active Nitrogen Species in III-V Nitride Epitaxy

NASA Technical Reports Server (NTRS)

Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

1997-01-01

A simple analysis is provided to determine the characteristics of an electron cyclotron resonance (ECR) plasma source for the generation of active nitrogen species in the molecular beam epitaxy of III-V nitrides. The effects of reactor geometry, pressure, power, and flow rate on the dissociation efficiency and ion flux are presented. Pulsing the input power is proposed to reduce the ion flux.

Generalized Fluid System Simulation Program, Version 5.0-Educational. Supplemental Information for NASA/TM-2011-216470. Supplement

NASA Technical Reports Server (NTRS)

Majumdar, A. K.

2011-01-01

The Generalized Fluid System Simulation Program (GFSSP) is a finite-volume based general-purpose computer program for analyzing steady state and time-dependent flow rates, pressures, temperatures, and concentrations in a complex flow network. The program is capable of modeling real fluids with phase changes, compressibility, mixture thermodynamics, conjugate heat transfer between solid and fluid, fluid transients, pumps, compressors and external body forces such as gravity and centrifugal. The thermofluid system to be analyzed is discretized into nodes, branches, and conductors. The scalar properties such as pressure, temperature, and concentrations are calculated at nodes. Mass flow rates and heat transfer rates are computed in branches and conductors. The graphical user interface allows users to build their models using the point, drag and click method; the users can also run their models and post-process the results in the same environment. The integrated fluid library supplies thermodynamic and thermo-physical properties of 36 fluids and 21 different resistance/source options are provided for modeling momentum sources or sinks in the branches. This Technical Memorandum illustrates the application and verification of the code through 12 demonstrated example problems. This supplement gives the input and output data files for the examples.

Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Kim, Jeomoh; Ji, Mi-Hee; Detchprohm, Theeradetch; Dupuis, Russell D.; Fischer, Alec M.; Ponce, Fernando A.; Ryou, Jae-Hyun

2015-09-01

Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.

Modeling constitutive behavior of a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel under hot compression using artificial neural network

NASA Astrophysics Data System (ADS)

Mandal, Sumantra

2006-11-01

ABSTRACT In this paper, an artificial neural network (ANN) model has been suggested to predict the constitutive flow behavior of a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel under hot deformation. Hot compression tests in the temperature range 850°C- 1250°C and strain rate range 10-3-102 s-1 were carried out. These tests provided the required data for training the neural network and for subsequent testing. The inputs of the neural network are strain, log strain rate and temperature while flow stress is obtained as output. A three layer feed-forward network with ten neurons in a single hidden layer and back-propagation learning algorithm has been employed. A very good correlation between experimental and predicted result has been obtained. The effect of temperature and strain rate on flow behavior has been simulated employing the ANN model. The results have been found to be consistent with the metallurgical trend. Finally, a monte carlo analiysis has been carried out to find out the noise sensitivity of the developed model.

Further assessment of the protozoal contribution to the nutrition of the ruminant animal.

PubMed

Hook, Sarah E; France, James; Dijkstra, Jan

2017-03-07

The flow of protozoa from the reticulo-rumen is lower than expected, due to ability of protozoa to prevent washout through sequestration on feed particles and the rumen epithelium. In order to estimate the distribution of protozoa within the reticulo-rumen and passage to the omasum, Czerkawski (1987) developed a model containing pools for the rumen liquid phase, rumen solid phase, and the omasum. This model was used to estimate loss of protozoa in the omasum as well as the amount of protozoal protein available to the animal in the lower gut. A number of assumptions were incorporated into the model, some of which appear unsupported by current research. This paper represents an update, revision, and re-evaluation of Czerkawski's model, where the assumptions that all protozoa in the 'attached' phase are in solid digesta, and that protozoa only leave the rumen in the liquid, have been relaxed. Therefore, the revised model allows for sequestration of protozoa on the rumen epithelium and protozoal passage with particulate outflow. Using experimental observations with inputs within biological limits, the revised model and Czerkawski's original model were verified. The effect of diet on the model was then assessed using inputs from a 100% forage diet and a 35-65% concentrate diet. The extent of sequestration was also varied from complete sequestration, to partial sequestration, and no sequestration. A sensitivity analysis was conducted through a linear regression of perturbed mean inputs versus outputs. The results from the revised model indicate that within the reticulo-rumen, the concentrate diet has a greater fractional flow rate of protozoa from the liquid to solid phase, but a lesser fractional flow rate back to the liquid phase, compared to the forage diet. As well, the concentrate diet has a slower net growth rate of protozoa in the attached phase, compared to the forage diet. In the omasum, the forage diet has a less negative net growth rate, compared to the concentrate diet. The forage diet was also associated with smaller loss of protozoa from the omasum. There are limited data from the omasum to be incorporated into the revised model, especially for quantity of protozoa in the omasum. Further research on quantification of protozoa in the omasum could strengthen the predictions made by the model. Despite this, the revised model found a loss of protozoa in the omasum similar to that suggested by Czerkawski's original model 65-73% versus 66%. The revised model results indicate that efforts to increase protozoal flow to the duodenum should focus on reduced sequestration and increased outflow rate from the rumen, although more research is needed to quantify protozoa in the omasum, and to investigate the role of sequestration onto the wall of the reticulo-rumen. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced capabilities and modified users manual for axial-flow compressor conceptual design code CSPAN

NASA Technical Reports Server (NTRS)

Glassman, Arthur J.; Lavelle, Thomas M.

1995-01-01

Modifications made to the axial-flow compressor conceptual design code CSPAN are documented in this report. Endwall blockage and stall margin predictions were added. The loss-coefficient model was upgraded. Default correlations for rotor and stator solidity and aspect-ratio inputs and for stator-exit tangential velocity inputs were included in the code along with defaults for aerodynamic design limits. A complete description of input and output along with sample cases are included.

Sliding Mode Control of a Thermal Mixing Process

NASA Technical Reports Server (NTRS)

Richter, Hanz; Figueroa, Fernando

2004-01-01

In this paper we consider the robust control of a thermal mixer using multivariable Sliding Mode Control (SMC). The mixer consists of a mixing chamber, hot and cold fluid valves, and an exit valve. The commanded positions of the three valves are the available control inputs, while the controlled variables are total mass flow rate, chamber pressure and the density of the mixture inside the chamber. Unsteady thermodynamics and linear valve models are used in deriving a 5th order nonlinear system with three inputs and three outputs, An SMC controller is designed to achieve robust output tracking in the presence of unknown energy losses between the chamber and the environment. The usefulness of the technique is illustrated with a simulation.

Neural network models for biological waste-gas treatment systems.

PubMed

Rene, Eldon R; Estefanía López, M; Veiga, María C; Kennes, Christian

2011-12-15

This paper outlines the procedure for developing artificial neural network (ANN) based models for three bioreactor configurations used for waste-gas treatment. The three bioreactor configurations chosen for this modelling work were: biofilter (BF), continuous stirred tank bioreactor (CSTB) and monolith bioreactor (MB). Using styrene as the model pollutant, this paper also serves as a general database of information pertaining to the bioreactor operation and important factors affecting gas-phase styrene removal in these biological systems. Biological waste-gas treatment systems are considered to be both advantageous and economically effective in treating a stream of polluted air containing low to moderate concentrations of the target contaminant, over a rather wide range of gas-flow rates. The bioreactors were inoculated with the fungus Sporothrix variecibatus, and their performances were evaluated at different empty bed residence times (EBRT), and at different inlet styrene concentrations (C(i)). The experimental data from these bioreactors were modelled to predict the bioreactors performance in terms of their removal efficiency (RE, %), by adequate training and testing of a three-layered back propagation neural network (input layer-hidden layer-output layer). Two models (BIOF1 and BIOF2) were developed for the BF with different combinations of easily measurable BF parameters as the inputs, that is concentration (gm(-3)), unit flow (h(-1)) and pressure drop (cm of H(2)O). The model developed for the CSTB used two inputs (concentration and unit flow), while the model for the MB had three inputs (concentration, G/L (gas/liquid) ratio, and pressure drop). Sensitivity analysis in the form of absolute average sensitivity (AAS) was performed for all the developed ANN models to ascertain the importance of the different input parameters, and to assess their direct effect on the bioreactors performance. The performance of the models was estimated by the regression coefficient values (R(2)) for the test data set. The results obtained from this modelling work can be useful for obtaining important relationships between different bioreactor parameters and for estimating their safe operating regimes. Copyright © 2011. Published by Elsevier B.V.

Breathing simulator of workers for respirator performance test.

PubMed

Yuasa, Hisashi; Kumita, Mikio; Honda, Takeshi; Kimura, Kazushi; Nozaki, Kosuke; Emi, Hitoshi; Otani, Yoshio

2015-01-01

Breathing machines are widely used to evaluate respirator performance but they are capable of generating only limited air flow patterns, such as, sine, triangular and square waves. In order to evaluate the respirator performance in practical use, it is desirable to test the respirator using the actual breathing patterns of wearers. However, it has been a difficult task for a breathing machine to generate such complicated flow patterns, since the human respiratory volume changes depending on the human activities and workload. In this study, we have developed an electromechanical breathing simulator and a respiration sampling device to record and reproduce worker's respiration. It is capable of generating various flow patterns by inputting breathing pattern signals recorded by a computer, as well as the fixed air flow patterns. The device is equipped with a self-control program to compensate the difference in inhalation and exhalation volume and the measurement errors on the breathing flow rate. The system was successfully applied to record the breathing patterns of workers engaging in welding and reproduced the breathing patterns.

Experimental characterisation and modelling of deformation- induced microstructure in an A6061 aluminium alloy

NASA Astrophysics Data System (ADS)

Kreyca, J. F.; Falahati, A.; Kozeschnik, E.

2016-03-01

For industry, the mechanical properties of a material in form of flow curves are essential input data for finite element simulations. Current practice is to obtain flow curves experimentally and to apply fitting procedures to obtain constitutive equations that describe the material response to external loading as a function of temperature and strain rate. Unfortunately, the experimental procedure for characterizing flow curves is complex and expensive, which is why the prediction of flow-curves by computer modelling becomes increasingly important. In the present work, we introduce a state parameter based model that is capable of predicting the flow curves of an A6061 aluminium alloy in different heat-treatment conditions. The model is implemented in the thermo-kinetic software package MatCalc and takes into account precipitation kinetics, subgrain formation, dynamic recovery by spontaneous annihilation and dislocation climb. To validate the simulation results, a series of compression tests is performed on the thermo-mechanical simulator Gleeble 1500.

UPIOM: a new tool of MFA and its application to the flow of iron and steel associated with car production.

PubMed

Nakamura, Shinichiro; Kondo, Yasushi; Matsubae, Kazuyo; Nakajima, Kenichi; Nagasaka, Tetsuya

2011-02-01

Identification of the flow of materials and substances associated with a product system provides useful information for Life Cycle Analysis (LCA), and contributes to extending the scope of complementarity between LCA and Materials Flow Analysis/Substances Flow Analysis (MFA/SFA), the two major tools of industrial ecology. This paper proposes a new methodology based on input-output analysis for identifying the physical input-output flow of individual materials that is associated with the production of a unit of given product, the unit physical input-output by materials (UPIOM). While the Sankey diagram has been a standard tool for the visualization of MFA/SFA, with an increase in the complexity of the flows under consideration, which will be the case when economy-wide intersectoral flows of materials are involved, the Sankey diagram may become too complex for effective visualization. An alternative way to visually represent material flows is proposed which makes use of triangulation of the flow matrix based on degrees of fabrication. The proposed methodology is applied to the flow of pig iron and iron and steel scrap that are associated with the production of a passenger car in Japan. Its usefulness to identify a specific MFA pattern from the original IO table is demonstrated.

Dynamic characteristics of hydrocarbon fuel within the channel at supercritical and pyrolysis condition

NASA Astrophysics Data System (ADS)

Yu, Bin; Zhou, Weixing; Qin, Jiang; Bao, Wen

2017-12-01

Regenerative cooling with fuel as the coolant is used in the scramjet engine. In order to grasp the dynamic characteristics of engine fuel supply processes, this article studies the dynamic characteristics of hydrocarbon fuel within the channel. A one-dimensional dynamic model was proved, the thermal energy storage effect, fuel volume effect and chemical dynamic effect have been considered in the model, the ordinary differential equations were solved using a 4th order Runge-Kutta method. The precision of the model was validated by three groups of experimental data. The effects of input signal, working condition, tube size on the dynamic characteristics of pressure, flow rate, temperature have been simulated. It is found that cracking reaction increased the compressibility of the fuel pyrolysis mixture and lead to longer responding time of outlet flow. The responding time of outlet flow can reach 3s when tube is 5m long which will greatly influence the control performance of the engine thrust system. Meanwhile, when the inlet flow rate appears the step change, the inlet pressure leads to overshoot, the overshoot can reach as much as 100%, such highly transient impulse will result in detrimental effect on fuel pump.

AOFA- THREE-DIMENSIONAL SUPERSONIC VISCOUS FLOW

NASA Technical Reports Server (NTRS)

Rakich, J. V.

1994-01-01

This program, which is called 'AOFA', determines the complete viscous and inviscid flow around a body of revolution at a given angle of attack and traveling at supersonic speeds. The viscous calculations from this program agree with experimental values for surface and pitot pressures and with surface heating rates. At high speeds, lee-side flows are important because the local heating is difficult to correlate and because the shed vortices can interact with vehicle components such as a canopy or a vertical tail. This program should find application in the design analysis of any high speed vehicle. Lee-side flows are difficult to calculate because thin-boundary-layer theory is not applicable and the concept of matching inviscid and viscous flow is questionable. This program uses the parabolic approximation to the compressible Navier-Stokes equations and solves for the complete inviscid and viscous regions of flow, including the pressure. The parabolic approximation results from the assumption that the stress derivatives in the streamwise direction are small in comparison with derivatives in the normal and circumferential directions. This assumption permits the equation to be solved by an implicit finite difference marching technique which proceeds downstream from the initial data point, provided the inviscid portion of flow is supersonic. The viscous cross-flow separation is also determined as part of the solution. To use this method it is necessary to first determine an initial data point in a region where the inviscid portion of the flow is supersonic. Input to this program consists of two parts. Problem description is conveyed to the program by namelist input. Initial data is acquired by the program as formatted data. Because of the large amount of run time this program can consume the program includes a restart capability. Output is in printed format and magnetic tape for further processing. This program is written in FORTRAN IV and has been implemented on a CDC 7600 with a central memory requirement of approximately 35K (octal) of 60 bit words.

Integrated Water Flow Model (IWFM), A Tool For Numerically Simulating Linked Groundwater, Surface Water And Land-Surface Hydrologic Processes

NASA Astrophysics Data System (ADS)

Dogrul, E. C.; Brush, C. F.; Kadir, T. N.

2006-12-01

The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D land surface, lake, stream flow and vertical unsaturated-zone flow processes which are solved simultaneously at each time step. The groundwater flow system is simulated as a multilayer aquifer system with a mixture of confined and unconfined aquifers separated by semiconfining layers. The groundwater flow process can simulate changing aquifer conditions (confined to unconfined and vice versa), subsidence, tile drains, injection wells and pumping wells. The land surface process calculates elemental water budgets for agricultural, urban, riparian and native vegetation classes. Crop water demands are dynamically calculated using distributed soil properties, land use and crop data, and precipitation and evapotranspiration rates. The crop mix can also be automatically modified as a function of pumping lift using logit functions. Surface water diversions and groundwater pumping can each be specified, or can be automatically adjusted at run time to balance water supply with water demand. The land-surface process also routes runoff to streams and deep percolation to the unsaturated zone. Surface water networks are specified as a series of stream nodes (coincident with groundwater nodes) with specified bed elevation, conductance and stage-flow relationships. Stream nodes are linked to form stream reaches. Stream inflows at the model boundary, surface water diversion locations, and one or more surface water deliveries per location are specified. IWFM routes stream flows through the network, calculating groundwater-surface water interactions, accumulating inflows from runoff, and allocating available stream flows to meet specified or calculated deliveries. IWFM utilizes a very straight-forward input file structure, allowing rapid development of complex simulations. A key feature of IWFM is a new algorithm for computation of groundwater flow across element faces. Enhancements to version 3.0 include automatic time-tracking of input and output data sets, linkage with the HEC-DSS database, and dynamic crop allocation using logit functions. Utilities linking IWFM to the PEST automated calibration suite are also available. All source code, executables and documentation are available for download from the DWR web site. IWFM is currently being used to develop hydrologic simulations of California's Central Valley (C2VSIM); the west side of California's San Joaquin Valley (WESTSIM); Butte County, CA; Solano County, CA; Merced County, CA; and the Oregon side of the Walla Walla River Basin.

Modeling the use of a binary mixture as a control scheme for two-phase thermal systems

NASA Technical Reports Server (NTRS)

Benner, S. M.; Costello, Frederick A.

1990-01-01

Two-phase thermal loops using mechanical pumps, capillary pumps, or a combination of the two have been chosen as the main heat transfer systems for the space station. For these systems to operate optimally, the flow rate in the loop should be controlled in response to the vapor/liquid ratio leaving the evaporator. By substituting a mixture of two non-azeotropic fluids in place of the single fluid normally used in these systems, it may be possible to monitor the temperature of the exiting vapor and determine the vapor/liquid ratio. The flow rate would then be adjusted to maximize the load capability with minimum energy input. A FLUINT model was developed to study the system dynamics of a hybrid capillary pumped loop using this type of control and was found to be stable under all the test conditions.

Design of artificial neural networks using a genetic algorithm to predict collection efficiency in venturi scrubbers.

PubMed

Taheri, Mahboobeh; Mohebbi, Ali

2008-08-30

In this study, a new approach for the auto-design of neural networks, based on a genetic algorithm (GA), has been used to predict collection efficiency in venturi scrubbers. The experimental input data, including particle diameter, throat gas velocity, liquid to gas flow rate ratio, throat hydraulic diameter, pressure drop across the venturi scrubber and collection efficiency as an output, have been used to create a GA-artificial neural network (ANN) model. The testing results from the model are in good agreement with the experimental data. Comparison of the results of the GA optimized ANN model with the results from the trial-and-error calibrated ANN model indicates that the GA-ANN model is more efficient. Finally, the effects of operating parameters such as liquid to gas flow rate ratio, throat gas velocity, and particle diameter on collection efficiency were determined.

TWINTAN: A program for transonic wall interference assessment in two-dimensional wind tunnels

NASA Technical Reports Server (NTRS)

Kemp, W. B., Jr.

1980-01-01

A method for assessing the wall interference in transonic two dimensional wind tunnel test was developed and implemented in a computer program. The method involves three successive solutions of the transonic small disturbance potential equation to define the wind tunnel flow, the perturbation attriburable to the model, and the equivalent free air flow around the model. Input includes pressure distributions on the model and along the top and bottom tunnel walls which are used as boundary conditions for the wind tunnel flow. The wall induced perturbation fields is determined as the difference between the perturbation in the tunnel flow solution and the perturbation attributable to the model. The methodology used in the program is described and detailed descriptions of the computer program input and output are presented. Input and output for a sample case are given.

Effects of Uncertainties in Hydrological Modelling. A Case Study of a Mountainous Catchment in Southern Norway

NASA Astrophysics Data System (ADS)

Engeland, Kolbjorn; Steinsland, Ingelin

2016-04-01

The aim of this study is to investigate how the inclusion of uncertainties in inputs and observed streamflow influence the parameter estimation, streamflow predictions and model evaluation. In particular we wanted to answer the following research questions: • What is the effect of including a random error in the precipitation and temperature inputs? • What is the effect of decreased information about precipitation by excluding the nearest precipitation station? • What is the effect of the uncertainty in streamflow observations? • What is the effect of reduced information about the true streamflow by using a rating curve where the measurement of the highest and lowest streamflow is excluded when estimating the rating curve? To answer these questions, we designed a set of calibration experiments and evaluation strategies. We used the elevation distributed HBV model operating on daily time steps combined with a Bayesian formulation and the MCMC routine Dream for parameter inference. The uncertainties in inputs was represented by creating ensembles of precipitation and temperature. The precipitation ensemble were created using a meta-gaussian random field approach. The temperature ensembles were created using a 3D Bayesian kriging with random sampling of the temperature laps rate. The streamflow ensembles were generated by a Bayesian multi-segment rating curve model. Precipitation and temperatures were randomly sampled for every day, whereas the streamflow ensembles were generated from rating curve ensembles, and the same rating curve was always used for the whole time series in a calibration or evaluation run. We chose a catchment with a meteorological station measuring precipitation and temperature, and a rating curve of relatively high quality. This allowed us to investigate and further test the effect of having less information on precipitation and streamflow during model calibration, predictions and evaluation. The results showed that including uncertainty in the precipitation and temperature input has a negligible effect on the posterior distribution of parameters and for the Nash-Sutcliffe (NS) efficiency for the predicted flows, while the reliability and the continuous rank probability score (CRPS) improves. Reduced information in precipitation input resulted in a and a shift in the water balance parameter Pcorr, a model producing smoother streamflow predictions giving poorer NS and CRPS, but higher reliability. The effect of calibrating the hydrological model using wrong rating curves is mainly seen as variability in the water balance parameter Pcorr. When evaluating predictions obtained using a wrong rating curve, the evaluation scores varies depending on the true rating curve. Generally, the best evaluation scores were not achieved for the rating curve used for calibration, but for a rating curves giving low variance in streamflow observations. Reduced information in streamflow influenced the water balance parameter Pcorr, and increased the spread in evaluation scores giving both better and worse scores. This case study shows that estimating the water balance is challenging since both precipitation inputs and streamflow observations have pronounced systematic component in their uncertainties.

Counterflow diffusion flames of hydrogen, and hydrogen plus methane, ethylene, propane, and silane vs. air - Strain rates at extinction

NASA Technical Reports Server (NTRS)

Pellett, G. L.; Northam, G. Burton; Wilson, L. G.

1991-01-01

Five coaxial tubular opposed jet burners (OJBs) with tube diameter D(T) of 1.8-10 mm and 5 mm conical nozzles were used to form dish-shaped counterflow diffusion flames centered by opposing laminar jets of nitrogen and hydrocarbon-diluted H2 versus air in an argon-purged chamber at 1 atm. Area-averaged air jet velocities at blowoff of the central flame, U(air), characterized extinction of the airside flame as functions of input H2 concentration on the fuelside. A master plot of extensive U(air) data at blowoff versus D(T) shows that U(air) varies linearly with D(T). This and other data sets are used to find that nozzle OJB results for U(air)/diameter average 4.24 + or - 0.28 times larger than tubular OJB results for the same fuel compositions. Critical radial velocity gradients consistent with one-dimensional stagnation point boundary theory and with plug flow inputs are estimated. The results compare favorably with published numerical results based only on potential flow.

Study of cryogenic propellant systems for loading the space shuttle

NASA Technical Reports Server (NTRS)

Voth, R. O.; Steward, W. G.; Hall, W. J.

1974-01-01

Computer programs were written to model the liquid oxygen loading system for the space shuttle. The programs allow selection of input data through graphic displays which schematically depict the part of the system being modeled. The computed output is also displayed in the form of graphs and printed messages. Any one of six computation options may be selected. The first four of these pertain to thermal stresses, pressure surges, cooldown times, flow rates and pressures during cooldown. Options five and six deal with possible water hammer effects due to closing of valves, steady flow and transient response to changes in operating conditions after cooldown. Procedures are given for operation of the graphic display unit and minicomputer.

Numerical Model of Channel and Aquatic Habitat Response to Sediment Pulses in Mountain Rivers of Central Idaho

NASA Astrophysics Data System (ADS)

Lewicki, M.; Buffington, J. M.; Thurow, R. F.; Isaak, D. J.

2006-12-01

Mountain rivers in central Idaho receive pulsed sediment inputs from a variety of mass wasting processes (side-slope landslides, rockfalls, and tributary debris flows). Tributary debris flows and hyperconcentrated flows are particularly common due to winter "rain-on-snow" events and summer thunderstorms, the effects of which are amplified by frequent wildfire and resultant changes in vegetation, soil characteristics, and basin hydrology. Tributary confluences in the study area are commonly characterized by debris fans built by these repeated sediment pulses, providing long-term controls on channel slope, hydraulics and sediment transport capacity in the mainstem channel network. These long-term impacts are magnified during debris-flow events, which deliver additional sediment and wood debris to the fan and may block the mainstem river. These changes in physical conditions also influence local and downstream habitat for aquatic species, and can impact local human infrastructure (roads, bridges). Here, we conduct numerical simulations using a modified version of Cui's [2005] network routing model to examine bedload transport and debris-fan evolution in medium- sized watersheds (65-570 km2) of south-central Idaho. We test and calibrate the model using data from a series of postfire debris-flow events that occurred from 2003-4. We investigate model sensitivity to different controlling factors (location of the pulse within the stream network, volume of the pulse, and size distribution of the input material). We predict that on decadal time scales, sediment pulses cause a local coarsening of the channel bed in the vicinity of the sediment input, and a wave of downstream fining over several kilometers of the river (as long as the pulse material is not coarser than the stream bed itself). The grain-size distribution of the pulse influences its rate of erosion, the rate and magnitude of downstream fining, and the time required for system recovery. The effects of textural fining on spawning habitat depend on the size of sediment in the wave relative to that of the downstream channel; fining can improve spawning habitat availability in channels that are otherwise too coarse, or degrade habitat availability in finer-grained channels. Despite the perceived negative effects of sediment pulses, they can be important sources of gravel and wood debris, creating downstream spawning sites and productive wood-forced habitats. Field observations illustrate that opportunistic salmonids will spawn along the margins of recently deposited debris fans, emphasizing the biological value of such disturbances and the plasticity of salmonids to natural disturbances.

Geomorphic change caused by outburst floods and debris flows at Mount Rainier, Washington, with emphasis on Tahoma Creek valley

USGS Publications Warehouse

Walder, J.S.; Driedger, C.L.

1994-01-01

Debris flows have caused rapid geomorphic change in several glacierized drainages on Mount Rainier, Washington. Nearly all of these flows began as glacial outburst floods, then transformed to debris flows by incorporating large masses of sediment in channel reaches where streams have incised proglacial sediments and stagnant glacier ice. This stagnant ice is a relic of advanced glacier positions achieved during the mid-nineteenth century Little Ice Age maximum and the readvance of the 1960's and 1970's. Debris flows have been especially important agents of geomorphic change along Tahoma Creek, which drains South Tahoma Glacier. Debris flows in Tahoma Creek valley have transported downstream about 107 m3 Of sediment since 1967, causing substantial aggradation and damage to roads and facilities in Mount Rainier National Park. The average denudation rate in the upper part of the Tahoma Creek drainage basin in the same period has been extraordinarily high: more than 20 millimeters per year, a value exceeded only rarely in basins affected by debris flows. However, little or none of this sediment has yet passed out of the Tahoma Creek drainage basin. Outburst floods from South Tahoma Glacier form by release of subglacially stored water. The volume of stored water discharged during a typical outburst flood would form a layer several tens of millimeters thick over the bed of the entire glacier, though it is more likely that large linked cavities account for most of the storage. Statistical analysis shows that outburst floods usually occur during periods of atypically hot or rainy weather in summer or early autumn, and that the probability of an outburst increases with temperature (a proxy measure of ablation rate) or rainfall rate. On the basis of these results, we suggest that outburst floods are triggered when rapid input of water to the glacier bed causes transient increase in water pressure, thereby destabilizing the linked-cavity system. The probabilistic nature of the relation between water-input rate and outburst-flood occurrence suggests that the connections between englacial conduits, basal cavities and main meltwater channels may vary temporally. The correlation between outburst floods and meteorological factors casts doubt on an earlier hypothesis that melting around geothermal vents triggers outburst floods from South Tahoma Glacier. The likelihood that outburst floods from South Tahoma Glacier will trigger debris flows should decrease with time, as the deeply incised reach of Tahoma Creek widens by normal slope processes and stagnant ice decays. Drawing analogies to the geomorphic evolution of a reach of Tahoma Creek first incised by an outburst flood in 1967, we suggest the present period of debris-flow activity along Tahoma Creek will last about 25 years, that is, until about the year 2010. Comparison of geomorphic change at Tahoma Creek to that in two other glacierized alphine basins indicates that debris-rich stagnant ice can be an importantsource of sediment to debris flows as long as floods are frequent or channel slope is great.

Comparative performance of fixed-film biological filters: Application of reactor theory

USGS Publications Warehouse

Watten, B.J.; Sibrell, P.L.

2006-01-01

Nitrification is classified as a two-step consecutive reaction where R1 represents the rate of formation of the intermediate product NO2-N and R2 represents the rate of formation of the final product NO3-N. The relative rates of R1 and R2 are influenced by reactor type characterized hydraulically as plug-flow, plug-flow with dispersion and mixed-flow. We develop substrate conversion models for fixed-film biofilters operating in the first-order kinetic regime based on application of chemical reactor theory. Reactor type, inlet conditions and the biofilm kinetic constants Ki (h-1) are used to predict changes in NH4-N, NO2-N, NO3-N and BOD5. The inhibiting effects of the latter on R1 and R2 were established based on the ?? relation, e.g.:{A formula is presented}where BOD5,max is the concentration that causes nitrification to cease and N is a variable relating Ki to increasing BOD5. Conversion models were incorporated in spreadsheet programs that provided steady-state concentrations of nitrogen and BOD5 at several points in a recirculating aquaculture system operating with input values for fish feed rate, reactor volume, microscreen performance, make-up and recirculating flow rates. When rate constants are standardized, spreadsheet use demonstrates plug-flow reactors provide higher rates of R1 and R2 than mixed-flow reactors thereby reducing volume requirements for target concentrations of NH4-N and NO2-N. The benefit provided by the plug-flow reactor varies with hydraulic residence time t as well as the effective vessel dispersion number, D/??L. Both reactor types are capable of providing net increases in NO2-N during treatment but the rate of decrease in the mixed-flow case falls well behind that predicted for plug-flow operation. We show the potential for a positive net change in NO2-N increases with decreases in the dimensionless ratios K2, (R2 )/K1,( R1 ) and [NO2-N]/[NH4-N] and when the product K1, (R1) t provides low to moderate NH4-N conversions. Maintaining high levels of the latter reduces the effective reactor utilization rate (%) defined here as (RNavg/RNmax)100 where RNavg is the mean reactive nitrogen concentration ([NH4-N] + [NO2-N]) within the reactor, and RNmax represents the feed concentration of the same. Low utilization rates provide a hedge against unexpected increases in substrate loading and reduce water pumping requirements but force use of elevated reactor volumes. Further ?? effects on R1 and R2 can be reduced through use of a tanks-in-series versus a single mixed-flow reactor configuration and by improving the solids removal efficiency of microscreen treatment.

A dual theory of price and value in a meso-scale economic model with stochastic profit rate

NASA Astrophysics Data System (ADS)

Greenblatt, R. E.

2014-12-01

The problem of commodity price determination in a market-based, capitalist economy has a long and contentious history. Neoclassical microeconomic theories are based typically on marginal utility assumptions, while classical macroeconomic theories tend to be value-based. In the current work, I study a simplified meso-scale model of a commodity capitalist economy. The production/exchange model is represented by a network whose nodes are firms, workers, capitalists, and markets, and whose directed edges represent physical or monetary flows. A pair of multivariate linear equations with stochastic input parameters represent physical (supply/demand) and monetary (income/expense) balance. The input parameters yield a non-degenerate profit rate distribution across firms. Labor time and price are found to be eigenvector solutions to the respective balance equations. A simple relation is derived relating the expected value of commodity price to commodity labor content. Results of Monte Carlo simulations are consistent with the stochastic price/labor content relation.

Interactive effects of mechano- and chemo-receptor inputs on cardiorespiratory outputs in the toad.

PubMed

Wang, T; Taylor, E W; Reid, S G; Milsom, W K

2004-04-20

Arterial blood pressure (P(b)), pulmocutaneous blood flow (Q(pc)), heart rate (f(H)), and fictive ventilation (motor activity in the Vth cranial nerve, V(int)), were recorded from decerebrated, paralysed toads receiving unidirectional ventilation with experimental gas mixtures over a range of lung inflation. At the onset of spontaneous bouts of fictive ventilation, (Q(pc)) and P(b) increased immediately, often with changes in heart rate, implying central cardiorespiratory interactions. Inflation of the lungs with different gas mixtures revealed that the effect of hypercarbia on V(int) was reduced by lung inflation and that feedback from pulmonary stretch receptors may summate with central feedforward control of f(H) and (Q(pc)) in an interactive fashion. The results of bolus injections of cyanide into the carotid or the pulmonary circulations suggest there are oxygen sensitive receptors in both circuits that affect the cardiovascular system directly and respiratory activity by complex central interactions with inputs from central chemoreceptors and pulmonary stretch receptors.

RTE: A computer code for Rocket Thermal Evaluation

NASA Technical Reports Server (NTRS)

Naraghi, Mohammad H. N.

1995-01-01

The numerical model for a rocket thermal analysis code (RTE) is discussed. RTE is a comprehensive thermal analysis code for thermal analysis of regeneratively cooled rocket engines. The input to the code consists of the composition of fuel/oxidant mixture and flow rates, chamber pressure, coolant temperature and pressure. dimensions of the engine, materials and the number of nodes in different parts of the engine. The code allows for temperature variation in axial, radial and circumferential directions. By implementing an iterative scheme, it provides nodal temperature distribution, rates of heat transfer, hot gas and coolant thermal and transport properties. The fuel/oxidant mixture ratio can be varied along the thrust chamber. This feature allows the user to incorporate a non-equilibrium model or an energy release model for the hot-gas-side. The user has the option of bypassing the hot-gas-side calculations and directly inputting the gas-side fluxes. This feature is used to link RTE to a boundary layer module for the hot-gas-side heat flux calculations.

A note on the theory of fast money flow dynamics

NASA Astrophysics Data System (ADS)

Sokolov, A.; Kieu, T.; Melatos, A.

2010-08-01

The gauge theory of arbitrage was introduced by Ilinski in [K. Ilinski, preprint arXiv:hep-th/9710148 (1997)] and applied to fast money flows in [A. Ilinskaia, K. Ilinski, preprint arXiv:cond-mat/9902044 (1999); K. Ilinski, Physics of finance: gauge modelling in non-equilibrium pricing (Wiley, 2001)]. The theory of fast money flow dynamics attempts to model the evolution of currency exchange rates and stock prices on short, e.g. intra-day, time scales. It has been used to explain some of the heuristic trading rules, known as technical analysis, that are used by professional traders in the equity and foreign exchange markets. A critique of some of the underlying assumptions of the gauge theory of arbitrage was presented by Sornette in [D. Sornette, Int. J. Mod. Phys. C 9, 505 (1998)]. In this paper, we present a critique of the theory of fast money flow dynamics, which was not examined by Sornette. We demonstrate that the choice of the input parameters used in [K. Ilinski, Physics of finance: gauge modelling in non-equilibrium pricing (Wiley, 2001)] results in sinusoidal oscillations of the exchange rate, in conflict with the results presented in [K. Ilinski, Physics of finance: gauge modelling in non-equilibrium pricing (Wiley, 2001)]. We also find that the dynamics predicted by the theory are generally unstable in most realistic situations, with the exchange rate tending to zero or infinity exponentially.

Floodplain restoration enhances denitrification and reach-scale nitrogen removal in an agricultural stream.

PubMed

Roley, Sarah S; Tank, Jennifer L; Stephen, Mia L; Johnson, Laura T; Beaulieu, Jake J; Witter, Jonathan D

2012-01-01

Streams of the agricultural Midwest, USA, export large quantities of nitrogen, which impairs downstream water quality, most notably in the Gulf of Mexico. The two-stage ditch is a novel restoration practice, in which floodplains are constructed alongside channelized ditches. During high flows, water flows across the floodplains, increasing benthic surface area and stream water residence time, as well as the potential for nitrogen removal via denitrification. To determine two-stage ditch nitrogen removal efficacy, we measured denitrification rates in the channel and on the floodplains of a two-stage ditch in north-central Indiana for one year before and two years after restoration. We found that instream rates were similar before and after the restoration, and they were influenced by surface water NO3- concentration and sediment organic matter content. Denitrification rates were lower on the constructed floodplains and were predicted by soil exchangeable NO3- concentration. Using storm flow simulations, we found that two-stage ditch restoration contributed significantly to NO3- removal during storm events, but because of the high NO3- loads at our study site, < 10% of the NO3- load was removed under all storm flow scenarios. The highest percentage of NO3- removal occurred at the lowest loads; therefore, the two-stage ditch's effectiveness at reducing downstream N loading will be maximized when the practice is coupled with efforts to reduce N inputs from adjacent fields.

Radar Absorbing Colloidal Solutions (RACS)

DTIC Science & Technology

2007-08-01

fig.5 sloiws te W-b yskm tinder test (a) and the two W- and D-band homi (b). The sytm ut~u4 tapol Ogm ingpi~s uVsmsso thepeanemptyeietm eone Twele...Because there is a very well defined relationship between DNA sequence and the thermodynamics of double-stranded DNA (dsDNA) formation, it is possible...to test device performance. The mass flow rate basically increases with heat input from the heat son=v though the exact relationship would be

Real time closed loop control of an Ar and Ar/O2 plasma in an ICP

NASA Astrophysics Data System (ADS)

Faulkner, R.; Soberón, F.; McCarter, A.; Gahan, D.; Karkari, S.; Milosavljevic, V.; Hayden, C.; Islyaikin, A.; Law, V. J.; Hopkins, M. B.; Keville, B.; Iordanov, P.; Doherty, S.; Ringwood, J. V.

2006-10-01

Real time closed loop control for plasma assisted semiconductor manufacturing has been the subject of academic research for over a decade. However, due to process complexity and the lack of suitable real time metrology, progress has been elusive and genuine real time, multi-input, multi-output (MIMO) control of a plasma assisted process has yet to be successfully implemented in an industrial setting. A Splasma parameter control strategy T is required to be adopted whereby process recipes which are defined in terms of plasma properties such as critical species densities as opposed to input variables such as rf power and gas flow rates may be transferable between different chamber types. While PIC simulations and multidimensional fluid models have contributed considerably to the basic understanding of plasmas and the design of process equipment, such models require a large amount of processing time and are hence unsuitable for testing control algorithms. In contrast, linear dynamical empirical models, obtained through system identification techniques are ideal in some respects for control design since their computational requirements are comparatively small and their structure facilitates the application of classical control design techniques. However, such models provide little process insight and are specific to an operating point of a particular machine. An ideal first principles-based, control-oriented model would exhibit the simplicity and computational requirements of an empirical model and, in addition, despite sacrificing first principles detail, capture enough of the essential physics and chemistry of the process in order to provide reasonably accurate qualitative predictions. This paper will discuss the development of such a first-principles based, control-oriented model of a laboratory inductively coupled plasma chamber. The model consists of a global model of the chemical kinetics coupled to an analytical model of power deposition. Dynamics of actuators including mass flow controllers and exhaust throttle are included and sensor characteristics are also modelled. The application of this control-oriented model to achieve multivariable closed loop control of specific species e.g. atomic Oxygen and ion density using the actuators rf power, Oxygen and Argon flow rates, and pressure/exhaust flow rate in an Ar/O2 ICP plasma will be presented.

Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qazi, H. I. A.; Li, He-Ping, E-mail: liheping@tsinghua.edu.cn; Zhang, Xiao-Fei

This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up themore » generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.« less

Simultaneous material flow analysis of nickel, chromium, and molybdenum used in alloy steel by means of input-output analysis.

PubMed

Nakajima, Kenichi; Ohno, Hajime; Kondo, Yasushi; Matsubae, Kazuyo; Takeda, Osamu; Miki, Takahiro; Nakamura, Shinichiro; Nagasaka, Tetsuya

2013-05-07

Steel is not elemental iron but rather a group of iron-based alloys containing many elements, especially chromium, nickel, and molybdenum. Steel recycling is expected to promote efficient resource use. However, open-loop recycling of steel could result in quality loss of nickel and molybdenum and/or material loss of chromium. Knowledge about alloying element substance flow is needed to avoid such losses. Material flow analyses (MFAs) indicate the importance of steel recycling to recovery of alloying elements. Flows of nickel, chromium, and molybdenum are interconnected, but MFAs have paid little attention to the interconnected flow of materials/substances in supply chains. This study combined a waste input-output material flow model and physical unit input-output analysis to perform a simultaneous MFA for nickel, chromium, and molybdenum in the Japanese economy in 2000. Results indicated the importance of recovery of these elements in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.

Dual Rate Adaptive Control for an Industrial Heat Supply Process Using Signal Compensation Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chai, Tianyou; Jia, Yao; Wang, Hong

The industrial heat supply process (HSP) is a highly nonlinear cascaded process which uses a steam valve opening as its control input, the steam flow-rate as its inner loop output and the supply water temperature as its outer loop output. The relationship between the heat exchange rate and the model parameters, such as steam density, entropy, and fouling correction factor and heat exchange efficiency are unknown and nonlinear. Moreover, these model parameters vary in line with steam pressure, ambient temperature and the residuals caused by the quality variations of the circulation water. When the steam pressure and the ambient temperaturemore » are of high values and are subjected to frequent external random disturbances, the supply water temperature and the steam flow-rate would interact with each other and fluctuate a lot. This is also true when the process exhibits unknown characteristic variations of the process dynamics caused by the unexpected changes of the heat exchange residuals. As a result, it is difficult to control the supply water temperature and the rates of changes of steam flow-rate well inside their targeted ranges. In this paper, a novel compensation signal based dual rate adaptive controller is developed by representing the unknown variations of dynamics as unmodeled dynamics. In the proposed controller design, such a compensation signal is constructed and added onto the control signal obtained from the linear deterministic model based feedback control design. Such a compensation signal aims at eliminating the unmodeled dynamics and the rate of changes of the currently sample unmodeled dynamics. A successful industrial application is carried out, where it has been shown that both the supply water temperature and the rate of the changes of the steam flow-rate can be controlled well inside their targeted ranges when the process is subjected to unknown variations of its dynamics.« less

Effect of basal forebrain stimulation on extracellular acetylcholine release and blood flow in the olfactory bulb.

PubMed

Uchida, Sae; Kagitani, Fusako

2017-05-12

The olfactory bulb receives cholinergic basal forebrain input, as does the neocortex; however, the in vivo physiological functions regarding the release of extracellular acetylcholine and regulation of regional blood flow in the olfactory bulb are unclear. We used in vivo microdialysis to measure the extracellular acetylcholine levels in the olfactory bulb of urethane-anesthetized rats. Focal chemical stimulation by microinjection of L-glutamate into the horizontal limb of the diagonal band of Broca (HDB) in the basal forebrain, which is the main source of cholinergic input to the olfactory bulb, increased extracellular acetylcholine release in the ipsilateral olfactory bulb. When the regional cerebral blood flow was measured using laser speckle contrast imaging, the focal chemical stimulation of the HDB did not significantly alter the blood flow in the olfactory bulb, while increases were observed in the neocortex. Our results suggest a functional difference between the olfactory bulb and neocortex regarding cerebral blood flow regulation through the release of acetylcholine by cholinergic basal forebrain input.

A large-grain mapping approach for multiprocessor systems through data flow model. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kim, Hwa-Soo

1991-01-01

A large-grain level mapping method is presented of numerical oriented applications onto multiprocessor systems. The method is based on the large-grain data flow representation of the input application and it assumes a general interconnection topology of the multiprocessor system. The large-grain data flow model was used because such representation best exhibits inherited parallelism in many important applications, e.g., CFD models based on partial differential equations can be presented in large-grain data flow format, very effectively. A generalized interconnection topology of the multiprocessor architecture is considered, including such architectural issues as interprocessor communication cost, with the aim to identify the 'best matching' between the application and the multiprocessor structure. The objective is to minimize the total execution time of the input algorithm running on the target system. The mapping strategy consists of the following: (1) large-grain data flow graph generation from the input application using compilation techniques; (2) data flow graph partitioning into basic computation blocks; and (3) physical mapping onto the target multiprocessor using a priority allocation scheme for the computation blocks.

Extended parametric representation of compressor fans and turbines. Volume 2: Part user's manual (parametric turbine)

NASA Technical Reports Server (NTRS)

Coverse, G. L.

1984-01-01

A turbine modeling technique has been developed which will enable the user to obtain consistent and rapid off-design performance from design point input. This technique is applicable to both axial and radial flow turbine with flow sizes ranging from about one pound per second to several hundred pounds per second. The axial flow turbines may or may not include variable geometry in the first stage nozzle. A user-specified option will also permit the calculation of design point cooling flow levels and corresponding changes in efficiency for the axial flow turbines. The modeling technique has been incorporated into a time-sharing program in order to facilitate its use. Because this report contains a description of the input output data, values of typical inputs, and example cases, it is suitable as a user's manual. This report is the second of a three volume set. The titles of the three volumes are as follows: (1) Volume 1 CMGEN USER's Manual (Parametric Compressor Generator); (2) Volume 2 PART USER's Manual (Parametric Turbine); (3) Volume 3 MODFAN USER's Manual (Parametric Modulation Flow Fan).

Robust estimation of pulse wave transit time using group delay.

PubMed

Meloni, Antonella; Zymeski, Heather; Pepe, Alessia; Lombardi, Massimo; Wood, John C

2014-03-01

To evaluate the efficiency of a novel transit time (Δt) estimation method from cardiovascular magnetic resonance flow curves. Flow curves were estimated from phase contrast images of 30 patients. Our method (TT-GD: transit time group delay) operates in the frequency domain and models the ascending aortic waveform as an input passing through a discrete-component "filter," producing the observed descending aortic waveform. The GD of the filter represents the average time delay (Δt) across individual frequency bands of the input. This method was compared with two previously described time-domain methods: TT-point using the half-maximum of the curves and TT-wave using cross-correlation. High temporal resolution flow images were studied at multiple downsampling rates to study the impact of differences in temporal resolution. Mean Δts obtained with the three methods were comparable. The TT-GD method was the most robust to reduced temporal resolution. While the TT-GD and the TT-wave produced comparable results for velocity and flow waveforms, the TT-point resulted in significant shorter Δts when calculated from velocity waveforms (difference: 1.8±2.7 msec; coefficient of variability: 8.7%). The TT-GD method was the most reproducible, with an intraobserver variability of 3.4% and an interobserver variability of 3.7%. Compared to the traditional TT-point and TT-wave methods, the TT-GD approach was more robust to the choice of temporal resolution, waveform type, and observer. Copyright © 2013 Wiley Periodicals, Inc.

Absorption of CO2 from modified flue gases of power generation Tarahan chemically using NaOH and Na2CO3 and biologically using microalgae

NASA Astrophysics Data System (ADS)

Purba, Elida; Agustina, Dewi; Putri Pertama, Finka; Senja, Fita

2018-03-01

This research was carried out on the absorption of CO2 from the modified flue gases of power generation Tarahan using NaOH (sodium hydroxide) and Na2CO3 (sodium carbonate). The operation was conducted in a packed column absorber and then the output gases from the packed column was fed into photo-bioreactor for biological absorption. In the photo-bioreactor, two species of microalgae, N. occulata and T. chuii, were cultivated to both absorb CO2 gas and to produce biomass for algal oil. The aims of this research were, first, to determine the effect of absorbent flow rate on the reduction of CO2 and on the decrease of output gas temperature, second, to determine the characteristics of methyl ester obtained from biological absorption process. Flow rates of the absorbent were varied as 1, 2, and 3 l/min. The concentrations of NaOH and Na2CO3 were 1 M at a constant gas flow rate of 6 l/min. The output concentrations of CO2 from the absorber was analyzed using Gas Chromatography 2014-AT SHIMADZU Corp 08128. The results show that both of the absorbents give different trends. From the absorption using NaOH, it can be concluded that the higher the flow rate, the higher the absorption rate obtained. The highest flow rate achieved maximum absorption of 100%. On the other hand, absorption with Na2CO3 revealed the opposite trend where the higher the flow rates the lower the absorption rate. The highest absorption using Na2CO3 was obtained with the lowest flow rate, 1 l/min, that was 45,5%. As the effect of flow rate on output gas temperature, the temperature decreased with increasing flow rates for both absorbents. The output gas temperature for NaOH and Na2CO3 were consecutively 35 °C and 31 °C with inlet gas temperature of 50°C. Absorption of CO2 biologically resulted a reduction of CO2 up to 60% from the input gas concentration. Algal oil was extracted with mixed hexane and chloroform to obtain algal oil. Extracted oil was transesterified to methyl ester using sodium hydroxide as a catalyst. The results of in-situ transesterification method cannot be identified. Both microalgae achieved maximum yield at 2% catalyst concentration. Nannochloropsis occulata achieved the highest yield of algal oil that is 88.5%. The highest content of methyl ester from Nannochloropsis occulata was undecanoic acid methyl ester by 55.42% and the result from Tetraselmis chuii was palmitic acid methyl ester by 81.58%.

Confidence intervals in Flow Forecasting by using artificial neural networks

NASA Astrophysics Data System (ADS)

Panagoulia, Dionysia; Tsekouras, George

2014-05-01

One of the major inadequacies in implementation of Artificial Neural Networks (ANNs) for flow forecasting is the development of confidence intervals, because the relevant estimation cannot be implemented directly, contrasted to the classical forecasting methods. The variation in the ANN output is a measure of uncertainty in the model predictions based on the training data set. Different methods for uncertainty analysis, such as bootstrap, Bayesian, Monte Carlo, have already proposed for hydrologic and geophysical models, while methods for confidence intervals, such as error output, re-sampling, multi-linear regression adapted to ANN have been used for power load forecasting [1-2]. The aim of this paper is to present the re-sampling method for ANN prediction models and to develop this for flow forecasting of the next day. The re-sampling method is based on the ascending sorting of the errors between real and predicted values for all input vectors. The cumulative sample distribution function of the prediction errors is calculated and the confidence intervals are estimated by keeping the intermediate value, rejecting the extreme values according to the desired confidence levels, and holding the intervals symmetrical in probability. For application of the confidence intervals issue, input vectors are used from the Mesochora catchment in western-central Greece. The ANN's training algorithm is the stochastic training back-propagation process with decreasing functions of learning rate and momentum term, for which an optimization process is conducted regarding the crucial parameters values, such as the number of neurons, the kind of activation functions, the initial values and time parameters of learning rate and momentum term etc. Input variables are historical data of previous days, such as flows, nonlinearly weather related temperatures and nonlinearly weather related rainfalls based on correlation analysis between the under prediction flow and each implicit input variable of different ANN structures [3]. The performance of each ANN structure is evaluated by the voting analysis based on eleven criteria, which are the root mean square error (RMSE), the correlation index (R), the mean absolute percentage error (MAPE), the mean percentage error (MPE), the mean percentage error (ME), the percentage volume in errors (VE), the percentage error in peak (MF), the normalized mean bias error (NMBE), the normalized root mean bias error (NRMSE), the Nash-Sutcliffe model efficiency coefficient (E) and the modified Nash-Sutcliffe model efficiency coefficient (E1). The next day flow for the test set is calculated using the best ANN structure's model. Consequently, the confidence intervals of various confidence levels for training, evaluation and test sets are compared in order to explore the generalisation dynamics of confidence intervals from training and evaluation sets. [1] H.S. Hippert, C.E. Pedreira, R.C. Souza, "Neural networks for short-term load forecasting: A review and evaluation," IEEE Trans. on Power Systems, vol. 16, no. 1, 2001, pp. 44-55. [2] G. J. Tsekouras, N.E. Mastorakis, F.D. Kanellos, V.T. Kontargyri, C.D. Tsirekis, I.S. Karanasiou, Ch.N. Elias, A.D. Salis, P.A. Kontaxis, A.A. Gialketsi: "Short term load forecasting in Greek interconnected power system using ANN: Confidence Interval using a novel re-sampling technique with corrective Factor", WSEAS International Conference on Circuits, Systems, Electronics, Control & Signal Processing, (CSECS '10), Vouliagmeni, Athens, Greece, December 29-31, 2010. [3] D. Panagoulia, I. Trichakis, G. J. Tsekouras: "Flow Forecasting via Artificial Neural Networks - A Study for Input Variables conditioned on atmospheric circulation", European Geosciences Union, General Assembly 2012 (NH1.1 / AS1.16 - Extreme meteorological and hydrological events induced by severe weather and climate change), Vienna, Austria, 22-27 April 2012.

Component-cost and performance based comparison of flow and static batteries

NASA Astrophysics Data System (ADS)

Hopkins, Brandon J.; Smith, Kyle C.; Slocum, Alexander H.; Chiang, Yet-Ming

2015-10-01

Flow batteries are a promising grid-storage technology that is scalable, inherently flexible in power/energy ratio, and potentially low cost in comparison to conventional or ;static; battery architectures. Recent advances in flow chemistries are enabling significantly higher energy density flow electrodes. When the same battery chemistry can arguably be used in either a flow or static electrode design, the relative merits of either design choice become of interest. Here, we analyze the costs of the electrochemically active stack for both architectures under the constraint of constant energy efficiency and charge and discharge rates, using as case studies the aqueous vanadium-redox chemistry, widely used in conventional flow batteries, and aqueous lithium-iron-phosphate (LFP)/lithium-titanium-phosphate (LTP) suspensions, an example of a higher energy density suspension-based electrode. It is found that although flow batteries always have a cost advantage (kWh-1) at the stack level modeled, the advantage is a strong function of flow electrode energy density. For the LFP/LTP case, the cost advantages decreases from ∼50% to ∼10% over experimentally reasonable ranges of suspension loading. Such results are important input for design choices when both battery architectures are viable options.

Effects of Wall-Normal and Angular Momentum Injections in Airfoil Separation Control

NASA Astrophysics Data System (ADS)

Munday, Phillip M.; Taira, Kunihiko

2018-05-01

The objective of this computational study is to quantify the influence of wall-normal and angular momentum injections in suppressing laminar flow separation over a canonical airfoil. Open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at $\\alpha = 9^\\circ$ and $Re = 23,000$ is examined with large-eddy simulations. This study independently introduces wall-normal momentum and angular momentum into the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. It is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Lift enhancement and suppression of separation with the wall-normal and angular momentum inputs are characterized by modifying the standard definition of the coefficient of momentum. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With this single modified coefficient of momentum, we are able to categorize each controlled flow into separated, transitional, and attached flows.

User guide for MODPATH version 6 - A particle-tracking model for MODFLOW

USGS Publications Warehouse

Pollock, David W.

2012-01-01

MODPATH is a particle-tracking post-processing model that computes three-dimensional flow paths using output from groundwater flow simulations based on MODFLOW, the U.S. Geological Survey (USGS) finite-difference groundwater flow model. This report documents MODPATH version 6. Previous versions were documented in USGS Open-File Reports 89-381 and 94-464. The program uses a semianalytical particle-tracking scheme that allows an analytical expression of a particle's flow path to be obtained within each finite-difference grid cell. A particle's path is computed by tracking the particle from one cell to the next until it reaches a boundary, an internal sink/source, or satisfies another termination criterion. Data input to MODPATH consists of a combination of MODFLOW input data files, MODFLOW head and flow output files, and other input files specific to MODPATH. Output from MODPATH consists of several output files, including a number of particle coordinate output files intended to serve as input data for other programs that process, analyze, and display the results in various ways. MODPATH is written in FORTRAN and can be compiled by any FORTRAN compiler that fully supports FORTRAN-2003 or by most commercially available FORTRAN-95 compilers that support the major FORTRAN-2003 language extensions.

Active Management of Integrated Geothermal-CO2 Storage Reservoirs in Sedimentary Formations

DOE Data Explorer

Buscheck, Thomas A.

2012-01-01

Active Management of Integrated Geothermal–CO2 Storage Reservoirs in Sedimentary Formations: An Approach to Improve Energy Recovery and Mitigate Risk : FY1 Final Report The purpose of phase 1 is to determine the feasibility of integrating geologic CO2 storage (GCS) with geothermal energy production. Phase 1 includes reservoir analyses to determine injector/producer well schemes that balance the generation of economically useful flow rates at the producers with the need to manage reservoir overpressure to reduce the risks associated with overpressure, such as induced seismicity and CO2 leakage to overlying aquifers. This submittal contains input and output files of the reservoir model analyses. A reservoir-model "index-html" file was sent in a previous submittal to organize the reservoir-model input and output files according to sections of the FY1 Final Report to which they pertain. The recipient should save the file: Reservoir-models-inputs-outputs-index.html in the same directory that the files: Section2.1.*.tar.gz files are saved in.

Active Management of Integrated Geothermal-CO2 Storage Reservoirs in Sedimentary Formations

DOE Data Explorer

Buscheck, Thomas A.

2000-01-01

Active Management of Integrated Geothermal–CO2 Storage Reservoirs in Sedimentary Formations: An Approach to Improve Energy Recovery and Mitigate Risk: FY1 Final Report The purpose of phase 1 is to determine the feasibility of integrating geologic CO2 storage (GCS) with geothermal energy production. Phase 1 includes reservoir analyses to determine injector/producer well schemes that balance the generation of economically useful flow rates at the producers with the need to manage reservoir overpressure to reduce the risks associated with overpressure, such as induced seismicity and CO2 leakage to overlying aquifers. This submittal contains input and output files of the reservoir model analyses. A reservoir-model "index-html" file was sent in a previous submittal to organize the reservoir-model input and output files according to sections of the FY1 Final Report to which they pertain. The recipient should save the file: Reservoir-models-inputs-outputs-index.html in the same directory that the files: Section2.1.*.tar.gz files are saved in.

TWINTN4: A program for transonic four-wall interference assessment in two-dimensional wind tunnels

NASA Technical Reports Server (NTRS)

Kemp, W. B., Jr.

1984-01-01

A method for assessing the wall interference in transonic two-dimensional wind tunnel tests including the effects of the tunnel sidewall boundary layer was developed and implemented in a computer program named TWINTN4. The method involves three successive solutions of the transonic small disturbance potential equation to define the wind tunnel flow, the equivalent free air flow around the model, and the perturbation attributable to the model. Required input includes pressure distributions on the model and along the top and bottom tunnel walls which are used as boundary conditions for the wind tunnel flow. The wall-induced perturbation field is determined as the difference between the perturbation in the tunnel flow solution and the perturbation attributable to the model. The methodology used in the program is described and detailed descriptions of the computer program input and output are presented. Input and output for a sample case are given.

Airflow and optic flow mediate antennal positioning in flying honeybees

PubMed Central

Roy Khurana, Taruni; Sane, Sanjay P

2016-01-01

To maintain their speeds during navigation, insects rely on feedback from their visual and mechanosensory modalities. Although optic flow plays an essential role in speed determination, it is less reliable under conditions of low light or sparse landmarks. Under such conditions, insects rely on feedback from antennal mechanosensors but it is not clear how these inputs combine to elicit flight-related antennal behaviours. We here show that antennal movements of the honeybee, Apis mellifera, are governed by combined visual and antennal mechanosensory inputs. Frontal airflow, as experienced during forward flight, causes antennae to actively move forward as a sigmoidal function of absolute airspeed values. However, corresponding front-to-back optic flow causes antennae to move backward, as a linear function of relative optic flow, opposite the airspeed response. When combined, these inputs maintain antennal position in a state of dynamic equilibrium. DOI: http://dx.doi.org/10.7554/eLife.14449.001 PMID:27097104

Closed-Loop Control of Chemical Injection Rate for a Direct Nozzle Injection System

PubMed Central

Cai, Xiang; Walgenbach, Martin; Doerpmond, Malte; Schulze Lammers, Peter; Sun, Yurui

2016-01-01

To realize site-specific and variable-rate application of agricultural pesticides, accurately metering and controlling the chemical injection rate is necessary. This study presents a prototype of a direct nozzle injection system (DNIS) by which chemical concentration transport lag was greatly reduced. In this system, a rapid-reacting solenoid valve (RRV) was utilized for injecting chemicals, driven by a pulse-width modulation (PWM) signal at 100 Hz, so with varying pulse width the chemical injection rate could be adjusted. Meanwhile, a closed-loop control strategy, proportional-integral-derivative (PID) method, was applied for metering and stabilizing the chemical injection rate. In order to measure chemical flow rates and input them into the controller as a feedback in real-time, a thermodynamic flowmeter that was independent of chemical viscosity was used. Laboratory tests were conducted to assess the performance of DNIS and PID control strategy. Due to the nonlinear input–output characteristics of the RRV, a two-phase PID control process obtained better effects as compared with single PID control strategy. Test results also indicated that the set-point chemical flow rate could be achieved within less than 4 s, and the output stability was improved compared to the case without control strategy. PMID:26805833

Waterborne nutrient flow through an upland-peatland watershed in Minnesota

Treesearch

Elon S. Verry; D.R. Timmons

1982-01-01

Water and nutrient flow were measured on a complex upland-peatland watershed in north central Minnesota. Annual water budgets for upland and peatland components and for the total watershed were developed. Nutrient input and output budgets were developed for each component on a seasonal basis, using net precipitation inputs, and an annual nutrient budget was developed...

A three-dimensional potential-flow program with a geometry package for input data generation

NASA Technical Reports Server (NTRS)

Halsey, N. D.

1978-01-01

Information needed to run a computer program for the calculation of the potential flow about arbitrary three dimensional lifting configurations is presented. The program contains a geometry package which greatly reduces the task of preparing the input data. Starting from a very sparse set of coordinate data, the program automatically augments and redistributes the coordinates, calculates curves of intersection between components, and redistributes coordinates in the regions adjacent to the intersection curves in a suitable manner for use in the potential flow calculations. A brief summary of the program capabilities and options is given, as well as detailed instructions for the data input, a suggested structure for the program overlay, and the output for two test cases.

Heat transfer in an evaporation-condensation system in simulated weightlessness conditions

NASA Astrophysics Data System (ADS)

Bologa, M. K.; Grosu, F. P.; Kozhevnikov, I. V.; Motorin, O. V.; Polikarpov, A. A.

2017-10-01

The process of heat transfer in an evaporation-condensation system (ECS) at circulation of dielectric liquid in a closed thermoelectrohydrodynamic (TEHD) loop consisting of an evaporator, a condenser and electrohydrodynamic (EHD) pump for pumping of heat carrier, is considered. Previously, the authors studied the dependence of heat transfer on the angle of rotation of TEHD loop in a vertical plane. The report contains the results of studies of heat transfer at electrohydrodynamic pumping of the heat carrier (8% solution of acetone in Freon 113) in the condenser area by means of EHD pump of “cone-cone” type. All elements of the ECS are arranged in a horizontal plane and the heat transfer from the heater to the condenser without EHD pumping is impossible. A pulsating heat carrier flow mode, depending on the heat input and the voltage applied to the pump, takes place at EHD pumping. As the input power is decreasing the frequency of the coolant pulsations as well as the departure diameter and number of vapour bubbles are also decreasing. At some critical heat input the pulsations disappear and the transition from turbulent mode to the laminar one takes place causing the decrease of the heat transfer coefficient. The increase of the pumping flow rate by raising the voltage applied to the EHD pump, results in a partial suppression of boiling. The maximum intensification of heat transfer is reached at pulsation frequency of 1.25 Hz. The maximum heat flow from the heater was 4.2·104 W/m2. Graphical representation and the physical interpretation of the results, which reflect the essence of the process, are given.

Estuarine wetland evolution including sea-level rise and infrastructure effects.

NASA Astrophysics Data System (ADS)

Rodriguez, Jose Fernando; Trivisonno, Franco; Rojas, Steven Sandi; Riccardi, Gerardo; Stenta, Hernan; Saco, Patricia Mabel

2015-04-01

Estuarine wetlands are an extremely valuable resource in terms of biotic diversity, flood attenuation, storm surge protection, groundwater recharge, filtering of surface flows and carbon sequestration. On a large scale the survival of these systems depends on the slope of the land and a balance between the rates of accretion and sea-level rise, but local man-made flow disturbances can have comparable effects. Climate change predictions for most of Australia include an accelerated sea level rise, which may challenge the survival of estuarine wetlands. Furthermore, coastal infrastructure poses an additional constraint on the adaptive capacity of these ecosystems. Numerical models are increasingly being used to assess wetland dynamics and to help manage some of these situations. We present results of a wetland evolution model that is based on computed values of hydroperiod and tidal range that drive vegetation preference. Our first application simulates the long term evolution of an Australian wetland heavily constricted by infrastructure that is undergoing the effects of predicted accelerated sea level rise. The wetland presents a vegetation zonation sequence mudflats - mangrove - saltmarsh from the seaward margin and up the topographic gradient but is also affected by compartmentalization due to internal road embankments and culverts that effectively attenuates tidal input to the upstream compartments. For this reason, the evolution model includes a 2D hydrodynamic module which is able to handle man-made flow controls and spatially varying roughness. It continually simulates tidal inputs into the wetland and computes annual values of hydroperiod and tidal range to update vegetation distribution based on preference to hydrodynamic conditions of the different vegetation types. It also computes soil accretion rates and updates roughness coefficient values according to evolving vegetation types. In order to explore in more detail the magnitude of flow attenuation due to roughness and its effects on the computation of tidal range and hydroperiod, we performed numerical experiments simulating floodplain flow on the side of a tidal creek using different roughness values. Even though the values of roughness that produce appreciable changes in hydroperiod and tidal range are relatively high, they are within the range expected for some of the wetland vegetation. Both applications of the model show that flow attenuation can play a major role in wetland hydrodynamics and that its effects must be considered when predicting wetland evolution under climate change scenarios, particularly in situations where existing infrastructure affects the flow.

Prediction of Welded Joint Strength in Plasma Arc Welding: A Comparative Study Using Back-Propagation and Radial Basis Neural Networks

NASA Astrophysics Data System (ADS)

Srinivas, Kadivendi; Vundavilli, Pandu R.; Manzoor Hussain, M.; Saiteja, M.

2016-09-01

Welding input parameters such as current, gas flow rate and torch angle play a significant role in determination of qualitative mechanical properties of weld joint. Traditionally, it is necessary to determine the weld input parameters for every new welded product to obtain a quality weld joint which is time consuming. In the present work, the effect of plasma arc welding parameters on mild steel was studied using a neural network approach. To obtain a response equation that governs the input-output relationships, conventional regression analysis was also performed. The experimental data was constructed based on Taguchi design and the training data required for neural networks were randomly generated, by varying the input variables within their respective ranges. The responses were calculated for each combination of input variables by using the response equations obtained through the conventional regression analysis. The performances in Levenberg-Marquardt back propagation neural network and radial basis neural network (RBNN) were compared on various randomly generated test cases, which are different from the training cases. From the results, it is interesting to note that for the above said test cases RBNN analysis gave improved training results compared to that of feed forward back propagation neural network analysis. Also, RBNN analysis proved a pattern of increasing performance as the data points moved away from the initial input values.

Evaluating Nitrate Contributions From Different Land Use Types Across a Regional Watershed Using Flow and Transport Models

NASA Astrophysics Data System (ADS)

Spansky, M. C.; Hyndman, D. W.; Long, D. T.; Pijanowski, B. C.

2004-05-01

Regional inputs of non-point source pollutants to groundwater, such as agriculturally-derived nitrate, have typically proven difficult to model due to sparse concentration data and complex system dynamics. We present an approach to evaluate the relative contribution of various land use types to groundwater nitrate across a regional Michigan watershed using groundwater flow and transport models. The models were parameterized based on land use data, and calibrated to a 20 year database of nitrate measured in drinking water wells. The database spans 1983-2003 and contains approximately 27,000 nitrate records for the five major counties encompassed by the watershed. The Grand Traverse Bay Watershed (GTBW), located in the northwest Lower Peninsula of Michigan, was chosen for this research. Groundwater flow and nitrate transport models were developed for the GTBW using MODFLOW2000 and RT3D, respectively. In a preliminary transport model, agricultural land uses were defined as the sole source of groundwater nitrate. Nitrate inputs were then refined to reflect variations in nitrogen loading rates for different agriculture types, including orchards, row crops, and pastureland. The calibration dataset was created by assigning spatial coordinates to each water well sample using address matching from a geographic information system (GIS). Preliminary results show that there is a significant link between agricultural sources and measured groundwater nitrate concentrations. In cases where observed concentrations remain significantly higher than simulated values, other sources of nitrate (e.g. septic tanks or abandoned agricultural fields) will be evaluated. This research will eventually incorporate temporal variations in fertilizer application rates and changing land use patterns to better represent fluid and solute fluxes at a regional scale.

Potential climate change impacts on a tropical estuary: Hilo Bay, Hawaii

NASA Astrophysics Data System (ADS)

Adolf, J.; LaPinta, J.; Marusek, J.; Pascoe, K.; Pugh, A.

2016-02-01

Hilo Bay is a tropical estuarine ecosystem on the northeast (windward) coast of Hawai`i Island that is potentially vulnerable to climate change effects mediated through elevated water temperatures and/or changing rainfall patterns that impact river and groundwater fluxes. Here, we document trends in water temperature, river flow and phytoplankton dynamics in Hilo Bay. Hilo Bay is fed by two major rivers, Wailuku and Honoli`i, both of which have shown long term declines in output over their 85 and 38 year monitoring periods (USGS), respectively. Time series of groundwater inputs to Hilo Bay do not exist, but the average estimated rate rivals that of average river inputs. Daily average Hilo Bay water temperatures have increased at a rate of 0.35 degrees C per year (p < 0.001) since measurement by the Hilo Bay water quality buoy began in 2010, with the warmest temperatures on record recorded Sept 2015. Salinity did not show a trend over this same time period. Phytoplankton showed a pronounced seasonal cycle in Hilo Bay with a long term average of 3.7 mg m-3 and dominance by diatoms that exploit the co-availability of silica and nitrate in this environment. On shorter time scales of days to < 1 week, flood events dramatically reduce Hilo Bay salinity, temperature and phytoplankton biomass. Coincidental atmospheric warming, SST warming in the adjacent North Pacific ocean, and declining river flows will likely work together to result in elevated SST in Hilo Bay if observed trends continue. The El Nino event that started this year is expected to exacerbate this warming through reduce river flow and warmer regional SST.

Implications of sediment transport by subglacial water flow for interpreting contemporary glacial erosion rates

NASA Astrophysics Data System (ADS)

Beaud, Flavien; Flowers, Gwenn E.; Venditti, Jeremy G.

2017-04-01

The role of glaciers in landscape evolution is central to the interactions between climate and tectonic forces at high latitudes and in mountainous regions. Sediment yields from glacierized basins are used to quantify contemporary erosion rates on seasonal to decadal timescales, often under the assumption that subglacial water flow is the main contributor to these yields. Two recent studies have furthermore used such sediment fluxes to calibrate a glacial erosion rule, where erosion rate scales with ice sliding speed raised to a power greater than one. Subglacial sediment transport by water flow has however seldom been studied, thus the controls on sediment yield from glacierized basins remain enigmatic. To bridge this gap, we develop a 1-D model of morphodynamics in semi-circular bedrock-floored subglacial channels. We adapt a sediment conservation law from the fluvial literature, developed for both mixed bedrock / alluvial and alluvial conditions, to subglacial channels. Channel evolution is a function of the traditional melt-opening due to viscous heat dissipation from the water flow, and creep closure of the overlying ice, to which we add the closure or enlargement due to sediment deposition or removal, respectively. Using a simple ice geometry representing a land-terminating glacier, we find that the shear stresses produced by the water flow on the bed decrease significantly near the terminus. As the ice thins, creep closure decreases and large hydraulic potential gradients cannot be sustained. The resulting gradients in sediment transport lead to a bottleneck, and sediment accumulates if the sediment supply is adequate. A similar bottleneck occurs if a channel is well established and water discharge drops. Whether such constriction happens in space of time, in the presence of a sufficiently large sediment supply sediment accumulates temporarily near the terminus, followed shortly thereafter by enhanced sediment transport. Reduction in the cross-sectional area of the channel by sediment storage leads to enhanced shear stresses and transport rates. As a result, assuming a constant sediment input and a seasonal water forcing sediment delivery to the proglacial environment undergoes two phases determined by a combination of meltwater discharge and channel development. In the stage of the melt season dominated by channel growth and increasing discharge, the sediment yield is virtually constant and matches the input. In contrast, during the stage dominated by channel closure and decreasing discharge the sediment yield exhibits daily fluctuations caused by temporary sediment storage in the channel. Our findings thus suggest that contemporary sediment yields may be controlled by the dynamics of subglacial water flow in the vicinity of the terminus. This provides a new perspective for the interpretation of proglacial sediment fluxes, fluxes which are central to refining glacial erosion laws utilized in landscape evolution models.

Modeling the influence of organic acids on soil weathering

NASA Astrophysics Data System (ADS)

Lawrence, Corey; Harden, Jennifer; Maher, Kate

2014-08-01

Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

Modeling the influence of organic acids on soil weathering

USGS Publications Warehouse

Lawrence, Corey R.; Harden, Jennifer W.; Maher, Kate

2014-01-01

Biological inputs and organic matter cycling have long been regarded as important factors in the physical and chemical development of soils. In particular, the extent to which low molecular weight organic acids, such as oxalate, influence geochemical reactions has been widely studied. Although the effects of organic acids are diverse, there is strong evidence that organic acids accelerate the dissolution of some minerals. However, the influence of organic acids at the field-scale and over the timescales of soil development has not been evaluated in detail. In this study, a reactive-transport model of soil chemical weathering and pedogenic development was used to quantify the extent to which organic acid cycling controls mineral dissolution rates and long-term patterns of chemical weathering. Specifically, oxalic acid was added to simulations of soil development to investigate a well-studied chronosequence of soils near Santa Cruz, CA. The model formulation includes organic acid input, transport, decomposition, organic-metal aqueous complexation and mineral surface complexation in various combinations. Results suggest that although organic acid reactions accelerate mineral dissolution rates near the soil surface, the net response is an overall decrease in chemical weathering. Model results demonstrate the importance of organic acid input concentrations, fluid flow, decomposition and secondary mineral precipitation rates on the evolution of mineral weathering fronts. In particular, model soil profile evolution is sensitive to kaolinite precipitation and oxalate decomposition rates. The soil profile-scale modeling presented here provides insights into the influence of organic carbon cycling on soil weathering and pedogenesis and supports the need for further field-scale measurements of the flux and speciation of reactive organic compounds.

Numerical model simulations of nitrate concentrations in groundwater using various nitrogen input scenarios, mid-Snake region, south-central Idaho

USGS Publications Warehouse

Skinner, Kenneth D.; Rupert, Michael G.

2012-01-01

As part of the U.S. Geological Survey’s National Water Quality Assessment (NAWQA) program nitrate transport in groundwater was modeled in the mid-Snake River region in south-central Idaho to project future concentrations of nitrate. Model simulation results indicated that nitrate concentrations would continue to increase over time, eventually exceeding the U.S. Environmental Protection Agency maximum contaminant level for drinking water of 10 milligrams per liter in some areas. A subregional groundwater model simulated the change of nitrate concentrations in groundwater over time in response to three nitrogen input scenarios: (1) nitrogen input fixed at 2008 levels; (2) nitrogen input increased from 2008 to 2028 using the same rate of increase as the average rate of increase during the previous 10 years (1998 through 2008); after 2028, nitrogen input is fixed at 2028 levels; and (3) nitrogen input related to agriculture completely halted, with only nitrogen input from precipitation remaining. Scenarios 1 and 2 project that nitrate concentrations in groundwater continue to increase from 10 to 50 years beyond the year nitrogen input is fixed, depending on the location in the model area. Projected nitrate concentrations in groundwater increase by as much as 2–4 milligrams per liter in many areas, with nitrate concentrations in some areas reaching 10 milligrams per liter. Scenario 3, although unrealistic, estimates how long (20–50 years) it would take nitrate in groundwater to return to background concentrations—the “flushing time” of the system. The amount of nitrate concentration increase cannot be explained solely by differences in nitrogen input; in fact, some areas with the highest amount of nitrogen input have the lowest increase in nitrate concentration. The geometry of the aquifer and the pattern of regional groundwater flow through the aquifer greatly influence nitrate concentrations. The aquifer thins toward discharge areas along the Snake River which forces upward convergence of good-quality regional groundwater that mixes with the nitrate-laden groundwater in the uppermost parts of the aquifer, which results in lowered nitrate concentrations. A new method of inputting nitrogen to the subregional groundwater model was used that prorates nitrogen input by the probability of detecting nitrate concentrations greater than 2 mg/L. The probability map is based on correlations with physical factors, and prorates an existing nitrogen input dataset providing an estimate of nitrogen flux to the water table that accounts for new factors such as soil properties. The effectiveness of this updated nitrogen input method was evaluated using the software UCODE_2005.

Flow cytometer acquisition and detection system

DOEpatents

Casstevens, Martin K.; Burzynski, Ryszard; Weibel, John; Kachynski, Alexander

2010-05-04

A flow cytometer has a flow cell through which a sample flows and at least one laser emitting an excitation beam for illuminating a corresponding interrogation region in the flow cell. Scattered and fluorescence light from each interrogation region is collected by one or more input fibers for that region, and the input fiber(s) are fed to a dispersion module for that interrogation region that disperses the incoming light into different spectral regions. The dispersed light is conveyed, such as by a plurality of output fibers, to one or more photosensitive detectors. Thus, time multiplexed light signals may be delivered to a detector whereby several unique light signals can be measured by a single detector.

Measurement of myocardial blood flow by cardiovascular magnetic resonance perfusion: comparison of distributed parameter and Fermi models with single and dual bolus.

PubMed

Papanastasiou, Giorgos; Williams, Michelle C; Kershaw, Lucy E; Dweck, Marc R; Alam, Shirjel; Mirsadraee, Saeed; Connell, Martin; Gray, Calum; MacGillivray, Tom; Newby, David E; Semple, Scott Ik

2015-02-17

Mathematical modeling of cardiovascular magnetic resonance perfusion data allows absolute quantification of myocardial blood flow. Saturation of left ventricle signal during standard contrast administration can compromise the input function used when applying these models. This saturation effect is evident during application of standard Fermi models in single bolus perfusion data. Dual bolus injection protocols have been suggested to eliminate saturation but are much less practical in the clinical setting. The distributed parameter model can also be used for absolute quantification but has not been applied in patients with coronary artery disease. We assessed whether distributed parameter modeling might be less dependent on arterial input function saturation than Fermi modeling in healthy volunteers. We validated the accuracy of each model in detecting reduced myocardial blood flow in stenotic vessels versus gold-standard invasive methods. Eight healthy subjects were scanned using a dual bolus cardiac perfusion protocol at 3T. We performed both single and dual bolus analysis of these data using the distributed parameter and Fermi models. For the dual bolus analysis, a scaled pre-bolus arterial input function was used. In single bolus analysis, the arterial input function was extracted from the main bolus. We also performed analysis using both models of single bolus data obtained from five patients with coronary artery disease and findings were compared against independent invasive coronary angiography and fractional flow reserve. Statistical significance was defined as two-sided P value < 0.05. Fermi models overestimated myocardial blood flow in healthy volunteers due to arterial input function saturation in single bolus analysis compared to dual bolus analysis (P < 0.05). No difference was observed in these volunteers when applying distributed parameter-myocardial blood flow between single and dual bolus analysis. In patients, distributed parameter modeling was able to detect reduced myocardial blood flow at stress (<2.5 mL/min/mL of tissue) in all 12 stenotic vessels compared to only 9 for Fermi modeling. Comparison of single bolus versus dual bolus values suggests that distributed parameter modeling is less dependent on arterial input function saturation than Fermi modeling. Distributed parameter modeling showed excellent accuracy in detecting reduced myocardial blood flow in all stenotic vessels.

Carbon monoxide mass transfer for syngas fermentation in a stirred tank reactor with dual impeller configurations.

PubMed

Ungerman, Andrew J; Heindel, Theodore J

2007-01-01

This study compares the power demand and gas-liquid volumetric mass transfer coefficient, kLa, in a stirred tank reactor (STR) (T = 0.211 m) using different impeller designs and schemes in a carbon monoxide-water system, which is applicable to synthesis gas (syngas) fermentation. Eleven different impeller schemes were tested over a range of operating conditions typically associated with the "after large cavity" region (ALC) of a Rushton-type turbine (D/T = 0.35). It is found that the dual Rushton-type impeller scheme exhibits the highest volumetric mass transfer rates for all operating conditions; however, it also displays the lowest mass transfer performance (defined as the volumetric mass transfer coefficient per unit power input) for all conditions due to its high power consumption. Dual impeller schemes with an axial flow impeller as the top impeller show improved mass transfer rates without dramatic increases in power draw. At high gas flow rates, dual impeller schemes with a lower concave impeller have kLa values similar to those of the Rushton-type dual impeller schemes but show improved mass transfer performance. It is believed that the mass transfer performance can be further enhanced for the bottom concave impeller schemes by operating at conditions beyond the ALC region defined for Rushton-type impellers because the concave impeller can handle higher gas flow rates prior to flooding.

Field emission microplasma actuation for microchannel flows

NASA Astrophysics Data System (ADS)

Sashank Tholeti, Siva; Shivkumar, Gayathri; Alexeenko, Alina A.

2016-06-01

Microplasmas offer attractive flow control methodology for gas transport in microsystems where large viscous losses make conventional pumping methods highly inefficient. We study microscale flow actuation by dielectric-barrier discharge (DBD) with field emission (FE) of electrons, which allows lowering the operational voltage from kV to a few hundred volts and below. A feasibility study of FE-DBD for flow actuation is performed using 2D particle-in-cell method with Monte Carlo collisions (PIC/MCC) at 10 MHz in nitrogen at atmospheric pressure. The free diffusion dominated, high velocity field emission electrons create a large positive space charge and a body force on the order of 106 N m-3. The body force and Joule heat decrease with increase in dielectric thickness and electrode thickness. The body force also decreases at lower pressures. The plasma body force distribution along with the Joule heating is then used in the Navier-Stokes simulations to quantify the flow actuation in a microchannel. Theoretical analysis and simulations for plasma actuated planar Poiseuille flow show that the gain in flow rate is inversely proportional to Reynolds number. This theoretical analysis is in good agreement with the simulations for a microchannel with closely placed actuators under incompressible conditions. Flow rate of FE-DBD driven 2D microchannel is around 100 ml min-1 mm-1 for an input power of 64 μW mm-1. The gas temperature rises by 1500 K due to the Joule heating, indicating FE-DBD’s potential for microcombustion, micropropulsion and chemical sensing in addition to microscale pumping and mixing applications.

Observations on preferential flow and horizontal transport of nitrogen fertilizer in the unsaturated zone

USGS Publications Warehouse

Wilkison, D.H.; Blevins, D.W.

1999-01-01

A study site underlain by a claypan soil was instrumented to examine the transport of fertilizer nitrogen (N) under corn (Zea mays L.) cultivation. The study was designed to examine N transport within the unsaturated zone and in interflow (the saturated flow of water on top of the claypan). A 15N- labeled fertilizer (labeled N), bromide (Br), and chloride (Cl) were used as field tracers. Rapid or prolonged infiltration events allowed water and dissolved solutes to perch on the claypan for brief periods. However, a well- developed network of preferential flow paths quickly diverted water and solutes through the claypan and into the underlying glacial till aquifer. Excess fertilizer N in the unsaturated zone supplied a continuous, but declining input of N to ground water for a period of 15 mo after a single fertilizer application. Calculated solute velocities through the claypan matrix (6.4 x 10-6 cm s-1) were similar to horizontal transport rates along the claypan (3.5 to 7.3 x 10-6 cm s-1) but much slower than infiltration rates determined for preferential flow paths (1.67 x 10-3 cm s-1). These flow paths accounted for 35% of the transport. A seasonally variable, dual mode of transport (matrix and preferential flow) prevented the claypan from being an effective barrier to vertical transport. Simulations of selected field observations, conducted using the variably saturated two- dimensional flow and transport model, VS2DT, confirmed the presence of a dual flow regime in the claypan.

Flow behavior and mobility of contaminated waste rock materials in the abandoned Imgi mine in Korea

NASA Astrophysics Data System (ADS)

Jeong, S. W.; Wu, Y.-H.; Cho, Y. C.; Ji, S. W.

2018-01-01

Incomplete mine reclamation can cause ecological and environmental impacts. This paper focuses on the geotechnical and rheological characteristics of waste rock materials, which are mainly composed of sand-size particles, potentially resulting in mass movement (e.g., slide or flow) and extensive acid mine drainage. To examine the potential for contaminant mobilization resulting from physicochemical processes in abandoned mines, a series of scenario-based debris flow simulations was conducted using Debris-2D to identify different hazard scenarios and volumes. The flow behavior of waste rock materials was examined using a ball-measuring rheometric apparatus, which can be adapted for large particle samples, such as debris flow. Bingham yield stresses determined in controlled shear rate mode were used as an input parameter in the debris flow modeling. The yield stresses ranged from 100 to 1000 Pa for shear rates ranging from 10- 5 to 102 s- 1. The results demonstrated that the lowest yield stress could result in high mobility of debris flow (e.g., runout distance > 700 m from the source area for 60 s); consequently, the material contaminants may easily reach the confluence of the Suyoung River through a mountain stream. When a fast slide or debris flow occurs at or near an abandoned mine area, it may result in extremely dynamic and destructive geomorphological changes. Even for the highest yield stress of debris flow simulation (i.e., τy = 2000 Pa), the released debris could flow into the mountain stream; therefore, people living near abandoned mines may become exposed to water pollution throughout the day. To maintain safety at and near abandoned mines, the physicochemical properties of waste materials should be monitored, and proper mitigation measures post-mining should be considered in terms of both their physical damage and chemical pollution potential.

PYFLOW 2.0. A new open-source software for quantifying the impact and depositional properties of dilute pyroclastic density currents

NASA Astrophysics Data System (ADS)

Dioguardi, Fabio; Dellino, Pierfrancesco

2017-04-01

Dilute pyroclastic density currents (DPDC) are ground-hugging turbulent gas-particle flows that move down volcano slopes under the combined action of density contrast and gravity. DPDCs are dangerous for human lives and infrastructures both because they exert a dynamic pressure in their direction of motion and transport volcanic ash particles, which remain in the atmosphere during the waning stage and after the passage of a DPDC. Deposits formed by the passage of a DPDC show peculiar characteristics that can be linked to flow field variables with sedimentological models. Here we present PYFLOW_2.0, a significantly improved version of the code of Dioguardi and Dellino (2014) that was already extensively used for the hazard assessment of DPDCs at Campi Flegrei and Vesuvius (Italy). In the latest new version the code structure, the computation times and the data input method have been updated and improved. A set of shape-dependent drag laws have been implemented as to better estimate the aerodynamic drag of particles transported and deposited by the flow. A depositional model for calculating the deposition time and rate of the ash and lapilli layer formed by the pyroclastic flow has also been included. This model links deposit (e.g. componentry, grainsize) to flow characteristics (e.g. flow average density and shear velocity), the latter either calculated by the code itself or given in input by the user. The deposition rate is calculated by summing the contributions of each grainsize class of all components constituting the deposit (e.g. juvenile particles, crystals, etc.), which are in turn computed as a function of particle density, terminal velocity, concentration and deposition probability. Here we apply the concept of deposition probability, previously introduced for estimating the deposition rates of turbidity currents (Stow and Bowen, 1980), to DPDCs, although with a different approach, i.e. starting from what is observed in the deposit (e.g. the weight fractions ratios between the different grainsize classes). In this way, more realistic estimates of the deposition rate can be obtained, as the deposition probability of different grainsize constituting the DPDC deposit could be different and not necessarily equal to unity. Calculations of the deposition rates of large-scale experiments, previously computed with different methods, have been performed as experimental validation and are presented. Results of model application to DPDCs and turbidity currents will also be presented. Dioguardi, F, and P. Dellino (2014), PYFLOW: A computer code for the calculation of the impact parameters of Dilute Pyroclastic Density Currents (DPDC) based on field data, Powder Technol., 66, 200-210, doi:10.1016/j.cageo.2014.01.013 Stow, D. A. V., and A. J. Bowen (1980), A physical model for the transport and sorting of fine-grained sediment by turbidity currents, Sedimentology, 27, 31-46

Computer program for flat sector thrust bearing performance

NASA Technical Reports Server (NTRS)

Presler, A. F.; Etsion, I.

1977-01-01

A versatile computer program is presented which achieves a rapid, numerical solution of the Reynolds equation for a flat sector thrust pad bearing with either compressible or liquid lubricants. Program input includes a range in values of the geometric and operating parameters of the sector bearing. Performance characteristics are obtained from the calculated bearing pressure distribution. These are the load capacity, center of pressure coordinates, frictional energy dissipation, and flow rates of liquid lubricant across the bearing edges. Two sample problems are described.

Application of a Design Space Exploration Tool to Enhance Interleaver Generation

DTIC Science & Technology

2009-06-24

2], originally dedicated to channel coding, are being currently reused in a large set of the whole digital communication systems (e.g. equalization... originally target interface synthesis, is shown to be also suited to the interleaver design space exploration. Our design flow can take as input...slice turbo codes,” in Proc. 3rd Int. Symp. Turbo Codes, Related Topics, Brest , 2003, pp. 343–346. [11] IEEE 802.15.3a, WPAN High Rate Alternative [12

Quantitative Functional Imaging Using Dynamic Positron Computed Tomography and Rapid Parameter Estimation Techniques

NASA Astrophysics Data System (ADS)

Koeppe, Robert Allen

Positron computed tomography (PCT) is a diagnostic imaging technique that provides both three dimensional imaging capability and quantitative measurements of local tissue radioactivity concentrations in vivo. This allows the development of non-invasive methods that employ the principles of tracer kinetics for determining physiological properties such as mass specific blood flow, tissue pH, and rates of substrate transport or utilization. A physiologically based, two-compartment tracer kinetic model was derived to mathematically describe the exchange of a radioindicator between blood and tissue. The model was adapted for use with dynamic sequences of data acquired with a positron tomograph. Rapid estimation techniques were implemented to produce functional images of the model parameters by analyzing each individual pixel sequence of the image data. A detailed analysis of the performance characteristics of three different parameter estimation schemes was performed. The analysis included examination of errors caused by statistical uncertainties in the measured data, errors in the timing of the data, and errors caused by violation of various assumptions of the tracer kinetic model. Two specific radioindicators were investigated. ('18)F -fluoromethane, an inert freely diffusible gas, was used for local quantitative determinations of both cerebral blood flow and tissue:blood partition coefficient. A method was developed that did not require direct sampling of arterial blood for the absolute scaling of flow values. The arterial input concentration time course was obtained by assuming that the alveolar or end-tidal expired breath radioactivity concentration is proportional to the arterial blood concentration. The scale of the input function was obtained from a series of venous blood concentration measurements. The method of absolute scaling using venous samples was validated in four studies, performed on normal volunteers, in which directly measured arterial concentrations were compared to those predicted from the expired air and venous blood samples. The glucose analog ('18)F-3-deoxy-3-fluoro-D -glucose (3-FDG) was used for quantitating the membrane transport rate of glucose. The measured data indicated that the phosphorylation rate of 3-FDG was low enough to allow accurate estimation of the transport rate using a two compartment model.

Ensemble engineering and statistical modeling for parameter calibration towards optimal design of microbial fuel cells

NASA Astrophysics Data System (ADS)

Sun, Hongyue; Luo, Shuai; Jin, Ran; He, Zhen

2017-07-01

Mathematical modeling is an important tool to investigate the performance of microbial fuel cell (MFC) towards its optimized design. To overcome the shortcoming of traditional MFC models, an ensemble model is developed through integrating both engineering model and statistical analytics for the extrapolation scenarios in this study. Such an ensemble model can reduce laboring effort in parameter calibration and require fewer measurement data to achieve comparable accuracy to traditional statistical model under both the normal and extreme operation regions. Based on different weight between current generation and organic removal efficiency, the ensemble model can give recommended input factor settings to achieve the best current generation and organic removal efficiency. The model predicts a set of optimal design factors for the present tubular MFCs including the anode flow rate of 3.47 mL min-1, organic concentration of 0.71 g L-1, and catholyte pumping flow rate of 14.74 mL min-1 to achieve the peak current at 39.2 mA. To maintain 100% organic removal efficiency, the anode flow rate and organic concentration should be controlled lower than 1.04 mL min-1 and 0.22 g L-1, respectively. The developed ensemble model can be potentially modified to model other types of MFCs or bioelectrochemical systems.

Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Jeomoh, E-mail: jkim610@gatech.edu; Ji, Mi-Hee; Detchprohm, Theeradetch

2015-09-28

Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effectivemore » partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.« less

Non-invasive classification of gas-liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

NASA Astrophysics Data System (ADS)

Musa Abbagoni, Baba; Yeung, Hoi

2016-08-01

The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas-liquid flow regimes objectively with the gas-liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase flow. Experimental data is obtained on a horizontal test rig with a total pipe length of 21 m and 5.08 cm internal diameter carrying air-water two-phase flow under slug, elongated bubble, stratified-wavy and, stratified flow regimes. Multilayer perceptron neural networks (MLPNNs) are used to develop the classification model. The classifier requires features as an input which is representative of the signals. Ultrasound signal features are extracted by applying both power spectral density (PSD) and discrete wavelet transform (DWT) methods to the flow signals. A classification scheme of ‘1-of-C coding method for classification’ was adopted to classify features extracted into one of four flow regime categories. To improve the performance of the flow regime classifier network, a second level neural network was incorporated by using the output of a first level networks feature as an input feature. The addition of the two network models provided a combined neural network model which has achieved a higher accuracy than single neural network models. Classification accuracies are evaluated in the form of both the PSD and DWT features. The success rates of the two models are: (1) using PSD features, the classifier missed 3 datasets out of 24 test datasets of the classification and scored 87.5% accuracy; (2) with the DWT features, the network misclassified only one data point and it was able to classify the flow patterns up to 95.8% accuracy. This approach has demonstrated the success of a clamp-on ultrasound sensor for flow regime classification that would be possible in industry practice. It is considerably more promising than other techniques as it uses a non-invasive and non-radioactive sensor.

Developing guidelines for elementary flow nomenclature

EPA Science Inventory

In general, a flow in life cycle inventory data refers to an input or output to a process. Flows may be of two broad types: elementary flows or intermediate (known as “technosphere”) flows according to ISO 14044 (ISO 14044 2006). Elementary flows may be defined as mat...

Three-dimensional steady flow computations in manifold-type junctions and a comparison with experiment

NASA Astrophysics Data System (ADS)

Kuo, Tang-Wei; Chang, Shengming

Results of three-dimensional steady flow calculations are compared with existing pressure and velocity measurements of two manifold-type junctions. The junctions consist of a main duct and a side branch, both with the same rectangular cross section, with the side branch joining the main duct at an angle of either 90 or 45 degrees. Both combining and dividing flow configurations are considered for different total mass flow rates and different side-branch-to-main-duct mass flow ratios. One objective of this investigation was to assess the effects of numerical differencing scheme and mesh refinement on solution accuracy, and both parameters showed strong influences on the computed results. It is shown that calculations should be made with the highest possible level of numerical accuracy and grid resolution in regions of flow recirculation. Comparisons of computed and measured velocities, static pressures, and flow loss coefficients are presented in this paper. For most cases considered, the model predictions are in good agreement with the measurements. Results can be used as input loss coefficients to an engine-simulation code, in addition to being used to evaluate a specific junction design.

Nonlinear extension of a hemodynamic linear model for coherent hemodynamics spectroscopy.

PubMed

Sassaroli, Angelo; Kainerstorfer, Jana M; Fantini, Sergio

2016-01-21

In this work, we are proposing an extension of a recent hemodynamic model (Fantini, 2014a), which was developed within the framework of a novel approach to the study of tissue hemodynamics, named coherent hemodynamics spectroscopy (CHS). The previous hemodynamic model, from a signal processing viewpoint, treats the tissue microvasculature as a linear time-invariant system, and considers changes of blood volume, capillary blood flow velocity and the rate of oxygen diffusion as inputs, and the changes of oxy-, deoxy-, and total hemoglobin concentrations (measured in near infrared spectroscopy) as outputs. The model has been used also as a forward solver in an inversion procedure to retrieve quantitative parameters that assess physiological and biological processes such as microcirculation, cerebral autoregulation, tissue metabolic rate of oxygen, and oxygen extraction fraction. Within the assumption of "small" capillary blood flow velocity oscillations the model showed that the capillary and venous compartments "respond" to this input as low pass filters, characterized by two distinct impulse response functions. In this work, we do not make the assumption of "small" perturbations of capillary blood flow velocity by solving without approximations the partial differential equation that governs the spatio-temporal behavior of hemoglobin saturation in capillary and venous blood. Preliminary comparison between the linear time-invariant model and the extended model (here identified as nonlinear model) are shown for the relevant parameters measured in CHS as a function of the oscillation frequency (CHS spectra). We have found that for capillary blood flow velocity oscillations with amplitudes up to 10% of the baseline value (which reflect typical scenarios in CHS), the discrepancies between CHS spectra obtained with the linear and nonlinear models are negligible. For larger oscillations (~50%) the linear and nonlinear models yield CHS spectra with differences within typical experimental errors, but further investigation is needed to assess the effect of these differences. Flow oscillations larger than 10-20% are not typically induced in CHS; therefore, the results presented in this work indicate that a linear hemodynamic model, combined with a method to elicit controlled hemodynamic oscillations (as done for CHS), is appropriate for the quantitative assessment of cerebral microcirculation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Validity of computational hemodynamics in human arteries based on 3D time-of-flight MR angiography and 2D electrocardiogram gated phase contrast images

NASA Astrophysics Data System (ADS)

Yu, Huidan (Whitney); Chen, Xi; Chen, Rou; Wang, Zhiqiang; Lin, Chen; Kralik, Stephen; Zhao, Ye

2015-11-01

In this work, we demonstrate the validity of 4-D patient-specific computational hemodynamics (PSCH) based on 3-D time-of-flight (TOF) MR angiography (MRA) and 2-D electrocardiogram (ECG) gated phase contrast (PC) images. The mesoscale lattice Boltzmann method (LBM) is employed to segment morphological arterial geometry from TOF MRA, to extract velocity profiles from ECG PC images, and to simulate fluid dynamics on a unified GPU accelerated computational platform. Two healthy volunteers are recruited to participate in the study. For each volunteer, a 3-D high resolution TOF MRA image and 10 2-D ECG gated PC images are acquired to provide the morphological geometry and the time-varying flow velocity profiles for necessary inputs of the PSCH. Validation results will be presented through comparisons of LBM vs. 4D Flow Software for flow rates and LBM simulation vs. MRA measurement for blood flow velocity maps. Indiana University Health (IUH) Values Fund.

Mathematical modelling of flow distribution in the human cardiovascular system

NASA Technical Reports Server (NTRS)

Sud, V. K.; Srinivasan, R. S.; Charles, J. B.; Bungo, M. W.

1992-01-01

The paper presents a detailed model of the entire human cardiovascular system which aims to study the changes in flow distribution caused by external stimuli, changes in internal parameters, or other factors. The arterial-venous network is represented by 325 interconnected elastic segments. The mathematical description of each segment is based on equations of hydrodynamics and those of stress/strain relationships in elastic materials. Appropriate input functions provide for the pumping of blood by the heart through the system. The analysis employs the finite-element technique which can accommodate any prescribed boundary conditions. Values of model parameters are from available data on physical and rheological properties of blood and blood vessels. As a representative example, simulation results on changes in flow distribution with changes in the elastic properties of blood vessels are discussed. They indicate that the errors in the calculated overall flow rates are not significant even in the extreme case of arteries and veins behaving as rigid tubes.

Control volume analyses of glottal flow using a fully-coupled numerical fluid-structure interaction model

NASA Astrophysics Data System (ADS)

Yang, Jubiao; Krane, Michael; Zhang, Lucy

2013-11-01

Vocal fold vibrations and the glottal jet are successfully simulated using the modified Immersed Finite Element method (mIFEM), a fully coupled dynamics approach to model fluid-structure interactions. A self-sustained and steady vocal fold vibration is captured given a constant pressure input at the glottal entrance. The flow rates at different axial locations in the glottis are calculated, showing small variations among them due to the vocal fold motion and deformation. To further facilitate the understanding of the phonation process, two control volume analyses, specifically with Bernoulli's equation and Newton's 2nd law, are carried out for the glottal flow based on the simulation results. A generalized Bernoulli's equation is derived to interpret the correlations between the velocity and pressure temporally and spatially along the center line which is a streamline using a half-space model with symmetry boundary condition. A specialized Newton's 2nd law equation is developed and divided into terms to help understand the driving mechanism of the glottal flow.

Prediction of friction factor of pure water flowing inside vertical smooth and microfin tubes by using artificial neural networks

NASA Astrophysics Data System (ADS)

Çebi, A.; Akdoğan, E.; Celen, A.; Dalkilic, A. S.

2017-02-01

An artificial neural network (ANN) model of friction factor in smooth and microfin tubes under heating, cooling and isothermal conditions was developed in this study. Data used in ANN was taken from a vertically positioned heat exchanger experimental setup. Multi-layered feed-forward neural network with backpropagation algorithm, radial basis function networks and hybrid PSO-neural network algorithm were applied to the database. Inputs were the ratio of cross sectional flow area to hydraulic diameter, experimental condition number depending on isothermal, heating, or cooling conditions and mass flow rate while the friction factor was the output of the constructed system. It was observed that such neural network based system could effectively predict the friction factor values of the flows regardless of their tube types. A dependency analysis to determine the strongest parameter that affected the network and database was also performed and tube geometry was found to be the strongest parameter of all as a result of analysis.

Vacuum testing of a miniaturised switch mode amplifier powering an electrothermal plasma micro-thruster

NASA Astrophysics Data System (ADS)

Charles, Christine; Liang, Wei; Raymond, Luke; Rivas-Davila, Juan; Boswell, Roderick W.

2017-08-01

A structurally supportive miniaturised low-weight (≤150 g) radiofrequency switch mode amplifier developed to power the small diameter Pocket Rocket electrothermal plasma micro-thruster called MiniPR is tested in vacuum conditions representative of space to demonstrate its suitability for use on nano-satellites such as `CubeSats'. Argon plasma characterisation is carried out by measuring the optical emission signal seen through the plenum window versus frequency (12.8-13.8 MHz) and the plenum cavity pressure increase (indicative of thrust generation from volumetric gas heating in the plasma cavity) versus power (1-15 Watts) with the amplifier operating at atmospheric pressure and a constant flow rate of 20 sccm. Vacuum testing is subsequently performed by measuring the operational frequency range of the amplifier as a function of gas flow rate. The switch mode amplifier design is finely tuned to the input impedance of the thruster ˜16 pF) to provide a power efficiency of 88 % at the resonant frequency and a direct feed to a low-loss (˜ 10 %) impedance matching network. This system provides successful plasma coupling at 1.54 Watts for all investigated flow rates (10-130 sccm) for cryogenic pumping speeds of the order of 6000 l.s^{-1} and a vacuum pressure of the order of ˜ 2x10^{-5} Torr during operation. Interestingly, the frequency bandwidth for which a plasma can be coupled increases from 0.04 to 0.4 MHz when the gas flow rate is increased, probably as a result of changes in the plasma impedance.

River flow prediction using hybrid models of support vector regression with the wavelet transform, singular spectrum analysis and chaotic approach

NASA Astrophysics Data System (ADS)

Baydaroğlu, Özlem; Koçak, Kasım; Duran, Kemal

2018-06-01

Prediction of water amount that will enter the reservoirs in the following month is of vital importance especially for semi-arid countries like Turkey. Climate projections emphasize that water scarcity will be one of the serious problems in the future. This study presents a methodology for predicting river flow for the subsequent month based on the time series of observed monthly river flow with hybrid models of support vector regression (SVR). Monthly river flow over the period 1940-2012 observed for the Kızılırmak River in Turkey has been used for training the method, which then has been applied for predictions over a period of 3 years. SVR is a specific implementation of support vector machines (SVMs), which transforms the observed input data time series into a high-dimensional feature space (input matrix) by way of a kernel function and performs a linear regression in this space. SVR requires a special input matrix. The input matrix was produced by wavelet transforms (WT), singular spectrum analysis (SSA), and a chaotic approach (CA) applied to the input time series. WT convolutes the original time series into a series of wavelets, and SSA decomposes the time series into a trend, an oscillatory and a noise component by singular value decomposition. CA uses a phase space formed by trajectories, which represent the dynamics producing the time series. These three methods for producing the input matrix for the SVR proved successful, while the SVR-WT combination resulted in the highest coefficient of determination and the lowest mean absolute error.

Efficacy of bedrock erosion by subglacial water flow

NASA Astrophysics Data System (ADS)

Beaud, F.; Flowers, G. E.; Venditti, J. G.

2015-09-01

Bedrock erosion by sediment-bearing subglacial water remains little-studied, however the process is thought to contribute to bedrock erosion rates in glaciated landscapes and is implicated in the excavation of tunnel valleys and the incision of inner gorges. We adapt physics-based models of fluvial abrasion to the subglacial environment, assembling the first model designed to quantify bedrock erosion caused by transient subglacial water flow. The subglacial drainage model consists of a one-dimensional network of cavities dynamically coupled to one or several Röthlisberger channels (R-channels). The bedrock erosion model is based on the tools and cover effect, whereby particles entrained by the flow impact exposed bedrock. We explore the dependency of glacial meltwater erosion on the structure and magnitude of water input to the system, the ice geometry and the sediment supply. We find that erosion is not a function of water discharge alone, but also depends on channel size, water pressure and on sediment supply, as in fluvial systems. Modelled glacial meltwater erosion rates are one to two orders of magnitude lower than the expected rates of total glacial erosion required to produce the sediment supply rates we impose, suggesting that glacial meltwater erosion is negligible at the basin scale. Nevertheless, due to the extreme localization of glacial meltwater erosion (at the base of R-channels), this process can carve bedrock (Nye) channels. In fact, our simulations suggest that the incision of bedrock channels several centimetres deep and a few meters wide can occur in a single year. Modelled incision rates indicate that subglacial water flow can gradually carve a tunnel valley and enhance the relief or even initiate the carving of an inner gorge.

Simulating Blade-Strike on Fish passing through Marine Hydrokinetic Turbines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Romero Gomez, Pedro DJ; Richmond, Marshall C.

2014-06-16

The study reported here evaluated the occurrence, frequency, and intensity of blade strike of fish on an axial-flow marine hydrokinetic turbine by using two modeling approaches: a conventional kinematic formulation and a proposed Lagrangian particle- based scheme. The kinematic model included simplifying assumptions of fish trajectories such as distribution and velocity. The proposed method overcame the need for such simplifications by integrating the following components into a computational fluid dynamics (CFD) model: (i) advanced eddy-resolving flow simulation, (ii) generation of ambient turbulence based on field data, (iii) moving turbine blades in highly transient flows, and (iv) Lagrangian particles to mimicmore » the potential fish pathways. The test conditions to evaluate the blade-strike probability and fish survival rate were: (i) the turbulent environment, (ii) the fish size, and (iii) the approaching flow velocity. The proposed method offered the ability to produce potential fish trajectories and their interaction with the rotating turbine. Depending upon the scenario, the percentile of particles that registered a collision event ranged from 6% to 19% of the released sample size. Next, by using a set of experimental correlations of the exposure-response of living fish colliding with moving blades, the simulated collision data were used as input variables to estimate the survival rate of fish passing through the operating turbine. The resulting survival rates were greater than 96% in all scenarios, which is comparable to or better than known survival rates for conventional hydropower turbines. The figures of strike probability and mortality rate were amplified by the kinematic model. The proposed method offered the advantage of expanding the evaluation of other mechanisms of stress and injury on fish derived from hydrokinetic turbines and related devices.« less

Overland flow, sediment output and nutrient loss from certain forested sites in the central Himalaya, India

NASA Astrophysics Data System (ADS)

Pathak, P. C.; Pandey, A. N.; Singh, J. S.

1984-03-01

Overland flow, sediment output and input and output of precipitation nutrients were evaluated on six forested sites in the central Himalaya during the 1981 and 1982 monsoon seasons. Overland flow was significantly different across the forests and the months of the rainy season. It was positively related with rainfall quantity and intensity, and was negatively related with tree canopy cover and with ground vegetation cover. Average overland flow was only 0.66% of the total incident rainfall, indicating that these sites are subsurface-flow systems. Sediment output was positively related to overland flow. Rainfall added a significant amount of nutrients to the forests. This extra-system input was greater than loss through overland flow + sediment output. The loss of nutrients from the forested sites was in the order: Mg > C > Ca > K = N = P.

The relative effectiveness of empirical and physical models for simulating the dense undercurrent of pyroclastic flows under different emplacement conditions

USGS Publications Warehouse

Ogburn, Sarah E.; Calder, Eliza S

2017-01-01

High concentration pyroclastic density currents (PDCs) are hot avalanches of volcanic rock and gas and are among the most destructive volcanic hazards due to their speed and mobility. Mitigating the risk associated with these flows depends upon accurate forecasting of possible impacted areas, often using empirical or physical models. TITAN2D, VolcFlow, LAHARZ, and ΔH/L or energy cone models each employ different rheologies or empirical relationships and therefore differ in appropriateness of application for different types of mass flows and topographic environments. This work seeks to test different statistically- and physically-based models against a range of PDCs of different volumes, emplaced under different conditions, over different topography in order to test the relative effectiveness, operational aspects, and ultimately, the utility of each model for use in hazard assessments. The purpose of this work is not to rank models, but rather to understand the extent to which the different modeling approaches can replicate reality in certain conditions, and to explore the dynamics of PDCs themselves. In this work, these models are used to recreate the inundation areas of the dense-basal undercurrent of all 13 mapped, land-confined, Soufrière Hills Volcano dome-collapse PDCs emplaced from 1996 to 2010 to test the relative effectiveness of different computational models. Best-fit model results and their input parameters are compared with results using observation- and deposit-derived input parameters. Additional comparison is made between best-fit model results and those using empirically-derived input parameters from the FlowDat global database, which represent “forward” modeling simulations as would be completed for hazard assessment purposes. Results indicate that TITAN2D is able to reproduce inundated areas well using flux sources, although velocities are often unrealistically high. VolcFlow is also able to replicate flow runout well, but does not capture the lateral spreading in distal regions of larger-volume flows. Both models are better at reproducing the inundated area of single-pulse, valley-confined, smaller-volume flows than sustained, highly unsteady, larger-volume flows, which are often partially unchannelized. The simple rheological models of TITAN2D and VolcFlow are not able to recreate all features of these more complex flows. LAHARZ is fast to run and can give a rough approximation of inundation, but may not be appropriate for all PDCs and the designation of starting locations is difficult. The ΔH/L cone model is also very quick to run and gives reasonable approximations of runout distance, but does not inherently model flow channelization or directionality and thus unrealistically covers all interfluves. Empirically-based models like LAHARZ and ΔH/L cones can be quick, first-approximations of flow runout, provided a database of similar flows, e.g., FlowDat, is available to properly calculate coefficients or ΔH/L. For hazard assessment purposes, geophysical models like TITAN2D and VolcFlow can be useful for producing both scenario-based or probabilistic hazard maps, but must be run many times with varying input parameters. LAHARZ and ΔH/L cones can be used to produce simple modeling-based hazard maps when run with a variety of input volumes, but do not explicitly consider the probability of occurrence of different volumes. For forward modeling purposes, the ability to derive potential input parameters from global or local databases is crucial, though important input parameters for VolcFlow cannot be empirically estimated. Not only does this work provide a useful comparison of the operational aspects and behavior of various models for hazard assessment, but it also enriches conceptual understanding of the dynamics of the PDCs themselves.

Methods to quantify seepage beneath Levee 30, Miami-Dade County, Florida

USGS Publications Warehouse

Sonenshein, R.S.

2001-01-01

A two-dimensional, cross-sectional, finite-difference, ground-water flow model and a simple application of Darcy?s law were used to quantify ground-water flow (from a wetlands) beneath Levee 30 in Miami-Dade County, Florida. Geologic and geophysical data, vertical seepage data from the wetlands, canal discharge data, ground-water-level data, and surface-water-stage data collected during 1995 and 1996 were used as boundary conditions and calibration data for the ground-water flow model and as input for the analytical model. Vertical seepage data indicated that water from the wetlands infiltrated the subsurface, near Levee 30, at rates ranging from 0.033 to 0.266 foot per day when the gates at the control structures along Levee 30 canal were closed. During the same period, stage differences between the wetlands (Water Conservation Area 3B) and Levee 30 canal ranged from 0.11 to 1.27 feet. A layer of low-permeability limestone, located 7 to 10 feet below land surface, restricts vertical flow between the surface water in the wetlands and the ground water. Based on measured water-level data, ground-water flow appears to be generally horizontal, except in the direct vicinity of the canal. The increase in discharge rate along a 2-mile reach of the Levee 30 canal ranged from 9 to 30 cubic feet per second per mile and can be attributed primarily to ground-water inflow. Flow rates in Levee 30 canal were greatest when the gates at the control structures were open. The ground-water flow model data were compared with the measured ground-water heads and vertical seepage from the wetlands. Estimating the horizontal ground-water flow rate beneath Levee 30 was difficult owing to the uncertainty in the horizontal hydraulic conductivity of the main flow zone of the Biscayne aquifer. Measurements of ground-water flows into Levee 30 canal, a substantial component of the water budget, were also uncertain, which lessened the ability to validate the model results. Because of vertical flows near Levee 30 canal and a very low hydraulic gradient east of the canal, a simplified Darcian approach simulated with the ground-water flow model does not accurately estimate the horizontal ground-water flow rate. Horizontal ground-water flow rates simulated with the ground-water flow model (for a 60-foot-deep by 1-foot-wide section of the Biscayne aquifer) ranged from 150 to 450 cubic feet per day west of Levee 30 and from 15 to 170 cubic feet per day east of Levee 30 canal. Vertical seepage from the wetlands, within 500 feet of Levee 30, generally accounted for 10 to 15 percent of the total horizontal flow beneath the levee. Simulated horizontal ground-water flow was highest during the wet season and when the gates at the control structures were open.

Internal cycle modeling and environmental assessment of multiple cycle consumer products

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsiliyannis, C.A., E-mail: anion@otenet.gr

2012-01-15

Highlights: Black-Right-Pointing-Pointer Dynamic flow models are presented for remanufactured, reused or recycled products. Black-Right-Pointing-Pointer Early loss and stochastic return are included for fast and slow cycling products. Black-Right-Pointing-Pointer The reuse-to-input flow ratio (Internal Cycle Factor, ICF) is determined. Black-Right-Pointing-Pointer The cycle rate, which is increasing with the ICF, monitors eco-performance. Black-Right-Pointing-Pointer Early internal cycle losses diminish the ICF, the cycle rate and performance. - Abstract: Dynamic annual flow models incorporating consumer discard and usage loss and featuring deterministic and stochastic end-of-cycle (EOC) return by the consumer are developed for reused or remanufactured products (multiple cycle products, MCPs), including fast andmore » slow cycling, short and long-lived products. It is shown that internal flows (reuse and overall consumption) increase proportionally to the dimensionless internal cycle factor (ICF) which is related to environmental impact reduction factors. The combined reuse/recycle (or cycle) rate is shown capable for shortcut, albeit effective, monitoring of environmental performance in terms of waste production, virgin material extraction and manufacturing impacts of all MCPs, a task, which physical variables (lifetime, cycling frequency, mean or total number of return trips) and conventional rates, via which environmental policy has been officially implemented (e.g. recycling rate) cannot accomplish. The cycle rate is shown to be an increasing (hyperbolic) function of ICF. The impact of the stochastic EOC return characteristics on total reuse and consumption flows, as well as on eco-performance, is assessed: symmetric EOC return has a small, positive effect on performance compared to deterministic, while early shifted EOC return is more beneficial. In order to be efficient, environmental policy should set higher minimum reuse targets for higher trippage MCPs. The results may serve for monitoring, flow accounting and comparative eco-assessment of MCPs. They may be useful in identifying reachable and efficient reuse/recycle targets for consumer products and in planning return via appropriate labelling and digital coding for enhancing environmental performance, while satisfying consumer demand.« less

Experimental Investigation on Heat Transfer Characteristics of Different Metallic Fin Arrays

NASA Astrophysics Data System (ADS)

Sangewar, Ravi Kumar

2018-04-01

The reliability of electronic equipment depends on the reliability of the system. For small applications natural convection cooling is sufficient, but for the electronic equipment having number of heat generating components, forced convection cooling is essential. In number of cases, pin fin arrangement is preferred for augmentation of heat transfer. Here, the performance of pin fin array of copper and aluminum material with in-line, as well as staggered arrangement over a flat plate is studied. Constant heat input was given to the inline, staggered arrangement of copper as well as aluminium pin fin arrays. In the present experimental study, heat input and airflow rates are the variables. It was found that the heat transfer coefficient for staggered array is 15% more than that of the in-line array, at the same time pressure drop across the staggered array is more by 10% than the in-line array. The pressure drop was observed to be increasing with increase in flow rate as expected. Endeavor of the present work is to find the optimum spacing between the fins in an array for maximum heat transfer rate, by investigating the heat transfer characteristics.

Including local rainfall dynamics and uncertain boundary conditions into a 2-D regional-local flood modelling cascade

NASA Astrophysics Data System (ADS)

Bermúdez, María; Neal, Jeffrey C.; Bates, Paul D.; Coxon, Gemma; Freer, Jim E.; Cea, Luis; Puertas, Jerónimo

2016-04-01

Flood inundation models require appropriate boundary conditions to be specified at the limits of the domain, which commonly consist of upstream flow rate and downstream water level. These data are usually acquired from gauging stations on the river network where measured water levels are converted to discharge via a rating curve. Derived streamflow estimates are therefore subject to uncertainties in this rating curve, including extrapolating beyond the maximum observed ratings magnitude. In addition, the limited number of gauges in reach-scale studies often requires flow to be routed from the nearest upstream gauge to the boundary of the model domain. This introduces additional uncertainty, derived not only from the flow routing method used, but also from the additional lateral rainfall-runoff contributions downstream of the gauging point. Although generally assumed to have a minor impact on discharge in fluvial flood modeling, this local hydrological input may become important in a sparse gauge network or in events with significant local rainfall. In this study, a method to incorporate rating curve uncertainty and the local rainfall-runoff dynamics into the predictions of a reach-scale flood inundation model is proposed. Discharge uncertainty bounds are generated by applying a non-parametric local weighted regression approach to stage-discharge measurements for two gauging stations, while measured rainfall downstream from these locations is cascaded into a hydrological model to quantify additional inflows along the main channel. A regional simplified-physics hydraulic model is then applied to combine these inputs and generate an ensemble of discharge and water elevation time series at the boundaries of a local-scale high complexity hydraulic model. Finally, the effect of these rainfall dynamics and uncertain boundary conditions are evaluated on the local-scale model. Improvements in model performance when incorporating these processes are quantified using observed flood extent data and measured water levels from a 2007 summer flood event on the river Severn. The area of interest is a 7 km reach in which the river passes through the city of Worcester, a low water slope, subcritical reach in which backwater effects are significant. For this domain, the catchment area between flow gauging stations extends over 540 km2. Four hydrological models from the FUSE framework (Framework for Understanding Structural Errors) were set up to simulate the rainfall-runoff process over this area. At this regional scale, a 2-dimensional hydraulic model that solves the local inertial approximation of the shallow water equations was applied to route the flow, whereas the full form of these equations was solved at the local scale to predict the urban flow field. This nested approach hence allows an examination of water fluxes from the catchment to the building scale, while requiring short setup and computational times. An accurate prediction of the magnitude and timing of the flood peak was obtained with the proposed method, in spite of the unusual structure of the rain episode and the complexity of the River Severn system. The findings highlight the importance of estimating boundary condition uncertainty and local rainfall contribution for accurate prediction of river flows and inundation.

On Riemann solvers and kinetic relations for isothermal two-phase flows with surface tension

NASA Astrophysics Data System (ADS)

Rohde, Christian; Zeiler, Christoph

2018-06-01

We consider a sharp interface approach for the inviscid isothermal dynamics of compressible two-phase flow that accounts for phase transition and surface tension effects. Kinetic relations are frequently used to fix the mass exchange and entropy dissipation rate across the interface. The complete unidirectional dynamics can then be understood by solving generalized two-phase Riemann problems. We present new well-posedness theorems for the Riemann problem and corresponding computable Riemann solvers that cover quite general equations of state, metastable input data and curvature effects. The new Riemann solver is used to validate different kinetic relations on physically relevant problems including a comparison with experimental data. Riemann solvers are building blocks for many numerical schemes that are used to track interfaces in two-phase flow. It is shown that the new Riemann solver enables reliable and efficient computations for physical situations that could not be treated before.

Viscoplastic sculpting in stable triple layer heavy oil transport flow

NASA Astrophysics Data System (ADS)

Sarmadi, Parisa; Hormozi, Sarah; A. Frigaard, Ian

2017-11-01

In we introduced a novel methodology for efficient transport of heavy oil via a triple layer core-annular flow. Pumping pressures are significantly reduced by concentrating high shear rates to a lubricating layer, while ideas from Visco-Plastic Lubrication are used to eliminate interfacial instabilities. We purposefully position a shaped unyielded skin of a viscoplastic fluid between the transported oil and the lubricating fluid layer to balance the density difference between the fluids. Here we address the sculpting of the shaped skin within a concentric inflow manifold. We use the quasi-steady model to provide inputs to an axisymmetric triple layer computation, showing the development of the streamwise skin profile and establishment of the flow. For this, we use a finite element discretization with the augmented-Lagrangian method to represent the yield surface behaviour accurately and a PLIC method to track the interface motion.

Mathematical model of an indirect action fuel flow controller for aircraft jet engines

NASA Astrophysics Data System (ADS)

Tudosie, Alexandru-Nicolae

2017-06-01

The paper deals with a fuel mass flow rate controller with indirect action for aircraft jet engines. The author has identified fuel controller's main parts and its operation mode, then, based on these observations, one has determined motion equations of each main part, which have built system's non-linear mathematical model. In order to realize a better study this model was linearised (using the finite differences method) and then adimensionalized. Based on this new form of the mathematical model, after applying Laplace transformation, the embedded system (controller+engine) was described by the block diagram with transfer functions. Some Simulink-Matlab simulations were performed, concerning system's time behavior for step input, which lead to some useful conclusions and extension possibilities.

Energy in the environment and the second law of thermodynamics

NASA Technical Reports Server (NTRS)

Mueller, R. F.

1972-01-01

The relationship between the consumption of energy by technological cultures and the second law of thermodynamics is discussed. The analysis is based on a description of the operation of a mechanical device which consumes energy. It is concluded that the flow of energy in manifold spontaneous conditions, which play a vital role in the operation of any technological process, remove most of the energy flow path from the control of the operator. It is stated that the increased efficiency of a process can benefit the environment only as much as this efficiency enables the total energy input to be reduced for a given level of production and increasing efficiency cannot meet the problems of an increased rate of energy utilization.

Potential flow theory and operation guide for the panel code PMARC

NASA Technical Reports Server (NTRS)

Ashby, Dale L.; Dudley, Michael R.; Iguchi, Steve K.; Browne, Lindsey; Katz, Joseph

1991-01-01

The theoretical basis for PMARC, a low-order potential-flow panel code for modeling complex three-dimensional geometries, is outlined. Several of the advanced features currently included in the code, such as internal flow modeling, a simple jet model, and a time-stepping wake model, are discussed in some detail. The code is written using adjustable size arrays so that it can be easily redimensioned for the size problem being solved and the computer hardware being used. An overview of the program input is presented, with a detailed description of the input available in the appendices. Finally, PMARC results for a generic wing/body configuration are compared with experimental data to demonstrate the accuracy of the code. The input file for this test case is given in the appendices.

Evaluation of infiltration for the determination of palms water needs

NASA Astrophysics Data System (ADS)

Benlarbi, Dalila; Boutaoutaou, Djamel; Saggaï, Sofiane

2018-05-01

In arid climate conditions, irrigation water requirements increase, but available water resources are limited. And therefore the Saharan regions, large consumers of water can be seriously threatened if they do not make the necessary to become as parsimonious as allow the irrigation techniques whose technological aspect on their improvement has been privileged until now but all the problems are not solved. The objective of this work is to know the process of infiltration of water in the soil, i.e.: to try to determine exactly its value with obtaining the best combination (flow of entry, board length and irrigation time) in order to have a more or less uniform distribution in the soil and especially by avoiding significant water losses that would cause rise in the water table. The infiltration will allow us to calculate at any point the dose of water received that we will compare with the needs of the date palm. For this purpose; we varied the input flow for a constant board length. Then we varied the board length for a constant input rate. In both cases we varied the irrigation time according to the water requirements of the date palm. The flow remains of course constant during the entire feeding period. This study is primarily experimental and aims to meet practical applications but not immediately because it is necessary to continue the experiments with several other combinations to achieve practical results.

Multi-timescale sediment responses across a human impacted river-estuary system

NASA Astrophysics Data System (ADS)

Chen, Yining; Chen, Nengwang; Li, Yan; Hong, Huasheng

2018-05-01

Hydrological processes regulating sediment transport from land to sea have been widely studied. However, anthropogenic factors controlling the river flow-sediment regime and subsequent response of the estuary are still poorly understood. Here we conducted a multi-timescale analysis on flow and sediment discharges during the period 1967-2014 for the two tributaries of the Jiulong River in Southeast China. The long-term flow-sediment relationship remained linear in the North River throughout the period, while the linearity showed a remarkable change after 1995 in the West River, largely due to construction of dams and reservoirs in the upland watershed. Over short timescales, rainstorm events caused the changes of suspended sediment concentration (SSC) in the rivers. Regression analysis using synchronous SSC data in a wet season (2009) revealed a delayed response (average 5 days) of the estuary to river input, and a box-model analysis established a quantitative relationship to further describe the response of the estuary to the river sediment input over multiple timescales. The short-term response is determined by both the vertical SSC-salinity changes and the sediment trapping rate in the estuary. However, over the long term, the reduction of riverine sediment yield increased marine sediments trapped into the estuary. The results of this study indicate that human activities (e.g., dams) have substantially altered sediment delivery patterns and river-estuary interactions at multiple timescales.

WE-FG-206-06: Dual-Input Tracer Kinetic Modeling and Its Analog Implementation for Dynamic Contrast-Enhanced (DCE-) MRI of Malignant Mesothelioma (MPM)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, S; Rimner, A; Hayes, S

Purpose: To use dual-input tracer kinetic modeling of the lung for mapping spatial heterogeneity of various kinetic parameters in malignant MPM Methods: Six MPM patients received DCE-MRI as part of their radiation therapy simulation scan. 5 patients had the epitheloid subtype of MPM, while one was biphasic. A 3D fast-field echo sequence with TR/TE/Flip angle of 3.62ms/1.69ms/15° was used for DCE-MRI acquisition. The scan was collected for 5 minutes with a temporal resolution of 5-9 seconds depending on the spatial extent of the tumor. A principal component analysis-based groupwise deformable registration was used to co-register all the DCE-MRI series formore » motion compensation. All the images were analyzed using five different dual-input tracer kinetic models implemented in analog continuous-time formalism: the Tofts-Kety (TK), extended TK (ETK), two compartment exchange (2CX), adiabatic approximation to the tissue homogeneity (AATH), and distributed parameter (DP) models. The following parameters were computed for each model: total blood flow (BF), pulmonary flow fraction (γ), pulmonary blood flow (BF-pa), systemic blood flow (BF-a), blood volume (BV), mean transit time (MTT), permeability-surface area product (PS), fractional interstitial volume (vi), extraction fraction (E), volume transfer constant (Ktrans) and efflux rate constant (kep). Results: Although the majority of patients had epitheloid histologies, kinetic parameter values varied across different models. One patient showed a higher total BF value in all models among the epitheloid histologies, although the γ value was varying among these different models. In one tumor with a large area of necrosis, the TK and ETK models showed higher E, Ktrans, and kep values and lower interstitial volume as compared to AATH and DP and 2CX models. Kinetic parameters such as BF-pa, BF-a, PS, Ktrans values were higher in surviving group compared to non-surviving group across most models. Conclusion: Dual-input tracer kinetic modeling is feasible in determining micro-vascular characteristics of MPM. This project was supported from Cycle for Survival and MSK Imaging and radiation science (IMRAS) grants.« less

The initial cooling of pahoehoe flow lobes

USGS Publications Warehouse

Keszthelyi, L.; Denlinger, R.

1996-01-01

In this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows. The accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation. This model is constructed from the physical phenomena observed to control the initial cooling of pahoehoe flows and is not an empirical fit to field data. We find that the only significant processes are (a) heat loss by thermal radiation, (b) heat loss by atmospheric convection, (c) heat transport within the flow by conduction with temperature and porosity-dependent thermal properties, and (d) the release of latent heat during crystallization. The numerical model is better able to reproduce field measurements made in Hawai'i between 1989 and 1993 than other published thermal models. By adjusting one parameter at a time, the effect of each of the input parameters on the cooling rate was determined. We show that: (a) the surfaces of porous flows cool more quickly than the surfaces of dense flows, (b) the surface cooling is very sensitive to the efficiency of atmospheric convective cooling, and (c) changes in the glass forming tendency of the lava may have observable petrographic and thermal signatures. These model results provide a quantitative explanation for the recently observed relationship between the surface cooling rate of pahoehoe lobes and the porosity of those lobes (Jones 1992, 1993). The predicted sensitivity of cooling to atmospheric convection suggests a simple field experiment for verification, and the model provides a tool to begin studies of the dynamic crystallization of real lavas. Future versions of the model can also be made applicable to extraterrestrial, submarine, silicic, and pyroclastic flows.

Experimental investigation of conical bubble structure and acoustic flow structure in ultrasonic field.

PubMed

Ma, Xiaojian; Huang, Biao; Wang, Guoyu; Zhang, Mindi

2017-01-01

The objective of this paper is to investigate the transient conical bubble structure (CBS) and acoustic flow structure in ultrasonic field. In the experiment, the high-speed video and particle image velocimetry (PIV) techniques are used to measure the acoustic cavitation patterns, as well as the flow velocity and vorticity fields. Results are presented for a high power ultrasound with a frequency of 18kHz, and the range of the input power is from 50W to 250W. The results of the experiment show the input power significantly affects the structures of CBS, with the increase of input power, the cavity region of CBS and the velocity of bubbles increase evidently. For the transient motion of bubbles on radiating surface, two different types could be classified, namely the formation, aggregation and coalescence of cavitation bubbles, and the aggregation, shrink, expansion and collapse of bubble cluster. Furthermore, the thickness of turbulent boundary layer near the sonotrode region is found to be much thicker, and the turbulent intensities are much higher for relatively higher input power. The vorticity distribution is prominently affected by the spatial position and input power. Copyright © 2016 Elsevier B.V. All rights reserved.

Breathing simulator of workers for respirator performance test

PubMed Central

YUASA, Hisashi; KUMITA, Mikio; HONDA, Takeshi; KIMURA, Kazushi; NOZAKI, Kosuke; EMI, Hitoshi; OTANI, Yoshio

2014-01-01

Breathing machines are widely used to evaluate respirator performance but they are capable of generating only limited air flow patterns, such as, sine, triangular and square waves. In order to evaluate the respirator performance in practical use, it is desirable to test the respirator using the actual breathing patterns of wearers. However, it has been a difficult task for a breathing machine to generate such complicated flow patterns, since the human respiratory volume changes depending on the human activities and workload. In this study, we have developed an electromechanical breathing simulator and a respiration sampling device to record and reproduce worker’s respiration. It is capable of generating various flow patterns by inputting breathing pattern signals recorded by a computer, as well as the fixed air flow patterns. The device is equipped with a self-control program to compensate the difference in inhalation and exhalation volume and the measurement errors on the breathing flow rate. The system was successfully applied to record the breathing patterns of workers engaging in welding and reproduced the breathing patterns. PMID:25382381

Global SWOT Data Assimilation of River Hydrodynamic Model; the Twin Simulation Test of CaMa-Flood

NASA Astrophysics Data System (ADS)

Ikeshima, D.; Yamazaki, D.; Kanae, S.

2016-12-01

CaMa-Flood is a global scale model for simulating hydrodynamics in large scale rivers. It can simulate river hydrodynamics such as river discharge, flooded area, water depth and so on by inputting water runoff derived from land surface model. Recently many improvements at parameters or terrestrial data are under process to enhance the reproducibility of true natural phenomena. However, there are still some errors between nature and simulated result due to uncertainties in each model. SWOT (Surface water and Ocean Topography) is a satellite, which is going to be launched in 2021, can measure open water surface elevation. SWOT observed data can be used to calibrate hydrodynamics model at river flow forecasting and is expected to improve model's accuracy. Combining observation data into model to calibrate is called data assimilation. In this research, we developed data-assimilated river flow simulation system in global scale, using CaMa-Flood as river hydrodynamics model and simulated SWOT as observation data. Generally at data assimilation, calibrating "model value" with "observation value" makes "assimilated value". However, the observed data of SWOT satellite will not be available until its launch in 2021. Instead, we simulated the SWOT observed data using CaMa-Flood. Putting "pure input" into CaMa-Flood produce "true water storage". Extracting actual daily swath of SWOT from "true water storage" made simulated observation. For "model value", we made "disturbed water storage" by putting "noise disturbed input" to CaMa-Flood. Since both "model value" and "observation value" are made by same model, we named this twin simulation. At twin simulation, simulated observation of "true water storage" is combined with "disturbed water storage" to make "assimilated value". As the data assimilation method, we used ensemble Kalman filter. If "assimilated value" is closer to "true water storage" than "disturbed water storage", the data assimilation can be marked effective. Also by changing the input disturbance of "disturbed water storage", acceptable rate of uncertainty at the input may be discussed.

Rates of species accumulation and taxonomic diversification during phototrophic biofilm development are controlled by both nutrient supply and current velocity.

PubMed

Larson, Chad A; Passy, Sophia I

2013-03-01

The accumulation of new and taxonomically diverse species is a marked feature of community development, but the role of the environment in this process is not well understood. To address this problem, we subjected periphyton in laboratory streams to low (10-cm · s(-1)), high (30-cm · s(-1)), and variable (9- to 32-cm · s(-1)) current velocity and low- versus high-nutrient inputs. We examined how current velocity and resource supply constrained (i) the rates of species accumulation, a measure of temporal beta-diversity, and (ii) the rates of diversification of higher taxonomic categories, defined here as the rate of higher taxon richness increase with the increase of species richness. Temporal biofilm dynamics were controlled by a strong nutrient-current interaction. Nutrients accelerated the rates of accumulation of new species, when flow velocity was not too stressful. Species were more taxonomically diverse under variable than under low-flow conditions, indicating that flow heterogeneity increased the niche diversity in the high-nutrient treatments. Conversely, the lower diversification rates under high- than under low-nutrient conditions at low velocity are explained with finer resource partitioning among species, belonging to a limited number of related genera. The overall low rates of diversification in high-current treatments suggest that the ability to withstand current stress was conserved within closely related species. Temporal heterogeneity of disturbance has been shown to promote species richness, but here we further demonstrate that it also affects two other components of biodiversity, i.e., temporal beta-diversity and diversification rate. Therefore, management efforts for preserving the inherent temporal heterogeneity of natural ecosystems will have detectable positive effects on biodiversity.

Rates of Species Accumulation and Taxonomic Diversification during Phototrophic Biofilm Development Are Controlled by both Nutrient Supply and Current Velocity

PubMed Central

2013-01-01

The accumulation of new and taxonomically diverse species is a marked feature of community development, but the role of the environment in this process is not well understood. To address this problem, we subjected periphyton in laboratory streams to low (10-cm · s−1), high (30-cm · s−1), and variable (9- to 32-cm · s−1) current velocity and low- versus high-nutrient inputs. We examined how current velocity and resource supply constrained (i) the rates of species accumulation, a measure of temporal beta-diversity, and (ii) the rates of diversification of higher taxonomic categories, defined here as the rate of higher taxon richness increase with the increase of species richness. Temporal biofilm dynamics were controlled by a strong nutrient-current interaction. Nutrients accelerated the rates of accumulation of new species, when flow velocity was not too stressful. Species were more taxonomically diverse under variable than under low-flow conditions, indicating that flow heterogeneity increased the niche diversity in the high-nutrient treatments. Conversely, the lower diversification rates under high- than under low-nutrient conditions at low velocity are explained with finer resource partitioning among species, belonging to a limited number of related genera. The overall low rates of diversification in high-current treatments suggest that the ability to withstand current stress was conserved within closely related species. Temporal heterogeneity of disturbance has been shown to promote species richness, but here we further demonstrate that it also affects two other components of biodiversity, i.e., temporal beta-diversity and diversification rate. Therefore, management efforts for preserving the inherent temporal heterogeneity of natural ecosystems will have detectable positive effects on biodiversity. PMID:23335757

Noise produced by turbulent flow into a rotor: Users manual for noise calculation

NASA Technical Reports Server (NTRS)

Amiet, R. K.; Egolf, C. G.; Simonich, J. C.

1989-01-01

A users manual for a computer program for the calculation of noise produced by turbulent flow into a helicopter rotor is presented. These inputs to the program are obtained from the atmospheric turbulence model and mean flow distortion calculation, described in another volume of this set of reports. Descriptions of the various program modules and subroutines, their function, programming structure, and the required input and output variables are included. This routine is incorporated as one module of NASA's ROTONET helicopter noise prediction program.

How reactive fluids alter fracture walls and affect shale-matrix accessibility

NASA Astrophysics Data System (ADS)

Fitts, J. P.; Deng, H.; Peters, C. A.

2014-12-01

Predictions of mass transfer across fracture boundaries and fluid flow in fracture networks provide fundamental inputs into risk and life cycle assessments of geologic energy technologies including oil and gas extraction, geothermal energy systems and geologic CO2 storage. However, major knowledge gaps exist due to the lack of experimental observations of how reactive fluids alter the pore structures and accessible surface area within fracture boundaries that control the mass transfer of organics, metals and salts, and influence fluid flow within the fracture. To investigate the fracture and rock matrix properties governing fracture boundary alteration, we developed a new flow-through cell that enables time-dependent 2D x-ray imaging of mineral dissolution and/or precipitation at a fracture surface. The parallel plate design provides an idealized fracture geometry to investigate the relationship between flow rate, reaction rate, and mineral spatial heterogeneity and variation. In the flow-cell, a carbonate-rich sample of Eagle Ford shale was reacted with acidified brine. The extent and rate of mineral dissolution were correlated with calcite abundance relative to less soluble silicate minerals. Three-dimensional x-ray tomography of the reacted fracture wall shows how calcite dissolution left behind a porous network of silicate minerals. And while this silicate network essentially preserved the location of the initial fracture wall, the pore network structures within the fracture boundary were dramatically altered, such that the accessible surface area of matrix components increased significantly. In a second set of experiments with a limestone specimen, however, the extent of dissolution and retreat of the fracture wall was not strictly correlated with the occurrence of calcite. Instead, the pattern and extent of dissolution suggested secondary causes such as calcite morphology, the presence of argillaceous minerals and other diagenetic features. Our experiments show that while calcite dissolution is the primary geochemical driver of fracture wall alterations, hydrodynamic properties and matrix accessibility within fracture boundaries evolve based on a complex relationship between mineral spatial heterogeneity and variation, fluid chemistry and flow rate.

Influence of Energy Input on the Flow Past Hypersonic Aircraft X-43

NASA Astrophysics Data System (ADS)

Khankhasaeva, Ya V.; E Borisov, V.; E Lutsky, A.

2017-02-01

This paper deals with a numerical study of the influence of energy sources on the flow past hypersonic aircraft X-43. Flight mode with M = 6 and angle of attack α = 0°, 4° with energy deposition in areas around various parts of HA was considered. It is shown that energy input in front of the bow of the HA leads to a significant weakening of the bow shock wave and an increase in aerodynamic efficiency of the vehicle. The results of studies on the impact of energy input in the scramjet intake are also presented.

Anisotropic effects on constitutive model parameters of aluminum alloys

NASA Astrophysics Data System (ADS)

Brar, Nachhatter S.; Joshi, Vasant S.

2012-03-01

Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. Model constants are determined from tension, compression or torsion stress-strain at low and high strain rates at different temperatures. These model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloy. Johnson- Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulation go well beyond minor parameter tweaking and experimental results show drastically different behavior it becomes important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy quasi-static and high strain rate tensile tests were performed on specimens fabricated in the longitudinal "L", transverse "T", and thickness "TH" directions of 1' thick Al7075 Plate. While flow stress at a strain rate of ~1/s as well as ~1100/s in the thickness and transverse directions are lower than the longitudinal direction. The flow stress in the bar was comparable to flow stress in the longitudinal direction of the plate. Fracture strain data from notched tensile specimens fabricated in the L, T, and Thickness directions of 1' thick plate are used to derive fracture constants.

Dynamic reservoir-condition microtomography of reactive transport in complex carbonates: Effect of initial pore structure and initial brine pH

NASA Astrophysics Data System (ADS)

Menke, H. P.; Bijeljic, B.; Blunt, M. J.

2017-05-01

We study the impact of brine acidity and initial pore structure on the dynamics of fluid/solid reaction at high Péclet numbers and low Damköhler numbers. A laboratory μ-CT scanner was used to image the dissolution of Ketton, Estaillades, and Portland limestones in the presence of CO2-acidified brine at reservoir conditions (10 MPa and 50 °C) at two injected acid strengths for a period of 4 h. Each sample was scanned between 6 and 10 times at ∼4 μm resolution and multiple effluent samples were extracted. The images were used as inputs into flow simulations, and analysed for dynamic changes in porosity, permeability, and reaction rate. Additionally, the effluent samples were used to verify the image-measured porosity changes. We find that initial brine acidity and pore structure determine the type of dissolution. Dissolution is either uniform where the porosity increases evenly both spatially and temporally, or occurs as channelling where the porosity increase is concentrated in preferential flow paths. Ketton, which has a relatively homogeneous pore structure, dissolved uniformly at pH = 3.6 but showed more channelized flow at pH = 3.1. In Estaillades and Portland, increasingly complex carbonates, channelized flow was observed at both acidities with the channel forming faster at lower pH. It was found that the effluent pH, which is higher than that injected, is a reasonably good indicator of effective reaction rate during uniform dissolution, but a poor indicator during channelling. The overall effective reaction rate was up to 18 times lower than the batch reaction rate measured on a flat surface at the effluent pH, with the lowest reaction rates in the samples with the most channelized flow, confirming that transport limitations are the dominant mechanism in determining reaction dynamics at the fluid/solid boundary.

Emissions-critical charge cooling using an organic rankine cycle

DOEpatents

Ernst, Timothy C.; Nelson, Christopher R.

2014-07-15

The disclosure provides a system including a Rankine power cycle cooling subsystem providing emissions-critical charge cooling of an input charge flow. The system includes a boiler fluidly coupled to the input charge flow, an energy conversion device fluidly coupled to the boiler, a condenser fluidly coupled to the energy conversion device, a pump fluidly coupled to the condenser and the boiler, an adjuster that adjusts at least one parameter of the Rankine power cycle subsystem to change a temperature of the input charge exiting the boiler, and a sensor adapted to sense a temperature characteristic of the vaporized input charge. The system includes a controller that can determine a target temperature of the input charge sufficient to meet or exceed predetermined target emissions and cause the adjuster to adjust at least one parameter of the Rankine power cycle to achieve the predetermined target emissions.

User Guide and Documentation for Five MODFLOW Ground-Water Modeling Utility Programs

USGS Publications Warehouse

Banta, Edward R.; Paschke, Suzanne S.; Litke, David W.

2008-01-01

This report documents five utility programs designed for use in conjunction with ground-water flow models developed with the U.S. Geological Survey's MODFLOW ground-water modeling program. One program extracts calculated flow values from one model for use as input to another model. The other four programs extract model input or output arrays from one model and make them available in a form that can be used to generate an ArcGIS raster data set. The resulting raster data sets may be useful for visual display of the data or for further geographic data processing. The utility program GRID2GRIDFLOW reads a MODFLOW binary output file of cell-by-cell flow terms for one (source) model grid and converts the flow values to input flow values for a different (target) model grid. The spatial and temporal discretization of the two models may differ. The four other utilities extract selected 2-dimensional data arrays in MODFLOW input and output files and write them to text files that can be imported into an ArcGIS geographic information system raster format. These four utilities require that the model cells be square and aligned with the projected coordinate system in which the model grid is defined. The four raster-conversion utilities are * CBC2RASTER, which extracts selected stress-package flow data from a MODFLOW binary output file of cell-by-cell flows; * DIS2RASTER, which extracts cell-elevation data from a MODFLOW Discretization file; * MFBIN2RASTER, which extracts array data from a MODFLOW binary output file of head or drawdown; and * MULT2RASTER, which extracts array data from a MODFLOW Multiplier file.

Development of a compact cryocooler system for high temperature superconductor filter application

NASA Astrophysics Data System (ADS)

Pang, Xiaomin; Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Hu, Jianying; Dai, Wei; Li, Haibing; Luo, Ercang

2016-12-01

Seeking a higher specific power of the pulse tube cryocooler is an important trend in recent studies. High frequency operation (100 Hz and higher), combined with co-axial configuration, serve as a good option to meet this requirement. This paper introduces a high efficiency co-axial pulse tube cryocooler operating at around 100 Hz. The whole system weighs 4.3 kg (not including the radiator) with a nominal input power of 320 W, namely, power density of the system is around 74 W/kg. The envelop dimensions of the cold finger itself is about 84 mm in length and 23 mm in outer diameter. Firstly, numerical model for designing the system and some simulation results are briefly introduced. Distributions of pressure wave, the phase difference between the pressure wave and the volume flow rate and different energy flow are presented for a better understanding of the system. After this, some of the characterizing experimental results are presented. At an optimum working point, the cooling power at 80 K reaches 16 W with an input electric power of 300 W, which leads to an efficiency of 15.5% of Carnot.

Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

NASA Astrophysics Data System (ADS)

Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

2016-12-01

This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

Nitrogen balance of a boreal Scots pine forest

NASA Astrophysics Data System (ADS)

Korhonen, J. F. J.; Pihlatie, M.; Pumpanen, J.; Aaltonen, H.; Hari, P.; Levula, J.; Kieloaho, A.-J.; Nikinmaa, E.; Vesala, T.; Ilvesniemi, H.

2013-02-01

The productivity of boreal forests is considered to be limited by low nitrogen (N) availability. Increased atmospheric N deposition has altered the functioning and N cycling of these N-sensitive ecosystems by increasing the availability of reactive nitrogen. The most important components of N pools and fluxes were measured in a boreal Scots pine stand in Hyytiälä, Southern Finland. The measurements at the site allowed direct estimations of nutrient pools in the soil and biomass, inputs from the atmosphere and outputs as drainage flow and gaseous losses from two micro-catchments. N was accumulating in the system, mainly in woody biomass, at a rate of 7 kg N ha-1 yr-1. Nitrogen input as atmospheric deposition was 7.4 kg N ha-1 yr-1. Dry deposition and organic N in wet deposition contributed over half of the inputs in deposition. Total outputs were 0.4 kg N ha-1 yr-1, the most important outputs being N2O emission to the atmosphere and organic N flux in drainage flow. Nitrogen uptake and retranslocation were equally important sources of N for plant growth. Most of the assimilated N originated from decomposition of organic matter, and the fraction of N that could originate directly from deposition was about 30%. In conclusion, atmospheric N deposition fertilizes the site considerably, but there are no signs of N saturation. Further research is needed to estimate soil N2 fluxes (emission and fixation), which may amount up to several kg N ha-1 yr-1.

Using stable isotopes of dissolved oxygen for the determination of gas exchange in the Grand River, Ontario, Canada.

PubMed

Jamieson, Terra S; Schiff, Sherry L; Taylor, William D

2013-02-01

Gas exchange can be a key component of the dissolved oxygen (DO) mass balance in aquatic ecosystems. Quantification of gas transfer rates is essential for the estimation of DO production and consumption rates, and determination of assimilation capacities of systems receiving organic inputs. Currently, the accurate determination of gas transfer rate is a topic of debate in DO modeling, and there are a wide variety of approaches that have been proposed in the literature. The current study investigates the use of repeated measures of stable isotopes of O₂ and DO and a dynamic dual mass-balance model to quantify gas transfer coefficients (k) in the Grand River, Ontario, Canada. Measurements were conducted over a longitudinal gradient that reflected watershed changes from agricultural to urban. Values of k in the Grand River ranged from 3.6 to 8.6 day⁻¹, over discharges ranging from 5.6 to 22.4 m³ s⁻¹, with one high-flow event of 73.1 m³ s⁻¹. The k values were relatively constant over the range of discharge conditions studied. The range in discharge observed in this study is generally representative of non-storm and summer low-flow events; a greater range in k might be observed under a wider range of hydrologic conditions. Overall, k values obtained with the dual model for the Grand River were found to be lower than predicted by the traditional approaches evaluated, highlighting the importance of determining site-specific values of k. The dual mass balance approach provides a more constrained estimate of k than using DO only, and is applicable to large rivers where other approaches would be difficult to use. The addition of an isotopic mass balance provides for a corroboration of the input parameter estimates between the two balances. Constraining the range of potential input values allows for a direct estimate of k in large, productive systems where other k-estimation approaches may be uncertain or logistically infeasible. Copyright © 2012 Elsevier Ltd. All rights reserved.

Geophysical characteristics of the hydrothermal systems of Kilauea volcano, Hawaii

USGS Publications Warehouse

Kauahikaua, J.

1993-01-01

Clues to the overall structure of Kilauea volcano can be obtained from spatial studies of gravity, magnetic, and seismic velocity variations. The rift zones and summit are underlain by dense, magnetic, high P-wave-velocity rocks at depths of about 2 km less. The gravity and seismic velocity studies indicate that the rift structures are broad, extending farther to the north than to the south of the surface features. The magnetic data give more definition to the rift structures by allowing separation into a narrow, highly-magnetized, shallow zone and broad, flanking, magnetic lows. The patterns of gravity, magnetic variations, and seismicity document the southward migration of the upper cast rift zone. Regional, hydrologic features of Kilauea can be determined from resistivity and self-potential studies. High-level groundwater exists beneath Kilauea summit to elevations of +800 m within a triangular area bounded by the west edge of the upper southwest rift zone, the east edge of the upper east rift zone, and the Koa'c fault system. High-level groundwater is present within the east rift zone beyond the triangular summit area. Self-potential mapping shows that areas of local heat produce local fluid circulation in the unconfined aquifer (water table). The dynamics of Kilauea eruptions are responsible for both the source of heat and the fracture permeability of the hydrothermal system. Shallow seismicity and surface deformation indicate that magma is intruding and that fractures are forming beneath the rift zones and summit area. Magma supply estimates are used to calculate the rate of heat input to Kilauea's hydrothermal systems. Heat flows of 370-820 mW/m2 are calculated from deep wells within the lower east rift zone. The estimated heat input rate for Kilauea of 9 gigawatts (GW) is at least 25 times higher than the conductive heat loss as estimated from the heat flow in wells extrapolated over the area of the summit caldera and rift zones. Heat must be dissipated by another mechanism, or the heat input rate estimates are much too high. ?? 1993.

Probabilistically modeling lava flows with MOLASSES

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Connor, L.; Connor, C.; Gallant, E.

2017-12-01

Modeling lava flows through Cellular Automata methods enables a computationally inexpensive means to quickly forecast lava flow paths and ultimate areal extents. We have developed a lava flow simulator, MOLASSES, that forecasts lava flow inundation over an elevation model from a point source eruption. This modular code can be implemented in a deterministic fashion with given user inputs that will produce a single lava flow simulation. MOLASSES can also be implemented in a probabilistic fashion where given user inputs define parameter distributions that are randomly sampled to create many lava flow simulations. This probabilistic approach enables uncertainty in input data to be expressed in the model results and MOLASSES outputs a probability map of inundation instead of a determined lava flow extent. Since the code is comparatively fast, we use it probabilistically to investigate where potential vents are located that may impact specific sites and areas, as well as the unconditional probability of lava flow inundation of sites or areas from any vent. We have validated the MOLASSES code to community-defined benchmark tests and to the real world lava flows at Tolbachik (2012-2013) and Pico do Fogo (2014-2015). To determine the efficacy of the MOLASSES simulator at accurately and precisely mimicking the inundation area of real flows, we report goodness of fit using both model sensitivity and the Positive Predictive Value, the latter of which is a Bayesian posterior statistic. Model sensitivity is often used in evaluating lava flow simulators, as it describes how much of the lava flow was successfully modeled by the simulation. We argue that the positive predictive value is equally important in determining how good a simulator is, as it describes the percentage of the simulation space that was actually inundated by lava.

40 CFR 75.83 - Calculation of Hg mass emissions and heat input rate.

Code of Federal Regulations, 2010 CFR

2010-07-01

... heat input rate. 75.83 Section 75.83 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Calculation of Hg mass emissions and heat input rate. The owner or operator shall calculate Hg mass emissions and heat input rate in accordance with the procedures in sections 9.1 through 9.3 of appendix F to...

Standards for the Analysis and Processing of Surface-Water Data and Information Using Electronic Methods

USGS Publications Warehouse

Sauer, Vernon B.

2002-01-01

Surface-water computation methods and procedures are described in this report to provide standards from which a completely automated electronic processing system can be developed. To the greatest extent possible, the traditional U. S. Geological Survey (USGS) methodology and standards for streamflow data collection and analysis have been incorporated into these standards. Although USGS methodology and standards are the basis for this report, the report is applicable to other organizations doing similar work. The proposed electronic processing system allows field measurement data, including data stored on automatic field recording devices and data recorded by the field hydrographer (a person who collects streamflow and other surface-water data) in electronic field notebooks, to be input easily and automatically. A user of the electronic processing system easily can monitor the incoming data and verify and edit the data, if necessary. Input of the computational procedures, rating curves, shift requirements, and other special methods are interactive processes between the user and the electronic processing system, with much of this processing being automatic. Special computation procedures are provided for complex stations such as velocity-index, slope, control structures, and unsteady-flow models, such as the Branch-Network Dynamic Flow Model (BRANCH). Navigation paths are designed to lead the user through the computational steps for each type of gaging station (stage-only, stagedischarge, velocity-index, slope, rate-of-change in stage, reservoir, tide, structure, and hydraulic model stations). The proposed electronic processing system emphasizes the use of interactive graphics to provide good visual tools for unit values editing, rating curve and shift analysis, hydrograph comparisons, data-estimation procedures, data review, and other needs. Documentation, review, finalization, and publication of records are provided for with the electronic processing system, as well as archiving, quality assurance, and quality control.

Evaluation of protein fractionation systems used in formulating rations for dairy cattle.

PubMed

Lanzas, C; Tedeschi, L O; Seo, S; Fox, D G

2007-01-01

Production efficiency decreases when diets are not properly balanced for protein. Sensitivity analyses of the protein fractionation schemes used by the National Research Council Nutrient Requirement of Dairy Cattle (NRC) and the Cornell Net Carbohydrate and Protein System (CNCPS) were conducted to assess the influence of the uncertainty in feed inputs and the assumptions underlying the CNCPS scheme on metabolizable protein and amino acid predictions. Monte Carlo techniques were used. Two lactating dairy cow diets with low and high protein content were developed for the analysis. A feed database provided by a commercial laboratory and published sources were used to obtain the distributions and correlations of the input variables. Spreadsheet versions of the models were used. Both models behaved similarly when variation in protein fractionation was taken into account. The maximal impact of variation on metabolizable protein from rumen-undegradable protein (RUP) was 2.5 (CNCPS) and 3.0 (NRC) kg/d of allowable milk for the low protein diet, and 3.5 (CNCPS) and 3.9 (NRC) kg/d of allowable milk for the high protein diet. The RUP flows were sensitive to ruminal degradation rates of the B protein fraction in NRC and of the B2 protein fraction in the CNCPS for protein supplements, energy concentrates, and forages. Absorbed Met and Lys flows were also sensitive to intestinal digestibility of RUP, and the CNCPS model was sensitive to acid detergent insoluble crude protein and its assumption of complete unavailability. Neither the intestinal digestibility of the RUP nor the protein degradation rates are routinely measured. Approaches need to be developed to account for their variability. Research is needed to provide better methods for measuring pool sizes and ruminal digestion rates for protein fractionation systems.

Experimental and Computational Analysis of Unidirectional Flow Through Stirling Engine Heater Head

NASA Technical Reports Server (NTRS)

Wilson, Scott D.; Dyson, Rodger W.; Tew, Roy C.; Demko, Rikako

2006-01-01

A high efficiency Stirling Radioisotope Generator (SRG) is being developed for possible use in long-duration space science missions. NASA s advanced technology goals for next generation Stirling convertors include increasing the Carnot efficiency and percent of Carnot efficiency. To help achieve these goals, a multi-dimensional Computational Fluid Dynamics (CFD) code is being developed to numerically model unsteady fluid flow and heat transfer phenomena of the oscillating working gas inside Stirling convertors. In the absence of transient pressure drop data for the zero mean oscillating multi-dimensional flows present in the Technology Demonstration Convertors on test at NASA Glenn Research Center, unidirectional flow pressure drop test data is used to compare against 2D and 3D computational solutions. This study focuses on tracking pressure drop and mass flow rate data for unidirectional flow though a Stirling heater head using a commercial CFD code (CFD-ACE). The commercial CFD code uses a porous-media model which is dependent on permeability and the inertial coefficient present in the linear and nonlinear terms of the Darcy-Forchheimer equation. Permeability and inertial coefficient were calculated from unidirectional flow test data. CFD simulations of the unidirectional flow test were validated using the porous-media model input parameters which increased simulation accuracy by 14 percent on average.

Experimental Investigation and Optimization of TIG Welding Parameters on Aluminum 6061 Alloy Using Firefly Algorithm

NASA Astrophysics Data System (ADS)

Kumar, Rishi; Mevada, N. Ramesh; Rathore, Santosh; Agarwal, Nitin; Rajput, Vinod; Sinh Barad, AjayPal

2017-08-01

To improve Welding quality of aluminum (Al) plate, the TIG Welding system has been prepared, by which Welding current, Shielding gas flow rate and Current polarity can be controlled during Welding process. In the present work, an attempt has been made to study the effect of Welding current, current polarity, and shielding gas flow rate on the tensile strength of the weld joint. Based on the number of parameters and their levels, the Response Surface Methodology technique has been selected as the Design of Experiment. For understanding the influence of input parameters on Ultimate tensile strength of weldment, ANOVA analysis has been carried out. Also to describe and optimize TIG Welding using a new metaheuristic Nature - inspired algorithm which is called as Firefly algorithm which was developed by Dr. Xin-She Yang at Cambridge University in 2007. A general formulation of firefly algorithm is presented together with an analytical, mathematical modeling to optimize the TIG Welding process by a single equivalent objective function.

Predicting playing frequencies for clarinets: A comparison between numerical simulations and simplified analytical formulas.

PubMed

Coyle, Whitney L; Guillemain, Philippe; Kergomard, Jean; Dalmont, Jean-Pierre

2015-11-01

When designing a wind instrument such as a clarinet, it can be useful to be able to predict the playing frequencies. This paper presents an analytical method to deduce these playing frequencies using the input impedance curve. Specifically there are two control parameters that have a significant influence on the playing frequency, the blowing pressure and reed opening. Four effects are known to alter the playing frequency and are examined separately: the flow rate due to the reed motion, the reed dynamics, the inharmonicity of the resonator, and the temperature gradient within the clarinet. The resulting playing frequencies for the first register of a particular professional level clarinet are found using the analytical formulas presented in this paper. The analytical predictions are then compared to numerically simulated results to validate the prediction accuracy. The main conclusion is that in general the playing frequency decreases above the oscillation threshold because of inharmonicity, then increases above the beating reed regime threshold because of the decrease of the flow rate effect.

Reutilisation-extended material flows and circular economy in China.

PubMed

Li, Nan; Zhang, Tianzhu; Liang, Sai

2013-06-01

Circular economy (CE), with its basic principle of Reduce, Reuse, and Recycle, has been determined as the key strategy for the national development plan by the Chinese government. Given the economy-wide material flow analysis (EW-MFA) that leaves the inner flow of resource reutilisation unidentified, the reutilisation-extended EW-MFA is first introduced to evaluate and analyse the material input, solid waste generation, and reutilisation simultaneously. The total amount of comprehensive reutilisation (CR) is divided into three sub-flows, namely, reutilisation, recycle, and reuse. Thus, this model is used to investigate the resource CR in China from 2000 to 2010. China's total amount of CR and its sub-flows, as well as the CR rate, remain to have a general upward trend. By the year 2010, about 60% of the overall solid waste generation had already been reutilised, and more than 20% of the total resource requirement was reutilised resource. Moreover, the growth patterns of the CR sub flows show different characteristics. Interpretations of resource reutilisation-related laws and regulations of CE and the corresponding policy suggestions are proposed based on the results. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modifications of the U.S. Geological Survey modular, finite-difference, ground-water flow model to read and write geographic information system files

USGS Publications Warehouse

Orzol, Leonard L.; McGrath, Timothy S.

1992-01-01

This report documents modifications to the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model, commonly called MODFLOW, so that it can read and write files used by a geographic information system (GIS). The modified model program is called MODFLOWARC. Simulation programs such as MODFLOW generally require large amounts of input data and produce large amounts of output data. Viewing data graphically, generating head contours, and creating or editing model data arrays such as hydraulic conductivity are examples of tasks that currently are performed either by the use of independent software packages or by tedious manual editing, manipulating, and transferring data. Programs such as GIS programs are commonly used to facilitate preparation of the model input data and analyze model output data; however, auxiliary programs are frequently required to translate data between programs. Data translations are required when different programs use different data formats. Thus, the user might use GIS techniques to create model input data, run a translation program to convert input data into a format compatible with the ground-water flow model, run the model, run a translation program to convert the model output into the correct format for GIS, and use GIS to display and analyze this output. MODFLOWARC, avoids the two translation steps and transfers data directly to and from the ground-water-flow model. This report documents the design and use of MODFLOWARC and includes instructions for data input/output of the Basic, Block-centered flow, River, Recharge, Well, Drain, Evapotranspiration, General-head boundary, and Streamflow-routing packages. The modification to MODFLOW and the Streamflow-Routing package was minimized. Flow charts and computer-program code describe the modifications to the original computer codes for each of these packages. Appendix A contains a discussion on the operation of MODFLOWARC using a sample problem.

Anisotropic Effects on Constitutive Model Parameters of Aluminum Alloys

NASA Astrophysics Data System (ADS)

Brar, Nachhatter; Joshi, Vasant

2011-06-01

Simulation of low velocity impact on structures or high velocity penetration in armor materials heavily rely on constitutive material models. The model constants are required input to computer codes (LS-DYNA, DYNA3D or SPH) to accurately simulate fragment impact on structural components made of high strength 7075-T651 aluminum alloys. Johnson-Cook model constants determined for Al7075-T651 alloy bar material failed to simulate correctly the penetration into 1' thick Al-7075-T651plates. When simulations go well beyond minor parameter tweaking and experimental results are drastically different it is important to determine constitutive parameters from the actual material used in impact/penetration experiments. To investigate anisotropic effects on the yield/flow stress of this alloy we performed quasi-static and high strain rate tensile tests on specimens fabricated in the longitudinal, transverse, and thickness directions of 1' thick Al7075-T651 plate. Flow stresses at a strain rate of ~1100/s in the longitudinal and transverse direction are similar around 670MPa and decreases to 620 MPa in the thickness direction. These data are lower than the flow stress of 760 MPa measured in Al7075-T651 bar stock.

Optimization of hydrogen dispersion in thermophilic up-flow reactors for ex situ biogas upgrading.

PubMed

Bassani, Ilaria; Kougias, Panagiotis G; Treu, Laura; Porté, Hugo; Campanaro, Stefano; Angelidaki, Irini

2017-06-01

This study evaluates the efficiency of four novel up-flow reactors for ex situ biogas upgrading converting externally provided CO 2 and H 2 to CH 4 , via hydrogenotrophic methanogenesis. The gases were injected through stainless steel diffusers combined with alumina ceramic sponge or through alumina ceramic membranes. Pore size, input gas loading and gas recirculation flow rate were modulated to optimize gas-liquid mass transfer, and thus methanation efficiency. Results showed that larger pore size diffusion devices achieved the best kinetics and output-gas quality converting all the injected H 2 and CO 2 , up to 3.6L/L REACTOR ·d H 2 loading rate. Specifically, reactors' CH 4 content increased from 23 to 96% and the CH 4 yield reached 0.25L CH4/ L H2 . High throughput 16S rRNA gene sequencing revealed predominance of bacteria belonging to Anaerobaculum genus and to uncultured order MBA08. Additionally, the massive increase of hydrogenotrophic methanogens, such as Methanothermobacter thermautotrophicus, and syntrophic bacteria demonstrates the selection-effect of H 2 on community composition. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Bayesian approach to model structural error and input variability in groundwater modeling

NASA Astrophysics Data System (ADS)

Xu, T.; Valocchi, A. J.; Lin, Y. F. F.; Liang, F.

2015-12-01

Effective water resource management typically relies on numerical models to analyze groundwater flow and solute transport processes. Model structural error (due to simplification and/or misrepresentation of the "true" environmental system) and input forcing variability (which commonly arises since some inputs are uncontrolled or estimated with high uncertainty) are ubiquitous in groundwater models. Calibration that overlooks errors in model structure and input data can lead to biased parameter estimates and compromised predictions. We present a fully Bayesian approach for a complete assessment of uncertainty for spatially distributed groundwater models. The approach explicitly recognizes stochastic input and uses data-driven error models based on nonparametric kernel methods to account for model structural error. We employ exploratory data analysis to assist in specifying informative prior for error models to improve identifiability. The inference is facilitated by an efficient sampling algorithm based on DREAM-ZS and a parameter subspace multiple-try strategy to reduce the required number of forward simulations of the groundwater model. We demonstrate the Bayesian approach through a synthetic case study of surface-ground water interaction under changing pumping conditions. It is found that explicit treatment of errors in model structure and input data (groundwater pumping rate) has substantial impact on the posterior distribution of groundwater model parameters. Using error models reduces predictive bias caused by parameter compensation. In addition, input variability increases parametric and predictive uncertainty. The Bayesian approach allows for a comparison among the contributions from various error sources, which could inform future model improvement and data collection efforts on how to best direct resources towards reducing predictive uncertainty.

The cost of energy from utility-owned solar electric systems. A required revenue methodology for ERDA/EPRI evaluations

NASA Technical Reports Server (NTRS)

1976-01-01

This methodology calculates the electric energy busbar cost from a utility-owned solar electric system. This approach is applicable to both publicly- and privately-owned utilities. Busbar cost represents the minimum price per unit of energy consistent with producing system-resultant revenues equal to the sum of system-resultant costs. This equality is expressed in present value terms, where the discount rate used reflects the rate of return required on invested capital. Major input variables describe the output capabilities and capital cost of the energy system, the cash flows required for system operation amd maintenance, and the financial structure and tax environment of the utility.

Erosion and deposition on a debris-flow fan

NASA Astrophysics Data System (ADS)

Densmore, A. L.; Schuerch, P.; Rosser, N. J.; McArdell, B. W.

2011-12-01

The ability of a debris flow to entrain or deposit sediment controls the downstream evolution of flow volume, and ultimately dictates both the geomorphic impact of the flow and the potential hazard that it represents. Our understanding of the patterns of, and controls on, such flow volume changes remains extremely limited, however, partly due to a poor mechanistic grasp of the interactions between debris flows and their bed and banks. In addition, we lack a good understanding of the cumulative long-term effects of sequences of flows in a single catchment-fan system. Here we begin to address these issues by using repeated terrestrial laser scanning (TLS) to characterize the detailed surface change associated with the passage of multiple debris flows on the Illgraben fan, Switzerland. We calculate surface elevation change along a 300 m study reach, and from this derive the downfan rate of flow volume change, or lag rate; for comparison, we also derive the spatially-averaged lag rate over the entire ~2 km length of the fan. Lag rates are broadly comparable over both length scales, indicating that flow behavior does not vary significantly across the fan for most flows, but importantly we find that flow volume at the fan head is a poor predictor of volume at the fan toe. The sign and magnitude of bed elevation change scale with local flow depth; at flow depths < 2 m, erosion and deposition are approximately equally likely, but erosion becomes increasingly dominant for flow depths > 2 m. On the Illgraben fan, this depth corresponds to a basal shear stress of 3-4 kPa. Because flow depth is in part a function of channel cross-sectional topography, which varies strongly both within and between flows, this result indicates that erosion and deposition are likely to be highly dynamic. The dependence of flow volume change on both the channel topography and the flow history may thus complicate efforts to predict debris-flow inundation areas by simple flow routing. We then apply a 2d numerical model of debris-flow fan evolution to explore the key controls on debris-flow routing and topographic development over sequences of multiple flows. We find that fan topographic roughness plays an important role in both channel development and fan surface stability. We also find that, while first-order fan shape is largely insensitive to the input flow sequence, second-order variables such as the pattern of surface exposure ages and the distribution of channel characteristics hold more promise as robust recorders of past flow conditions. Further work is needed to understand the degree to which the TLS-derived (and Illgraben-specific) relationship between bed elevation change and flow depth can be applied in different settings, and to elucidate the role played by coarse debris in controlling patterns of erosion and deposition.

[System analytical approach of lung function and hemodynamics].

PubMed

Naszlady, Attila; Kiss, Lajos

2009-02-15

The authors critically analyse the traditional views in physiology and complete them with new statements based on computer model simulations of lung function and of hemodynamics. Conclusions are derived for the clinical practice as follows: the four-dimensional function curves are similar in both systems; there is a "waterfall" zone in the pulmonary blood perfusion; the various time constants of pulmonary regions can modify the blood gas values; pulmonary capillary pressure is equal to pulmonary arterial diastole pressure; heart is not a pressure pump, but a flow source; ventricles are loaded by the input impedance of the arterial systems and not by the total vascular (ohmlike) resistance; optimum heart rate in rest depends on the length of the aorta; this law of heart rate, based on the principle of resonance is valid along the mammalian allometric line; tachycardia decreases the input impedance; using positive end expiratory pressure respirators the blood gas of pulmonary artery should be followed; coronary circulation should be assessed in beat per milliliter, the milliliter per minute may be false. These statements are compared to related references.

Coupled hydrological and biogeochemical processes controlling variability of nitrogen species in streamflow during autumn in an upland forest

USGS Publications Warehouse

Sebestyen, Stephen D.; Shanley, James B.; Boyer, Elizabeth W.; Kendall, Carol; Doctor, Daniel H.

2014-01-01

Autumn is a season of dynamic change in forest streams of the northeastern United States due to effects of leaf fall on both hydrology and biogeochemistry. Few studies have explored how interactions of biogeochemical transformations, various nitrogen sources, and catchment flow paths affect stream nitrogen variation during autumn. To provide more information on this critical period, we studied (1) the timing, duration, and magnitude of changes to stream nitrate, dissolved organic nitrogen (DON), and ammonium concentrations; (2) changes in nitrate sources and cycling; and (3) source areas of the landscape that most influence stream nitrogen. We collected samples at higher temporal resolution for a longer duration than typical studies of stream nitrogen during autumn. This sampling scheme encompassed the patterns and extremes that occurred during base flow and stormflow events of autumn. Base flow nitrate concentrations decreased by an order of magnitude from 5.4 to 0.7 µmol L−1 during the week when most leaves fell from deciduous trees. Changes to rates of biogeochemical transformations during autumn base flow explained the low nitrate concentrations; in-stream transformations retained up to 72% of the nitrate that entered a stream reach. A decrease of in-stream nitrification coupled with heterotrophic nitrate cycling were primary factors in the seasonal nitrate decline. The period of low nitrate concentrations ended with a storm event in which stream nitrate concentrations increased by 25-fold. In the ensuing weeks, peak stormflow nitrate concentrations progressively decreased over closely spaced, yet similarly sized events. Most stormflow nitrate originated from nitrification in near-stream areas with occasional, large inputs of unprocessed atmospheric nitrate, which has rarely been reported for nonsnowmelt events. A maximum input of 33% unprocessed atmospheric nitrate to the stream occurred during one event. Large inputs of unprocessed atmospheric nitrate show direct and rapid effects on forest streams that may be widespread, although undocumented, throughout nitrogen-polluted temperate forests. In contrast to a week-long nitrate decline during peak autumn litterfall, base flow DON concentrations increased after leaf fall and remained high for 2 months. Dissolved organic nitrogen was hydrologically flushed to the stream from riparian soils during stormflow. In contrast to distinct seasonal changes in base flow nitrate and DON concentrations, ammonium concentrations were typically at or below the detection limit, similar to the rest of the year. Our findings reveal couplings among catchment flow paths, nutrient sources, and transformations that control seasonal extremes of stream nitrogen in forested landscapes.

Benthic sulfate reduction along the Chesapeake Bay central channel. II. Temporal controls

USGS Publications Warehouse

Marvin-DiPasquale, M. C.; Boynton, W.R.; Capone, D.G.

2003-01-01

Seasonal and interannual controls of benthic sulfate reduction (SR) were examined at 3 sites (upper [UB], mid- [MB] and lower [LB] bay) along the Chesapeake Bay central channel, from early spring through fall, for 6 yr (1989 to 1994). The combined influences of temperature, sulfate, organic loading and bioturbation affected seasonal SR rates differently in the 3 regions. Consistently low SR rates at UB resulted from low overlying-water sulfate concentrations and the dominance of refractory organic terrestrial material. Combined seasonal variation in temperature and sulfate accounted for 50% of the annual variability in 0 to 2 cm depth interval SR rates, while sediment organic content had no significant seasonal influence. In contrast, MB and LB sites had high rates of SR fostered by high levels of overlying water SO42- and organic input dominated by labile phytoplankton detritus. New organic loading (measured as chl a) stimulated 0 to 2 cm SR during spring at both sites. Combined organic quantity (as particulate C and/or N) and temperature accounted for > 75% of the variability in 0 to 2 cm SR at MB during spring and fall. Molecular diffusion supplied 25 to 45% of the SO 42- needed to fuel 0 to 12 cm depth interval SR at MB, with the balance presumably supplied by S-recycling. Interannual differences in summertime SR rates were linked to the extent of freshwater flow during spring, with high-flow years associated with high SR rates at UB and MB, and low rates at LB. The negative trend between benthic SR and river flow at LB may result from the up-estuary transport of senescing organic matter in bottom water, which increases in the lower reach of the estuary with increasing freshwater inflow.

Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis

NASA Astrophysics Data System (ADS)

JøRgensen, Peter R.; Hoffmann, Martin; Kistrup, Jens P.; Bryde, Claus; Bossi, Rossana; Villholth, Karen G.

2002-11-01

This study investigates vertical flow and pesticide transport along fractures in water saturated unoxidized clayey till. From two experimental fields, each 40 m2, 96% and 98%, respectively, of total vertical flow was conducted along fractures in the till, while the remaining 2-4% of flow occurred in the clay matrix at very slow flow rate. An applied dye tracer was observed only along 10-26% of the total fracture length measured on the horizontal surface of the experimental fields. In vertical sections the dyed fracture portions constituted root channels, which penetrated the till vertically along the fractures into the local aquifer at 5 m depth. No dye tracer was observed in the fractures without root channels or in the unfractured clay matrix, suggesting that root growth along the fracture surfaces was the principal agent of fracture aperture enhancement. Using hydraulic fracture aperture values determined from large undisturbed column (LUC) collected from one of the experimental fields, it was estimated that 94% of flow in the fractures was conducted along the fracture root channels, while only 6% of flow was conducted along the fracture sections without root channels. For natural vertical hydraulic gradients (0.8-2.3 at the site), flow rates of 0.8-2 km/d were determined for a fracture root channel, while fracture sections without root channels revealed flow rates of 9-22 m/d. Corresponding flow rates in the unfractured matrix were 7-19 mm/yr. For infiltrated bromide (nonreactive tracer) and mobile pesticides mecoprop (MCPP) and metsulfuron, very rapid migration (0.28-0.5 m/d) and high relative breakthrough concentrations (30-60%) into the aquifer were observed to occur along the fracture root channels using a constant hydraulic gradient of 1. Only traces were measured from infiltration of the strongly sorbed pesticide prochloraz. The concentrations of the bromide and pesticides in the monitoring wells were modeled with a discrete fracture matrix diffusion (DFDM) model coupled with a single porosity model (SP) for the till and aquifer, respectively. Using effective fracture spacings and mean fracture apertures for the fracture channel sections as modeling input parameters for the till, the concentrations observed in the wells of the aquifer could be reasonably approximated.

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1990-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that were reduced to a relatively compact set of equations of a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-averaged behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equation a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. For hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates, chemical nonequilibrium is considered and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1989-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that have been reduced to a relatively compact set of equations in a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-average behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equations a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. Hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates chemical nonequilibrium is considered, and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

Mitigation of lava flow invasion hazard through optimized barrier configuration aided by numerical simulation: The case of the 2001 Etna eruption

NASA Astrophysics Data System (ADS)

Scifoni, S.; Coltelli, M.; Marsella, M.; Proietti, C.; Napoleoni, Q.; Vicari, A.; Del Negro, C.

2010-04-01

Lava flow spreading along the flanks of Etna volcano often produces damages to the land and proprieties. The impact of these eruptions could be mitigated by building artificial barriers for controlling and slowing down the lava, as recently experienced in 1983, 1991-1993, 2001 and 2002. This study investigates how numerical simulations can be adopted for evaluating the effectiveness of barrier construction and for optimizing their geometry, considering as test case the lava flows emplaced on Etna's south flank during 2001. The flow temporal evolutions were reconstructed deriving the effusion rate trends, together with the pre-eruption topography were adopted as input data of the MAGFLOW simulation code. Three simulations were then conducted to simulate lava flow with and without barriers. The first aimed at verifying the reconstruction of the effusion rate trends, while the others at assessing the performance of the barrier system realized during the eruption in comparison with an alternative solution here proposed. A quantitative analysis carried out on the first simulation confirms the suitability of the selected test case. The comparison of the three simulated thickness distributions showed both the effectiveness of the barriers in slowing down the lava flow and the sensitivity of the MAGFLOW code to the topographical variations represented by the barriers. Finally, for reducing both the time necessary to erect the barrier and the barrier environmental impact, the gabion's barrier construction was analyzed. The implemented and tested procedure enforces the capability of using numerical simulations for designing optimized lava flow barriers aimed at making swifter mitigatory actions upon lava flows and improving the effectiveness of civil protection interventions during emergencies.

Finite-time braiding exponents

NASA Astrophysics Data System (ADS)

Budišić, Marko; Thiffeault, Jean-Luc

2015-08-01

Topological entropy of a dynamical system is an upper bound for the sum of positive Lyapunov exponents; in practice, it is strongly indicative of the presence of mixing in a subset of the domain. Topological entropy can be computed by partition methods, by estimating the maximal growth rate of material lines or other material elements, or by counting the unstable periodic orbits of the flow. All these methods require detailed knowledge of the velocity field that is not always available, for example, when ocean flows are measured using a small number of floating sensors. We propose an alternative calculation, applicable to two-dimensional flows, that uses only a sparse set of flow trajectories as its input. To represent the sparse set of trajectories, we use braids, algebraic objects that record how trajectories exchange positions with respect to a projection axis. Material curves advected by the flow are represented as simplified loop coordinates. The exponential rate at which a braid stretches loops over a finite time interval is the Finite-Time Braiding Exponent (FTBE). We study FTBEs through numerical simulations of the Aref Blinking Vortex flow, as a representative of a general class of flows having a single invariant component with positive topological entropy. The FTBEs approach the value of the topological entropy from below as the length and number of trajectories is increased; we conjecture that this result holds for a general class of ergodic, mixing systems. Furthermore, FTBEs are computed robustly with respect to the numerical time step, details of braid representation, and choice of initial conditions. We find that, in the class of systems we describe, trajectories can be re-used to form different braids, which greatly reduces the amount of data needed to assess the complexity of the flow.

Finite-time braiding exponents.

PubMed

Budišić, Marko; Thiffeault, Jean-Luc

2015-08-01

Topological entropy of a dynamical system is an upper bound for the sum of positive Lyapunov exponents; in practice, it is strongly indicative of the presence of mixing in a subset of the domain. Topological entropy can be computed by partition methods, by estimating the maximal growth rate of material lines or other material elements, or by counting the unstable periodic orbits of the flow. All these methods require detailed knowledge of the velocity field that is not always available, for example, when ocean flows are measured using a small number of floating sensors. We propose an alternative calculation, applicable to two-dimensional flows, that uses only a sparse set of flow trajectories as its input. To represent the sparse set of trajectories, we use braids, algebraic objects that record how trajectories exchange positions with respect to a projection axis. Material curves advected by the flow are represented as simplified loop coordinates. The exponential rate at which a braid stretches loops over a finite time interval is the Finite-Time Braiding Exponent (FTBE). We study FTBEs through numerical simulations of the Aref Blinking Vortex flow, as a representative of a general class of flows having a single invariant component with positive topological entropy. The FTBEs approach the value of the topological entropy from below as the length and number of trajectories is increased; we conjecture that this result holds for a general class of ergodic, mixing systems. Furthermore, FTBEs are computed robustly with respect to the numerical time step, details of braid representation, and choice of initial conditions. We find that, in the class of systems we describe, trajectories can be re-used to form different braids, which greatly reduces the amount of data needed to assess the complexity of the flow.

Trade Agreements: Impact on the U.S. Economy

DTIC Science & Technology

2009-11-10

model is consistent with the Ricardian and Heckscher- Ohlin models . An important drawback of the model is that it can estimate only the aggregate...24 Now known as the Michigan Brown-Deardorff-Stern Model , the Michigan Model of World Production and Trade includes data on 29...economy in the model . Input- output accounts trace the flow of input commodities into the production processes of industries, the flow of intermediate

Blade loss transient dynamics analysis. Volume 3: User's manual for TETRA program

NASA Technical Reports Server (NTRS)

Black, G. R.; Gallardo, V. C.; Storace, A. S.; Sagendorph, F.

1981-01-01

The users manual for TETRA contains program logic, flow charts, error messages, input sheets, modeling instructions, option descriptions, input variable descriptions, and demonstration problems. The process of obtaining a NASTRAN 17.5 generated modal input file for TETRA is also described with a worked sample.

CFEST Coupled Flow, Energy & Solute Transport Version CFEST005 User’s Guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freedman, Vicky L.; Chen, Yousu; Gilca, Alex

2006-07-20

The CFEST (Coupled Flow, Energy, and Solute Transport) simulator described in this User’s Guide is a three-dimensional finite-element model used to evaluate groundwater flow and solute mass transport. Confined and unconfined aquifer systems, as well as constant and variable density fluid flows can be represented with CFEST. For unconfined aquifers, the model uses a moving boundary for the water table, deforming the numerical mesh so that the uppermost nodes are always at the water table. For solute transport, changes in concentra¬tion of a single dissolved chemical constituent are computed for advective and hydrodynamic transport, linear sorption represented by a retardationmore » factor, and radioactive decay. Although several thermal parameters described in this User’s Guide are required inputs, thermal transport has not yet been fully implemented in the simulator. Once fully implemented, transport of thermal energy in the groundwater and solid matrix of the aquifer can also be used to model aquifer thermal regimes. The CFEST simulator is written in the FORTRAN 77 language, following American National Standards Institute (ANSI) standards. Execution of the CFEST simulator is controlled through three required text input files. These input file use a structured format of associated groups of input data. Example input data lines are presented for each file type, as well as a description of the structured FORTRAN data format. Detailed descriptions of all input requirements, output options, and program structure and execution are provided in this User’s Guide. Required inputs for auxillary CFEST utilities that aide in post-processing data are also described. Global variables are defined for those with access to the source code. Although CFEST is a proprietary code (CFEST, Inc., Irvine, CA), the Pacific Northwest National Laboratory retains permission to maintain its own source, and to distribute executables to Hanford subcontractors.« less

Risk assessment of debris flow hazards in natural slope

NASA Astrophysics Data System (ADS)

Choi, Junghae; Chae, Byung-gon; Liu, Kofei; Wu, Yinghsin

2016-04-01

The study area is located at north-east part of South Korea. Referring to the map of landslide sus-ceptibility (KIGAM, 2009) from Korea Institute of Geoscience and Mineral Resources (KIGAM for short), there are large areas of potential landslide in high probability on slope land of mountain near the study area. Besides, recently some severe landslide-induced debris flow hazards occurred in this area. So this site is convinced to be prone to debris flow haz-ards. In order to mitigate the influence of hazards, the assessment of potential debris flow hazards is very important and essential. In this assessment, we use Debris-2D, debris flow numerical program, to assess the potential debris flow hazards. The worst scenario is considered for simulation. The input mass sources are determined using landslide susceptibility map. The water input is referred to the daily accumulative rainfall in the past debris flow event in study area. The only one input material property, i.e. yield stress, is obtained using calibration test. The simulation results show that the study area has po-tential to be impacted by debris flow. Therefore, based on simulation results, to mitigate debris flow hazards, we can propose countermeasures, including building check dams, constructing a protection wall in study area, and installing instruments for active monitoring of debris flow hazards. Acknowledgements:This research was supported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2012M3A2A1050983)

40 CFR 75.71 - Specific provisions for monitoring NOX and heat input for the purpose of calculating NOX mass...

Code of Federal Regulations, 2011 CFR

2011-07-01

... and heat input for the purpose of calculating NOX mass emissions. 75.71 Section 75.71 Protection of... MONITORING NOX Mass Emissions Provisions § 75.71 Specific provisions for monitoring NOX and heat input for... and for a flow monitoring system and an O2 or CO2 diluent gas monitoring system to measure heat input...

40 CFR 75.36 - Missing data procedures for heat input rate determinations.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 16 2011-07-01 2011-07-01 false Missing data procedures for heat input... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Missing Data Substitution Procedures § 75.36 Missing data procedures for heat input rate determinations. (a) When hourly heat input rate is...

40 CFR 75.36 - Missing data procedures for heat input rate determinations.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Missing data procedures for heat input... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Missing Data Substitution Procedures § 75.36 Missing data procedures for heat input rate determinations. (a) When hourly heat input rate is...

40 CFR 75.36 - Missing data procedures for heat input rate determinations.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Missing data procedures for heat input... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Missing Data Substitution Procedures § 75.36 Missing data procedures for heat input rate determinations. (a) When hourly heat input rate is...

40 CFR 75.36 - Missing data procedures for heat input rate determinations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Missing data procedures for heat input... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Missing Data Substitution Procedures § 75.36 Missing data procedures for heat input rate determinations. (a) When hourly heat input rate is...

40 CFR 75.36 - Missing data procedures for heat input rate determinations.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 17 2012-07-01 2012-07-01 false Missing data procedures for heat input... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTINUOUS EMISSION MONITORING Missing Data Substitution Procedures § 75.36 Missing data procedures for heat input rate determinations. (a) When hourly heat input rate is...

Input related microbial carbon dynamic of soil organic matter in particle size fractions

NASA Astrophysics Data System (ADS)

Gude, A.; Kandeler, E.; Gleixner, G.

2012-04-01

This paper investigated the flow of carbon into different groups of soil microorganisms isolated from different particle size fractions. Two agricultural sites of contrasting organic matter input were compared. Both soils had been submitted to vegetation change from C3 (Rye/Wheat) to C4 (Maize) plants, 25 and 45 years ago. Soil carbon was separated into one fast-degrading particulate organic matter fraction (POM) and one slow-degrading organo-mineral fraction (OMF). The structure of the soil microbial community were investigated using phospholipid fatty acids (PLFA), and turnover of single PLFAs was calculated from the changes in their 13C content. Soil enzyme activities involved in the degradation of carbohydrates was determined using fluorogenic MUF (methyl-umbelliferryl phosphate) substrates. We found that fresh organic matter input drives soil organic matter dynamic. Higher annual input of fresh organic matter resulted in a higher amount of fungal biomass in the POM-fraction and shorter mean residence times. Fungal activity therefore seems essential for the decomposition and incorporation of organic matter input into the soil. As a consequence, limited litter input changed especially the fungal community favouring arbuscular mycorrhizal fungi. Altogether, supply and availability of fresh plant carbon changed the distribution of microbial biomass, the microbial community structure and enzyme activities and resulted in different priming of soil organic matter. Most interestingly we found that only at low input the OMF fraction had significantly higher calculated MRT for Gram-positive and Gram-negative bacteria suggesting high recycling of soil carbon or the use of other carbon sources. But on average all microbial groups had nearly similar carbon uptake rates in all fractions and both soils, which contrasted the turnover times of bulk carbon. Hereby the microbial carbon turnover was always faster than the soil organic carbon turnover and higher carbon input reduced the carbon storage efficiency from 51 % in the low input to 20 %. These findings suggest that microbial community preferentially assimilated fresh carbon sources but also used recycled existing soil carbon. However, the priming rate was drastically reduced under carbon limitation. In consequence at high carbon availability more carbon was respired to activate the existing soil carbon (priming) whereas at low carbon availability new soil carbon was formed at higher efficiencies.

Input variable selection for data-driven models of Coriolis flowmeters for two-phase flow measurement

NASA Astrophysics Data System (ADS)

Wang, Lijuan; Yan, Yong; Wang, Xue; Wang, Tao

2017-03-01

Input variable selection is an essential step in the development of data-driven models for environmental, biological and industrial applications. Through input variable selection to eliminate the irrelevant or redundant variables, a suitable subset of variables is identified as the input of a model. Meanwhile, through input variable selection the complexity of the model structure is simplified and the computational efficiency is improved. This paper describes the procedures of the input variable selection for the data-driven models for the measurement of liquid mass flowrate and gas volume fraction under two-phase flow conditions using Coriolis flowmeters. Three advanced input variable selection methods, including partial mutual information (PMI), genetic algorithm-artificial neural network (GA-ANN) and tree-based iterative input selection (IIS) are applied in this study. Typical data-driven models incorporating support vector machine (SVM) are established individually based on the input candidates resulting from the selection methods. The validity of the selection outcomes is assessed through an output performance comparison of the SVM based data-driven models and sensitivity analysis. The validation and analysis results suggest that the input variables selected from the PMI algorithm provide more effective information for the models to measure liquid mass flowrate while the IIS algorithm provides a fewer but more effective variables for the models to predict gas volume fraction.

Stream-flow forecasting using extreme learning machines: A case study in a semi-arid region in Iraq

NASA Astrophysics Data System (ADS)

Yaseen, Zaher Mundher; Jaafar, Othman; Deo, Ravinesh C.; Kisi, Ozgur; Adamowski, Jan; Quilty, John; El-Shafie, Ahmed

2016-11-01

Monthly stream-flow forecasting can yield important information for hydrological applications including sustainable design of rural and urban water management systems, optimization of water resource allocations, water use, pricing and water quality assessment, and agriculture and irrigation operations. The motivation for exploring and developing expert predictive models is an ongoing endeavor for hydrological applications. In this study, the potential of a relatively new data-driven method, namely the extreme learning machine (ELM) method, was explored for forecasting monthly stream-flow discharge rates in the Tigris River, Iraq. The ELM algorithm is a single-layer feedforward neural network (SLFNs) which randomly selects the input weights, hidden layer biases and analytically determines the output weights of the SLFNs. Based on the partial autocorrelation functions of historical stream-flow data, a set of five input combinations with lagged stream-flow values are employed to establish the best forecasting model. A comparative investigation is conducted to evaluate the performance of the ELM compared to other data-driven models: support vector regression (SVR) and generalized regression neural network (GRNN). The forecasting metrics defined as the correlation coefficient (r), Nash-Sutcliffe efficiency (ENS), Willmott's Index (WI), root-mean-square error (RMSE) and mean absolute error (MAE) computed between the observed and forecasted stream-flow data are employed to assess the ELM model's effectiveness. The results revealed that the ELM model outperformed the SVR and the GRNN models across a number of statistical measures. In quantitative terms, superiority of ELM over SVR and GRNN models was exhibited by ENS = 0.578, 0.378 and 0.144, r = 0.799, 0.761 and 0.468 and WI = 0.853, 0.802 and 0.689, respectively and the ELM model attained lower RMSE value by approximately 21.3% (relative to SVR) and by approximately 44.7% (relative to GRNN). Based on the findings of this study, several recommendations were suggested for further exploration of the ELM model in hydrological forecasting problems.

Computer program for preliminary design analysis of axial-flow turbines

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1972-01-01

The program method is based on a mean-diameter flow analysis. Input design requirements include power or pressure ratio, flow, temperature, pressure, and speed. Turbine designs are generated for any specified number of stages and for any of three types of velocity diagrams (symmetrical, zero exit swirl, or impulse). Exit turning vanes can be included in the design. Program output includes inlet and exit annulus dimensions, exit temperature and pressure, total and static efficiencies, blading angles, and last-stage critical velocity ratios. The report presents the analysis method, a description of input and output with sample cases, and the program listing.

A Finite-Rate-Catalytic Model For Hypersonic Flows Informed By Molecular Dynamics

NASA Astrophysics Data System (ADS)

Schwartzentruber, T. E.; Valentini, P.; Norman, P.; Sorensen, C.

2011-05-01

The implementation of a finite-rate catalytic (FRC) wall boundary condition within a general 3D unstructured CFD solver is described. A set of one-step gas-surface chemical equations and atomistic parameters that deter- mine the reaction rates must be prescribed as input to the model. The chemical rate equations are solved at each wall face in the CFD simulation and result in a net production of species at the wall. In order for a finite- rate gas-surface reaction model to be consistent at equilibrium, it is determined that not all forward and back- ward rates can be specified arbitrarily. Provided that the forward rates for each surface recombination are as- signed, the backward rates must be determined using equilibrium constants that are consistent with the gas- phase chemistry model and thermodynamics. Reactive molecular dynamics (MD) simulations are performed us- ing the ReaxFFSiO potential to investigate oxygen-silica interactions. β-quartz and amorphous SiO2 surfaces are accommodated to a high temperature gas via MD simulation and reach a steady-state surface coverage. In addition to stable surface reconstructions a number of active sites are observed on which recombination occurs. Single collision MD simulations are performed where gas-phase oxygen atoms interact with the most dominant active site. Probabilities of recombination are found to have an exponential trend with gas-surface system temperature. The MD simulations are used to determine the activation energy for Eley-Rideal recombination of oxygen on a specific silica active site which is an important input parameter for the FRC model.

Method for analyzing the chemical composition of liquid effluent from a direct contact condenser

DOEpatents

Bharathan, Desikan; Parent, Yves; Hassani, A. Vahab

2001-01-01

A computational modeling method for predicting the chemical, physical, and thermodynamic performance of a condenser using calculations based on equations of physics for heat, momentum and mass transfer and equations of equilibrium thermodynamics to determine steady state profiles of parameters throughout the condenser. The method includes providing a set of input values relating to a condenser including liquid loading, vapor loading, and geometric characteristics of the contact medium in the condenser. The geometric and packing characteristics of the contact medium include the dimensions and orientation of a channel in the contact medium. The method further includes simulating performance of the condenser using the set of input values to determine a related set of output values such as outlet liquid temperature, outlet flow rates, pressures, and the concentration(s) of one or more dissolved noncondensable gas species in the outlet liquid. The method may also include iteratively performing the above computation steps using a plurality of sets of input values and then determining whether each of the resulting output values and performance profiles satisfies acceptance criteria.

The influence of fish cage aquaculture on pelagic carbon flow and water chemistry in tidally dominated mangrove estuaries of peninsular Malaysia.

PubMed

Alongi, D M; Chong, V C; Dixon, P; Sasekumar, A; Tirendi, F

2003-05-01

The impact of floating net cages culturing the seabass, Lates calcarifer, on planktonic processes and water chemistry in two heavily used mangrove estuaries in Malaysia was examined. Concentrations of dissolved inorganic and particulate nutrients were usually greater in cage vs. adjacent (approximately 100 m) non-cage waters, although most variability in water-column chemistry related to water depth and tides. There were few consistent differences in plankton abundance, production or respiration between cage and non-cage sites. Rates of primary production were low compared with rates of pelagic mineralization reflecting high suspended loads coupled with large inputs of organic matter from mangrove forests, fishing villages, fish cages, pig farms and other industries within the catchment. Our preliminary sampling did not reveal any large-scale eutrophication due to the cages. A crude estimate of the contribution of fish cage inputs to the estuaries shows that fish cages contribute only approximately 2% of C but greater percentages of N (32-36%) and P (83-99%) to these waters relative to phytoplankton and mangrove inputs. Isolating and detecting impacts of cage culture in such heavily used waterways--a situation typical of most mangrove estuaries in Southeast Asia--are constrained by a background of large, highly variable fluxes of organic material derived from extensive mangrove forests and other human activities. Copyright 2002 Elsevier Science B.V.

Energy structure of MHD flow coupling with outer resistance circuit

NASA Astrophysics Data System (ADS)

Huang, Z. Y.; Liu, Y. J.; Chen, Y. Q.; Peng, Z. L.

2015-08-01

Energy structure of MHD flow coupling with outer resistance circuit is studied to illuminate qualitatively and quantitatively the energy relation of this basic MHD flow system with energy input and output. Energy structure are analytically derived based on the Navier-Stocks equations for two-dimensional fully-developed flow and generalized Ohm's Law. The influences of applied magnetic field, Hall parameter and conductivity on energy structure are discussed based on the analytical results. Associated energies in MHD flow are deduced and validated by energy conservation. These results reveal that energy structure consists of two sub structures: electrical energy structure and internal energy structure. Energy structure and its sub structures provide an integrated theoretical energy path of the MHD system. Applied magnetic field and conductivity decrease the input energy, dissipation by fluid viscosity and internal energy but increase the ratio of electrical energy to input energy, while Hall parameter has the opposite effects. These are caused by their different effects on Bulk velocity, velocity profiles, voltage and current in outer circuit. Understanding energy structure helps MHD application designers to actively adjust the allocation of different parts of energy so that it is more reasonable and desirable.

Modeling Streamflow and Water Temperature in the North Santiam and Santiam Rivers, Oregon, 2001-02

USGS Publications Warehouse

Sullivan, Annett B.; Roundsk, Stewart A.

2004-01-01

To support the development of a total maximum daily load (TMDL) for water temperature in the Willamette Basin, the laterally averaged, two-dimensional model CE-QUAL-W2 was used to construct a water temperature and streamflow model of the Santiam and North Santiam Rivers. The rivers were simulated from downstream of Detroit and Big Cliff dams to the confluence with the Willamette River. Inputs to the model included bathymetric data, flow and temperature from dam releases, tributary flow and temperature, and meteorologic data. The model was calibrated for the period July 1 through November 21, 2001, and confirmed with data from April 1 through October 31, 2002. Flow calibration made use of data from two streamflow gages and travel-time and river-width data. Temperature calibration used data from 16 temperature monitoring locations in 2001 and 5 locations in 2002. A sensitivity analysis was completed by independently varying input parameters, including point-source flow, air temperature, flow and water temperature from dam releases, and riparian shading. Scenario analyses considered hypothetical river conditions without anthropogenic heat inputs, with restored riparian vegetation, with minimum streamflow from the dams, and with a more-natural seasonal water temperature regime from dam releases.

Implementation and Validation of an Impedance Eduction Technique

NASA Technical Reports Server (NTRS)

Watson, Willie R.; Jones, Michael G.; Gerhold, Carl H.

2011-01-01

Implementation of a pressure gradient method of impedance eduction in two NASA Langley flow ducts is described. The Grazing Flow Impedance Tube only supports plane-wave sources, while the Curved Duct Test Rig supports sources that contain higher-order modes. Multiple exercises are used to validate this new impedance eduction method. First, synthesized data for a hard wall insert and a conventional liner mounted in the Grazing Flow Impedance Tube are used as input to the two impedance eduction methods, the pressure gradient method and a previously validated wall pressure method. Comparisons between the two results are excellent. Next, data measured in the Grazing Flow Impedance Tube are used as input to both methods. Results from the two methods compare quite favorably for sufficiently low Mach numbers but this comparison degrades at Mach 0.5, especially when the hard wall insert is used. Finally, data measured with a hard wall insert mounted in the Curved Duct Test Rig are used as input to the pressure gradient method. Significant deviation from the known solution is observed, which is believed to be largely due to 3-D effects in this flow duct. Potential solutions to this issue are currently being explored.

Real Time Global Tests of the ALICE High Level Trigger Data Transport Framework

NASA Astrophysics Data System (ADS)

Becker, B.; Chattopadhyay, S.; Cicalo, C.; Cleymans, J.; de Vaux, G.; Fearick, R. W.; Lindenstruth, V.; Richter, M.; Rohrich, D.; Staley, F.; Steinbeck, T. M.; Szostak, A.; Tilsner, H.; Weis, R.; Vilakazi, Z. Z.

2008-04-01

The High Level Trigger (HLT) system of the ALICE experiment is an online event filter and trigger system designed for input bandwidths of up to 25 GB/s at event rates of up to 1 kHz. The system is designed as a scalable PC cluster, implementing several hundred nodes. The transport of data in the system is handled by an object-oriented data flow framework operating on the basis of the publisher-subscriber principle, being designed fully pipelined with lowest processing overhead and communication latency in the cluster. In this paper, we report the latest measurements where this framework has been operated on five different sites over a global north-south link extending more than 10,000 km, processing a ldquoreal-timerdquo data flow.

Contamination-Free Sonoreactor for the Food Industry

NASA Astrophysics Data System (ADS)

Dion, Jean-Luc

A new sonoreactor technology is presented here, which should open vast development possibilities in various fields of chemical, pharmaceutical, and food industries. It should give a decisive impulse to sonochemistry in these various areas. These exclusive systems use high-power converging acoustic waves in a tube to produce a relatively large volume confined acoustic cavitation zone in flowing liquid reagents. It is well known that numerous chemical reactions are strongly accelerated when they take place inside such a zone. The new cylindrical sonoreactors do not contaminate the processed liquids with erosion products as other devices do. The processing conditions can be widely varied with pressure, power, temperature, and flow rate. The processing capacity of the largest models may be up to several tons per hour, using an electric power input of about 50 kW.

Drilling and completion specifications for CA series multilevel piezometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clawson, T.S.

1986-08-01

CX Series multilevel piezometer boreholes will provide information on hydraulic heads in the Rosalia, Sentinel Gap, Ginkgo, Rocky Coulee, Cohassett, Birkett, and Umtanum flow tops. The borehole sites will be located adjacent to the reference repository location. In addition, information from the boreholes will provide input data used to determine horizontal and vertical flow rates, and identify possible geologic structures. This specification includes details for drilling, piezometer design, hydrologic testing, and hydrochemical sampling of the boreholes. It includes drilling requirements, design, and installation procedures for the series piezometer nests, intervals selected for head monitoring and schedules for drilling and piezometermore » installation. Specific drilling and piezometer installation specifications for boreholes DC-24CX and DC-25CX are also included. 27 refs., 5 figs., 3 tabs.« less

An experimental study of energy loss mechanisms and efficiency consideration in the low power dc arcjet

NASA Technical Reports Server (NTRS)

Curran, F. M.

1985-01-01

The potential utility of the low power dc arcjet in auxiliary propulsion was investigated. It was indicated that improvements in the areas of stability, energy efficiency, reliability, and electrode erosion are necessary to obtain a useful device. A water-cooled arcjet simulator was tested to investigate both the energy loss mechanisms at the electrodes and the stability of different conventional arcjet configurations in the presence of a vortex flow field. It is shown that in certain configurations only 25 to 30% of the input energy is lost to the electrodes. It is also shown that vortex stabilization is not difficult to obtain in many cases at the flow rates used and that a careful starting procedure is effective in minimizing electrode damage.

An experimental study of energy loss mechanisms and efficiency considerations in the low power dc arcjet

NASA Technical Reports Server (NTRS)

Curran, F. M.

1985-01-01

The potential utility of the low power dc arcjet in auxiliary propulsion was investigated. It was indicated that improvements in the areas of stability, energy efficiency, reliability, and electrode erosion are necessary to obtain a useful device. A water-cooled arcjet simulator was tested to investigate both the energy loss mechanisms at the electrodes and the stability of different conventional arcjet configurations in the presence of a vortex flow field. It is shown that in certain configurations only 25 to 30 percent of the input energy is lost to the electrodes. It is also shown that vortex stabilization is not difficult to obtain in many cases at the flow rates used and that a careful starting procedure is effective in minimizing electrode damage.

Unsteady heat transfer performance of heat pipe with axially swallow-tailed microgrooves

NASA Astrophysics Data System (ADS)

Zhang, R. P.

2017-04-01

A mathematical model is developed for predicting the transient heat transfer and fluid flow of heat pipe with axially swallow-tailed microgrooves. The effects of liquid convective heat transfer in the microgrooves, liquid-vapor interfacial phase-change heat transfer and liquid-vapor interfacial shear stress are accounted for in the present model. The coupled non-linear control equations are solved numerically. Mass flow rate at the interface is obtained from the application of kinetic theory. Time variation of wall temperature is studied from the initial startup to steady state. The numerical results are verified by experiments. Time constants for startup and shutdown operation are defined to determine how fast a heat pipe responds to an applied input heat flux, which slightly decreases with increasing heat load.

Development of an Air Brayton solar receiver

NASA Technical Reports Server (NTRS)

1980-01-01

Various receiver configurations and operating conditions were examined. The interface requirements between the receiver/concentrator/power module were addressed. Production cost estimates were obtained to determine the cost of the receiver during the 1980 timeframe. A conceptual design of an air Brayton solar receiver is presented based on the results. The following design goals were established: (1)peak thermal input power - 85 KWt; (2)receiver outlet air temperature - 1500 F; (3)receiver inlet air temperature - 1050 F; (4)design mass flow rate - 0.533 lb/sec; and (5)design receiver inlet pressure - 36.75 psia.

Freedrop Testing and CFD Simulation of Ice Models from a Cavity into Supersonic Flow

DTIC Science & Technology

2012-09-01

constructed of stereo lithography (SLA) plastic filled with assorted metal washers for ballast. This allowed the mass and moment of inertia to be finely...set to 0.005 in, with a growth rate of 1.2, extruded out to 0.5 in from the surface of the sphere. The final, multiblock grid input into the OVERFLOW...size article made of balsa wood . While these values illustrate the mass scaling relationship of heavy Mach scaling, with the exception of the 1 Psia case

Optimization of the SHX Fusion Powered Transatmospheric Propulsion Concept

NASA Technical Reports Server (NTRS)

Adams, Robert B.; Landrum, D. Brian

2001-01-01

Existing propulsion technology has not achieved cost effective payload delivery rates to low earth orbit. A fusion based propulsion system, denoted as the Simultaneous Heating and eXpansion (SHX) engine, has been proposed in earlier papers. The SHX couples energy generated by a fusion reactor to the engine flowpath by use of coherent beam emitters. A quasi-one-dimensional flow model was used to quantify the effects of area expansion and energy input on propulsive efficiency for several beam models. Entropy calculations were included to evaluate the lost work in the system.

Off-design computer code for calculating the aerodynamic performance of axial-flow fans and compressors

NASA Technical Reports Server (NTRS)

Schmidt, James F.

1995-01-01

An off-design axial-flow compressor code is presented and is available from COSMIC for predicting the aerodynamic performance maps of fans and compressors. Steady axisymmetric flow is assumed and the aerodynamic solution reduces to solving the two-dimensional flow field in the meridional plane. A streamline curvature method is used for calculating this flow-field outside the blade rows. This code allows for bleed flows and the first five stators can be reset for each rotational speed, capabilities which are necessary for large multistage compressors. The accuracy of the off-design performance predictions depend upon the validity of the flow loss and deviation correlation models. These empirical correlations for the flow loss and deviation are used to model the real flow effects and the off-design code will compute through small reverse flow regions. The input to this off-design code is fully described and a user's example case for a two-stage fan is included with complete input and output data sets. Also, a comparison of the off-design code predictions with experimental data is included which generally shows good agreement.

Daily River Flow Forecasting with Hybrid Support Vector Machine – Particle Swarm Optimization

NASA Astrophysics Data System (ADS)

Zaini, N.; Malek, M. A.; Yusoff, M.; Mardi, N. H.; Norhisham, S.

2018-04-01

The application of artificial intelligence techniques for river flow forecasting can further improve the management of water resources and flood prevention. This study concerns the development of support vector machine (SVM) based model and its hybridization with particle swarm optimization (PSO) to forecast short term daily river flow at Upper Bertam Catchment located in Cameron Highland, Malaysia. Ten years duration of historical rainfall, antecedent river flow data and various meteorology parameters data from 2003 to 2012 are used in this study. Four SVM based models are proposed which are SVM1, SVM2, SVM-PSO1 and SVM-PSO2 to forecast 1 to 7 day ahead of river flow. SVM1 and SVM-PSO1 are the models with historical rainfall and antecedent river flow as its input, while SVM2 and SVM-PSO2 are the models with historical rainfall, antecedent river flow data and additional meteorological parameters as input. The performances of the proposed model are measured in term of RMSE and R2 . It is found that, SVM2 outperformed SVM1 and SVM-PSO2 outperformed SVM-PSO1 which meant the additional meteorology parameters used as input to the proposed models significantly affect the model performances. Hybrid models SVM-PSO1 and SVM-PSO2 yield higher performances as compared to SVM1 and SVM2. It is found that hybrid models are more effective in forecasting river flow at 1 to 7 day ahead at the study area.

Water, Energy, and Biogeochemical Model (WEBMOD), user’s manual, version 1

USGS Publications Warehouse

Webb, Richard M.T.; Parkhurst, David L.

2017-02-08

The Water, Energy, and Biogeochemical Model (WEBMOD) uses the framework of the U.S. Geological Survey (USGS) Modular Modeling System to simulate fluxes of water and solutes through watersheds. WEBMOD divides watersheds into model response units (MRU) where fluxes and reactions are simulated for the following eight hillslope reservoir types: canopy; snowpack; ponding on impervious surfaces; O-horizon; two reservoirs in the unsaturated zone, which represent preferential flow and matrix flow; and two reservoirs in the saturated zone, which also represent preferential flow and matrix flow. The reservoir representing ponding on impervious surfaces, currently not functional (2016), will be implemented once the model is applied to urban areas. MRUs discharge to one or more stream reservoirs that flow to the outlet of the watershed. Hydrologic fluxes in the watershed are simulated by modules derived from the USGS Precipitation Runoff Modeling System; the National Weather Service Hydro-17 snow model; and a topography-driven hydrologic model (TOPMODEL). Modifications to the standard TOPMODEL include the addition of heterogeneous vertical infiltration rates; irrigation; lateral and vertical preferential flows through the unsaturated zone; pipe flow draining the saturated zone; gains and losses to regional aquifer systems; and the option to simulate baseflow discharge by using an exponential, parabolic, or linear decrease in transmissivity. PHREEQC, an aqueous geochemical model, is incorporated to simulate chemical reactions as waters evaporate, mix, and react within the various reservoirs of the model. The reactions that can be specified for a reservoir include equilibrium reactions among water; minerals; surfaces; exchangers; and kinetic reactions such as kinetic mineral dissolution or precipitation, biologically mediated reactions, and radioactive decay. WEBMOD also simulates variations in the concentrations of the stable isotopes deuterium and oxygen-18 as a result of varying inputs, mixing, and evaporation. This manual describes the WEBMOD input and output files, along with the algorithms and procedures used to simulate the hydrology and water quality in a watershed. Examples are presented that demonstrate hydrologic processes, weathering reactions, and isotopic evolution in an alpine watershed and the effect of irrigation on water flows and salinity in an intensively farmed agricultural area.

Microstructural Evolution and Constitutive Relationship of M350 Grade Maraging Steel During Hot Deformation

NASA Astrophysics Data System (ADS)

Chakravarthi, K. V. A.; Koundinya, N. T. B. N.; Narayana Murty, S. V. S.; Nageswara Rao, B.

2017-03-01

Maraging steels exhibit extraordinary strength coupled with toughness and are therefore materials of choice for critical structural applications in defense, aerospace and nuclear engineering. Thermo-mechanical processing is an important step in the manufacture of these structural components. This process assumes significance as these materials are expensive and the mechanical properties obtained depend on the microstructure evolved during thermo-mechanical processing. In the present study, M350 grade maraging steel specimens were hot isothermally compressed in the temperature range of 900-1200 °C and in the strain rate range of 0.001-100 s-1, and true stress-true strain curves were generated. The microstructural evolution as a function of strain rate and temperature in the deformed compression specimens was studied. The effect of friction between sample and compression dies was evaluated, and the same was found to be low. The measured flow stress data was used for the development of a constitutive model to represent the hot deformation behavior of this alloy. The proposed equation can be used as an input in the finite element analysis to obtain the flow stress at any given strain, strain rate, and temperature useful for predicting the flow localization or fracture during thermo-mechanical simulation. The activation energy for hot deformation was calculated and is found to be 370.88 kJ/mol, which is similar to that of M250 grade maraging steel.

Lactation in the Human Breast From a Fluid Dynamics Point of View.

PubMed

Negin Mortazavi, S; Geddes, Donna; Hassanipour, Fatemeh

2017-01-01

This study is a collaborative effort among lactation specialists and fluid dynamic engineers. The paper presents clinical results for suckling pressure pattern in lactating human breast as well as a 3D computational fluid dynamics (CFD) modeling of milk flow using these clinical inputs. The investigation starts with a careful, statistically representative measurement of suckling vacuum pressure, milk flow rate, and milk intake in a group of infants. The results from clinical data show that suckling action does not occur with constant suckling rate but changes in a rhythmic manner for infants. These pressure profiles are then used as the boundary condition for the CFD study using commercial ansys fluent software. For the geometric model of the ductal system of the human breast, this work takes advantage of a recent advance in the development of a validated phantom that has been produced as a ground truth for the imaging applications for the breast. The geometric model is introduced into CFD simulations with the aforementioned boundary conditions. The results for milk intake from the CFD simulation and clinical data were compared and cross validated. Also, the variation of milk intake versus suckling pressure are presented and analyzed. Both the clinical and CFD simulation show that the maximum milk flow rate is not related to the largest vacuum pressure or longest feeding duration indicating other factors influence the milk intake by infants.

Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer

PubMed Central

Ye, Congwang; Chen, Anthony; Colombo, Paolo; Martinez, Carlos

2010-01-01

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s−1. Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 µm, shell thicknesses ranging from 10 to 50 µm and shell pore diameters ranging from 1 to 10 µm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core–shell multimaterial particles. PMID:20484226

Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer.

PubMed

Ye, Congwang; Chen, Anthony; Colombo, Paolo; Martinez, Carlos

2010-08-06

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s(-1). Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 microm, shell thicknesses ranging from 10 to 50 microm and shell pore diameters ranging from 1 to 10 microm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core-shell multimaterial particles.

A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise

PubMed Central

Lau, Kevin D.; Asrress, Kaleab N.; Redwood, Simon R.; Figueroa, C. Alberto

2016-01-01

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit. PMID:26945076

A mathematical model of coronary blood flow control: simulation of patient-specific three-dimensional hemodynamics during exercise.

PubMed

Arthurs, Christopher J; Lau, Kevin D; Asrress, Kaleab N; Redwood, Simon R; Figueroa, C Alberto

2016-05-01

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit. Copyright © 2016 the American Physiological Society.

An improved panel method for the solution of three-dimensional leading edge vortex flows Volume 2: User's guide and programmer's document

NASA Technical Reports Server (NTRS)

Tinoco, E. N.; Lu, P.; Johnson, F. T.

1980-01-01

A computer program developed for solving the subsonic, three dimensional flow over wing-body configurations with leading edge vortex separation is presented. Instructions are given for the proper set up and input of a problem into the computer code. Program input formats and output are described, as well as the overlay structure of the program. The program is written in FORTRAN.

Advances in Software Tools for Pre-processing and Post-processing of Overset Grid Computations

NASA Technical Reports Server (NTRS)

Chan, William M.

2004-01-01

Recent developments in three pieces of software for performing pre-processing and post-processing work on numerical computations using overset grids are presented. The first is the OVERGRID graphical interface which provides a unified environment for the visualization, manipulation, generation and diagnostics of geometry and grids. Modules are also available for automatic boundary conditions detection, flow solver input preparation, multiple component dynamics input preparation and dynamics animation, simple solution viewing for moving components, and debris trajectory analysis input preparation. The second is a grid generation script library that enables rapid creation of grid generation scripts. A sample of recent applications will be described. The third is the OVERPLOT graphical interface for displaying and analyzing history files generated by the flow solver. Data displayed include residuals, component forces and moments, number of supersonic and reverse flow points, and various dynamics parameters.

MODFLOW-NWT, A Newton formulation for MODFLOW-2005

USGS Publications Warehouse

Niswonger, Richard G.; Panday, Sorab; Ibaraki, Motomu

2011-01-01

This report documents a Newton formulation of MODFLOW-2005, called MODFLOW-NWT. MODFLOW-NWT is a standalone program that is intended for solving problems involving drying and rewetting nonlinearities of the unconfined groundwater-flow equation. MODFLOW-NWT must be used with the Upstream-Weighting (UPW) Package for calculating intercell conductances in a different manner than is done in the Block-Centered Flow (BCF), Layer Property Flow (LPF), or Hydrogeologic-Unit Flow (HUF; Anderman and Hill, 2000) Packages. The UPW Package treats nonlinearities of cell drying and rewetting by use of a continuous function of groundwater head, rather than the discrete approach of drying and rewetting that is used by the BCF, LPF, and HUF Packages. This further enables application of the Newton formulation for unconfined groundwater-flow problems because conductance derivatives required by the Newton method are smooth over the full range of head for a model cell. The NWT linearization approach generates an asymmetric matrix, which is different from the standard MODFLOW formulation that generates a symmetric matrix. Because all linear solvers presently available for use with MODFLOW-2005 solve only symmetric matrices, MODFLOW-NWT includes two previously developed asymmetric matrix-solver options. The matrix-solver options include a generalized-minimum-residual (GMRES) Solver and an Orthomin / stabilized conjugate-gradient (CGSTAB) Solver. The GMRES Solver is documented in a previously published report, such that only a brief description and input instructions are provided in this report. However, the CGSTAB Solver (called XMD) is documented in this report. Flow-property input for the UPW Package is designed based on the LPF Package and material-property input is identical to that for the LPF Package except that the rewetting and vertical-conductance correction options of the LPF Package are not available with the UPW Package. Input files constructed for the LPF Package can be used with slight modification as input for the UPW Package. This report presents the theory and methods used by MODFLOW-NWT, including the UPW Package. Additionally, this report provides comparisons of the new methodology to analytical solutions of groundwater flow and to standard MODFLOW-2005 results by use of an unconfined aquifer MODFLOW example problem. The standard MODFLOW-2005 simulation uses the LPF Package with the wet/dry option active. A new example problem also is presented to demonstrate MODFLOW-NWT's ability to provide a solution for a difficult unconfined groundwater-flow problem.

Temperature Regulation in Critical Salmon Habitat of the Middle Fork of the John Day River, Oregon.

NASA Astrophysics Data System (ADS)

Buskirk, B. A.; Selker, J. S.

2016-12-01

Flow and temperature within the Middle Fork of the John Day River, an arid Eastern Oregon river, is dominated primarily by contributions from groundwater fed tributaries. The hydrology of arid streams is an important metric for understanding the critical environment in which salmon spawn and salmonids reside. The regulation of temperature within these streams is considered the primary metric for survival rates of these fish. Since 2007 Oregon State University has conducted stream monitoring efforts on the Middle Fork of the John Day River at the Oxbow and Forrest Conservation Areas. These sites were chosen through collaborative effort with the Confederated Tribes of the Warm Springs Reservation of Oregon, who have been restoring remnant mining canals back to their natural sinuous river pattern. The John Day River is also one of the few undammed reaches in which salmon runs occur. Efforts have focused on fiber optic distributed temperature sensing (DTS), groundwater gradient, stream discharge, bed permeability, GPS location and stream bathymetry across the conservation sites. During the peak of summer, stream temperature exhibits a strong diurnal cycle ranging from 9° C to 23° C depending on the daily maximum observed within the reach. Salmon have been found to be sensitive to stream temperatures above 15° C and are unable to survive temperatures above 24° C (Bell et al, 1991). The synthesis of temperature and stream flow data we collected show that very little groundwater is contributing to flow and temperature in the main channel of our study site while tributaries provide a constant, typically 0.5 to 2° C cooler, input of water to the main river channel and significant source of flow (0.01 - 0.1 m3/s). Due to the minimal rain fall in this arid environment, snow melt infiltration is likely the primary annual source of recharge into the head waters of the tributaries while also providing temperature regulation through input of near 0° C water. This cold water input from tributaries in addition to bank overhanging sedge grass provide cool safe zones for the young and mature fish during peak summer temperatures.

Parallel momentum input by tangential neutral beam injections in stellarator and heliotron plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, S., E-mail: nishimura.shin@lhd.nifs.ac.jp; Nakamura, Y.; Nishioka, K.

The configuration dependence of parallel momentum inputs to target plasma particle species by tangentially injected neutral beams is investigated in non-axisymmetric stellarator/heliotron model magnetic fields by assuming the existence of magnetic flux-surfaces. In parallel friction integrals of the full Rosenbluth-MacDonald-Judd collision operator in thermal particles' kinetic equations, numerically obtained eigenfunctions are used for excluding trapped fast ions that cannot contribute to the friction integrals. It is found that the momentum inputs to thermal ions strongly depend on magnetic field strength modulations on the flux-surfaces, while the input to electrons is insensitive to the modulation. In future plasma flow studies requiringmore » flow calculations of all particle species in more general non-symmetric toroidal configurations, the eigenfunction method investigated here will be useful.« less

Validation of the inverse pulse wave transit time series as surrogate of systolic blood pressure in MVAR modeling.

PubMed

Giassi, Pedro; Okida, Sergio; Oliveira, Maurício G; Moraes, Raimes

2013-11-01

Short-term cardiovascular regulation mediated by the sympathetic and parasympathetic branches of the autonomic nervous system has been investigated by multivariate autoregressive (MVAR) modeling, providing insightful analysis. MVAR models employ, as inputs, heart rate (HR), systolic blood pressure (SBP) and respiratory waveforms. ECG (from which HR series is obtained) and respiratory flow waveform (RFW) can be easily sampled from the patients. Nevertheless, the available methods for acquisition of beat-to-beat SBP measurements during exams hamper the wider use of MVAR models in clinical research. Recent studies show an inverse correlation between pulse wave transit time (PWTT) series and SBP fluctuations. PWTT is the time interval between the ECG R-wave peak and photoplethysmography waveform (PPG) base point within the same cardiac cycle. This study investigates the feasibility of using inverse PWTT (IPWTT) series as an alternative input to SBP for MVAR modeling of the cardiovascular regulation. For that, HR, RFW, and IPWTT series acquired from volunteers during postural changes and autonomic blockade were used as input of MVAR models. Obtained results show that IPWTT series can be used as input of MVAR models, replacing SBP measurements in order to overcome practical difficulties related to the continuous sampling of the SBP during clinical exams.

Measurement of ozone production scaling in a helium plasma jet with oxygen admixture

NASA Astrophysics Data System (ADS)

Sands, Brian; Ganguly, Biswa

2012-10-01

Capillary dielectric barrier plasma jet devices that generate confined streamer-like discharges along a rare gas flow can produce significant quantities of reactive oxygen species with average input powers ranging from 100 mW to >1 W. We have measured spatially-resolved ozone production in a He plasma jet with O2 admixture concentrations up to 5% using absorption spectroscopy of the O3 Hartley band system. A 20-ns risetime, 10-13 kV positive unipolar voltage pulse train was used to power the discharge, with pulse repetition rates varied from 1-20 kHz. The discharge was operated in a transient glow mode to scale the input power by adjusting the gap width between the anode and downstream cathodic plane. Peak ozone number densities in the range of 10^16 - 10^17 cm-3 were measured. At a given voltage, the density of ozone increased monotonically up to 3% O2 admixture (6 mm gap) as the peak discharge current decreased by an order of magnitude. Ozone production increased with distance from the capillary, consistent with observations by other groups. Atomic oxygen production inferred from O-atom 777 nm emission intensity did not scale with ozone as the input power was increased. The spatial distribution of ozone and scaling with input power will be presented.

Impaired neurogenesis of the dentate gyrus is associated with pattern separation deficits: A computational study.

PubMed

Faghihi, Faramarz; Moustafa, Ahmed A

2016-09-01

The separation of input patterns received from the entorhinal cortex (EC) by the dentate gyrus (DG) is a well-known critical step of information processing in the hippocampus. Although the role of interneurons in separation pattern efficiency of the DG has been theoretically known, the balance of neurogenesis of excitatory neurons and interneurons as well as its potential role in information processing in the DG is not fully understood. In this work, we study separation efficiency of the DG for different rates of neurogenesis of interneurons and excitatory neurons using a novel computational model in which we assume an increase in the synaptic efficacy between excitatory neurons and interneurons and then its decay over time. Information processing in the EC and DG was simulated as information flow in a two layer feed-forward neural network. The neurogenesis rate was modeled as the percentage of new born neurons added to the neuronal population in each time bin. The results show an important role of an optimal neurogenesis rate of interneurons and excitatory neurons in the DG in efficient separation of inputs from the EC in pattern separation tasks. The model predicts that any deviation of the optimal values of neurogenesis rates leads to different decreased levels of the separation deficits of the DG which influences its function to encode memory.

Measurement of Giardia lamblia adhesion force using an integrated microfluidic assay.

PubMed

Lu, Ling; Zheng, Guo-Xia; Yang, Yu-Suo; Feng, Cheng-Yu; Liu, Fang-Fang; Wang, Yun-Hua

2017-02-01

The mechanisms how Giardias attach to the intestinal epithelium remain unclear. None of the methods currently being used to measure the attachment force could provide a continuous nutrition supply and a micro-aerobic atmosphere to the Giardia. Besides, they are all labor-intensive. In the present research, a microfluidic method based on electric circuit analogy was developed. The input fluid flowed through the inlet channel with different lengths and was distributed in four assay chambers. Shear force gradients were generated in chambers, too. This allowed an easy control of fluids and the shear forces. Most importantly, the shear stress large enough to detach Giardia could be generated in laminar flow regime. Moreover, analysis could be accomplished in one single test. By applying inlet flow rates of 30, 60, and 120 μL ml -1 , shear force gradients ranging from 19.47 to 60.50 Pa were generated. The adhesion forces of trophozoites were analyzed and the EC 50 of the force that caused 50% trophozoites detachment was calculated as 36.60 Pa. This paper presents a novel method for measurement of Giardia adhesion force. Graphical Abstract Measurement of Giardia adhesion force. Various of flow rates were applied to generate different shear forces and Giardia trophozoites remaining attached were counted (a-c). The percentages of attachment vs shear stress were plotted and the EC 50 of adhesion force was calculated (d).

Enhanced ozone production in a pulsed dielectric barrier discharge plasma jet with addition of argon to a He-O2 flow gas

NASA Astrophysics Data System (ADS)

Sands, Brian; Ganguly, Biswa; Scofield, James

2013-09-01

Ozone production in a plasma jet DBD driven with a 20-ns risetime unipolar pulsed voltage can be significantly enhanced using helium as the primary flow gas with an O2 coflow. The overvolted discharge can be sustained with up to a 5% O2 coflow at <20 kHz pulse repetition frequency at 13 kV applied voltage. Ozone production scales with the pulse repetition frequency up to a ``turnover frequency'' that depends on the O2 concentration, total gas flow rate, and applied voltage. For example, peak ozone densities >1016 cm-3 were measured with 3% O2 admixture and <3 W input power at a 12 kHz turnover frequency. A further increase in the repetition frequency results in increased discharge current and 777 nm O(5 P) emission, but decreased ozone production and is followed by a transition to a filamentary discharge mode. The addition of argon at concentrations >=5% reduces the channel conductivity and shifts the turnover frequency to higher frequencies. This results in increased ozone production for a given applied voltage and gas flow rate. Time-resolved Ar(1s5) and He(23S1) metastable densities were acquired along with discharge current and ozone density measurements to gain insight into the mechanisms of optimum ozone production.

Response and recovery of streams to an intense regional flooding event

NASA Astrophysics Data System (ADS)

Dethier, E.; Magilligan, F. J.; Renshaw, C. E.; Kantack, K. M.

2015-12-01

Determining the relative roles of frequent and infrequent events on landscape form and material transport has implications for understanding landscape development, and informs planning and infrastructure decisions. Flooding due to Tropical Storm Irene in 2011 provides a unique opportunity to examine the effects of a rare, major disturbance across a broad area (14,000 km2). Intense flooding caused variable but widespread channel and riparian reconfiguration, including 995 channel-adjacent mass-wasting events, collectively referred to here as landslides, that mostly occurred in glacial deposits. Of these, about half involved reactivation of existing scars. Landslides were generally small, ranging from 60 - 26,000 m2 in planform, and covered less than 0.01 % of land in the region, yet sediment input from landslides alone (131 mm/kyr when integrated over the study area) exceeded inferred local background erosion rates by 60 times. If Irene inputs are included in a thirty-year erosion record, the estimated erosion rate, 7.2 mm/kyr, aligns closely with long-term regional rates of 5-10 mm/kyr. Landslides also input trees to streams, increasing large wood influence on those reaches. Combined wood and sediment inputs contributed to channel changes downstream of landslides. In four years since Irene, terrestrial lidar and suspended sediment sampling has documented continued large wood and sediment input. Erosion occurred on each of seventeen monitored landslides during snowmelt, but is otherwise limited except during intense precipitation and/or flood events. Repeat lidar models have recorded erosion of up to 5,000 m3 on a single slide in one year, including as much as 4000 m3 during a single event. Tree fall on scarps during erosion events creates sediment traps at the base of landslides, contributing to an observed return to equilibrium slopes. Despite trapping, substantial sediment continues to enter streams. Ninety-five suspended sediment samples from forty sites show that landslides remain important sediment sources. Across a range of flows, 2014 - 2015 sediment flux for a given discharge is an order of magnitude higher than pre-Irene flux. Though landslide slope relaxation suggests incipient recovery from Irene, persistent rapid erosion of large wood and sediment indicates that recovery is still on-going.

SP industry calorimeter for rate of heat release measurements up to 10MW

NASA Astrophysics Data System (ADS)

Dahlberg, Martin

The Swedish National Testing and Research Institute (SP) has installed a 10 MW fire calorimeter for rate of heat release measurements, similar to the one at Factory Mutual Research Corporation (FMRC). It can be used to classify commodities with respect to their fire hazard, to evaluate the efficiency of sprinkler systems, for chemical analysis of the combustion gases from hazardous fires, to produce input data for the fire modelling, etc. A large hood collects the fire gases and leads them into a duct where gas velocity, gas temperature, smoke density, and contents of oxygen, carbon dioxide, and carbon monoxide are measured. On the basis of these measurements, mass flow and rate of heat release are calculated. The rate of heat release is calculated according to the oxygen consumption principle. The upper limit for measurements is approximately 10 MW and the lower is 0.1 MW.

An original valveless artificial heart providing pulsatile flow tested in mock circulatory loops.

PubMed

Tozzi, Piergiorgio; Maertens, Audrey; Emery, Jonathan; Joseph, Samuel; Kirsch, Matthias; Avellan, François

2017-11-24

We present the test bench results of a valveless total artificial heart that is potentially compatible with the pediatric population. The RollingHeart is a valveless volumetric pump generating pulsatile flow. It consists of a single spherical cavity divided into 4 chambers by 2 rotating disks. The combined rotations of both disks produce changes in the volumes of the 4 cavities (suction and ejection). The blood enters/exits the spherical cavity through 4 openings that are symmetrical to the fixed rotation axis of the first disk.Mock circulatory system: The device pumps a 37% glycerin solution through 2 parallel circuits, simulating the pulmonary and systemic circulations. Flow rates are acquired with a magnetic inductive flowmeter, while pressure sensors collect pressure in the left and right outflow and inflow tracts.In vitro test protocol: The pump is run at speeds ranging from 20 to 180 ejections per minute. The waveform of the pressure generated at the inflow and outflow of the 4 chambers and the flow rate in the systemic circulation are measured. At an ejection rate of 178 min-1, the RollingHeart pumps 5.3 L/min for a systemic maximal pressure gradient of 174 mmHg and a pulmonary maximal pressure gradient of 75 mmHg. The power input was 14 W, corresponding to an efficiency of 21%. The RollingHeart represents a new approach in the domain of total artificial heart. This preliminary study endorses the feasibility of a single valveless device acting as a total artificial heart.

Thirty Stage Annular Centrifugal Contactor Thermal Profile Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

David H. Meikrantz; Troy G. Garn; Jack D. Law

2010-02-01

A thirty stage 5 cm annular centrifugal contactor cascade has been assembled and tested to obtain thermal profiles during both ambient and heated input conditions of operation. Thermocouples were installed on every stage as well as feed inputs and Real-time data was taken during experiments lasting from two to eight hours at total flow rates of 0.5 to 1.4 liters per minute. Ambient temperature profile results show that only a small amount of heat is generated by the mechanical energy of the contactors. Steady state temperature profiles mimic the ambient temperature of the lab but are higher toward the middlemore » of the cascade. Heated inlet solutions gave temperature profiles with smaller temperature gradients, more driven by the temperature of the inlet solutions than ambient lab temperature. Temperature effects of solution mixing, even at rotor speeds of 4000 rpm, were not measurable.« less

Developing Emergency Room Key Performance Indicators: What to Measure and Why Should We Measure It?

PubMed

Khalifa, Mohamed; Zabani, Ibrahim

2016-01-01

Emergency Room (ER) performance has been a timely topic for both healthcare practitioners and researchers. King Faisal Specialist Hospital and Research Center, Saudi Arabia worked on developing a comprehensive set of KPIs to monitor, evaluate and improve the performance of the ER. A combined approach using quantitative and qualitative methods was used to collect and analyze the data. 34 KPIs were developed and sorted into the three components of the ER patient flow model; input, throughput and output. Input indicators included number and acuity of ER patients, patients leaving without being seen and revisit rates. Throughput indicators included number of active ER beds, ratio of ER patients to ER staff and the length of stay including waiting time and treatment time. The turnaround time of supportive services, such as lab, radiology and medications, were also included. Output indicators include boarding time and available hospital beds, ICU beds and patients waiting for admission.

Microbial Source Module (MSM): Documenting the Science ...

EPA Pesticide Factsheets

The Microbial Source Module (MSM) estimates microbial loading rates to land surfaces from non-point sources, and to streams from point sources for each subwatershed within a watershed. A subwatershed, the smallest modeling unit, represents the common basis for information consumed and produced by the MSM which is based on the HSPF (Bicknell et al., 1997) Bacterial Indicator Tool (EPA, 2013b, 2013c). Non-point sources include numbers, locations, and shedding rates of domestic agricultural animals (dairy and beef cows, swine, poultry, etc.) and wildlife (deer, duck, raccoon, etc.). Monthly maximum microbial storage and accumulation rates on the land surface, adjusted for die-off, are computed over an entire season for four land-use types (cropland, pasture, forest, and urbanized/mixed-use) for each subwatershed. Monthly point source microbial loadings to instream locations (i.e., stream segments that drain individual sub-watersheds) are combined and determined for septic systems, direct instream shedding by cattle, and POTWs/WWTPs (Publicly Owned Treatment Works/Wastewater Treatment Plants). The MSM functions within a larger modeling system that characterizes human-health risk resulting from ingestion of water contaminated with pathogens. The loading estimates produced by the MSM are input to the HSPF model that simulates flow and microbial fate/transport within a watershed. Microbial counts within recreational waters are then input to the MRA-IT model (Soller et

Hydrogeology of well-field areas near Tampa, Florida; Phase 2, development and documentation of a quasi-three-dimensional finite-difference model for simulation of steady-state ground-water flow

USGS Publications Warehouse

Hutchinson, C.B.

1984-01-01

This report describes a quasi-three-dimensional finite-difference model for simulation of steady-state ground-water flow in the Floridan aquifer over a 932-square-mile area that contains 10 municipal well fields. The over-lying surficial aquifer contains a water table and is coupled to the Floridan aquifer by leakage term that represents flow through a confining layer separating the two aquifers. Under the steady-state condition, all storage terms are set to zero. Use of the head-controlled flux condition allows simulated head and flow changes to occur in the Floridan aquifer at the model boundaries. Procedures used to calibrate the model, test its sensitivity to input-parameter errors, and validate its accuracy for predictive purposes are described. Also included are attachments that describe setting up and running the model. Example model-interrogation runs show anticipated drawdowns under high, average, and low recharge conditions with 10 well fields pumping simultaneously at the maximum annual permitted rates totaling 186.9 million gallons per day. (USGS)

Long-term changes in river system hydrology in Texas

NASA Astrophysics Data System (ADS)

Zhang, Yiwen; Wurbs, Ralph

2018-06-01

Climate change and human actives are recognized as a topical issue that change long-term water budget, flow-frequency, and storage-frequency characteristics of different river systems. Texas is characterized by extreme hydrologic variability both spatially and temporally. Meanwhile, population and economic growth and accompanying water resources development projects have greatly impacted river flows throughout Texas. The relative effects of climate change, water resources development, water use, and other factors on long-term changes in river flow, reservoir storage, evaporation, water use, and other components of the water budgets of different river basins of Texas have been simulated in this research using the monthly version of the Water Rights Analysis Package (WRAP) modelling system with input databases sets from the Texas Commission on Environmental Quality (TCEQ) and Texas Water Development Board (TWDB). The results show that long-term changes are minimal from analysis monthly precipitation depths. Evaporation rates vary greatly seasonally and for much of the state appear to have a gradually upward trend. River/reservoir system water budgets and river flow characteristics have changed significantly during the past 75 years in response to water resources development and use.

Balanced Synaptic Input Shapes the Correlation between Neural Spike Trains

PubMed Central

Litwin-Kumar, Ashok; Oswald, Anne-Marie M.; Urban, Nathaniel N.; Doiron, Brent

2011-01-01

Stimulus properties, attention, and behavioral context influence correlations between the spike times produced by a pair of neurons. However, the biophysical mechanisms that modulate these correlations are poorly understood. With a combined theoretical and experimental approach, we show that the rate of balanced excitatory and inhibitory synaptic input modulates the magnitude and timescale of pairwise spike train correlation. High rate synaptic inputs promote spike time synchrony rather than long timescale spike rate correlations, while low rate synaptic inputs produce opposite results. This correlation shaping is due to a combination of enhanced high frequency input transfer and reduced firing rate gain in the high input rate state compared to the low state. Our study extends neural modulation from single neuron responses to population activity, a necessary step in understanding how the dynamics and processing of neural activity change across distinct brain states. PMID:22215995

A combined PHREEQC-2/parallel fracture model for the simulation of laminar/non-laminar flow and contaminant transport with reactions

NASA Astrophysics Data System (ADS)

Masciopinto, Costantino; Volpe, Angela; Palmiotta, Domenico; Cherubini, Claudia

2010-09-01

A combination of a parallel fracture model with the PHREEQC-2 geochemical model was developed to simulate sequential flow and chemical transport with reactions in fractured media where both laminar and turbulent flows occur. The integration of non-laminar flow resistances in one model produced relevant effects on water flow velocities, thus improving model prediction capabilities on contaminant transport. The proposed conceptual model consists of 3D rock-blocks, separated by horizontal bedding plane fractures with variable apertures. Particle tracking solved the transport equations for conservative compounds and provided input for PHREEQC-2. For each cluster of contaminant pathways, PHREEQC-2 determined the concentration for mass-transfer, sorption/desorption, ion exchange, mineral dissolution/precipitation and biodegradation, under kinetically controlled reactive processes of equilibrated chemical species. Field tests have been performed for the code verification. As an example, the combined model has been applied to a contaminated fractured aquifer of southern Italy in order to simulate the phenol transport. The code correctly fitted the field available data and also predicted a possible rapid depletion of phenols as a result of an increased biodegradation rate induced by a simulated artificial injection of nitrates, upgradient to the sources.

Estimating Aeroheating of a 3D Body Using a 2D Flow Solver

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Brykina, Irina G.

2005-01-01

A method for rapidly estimating the aeroheating, shear stress, and other properties of hypersonic flow about a three-dimensional (3D) blunt body has been devised. First, the geometry of the body is specified in Cartesian coordinates. The surface of the body is then described by its derivatives, coordinates, and principal curvatures. Next, previously relatively simple equations are used to find, for each desired combination of angle of attack and meridional angle, a scaling factor and the shape of an equivalent axisymmetric body. These factors and equivalent shapes are entered as inputs into a previously developed computer program that solves the two-dimensional (2D) equations of flow in a non-equilibrium viscous shock layer (VSL) about an axisymmetric body. The coordinates in the output of the VSL code are transformed back to the Cartesian coordinates of the 3D body, so that computed flow quantities can be registered with locations in the 3D flow field of interest. In tests in which the 3D bodies were elliptic paraboloids, the estimates obtained by use of this method were found to agree well with solutions of 3D, finite-rate-chemistry, thin-VSL equations for a catalytic body.

Evaporation-induced gas-phase flows at selective laser melting

NASA Astrophysics Data System (ADS)

Zhirnov, I.; Kotoban, D. V.; Gusarov, A. V.

2018-02-01

Selective laser melting is the method for 3D printing from metals. A solid part is built from powder layer-by-layer. A continuum-wave laser beam scans every powder layer to fuse powder. The process is studied with a high-speed CCD camera at the frame rate of 104 fps and the resolution up to 5 µm per pixel. Heat transfer and evaporation in the laser-interaction zone are numerically modeled. Droplets are ejected from the melt pool in the direction around the normal to the melt surface and the powder particles move in the horizontal plane toward the melt pool. A vapor jet is observed in the direction of the normal to the melt surface. The velocities of the droplets, the powder particles, and the jet flow and the mass loss due to evaporation are measured. The gas flow around the vapor jet is calculated by Landau's model of submerged jet. The measured velocities of vapor, droplets, and powder particles correlate with the calculated flow field. The obtained results show the importance of evaporation and the flow of the vapor and the ambient gas. These gas-dynamic phenomena can explain the formation of the denudated zones and the instability at high-energy input.

Electro-osmotic flow of a model electrolyte

NASA Astrophysics Data System (ADS)

Zhu, Wei; Singer, Sherwin J.; Zheng, Zhi; Conlisk, A. T.

2005-04-01

Electro-osmotic flow is studied by nonequilibrium molecular dynamics simulations in a model system chosen to elucidate various factors affecting the velocity profile and facilitate comparison with existing continuum theories. The model system consists of spherical ions and solvent, with stationary, uniformly charged walls that make a channel with a height of 20 particle diameters. We find that hydrodynamic theory adequately describes simple pressure-driven (Poiseuille) flow in this model. However, Poisson-Boltzmann theory fails to describe the ion distribution in important situations, and therefore continuum fluid dynamics based on the Poisson-Boltzmann ion distribution disagrees with simulation results in those situations. The failure of Poisson-Boltzmann theory is traced to the exclusion of ions near the channel walls resulting from reduced solvation of the ions in that region. When a corrected ion distribution is used as input for hydrodynamic theory, agreement with numerical simulations is restored. An analytic theory is presented that demonstrates that repulsion of the ions from the channel walls increases the flow rate, and attraction to the walls has the opposite effect. A recent numerical study of electro-osmotic flow is reanalyzed in the light of our findings, and the results conform well to our conclusions for the model system.

Possible effects of depolarizing GABAA conductance on the neuronal input-output relationship: a modeling study.

PubMed

Morita, Kenji; Tsumoto, Kunichika; Aihara, Kazuyuki

2005-06-01

Recent in vitro experiments revealed that the GABAA reversal potential is about 10 mV higher than the resting potential in mature mammalian neocortical pyramidal cells; thus GABAergic inputs could have facilitatory, rather than inhibitory, effects on action potential generation under certain conditions. However, how the relationship between excitatory input conductances and the output firing rate is modulated by such depolarizing GABAergic inputs under in vivo circumstances has not yet been understood. We examine herewith the input-output relationship in a simple conductance-based model of cortical neurons with the depolarized GABAA reversal potential, and show that a tonic depolarizing GABAergic conductance up to a certain amount does not change the relationship between a tonic glutamatergic driving conductance and the output firing rate, whereas a higher GABAergic conductance prevents spike generation. When the tonic glutamatergic and GABAergic conductances are replaced by in vivo-like highly fluctuating inputs, on the other hand, the effect of depolarizing GABAergic inputs on the input-output relationship critically depends on the degree of coincidence between glutamatergic input events and GABAergic ones. Although a wide range of depolarizing GABAergic inputs hardly changes the firing rate of a neuron driven by noncoincident glutamatergic inputs, a certain range of these inputs considerably decreases the firing rate if a large number of driving glutamatergic inputs are coincident with them. These results raise the possibility that the depolarized GABAA reversal potential is not a paradoxical mystery, but is instead a sophisticated device for discriminative firing rate modulation.

Material flows generated by pyromet copper smelting

USGS Publications Warehouse

Goonan, T.G.

2005-01-01

Copper production through smelting generates large volumes of material flows. As copper contained in ore becomes copper contained in concentrate to be fed into the smelting process, it leaves behind an altered landscape, sometimes mine waste, and always mill tailings. Copper concentrate, fluxing materials, fuels, oxygen, recyclables, scrap and water are inputs to the process. Dust (recycled), gases - containing carbon dioxide (CO2) (dissipated) and sulfur dioxide (SO2) (mostly collected, transformed and sold) and slag (discarded or sold) - are among the significant process outputs. This article reports estimates of the flows of these input/output materials for a particular set of smelters studied in some countries.

Computer input and output files associated with ground-water-flow simulations of the Albuquerque Basin, central New Mexico, 1901-94, with projections to 2020; (supplement one to U.S. Geological Survey Water-resources investigations report 94-4251)

USGS Publications Warehouse

Kernodle, J.M.

1996-01-01

This report presents the computer input files required to run the three-dimensional ground-water-flow model of the Albuquerque Basin, central New Mexico, documented in Kernodle and others (Kernodle, J.M., McAda, D.P., and Thorn, C.R., 1995, Simulation of ground-water flow in the Albuquerque Basin, central New Mexico, 1901-1994, with projections to 2020: U.S. Geological Survey Water-Resources Investigations Report 94-4251, 114 p.). Output files resulting from the computer simulations are included for reference.

Inhibition of the active lymph pump by flow in rat mesenteric lymphatics and thoracic duct

NASA Technical Reports Server (NTRS)

Gashev, Anatoliy A.; Davis, Michael J.; Zawieja, David C.; Delp, M. D. (Principal Investigator)

2002-01-01

There are only a few reports of the influence of imposed flow on an active lymph pump under conditions of controlled intraluminal pressure. Thus, the mechanisms are not clearly defined. Rat mesenteric lymphatics and thoracic ducts were isolated, cannulated and pressurized. Input and output pressures were adjusted to impose various flows. Lymphatic systolic and diastolic diameters were measured and used to determine contraction frequency and pump flow indices. Imposed flow inhibited the active lymph pump in both mesenteric lymphatics and in the thoracic duct. The active pump of the thoracic duct appeared more sensitive to flow than did the active pump of the mesenteric lymphatics. Imposed flow reduced the frequency and amplitude of the contractions and accordingly the active pump flow. Flow-induced inhibition of the active lymph pump followed two temporal patterns. The first pattern was a rapidly developing inhibition of contraction frequency. Upon imposition of flow, the contraction frequency immediately fell and then partially recovered over time during continued flow. This effect was dependent on the magnitude of imposed flow, but did not depend on the direction of flow. The effect also depended upon the rate of change in the direction of flow. The second pattern was a slowly developing reduction of the amplitude of the lymphatic contractions, which increased over time during continued flow. The inhibition of contraction amplitude was dependent on the direction of the imposed flow, but independent of the magnitude of flow. Nitric oxide was partly but not completely responsible for the influence of flow on the mesenteric lymph pump. Exposure to NO mimicked the effects of flow, and inhibition of the NO synthase by N (G)-monomethyl-L-arginine attenuated but did not completely abolish the effects of flow.

Complex Catchment Processes that Control Stream Nitrogen and Organic Matter Concentrations in a Northeastern USA Upland Catchment

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Shanley, J. B.; Pellerin, B.; Saraceno, J.; Aiken, G. R.; Boyer, E. W.; Doctor, D. H.; Kendall, C.

2009-05-01

There is a need to understand the coupled biogeochemical and hydrological processes that control stream hydrochemistry in upland forested catchments. At watershed 9 (W-9) of the Sleepers River Research Watershed in the northeastern USA, we use high-frequency sampling, environmental tracers, end-member mixing analysis, and stream reach mass balances to understand dynamic factors affect forms and concentrations of nitrogen and organic matter in streamflow. We found that rates of stream nitrate processing changed during autumn baseflow and that up to 70% of nitrate inputs to a stream reach were retained. At the same time, the stream reach was a net source of the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) fractions of dissolved organic matter (DOM). The in-stream nitrate loss and DOM gains are examples of hot moments of biogeochemical transformations during autumn when deciduous litter fall increases DOM availability. As hydrological flowpaths changed during rainfall events, the sources and transformations of nitrate and DOM differed from baseflow. For example, during storm flow we measured direct inputs of unprocessed atmospheric nitrate to streams that were as large as 30% of the stream nitrate loading. At the same time, stream DOM composition shifted to reflect inputs of reactive organic matter from surficial upland soils. The transport of atmospheric nitrate and reactive DOM to streams underscores the importance of quantifying source variation during short-duration stormflow events. Building upon these findings we present a conceptual model of interacting ecosystem processes that control the flow of water and nutrients to streams in a temperate upland catchment.

Long term (1997-2014) spatial and temporal variations in nitrogen in Dongting Lake, China

PubMed Central

Tian, Zebin; Zheng, Binghui; Wang, Lijing; Li, Liqiang; Wang, Xing; Li, Hong; Norra, Stefan

2017-01-01

In order to protect the water quality of Dongting Lake, it is significant to find out its nitrogen pollution characteristics. Using long-term monthly to seasonally data (1997–2014), we investigated the spatial and temporal variations in nitrogen in Dongting Lake, the second largest freshwater lake in China. The average concentrations of total nitrogen (TN) in the eastern, southern, and western parts of the lake were 1.77, 1.56, and 1.35 mg/L, respectively, in 2014. TN pollution was generally worse in the southern area than in the western area. Concentrations showed temporal variation, and were significantly higher during the dry season than during the wet season. Based on the concentration and growth rate of TN, three different stages were identified in the long term lake data, from 1997 to 2002, from 2003 to 2008, and from 2009 to 2014, during which the concentrations and the growth rate ranged from 1.09–1.51 mg/L and 22.09%-40.03%, 1.05–1.57 mg/L and -9.05%-7.74%, and 1.68–2.02 mg/L and 57.99%-60.41%, respectively. The main controls on the lake water TN concentrations were the quality and quantity of the lake inflows, spatial and temporal variations in hydrodynamic conditions within the lake (flow velocity, flow direction), and point and nonpoint inputs from human activities. Diffuse nutrient losses from agricultural land are a significant contributor. As a priority, the local government should aim to control the pollutant inputs from upstream and non-point nutrient losses from land. PMID:28166245

Development of Compact Ozonizer with High Ozone Output by Pulsed Power

NASA Astrophysics Data System (ADS)

Tanaka, Fumiaki; Ueda, Satoru; Kouno, Kanako; Sakugawa, Takashi; Akiyama, Hidenori; Kinoshita, Youhei

Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

The NATA code; theory and analysis. Volume 2: User's manual

NASA Technical Reports Server (NTRS)

Bade, W. L.; Yos, J. M.

1975-01-01

The NATA code is a computer program for calculating quasi-one-dimensional gas flow in axisymmetric nozzles and rectangular channels, primarily to describe conditions in electric archeated wind tunnels. The program provides solutions based on frozen chemistry, chemical equilibrium, and nonequilibrium flow with finite reaction rates. The shear and heat flux on the nozzle wall are calculated and boundary layer displacement effects on the inviscid flow are taken into account. The program contains compiled-in thermochemical, chemical kinetic and transport cross section data for high-temperature air, CO2-N2-Ar mixtures, helium, and argon. It calculates stagnation conditions on axisymmetric or two-dimensional models and conditions on the flat surface of a blunt wedge. Included in the report are: definitions of the inputs and outputs; precoded data on gas models, reactions, thermodynamic and transport properties of species, and nozzle geometries; explanations of diagnostic outputs and code abort conditions; test problems; and a user's manual for an auxiliary program (NOZFIT) used to set up analytical curvefits to nozzle profiles.

Dynamics of face and annular seals with two-phase flow

NASA Technical Reports Server (NTRS)

Hughes, William F.; Basu, Prithwish; Beatty, Paul A.; Beeler, Richard M.; Lau, Stephen

1988-01-01

A detailed study was made of face and annular seals under conditions where boiling, i.e., phase change of the leaking fluid, occurs within the seal. Many seals operate in this mode because of flashing due to pressure drop and/or heat input from frictional heating. Some of the distinctive behavior characteristics of two phase seals are discussed, particularly their axial stability. The main conclusions are that seals with two phase flow may be unstable if improperly balanced. Detailed theoretical analyses of low (laminar) and high (turbulent) leakage seals are presented along with computer codes, parametric studies, and in particular a simplified PC based code that allows for rapid performance prediction: calculations of stiffness coefficients, temperature and pressure distributions, and leakage rates for parallel and coned face seals. A simplified combined computer code for the performance prediction over the laminar and turbulent ranges of a two phase flow is described and documented. The analyses, results, and computer codes are summarized.

Design and evaluation of a flow-to-frequency converter circuit with thermal feedback

NASA Astrophysics Data System (ADS)

Pawlowski, Eligiusz

2017-05-01

A novel thermal flow sensor with a frequency output is presented. The sensor provides a pulse-train output whose frequency is related to the fluid flow rate around a self-heating thermistor. The integrating properties of the temperature sensor have been used, which allowed for realization of the pulse frequency modulator with a thermal feedback loop, stabilizing the temperature of the sensor placed in the flowing medium. The system assures a balance of the amount of heat supplied in the impulses to the sensor and the heat given up by the sensor in a continuous way to the flowing medium. Therefore the frequency of output pulse-train is proportional to the medium flow velocity around the sensor. The special feature of the presented solution is the total integration of the thermal sensor with the measurement signal conditioning system. i.e. the sensor and conditioning system are not separate elements of the measurement circuit, but constitute a whole in the form of a thermal heat-balance mode flow-to-frequency converter. The frequency signal from the converter may be directly connected to the microprocessor digital input, which with use of the standard built-in counters may convert the frequency into a numerical value of high precision. The sensor has been experimentally characterized as a function of the average flow velocity of air at room temperature.

Guide to Flow Measurement for Electric Propulsion Systems

NASA Technical Reports Server (NTRS)

Frieman, Jason D.; Walker, Mitchell L. R.; Snyder, Steve

2013-01-01

In electric propulsion (EP) systems, accurate measurement of the propellant mass flow rate of gas or liquid to the thruster and external cathode is a key input in the calculation of thruster efficiency and specific impulse. Although such measurements are often achieved with commercial mass flow controllers and meters integrated into propellant feed systems, the variability in potential propellant options and flow requirements amongst the spectrum of EP power regimes and devices complicates meter selection, integration, and operation. At the direction of the Committee on Standards for Electric Propulsion Testing, a guide was jointly developed by members of the electric propulsion community to establish a unified document that contains the working principles, methods of implementation and analysis, and calibration techniques and recommendations on the use of mass flow meters in laboratory and spacecraft electric propulsion systems. The guide is applicable to EP devices of all types and power levels ranging from microthrusters to high-power ion engines and Hall effect thrusters. The establishment of a community standard on mass flow metering will help ensure the selection of the proper meter for each application. It will also improve the quality of system performance estimates by providing comprehensive information on the physical phenomena and systematic errors that must be accounted for during the analysis of flow measurement data. This paper will outline the standard methods and recommended practices described in the guide titled "Flow Measurement for Electric Propulsion Systems."

Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE)

NASA Technical Reports Server (NTRS)

Ruff, Gary A.; Berkowitz, Brian M.

1990-01-01

LEWICE is an ice accretion prediction code that applies a time-stepping procedure to calculate the shape of an ice accretion. The potential flow field is calculated in LEWICE using the Douglas Hess-Smith 2-D panel code (S24Y). This potential flow field is then used to calculate the trajectories of particles and the impingement points on the body. These calculations are performed to determine the distribution of liquid water impinging on the body, which then serves as input to the icing thermodynamic code. The icing thermodynamic model is based on the work of Messinger, but contains several major modifications and improvements. This model is used to calculate the ice growth rate at each point on the surface of the geometry. By specifying an icing time increment, the ice growth rate can be interpreted as an ice thickness which is added to the body, resulting in the generation of new coordinates. This procedure is repeated, beginning with the potential flow calculations, until the desired icing time is reached. The operation of LEWICE is illustrated through the use of five examples. These examples are representative of the types of applications expected for LEWICE. All input and output is discussed, along with many of the diagnostic messages contained in the code. Several error conditions that may occur in the code for certain icing conditions are identified, and a course of action is recommended. LEWICE has been used to calculate a variety of ice shapes, but should still be considered a research code. The code should be exercised further to identify any shortcomings and inadequacies. Any modifications identified as a result of these cases, or of additional experimental results, should be incorporated into the model. Using it as a test bed for improvements to the ice accretion model is one important application of LEWICE.

Ambient and potential denitrification rates in marsh soils of Northeast Creek and Bass Harbor Marsh watersheds, Mount Desert Island, Maine

USGS Publications Warehouse

Huntington, Thomas G.; Culbertson, Charles W.; Duff, John H.

2012-01-01

Nutrient enrichment from atmospheric deposition, agricultural activities, wildlife, and domestic sources is a concern at Acadia National Park on Mount Desert Island, Maine, because of the potential problems of degradation of water quality and eutrophication in estuaries. Degradation of water quality has been observed at Bass Harbor Marsh estuary in the park but only minimally in Northeast Creek estuary. Previous studies at Acadia National Park have estimated nutrient inputs to estuaries from atmospheric deposition and surface-water runoff, and have identified shallow groundwater as an additional potential source of nutrients. Previous studies at Acadia National Park have assumed that a certain fraction of the nitrogen input was removed through microbial denitrification, but rates of denitrification (natural or maximum potential) in marsh soils have not been determined. The U.S. Geological Survey, in cooperation with Acadia National Park, measured in-place denitrification rates in marsh soils in Northeast Creek and in Bass Harbor Marsh watersheds during summer 2008 and summer 2009. Denitrification was measured under ambient conditions as well as after additions of inorganic nitrogen and glucose. In-place denitrification rates under ambient conditions were similar to those reported for other coastal wetlands, although they were generally lower than those reported for salt marshes having high ambient concentrations of nitrate (NO3). Denitrification rates generally increased by at least an order of magnitude following NO3 additions, with or without glucose (as the carbohydrate) additions, compared with the ambient treatments that received no nutrient additions. The treatment that added both glucose and NO3 resulted in a variety of denitrification responses when compared with the addition of NO3 alone. In most cases, the addition of glucose to a given rate of NO3 addition resulted in higher rates of denitrification. These variable responses indicate that the amount of labile carbohydrates can limit denitrification even if NO3 is present. For most sites in both watersheds, the maximum denitrification rates ranged from of 150 to 900 micromoles of nitrous oxide per square meter per hour. These rates were equivalent to the release of 37 to 221 grams of nitrogen per square meter per year. Weak positive correlations were observed for soil temperature and for measured ammonium concentration in groundwater. Weak negative correlations were observed between denitrification rate and water level and specific conductance. The rates of denitrification in Bass Harbor Marsh and Northeast Creek under ambient conditions, both of which were relatively low, indicate that NO3 availability is low in both systems. It is evident from the addition of combined treatments of NO3 and glucose that these marsh soils are capable of comparatively high rates of denitrification, therefore, estuarine eutrophication is not a result of nitrogen inputs to marsh soils that are in excess of the denitrification capacity in these systems. If terrestrial inputs to the estuary are the cause of the observed eutrophic condition in Bass Harbor Marsh, then these inputs to the estuary must bypass the marsh in channelized surface flow, or perhaps they circumvent the marsh in shallow groundwater seepage along subsurface pathways that enter the estuary directly.

Influence of liquid-volume and airflow rates on spray application quality and homogeneity in super-intensive olive tree canopies.

PubMed

Miranda-Fuentes, Antonio; Rodríguez-Lizana, Antonio; Gil, Emilio; Agüera-Vega, J; Gil-Ribes, Jesús A

2015-12-15

Olive is a key crop in Europe, especially in countries around the Mediterranean Basin. Optimising the parameters of a spray is essential for sustainable pesticide use, especially in high-input systems, such as the super-intensive hedgerow system. Parameters may be optimised by adjusting the applied volume and airflow rate of sprays, in addition to the liquid to air proportion and the relationship between air velocity and airflow rate. Two spray experiments using a commercial airblast sprayer were conducted in a super-intensive orchard to study how varying the liquid volume rate (testing volumes of 182, 619, and 1603 l ha(-1)) and volumetric airflow rate (with flow rates of 11.93, 8.90, and 6.15 m(3) s(-1)) influences the coverage parameters and the amount and distribution of deposits in different zones of the canopy.. Our results showed that an increase in the application volume raised the mean deposit and percentage coverage, but decreased the application efficiency, spray penetration, and deposit homogeneity. Furthermore, we found that the volumetric airflow rate had a lower influence on the studied parameters than the liquid volume; however, an increase in the airflow rate improved the application efficiency and homogeneity to a certain threshold, after which the spray quality decreased. This decrease was observed in the high-flow treatment. Our results demonstrate that intermediate liquid volume rates and volumetric airflow rates are required for the optimal spraying of pesticides on super-intensive olive crops, and would reduce current pollution levels. Copyright © 2015 Elsevier B.V. All rights reserved.

Dual control active superconductive devices

DOEpatents

Martens, Jon S.; Beyer, James B.; Nordman, James E.; Hohenwarter, Gert K. G.

1993-07-20

A superconducting active device has dual control inputs and is constructed such that the output of the device is effectively a linear mix of the two input signals. The device is formed of a film of superconducting material on a substrate and has two main conduction channels, each of which includes a weak link region. A first control line extends adjacent to the weak link region in the first channel and a second control line extends adjacent to the weak link region in the second channel. The current flowing from the first channel flows through an internal control line which is also adjacent to the weak link region of the second channel. The weak link regions comprise small links of superconductor, separated by voids, through which the current flows in each channel. Current passed through the control lines causes magnetic flux vortices which propagate across the weak link regions and control the resistance of these regions. The output of the device taken across the input to the main channels and the output of the second main channel and the internal control line will constitute essentially a linear mix of the two input signals imposed on the two control lines. The device is especially suited to microwave applications since it has very low input capacitance, and is well suited to being formed of high temperature superconducting materials since all of the structures may be formed coplanar with one another on a substrate.

Methods for freshwater riverine input into regional ocean models

NASA Astrophysics Data System (ADS)

Herzfeld, M.

2015-06-01

The input of freshwater at the coast in regional models is a non-trivial exercise that has been studied extensively in the past. Several issues are of relevance; firstly, estuaries process water properties along their length, so that while freshwater may enter at the estuary head, it is no longer fresh at the mouth. Secondly, models create a numerical response that results in excessive upstream or offshore transport compared to what is typically observed. The cause of this has been traced to the lack of landward flow at the coast where freshwater is input. In this study we assess the performance of various methods of freshwater input in coarse resolution regional models where the estuary cannot be explicitly resolved, and present a formulation that attempts to account for upstream flow in the salt wedge and in-estuary mixing that elevates salinity at the mouth.

Automated method for relating regional pulmonary structure and function: integration of dynamic multislice CT and thin-slice high-resolution CT

NASA Astrophysics Data System (ADS)

Tajik, Jehangir K.; Kugelmass, Steven D.; Hoffman, Eric A.

1993-07-01

We have developed a method utilizing x-ray CT for relating pulmonary perfusion to global and regional anatomy, allowing for detailed study of structure to function relationships. A thick slice, high temporal resolution mode is used to follow a bolus contrast agent for blood flow evaluation and is fused with a high spatial resolution, thin slice mode to obtain structure- function detail. To aid analysis of blood flow, we have developed a software module, for our image analysis package (VIDA), to produce the combined structure-function image. Color coded images representing blood flow, mean transit time, regional tissue content, regional blood volume, regional air content, etc. are generated and imbedded in the high resolution volume image. A text file containing these values along with a voxel's 3-D coordinates is also generated. User input can be minimized to identifying the location of the pulmonary artery from which the input function to a blood flow model is derived. Any flow model utilizing one input and one output function can be easily added to a user selectable list. We present examples from our physiologic based research findings to demonstrate the strengths of combining dynamic CT and HRCT relative to other scanning modalities to uniquely characterize pulmonary normal and pathophysiology.

Investigation of micromixing by acoustically oscillated sharp-edges

PubMed Central

Nama, Nitesh; Huang, Po-Hsun; Huang, Tony Jun; Costanzo, Francesco

2016-01-01

Recently, acoustically oscillated sharp-edges have been utilized to achieve rapid and homogeneous mixing in microchannels. Here, we present a numerical model to investigate acoustic mixing inside a sharp-edge-based micromixer in the presence of a background flow. We extend our previously reported numerical model to include the mixing phenomena by using perturbation analysis and the Generalized Lagrangian Mean (GLM) theory in conjunction with the convection-diffusion equation. We divide the flow variables into zeroth-order, first-order, and second-order variables. This results in three sets of equations representing the background flow, acoustic response, and the time-averaged streaming flow, respectively. These equations are then solved successively to obtain the mean Lagrangian velocity which is combined with the convection-diffusion equation to predict the concentration profile. We validate our numerical model via a comparison of the numerical results with the experimentally obtained values of the mixing index for different flow rates. Further, we employ our model to study the effect of the applied input power and the background flow on the mixing performance of the sharp-edge-based micromixer. We also suggest potential design changes to the previously reported sharp-edge-based micromixer to improve its performance. Finally, we investigate the generation of a tunable concentration gradient by a linear arrangement of the sharp-edge structures inside the microchannel. PMID:27158292

Turbulent kinetic energy equation and free mixing

NASA Technical Reports Server (NTRS)

Morel, T.; Torda, T. P.; Bradshaw, P.

1973-01-01

Calculation of free shear flows was carried out to investigate the usefulness of several concepts which were previously successfully applied to wall flows. The method belongs to the class of differential approaches. The turbulence is taken into account by the introduction of one additional partial differential equation, the transport equation for the turbulent shear stress. The structure of turbulence is modeled after Bradshaw et al. This model was used successfully in boundary layers and its applicability to other flows is demonstrated. The work reported differs substantially from that of an earlier attempt to use this approach for calculation of free flows. The most important difference is that the region around the center line is treated by invoking the interaction hypothesis (concerning the structure of turbulence in the regions separated by the velocity extrema). The compressibility effects on shear layer spreading at low and moderate Mach numbers were investigated. In the absence of detailed experiments in free flows, the evidence from boundary layers that at low Mach numbers the structure of turbulence is unaffected by the compressibility was relied on. The present model was tested over a range of self-preserving and developing flows including pressure gradients using identical empirical input. The dependence of the structure of turbulence on the spreading rate of the shear layer was established.

Investigation of micromixing by acoustically oscillated sharp-edges.

PubMed

Nama, Nitesh; Huang, Po-Hsun; Huang, Tony Jun; Costanzo, Francesco

2016-03-01

Recently, acoustically oscillated sharp-edges have been utilized to achieve rapid and homogeneous mixing in microchannels. Here, we present a numerical model to investigate acoustic mixing inside a sharp-edge-based micromixer in the presence of a background flow. We extend our previously reported numerical model to include the mixing phenomena by using perturbation analysis and the Generalized Lagrangian Mean (GLM) theory in conjunction with the convection-diffusion equation. We divide the flow variables into zeroth-order, first-order, and second-order variables. This results in three sets of equations representing the background flow, acoustic response, and the time-averaged streaming flow, respectively. These equations are then solved successively to obtain the mean Lagrangian velocity which is combined with the convection-diffusion equation to predict the concentration profile. We validate our numerical model via a comparison of the numerical results with the experimentally obtained values of the mixing index for different flow rates. Further, we employ our model to study the effect of the applied input power and the background flow on the mixing performance of the sharp-edge-based micromixer. We also suggest potential design changes to the previously reported sharp-edge-based micromixer to improve its performance. Finally, we investigate the generation of a tunable concentration gradient by a linear arrangement of the sharp-edge structures inside the microchannel.

The queueing perspective of asynchronous network coding in two-way relay network

NASA Astrophysics Data System (ADS)

Liang, Yaping; Chang, Qing; Li, Xianxu

2018-04-01

Asynchronous network coding (NC) has potential to improve the wireless network performance compared with a routing or the synchronous network coding. Recent researches concentrate on the optimization between throughput/energy consuming and delay with a couple of independent input flow. However, the implementation of NC requires a thorough investigation of its impact on relevant queueing systems where few work focuses on. Moreover, few works study the probability density function (pdf) in network coding scenario. In this paper, the scenario with two independent Poisson input flows and one output flow is considered. The asynchronous NC-based strategy is that a new arrival evicts a head packet holding in its queue when waiting for another packet from the other flow to encode. The pdf for the output flow which contains both coded and uncoded packets is derived. Besides, the statistic characteristics of this strategy are analyzed. These results are verified by numerical simulations.

Efficient removal of UDMH from dilute nitride MOCVD exhaust streams

NASA Astrophysics Data System (ADS)

Pahle, Jörg; Czerniak, Mike; Seeley, Andy; Baker, Derek

2004-12-01

Unsymmetrical dimethyl hydrazine (UDMH) (CH 3) 2N 2H 2 is often used in the deposition of dilute nitride semiconductors because it provides a source of nitrogen with a low thermal decomposition temperature (Temperature-dependent carrier lifetime in GaNAs using resonant-coupled photoconductive decay, NCPV Program Review Meeting, Lakewood, Colorado, 14-17 October, 2001). The problems with using this material, however, are its significant toxicity (0.01 ppm compared to ammonia's 25 ppm) and also the fact that it blocks the action of conventional dosed wet scrubbers sometimes used on nitride applications, resulting in diminished efficiency in removing arsine (the source of arsenic), and arsine being similarly toxic (TLV of 0.05 ppm). Efficient removal of UDMH, AsH 3 and hydrogen (which, though not toxic poses a potential safety hazard) by means of a combined thermal oxidation reaction and wet scrubber in series is described at input gas flow rates exceeding those typically encountered in practice. The detection technique employed was Fourier transform infra red spectroscopy (FTIR), and the calibration and resolution techniques will be described. For input UDMH flows of up to 445 sccm (i.e. 1.85×10 -2 mol/min), destructive reaction efficiencies (DREs) of >99.9% were demonstrated, corresponding to the background detection resolution of 0.4 ppm.

A data driven approach using Takagi-Sugeno models for computationally efficient lumped floodplain modelling

NASA Astrophysics Data System (ADS)

Wolfs, Vincent; Willems, Patrick

2013-10-01

Many applications in support of water management decisions require hydrodynamic models with limited calculation time, including real time control of river flooding, uncertainty and sensitivity analyses by Monte-Carlo simulations, and long term simulations in support of the statistical analysis of the model simulation results (e.g. flood frequency analysis). Several computationally efficient hydrodynamic models exist, but little attention is given to the modelling of floodplains. This paper presents a methodology that can emulate output from a full hydrodynamic model by predicting one or several levels in a floodplain, together with the flow rate between river and floodplain. The overtopping of the embankment is modelled as an overflow at a weir. Adaptive neuro fuzzy inference systems (ANFIS) are exploited to cope with the varying factors affecting the flow. Different input sets and identification methods are considered in model construction. Because of the dual use of simplified physically based equations and data-driven techniques, the ANFIS consist of very few rules with a low number of input variables. A second calculation scheme can be followed for exceptionally large floods. The obtained nominal emulation model was tested for four floodplains along the river Dender in Belgium. Results show that the obtained models are accurate with low computational cost.

Prediction of Turbulence-Generated Noise in Unheated Jets. Part 2; JeNo Users' Manual (Version 1.0)

NASA Technical Reports Server (NTRS)

Khavaran, Abbas; Wolter, John D.; Koch, L. Danielle

2009-01-01

JeNo (Version 1.0) is a Fortran90 computer code that calculates the far-field sound spectral density produced by axisymmetric, unheated jets at a user specified observer location and frequency range. The user must provide a structured computational grid and a mean flow solution from a Reynolds-Averaged Navier Stokes (RANS) code as input. Turbulence kinetic energy and its dissipation rate from a k-epsilon or k-omega turbulence model must also be provided. JeNo is a research code, and as such, its development is ongoing. The goal is to create a code that is able to accurately compute far-field sound pressure levels for jets at all observer angles and all operating conditions. In order to achieve this goal, current theories must be combined with the best practices in numerical modeling, all of which must be validated by experiment. Since the acoustic predictions from JeNo are based on the mean flow solutions from a RANS code, quality predictions depend on accurate aerodynamic input.This is why acoustic source modeling, turbulence modeling, together with the development of advanced measurement systems are the leading areas of research in jet noise research at NASA Glenn Research Center.