Stage-discharge rating curves based on satellite altimetry and modeled discharge in the Amazon basin
Paris, Adrien; Dias de Paiva, Rodrigo; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stephane; Garambois, Pierre-André; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frederique
2016-05-01
In this study, rating curves (RCs) were determined by applying satellite altimetry to a poorly gauged basin. This study demonstrates the synergistic application of remote sensing and watershed modeling to capture the dynamics and quantity of flow in the Amazon River Basin, respectively. Three major advancements for estimating basin-scale patterns in river discharge are described. The first advancement is the preservation of the hydrological meanings of the parameters expressed by Manning's equation to obtain a data set containing the elevations of the river beds throughout the basin. The second advancement is the provision of parameter uncertainties and, therefore, the uncertainties in the rated discharge. The third advancement concerns estimating the discharge while considering backwater effects. We analyzed the Amazon Basin using nearly one thousand series that were obtained from ENVISAT and Jason-2 altimetry for more than 100 tributaries. Discharge values and related uncertainties were obtained from the rain-discharge MGB-IPH model. We used a global optimization algorithm based on the Monte Carlo Markov Chain and Bayesian framework to determine the rating curves. The data were randomly allocated into 80% calibration and 20% validation subsets. A comparison with the validation samples produced a Nash-Sutcliffe efficiency (Ens) of 0.68. When the MGB discharge uncertainties were less than 5%, the Ens value increased to 0.81 (mean). A comparison with the in situ discharge resulted in an Ens value of 0.71 for the validation samples (and 0.77 for calibration). The Ens values at the mouths of the rivers that experienced backwater effects significantly improved when the mean monthly slope was included in the RC. Our RCs were not mission-dependent, and the Ens value was preserved when applying ENVISAT rating curves to Jason-2 altimetry at crossovers. The cease-to-flow parameter of our RCs provided a good proxy for determining river bed elevation. This proxy was validated
Modeling Electric Discharges with Entropy Production Rate Principles
Directory of Open Access Journals (Sweden)
Thomas Christen
2009-12-01
Full Text Available Under which circumstances are variational principles based on entropy production rate useful tools for modeling steady states of electric (gas discharge systems far from equilibrium? It is first shown how various different approaches, as Steenbeck’s minimum voltage and Prigogine’s minimum entropy production rate principles are related to the maximum entropy production rate principle (MEPP. Secondly, three typical examples are discussed, which provide a certain insight in the structure of the models that are candidates for MEPP application. It is then thirdly argued that MEPP, although not being an exact physical law, may provide reasonable model parameter estimates, provided the constraints contain the relevant (nonlinear physical effects and the parameters to be determined are related to disregarded weak constraints that affect mainly global entropy production. Finally, it is additionally conjectured that a further reason for the success of MEPP in certain far from equilibrium systems might be based on a hidden linearity of the underlying kinetic equation(s.
Predictions of Radionuclide Dose Rates from Sellafield Discharges using a Compartmental Model
Energy Technology Data Exchange (ETDEWEB)
McCubbin, D.; Leonard, K.S.; Gurbutt, P.A.; Round, G.D
1998-07-01
A multi-compartmental model (MIRMAID) of the Irish Sea has been used to predict radionuclide dose rates to the public, via seafood consumption pathways. Radionuclides originate from the authorised discharge of low level liquid effluent from the BNF plc nuclear reprocessing plant at Sellafield. The model has been used to predict combined annual doses, the contribution of dose from individual radionuclides and to discriminate dose between present day and historic discharges. An assessment has been carried out to determine the sensitivity of the predictions to changes in various model parameters. The predicted dose to the critical group from seafood consumption in 1995 ranged from 37-96 {mu}Sv of which the majority originated from current discharges. The contribution from {sup 99}Tc was predicted to have increased from 0.2% in 1993 up to 20% in 1995. The predicted contribution of Pu and Am from historic discharges is underestimated in the model. (author)
Model for charge/discharge-rate-dependent plastic flow in amorphous battery materials
Khosrownejad, S. M.; Curtin, W. A.
2016-09-01
Plastic flow is an important mechanism for relaxing stresses that develop due to swelling/shrinkage during charging/discharging of battery materials. Amorphous high-storage-capacity Li-Si has lower flow stresses than crystalline materials but there is evidence that the plastic flow stress depends on the conditions of charging and discharging, indicating important non-equilibrium aspects to the flow behavior. Here, a mechanistically-based constitutive model for rate-dependent plastic flow in amorphous materials, such as LixSi alloys, during charging and discharging is developed based on two physical concepts: (i) excess energy is stored in the material during electrochemical charging and discharging due to the inability of the amorphous material to fully relax during the charging/discharging process and (ii) this excess energy reduces the barriers for plastic flow processes and thus reduces the applied stresses necessary to cause plastic flow. The plastic flow stress is thus a competition between the time scales of charging/discharging and the time scales of glassy relaxation. The two concepts, as well as other aspects of the model, are validated using molecular simulations on a model Li-Si system. The model is applied to examine the plastic flow behavior of typical specimen geometries due to combined charging/discharging and stress history, and the results generally rationalize experimental observations.
Directory of Open Access Journals (Sweden)
Konstantinos Katsonis
2013-01-01
Full Text Available We developed a Global Model for N2O plasmas valid for applications in various power, gas flow rate, and pressure regimes. Besides energy losses from electron collisions with N2O, it takes into consideration those due to molecular N2 and O2 and to atomic N and O species. Positive atomic N+ and O+ and molecular N2O+, N2+, and O2+ have been treated as separate species and also negative O− ions. The latter confer an electronegative character to the discharge, calling for modified plasma sheath and plasma potential formulas. Electron density and temperature and all species densities have been evaluated, hence the ionization and dissociation percentages of N2O, N2, and O2 molecules and the plasma electronegativity. The model is extended to deal with N2/O2 mixtures feedings, notably with air. Rate coefficients and model results are discussed and compared with those from available theoretical and experimental work on ICP and glow discharge devices.
A model for the silver-zinc battery during high rates of discharge
Venkatraman, Murali; Van Zee, J. W.
A transient one-dimensional mathematical model is developed and used to study the performance and thermal behavior of the silver-zinc cell during discharge. The model considers the negative (zinc) electrode, separator, and positive (silver) electrode and describes the simultaneous electrochemical reactions in the positive electrode, mass transfer limitations, and heat generation. Changes in porosity and electrolyte composition due to electrochemical reactions, local reaction rates, diffusion, and migration of electrolyte are reported. Emphasis is placed on understanding the movement of the reaction front in the negative electrode during discharge and its correlation to the useful capacity of the cell. The sensitivity of this capacity to changes in the values of initial electrolyte, exchange current densities, and tortuosity are presented. It is shown that under certain conditions, in a system employing 25% KOH as the electrolyte, the useful capacity of the cell could be limited to 55.6% of its rated capacity when the discharge rate is increased from 1 C to 2 C. The temperature rise in a single cell was predicted and observed to agree with the experimental values.
Dynamic linear models to explore time-varying suspended sediment-discharge rating curves
Ahn, Kuk-Hyun; Yellen, Brian; Steinschneider, Scott
2017-06-01
This study presents a new method to examine long-term dynamics in sediment yield using time-varying sediment-discharge rating curves. Dynamic linear models (DLMs) are introduced as a time series filter that can assess how the relationship between streamflow and sediment concentration or load changes over time in response to a wide variety of natural and anthropogenic watershed disturbances or long-term changes. The filter operates by updating parameter values using a recursive Bayesian design that responds to 1 day-ahead forecast errors while also accounting for observational noise. The estimated time series of rating curve parameters can then be used to diagnose multiscale (daily-decadal) variability in sediment yield after accounting for fluctuations in streamflow. The technique is applied in a case study examining changes in turbidity load, a proxy for sediment load, in the Esopus Creek watershed, part of the New York City drinking water supply system. The results show that turbidity load exhibits a complex array of variability across time scales. The DLM highlights flood event-driven positive hysteresis, where turbidity load remained elevated for months after large flood events, as a major component of dynamic behavior in the rating curve relationship. The DLM also produces more accurate 1 day-ahead loading forecasts compared to other static and time-varying rating curve methods. The results suggest that DLMs provide a useful tool for diagnosing changes in sediment-discharge relationships over time and may help identify variability in sediment concentrations and loads that can be used to inform dynamic water quality management.
DEFF Research Database (Denmark)
Puthumana, Govindan
2017-01-01
conductivity and high strength causing it extremely difficult tomachine. Micro-Electrical Discharge Machining (Micro-EDM) is a non-conventional method that has a potential toovercome these restrictions for machining of Inconel 718. Response Surface Method (RSM) was used for modelling thetool Electrode Wear...
A self-consistent model for the discharge kinetics in a high-repetition-rate copper-vapor laser
Energy Technology Data Exchange (ETDEWEB)
Carman, R.J.; Brown, D.J.W.; Piper, J.A. (Macquarie Univ., Sydney (Australia). Centre for Lasers and Applications)
1994-08-01
A self-consistent computer model has been developed to simulate the discharge kinetics and lasing characteristics of a copper-vapor laser (CVL) for typical operating conditions. Using a detailed rate-equation analysis, the model calculates the spatio-temporal evolution of the population densities of 11 atomic and ionic copper levels, four neon levels, and includes 70 collisional and radiative processes, in addition to radial particle transport. The long-term evolution of the plasma is taken into account by integrating the set of coupled rate equations describing the discharge and electrical circuit through multiple excitation-afterglow cycles. A time-dependent two-electron group model, based on a bi-Maxwellian electron energy distribution function, has been used to evaluate the energy partitioning between the copper vapor and the neon-buffer gas. The behavior of the plasma in the cooler end regions of the discharge tube near the electrodes, where the plasma kinetics are dominated by the buffer gas, has also been modeled. Results from the model have been compared to experimental data for a narrow-bore ([phi] = 1.8 cm) CVL operating under optimum conditions.
Modeling electronegative plasma discharge
Energy Technology Data Exchange (ETDEWEB)
Lichtenberg, A.J.; Lieberman, M.A. [Univ. of California, Berkley, CA (United States)
1995-12-31
Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.
Sawdust discharge rate from aerated hoppers
Institute of Scientific and Technical Information of China (English)
Pan Chen; Zhulin Yuan; Chien-Song Chyang; Fu-Xiong Zhuan
2011-01-01
This paper presents a numerical and experimental study of the discharge rate of sawdust from an aerated hopper as an important parameter in many industrial processes involving the handling of other granular materials. Numerical experiments are conducted by means of an Eulerian-Eulerian approach coupled with the kinetic theory of granular flow (KTGF). Emphasis is given to the effects of particle size, hopper outlet width, hopper half angle, aeration height and air flow rate. The results show that the discharge rate is significantly affected by hopper outlet width, particle size and air flow rate, but is not sensitive to the hopper half angle and aeration height: increasing hopper outlet width or air flow rate increases discharge rate, while increasing particle size decreases discharge rate. Close agreement between numerical predictions and experimental results is obtained.
Granular discharge rate for submerged hoppers
Directory of Open Access Journals (Sweden)
T. J. Wilson
2014-10-01
Full Text Available The discharge of spherical grains from a hole in the bottom of a right circular cylinder is measured with the entire system underwater. We find that the discharge rate depends on filling height, in contrast to the well-known case of dry non-cohesive grains. It is further surprising that the rate increases up to about twenty five percent, as the hopper empties and the granular pressure head decreases. For deep filling, where the discharge rate is constant, we measure the behavior as a function of both grain and hole diameters. The discharge rate scale is set by the product of hole area and the terminal falling speed of isolated grains. But there is a small-hole cutoff of about two and half grain diameters, which is larger than the analogous cutoff in the Beverloo equation for dry grains. Received: 11 September 2014, Accepted: 10 October 2014; Reviewed by: L. Staron, CNRS, Universite Pierre et Marie Curie, Institut Le Rond d'Alembert, Paris, France; Edited by: L. A. Pugnaloni; DOI: http://dx.doi.org/10.4279/PIP.060009 Cite as: T J Wilson, C R Pfeifer, N Meysingier, D J Durian, Papers in Physics 6, 060009 (2014
1988-06-01
Dielectric Sensor ................................... 12 5 ESA S/N 001 ......................................... 24 6 Preliminary Test Sequence...71 28 Optical Transmission Loss of Contamination "Witness" Slide 3 .................................. 72 29 Apparatus used in FMDS Spectroscopic...Monitor ( TPU ). This sensor detects the electromagnetic pulses generated by the onset of arcing. (2) An active discharge device (plasma source). (3) A
Modelling Of Chlorine Inductive Discharges
Chabert P.; Despiau-Pujo, E.
2010-07-01
III-V compounds such as GaAs, InP or GaN-based materials are increasingly important for their use in optoelectronic applications, especially in the telecommunications and light detection industries. Photonic devices including lasers, photodetectors or LEDs, require reliable etching processes characterized by high etch rate, profile control and low damage. Although many problems remain to be understood, inductively coupled discharges seem to be promising to etch such materials, using Cl2/Ar, Cl2/N2 and Cl2/H2 gas chemistries. Inductively coupled plasma (ICP) sources meet most of the requirements for efficient plasma processing such as high etch rates, high ion densities and low controllable ion energies. However, the presence of a negative ion population in the plasma alters the positive ion flux, reduces the electron density, changes the electron temperature, modifies the spatial structure of the discharge and can cause unstable operation. Several experimental studies and numerical simulation results have been published on inductively coupled Cl2/Ar plasmas but relatively few systematic comparisons of model predictions and experimental data have been reported in given reactor geometries under a wide range of op- erating conditions. Validation of numerical predictions is essential for chemically complex plasma processing and there is a need to benchmark the models with as many measurements as possible. In this paper, comparisons of 2D fluid simulations with experimental measurements of Ar/Cl2 plasmas in a low pressure ICP reactor are reported (Corr et al. 2008). The electron density, negative ion fraction and Cl atom density are investigated for various conditions of Ar/Cl2 ratio, gas pressure and applied RF power in H mode. Simulations show that the wall recombination coefficient of Cl atom (?) is a key parameter of the model and that neutral densities are very sensitive to its variations. The best agreement between model and experiment is obtained for ? = 0
Helicon plasma thruster discharge model
Energy Technology Data Exchange (ETDEWEB)
Lafleur, T., E-mail: trevor.lafleur@lpp.polytechnique.fr [Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ Paris-Sud, Ecole Polytechnique, 91128 Palaiseau, France and ONERA - The French Aerospace Lab, 91120 Palaiseau (France)
2014-04-15
By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.
Estimating river discharge rates through remotely sensed thermal plumes
Abou Najm, M.; Alameddine, I.; Ibrahim, E.; Nasr, R.
2016-12-01
An empirical relationship is developed for estimating river discharge rates from remotely sensed thermal plumes that generate due to the temperature gradient at the interface between rivers and large water bodies. The method first determines the plumes' near field area, length scale, and length scale deviation angle from river channel centerline from Landsat 7 ETM+ satellite images. It also makes use of mean river and ocean temperatures and tidal levels collected from NOAA. A multiple linear regression model is then used to predict measured daily discharge rates with the determined predictors. The approach is tested and validated with discharge rates collected from four USGS gauged rivers in Oregon and California. Results from 116 Landsat 7 ETM+ satellites images of the four rivers show that the standard error of the discharge estimates were within a factor of 1.5-2.0 of observed values, with mean estimate accuracy of 10%. Goodness of fit (R2) ranged from 0.51 for the Rogue River up to 0.64 for the Coquille and Siuslaw rivers. The method offers an opportunity to monitor changes in flow discharge in ungauged basins, where tidal flow is not dominating and where a temperature difference of 2 oC exists between the river and the receiving water body.
Influence of Four Factors on Discharge Capacity and Self-Discharge Rate of Iron Electrode
Institute of Scientific and Technical Information of China (English)
Dongfeng LIN; Shihai YE; Rong CAI; Deying SONG; Panwen SHEN
2003-01-01
Ni-Fe rechargeable batteries possess the advantages of long cycle life, high theoretical specific energy, abundant raw material,Iow price and environmental friendship. It has a wide applied perspective. The advantages, disadvantages and preparation methods of iron electrodes were summarized. The influence of four factors on discharge capacity and self-discharge rate of iron electrode were discussed by means of orthogonal experiments, galvanostatic charges and discharges. The influences of graphite on the discharge capacity and self-discharge rate of iron electrode were the most remarkable, the most unapparent influences on the discharge capacity and self-discharge rate were HPMC (hydroxy propoxy methoxy cellulose) and sodium sulphide, respectively. The aim of the present research was to study the effects of graphite, HPMC and iron powder added in the electrodes, sodium sulphide added in the electrolytes on the discharge capacity and self-discharge rate of iron electrodes.The largest discharge capacity of the iron electrodes was 488.5 mAh/g-Fe at 66.4 mA/g-Fe in the first ten cycles, and the average self-discharge rate was 0.367% per hour.
Properties of water surface discharge at different pulse repetition rates
Energy Technology Data Exchange (ETDEWEB)
Ruma,; Yoshihara, K. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Hosseini, S. H. R., E-mail: hosseini@kumamoto-u.ac.jp; Sakugawa, T.; Akiyama, H. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Akiyama, M. [Department of Electrical and Electronic Engineering, Kagoshima University, Kagoshima 890-0065 (Japan); Lukeš, P. [Institute of Plasma Physics, AS CR, Prague, Prague 18200 (Czech Republic)
2014-09-28
The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H₂O₂) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H₂O₂ and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.
A General Thermal Equilibrium Discharge Flow Model
Institute of Scientific and Technical Information of China (English)
ZHAO; Min-fu; ZHANG; Dong-xu; LV; Yu-feng
2015-01-01
In isentropic and thermal equilibrium assumptions,a discharge flow model was derived,which unified the rules of normal temperature water discharge,high temperature and high pressure water discharge,two-phase critical flow,saturated steam and superheated steam critical
Proposed test method for determining discharge rates from water closets
DEFF Research Database (Denmark)
Nielsen, V.; Fjord Jensen, T.
At present the rates at which discharge takes place from sanitary appliances are mostly known only in the form of estimated average values. SBI has developed a measuring method enabling determination of the exact rate of discharge from a sanitary appliance as function of time. The methods depends...... on the application of a calibrated measuring vessel, the volume of water in the vessel being measured at a given moment by means of a transducer and recorded by an UV recorder which is able to follow very rapid variations. In the article the apparatus is described in detail, and an example is given...... of the measurements of the rate of discharge from a WC....
Modelling Discharge Inception in Thunderstorms
Rutjes, Casper; Dubinova, Anna; Ebert, Ute; Buitink, Stijn; Scholten, Olaf; Trinh, Gia Thi Ngoc
2015-01-01
The electric fields in thunderstorms can exceed the breakdown value locally near hydrometeors. But are fields high enough and the regions large enough to initiate a streamer discharge? And where would a sufficient density of free electrons come from to start the discharge in the humid air that rapid
Directory of Open Access Journals (Sweden)
Wei Bengang
2016-01-01
Full Text Available In this paper, the different types of discharge in transformer were simulated based on the real transformer fault model. The optical partial discharge detection system was established based on optical sensors which were capturing partial discharge accompanied by optical effects. In this research, surface discharge and suspended discharge defect model was pressurized to generate partial discharge signal. The results showed that: Partial discharge optical signals could effectively respond the production and development process of transformer partial discharge. It was able to assess discharge level also. When the discharge phenomenon stabilized, the phase of surface discharge mainly between 60°~150°and 240°~330°, the phase of suspended discharge mainly between 260°~320°. According to the phase characteristic of discharge pattern, the creeping discharge and suspended discharge phenomenon of transformer can be distinguished. It laid the foundation for the application of transformer optical partial discharge detection technology.
Extension of silo discharge model based on discrete element method
Energy Technology Data Exchange (ETDEWEB)
Oldal, Istvan; Safranyil, Ferenc [Szent Istvan University, Goedoelloe (Hungary)
2015-09-15
Silos are containers used by almost all fields of industry for storing granular materials and generally classified in two types: mass flow and funnel flow. One of the most important design parameter of these equipment is the discharge rate which depends on the flow mode. There are high numbers of analytical and empirical models used for determine this parameter, however none of them is suitable for both flow modes; moreover the accuracy of mass flow models is not acceptable. Recently a few numerical discharge models are made for certain geometries; but the applicability of these models in case of different flow modes was not examined. Aim of our work is the creation of an experimentally validated numerical discharge model based on others work and examination of this in term of different flow modes. We prove that our modified model is suitable for determine silos discharge rate independently from flow mode.
Numerical modeling of partial discharges parameters
Directory of Open Access Journals (Sweden)
Kartalović Nenad M.
2016-01-01
Full Text Available In recent testing of the partial discharges or the use for the diagnosis of insulation condition of high voltage generators, transformers, cables and high voltage equipment develops rapidly. It is a result of the development of electronics, as well as, the development of knowledge about the processes of partial discharges. The aim of this paper is to contribute the better understanding of this phenomenon of partial discharges by consideration of the relevant physical processes in isolation materials and isolation systems. Prebreakdown considers specific processes, and development processes at the local level and their impact on specific isolation material. This approach to the phenomenon of partial discharges needed to allow better take into account relevant discharge parameters as well as better numerical model of partial discharges.
Zhu, Zhecheng
2011-01-01
Beds are one of the most important resources in a healthcare system. How to manage beds efficiently is an important indicator of the efficiency of the healthcare system. Bed management is challenging to many healthcare service providers in many aspects. In recent years, population growth and aging society impose extra pressure on bed requirement. There are usually two key performance indicators of a bed management system: bed occupancy rate and bed waiting time. In this paper, different discharge patterns and their impacts on the bed occupancy rate and bed waiting time are studied. A discrete event simulation model is constructed to evaluate the existing discharge pattern in a Singapore regional hospital using actual hospital admission and discharge transaction data. Then different discharge patterns are tested in the same context. Simulation results show that a proper discharge pattern significantly smoothes the fluctuation of bed occupancy rate and reduce the bed waiting time.
Demonstration of a high repetition rate capillary discharge waveguide
Energy Technology Data Exchange (ETDEWEB)
Gonsalves, A. J., E-mail: ajgonsalves@lbl.gov; Pieronek, C.; Daniels, J.; Bulanov, S. S.; Waldron, W. L.; Mittelberger, D. E.; Leemans, W. P. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Liu, F.; Antipov, S.; Butler, J. E. [Euclid TechLabs, Gaithersburg, Maryland 20879 (United States); Bobrova, N. A.; Sasorov, P. V. [Keldysh Institute of Applied Mathematics, Moscow (Russian Federation)
2016-01-21
A hydrogen-filled capillary discharge waveguide operating at kHz repetition rates is presented for parameters relevant to laser plasma acceleration (LPA). The discharge current pulse was optimized for erosion mitigation with laser guiding experiments and MHD simulation. Heat flow simulations and measurements showed modest temperature rise at the capillary wall due to the average heat load at kHz repetition rates with water-cooled capillaries, which is promising for applications of LPAs such as high average power radiation sources.
Water Transport Models of Moisture Absorption and Sweat Discharge Yarns
Institute of Scientific and Technical Information of China (English)
WANG Fa-ming; ZHOU Xiao-hong; WANG Shan-yuan
2008-01-01
An important property of moisture absorption and sweat discharge yams is their water transport property. In the paper, two water transport models of moisture absorption and sweat discharge yams were developed to investigate the influence factors on their wicking rate. In parallel Column Pores Model, wicking rate is determined by the equivalent capillary radius R and length of the capillary tube L. In Pellets Accumulation Model, wicking rate is decided by the capillary radius r and length of the fiber unit assemble L0.
Improving transmission rates of electronic discharge summaries to GPs.
Barr, Rory; Chin, Kuen Yeow; Yeong, Keefai
2013-01-01
Discharge summaries are a vital tool to communicate information from Hospital to Primary Care teams; updating GPs about what happened during an admission, and handing over care detailing any follow up care required. Historically, Discharge Summaries have been posted to hospitals, increasing costs for hospitals, creating administrative work for GP practices receiving the letters, and resulting in some letters being lost or delayed in reaching the GP, with implications for patient safety if follow up requests are not received and acted upon. In an effort to improve patient care, the Clinical Commissioning Group in Surrey drew up a contract with Ashford and St Peter's Foundation Trust, aiming to increase the percentage of discharge summaries sent electronically from the rate of 9% sent within 24 hours, to over 75%. This contract set targets of 50% in May, 65% in June, and 80% in July. Financial penalties would be imposed if targets were not achieved, starting in June 2013. The Trust set up a working group comprising of doctors, IT personnel and ward PAs to devise a multi-pronged solution to achieve this target. The electronic discharge summary system was reviewed and improvements were designed and developed to make the process of signing off letters easier, and transmission of signed off letters became automated rather than requiring manual transmission by ward PAs. Presentations and leaflets to explain the importance of prompt completion and transmission of discharge summaries were given to Doctors to improve compliance using the revised IT system. Figures on transmission rates were automatically emailed to key stakeholders every day (Ward PAs, Divisional Leads) showing performance on each ward. This helped identify areas requiring more intervention. Areas (e.g. Day Surgery) that had not used electronic discharge summaries were engaged with, and persuaded to take part. As a result, transmission rates of Discharge Summaries within 24 hours of patient discharge
Bayesian discharge rating curves based on B-spline smoothing functions
Directory of Open Access Journals (Sweden)
K. M. Ingimarsson
2010-05-01
Full Text Available Discharge in rivers is commonly estimated by the use of a rating curve constructed from pairs of measured water elevations and discharges at a specific location. The Bayesian approach has been successfully applied to estimate discharge rating curves that are based on the standard power-law. In this paper the standard power-law model is extended by adding a B-spline function. The extended model is compared to the standard power-law model by applying the models to discharge data sets from sixty one different rivers. In addition four rivers are analyzed in detail to demonstrate the benefit of the extended model. The models are compared using two measures, the Deviance Information Criterion (DIC and Bayes factor. The former provides robust comparison of fit adjusting for the different complexity of the models and the latter measures the evidence of one model against the other. The extended model captures deviations in the data from the standard power-law but reduces to the standard power-law when that model is adequate. The extended model provides substantially better fit than the standard power-law model for about 30% of the rivers and performs better for 60% of the rivers when extrapolating large discharge values.
Disaggregation modelling of spring discharges
Directory of Open Access Journals (Sweden)
Kirilova Bojilova Elena
2004-12-01
Full Text Available Disaggregation models are basically divided into three main groups: temporal, spatial and temporal-spatial. The focus of this paper is the application of temporal disaggregation models to disaggregate the seasonal flow in some large time intervals to sub-seasonal flows in some shorter time intervals. Two basic models are applied: the original model of Mejia and Rousselle and the corrected extended Lin model one-stage disaggregation. The flow totals from some karstic springs are used. Data for five springs in different areas of Bulgaria for the aims of the study are executed. The synthetic data generation for the chosen spring stations for a new realisation of thirty years is obtained. The multi-variate lag-one auto regressive model (AR(1 model is applied for generation of the annual flow sequences. The Lin model single- site is performed for thirty years generation period. The Lin model is an improvement compared to the original extended model. The new Lin approach succeeds in the preservation of the additivity as well as the moments. Applying the Lin model one-stage disaggregation results in consistent model parameter estimates. As a second step in the research multi-site disaggregation schemes are also applied.
Jang, C. S.; Liu, C. W.
2014-12-01
The Tatun volcanic area is the only potential volcanic geothermal region in the Taiwan island, and abundant in hot spring resources owing to stream water mixing with fumarolic gases. According to the Meinzer's classification, spring temperatures and discharge rates are the most important properties for characterizing spring classifications. This study attempted to spatially characterize spring temperatures and discharge rates in the Tatun volcanic area, Taiwanusing indicator kriging (IK). First, data on spring temperatures and discharge rates, which were collected from surveyed data of the Taipei City Government, were divided into high, moderate and low categories according to spring classification criteria, and the various categories were regarded as estimation thresholds. Then, IK was adopted to model occurrence probabilities of specified temperatures and discharge rates in springs, and to determine their classifications based on estimated probabilities. Finally, nine combinations were obtained from the classifications of temperatures and discharge rates in springs. Moreover, the combinations and features of spring water were spatially quantified according to seven sub-zones of spring utilization. A suitable and sustainable development strategy of the spring area was proposed in each sub-zone based on probability-based combinations and features of spring water.The research results reveal that the probability-based classifications using IK provide an excellent insight in exploring the uncertainty of spatial features in springs, and can provide Taiwanese government administrators with detailed information on sustainable spring utilization and conservation in the overexploited spring tourism areas. The sub-zones BT (Beitou), RXY (Rd. Xingyi), ZSL (Zhongshanlou) and LSK (Lengshuikeng) with high or moderate discharge rates are suitable to supply spring water for tourism hotels.Local natural hot springs should be planned in the sub-zones DBT (Dingbeitou), ZSL, XYK
Documentation for the hydrological discharge model
Energy Technology Data Exchange (ETDEWEB)
Hagemann, S.; Duemenil, L. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany)
1998-10-01
To improve the representation of hydrological land surface processes, which has so far been treated inadequately in global models of the atmospheric general circulation (GCMs), a model for the lateral waterflows from the continents into the ocean on the global scale was developed. The model describes the translation and retention of the lateral discharge as a function of the spatially distributed land surface characteristics that are globally available. Here, global scale refers to the resolution of 0.5 and lower, corresponding to a typical GCM gridbox area of about 2500 km{sup 2}. This model is called the Hydrological Discharge model or HD model. The HD model computes the discharge only at 0.5 resolution. A model input fields (runoff and drainage, see Sect. 3.1.) from the various GCM resolutions are interpolated to the same 0.5 grid. Thus, input fields may be used from any available resolution, if the corresponding interpolation routine to the 0.5 degree grid is provided. Since the HD model uses a time step of one day, a temporal resolution of one day is sufficient for the input fields. (orig.)
Modelling of First Discharge in EAST Tokamak
Institute of Scientific and Technical Information of China (English)
LIU Chengyue; WU Bin; XIAO Bingjia; SHU Shuangbao
2008-01-01
An 1.5D equilibrium evolution code was used to model the time evolution of the first ohmic discharges in the EAST experiment. Good agreement between the simulation and the experimental results was obtained in the plasma current, major radius, electron temperature, loop voltage and poloidal field (PF) current for the entire duration of the discharge, which indicates that the code is highly reliable and will allow to further study the EAST discharge. At the same time, the code also simulates some important plasma parameters without experimental measured data yet, such as the plasma minor radius, central and edge safety factors, elongation and triangilarity, which are important in the analysis of EAST data.
A digital procedure for ground water recharge and discharge pattern recognition and rate estimation.
Lin, Yu-Feng; Anderson, Mary P
2003-01-01
A digital procedure to estimate recharge/discharge rates that requires relatively short preparation time and uses readily available data was applied to a setting in central Wisconsin. The method requires only measurements of the water table, fluxes such as stream baseflows, bottom of the system, and hydraulic conductivity to delineate approximate recharge/discharge zones and to estimate rates. The method uses interpolation of the water table surface, recharge/discharge mapping, pattern recognition, and a parameter estimation model. The surface interpolator used is based on the theory of radial basis functions with thin-plate splines. The recharge/discharge mapping is based on a mass-balance calculation performed using MODFLOW. The results of the recharge/discharge mapping are critically dependent on the accuracy of the water table interpolation and the accuracy and number of water table measurements. The recharge pattern recognition is performed with the help of a graphical user interface (GUI) program based on several algorithms used in image processing. Pattern recognition is needed to identify the recharge/discharge zonations and zone the results of the mapping method. The parameter estimation program UCODE calculates the parameter values that provide a best fit between simulated heads and flows and calibration head-and-flow targets. A model of the Buena Vista Ground Water Basin in the Central Sand Plains of Wisconsin is used to demonstrate the procedure.
Global Modeling of CO2 Discharges with Aerospace Applications
Directory of Open Access Journals (Sweden)
Chloe Berenguer
2014-01-01
Full Text Available We developed a global model aiming to study discharges in CO2 under various conditions, pertaining to a large spectrum of pressure, absorbed energy, and feeding values. Various physical conditions and form factors have been investigated. The model was applied to a case of radiofrequency discharge and to helicon type devices functioning in low and high feed conditions. In general, main charged species were found to be CO2+ for sufficiently low pressure cases and O− for higher pressure ones, followed by CO2+, CO+, and O2+ in the latter case. Dominant reaction is dissociation of CO2 resulting into CO production. Electronegativity, important for radiofrequency discharges, increases with pressure, arriving up to 3 for high flow rates for absorbed power of 250 W, and diminishes with increasing absorbed power. Model results pertaining to radiofrequency type plasma discharges are found in satisfactory agreement with those available from an existing experiment. Application to low and high flow rates feedings cases of helicon thruster allowed for evaluation of thruster functioning conditions pertaining to absorbed powers from 50 W to 1.8 kW. The model allows for a detailed evaluation of the CO2 potential to be used as propellant in electric propulsion devices.
Micro Wire Electro Discharge Grinding: Optimization of Material Removal Rate and Surface Roughness
Yeakub Ali, Mohammad; Rahman, Mohamed Abd; Nordin, Rosmarina
2017-03-01
This paper presents the analysis and modelling of material removal rate (MRR) and surface roughness (Ra) by micro wire electro discharge grinding (micro-WEDG) with control parameter of gap voltage, feed rate, and spindle speed. The data were analyzed and empirical models are developed. The optimized values of MRR and Ra are 0.051 mm3/min and 0.25 μm respectively with 110 V gap voltage, 38 μm/s feed rate, and 1315 rpm spindle speed. The analysis showed that gap voltage has significant effect on material removal rate while spindle speed has significant effect on surface roughness.
Predicting the Discharge Rate Contribution of the Binuwang Watershed to the Agos River, Philippines
Aquino, Dakila; Paningbatan, Eduardo; Mahar Francisco Lagmay, Alfredo
2014-05-01
In 2004, Typhoon Winnie brought torrential rains which triggered massive landslides and floods which devastated the provinces of Infanta, Real and General Nakar in the Philippines. Winnie inflicted USD 111.14 million worth of damage to crops, livestock and infrastructure and left thousands dead or homeless. The Binuwang River is a sub-tributary of the Agos River, but the extent to which it contributes to flooding has not yet been determined. This study measures the depth of the Binuwang River to estimate the discharge rate contribution of the Binuwang River Watershed to the Agos River using an automatic rain gauge recorder and water level loggers set to record at 5-minute intervals. Flood-generating rainfall events were monitored during the onset of Typhoon Nesat (locally called 'Pedring') September 26-27, 2011. The automated rain gauge recorded 227 mm cumulative rainfall over a 6-hour and 41-minute period. It reached a peak rainfall intensity of 17.5 mm per 5-minute interval that generated a discharge height increase of 1.8 m at the monitoring station and a total discharge volume of 99,823 m3 over a 35-hour duration. An 8.81-hour lag time from the peak rainfall to the peak discharge concentration was recorded. A PCRaster-based hydrologic model was used to predict the total discharge hydrograph of the Binuwang River Watershed. A Digital Elevation Model (DEM) and soil and land use maps were prepared to parameterize the model. The observed and predicted discharge hydrographs were found to be highly correlated. Among the parameters used to calibrate the model hydrologic output, most sensitive are the infiltration saturation coefficient and Manning's roughness coefficient. An increase in the infiltration saturation coefficient resulted in a decreased discharge height, while an increase of Manning's roughness coefficient lengthened the lag time. The predicted discharge volume and height were used to simulate the impact of reforestation and land conversion to cultivated
Self-discharge rate of lithium thionyl-chloride cells
Energy Technology Data Exchange (ETDEWEB)
Cieslak, W.R.
1993-12-31
Our low-rate lithium/thionyl-chloride ``D`` cell is required to provide power continuously for up to 10 years. The cell was designed at Sandia National Laboratories and manufactured at Eagle-Picher Industries, Joplin, Missouri. We have conducted accelerated aging studies at elevated temperatures to predict long-term performance of cells fabricated in 1992. Cells using 1.0M LiAlCl{sub 4} electrolyte follow Arrhenius kinetics with an activation energy of 14.6 Kcal/mol. This results in an annual capacity loss to self-discharge of 0.13 Ah at 25 C. Cells using a 1.0M LiAlCl{sub 4}{sm_bullet}SO{sub 2} electrolyte do not follow Arrhenius behavior. The performance of aged cells from an earlier fabrication lot is variable.
River Network Modeling Beyond Discharge at Gauges
David, C. H.; Famiglietti, J. S.; Salas, F. R.; Whiteaker, T. L.; Maidment, D. R.; Tolle, K.
2014-12-01
Over the past two decades, the estimation of water flow in river networks within hydro-meteorological models has mostly focused on simulations of natural processes and on their verification at available river gauges. Despite valuable existing skills in hydrologic modeling the accounting for anthropogenic actions in current models remains limited. The emerging availability of datasets containing measured dam outflows and reported irrigation withdrawals motivates their inclusion into simulations of flow in river networks. However, the development of advanced river network models accounting for such datasets of anthropogenic influences requires a detailed data model and a thorough handling of the various data types, sources and time scales. This contribution details the development of a consistent data model suitable for accounting some observations of anthropogenic modifications of the surface water cycle and presents the impact of such inclusion on simulations using the Routing Application for Parallel computatIon of Discharge (RAPID).
Flow of granular materials-I. Discharge rates from hoppers
Energy Technology Data Exchange (ETDEWEB)
Nedderman, R.M. (Univ. of Cambridge, England); Tuezuen, U.; Savage, S.B.; Houlsby, G.T.
1982-01-01
This was the first of a set of three review papers on the flow of granular materials. The objective of the papers was to review the published literature in these fields. Much information was drawn from a body of unpulished work represented by internal reports of the Chemical Engineering Department at Cambridge. This paper discussed the experimental results for hopper discharge rates and the correlations of these results. Then theoretical analyses that have been advanced to explain the observations were presented. Also the effects of interstitial pressure gradients were discussed, both those that arise due to deliberate pressurization of the hopper and those caused by the dilation of the flowing material. The flow of coarse, free-flowing materials through orifices seemed to have been adequately investigated experimentally and the correlation of Beverloo or minor modifications of it appeared to predict the flow rates with acceptable precision. Some difficulties were however encountered with narrow angled conical hoppers or in cases where the orifice is close to a vertical wall. The effects of an imposed gas flow were also correlated to reasonable precision at least for modest gas flow rates. Though the correlations seemed satisfactory, there was no really adequate theoretical explanations of the observations. Several theories exist that give qualitative trends in accord with obsrvation but there is no theory that can be used without empirical adjustments of the coefficients. However, with fine particles many more difficulties are encountered. 6 figures. (DP)
Study and optimization of the partial discharges in capacitor model ...
African Journals Online (AJOL)
model at different temperatures. Etude et ... undegased is measured and the effect of temperature was examined. The partial discharge ... discharges and show that the low temperature ..... Journal Exploring the Frontiers of Physics, Vol. 66 (1),.
Pal, U. N.; Kumar, M.; Tyagi, M. S.; Meena, B. L.; Khatun, H.; Sharma, A. K.
2010-02-01
Dielectric-barrier discharges (DBDs) are characterized by the presence of at least one insulating layer in contact with the discharge between two planar or cylindrical electrodes connected to an AC/pulse power supply. The dielectric layers covering the electrodes act as current limiters and prevent the transition to an arc discharge. DBDs exist usually in filamentary mode, based on the streamer nature of the discharges. The main advantage of this type of electrical discharges is that nonequilibrium and non-thermal plasma conditions can be established at atmospheric pressure. VUV/UV sources based on DBDs are considered as promising alternatives of conventional mercury-based discharge plasmas, producing highly efficient VUV/UV radiation. The experiments have been performed using two coaxial quartz double barrier DBD tubes, which are filled with Xe/Ar at different pressures. A sinusoidal voltage up to 2.4 kV peak with frequencies from 20 to 100 kHz has been applied to the discharge electrodes for the generation of microdischarges. A stable and uniform discharge is produced in the gas gap between the dielectric barrier electrodes. By comparisons of visual images and electrical waveforms, the filamentary discharges for Ar tube while homogeneous discharge for Xe tube at the same conditions have been confirmed. The electrical modeling has been carried out to understand DBD phenomenon in variation of applied voltage waveforms. The simulated discharge characteristics have been validated by the experimental results.
Modeling High Pressure Micro Hollow Cathode Discharges
2007-11-02
cathode discharge excimer lamps , Phys. Plasmas 7, 286 (2000). [3] RH Stark and KH Schoenbach, Direct high pressure glow discharges, J. Appl. Phys...temperature profiles in argon glow discharges, J. Appl. Phys. 88, 2234 (2000) [8] M. Moselhy, W. Shi, R. Stark, A flat glow discharge excimer radiation...MHCD acts as a plasma cathode for a third electrode (anode). Some experimental results in this geometry are available for argon and for air from the
Study on High Rate Discharge Performance and Mechanism of AB5 Type Hydrogen Storage Alloys
Institute of Scientific and Technical Information of China (English)
郭靖洪; 陈德敏; 于军; 张建海; 刘国忠; 杨柯
2004-01-01
The effects of surface treatment, particle size distribution,rare earth composition and B additive on the high rate discharge performance of hydrogen storage alloys were investigated. It is found that the activity, discharge capacity and high rate dischargeability of the alloys are improved after physical and chemical modification as a result of the increase of the surface area and formation of the electrocatalysis layers, which increase both the electrochemical reaction rate on the alloy surface and H diffusion rate in the alloy bulk. It is also found that both the over-coarse and over-fine particle size increase the contact resistance of the electrode, resulting in a decrease of discharge capacity, deterioration of high rate dischargeability and lower discharge plateau. In another word, a suitable particle size distribution can enhance the alloy activity, discharge capacity and high rate dischargeability. In addition, the high rate dischargeability is enhanced by increasing La content and decreasing Ce content of the alloy composition because of enlargement of the unit cell volume and the improvement of the surface activity. Moreover, B additive resultes in the formation of the second phase, and makes the alloys easier pulverization, which greatly improves the activity, discharge capacity and high rate dischargeability.
Model of Ozone Production in the DC Corona Discharge
Chen, Junhong; Davidson, Jane
2002-10-01
A comprehensive numerical model of ozone production in clean, dry air by DC corona discharges is presented. This model combines a first-principle corona plasma model with a chemistry and 2-D transport model to obtain the distributions of ozone and other gaseous products in the neighborhood of a corona discharge wire. Electron number density distribution is obtained by solving the continuity equations for electrons and ions and the simplified Maxwell's equation. The non-Maxwellian electron energy distribution is solved from the Boltzmann equation. The chemical kinetics of ozone formation and destruction are based on recent atmospheric chemistry models taking into account the contributions of excited molecules. The transport model includes the conservation equations for total mass, momentum, energy and the mass of individual species and is solved using FLUENT. The predicted ozone production rate agrees well with experimental data. Excited molecules contribute more than 80 percent of the total ozone produced. The effects of discharge polarity, current, wire radius, air temperature, and air velocity (residence time) on the production of ozone are discussed.
Parameter optimization model in electrical discharge machining process
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
Electrical discharge machining (EDM) process, at present is still an experience process, wherein selected parameters are often far from the optimum, and at the same time selecting optimization parameters is costly and time consuming. In this paper,artificial neural network (ANN) and genetic algorithm (GA) are used together to establish the parameter optimization model. An ANN model which adapts Levenberg-Marquardt algorithm has been set up to represent the relationship between material removal rate (MRR) and input parameters, and GA is used to optimize parameters, so that optimization results are obtained. The model is shown to be effective, and MRR is improved using optimized machining parameters.
Estimates of EPSP amplitude based on changes in motoneuron discharge rate and probability.
Powers, Randall K; Türker, K S
2010-10-01
When motor units are discharging tonically, transient excitatory synaptic inputs produce an increase in the probability of spike occurrence and also increase the instantaneous discharge rate. Several researchers have proposed that these induced changes in discharge rate and probability can be used to estimate the amplitude of the underlying excitatory post-synaptic potential (EPSP). We tested two different methods of estimating EPSP amplitude by comparing the amplitude of simulated EPSPs with their effects on the discharge of rat hypoglossal motoneurons recorded in an in vitro brainstem slice preparation. The first estimation method (simplified-trajectory method) is based on the assumptions that the membrane potential trajectory between spikes can be approximated by a 10 mV post-spike hyperpolarization followed by a linear rise to the next spike and that EPSPs sum linearly with this trajectory. We hypothesized that this estimation method would not be accurate due to interspike variations in membrane conductance and firing threshold that are not included in the model and that an alternative method based on estimating the effective distance to threshold would provide more accurate estimates of EPSP amplitude. This second method (distance-to-threshold method) uses interspike interval statistics to estimate the effective distance to threshold throughout the interspike interval and incorporates this distance-to-threshold trajectory into a threshold-crossing model. We found that the first method systematically overestimated the amplitude of small (EPSPs and underestimated the amplitude of large (>5 mV EPSPs). For large EPSPs, the degree of underestimation increased with increasing background discharge rate. Estimates based on the second method were more accurate for small EPSPs than those based on the first model, but estimation errors were still large for large EPSPs. These errors were likely due to two factors: (1) the distance to threshold can only be directly
Suicide Rates After Discharge From Psychiatric Facilities: A Systematic Review and Meta-analysis.
Chung, Daniel Thomas; Ryan, Christopher James; Hadzi-Pavlovic, Dusan; Singh, Swaran Preet; Stanton, Clive; Large, Matthew Michael
2017-07-01
High rates of suicide after psychiatric hospitalization are reported in many studies, yet the magnitude of the increases and the factors underlying them remain unclear. To quantify the rates of suicide after discharge from psychiatric facilities and examine what moderates those rates. English-language, peer-reviewed publications published from January 1, 1946, to May 1, 2016, were located using MEDLINE, PsychINFO, and EMBASE with the search terms ((suicid*).ti AND (hospital or discharg* OR inpatient or in-patient OR admit*).ab and ((mortality OR outcome* OR death*) AND (psych* OR mental*)).ti AND (admit* OR admis* or hospital* OR inpatient* OR in-patient* OR discharg*).ab. Hand searching was also done. Studies reporting the number of suicides among patients discharged from psychiatric facilities and the number of exposed person-years and studies from which these data could be calculated. The meta-analysis adhered to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. A random-effects model was used to calculate a pooled estimate of postdischarge suicides per 100 000 person-years. The suicide rate after discharge from psychiatric facilities was the main outcome, and the association between the duration of follow-up and the year of the sampling were the main a priori moderators. A total of 100 studies reported 183 patient samples (50 samples of females, 49 of males, and 84 of mixed sex; 129 of adults or unspecified patients, 20 of adolescents, 19 of older patients, and 15 from long-term or forensic discharge facilities), including a total of 17 857 suicides during 4 725 445 person-years. The pooled estimate postdischarge suicide rate was 484 suicides per 100 000 person-years (95% CI, 422-555 suicides per 100 000 person-years; prediction interval, 89-2641), with high between-sample heterogeneity (I2 = 98%). The suicide rate was highest within 3 months
Laskey, Warren K.; Alomari, Ihab; Cox, Margueritte; Schulte, Phillip J.; Zhao, Xin; Hernandez, Adrian F.; Heidenreich, Paul A.; Eapen, Zubin J.; Yancy, Clyde; Bhatt, Deepak L.; Fonarow, Gregg C.
2015-01-01
Background Whether heart rate upon discharge following hospitalization for heart failure is associated with long‐term adverse outcomes and whether this association differs between patients with sinus rhythm (SR) and atrial fibrillation (AF) have not been well studied. Methods and Results We conducted a retrospective cohort study from clinical registry data linked to Medicare claims for 46 217 patients participating in Get With The Guidelines®–Heart Failure. Cox proportional‐hazards models were used to estimate the association between discharge heart rate and all‐cause mortality, all‐cause readmission, and the composite outcome of mortality/readmission through 1 year. For SR and AF patients with heart rate ≥75, the association between heart rate and mortality (expressed as hazard ratio [HR] per 10 beats‐per‐minute increment) was significant at 0 to 30 days (SR: HR 1.30, 95% CI 1.22 to 1.39; AF: HR 1.23, 95% CI 1.16 to 1.29) and 31 to 365 days (SR: HR 1.15, 95% CI 1.12 to 1.20; AF: HR 1.05, 95% CI 1.01 to 1.08). Similar associations between heart rate and all‐cause readmission and the composite outcome were obtained for SR and AF patients from 0 to 30 days but only in the composite outcome for SR patients over the longer term. The HR from 0 to 30 days exceeded that from 31 to 365 days for both SR and AF patients. At heart rates heart failure, higher discharge heart rate was associated with increased risks of death and rehospitalization, with higher risk in the first 30 days and for SR compared with AF. PMID:25904590
Characterizing uniform discharge in atmospheric helium by numerical modelling
Institute of Scientific and Technical Information of China (English)
Lü Bo; Wang Xin-Xin; Luo Hai-Yun; Liang Zhuo
2009-01-01
One-dimensional fluid model of dielectric barrier discharge (DBD) in helium at atmospheric pressure was estab-lished and the discharge was numerically simulated. It was found that not only the spatial distributions of the internal parameters such as the electric field, the electron density and ion density are similar to those in a low-pressure glow discharge, but also the visually apparent attribute (light emission) is exactly the same as the observable feature of a low-pressure glow discharge. This confirms that the uniform DBD in atmosphcric helium is a glow type discharge. The fact that the thickness of the cathode fall layer is about 0.5 ram, much longer than that of a normal glow dischargc in helium at atmospheric pressure, indicates the discharge being a sub-normal glow discharge close to normal one. The multipulse phenomenon was reproduced in the simulation and a much less complicated explanation for this phenomenon was given.
Modelling radioactivity in the Irish Sea: From discharge to dose
Energy Technology Data Exchange (ETDEWEB)
Gleizon, P., E-mail: philippe.gleizon@westlakes.ac.u [Westlakes Scientific Consulting Ltd, The Princess Royal Building, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom); McDonald, P. [Westlakes Scientific Consulting Ltd, The Princess Royal Building, Westlakes Science and Technology Park, Moor Row, Cumbria CA24 3LN (United Kingdom)
2010-05-15
In order to support authorised discharges of low level radioactive liquid effluent into coastal regions, mathematical models are required to robustly predict radiological impacts on critical groups of current and proposed changes to liquid discharges. The grid model presented here simulates the long term dispersion and transport of radioactivity discharged from the Sellafield site in Cumbria, UK, and the subsequent exposure of critical groups in Cumbria and across the Irish Sea in Northern Ireland. The fine grid of the model allows a good resolution of the seabed sediment distribution. This benefits the predictions for the last decades of low discharge level, when bed sediment can become a source of contamination by bringing back the legacy of past high discharges. This is highlighted by the dose comparison, where the predicted dose to Cumbria critical group follows well the dose estimated from environmental data during the low discharge level period.
A 2-Dimensional Fluid Model for an Argon Rf Discharge
Passchier, J. D. P.; W. J. Goedheer,
1993-01-01
A fluid model for an argon rf discharge in a cylindrical discharge chamber is presented. The model contains the particle balances for electrons and ions and the electron energy balance. A nonzero autobias voltage is obtained by imposing the condition that the time-averaged current toward the powered
Capacity fade study of lithium-ion batteries cycled at high discharge rates
Ning, Gang; Haran, Bala; Popov, Branko N.
Capacity fade of Sony US 18650 Li-ion batteries cycled using different discharge rates was studied at ambient temperature. The capacity losses were estimated after 300 cycles at 2 C and 3 C discharge rates and were found to be 13.2 and 16.9% of the initial capacity, respectively. At 1 C discharge rate the capacity lost was only 9.5%. The cell cycled at high discharge rate (3 C) showed the largest internal resistance increase of 27.7% relative to the resistance of the fresh cells. The rate capability losses were proportional with the increase of discharge rates. Half-cell study and material and charge balances were used to quantify the capacity fade due to the losses of primary active material (Li +), the secondary active material (LiCoO 2/C)) and rate capability losses. It was found that carbon with 10.6% capacity loss after 300 cycles dominates the capacity fade of the whole cell at high discharge rates (3 C). A mechanism is proposed which explains the capacity fade at high discharge rates.
Modeling the discharge behavior of the lithium/iodine battery
Energy Technology Data Exchange (ETDEWEB)
Skarstad, P.M. (Medtronic, Inc., Minneapolis, MN (United States)); Schmidt, C.L. (Medtronic, Inc., Minneapolis, MN (United States))
1993-03-15
We have previously reported the development of a physically-based mode describing the discharge behaviour of the lithium/iodine battery. Values for the parameters of the model have been determined through analysis of discharge data from a wide variety of battery designs. This paper reviews the essential features of the model and describes several applications. These applications include estimation of performance distributions through Monte-Carlo simulations, analysis of variability in discharge performances, and identification of the parameters to which discharge performance is most sensitive. (orig.)
Model of Pulsed Electrical Discharge Machining (EDM using RL Circuit
Directory of Open Access Journals (Sweden)
Ade Erawan Bin Minhat
2014-10-01
Full Text Available This article presents a model of pulsed Electrical Discharge Machining (EDM using RL circuit. There are several mathematical models have been successfully developed based on the initial, ignition and discharge phase of current and voltage gap. According to these models, the circuit schematic of transistor pulse power generator has been designed using electrical model in Matlab Simulink software to identify the profile of voltage and current during machining process. Then, the simulation results are compared with the experimental results.
Matched comparison of GP and consultant rating of electronic discharge summaries.
Stainkey, Lesley; Pain, Tilley; McNichol, Margaret; Hack, John; Roberts, Lynden
2010-01-01
Queensland Health is implementing a state-wide system to electronically generate and distribute discharge summaries. Previously, general practitioners (GPs) have indicated that the quality of the discharge summary does not support clinical handover. While the electronic system will address some issues (e.g. legibility and timeliness), the quality of the discharge summary content is predominantly independent of method of generation. As discharge summaries are usually generated by interns, we proposed that improvement in the quality of the summary may be achieved through education. This project aimed to compare the perceptions of hospital-based consultant educators and recipient GPs regarding discharge summary content and quality. The discharge summary and audit tool were sent to the recipient GP (n=134) and a hospital consultant (n=14) for satisfaction rating, using a 5- point Likert scale for questions relating to diagnosis, the listing of clinical management, medication, pathology, investigations, and recommendations to GP. Sampling was performed by selecting up to 10 discharge summaries completed by each first-year intern (n=36) in 2009, during the second, third and fourth rotations at the Townsville Hospital until a total of 403 was reached. Matched responses were compared using the Kappa statistic. The response rate was 93% (n=375) and 63% (n=254) for consultants and GPs respectively. Results from this study demonstrated that GPs were more satisfied with discharge summaries than were consultants. An anomaly occurred in three questions where, despite the majority of GPs rating satisfied or very satisfied, a small but proportionally greater number of GPs were very dissatisfied when compared with consultants. Poor or fair agreement between GPs and consultants was demonstrated in medications, pathology results, investigations and recommendations to GP, with GPs rating higher satisfaction in all questions. Lower consultant satisfaction ratings compared with GP
Modeling of Kr-Xe discharge of excimer lamp
Directory of Open Access Journals (Sweden)
Belasri A.
2013-03-01
Full Text Available This paper reports the numerical simulation of Dielectric Barrier Discharge (DBD for Kr-Xe excilamp. The model of the discharge consists of three main modules: a plasma chemistry module, a circuit module and a Boltzmann equation module. The results predict the optimal operating conditions and describe the electrical and chemical properties of the KrXe* excimer lamp.
Modelling heart rate kinetics.
Zakynthinaki, Maria S
2015-01-01
The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise). Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual's cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects) but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women).
Modelling heart rate kinetics.
Directory of Open Access Journals (Sweden)
Maria S Zakynthinaki
Full Text Available The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise. Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual's cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women.
Zakynthinaki, Maria S.
2015-01-01
The objective of the present study was to formulate a simple and at the same time effective mathematical model of heart rate kinetics in response to movement (exercise). Based on an existing model, a system of two coupled differential equations which give the rate of change of heart rate and the rate of change of exercise intensity is used. The modifications introduced to the existing model are justified and discussed in detail, while models of blood lactate accumulation in respect to time and exercise intensity are also presented. The main modification is that the proposed model has now only one parameter which reflects the overall cardiovascular condition of the individual. The time elapsed after the beginning of the exercise, the intensity of the exercise, as well as blood lactate are also taken into account. Application of the model provides information regarding the individual’s cardiovascular condition and is able to detect possible changes in it, across the data recording periods. To demonstrate examples of successful numerical fit of the model, constant intensity experimental heart rate data sets of two individuals have been selected and numerical optimization was implemented. In addition, numerical simulations provided predictions for various exercise intensities and various cardiovascular condition levels. The proposed model can serve as a powerful tool for a complete means of heart rate analysis, not only in exercise physiology (for efficiently designing training sessions for healthy subjects) but also in the areas of cardiovascular health and rehabilitation (including application in population groups for which direct heart rate recordings at intense exercises are not possible or not allowed, such as elderly or pregnant women). PMID:25876164
DEFF Research Database (Denmark)
De Giovanni, Domenico
prepayment models for mortgage backed securities, this paper builds a Rational Expectation (RE) model describing the policyholders' behavior in lapsing the contract. A market model with stochastic interest rates is considered, and the pricing is carried out through numerical approximation...... of the corresponding two-space-dimensional parabolic partial differential equation. Extensive numerical experiments show the differences in terms of pricing and interest rate elasticity between the ACC and RE approaches as well as the sensitivity of the contract price with respect to changes in the policyholders...
DEFF Research Database (Denmark)
De Giovanni, Domenico
2010-01-01
prepayment models for mortgage backed securities, this paper builds a Rational Expectation (RE) model describing the policyholders' behavior in lapsing the contract. A market model with stochastic interest rates is considered, and the pricing is carried out through numerical approximation...... of the corresponding two-space-dimensional parabolic partial differential equation. Extensive numerical experiments show the differences in terms of pricing and interest rate elasticity between the ACC and RE approaches as well as the sensitivity of the contract price with respect to changes in the policyholders...
Discharge Water Quality Models of Storm Runoff in a Catchment
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The relationships between the water qualities of nitrogen and phosphorous contents in the discharge water and the discharge of storm runoff of an experimental catchment including terraced paddy field are analyzed based on experiment results of the catchment. By summarizing the currently related research on water quality models, the water quality models of different components of storm runoff of the catchment are presented and verified with the experiment data of water quality analyses and the corresponding discharge of the storm runoffs during 3 storms. Through estimating the specific discharge of storm runoff, the specific load of different components of nitrogen and phosphorus in the discharge water of the catchment can be forecasted by the models. It is found that the mathematical methods of linear regression are very useful for analysis of the relationship between the concentrations of nitrogen and phosphorus and the water discharge of storm runoff. It is also found that the most content of the nitrogen (75%) in the discharge water is organic, while half of the content (49%) of phosphorus in the discharge water is inorganic.
Modeling annual discharge of six Mexico’s northern rivers
Directory of Open Access Journals (Sweden)
Jose de Jesus Navar
2012-04-01
Full Text Available The overall goal of this report was to understand river discharge variability to improve conventional water management practices of Mexico’s northern subtropical rivers. This report addresses whether: a river discharge tendencies, patterns and cycles can be detected with proxy and instrumental records; and b annual discharge can be forecasted by stochastic models. Eleven gauging stations of six major rivers; three lowland rivers discharging into the Pacific Ocean (Rios Santa Cruz, Acaponeta, and San Pedro; five upland rivers draining into the Pacific Ocean (Rio San Pedro: Peña del Aguila, Refugio Salcido, San Felipe, Vicente Guerrero and Saltito, one river flowing across the interior Basin (Rio Nazas: Salomé Acosta and two more rivers discharging into the Northern Gulf of Mexico (Rio San Juan: El Cuchillo and Rio Ramos: Pablillos were statistically analyzed. Instrumental recorded daily discharge data (1940-1999 and reconstructed time series data (1860-1940 using dendrochronological analysis delivered annual discharge data to be modeled using autoregressive integrated moving average, ARIMA models. Spectral density analysis, autocorrelation functions and the standardized annual discharge data evaluated annual discharge frequency cycles. Results showed ARIMA models with two autoregressive and one moving average coefficient adequately project river discharge for all gauging stations with four of them showing significant declining patterns since 1860. ARIMA models in combination with autocorrelation and spectral density techniques as well as standardized departures, in agreement with present (2002-2010 observations, forecast a wet episode that may last between 9 and 12 years thereafter entering again into a dry episode. Three dry-wet spell cycles with different time scales (1-2 years; 4-7 years; 9-12 years could be discerned from these analyses that are consistent for all three northern Mexico’s river clusters that emerged from a multivariate
Improvement of growth rate of plants by bubble discharge in water
Takahata, Junichiro; Takaki, Koichi; Satta, Naoya; Takahashi, Katsuyuki; Fujio, Takuya; Sasaki, Yuji
2015-01-01
The effect of bubble discharge in water on the growth rate of plants was investigated experimentally for application to plant cultivation systems. Spinach (Spinacia oleracea), radish (Raphanus sativus var. sativus), and strawberry (Fragaria × ananassa) were used as specimens to clarify the effect of the discharge treatment on edible parts of the plants. The specimens were cultivated in pots filled with artificial soil, which included chicken manure charcoal. Distilled water was sprayed on the artificial soil and drained through a hole in the pots to a water storage tank. The water was circulated from the water storage tank to the cultivation pots after 15 or 30 min discharge treatment on alternate days. A magnetic compression-type pulsed power generator was used to produce the bubble discharge with a repetition rate of 250 pps. The plant height in the growth phase and the dry weight of the harvested plants were improved markedly by the discharge treatment in water. The soil and plant analyzer development (SPAD) value of the plants also improved in the growth phase of the plants. The concentration of nitrate nitrogen, which mainly contributed to the improvement of the growth rate, in the water increased with the discharge treatment. The Brix value of edible parts of Fragaria × ananassa increased with the discharge treatment. The inactivation of bacteria in the water was also confirmed with the discharge treatment.
Morgan, Hilary A.; Harris, Andrew J. L.; Gurioli, Lucia
2013-08-01
Pacaya is one of the most active volcanoes in Central America and has produced lava flows frequently since 1961. All effusive activity between 1961 and 2009 was confined by an arcuate collapse scarp surrounding the northern and eastern flanks. However, the recent breaching of this topographic barrier, and the eruption of a large lava flow outside of the main center of activity, have allowed lava to extend into nearby populated areas, indicating the need for assessment and monitoring of lava flow hazards. We investigated whether a commonly used satellite-based model could produce accurate lava discharge rates for the purpose of near-real-time assessment of hazards during future eruptions and to assess the dynamics of this persistently degassing system. The model assumes a linear relationship between active lava flow area and time-averaged discharge rate (TADR) via a simple conversion factor. We calculated the conversion factor via two methods: (1) best-fitting of satellite-derived flow areas to ground-based estimates of lava flow volume, and (2) theoretically via a parameterized model that takes into account the physical properties of the lava. To apply the latter method, we sampled four lava flows and measured density, vesicularity, crystal content, and major element composition. We found the best agreement of conversion factors in the eruption with the most complete satellite coverage, and used data for these flows to define the linear relationship between area and discharge rate. The physical properties of the sampled flows were essentially identical, so that any discrepancy between the two methods of calculating conversion factors must be due to modeling errors or environmental factors unaccounted for by the parameterized model. However, our best-fitting method provides a new means to set the conversion appropriately, and to obtain self-consistent TADRs. We identified two distinct types of effusive activity at Pacaya: Type 1 activity characterized by initially
Mass discharge rate retrieval combining weather radar and thermal camera observations
Vulpiani, Gianfranco; Ripepe, Maurizio; Valade, Sebastien
2016-08-01
The mass discharge rate is a key parameter for initializing volcanic ash dispersal models. Commonly used empirical approaches derive the discharge rate by the plume height as estimated by remote sensors. A novel approach based on the combination of weather radar observations and thermal camera imagery is presented here. It is based on radar ash concentration estimation and the retrieval of the vertical exit velocities of the explosive cloud using thermal camera measurements. The applied radar retrieval methodology is taken from a revision of previously presented work. Based on the analysis of four eruption events of the Mount Etna volcano (Sicily, Italy) that occurred in December 2015, the proposed methodology is tested using observations collected by three radar systems (at C and X band) operated by the Italian Department of Civil Protection. The total erupted mass was estimated to be about 9·109 kg and 2.4·109 kg for the first and second events, respectively, while it was about 1.2·109 kg for both the last two episodes. The comparison with empirical approaches based on radar-retrieved plume height shows a reasonably good agreement. Additionally, the comparative analysis of the polarimetric radar measurements provides interesting information on the vertical structure of the ash plume, including the size of the eruption column and the height of the gas thrust region.
Impact of gas flow rate on breakdown of filamentary dielectric barrier discharges
Höft, H.; Becker, M. M.; Kettlitz, M.
2016-03-01
The influence of gas flow rate on breakdown properties and stability of pulsed dielectric barrier discharges (DBDs) in a single filament arrangement using a gas mixture of 0.1 vol. % O2 in N2 at atmospheric pressure was investigated by means of electrical and optical diagnostics, accompanied by fluid dynamics and electrostatics simulations. A higher flow rate perpendicular to the electrode symmetry axis resulted in an increased breakdown voltage and DBD current maximum, a higher discharge inception jitter, and a larger emission diameter of the discharge channel. In addition, a shift of the filament position for low gas flow rates with respect to the electrode symmetry axis was observed. These effects can be explained by the change of the residence time of charge carriers in the discharge region—i.e., the volume pre-ionization—for changed flow conditions due to the convective transport of particles out of the center of the gap.
Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet
Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan
2015-09-01
A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)
Applying the welfare model to at-own-risk discharges.
Krishna, Lalit Kumar Radha; Menon, Sumytra; Kanesvaran, Ravindran
2017-08-01
"At-own-risk discharges" or "self-discharges" evidences an irretrievable breakdown in the patient-clinician relationship when patients leave care facilities before completion of medical treatment and against medical advice. Dissolution of the therapeutic relationship terminates the physician's duty of care and professional liability with respect to care of the patient. Acquiescence of an at-own-risk discharge by the clinician is seen as respecting patient autonomy. The validity of such requests pivot on the assumptions that the patient is fully informed and competent to invoke an at-own-risk discharge and that care up to the point of the at-own-risk discharge meets prevailing clinical standards. Palliative care's use of a multidisciplinary team approach challenges both these assumptions. First by establishing multiple independent therapeutic relations between professionals in the multidisciplinary team and the patient who persists despite an at-own-risk discharge. These enduring therapeutic relationships negate the suggestion that no duty of care is owed the patient. Second, the continued employ of collusion, familial determinations, and the circumnavigation of direct patient involvement in family-centric societies compromises the patient's decision-making capacity and raises questions as to the patient's decision-making capacity and their ability to assume responsibility for the repercussions of invoking an at-own-risk discharge. With the validity of at-own-risk discharge request in question and the welfare and patient interest at stake, an alternative approach to assessing at-own-risk discharge requests are called for. The welfare model circumnavigates these concerns and preserves the patient's welfare through the employ of a multidisciplinary team guided holistic appraisal of the patient's specific situation that is informed by clinical and institutional standards and evidenced-based practice. The welfare model provides a robust decision-making framework for
Maheshwari, Arpit; Dumitrescu, Mihaela Aneta; Destro, Matteo; Santarelli, Massimo
2016-03-01
Battery models are riddled with incongruous values of parameters considered for validation. In this work, thermally coupled electrochemical model of the pouch is developed and discharge tests on a LiFePO4 pouch cell at different discharge rates are used to optimize the LiFePO4 battery model by determining parameters for which there is no consensus in literature. A discussion on parameter determination, selection and comparison with literature values has been made. The electrochemical model is a P2D model, while the thermal model considers heat transfer in 3D. It is seen that even with no phase change considered for LiFePO4 electrode, the model is able to simulate the discharge curves over a wide range of discharge rates with a single set of parameters provided a dependency of the radius of the LiFePO4 electrode on discharge rate. The approach of using a current dependent radius is shown to be equivalent to using a current dependent diffusion coefficient. Both these modelling approaches are a representation of the particle size distribution in the electrode. Additionally, the model has been thermally validated, which increases the confidence level in the selection of values of parameters.
DEFF Research Database (Denmark)
De Giovanni, Domenico
2010-01-01
prepayment models for mortgage backed securities, this paper builds a Rational Expectation (RE) model describing the policyholders' behavior in lapsing the contract. A market model with stochastic interest rates is considered, and the pricing is carried out through numerical approximation......The surrender option embedded in many life insurance products is a clause that allows policyholders to terminate the contract early. Pricing techniques based on the American Contingent Claim (ACC) theory are often used, though the actual policyholders' behavior is far from optimal. Inspired by many......' behavior....
Jang, Cheng-Shin
2015-05-01
Accurately classifying the spatial features of the water temperatures and discharge rates of hot springs is crucial for environmental resources use and management. This study spatially characterized classifications of the water temperatures and discharge rates of hot springs in the Tatun Volcanic Region of Northern Taiwan by using indicator kriging (IK). The water temperatures and discharge rates of the springs were first assigned to high, moderate, and low categories according to the two thresholds of the proposed spring classification criteria. IK was then used to model the occurrence probabilities of the water temperatures and discharge rates of the springs and probabilistically determine their categories. Finally, nine combinations were acquired from the probability-based classifications for the spatial features of the water temperatures and discharge rates of the springs. Moreover, various combinations of spring water features were examined according to seven subzones of spring use in the study region. The research results reveal that probability-based classifications using IK provide practicable insights related to propagating the uncertainty of classifications according to the spatial features of the water temperatures and discharge rates of the springs. The springs in the Beitou (BT), Xingyi Road (XYR), Zhongshanlou (ZSL), and Lengshuikeng (LSK) subzones are suitable for supplying tourism hotels with a sufficient quantity of spring water because they have high or moderate discharge rates. Furthermore, natural hot springs in riverbeds and valleys should be developed in the Dingbeitou (DBT), ZSL, Xiayoukeng (XYK), and Macao (MC) subzones because of low discharge rates and low or moderate water temperatures.
A differential equation for the flow rate during silo discharge: Beyond the Beverloo rule
2016-01-01
We present a differential equation for the flow rate of granular materials during the discharge of a silo. This is based in the energy balance of the variable mass system in contrast with the traditional derivations based on heuristic postulates such as the free fall arch. We show that this new equation is consistent with the well known Beverloo rule, providing an independent estimate for the universal Beverloo prefactor. We also find an analytic expression for the pressure under discharging ...
Study on the Hippocampal Neuron's Minimal Models' Discharge Patterns
Directory of Open Access Journals (Sweden)
Yueping Peng
2011-06-01
Full Text Available The hippocampal CA1 pyramid neuron has plenty of discharge actions. The one-compartment model of CA1 pyramid neuron developed by David is a nine-dimension complex dynamic model. In the thesis, the currents related to the nine-dimension complex model are analyzed and classified by the model’s reduction theory and methods based on neurodynamics, and four minimal models are gotten: (I_Na+I_Kdr-minimal model, (I_Na+I_M-minimal model, (I_Na+I_Ca+I_y-minimal model, and (I_Na+I_Ca+I_sAHP-minimal model. These minimal models have plenty of dynamic actions, and under the current’s stimulation, they can all generate regular discharge and have period discharge pattern, bursting pattern, the chaos discharge pattern, and so on. Compared with the initial nine-dimension complex model, these minimal models’ dimension are much reduced, and are more convenient to numerical simulation, calculating, and analyzing. In addition, these minimal models provide a simpler and flexible method to discuss the specific currents’ dynamic characteristics and functions of the initial nine-dimension complex model by the theory of neurodynamics.
Analysis of low energy arc discharge characteristics based on dynamic V-A characteristics model
Institute of Scientific and Technical Information of China (English)
JING Li-nan; WANG Li-gong
2006-01-01
Low energy arc discharge characteristics was analyzed based on dynamic V-A characteristics model. It draws conclusions that discharge time relates to the source voltage and the product of inductance and stable current, discharge time will increase when the source voltage increases; current reduce rate is in inverse proportion to the value of inductance; arc resistance when the arc occurs is the ratio of minimum arcing voltage to stable current. It also gains the expressions of arc resistance and arc power, arc resistance and arc power both increase as the source voltage increases and decrease as the value of inductance increases. Conclusions above mentioned are helpful to design intrinsically safe circuits.
Wang, Pengxiang; Chen, Junhong
2009-02-01
The effect of electrode configuration on ozone production in the direct-current corona discharge of dry and humid air is studied by a numerical model that combines the electron distribution in the corona plasma, plasma chemistry and transport phenomena. Two electrode configurations are considered: wire-cylinder discharge with air flowing along the wire axis and wire-plate discharge with air flowing transverse to the wire. The ozone distributions in both types of discharges are compared. For both electrode configurations, the ozone production rate is higher in the negative corona than in the positive corona and it decreases with an increase in relative humidity. More importantly, the detailed ozone distribution in the neighbourhood of the discharge wire, together with the ozone kinetics, reveals the possible difference in the ozone production from the two discharges. With the same operating conditions and sufficiently short flow residence time, the ozone production rate is nearly the same for both electrode configurations. When the flow residence time is longer than the characteristic time for homogeneous ozone destruction, the net ozone production is higher in the wire-cylinder discharge than in the wire-plate discharge due to relatively less ozone destruction.
Modeling and optimization of Electrical Discharge Machining (EDM using statistical design
Directory of Open Access Journals (Sweden)
Hegab Husein A.
2015-01-01
Full Text Available Modeling and optimization of nontraditional machining is still an ongoing area of research. The objective of this work is to optimize Electrical Discharge Machining process parameters of Aluminum-multiwall carbon Nanotube composites (AL-CNT model. Material Removal Rate (MRR, Wear Electrode Ratio (EWR and Average Surface Roughness (Ra are primary objectives. The Machining parameters are machining-on time (sec, discharge current (A, voltage (V, total depth of cut (mm, and %wt. CNT added. Mathematical models for all responses as function of significant process parameters are developed using Response Surface Methodology (RSM. Experimental results show optimum levels for material removal rate are %wt. CNT (0%, high level of discharge current (6A and low level of voltage (50 V while optimum levels for Electrode wear ratio are %wt. CNT (5%, high level of discharge current (6A and optimum levels for average surface roughness are %wt. CNT (0%, low level of discharge current (2A and high level of depth of cut (1 mm. Single-objective optimization is formulated and solved via Genetic Algorithm. Multi-objective optimization model is then formulated for the three responses of interest. This methodology gathers experimental results, builds mathematical models in the domain of interest and optimizes the process models. As such, process analysis, modeling, design and optimization are achieved.
Modelling of Suspended Sediment Discharge for Masinga ...
African Journals Online (AJOL)
Sedimentation models however, require suspended load as the basic input data. ... at the two mouths of the reservoir, at the confluence, and near the dam wall. ... Dredging out fine sediments, construction of sedimentation basins at the two ...
Stability-transport modeling of the SINP tokamak discharges
Indian Academy of Sciences (India)
S Lahiri; S Mukhopadhyay; A N S Iyengar; R Pal
2001-05-01
A one-dimensional stability transport code has been developed to simulate the evolution of tokamak plasma discharges. Explicit finite-difference methods have been used to follow the temporal evolution of the electron temperature equation. The poloidal field diffusion equation has been solved at every time step. The effects of MHD instabilities have been incorporated by solving equations for MHD mixing and tearing modes as and when required. The code has been applied to follow the evolution of tokamak plasma discharges obtained in the Saha Institute of Nuclear Physics (SINP) tokamak. From these simulations, we have been able to identify the possible models of thermal conductivity, diffusion and impurity contents in these discharges. Effects of different MHD modes have been estimated. It has been found that in low discharge =1, =1 and =2, =1 modes play major role in discharge evolution. These modes are found to result in the positive jump in the loop voltage which was also observed in the experiments. Hollow current density profile and negative shear in the profile have also been found in the rising phase of a discharge.
Modeling self-discharge of Li/SOCl 2 cells
Spotnitz, R. M.; Yeduvaka, G. S.; Nagasubramanian, G.; Jungst, R.
A kinetic expression for the chemical reaction of lithium metal with thionyl chloride is presented that is consistent with calorimetric measurements of the heat generation from a thionyl chloride cell. The kinetics expression is incorporated into a well-established electrochemical model for the discharge behavior, and then used to estimate the life of the battery under an intermittent discharge so as to assess the importance of lithium corrosion. The model predicts that, under the conditions examined, there is no danger of depleting the lithium anode and so introducing a safety hazard.
Sasaki, Akira; Kato, Susumu; Takahashii, Eiichi; Kishimoto, Yasuaki; Fujii, Takashi; Kanazawa, Seiji
2016-02-01
We show a cell simulation of a discharge in an insulating gas from the initial partial discharge to leader inception until breakdown, based on the percolation model. In the model, we consider that the propagation of the leader occurs when connections between randomly produced ionized regions in the discharge medium are established. To determine the distribution of ionized regions, the state of each simulation cell is decided by evaluating the probability of ionization in SF6, which depends on the local electric field. The electric field as well as the discharge current are calculated by solving circuit equations for the network of simulation cells. Both calculations are coupled to each other and the temporal evolution of discharge is self-consistently calculated. The model dependence of the features of the discharge is investigated. It is found that taking the suppression of attachment in the presence of a discharge current into account, the calculation reproduces the behavior of experimental discharges. It is shown that for a strong electric field, the inception of a stepped leader causes immediate breakdown. For an electric field of 30-50% of the critical field, the initial partial discharge persists for a stochastic time lag and then the propagation of a leader takes place. As the strength of the electric field decreases, the time lag increases rapidly and eventually only a partial discharge with a short arrested leader occurs, as observed in experiments.
Energy Technology Data Exchange (ETDEWEB)
Brenning, N.; Axnaes, I.; Nilsson, J.O.; Eninger, J.E. [Royal Inst. of Tech., Stockholm (Sweden)
1997-02-01
The requirements on preionization for the formation of spatially homogeneous pulsed avalanche discharges are examined. The authors derive two formulas which apply in the case of a slowly rising electric field, one which gives the required preionization density at breakdown, and one which gives the required preionization rate. These quantities are expressed as functions of the electrochemical properties of the gas, the neutral density, and the electric field rise time. They also treat the statistical effect that the electrons tend to form groups, in contrast to being randomly distributed in space, during the prebreakdown phase. This process is found to increase the required preionization rate significantly, typically by a factor of five for a discharge at atmospheric pressure. Homogeneous high-pressure discharges have been used for laser excitation, and have also been proposed for chemical plasma processing (ozone production) because of their good scaling properties and high efficiency.
Comparison Between Overtopping Discharge in Small and Large Scale Models
DEFF Research Database (Denmark)
Helgason, Einar; Burcharth, Hans F.
2006-01-01
small and large scale model tests show no clear evidence of scale effects for overtopping above a threshold value. In the large scale model no overtopping was measured for waveheights below Hs = 0.5m as the water sunk into the voids between the stones on the crest. For low overtopping scale effects...... are presented as the small-scale model underpredicts the overtopping discharge....
Strength training, but not endurance training, reduces motor unit discharge rate variability.
Vila-Chã, Carolina; Falla, Deborah
2016-02-01
This study evaluates and compares the effects of strength and endurance training on motor unit discharge rate variability and force steadiness of knee extensor muscles. Thirty sedentary healthy men (age, 26.0±3.8yrs) were randomly assigned to strength training, endurance training or a control group. Conventional endurance and strength training was performed 3days per week, over a period of 6weeks. Maximum voluntary contraction (MVC), time to task failure (at 30% MVC), coefficient of variation (CoV) of force and of the discharges rates of motor units from the vastus medialis obliquus and vastus lateralis were determined as subjects performed 20% and 30% MVC knee extension contractions before and after training. CoV of motor unit discharges rates was significantly reduced for both muscles following strength training (Pstrength training intervention only (PStrength training, but not endurance training, reduces motor unit discharge rate variability and enhances force steadiness of the knee extensors. These results provide new insights into the neuromuscular adaptations that occur with different training methods.
KINETIC MODEL OF ELECTRIC-DISCHARGE СО2-LASER WITH FAST FLOW
Directory of Open Access Journals (Sweden)
V. Nevdakh
2013-01-01
Full Text Available The paper presents a kinetic model of CW electric-discharge CO2-laser with fast flow. Expressions linking a non-saturated gain ratio, saturation intensity and output power of the fast-flow laser with excitation rates and relaxation times of laser levels have been obtained in the paper. The paper demonstrates that the higher excitation and flow rates or higher saturation intensity provide considerably higher specific output power of the fast-flow CO2-laser in comparison with a sealed-off CO2-laser. While maintaining a steady discharge the same output power of the fast-flow CO2-laser may be obtained under various discharge conditions and combinations of fast flow rate, gas mixture composition and active media temperature.
A differential equation for the flow rate during silo discharge: Beyond the Beverloo rule
Directory of Open Access Journals (Sweden)
Madrid Marcos A.
2017-01-01
Full Text Available We present a differential equation for the flow rate of granular materials during the discharge of a silo. This is based in the energy balance of the variable mass system in contrast with the traditional derivations based on heuristic postulates such as the free fall arch. We show that this new equation is consistent with the well known Beverloo rule, providing an independent estimate for the universal Beverloo prefactor. We also find an analytic expression for the pressure under discharging conditions.
Four Order Electrostatic Discharge Circuit Model and its Simulation
Directory of Open Access Journals (Sweden)
Xiaodong Wang
2012-12-01
Full Text Available According to the international electrotechnical commission issued IEC61000-4-2 test standard, through the electrostatic discharge current waveform characteristics analysis and numerical experiment method, and construct a new ESD current expression. Using Laplasse transform, established the ESD system mathematical model. According to the mathematical model, construction of passive four order ESD system circuit model and active four order ESD system circuit model, and simulation. The simulation results meet the IEC61000-4-2 standard, and verify the consistency of the ESD current expression, the mathematical model and the circuit model.
Rate of three-body electron attachment to the oxygen molecule in an externally sustained discharge
Energy Technology Data Exchange (ETDEWEB)
Krasyukov, A.G.; Naumov, V.G.; Shachkin, L.V.; Shashkov, V.M.
1981-05-01
The rate of three-body attachment of electrons to the oxygen molecule has been determined in an atmospheric-pressure discharge sustained by a fast electron beam in a O/sub 2/:N/sub 2/ = 1:20 mixture. The experimental results agree well with theoretical results derived elsewhere. The attachment rate falls off with increasing input energy. A qualitative explanation is offered for this effect.
Directory of Open Access Journals (Sweden)
Won Il Cho
2013-10-01
Full Text Available This paper reports a modeling methodology to predict the effects on the discharge behavior of the cathode composition of a lithium iron phosphate (LFP battery cell comprising a LFP cathode, a lithium metal anode, and an organic electrolyte. A one-dimensional model based on a finite element method is presented to calculate the cell voltage change of a LFP battery cell during galvanostatic discharge. To test the validity of the modeling approach, the modeling results for the variations of the cell voltage of the LFP battery as a function of time are compared with the experimental measurements during galvanostatic discharge at various discharge rates of 0.1C, 0.5C, 1.0C, and 2.0C for three different compositions of the LFP cathode. The discharge curves obtained from the model are in good agreement with the experimental measurements. On the basis of the validated modeling approach, the effects of the cathode composition on the discharge behavior of a LFP battery cell are estimated. The modeling results exhibit highly nonlinear dependencies of the discharge behavior of a LFP battery cell on the discharge C-rate and cathode composition.
Directory of Open Access Journals (Sweden)
Seena Fazel
Full Text Available To determine rates and risk factors for adverse outcomes in patients discharged from forensic psychiatric services.We conducted a historical cohort study of all 6,520 psychiatric patients discharged from forensic psychiatric hospitals between 1973 and 2009 in Sweden. We calculated hazard ratios for mortality, rehospitalisation, and violent crime using Cox regression to investigate the effect of different psychiatric diagnoses and two comorbidities (personality or substance use disorder on outcomes.Over mean follow-up of 15.6 years, 30% of patients died (n = 1,949 after discharge with an average age at death of 52 years. Over two-thirds were rehospitalised (n = 4,472, 69%, and 40% violently offended after discharge (n = 2,613 with a mean time to violent crime of 4.2 years. The association between psychiatric diagnosis and outcome varied-substance use disorder as a primary diagnosis was associated with highest risk of mortality and rehospitalisation, and personality disorder was linked with the highest risk of violent offending. Furthermore comorbid substance use disorder typically increased risk of adverse outcomes.Violent offending, premature mortality and rehospitalisation are prevalent in patients discharged from forensic psychiatric hospitals. Individualised treatment plans for such patients should take into account primary and comorbid psychiatric diagnoses.
Model of hospital-supported discharge after stroke
DEFF Research Database (Denmark)
Torp, Claus Rydahl; Vinkler, Sonja; Pedersen, Kirsten Damgaard
2006-01-01
BACKGROUND AND PURPOSE: Readmission rate within 6 months after a stroke is 40% to 50%. The purpose of the project was to evaluate whether an interdisciplinary stroke team could reduce length of hospital stay, readmission rate, increase patient satisfaction and reduce dependency of help. METHODS......: One hundred and ninety-eight patients with acute stroke were randomized into 103 patients whose discharge was supported by an interdisciplinary stroke team and 95 control patients who received standard aftercare. Baseline characteristics were comparable in the 2 groups. The patients were evaluated...... services. Furthermore, there was no significant difference in functional scores or patient satisfaction. CONCLUSIONS: In this setting we could not show benefit of an interdisciplinary stroke team supporting patients at discharge perhaps because standard aftercare was very efficient already....
A self-consistent model for a longitudinal discharge excited He-Sr recombination laser
Energy Technology Data Exchange (ETDEWEB)
Carman, R.J. (Centre for Lasers and Applications, Macquarie University, Sydney NSW 2109 (AU))
1990-09-01
A computer model has been developed to simulate the plasma kinetics in a high-repetition frequency, discharge excited He-Sr recombination laser. A detailed rate equation analysis, incorporating about 80 collisional and radiative processes, is used to determine the temporal and spatial (radial) behavior of the discharge parameters and the intracavity laser field during the current pulse, recombination phase, and afterglow periods. The set of coupled first-order ordinary differential equations used to describe the plasma and external electrical circuit are integrated over multiple discharge cycles to yield fully self-consistent results. The computer model has been used to simulate the behavior of the laser for a set of standard conditions corresponding to typical operating conditions. The species population densities predicted by the model are compared with radial and time-dependent Hook measurements determined experimentally for the same set of standard conditions.
Numerical modeling of a glow discharge through a supersonic bow shock in air
Rassou, S.; Packan, D.; Elias, P.-Q.; Tholin, F.; Chemartin, L.; Labaune, J.
2017-03-01
The interaction between a glow discharge and the bow shock of a Mach 3 air flow around a truncated conical model with a central spike is modeled, and comparison is made with prior experimental results. The KRONOS workflow for plasma modeling in flow fields, which has recently been developed at ONERA, was used for the modeling. Based on the quasi-neutral approximation, it couples hypersonic and reactive flow fields with electron chemistry, including the effect of non-Maxwellian electron energy distribution function. The model used for the discharge involves 12 species and 82 reactions, including ionization, electronic and vibrational excitation, and attachment. The simulations reproduce the main features of the discharge observed experimentally well, in particular, the very recognizable topology of the discharge. It was found from the simulations that behind the bow shock, in the afterglow, the negative ion flow ensures the electrical conduction and the establishment of the glow discharge. The influence of kinetic rates on the voltage-current characteristics is discussed.
Baumann, Matt; Evans, Sherrill; Perkins, Margaret; Curtis, Lesley; Netten, Ann; Fernandez, Jose-Luis; Huxley, Peter
2007-07-01
In recent years, there has been significant concern, and policy activity, in relation to the problem of delayed discharges from hospital. Key elements of policy to tackle delays include new investment, the establishment of the Health and Social Care Change Agent Team, and the implementation of the Community Care (Delayed Discharge) Act 2003. Whilst the problem of delays has been widespread, some authorities have managed to tackle delays successfully. The aim of the qualitative study reported here was to investigate discharge practice and the organisation of services at sites with consistently low rates of delay, in order to identify factors supporting such good performance. Six 'high performing' English sites (each including a hospital trust, a local authority, and a primary care trust) were identified using a statistical model, and 42 interviews were undertaken with health and social services staff involved in discharge arrangements. Additionally, the authors set out to investigate the experiences of patients in the sites to examine whether there was a cost to patient care and outcomes of discharge arrangements in these sites, but unfortunately, it was not possible to secure sufficient patient participation. Whilst acknowledging the lack of patient experience and outcome data, a range of service elements was identified at the sites that contribute to the avoidance of delays, either through supporting efficiency within individual agencies or enabling more efficient joint working. Sites still struggling with delays should benefit from knowledge of this range. The government's reimbursement scheme appears to have been largely helpful in the study sites, prompting efficiency-driven changes to the organisation of services and discharge systems, but further focused research is required to provide clear evidence of its impact nationally, and in particular, how it impacts on staff, and patients and their families.
Xu, Wen-Tao; Peng, Hong-Jie; Huang, Jia-Qi; Zhao, Chen-Zi; Cheng, Xin-Bing; Zhang, Qiang
2015-09-01
The self-discharge of a lithium-sulfur cell decreases the shelf-life of the battery and is one of the bottlenecks that hinders its practical applications. New insights into both the internal chemical reactions in a lithium-sulfur system and effective routes to retard self-discharge for highly stable batteries are crucial for the design of lithium-sulfur cells. Herein, a lithium-sulfur cell with a carbon nanotube/sulfur cathode and lithium-metal anode in lithium bis(trifluoromethanesulfonyl)imide/1,3-dioxolane/dimethyl ether electrolyte was selected as the model system to investigate the self-discharge behavior. Both lithium anode passivation and polysulfide anion diffusion suppression strategies are applied to reduce self-discharge of the lithium-sulfur cell. When the lithium-metal anode is protected by a high density passivation layer induced by LiNO3 , a very low shuttle constant of 0.017 h(-1) is achieved. The diffusion of the polysulfides is retarded by an ion-selective separator, and the shuttle constants decreased. The cell with LiNO3 additive maintained a discharge capacity of 97 % (961 mAh g(-1) ) of the initial capacity after 120 days at open circuit, which was around three times higher than the routine cell (32 % of initial capacity, corresponding to 320 mAh g(-1) ). It is expected that lithium-sulfur batteries with ultralow self-discharge rates may be fabricated through a combination of anode passivation and polysulfide shuttle control, as well as optimization of the lithium-sulfur cell configuration.
Effects of mixing on post-discharge modeling of ElectricOIL experiments
Palla, Andrew D.; Carroll, David L.; Verdeyen, Joseph T.; Solomon, Wayne C.
2006-02-01
In an electric discharge Oxygen-Iodine laser (ElectricOIL), the desired O II(a1Δ) is produced using a low-to-medium pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the post-discharge kinetics which are not encountered in a classic purely chemical O II(a1-Δ) generation system. Mixing effects are also present. In this paper we present post-discharge modeling results obtained using a modified version of the Blaze-II gas laser code. A 28 specie, 105 reaction chemical kinetic reaction set for the post-discharge kinetics is presented. Calculations were performed to ascertain the impact of a two stream mixing mechanism on the numerical model and to study gain as a function of reactant mass flow rates. The calculations were compared with experimental data. Agreement with experimental data was improved with the addition of new kinetics and the mixing mechanism.
Design of Water Discharge of Medewi Watershed Using Avswat Model
Pramana, Y. H.; Purwanto, B. P.
2013-12-01
Medewi watersheds is located in the southern of Bali Island and its estuary is located in Medewi Beach at Kabupaten Jembrana. The exact location of Medewi watersheds is between Desa Medewi and Desa Pulukan, Kecamatan Pekutatan, Kabupaten Jembrana. The watersheds itself, due to its strategic location is used as a territorial border between the two villages. Geographically, Medewi watersheds is between 114o48'00' - 114o50'00' east longitude and 08o20'00' - 08o26,5'00' south latitude. The main river of Medewi Watersheds is 25,64 km long and is classified as a continuous river, the width of the watersheds itself is measured 128,2 km2. Medewi watersheds have two tributaries which is Medaan watersheds and Pangliman watersheds, both watersheds' heads are located in Medewi Beach. Medewi watersheds is often flooded and brings heavy toll to its surrounding areas and citizen. Therefore, there is an urgent need to perform engineering techniques to overcome the aforementioned problem. However, there is a slight issue in the definition of water discharge plan in the location. The water discharge plan, which is used as a basis to prevent flooding, is often inaccurate. That is the reason why it is needed to build a model in order to accurately find out the amount of water discharge in the study location. Medewi watersheds' area usage is as follow: bushes (9,44%), forestation (77,10%), farm (7,76%), settlement (2,15%), irrigation field (1,64%), rainfed field (1,88%) and crops field (0,48%). The result of our modeling using ASVAT shows that the maximum water discharge is 149,9 m3/sec. The discharge is calibrated with the available water discharge data log. According to AWLR data, it is known that the largest discharge occurred on June 2nd, 2009 and measured at 147,9 m3/sec. Our conclusion is that the model used in this study managed to approach the field result with minimum error.
Mathematical model for simulating discharges on the Sabine River between Tatum and Ruliff, Texas
Neely, Braxtel L.
1979-01-01
A mathematical model for simulating discharges on the Sabine River between Tatum and Ruliff, TX., was developed to evaluate the effects of release schedules on discharges from the Toledo Bend Reservoir compared to discharges under natural conditions. Using the discharge at Tatum, TX., the rainfall over the basin, and the discharge release schedule for the reservoir, discharge hydrographs for the natural and reservoir-controlled conditions can be computed. (Woodard-USGS)
Panchal, S.; Dincer, I.; Agelin-Chaab, M.; Fraser, R.; Fowler, M.
2017-03-01
It is very important to have quantitative data regarding the temperature distributions of lithium-ion batteries at different discharge rates in order to design thermal management systems and also for battery thermal modellers. In this paper, the surface temperature distributions on a superior lithium polymer battery (SLPB) with lithium manganese nickel cobalt oxide (LiMnNiCoO2) cathode material (16 Ah capacity) at C/8, C/4, C/2, 1C, 2C, and 3C discharge rates are presented. Additionally, a battery thermal model is developed for this battery using a neural network approach with the Bayesian Regularization method and the simulated results are compared with experimental results in terms of temperature and voltage profiles at C/8, C/4, C/2, 1C, 2C, and 3C discharge rates. Thermal images, which were also captured during experiments with an IR camera at various discharge rates, and are reported in the paper. The results of this study show that the increased discharge rates between C/8 and 3C results in increased surface temperature distributions on the principal surface of the battery and decreased discharge capacity.
Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration
Energy Technology Data Exchange (ETDEWEB)
Prasetyaningrum, A., E-mail: ajiprasetyaningrum@gmail.com; Ratnawati,; Jos, B. [Department of Chemical Engineering, Faculty of Engineering, Diponegoro University Jl. Prof. H. Soedarto Tembalang, Semarang, Central Java, Indonesia, 50276 (Indonesia)
2015-12-29
Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.
Determining the Discharge Rate from a Submerged Oil Leaks using ROV Video and CFD study
Saha, Pankaj; Shaffer, Frank; Shahnam, Mehrdad; Savas, Omer; Devites, Dave; Steffeck, Timothy
2016-11-01
The current paper reports a technique to measure the discharge rate by analyzing the video from a Remotely Operated Vehicle (ROV). The technique uses instantaneous images from ROV video to measure the velocity of visible features (turbulent eddies) along the boundary of an oil leak jet and subsequently classical theory of turbulent jets is imposed to determine the discharge rate. The Flow Rate Technical Group (FRTG) Plume Team developed this technique that manually tracked the visible features and produced the first accurate government estimates of the oil discharge rate from the Deepwater Horizon (DWH). For practical application this approach needs automated control. Experiments were conducted at UC Berkeley and OHMSETT that recorded high speed, high resolution video of submerged dye-colored water or oil jets and subsequently, measured the velocity data employing LDA and PIV software. Numerical simulation have been carried out using experimental submerged turbulent oil jets flow conditions employing LES turbulence closure and VOF interface capturing technique in OpenFOAM solver. The CFD results captured jet spreading angle and jet structures in close agreement with the experimental observations. The work was funded by NETL and DOI Bureau of Safety and Environmental Enforcement (BSEE).
A global model study of silane/hydrogen discharges
Danko, Stephan; Bluhm, Dirk; Bolsinger, Valentin; Dobrygin, Wladislaw; Schmidt, Oliver; Brinkmann, Ralf Peter
2013-10-01
An algorithm to automatically build a general global chemical model on the basis of a set of chemical reactions is developed for capacitively coupled discharges. The methodology is applied to silane/hydrogen discharge regimes relevant for the deposition of microcrystalline silicon thin films for solar cell fabrication. The input parameters of the model are merely the process conditions such as absorbed power, pressure, gas flow, gas mixture and gap distance as well as the electron energy distribution function. Computational time is less than 30 s for an analytical description of the electron energy distribution and less than 40 s in the case of a look-up table for one set of process parameters for a silane/hydrogen gas mixture. The electron Boltzmann equation solver BOLSIG+ is used to determine the most appropriate electron energy distribution depending on different process conditions of this application. The numerical results of the global model are compared with measurements of silane depletion from the literature and show good agreement. A wide range of process conditions relevant for the deposition of thin-film silicon is covered. An analysis of the effect of different process conditions on the resulting plasma composition is performed. This shows the potential of a global model for silane/hydrogen discharges.
Directory of Open Access Journals (Sweden)
J. Crusius
2005-01-01
Full Text Available Submarine groundwater discharge was quantified by a variety of methods for a 4-day period during the early summer of 2004, in Salt Pond, adjacent to Nauset Marsh, on Cape Cod, USA. Discharge estimates based on radon and salinity took advantage of the presence of the narrow channel connecting Salt Pond to Nauset Marsh, which allowed constructing whole-pond mass balances as water flowed in and out due to tidal fluctuations. The data suggest that less than one quarter of the discharge in the vicinity of Salt Pond happened within the pond itself, while three quarters or more of the discharge occurred immediately seaward of the pond, either in the channel or in adjacent regions of Nauset Marsh. Much of this discharge, which maintains high radon activities and low salinity, is carried into the pond during each incoming tide. A box model was used as an aid to understand both the rates and the locations of discharge in the vicinity of Salt Pond. The model achieves a reasonable fit to both the salinity and radon data assuming submarine groundwater discharge is fresh and that most of it occurs either in the channel or in adjacent regions of Nauset Marsh. Salinity and radon data, together with seepage meter results, do not rule out discharge of saline groundwater, but suggest either that the saline discharge is at most comparable in volume to the fresh discharge or that it is depleted in radon. The estimated rate of fresh groundwater discharge in the vicinity of Salt Pond is 3000-7000 m3 d-1. This groundwater flux estimated from the radon and salinity data is comparable to a value of 3200-4500 m3 d-1 predicted by a recent hydrologic model (Masterson, 2004; Colman and Masterson, 2004, although the model predicts this rate of discharge to the pond whereas our data suggest most of the groundwater bypasses the pond prior to discharge. Additional work is needed to determine if the measured rate of discharge is representative of the long-term average, and to
Electrical model of dielectric barrier discharge homogenous and filamentary modes
López-Fernandez, J. A.; Peña-Eguiluz, R.; López-Callejas, R.; Mercado-Cabrera, A.; Valencia-Alvarado, R.; Muñoz-Castro, A.; Rodríguez-Méndez, B. G.
2017-01-01
This work proposes an electrical model that combines homogeneous and filamentary modes of an atmospheric pressure dielectric barrier discharge cell. A voltage controlled electric current source has been utilized to implement the power law equation that represents the homogeneous discharge mode, which starts when the gas breakdown voltage is reached. The filamentary mode implies the emergence of electric current conducting channels (microdischarges), to add this phenomenon an RC circuit commutated by an ideal switch has been proposed. The switch activation occurs at a higher voltage level than the gas breakdown voltage because it is necessary to impose a huge electric field that contributes to the appearance of streamers. The model allows the estimation of several electric parameters inside the reactor that cannot be measured. Also, it is possible to appreciate the modes of the DBD depending on the applied voltage magnitude. Finally, it has been recognized a good agreement between simulation outcomes and experimental results.
Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator
Energy Technology Data Exchange (ETDEWEB)
Belinger, A; Cambronne, J P [Universite de Toulouse, UPS, INPT, LAPLACE - Laboratoire Plasma et Conversion d' Energie, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Hardy, P; Barricau, P; Caruana, D, E-mail: daniel.caruana@onera.fr [ONERA Centre Midi-Pyrenees, Departement Modeles pour l' Aerodynamique et l' Energetique, BP74025, 2 avenue Edouard Belin, 31055 TOULOUSE CEDEX 4 (France)
2011-09-14
A promising actuator for high-speed flow control, referred to as a plasma synthetic jet (PSJ), is being studied by the DMAE department of the ONERA, and the Laplace laboratory of the CNRS, in France. This actuator was inspired by the 'sparkjet' device developed by the Johns Hopkins University Applied Physics Laboratory. The PSJ, which produces a synthetic jet with high exhaust velocities, no active mechanical components and no mass flow admission, holds the promise of enabling high-speed flows to be manipulated. With this high-velocity jet it is possible to reduce fluid phenomena such as transition and turbulence, thus making it possible to increase an aircraft's performance whilst at the same time reducing its environmental impact. A thermal plasma discharge was created in a micro-cavity, causing the gas to be expelled. It is relevant that the velocity and momentum depend on the energy dispersed by the electric discharge. To control the frequency and energy dispersed in the plasma, the Laplace laboratory has developed two high-voltage power supply systems. These allow two different types of discharge to be produced, with energy being supplied to the discharge in two different manners. In this paper, we focus on the impact of the power supply on the plasma synthetic jet, and in particular on the role of the rate of energy dissipation in the discharge. In order to estimate the influence of the power supply on the machinery of the actuator, specific experimental techniques were used to investigate the electrical (voltage, current), thermal (Infra-red camera) and aerodynamic (jet duration, isentropic pressure, jet velocity) characteristics. These data sets were used to determine which of the two power supplies was more effective, thus allowing us to reach several conclusions concerning the importance of the energy dissipation rate on the PSJ actuator.
Pan, Feifei; Wang, Cheng; Xi, Xiaohuan
2016-09-01
Remote sensing from satellites and airborne platforms provides valuable data for monitoring and gauging river discharge. One effective approach first estimates river stage from satellite-measured inundation area based on the inundation area-river stage relationship (IARSR), and then the estimated river stage is used to compute river discharge based on the stage-discharge rating (SDR) curve. However, this approach is difficult to implement because of a lack of data for constructing the SDR curves. This study proposes a new method to construct the SDR curves using remotely sensed river cross-sectional inundation areas and river bathymetry. The proposed method was tested over a river reach between two USGS gauging stations, i.e., Kingston Mines (KM) and Copperas Creek (CC) along the Illinois River. First a polygon over each of two cross sections was defined. A complete IARSR curve was constructed inside each polygon using digital elevation model (DEM) and river bathymetric data. The constructed IARSR curves were then used to estimate 47 river water surface elevations at each cross section based on 47 river inundation areas estimated from Landsat TM images collected during 1994-2002. The estimated water surface elevations were substituted into an objective function formed by the Bernoulli equation of gradually varied open channel flow. A nonlinear global optimization scheme was applied to solve the Manning's coefficient through minimizing the objective function value. Finally the SDR curve was constructed at the KM site using the solved Manning's coefficient, channel cross sectional geometry and the Manning's equation, and employed to estimate river discharges. The root mean square error (RMSE) in the estimated river discharges against the USGS measured river discharges is 112.4 m3/s. To consider the variation of the Manning's coefficient in the vertical direction, this study also suggested a power-law function to describe the vertical decline of the Manning
Modeling of dielectric barrier discharge excimer lamp excited by mono polar voltage pulses
Akashi, Haruaki; Oda, Akinori; Sakai, Yosuke
2007-10-01
Filametal discharges in Dielectric Barrier Discharge (DBD) excimer lamp excited by mono polar voltage pulses has been simulated using two dimensional fluid model. And the differences of the filament discharges formations between mono polar case and bipolar case [1] have been examined. Xe gas was used and its pressure is 300Torr. Simulated region is 1cm (gap length) x 3cm (radial length). Periodical boundary conditions are assumed for the radial direction boundaries. The both electrodes are covered with dielectrics and their thickness is 0.2cm. Applied voltage is 5kV trapezoid shape with 50% duty ratio waveform and its repetition rate is 200kpps. First a small amount of electron-ion pair is provided in the middle of the gap for initial condition. Then the voltage starts to apply. In the case of bipolar excitation, the discharge starts from one filament (streamer discharge), and finally, 5 filaments are obtained self-consistently. In the case of mono polar case, as first, similar to bipolar case, the discharge starts from one filament, however, only 3 filaments have been obtained. This result is similar to that of 100kHz bipolar voltage case. [1] H. Akashi et al, IEEE Trans. Plasma Science, Vol.33, No.2 (2005) pp.308-309
Swanson, Patricia E.
2015-01-01
Elementary school mathematics is increasingly recognized for its crucial role in developing the foundational skills and understandings for algebra. In this article, the author uses a lesson to introduce the concept of "rates"--comparing two different types and units of measure--and how to graph them. Described is the lesson and shared…
Statistical modelling of discharge behavior of atmospheric pressure dielectric barrier discharge
Energy Technology Data Exchange (ETDEWEB)
Tay, W. H.; Kausik, S. S.; Wong, C. S., E-mail: cswong@um.edu.my; Yap, S. L.; Muniandy, S. V. [Plasma Technology Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia)
2014-11-15
In this work, stochastic behavior of atmospheric pressure dielectric barrier discharge (DBD) has been investigated. The experiment is performed in a DBD reactor consisting of a pair of stainless steel parallel plate electrodes powered by a 50 Hz ac high voltage source. Current pulse amplitude distributions for different space gaps and the time separation between consecutive current pulses are studied. A probability distribution function is proposed to predict the experimental distribution function for the current pulse amplitudes and the occurrence of the transition regime of the pulse distribution. Breakdown voltage at different positions on the dielectric surface is suggested to be stochastic in nature. The simulated results based on the proposed distribution function agreed well with the experimental results and able to predict the regime of transition voltage. This model would be useful for the understanding of stochastic behaviors of DBD and the design of DBD device for effective operation and applications.
2010-10-01
... 46 Shipping 4 2010-10-01 2010-10-01 false Pipe sizes and discharge rates for enclosed ventilation... Systems Fixed Carbon Dioxide Fire Extinguishing Systems § 108.437 Pipe sizes and discharge rates for enclosed ventilation systems for rotating electrical equipment. (a) The minimum pipe size for the initial...
Assessing modern rates of river sediment discharge to the ocean using satellite gravimetry
Mouyen, Maxime; Longuevergne, Laurent; Steer, Philippe; Crave, Alain; Lemoine, Jean-Michel; Save, Himanshu; Robin, Cécile
2017-04-01
Worldwide rivers annually export about 19 Gigatons of sediments to the ocean that mostly accumulate in the coastal zones and on the continental shelves. This sediment discharge testifies of the intensity of continental erosion and records changes in climate, tectonics and human activity. However, natural and instrumental uncertainties inherent to the in-situ measurements of sediment discharge prevent from conclusive estimates to better understand these linkages. Here we develop a new method, using the Gravity Recovery and Climate Experiment (GRACE) satellite data, to infer mass-integrative estimates of sediment discharge of large rivers to the ocean. GRACE satellite provides global gravity time series that have proven useful for quantifying mass transport, including continental water redistribution at the Earth surface (ice sheets and glaciers melting, groundwater storage variations) but has been seldom used for monitoring sediment mass transfers so far. Here we pair the analysis of regularized GRACE solutions at high spatial resolution corrected from all known contributions (hydrology, ocean, atmosphere) to a particle tracking model that predicts the location of the sediment sinks for 13 rivers with the highest sediments loads in the world. We find that the resulting GRACE-derived sediment discharges off the mouth of the Amazon, Ganges-Brahmaputra, Changjiang (Yangtze), Indus, Magdalena, Godavari and Mekong rivers are consistent with in-situ measurements. Our results suggest that the lack of time continuity and of global coverage in terrestrial sediment discharge measurements could be reduced by using GRACE, which provides global and continuous data since 2002. GRACE solutions are regularly improved and new satellite gravity missions are being prepared hence making our approach even more relevant in a near future. The accumulation of sediments over time will keep increasing the signal to noise ratio of the gravity time series, which will improve the precision of
Energy Technology Data Exchange (ETDEWEB)
Li, Tianjin, E-mail: tjli@tsinghua.edu.cn; Zhang, He; Liu, Malin; Huang, Zhiyong; Bo, Hanliang; Dong, Yujie
2017-04-01
Highlights: • The work concerns granular flow in a vertical pipe with a bend. • Discharge rate fluctuation in vertical pipe are mainly from velocity fluctuation. • Steady discharge rate decreases rapidly and saturates with μ{sub s} increasing. • Steady discharge rate W{sub s} still obey the 5/2 power law of pipe internal diameter. • A correlation developed for steady discharge rate for this new geometry. - Abstract: Absorber sphere pneumatic conveying is a special application of pneumatic conveying technique in the pebble bed High Temperature Gas-Cooled Reactor (HTGR or HTR). Granular discharge through a vertical pipe with a bend outlet is one of the control modes to determine solid mass flowrate which is an important parameter for the design of absorber sphere pneumatic conveying. Granular discharge rate through the vertical pipe with a bend outlet in the small absorber sphere system are investigated by discrete element method simulation. The effect of geometry parameters on discharge rate, the discharge rate fluctuation in the vertical pipe, and the effect of friction on steady discharge rate (W{sub s}) are analyzed and discussed. The phenomena of discharge rate fluctuation in the vertical pipe are observed, which are mainly resulted from the evolution of the average downward granular velocity. The steady discharge rate decreases rapidly with sliding friction coefficient increasing from 0.125 to 0.5, and gradually saturates with the friction coefficient further increasing from 0.5 to 1. It is interesting that the linear relation between W{sub s}{sup 2/5} and pipe internal diameter D with zero intercept are found for the vertical pipe discharge with a bend outlet, which is different from the orifice discharge through a hopper or silo with none-zero intercept. A correlation similar to Beverloo’s correlation is developed to predict the steady discharge rate through the vertical pipe with a bend outlet. These results are helpful for the design of sphere
Effect of Electric Discharge Machining on Material Removal Rate and White Layer Composition
Directory of Open Access Journals (Sweden)
SHAHID MEHMOOD
2017-01-01
Full Text Available In this study the MRR (Material Removal Rate of the aerospace grade (2024 T6 aluminum alloy 2024 T6 has been determined with copper electrode and kerosene oil is used as dielectric liquid. Discharge energy is controlled by electric current while keeping Pulse-ON time and Pulse-OFF time as constant. The characteristics of the EDMed (Electric Discharge Machined surface are discussed. The sub-surface defect due to arcing has been explained. As the surface material of tool electrode and workpiece melts simultaneously and there are chances of the contamination of both surfaces by the contents of each other. Therefore, the EDS (Energy Dispersive Spectroscopy of the white layer and base material of the workpiece was performed by SEM (Scanning Electron Microscope at the discharge currents of 3, 6 and 12 amperes. It was conformed that the contamination of the surface of the workpiece material occurred by carbon, copper and oxygen contents. The quantitative analysis of these contents with respect to the discharge current has been presented in this paper.
Computational modeling of glow discharge-induced fluid dynamics
Jayaraman, Balaji
Glow discharge at atmospheric pressure using a dielectric barrier discharge can induce fluid flow and operate as an actuator for flow control. The largely isothermal surface plasma generation realized above can modify the near-wall flow structure by means of Lorentzian collisions between the ionized fluid and the neutral fluid. Such an actuator has advantages of no moving parts, performance at atmospheric conditions and devising complex control strategies through the applied voltage. However, the mechanism of the momentum coupling between the plasma and the fluid flow is not yet adequately understood. In the present work, a modeling framework is presented to simulate athermal, non-equilibrium plasma discharges in conjunction with low Mach number fluid dynamics at atmospheric pressure. The plasma and fluid species are treated as a two-fluid system exhibiting a few decades of length and time scales. The effect of the plasma dynamics on the fluid dynamics is devised via a body force treatment in the Navier-Stokes equations. Two different approaches of different degrees of fidelity are presented for modeling the plasma dynamics. The first approach, a phenomenological model, is based on a linearized force distribution approximating the discharge structure, and utilizing experimental guidance to deduce the empirical constants. A high fidelity approach is to model the plasma dynamics in a self-consistent manner using a first principle-based hydrodynamic plasma model. The atmospheric pressure regime of interest here enables us to employ local equilibrium assumptions, signifying efficient collisional energy exchange as against thermal heating from inelastic collision processes. The time scale ratios between convection, diffusion, and reaction/ionization mechanisms are O(107), making the system computationally stiff. To handle the stiffness, a sequential finite-volume operator-splitting algorithm capable of conserving space charge is developed; the approach can handle time
Modeling terrestrial gamma ray flashes produced by relativistic feedback discharges
Liu, Ningyu; Dwyer, Joseph R.
2013-05-01
This paper reports a modeling study of terrestrial gamma ray flashes (TGFs) produced by relativistic feedback discharges. Terrestrial gamma ray flashes are intense energetic radiation originating from the Earth's atmosphere that has been observed by spacecraft. They are produced by bremsstrahlung interactions of energetic electrons, known as runaway electrons, with air atoms. An efficient physical mechanism for producing large fluxes of the runaway electrons to make the TGFs is the relativistic feedback discharge, where seed runaway electrons are generated by positrons and X-rays, products of the discharge itself. Once the relativistic feedback discharge becomes self-sustaining, an exponentially increasing number of relativistic electron avalanches propagate through the same high-field region inside the thundercloud until the electric field is partially discharged by the ionization created by the discharge. The modeling results indicate that the durations of the TGF pulses produced by the relativistic feedback discharge vary from tens of microseconds to several milliseconds, encompassing all durations of the TGFs observed so far. In addition, when a sufficiently large potential difference is available in thunderclouds, a self-propagating discharge known as the relativistic feedback streamer can be formed, which propagates like a conventional positive streamer. For the relativistic feedback streamer, the positive feedback mechanism of runaway electron production by the positrons and X-rays plays a similar role as the photoionization for the conventional positive streamer. The simulation results of the relativistic feedback streamer show that a sequence of TGF pulses with varying durations can be produced by the streamer. The relativistic streamer may initially propagate with a pulsed manner and turn into a continuous propagation mode at a later stage. Milliseconds long TGF pulses can be produced by the feedback streamer during its continuous propagation. However
Numerical modeling of ozone production in a pulsed homogeneous discharge: A parameter study
Energy Technology Data Exchange (ETDEWEB)
Nilsson, J.O.; Eninger, J.E. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Industrial Electrotechnology
1997-02-01
The pulsed volume discharge is an alternative for the efficient generation of ozone in compact systems. This paper presents a parameter study of the reactions in this kind of homogeneous discharge by using a numerical model which solves plasma chemical kinetic rate and energy equations. Results are presented of ozone generation efficiency versus ozone concentration for different parameter combinations. Two parameter regimes are identified and analyzed. In the plasma phase ozone formation regime, where significant amounts of ozone are produced during the discharge pulse, it is found that higher ozone concentrations can be obtained than in the neutral phase ozone formation regime, where most of the ozone is formed after the discharge pulse. In the two-step ozone formation process, the rate of conversion of atomic oxygen plays a key role. In both regimes the ozone generation efficiency increases as n is increased or T{sub 0} decreased. The maximum concentration is 3% at 10 amagat and 100 K. The results on ozone accumulation in multiple pulse discharges are presented. In contrast to the single pulse case, higher efficiency is achieved at lower gas density. This scaling can be explained by losses due to ion currents. A tradeoff can be made between ozone generation efficiency and the number of pulses required to reach a certain concentration.
Flow Rate in the Discharge of a Two-dimensional Silo
Zuriguel, I.; Janda, A.; Garcimartín, A.; Maza, D.
2009-06-01
We present an experimental study of the flow rate in the discharge of a flat bottomed two-dimensional silo. The results of the flow rate dependence on the size of the orifice evidence that the Beverloo expression is not valid for small outlet sizes. This behavior is related with the properties of the flow rate which has been found to fluctuate in a gaussian like form for large orifices. On the contrary, for small orifices extreme events appear at zero flow rates causing a significant slow down of the average flow rate. These events are explained in terms of the existence of arches that block the outlet instantaneously but are unstable to permanently halt the flow.
Liu, Ruiqiang; Liu, Yue; Jia, Wenzhu; Zhou, Yanwen
2017-01-01
Based on the plasma fluid theory and using the drift-diffusion approximation, a mathematical model for continuous and pulsed radial frequency (RF) argon capacitive glow discharges at low pressure is established. The model is solved by a finite difference method and the numerical results are reported. Based on the systematic analysis of the results, plasma characteristics of the continuous and pulsed RF discharges are comparatively investigated. It is shown that, under the same condition for the peak value of the driving potential, the cycle-averaged electron density, the current density, and other essential physical quantities in the continuous RF discharge are higher than those from the pulsed RF discharge. On the other hand, similar plasma characteristics are obtained with two types of discharges, by assuming the same deposited power. Consequently, higher driving potential is needed in pulsed discharges in order to maintain the same effective plasma current. Furthermore, it is shown that, in the bulk plasma region, the peak value of the bipolar electric field from the continuous RF discharge is greater than that from the pulsed RF discharge. In the sheath region, the ionization rate has the shape of double-peaking and the explanation is given. Because the plasma input power depends on the driving potential and the plasma current phase, the phase differences between the driving potential and the plasma current are compared between the continuous and the pulsed RF discharges. It is found that this phase difference is smaller in the pulsed RF discharge compared to that of the continuous RF discharge. This means that the input energy coupling in the pulsed RF discharge is less efficient than the continuous counterpart. This comparative study, carried out also under other conditions, thus can provide instructive ideas in applications using the continuous and pulsed RF capacitive glow discharges.
Motor unit discharge rate in dynamic movements of the aging soleus
DEFF Research Database (Denmark)
Kallio, Jouni; Søgaard, Karen; Avela, Janne
2014-01-01
% in concentric (CON) and eccentric (ECC) contractions. Soleus intramuscular EMG was recorded with bipolar fine-wire electrodes and decomposed to individual trains of motor unit discharges. In ISO the MUDR increased with each force level from 40 to 100% MVC. In dynamic contractions the descriptive analysis showed......Aging is related to a variety of changes at the muscular level. It seems that the age-related changes in motor unit activation are muscle- and intensity dependent. The purpose of this study was to examine the motor unit discharge rate (MUDR) in both isometric and dynamic contractions of the aging...... a higher MUDR in CON compared to ISO or ECC. The difficulties of recording single motor units in dynamic contractions, especially in the elderly is discussed....
Energy Technology Data Exchange (ETDEWEB)
Welland, Michael J.; Lau, Kah Chun; Redfern, Paul C.; Wolf, Dieter; Curtiss, Larry A., E-mail: curtiss@anl.gov [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liang, Linyun [Mathematics and Computer Science, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zhai, Denyun [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2015-12-14
An atomistically informed mesoscale model is developed for the deposition of a discharge product in a Li-O{sub 2} battery. This mescocale model includes particle growth and coarsening as well as a simplified nucleation model. The model involves LiO{sub 2} formation through reaction of O{sub 2}{sup −} and Li{sup +} in the electrolyte, which deposits on the cathode surface when the LiO{sub 2} concentration reaches supersaturation in the electrolyte. A reaction-diffusion (rate-equation) model is used to describe the processes occurring in the electrolyte and a phase-field model is used to capture microstructural evolution. This model predicts that coarsening, in which large particles grow and small ones disappear, has a substantial effect on the size distribution of the LiO{sub 2} particles during the discharge process. The size evolution during discharge is the result of the interplay between this coarsening process and particle growth. The growth through continued deposition of LiO{sub 2} has the effect of causing large particles to grow ever faster while delaying the dissolution of small particles. The predicted size evolution is consistent with experimental results for a previously reported cathode material based on activated carbon during discharge and when it is at rest, although kinetic factors need to be included. The approach described in this paper synergistically combines models on different length scales with experimental observations and should have applications in studying other related discharge processes, such as Li{sub 2}O{sub 2} deposition, in Li-O{sub 2} batteries and nucleation and growth in Li-S batteries.
Energy Technology Data Exchange (ETDEWEB)
Welland, Michael J. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Lau, Kah Chun [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Redfern, Paul C. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Liang, Linyun [Mathematics and Computer Science, Argonne National Laboratory, Argonne, Illinois 60439, USA; Zhai, Denyun [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Wolf, Dieter [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA; Curtiss, Larry A. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
2015-12-14
An atomistically informed mesoscale model is developed for the deposition of a discharge product in a Li-O-2 battery. This mescocale model includes particle growth and coarsening as well as a simplified nucleation model. The model involves LiO2 formation through reaction of O-2(-) and Li+ in the electrolyte, which deposits on the cathode surface when the LiO2 concentration reaches supersaturation in the electrolyte. A reaction-diffusion (rate-equation) model is used to describe the processes occurring in the electrolyte and a phase-field model is used to capture microstructural evolution. This model predicts that coarsening, in which large particles grow and small ones disappear, has a substantial effect on the size distribution of the LiO2 particles during the discharge process. The size evolution during discharge is the result of the interplay between this coarsening process and particle growth. The growth through continued deposition of LiO2 has the effect of causing large particles to grow ever faster while delaying the dissolution of small particles. The predicted size evolution is consistent with experimental results for a previously reported cathode material based on activated carbon during discharge and when it is at rest, although kinetic factors need to be included. The approach described in this paper synergistically combines models on different length scales with experimental observations and should have applications in studying other related discharge processes, such as Li2O2 deposition, in Li-O-2 batteries and nucleation and growth in Li-S batteries.
Modelling the fate of the Tijuana River discharge plume
van Ormondt, M.; Terrill, E.; Hibler, L. F.; van Dongeren, A. R.
2010-12-01
After rainfall events, the Tijuana River discharges excess runoff into the ocean in a highly turbid plume. The runoff waters contain large suspended solids concentrations, as well as high levels of toxic contaminants, bacteria, and hepatitis and enteroviruses. Public health hazards posed by the effluent often result in beach closures for several kilometers northward along the U.S. shoreline. A Delft3D model has been set up to predict the fate of the Tijuana River plume. The model takes into account the effects of tides, wind, waves, salinity, and temperature stratification. Heat exchange with the atmosphere is also included. The model consists of a relatively coarse outer domain and a high-resolution surf zone domain that are coupled with Domain Decomposition. The offshore boundary conditions are obtained from the larger NCOM SoCal model (operated by the US Navy) that spans the entire Southern California Bight. A number of discharge events are investigated, in which model results are validated against a wide range of field measurements in the San Diego Bight. These include HF Radar surface currents, REMUS tracks, drifter deployments, satellite imagery, as well as current and temperature profile measurements at a number of locations. The model is able to reproduce the observed current and temperature patterns reasonably well. Under calm conditions, the model results suggest that the hydrodynamics in the San Diego Bight are largely governed by internal waves. During rainfall events, which are typically accompanied by strong winds and high waves, wind and wave driven currents become dominant. An analysis will be made of what conditions determine the trapping and mixing of the plume inside the surfzone and/or the propagation of the plume through the breakers and onto the coastal shelf. The model is now also running in operational mode. Three day forecasts are made every 24 hours. This study was funded by the Office of Naval Research.
DEFF Research Database (Denmark)
Kallio, J; Søgaard, Karen; Avela, J
2012-01-01
Aging is related to multiple changes in muscle physiology and function. Previous findings concerning the effects of aging on motor unit discharge rate (DR) and fluctuations in DR and force are somewhat contradictory. Eight YOUNG and nine OLD physically active males performed isometric ramp (RECR......) and isotonic (ISO) plantar flexions at 10 and 20% of surface EMG at MVC. Motor unit (MU) action potentials were recorded with intramuscular fine-wire electrodes and decomposed with custom build software "Daisy". DR was lower in OLD in RECR-10% (17.9%, p...
DEFF Research Database (Denmark)
Guan, Yajuan; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.
2016-01-01
incidents and unintentional outages in DG units, but also aims to provide a fast transient response and an accurate output-current-sharing performance. A complete root locus analysis is given in order to achieve system stability and parameter sensitivity. Experimental results are presented to show......A coordinated secondary control approach based on an autonomous current-sharing control strategy for balancing the discharge rates of energy storage systems (ESSs) in islanded AC microgrids is proposed in this paper. The coordinated secondary controller can regulate the power outputs of distributed...... the performance of the whole system and to verify the effectiveness of the proposed controller....
Plutonium Discharge Rates and Spent Nuclear Fuel Inventory Estimates for Nuclear Reactors Worldwide
Energy Technology Data Exchange (ETDEWEB)
Brian K. Castle; Shauna A. Hoiland; Richard A. Rankin; James W. Sterbentz
2012-09-01
This report presents a preliminary survey and analysis of the five primary types of commercial nuclear power reactors currently in use around the world. Plutonium mass discharge rates from the reactors’ spent fuel at reload are estimated based on a simple methodology that is able to use limited reactor burnup and operational characteristics collected from a variety of public domain sources. Selected commercial reactor operating and nuclear core characteristics are also given for each reactor type. In addition to the worldwide commercial reactors survey, a materials test reactor survey was conducted to identify reactors of this type with a significant core power rating. Over 100 material or research reactors with a core power rating >1 MW fall into this category. Fuel characteristics and spent fuel inventories for these material test reactors are also provided herein.
Modelling Australia's Retail Mortgage Rate
Abbas Valadkhani; Sajid Anwar
2012-01-01
There is an ongoing controversy over whether banks’ mortgage rates rise more readily than they fall due to their asymmetric responses to changes in the cash rate. This paper examines the dynamic interplay between the cash rate and the variable mortgage rate using monthly data in the post-1989 era. Unlike previous studies for Australia, our proposed threshold and asymmetric error-correction models account for both the amount and adjustment asymmetries. We found thatrate rises have much larger ...
Miyazu, Susumu; Yasutaka, Tetsuo; Yoshikawa, Natsuki; Tamaki, Shouhei; Nakajima, Kousei; Sato, Iku; Nonaka, Masanori; Harada, Naoki
2016-05-01
In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation.
Large Scale Modelling of Glow Discharges or Non - Plasmas
Shankar, Sadasivan
The Electron Velocity Distribution Function (EVDF) in the cathode fall of a DC helium glow discharge was evaluated from a numerical solution of the Boltzmann Transport Equation(BTE). The numerical technique was based on a Petrov-Galerkin technique and a unique combination of streamline upwinding with self -consistent feedback-based shock-capturing. EVDF for the cathode fall was solved at 1 Torr, as a function of position x, axial velocity v_{rm x}, radial velocity v_{rm r}, and time t. The electron-neutral collisions consisted of elastic, excitation, and ionization processes. The algorithm was optimized and vectorized to speed execution by more than a factor of 10 on CRAY-XMP. Efficient storage schemes were used to save the memory allocation required by the algorithm. The analysis of the solution of BTE was done in terms of the 8-moments that were evaluated. Higher moments were found necessary to study the momentum and energy fluxes. The time and length scales were estimated and used as a basis for the characterization of DC glow discharges. Based on an exhaustive study of Knudsen numbers, it was observed that the electrons in the cathode fall were in the transition or Boltzmann regime. The shortest relaxation time was the momentum relaxation and the longest times were the ionization and energy relaxation times. The other times in the processes were that for plasma reaction, diffusion, convection, transit, entropy relaxation, and that for mean free flight between the collisions. Different models were classified based on the moments, time scales, and length scales in their applicability to glow discharges. These consisted of BTE with different number af phase and configuration dimensions, Bhatnagar-Gross-Krook equation, moment equations (e.g. Drift-Diffusion, Drift-Diffusion-Inertia), and spherical harmonic expansions.
Barnwal, S.; Nigam, S.; Aneesh, K.; Prasad, Y. B. S. R.; Naik, P. A.; Navathe, C. P.; Gupta, P. D.
2016-06-01
The rate of rise in discharge current (d I/d t) is an important parameter in an X-ray laser pumped by fast capillary discharge. The effect of this parameter on the energy of an argon plasma-based 46.9-nm soft X-ray laser pulse has been experimentally studied. It was found that an X-ray laser pulse with ~2 μJ energy, which can be obtained at a discharge current of ~40 kA with d I/d t value of ~7.1 × 1011 A/s, can also be obtained at a much lower peak current of ~26 kA if the quarter period ( T/4) of the discharge current is made shorter to achieve a comparable d I/d t value. For a fixed T/4, the laser energy could be enhanced from 2 to 4 μJ for an increase in the d I/d t value from 7.1 × 1011 to 1.3 × 1012 A/s by increasing the peak current from 26 to 44 kA. It was also observed that for a fixed d I/d t, mere increase in the discharge current does not increase the laser energy.
Dolin, Rachel; Holmes, G Mark; Stearns, Sally C; Kirk, Denise A; Hanson, Laura C; Taylor, Donald H; Silberman, Pam
2017-07-01
Hospice care is designed to support patients and families through the final phase of illness and death. Yet for more than a decade, hospices have steadily increased the rate at which they discharge patients before death-a practice known as "live discharge." Although certain live discharges are consistent with high-quality care, regulators have expressed concern that some hospices' desire to maximize profits drives them to inappropriately discharge patients. We used Medicare claims data for 2012-13 and cost reports for 2011-13 to explore relationships between hospice-level financial margins and live discharge rates among freestanding hospices. Adjusted analyses showed positive and significant associations between both operating and total margins and hospice-level rates of live discharge: One-unit increases in operating and total margin were associated with increases of 3 percent and 4 percent in expected hospice-level live discharge rates, respectively. These findings suggest that additional research is needed to explore links between profitability and patient-centeredness in the Medicare hospice program. Project HOPE—The People-to-People Health Foundation, Inc.
Slow electron energy balance for hybrid models of direct-current glow discharges
Eliseev, S. I.; Bogdanov, E. A.; Kudryavtsev, A. A.
2017-09-01
In this paper, we present the formulation of slow electron energy balance for hybrid models of direct current (DC) glow discharge. Electrons originating from non-local ionization (secondary) contribute significantly to the energy balance of slow electrons. An approach towards calculating effective energy brought by a secondary electron to the group of slow electrons by means of Coulomb collisions is suggested. The value of effective energy shows a considerable dependence on external parameters of a discharge, such as gas pressure, type, and geometric parameters. The slow electron energy balance was implemented into a simple hybrid model that uses analytical formulation for the description of non-local ionization by fast electrons. Simulations of short (without positive column) DC glow discharge in argon are carried out for a range of gas pressures. Comparison with experimental data showed generally good agreement in terms of current-voltage characteristics, electron density, and electron temperature. Simulations also capture the trend of increasing electron density with decreasing pressure observed in the experiment. Analysis shows that for considered conditions, the product of maximum electron density ne and electron temperature Te in negative glow is independent of gas pressure and depends on the gas type, cathode material, and discharge current. Decreasing gas pressure reduces the heating rate of slow electrons during Coulomb collisions with secondary electrons, which leads to lower values of Te and, in turn, higher maximum ne.
Electrostatic modelling of dual frequency rf plasma discharges
Energy Technology Data Exchange (ETDEWEB)
Boyle, P C; Ellingboe, A R; Turner, M M [Plasma Research Laboratory, National Centre for Plasma Science and Technology and School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)
2004-08-01
Particle-in-cell simulations have been used to study the nature of dual frequency plasma discharges. It is observed that both the ion flux on to the electrodes and the ion bombardment energy on to the electrodes can be controlled independently. There are two separate regimes in which this occurs. At large electrode separation, the ion current is controlled by varying the total discharge current, J{sub lf} + J{sub hf}. At small electrode separations, the ion flux can be controlled by varying the high frequency power source. In both regimes, the energy of the ions bombarding the electrodes is then determined by the low frequency voltage. A consequence of using dual frequencies to power the device is that the sheath width increases linearly as the low frequency power source is increased. This results in the dimensions of the bulk plasma decreasing, causing the electron temperature to increase for devices with electrode separations that are of comparable size to the electrode separation. In order to better understand the underlying physics involved within these devices an analytical global model has been developed which can explain many of the characteristics observed in the simulations.
The relativistic feedback discharge model of terrestrial gamma ray flashes
Dwyer, Joseph R.
2012-02-01
As thunderclouds charge, the large-scale fields may approach the relativistic feedback threshold, above which the production of relativistic runaway electron avalanches becomes self-sustaining through the generation of backward propagating runaway positrons and backscattered X-rays. Positive intracloud (IC) lightning may force the large-scale electric fields inside thunderclouds above the relativistic feedback threshold, causing the number of runaway electrons, and the resulting X-ray and gamma ray emission, to grow exponentially, producing very large fluxes of energetic radiation. As the flux of runaway electrons increases, ionization eventually causes the electric field to discharge, bringing the field below the relativistic feedback threshold again and reducing the flux of runaway electrons. These processes are investigated with a new model that includes the production, propagation, diffusion, and avalanche multiplication of runaway electrons; the production and propagation of X-rays and gamma rays; and the production, propagation, and annihilation of runaway positrons. In this model, referred to as the relativistic feedback discharge model, the large-scale electric fields are calculated self-consistently from the charge motion of the drifting low-energy electrons and ions, produced from the ionization of air by the runaway electrons, including two- and three-body attachment and recombination. Simulation results show that when relativistic feedback is considered, bright gamma ray flashes are a natural consequence of upward +IC lightning propagating in large-scale thundercloud fields. Furthermore, these flashes have the same time structures, including both single and multiple pulses, intensities, angular distributions, current moments, and energy spectra as terrestrial gamma ray flashes, and produce large current moments that should be observable in radio waves.
Discharge processes and an electrical model of atmospheric pressure plasma jets in argon
Fang, Zhi; Shao, Tao; Yang, Jing; Zhang, Cheng
2016-01-01
In this paper, an atmospheric pressure plasma discharge in argon was generated using a needle-to-ring electrode configuration driven by a sinusoidal excitation voltage. The electric discharge processes and discharge characteristics were investigated by inspecting the voltage-current waveforms, Lissajous curves and lighting emission images. The change in discharge mode with applied voltage amplitude was studied and characterised, and three modes of corona discharge, dielectric barrier discharge (DBD) and jet discharge were identified, which appeared in turn with increasing applied voltage and can be distinguished clearly from the measured voltage-current waveforms, light-emission images and the changing gradient of discharge power with applied voltage. Based on the experimental results and discharge mechanism analysis, an equivalent electrical model and the corresponding equivalent circuit for characterising the whole discharge processes accurately was proposed, and the three discharge stages were characterised separately. A voltage-controlled current source (VCCS) associated with a resistance and a capacitance were used to represent the DBD stage, and the plasma plume and corona discharge were modelled by a variable capacitor in series with a variable resistor. Other factors that can influence the discharge, such as lead and stray capacitance values of the circuit, were also considered in the proposed model. Contribution to the Topical Issue "Recent Breakthroughs in Microplasma Science and Technology", edited by Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu.
Maeda, Jared Lane K; Henke, Rachel Mosher; Marder, William D; Karaca, Zeynal; Friedman, Bernard S; Wong, Herbert S
2014-10-13
Several reports have linked the 2007-2009 Great Recession in the United States with a slowdown in health care spending and decreased utilization. However, little is known regarding how the recent economic downturn affected hospital costs per inpatient stay for different segments of the population. The purpose of this study was to examine the association between changes in the unemployment rate and inpatient cost per discharge for Medicare and commercial discharges. We used retrospective data at the Core Based Statistical Area (CBSA)-level from 46 states that contributed to the Healthcare Cost and Utilization Project State Inpatient Databases from 2005 to 2010. Unemployment data was derived from the American Community Survey. An instrumental variable two-stage least squares approach with fixed- or random-effects was used to examine the association between unemployment rate and inpatient cost per discharge by payer because of potential endogeneity. The marginal effect of unemployment was associated with an increase in inpatient cost per discharge for both payers. A one percentage point increase in the unemployment rate was associated with a $37 increase for commercial discharges and a $49 increase for Medicare discharges. We find evidence that the inpatient cost per discharge is countercyclical across different segments of the population. The underlying mechanisms by which unemployment affects hospital resource use however, might differ between payer groups.
Tillaart, van den S.P.M.; Booij, M.J.; Krol, M.S
2013-01-01
Uncertainties in discharge determination may have serious consequences for hydrological modelling and resulting discharge predictions used for flood forecasting, climate change impact assessment and reservoir operation. The aim of this study is to quantify the effect of discharge errors on parameter
Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C
2007-07-26
Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.
Ike, Innocent S.; Sigalas, Iakovos; Iyuke, Sunny E.
2017-02-01
The effects of self-discharge on the performance of symmetric electric double-layer capacitors (EDLCs) and active electrolyte-enhanced supercapacitors were examined by incorporating self-discharge into electrochemical capacitor models during charging and discharging. The sources of self-discharge in capacitors were side reactions or redox reactions and several impurities and electric double-layer (EDL) instability. The effects of self-discharge during capacitor storage was negligible since it took a fully charged capacitor a minimum of 14.0 days to be entirely discharged by self-discharge in all conditions studied, hence self-discharge in storage condition can be ignored. The first and second charge-discharge cycle energy efficiencies η_{{{{E}}1}} and η_{{{{E}}2}} of a capacitor of electrode effective conductivity α1 = 0.05 S/cm with only EDL instability self-discharge with current density J_{{VR}} = 1.25 × 10-3 A/cm2 were 72.33% and 72.34%, respectively. Also, energy efficiencies η_{{{{E}}1}} and η_{{{{E}}2}} of a similar capacitor with both side reactions and redox reactions and EDL instability self-discharges with current densities J_{{VR}} = 0.00125 A/cm2 and J_{{{{VR}}1}} = 0.0032 A/cm2 were 38.13% and 38.14% respectively, compared with 84.24% and 84.25% in a similar capacitor without self-discharge. A capacitor with only EDL instability self-discharge and that with both side reactions and redox reactions and EDL instability self-discharge lost 9.73 Wh and 28.38 Wh of energy, respectively, through self-discharge during charging and discharging. Hence, EDLCs charging and discharging time is significantly dependent on the self-discharge rate which are too large to be ignored.
River Discharge Estimation by Using Altimetry Data and Simplified Flood Routing Modeling
Directory of Open Access Journals (Sweden)
Tommaso Moramarco
2013-08-01
Full Text Available A methodology to estimate the discharge along rivers, even poorly gauged ones, taking advantage of water level measurements derived from satellite altimetry is proposed. The procedure is based on the application of the Rating Curve Model (RCM, a simple method allowing for the estimation of the flow conditions in a river section using only water levels recorded at that site and the discharges observed at another upstream section. The European Remote-Sensing Satellite 2, ERS-2, and the Environmental Satellite, ENVISAT, altimetry data are used to provide time series of water levels needed for the application of RCM. In order to evaluate the usefulness of the approach, the results are compared with the ones obtained by applying an empirical formula that allows discharge estimation from remotely sensed hydraulic information. To test the proposed procedure, the 236 km-reach of the Po River is investigated, for which five in situ stations and four satellite tracks are available. Results show that RCM is able to appropriately represent the discharge, and its performance is better than the empirical formula, although this latter does not require upstream hydrometric data. Given its simple formal structure, the proposed approach can be conveniently utilized in ungauged sites where only the survey of the cross-section is needed.
Modeling the variability of firing rate of retinal ganglion cells.
Levine, M W
1992-12-01
Impulse trains simulating the maintained discharges of retinal ganglion cells were generated by digital realizations of the integrate-and-fire model. If the mean rate were set by a "bias" level added to "noise," the variability of firing would be related to the mean firing rate as an inverse square root law; the maintained discharges of retinal ganglion cells deviate systematically from such a relationship. A more realistic relationship can be obtained if the integrate-and-fire mechanism is "leaky"; with this refinement, the integrate-and-fire model captures the essential features of the data. However, the model shows that the distribution of intervals is insensitive to that of the underlying variability. The leakage time constant, threshold, and distribution of the noise are confounded, rendering the model unspecifiable. Another aspect of variability is presented by the variance of responses to repeated discrete stimuli. The variance of response rate increases with the mean response amplitude; the nature of that relationship depends on the duration of the periods in which the response is sampled. These results have defied explanation. But if it is assumed that variability depends on mean rate in the way observed for maintained discharges, the variability of responses to abrupt changes in lighting can be predicted from the observed mean responses. The parameters that provide the best fits for the variability of responses also provide a reasonable fit to the variability of maintained discharges.
Particle-in-cell modeling of gas-confined barrier discharge
Levko, Dmitry; Raja, Laxminarayan L.
2016-04-01
Gas-confined barrier discharge is studied using the one-dimensional Particle-in-Cell Monte Carlo Collisions model for the conditions reported by Guerra-Garcia and Martinez-Sanchez [Appl. Phys. Lett. 106, 041601 (2015)]. Depending on the applied voltage, two modes of discharge are observed. In the first mode, the discharge develops in the entire interelectrode gap. In the second mode, the discharge is ignited and develops only in the gas layer having smaller breakdown voltage. The one-dimensional model shows that for the conditions considered, there is no streamer stage of breakdown as is typical for a traditional dielectric barrier discharge.
Particle-in-cell modeling of gas-confined barrier discharge
Energy Technology Data Exchange (ETDEWEB)
Levko, Dmitry; Raja, Laxminarayan L. [Department of Aerospace Engineering and Engineering Mechanics, The University of Texas at Austin, Austin, Texas 78712 (United States)
2016-04-15
Gas-confined barrier discharge is studied using the one-dimensional Particle-in-Cell Monte Carlo Collisions model for the conditions reported by Guerra-Garcia and Martinez-Sanchez [Appl. Phys. Lett. 106, 041601 (2015)]. Depending on the applied voltage, two modes of discharge are observed. In the first mode, the discharge develops in the entire interelectrode gap. In the second mode, the discharge is ignited and develops only in the gas layer having smaller breakdown voltage. The one-dimensional model shows that for the conditions considered, there is no streamer stage of breakdown as is typical for a traditional dielectric barrier discharge.
Directory of Open Access Journals (Sweden)
J. A. Colman
2005-01-01
Full Text Available Submarine groundwater discharge was quantified by a variety of methods in Salt Pond, adjacent to Nauset Marsh on Cape Cod, USA. Discharge estimates based on radon and salinity took advantage of the presence of the narrow channel connecting Salt Pond to Nauset Marsh, which allowed constructing whole-pond mass balances as water flowed in and out due to tidal fluctuations. A box model was used to estimate discharge separately to Salt Pond and to the channel by simulating the timing and magnitude of variations in the radon and salinity data in the channel. Discharge to the pond is estimated to be 2200±1100 m3d-1, while discharge to the channel is estimated to be 300±150 m3d-1, for a total discharge of 2500±1250 m3d-1 to the Salt Pond system. This translates to an average groundwater flow velocity of 3±1.5 cm d-1 Seepage meter flow estimates are broadly consistent with this figure, provided discharge is confined to shallow sediments (water depth 3d-1 predicted by a recent hydrologic model (Masterson, 2004; Colman and Masterson, 2004. Additional work is needed to determine if the measured rate of discharge is representative of the long-term average, and to determine the rate of groundwater discharge seaward of Salt Pond. Data also suggest a TDN flux from groundwater to Salt Pond of ~2.6 mmol m-2d-1, a figure comparable to fluxes observed in other eutrophic settings.
Botelho, D A; Barry, M E; Collecutt, G C; Brook, J; Wiltshire, D
2013-01-01
A desalination plant is proposed to be the major water supply to the Olympic Dam Expansion Mining project. Located in the Upper Spencer Gulf, South Australia, the site was chosen due to the existence of strong currents and their likely advantages in terms of mixing and dilution of discharged return water. A high-resolution hydrodynamic model (Estuary, Lake and Coastal Ocean Model, ELCOM) was constructed and, through a rigorous review process, was shown to reproduce the intricate details of the Spencer Gulf dynamics, including those characterising the discharge site. Notwithstanding this, it was found that deploying typically adopted 'direct insertion' techniques to simulate the brine discharge within the hydrodynamic model was problematic. Specifically, it was found that in this study the direct insertion technique delivered highly conservative brine dilution predictions in and around the proposed site, and that these were grid and time-step dependent. To improve the predictive capability, a strategy to link validated computational fluid dynamics (CFD) predictions to hydrodynamic simulations was devised. In this strategy, environmental conditions from ELCOM were used to produce boundary conditions for execution of a suite of CFD simulations. In turn, the CFD simulations provided the brine dilutions and flow rates to be applied in ELCOM. In order to conserve mass in a system-wide sense, artificial salt sinks were introduced to the ELCOM model such that salt quantities were conserved. As a result of this process, ELCOM predictions were naturally very similar to CFD predictions near the diffuser, whilst at the same time they produced an area of influence (further afield) comparable to direct insertion methods. It was concluded that the linkage of the models, in comparison to direct insertion methods, constituted a more realistic and defensible alternative to predict the far-field dispersion of outfall discharges, particularly with regards to the estimation of brine
Impact Of Particle Agglomeration On Accumulation Rates In The Glass Discharge Riser Of HLW Melter
Energy Technology Data Exchange (ETDEWEB)
Kruger, A. A. [Department of Energy, Office of River Protection, Richland, WA (United States); Rodriguez, C. A. [Pacific Northwest National Laboratory, Richland, WA (United States); Matyas, J. [Pacific Northwest National Laboratory, Richland, WA (United States); Owen, A. T. [Pacific Northwest National Laboratory, Richland, WA (United States); Jansik, D. P. [Pacific Northwest National Laboratory, Richland, WA (United States); Lang, J. B. [Pacific Northwest National Laboratory, Richland, WA (United States)
2012-11-12
The major factor limiting waste loading in continuous high-level radioactive waste (HLW) melters is an accumulation of particles in the glass discharge riser during a frequent and periodic idling of more than 20 days. An excessive accumulation can produce robust layers a few centimeters thick, which may clog the riser, preventing molten glass from being poured into canisters. Since the accumulation rate is driven by the size of particles we investigated with x-ray microtomography, scanning electron microscopy, and image analysis the impact of spinel forming components, noble metals, and alumina on the size, concentration, and spatial distribution of particles, and on the accumulation rate. Increased concentrations of Fe and Ni in the baseline glass resulted in the formation of large agglomerates that grew over the time to an average size of ~185+-155 {mu}m, and produced >3 mm thick layer after 120 h at 850 deg C. The noble metals decreased the particle size, and therefore significantly slowed down the accumulation rate. Addition of alumina resulted in the formation of a network of spinel dendrites which prevented accumulation of particles into compact layers.
Modelling groundwater discharge areas using only digital elevation models as input data
Energy Technology Data Exchange (ETDEWEB)
Brydsten, Lars [Umeaa Univ. (Sweden). Dept. of Biology and Environmental Science
2006-10-15
Advanced geohydrological models require data on topography, soil distribution in three dimensions, vegetation, land use, bedrock fracture zones. To model present geohydrological conditions, these factors can be gathered with different techniques. If a future geohydrological condition is modelled in an area with positive shore displacement (say 5,000 or 10,000 years), some of these factors can be difficult to measure. This could include the development of wetlands and the filling of lakes. If the goal of the model is to predict distribution of groundwater recharge and discharge areas in the landscape, the most important factor is topography. The question is how much can topography alone explain the distribution of geohydrological objects in the landscape. A simplified description of the distribution of geohydrological objects in the landscape is that groundwater recharge areas occur at local elevation curvatures and discharge occurs in lakes, brooks, and low situated slopes. Areas in-between these make up discharge areas during wet periods and recharge areas during dry periods. A model that could predict this pattern only using topography data needs to be able to predict high ridges and future lakes and brooks. This study uses GIS software with four different functions using digital elevation models as input data, geomorphometrical parameters to predict landscape ridges, basin fill for predicting lakes, flow accumulations for predicting future waterways, and topographical wetness indexes for dividing in-between areas based on degree of wetness. An area between the village of and Forsmarks' Nuclear Power Plant has been used to calibrate the model. The area is within the SKB 10-metre Elevation Model (DEM) and has a high-resolution orienteering map for wetlands. Wetlands are assumed to be groundwater discharge areas. Five hundred points were randomly distributed across the wetlands. These are potential discharge points. Model parameters were chosen with the
Directory of Open Access Journals (Sweden)
SONI S.S.
2012-09-01
Full Text Available This paper describes development of fuzzy logic model for powder mixed electro discharge machining (PMEDM process. The developed fuzzy model implements triangular and trapezoidal membership functionsfor fuzzification and centre-of-area method for defuzzification processes. The process parameters selected as control variables for experimental work were tool material, type of powder, concentration of powder in dielectric medium and peak current. The machining operation was conducted by using copper and graphite as electrode material on mild steel workpiece material. The powder additives used in the experiment were aluminum and silicon because of their significantly different electrical and thermal properties. The dielectric fluid used was kerosene. The response parameters selected are material removal rate and electrode wear rate. Response surfaces are developed from the developed fuzzy system model. Also exemplar plot developed to compare the responses from fuzzy model and experiment.
Modelling effect of magnetic field on material removal in dry electrical discharge machining
Abhishek, Gupta; Suhas, S. Joshi
2017-02-01
One of the reasons for increased material removal rate in magnetic field assisted dry electrical discharge machining (EDM) is confinement of plasma due to Lorentz forces. This paper presents a mathematical model to evaluate the effect of external magnetic field on crater depth and diameter in single- and multiple-discharge EDM process. The model incorporates three main effects of the magnetic field, which include plasma confinement, mean free path reduction and pulsating magnetic field effects. Upon the application of an external magnetic field, Lorentz forces that are developed across the plasma column confine the plasma column. Also, the magnetic field reduces the mean free path of electrons due to an increase in the plasma pressure and cycloidal path taken by the electrons between the electrodes. As the mean free path of electrons reduces, more ionization occurs in plasma column and eventually an increase in the current density at the inter-electrode gap occurs. The model results for crater depth and its diameter in single discharge dry EDM process show an error of 9%-10% over the respective experimental values.
Semi-analytical modelling of positive corona discharge in air
Pontiga, Francisco; Yanallah, Khelifa; Chen, Junhong
2013-09-01
Semianalytical approximate solutions of the spatial distribution of electric field and electron and ion densities have been obtained by solving Poisson's equations and the continuity equations for the charged species along the Laplacian field lines. The need to iterate for the correct value of space charge on the corona electrode has been eliminated by using the corona current distribution over the grounded plane derived by Deutsch, which predicts a cos m θ law similar to Warburg's law. Based on the results of the approximated model, a parametric study of the influence of gas pressure, the corona wire radius, and the inter-electrode wire-plate separation has been carried out. Also, the approximate solutions of the electron number density has been combined with a simplified plasma chemistry model in order to compute the ozone density generated by the corona discharge in the presence of a gas flow. This work was supported by the Consejeria de Innovacion, Ciencia y Empresa (Junta de Andalucia) and by the Ministerio de Ciencia e Innovacion, Spain, within the European Regional Development Fund contracts FQM-4983 and FIS2011-25161.
Differences between young and elderly in soleus motor unit discharge rate in dynamic movements
Directory of Open Access Journals (Sweden)
Jouni eKallio
2014-09-01
Full Text Available Aging is related to changes at the muscular level, leading to a decline in motor performance increasing the risk of falling and injury. It seems that the age-related changes in motor unit activation are muscle- and intensity dependent. The purpose of this study was to examine possible differences in soleus motor unit discharge rate (MUDR in both isometric and dynamic contractions between young and elderly adults. 11 young (YOUNG and 8 elderly (OLD males participated in the study. The subjects performed isometric and dynamic plantar flexions while seated in an ankle dynamometer. The force levels studied were 10, 20, 40, 60, 80 and 100% of the isometric (ISO MVC in ISO and 10, 20 and 40% in concentric (CON and eccentric (ECC contractions. Soleus intramuscular EMG was recorded with bipolar fine-wire electrodes and decomposed to individual trains of motor unit discharges. In ISO the MUDR was higher in YOUNG in 20, 40, 60 and 80% MVC, while in the dynamic contractions no age-difference was seen. For both age-groups MUDR was higher in CON compared to ISO or ECC. The relative level of sEMG activity in SOL and GM for a given force level was in all conditions higher for OLD compared to YOUNG. The decreased MUDR in OLD may be an adaptation to an increased twitch duration in order to optimize force generation. The lack of an age-difference in dynamic contractions could be due to differences in recruitment-strategies, coactivation or a lack of recording from high force levels.
Analysis of a lithium/thionyl chloride battery under moderate-rate discharge
Energy Technology Data Exchange (ETDEWEB)
Jain, M.; Nagasubramanian, G.; Jungst, R.G.; Weidner, J.W.
1999-11-01
A one-dimensional mathematical model of a spirally wound lithium/thionyl chloride primary battery is developed and used for parameter estimation and design studies. The model formulation is based on the fundamental conservation laws using porous electrode theory and concentrated solution theory. The model is used to estimate the transference number, the diffusion coefficient, and the kinetic parameters for the reactions at the anode and the cathode as a function of temperature. These parameters are obtained by fitting the simulated capacity and average cell voltage to experimental data over a wide range of temperatures ({minus}55 to 49 C) and discharge loads (10--250 {Omega}). The experiments were performed on D-sized, cathode-limited, spirally wound lithium/thionyl chloride cells. The model is also used to study the effect of cathode thickness on the cell capacity as a function of temperature, and it was found that the optimum thickness for the cathode-limited design is temperature and load dependent.
Flexible graphene-based lithium ion batteries with ultrafast charge and discharge rates.
Li, Na; Chen, Zongping; Ren, Wencai; Li, Feng; Cheng, Hui-Ming
2012-10-23
There is growing interest in thin, lightweight, and flexible energy storage devices to meet the special needs for next-generation, high-performance, flexible electronics. Here we report a thin, lightweight, and flexible lithium ion battery made from graphene foam, a three-dimensional, flexible, and conductive interconnected network, as a current collector, loaded with Li(4)Ti(5)O(12) and LiFePO(4), for use as anode and cathode, respectively. No metal current collectors, conducting additives, or binders are used. The excellent electrical conductivity and pore structure of the hybrid electrodes enable rapid electron and ion transport. For example, the Li(4)Ti(5)O(12)/graphene foam electrode shows a high rate up to 200 C, equivalent to a full discharge in 18 s. Using them, we demonstrate a thin, lightweight, and flexible full lithium ion battery with a high-rate performance and energy density that can be repeatedly bent to a radius of 5 mm without structural failure and performance loss.
Institute of Scientific and Technical Information of China (English)
Sun Ji-Zhong; Li Xian-Tao; Bai Jing; Wang De-Zhen
2012-01-01
Hydrogen discharges driven by the combined radio-frequency(rf)/short pulse sources are investigated using the particle-in-cell method.The simulation results show that the discharge driven additionally by the short pulse can enhance the electron density and modulate the electron energy to provide a better condition for negative hydrogen ion production than the discharge driven by the rf-only source.
Development of Efficient Models of Corona Discharges Around Tall Structures
Tucker, J.; Pasko, V. P.
2012-12-01
This work concerns with numerical modeling of glow corona and sreamer corona discharges that occur near tall ground structures under thunderstorm conditions. Glow corona can occur when ambient electric field reaches modest values on the order of 0.2 kV/cm and when the electric field near sharp points of ground structure rises above a geometry dependent critical field required for ionization of air. Air is continuously ionized in a small region close to the surface of the structure and ions diffuse out into the surrounding air forming a corona. A downward leader approaching from a thundercloud causes a further increase in the electric field at the ground level. If the electric field rises to the point where it can support formation of streamers in air surrounding the tall structure, a streamer corona flash, or series of streamer corona flashes can be formed significantly affecting the space charge configuration formed by the preceding glow corona. The streamer corona can heat the surrounding air enough to form a self-propagating thermalized leader that is launched upward from the tall structure. This leader travels upward towards the thundercloud and connects with the downward approaching leader thus causing a lightning flash. Accurate time-dependent modeling of charge configuration created by the glow and streamer corona discharges around tall structure is an important component for understanding of the sequence of events leading to lightning attachment to the tall structure. The present work builds on principal modeling ideas developed previously in [Aleksandrov et al., J. Phys. D: Appl. Phys., 38, 1225, 2005; Bazelyan et al., Plasma Sources Sci. Technol., 17, 024015, 2008; Kowalski, E. J., Honors Thesis, Penn State Univ., University Park, PA, May 2008; Tucker and Pasko, NSF EE REU Penn State Annual Res. J., 10, 13, 2012]. The non-stationary glow and streamer coronas are modeled in spherical geometry up to the point of initiation of the upward leader. The model
Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material
Pannala, Sreekanth; Daw, C. Stuart; Finney, Charles E. A.; Benyahia, Sofiane; Syamlal, Madhava; O'Brien, Thomas J.
2009-06-01
We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear `blending' function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al.., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implement our stress transition model in an open-source multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model's effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., `sticky' solids).
Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material
Energy Technology Data Exchange (ETDEWEB)
Pannala, Sreekanth [ORNL; Daw, C Stuart [ORNL; FINNEY, Charles E A [ORNL; Benyahia, S. [National Energy Technology Laboratory (NETL); Syamlal, M. [National Energy Technology Laboratory (NETL); O' Brien, T. J. [National Energy Technology Laboratory (NETL)
2009-01-01
We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear blending function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implement our stress transition model in an opensource multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model s effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., sticky solids).
Directory of Open Access Journals (Sweden)
Ladeesh V. G.
2017-01-01
Full Text Available Grinding aided electrochemical discharge machining is a hybrid technique, which combines the grinding action of an abrasive tool and thermal effects of electrochemical discharges to remove material from the workpiece for producing complex contours. The present study focuses on developing fluidic channels on borosilicate glass using G-ECDM and attempts to develop a mathematical model for surface roughness of the machined channel. Preliminary experiments are conducted to study the effect of machining parameters on surface roughness. Voltage, duty factor, frequency and tool feed rate are identified as the significant factors for controlling surface roughness of the channels produced by G-ECDM. A mathematical model was developed for surface roughness by considering the grinding action and thermal effects of electrochemical discharges in material removal. Experiments are conducted to validate the model and the results obtained are in good agreement with that predicted by the model.
DEFF Research Database (Denmark)
Saeed Madani, Seyed; Swierczynski, Maciej Jozef; Kær, Søren Knudsen
2017-01-01
This paper gives insight into the discharge behavior of lithium-ion batteries based on the investigations, which have been done by the researchers [1– 19]. In this article, the battery's discharge behaviour at various discharge rates is studied and surface monitor, discharge curve, volume monitor...... to analysis the discharge behaviour of lithium-ion batteries. The results show that surface monitor plot of discharge curve at 1 C has a decreasing trend and volume monitor plot of maximum temperature in the domain has slightly increasing pattern over the simulation time. For the curves of discharge...... plot of maximum temperature in the domain and maximum temperature in the area are illustrated. Additionally, an external and internal short-circuit treatment for three cases have been studied. The Dual-Potential Multi-Scale Multi-Dimensional (MSMD) Battery Model (BM) was used by ANSYS FLUENT software...
Mixing effects in postdischarge modeling of electric discharge oxygen-iodine laser experiments
Palla, Andrew D.; Carroll, David L.; Verdeyen, Joseph T.; Solomon, Wayne C.
2006-07-01
In an electric discharge oxygen-iodine laser, laser action at 1315nm on the I(P1/22)→I(P3/22) transition of atomic iodine is obtained by a near resonant energy transfer from O2(aΔ1) which is produced using a low-pressure electric discharge. The discharge production of atomic oxygen, ozone, and other excited species adds higher levels of complexity to the postdischarge kinetics which are not encountered in a classic purely chemical O2(aΔ1) generation system. Mixing effects are also present. In this paper we present postdischarge modeling results obtained using a modified version of the BLAZE-II gas laser code. A 28 species, 105 reaction chemical kinetic reaction set for the postdischarge kinetics is presented. Calculations were performed to ascertain the impact of a two stream mixing mechanism on the numerical model and to study gain as a function of reactant mass flow rates. The calculations were compared with experimental data. Agreement with experimental data was improved with the addition of new kinetics and the mixing mechanism.
An advanced time-dependent collisional-radiative model of helium plasma discharges
Claustre, J.; Boukandou-Mombo, C.; Margot, J.; Matte, J.-P.; Vidal, F.
2017-10-01
A new spatially averaged time-dependent collisional-radiative model for helium plasmas, coupled to the electron Boltzmann equation (EBE), has been developed. Its main novelties are: (1) full time dependence for both the multi-species kinetics and the EBE. It is shown that this is necessary to correctly simulate discharges where the parameters vary on nanoseconds-microsecond timescales. (2) All electron processes are accounted for accurately. In particular, for the various ionization and recombination processes, free electrons are added or removed at the appropriate energy, with the appropriate interpolation on the energy grid. (3) The energy dependence of the electron loss by ambipolar diffusion is taken into account approximately. (4) All of the processes which are known to be important in helium discharges for pressure P≤slant 760 Torr are included, and 42 energy levels up to n = 6, where n is the main quantum number, are taken into account. Atomic and molecular ions, as well as excimers, are also included. (5) The gas temperature is calculated self-consistently. The model is validated through comparisons with known numerical steady-state results of Santos et al (2014 J. Phys. D. 47 265201) which they compared to their experimental results, and good agreement is obtained for their measured quantities. It is then applied to post-discharge decay cases with very short power decay times. The time evolution of the population densities and reaction rates are analyzed in detail with emphasis on the observed large increase of the metastable density.
Partial Discharge in Capacitor Model at Low Temperature
Directory of Open Access Journals (Sweden)
P. Rain
2009-01-01
Full Text Available The partial discharge plays an important role in the ageing and the rupture process of solid or mixed insulation systems. Ithas been recognized that the failure of this insulation can be joined to the presence of partial discharge often in inclusionssparkling. Liquid filled cavities can be considered as the most likely defects that can exist in capacitors. In this paper wedescribe the partial discharge evolution at low temperatures in all-PP film capacitors according to the time and the appliedvoltage. We distinguish two regimes of discharges for all the range of temperature and the low temperatures encourage thebreakdown of capacitors at weak voltage, we assign this phenomenon to the increase of the viscosity of filling liquid.
ORAL ISSUE OF THE JOURNAL "USPEKHI FIZICHESKIKH NAUK": Modeling of gas discharge plasma
Smirnov, Boris M.
2009-06-01
The condition for the self-maintenance of a gas discharge plasma (GDP) is derived from its ionization balance expressed in the Townsend form and may be used as a definition of a gas discharge plasma in its simplest form. The simple example of a gas discharge plasma in the positive column of a cylindrical discharge tube allows demonstrating a wide variety of possible GDP regimes, revealing a contradiction between simple models used to explain gas discharge regimes and the large number of real processes responsible for the self-maintenance of GDP. The variety of GDP processes also results in a stepwise change of plasma parameters and developing some instabilities as the voltage or discharge current is varied. As a consequence, new forms and new applications of gas discharge arise as technology progresses.
An automated system to simulate the River discharge in Kyushu Island using the H08 model
Maji, A.; Jeon, J.; Seto, S.
2015-12-01
Kyushu Island is located in southwestern part of Japan, and it is often affected by typhoons and a Baiu front. There have been severe water-related disasters recorded in Kyushu Island. On the other hand, because of high population density and for crop growth, water resource is an important issue of Kyushu Island.The simulation of river discharge is important for water resource management and early warning of water-related disasters. This study attempts to apply H08 model to simulate river discharge in Kyushu Island. Geospatial meteorological and topographical data were obtained from Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) and Automated Meteorological Data Acquisition System (AMeDAS) of Japan Meteorological Agency (JMA). The number of the observation stations of AMeDAS is limited and is not quite satisfactory for the application of water resources models in Kyushu. It is necessary to spatially interpolate the point data to produce grid dataset. Meteorological grid dataset is produced by considering elevation dependence. Solar radiation is estimated from hourly sunshine duration by a conventional formula. We successfully improved the accuracy of interpolated data just by considering elevation dependence and found out that the bias is related to geographical location. The rain/snow classification is done by H08 model and is validated by comparing estimated and observed snow rate. The estimates tend to be larger than the corresponding observed values. A system to automatically produce daily meteorological grid dataset is being constructed.The geospatial river network data were produced by ArcGIS and they were utilized in the H08 model to simulate the river discharge. Firstly, this research is to compare simulated and measured specific discharge, which is the ratio of discharge to watershed area. Significant error between simulated and measured data were seen in some rivers. Secondly, the outputs by the coupled model including crop growth
Directory of Open Access Journals (Sweden)
Thangam Chinnadurai
2016-12-01
Full Text Available This study focuses on investigating the effects of process parameters, namely, Peak current (Ip, Pulse on time (Ton, Pulse off time (Toff, Water pressure (Wp, Wire feed rate (Wf, Wire tension (Wt, Servo voltage (Sv and Servo feed setting (Sfs, on the Material Removal Rate (MRR and Surface Roughness (SR for Wire electrical discharge machining (Wire-EDM of nickel using Taguchi method. Response Surface Methodology (RSM is adopted to evolve mathematical relationships between the wire cutting process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired optimal wire cutting quality. Besides, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Mini-tab is used to establish the design and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA method to check their appropriateness and suitability. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses accurately and precisely within the limits of cutting parameter being used.
Ameli, Ali; Erlandsson, Martin; Beven, Keith; Creed, Irena; McDonnell, Jeffrey; Bishop, Kevin
2017-04-01
The permeability architecture of the critical zone exerts a major influence on the hydrogeochemistry of the critical zone. Water flowpath dynamics drive the spatio-temporal pattern of geochemical evolution and resulting streamflow concentration-discharge (C-Q) relation, but these flowpaths are complex and difficult to map quantitatively. Here, we couple a new integrated flow and particle tracking transport model with a general reversible Transition-State-Theory style dissolution rate-law to explore theoretically how C-Q relations and concentration in the critical zone respond to decline in saturated hydraulic conductivity (Ks) with soil depth. We do this for a range of flow rates and mineral reaction kinetics. Our results show that for minerals with a high ratio of equilibrium concentration to intrinsic weathering rate, vertical heterogeneity in Ks enhances the gradient of weathering-derived solute concentration in the critical zone and strengthens the inverse stream C-Q relation. As the ratio of equilibrium concentration to intrinsic weathering rate decreases, the spatial distribution of concentration in the critical zone becomes more uniform for a wide range of flow rates, and stream C-Q relation approaches chemostatic behaviour, regardless of the degree of vertical heterogeneity in Ks. These findings suggest that the transport-controlled mechanisms in the hillslope can lead to chemostatic C-Q relations in the stream while the hillslope surface reaction-controlled mechanisms are associated with an inverse stream C-Q relation. In addition, as the ratio of equilibrium concentration to intrinsic weathering rate decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time)
Shukla, Garima; Del Olmo Diaz, Diego; Thangavel, Vigneshwaran; Franco, Alejandro A
2017-05-31
We report a comprehensive modeling-based study of electroactive suspensions in slurry redox flow batteries undergoing discharge. A three-dimensional kinetic Monte Carlo model based on the variable step size method is used to describe the electrochemical discharge of a silicon/carbon slurry electrode in static mode (i.e., no fluid flow conditions). The model accounts for Brownian motion of particles, volume expansion of silicon upon lithium insertion, and formation and destruction of conducting carbon networks. Coupled to an electrochemical model, this study explores the impact of carbon fraction in the slurry and applied c-rate on the specific capacity. The trends obtained are analyzed by following the behavior of parameters such as number of contacts between electroactive particles and the percentage of electroactive silicon particles. Furthermore, instead of studying the bulk behavior of the slurry, here the focus is given to the slurry/current collector interface in order to illustrate its importance. Hereby, it is demonstrated how this modeling tool can lead to deeper understanding and optimization of electroactive particle suspensions in redox flow batteries.
AGGREGATE RATING MODEL IN THE TOURISM INDUSTRY
Directory of Open Access Journals (Sweden)
Maris Angela
2014-07-01
Full Text Available In the paper the authors present a model aggregate rating based on credit-scoring models, banking models and their rating model. Multi-criteria approach and an aggregate model better capture business risk of the company.
Energy Technology Data Exchange (ETDEWEB)
Carman, R.J. [Department of Physics, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)). E-mail: rcarman@physics.mq.edu.au; Mildren, R.P. [Centre for Lasers and Applications, Division of Information and Communications Sciences, Macquarie University, Sydney, NSW (Australia)
2000-10-07
In modelling the plasma kinetics in dielectric barrier discharges (DBDs), the electron energy conservation equation is often included in the rate equation analysis (rather than utilizing the local-field approximation) with the assumption that the electron energy distribution function (EEDF) has a Maxwellian profile. We show that adopting a Maxwellian EEDF leads to a serious overestimate of the calculated ionization/excitation rate coefficients and the electron mobility for typical plasma conditions in a xenon DBD. Alternative EEDF profiles are trialed (Druyvesteyn, bi-Maxwellian and bi-Druyvesteyn) and benchmarked against EEDFs obtained from solving the steady-state Boltzmann equation. A bi-Druyvesteyn EEDF is shown to be more inherently accurate for modelling simulations of xenon DBDs. (author)
Modeling and experimental study of molecular nitrogen dissociation in an Ar-N{sub 2} ICP discharge
Energy Technology Data Exchange (ETDEWEB)
Kang, Namjun; Gaboriau, Freddy; Ricard, Andre [Universite de Toulouse, UPS, INPT, LAPLACE - Laboratoire Plasma et Conversion d' Energie, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Oh, Soo-ghee, E-mail: gaboriau@laplace.univ-tlse.fr [Division of Energy Systems Research, Ajou University, Suwon 443-749 (Korea, Republic of)
2011-08-15
The dissociation of nitrogen molecules in an Ar-N{sub 2} inductively coupled plasma (ICP) discharge is studied both experimentally and theoretically. To measure the absolute N atom density and emission intensity of Ar and N{sub 2} excited levels, two-photon absorption laser-induced fluorescence (TALIF) spectroscopy and optical emission spectroscopy are used. We observe an increase in N atom density with increasing pressure whereas the N atom density decreases for pressures higher than 100 mTorr in a pure nitrogen discharge. On adding argon to the mixture, we observe that the dissociation rate is enhanced when going from a pure nitrogen discharge to an argon mixed discharge. To calculate the plasma parameters, a global (volume-averaged) model is developed. The variation of the electron temperature and the particle densities are calculated by solving the particle and energy balance equations. The model calculations are compared with the measurement results and the production and loss rates of each species are described under each discharge condition. From the model calculation, the dissociation of N{sub 2} molecules in the Ar-N{sub 2} mixed discharge occurs mainly by electron impact dissociation at low pressures, while at high pressures the dissociative recombination is enhanced by charge transfer between Ar{sup +} and N{sub 2}(X) as well as metastable-metastable pooling dissociation due to the high N{sub 2}(A {sup 3{Sigma}}{sub u}{sup +}) density. In addition, the surface sticking coefficient of nitrogen atoms in a planar ICP discharge (including glass and stainless steel walls) is deduced from TALIF measurements and is estimated to be 0.02 under our set-up conditions.
Analysis and application of the scale effect of flood discharge atomization model
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The phenomenon of discharge atomization occurs as hydraulic structures discharging,which influences the safety of power station,electrical equipment and produces environmental pollution.A series of physical model tests and feedback analysis are adapted to preliminarily study the scale effect of discharge atomization model by use of the field observation data of discharge atomization.The effect of Re and We numbers of flow on the atomization intensity is analyzed.A conversion relationship of atomization intensity between prototype and model results and the similarity criteria of the atomization range are developed. The conclusion is that the surface tension of discharge atomization model could be ignored when the Weber number is larger than 500.Some case studies are given by use of the similitude criteria of the atomization model.
Modeling of asymmetric pulsed phenomena in dielectric-barrier atmospheric-pressure glow discharges
Energy Technology Data Exchange (ETDEWEB)
Ha Yan [College of Mathematics and Computer Science, Hebei University, Baoding 071002 (China); Wang Huijuan [School of Mathematics and Physics, North China Electric Power University, Baoding 071003 (China); Wang Xiaofei [College of Physics Science and Technology, Hebei University, Baoding 071002 (China)
2012-01-15
Asymmetric current pulses in dielectric-barrier atmospheric-pressure glow discharges are investigated by a self-consistent, one-dimensional fluid model. It is found that the glow mode and Townsend mode can coexist in the asymmetric discharge even though the gas gap is rather large. The reason for this phenomenon is that the residual space charge plays the role of anode and reduces the gap width, resulting in the formation of a Townsend discharge.
Shlyaptsev, Vyacheslav N.; Gerusov, Alexey V.; Vinogradov, Alexander V.; Rocca, Jorge J. G.; Cortazar, O. D.; Tomasel, Fernando G.; Szapiro, Benito T.
1994-02-01
In this paper we report results of a model of a fast capillary discharge (FCD) and discuss them in comparison with experiments. The overall good coincidence between theory and experiment and the observation of stable reproducible compression are beneficial properties of FCD which open the possibility for achieving X-ray laser action in a compact discharge device. The required discharge parameters for lasing in different atomic elements have been calculated.
Harwood, B; Choi, I; Rice, C L
2012-12-15
Fatigability is highly task dependent wherein motor unit (MU) discharge rates and recruitment thresholds are affected differently depending on whether contractions are performed at maximal or submaximal intensities. Although much is described for isometric tasks, the behavior of MU properties during the production of maximal velocity dynamic contractions following submaximal fatiguing contractions is unknown. In seven young men, we evaluated changes in MU recruitment thresholds and MU discharge rates of the anconeus muscle during both submaximal and maximal dynamic elbow extensions following a submaximal dynamic fatiguing protocol of moderate intensity to velocity task failure. Velocity and power of the maximal dynamic contractions declined ∼45 and ∼55%, respectively, but these variables were unchanged for the submaximal target velocity contractions. Discharge rates of the 12 MUs at task failure were unchanged for submaximal dynamic contractions, but were decreased ∼20% for maximal dynamic and ballistic isometric contractions at task failure. MU recruitment thresholds of submaximal dynamic contractions decreased 52% at task failure, but were similar throughout the fatiguing protocol for maximal contractions. These findings support the concept of a common neural mechanism responsible for the relative declines in MU discharge rate associated with submaximal fatigability in both isometric and dynamic contractions.
Kriha, Vitezslav
2003-10-01
Non-thermal plasma of atmospheric pressure electrical discharges in flowing air can be used to generation of ozone. We have been observed two modes of discharge burning in a hollow needle to plane electrodes configuration studied in the ozone generation experiments: A low current diffuse mode is characterized by increasing of the ozone production with the discharge current; a high current filamentary mode is disadvantageous for the ozone generation(the ozone production decreases when the discharge current increases). A possible interpretation of this effect is following: The filamentary mode discharge current density is redistributed and high current densities in filaments cores lead to degradation of the ozone generation. Local fields in the discharge can be modified by charged metallic and/or dielectric components (passive modulators) in the discharge space. An interactive numerical model has been developed for this purpose. This model is based on Ferguson's polynomial objects for both the discharge chamber scene modelling and the discharge fields analyzing. This approach allows intuitive modifications of modulators shapes and positions in 3D scene followed by quantitative comparison of the current density distribution with previous configurations.
Coppola, Diego; Laiolo, Marco; Cigolini, Corrado
2016-04-01
The rate at which the lava is erupted is a crucial parameter to be monitored during any volcanic eruption. However, its accurate and systematic measurement, throughout the whole duration of an event, remains a big challenge, also for volcanologists working on highly studied and well monitored volcanoes. The thermal approach (also known as thermal proxy) is actually one of most promising techniques adopted during effusive eruptions, since it allows to estimate Time Averaged lava Discharge Rates (TADR) from remote-sensed infrared data acquired several time per day. However, due to the complexity of the physic behind the effusive phenomenon and the difficulty to have field validations, the application of the thermal proxy is still debated and limited to few volcanoes only. Here we present the analysis of MODIS Middle InfraRed data, collected by during several distinct eruptions, in order to show how an alternative, empirical method (called radiant density approach; Coppola et al., 2013) permit to estimate TADRs over a wide range of emplacement styles and lava compositions. We suggest that the simplicity of this empirical approach allows its rapid application during eruptive crisis, and provides the basis for more complex models based on the cooling and spreading processes of the active lava bodies.
Modeling Hospital Discharge and Placement Decision Making: Whither the Elderly.
Clark, William F.; Pelham, Anabel O.
This paper examines the hospital discharge decision making process for elderly patients, based on observations of the operations of a long term care agency, the California Multipurpose Senior Services Project. The analysis is divided into four components: actors, factors, processes, and strategy critique. The first section discusses the major…
High order fluid model for ionization fronts in streamer discharges
Markosyan, A.; Dujko, S.; Hundsdorfer, W.; Ebert, U.
2011-01-01
When non-ionized or lowly ionized matter is exposed to high electric fields, non-equilibrium ionization processes, streamer discharges, can develop. Streamers occur in nature and as well in many industrial applications such as the treatment of exhaust gasses, polluted water or biogas. A third order
Levko, Dmitry; Raja, Laxminarayan L.
2017-03-01
In this paper, we seek to validate the zero-dimensional (global) model approach for the modeling of the plasma composition in high pressure reactive streamer discharges. We focus on streamers typical of dielectric barrier discharge that are widely used, for instance, for plasma-assisted reforming of greenhouse gases. However, our conclusions can be extended to the streamers used in plasma-assisted ignition/combustion and other related systems. First, we perform two-dimensional fluid simulations for streamers with positive and negative trigger voltages and analyze the difference between the breakdown mechanisms of these two modes. Second, we use the time evolution of the electron heating term obtained from the fluid simulations as the input parameter of the global model and compare the plasma component content predicted by this model with the results of the fluid model. We obtain a very good agreement between fluid and global models for all species generated in plasma. However, we conclude that streamers initiated by the positive and negative trigger voltage cannot be considered as symmetrical which is usually done in global models of barrier discharge reactors.
Rate of three-body electron attachment to an oxygen molecule in a semi-self-maintained discharge
Krasiukov, A. G.; Naumov, V. G.; Shachkin, L. V.; Shashkov, V. M.
1981-06-01
The rate of three-body electron attachment to an oxygen molecule has been investigated in a semi-self-maintained discharge sustained by a fast electron beam in a mixture of O2:N2 = 1:20 at atmospheric pressure. Experimental results are in good agreement with theory. It is found that the attachment rate decreases with the increasing energy input, and a qualitative explanation of this effect is presented.
Integrating topography, hydrology and rock structure in weathering rate models of spring watersheds
Pacheco, F.A.L.; Weijden, C.H. van der
2012-01-01
Weathering rate models designed for watersheds combine chemical data of discharging waters with morphologic and hydrologic parameters of the catchments. At the spring watershed scale, evaluation of morphologic parameters is subjective due to difficulties in conceiving the catchment geometry. Besides
Temnikov, A. G.; Chernenskii, L. L.; Orlov, A. V.; Lysov, N. Yu.; Belova, O. S.; Kalugina, I. E.; Gerastenok, T. K.; Zhuravkova, D. S.
2017-02-01
The initiation of discharge by model hydrometeors between an artificial-thunderstorm cell (aerosol cloud) of negative or positive polarity and ground has been experimentally studied. It is established for the first time that the conditions of cloud-ground spark discharge initiation by hydrometeors, as well as the characteristics of discharge significantly depend on the polarity of charged cloud. The effect of hydrometeor arrays can be manifested by the cloud-ground lightning initiated in a thundercloud and used for developing scientific principles of artificial lightning discharge.
A self-discharge model of Lithium-Sulfur batteries based on direct shuttle current measurement
DEFF Research Database (Denmark)
Knap, Vaclav; Stroe, Daniel Loan; Swierczynski, Maciej Jozef
2016-01-01
. A simple but comprehensive mathematical model of the Li-S battery cell self-discharge based on the shuttle current was developed and is presented. The shuttle current values for the model parameterization were obtained from the direct shuttle current measurements. Furthermore, the battery cell depth......-of-discharge values were recomputed in order to account for the influence of the self-discharge and provide a higher accuracy of the model. Finally, the derived model was successfully validated against laboratory experiments at various conditions....
Discharge area segmentation of power equipment in UV image based on GVF snake model
Institute of Scientific and Technical Information of China (English)
He Zhenhua; Deng Wei; Li Lianlian; Huang Wenwu; Wang Wei; Liu Xuming
2014-01-01
To extract the discharge region contour of the ultraviolet (UV) image may help us to locate the discharge position, to obtain the appearance and the size, furthermore, it help us to analysis and judge the equipment defect. In this paper, a GVF(Gradient Vector Flow) snake model method is applied to obtain the discharge region contour, this method diffuses the traditional snake model’s force field, so it can guide the initial curve to shrink or expand to the real boundary automatically. The method has the character of fast convergence speed, not sensitive to the initial contour, and the initial curve can converge to the convex-concave part of discharge region. Experiments show that the discharge region boundary extracted by GVF snake method is continuous, good smoothness, near to the real edge of discharge region, and it also has a good anti-noise ability.
Predictors of Discharge Disposition in Older Adults With Burns: A Study of the Burn Model Systems.
Pham, Tam N; Carrougher, Gretchen J; Martinez, Erin; Lezotte, Dennis; Rietschel, Carly; Holavanahalli, Radha; Kowalske, Karen; Esselman, Peter C
2015-01-01
Older patients with burn injury have a greater likelihood for discharge to nursing facilities. Recent research indicates that older patients discharged to nursing facilities are two to three times as likely to die within a 3-year period relative to those discharged to home. In light of these poor long-term outcomes, we conducted this study to identify predictors for discharge to independent vs nonindependent living status in older patients hospitalized for burns. We retrospectively reviewed all older adults (age ≥ 55 years) who were prospectively enrolled in a longitudinal multicenter study of outcomes from 1993 to 2011. Patient, injury, and treatment outcomes data were analyzed. Recognizing that transfer to inpatient rehabilitation may have impacted final hospital discharge disposition: we assessed the likelihood of inpatient rehabilitation stay, based on identified predictors of inpatient rehabilitation. We subsequently performed a logistic regression analysis on the clustered, propensity-matched cohort to assess associations of burn and injury characteristics on the primary outcome of final discharge status. A total of 591 patients aged ≥55 years were treated and discharged alive from three participating U.S. burn centers during the study period. Mean burn size was 14.8% (SD 11.2%) and mean age was 66.7 years (SD 9.3 years). Ninety-three patients had an inpatient rehabilitation stay before discharge (15.7%). Significant factors predictive of inpatient rehabilitation included a burn >20% TBSA, mechanical ventilation, older age, range of motion deficits at acute care discharge, and study site. These factors were included in the propensity model. Four hundred seventy-one patients (80%) were discharged to independent living status. By matched propensity analysis, older age was significantly associated with a higher likelihood of discharge to nonindependent living (P patient factors. Furthermore, clinical practice variations among the three study sites also
Kushima, Akihiro; Koido, Tetsuya; Fujiwara, Yoshiya; Kuriyama, Nariaki; Kusumi, Nobuhiro; Li, Ju
2015-12-09
Liquid-cell in situ transmission electron microscopy (TEM) observations of the charge/discharge reactions of nonaqueous Li-oxygen battery cathode were performed with ∼5 nm spatial resolution. The discharging reaction occurred at the interface between the electrolyte and the reaction product, whereas in charging, the reactant was decomposed at the contact with the gold current collector, indicating that the lithium ion diffusivity/electronic conductivity is the limiting factor in discharging/charging, respectively, which is a root cause for the asymmetry in discharging/charging overpotential. Detachments of lithium oxide particles from the current collector into the liquid electrolyte are frequently seen when the cell was discharged at high overpotentials, with loss of active materials into liquid electrolyte ("flotsam") under minute liquid flow agitation, as the lithium peroxide dendritic trees are shown to be fragile mechanically and electrically. Our result implies that enhancing the binding force between the reaction products and the current collector to maintain robust electronic conduction is a key for improving the battery performance. This work demonstrated for the first time the in situ TEM observation of a three-phase-reaction involving gold electrode, lithium oxides, DMSO electrolyte and lithium salt, and O2 gas. The technique described in this work is not limited to Li-oxygen battery but also can be potentially used in other applications involving gas/liquid/solid electrochemical reactions.
High rates of relapse in adolescents crack users after inpatient clinic discharge
Directory of Open Access Journals (Sweden)
Rosemeri Siqueira Pedroso
Full Text Available ABSTRACT Objective The objective of the present study was to evaluate 88 adolescent crack users referred to hospitalization and to follow them up after discharge to investigate relapse and factors associated with treatment. Methods Cohort (30 and 90 days after discharge from a psychiatric hospital and a rehab clinic for treatment for chemical dependency in Porto Alegre between 2011 and 2012. Instruments: Semi-structured interview, conducted to evaluate the sociodemographic profile of the sample and describe the pattern of psychoactive substance use; Crack Use Relapse Scale/CURS; Questionnaire Tracking Users to Crack/QTUC; K-SADS-PL. Results In the first follow-up period (30 days after discharge, 65.9% of participants had relapsed. In the second follow-up period (90 days after discharge, 86.4% of participants had relapsed. Conclusion This is one of the first studies that show the extremely high prevalence of early relapse in adolescent crack users after discharge, questioning the cost/benefit of inpatient treatment for this population. Moreover, these results corroborate studies which suggested, young psychostimulants users might need tailored intensive outpatient treatment with contingency management and other behavioral strategies, in order to increase compliance and reduce drug or crime relapse, but this specific therapeutic modality is still scarce and must be developed in Brazil.
Li, Zhiying; Fang, Haiyan
2017-09-01
Climate change is expected to impact discharge and sediment yield in watersheds. The purpose of this paper is to assess the potential impacts of climate change on water discharge and sediment yield for the Yi'an watershed of the black soil region, northeastern China, based on the newly released Representative Concentration Pathways (RCPs) during 2071-2099. For this purpose, the TETIS model was implemented to simulate the hydrological and sedimentological responses to climate change. The model calibration (1971-1977) and validation (1978-1987) performances were rated as satisfactory. The modeling results for the four RCP scenarios relative to the control scenario under the same land use configuration indicated an increase in discharge of 16.3% (RCP 2.6), 14.3% (RCP 4.5), 36.7% (RCP 6.0) and 71.4% (RCP 8.5) and an increase in the sediment yield of 16.5% (RCP 2.6), 32.4% (RCP 4.5), 81.8% (RCP 6.0) and 170% (RCP 8.5). This implies that the negative impact of climate change on sediment yield is generally greater than that on discharge. At the monthly scale, both discharge and sediment yield increased dramatically in April to June and August to September. A more vigorous hydrological cycle and an increase in high values of sediment yield are also expected. These changes in annual discharge and sediment yield were closely linked with changes in precipitation, whereas monthly changes in late spring and autumn were mainly related to temperature. This study highlights the possible adverse impact of climate change on discharge and sediment yield in the black soil region of northeastern China and could provide scientific basis for adaptive management.
Institute of Scientific and Technical Information of China (English)
Huijuan Ye; Hao Zhou; Xinye Wang
2016-01-01
In order to study the underwater trajectory of the non⁃powered vehicle discharged from the broadside of the underwater platform, the simulation on the ascent process of non⁃powered vehicle was realized based on the mathematical model including the movement of the vehicle on the slope plate and in the seawater, the air chamber underwater working process etc. The simulation results show that the outlet speed and attitude of the vehicle meet the requirements of missile launching, the non⁃powered vehicle discharged from the broadside of the underwater platform is feasible. The simulation results with varying parameters show that the negative buoyancy of the vehicle imposes great impacts on the security of its discharge and the floating process, and the vehicle discharge depth is proportional to the floating time. The models and simulation result can be used in further research on the broadside discharging technology of the underwater platform.
Swarzenski, P. W.; Baskaran, M.; Reich, C.; Greenwood, J.
2006-12-01
It is now widely accepted that water and constituent transport by submarine groundwater discharge (SGD) can be ecologically important within some coastal environments. However, the nature of this discharge, which can exhibit tremendously temporal and spatial heterogeneity, renders SGD most often difficult to identify and quantify. U/Th series geochemical tracers and new geophysical tools have been developed that now can yield system-wide information on SGD rates and processes. The objective of this study was to apply naturally- occurring Ra and Rn isotopes to derive SGD rates bay wide, and then examine to the geologic controls on SGD in this system with streaming and time series resistivity measurements. Submarine groundwater discharge rates calculated using a mass balance of excess Ra-226 ranged from 2 to 14 L per square-m per d. When extrapolated to the total shoreline length of the bay, such SGD rates ranged from 2 to 10 cubic-m per d per m of shoreline. High-resolution time series and streaming resistivity measurements confirm that SGD within Tampa Bay can be separated into a near-shore and mid-bay component that involve different water masses and unique mixing processes. SGD-derived nutrient loading estimates in Tampa bay will be compared to similar riverine estimates.
Numerical Simulations of an atmospheric pressure discharge using a two dimensional fluid model
Iqbal, Muhammad M.; Turner, Miles M.
2008-10-01
We present numerical simulations of a parallel-plate dielectric barrier discharge using a two-dimensional fluid model with symmetric boundary conditions in pure helium and He-N2 gases at atmospheric pressure. The periodic stationary pattern of electrons and molecular helium ions density is shown at different times during one breakdown pulse for the pure helium gas. The temporal behavior of the helium metastables and excimers species density is examined and their influences on the discharge characteristics are exhibited for an APD. The atmospheric pressure discharge modes (APGD and APTD) are affected with small N2 impurities and the discharge mode structures are described under different operating conditions. The uniform and filamentary behavior of the discharge is controlled with the variable relative permittivity of the dielectric barrier material. The influence of nitrogen impurities plays a major role for the production of the filaments in the after glow phase of He-N2 discharge and the filaments are clearly observed with the increased recombination coefficient of nitrogen ions. The creation and annihilation mechanism of filaments is described with the production and destruction of nitrogen ions at different applied voltages and driving frequencies for a complete cycle. The results of the fluid model are validated by comparison with the experimental atmospheric pressure discharge results in He-N2 plasma discharge.
Using Contaminant Transport Modeling to Determine Historical Discharges at the Surface
Fogwell, T. W.
2013-12-01
When it is determined that a contaminated site needs to be remediated, the issue of who is going to pay for that remediation is an immediate concern. This means that there needs to be a determination of who the responsible parties are for the existing contamination. Seldom is it the case that records have been made and kept of the surface contaminant discharges. In many cases it is possible to determine the relative amount of contaminant discharge at the surface of the various responsible parties by employing a careful analysis of the history of contaminant transport through the surface, through the vadose zone, and within the saturated zone. The process begins with the development of a dynamic conceptual site model that takes into account the important features of the transport of the contaminants through the vadose zone and in the groundwater. The parameters for this model can be derived from flow data available for the site. The resulting contaminant transport model is a composite of the vadose zone transport model, together with the saturated zone (groundwater) flow model. Any calibration of the model should be carefully employed in order to avoid using information about the conclusions of the relative discharge amounts of the responsible parties in determining the calibrated parameters. Determination of the leading edge of the plume is an important first step. It is associated with the first discharges from the surface of the site. If there were several discharging parties at the same time, then it is important to establish a chemical or isotopic signature of the chemicals that were discharged. The time duration of the first discharger needs to be determined as accurately as possible in order to establish the appropriate characterization of the leading portion of the resulting plume in the groundwater. The information about the first discharger and the resulting part of the plume associated with this discharger serves as a basis for the determination of the
Combining flow routing modelling and direct velocity measurement for optimal discharge estimation
Directory of Open Access Journals (Sweden)
G. Corato
2011-03-01
Full Text Available A new procedure is proposed for estimating river discharge hydrographs during flood events, using only water level data measured at a gauged site, as well as 1-D shallow water modelling and sporadic maximum surface flow velocity measurements. During flood, the piezometric level is surmised constant in the vertical plane of the river section, where the top of the banks is always above the river level, and is well represented by the recorded stage hydrograph. The river is modelled along the reach directly located downstream the upstream gauged section, where discharge hydrograph is sought after. For the stability with respect to the topographic error, as well as for the simplicity of the data required to satisfy the boundary conditions, a diffusive hydraulic model is adopted for flow routing. Assigned boundary conditions are: (1 the recorded stage hydrograph at the upstream river site and (2 the zero diffusion condition at the downstream end of the reach. The MAST algorithm is used for the numerical solution of the flow routing problem, which is embedded in the Brent algorithm used for the computation of the optimum Manning coefficient. Based on synthetic tests concerning a broad prismatic channel, the optimal reach length is chosen so that the approximated downstream boundary condition effects on discharge hydrograph assessment at upstream end are negligible. The roughness Manning coefficient is calibrated by using sporadic instantaneous surface velocity measurements during the rising limb of flood that are turned into instantaneous discharges through the solid of velocity estimated by a two-dimensional entropic model. Several historical events, occurring in three gauged sites along the upper Tiber River wherein a reliable rating curve is available, have been used for the validation. The analysis outcomes can be so summarized: (1 criteria adopted for selecting the optimal channel length and based on synthetic tests have been proved reliable by
Zhao, Fang; Veldkamp, Ted; Schauberger, Bernhard; Willner, Sven; Yamazaki, Dai
2017-04-01
Global hydrological models (GHMs) have been applied to assess global flood hazards. However, their capacity to capture the timing and amplitude of peak river discharge—which is crucial in flood simulations—has traditionally not been the focus of examination. Here we evaluate to what degree the choice of river routing scheme affects simulations of peak discharge and may help to provide better agreement with observations. To this end we use runoff and discharge simulations of nine GHMs forced by observational climate data (1971-2010) within the ISIMIP2a project. The runoff simulations were used as input for the global river routing model CaMa-Flood. The simulated daily discharges were compared to the discharge generated by each GHM using its native river routing scheme. For each GHM both versions of simulated discharge were compared to monthly and daily discharge observations from 1701 GRDC stations as a benchmark. CaMa-Flood routing shows a general reduction of peak river discharge and a delay of about two to three weeks in its occurrence, probably induced by the buffering capacity of floodplain reservoirs. For most river basins, discharge produced by CaMa-Flood resulted in a better agreement with observations. In particular, maximum daily discharge was adjusted, with a multi-model averaged reduction in bias over more than 60% of the basin area. The increase in agreement was obtained in both managed and near-natural basins. Overall, this study demonstrates the importance of routing scheme in peak discharge simulation, where CaMa-Flood routing accounts for floodplain storage and backwater effects that are not present in most GHMs. Our study provides important hints that an explicit parameterisation of these processes may be essential in future impact studies.
Zhao, Fang; Veldkamp, Ted I. E.; Frieler, Katja; Schewe, Jacob; Ostberg, Sebastian; Willner, Sven; Schauberger, Bernhard; Gosling, Simon N.; Müller Schmied, Hannes; Portmann, Felix T.; Leng, Gobias; Huang, Maoyi; Liu, Xingcai; Tang, Qiuhong; Hanasaki, Naota; Biemans, Hester; Gerten, Dieter; Satoh, Yusuke; Pokhrel, Yadu; Stacke, Tobias; Ciais, Philippe; Chang, Jinfeng; Ducharne, Agnes; Guimberteau, Matthieu; Wada, Yoshihide; Kim, Hyungjun; Yamazaki, Dai
2017-07-01
Global hydrological models (GHMs) have been applied to assess global flood hazards, but their capacity to capture the timing and amplitude of peak river discharge—which is crucial in flood simulations—has traditionally not been the focus of examination. Here we evaluate to what degree the choice of river routing scheme affects simulations of peak discharge and may help to provide better agreement with observations. To this end we use runoff and discharge simulations of nine GHMs forced by observational climate data (1971-2010) within the ISIMIP2a project. The runoff simulations were used as input for the global river routing model CaMa-Flood. The simulated daily discharge was compared to the discharge generated by each GHM using its native river routing scheme. For each GHM both versions of simulated discharge were compared to monthly and daily discharge observations from 1701 GRDC stations as a benchmark. CaMa-Flood routing shows a general reduction of peak river discharge and a delay of about two to three weeks in its occurrence, likely induced by the buffering capacity of floodplain reservoirs. For a majority of river basins, discharge produced by CaMa-Flood resulted in a better agreement with observations. In particular, maximum daily discharge was adjusted, with a multi-model averaged reduction in bias over about 2/3 of the analysed basin area. The increase in agreement was obtained in both managed and near-natural basins. Overall, this study demonstrates the importance of routing scheme choice in peak discharge simulation, where CaMa-Flood routing accounts for floodplain storage and backwater effects that are not represented in most GHMs. Our study provides important hints that an explicit parameterisation of these processes may be essential in future impact studies.
Modelling of low-current self-generated oscillations in a hollow cathode discharge
Donko, Z
1999-01-01
Low-current self-generated oscillations in a rectangular hollow cathode discharge in helium gas were investigated experimentally and by means of a two-dimensional self-consistent hybrid model. The model combines Monte Carlo simulation of the motion of fast electrons and a fluid description of slow electrons and positive ions. The low-frequency (<=20 kHz) oscillations were found to arise as an effect of the interaction of the gas discharge and the external electric circuit - consisting of a stable voltage source, a series resistor and a capacitor formed by the discharge electrodes. Good agreement was found between the experimentally observed and calculated oscillation frequency and current wave forms. Beside these characteristics the modelling also made it possible to calculate the time dependence of numerous other discharge characteristics (e.g. electron multiplication, ion density, potential distribution) and provided detailed insight into the mechanism of oscillations. The advantage of the present model ...
Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges
P. Sarrette, J.; Eichwald, O.; Marchal, F.; Ducasse, O.; Yousfi, M.
2016-05-01
The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply. The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz. The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air). The simulation involves the electro-dynamics, chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation. Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond. The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO. After 5 ms, the time corresponding to the occurrence of 50 successive discharge/post-discharge phases, a higher NO removal rate and a lower ozone production rate are found in humid air. This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.
Electro-Hydrodynamics and Kinetic Modeling of Dry and Humid Air Flows Activated by Corona Discharges
Institute of Scientific and Technical Information of China (English)
J.P.SARRETTE; O.EICHWALD; F.MARCHAL; O.DUCASSE; M.YOUSFI
2016-01-01
The present work is devoted to the 2D simulation of a point-to-plane Atmospheric Corona Discharge Reactor (ACDR) powered by a DC high voltage supply.The corona reactor is periodically crossed by thin mono filamentary streamers with a natural repetition frequency of some tens of kHz.The study compares the results obtained in dry air and in air mixed with a small amount of water vapour (humid air).The simulation involves the electro-dynamics,chemical kinetics and neutral gas hydrodynamics phenomena that influence the kinetics of the chemical species transformation.Each discharge lasts about one hundred of a nanosecond while the post-discharge occurring between two successive discharges lasts one hundred of a microsecond.The ACDR is crossed by a lateral dry or humid air flow initially polluted with 400 ppm of NO.After 5 ms,the time corresponding to the occurrence of 50 successive discharge/post-discharge phases,a higher NO removal rate and a lower ozone production rate are found in humid air.This change is due to the presence of the HO2 species formed from the H primary radical in the discharge zone.
Directory of Open Access Journals (Sweden)
S. C. van Pelt
2009-12-01
Full Text Available Studies have demonstrated that precipitation on Northern Hemisphere mid-latitudes has increased in the last decades and that it is likely that this trend will continue. This will have an influence on discharge of the river Meuse. The use of bias correction methods is important when the effect of precipitation change on river discharge is studied. The objective of this paper is to investigate the effect of using two different bias correction methods on output from a Regional Climate Model (RCM simulation. In this study a Regional Atmospheric Climate Model (RACMO2 run is used, forced by ECHAM5/MPIOM under the condition of the SRES-A1B emission scenario, with a 25 km horizontal resolution. The RACMO2 runs contain a systematic precipitation bias on which two bias correction methods are applied. The first method corrects for the wet day fraction and wet day average (WD bias correction and the second method corrects for the mean and coefficient of variance (MV bias correction. The WD bias correction initially corrects well for the average, but it appears that too many successive precipitation days were removed with this correction. The second method performed less well on average bias correction, but the temporal precipitation pattern was better. Subsequently, the discharge was calculated by using RACMO2 output as forcing to the HBV-96 hydrological model. A large difference was found between the simulated discharge of the uncorrected RACMO2 run, the WD bias corrected run and the MV bias corrected run. These results show the importance of an appropriate bias correction.
Directory of Open Access Journals (Sweden)
Younghun Jung
2014-05-01
Full Text Available This study suggests an approach to obtain flood extent boundaries using spatial analysis based on Landsat-5 Thematic Mapper imageries and the digital elevation model. The suggested approach firstly extracts the flood inundation areas using the ISODATA image-processing algorithm from four Landsat 5TM imageries. Then, the ground elevations at the intersections of the extracted flood extent boundaries and the specified river cross sections are read from the digital elevation to estimate the elevation-discharge relationship. Lastly, the flood extent is generated based on the estimated elevation-discharge relationship. The methodology was tested over two river reaches in Indiana, United States. The estimated elevation-discharge relationship showed a good match with the correlation coefficients varying between 0.82 and 0.99. In addition, self-validation was also performed for the estimated spatial extent of the flood by comparing it to the waterbody extracted from the Landsat images used to develop the elevation-discharge relationship. The result indicated that the match between the estimated and the extracted flood extents was better with higher flood magnitude. We expect that the suggested methodology will help under-developed and developing countries to obtain flood maps, which have difficulties getting flood maps through traditional approaches based on computer modeling.
Development of Artificial Neural-Network-Based Models for the Simulation of Spring Discharge
Directory of Open Access Journals (Sweden)
M. Mohan Raju
2011-01-01
Full Text Available The present study demonstrates the application of artificial neural networks (ANNs in predicting the weekly spring discharge. The study was based on the weekly spring discharge from a spring located near Ranichauri in Tehri Garhwal district of Uttarakhand, India. Five models were developed for predicting the spring discharge based on a weekly interval using rainfall, evaporation, temperature with a specified lag time. All models were developed both with one and two hidden layers. Each model was developed with many trials by selecting different network architectures and different number of hidden neurons; finally a best predicting model presented against each developed model. The models were trained with three different algorithms, that is, quick-propagation algorithm, batch backpropagation algorithm, and Levenberg-Marquardt algorithm using weekly data from 1999 to 2005. A best model for the simulation was selected from the three presented algorithms using the statistical criteria such as correlation coefficient (, determination coefficient, or Nash Sutcliff's efficiency (DC. Finally, optimized number of neurons were considered for the best model. Training and testing results revealed that the models were predicting the weekly spring discharge satisfactorily. Based on these criteria, ANN-based model results in better agreement for the computation of spring discharge. LMR models were also developed in the study, and they also gave good results, but, when compared with the ANN methodology, ANN resulted in better optimized values.
Maximov, M. Yu.; Novikov, P. A.; Nazarov, D. V.; Rymyantsev, A. M.; Silin, A. O.; Zhang, Y.; Popovich, A. A.
2017-07-01
In this study, thin films of tin dioxide have been synthesized on substrates of silicon and stainless steel by atomic layer deposition (ALD) with tetraethyl tin and by inductively coupled remote oxygen plasma as precursors. Studies of the surface morphology by scanning electron microscopy show a strong dependence on synthesis temperature. According to the x-ray photoelectron spectroscopy measurements, the samples contain tin in the oxidation state +4. The thickness of the thin films for electrochemical performance was approximately 80 nm. Electrochemical cycling in the voltage range of 0.01-0.8 V have shown that tin oxide has a stable discharge capacity of approximately 650 mAh/g during 400 charge/discharge cycles with an efficiency of approximately 99.5%. The decrease in capacity after 400 charge/discharge cycles was around 5-7%. Synthesized SnO2 thin films have fast kinetics of lithium ions intercalation and excellent discharge efficiency at high C-rates, up to 40C, with a small decrease in capacity of less than 20%. Specific capacity and cyclic stability of thin films of SnO2 synthesized by ALD exceed the values mentioned in the literature for pure tin dioxide thin films.
Institute of Scientific and Technical Information of China (English)
D. GUENDOUZ; A. HAMID; A. HENNAD
2011-01-01
Behavior of charged particles in a DC low pressure glow discharge is studied. The electric properties of the glow discharge in argon, maintained by a constant source term with uni- form electron and ion generation, between two plane electrodes or by secondary electron emission at the cathode, are determined. A fluid model is used to solve self-consistently the first three moments of the Boltzmann equation coupled with the Poisson equation. The stationary spatial distribution of the electron and ion densities, the electric potential, the electric field, and the electron energy, in a two-dimensional （2D） configuration, are presented.
Modeling the impact of river discharge and wind on the hypoxia off Yangtze Estuary
Zheng, Jingjing; Gao, Shan; Liu, Guimei; Wang, Hui; Zhu, Xueming
2016-12-01
The phenomenon of low dissolved oxygen (known as hypoxia) in a coastal ocean system is closely related to a combination of anthropogenic and natural factors. Marine hypoxia occurs in the Yangtze Estuary, China, with high frequency and long persistence. It is related primarily to organic and nutrient enrichment influenced by river discharges and physical factors, such as water mixing. In this paper, a three-dimensional hydrodynamic model was coupled to a biological model to simulate and analyze the ecological system of the East China Sea. By comparing with the observation data, the model results can reasonably capture the physical and biochemical dynamics of the Yangtze Estuary. In addition, the sensitive experiments were also used to examine the role of physical forcing (river discharge, wind speed, wind direction) in controlling hypoxia in waters adjacent to the Yangtze Estuary. The results showed that the wind field and river discharge have significant impact on the hypoxia off the Yangtze Estuary. The seasonal cycle of hypoxia was relatively insensitive to synoptic variability in the river discharge, but integrated hypoxic areas were sensitive to the whole magnitude of river discharge. Increasing the river discharge was shown to increase hypoxic areas, while decreasing the river discharge tended to decrease hypoxic areas. The variations of wind speed and direction had a great impact on the integrated hypoxic areas.
Wong, Hannah J; Wu, Robert C; Caesar, Michael; Abrams, Howard; Morra, Dante
2010-08-01
Timely access to emergency patient care is an important quality and efficiency issue. Reduced discharges of inpatients at weekends are a reality to many hospitals and may reduce hospital efficiency and contribute to emergency department (ED) congestion. To evaluate the daily number of ED beds occupied by inpatients after evenly distributing inpatient discharges over the course of the week using a computer simulation model. Simulation modelling study from an academic care hospital in Toronto, Canada. Daily historical data from the general internal medicine (GIM) department between 15 January and 15 December for two years, 2005 and 2006, were used for model building and validation, respectively. There was good agreement between model simulations and historical data for both ED and ward censuses and their respective lengths of stay (LOS), with the greatest difference being +7.8% for GIM ward LOS (model: 9.3 days vs historical: 8.7 days). When discharges were smoothed across the 7 days, the number of ED beds occupied by GIM patients decreased by approximately 27-57% while ED LOS decreased 7-14 hours. The model also demonstrated that patients occupying hospital beds who no longer require acute care have a considerable impact on ED and ward beds. Smoothing out inpatient discharges over the course of a week had a positive effect on decreasing the number of ED beds occupied by inpatients. Despite the particular challenges associated with weekend discharges, simulation experiments suggest that discharges evenly spread across the week may significantly reduce bed requirements and ED LOS.
Fach, S; Sitzenfrei, R; Rauch, W
2009-01-01
It is state of the art to evaluate and optimise sewer systems with urban drainage models. Since spill flow data is essential in the calibration process of conceptual models it is important to enhance the quality of such data. A wide spread approach is to calculate the spill flow volume by using standard weir equations together with measured water levels. However, these equations are only applicable to combined sewer overflow (CSO) structures, whose weir constructions correspond with the standard weir layout. The objective of this work is to outline an alternative approach to obtain spill flow discharge data based on measurements with a sonic depth finder. The idea is to determine the relation between water level and rate of spill flow by running a detailed 3D computational fluid dynamics (CFD) model. Two real world CSO structures have been chosen due to their complex structure, especially with respect to the weir construction. In a first step the simulation results were analysed to identify flow conditions for discrete steady states. It will be shown that the flow conditions in the CSO structure change after the spill flow pipe acts as a controlled outflow and therefore the spill flow discharge cannot be described with a standard weir equation. In a second step the CFD results will be used to derive rating curves which can be easily applied in everyday practice. Therefore the rating curves are developed on basis of the standard weir equation and the equation for orifice-type outlets. Because the intersection of both equations is not known, the coefficients of discharge are regressed from CFD simulation results. Furthermore, the regression of the CFD simulation results are compared with the one of the standard weir equation by using historic water levels and hydrographs generated with a hydrodynamic model. The uncertainties resulting of the wide spread use of the standard weir equation are demonstrated.
Modeling the capillary discharge of an electrothermal (ET) launcher
Least, Travis
Over the past few decades, different branches of the US Department of Defense (DoD) have invested at improving the field ability of electromagnetic launchers. One such focus has been on achieving hypervelocity launch velocities in excess of 7 km/s for direct launch to space applications [1]. It has been shown that pre-injection is required for this to be achieved. One method of pre-injection which has promise involves using an electro-thermal (ET) due to its ability to achieve the desired velocities with a minimal amount of hot plasma injected into the launcher behind the projectile. Despite the demonstration of pre-injection using this method, polymer ablation is not very well known and this makes it challenging to predict how the system will behave for a given input of electrical power. In this work, the rate of ablation has been studied and predicted using different models to generate the best possible characteristic curve. [1] - Wetz, David A., Francis Stefani, Jerald V. Parker, and Ian R. McNab. "Advancements in the Development of a Plasma-Driven Electromagnetic Launcher." IEEE TRANSACTIONS ON MAGNETICS 45.1 (2009): 495--500. IEEE Xplore. Web. 18 Aug. 2012.
Institute of Scientific and Technical Information of China (English)
Chen Ying-Chao; Xie Kai; Pan Yi; Zheng Chun-Man; Wang Hua-Lin
2011-01-01
Nano-LiMn2O4 cathode materials with nano-sized particles are synthesized via a citric acid assisted sol-gel route. The structure, the morphology and the electrochemical properties of the nano-LiMn2O4 are investigated. Compared with the micro-sized LiMn2O4, the nano-LiMn2O4 possesses a high initial capacity (120 mAh/g) at a discharge rate of 0.2 C (29.6 mA/g). The nano-LiMn2O4 also has a good high-rate discharge capability, retaining 91% of its capacity at a discharge rate of 10 C and 73% at a discharge rate of 40 C. In particular, the nano-LiMn2O4 shows an excellent high-rate pulse discharge capability. The cut-off voltage at the end of 50-ms pulse discharge with a discharge rate of 80 C is above 3.40 V, and the voltage returns to over 4.10 V after the pulse discharge. These results show that the prepared nano-LiMn2O4 could be a potential cathode material for the power sources with the capability to deliver very high-rate pulse currents.
Computational Model of One-Dimensional Dielectric Barrier Discharges
2005-06-01
Siemens proposed a special electrical discharge to produce ozone (6:309). In 1955, Tanaka discovered that the DBD could be used for excimer...un t x t n nx t x tnn unn nu t n n n un u t nx t nx t x t n nx t x tunneNE ν δδϕ ϕ δ ν δ ν δϕ ϕϕ δδϕ ϕ ϕ . (91) This process is repeated for the...or blocks, consisting of the coefficients of the δ terms, nx is a four-term sub-vector of the unknown δ ’s and nb is a four-term sub- vector
Neural Network Model for Prediction of Discharged from the Catchments of Langat River, Malaysia
Directory of Open Access Journals (Sweden)
Z. Ahmad
2010-09-01
Full Text Available Artificial neural networks have been shown to be able to approximate any continuous non-linear functions and have been used to build data base empirical models for non-linear processes. In this study, neural networks models were used to model the daily river flows or discharged in Langat River, Malaysia. Two possible ways of modelling were implemented which is by time series prediction and by the dynamics function of the system which include the past value of the discharged and also the rainfall in the input. The sum square error (SSE, residue analysis and correlation coefficient based on the observed and prediction output is chosen as the criteria of selection of which models is appropriate. It was found that the developed neural networks models using dynamics function provided satisfactory model discharges.
Energy Technology Data Exchange (ETDEWEB)
Rodriguez, F. [Department Economia Aplicada, Facultad de Derecho, Campus ' Miguel de Unamuno' , University of Salamanca, Salamanca (Spain)
2000-04-01
The use of a system of transferable discharge permits to control the harmful effects of non-uniformly mixed pollutants requires the application of trading rules in order to prevent permit trading among sources from violating environmental standards. The elements and properties of bilateral trading rules can be analyzed more easily once formulated as exchange rates, which would convert, in a cost-effective way, the emission right potentially given up by the seller into an offsetting emission right acquired by the buyer. In this article, a new expression for such exchange rates is proposed and then analyzed to infer some unexplored properties of the system. 8 refs.
FLUSHING TIME OF THE YANGTZE ESTUARY BY DISCHARGE: A MODEL STUDY
Institute of Scientific and Technical Information of China (English)
Qi Ding-man; Shen Huan-ting; Zhu Jian-rong
2003-01-01
Flushing time of the Yangtze estuary by discharge is one of the important factors responsible for the transport of pollutants from various sources located along the Yangtze estuary: Therefore, an objective of the present study, which analysis flushing time in the case of different discharge is very helpful to evaluate the water environmental of the Yangtze estuary.Using a dissolved conservative material as a tracer in the water, a three-dimension advection-diffusion water exchange numerical model was used to study the flushing time by discharge and the discharge dominated region of the Yangtze estuary.The initial tracer concentration is set to 0.0 in the numerical domain of the Yangtze estuary, and the concentration value is set to 1.0 on the inflow boundary.The tracer flux normal to the solid boundary is set to 0.0.The flushing time and the out limit of discharge dominated region can be calculated in terms of the tracer concentration.Estuarine, Coastal and Ocean Model (ECOM) is used as the hydrodynamic model.The result shows that the flushing time is approximately in inverse proportion to the discharge at the upper stream.The out limit is farther from the upper inflow boundary as discharge increases.The out limit at the north branch is different from that of the south branch because the discharge into the north branch is much less than that into the south branch.The data is qualitative similar to the observed data, which show the three-dimensional advection-diffusion equation can be used to estimate the flushing time and the discharge dominated region of the Yangtze estuary.
Mutzner, Lena; Staufer, Philipp; Ort, Christoph
2016-11-01
Wet-weather discharges contribute to anthropogenic micropollutant loads entering the aquatic environment. Thousands of wet-weather discharges exist in Swiss sewer systems, and we do not have the capacity to monitor them all. We consequently propose a model-based approach designed to identify critical discharge points in order to support effective monitoring. We applied a dynamic substance flow model to four substances representing different entry routes: indoor (Triclosan, Mecoprop, Copper) as well as rainfall-mobilized (Glyphosate, Mecoprop, Copper) inputs. The accumulation on different urban land-use surfaces in dry weather and subsequent substance-specific wash-off is taken into account. For evaluation, we use a conservative screening approach to detect critical discharge points. This approach considers only local dilution generated onsite from natural, unpolluted areas, i.e. excluding upstream dilution. Despite our conservative assumptions, we find that the environmental quality standards for Glyphosate and Mecoprop are not exceeded during any 10-min time interval over a representative one-year simulation period for all 2500 Swiss municipalities. In contrast, the environmental quality standard is exceeded during at least 20% of the discharge time at 83% of all modelled discharge points for Copper and at 71% for Triclosan. For Copper, this corresponds to a total median duration of approximately 19 days per year. For Triclosan, discharged only via combined sewer overflows, this means a median duration of approximately 10 days per year. In general, stormwater outlets contribute more to the calculated effect than combined sewer overflows for rainfall-mobilized substances. We further evaluate the Urban Index (Aurban,impervious/Anatural) as a proxy for critical discharge points: catchments where Triclosan and Copper exceed the corresponding environmental quality standard often have an Urban Index >0.03. A dynamic substance flow analysis allows us to identify the most
Dynamic modeling of environmental risk associated with drilling discharges to marine sediments.
Durgut, İsmail; Rye, Henrik; Reed, Mark; Smit, Mathijs G D; Ditlevsen, May Kristin
2015-10-15
Drilling discharges are complex mixtures of base-fluids, chemicals and particulates, and may, after discharge to the marine environment, result in adverse effects on benthic communities. A numerical model was developed to estimate the fate of drilling discharges in the marine environment, and associated environmental risks. Environmental risk from deposited drilling waste in marine sediments is generally caused by four types of stressors: oxygen depletion, toxicity, burial and change of grain size. In order to properly model these stressors, natural burial, biodegradation and bioturbation processes were also included. Diagenetic equations provide the basis for quantifying environmental risk. These equations are solved numerically by an implicit-central differencing scheme. The sediment model described here is, together with a fate and risk model focusing on the water column, implemented in the DREAM and OSCAR models, both available within the Marine Environmental Modeling Workbench (MEMW) at SINTEF in Trondheim, Norway.
Neural Network Model for Prediction of Discharged from the Catchments of Langat River, Malaysia
2010-01-01
Artificial neural networks have been shown to be able to approximate any continuous non-linear functions and have been used to build data base empirical models for non-linear processes. In this study, neural networks models were used to model the daily river flows or discharged in Langat River, Malaysia. Two possible ways of modelling were implemented which is by time series prediction and by the dynamics function of the system which include the past value of the discharged and also th...
Collisional-radiative model of helium microwave discharges at atmospheric pressure
Santos, M.; Alves, L. L.; Gadonna, K.; Belmonte, T.
2011-10-01
This paper presents a stationary collisional-radiative model to describe the behavior of helium microwave discharges (2.45 GHz), produced in cylindrical geometry (1 mm radius) at atmospheric pressure. The model couples the rate balance equations for the charged particles (electrons, He+ and He2+ions), the He(n excimers, to the two-term homogeneous and stationary electron Boltzmann equation,. The latter is solved using a coherent set of electron cross sections, adjusted to ensure good predictions of the swarm parameters and the Townsend ionization coefficient. The model was solved for typical 5x1014 cm-3 electron density and 2500 K gas temperature, yielding [He2+]/[He+] ~ 0.92 and [He2*]/[He] ~ 3.4x10-8. Results show also that the He2+ions are produced mainly from the 3-body conversion of He+ ions and lost by the corresponding reverse reaction together with diffusion and dissociative recombination. The He2*is produced by a 3-body reaction involving the 23P states and by the electron-stabilized recombination of He2+and is lost by electron dissociation. This paper presents a stationary collisional-radiative model to describe the behavior of helium microwave discharges (2.45 GHz), produced in cylindrical geometry (1 mm radius) at atmospheric pressure. The model couples the rate balance equations for the charged particles (electrons, He+ and He2+ions), the He(n excimers, to the two-term homogeneous and stationary electron Boltzmann equation,. The latter is solved using a coherent set of electron cross sections, adjusted to ensure good predictions of the swarm parameters and the Townsend ionization coefficient. The model was solved for typical 5x1014 cm-3 electron density and 2500 K gas temperature, yielding [He2+]/[He+] ~ 0.92 and [He2*]/[He] ~ 3.4x10-8. Results show also that the He2+ions are produced mainly from the 3-body conversion of He+ ions and lost by the corresponding reverse reaction together with diffusion and dissociative recombination. The He2*is produced
Carman, R J
2003-01-01
A detailed rate-equation analysis has been used to simulate the plasma kinetics in a pulsed-excited dielectric barrier discharge in xenon, under operating conditions where the discharge structure is spatially homogeneous. The one-dimensional model, incorporating 14 species and 70 reaction processes, predicts results that are in good agreement with experimental measurements of the electrical characteristics, and optical (vacuum-ultraviolet (VUV) and visible) pulse shapes. The model reveals that electrical breakdown of the discharge gap occurs via a fast-moving ionization/excitation wavefront that starts close to the anode dielectric and propagates towards the cathode at approx 3x10 sup 5 m s sup - sup 1. The wavefront appears as a result of successive avalanches of electrons that propagate across the discharge gap after release from the cathode dielectric. During breakdown, the mean electron energy in the bulk plasma is close to optimum for preferential excitation of the Xe* 1s sub 4 sub , sub 5 states that fe...
Readmissions and death after ICU discharge: development and validation of two predictive models.
Directory of Open Access Journals (Sweden)
Omar Badawi
Full Text Available INTRODUCTION: Early discharge from the ICU is desirable because it shortens time in the ICU and reduces care costs, but can also increase the likelihood of ICU readmission and post-discharge unanticipated death if patients are discharged before they are stable. We postulated that, using eICU® Research Institute (eRI data from >400 ICUs, we could develop robust models predictive of post-discharge death and readmission that may be incorporated into future clinical information systems (CIS to assist ICU discharge planning. METHODS: Retrospective, multi-center, exploratory cohort study of ICU survivors within the eRI database between 1/1/2007 and 3/31/2011. EXCLUSION CRITERIA: DNR or care limitations at ICU discharge and discharge to location external to hospital. Patients were randomized (2∶1 to development and validation cohorts. Multivariable logistic regression was performed on a broad range of variables including: patient demographics, ICU admission diagnosis, admission severity of illness, laboratory values and physiologic variables present during the last 24 hours of the ICU stay. Multiple imputation was used to address missing data. The primary outcomes were the area under the receiver operator characteristic curves (auROC in the validation cohorts for the models predicting readmission and death within 48 hours of ICU discharge. RESULTS: 469,976 and 234,987 patients representing 219 hospitals were in the development and validation cohorts. Early ICU readmission and death was experienced by 2.54% and 0.92% of all patients, respectively. The relationship between predictors and outcomes (death vs readmission differed, justifying the need for separate models. The models for early readmission and death produced auROCs of 0.71 and 0.92, respectively. Both models calibrated well across risk groups. CONCLUSIONS: Our models for death and readmission after ICU discharge showed good to excellent discrimination and good calibration. Although
Realizations of interest rate models
Nieuwenhuis, J.W.
2000-01-01
In this paper we comment on a recent paper by Bj¨ork and Gombani. In contrast to this paper our starting point is not the Musiela equation but the forward rate dynamics. In our approach we do not need to talk about infinitesimal generators.
Realizations of interest rate models
Nieuwenhuis, J.W.
2000-01-01
In this paper we comment on a recent paper by Bj¨ork and Gombani. In contrast to this paper our starting point is not the Musiela equation but the forward rate dynamics. In our approach we do not need to talk about infinitesimal generators.
Multiplicative earthquake likelihood models incorporating strain rates
Rhoades, D. A.; Christophersen, A.; Gerstenberger, M. C.
2017-01-01
SUMMARYWe examine the potential for strain-rate variables to improve long-term earthquake likelihood models. We derive a set of multiplicative hybrid earthquake likelihood models in which cell rates in a spatially uniform baseline model are scaled using combinations of covariates derived from earthquake catalogue data, fault data, and strain-rates for the New Zealand region. Three components of the strain rate estimated from GPS data over the period 1991-2011 are considered: the shear, rotational and dilatational strain rates. The hybrid model parameters are optimised for earthquakes of M 5 and greater over the period 1987-2006 and tested on earthquakes from the period 2012-2015, which is independent of the strain rate estimates. The shear strain rate is overall the most informative individual covariate, as indicated by Molchan error diagrams as well as multiplicative modelling. Most models including strain rates are significantly more informative than the best models excluding strain rates in both the fitting and testing period. A hybrid that combines the shear and dilatational strain rates with a smoothed seismicity covariate is the most informative model in the fitting period, and a simpler model without the dilatational strain rate is the most informative in the testing period. These results have implications for probabilistic seismic hazard analysis and can be used to improve the background model component of medium-term and short-term earthquake forecasting models.
New pixelized Micromegas detector with low discharge rate for the COMPASS experiment
Neyret, D.; Anfreville, M.; Bedfer, Y.; Burtin, E.; Coquelet, C.; d'Hose, N.; Desforge, D.; Giganon, A.; Jourde, D.; Kunne, F.; Magnon, A.; Makke, N.; Marchand, C.; Paul, B.; Platchkov, S.; Thibaud, F.; Usseglio, M.; Vandenbroucke, M.
2012-01-01
New Micromegas (Micro-mesh gaseous detectors) are being developed in view of the future physics projects planned by the COMPASS collaboration at CERN. Several major upgrades compared to present detectors are being studied: detectors standing five times higher luminosity with hadron beams, detection of beam particles (flux up to a few hundred of kHz/mm^{2}, 10 times larger than for the present Micromegas detectors) with pixelized read-out in the central part, light and integrated electronics, and improved robustness. Two solutions of reduction of discharge impact have been studied, with Micromegas detectors using resistive layers and using an additional GEM foil. Performance of such detectors has also been measured. A large size prototypes with nominal active area and pixelized read-out has been produced and installed at COMPASS in 2010. In 2011 prototypes featuring an additional GEM foil, as well as an resistive prototype, are installed at COMPASS and preliminary results from those detectors presented very go...
High-rate deposition of silicon films in a magnetron discharge with liquid target
Tumarkin, A.; Zibrov, M.; Khodachenko, G.; Tumarkina, D.
2016-10-01
Silicon coatings have been deposited on substrates made of low-carbon and high- carbon steels and tungsten in a magnetron discharge with liquid target at substrate bias voltages ranging from +100 V to -600 V. The structure of obtained coatings was examined by a scanning electron microscopy. The strong influence of substrate bias voltage on the coating structure was observed. The corrosion resistance of coated steel samples was examined in concentrated sulphuric, hydrochloric and nitric acids and their solutions. The resistance of coated tungsten samples against high-temperature oxidation was examined by their exposure to O2 gas at a pressure of 0.2 Pa and a temperature of 1073 K. The coatings deposited under bias voltages of+100 V and -600 V had dense structures and showed the best protective properties among all deposited coatings.
Modeling plasma glow discharges in Air near a Mach 3 bow shock with KRONOS
Rassou, Sebastien; Labaune, Julien; Packan, Denis; Elias, Paul-Quentin
2016-09-01
In this work, plasma glow discharge in Air is modeled near a Mach 3 bow shock. Numerical simulations are performed using the coupling KRONOS which have been developed at ONERA. The flow field is modeled using the code CFD: CEDRE from ONERA and the electrical and plasma part by the EDF open-source code CODE_SATURNE. The plasma kinetic modeling consists on a two-term Boltzmann equation solver and a chemical reaction solver depending of the electric field. The coupling KRONOS is fully parallelized and run on ONERA supercomputers. The shock wave is formed by the propagation of a supersonic flow (M = 3) through a truncated conical model mounted with a central spike. Depending on the spike's voltage value, corona, glow or arc regime could be obtained in a steady flow. The parameters for the supersonic flow and the spike configurations are chosen to be in glow discharge regime and to reproduce the experimental setup. In our simulations, 12 species and 80 reactions (ionization, electronic or vibrational excitation, attachment etc ...) are considered to properly model the glow discharge and the afterglow. In a stationary flow, glow discharge is observed only at the upstream of the shock wave near the high voltage spike. Behind the bow shock, in the afterglow, negative ions are provided by electrons attachment with O2. The negative ions flow convection ensures the electrical conduction and the establishment of the glow discharge.
Better Modeling of Electrostatic Discharge in an Insulator
Pekov, Mihail
2010-01-01
An improved mathematical model has been developed of the time dependence of buildup or decay of electric charge in a high-resistivity (nominally insulating) material. The model is intended primarily for use in extracting the DC electrical resistivity of such a material from voltage -vs.- current measurements performed repeatedly on a sample of the material over a time comparable to the longest characteristic times (typically of the order of months) that govern the evolution of relevant properties of the material. This model is an alternative to a prior simplistic macroscopic model that yields results differing from the results of the time-dependent measurements by two to three orders of magnitude.
Biological evolution model with conditional mutation rates
Saakian, David B.; Ghazaryan, Makar; Bratus, Alexander; Hu, Chin-Kun
2017-05-01
We consider an evolution model, in which the mutation rates depend on the structure of population: the mutation rates from lower populated sequences to higher populated sequences are reduced. We have applied the Hamilton-Jacobi equation method to solve the model and calculate the mean fitness. We have found that the modulated mutation rates, directed to increase the mean fitness.
An "Emergent Model" for Rate of Change
Herbert, Sandra; Pierce, Robyn
2008-01-01
Does speed provide a "model for" rate of change in other contexts? Does JavaMathWorlds (JMW), animated simulation software, assist in the development of the "model for" rate of change? This project investigates the transference of understandings of rate gained in a motion context to a non-motion context. Students were 27 14-15 year old students at…
Capillary Discharge Thruster Experiments and Modeling (Briefing Charts)
2016-06-01
PROPULSION MODELS & EXPERIMENTS Spacecraft Propulsion Relevant Plasma: From hall thrusters to plumes and fluxes on components Complex reaction physics i.e...PROPULSION MODELS & EXPERIMENTS Spacecraft Propulsion Relevant Plasma: From hall thrusters to plumes and fluxes on components Complex reaction ...Conductivity h is the Enthalpy Cs is the Sound Speed Θ is the Wall Energy Flux Pekker, 40th AIAA Plasmadynamics and Laser Conference, 2009. R.S. MARTIN (ERC INC
Drift-diffusion model of normal glow discharge in an axial magnetic field
Surzhikov, S. T.
2016-12-01
A two-dimensional axisymmetrical computing model is formulated with using of which the mathematical modeling of the normal glow discharge in molecular hydrogen is fulfilled in an axial magnetic field with the induction B = 0.1 T in the pressure range p = 1.25-5 Torr and the current-source electromotive force E = 1-3 kV.
Large-scale Ice Discharge Events in a Pure Ice Sheet Model
Alverson, K.; Legrand, P.; Papa, B. D.; Mysak, L. A.; Wang, Z.
2004-05-01
Sediment cores in the North Atlantic show evidence of periodic large-scale ice discharge events between 60 ka and 10 ka BP. These events occurred with a typical period between 5 kyr and 10 kyr. During each event, a significant amount of ice was discharged from the Hudson Bay region through the Hudson Strait and into the North Atlantic. This input of freshwater through the melting of icebergs is thought to have strongly affected the Atlantic thermohaline circulation. One theory is that these periodic ice discharge events represent an internal oscillation of the ice sheet under constant forcing. A second theory requires some variable external forcing on an unstable ice sheet to produce a discharge event. Using the ice sheet model of Marshall, an attempt is made to simulate periodic large-scale ice discharge events within the framework of the first theory. In this case, ice sheet surges and large-scale discharge events occur as a free oscillation of the ice sheet. An analysis of the activation of ice surge events and the thermodynamic controls on these events is also made.
Madarang, Krish J; Kang, Joo-Hyon
2014-06-01
Stormwater runoff has been identified as a source of pollution for the environment, especially for receiving waters. In order to quantify and manage the impacts of stormwater runoff on the environment, predictive models and mathematical models have been developed. Predictive tools such as regression models have been widely used to predict stormwater discharge characteristics. Storm event characteristics, such as antecedent dry days (ADD), have been related to response variables, such as pollutant loads and concentrations. However it has been a controversial issue among many studies to consider ADD as an important variable in predicting stormwater discharge characteristics. In this study, we examined the accuracy of general linear regression models in predicting discharge characteristics of roadway runoff. A total of 17 storm events were monitored in two highway segments, located in Gwangju, Korea. Data from the monitoring were used to calibrate United States Environmental Protection Agency's Storm Water Management Model (SWMM). The calibrated SWMM was simulated for 55 storm events, and the results of total suspended solid (TSS) discharge loads and event mean concentrations (EMC) were extracted. From these data, linear regression models were developed. R(2) and p-values of the regression of ADD for both TSS loads and EMCs were investigated. Results showed that pollutant loads were better predicted than pollutant EMC in the multiple regression models. Regression may not provide the true effect of site-specific characteristics, due to uncertainty in the data.
High order fluid model for streamer discharges: I. Derivation of model and transport data
Dujko, S; White, R D; Ebert, U
2013-01-01
Streamer discharges pose basic problems in plasma physics, as they are very transient, far from equilibrium and have high ionization density gradients; they appear in diverse areas of science and technology. The present paper focuses on the derivation of a high order fluid model for streamers. Using momentum transfer theory, the fluid equations are obtained as velocity moments of the Boltzmann equation; they are closed in the local mean energy approximation and coupled to the Poisson equation for the space charge generated electric field. The high order tensor in the energy flux equation is approximated by the product of two lower order moments to close the system. The average collision frequencies for momentum and energy transfer in elastic and inelastic collisions for electrons in molecular nitrogen are calculated from a multi term Boltzmann equation solution. We then discuss, in particular, (1) the correct implementation of transport data in streamer models; (2) the accuracy of the two term approximation f...
Campuzano, Francisco; Brito, David; Juliano, Manuela; Fernandes, Rodrigo; Neves, Ramiro
2015-04-01
In the Iberian Peninsula, most of the largest rivers discharge on the Atlantic coast draining almost two thirds of the territory. It is an important source of nutrients and sediments to these coastal areas. Rivers discharges in the Atlantic area when compared with the ones in the Mediterranean side present the particularity that their water before is released into the ocean is previously mixed in their estuaries in a different ratio depending of the estuarine residence time and the discharged flow. In order to evaluate the relative importance of the inland waters in the circulation patterns of Western Iberia, the rivers discharges were implemented in the PCOMS model application (Portuguese Coast Operational Modelling System). To reproduce the water continuum including the different spatial and temporal scales, a methodology consisting in a system of integrated models using the Mohid model was designed. At the watershed level, the Mohid Land model calculated operationally water flow and properties, including nutrients, for the main river catchments of Western Iberian with a 2 km horizontal resolution. Downstream, several operational hydrodynamic and biological estuarine applications used those outcomes as model inputs, filling the gaps in the observation network. From the estuarine models, the tidally modulated water and properties fluxes to the coast were obtained. These fluxes were finally imposed in the Portuguese Coast Operational Modelling System (PCOMS), a fully 3D baroclinic hydrodynamic and ecological regional model that covers the Iberian Atlantic front. The fate of the rivers discharges were analysed by integrating model results in boxes, comparing the climatologies obtained with and without rivers and the rivers area of influence was obtained by lagrangian tracers simulations.
Discharge model for the lithium iron-phosphate electrode
Energy Technology Data Exchange (ETDEWEB)
Srinivasan, Venkat; Newman, John
2004-02-28
This paper develops a mathematical model for lithium intercalation and phase change in an iron phosphate-based lithium-ion cell in order to understand the cause for the low power capability of the material. The juxtaposition of the two phases is assumed to be in the form of a shrinking core, where a shell of one phase covers a core of the second phase. Diffusion of lithium through the shell and the movement of the phase interface are described and incorporated into a porous electrode model consisting of two different particle sizes. Open-circuit measurements are used to estimate the composition ranges of the single-phase region. Model-experimental comparisons under constant current show that ohmic drops in the matrix phase, contact resistances between the current collector and the porous matrix, and transport limitations in the iron phosphate particle limit the power capability of the cells. Various design options, consisting of decreasing the ohmic drops, using smaller particles, and substituting the liquid electrolyte by a gel are explored, and their relative importance discussed. The model developed in this paper can be used as a means of optimizing the cell design to suit a particular application.
High order fluid model for ionization fronts in streamer discharges
Markosyan, A.; Dujko, S.; Ebert, U.; Almeida, P.G.C.; Alves, L.L.; Guerra, V.
2012-01-01
A high order fluid model for streamer dynamics is developed by closing the system after the 4th mo- ment of the Boltzmann equation in local mean energy approximation. This is done by approximating the high order pressure tensor in the heat flux equation through the previous moments. The electric fi
An Research on Electrical Vehicle'S Charge-Discharge Behavior Based on Logit Model
Xiaoyin, Wang; Junyong, Liu
Electric Vehicle is the future trend of the automobile industry, and the energy exchanging between the electrical vehicles and the grid through the vehicle-to-grid (V2G) technology becomes possiable. V2G leads to a rapid load growth effecting the benefit of the grid, which wasn't discussed. The charge and discharge model of the electrical vehicles is discussed using the multinomial logit model based on the discrete choice theory, then preliminarily evaluates the effects of economic benefit both on the motorist and the grid. Finally, suggestions on period division and electricity pricing for charge and discharge of the electrical vehicle are given.
An efficient model to simulate stable glow corona discharges and their transition into streamers
Liu, Lipeng; Becerra, Marley
2017-03-01
A computationally efficient model to evaluate stable glow corona discharges and their transition into streamers is proposed. The simplified physical model referred to as the SPM is based on the classic hydrodynamic model of charge particles and a quasi-steady state approximation for electrons. The solution follows a two-step segregated procedure, which solves sequentially the stationary continuity equation for electrons and then time-dependent continuity equations for ions. The validity of using the SPM to simulate glow corona discharges and their transition into streamers is demonstrated by performing comparisons with a fully coupled physical model (FPM) and with experimental data available in the literature for air under atmospheric conditions. It is shown that the SPM can obtain estimates similar to those calculated with the FPM and those measured in experiments but using significantly less computation time. Since the proposed model simulates efficiently the ionization layer without prior knowledge of the surface electric field or the discharge current, it is a computationally efficient alternative to calculations of glow corona discharges based on Kaptzov’s approximation (KAM). The model can also be employed to efficiently calculate the conditions for the transition of glow corona into streamers, overcoming the limitations of KAM to provide such estimates.
DEFF Research Database (Denmark)
Draghici, Mihai; Stamate, Eugen
2010-01-01
Negative ion production is investigated in a chamber with transversal magnetic filter operated in dc or inductively coupled plasma (ICP) modes in Ar/SF6 gas mixtures. Plasma parameters are evaluated by mass spectrometry and Langmuir probe for different discharge conditions. The density ratio...... of negative ion to electron exceeded 300 in dc mode while it was below 100 in the ICP mode. The possibility to apply a large positive bias to an electrode without affecting the plasma potential and the transition from a negative sheath to anodic glow are also investigated. The etching rates by positive...... and negative ions are evaluated on silicon substrate for different Ar/SF6 gas ratios. The etching rate by negative ions was with less than 5% smaller than that by positive ions....
Self-Consistent Model for Pulsed Direct-Current N2 Glow Discharge
Institute of Scientific and Technical Information of China (English)
Liu Chengsen; Wang Dezhen
2005-01-01
A self-consistent analysis of a pulsed direct-current (DC) N2 glow discharge is presented. The model is based on a numerical solution of the continuity equations for electron and ions coupled with Poisson's equation. The spatial-temporal variations of ionic and electronic densities and electric field are obtained. The electric field structure exhibits all the characteristic regions of a typical glow discharge (the cathode fall, the negative glow, and the positive column).Current-voltage characteristics of the discharge can be obtained from the model. The calculated current-voltage results using a constant secondary electron emission coefficient for the gas pressure 133.32 Pa are in reasonable agreement with experiment.
Directory of Open Access Journals (Sweden)
Ph. Weng
2003-01-01
Full Text Available Interaction between a wetland and its surrounding aquifer was studied in the Rochefort agricultural marsh (150 km2. Groundwater discharge in the marsh was measured with a network of nested piezometers. Hydrological modelling of the wetland showed that a water volume of 770,000 m3 yr–1 is discharging into the marsh, but that this water flux essentially takes place along the lateral borders of the wetland. However, this natural discharge volume represents only 20% of the artificial freshwater injected each year into the wetland to maintain the water level close to the soil surface. Understanding and quantifying the groundwater component in wetland hydrology is crucial for wetland management and conservation. Keywords: wetland, hydrology, groundwater, modelling, marsh
Three-dimensional modeling of the neutral gas depletion effect in a helicon discharge plasma
Kollasch, Jeffrey; Schmitz, Oliver; Norval, Ryan; Reiter, Detlev; Sovinec, Carl
2016-10-01
Helicon discharges provide an attractive radio-frequency driven regime for plasma, but neutral-particle dynamics present a challenge to extending performance. A neutral gas depletion effect occurs when neutrals in the plasma core are not replenished at a sufficient rate to sustain a higher plasma density. The Monte Carlo neutral particle tracking code EIRENE was setup for the MARIA helicon experiment at UW Madison to study its neutral particle dynamics. Prescribed plasma temperature and density profiles similar to those in the MARIA device are used in EIRENE to investigate the main causes of the neutral gas depletion effect. The most dominant plasma-neutral interactions are included so far, namely electron impact ionization of neutrals, charge exchange interactions of neutrals with plasma ions, and recycling at the wall. Parameter scans show how the neutral depletion effect depends on parameters such as Knudsen number, plasma density and temperature, and gas-surface interaction accommodation coefficients. Results are compared to similar analytic studies in the low Knudsen number limit. Plans to incorporate a similar Monte Carlo neutral model into a larger helicon modeling framework are discussed. This work is funded by the NSF CAREER Award PHY-1455210.
A model for precessing helical vortex in the turbine discharge cone
Kuibin, P. A.; Susan-Resiga, R. F.; Muntean, S.
2014-03-01
The decelerated swirling flow in the discharge cone of hydraulic turbine develops various self-induced instabilities and associated low frequency phenomena when the turbine is operated far from the best efficiency regime. In particular, the precessing helical vortex ("vortex rope") developed at part-load regimes is notoriously difficult and expensive to be computed using full three-dimensional turbulent unsteady flow models. On the other hand, modern design and optimization techniques require robust, tractable and accurate a-priori assessment of the turbine flow unsteadiness level within a wide operating range before actually knowing the runner geometry details. This paper presents the development and validation of a quasi-analytical model of the vortex rope in the discharge cone. The first stage is the computing of the axisymmetrical swirling flow at runner outlet with input information related only to the operating point and to the blade outlet angle. Then, the swirling flow profile further downstream is computed in successive cross-sections through the discharge cone. The second stage is the reconstruction of the precessing vortex core parameters in successive cross-sections of the discharge cone. The final stage lies in assembling 3D unsteady flow field in the discharge cone. The end result is validated against both experimental and numerical data.
Modelling the landslide area and sediment discharge in landslide-dominated region, Taiwan
Teng, Tse-Yang; Huang, -Chuan, Jr.; Lee, Tsung-Yu; Chen, Yi-Chin; Jan, Ming-Young; Liu, Cheng-Chien
2016-04-01
Many studies have indicated the magnified increase of rainfall intensification, landsliding and subsequent sediment discharge due to the global warming effect. However, a few works synthesized the "chain reaction" from rainfall, landsliding to sediment discharge at the same time because of the limited observations of landslide area and sediment discharge during episodes. Besides, the sediment transport strongly depends on the sediment supply and stream power which interact conditionally. In this study, our goal is to build a model that can simulate time-series landslide area and subsequent sediment discharge. The synthesized model would be applied onto Tsengwen Reservoir watershed in southern Taiwan, where lots of landslides occur every year. Unlike other studies, our landslide model considers not only rainfall effect but also previous landslide status, which may be applied to landslide-dominated regions and explains the irrelevant relationship between typhoon rainfall and landslide area. Furthermore, our sediment transport model considers the sediment budget which couples transport- and supply-limited of sediment. The result shows that the simulated time-series landslide area and the sediment transport agree with the observation and the R2 are 0.88 and 0.56, respectively. Reactivated ratio of previous landslide area is 72.7% which indicates the high reoccurrence of historical landslide in landslide-dominated regions. We divided nine historical typhoons into three periods to demonstrate the effect of sediment supply/supply-limited condition upon sediment transport. For instance, the rainfall is smaller in period 3 than in period 1 but the sediment transport is higher in period 3 due to the catastrophic landslide (typhoon Morakot) during period 2. We argue that quantifying sediment transport should couple not only with water discharge but sediment budget, which is rarely considered in calculating sediment transport. Moreover, the parameterization of the controlling
Analytical Model to Describe the Thermal Behavior of a Heat Discharge System in Roofs
Directory of Open Access Journals (Sweden)
Hernández-Gómez V.H.
2012-01-01
Full Text Available The present study proposes an analytical model which describes the thermal behavior of a heat discharge system in roof, when the surfaces that constitute it are not translucent. Such a model derives from a thermal balance carried out to a heat discharge system in roofs. To validate it, an experimental prototype that allows simulating the thermal behavior of a heat discharge system in wall and roof was used, and the results were compared to those obtained with the proposed analytical model. It was found that the thermal behavior of the analytical model is similar to the thermal behavior of the experimental prototype; a worthless variation was detected among their respective outcome (The difference of temperatures can be caused by the heat transfer coefficient, of which no studies defining its behavior accurately have been found. Therefore, it can be considered that the proposed analytical model can be employed to simulate the thermal behavior of a heat discharge system in roofs when the surfaces that constitute it are opaque.
Dekić, L.; Mihalović, A.; Jovičić, I.; Vladiković, D.; Jerinić, J.; Ivković, M.
2012-04-01
This paper examines two episodes of heavy rainfall and significantly increased water levels. The first case relates to the period including the beginning and the end of the third decade of June 2010 at the Kolubara river basin, where extreme rainfall led to two big flood waves on the Kolubara river, whereat water levels exceeded both regular and extraordinary flood defence and approached their historical maximum. The second case relates to the period including the end of November and the beginning of December 2010 at the Jadar river basin, where heavier precipitation caused the water levels of the basin to reach and surpass the occurrence limit (warning level). The HBV (Hydrological Bureau Waterbalance-section) rainfall/snowmelt - runoff model installed at the RHMSS uses gridded quantitative precipitation and air temperature forecast for 72 hours in advance based on meteorological weather forecast WRF-NMM mesoscale model. Nonhydrostatic Mesoscale Model (NMM) core of the Weather Research and Forecasting (WRF) system is flexible state-of-the-art numerical weather prediction model capable to describe and estimate powerful nonhydrostatic mechanism in convective clouds that cause heavy rain. The HBV model is a semi-distributed conceptual catchment model in which the spatial structure of a catchment area is not explicitly modelled. Instead, the sub-basin represents a primary modelling unit while the basin is characterised by area-elevation distribution and classification of vegetation cover and land use distributed by height zone. WRF-NMM forecast shows very good agreement with observations in terms of timing, location and amount of precipitation. They are used as input for HBV model, forecasted discharges at the output profile of the selected river basin represent model output for consideration. 1 Republic Hydrometeorological Service of Serbia
Modeling helicity dissipation-rate equation
Yokoi, Nobumitsu
2016-01-01
Transport equation of the dissipation rate of turbulent helicity is derived with the aid of a statistical analytical closure theory of inhomogeneous turbulence. It is shown that an assumption on the helicity scaling with an algebraic relationship between the helicity and its dissipation rate leads to the transport equation of the turbulent helicity dissipation rate without resorting to a heuristic modeling.
Demkin, V. P.; Melnichuk, S. V.
2017-06-01
Results of numerical experiment on modeling of the atmospheric-pressure plasma formed during the spark-to-glow discharge transition in helium in low-current non-stationary plasmatron are presented. The numerical experiment is performed using the developed 2D physical and mathematical plasma model in the drift-diffusion approximation. Results of numerical calculation of the dynamics of discharge evolution are confirmed by the experimental data on the atmospheric-pressure plasma dynamics formed in the plasmatron during the spark-to-glow discharge transition. It is demonstrated that with preset initial conditions characteristic for spark breakdown, further discharge evolution leads to the formation of the near-cathode zone of the potential drop and the pulsed behavior of the electric current of the discharge. After the current pulse, the discharge transforms into the quasi-stationary mode with parameters characteristic for the glow discharge with monotonically increasing electric current and transverse dimensions of the plasma column.
Studies on fluid model for numerical simulation of gas discharges in color plasma displays
Institute of Scientific and Technical Information of China (English)
HE Feng; LIU Chun-Liang
2005-01-01
The fluid models of gas discharge in alternating current plasma display panel (AC PDP) cell are discussed.From the Boltzmann equation, the hydrodynamic equations are derived, but this model consumes much computa tional time for simulation. The drift-diffusion approximation model and the local field approximation model are ob tained to simplify the numerical computation, and the approximation conditions of these two models are discussed in detail. The drift-diffusion approximation model gives more satisfactory result for PDP simulation, and the expression of energy balance equation is given completely in this model.
Modeling discharge, temperature, and water quality in the Tualatin River, Oregon
Rounds, Stewart A.; Wood, Tamara M.; Lynch, Dennis D.
1999-01-01
The discharge, water temperature, and water quality of the Tualatin River in northwestern Oregon was simulated with CE-QUAL-W2, a two-dimensional, laterally averaged model developed by the U.S. Army Corps of Engineers. The model was calibrated for May through October periods of 1991, 1992, and 1993. Nine hypothetical scenarios were tested with the model to provide insight for river managers and regulators.
1D fluid model of the dielectric barrier discharge in chlorine
Avtaeva, Svetlana
2016-09-01
The 1D fluid model of the dielectric barrier discharge (DBD) in pure chlorine is developed. The discharge is excited in 8 mm gas gap between quartz dielectric layers of 2 mm thickness covered metallic electrodes. The source voltage US =U0 sin ωt with a frequency 100 kHz and amplitude 8 kV is applied to the electrodes. Chlorine pressure is varied from 15 to 100 Torr. At pressure of 15 Torr a breakdown appears with voltage drop across the discharge gap about 1 kV whereas at 100 Torr it appears with voltage drop about 2 kV. After the first current spike some lower current spikes are observes with chlorine pressure of 100 Torr and large in number current spikes of about identical magnitude are observed with the pressure of 15 Torr. The maximal current density at all pressures reaches about 4 mA/cm.2Total density of surface charge deposited on the electrodes during a half-cycle decreases with chlorine pressure because duration of the current spike discharge phase reduces with chlorine pressure. The average power density inputted in the discharge is 2.5-5.8 W/cm3 per a cycle. The Cl2 plasma is electronegative, the most abundant ions are Cl2+and Cl-. It is shown, that ions get about 95% of the discharge power as electrons get about 5% of the discharge power. 67-97% of the electron power is spending for dissociation and ionization of Cl2 molecules. Emission of Cl* atoms and Cl2*molecules is weak.
The ability of a GCM-forced hydrological model to reproduce global discharge variability
Directory of Open Access Journals (Sweden)
F. C. Sperna Weiland
2010-08-01
Full Text Available Data from General Circulation Models (GCMs are often used to investigate hydrological impacts of climate change. However GCM data are known to have large biases, especially for precipitation. In this study the usefulness of GCM data for hydrological studies, with focus on discharge variability and extremes, was tested by using bias-corrected daily climate data of the 20CM3 control experiment from a selection of twelve GCMs as input to the global hydrological model PCR-GLOBWB. Results of these runs were compared with discharge observations of the GRDC and discharges calculated from model runs based on two meteorological datasets constructed from the observation-based CRU TS2.1 and ERA-40 reanalysis. In the first dataset the CRU TS 2.1 monthly timeseries were downscaled to daily timeseries using the ERA-40 dataset (ERA6190. This dataset served as a best guess of the past climate and was used to analyze the performance of PCR-GLOBWB. The second dataset was created from the ERA-40 timeseries bias-corrected with the CRU TS 2.1 dataset using the same bias-correction method as applied to the GCM datasets (ERACLM. Through this dataset the influence of the bias-correction method was quantified. The bias-correction was limited to monthly mean values of precipitation, potential evaporation and temperature, as our focus was on the reproduction of inter- and intra-annual variability.
After bias-correction the spread in discharge results of the GCM based runs decreased and results were similar to results of the ERA-40 based runs, especially for rivers with a strong seasonal pattern. Overall the bias-correction method resulted in a slight reduction of global runoff and the method performed less well in arid and mountainous regions. However, deviations between GCM results and GRDC statistics did decrease for Q, Q90 and IAV. After bias-correction consistency amongst
SIGMA-COORDINATE NUMERICAL MODEL FOR SIDE-DISCHARGE INTO NATURAL RIVERS
Institute of Scientific and Technical Information of China (English)
LIU Zhao-wei; CHEN Yong-can; LI Ling; ZHENG Jing-yun
2009-01-01
Due to large topography slopes in natural rivers, pollutant concentration embodies a property of three-dimensional distribution when wastewater is discharged from effluents along the bank. With the sigma coordinate along the vertical dimension fitted to both the moving free surface and the bed topography, a three-dimensional numerical model was developed in the present work to address pollutant transport processes in the above-mentioned cases. To avoid the reduction in accuracy caused by spurious diffusion in the case of steep bottom slopes, a formula for horizontal diffusion in the sigma coordinate system was derived. A case study for the side discharge into a straight open-channel flow shows that numerical results are verified well by experimental data. Furthermore, the present model is also verified by the simulation of discharging wastewater from Fuling Phosphorus Factory effluent into the Three Gorges Reservoir and the agreement between the numerical simulation results and field observation data is satisfactory. The change of the mixing zone scope in the water surface versus the layers along the vertical dimension was also discussed in detail. The study shows that a more realistic calculation for pollutant discharge has been provided by the present model than by the depth-average model which predicts an unrealistically smaller mixing zone.
Energy Technology Data Exchange (ETDEWEB)
Castell, A.; Medrano, M.; Sole, C.; Cabeza, L.F. [GREA Innovacio concurrent, Universitat de Lleida, Pere de Cabrera s/n, 25001 Lleida (Spain)
2010-10-15
The efficiency of thermal energy storage and solar collector systems is improved if the water tank is stratified. There are many parameters to characterize stratification but no work compares their suitability. This paper identifies the most used dimensionless numbers to characterize stratification in water tanks and studies their suitability. Experiments with different flow rates were done and the dimensionless numbers were determined. Richardson is the best number to define stratification in a water tank, while Mix number presents some problems and a bad behaviour. The other numbers do not clearly characterize stratification but can be useful combined with Richardson. (author)
Advanced fluid modelling and PIC/MCC simulations of low-pressure ccrf discharges
Becker, Markus M; Sun, Anbang; Bonitz, Michael; Loffhagen, Detlef
2016-01-01
Comparative studies of capacitively coupled radio-frequency discharges in helium and argon at pressures between 10 and 80 Pa are presented applying two different fluid modelling approaches as well as two independently developed particle-in-cell/Monte Carlo collision (PIC/MCC) codes. The focus is on the analysis of the range of applicability of a recently proposed fluid model including an improved drift-diffusion approximation for the electron component as well as its comparison with fluid modelling results using the classical drift-diffusion approximation and benchmark results obtained by PIC/MCC simulations. Main features of this time- and space-dependent fluid model are given. It is found that the novel approach shows generally quite good agreement with the macroscopic properties derived by the kinetic simulations and is largely able to characterize qualitatively and quantitatively the discharge behaviour even at conditions when the classical fluid modelling approach fails. Furthermore, the excellent agreem...
Directory of Open Access Journals (Sweden)
ZIANE, M.
2007-11-01
Full Text Available The aim of this paper is to study the dynamic behaviour of a plant constituted by an electrical power system and a gas discharge lamp, this latter, increasingly used in street lighting, remains a nonlinear load element. Various approaches are used to represent it, one is the approximation of the discharge represented by a hot "channel", which verifies the assumption of local thermodynamic equilibrium [LTE] or the polynomial form of the conductance variation. A calculation procedure, based on "channel" approximation of the high pressure mercury (HPM gas-discharge lamp, is developed to determine the physical and electric magnitudes, which characterize the dynamic behavior of the couple "lamp-electrical power system". The evolution of the lamp properties when principal parameters of the discharge (pressure of mercury, voltage supply, frequency are varying were studied and analyzed. We show the concordance between simulation, calculations and measurements for electric, energetic or irradiative characteristics. The model reproduces well the evolution of properties of the supply when principal parameters of the discharge vary.
Radiating dipole model of interference induced in spacecraft circuitry by surface discharges
Metz, R. N.
1984-01-01
Spacecraft in geosynchronous orbit can be charged electrically to high voltages by interaction with the space plasma. Differential charging of spacecraft surfaces leads to arc and blowoff discharging. The discharges are thought to upset interior, computer-level circuitry. In addition to capacitive or electrostatic effects, significant inductive and less significant radiative effects of these discharges exist and can be modeled in a dipole approximation. Flight measurements suggest source frequencies of 5 to 50 MHz. Laboratory tests indicate source current strengths of several amperes. Electrical and magnetic fields at distances of many centimeters from such sources can be as large as tens of volts per meter and meter squared, respectively. Estimates of field attenuation by spacecraft walls and structures suggest that interior fields may be appreciable if electromagnetic shielding is much thinner than about 0.025 mm (1 mil). Pickup of such fields by wires and cables interconnecting circuit components could be a source of interference signals of several volts amplitude.
DEFF Research Database (Denmark)
Thomsen, Nanna Isbak; Troldborg, Mads; McKnight, Ursula S.
2012-01-01
) leave as is, (2) clean up, or (3) further investigation needed. However, mass discharge estimates are often very uncertain, which may hamper the management decisions. If option 1 is incorrectly chosen soil and water quality will decrease, threatening or destroying drinking water resources. The risk......Mass discharge estimates are increasingly being used in the management of contaminated sites. Such estimates have proven useful for supporting decisions related to the prioritization of contaminated sites in a groundwater catchment. Potential management options can be categorised as follows: (1...... the appropriate management option. The uncertainty of mass discharge estimates depends greatly on the extent of the site characterization. A good approach for uncertainty estimation will be flexible with respect to the investigation level, and account for both parameter and conceptual model uncertainty. We...
Modeling inflation rates and exchange rates in Ghana: application of multivariate GARCH models.
Nortey, Ezekiel Nn; Ngoh, Delali D; Doku-Amponsah, Kwabena; Ofori-Boateng, Kenneth
2015-01-01
This paper was aimed at investigating the volatility and conditional relationship among inflation rates, exchange rates and interest rates as well as to construct a model using multivariate GARCH DCC and BEKK models using Ghana data from January 1990 to December 2013. The study revealed that the cumulative depreciation of the cedi to the US dollar from 1990 to 2013 is 7,010.2% and the yearly weighted depreciation of the cedi to the US dollar for the period is 20.4%. There was evidence that, the fact that inflation rate was stable, does not mean that exchange rates and interest rates are expected to be stable. Rather, when the cedi performs well on the forex, inflation rates and interest rates react positively and become stable in the long run. The BEKK model is robust to modelling and forecasting volatility of inflation rates, exchange rates and interest rates. The DCC model is robust to model the conditional and unconditional correlation among inflation rates, exchange rates and interest rates. The BEKK model, which forecasted high exchange rate volatility for the year 2014, is very robust for modelling the exchange rates in Ghana. The mean equation of the DCC model is also robust to forecast inflation rates in Ghana.
Transfer Rate Models for Gnutella Signaling Traffic
2006-01-01
This paper reports on transfer rate models for the Gnutella signaling protocol. New results on message-level and IP-level rates are presented. The models are based on traffic captured at the Blekinge Institute of Technology (BTH) campus in Sweden and offer several levels of granularity: message type, application layer and network layer. The aim is to obtain parsimonous models suitable for analysis and simulation of P2P workload. IEEE Explorer
Simulating river discharge in a snowy region of Japan using output from a regional climate model
Ma, X.; Kawase, H.; Adachi, S.; Fujita, M.; Takahashi, H. G.; Hara, M.; Ishizaki, N.; Yoshikane, T.; Hatsushika, H.; Wakazuki, Y.; Kimura, F.
2013-07-01
Snowfall amounts have fallen sharply along the eastern coast of the Sea of Japan since the mid-1980s. Toyama Prefecture, located approximately in the center of the Japan Sea region, includes high mountains of the northern Japanese Alps on three of its sides. The scarcity of meteorological observation points in mountainous areas limits the accuracy of hydrological analysis. With the development of computing technology, a dynamical downscaling method is widely applied into hydrological analysis. In this study, we numerically modeled river discharge using runoff data derived by a regional climate model (4.5-km spatial resolution) as input data to river networks (30-arcseconds resolution) for the Toyama Prefecture. The five main rivers in Toyama (the Oyabe, Sho, Jinzu, Joganji, and Kurobe rivers) were selected in this study. The river basins range in area from 368 to 2720 km2. A numerical experiment using climate comparable to that at present was conducted for the 1980s and 1990s. The results showed that seasonal river discharge could be represented and that discharge was generally overestimated compared with measurements, except for Oyabe River discharge, which was always underestimated. The average correlation coefficient for 10-year average monthly mean discharge was 0.8, with correlation coefficients ranging from 0.56 to 0.88 for all five rivers, whereas the Nash-Sutcliffe efficiency coefficient indicated that the simulation accuracy was insufficient. From the water budget analysis, it was possible to speculate that the lack of accuracy of river discharge may be caused by insufficient accuracy of precipitation simulation.
Energy Technology Data Exchange (ETDEWEB)
Carman, R.J. [Center for Lasers and Applications, Macquarie University, Sydney, (Australia) NSW 2109
1996-06-01
A rate-equation analysis has been used to investigate the feasibility of exciting new UV laser transitions in Cu II (3{ital d}{sup 9}4{ital p}{minus}3{ital d}{sup 9}4{ital s}) by use of a pulsed Cu{emdash}Ne discharge. The model predicts average output powers in excess of 100 mW at 10 kHz from the combined output at 201.5 and 211.2 nm. {copyright} {ital 1996 Optical Society of America.}
Impacts of combining reanalyses and weather station data on the accuracy of discharge modelling
Essou, Gilles R. C.; Brissette, François; Lucas-Picher, Philippe
2017-02-01
Reanalyses are important sources of meteorological data. Recent studies have shown that precipitation and temperature data from reanalysis present a strong potential for hydrological modelling, especially in regions with a sparse observational network. The objective of this study is to evaluate the impacts of the combination of three global atmospheric reanalyses - ERA-Interim, CFSR and MERRA - and one gridded observation dataset on the accuracy of hydrological model discharge simulations. Two combination approaches were used. The first one combined reanalyses and the observational database using a weighted average of the precipitation and temperature inputs. The second one consisted in using all meteorological inputs separately and combining the simulated hydrographs. The combinations were performed over 460 Canadian watersheds (representing regions with a low density of weather stations) and 370 US watersheds (representing regions with a higher density of weather stations). Results showed significant improvements in the simulated discharges for 68% and 92% of the Canadian watersheds for the input combinations and output combinations, respectively. Moreover, both approaches led to significant improvements in the simulated discharges for 72% of the US watersheds studied. For all watersheds where simulated discharges using observational data had a Nash Sutcliffe efficiency (NSE) lower than 0.5, the combination with reanalyses resulted in a median NSE increase of 0.3. This indicates that reanalysis can successfully compensate for deficiencies in the surface observation record and provide significantly better hydrological modelling performance.
Modelling of the negative discharge in long air gaps under impulse voltages
Energy Technology Data Exchange (ETDEWEB)
Rakotonandrasana, J H; Beroual, A [Ecole Centrale de Lyon, Laboratoire AMPERE UMR CNRS 5005, 69134 Ecully Cedex (France); Fofana, I [Universite of Quebec at Chicoutimi, 555, Boulevard de l' Universite, G7H 2B1, Chicoutimi, QC (Canada)
2008-05-21
This paper presents a self-consistent model enabling the description of the whole negative discharge sequence, initiated in long air gaps under impulse voltage waves. This sequence includes the different phases of the propagation such as the initiation of the first corona, the pilot leader, the electrode and space leaders, and their junction. The model consists of using a RLC equivalent electrical network, the parameters of which vary with time according to the discharge characteristics and geometry (R, L and C being, respectively, the resistance, the inductance and the capacitance). This model provides the spatial and temporal evolution of the entire discharge, the current and the corresponding electrical charge, the power and energy injected into the gap and the velocity. It also allows us to simulate an image converter working in streak or frame mode and the leader propagation velocities as well as the trajectory of the discharge obtained from a probabilistic distribution. The computed results are compared with experimental data. Good agreement between computed and experimental results was obtained for various test configurations.
Overnight Index Rate: Model, calibration and simulation
Olga Yashkir; Yuri Yashkir
2014-01-01
In this study, the extended Overnight Index Rate (OIR) model is presented. The fitting function for the probability distribution of the OIR daily returns is based on three different Gaussian distributions which provide modelling of the narrow central peak and the wide fat-tailed component. The calibration algorithm for the model is developed and investigated using the historical OIR data.
Overnight Index Rate: Model, calibration and simulation
Directory of Open Access Journals (Sweden)
Olga Yashkir
2014-12-01
Full Text Available In this study, the extended Overnight Index Rate (OIR model is presented. The fitting function for the probability distribution of the OIR daily returns is based on three different Gaussian distributions which provide modelling of the narrow central peak and the wide fat-tailed component. The calibration algorithm for the model is developed and investigated using the historical OIR data.
Overnight Index Rate: Model, Calibration, and Simulation
Olga Yashkir; Yuri Yashkir
2013-01-01
In this study, the extended Overnight Index Rate (OIR) model is presented. The fitting function for the probability distribution of the OIR daily returns is based on three different Gaussian distributions which provide modelling of the narrow central peak and the wide fat-tailed component. The calibration algorithm for the model is developed and investigated using the historical OIR data.
Schneider, Jens; Holzer, Frank; Rabe, Carsten; Häupl, Tilmann; Kopinke, Frank-Dieter; Roland, Ulf
2013-04-01
Applying a new experimental design with a capillary glass reactor and plate electrodes outside of the reactor allowed the initiation of discharges in aqueous electrolytes under the influence of a radio-frequency (RF) electromagnetic field. This study focused on the mechanism leading to the initiation of such discharges in the restriction of a glass tube. The light emission correlated with discharges was analysed with optical emission spectroscopy. Electrons with energies between 20 and 45 eV were responsible for the dissociation of water molecules into (excited) OH, H and O radicals. Current-voltage characteristics were measured before and under discharge conditions. Modelling of the experimental setup and simulation of electrical field strength distribution support the hypothesis of the origin of discharges in general and experimental findings such as ring-shaped discharges and a minimum solution conductivity of about 1 S m-1 required for discharge initiation with RF voltages of 2 kV.
Yoshitake, Yasuhide; Shinohara, Minoru
2013-11-01
Common drive to a motor unit (MU) pool manifests as low-frequency oscillations in MU discharge rate, producing fluctuations in muscle force. The aim of the study was to examine the temporal correlation between instantaneous MU discharge rate and rectified EMG in low frequencies. Additionally, we attempted to examine whether there is a temporal correlation between the low-frequency oscillations in MU discharge rate and the first derivative of force (dF/dt). Healthy young subjects produced steady submaximal force with their right finger as a single task or while maintaining a pinch-grip force with the left hand as a dual task. Surface EMG and fine-wire MU potentials were recorded from the first dorsal interosseous muscle in the right hand. Surface EMG was band-pass filtered (5-1,000 Hz) and full-wave rectified. Rectified surface EMG and the instantaneous discharge rate of MUs were smoothed by a Hann-window of 400 ms duration (equivalent to 2 Hz low-pass filtering). In each of the identified MUs, the smoothed MU discharge rate was positively correlated with the rectified-and-smoothed EMG as confirmed by the distinct peak in cross-correlation function with greater values in the dual task compared with the single task. Additionally, the smoothed MU discharge rate was temporally correlated with dF/dt more than with force and with rectified-and-smoothed EMG. The results indicated that the low-frequency component of rectified surface EMG and the first derivative of force provide temporal information on the low-frequency oscillations in the MU discharge rate.
Aerated bunker discharge of fine dilating powders
Ouwerkerk, C.E.D.; Molenaar, H.J.; Frank, M.J.W.
1992-01-01
The discharge rate of coarse powders (mean particle size 500 ¿m) from bunkers without aeration can be described by both empirical relations and theoretical models. In the case of small particles the discharge rate is largely overestimated. As the powder dilates during flow a negative pressure gradie
Value of river discharge data for global-scale hydrological modeling
Directory of Open Access Journals (Sweden)
M. Hunger
2007-11-01
Full Text Available This paper investigates the value of observed river discharge data for global-scale hydrological modeling of a number of flow characteristics that are required for assessing water resources, flood risk and habitat alteration of aqueous ecosystems. An improved version of WGHM (WaterGAP Global Hydrology Model was tuned in a way that simulated and observed long-term average river discharges at each station become equal, using either the 724-station dataset (V1 against which former model versions were tuned or a new dataset (V2 of 1235 stations and often longer time series. WGHM is tuned by adjusting one model parameter (γ that affects runoff generation from land areas, and, where necessary, by applying one or two correction factors, which correct the total runoff in a sub-basin (areal correction factor or the discharge at the station (station correction factor. The study results are as follows. (1 Comparing V2 to V1, the global land area covered by tuning basins increases by 5%, while the area where the model can be tuned by only adjusting γ increases by 8% (546 vs. 384 stations. However, the area where a station correction factor (and not only an areal correction factor has to be applied more than doubles (389 vs. 93 basins, which is a strong drawback as use of a station correction factor makes discharge discontinuous at the gauge and inconsistent with runoff in the basin. (2 The value of additional discharge information for representing the spatial distribution of long-term average discharge (and thus renewable water resources with WGHM is high, particularly for river basins outside of the V1 tuning area and for basins where the average sub-basin area has decreased by at least 50% in V2 as compared to V1. For these basins, simulated long-term average discharge would differ from the observed one by a factor of, on average, 1.8 and 1.3, respectively, if the additional discharge information were not used for tuning. The value tends to be higher in
Carman, R. J.; Mildren, R. P.
2003-01-01
A detailed rate-equation analysis has been used to simulate the plasma kinetics in a pulsed-excited dielectric barrier discharge in xenon, under operating conditions where the discharge structure is spatially homogeneous. The one-dimensional model, incorporating 14 species and 70 reaction processes, predicts results that are in good agreement with experimental measurements of the electrical characteristics, and optical (vaccum-ultraviolet (VUV) and visible) pulse shapes. The model reveals that electrical breakdown of the discharge gap occurs via a fast-moving ionization/excitation wavefront that starts close to the anode dielectric and propagates towards the cathode at ~3×105 m s-1. The wavefront appears as a result of successive avalanches of electrons that propagate across the discharge gap after release from the cathode dielectric. During breakdown, the mean electron energy in the bulk plasma is close to optimum for preferential excitation of the Xeast 1s4,5 states that feed the VUV emitting Xe2ast excimer states. Calculations suggest that the overall conversion efficiency from electrical energy to VUV output in the plasma is greater than 60%, with >99% of the light output emitted in the VUV. Parasitic processes that act to reduce the key Xeast 1s4,5 and Xe2ast populations are found to be essentially negligible. For pulsed excitation, the longer-term spatio-temporal behaviour of the electron/ions during the afterglow or inter-pulse period is important, resulting in a remnant `pre-pulse' ion density of ~1015 m-3 close to the cathode dielectric. These ions bombard the cathode during the subsequent excitation period to release the secondary (seed) electrons required to achieve electrical breakdown.
Energy Technology Data Exchange (ETDEWEB)
Carman, R J; Mildren, R P [Department of Physics, Macquarie University, North Ryde, Sydney NSW (Australia)
2003-01-07
A detailed rate-equation analysis has been used to simulate the plasma kinetics in a pulsed-excited dielectric barrier discharge in xenon, under operating conditions where the discharge structure is spatially homogeneous. The one-dimensional model, incorporating 14 species and 70 reaction processes, predicts results that are in good agreement with experimental measurements of the electrical characteristics, and optical (vacuum-ultraviolet (VUV) and visible) pulse shapes. The model reveals that electrical breakdown of the discharge gap occurs via a fast-moving ionization/excitation wavefront that starts close to the anode dielectric and propagates towards the cathode at {approx} 3x10{sup 5} m s{sup -1}. The wavefront appears as a result of successive avalanches of electrons that propagate across the discharge gap after release from the cathode dielectric. During breakdown, the mean electron energy in the bulk plasma is close to optimum for preferential excitation of the Xe* 1s{sub 4,5} states that feed the VUV emitting Xe{sub 2}* excimer states. Calculations suggest that the overall conversion efficiency from electrical energy to VUV output in the plasma is greater than 60%, with >99% of the light output emitted in the VUV. Parasitic processes that act to reduce the key Xe* 1s{sub 4,5} and Xe{sub 2}* populations are found to be essentially negligible. For pulsed excitation, the longer-term spatio-temporal behaviour of the electron/ions during the afterglow or inter-pulse period is important, resulting in a remnant 'pre-pulse' ion density of {approx} 10{sup 15} m{sup -3} close to the cathode dielectric. These ions bombard the cathode during the subsequent excitation period to release the secondary (seed) electrons required to achieve electrical breakdown.
Adsorption Rate Models for Multicomponent Adsorption Systems
Institute of Scientific and Technical Information of China (English)
姚春才
2004-01-01
Three adsorption rate models are derived for multicomponent adsorption systems under either pore diffusion or surface diffusion control. The linear driving force (LDF) model is obtained by assuming a parabolic intraparticle concentration profile. Models I and Ⅱ are obtained from the parabolic concentration layer approximation. Examples are presented to demonstrate the usage and accuracy of these models. It is shown that Model I is suitable for batch adsorption calculations and Model Ⅱ provides a good approximation in fixed-bed adsorption processes while the LDF model should not be used in batch adsorption and may be considered acceptable in fixed-bed adsorption where the parameter Ti is relatively large.
An Equivalent Circuit Modeling of Discharge Current Injected in Contact with an ESD-gun
Fujiwara, Osamu; Tanaka, Hideyuki; Yamanaka, Yukio
The transient electromagnetic (EM) fields caused by an electrostatic discharge (ESD) have broadband frequency spectra, which cause serious failure to high-tech information equipment. From this perspective, an ESD testing for the EM immunity of the equipment is specified by the IEC 61000-4-2, in which the detailed waveform of the discharge current injected onto the IEC recommended Pellegrini target in contact with an ESD-gun is prescribed for calibration. However, the factors for determining the current waveform remain unclear, and thus the IEC prescribed current waveform is unlikely to be injected into actual equipment. In this study, based on the structure of an ESD-gun, an equivalent circuit modeling is proposed for analyzing the discharge current injected onto a 50-Ω SMA connector instead of the IEC target that has frequency-dependent transmission characteristics. Its validity is confirmed by comparing the calculated current waveform with the measured result. The proposed circuit modeling is also validated from measurement of the discharge current injected onto a transmission-line by the ESD-gun.
Directory of Open Access Journals (Sweden)
P.O Idogho
2015-07-01
Full Text Available Analysis of discharges, precipitation and temperature and some other meteorological-hydrological variables from 1996-2011 at the section of Owena River Basin. The evaluation, correlations, and the relationship between precipitation and discharge time series indicate a strong relationship. Minimum discharge values of 0.8 m 3 /s and 1.2 m 3 /s were observed in January and December and these values correspond to rainfall depth of 1.4 mm and 8.2 mm respectively. The average annual rainfall, river discharge were computed as 1,306.7 mm, 1,165 m 3 /s and mean temperature and evaporation of 31.1 oC and 4.6 mm. Evapotranspiration computation using pan evaporation model overestimated the evapotranspiration values by 0.5 mm and 0.21 mm over IHACRES and CROPWAT model for the total period of 15-year. Integration of the simulation outputs would be veritable in creating realistic-robust water management system for domestic and agricultural applications.
Keeys, Christopher; Kalejaiye, Bamidele; Skinner, Michelle; Eimen, Mandana; Neufer, Joann; Sidbury, Gisele; Buster, Norman; Vincent, Joan
2014-12-15
The development, implementation, and pilot testing of a discharge medication reconciliation service managed by pharmacists with offsite telepharmacy support are described. Hospitals' efforts to prepare legible, complete, and accurate medication lists to patients prior to discharge continue to be complicated by staffing and time constraints and suboptimal information technology. To address these challenges, the pharmacy department at a 324-bed community hospital initiated a quality-improvement project to optimize patients' discharge medication lists while addressing problems that often resulted in confusing, incomplete, or inaccurate lists. A subcommittee of the hospital's pharmacy and therapeutics committee led the development of a revised medication reconciliation process designed to streamline and improve the accuracy and utility of discharge medication documents, with subsequent implementation of a new service model encompassing both onsite and remote pharmacists. The new process and service were evaluated on selected patient care units in a 19-month pilot project requiring collaboration by physicians, nurses, case managers, pharmacists, and an outpatient prescription drug database vendor. During the pilot testing period, 6402 comprehensive reconciled discharge medication lists were prepared; 634 documented discrepancies or medication errors were detected. The majority of identified problems were in three categories: unreconciled medication orders (31%), order clarification (25%), and duplicate orders (12%). The most problematic medications were the opioids, cardiovascular agents, and anticoagulants. A pharmacist-managed medication reconciliation service including onsite pharmacists and telepharmacy support was successful in improving the final discharge lists and documentation received by patients. Copyright © 2014 by the American Society of Health-System Pharmacists, Inc. All rights reserved.
Plasma diagnostics and modeling of direct current microplasma discharges at atmospheric pressure
Wang, Qiang
High pressure (100s of torr) microplasma (length scale 100s of micrometer) non-equilibrium discharges have potential applications as chemical microreactors, sensors, microelectromechanical systems (MEMS), and excimer radiation sources. Experimental and theoretical studies of these microplasmas can provide critical information on fundamental discharge characteristics, and help extend the window of stable discharge operation. Spatially resolved measurements (resolution ˜ 6 mum) were taken across a 200 mum slot-type microdischarge in atmospheric pressure helium or argon. Small amounts of actinometer gases were added to the flow for optical emission spectroscopy measurements. Gas temperature profiles were determined from N2 emission rotational spectroscopy. Stark splitting of the hydrogen Balmer-beta (Hbeta ) line was used to investigate the electric field distribution in the cathode sheath region. Electron densities were evaluated from the analysis of the spectral line broadenings of Hbeta emission. The measured gas temperature was in the range of 350--650 K in He, and 600--1200 K in Ar, both peaking near the cathode and increasing with power. The electron density in the bulk plasma was in the range (3-7)x1013 cm -3 in He, and (1-4)x1014 cm-3 in Ar. The measured electric field in He peaked at the cathode and decayed to small values over a distance of ˜50 mum (sheath edge) from the cathode. The experimental data were also used to validate a self-consistent one-dimensional plasma model. By a combination of measurements and simulation it was found that the dominant gas heating mechanism in DC microplasmas was ion Joule heating. Simulation results also predicted the existence of electric field reversals in the negative glow under operating conditions that favor a high electron diffusion flux emanating from the cathode sheath. The electric field adjusted to satisfy continuity of the total current. Also, the electric field in the anode layer was self adjusted to be
Modeling and Performance of Contact-Free Discharge Systems for Space Inertial Sensors
Ziegler, Tobias; Hechenblaikner, Gerald; Brandt, Nico; Fichter, Walter
2012-01-01
This article presents a detailed overview and assessment of contact-free UV light discharge systems (UVDS) needed to control the variable electric charge level of free-flying test masses which are part of high precision inertial sensors in space. A comprehensive numerical analysis approach on the basis of experimental data is detailed. This includes UV light ray tracing, the computation of time variant electric fields inside the complex inertial sensor geometry, and the simulation of individual photo-electron trajectories. Subsequent data analysis allows to determine key parameters to set up an analytical discharge model. Such a model is an essential system engineering tool needed for requirement breakdown and subsystem specification, performance budgeting, on-board charge control software development, and instrument modeling within spacecraft end-to-end performance simulators. Different types of UVDS design concepts are presented and assessed regarding their robustness and performance. Critical hardware aspe...
Experimental investigation and numerical modelling of positive corona discharge: ozone generation
Yanallah, K; Pontiga, F; Fernández-Rueda, A; Castellanos, A
2009-03-01
The spatial distribution of the species generated in a wire-cylinder positive corona discharge in pure oxygen has been computed using a plasma chemistry model that includes the most significant reactions between electrons, ions, atoms and molecules. The plasma chemistry model is included in the continuity equations of each species, which are coupled with Poisson's equation for the electric field and the energy conservation equation for the gas temperature. The current-voltage characteristic measured in the experiments has been used as an input data to the numerical simulation. The numerical model is able to reproduce the basic structure of the positive corona discharge and highlights the importance of Joule heating on ozone generation. The average ozone density has been computed as a function of current intensity and compared with the experimental measurements of ozone concentration determined by UV absorption spectroscopy.
Experimental investigation and numerical modelling of positive corona discharge: ozone generation
Energy Technology Data Exchange (ETDEWEB)
Yanallah, K; Castellanos, A [Departamento de Electronica y Electromagnetismo, Universidad de Sevilla (Spain); Pontiga, F; Fernandez-Rueda, A [Departamento de FIsica Aplicada II, Universidad de Sevilla (Spain)
2009-03-21
The spatial distribution of the species generated in a wire-cylinder positive corona discharge in pure oxygen has been computed using a plasma chemistry model that includes the most significant reactions between electrons, ions, atoms and molecules. The plasma chemistry model is included in the continuity equations of each species, which are coupled with Poisson's equation for the electric field and the energy conservation equation for the gas temperature. The current-voltage characteristic measured in the experiments has been used as an input data to the numerical simulation. The numerical model is able to reproduce the basic structure of the positive corona discharge and highlights the importance of Joule heating on ozone generation. The average ozone density has been computed as a function of current intensity and compared with the experimental measurements of ozone concentration determined by UV absorption spectroscopy.
Modelling of local ion nitriding in a glow discharge with hollow cathode
Budilov, V.; Ramazanov, K.; Khusainov, Yu
2017-05-01
The paper presents the results of computer calculations of glow discharge plasma parameters in a hollow cathode zone and modeling of thermal and diffusion processes at local ion nitriding with a hollow cathode. The proposed model of a glow discharge with a hollow cathode with sufficient accuracy allowed to describe the distribution of plasma parameters in a cathode void. Values of plasma parameters in a cathode void formed by a mesh screen and cathode surface were obtained via the probe method. It was found that the use of hollow cathode effect allows to increase the concentration of ions near the treated surface by 1.5 times. The suggested computer model allows to predict the distribution of the temperature field and depth of a diffusion layer at local ion nitriding with a hollow cathode for various configurations and sizes.
Term structure modeling and asymptotic long rate
Yao, Y.
1999-01-01
This paper examines the dynamics of the asymptotic long rate in three classes of term structure models. It shows that, in a frictionless and arbitrage-free market, the asymptotic long rate is a non-decreasing process. This gives an alternative proof of the same result of Dybvig et al. (Dybvig, P.H.,
Simulated discharge trends indicate robustness of hydrological models in a changing climate
Addor, Nans; Nikolova, Silviya; Seibert, Jan
2016-04-01
Assessing the robustness of hydrological models under contrasted climatic conditions should be part any hydrological model evaluation. Robust models are particularly important for climate impact studies, as models performing well under current conditions are not necessarily capable of correctly simulating hydrological perturbations caused by climate change. A pressing issue is the usually assumed stationarity of parameter values over time. Modeling experiments using conceptual hydrological models revealed that assuming transposability of parameters values in changing climatic conditions can lead to significant biases in discharge simulations. This raises the question whether parameter values should to be modified over time to reflect changes in hydrological processes induced by climate change. Such a question denotes a focus on the contribution of internal processes (i.e., catchment processes) to discharge generation. Here we adopt a different perspective and explore the contribution of external forcing (i.e., changes in precipitation and temperature) to changes in discharge. We argue that in a robust hydrological model, discharge variability should be induced by changes in the boundary conditions, and not by changes in parameter values. In this study, we explore how well the conceptual hydrological model HBV captures transient changes in hydrological signatures over the period 1970-2009. Our analysis focuses on research catchments in Switzerland undisturbed by human activities. The precipitation and temperature forcing are extracted from recently released 2km gridded data sets. We use a genetic algorithm to calibrate HBV for the whole 40-year period and for the eight successive 5-year periods to assess eventual trends in parameter values. Model calibration is run multiple times to account for parameter uncertainty. We find that in alpine catchments showing a significant increase of winter discharge, this trend can be captured reasonably well with constant
Methods of modelling relative growth rate
Institute of Scientific and Technical Information of China (English)
Arne Pommerening; Anders Muszta
2015-01-01
Background:Analysing and modelling plant growth is an important interdisciplinary field of plant science. The use of relative growth rates, involving the analysis of plant growth relative to plant size, has more or less independently emerged in different research groups and at different times and has provided powerful tools for assessing the growth performance and growth efficiency of plants and plant populations. In this paper, we explore how these isolated methods can be combined to form a consistent methodology for modelling relative growth rates. Methods:We review and combine existing methods of analysing and modelling relative growth rates and apply a combination of methods to Sitka spruce (Picea sitchensis (Bong.) Carr.) stem-analysis data from North Wales (UK) and British Douglas fir (Pseudotsuga menziesi (Mirb.) Franco) yield table data. Results:The results indicate that, by combining the approaches of different plant-growth analysis laboratories and using them simultaneously, we can advance and standardise the concept of relative plant growth. Particularly the growth multiplier plays an important role in modelling relative growth rates. Another useful technique has been the recent introduction of size-standardised relative growth rates. Conclusions:Modelling relative growth rates mainly serves two purposes, 1) an improved analysis of growth performance and efficiency and 2) the prediction of future or past growth rates. This makes the concept of relative growth ideally suited to growth reconstruction as required in dendrochronology, climate change and forest decline research and for interdisciplinary research projects beyond the realm of plant science.
Methods of modelling relative growth rate
Directory of Open Access Journals (Sweden)
Arne Pommerening
2015-03-01
Full Text Available Background Analysing and modelling plant growth is an important interdisciplinary field of plant science. The use of relative growth rates, involving the analysis of plant growth relative to plant size, has more or less independently emerged in different research groups and at different times and has provided powerful tools for assessing the growth performance and growth efficiency of plants and plant populations. In this paper, we explore how these isolated methods can be combined to form a consistent methodology for modelling relative growth rates. Methods We review and combine existing methods of analysing and modelling relative growth rates and apply a combination of methods to Sitka spruce (Picea sitchensis (Bong. Carr. stem-analysis data from North Wales (UK and British Douglas fir (Pseudotsuga menziesii (Mirb. Franco yield table data. Results The results indicate that, by combining the approaches of different plant-growth analysis laboratories and using them simultaneously, we can advance and standardise the concept of relative plant growth. Particularly the growth multiplier plays an important role in modelling relative growth rates. Another useful technique has been the recent introduction of size-standardised relative growth rates. Conclusions Modelling relative growth rates mainly serves two purposes, 1 an improved analysis of growth performance and efficiency and 2 the prediction of future or past growth rates. This makes the concept of relative growth ideally suited to growth reconstruction as required in dendrochronology, climate change and forest decline research and for interdisciplinary research projects beyond the realm of plant science.
Modeling oxygen depletion forced by acetate discharge in the coastal waters of the North Sea
Ilinskaya, Alisa; Yakushev, Evgeny; Nøst, Ole-Anders; Pakhomova, Svetlana
2017-04-01
Consequences of discharge of acetate produced during the production of X-ray contrast agents in the coastal waters of the Norwegian coast of the North Sea were analyzed with a set of mathematical models. The baseline seasonal variability of temperature, salinity, advection and turbulence were calculated with the Finite Volume Community Ocean Model (FVCOM) applied to the Southern coast of Norway. These data were used to force a vertical 2-Dimensional Benthic-Pelagic transport model (2DBP) coupled via Framework for Aquatic Biogeochemical Models (FABM) with a biogeochemical model OxyDep, considering phytoplankton, heterotrophs, nutrient, dissolved organic matter, particulate organic matter, and dissolved oxygen (DO). Acetate was considered as a chemical oxygen depletion substrate leading to the decrease of oxygen concentrations. We simulated seasonal variability at a 10 km long vertical transect with a spatial resolution of 50 m horizontally and approximately 2 m vertically. These calculations reproduced local minimum in the vertical DO distributions in 2 km distance from the discharge point, that corresponded to the observations. We conducted numerical experiments on the effects of doubling of the acetate discharge and on formation of acetate complexes.
Oscillations of low-current electrical discharges between parallel-plane electrodes. III. Models
Phelps, A. V.; Petrović, Z. Lj.; Jelenković, B. M.
1993-04-01
Simple models are developed to describe the results of measurements of the oscillatory and negative differential resistance properties of low- to moderate-current discharges in parallel-plane geometry. The time-dependent model assumes that the ion transit time is fixed and is short compared to the times of interest, that electrons are produced at the cathode only by ions, and that space-charge distortion of the electric field is small but not negligible. Illustrative numerical solutions are given for large voltage and current changes and analytic solutions for the time dependence of current and voltage are obtained in the small-signal limit. The small-signal results include the frequency and damping constants for decaying oscillations following a voltage change or following the injection of photoelectrons. The conditions for underdamped, overdamped, and self-sustained or growing oscillations are obtained. A previously developed steady-state, nonequilibrium model for low-pressure hydrogen discharges that includes the effects of space-charge distortion of the electric field on the yield of electrons at the cathode is used to obtain the negative differential resistance. Analytic expressions for the differential resistance and capacitance are developed using the steady-state, local-equilibrium model for electron and ion motion and a first-order perturbation treatment of space-charge electric fields. These models generally show good agreement with data from dc and pulsed discharge experiments presented in the accompanying papers.
Integrated modeling of temperature profiles in L-mode tokamak discharges
Rafiq, T.; Kritz, A. H.; Tangri, V.; Pankin, A. Y.; Voitsekhovitch, I.; Budny, R. V.
2014-12-01
Simulations of doublet III-D, the joint European tokamak, and the tokamak fusion test reactor L-mode tokamak plasmas are carried out using the PTRANSP predictive integrated modeling code. The simulation and experimental temperature profiles are compared. The time evolved temperature profiles are computed utilizing the Multi-Mode anomalous transport model version 7.1 (MMM7.1) which includes transport associated with drift-resistive-inertial ballooning modes (the DRIBM model [T. Rafiq et al., Phys. Plasmas 17, 082511 (2010)]). The tokamak discharges considered involved a broad range of conditions including scans over gyroradius, ITER like current ramp-up, with and without neon impurity injection, collisionality, and low and high plasma current. The comparison of simulation and experimental temperature profiles for the discharges considered is shown for the radial range from the magnetic axis to the last closed flux surface. The regions where various modes in the Multi-Mode model contribute to transport are illustrated. In the simulations carried out using the MMM7.1 model it is found that: The drift-resistive-inertial ballooning modes contribute to the anomalous transport primarily near the edge of the plasma; transport associated with the ion temperature gradient and trapped electron modes contribute in the core region but decrease in the region of the plasma boundary; and neoclassical ion thermal transport contributes mainly near the center of the discharge.
Integrated modeling of temperature profiles in L-mode tokamak discharges
Energy Technology Data Exchange (ETDEWEB)
Rafiq, T.; Kritz, A. H.; Tangri, V. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Pankin, A. Y. [Tech-X Corporation, Boulder, Colorado 80303 (United States); Voitsekhovitch, I. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Budny, R. V. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
2014-12-15
Simulations of doublet III-D, the joint European tokamak, and the tokamak fusion test reactor L-mode tokamak plasmas are carried out using the PTRANSP predictive integrated modeling code. The simulation and experimental temperature profiles are compared. The time evolved temperature profiles are computed utilizing the Multi-Mode anomalous transport model version 7.1 (MMM7.1) which includes transport associated with drift-resistive-inertial ballooning modes (the DRIBM model [T. Rafiq et al., Phys. Plasmas 17, 082511 (2010)]). The tokamak discharges considered involved a broad range of conditions including scans over gyroradius, ITER like current ramp-up, with and without neon impurity injection, collisionality, and low and high plasma current. The comparison of simulation and experimental temperature profiles for the discharges considered is shown for the radial range from the magnetic axis to the last closed flux surface. The regions where various modes in the Multi-Mode model contribute to transport are illustrated. In the simulations carried out using the MMM7.1 model it is found that: The drift-resistive-inertial ballooning modes contribute to the anomalous transport primarily near the edge of the plasma; transport associated with the ion temperature gradient and trapped electron modes contribute in the core region but decrease in the region of the plasma boundary; and neoclassical ion thermal transport contributes mainly near the center of the discharge.
Modeling anthropogenic boron in groundwater flow and discharge at Volusia Blue Spring (Florida, USA)
Reed, Erin M.; Wang, Dingbao; Duranceau, Steven J.
2016-08-01
Volusia Blue Spring (VBS) is the largest spring along the St. Johns River in Florida (USA) and the spring pool is refuge for hundreds of manatees during winter months. However, the water quality of the spring flow has been degraded due to urbanization in the past few decades. A three-dimensional contaminant fate and transport model, utilizing MODFLOW-2000 and MT3DMS, was developed to simulate boron transport in the Upper Florida Aquifer, which sustains the VBS spring discharge. The VBS model relied on information and data related to natural water features, rainfall, land use, water use, treated wastewater discharge, septic tank effluent flows, and fertilizers as inputs to simulate boron transport. The model was calibrated against field-observed water levels, spring discharge, and analysis of boron in water samples. The calibrated VBS model yielded a root-mean-square-error value of 1.8 m for the head and 17.7 μg/L for boron concentrations within the springshed. Model results show that anthropogenic boron from surrounding urbanized areas contributes to the boron found at Volusia Blue Spring.
Capacitive coupled RF discharge: modelling at the local statement of the problem
Badriev, I. B.; Chebakova, V. Yu; Zheltukhin, V. S.
2017-01-01
In this paper a mathematical model of capacitively coupled RF discharge at atmospheric pressure is constructed, a method of numerical realization of the model is developed, and the numerical calculations are carried out. Comparison of the results of the numerical experiments with the data of other authors, in particular, with the experimental data, is demonstrated as well a model adequacy as effectiveness of the numerical method. A results of calculations of the model problem at pressure of 760 Torr, frequency of generator of 13.76 MHz and interelectrode distance of 20mm, in local approximation are presented.
FUZZY MODEL FOR TWO-DIMENSIONAL RIVER WATER QUALITY SIMULATION UNDER SUDDEN POLLUTANTS DISCHARGED
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Based on the fuzziness and impreciseness of water environmental system, the fuzzy arithmetic was used to simulate the fuzzy and imprecise relations in modeling river water quality. By defining the parameters of water quality model as symmetrical triangular fuzzy numbers, a two-dimensional fuzzy water quality model for sudden pollutant discharge is established. From the fuzzy model, the pollutant concentrations, corresponding to the specified confidence level of α, can be obtained by means of the α-cut technique and arithmetic operations of triangular fuzzy numbers. Study results reveal that it is feasible in theory and reliable on calculation applying triangular fuzzy numbers to the simulation of river water quality.
Discharge and Nitrogen Transfer Modelling in the Berze River: A HYPE Setup and Calibration
Veinbergs, Arturs; Lagzdins, Ainis; Jansons, Viesturs; Abramenko, Kaspars; Sudars, Ritvars
2017-05-01
This study is focused on water quality and quantity modelling in the Berze River basin located in the Zemgale region of Latvia. The contributing basin area of 872 km2 is furthermore divided into 15 sub-basins designated according to the characteristics of hydrological network and water sampling programme. The river basin of interest is a spatially complex system with agricultural land and forests as two predominant land use types. Complexity of the system reflects in the discharge intensity and diffuse pollution of nitrogen compounds into the water bodies of the river basin. The presence of urban area has an impact as the load from the existing wastewater treatment plants consist up to 76 % of the total nitrogen load in the Berze River basin. Representative data sets of land cover, agricultural field data base for crop distribution analysis, estimation of crop management, soil type map, digital elevation model, drainage conditions, network of water bodies and point sources were used for the modelling procedures. The semi-distributed hydro chemical model HYPE has a setup to simulate discharge and nitrogen transfer. In order to make the model more robust and appropriate for the current study the data sets previously stated were classified by unifying similar spatially located polygons. The data layers were overlaid and 53 hydrological response units (SLCs) were created. Agricultural land consists of 48 SLCs with the details of soils, drainage conditions, crop types, and land management practices. Manual calibration procedure was applied to improve the performance of discharge simulation. Simulated discharge values showed good agreement with the observed values with the Nash-Sutcliffe efficiency of 0.82 and bias of -6.6 %. Manual calibration of parameters related to nitrogen leakage simulation was applied to test the most sensitive parameters.
Fluid model for a partially packed dielectric barrier discharge plasma reactor
Gadkari, Siddharth; Tu, Xin; Gu, Sai
2017-09-01
In this work, a two-dimensional numerical fluid model is developed for a partially packed dielectric barrier discharge (DBD) in pure helium. Influence of packing on the discharge characteristics is studied by comparing the results of DBD with partial packing with those obtained for DBD with no packing. In the axial partial packing configuration studied in this work, the electric field strength was shown to be enhanced at the top surface of the spherical packing material and at the contact points between the packing and the dielectric layer. For each value of applied potential, DBD with partial packing showed an increase in the number of pulses in the current profile in the positive half cycle of the applied voltage, as compared to DBD with no packing. Addition of partial packing to the plasma-alone DBD also led to an increase in the electron and ion number densities at the moment of breakdown. The time averaged electron energy profiles showed that a much higher range of electron energy can be achieved with the use of partial packing as compared to no packing in a DBD, at the same applied power. The spatially and time averaged values over one voltage cycle also showed an increase in power density and electron energy on inclusion of partial packing in the DBD. For the applied voltage parameters studied in this work, the discharge was found to be consistently homogeneous and showed the characteristics of atmospheric pressure glow discharge.
Two-dimensional modeling of a glow discharge source for mass spectrometry
Energy Technology Data Exchange (ETDEWEB)
Fiala, A.; Pitchford, L.C.; Boeuf, J.P. [Univ. Paul Sabatier, Toulouse (France); Baude, S. [CEA, Bruyeres-le-Chatel (France); Blaise, G. [Univ. Paris 11, Orsay (France). Lab. de Physique des Solides
1996-12-31
Glow discharge mass spectrometry (GDMS) is now widely used for elemental analysis of various materials. This diagnostic uses a low current discharge in a buffer gas to sputter atoms from a sample to be analyzed. A small density of atoms of the sample are thus introduced into the gas phase. These atoms are ionized in the discharge, and the ions are extracted through a small, rectangular slit leading to a mass spectrometer. Very low absolute detection limits are possible with GDMS`s, but many aspects of this diagnostic still require careful adjustments to achieve good performance. A better understanding especially of the influence of the discharge operating conditions (pressure, current, geometry,...) on the ion fluxes arriving at the plane of the exit slit is needed. The purpose of the work presented here is to develop such an understanding through a combined experimental and theoretical program, but the work reported here relates mainly to results from the model. The particular conditions the authors have chosen to study correspond to the commercially available VG9000 spectrometer and Megacell source.
Eylenceoglu, Ender; Rafatov, Ismail; Kudryavtsev, Anatoly
2016-09-01
A modification of the conventional hybrid Monte Carlo - fluid model for glow discharge, which incorporates the electron energy equation, is considered. In the proposed model electrons are separated into two groups, namely, high energetic fast and low energetic slow (bulk) electrons. Density profiles of ions, slow electrons, and meta-stable particles are determined from the solution of corresponding continuity equations. Fast electrons, which are responsible for ionization and excitation events in the discharge, are simulated by the Monte-Carlo method. The temperature profile for slow electrons is obtained from the solution of the energy balance equation. The transport (mobility and diffusion) coefficients as well as the reaction rates for slow electrons are determined as functions of the electron temperature. Test calculations are carried out for the direct current glow discharge in argon within two-dimensional geometry. Comparison of the computed results with those obtained from the conventional fluid and hybrid models and the experimental data is done, the applicability and reliability of the proposed model is studied in details.
An ETAS model with varying productivity rates
Harte, D. S.
2014-07-01
We present an epidemic type aftershock sequenc (ETAS) model where the offspring rates vary both spatially and temporally. This is achieved by distinguishing between those space-time volumes where the interpoint space and time distances are small, and those where they are considerably larger. We also question the nature of the background component in the ETAS model. Is it simply a temporal boundary correction (t = 0) or does it represent an additional tectonic process not described by the aftershock component? The form of these stochastic models should not be considered to be fixed. As we accumulate larger and better earthquake catalogues, GPS data, strain rates, etc., we have the ability to ask more complex questions about the nature of the process. By fitting modified models consistent with such questions, we should gain a better insight into the earthquake process. Hence, we consider a sequence of incrementally modified ETAS type models rather than `the' ETAS model.
Takeuchi, E. S.; Meyer, S. M.; Holmes, C. F.
1990-06-01
Real-time discharge is one of the few reliable methods available for determining capacities of low-rate cells. The utilization of high energy density lithium batteries in low-rate implantable applications has increased the need for more time-efficient methods of predicting cell longevity since cells have been shown to last in excess of eight years. The relationship between heat dissipation and self-discharge of low-rate lithium/BCX (bromine chloride in thionyl chloride) cells was studied and allows prediction of cell life prior to the availability of real-time data. The method was verified by real-time cell discharge data and provided estimates of delivered capacity within 6 percent of the actual values.
Multi-temperature state-dependent equivalent circuit discharge model for lithium-sulfur batteries
DEFF Research Database (Denmark)
Propp, Karsten; Marinescu, Monica; Auger, Daniel J.;
2016-01-01
-linear state-of-charge dependent Li-S equivalent circuit network (ECN) model for a Li-S cell under discharge. Li-S batteries are fundamentally different to Li-ion batteries, and require chemistry-specific models. A new Li-S model is obtained using a ‘behavioural’ interpretation of the ECN model; as Li......Lithium-sulfur (Li-S) batteries are described extensively in the literature, but existing computational models aimed at scientific understanding are too complex for use in applications such as battery management. Computationally simple models are vital for exploitation. This paper proposes a non...... pulse profile at four temperatures from 10 °C to 50 °C, giving linearized ECN parameters for a range of states-of-charge, currents and temperatures. These are used to create a nonlinear polynomial-based battery model suitable for use in a battery management system. When the model is used to predict...
Markosyan, A H; Ebert, U
2013-01-01
The high order fluid model developed in the preceding paper is employed here to study the propagation of negative planar streamer fronts in pure nitrogen. The model consists of the balance equations for electron density, average electron velocity, average electron energy and average electron energy flux. These balance equations have been obtained as velocity moments of Boltzmann's equation and are here coupled to the Poisson equation for the space charge electric field. Here the results of simulations with the high order model, with a PIC/MC (Particle in cell/Monte Carlo) model and with the first order fluid model based on the hydrodynamic drift-diffusion approximation are presented and compared. The comparison with the MC model clearly validates our high order fluid model, thus supporting its correct theoretical derivation and numerical implementation. The results of the first order fluid model with local field approximation, as usually used for streamer discharges, show considerable deviations. Furthermore,...
Temporal modelling of ballast water discharge and ship-mediated invasion risk to Australia
Cope, Robert C.; Prowse, Thomas A. A.; Ross, Joshua V.; Wittmann, Talia A.; Cassey, Phillip
2015-01-01
Biological invasions have the potential to cause extensive ecological and economic damage. Maritime trade facilitates biological invasions by transferring species in ballast water, and on ships' hulls. With volumes of maritime trade increasing globally, efforts to prevent these biological invasions are of significant importance. Both the International Maritime Organization and the Australian government have developed policy seeking to reduce the risk of these invasions. In this study, we constructed models for the transfer of ballast water into Australian waters, based on historic ballast survey data. We used these models to hindcast ballast water discharge over all vessels that arrived in Australian waters between 1999 and 2012. We used models for propagule survival to compare the risk of ballast-mediated propagule transport between ecoregions. We found that total annual ballast discharge volume into Australia more than doubled over the study period, with the vast majority of ballast water discharge and propagule pressure associated with bulk carrier traffic. As such, the ecoregions suffering the greatest risk are those associated with the export of mining commodities. As global marine trade continues to increase, effective monitoring and biosecurity policy will remain necessary to combat the risk of future marine invasion events. PMID:26064643
ECONOMETRIC MODELS FOR DETERMING THE EXCHANGE RATE
Directory of Open Access Journals (Sweden)
Mihaela BRATU
2012-05-01
Full Text Available The simple econometric models for the exchange rate, according to recent researches, generates the forecasts with the highest degree of accuracy. This type of models (Simultaneous Equations Model, MA(1 Procedure, Model with lagged variables is used to describe the evolution of the average exchange rate in Romanian in January 1991-March 2012 and to predict it on short run. The best forecasts, in terms of accuracy, on the forecasting horizon April-May 2012 were those based on a Simultaneous Equations Model that takes into account the Granger causality. An almost high degree of accuracy was gotten by combining the predictions based on MA(1 model with those based on the simultaneous equations model, when INV weighting scheme was applied (the forecasts are inversely weighted to their relative mean squared forecast error. The lagged variables Model provided the highest prediction errors. The importance of knowing the best exchange rate forecasts is related to the improvement of decision-making and the building of the monetary policy.
Hoseini, Yaser; Azari, Arash; Pilpayeh, Alireza
2016-10-01
It is of high importance to determine the flood discharge of different basins, in studies on water resources. However, it is necessary to use new models to determine flood hydrograph parameters. Therefore, it will be beneficial to conduct studies to calibrate the models, keeping in mind the local conditions of different regions. Therefore, this study was carried out to determine the peak flood discharge of a basin located in Southwest Iran, using the TR-20, TR55, and HEC-1 methods of the WMS model (watershed modeling system). The obtained results were compared with empirical values, as well as those of the soil conservation service (SCS) approach. Based on the results obtained, the TR55 method of the WMS model recorded the highest agreement with empirical values in Southwest Iran.
Dielectronic recombination rate in statistical model
Demura A.V.; Leontyev D.S.; Lisitsa V.S.; Shurigyn V.A.
2017-01-01
The dielectronic recombination rate of multielectron ions was calculated by means of the statistical approach. It is based on an idea of collective excitations of atomic electrons with the local plasma frequencies. These frequencies are expressed via the Thomas-Fermi model electron density distribution. The statistical approach provides fast computation of DR rates that are compared with the modern quantum mechanical calculations. The results are important for current studies of thermonuclear...
Dielectronic recombination rate in statistical model
Directory of Open Access Journals (Sweden)
Demura A.V.
2017-01-01
Full Text Available The dielectronic recombination rate of multielectron ions was calculated by means of the statistical approach. It is based on an idea of collective excitations of atomic electrons with the local plasma frequencies. These frequencies are expressed via the Thomas-Fermi model electron density distribution. The statistical approach provides fast computation of DR rates that are compared with the modern quantum mechanical calculations. The results are important for current studies of thermonuclear plasmas with the tungsten impurities.
Dielectronic recombination rate in statistical model
Demura, A. V.; Leontyev, D. S.; Lisitsa, V. S.; Shurigyn, V. A.
2016-12-01
The dielectronic recombination rate of multielectron ions was calculated by means of the statistical approach. It is based on an idea of collective excitations of atomic electrons with the local plasma frequencies. These frequencies are expressed via the Thomas-Fermi model electron density distribution. The statistical approach provides fast computation of DR rates that are compared with the modern quantum mechanical calculations. The results are important for current studies of thermonuclear plasmas with the tungsten impurities.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper,a new model with a total amount control target of allowable water withdrawal based on initial water right is built for the implementation of initial water right allocation scheme as well as unified allocation for allowable water withdrawal and sewage discharge.The model couples the water allocation simulation model and the computational model of permissible pol-lution bearing capacity.In view of the model complexity,a new technology which synthesizes system simulation,iterative reservoir turns and intelligent computation is proposed to improve the operability of allocation scheme and computational efficiency.Taking the Beijiang River Basin in the Pearl River Basin as an example,the study explains the model establishment,solution and application,and draws an optimized operation graph of large-scale reservoirs.The study also obtains a long-term operation strategy of river basin water resources system,the allocation schemes of allowable water withdrawal and sewage discharge in a typical year and the flow hydrographs of trans-boundary sections.The validity of the model and the allocation rationality are analyzed as well.
Modelling the impact of wind stress and river discharge on Danshuei River plume
Liu, W.-C.; Chen, W.-B.; Cheng, R.T.; Hsu, M.-H.
2008-01-01
A three-dimensional, time-dependent, baroclinic, hydrodynamic and salinity model, UnTRIM, was performed and applied to the Danshuei River estuarine system and adjacent coastal sea in northern Taiwan. The model forcing functions consist of tidal elevations along the open boundaries and freshwater inflows from the main stream and major tributaries in the Danshuei River estuarine system. The bottom friction coefficient was adjusted to achieve model calibration and verification in model simulations of barotropic and baroclinic flows. The turbulent diffusivities were ascertained through comparison of simulated salinity time series with observations. The model simulation results are in qualitative agreement with the available field data. The validated model was then used to investigate the influence of wind stress and freshwater discharge on Dasnhuei River plume. As the absence of wind stress, the anticyclonic circulation is prevailed along the north to west coast. The model results reveal when winds are downwelling-favorable, the surface low-salinity waters are flushed out and move to southwest coast. Conversely, large amounts of low-salinity water flushed out the Danshuei River mouth during upwelling-favorable winds, as the buoyancy-driven circulation is reversed. Wind stress and freshwater discharge are shown to control the plume structure. ?? 2007 Elsevier Inc. All rights reserved.
Zheng, Jiaxin; Hou, Yuyang; Duan, Yandong; Song, Xiaohe; Wei, Yi; Liu, Tongchao; Hu, Jiangtao; Guo, Hua; Zhuo, Zengqing; Liu, Lili; Chang, Zheng; Wang, Xiaowei; Zherebetskyy, Danylo; Fang, Yanyan; Lin, Yuan; Xu, Kang; Wang, Lin-Wang; Wu, Yuping; Pan, Feng
2015-09-09
LiFePO4 has long been held as one of the most promising battery cathode for its high energy storage capacity. Meanwhile, although extensive studies have been conducted on the interfacial chemistries in Li-ion batteries,1-3 little is known on the atomic level about the solid-liquid interface of LiFePO4/electrolyte. Here, we report battery cathode consisted with nanosized LiFePO4 particles in aqueous electrolyte with an high charging and discharging rate of 600 C (3600/600 = 6 s charge time, 1 C = 170 mAh g(-1)) reaching 72 mAh g(-1) energy storage (42% of the theoretical capacity). By contrast, the accessible capacity sharply decreases to 20 mAh g(-1) at 200 C in organic electrolyte. After a comprehensive electrochemistry tests and ab initio calculations of the LiFePO4-H2O and LiFePO4-EC (ethylene carbonate) systems, we identified the transient formation of a Janus hydrated interface in the LiFePO4-H2O system, where the truncated symmetry of solid LiFePO4 surface is compensated by the chemisorbed H2O molecules, forming a half-solid (LiFePO4) and half-liquid (H2O) amphiphilic coordination environment that eases the Li desolvation process near the surface, which makes a fast Li-ion transport across the solid/liquid interfaces possible.
Parametric Regression Models Using Reversed Hazard Rates
Directory of Open Access Journals (Sweden)
Asokan Mulayath Variyath
2014-01-01
Full Text Available Proportional hazard regression models are widely used in survival analysis to understand and exploit the relationship between survival time and covariates. For left censored survival times, reversed hazard rate functions are more appropriate. In this paper, we develop a parametric proportional hazard rates model using an inverted Weibull distribution. The estimation and construction of confidence intervals for the parameters are discussed. We assess the performance of the proposed procedure based on a large number of Monte Carlo simulations. We illustrate the proposed method using a real case example.
A fault tree model to assess probability of contaminant discharge from shipwrecks.
Landquist, H; Rosén, L; Lindhe, A; Norberg, T; Hassellöv, I-M; Lindgren, J F; Dahllöf, I
2014-11-15
Shipwrecks on the sea floor around the world may contain hazardous substances that can cause harm to the marine environment. Today there are no comprehensive methods for environmental risk assessment of shipwrecks, and thus there is poor support for decision-making on prioritization of mitigation measures. The purpose of this study was to develop a tool for quantitative risk estimation of potentially polluting shipwrecks, and in particular an estimation of the annual probability of hazardous substance discharge. The assessment of the probability of discharge is performed using fault tree analysis, facilitating quantification of the probability with respect to a set of identified hazardous events. This approach enables a structured assessment providing transparent uncertainty and sensitivity analyses. The model facilitates quantification of risk, quantification of the uncertainties in the risk calculation and identification of parameters to be investigated further in order to obtain a more reliable risk calculation.
Modelling cathode spots in glow discharges in the cathode boundary layer geometry
Almeida, P G C; Bieniek, M S
2015-01-01
Self-organized patterns of cathode spots in glow discharges are computed in the cathode boundary layer geometry, which is the one employed in most of the experiments reported in the literature. The model comprises conservation and transport equations of electrons and a single ion species, written in the drift-diffusion and local-field approximations, and Poisson's equation. Multiple solutions existing for the same value of the discharge current and describing modes with different configurations of cathode spots are computed by means of a stationary solver. The computed solutions are compared to their counterparts for plane-parallel electrodes, and experiments. All of the computed spot patterns have been observed in the experiment.
Institute of Scientific and Technical Information of China (English)
LIU Xiang-Mei; SONG Yuan-Hong; WANG You-Nian
2009-01-01
A self-consistent fluid model, which incorporates density and flux balances of electrons, ions, neutrals and nanopar ticles, electron energy balance, and Poiaaon 's equation, is employed to investigate the capacitively coupled silane discharge modulated by dual-frequency electric sources. In this discharge process, nanoparticles are formed by a successive chemical reactions of anion with silane. The density distributions of the precursors in the dust particle formation are put forward, and the charging, transport and growth of nanoparticles are simulated. In this work, we focus our main attention on the influences of the high-frequency and low-frequency voltage on nanoparticle densities, nanoparticle charge distributions in both the bulk plasma and sheath region.
Petermann, Eric; Stollberg, Reiner; Scholten, Jan; Knöller, Kay; Schubert, Michael
2016-04-01
Apart from river and surface water runoff subsurface discharge of groundwater plays a key role in coastal water and matter budgets. Two major forms of submarine groundwater discharge (SGD) can be distinguished: (i) pure freshwater discharge from continental aquifers that are connected to the coastal sea driven by a positive hydraulic gradient (fresh SGD) and (ii) re-circulation of seawater that has penetrated permeable coastal sediments (re-circulated SGD), e.g. driven by tidal pumping. The localization of SGD zones and the quantification of SGD fluxes is of high interest for coastal water management due to potential threats related to SGD, namely (i) the detrimental impact of discharging nutrient- or contaminant-laden groundwater on coastal seawater quality, an aspect that is of relevance along coastlines which are impacted by agriculture, industry or intense urbanization, and (ii) the loss of freshwater to the ocean, an issue that is of major relevance in all coastal areas with (seasonally) limited freshwater availability. In this work, we discuss estimates for the total (fresh + re-circulated) SGD fluxes derived from a mass balance of the radioactive noble gas radon (222-Rn) with estimates of fresh SGD fluxes derived by hydrogeological modelling. The precision of the mass balance results depends on the adequate determination of the mass balance source and sink terms. These terms are calculated based on field observations of environmental tracers (salinity, δ18O, 222-Rn, 223-Ra, 224-Ra, 226-Ra) in seawater and porewater, as well as on meteorological data. The numerical hydrogeological model estimates groundwater flow based on groundwater monitoring data, river flow data, groundwater recharge estimates, tidal dynamics, and density effects along the freshwater/seawater interface. We compare these two independent methodological approaches of SGD flux estimation, discuss results regarding their relevance for the regional water balance and reason the implications of
Impact modelling of water resources development and climate scenarios on Zambezi River discharge
Directory of Open Access Journals (Sweden)
Harald Kling
2014-07-01
New hydrological insights for the region: Comparisons between historical and future scenarios show that the biggest changes have already occurred. Construction of Kariba and CahoraBassa dams in the mid 1900s altered the seasonality and flow duration curves. Future irrigation development will cause decreases of a similar magnitude to those caused by current reservoir evaporation losses. The discharge is highly sensitive to small precipitation changes and the two climate models used give different signs for future precipitation change, suggestive of large uncertainty. The river basin model and database are available as anopen-online Decision Support System to facilitate impact assessments of additional climate or development scenarios.
Energy Technology Data Exchange (ETDEWEB)
Dux, R.; Kallenbach, A.; Bessenrodt-Weberpals, M.; Behringer, K.; Bosch, H.S.; Fuchs, J.C.; Gehre, O.; Mast, F.; Poschenrieder, W.; Murmann, H.; Salzmann, H.; Schweinzer, J.; Suttrop, W. [MPI fuer Plasmaphysik, EURATOM Association, Garching and Berlin (Germany); ASDEX Upgrade- and NI-Team
1996-02-01
The radiation and transport characteristics of ASDEX Upgrade discharges with a neon driven radiative mantle are modelled using a 1-D radial impurity transport code that has been coupled to a simple divertor model describing particle recycling and pumping. The code is well suited to describe the measured impurity line radiation, total, soft X-ray and bremsstrahlung radiation in regions of the plasma which are not dominated by two dimensional effects. The recycling and pumping behaviour of neon as well as the bulk transport of neon for radiative boundary scenarios are discussed. (orig.)
Yoon, J.; Shahvari, A.
2011-12-01
This characterization and modeling study of dispersive tidal plume of brine discharge from reverse osmosis (RO) desalination system is a part of the Environmental Assessment (EA) for a new reverse osmosis system in the Coral Bay, St. John, USVI (US Virgin Island). Main foci are on developing the tidal longitudinal (perpendicular to the shoreline) and lateral (parallel to the shoreline) dispersion coefficients and subsequently characterize dispersion and mixing characterization of the negatively buoyant brine discharge plume from the proposed reverse osmosis plant to evaluate the level of salinity variations in the nearshore mixing plume in regard to existing coral reef ecosystem. An in situ dye study was conducted by a marine biologist for this purpose to estimate brine discharge plume dispersion coefficients under oscillatory tidal transport and fate flux for current and proposed plant configuration. Additional tidal and surface runoff hydrologic data, bathymetric data and brine discharge characteristics in the vicinity of the brine discharge location are reflected in this study. With estimated dispersion coefficients, eighteen brine discharge scenarios were evaluated to model anticipated dispersive characteristics under varying operational conditions and ambient tidal current conditions for average measured salinity of 33.27 PSU in loco as well as a standard 35 PSU for typical nearshore water salinity variations. Modeling results indicated that the dispersive tidal plume of design brine discharge from reverse osmosis (RO) desalination system at a discharge of 150,000 gpd would raise salinity no higher than 0.0123 PSU in receiving nearshore estuarine water (Maximum concentration at the segment 3 = 33.2822 PSU at Δt = 12 hrs and 24 hrs in diurnal tidal cycle under when the brine discharge with Base+25% concentration, 81.25 PSU at brine discharge rate of 0.0066 m3/sec, and with a minimum direct overland flow efflux at 0.003 m3/sec - this is a "worst-case" operating
An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge
Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.
2016-12-01
A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.
Advanced fluid modeling and PIC/MCC simulations of low-pressure ccrf discharges
Becker, M. M.; Kählert, H.; Sun, A.; Bonitz, M.; Loffhagen, D.
2017-04-01
Comparative studies of capacitively coupled radio-frequency discharges in helium and argon at pressures between 10 and 80 Pa are presented applying two different fluid modeling approaches as well as two independently developed particle-in-cell/Monte Carlo collision (PIC/MCC) codes. The focus is on the analysis of the range of applicability of a recently proposed fluid model including an improved drift-diffusion approximation for the electron component as well as its comparison with fluid modeling results using the classical drift-diffusion approximation and benchmark results obtained by PIC/MCC simulations. Main features of this time- and space-dependent fluid model are given. It is found that the novel approach shows generally quite good agreement with the macroscopic properties derived by the kinetic simulations and is largely able to characterize qualitatively and quantitatively the discharge behavior even at conditions when the classical fluid modeling approach fails. Furthermore, the excellent agreement between the two PIC/MCC simulation codes using the velocity Verlet method for the integration of the equations of motion verifies their accuracy and applicability.
Validation of RF CCP Discharge Model against Experimental Data using PIC Method
Icenhour, Casey; Kummerer, Theresa; Green, David L.; Smithe, David; Shannon, Steven
2014-10-01
The particle-in-cell (PIC) simulation method is a well-known standard for the simulation of laboratory plasma discharges. Using parallel computation on the Titan supercomputer at Oak Ridge National Laboratory (ORNL), this research is concerned with validation of a radio-frequency (RF) capacitively-coupled plasma (CCP) discharge PIC model against previously obtained experimental data. The plasma sources under simulation are 10--100 mTorr argon plasmas with a 13 MHz source and 27 MHz source operating at 50--200 W in both pulse and constant power conditions. Plasma parameters of interest in the validation include peak electron density, electron temperature, and RF plasma sheath voltages and thicknesses. The plasma is modeled utilizing the VSim plasma simulation tool, developed by the Tech-X Corporation. The implementation used here is a two-dimensional electromagnetic model, with corresponding external circuit model of the experimental setup. The goal of this study is to develop models for more complex RF plasma systems utilizing highly parallel computing technologies and methodology. This work is carried out with the support of Oak Ridge National Laboratory and the Tech-X Corporation.
Ability in daily activities after early supported discharge models of stroke rehabilitation
Taule, Tina; Strand, Liv Inger; Assmus, Jörg; Skouen, Jan Sture
2015-01-01
Abstract More knowledge is needed about how different rehabilitation models in the municipality influence stroke survivors’ ability in activities of daily living (ADL). Objectives: To compare three models of outpatient rehabilitation; early supported discharge (ESD) in a day unit, ESD at home and traditional treatment in the municipality (control group), regarding change in ADL ability during the first three months after stroke. Methods: A group comparison study was designed within a randomized controlled trial. Included participants were tested with the Assessment of Motor and Process Skills (AMPS) at baseline and discharged directly home. Primary and secondary outcomes were the AMPS and the modified Rankin Scale (mRS). Results and conclusions: Included were 154 participants (57% men, median age 73 years), and 103 participants completed the study. There were no significant group differences in pre–post changed ADL ability measured by the AMPS. To find the best rehabilitation model to improve the quality of stroke survivors’ motor and process skills needs further research. Patients participating in the ESD rehabilitation models were, compared with traditional treatment, significantly associated with improved ADL ability measured by the mRS when controlling for confounding factors, indicating that patients with social needs and physical impairment after stroke may benefit from ESD rehabilitation models. PMID:26005768
Ability in daily activities after early supported discharge models of stroke rehabilitation.
Taule, Tina; Strand, Liv Inger; Assmus, Jörg; Skouen, Jan Sture
2015-01-01
More knowledge is needed about how different rehabilitation models in the municipality influence stroke survivors' ability in activities of daily living (ADL). To compare three models of outpatient rehabilitation; early supported discharge (ESD) in a day unit, ESD at home and traditional treatment in the municipality (control group), regarding change in ADL ability during the first three months after stroke. A group comparison study was designed within a randomized controlled trial. Included participants were tested with the Assessment of Motor and Process Skills (AMPS) at baseline and discharged directly home. Primary and secondary outcomes were the AMPS and the modified Rankin Scale (mRS). Included were 154 participants (57% men, median age 73 years), and 103 participants completed the study. There were no significant group differences in pre-post changed ADL ability measured by the AMPS. To find the best rehabilitation model to improve the quality of stroke survivors' motor and process skills needs further research. Patients participating in the ESD rehabilitation models were, compared with traditional treatment, significantly associated with improved ADL ability measured by the mRS when controlling for confounding factors, indicating that patients with social needs and physical impairment after stroke may benefit from ESD rehabilitation models.
Modeling the Dynamics of Micro- and Macroparticles in a Combined Gas-Discharge Installation
Astashinskii, V. V.; Bogach, M. I.; Burachevskii, A. V.
2016-05-01
We present a model of the dynamics of micro- and macroparticles in a combined gas-discharge installation that accounts for the processes of metal explosion (heating of a metal in its solid state, melting, heating of the liquid metal, intense evaporation, ionization in metal vapor), a magnetohydrodynamic description of plasma acceleration (on the basis of the mass, momentum, and energy conservation laws neglecting the plasma viscosity and thermal conductivity), and a description of the processes of energy transfer from a high-velocity stream to accelerated particles. It has been established that the process of melting terminates in 1.3 ns after the start of the discharge and that the evaporation terminates in 480 ns. The stage of cooling starts in 21 μs. The average density of the plasma upon completion of the evaporation process can be estimated to be 1.7·10-5 g/cm3, with the pressure being of the order of 1.5·104 Pa and the total time of discharge, of about 250 μs.
Directory of Open Access Journals (Sweden)
Guohua Fang
2016-09-01
Full Text Available To alleviate increasingly serious water pollution and shortages in developing countries, various kinds of policies have been implemented by local governments. It is vital to quantify and evaluate the performance and potential economic impacts of these policies. This study develops a Computable General Equilibrium (CGE model to simulate the regional economic and environmental effects of discharge fees. Firstly, water resources and water environment factors are separated from the input and output sources of the National Economic Production Department. Secondly, an extended Social Accounting Matrix (SAM of Jiangsu province is developed to simulate various scenarios. By changing values of the discharge fees (increased by 50%, 100% and 150%, three scenarios are simulated to examine their influence on the overall economy and each industry. The simulation results show that an increased fee will have a negative impact on Gross Domestic Product (GDP. However, waste water may be effectively controlled. Also, this study demonstrates that along with the economic costs, the increase of the discharge fee will lead to the upgrading of industrial structures from a situation of heavy pollution to one of light pollution which is beneficial to the sustainable development of the economy and the protection of the environment.
DEFF Research Database (Denmark)
Chang, C. T.; Thomsen, Kenneth
1985-01-01
Several assumptions made in a previous study of the correlation between the Hα-line emission rate and the ablation rate of a hydrogen pellet injected into a tokamak discharge showed that the emission layer of the ablatant as optically thin with respect to all levels of the principal quantum numbe...
DEFF Research Database (Denmark)
Jensen, Magnus Thorsten; Kaiser, Christoph; Sandsten, Karl Erik;
2013-01-01
Elevated heart rate (HR) is associated with mortality in a number of heart diseases. We examined the long-term prognostic significance of HR at discharge in a contemporary population of patients with stable angina (SAP), non-ST-segment elevation acute coronary syndromes (NSTE-ACS), and ST-segment...
Lazarou, C.; Belmonte, T.; Chiper, A. S.; Georghiou, G. E.
2016-10-01
A validated numerical model developed for the study of helium barrier discharges in the presence of dry air impurities is presented in this paper. The model was used to numerically investigate the influence of air traces on the evolution of the helium dielectric barrier discharge (DBD). The level of dry air used as impurity was in the range from 0 to 1500 ppm, which corresponds to the most commonly encountered range in atmospheric pressure discharge experiments. The results presented in this study clearly show that the plasma chemistry and consequently the discharge evolution is highly affected by the concentration level of impurities in the mixture. In particular, it was observed that air traces assist the discharge ignition at low concentration levels (~55 ppm), while on the other hand, they increase the burning voltage at higher concentration levels (~1000 ppm). Furthermore, it was found that the discharge symmetry during the voltage cycle highly depends on the concentration of air. For the interpretation of the results, a detailed analysis of the processes that occur in the discharge gap is performed and the main reaction pathways of ion production are described. Thanks to this approach, useful insight into the physics behind the evolution of the discharge is obtained.
Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...
Directory of Open Access Journals (Sweden)
Moon Soo Bak
2012-01-01
Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.
Directory of Open Access Journals (Sweden)
Szolgayová Elena
2014-03-01
Full Text Available Short term streamflow forecasting is important for operational control and risk management in hydrology. Despite a wide range of models available, the impact of long range dependence is often neglected when considering short term forecasting. In this paper, the forecasting performance of a new model combining a long range dependent autoregressive fractionally integrated moving average (ARFIMA model with a wavelet transform used as a method of deseasonalization is examined. It is analysed, whether applying wavelets in order to model the seasonal component in a hydrological time series, is an alternative to moving average deseasonalization in combination with an ARFIMA model. The one-to-ten-steps-ahead forecasting performance of this model is compared with two other models, an ARFIMA model with moving average deseasonalization, and a multiresolution wavelet based model. All models are applied to a time series of mean daily discharge exhibiting long range dependence. For one and two day forecasting horizons, the combined wavelet - ARFIMA approach shows a similar performance as the other models tested. However, for longer forecasting horizons, the wavelet deseasonalization - ARFIMA combination outperforms the other two models. The results show that the wavelets provide an attractive alternative to the moving average deseasonalization.
Development of electron thermal transport model in DIII-D discharges
Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.; Callen, J. D.
2008-11-01
The electron thermal transport in tokamak plasmas is investigated with predictive integrated modeling simulations using a choice of different electron thermal transport models. Two models for transport driven by Electron Temperature Gradient (ETG) modes are considered: (1) the ETG part of the GLF23 transport model; and (2) the Horton model for the the electromagnetic part of the ETG anomalous transport [1]. These models are combined with the paleoclassical model [2] for electron thermal transport. ASTRA predictive simulation results obtained using these models are compared with one another and compared with experimental data from DIII-D H-mode discharges in an effort to discriminate among the models. It is found that the electromagnetic limit of the Horton model is important near the magnetic axis where the ETG mode in the GLF23 model is below threshold. The paleoclassical model is found to be needed to produce the observed edge pedestal in the DIII-D simulations. [1] W. Horton, B. G. Hong, and W. M. Tang, Phys. Fluids 31, 2971 (1988). [2] J. D. Callen, Nucl. Fusion 45, 1120 (2005).
Energy Technology Data Exchange (ETDEWEB)
PAT GRANDELLI, P.E.; GREG ROCHELEAU; JOHN HAMRICK, Ph.D.; MATT CHURCH, Ph.D.; BRIAN POWELL, Ph.D.
2012-09-29
. Results: The model was run for a 100 MW OTEC Plant consisting of four separate ducts, discharging a total combined flow rate of 420 m3/s of warm water and 320 m3/s of cold water in a mixed discharge at 70 meters deep. Each duct was assumed to have a discharge port diameter of 10.5m producing a downward discharge velocity of about 2.18 m/s. The natural system, as measured in the HOTS program, has an average concentration of 10-15 mgC/m3. To calibrate the biological model, we first ran the model with no OTEC plant and varied biological parameters until the simulated data was a good match to the HOTS observations. This modeling showed that phytoplankton concentration were patchy and highly dynamic. The patchiness was a good match with the data variability observed within the HOTS data sets. We then ran the model with simulated OTEC intake and discharge flows and associated nutrients. Directly under the OTEC plant, the near-field plume has an average terminal depth of 172 meters, with a volumetric dilution of 13:1. The average terminal plume temperature was 19.8oC. Nitrate concentrations are 1 to 2 umol/kg above ambient. The advecting plume then further dilutes to less than 1 umol/kg above ambient within a few kilometers downstream, while remaining at depth. Because this terminal near-field plume is well below the 1% light limited depths (~120m), no immediate biological utilization of the nutrients occurs. As the nitrate is advected and dispersed downstream, a fraction of the deep ocean nutrients (< 0.5 umol/kg perturbation) mix upward where they are utilized by the ambient phytoplankton population. This occurs approximately twenty-five kilometers downstream from the plant at 110 - 70 meters depth. For pico-phytoplankton, modeling results indicate that this nutrient perturbation causes a phytoplankton perturbation of approximately 1 mgC/m3 (~10% of average ambient concentrations) that covers an area 10x5 km in size at the 70 to 90m depth. Thus, the perturbations are well
Stereotactic radiosurgery - discharge
Gamma knife - discharge; Cyberknife - discharge; Stereotactic radiotherapy - discharge; Fractionated stereotactic radiotherapy - discharge; Cyclotrons - discharge; Linear accelerator - discharge; Lineacs - ...
Multi-scale Model Coupling for CFD Simulations of Discharge Dispersion in the Sea
Robinson, D.; Wood, M.; Piggott, M. D.; Gorman, G.
2014-12-01
The processes that influence the dispersion of effluent discharges in the sea occur over a wide range of length and time scales. The distance that effluent can travel before it is considered mixed can be several kilometres, whereas the turbulent eddies that affect the near-field mixing of a discharge can be as small as a few centimetres. The range of scales that are involved mean that it is not generally practical to include all influencing physical phenomena within one model. Typically, the modelling of effluent dispersion is performed using two separate numerical models: a local model of the outlet(s), including the near-field effects of momentum, buoyancy and turbulence; and a larger scale model that can include the far-field effects of tidal-, wind- and wave-driven-currents, water depth variations, atmospheric fluxes, and Coriolis forces. The boundary between the two models is often not strictly defined, but is usually placed at the transition from where the behaviour of the effluent is dominated by the ambient environment, rather than the discharge characteristics and outfall configuration. In most real applications, this transition line varies considerably in time and space. This paper presents the findings of collaborative research between the Applied Modelling and Computation Group (AMCG) at Imperial College London, UK, and HR Wallingford Ltd. Results are presented using a range of coupling methods to link the near- and far-field mixing regions. An idealised domain and tidal conditions are used, with the outfall and ambient conditions typical of those found at small coastal desalination plants. Open-source CFD code Fluidity is used for both the near-field and far-field modelling. Fluidity scales well when run in parallel on large numbers of cores. It also has an anisotropic adaptive mesh capability which allows local control over solution accuracy throughout the domain. This combination means that accuracy can be achieved without excessive time costs, with
Energy Technology Data Exchange (ETDEWEB)
PAT GRANDELLI, P.E.; GREG ROCHELEAU; JOHN HAMRICK, Ph.D.; MATT CHURCH, Ph.D.; BRIAN POWELL, Ph.D.
2012-09-29
. Results: The model was run for a 100 MW OTEC Plant consisting of four separate ducts, discharging a total combined flow rate of 420 m3/s of warm water and 320 m3/s of cold water in a mixed discharge at 70 meters deep. Each duct was assumed to have a discharge port diameter of 10.5m producing a downward discharge velocity of about 2.18 m/s. The natural system, as measured in the HOTS program, has an average concentration of 10-15 mgC/m3. To calibrate the biological model, we first ran the model with no OTEC plant and varied biological parameters until the simulated data was a good match to the HOTS observations. This modeling showed that phytoplankton concentration were patchy and highly dynamic. The patchiness was a good match with the data variability observed within the HOTS data sets. We then ran the model with simulated OTEC intake and discharge flows and associated nutrients. Directly under the OTEC plant, the near-field plume has an average terminal depth of 172 meters, with a volumetric dilution of 13:1. The average terminal plume temperature was 19.8oC. Nitrate concentrations are 1 to 2 umol/kg above ambient. The advecting plume then further dilutes to less than 1 umol/kg above ambient within a few kilometers downstream, while remaining at depth. Because this terminal near-field plume is well below the 1% light limited depths (~120m), no immediate biological utilization of the nutrients occurs. As the nitrate is advected and dispersed downstream, a fraction of the deep ocean nutrients (< 0.5 umol/kg perturbation) mix upward where they are utilized by the ambient phytoplankton population. This occurs approximately twenty-five kilometers downstream from the plant at 110 - 70 meters depth. For pico-phytoplankton, modeling results indicate that this nutrient perturbation causes a phytoplankton perturbation of approximately 1 mgC/m3 (~10% of average ambient concentrations) that covers an area 10x5 km in size at the 70 to 90m depth. Thus, the perturbations are well
Energy Technology Data Exchange (ETDEWEB)
Morscheidt, W.; Hassouni, K. [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS-UPN, 93 - Villetaneuse (France); Amouroux, J.; Arefi-Khonsari, F. [Universite Pierre et Marie Curie, Lab. de Genie des Procedes Plasmas, 75 - Paris (France)
2001-07-01
A one-dimensional self consistent numerical model of argon-oxygen glow discharges obtained in parallel plate capacitively coupled devices has been presented. This model includes a discharge module that solves for the coupled set of charged species continuity equations, the electron energy transport equation and Poisson's equation. It also includes a neutral species transport-chemistry module that solves the stationary continuity equations of these species. The chemistry and electron energy losses through inelastic collisions were described by a 14 species-62 reactions thermochemical model. Results obtained from simulations performed for a feed gas composition of 66% Oxygen-34% Argon and several discharge pressures were discussed. These results mainly showed that for pressures below 200 mTorr the electron-impact ionization, dissociation and excitation processes mainly took place in the center of the discharge, while at higher pressures these processes took place at the discharge edges. The discharges obtained in the low pressure regime are electronegative, O{sup -} being the major negative ion, while at higher pressures the plasma was electro-positive. The axial profiles of the major charged species show a substantial non uniformity with pronounced maxima in the center of the discharge at low pressure. At high pressures, these profiles are more uniform in the ambipolar plasma region and sharply decrease at the sheath. (authors)
Forecasting Exchange Rates with Mixed Models
Directory of Open Access Journals (Sweden)
Laura Maria Badea
2013-06-01
Full Text Available Gaining accuracy in exchange rate forecasting applications provides true benefits for financial activities. Supported today by the advancements in computing power, machine learning techniques provide good alternatives to traditional time series estimation methods. Very approached in time series forecasting are Artificial Neural Networks (ANNs which offer robust results and allow a flexible data manipulation. When integrating both, the “white-box” feature of conventional methods and the complexity of machine learning techniques, forecasting models perform even better in terms of generated errors. In this study, input variables (independent variables are selected using an ARIMA technique and are further employed in differently configured multilayered feed-forward neural networks using Broyden-Fletcher-Goldfarb-Shanno (BFGS optimization algorithm to perform predictions on EUR/RON and CHF/RON exchange rates. Results in terms of mean squared error highlight good results when using mixed models.
Gaussian mixture model of heart rate variability.
Directory of Open Access Journals (Sweden)
Tommaso Costa
Full Text Available Heart rate variability (HRV is an important measure of sympathetic and parasympathetic functions of the autonomic nervous system and a key indicator of cardiovascular condition. This paper proposes a novel method to investigate HRV, namely by modelling it as a linear combination of Gaussians. Results show that three Gaussians are enough to describe the stationary statistics of heart variability and to provide a straightforward interpretation of the HRV power spectrum. Comparisons have been made also with synthetic data generated from different physiologically based models showing the plausibility of the Gaussian mixture parameters.
Smith, Brandon D.; Boyd, Iain D.; Kamhawi, Hani
2014-01-01
The sensitivity of xenon ionization rates to collision cross-sections is studied within the framework of a hybrid-PIC model of a Hall thruster discharge. A revised curve fit based on the Drawin form is proposed and is shown to better reproduce the measured crosssections at high electron energies, with differences in the integrated rate coefficients being on the order of 10% for electron temperatures between 20 eV and 30 eV. The revised fit is implemented into HPHall and the updated model is used to simulate NASA's HiVHAc EDU2 Hall thruster at discharge voltages of 300, 400, and 500 V. For all three operating points, the revised cross-sections result in an increase in the predicted thrust and anode efficiency, reducing the error relative to experimental performance measurements. Electron temperature and ionization reaction rates are shown to follow the trends expected based on the integrated rate coefficients. The effects of triply-charged xenon are also assessed. The predicted thruster performance is found to have little or no dependence on the presence of triply-charged ions. The fraction of ion current carried by triply-charged ions is found to be on the order of 1% and increases slightly with increasing discharge voltage. The reaction rates for the 0?III, I?III, and II?III ionization reactions are found to be of similar order of magnitude and are about one order of magnitude smaller than the rate of 0?II ionization in the discharge channel.
van Laer, Koen; Bogaerts, Annemie
2016-09-01
Packed bed dielectric barrier discharge (DBD) reactors have proven to be very useful sources of non-thermal plasma for a wide range of applications, of which the environmental applications have received most attention in recent years. Compared to an empty DBD reactor, a packing was introduced to either enhance the energy efficiency of the process, or, if the packing is catalytically active, steer the process towards a preferred end product. A wide range of geometries, bead sizes and bead materials have been tested experimentally in the past. However, since experimental diagnostics become more difficult with a packing present, a computational study is proposed to gain more insight. Using COMSOL's built in plasma module, a 2D axisymmetric fluid model is developed to study the influence of the gap size and the dielectric constant (ɛ) of the packing. Helium is used as discharge gas, at atmospheric pressure and room temperature. By decreasing the gas gap, the electric field strength is enhanced, resulting in a higher number of current peaks per half cycle of applied rf potential. Increasing ɛ also enhances the electric field strength. However, after a certain ɛ, its influence saturates. The electric field strength will no longer increase, leaving the discharge behavior unchanged.
Modeling the Volatility of Exchange Rates: GARCH Models
Directory of Open Access Journals (Sweden)
Fahima Charef
2017-03-01
Full Text Available The modeling of the dynamics of the exchange rate at a long time remains a financial and economic research center. In our research we tried to study the relationship between the evolution of exchange rates and macroeconomic fundamentals. Our empirical study is based on a series of exchange rates for the Tunisian dinar against three currencies of major trading partners (dollar, euro, yen and fundamentals (the terms of trade, the inflation rate, the interest rate differential, of monthly data, from jan 2000 to dec-2014, for the case of the Tunisia. We have adopted models of conditional heteroscedasticity (ARCH, GARCH, EGARCH, TGARCH. The results indicate that there is a partial relationship between the evolution of the Tunisian dinar exchange rates and macroeconomic variables.
Energy Technology Data Exchange (ETDEWEB)
Fendel, Peter [Thorlabs, 56 Sparta Avenue, Newton, New Jersey 07860 (United States); Ganguly, Biswa N.; Bletzinger, Peter [Air Force Research Laboratory, WPAFB, Ohio 45433 (United States)
2015-08-15
Axial and radial variations of electric field have been measured in dielectric shielded 0.025 m diameter parallel plate electrode with 0.0065 m gap for 1.6 mA, 2260 V helium dc discharge at 1.75 Torr. The axial and radial electric field profiles have been measured from the Stark splitting of 2{sup 1}S→11 {sup 1}P transition through collision induced fluorescence from 4{sup 3}D→2{sup 3}P. The electric field values showed a strong radial variation peaking to 500 kV/m near the cathode radial boundary, and decreasing to about 100 kV/m near the anode edge, suggesting the formation of an obstructed discharge for this low nd condition, where n is the gas density and d is the gap distance. The off-axis Stark spectra showed that the electric field vector deviates from normal to the cathode surface which permits longer path electron trajectories in the inter-electrode gap. Also, the on-axis electric field gradient was very small and off-axis electric field gradient was large indicating a radially non-uniform current density. In order to obtain information about the space charge distribution in this obstructed discharge, it was modeled using the 2-d axisymmetric Poisson solver with the COMSOL finite element modeling program. The best fit to the measured electric field distribution was obtained with a space charge variation of ρ(r) = ρ{sub 0}(r/r{sub 0}){sup 3}, where ρ(r) is the local space charge density, ρ{sub 0} = 6 × 10{sup −3} Coulomb/m{sup 3}, r is the local radial value, and r{sub 0} is the radius of the electrode.
Kohn, Irene; Vis, Marc; Freudiger, Daphné; Seibert, Jan; Weiler, Markus; Stahl, Kerstin
2016-04-01
The response of alpine streamflows to long-term climate variations is highly relevant for the supply of water to adjacent lowlands. A key challenge in modelling high-elevation catchments is the complexity and spatial variability of processes, whereas data availability is rather often poor, restricting options for model calibration and validation. Glaciers represent a long-term storage component that changes over long time-scales and thus introduces additional calibration parameters into the modelling challenge. The presented study aimed to model daily streamflow as well as the contributions of ice and snow melt for all 49 of the River Rhine's glaciated headwater catchments over the long time-period from 1901 to 2006. To constrain the models we used multiple data sources and developed an adapted modelling framework based on an extended version of the HBV model that also includes a time-variable glacier change model and a conceptual representation of snow redistribution. In this study constraints were applied in several ways. A water balance approach was applied to correct precipitation input in order to avoid calibration of precipitation; glacier area change from maps and satellite products and information on snow depth and snow covered area were used for the calibration of each catchment model; and finally, specific seasonal and dynamic aspects of discharge were used for calibration. Additional data like glacier mass balances were used to evaluate the model in selected catchments. The modelling experiment showed that the long-term development of the coupled glacier and streamflow change was particularly important to constrain the model through an objective function incorporating three benchmarks of glacier retreat during the 20th Century. Modelling using only streamflow as calibration criteria had resulted in disproportionate under and over estimation of glacier retreat, even though the simulated and observed streamflow agreed well. Also, even short discharge time
Modeling a short cold cathode DC discharge device with controllable plasma parameters
Kudryavtsev, Anatoly; Adams, Steven; Demidov, Vladimir; Bogdanov, Yevgeny
2009-11-01
A short (without positive column) DC gas-discharge device with a cold cathode has been modeled. The device consists of the plane disk-shaped cathode and anode while the inter-electrode gap is bounded by a cylindrical wall. The cathode and anode are each 2.5 cm in diameter, and the inter-electrode gap is 12 mm. The wall is made of conducting parts divided by an insulator. The modeling has been performed for argon plasma at 1 Torr pressure. It is demonstrated in the model that spatial distributions of electron density and temperature and argon metastable atom density depend on the DC voltage applied to different conducting parts of the wall. Applied voltage can trap within the device volume energetic electrons arising from atomic and molecular processes in the plasma. This leads to a modification in the heating of slow electrons by energetic electrons and as a result modifies the controlling plasma parameters.
Experimental modeling of high-voltage corona discharge using design of experiments
Institute of Scientific and Technical Information of China (English)
Rezzouga M; Tilmatine A; Gouri R; Medics K; Dascalescu L
2007-01-01
Many studies,both experimental and numerical,were devoted to the electric current of corona discharge and some mathematical models were proposed to express it.As it depends on several parameters,it is difficult to find a theoretical or an experimental formula,which considers all the factors.So we opted for the methodology of experimental designs,also called Tagushi's methodology,which represents a powerful tool generally employed when the process has many factors to consider.The objective of this paper is to model current using this experimental methodology.The factors considered were geometrical factors (interelectrode interval,surface of the grounded plane electrode,curvature radius of the point electrode),climatic factors (temperature and relative humidity),and applied high voltage.Results of experiments made it possible to obtain mathematical models and to analyse the interactions between all factors.
Wen, De-Qi; Liu, Wei; Gao, Fei; Lieberman, M. A.; Wang, You-Nian
2016-08-01
A hybrid model, i.e. a global model coupled bidirectionally with a parallel Monte-Carlo collision (MCC) sheath model, is developed to investigate an inductively coupled discharge with a bias source. This hybrid model can self-consistently reveal the interaction between the bulk plasma and the radio frequency (rf) bias sheath. More specifically, the plasma parameters affecting characteristics of rf bias sheath (sheath length and self-bias) are calculated by a global model and the effect of the rf bias sheath on the bulk plasma is determined by the voltage drop of the rf bias sheath. Moreover, specific numbers of ions are tracked in the rf bias sheath and ultimately the ion energy distribution function (IEDF) incident on the bias electrode is obtained. To validate this model, both bulk plasma density and IEDF on the bias electrode in an argon discharge are compared with experimental measurements, and a good agreement is obtained. The advantage of this model is that it can quickly calculate the bulk plasma density and IEDF on the bias electrode, which are of practical interest in industrial plasma processing, and the model could be easily extended to serve for industrial gases.
Surzhikov, S. T.
2017-08-01
The drift-diffusion model of a Penning discharge in molecular hydrogen under pressures of about 1 Torr with regard to the external electric circuit has been proposed. A two-dimensional axially symmetric discharge geometry with a cylindrical anode and flat cathodes perpendicular to the symmetry axis has been investigated. An external magnetic field of about 0.1 T is applied in the axial direction. Using the developed drift-diffusion model, the electrodynamic structure of a Penning discharge in the pressure range of 0.5-5 Torr at a current source voltage of 200-500 V is numerically simulated. The evolution of the discharge electrodynamic structure upon pressure variations in zero magnetic field (the classical glow discharge mode) and in the axial magnetic field (Penning discharge) has been studied using numerical experiments. The theoretical predictions of the existence of an averaged electron and ion motion in a Penning discharge both in the axial and radial directions and in the azimuthal direction have been confirmed by the calculations.
Modelling of rate effects at multiple scales
DEFF Research Database (Denmark)
Pedersen, R.R.; Simone, A.; Sluys, L. J.
2008-01-01
At the macro- and meso-scales a rate dependent constitutive model is used in which visco-elasticity is coupled to visco-plasticity and damage. A viscous length scale effect is introduced to control the size of the fracture process zone. By comparison of the widths of the fracture process zone......, the length scale in the meso-model and the macro-model can be coupled. In this fashion, a bridging of length scales can be established. A computational analysis of a Split Hopkinson bar test at medium and high impact load is carried out at macro-scale and meso-scale including information from the micro-scale....
Multi-temperature state-dependent equivalent circuit discharge model for lithium-sulfur batteries
Propp, Karsten; Marinescu, Monica; Auger, Daniel J.; O'Neill, Laura; Fotouhi, Abbas; Somasundaram, Karthik; Offer, Gregory J.; Minton, Geraint; Longo, Stefano; Wild, Mark; Knap, Vaclav
2016-10-01
Lithium-sulfur (Li-S) batteries are described extensively in the literature, but existing computational models aimed at scientific understanding are too complex for use in applications such as battery management. Computationally simple models are vital for exploitation. This paper proposes a non-linear state-of-charge dependent Li-S equivalent circuit network (ECN) model for a Li-S cell under discharge. Li-S batteries are fundamentally different to Li-ion batteries, and require chemistry-specific models. A new Li-S model is obtained using a 'behavioural' interpretation of the ECN model; as Li-S exhibits a 'steep' open-circuit voltage (OCV) profile at high states-of-charge, identification methods are designed to take into account OCV changes during current pulses. The prediction-error minimization technique is used. The model is parameterized from laboratory experiments using a mixed-size current pulse profile at four temperatures from 10 °C to 50 °C, giving linearized ECN parameters for a range of states-of-charge, currents and temperatures. These are used to create a nonlinear polynomial-based battery model suitable for use in a battery management system. When the model is used to predict the behaviour of a validation data set representing an automotive NEDC driving cycle, the terminal voltage predictions are judged accurate with a root mean square error of 32 mV.
Over, Thomas M.; Soong, David T.; Holmes, Jr., Robert R.
2011-01-01
Boneyard Creek—which drains an urbanized watershed in the cities of Champaign and Urbana, Illinois, including part of the University of Illinois at Urbana-Champaign (UIUC) campus—has historically been prone to flooding. Using the Stormwater Management Model (SWMM), a hydrologic and hydraulic model of Boneyard Creek was developed for the design of the projects making up the first phase of a long-term plan for flood control on Boneyard Creek, and the construction of the projects was completed in May 2003. The U.S. Geological Survey, in cooperation with the Cities of Champaign and Urbana and UIUC, installed and operated stream and rain gages in order to obtain data for evaluation of the design-model simulations. In this study, design-model simulations were evaluated by using observed postconstruction precipitation and peak-discharge data. Between May 2003 and September 2008, five high-flow events on Boneyard Creek satisfied the study criterion. The five events were simulated with the design model by using observed precipitation. The simulations were run with two different values of the parameter controlling the soil moisture at the beginning of the storms and two different ways of spatially distributing the precipitation, making a total of four simulation scenarios. The simulated and observed peak discharges and stages were compared at gaged locations along the Creek. The discharge at one of these locations was deemed to be critical for evaluating the design model. The uncertainty of the measured peak discharge was also estimated at the critical location with a method based on linear regression of the stage and discharge relation, an estimate of the uncertainty of the acoustic Doppler velocity meter measurements, and the uncertainty of the stage measurements. For four of the five events, the simulated peak discharges lie within the 95-percent confidence interval of the observed peak discharges at the critical location; the fifth was just outside the upper end of
Over, Thomas M.; Soong, David T.; Holmes, Jr., Robert R.
2011-01-01
Boneyard Creek—which drains an urbanized watershed in the cities of Champaign and Urbana, Illinois, including part of the University of Illinois at Urbana-Champaign (UIUC) campus—has historically been prone to flooding. Using the Stormwater Management Model (SWMM), a hydrologic and hydraulic model of Boneyard Creek was developed for the design of the projects making up the first phase of a long-term plan for flood control on Boneyard Creek, and the construction of the projects was completed in May 2003. The U.S. Geological Survey, in cooperation with the Cities of Champaign and Urbana and UIUC, installed and operated stream and rain gages in order to obtain data for evaluation of the design-model simulations. In this study, design-model simulations were evaluated by using observed postconstruction precipitation and peak-discharge data. Between May 2003 and September 2008, five high-flow events on Boneyard Creek satisfied the study criterion. The five events were simulated with the design model by using observed precipitation. The simulations were run with two different values of the parameter controlling the soil moisture at the beginning of the storms and two different ways of spatially distributing the precipitation, making a total of four simulation scenarios. The simulated and observed peak discharges and stages were compared at gaged locations along the Creek. The discharge at one of these locations was deemed to be critical for evaluating the design model. The uncertainty of the measured peak discharge was also estimated at the critical location with a method based on linear regression of the stage and discharge relation, an estimate of the uncertainty of the acoustic Doppler velocity meter measurements, and the uncertainty of the stage measurements. For four of the five events, the simulated peak discharges lie within the 95-percent confidence interval of the observed peak discharges at the critical location; the fifth was just outside the upper end of
VR closure rates for two vocational models.
Fraser, Virginia V; Jones, Amanda M; Frounfelker, Rochelle; Harding, Brian; Hardin, Teresa; Bond, Gary R
2008-01-01
The Individual Placement and Support (IPS) model of supported employment is an evidence-based practice for individuals with psychiatric disabilities. To be financially viable, IPS programs require funding from the state-federal vocational rehabilitation (VR) system. However, some observers have questioned the compatibility of IPS and the VR system. Using a randomized controlled trial comparing IPS to a well-established vocational program called the Diversified Placement Approach (DPA), we examined rates of VR sponsorship and successful VR closures. We also describe the establishment of an active collaboration between a psychiatric rehabilitation agency and the state VR system to facilitate rapid VR sponsorship for IPS clients. Both IPS and DPA achieved a 44% rate of VR Status 26 closure when considering all clients entering the study. IPS and DPA averaged similar amount of time to achieve VR sponsorship. Time from vocational program entry to Status 26 was 51 days longer on average for IPS. Even though several IPS principles seem to run counter to VR practices, such as zero exclusion and rapid job search, we found IPS closure rates comparable to those for DPA, a vocational model that screens for readiness, provides prevocational preparation, and extensively uses agency-run businesses.
Operation and Thermal Modeling of the ISIS H– Source from 50 to 2 Hz Repetition Rates
Pereira, H; Lettry, J
2013-01-01
CERN’s Linac4 accelerator H− ion source, currently under construction, will operate at a 2 Hz repetition rate, with pulse length of 0.5 ms and a beam current of 80 mA. Its reliability must exceed 99 % with a mandatory 3 month uninterrupted operation period. A Penning ion source is successfully operated at ISIS; at 50 Hz repetition rate it reliably provides 55 mA H− pulses of 0.25 ms duration over 1 month. The discharge plasma ignition is very sensitive to the temperatures of the discharge region, especially of its cathode. The investigation by modeling and measurement of operation parameters suitable for arc ignition and H− production at 2 Hz is of paramount importance and must be understood prior to the implementation of discharge ion sources in the Linac4 accelerator. In its original configuration, the ISIS H− source delivers beam only if the repetition rate is above 12.5 Hz, this paper describes the implementation of a temperature control of the discharge region aiming at lower repetition rate op...
U.S. Geological Survey, Department of the Interior — This digital data set represents discharge areas in the Death Valley regional ground-water flow system (DVRFS) transient model. Natural ground-water discharge occurs...
U.S. Geological Survey, Department of the Interior — This digital data set represents discharge areas in the Death Valley regional ground-water flow system (DVRFS) transient model. Natural ground-water discharge...
Vašina, P; Hytková, T; Eliáš, M
2009-05-01
The majority of current models of the reactive magnetron sputtering assume a uniform shape of the discharge current density and the same temperature near the target and the substrate. However, in the real experimental set-up, the presence of the magnetic field causes high density plasma to form in front of the cathode in the shape of a toroid. Consequently, the discharge current density is laterally non-uniform. In addition to this, the heating of the background gas by sputtered particles, which is usually referred to as the gas rarefaction, plays an important role. This paper presents an extended model of the reactive magnetron sputtering that assumes the non-uniform discharge current density and which accommodates the gas rarefaction effect. It is devoted mainly to the study of the behaviour of the reactive sputtering rather that to the prediction of the coating properties. Outputs of this model are compared with those that assume uniform discharge current density and uniform temperature profile in the deposition chamber. Particular attention is paid to the modelling of the radial variation of the target composition near transitions from the metallic to the compound mode and vice versa. A study of the target utilization in the metallic and compound mode is performed for two different discharge current density profiles corresponding to typical two pole and multipole magnetics available on the market now. Different shapes of the discharge current density were tested. Finally, hysteresis curves are plotted for various temperature conditions in the reactor.
Institute of Scientific and Technical Information of China (English)
郭崇志; 刘佳
2014-01-01
Discharge capacity is the most important parameter to measure the safety valve performance ,so evaluating and measuring it accurately is extremely important .Standard test method of safety valve dis-charge capacity is too complicated and strict to promote .Different from lots of experimental studies on the discharge in most papers tested in a fixed opening height state which omitted the dynamic effects on tran -sient opening process will cause deviations .This paper has studied a new evaluating method of discharge in stable discharge stage by using the spool sensor tested data .Numerical simulations have found that the theoretical nozzle throat located on the curtain face and the relief fluid was in transonic flow stage when the valve was in stable discharge stage caused by overpressure .Further detection technology studies have shown that stable discharge could be determined and measured by the data of stable discharge stage col -lected by spool sensor , and could achieve the rated capacity assessment .This new detection method ex-plored the discharge testing technology ,revolutionized the traditional flow meter ideas ,extended the appli-cations of the spool sensor ,provided a simply approached testing method ,and the accuracy is sufficient .%排量是衡量安全阀性能的重要参数，因此其准确计算和评估极为重要。排量的标准测试方法要求严格，测试繁琐且难以实施。与多数文献略去开启过程动态效应在固定开高状态下进行排量研究不同，文中研究了一种利用阀芯传感器的测试数据来评估动态开启稳定排放阶段排量的计量方法。数值模拟发现，超压泄放过程的稳态排放阶段喷管的喉部位于帘面，并且发现，排放流体处于跨音速流态。进一步的检测技术研究表明，稳态排量可以通过阀芯传感器采集的稳态排放数据来确定和计量，进而可以实现额定排量评估。这种新的排量计量和测试技术改变
Directory of Open Access Journals (Sweden)
Taru Olsson
2017-10-01
New hydrological insights for the region: On average, GCMs indicate increased annual mean temperatures by 3.1 °C (RCP4.5 and by 4.3 °C (RCP8.5 and precipitation sum by 20% (RCP4.5 and by 28% (RCP8.5. With increasing total precipitation, river discharges are also found to increase, but the variability among the GCMs is considerable. The largest increases in monthly discharge are projected to occur in the wet season (November − April − with up to 31% increase of December multi-model mean. Despite the larger annual discharge for the mean multi-model result, discharges in the dry season may decrease according to some GCMs, showing the need for an adapted future water management.
Towards a model for protein production rates
Dong, J J; Zia, R K P
2007-01-01
In the process of translation, ribosomes read the genetic code on an mRNA and assemble the corresponding polypeptide chain. The ribosomes perform discrete directed motion which is well modeled by a totally asymmetric simple exclusion process (TASEP) with open boundaries. Using Monte Carlo simulations and a simple mean-field theory, we discuss the effect of one or two ``bottlenecks'' (i.e., slow codons) on the production rate of the final protein. Confirming and extending previous work by Chou and Lakatos, we find that the location and spacing of the slow codons can affect the production rate quite dramatically. In particular, we observe a novel ``edge'' effect, i.e., an interaction of a single slow codon with the system boundary. We focus in detail on ribosome density profiles and provide a simple explanation for the length scale which controls the range of these interactions.
Towards a Model for Protein Production Rates
Dong, J. J.; Schmittmann, B.; Zia, R. K. P.
2007-07-01
In the process of translation, ribosomes read the genetic code on an mRNA and assemble the corresponding polypeptide chain. The ribosomes perform discrete directed motion which is well modeled by a totally asymmetric simple exclusion process (TASEP) with open boundaries. Using Monte Carlo simulations and a simple mean-field theory, we discuss the effect of one or two "bottlenecks" (i.e., slow codons) on the production rate of the final protein. Confirming and extending previous work by Chou and Lakatos, we find that the location and spacing of the slow codons can affect the production rate quite dramatically. In particular, we observe a novel "edge" effect, i.e., an interaction of a single slow codon with the system boundary. We focus in detail on ribosome density profiles and provide a simple explanation for the length scale which controls the range of these interactions.
Ladeesh V. G.; Manu R
2017-01-01
Grinding aided electrochemical discharge machining is a hybrid technique, which combines the grinding action of an abrasive tool and thermal effects of electrochemical discharges to remove material from the workpiece for producing complex contours. The present study focuses on developing fluidic channels on borosilicate glass using G-ECDM and attempts to develop a mathematical model for surface roughness of the machined channel. Preliminary experiments are conducted to study the effect of mac...
Lee, Hyo-Chang; Chung, Chin-Wook
2015-10-20
Hysteresis, which is the history dependence of physical systems, is one of the most important topics in physics. Interestingly, bi-stability of plasma with a huge hysteresis loop has been observed in inductive plasma discharges. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics.
Development of Rainfall-Discharge Model for Future NPP candidate Site
Energy Technology Data Exchange (ETDEWEB)
An, Ji-hong; Yee, Eric [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)
2015-10-15
By this study, most suitable model for future nuclear power plant site in Yeongdeok to be used to predict peak amount of riverine flooding was developed by examining historical rainfall and discharge data from the nearest gage station which is Jodong water level gage station in Taehwa basin. Sitting a nuclear power plant (NPP) requires safety analyses that include the effects of extreme events such as flooding or earthquake. In light of South Korean government's 15-year power supply plan that calls for the construction of new nuclear power station in Yeongdeok, it becomes more important to site new station in a safe area from flooding. Because flooding or flooding related accidents mostly happen due to extremely intense rainfall, it is necessary to find out the relationship between rainfall and run-off by setting up feasible model to figure out the peak flow of the river around nuclear related facilities.
OEDGE modeling of DIII-D density scan discharges leading to detachment
Energy Technology Data Exchange (ETDEWEB)
Elder, J.D., E-mail: david@starfire.utias.utoronto.ca [University of Toronto Institute for Aerospace Studies, Toronto M3H 5T6 (Canada); Stangeby, P.C. [University of Toronto Institute for Aerospace Studies, Toronto M3H 5T6 (Canada); General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Bray, B.D. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); Brooks, N. [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550 (United States); Leonard, A.W. [General Atomics, PO Box 85608, San Diego, CA 92186-5608 (United States); McLean, A.G. [Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94550 (United States); Unterberg, E.A. [Oak Ridge National Laboratories, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Watkins, J.G. [Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 (United States)
2015-08-15
The OEDGE code is used to model the outer divertor plasma for discharges from a density scan experiment on DIII-D with the objective of assessing EIRENE and ADAS hydrogenic emission atomic physics data for D{sub α}, D{sub β} and D{sub γ} for values of T{sub e} and n{sub e} characteristic of the range of divertor plasma conditions from attached to weakly detached. Confidence in these values is essential to spectroscopic interpretation of any experiment or modeling effort. Good agreement between experiment and calculated emissions is found for both EIRENE and ADAS calculated emission profiles, confirming their reliability for plasma conditions down to ∼1 eV. For the cold dense plasma conditions characteristic of detachment, it is found that the calculated emissions are especially sensitive to T{sub e}.
Lei, Wang; Yanzhong, Li; Kang, Zhu; Yonghua, Jin
2015-01-01
In order to select an effective approach to predict the pressurization characteristics of cryogenic tank during rocket launching, three computational models, defined as 0-D, 1-D and CFD models, are used to obtain the pressure evolution and thermal performance of a cryogenic tank during pressurized discharge period. Several pressurization cases are computed by all of the three models to evaluate their predictive abilities and effects, respectively. The comparative study shows that for the case with a diffuser-type injector at the tank inlet, the consistent results by the three models are obtained in the most of period, except that 1-D model has a peak departure prediction of pressure value at the beginning of process. All of the three models can be used to predict the pressurization performance, and their predictive abilities could be validated with one another. The CFD model is the unique suitable model to display the pressurization performance including physical distribution in radial direction especially for the system with no-diffuser-type injector. Based on the analysis, the application selection of three models for different cases is accomplished. The 0-D model is the priority selection for a simple pressure prediction of tank ullage, even for the situation that severe temperature distribution exists in the ullage range. The 1-D model is the optimal selection as considering both the convenience and the time consumption for the constant-pressure cases. But it is not recommended in a constant-inlet flux cases for its distinct predicting deviation at the beginning of the process. When the detailed distributions within the tank are concerned, the CFD model is the unique selection. The results of this paper may be beneficial to the model selection and optimization analysis of a pressurization system.
Sutanudjaja, E.H.; Beek, L.P.H. van; Jong, S.M. de; Geer, F.C. van; Bierkens, M.F.P.
2014-01-01
We explore the possibility of using remotely sensed soil moisture data and in situ discharge observations to calibrate a large-extent hydrological model. The model used is PCR-GLOBWB-MOD, which is a physically based and fully coupled groundwater-land surface model operating at a daily basis and havi
Energy Technology Data Exchange (ETDEWEB)
Schrum, R.W.
1978-02-01
A generalized method of similitude is introduced and applied to develop scaling relationships for a General Electric Mark I suppression pool. A scale model is proposed to model suppression pool wall loads due to air flow through a T-quencher discharge device. The scaling relationships developed provide the means for relating scale model parameters (i.e., pressure, velocity,) to full scale.
van den Berg, Fabien; Schlunegger, Fritz; Norton, Kevin
2010-05-01
The 65 km2-large Entle catchment is located at the northern border of the Central Alps of Switzerland and is underlain by various lithologies including Flysch, carbonate sequences, Molasse deposits and glacial till. It has been subjected to headward knickpoint migration since the termination of the LGM (16 ± 3 ka), due to a base level fall upon glacial retreat. The incised portions of the catchment were delineated within a GIS environment in an effort to calculate volumetric differences between the glacial surface and the modern topography. The sediment budget estimates yield an average erosion rate of 1.93 ± 0.36 mm.yr-1 in the incised reaches, and a maximum local erosion rate of 11.47 ± 2.15 mm.yr-1. Assuming that there has been no erosion elsewhere, the basin-wide averaged erosion rate is estimated at 0.31 ± 0.06 mm.yr-1. This is consistent with 10Be-based denudation rates measured in adjacent catchments. Although constant erosion rates are generally assumed for studies involving 10Be analysis, field evidence indicate that headward knickzone migration through bedrock and unconsolidated glacial till has destabilized the surrounding hillslopes, resulting in supply of large volumes of sediment to the trunk channel by landsliding and/or debris flows downstream the knickzone. This additional influx of sediments may raise the local base level within the incised reach, thus perturbing the migration of the knickzone for a limited time interval. This time span critically depends on the relative importance between the probability density function (PDF) of the sediment particle size supplied by mass failure processes and debris flows, and the characteristic water discharge magnitude to remove that material. Measurements of the PDFs of the sediment particles along the incised Entle reach together with the application a simple long profile stream-power model for the entrainment and transport of sediment allow the identification of characteristic bed-forming discharge
Calculation of mass discharge of the Greenland ice sheet in the Earth System Model
Directory of Open Access Journals (Sweden)
O. O. Rybak
2016-01-01
Full Text Available Mass discharge calculation is a challenging task for the ice sheet modeling aimed at evaluation of their contribution to the global sea level rise during past interglacials, as well as one of the consequences of future climate change. In Greenland, ablation is the major source of fresh water runoff. It is approximately equal to the dynamical discharge (iceberg calving. Its share might have still larger during the past interglacials when the margins of the GrIS retreated inland. Refreezing of the melted water and its retention are two poorly known processes playing as a counterpart of melting and, thus, exerting influence on the run off. Interaction of ice sheets and climate is driven by energy and mass exchange processes and is complicated by numerous feed-backs. To study the complex of these processes, coupling of an ice sheet model and a climate model (i.e. models of the atmosphere and the ocean in one model is required, which is often called the Earth System Model (ESM. Formalization of processes of interaction between the ice sheets and climate within the ESM requires elaboration of special techniques to deal with dramatic differences in spatial and temporal variability scales within each of three ESM’s blocks. In this paper, we focus on the method of coupling of a Greenland ice sheet model (GrISM with the climate model INMCM having been developed in the Institute of Numerical Mathematics of Russian Academy of Sciences. Our coupling approach consists in applying of a special buffer model, which serves as an interface between GrISM and INMCM. A simple energy and water exchange model (EWBM-G allows realistic description of surface air temperature and precipitation fields adjusted to a relief of elevation of the GrIS surface. In a series of diagnostic numerical experiments with the present-day GrIS geometry and the modeled climate we studied sensitivity of the modeled surface mass balance and run off to the key EWBM-G parameters and compared
Models of decoherence with negative dephasing rate
Pernice, Ansgar; Strunz, Walter T
2012-01-01
We determine the total state dynamics of a dephasing open quantum system using the standard environment of harmonic oscillators. Of particular interest are random unitary approaches to the same reduced dynamics and system-environment correlations in the full model. Concentrating on a model with an at times negative dephasing rate, the issue of "non-Markovianity" will also be addressed with the emphasis on information obtained from the dynamics of the total state of system and environment: making use of criteria that allow us to distinguish between classically correlated and entangled total states, we employ a simple measure for the correlations emerging from the increase of the two local entropies, and relate it the nature of the correlations.
Modeling inflation rates and exchange rates in Ghana: application of multivariate GARCH models
Nortey, Ezekiel NN; Ngoh, Delali D; Doku-Amponsah, Kwabena; Ofori-Boateng, Kenneth
2015-01-01
This paper was aimed at investigating the volatility and conditional relationship among inflation rates, exchange rates and interest rates as well as to construct a model using multivariate GARCH DCC and BEKK models using Ghana data from January 1990 to December 2013. The study revealed that the cumulative depreciation of the cedi to the US dollar from 1990 to 2013 is 7,010.2% and the yearly weighted depreciation of the cedi to the US dollar for the period is 20.4%. There was evidence that, t...
Modeling inflation rates and exchange rates in Ghana: application of multivariate GARCH models
Nortey, Ezekiel NN; Ngoh, Delali D; Doku-Amponsah, Kwabena; Ofori-Boateng, Kenneth
2015-01-01
This paper was aimed at investigating the volatility and conditional relationship among inflation rates, exchange rates and interest rates as well as to construct a model using multivariate GARCH DCC and BEKK models using Ghana data from January 1990 to December 2013. The study revealed that the cumulative depreciation of the cedi to the US dollar from 1990 to 2013 is 7,010.2% and the yearly weighted depreciation of the cedi to the US dollar for the period is 20.4%. There was evidence that, t...
Directory of Open Access Journals (Sweden)
G.Sankara Narayanan
2014-03-01
Full Text Available Unconventional machining process finds lot of application in aerospace and precision industries. It is preferred over other conventional methods because of the advent of composite and high strength to weight ratio materials, complex parts and also because of its high accuracy and precision. Usually in unconventional machine tools, trial and error method is used to fix the values of process parameters which increase the production time and material wastage. A mathematical model functionally relating process parameters and operating parameters of a wire cut electric discharge machine (WEDM is developed incorporating Artificial neural network (ANN and the work piece material is SKD11 tool steel. This is accomplished by training a feed forward neural network with back propagation learning Levenberg-Marquardt algorithm. The required data used for training and testing the ANN are obtained by conducting trial runs in wire cut electric discharge machine in a small scale industry from South India. The programs for training and testing the neural network are developed, using matlab 7.0.1 package. In this work, we have considered the parameters such as thickness, time and wear as the input values and from that the values of the process parameters are related and a algorithm is arrived. Hence, the proposed algorithm reduces the time taken by trial runs to set the input process parameters of WEDM and thus reduces the production time along with reduction in material wastage. Thus the cost of machining processes is reduced and thereby increases the overall productivity.
A stochastic conflict resolution model for trading pollutant discharge permits in river systems.
Niksokhan, Mohammad Hossein; Kerachian, Reza; Amin, Pedram
2009-07-01
This paper presents an efficient methodology for developing pollutant discharge permit trading in river systems considering the conflict of interests of involving decision-makers and the stakeholders. In this methodology, a trade-off curve between objectives is developed using a powerful and recently developed multi-objective genetic algorithm technique known as the Nondominated Sorting Genetic Algorithm-II (NSGA-II). The best non-dominated solution on the trade-off curve is defined using the Young conflict resolution theory, which considers the utility functions of decision makers and stakeholders of the system. These utility functions are related to the total treatment cost and a fuzzy risk of violating the water quality standards. The fuzzy risk is evaluated using the Monte Carlo analysis. Finally, an optimization model provides the trading discharge permit policies. The practical utility of the proposed methodology in decision-making is illustrated through a realistic example of the Zarjub River in the northern part of Iran.
Institute of Scientific and Technical Information of China (English)
牛宗涛; 章程; 马云飞; 王瑞雪; 陈根永; 严萍; 邵涛
2015-01-01
Gliding discharges driven by microsecond-pulse power supply can generate non-thermal plasmas with high energy and high power density at atmospheric pressure. However, the flowing air significantly influences the characteristics of the microsecond-pulse gliding discharges in a repetitive mode. In this paper, in order to obtain the characteristics of the microsecond-pulse gliding discharges in a needle-to-needle gap, a microsecond-pulse power supply with an output voltage up to 30 kV, a pulse width ∼8 µs, and a pulse repetition frequencies 1–3000 Hz is used to investigate the electrical characteristics of gliding discharges by analyzing the voltage-current waveforms and obtaining the discharge images. Experimental results show that there are three typical discharge modes in the microsecond-pulse gliding discharges as the applied voltage increases, i.e. corona discharge, diffuse discharge, and gliding-like discharge. Both voltage-current waveforms and the discharge images at different discharge modes have significantly different behaviors. Corona discharge only exists near the positive electrode with a small radius of curvature. Diffuse discharges behave as the overlapped plasma channels bridge the entire gap. The channel of diffuse discharge is full of gap, which starts from the positive electrode, spreads in all directions, and ends at the negative electrode. Gliding-like discharge behaves as a continuous spark channeling, showing a continuous spark, which is discharging strongly and influenced by flow rates. Furthermore, both pulse repetition frequency (PRF) and flow rate remarkably affects the characteristics of microsecond-pulse gliding discharges. When the flow rate is small (2 L/min), the spark channels of gliding-like discharge gradually concentrate with the increase of the PRF. However, when the flow rate is larger (16 L/min), the spark channels of gliding-like discharge behave dispersively when the PRF increases. In our opinion, different
Simulating extreme low-discharge events for the Rhine using a stochastic model
Macian-Sorribes, Hector; Mens, Marjolein; Schasfoort, Femke; Diermanse, Ferdinand; Pulido-Velazquez, Manuel
2017-04-01
The specific features of hydrological droughts make them more difficult to be analysed than other water-related phenomena: longer time scales (months to several years) so less historical events are available, and the drought severity and associate damage depends on a combination of variables with no clear prevalence (e.g., total water deficit, maximum deficit and duration). As part of drought risk analysis, which aims to provide insight into the variability of hydrological conditions and associated socio-economic impacts, long synthetic time series should therefore be developed. In this contribution, we increase the length of the available inflow time series using stochastic autoregressive modelling. This enhancement could improve the characterization of the extreme range and can define extreme droughts with similar periods of return but different patterns that can lead to distinctly different damages. The methodology consists of: 1) fitting an autoregressive model (AR, ARMA…) to the available records; 2) generating extended time series (thousands of years); 3) performing a frequency analysis with different characteristic variables (total, deficit, maximum deficit and so on); and 4) selecting extreme drought events associated with different characteristic variables and return periods. The methodology was applied to the Rhine river discharge at location Lobith, where the Rhine enters The Netherlands. A monthly ARMA(1,1) autoregressive model with seasonally varying parameters was fitted and successfully validated to the historical records available since year 1901. The maximum monthly deficit with respect to a threshold value of 1800 m3/s and the average discharge for a given time span in m3/s were chosen as indicators to identify drought periods. A synthetic series of 10,000 years of discharges was generated using the validated ARMA model. Two time spans were considered in the analysis: the whole calendar year and the half-year period between April and September
Annonaceae substitution rates: a codon model perspective
Directory of Open Access Journals (Sweden)
Lars Willem Chatrou
2014-01-01
Full Text Available The Annonaceae includes cultivated species of economic interest and represents an important source of information for better understanding the evolution of tropical rainforests. In phylogenetic analyses of DNA sequence data that are used to address evolutionary questions, it is imperative to use appropriate statistical models. Annonaceae are cases in point: Two sister clades, the subfamilies Annonoideae and Malmeoideae, contain the majority of Annonaceae species diversity. The Annonoideae generally show a greater degree of sequence divergence compared to the Malmeoideae, resulting in stark differences in branch lengths in phylogenetic trees. Uncertainty in how to interpret and analyse these differences has led to inconsistent results when estimating the ages of clades in Annonaceae using molecular dating techniques. We ask whether these differences may be attributed to inappropriate modelling assumptions in the phylogenetic analyses. Specifically, we test for (clade-specific differences in rates of non-synonymous and synonymous substitutions. A high ratio of nonsynonymous to synonymous substitutions may lead to similarity of DNA sequences due to convergence instead of common ancestry, and as a result confound phylogenetic analyses. We use a dataset of three chloroplast genes (rbcL, matK, ndhF for 129 species representative of the family. We find that differences in branch lengths between major clades are not attributable to different rates of non-synonymous and synonymous substitutions. The differences in evolutionary rate between the major clades of Annonaceae pose a challenge for current molecular dating techniques that should be seen as a warning for the interpretation of such results in other organisms.
Ehrhardt, Manfred; Wattayakorn, Gullaya; Dawson, Rodger
1990-05-01
Detailed GC/MS based chemical analyses of organic concentrates from the Chao Phraya River obtained from a water sample collected in the Bangkok metropolitan area indicated that hydrocarbons of petroleum or combustion sources may be minor constituents of the dissolved lipophilic fraction relative to biogenic hydrocarbons and industrial chemicals. Using published data on river discharge and the concentrations measured in an integrated sample, tentative input rates into the Upper Gulf of Thailand for characterized chemicals are calculated.
Analysis of groundwater discharge with a lumped-parameter model, using a case study from Tajikistan
Pozdniakov, S. P.; Shestakov, V. M.
A lumped-parameter model of groundwater balance is proposed that permits an estimate of discharge variability in comparison with the variability of recharge, by taking into account the influence of aquifer parameters. Recharge-discharge relationships are analysed with the model for cases of deterministic and stochastic recharge time-series variations. The model is applied to study the temporal variability of groundwater discharge in a river valley in the territory of Tajikistan, an independent republic in Central Asia. Résumé Un modèle global de bilan d'eau souterraine a été développé pour estimer la variabilité de l'écoulement par rapport à celle de la recharge, en prenant en compte l'influence des paramètres de l'aquifère. Les relations entre recharge et écoulement sont analysées à l'aide du modèle pour des variations des chroniques de recharge soit déterministes, soit stochastiques. Le modèle est appliquéà l'étude de la variabilité temporelle de l'écoulement souterrain vers une rivière, dans le Tadjikistan, une république indépendante d'Asie centrale. Resumen Se propone un modelo de parámetros concentrados para realizar el balance de aguas subterráneas, el cual permite estimar la variabilidad en la descarga con respecto a la variabilidad en la recarga, en función de los parámetros que caracterizan el acuífero. Las relaciones entre recarga y descarga se analizan con el modelo para distintos casos de series temporales de recarga, tanto deterministas como estocásticas. El modelo se aplica al estudio de la variabilidad temporal de la descarga en un valle aluvial de Tadyikistán, una república independiente del Asia Central.
van Vliet, M. T. H.; van Beek, L. P. H.; Eisener, S.; Wada, Y.; Bierkens, M. F. P.
2016-01-01
Worldwide, 98% of total electricity is currently produced by thermoelectric power and hydropower. Climate change is expected to directly impact electricity supply, in terms of both water availability for hydropower generation and cooling water usage for thermoelectric power. Improved understanding of how climate change may impact the availability and temperature of water resources is therefore of major importance. Here we use a multi-model ensemble to show the potential impacts of climate change on global hydropower and cooling water discharge potential. For the first time, combined projections of streamflow and water temperature were produced with three global hydrological models (GHMs) to account for uncertainties in the structure and parametrization of these GHMs in both water availability and water temperature. The GHMs were forced with bias-corrected output of five general circulation models (GCMs) for both the lowest and highest representative concentration pathways (RCP2.6 and RCP8.5). The ensemble projections of streamflow and water temperature were then used to quantify impacts on gross hydropower potential and cooling water discharge capacity of rivers worldwide. We show that global gross hydropower potential is expected to increase between +2.4% (GCM-GHM ensemble mean for RCP 2.6) and +6.3% (RCP 8.5) for the 2080s compared to 1971-2000. The strongest increases in hydropower potential are expected for Central Africa, India, central Asia and the northern high-latitudes, with 18-33% of the world population living in these areas by the 2080s. Global mean cooling water discharge capacity is projected to decrease by 4.5-15% (2080s). The largest reductions are found for the United States, Europe, eastern Asia, and southern parts of South America, Africa and Australia, where strong water temperature increases are projected combined with reductions in mean annual streamflow. These regions are expected to affect 11-14% (for RCP2.6 and the shared socioeconomic
van Vliet, M. T. H.; van Beek, L. P. H.; Eisener, S.; Wada, Y.; Bierkens, M. F. P.
2016-01-01
Worldwide, 98% of total electricity is currently produced by thermoelectric power and hydropower. Climate change is expected to directly impact electricity supply, in terms of both water availability for hydropower generation and cooling water usage for thermoelectric power. Improved understanding of how climate change may impact the availability and temperature of water resources is therefore of major importance. Here we use a multi-model ensemble to show the potential impacts of climate change on global hydropower and cooling water discharge potential. For the first time, combined projections of streamflow and water temperature were produced with three global hydrological models (GHMs) to account for uncertainties in the structure and parametrization of these GHMs in both water availability and water temperature. The GHMs were forced with bias-corrected output of five general circulation models (GCMs) for both the lowest and highest representative concentration pathways (RCP2.6 and RCP8.5). The ensemble projections of streamflow and water temperature were then used to quantify impacts on gross hydropower potential and cooling water discharge capacity of rivers worldwide. We show that global gross hydropower potential is expected to increase between +2.4% (GCM-GHM ensemble mean for RCP 2.6) and +6.3% (RCP 8.5) for the 2080s compared to 1971-2000. The strongest increases in hydropower potential are expected for Central Africa, India, central Asia and the northern high-latitudes, with 18-33% of the world population living in these areas by the 2080s. Global mean cooling water discharge capacity is projected to decrease by 4.5-15% (2080s). The largest reductions are found for the United States, Europe, eastern Asia, and southern parts of South America, Africa and Australia, where strong water temperature increases are projected combined with reductions in mean annual streamflow. These regions are expected to affect 11-14% (for RCP2.6 and the shared socioeconomic
Directory of Open Access Journals (Sweden)
Somvir Singh Nain
2017-02-01
Full Text Available This paper presents the behavior of Udimet-L605 after wire electric discharge machining and evaluating the WEDM process using sophisticated machine learning approaches. The experimental work is depicted on the basis of Taguchi orthogonal L27 array, considering six input variables and three interactions. Three models such as support vector machine algorithms based on PUK kernel, non-linear regression and multi-linear regression have been proposed to examine the variance between experimental and predicted outcome and preferred the preeminent model based on its evaluation parameters performance and graph analysis. The grey relational analysis is the relevant approach to obtain the best grouping of input variables for maximum material removal rate and minimum surface roughness. Based on statistical analysis, it has been concluded that pulse-on time, interaction between pulse-on time x pulse-off time, spark-gap voltage and wire tension are the momentous variable for surface roughness while the pulse-on time, spark-gap voltage and pulse-off time are the momentous variables for material removal rate. The micro structural and compositional changes on the surface of work material were examined by means of SEM and EDX analysis. The thickness of the white layer and the recast layer formation increases with increases in the pulse-on time duration.
Innovative model-based flow rate optimization for vanadium redox flow batteries
König, S.; Suriyah, M. R.; Leibfried, T.
2016-11-01
In this paper, an innovative approach is presented to optimize the flow rate of a 6-kW vanadium redox flow battery with realistic stack dimensions. Efficiency is derived using a multi-physics battery model and a newly proposed instantaneous efficiency determination technique. An optimization algorithm is applied to identify optimal flow rates for operation points defined by state-of-charge (SoC) and current. The proposed method is evaluated against the conventional approach of applying Faraday's first law of electrolysis, scaled to the so-called flow factor. To make a fair comparison, the flow factor is also optimized by simulating cycles with different charging/discharging currents. It is shown through the obtained results that the efficiency is increased by up to 1.2% points; in addition, discharge capacity is also increased by up to 1.0 kWh or 5.4%. Detailed loss analysis is carried out for the cycles with maximum and minimum charging/discharging currents. It is shown that the proposed method minimizes the sum of losses caused by concentration over-potential, pumping and diffusion. Furthermore, for the deployed Nafion 115 membrane, it is observed that diffusion losses increase with stack SoC. Therefore, to decrease stack SoC and lower diffusion losses, a higher flow rate during charging than during discharging is reasonable.
An, Kang; Chen, Liangxian; Liu, Jinlong; Zhao, Yun; Yan, Xiongbo; Hua, Chenyi; Guo, Jianchao; Wei, Junjun; Hei, Lifu; Li, Chengming; Lu, Fanxiu
2017-09-01
The effect of the substrate holder feature dimensions on plasma density (n e), power density (Q mw) and gas temperature (T) of a discharge marginal plasma (a plasma caused by marginal discharge) and homogeneous plasma were investigated for the microwave plasma chemical vapor deposition process. Our simulations show that decreasing the dimensions of the substrate holder in a radical direction and increasing its dimension in the direction of the axis helps to produce marginally inhomogeneous plasma. When the marginal discharge appears, the maximum plasma density and power density appear at the edge of the substrate. The gas temperature increases until a marginally inhomogeneous plasma develops. The marginally inhomogeneous plasma can be avoided using a movable substrate holder that can tune the plasma density, power density and gas temperature. It can also ensure that the power density and electron density are as high as possible with uniform distribution of plasma. Moreover, both inhomogeneous and homogeneous diamond films were prepared using a new substrate holder with a diameter of 30 mm. The observation of inhomogeneous diamond films indicates that the marginal discharge can limit the deposition rate in the central part of the diamond film. The successfully produced homogeneous diamond films show that by using a substrate holder it is possible to deposit diamond film at 7.2 μm h-1 at 2.5 kW microwave power.
Directory of Open Access Journals (Sweden)
Huan Yang
2015-11-01
Full Text Available Based on charge-discharge cycle tests for commercial nickel-metal hydride (Ni-MH batteries, a nonlinear relationship is found between the discharging capacity (Cdischarge, Ah and the voltage changes in 1 s occurring at the start of the charging process (ΔVcharge, mV. This nonlinear relationship between Cdischarge and ΔVcharge is described with a curve equation, which can be determined using a nonlinear least-squares method. Based on the curve equation, a curve model for the state-of-health (SOH prediction is constructed without battery models and cycle numbers. The validity of the curve model is verified using (Cdischarge, ΔVcharge data groups obtained from the charge-discharge cycle tests at different rates. The results indicate that the curve model can be effectively applied to predict the SOH of the Ni-MH batteries and the best prediction root-mean-square error (RMSE can reach upto 1.2%. Further research is needed to confirm the application of this empirical curve model in practical fields.
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Yoshinobu Sato
2012-01-01
Full Text Available The impact of climate change on river discharge was assessed by hydrological simulations for several major river basins in Japan using the latest version of a super-high-resolution atmospheric general circulation model (AGCM with a horizontal resolution of about 20 km. Projections were made using two different datasets, one representing the present climate (1980 - 1999 and the other representing the end of the 21st century (2080 - 2099 assuming the SRES A1B scenario. River discharge was estimated by a distributed hydrological model calibrated against observed river discharge in advance. The results showed that even if the amount of precipitation does not change much in the future, river discharge will change significantly because of the increase in rainfall, decrease in snowmelt, and increase in evapotranspiration with higher air temperature. The impact of climate change on river discharge will be more significant in the northern part of Japan, especially in the Tohoku and Hokuriku regions. In these regions, the monthly average river discharge at the end of the 21st century was projected to be more than 200% higher in February and approximately 50 - 60% lower in May compared with the present flow. These results imply that the increase in air temperature has important consequences for the hydrological cycle, particularly in regions where the water supply is currently dominated by snowmelt.
Ogungbemi, Kayode I.
The Optogalvanic Effect (OGE) of neon in a hollow cathode discharge lamp has been investigated both experimentally and theoretically. A tunable dye laser was tuned to several 1si -- 2pj neon transitions and the associated time--resolved optogalvanic (OG) spectral waveforms recorded corresponding to the DeltaJ = DeltaK = 0, +/-1 selection rules and modeled using a semi-empirical model. Decay rate constants, amplitudes and the instrumentation time constants were recorded following a good least-squares fit (between the experimental and the theoretical OG data) using the Monte Carlo technique and utilizing both the search and random walk methods. Dominant physical processes responsible for the optogalvanic effect have been analyzed, and the corresponding populations of the laser-excited level and collisional excited levels determined. The behavior of the optogalvanic signal waveform as a function of time, together with the decay rate constants as a function of the discharge current and the instrumentation time constant as a function of current have been studied in detail. The decay times of the OG signals and the population redistributions were also determined. Fairly linear relationships between the decay rate constant and the discharge current, as well as between the instrumental time constant and the discharge current, have been observed. The decay times and the electron collisional rate parameters of the 1s levels involved in the OG transitions have been obtained with accuracy. The excitation temperature of the discharge for neon transitions grouped with the same 1s level have been determined and found to be fairly constant for the neon transitions studied. The experimental optogalvanic effort in the visible region of the electromagnetic spectrum has been complemented by a computation-intensive modeling investigation of rocket plumes in the microwave region. Radio frequency lines of each of the plume species identified were archived utilizing the HITRAN and other
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Daniel J Tollin
2014-12-01
Full Text Available The interaural level difference (ILD cue to sound location is first encoded in the lateral superior olive (LSO. ILD sensitivity results because the LSO receives excitatory input from the ipsilateral cochlear nucleus and inhibitory input indirectly from the contralateral cochlear nucleus via glycinergic neurons of the ipsilateral medial nucleus of the trapezoid body (MNTB. It is hypothesized that in order for LSO neurons to encode ILDs, the sound spectra at both ears must be accurately encoded via spike rate by their afferents. This spectral-coding hypothesis has not been directly tested in MNTB, likely because MNTB neurons have been mostly described and studied recently in regards to their abilities to encode temporal aspects of sounds, not spectral. Here, we test the hypothesis that MNTB neurons and their inputs from the cochlear nucleus and auditory nerve code sound spectra via discharge rate. The Random Spectral Shape method was used to estimate how the levels of 100-ms duration spectrally stationary stimuli were weighted, both linearly and non- linearly, across a wide band of frequencies. In general, MNTB neurons and their globular bushy cell inputs, were found to be well-modeled by a linear weighting of spectra demonstrating that the pathways through the MNTB can accurately encode sound spectra including those resulting from the acoustical cues to sound location provided by head-related directional transfer functions. Together with the anatomical and biophysical specializations for timing in the MNTB-LSO complex, these mechanisms may allow ILDs to be computed for complex stimuli with rapid spectrotemporally-modulated envelopes such as speech and animal vocalizations and moving sound sources.
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J. G. Leon
2006-09-01
Full Text Available The main objective of this paper is to review the usefulness of altimetric data in ungauged or very poorly monitored basin. It is shown that altimetric measurements can be combined with a single in-situ gauge to derive a reliable stage-discharge relationship upstream from the gauge. The Caqueta River in the Colombian Amazon Basin was selected to simulate a poorly monitored basin. Thus it was possible to derive the stage-discharge relationship for 13 "virtual gauge stations'' defined at river crossing with radar altimetric ground tracks. Stage measurements are derived from altimetric data following the methodology developed by Leon et al. (2006. Discharge is modeled using PROGUM – a flow routing model based on the Muskingum Cunge (M-C approach considering a diffusion-cum-dynamic wave propagation (Leon et al., 2006 using a single gauge located downstream from the basin under study. Rating curve parameters at virtual stations are estimated by fitting with a power law the temporal series of water surface altitude derived from satellite measurements and the modelled discharges. The methodology allows the ellipsoidal height of effective zero flow to be estimated. This parameter is a good proxy of the mean water depth from which the bottom slope of the reaches can be computed. Validation has been conducted by comparing the results with stages and discharges measured at five other gauges available on the Caqueta basin. Outflow errors range from 10% to 20% between the upper basin and the lower basin, respectively. Mean absolute differences less than 1.10 m between estimated equivalent water depth and measured water depth indicates the reliability of the proposed method. Finally, a 1.2×10^{−4} mm^{−1} mean bottom slope has been obtained for the 730 km long reach of the Caqueta main stream considered.
Glow discharge in low pressure plasma PVD: mathematical model and numerical simulations
Speranza, A; Meacci, L; Fanfani, S; Borsi, I; Monti, A; 10.1007/s11012-010-9330-z
2010-01-01
In this paper we analyze the problem of glow discharge in low pressure plasma in industrial plant, for chambers of different shapes and various working parameters, like pressure and electric potential. The model described is based upon a static approximation of the AC configuration with two electrodes and a drift diffusion approximation for the current density of positive ions and electrons. A detailed discussion of the boundary conditions imposed is given, as well as the full description of the mathematical model. Numerical simulations were performed for a simple 1D model and two different 2D models, corresponding to two different settings of the industrial plant. The simpler case consists of a radially symmetric chamber, with one central electrode (cathode), based upon a DC generator. In this case, the steel chamber acts as the anode. The second model concerns a two dimensional horizontal cut of the most common plant configuration, with two electrodes connected to an AC generator. The case is treated in a "...
Modeling of thermal spalling during electrical discharge machining of titanium diboride
Energy Technology Data Exchange (ETDEWEB)
Gadalla, A.M.; Bozkurt, B.; Faulk, N.M. (Texas A and M Univ., Dept. of Chemical Engineering, College Station, TX (US))
1991-04-01
Erosion in electrical discharge machining has been described as occurring by melting and flushing the liquid formed. Recently, however, thermal spalling was reported as the mechanism for machining refractory materials with low thermal conductivity and high thermal expansion. The process is described in this paper by a model based on a ceramic surface exposed to a constant circular heating source which supplied a constant flux over the pulse duration. The calculations were based on TiB{sub 2} mechanical properties along a and c directions. Theoretical predictions were verified by machining hexagonal TiB{sub 2}. Large flakes of TiB{sub 2} with sizes close to grain size and maximum thickness close to the predicted values were collected, together with spherical particles of Cu and Zn eroded from cutting wire. The cutting surfaces consist of cleavage planes sometimes contaminated with Cu, Zn, and impurities from the dielectric fluid.
Weir, Graham J.; Dolby, Carl E.
1999-07-01
The rapid and uncontrolled discharge of a large-sized granular-like material from a vertical cylinder is modelled assuming a modified kinematic relationship exists between granular pressure, speed and density. Discharge is driven by the initial Janssen pressure, and a Beverloo-type equation is derived for the initial discharge. A shock occurs at the bottom of the cylinder, and another upwards travelling shock separates static and moving material. The initial discharge is non-constant, with the constant density and discharge case violating the `entropy' condition. Two sets of characteristics are found : one travelling upwards, associated with the motion of voids; and the other travelling downwards, associated with work performed by the particle pressure. Contrary to hopper models, a low density of solids is predicted about the cylinder exit. The modified kinematic model allows density waves to travel either up or down through the cylinder, but the frequency and speed of the waves is not fixed uniquely by the model. The waves exhibit a saw-tooth behaviour, with a continuously increasing magnitude in flux at the orifice, interspersed with discontinuous decreases.
Modeling rating curves using remotely-sensed LiDAR data
Nathanson, M.; Lyon, S. W.; Kean, J. W.; Grabs, T. J.; Seibert, J.; Laudon, H.
2010-12-01
Discharge is important since it integrates water from across the landscape. In remote locations, however, it is often difficult to obtain accurate streamflow information because of the difficulty of obtaining the discharge measurements necessary to define stage-discharge relationships (rating curves). The aim of this study is to investigate the feasibility of defining rating curves indirectly using a fluid-mechanically based model constrained with topographic data from airborne LiDAR scanning. The study is carried out for a small 8-m wide channel in the boreal landscape of northern Sweden. Helicopter-mounted LiDAR data with an approximately 30-cm average point spacing was used to define the channel geometry above a low flow water surface along a 90-m long reach. The channel topography below the surface was estimated using the simple assumption of a flat bed. The roughness for the modeled reach was back-calculated from a single direct measurement of discharge. This topographic and roughness information was then used to calculate a rating curve using the method of Kean and Smith (JGR-Earth Surface, 2010). The rating curve from the LiDAR scan was compared with direct measurements of discharge, as well as with a calculated rating curve developed using more detailed topographic data from a ground survey. In general, there was good agreement between all three methods. The calculated rating curve based on the detailed ground survey was in the best agreement with the direct measurements. The LiDAR-based rating curve was in good agreement with the medium and high flow measurements, but deviated from the direct measurements at low flows. The discrepancy between the LiDAR-based rating curve and the low flow measurements is due to unresolved bed topography, which could not be detected by the scan because of the cover of water. This deficiency can be minimized by scanning during periods of extremely low flow. The results so far suggest that further studies using combined site
Experiment and Modeling of ITER Demonstration Discharges in the DIII-D Tokamak
Energy Technology Data Exchange (ETDEWEB)
Park, Jin Myung [ORNL; Doyle, E. J. [University of California, Los Angeles; Ferron, J.R. [General Atomics, San Diego; Holcomb, C T [Lawrence Livermore National Laboratory (LLNL); Jackson, G. L. [General Atomics; Lao, L. L. [General Atomics; Luce, T.C. [General Atomics, San Diego; Owen, Larry W [ORNL; Murakami, Masanori [ORNL; Osborne, T. H. [General Atomics; Politzer, P. A. [General Atomics, San Diego; Prater, R. [General Atomics; Snyder, P. B. [General Atomics
2011-01-01
DIII-D is providing experimental evaluation of 4 leading ITER operational scenarios: the baseline scenario in ELMing H-mode, the advanced inductive scenario, the hybrid scenario, and the steady state scenario. The anticipated ITER shape, aspect ratio and value of I/{alpha}B were reproduced, with the size reduced by a factor of 3.7, while matching key performance targets for {beta}{sub N} and H{sub 98}. Since 2008, substantial experimental progress was made to improve the match to other expected ITER parameters for the baseline scenario. A lower density baseline discharge was developed with improved stationarity and density control to match the expected ITER edge pedestal collisionality ({nu}*{sub e} {approx} 0.1). Target values for {beta}{sub N} and H{sub 98} were maintained at lower collisionality (lower density) operation without loss in fusion performance but with significant change in ELM characteristics. The effects of lower plasma rotation were investigated by adding counter-neutral beam power, resulting in only a modest reduction in confinement. Robust preemptive stabilization of 2/1 NTMs was demonstrated for the first time using ECCD under ITER-like conditions. Data from these experiments were used extensively to test and develop theory and modeling for realistic ITER projection and for further development of its optimum scenarios in DIII-D. Theory-based modeling of core transport (TGLF) with an edge pedestal boundary condition provided by the EPED1 model reproduces T{sub e} and T{sub i} profiles reasonably well for the 4 ITER scenarios developed in DIII-D. Modeling of the baseline scenario for low and high rotation discharges indicates that a modest performance increase of {approx} 15% is needed to compensate for the expected lower rotation of ITER. Modeling of the steady-state scenario reproduces a strong dependence of confinement, stability, and noninductive fraction (f{sub NI}) on q{sub 95}, as found in the experimental I{sub p} scan, indicating that
Pintassilgo, C. D.; Jaoul, C.; Loureiro, J.; Belmonte, T.; Czerwiec, T.
2007-06-01
A kinetic study is conducted to investigate the elementary processes scheme that produces methane decomposition as a small percentage of this gas is introduced downstream in the flowing afterglow of a nitrogen microwave discharge. For this purpose a self-consistent kinetic model is used for the discharge and corresponding afterglow including, besides the species associated with active nitrogen, such as vibrationally excited N_2(X\\, ^1\\Sigma_g^+,v) molecules, N_2(A\\, ^3\\Sigma_u^+) and N_2(a^{\\prime}\\,^1\\Sigma_u^-) metastables and N(4S) atoms, various hydrocarbons formed from methane decomposition, and other species produced in nitrogen-methane reactions. It is observed that CH4 is primarily dissociated in CH3 and CH2 in collisions with N2(A), the stable hydrogen cyanide molecule HCN is formed at an intermediate stage of the process, HCN and CH2 give place to the formation of CN(X 2Σ+), and ultimately C atoms are produced by collisions of CN(X) with N atoms. The predicted concentrations so obtained are compared with experimental determinations of N and C atoms and of N2(B 3Πg) and CN(B 2Σ+) states, these latter obtained from spectroscopic measurements.
Energy Technology Data Exchange (ETDEWEB)
Pintassilgo, C D [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Jaoul, C [Sciences des Procedes Ceramiques et Traitements de Surfaces, Universite de Limoges, 87068 Limoges Cedex (France); Loureiro, J [Centro de Fisica dos Plasmas, Instituto Superior Tecnico, 1049-001 Lisbon (Portugal); Belmonte, T [Laboratoire de Science et Genie des Surfaces, Ecole des Mines, 5402 Nancy Cedex (France); Czerwiec, T [Laboratoire de Science et Genie des Surfaces, Ecole des Mines, 5402 Nancy Cedex (France)
2007-06-21
A kinetic study is conducted to investigate the elementary processes scheme that produces methane decomposition as a small percentage of this gas is introduced downstream in the flowing afterglow of a nitrogen microwave discharge. For this purpose a self-consistent kinetic model is used for the discharge and corresponding afterglow including, besides the species associated with active nitrogen, such as vibrationally excited N{sub 2}(X{sup 1}{sigma}{sub g}{sup +}, v) molecules, N{sub 2}(A{sup 3}{sigma}{sub u}{sup +}) and N{sub 2}(a'{sup 1}{sigma}{sub u}{sup -}) metastables and N({sup 4}S) atoms, various hydrocarbons formed from methane decomposition, and other species produced in nitrogen-methane reactions. It is observed that CH{sub 4} is primarily dissociated in CH{sub 3} and CH{sub 2} in collisions with N{sub 2}(A), the stable hydrogen cyanide molecule HCN is formed at an intermediate stage of the process, HCN and CH{sub 2} give place to the formation of CN(X {sup 2}{sigma}{sup +}), and ultimately C atoms are produced by collisions of CN(X) with N atoms. The predicted concentrations so obtained are compared with experimental determinations of N and C atoms and of N{sub 2}(B {sup 3}{pi}{sub g}) and CN(B {sup 2}{sigma}{sup +}) states, these latter obtained from spectroscopic measurements.
One-equation modeling and validation of dielectric barrier discharge plasma actuator thrust
Yoon, Jae-San; Han, Jae-Hung
2014-10-01
Dielectric barrier discharge (DBD) plasma actuators with an asymmetric electrode configuration can generate a wall-bounded jet without mechanical moving parts, which require considerable modifications of existing aeronautical objects and which incur high maintenance costs. Despite this potential, one factor preventing the wider application of such actuators is the lack of a reliable actuator model. It is difficult to develop such a model because calculating the ion-electric field and fluid interaction consume a high amount calculation effort during the numerical analysis. Thus, the authors proposed a semi-empirical model which predicted the thrust of plasma actuators with a simple equation. It gave a numeric thrust value, and we implemented the value on a computational fluid dynamics (CFD) solver to describe the two-dimensional flow field induced by the actuator. However, the model had a narrow validation range, depending on the empirical formula, and it did not fully consider environment variables. This study presents an improved model by replacing the empirical formulae in the previous model with physical equations that take into account physical phenomena and environmental variables. During this process, additional operation parameters, such as pressure, temperature and ac waveforms, are newly taken to predict the thrust performance of the actuators with a wider range of existing parameters, the thickness of the dielectric barrier, the exposed electrode, the dielectric constant, the ac frequency and the voltage amplitude. Thrust prediction curves from the model are compared to those of earlier experimental results, showing that the average error is less than 5% for more than one hundred instances of data. As in the earlier work, the predicted thrust value is implemented on a CFD solver, and two-dimensional wall-jet velocity profiles induced by the actuator are compared to the previous experimental results.
Dynamics of dissolved organic carbon in hillslope discharge: Modeling and challenges
Dusek, Jaromir; Vogel, Tomas; Dohnal, Michal; Barth, Johannes A. C.; Sanda, Martin; Marx, Anne; Jankovec, Jakub
2017-03-01
Reliable quantitative prediction of water movement and fluxes of dissolved substances - specifically organic carbon - at both the hillslope and the catchment scales remains a challenge due to complex boundary conditions and soil spatial heterogeneity. In addition, microbially mediated transformations of dissolved organic carbon (DOC) are recognized to determine the balance of DOC in soils. So far, only few studies utilized stable water isotope information in modeling and even fewer linked dissolved carbon fluxes to mixing and/or transport models. In this study, stormflow dynamics of 18O/16O ratios in the water molecules (expressed as δ18O) and DOC were analyzed using a physically-based modeling approach. A one-dimensional dual-continuum vertical flow and transport model was used to simulate the subsurface transport processes in a forest hillslope soil over a period of 2.5 years. The model was applied to describe the transformation of input signals of δ18O and DOC into output signals observed in the hillslope stormflow. To quantify uncertainty associated with the model parameterization, Monte Carlo analysis in conjunction with Latin hypercube sampling was applied. δ18O variations in hillslope discharge and in soil pore water were predicted reasonably well. Despite the complex nature of microbial transformations that caused uncertainty in model parameters and subsequent prediction of DOC transport, the simulated temporal patterns of DOC concentration in stormflow showed similar behavior to that reflected in the observed DOC fluxes. Due to preferential flow, the contribution of the hillslope DOC export was higher than the amounts that are usually found in the available literature.
Lau, Vincent I; Priestap, Fran A; Lam, Joyce N H; Ball, Ian M
2016-09-20
To evaluate the relationship between rates of discharge directly to home (DDH) from the intensive care unit (ICU) and bed availability (ward and ICU). Also to identify patient characteristics that make them candidates for safe DDH and describe transfer delay impact on length of stay (LOS). Retrospective cohort study of all adult patients who survived their stay in our medical-surgical-trauma ICU between April 2003 and March 2015. Median age was 49 years (interquartile range [IQR]: 33.5-60.4), and the majority of the patients were males (54.8%). Median number of preexisting comorbidities was 5 (IQR: 2-7) diagnoses. Discharge directly to home increased from 28 (3.1% of all survivors) patients in 2003 to 120 (12.5%) patients in 2014. The mean annual rate of DDH was between 11% and 12% over the last 6 years. Approximately 62% (n = 397) of patients waited longer than 4 hours for a ward bed, with a median delay of 2.0 days (IQR: 0.5-4.7) before being DDH. There was an inverse correlation between ICU occupancy and DDH rates (r P = -.55, P occupancy and DDH rates (r s = -.055, P = .64, 95% CI = -0.25 to 0.21). The DDH rates have been increasing over time at our institution and were inversely correlated with ICU bed occupancy but were not associated with ward occupancy. The DDH patients are young, have few comorbidities on admission, and few discharge diagnoses, which are usually reversible single system problems with low disease burden. Transfers to the ward are delayed in a majority of cases, leading to increased ICU LOS and likely increased overall hospital LOS as well. © The Author(s) 2016.
Directory of Open Access Journals (Sweden)
M. Coustau
2013-03-01
Full Text Available Mediterranean catchments in southern France are threatened by potentially devastating fast floods which are difficult to anticipate. In order to improve the skill of rainfall-runoff models in predicting such flash floods, hydrologists use data assimilation techniques to provide real-time updates of the model using observational data. This approach seeks to reduce the uncertainties present in different components of the hydrological model (forcing, parameters or state variables in order to minimize the error in simulated discharges. This article presents a data assimilation procedure, the best linear unbiased estimator (BLUE, used with the goal of improving the peak discharge predictions generated by an event-based hydrological model Soil Conservation Service lag and route (SCS-LR. For a given prediction date, selected model inputs are corrected by assimilating discharge data observed at the basin outlet. This study is conducted on the Lez Mediterranean basin in southern France. The key objectives of this article are (i to select the parameter(s which allow for the most efficient and reliable correction of the simulated discharges, (ii to demonstrate the impact of the correction of the initial condition upon simulated discharges, and (iii to identify and understand conditions in which this technique fails to improve the forecast skill. The correction of the initial moisture deficit of the soil reservoir proves to be the most efficient control parameter for adjusting the peak discharge. Using data assimilation, this correction leads to an average of 12% improvement in the flood peak magnitude forecast in 75% of cases. The investigation of the other 25% of cases points out a number of precautions for the appropriate use of this data assimilation procedure.
Coustau, M.; Ricci, S.; Borrell-Estupina, V.; Bouvier, C.; Thual, O.
2013-03-01
Mediterranean catchments in southern France are threatened by potentially devastating fast floods which are difficult to anticipate. In order to improve the skill of rainfall-runoff models in predicting such flash floods, hydrologists use data assimilation techniques to provide real-time updates of the model using observational data. This approach seeks to reduce the uncertainties present in different components of the hydrological model (forcing, parameters or state variables) in order to minimize the error in simulated discharges. This article presents a data assimilation procedure, the best linear unbiased estimator (BLUE), used with the goal of improving the peak discharge predictions generated by an event-based hydrological model Soil Conservation Service lag and route (SCS-LR). For a given prediction date, selected model inputs are corrected by assimilating discharge data observed at the basin outlet. This study is conducted on the Lez Mediterranean basin in southern France. The key objectives of this article are (i) to select the parameter(s) which allow for the most efficient and reliable correction of the simulated discharges, (ii) to demonstrate the impact of the correction of the initial condition upon simulated discharges, and (iii) to identify and understand conditions in which this technique fails to improve the forecast skill. The correction of the initial moisture deficit of the soil reservoir proves to be the most efficient control parameter for adjusting the peak discharge. Using data assimilation, this correction leads to an average of 12% improvement in the flood peak magnitude forecast in 75% of cases. The investigation of the other 25% of cases points out a number of precautions for the appropriate use of this data assimilation procedure.
Filament Discharge Phenomena in Fingerprint Acquisition by Dielectric Barrier Discharge
Institute of Scientific and Technical Information of China (English)
WENG Ming; XU Weijun; LIU Qiang
2007-01-01
In this paper, the dielectric barrier discharge fingerprint acquisition technique is introduced. The filament discharge phenomena were observed in the process of fingerprint acquisition. The filament discharge reduced the quality of fingerprint images. Obviously, it was necessary to eliminate streamer discharges in order to get good fingerprint images. The streamer discharge was considered to be the cause of the filament discharge in the experiment. The relationship between the critical electric field and the discharge gap was calculated with the Raether's model of streamer discharge. The calculated results and our experiment proved that it would be difficult for the streamer discharge to occur when the discharge gap was narrow. With a narrow discharge gap, the discharge was homogeneous, and the fingerprint images were clear and large in area. The images obtained in the experiment are very suitable for fingerprint identification as they contain more information.
Hippensteele, S. A.; Cochran, R. P.
1980-01-01
The effects of two design parameters, electrode diameter and hole angle, and two machine parameters, electrode current and current-on time, on air flow rates through small-diameter (0.257 to 0.462 mm) electric-discharge-machined holes were measured. The holes were machined individually in rows of 14 each through 1.6 mm thick IN-100 strips. The data showed linear increase in air flow rate with increases in electrode cross sectional area and current-on time and little change with changes in hole angle and electrode current. The average flow-rate deviation (from the mean flow rate for a given row) decreased linearly with electrode diameter and increased with hole angle. Burn time and finished hole diameter were also measured.
Forecasting monthly inflow discharge of the Iffezheim reservoir using data-driven models
Zhang, Qing; Aljoumani, Basem; Hillebrand, Gudrun; Hoffmann, Thomas; Hinkelmann, Reinhard
2017-04-01
River stream flow is an essential element in hydrology study fields, especially for reservoir management, since it defines input into reservoirs. Forecasting this stream flow plays an important role in short or long-term planning and management in the reservoir, e.g. optimized reservoir and hydroelectric operation or agricultural irrigation. Highly accurate flow forecasting can significantly reduce economic losses and is always pursued by reservoir operators. Therefore, hydrologic time series forecasting has received tremendous attention of researchers. Many models have been proposed to improve the hydrological forecasting. Due to the fact that most natural phenomena occurring in environmental systems appear to behave in random or probabilistic ways, different cases may need a different methods to forecast the inflow and even a unique treatment to improve the forecast accuracy. The purpose of this study is to determine an appropriate model for forecasting monthly inflow to the Iffezheim reservoir in Germany, which is the last of the barrages in the Upper Rhine. Monthly time series of discharges, measured from 1946 to 2001 at the Plittersdorf station, which is located 6 km downstream of the Iffezheim reservoir, were applied. The accuracies of the used stochastic models - Fiering model and Auto-Regressive Integrated Moving Average models (ARIMA) are compared with Artificial Intelligence (AI) models - single Artificial Neural Network (ANN) and Wavelet ANN models (WANN). The Fiering model is a linear stochastic model and used for generating synthetic monthly data. The basic idea in modeling time series using ARIMA is to identify a simple model with as few model parameters as possible in order to provide a good statistical fit to the data. To identify and fit the ARIMA models, four phase approaches were used: identification, parameter estimation, diagnostic checking, and forecasting. An automatic selection criterion, such as the Akaike information criterion, is utilized
Spiteri, C.
2007-01-01
The quality of groundwater, in particular in coastal areas, is increasingly deteriorating due to the input of nutrients (NO3-, NH4+ and PO4) from septic systems and agricultural leaching. The discharge of groundwater to coastal waters, termed submarine groundwater discharge (SGD), is now recognized
Applicability of CFD Modelling in Determining Accurate Weir Discharge: Water Level Relationships
Rombouts, P.M.M.; Tralli, A.; Langeveld, J.G.; Verhaart, F.; Clemens, F.H.L.R.
2014-01-01
Being able to accurately determine weir discharges is of key importance in urban water management. The most common method is performing a level measurement and calculating the discharge using the standard weir equation. Since this equation is only valid in certain conditions, this can lead to large
Ballesteros, Daniel; Meléndez, Mónica; Malard, Arnauld; Jiménez-Sánchez, Montserrat; Heredia, Nemesio; Jeannin, Pierre-Yves; García-Sansegundo, Joaquín
2014-05-01
The study of karst aquifers developed in high-mountain areas is quite complex since the application of many techniques of hydrogeology in these areas is difficult, expensive, and requires many hours of field work. In addition, the access to the study area is usually conditioned by the orography and the meteorological conditions. A pragmatic approach to study these aquifers can be the combination of geometric models of the aquifer with the monitoring of the discharge rate of springs and the meteorological records. KARSYS approach (Jeannin et al. 2013) allows us to elaborate a geometric model of karst aquifers establishing the boundaries of the groundwater bodies, the main drainage axes and providing evidences of the catchment delineation of the springs. The aim of this work is to analyse the functioning of the karst aquifer from the western and central part of the Picos de Europa Mountains (Spain) combining the KARSYS approach, the discharge record from two springs and the meteorological records (rain, snow and temperature). The Picos de Europa (North Spain) is a high-mountains area up to 2.6 km altitude with 2,500 mm/year of precipitations. The highest part of these mountains is covered by snow four to seven months a year. The karst aquifer is developed in Carboniferous limestone which is strongly compartmentalized in, at least, 17 groundwater bodies. The method of work includes: 1) the elaboration of a hydrogeological 3D model of the geometry of the karst aquifers by KARSYS approach, 2) the definition of the springs catchment areas based on the hydrogeological 3D model, 3) the selection of two representative springs emerging from the aquifers to study it, 4) the continuous monitoring of water levels in two karst springs since October 2013, 5) the transformation of the water level values to flow values using height-stream relation curves constructed by measures of the spring discharge, and 5) the comparison of the spring discharge rate records and meteorological
Introducing AORN's new model for evidence rating.
Spruce, Lisa; Van Wicklin, Sharon A; Hicks, Rodney W; Conner, Ramona; Dunn, Debra
2014-02-01
Nurses today are expected to implement evidence-based practices in the perioperative setting to assess and implement practice changes. All evidence-based practice begins with a question, a practice problem to address, or a needed change that is identified. To assess the question, a literature search is performed and relevant literature is identified and appraised. The types of evidence used to inform practice can be scientific research (eg, randomized controlled trials, systematic reviews) or nonresearch evidence (eg, regulatory and accrediting agency requirements, professional association practice standards and guidelines, quality improvement project reports). The AORN recommended practices are a synthesis of related knowledge on a given topic, and the authorship process begins with a systematic review of the literature conducted in collaboration with a medical librarian. At least two appraisers independently evaluate the applicable literature for quality and strength by using the AORN Research Appraisal Tool and AORN Non-Research Appraisal Tool. To collectively appraise the evidence supporting particular practice recommendations, the AORN recommended practices authors have implemented a new evidence rating model that is appropriate for research and nonresearch literature and that is relevant to the perioperative setting.
Modeling Equity for Alternative Water Rate Structures
Griffin, R.; Mjelde, J.
2011-12-01
The rising popularity of increasing block rates for urban water runs counter to mainstream economic recommendations, yet decision makers in rate design forums are attracted to the notion of higher prices for larger users. Among economists, it is widely appreciated that uniform rates have stronger efficiency properties than increasing block rates, especially when volumetric prices incorporate intrinsic water value. Yet, except for regions where water market purchases have forced urban authorities to include water value in water rates, economic arguments have weakly penetrated policy. In this presentation, recent evidence will be reviewed regarding long term trends in urban rate structures while observing economic principles pertaining to these choices. The main objective is to investigate the equity of increasing block rates as contrasted to uniform rates for a representative city. Using data from four Texas cities, household water demand is established as a function of marginal price, income, weather, number of residents, and property characteristics. Two alternative rate proposals are designed on the basis of recent experiences for both water and wastewater rates. After specifying a reasonable number (~200) of diverse households populating the city and parameterizing each household's characteristics, every household's consumption selections are simulated for twelve months. This procedure is repeated for both rate systems. Monthly water and wastewater bills are also computed for each household. Most importantly, while balancing the budget of the city utility we compute the effect of switching rate structures on the welfares of households of differing types. Some of the empirical findings are as follows. Under conditions of absent water scarcity, households of opposing characters such as low versus high income do not have strong preferences regarding rate structure selection. This changes as water scarcity rises and as water's opportunity costs are allowed to
Modeling battery cells under discharge using kinetic and stochastic battery models
Kaj, Ingemar; Konane, Victorien
2016-01-01
In this paper we review several approaches to mathematical modeling of simple battery cells and develop these ideas further with emphasis on charge recovery and the response behavior of batteries to given external load. We focus on models which use few parameters and basic battery data, rather than detailed reaction and material characteristics of a specific battery cell chemistry, starting with the coupled ODE linear dynamics of the kinetic battery model. We show that a related system of PDE...
Modeling And Forecasting Exchange-Rate Shocks
Andreou, A. S.; Zombanakis, George A.; Likothanassis, S. D.; Georgakopoulos, E.
1998-01-01
This paper considers the extent to which the application of neural networks methodology can be used in order to forecast exchange-rate shocks. Four major foreign currency exchange rates against the Greek Drachma as well as the overnight interest rate in the Greek market are employed in an attempt to predict the extent to which the local currency may be suffering an attack. The forecasting is extended to the estimation of future exchange rates and interest rates. The MLP proved to be highly ...
DEFF Research Database (Denmark)
Hansen, Anne Lausten; Refsgaard, Jens Christian; Christensen, Britt Stenhøj Baun;
2013-01-01
the catchment. In this study, a coupled groundwater-surface water model based on the MIKE SHE code was developed for the 4.7 km2 Lillebæk catchment in Denmark, where tile drain flow is a major contributor to the stream discharge. The catchment model was calibrated in several steps by incrementally including...... the observation data into the calibration to see the effect on model performance of including diverse data types, especially tile drain discharge. For the Lillebæk catchment, measurements of hydraulic head, daily stream discharge, and daily tile drain discharge from five small (1–4 ha) drainage areas exist....... The results showed that including tile drain data in the calibration of the catchment model improved its general performance for hydraulic heads and stream discharges. However, the model failed to correctly describe the local-scale dynamics of the tile drain discharges, and, furthermore, including the drain...
Account of near-cathode sheath in numerical models of high-pressure arc discharges
Benilov, M. S.; Almeida, N. A.; Baeva, M.; Cunha, M. D.; Benilova, L. G.; Uhrlandt, D.
2016-06-01
Three approaches to describing the separation of charges in near-cathode regions of high-pressure arc discharges are compared. The first approach employs a single set of equations, including the Poisson equation, in the whole interelectrode gap. The second approach employs a fully non-equilibrium description of the quasi-neutral bulk plasma, complemented with a newly developed description of the space-charge sheaths. The third, and the simplest, approach exploits the fact that significant power is deposited by the arc power supply into the near-cathode plasma layer, which allows one to simulate the plasma-cathode interaction to the first approximation independently of processes in the bulk plasma. It is found that results given by the different models are generally in good agreement, and in some cases the agreement is even surprisingly good. It follows that the predicted integral characteristics of the plasma-cathode interaction are not strongly affected by details of the model provided that the basic physics is right.
Shifman, Aaron R; Longtin, André; Lewis, John E
2015-10-30
Identifying and understanding the current sources that give rise to bioelectric fields is a fundamental problem in the biological sciences. It is very difficult, for example, to attribute the time-varying features of an electroencephalogram recorded from the head surface to the neural activity of specific brain areas; model systems can provide important insight into such problems. Some species of fish actively generate an oscillating (c. 1000 Hz) quasi-dipole electric field to communicate and sense their environment in the dark. A specialized electric organ comprises neuron-like cells whose collective signal underlies this electric field. As a step towards understanding the detailed biophysics of signal generation in these fish, we use an anatomically-detailed finite-element modelling approach to reverse-engineer the electric organ signal over one oscillation cycle. We find that the spatiotemporal profile of current along the electric organ constitutes a travelling wave that is well-described by two spatial Fourier components varying in time. The conduction velocity of this wave is faster than action potential conduction in any known neuronal axon (>200 m/s), suggesting that the spatiotemporal features of high-frequency electric organ discharges are not constrained by the conduction velocities of spinal neuron pathways.
Lee, Hyo-Chang; Chung, Chin-Wook
2016-09-01
Hysteresis, which is the history dependence of physical systems, indicates that there are more-than-two stable points in a given condition, and it has been considered to one of the most important topics in fundamental physics. Recently, the hysteresis of plasma has become a focus of research because stable plasma operation is very important for fusion reactors, bio-medical plasmas, and industrial plasmas for nano-device fabrication process. Interestingly, the bi-stability characteristics of plasma with a huge hysteresis loop have been observed in inductive discharge plasmas Because hysteresis study in such plasmas can provide a universal understanding of plasma physics, many researchers have attempted experimental and theoretical studies. Despite long plasma research, how this plasma hysteresis occurs remains an unresolved question in plasma physics. Here, we report theory, experiment, and modeling of the hysteresis. It was found experimentally and theoretically that evolution of the electron energy distribution (EED) makes a strong plasma hysteresis. In Ramsauer and non-Ramsauer gas experiments, it was revealed that the plasma hysteresis is observed only at high pressure Ramsauer gas where the EED deviates considerably from a Maxwellian shape. This hysteresis was presented in the plasma balance model where the EED is considered. Because electrons in plasmas are usually not in a thermal equilibrium, this EED-effect can be regarded as a universal phenomenon in plasma physics. This research was partially supported by Korea Research Institute of Standard and Science.
Lee, S. S.; Sengupta, S.
1978-01-01
Two sets of programs, named Nasum 2 and Nasum 3 are presented in detail. Nasum 2 is a far field formulation and is used without including the plant thermal discharge. Nasum 3 uses horizontal stretching to provide higher resolution at thermal discharge joints; and includes far field influences such as varying tides and ambient currents far from point of discharge.
Visible and VUV images of dielectric barrier discharges in Xe
Energy Technology Data Exchange (ETDEWEB)
Mildren, R.P. [Centre for Lasers and Applications, Macquarie University, Sydney, NSW (Australia); Carman, R.J. [Department of Physics, Macquarie University, Sydney, NSW (Australia); Falconer, I.S. [School of Physics A28, University of Sydney, Sydney, NSW (Australia)
2001-12-07
We have recorded short exposure images of visible and vacuum ultraviolet (VUV) emission from a Xe dielectric barrier discharge lamp, and investigated the effects of excitation by fast rising pulse and sinusoidal voltage waveforms on the discharge structure. The images from the pulsed discharge are essentially uniform over the active electrode area unlike the sinusoidal discharge which is filamentary. By investigating a single filament discharge, it is also found that a large fraction ((>)90%) of the total visible and VUV emission for sinusoidal excitation is generated from regions outside the filament. The images suggest that the VUV is generated from surface discharges, or 'feelers', which branch out laterally from the filaments. Model calculations suggest that surface or volume discharges, in which the current density is much lower than for filamentary discharges, generate VUV emission more efficiently due to the reduced rate for multi-step electron excitation of Xe* species. (author)
Z. Kalantari; Jansson, P.-E.; Stolte, J.; Folkeson, L.; French, H. K.; M. Sassner
2012-01-01
Four hydrological models (LISEM, MIKE SHE, CoupModel and HBV) were compared with respect to their capability to predict peak flow in a small catchment upstream of a road in SE Norway on an hourly basis. All four models were calibrated using hourly observed streamflow. Simulated and observed discharge generated during three types of hydrological situations characteristic of winter/spring conditions causing overland flow were considered: snowmelt, partially frozen soil and hea...
Institute of Scientific and Technical Information of China (English)
Xuan Wang; Xian-Cui Wu
2016-01-01
Objective: We sought to determine any benefits of applying a transitional care model in the continuum of cancer pain management, especially after patients' discharge from the hospital. Methods: A total of 156 eligible participants were recruited and randomly assigned into intervention or control groups. The control group received standard care, while the intervention group received extra, specialized transitional care of pain management. Outcomes were measured at weeks 0 and 2e4 and included demographic data, the Brief Pain Inventory, Global Quality of Life Scale, and Satisfaction Degree of Nursing Service. Adequacy of analgesia and severity of pain were assessed with the Pain Management Index and interview findings. Results: After 2e4 weeks of intervention, there was a significant difference in the change in average pain score between intervention and control groups (P <0.05). Reductions in pain scores were significantly greater in the intervention group than in the control group (difference:0.98, P<0.05). Regarding pain management outcomes, there was a significantly better condition in the intervention group compared with the control group;in the intervention group, 79%of patients had adequate opioids, whereas in the control group, only 63% of patients reported having adequate opioids. Furthermore, there was a signif-icant difference between the two groups in quality of life (QOL) scores (P<0.05);the intervention group had significantly higher quality of life than the control group (difference: 1.06). Finally, there was a significant difference in the degree of satisfaction with the home nursing service;the intervention group had a significantly higher degree of satisfaction with the home nursing service in three aspects:quality, content, and attitude of service. Conclusions: The application of a transitional care model in cancer pain management after discharge could help patients to improve their cancer pain management knowledge and analgesics compliance. In
Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.
2016-05-01
An active volume scaling in bore and length of a Sr atom laser excited in a nanosecond pulse longitudinal He-SrBr2 discharge is carried out. Considering axial symmetry and uniform power input, a 2D model (r, z) is developed by numerical methods for determination of gas temperature in a new large-volume high-temperature discharge tube with additional incompact ZrO2 insulation in the discharge free zone, in order to find out the optimal thermal mode for achievement of maximal output laser parameters. A 2D model (r, z) of gas temperature is developed by numerical methods for axial symmetry and uniform power input. The model determines gas temperature of nanosecond pulsed longitudinal discharge in helium with small additives of strontium and bromine.
Roatta, Silvestro; Arendt-Nielsen, Lars; Farina, Dario
2008-11-15
Animal and in vitro studies have shown that the sympathetic nervous system modulates the contractility of skeletal muscle fibres, which may require adjustments in the motor drive to the muscle in voluntary contractions. In this study, these mechanisms were investigated in the tibialis anterior muscle of humans during sympathetic activation induced by the cold pressor test (CPT; left hand immersed in water at 4 degrees C). In the first experiment, 11 healthy men performed 20 s isometric contractions at 10% of the maximal torque, before, during and after the CPT. In the second experiment, 12 healthy men activated a target motor unit at the minimum stable discharge rate for 5 min in the same conditions as in experiment 1. Intramuscular electromyographic (EMG) signals and torque were recorded and used to assess the motor unit discharge characteristics (experiment 1) and spike-triggered average twitch torque (experiment 2). CPT increased the diastolic blood pressure and heart rate by (mean +/- S.D.) 18 +/- 9 mmHg and 4.7 +/- 6.5 beats min(-1) (P < 0.01), respectively. In experiment 1, motor unit discharge rate increased from 10.4 +/- 1.0 pulses s(-1) before to 11.1 +/- 1.4 pulses s(-1) (P < 0.05) during the CPT. In experiment 2, the twitch half-relaxation time decreased by 15.8 +/- 9.3% (P < 0.05) during the CPT with respect to baseline. These results provide the first evidence of an adrenergic modulation of contractility of muscle fibres in individual motor units in humans, under physiological sympathetic activation.
Biplot models applied to cancer mortality rates.
Osmond, C
1985-01-01
"A graphical method developed by Gabriel to display the rows and columns of a matrix is applied to tables of age- and period-specific cancer mortality rates. It is particularly useful when the pattern of age-specific rates changes with time. Trends in age-specific rates and changes in the age distribution are identified as projections. Three examples [from England and Wales] are given."
Model Uncertainty and Exchange Rate Forecasting
Kouwenberg, Roy; Markiewicz, Agnieszka; Verhoeks, Ralph; Zwinkels, Remco
2013-01-01
textabstractWe propose a theoretical framework of exchange rate behavior where investors focus on a subset of economic fundamentals. We find that any adjustment in the set of predictors used by investors leads to changes in the relation between the exchange rate and fundamentals. We test the validity of this framework via a backward elimination rule which captures the current set of fundamentals that best predicts the exchange rate. Out-of-sample forecasting tests show that the backward elimi...
Factor Model Forecasts of Exchange Rates
Charles Engel; Nelson C. Mark; Kenneth D. West
2012-01-01
We construct factors from a cross section of exchange rates and use the idiosyncratic deviations from the factors to forecast. In a stylized data generating process, we show that such forecasts can be effective even if there is essentially no serial correlation in the univariate exchange rate processes. We apply the technique to a panel of bilateral U.S. dollar rates against 17 OECD countries. We forecast using factors, and using factors combined with any of fundamentals suggested by Taylor r...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The relation between runoff volume and sediment yield for individual events in a given watershed receives little attention compared to the relation between water discharge and sediment yield, though it may underlie the event-based sediment-yield model for large-size watershed. The data observed at 12 experimental subwatersheds in the Dalihe river watershed in hilly areas of Loess Plateau, North China,was selected to develop and validate the relation. The peak flow is often considered as an important factor affecting event sediment yield. However, in the study areas, sediment concentration remains relatively constant when water discharge exceeds a certain critical value, implying that the heavier flow is not accompanied with the higher sediment transport capacity. Hence, only the runoff volume factor was considered in the sediment-yield model. As both the total sediment and runoff discharge were largely produced during the heavy-discharge stage, and the sediment concentration was negligibly variable during this stage, a proportional function can be used to model the relation between event runoff volume and sediment yield for a given subwatershed. The applicability of this model at larger spatial scales was also discussed, and it was found that for the Yaoxinzhuang station at the Puhe River basin, which controls a drainage area of 2264km2, a directly proportional relation between event runoff volume and sediment yield may also exist.
Meijer, P. M.; Passchier, J. D. P.; W. J. Goedheer,; Bezemer, J.; van Sark, Wgjhm
1994-01-01
The results of a two-dimensional fluid model for argon rf discharges in a closed cylindrical vacuum chamber are compared with experimental data from an amorphous silicon deposition reactor. Good agreement is obtained for the relation between the dc autobias voltage and the dissipated power in the fr
W. J. Goedheer,; Meijer, P. M.; Bezemer, J.; Passchier, J. D. P.; van Sark, Wgjhm
1995-01-01
The results of a 2-D fluid model for argon radiofrequency (RF) discharges in a closed cylindrical vacuum chamber are compared with experimental data from an amorphous silicon deposition reactor operated in argon. Good agreement is obtained for the relation between the DC autobias voltage and the dis
Scicchitano, F.; Rijn, C.M. van; Luijtelaar, E.L.J.M. van
2015-01-01
Research Question Recent discoveries have challenged the traditional view that the thalamus is the primary source driving spike-and-wave discharges (SWDs). At odds, SWDs in genetic absence models have a cortical focal origin in the deep layers of the perioral region of the somatosensory cortex. The
Ghani, N. Ab; Abrahart, R. J.; Clifford, N. J.
2009-04-01
Neural networks can be trained to model the sediment-discharge relationship: numerous illustrative applications exist. The standard method of reporting involves using a scatterplot of observed versus predicted records, plus a handful of global statistics, to support an assessment of model skill. This traditional approach will nevertheless result in undesirable side effects since it reinforces the 'black box' criticisms and associated demonisation that is sometimes levelled at computational intelligence solutions: no 'line-of-best-fit' is ever supplied. This paper in contrast compares and evaluates six computational methods for modelling the sediment-discharge relationship from a structural and behavioural standpoint in which the exact nature of each model is visualised for the purposes of diagnostic appraisal and scientific enlightenment. The following methods are compared: backpropagation neural network; corrected power function; simple linear regression; piecewise linear regression using an M5 Model Tree; LOWESS; and Robust LOWESS. Modelling is restricted to a consideration of bivariate relationships. The models were developed on daily river discharge and sediment concentration datasets for two rivers in Missouri: Lower Salt River and Little Black River. Each dataset was divided into two parts using different methods and each model was first calibrated on one sub-set and thereafter tested on the other. The datasets were next swapped over and the process repeated. Each model is also evaluated using statistical measures calculated in HydroTest (http://www.hydrotest.org.uk/). The need for more benchmarking exercises of a similar nature is highlighted.
Supharatid, Seree
2003-10-01
This paper presents the applicability of neural network (NN) modelling for forecasting and filtering problems. The multilayer feedforward (MLFF) network was first constructed to forecast the tidal-level variations at the mouth of the River Chao Phraya in Thailand. Unlike the well-known conventional harmonic analysis, the NN model uses a set of previous data for learning and then forecasting directly the time-series of tidal levels. It was found that lead time of 1 to 24 hourly tidal levels can be predicted successfully using only a short-time hourly learning data. The MLFF network was further used to establish a stage-discharge relationship for the tidal river. The results show a considerably better performance of the NN model over the conventional models. In addition, the stage-discharge relationship obtained by the NN model can indicate reasonably well the important behaviour of the tidal influences. Copyright
Klett, C.; Touchard, S.; Vega-Gonzalez, A.; Redolfi, M.; Bonnin, X.; Hassouni, K.; Duten, X.
2012-08-01
This paper reports the results obtained for the degradation of acetaldehyde by an atmospheric plasma corona discharge working in a pulsed regime. It was shown that a few hundred ppm of acetaldehyde diluted in a pure N2 gas flow can be removed up to 80% by a discharge fed with an electric power lower than 1 W. Under the same conditions, adding up to 5% of O2 allowed the removal of up to 95% of the initial acetaldehyde. The main identified end products were CO2, CO and methanol. A quasi-homogeneous zero-dimensional chemical model was developed to investigate the respective efficiency of the discharge and post-discharge periods in the global removal of the pollutant. The identified main pathways of acetaldehyde degradation were quenching of N2 metastable states during plasma pulses and oxidation by O and OH radicals during the post-discharge. This latter contribution increased with input power because of ozone accumulation in the gas mixture acting as an additional oxygen reservoir.
Directory of Open Access Journals (Sweden)
Ignat Ignatov
2015-12-01
Full Text Available In this paper are submited data on the possibility of applying the coronal gas discharge effect (CGDE in modeling non-equilibrium conditions with gas electric discharge simulating conditions occurying in the primary atmosphere (electric sparks, lightning imitating S. Miller’s experiments. The physical basis and technique of visualization of gas discharge (GD glowing of water drops in alternating electric fields of high electrical voltage (5–30 kV and frequency (10–150 kHz, as well as the possible electrosynthesis of organic molecules from a mixture of inorganic substances as hydrogen (H2, methane (CH4, ammonia (NH3 and carbon monoxide (CO in aqueous solutions of water exposed under the electrical discharge, UV-radiation and thermal heating to t = +100 0C were examined. The colour coronal spectral gas discharge analysis was applied for investigation of water samples of various origin, the samples of hot mineral, sea and mountain water obtained from various water sources of Bulgaria.
Model Uncertainty and Exchange Rate Forecasting
R.R.P. Kouwenberg (Roy); A. Markiewicz (Agnieszka); R. Verhoeks (Ralph); R.C.J. Zwinkels (Remco)
2013-01-01
textabstractWe propose a theoretical framework of exchange rate behavior where investors focus on a subset of economic fundamentals. We find that any adjustment in the set of predictors used by investors leads to changes in the relation between the exchange rate and fundamentals. We test the validit
Bendtsen, Jørgen; Mortensen, John; Rysgaard, Søren
2017-04-01
Subglacial discharge from tidewater outlet glaciers forms convective bouyant freshwater plumes ascending close the glacier face, and entrainment of ambient bottom water increases the salinity of the water until the plume reaches its level of neutral buoyancy at sub-surface levels or reaches the surface. Relatively warm bottom water masses characterize many fjords around Greenland and therefore entrainment would also increase the temperature in the plumes and, thereby, impact the heat transport in the fjords. However, relatively few oceanographic measurements have been made in or near plumes from subglacial discharge and, therefore, the potential for subglacial discharge for increasing heat transport towards the tidewater outlet glaciers are poorly understood. We present the first direct hydrographic measurements in a plume from subglacial discharge in Godthåbsfjord (located on the western coast of Greenland) where a XCTD was launched from a helicopter directly into the plume. Measurements of the surface salinity showed that the plume only contained 7% of freshwater at the surface, implying a large entrainment with a mixing ratio of 1:13 between outflowing meltwater and saline fjord water. These observations are analyzed together with seasonal observations of ocean heat transport towards the tidewater outlet glaciers in Godthåbsfjord and we show that subglacial discharge only had modest effects on the overall heat budget in front of the glacier. These results were supported from a high-resolution three-dimensional model of Godthåbsfjord. The model explicitly considered subglacial freshwater discharge from three tidewater outlet glaciers where entrainment of bottom water was taken into account. Model results showed that subglacial discharge only affected the fjord circulation relatively close ( 10 km) to the glaciers. Thus, the main effect on heat transport was due to the freshwater discharge itself whereas the subsurface discharge and associated entrainment only
The effect of modelling on drinking rate.
Garlington, W K; Dericco, D A
1977-01-01
Three male college seniors were asked to drink beer at their normal rate in a simulated tavern setting. Each was paired with a confederate, also a male college senior, in an ABACA single subject design. In the baseline conditions, the confederate matched the drinking rate of the subject. Baseline and all subsequent conditions were continued in 1-hr sessions until a stable drinking rate was achieved. In Condition B, the confederate drank either one third more or one third less than the subject's baseline rate. In Condition C, the direction was reversed. All three subjects closely matched the confederate's drinking rate, whether high or low. All subjects reported they were unaware of the true purpose of the study.
Baldus, Sabrina; Schröder, Daniel; Bibinov, Nikita; Schulz-von der Gathen, Volker; Awakowicz, Peter
2015-06-01
Cold atmospheric pressure plasmas are a promising alternative therapy for treatment of chronic wounds, as they have already shown in clinical trials. In this study an air dielectric barrier discharge (DBD) developed for therapeutic use in dermatology is characterized with respect to the plasma produced reactive oxygen species, namely atomic oxygen and ozone, which are known to be of great importance to wound healing. To understand the plasma chemistry of the applied DBD, xenon-calibrated two-photon laser-induced fluorescence spectroscopy and optical absorption spectroscopy are applied. The measured spatial distributions are shown and compared to each other. A model of the afterglow chemistry based on optical emission spectroscopy is developed to cross-check the measurement results and obtain insight into the dynamics of the considered reactive oxygen species. The atomic oxygen density is found to be located mostly between the electrodes with a maximum density of {{n}\\text{O}}=6× {{10}16} cm-3 . Time resolved measurements reveal a constant atomic oxygen density between two high voltage pulses. The ozone is measured up to 3 mm outside the active plasma volume, reaching a maximum value of {{n}{{\\text{O}3}}}=3× {{10}16} cm-3 between the electrodes.
Issakhov, Alibek
2016-06-01
The paper presents a mathematical model of distribution the discharged heat water from thermal power plant under various operational capacities on the aquatic environment. It was solved by the Navier-Stokes and temperature equations for an incompressible fluid in a stratified medium were based on the splitting method by physical parameters which approximated by the finite volume method. The numerical solution of the equation system was divided into four stages. At the first step it was assumed that the momentum transfer carried out only by convection and diffusion. While the intermediate velocity field was solved by 5-step Runge-Kutta method. At the second stage, the pressure field was solved by found the intermediate velocity field. Whereas Poisson equation for the pressure field was solved by Jacobi method. The third step assumes that the transfer was carried out only by pressure gradient. Finally the fourth step of the temperature equation was also solved as motion equations, with 5-step Runge-Kutta method. The algorithm was parallelized on high-performance computer. The obtained numerical results of three-dimensional stratified turbulent flow were compared with experimental data. What revealed qualitatively and quantitatively approximately the basic laws of hydrothermal processes occurring in the reservoir-cooler.
Casares, R.; Marino-Tapia, I.
2013-05-01
Coastal lagoons are subjected to physical forces that make them vulnerable to climate change and human intervention. The karstic geology along the coastal zone of Yucatan Peninsula, Mexico, forces groundwater to discharge in the sea and coastal lagoons through underground conduits that can form small but numerous and scattered underwater springs. These freshwater inputs, along with other physical forces like ocean tides and meteorological events, can have a significant effect on the circulation and residence times in coastal lagoons. Climate change consequences such as sea level rise and changing rain patterns, as well as the increasing human impact, can cause or aggravate certain environmental effects. Since coastal lagoons provide important environmental services there is a need to understand and have predictive capability to simulate the transport processes and the forces acting on them. The present study was carried out in the coastal lagoon of Celestun, located at NW Yucatan Peninsula, a region of karstic geology. The aim of this research is to understand the barotropic hydrodynamic functioning of this shallow system, taking into account the oceanographical, meteorological and hydrological forcing. Emphasis is made on the residence times in different parts of the lagoon, and the effects of freshwater inputs. For the detailed understanding of the processes the hydrodynamic numerical model DELFT3D was implemented. The model was validated with data gathered on the field during two intensive oceanographic campaigns, which included installation of CTDs and acoustic current meters at strategic sites distributed in the system, and detailed bathymetric measurements using an echosounder coupled with a differential GPS on board of a motorboat. In order to improve model performance a sensitivity analysis to the main variables involved in the model was carried out, among them: the size of the grid cells, grid depth, time step, friction coefficients, boundary conditions
Energy Technology Data Exchange (ETDEWEB)
GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; DAI,JINXIANG; XIAO,T. DANNY; REISNER,DAVID
2000-05-25
Using an optimized thermal-spray process, coherent, dense deposits of pyrite (FeS{sub 2}) with good adhesion were formed on 304 stainless steel substrates (current collectors). After leaching with CS{sub 2} to remove residual free sulfur, these served as cathodes in Li(Si)/FeS{sub 2} thermal cells. The cells were tested over a temperature range of 450 C to 550 C under baseline loads of 125 and 250 mA/cm{sup 2}, to simulate conditions found in a thermal battery. Cells built with such cathodes outperformed standard cells made with pressed-powder parts. They showed lower interracial resistance and polarization throughout discharge, with higher capacities per mass of pyrite. Post-treatment of the cathodes with Li{sub 2}O coatings at levels of >7% by weight of the pyrite was found to eliminate the voltage transient normally observed for these materials. Results equivalent to those of standard lithiated catholytes were obtained in this manner. The use of plasma-sprayed cathodes allows the use of much thinner cells for thermal batteries since only enough material needs to be deposited as the capacity requirements of a given application demand.
Petri nets extension to model state-varying failure rates
DEFF Research Database (Denmark)
Lazarova-Molnar, Sanja
2013-01-01
One of the most common assumptions in reliability modeling is the constant failure rate. This has been increasingly changing lately, yielding significant research towards abandoning simulation results based on this assumption; thus, deeming constant failure rates as inadequate to model failures......-varying failure rates and extend the formalism of Petri nets to model them. To illustrate our approach we provide an example model that features state-varying failure rates....
Predicting tile drainage discharge
DEFF Research Database (Denmark)
Iversen, Bo Vangsø; Kjærgaard, Charlotte; Petersen, Rasmus Jes;
of the water load coming from the tile drainage system is therefore essential. This work aims at predicting tile drainage discharge using dynamic as well as a statistical predictive models. A large dataset of historical tile drain discharge data, daily discharge values as well as yearly average values were......More than 50 % of Danish agricultural areas are expected to be artificial tile drained. Transport of water and nutrients through the tile drain system to the aquatic environment is expected to be significant. For different mitigation strategies such as constructed wetlands an exact knowledge...... used in the analysis. For the dynamic modelling, a simple linear reservoir model was used where different outlets in the model represented tile drain as well as groundwater discharge outputs. This modelling was based on daily measured tile drain discharge values. The statistical predictive model...
Directory of Open Access Journals (Sweden)
Gangadharudu Talla
2015-09-01
Full Text Available Low material removal rate (MRR and high surface roughness values hinder large-scale application of electro discharge machining (EDM in the fields like automobile, aerospace and medical industry. In recent years, however, EDM has gained more significance in these industries as the usage of difficult-to-machine materials including metal matrix composites (MMCs increased. In the present work, an attempt has been made to fabricate and machine aluminum/alumina MMC using EDM by adding aluminum powder in kerosene dielectric. Results showed an increase in MRR and decrease in surface roughness (Ra compared to those for conventional EDM. Semi empirical models for MRR and Ra based on machining parameters and important thermo physical properties were established using a hybrid approach of dimensional and regression analysis. A multi response optimization was also performed using principal component analysis-based grey technique (Grey-PCA to determine optimum settings of process parameters for maximum MRR and minimum Ra within the experimental range. The recommended setting of process parameters for the proposed process has been found to be powder concentration (Cp = 4 g/l, peak current (Ip = 3 A, pulse on time (Ton = 150 μs and duty cycle (Tau = 85%.
Abd Rahman, M S; L. Hao; Rapisarda, P.; Lewin, P L
2012-01-01
In high voltage plant, ageing processes can occur in the dielectric and insulation system which are totally unavoidable and ultimately limit the operational life of the plant. For example, these unwanted processes can cause partial discharge (PD) activity inside a transformer and the presence of this activity will lead to further ageing and degradation processes until eventually there is catastrophic failure. Therefore, partial discharge condition monitoring inside a transformer and along a t...
RSV bronchiolitis - discharge; Respiratory syncytial virus bronchiolitis - discharge ... Your child has bronchiolitis , which causes swelling and mucus to build up in the smallest air passages of the lungs. In the hospital, ...
Meyfroidt, Geert; Güiza, Fabian; Cottem, Dominiek; De Becker, Wilfried; Van Loon, Kristien; Aerts, Jean-Marie; Berckmans, Daniël; Ramon, Jan; Bruynooghe, Maurice; Van den Berghe, Greet
2011-10-25
The intensive care unit (ICU) length of stay (LOS) of patients undergoing cardiac surgery may vary considerably, and is often difficult to predict within the first hours after admission. The early clinical evolution of a cardiac surgery patient might be predictive for his LOS. The purpose of the present study was to develop a predictive model for ICU discharge after non-emergency cardiac surgery, by analyzing the first 4 hours of data in the computerized medical record of these patients with Gaussian processes (GP), a machine learning technique. Non-interventional study. Predictive modeling, separate development (n = 461) and validation (n = 499) cohort. GP models were developed to predict the probability of ICU discharge the day after surgery (classification task), and to predict the day of ICU discharge as a discrete variable (regression task). GP predictions were compared with predictions by EuroSCORE, nurses and physicians. The classification task was evaluated using aROC for discrimination, and Brier Score, Brier Score Scaled, and Hosmer-Lemeshow test for calibration. The regression task was evaluated by comparing median actual and predicted discharge, loss penalty function (LPF) ((actual-predicted)/actual) and calculating root mean squared relative errors (RMSRE). Median (P25-P75) ICU length of stay was 3 (2-5) days. For classification, the GP model showed an aROC of 0.758 which was significantly higher than the predictions by nurses, but not better than EuroSCORE and physicians. The GP had the best calibration, with a Brier Score of 0.179 and Hosmer-Lemeshow p-value of 0.382. For regression, GP had the highest proportion of patients with a correctly predicted day of discharge (40%), which was significantly better than the EuroSCORE (p nurses (p = 0.044) but equivalent to physicians. GP had the lowest RMSRE (0.408) of all predictive models. A GP model that uses PDMS data of the first 4 hours after admission in the ICU of scheduled adult cardiac surgery
Two-dimensional, hybrid model of glow discharge in hollow cathode geometries
Energy Technology Data Exchange (ETDEWEB)
Fiala, A.; Pitchford, L.C.; Boeuf, J.P. [Universite Paul Sabatier, Toulouse (France)
1995-12-31
Low pressure glow discharges in plane-plane geometries have been studied extensively over the years and most of their features are known from experiments and numerical simulation. If a plane cathode is replaced by a cathode with some hollow structure, then, for a certain range of conditions, the negative glows of opposite (adjacent) cathode walls overlap and the discharge behaviour dramatically changes. The voltage is lower at a constant current and the current is even several orders of magnitude higher for a given voltage than for the plane cathode. At the same time, the intensity of the light emission from the discharge considerably increases. This effect is called the hollow cathode effect. There are several physical phenomena which could be responsible for the big efficiency of the hollow cathode discharges. The recent investigations based on the Monte Carlo simulation of the electron kinetics have shown that the trapping of energetic electrons in the hollow cathode cavity can explain the order of magnitude of the hollow cathode effect. The configuration of the discharge tube presented in fig. 1 is used here to study the behaviour of glow discharges in a hollow cathode means of numerical simulation.
Forecasting the Euro exchange rate using vector error correction models
Aarle, B. van; Bos, M.; Hlouskova, J.
2000-01-01
Forecasting the Euro Exchange Rate Using Vector Error Correction Models. — This paper presents an exchange rate model for the Euro exchange rates of four major currencies, namely the US dollar, the British pound, the Japanese yen and the Swiss franc. The model is based on the monetary approach of ex
Lam, N.; Lyon, S. W.; Kean, J. W.
2015-12-01
The rating curve enables the translation of water depth into discharge through a reference cross section. Errors in estimating stream channel geometry can therefore result in increased discharge uncertainty. This study investigates coupling national-scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. Specifically, stream channel geometries were generated from coupled ALS and ADCP scanning data collected for a well-monitored site located in northern Sweden. These data were used to define the hydraulic geometry required by a physically-based 1-D hydraulic model. The results of our study demonstrate that the effects of potential scanning data errors on the model generated rating curve were less than the uncertainties due to stream gauging measurements and empirical rating curve fitting. Further analysis of the ALS data showed that an overestimation of the streambank elevation (the main scanning data error) was primarily due to vegetation that could be adjusted for through a root-mean-square-error bias correction. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establish rating curves at gauging stations.
Further Results on Dynamic Additive Hazard Rate Model
Directory of Open Access Journals (Sweden)
Zhengcheng Zhang
2014-01-01
Full Text Available In the past, the proportional and additive hazard rate models have been investigated in the works. Nanda and Das (2011 introduced and studied the dynamic proportional (reversed hazard rate model. In this paper we study the dynamic additive hazard rate model, and investigate its aging properties for different aging classes. The closure of the model under some stochastic orders has also been investigated. Some examples are also given to illustrate different aging properties and stochastic comparisons of the model.
Kalantari, Z.; Jansson, P.-E.; Stolte, J.; Folkeson, L.; French, H. K.; Sassner, M.
2012-04-01
Four hydrological models (LISEM, MIKE SHE, CoupModel and HBV) were compared with respect to their capability to predict peak flow in a small catchment upstream of a road in SE Norway on an hourly basis. All four models were calibrated using hourly observed streamflow. Simulated and observed discharge generated during three types of hydrological situations characteristic of winter/spring conditions causing overland flow were considered: snowmelt, partially frozen soil and heavy rain events. Using parameter sets optimised for winter/spring conditions, flows simulated by HBV coupled with CoupModel were comparable to measured discharge from the catchment in corresponding periods. However, this combination was best when all the parameters were calibrated in HBV. For ungauged basins with no real-time monitoring of discharge and when the spatial distribution is important, MIKE SHE may be more suitable than the other models, but the lack of detailed input data and the uncertainty in physical parameters should be considered. LISEM is potentially capable of calculating runoff from small catchments during winter/spring but requires better description of snowmelt, infiltration into frozen layers and tile drainage. From a practical road maintenance perspective, the usefulness and accuracy of a model depends on its ability to represent site-specific processes, data availability and calibration requirements.
Directory of Open Access Journals (Sweden)
Z. Kalantari
2012-04-01
Full Text Available Four hydrological models (LISEM, MIKE SHE, CoupModel and HBV were compared with respect to their capability to predict peak flow in a small catchment upstream of a road in SE Norway on an hourly basis. All four models were calibrated using hourly observed streamflow. Simulated and observed discharge generated during three types of hydrological situations characteristic of winter/spring conditions causing overland flow were considered: snowmelt, partially frozen soil and heavy rain events. Using parameter sets optimised for winter/spring conditions, flows simulated by HBV coupled with CoupModel were comparable to measured discharge from the catchment in corresponding periods. However, this combination was best when all the parameters were calibrated in HBV. For ungauged basins with no real-time monitoring of discharge and when the spatial distribution is important, MIKE SHE may be more suitable than the other models, but the lack of detailed input data and the uncertainty in physical parameters should be considered. LISEM is potentially capable of calculating runoff from small catchments during winter/spring but requires better description of snowmelt, infiltration into frozen layers and tile drainage. From a practical road maintenance perspective, the usefulness and accuracy of a model depends on its ability to represent site-specific processes, data availability and calibration requirements.
Core-SOL modelling of neon seeded JET discharges with the ITER-like wall
Energy Technology Data Exchange (ETDEWEB)
Telesca, G. [Department of Applied Physics, Ghent University (Belgium); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Ivanova-Stanik, I.; Zagoerski, R.; Czarnecka, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Brezinsek, S.; Huber, A.; Wiesen, S. [Forschungszentrum Juelich GmbH, Institut fuer Klima- und Energieforschung-Plasmaphysik, Juelich (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Drewelow, P. [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Giroud, C. [CCFE Culham, Abingdon (United Kingdom); EUROfusion Consortium, JET, Culham Science Centre, Abingdon (United Kingdom); Collaboration: JET EFDA contributors
2016-08-15
Five ELMy H-mode Ne seeded JET pulses have been simulated with the self-consistent core-SOL model COREDIV. In this five pulse series only the Ne seeding rate was changed shot by shot, allowing a thorough study of the effect of Ne seeding on the total radiated power and of its distribution between core and SOL tobe made. The increase in the simulations of the Ne seeding rate level above that achieved in experiments shows saturation of the total radiated power at a relatively low radiated-heating power ratio (f{sub rad} = 0.60) and a further increase of the ratio of SOL to core radiation, in agreement with the reduction of W release at high Ne seeding level. In spite of the uncertainties caused by the simplified SOL model of COREDIV (neutral model, absence of ELMs and slab model for the SOL), the increase of the perpendicular transport in the SOL with increasing Ne seeding rate, which allows to reproduce numerically the experimental distribution core-SOL of the radiated power, appears to be of general applicability. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)
Directory of Open Access Journals (Sweden)
M. Hafiz Helmi
2009-09-01
Full Text Available This paper presents the investigation on surface roughness and material removal rate (MRR of tool steel machined with brass and copper electrode for Electrical Discharge Grinding (EDG process. The machining parameter include pulse ON time, pulse OFF time, peak current and capacitance. Analysis of variance (ANOVA with Taguchi method is used to investigate the significant effect on the performance characteristic and the optimal cutting parameters of EDG. The result shows that, the surface roughness value when using of both tool materials are mostly influenced by pulse ON time and peak current. The capacitance parameter in both experiments was not giving any significant effect. The significant factors for the material removal rate due to the machining parameter are peak current parameter and ON time parameter but it also can increase the machining time
A self-consistent fluid model for radio-frequency discharges in SiH4-H-2 compared to experiments
Nienhuis, G. J.; W. J. Goedheer,; Hamers, E. A. G.; van Sark, Wgjhm; Bezemer, J.
1997-01-01
A one-dimensional fluid model for radio-frequency glow discharges is presented which describes silane/hydrogen discharges that are used for the deposition of amorphous silicon (a-Si:H). The model is used to investigate the relation between the external settings (such as pressure, gas inlet, applied
Lee, S. S.; Sengupta, S.; Nwadike, E. V.
1980-01-01
A user's manual for a one dimensional thermal model to predict the temperature profiles of a deep body of water for any number of annual cycles is presented. The model is essentially a set of partial differential equations which are solved by finite difference methods using a high speed digital computer. The model features the effects of area change with depth, nonlinear interaction of wind generated turbulence and buoyancy, adsorption of radiative heat flux below the surface, thermal discharges, and the effects of vertical convection caused by discharge. The main assumption in the formulation is horizontal homogeneity. The environmental impact of thermal discharges from power plants is emphasized. Although the model is applicable to most lakes, a specific site (Lake Keowee, S.C.) application is described in detail. The programs are written in FORTRAN 5.
Directory of Open Access Journals (Sweden)
Ahmed N. Al-Khazraji
2015-09-01
Full Text Available This paper concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (PMEDM of high carbon high chromium AISI D2 steel. The type of electrode (copper and graphite, the pulse current and the pulse-on time and mixing powder in kerosene dielectric fluid are taken as the process main input parameters. The material removal rate MRR, the tool wear ratio TWR and the work piece surface roughness (SR are taken as output parameters to measure the process performance. The experiments are planned using response surface methodology (RSM design procedure. Empirical models are developed for MRR, TWR and SR, using the analysis of variance (ANOVA.The best results for the productivity of the process (MRR obtained when using the graphite electrodes, the pulse current (22 A, the pulse on duration (120 µs and using the graphite powder mixing in kerosene dielectric reaches (82.84mm³/min. The result gives an improvement in material removal rate of (274% with respect to the corresponding value obtained when copper electrodes with kerosene dielectric alone. The best results for the tool wear ratio (TWR of the process obtained when using the copper electrodes, the pulse current (8 A, the pulse on duration (120 µs and using the kerosene dielectric alone reaches (0.31 %. The use of graphite electrodes, the kerosene dielectric with 5g/l graphite powder mixing, the pulse current (8 A, the pulse on duration (40 µs give the best surface roughness of a value (2.77 µm.This result yields an improvement in SR by (141% with respect to the corresponding value obtained when using copper electrodes and the kerosene dielectric alone with the same other parameters and machining conditions.
Modelling the filling rate of pit latrines
African Journals Online (AJOL)
2012-09-18
Sep 18, 2012 ... 4 July 2013. ISSN 1816-7950 (On-line) = Water SA Vol. 39 No. 4 July 2013 ... Keywords: Pit latrine, filling rate, biodegradation, solid waste disposal ...... by considerations of logistics, human resources, cost and the subsequent ...
Energy Technology Data Exchange (ETDEWEB)
Loarte, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Chankin, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Clement, S. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Corrigan, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Harbour, P. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Horton, L. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Janeschitz, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Lingertat, J. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Matthews, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Simonini, R. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Tagle, J.A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Taroni, A. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom); Vlases, G. [JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (United Kingdom)
1995-04-01
Modelling with the EDGE2D/U-NIMBUS code of the measured scrape-off layer plasma parameters for JET divertor discharges is presented. Model results agree with the experiment if very small values (< or {approx}0.1 m{sup 2}/s in H-modes and low power L-modes) for the anomalous particle transport diffusion coefficient in the SOL are used. While the assumption of the power flow out of the main plasma being carried equally by the electrons and the ions describes satisfactorily the global power balance for Ohmic and L-mode discharges, more power flowing out through the ion channel is consistent with the power balance in hot ion H-modes. Some sensitivity studies of the code results on the modelling hypothesis are discussed. ((orig.)).
Institute of Scientific and Technical Information of China (English)
WANG Chao; WANG Pei-fang
2005-01-01
Laboratory experiments were conducted to investigate the mixture of wastewater discharged from a submerged multiport diffuser in the Nantong sea-area. The process was then simulated with a three-dimensional numerical model. The plane or line patch was used to impose the discharge momentum flux in the near field. A comparison of model simulation with laboratory experiments shows that the proposed model can be used to simulate the shapes of pollution plumes, the distributions of excess concentration, and the velocity induced by a coflowing diffuser in proximity to a shoreline boundary. From the numerical simulation and laboratory experiments, it is recommended that the multiport diffuser be placed in a hydrodynamically active sea-area.
Energy Technology Data Exchange (ETDEWEB)
Schwabedissen, A. (Inst. fuer Plasmaphysik, Univ. Hannover (Germany)); Loffhagen, D. (Inst. fuer Plasmaphysik, Univ. Hannover (Germany)); Boetticher, W. (Inst. fuer Plasmaphysik, Univ. Hannover (Germany)); Hammer, T. (Siemens AG, Corp. Research and Development, Plasma and Switching Technology, Erlangen (Germany))
1994-06-01
Absorption spectroscopic measurements of effective particle number densities of excited Xe, Ne, Cl, and H performed on a small scale discharge with well-defined current and voltage pulses are compared with the results of model calculations over a wide range of discharge parameters. The reaction kinetic pathways determining the ionization and dissociative attachment rates have been verified by the good agreement obtained during the quasi-steady-state phase of the discharge for Xe and H. To reproduce the rise times of the excited Xe particle number densities during the ignition phase, the electron collision excitation cross sections of ground state Xe published by Puech and Mizzi had to be enhanced by about 25%. From the Ne measurements it is concluded that the electron collision excitation cross sections of ground state Ne published by Puech and Mizzi may be too large near the theshold. Measurements of excited Cl particle number densities re unsuitable to check the attachment kinetics of HCl, because these densities are mainly determined by reactions not involving the formation of Cl[sup -] ions. (orig.)
Schwabedissen, A.; Loffhagen, D.; Hammer, Th.; Bötticher, W.
1994-06-01
Absorption spectroscopic measurements of effective particle number densities of excited Xe, Ne, Cl, and H performed on a small scale discharge with well-defined current and voltage pulses are compared with the results of model calculations over a wide range of discharge parameters. The reaction kinetic pathways determining the ionization and dissociative attachment rates have been verified by the good agreement obtained during the quasi-steady-state phase of the discharge for Xe and H. To reproduce the rise times of the excited Xe particle number densities during the ignition phase, the electron collision excitation cross sections of ground state Xe published by Puech and Mizzi [1] had to be enhanced by about 25%. From the Ne measurements it is concluded that the electron collision excitation cross sections of ground state Ne published by Puech and Mizzi [1] may be too large near the threshold. Measurements of excited Cl particle number densities are unsuitable to check the attachment kinetics of HCl, because these densities are mainly determined by reactions not involving the formation of Cl- ions.
Modeling the Dynamics of Chinese Spot Interest Rates
Yongmiao Hong; Hai Lin; Shouyang Wang
2013-01-01
Understanding the dynamics of spot interest rates is important for derivatives pricing, risk management, interest rate liberalization, and macroeconomic control. Based on a daily data of Chinese 7-day repo rates from July 22, 1996 to August 26, 2004, we estimate and test a variety of popular spot rate models, including single factor diffusion, GARCH, Markov regime switching and jump diffusion models, to examine how well they can capture the dynamics of the Chinese spot rates and whether the d...
Zheng, B. C.; Wu, Z. L.; Wu, B.; Li, Y. G.; Lei, M. K.
2017-05-01
A spatially averaged, time-dependent global plasma model has been developed to describe the reactive deposition of a TiAlSiN thin film by modulated pulsed power magnetron sputtering (MPPMS) discharges in Ar/N2 mixture gas, based on the particle balance and the energy balance in the ionization region, and considering the formation and erosion of the compound at the target surface. The modeling results show that, with increasing the N2 partial pressure from 0% to 40% at a constant working pressure of 0.3 Pa, the electron temperature during the strongly ionized period increases from 4 to 7 eV and the effective power transfer coefficient, which represents the power fraction that effectively heats the electrons and maintains the discharge, increases from about 4% to 7%; with increasing the working pressure from 0.1 to 0.7 Pa at a constant N2 partial pressure of 25%, the electron temperature decreases from 10 to 4 eV and the effective power transfer coefficient decreases from 8% to 5%. Using the modeled plasma parameters to evaluate the kinetic energy of arriving ions, the ion-to-neutral flux ratio of deposited species, and the substrate heating, the variations of process parameters that increase these values lead to an enhanced adatom mobility at the target surface and an increased input energy to the substrate, corresponding to the experimental observation of surface roughness reduction, the microstructure transition from the columnar structure to the dense featureless structure, and the enhancement of phase separation. At higher N2 partial pressure or lower working pressure, the modeling results demonstrate an increase in electron temperature, which shifts the discharge balance of Ti species from Ti+ to Ti2+ and results in a higher return fraction of Ti species, corresponding to the higher Al/Ti ratio of deposited films at these conditions. The modeling results are well correlated with the experimental observation of the composition variation and the microstructure
Liu, Jingjing; Han, Shumin; Han, Da; Li, Yuan; Yang, Shuqin; Zhang, Lu; Zhao, Yumeng
2015-08-01
The A2B7-type lanthanum (La)-magnesium (Mg)-nickel (Ni)-based alloy with single (La,Mg)2Ni7 phase and different amounts of (La,Mg)5Ni19 minor phase was obtained by step-wise sintering. The impact of (La,Mg)5Ni19 phase on the alloy's microstructure and electrochemical performance was subsequently studied. It was found that the average subunit volume in (La,Mg)5Ni19 phase is smaller than that in (La,Mg)2Ni7 phase, resulting in increases of strains inside the alloys and decreases of cell volumes. During battery charge/discharge, the (La,Mg)5Ni19 phase network scattered in the alloys relieves internal stress, alleviates pulverization and oxidation of the alloys, stabilizes the stacking structures against amorphization, and finally improves the cycling stability of the alloys. Furthermore, (La,Mg)5Ni19 phase with higher Ni content desorbs hydrogen ahead of (La,Mg)2Ni7 phase. The reduced hydrogen pressure in (La,Mg)5Ni19 phase can subsequently lead to the fast discharge of (La,Mg)2Ni7 phase, thus making a remarkable improvement in high rate dischargeability at 1500 mA g-1 from 46.2% to 58.9% with increasing (La,Mg)5Ni19 phase abundance from 0 to 37.4 wt.%. Therefore, it is believed that A2B7-type La-Mg-Ni-based alloys with A5B19-type minor phase are promising prototypes for high-power and long-lifetime nickel/metal hydride battery electrode materials.
AN EOQ MODEL WITH CONTROLLABLE SELLING RATE
HORNG-JINH CHANG; PO-YU CHEN
2008-01-01
According to the marketing principle, a decision maker may control demand rate through selling price and the unit facility cost of promoting transaction. In fact, the upper bound of willing-to-pay price and the transaction cost probably depend upon the subjective judgment of individual consumer in purchasing merchandise. This study therefore attempts to construct a bivariate distribution function to simultaneously incorporate the willing-to-pay price and the transaction cost into the classica...
Model of control of glow discharge electron gun current for microelectronics production applications
Denbnovetsky, S. V.; Melnyk, V. I.; Melnyk, I. V.; Tugay, B. A.
2003-04-01
The problems of simulation of discharge current control and its gas-dynamic stabilization for technological glow discharge electron guns with a cold cathode are considered in a paper. Such guns are successfully operated in soft vacuum and can be used in modern microelectronic technologies for providing of thermal operations with using different technological gases including active ones. The results of theoretical and experimental investigation of automatic control system of current of electron gun which were used for deposition of coatings in reactive gas medium are presented in article. Time of regulation for considered system did not exceed 400 ms. Is proved, that the automatic control of a current of a glow discharge electron gun by pressure variation its volume is effective on all operation range of pressure, and the minimum time of a current regulation can be tens -- hundred of ms, and this fact is allow to use in the majority of technological operations for microelectronic production.
Institute of Scientific and Technical Information of China (English)
LI Yong; WANG Chao
2007-01-01
A simple estimation model of groundwater discharge and nutrient flux from nearshore unconfined aquifer to lake was studied. It was supposed that the aquifer was permeable isotropic homogeneously and its thickness approximated to the depth of lake. Distribution of the hydraulic gradient and the specific discharge along the transect of the discharge zone were discussed. Results show that the groundwater discharge patterns vary with the inclination angle of lakeshore bottom. For a shallow lake with gentle slope bottom, the rate of discharge of groundwater to lake is not constant across a discharge zone, but the discharge is concentrated in a narrow portion of the littoral zone where the Dupuit assumptions are invalid. The width of the discharge zone is correlative with aquifer thickness and slope of the lake bottom. The distribution functions of hydraulic gradient and groundwater discharge rates accord exponentially with offshore distance.
2006-06-01
Dielectric Barrier Discharge The Dielectric Barrier Discharge (DBD) device has been put to use since 1857 when Werner von Siemens used to produce...x y s t s t x y x ys t s t s t s t x y x y x yn S L t nx + − − Γ − Γ = − − Δ + Δ (18) and 1 1 2 2 , , , , ,, , , , , 1 , 1...driven flux and the thermal flux were oppositely directed. ( ), , , , 1s t s t s t s tadjacent Scharfetter Gummel thermal adjacenttn S L nx − − Δ = Γ
Line Shape Modeling for the Diagnostic of the Electron Density in a Corona Discharge
Directory of Open Access Journals (Sweden)
Joël Rosato
2017-09-01
Full Text Available We present an analysis of spectra observed in a corona discharge designed for the study of dielectrics in electrical engineering. The medium is a gas of helium and the discharge was performed at the vicinity of a tip electrode under high voltage. The shape of helium lines is dominated by the Stark broadening due to the plasma microfield. Using a computer simulation method, we examine the sensitivity of the He 492 nm line shape to the electron density. Our results indicate the possibility of a density diagnostic based on passive spectroscopy. The influence of collisional broadening due to interactions between the emitters and neutrals is discussed.
Directory of Open Access Journals (Sweden)
Nana Mulyana Arifjaya
2012-01-01
Full Text Available The concept of hydrological tank model was well described into four compartments (tanks. The first tank (tank A comprised of one vertical (qA0 and two lateral (qA1 and qA2 water flow components and tank B comprised of one vertical (qB0 and one lateral (qB1 water flow components. Tank C comprised of one vertical (qC0 and one lateral (qC1 water flow components, whereas tank D comprised of one lateral water flow component (qD1. These vertical water flows would also contribute to the depletion of water flow in the related tanks but would replenish tanks in the deeper layers. It was assumed that at all lateral water flow components would finally accumulate in one stream, summing-up of the lateral water flow, much or less, should be equal to the water discharge (Qo at specified time concerns. Tank A received precipitation (R and evapo-transpiration (ET which was its gradientof (R-ET over time would become the driving force for the changes of water stored in the soil profiles and thosewater flows leaving the soil layer. Thus tank model could describe th vertical and horizontal water flow withinthe watershed. The research site was Cisadane Upper Catchment, located at Pasir Buncir Village of CaringinSub-District within the Regency of Bogor in West Java Province. The elevations ranged 512 –2,235 m above sealevel, with a total drainage area of 1,811.5 ha and total length of main stream of 14,340.7 m. The land cover wasdominated by forest with a total of 1,044.6 ha (57.67%, upland agriculture with a total of 477.96 ha (26.38%,mixed garden with a total of 92.85 ha(5.13% and semitechnical irigated rice field with a total of 196.09 ha (10,8%. The soil was classified as hydraquent (96.6% and distropept (3.4%. Based on the calibration of tank model application in the study area, the resulting coefficient of determination (R2 was 0.72 with model efficiency (NSEof= 0.75, thus tank model could well illustrate the water flow distribution of
Pasko, V. P.
2011-12-01
It is well established by now that large charge transfers between cloud and ground in positive cloud-to-ground lightning discharges (+CGs) can lead to transient electric field enhancements at mesospheric and lower ionospheric altitudes. In these events the electric field can exceed the conventional breakdown field and lead to formation of transient luminous events referred to as sprites and sprite halos [e.g., Qin et al., JGR, 116, A06305, 2011, and references therein]. Stanley and Heavner [Proc. 12th International Conference on Atmospheric Electricity, Versailles, France, 2003] reported that the large and rapid charge transfer of +CGs producing sprites can also initiate upward positive leaders from tall structures. These authors also presented data analysis indicating that structures with >400 m height have a significantly enhanced probability of launching upward positive leaders that may culminate in a -CG return stroke to the structure. The effect can be understood by considering the field intensification at the top of the tall structure combined with fast application of the field preventing formation and shielding effects of ion corona [Brook et al., JGR, 66, 3967, 1961]. In the present work we utilize the most recent modeling approaches developed at Penn State [e.g., Riousset et al., JGR, 115, A00E10, 2010] to quantify the conditions leading to initiation of positive leaders from tall structures following sprite-producing +CGs. Experiments show that the streamer zone transforms into leader when voltage drop along the streamer zone exceeds 400 kV [e.g., Aleksandrov et al., J. Phys. D: Appl. Phys., 38, 1225, 2005]. For a formed leader half of the voltage drops in the streamer zone, and another half in free space ahead of the streamer zone [Bazelyan and Raizer, Lightning physics and lightning protection, p. 62, 2000]. In our analysis therefore we assume that minimum voltage at the tip of the tower should exceed 800 kV for sustainment of upward propagating leader
He, Yuchen; Satoshi, Uehara; Hidemasa, Takana; Hideya, Nishiyama
2016-09-01
A zero-dimensional model to simulate a nano-pulse-discharged bubble in water was developed. The model consists of gas and liquid phases corresponding to the inside and outside of the bubble, respectively. The diffusions of chemical species from the gas to the liquid phase through the bubble interface was also investigated. The initial gas is Ar, but includes a little H2O and O2 in the bubble. The time evolution of the OH concentration in the liquid phase was mainly investigated as an important species for water treatment. It was shown that OH was generated in the bubble and then diffused into the liquid. With the application of a continuous nano-pulse discharge, more OH radicals were generated as the frequency increased at a low voltage for a given power consumption. supported partially by Japan Society for the Promotion of Science (JSPS) KAKENHI (No. 26249015)
Liu, Fei-Xiang; Long, Ji-Dong; Zheng, Le; Dong, Pan; Li, Chen; Chen, Wei
2017-04-01
The pulsed vacuum arc discharge using a metal deuteride cathode is widely applied as a deuterium ion source, where the upper limit of the deuterium ion yield is largely determined by the deuterium releasing quantity (DRQ) from the cathode. This work aims to measure the DRQ at various discharge conditions, and meanwhile develop a simple thermoelectric model to evaluate the deuterium liberation from different sources, such as the crater vicinity during the arc power-on phase and the hot crater in the afterglow. The calculated DRQ are in accordance with the experimental results obtained by measuring the D2 pressure evolution in the early afterglow using a quadrupole mass spectrometer. Furthermore, the model reveals that at low arc current (<10 A), the DRQ orginates dominantly from the crater vicinity, leading to a low conversion efficiency of the released deuterium to ions and a high D:Ti elemental ratio in the released cathode vapor.
Interpretation on Partial Discharge of Typical Insulation Model Under Oscillating Impulse Voltage
Institute of Scientific and Technical Information of China (English)
SUN Zhenquan; ZHAO Xuefeng; LI Jisheng; LI Yanming
2012-01-01
The aim of this paper was to give an overview on partial discharges under oscillating impulse voltage.Three models（void in solid,needle-plate in air and oil） were presented,which describe the stochastic discharge process and represent internal discharges in solids and corona in air or silicon oil.Moreover,an air cored Rogowski coil and a sampling resistor for partial discharge（PD） measurement were developed and introduced in this paper.PD inception and extinction voltages（PDIV,PDEV） under single oscillating impulse voltage and AC voltage were investigated with different test samples.Experimental results firstly revealed that the PD inception voltage（PDIV） decreased with increasing applied voltage;secondly the PD inception voltage for three different insulating materials,showed an escalating trend with increasing frequency of the applied voltage.It was proven that the characteristics of PD under oscillating impulse voltage were identical to the features under AC voltage,which could be measured with the phase resolved partial discharge analysis（PRPDA） technique.Based on the reorganization and analysis of PDs under oscillating impulse voltage,the information about insulation defects was extracted from the measured data and used for estimating the risk of insulation failure of the equipment.
Monetary models and exchange rate determination: The Nigerian ...
African Journals Online (AJOL)
Monetary models and exchange rate determination: The Nigerian evidence. ... income levels and real interest rate differentials provide better forecasts of the naira-US dollar ... in this regard is that monetary policy should be positively predicted.
Temperature-dependent rate models of vascular cambium cell mortality
Matthew B. Dickinson; Edward A. Johnson
2004-01-01
We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of...
An equity-interest rate hybrid model with stochastic volatility and the interest rate smile
Grzelak, L.A.; Oosterlee, C.W.
2010-01-01
We define an equity-interest rate hybrid model in which the equity part is driven by the Heston stochastic volatility [Hes93], and the interest rate (IR) is generated by the displaced-diffusion stochastic volatility Libor Market Model [AA02]. We assume a non-zero correlation between the main
HIV Transmission Rate Modeling: A Primer, Review, and Extension
Pinkerton, Steven D.
2012-01-01
Several mathematical modeling studies based on the concept of “HIV transmission rates” have recently appeared in the literature. The transmission rate for a particular group of HIV-infected persons is defined as the mean number of secondary infections per member of the group per unit time. This article reviews the fundamental principles and mathematics of transmission rate models; explicates the relationship between these models, Bernoullian models of HIV transmission, and mathematical models...
Energy Technology Data Exchange (ETDEWEB)
Vagin, N. P.; Ionin, A. A., E-mail: aion@sci.lebedev.ru; Kochetov, I. V.; Napartovich, A. P.; Sinitsyn, D. V., E-mail: dsinit@sci.lebedev.ru; Yuryshev, N. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)
2017-03-15
The existing kinetic model describing self-sustained and electroionization discharges in mixtures enriched with singlet oxygen has been modified to calculate the characteristics of a flow RF discharge in molecular oxygen and its mixtures with helium. The simulations were performed in the gas plug-flow approximation, i.e., the evolution of the plasma components during their motion along the channel was represented as their evolution in time. The calculations were carried out for the O{sub 2}: He = 1: 0, 1: 1, 1: 2, and 1: 3 mixtures at an oxygen partial pressure of 7.5 Torr. It is shown that, under these conditions, volumetric gas heating in a discharge in pure molecular oxygen prevails over gas cooling via heat conduction even at an electrode temperature as low as ~100 K. When molecular oxygen is diluted with helium, the behavior of the gas temperature changes substantially: heat removal begins to prevail over volumetric gas heating, and the gas temperature at the outlet of the discharge zone drops to ~220–230 K at room gas temperature at the inlet, which is very important in the context of achieving the generation threshold in an electric-discharge oxygen−iodine laser based on a slab cryogenic RF discharge.
Oda, Akinori; Sugawara, Hirotake; Sakai, Yosuke; Akashi, Haruaki
2000-06-01
Xe dielectric barrier discharges at different gap lengths under applied pulse voltages with trapezoidal and sinusoidal waveforms were simulated using a self-consistent one-dimensional fluid model. In both waveforms, the light output power depended not only on the amplitude of voltage waveforms but also on the discharge gap length. At the narrower discharge gap, the light output efficiency was improved by increasing the time gradient of the applied voltage when the trapezoidal pulse is applied, and by decreasing the duty ratio in the sinusoidal case. In the present simulation, we adopted a fast numerical method for calculation of electric field introducing an exact expression of the discharge current.
Single crystal plasticity by modeling dislocation density rate behavior
Energy Technology Data Exchange (ETDEWEB)
Hansen, Benjamin L [Los Alamos National Laboratory; Bronkhorst, Curt [Los Alamos National Laboratory; Beyerlein, Irene [Los Alamos National Laboratory; Cerreta, E. K. [Los Alamos National Laboratory; Dennis-Koller, Darcie [Los Alamos National Laboratory
2010-12-23
The goal of this work is to formulate a constitutive model for the deformation of metals over a wide range of strain rates. Damage and failure of materials frequently occurs at a variety of deformation rates within the same sample. The present state of the art in single crystal constitutive models relies on thermally-activated models which are believed to become less reliable for problems exceeding strain rates of 10{sup 4} s{sup -1}. This talk presents work in which we extend the applicability of the single crystal model to the strain rate region where dislocation drag is believed to dominate. The elastic model includes effects from volumetric change and pressure sensitive moduli. The plastic model transitions from the low-rate thermally-activated regime to the high-rate drag dominated regime. The direct use of dislocation density as a state parameter gives a measurable physical mechanism to strain hardening. Dislocation densities are separated according to type and given a systematic set of interactions rates adaptable by type. The form of the constitutive model is motivated by previously published dislocation dynamics work which articulated important behaviors unique to high-rate response in fcc systems. The proposed material model incorporates thermal coupling. The hardening model tracks the varying dislocation population with respect to each slip plane and computes the slip resistance based on those values. Comparisons can be made between the responses of single crystals and polycrystals at a variety of strain rates. The material model is fit to copper.
Fedorov, E.; Mazur, N.; Pilipenko, V.; Baddeley, L.
2016-11-01
The ionospheric Alfvén resonator (IAR) and fast magnetosonic (FMS) waveguide, which can trap the electromagnetic wave energy in the range from fractions of Hz to several Hz, are characteristic features of the upper ionosphere. Their role in the electromagnetic impulsive coupling between atmospheric discharge processes and the ionosphere can be elucidated with a proper model. The presented model is based on numerical solution of coupled wave equations for electromagnetic modes in the ionosphere and atmosphere in a realistic ionosphere modeled with the use of IRI (International Reference Ionosphere) vertical profiles. The geomagnetic field is supposed to be nearly vertical, so the model can be formally applied to high latitudes, though the main features of ground ULF structure will be qualitatively similar at middle latitudes as well. The modeling shows that during the lightning discharge a coupled wave system comprising IAR and MHD waveguide is excited. Using the model, the spatial structure, frequency spectra, and polarization parameters have been calculated at various distances from a vertical dipole. In the lightning proximity (about several hundred kilometer) only the lowest IAR harmonics are revealed in the radial magnetic component spectra. At distances >800 km the multiband spectral structure is formed predominantly by harmonics of FMS waveguide modes. The model predictions do not contradict the results of search coil magnetometer observations on Svalbard; however, the model validation demands more dedicated experimental studies.
Li, Yuan; Ryu, Dongryeol; Western, Andrew W.; Wang, Q. J.
2015-05-01
Real-time discharge observations can be assimilated into flood models to improve forecast accuracy; however, the presence of time lags in the routing process and a lack of methods to quantitatively represent different sources of uncertainties challenge the implementation of data assimilation techniques for operational flood forecasting. To address these issues, an integrated error parameter estimation and lag-aware data assimilation (IEELA) scheme was recently developed for a lumped model. The scheme combines an ensemble-based maximum a posteriori (MAP) error estimation approach with a lag-aware ensemble Kalman smoother (EnKS). In this study, the IEELA scheme is extended to a semidistributed model to provide for more general application in flood forecasting by including spatial and temporal correlations in model uncertainties between subcatchments. The result reveals that using a semidistributed model leads to more accurate forecasts than a lumped model in an open-loop scenario. The IEELA scheme improves the forecast accuracy significantly in both lumped and semidistributed models, and the superiority of the semidistributed model remains in the data assimilation scenario. However, the improvements resulting from IEELA are confined to the outlet of the catchment where the discharge observations are assimilated. Forecasts at "ungauged" internal locations are not improved, and in some instances, even become less accurate.
Rye, H.; Reed, M.; Frost, T.K.; Smit, M.G.D.; Durgut, S.
2008-01-01
Drilling discharges are complex mixtures of chemical components and particles which might lead to toxic and nontoxic stress in the environment. In order to be able to evaluate the potential environmental consequences of such discharges in the water column and in sediments, a numerical model was deve
Directory of Open Access Journals (Sweden)
Yan-jie Ni
2016-04-01
Full Text Available A 30 mm electrothermal-chemical (ETC gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates (EGGR of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient (dp/dt is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW−1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley's modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient (dp/dt and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.
Institute of Scientific and Technical Information of China (English)
Yan-jie NI; Yong JIN; Gang WAN; Chun-xia YANG; Hai-yuan LI; Bao-ming LI
2016-01-01
A 30 mm electrothermal-chemical (ETC) gun experimental system is employed to research the burning rate characteristics of 4/7 high-nitrogen solid propellant. Enhanced gas generation rates (EGGR) of propellants during and after electrical discharges are verified in the experiments. A modified 0D internal ballistic model is established to simulate the ETC launch. According to the measured pressure and electrical parameters, a transient burning rate law including the influence of EGGR coefficient by electric power and pressure gradient (dp/dt) is added into the model. The EGGR coefficient of 4/7 high-nitrogen solid propellant is equal to 0.005 MW−1. Both simulated breech pressure and projectile muzzle velocity accord with the experimental results well. Compared with Woodley’s modified burning rate law, the breech pressure curves acquired by the transient burning rate law are more consistent with test results. Based on the parameters calculated in the model, the relationship among propellant burning rate, pressure gradient (dp/dt) and electric power is analyzed. Depending on the transient burning rate law and experimental data, the burning of solid propellant under the condition of plasma is described more accurately.
Rate equation modelling and investigation of quantum cascade detector characteristics
Saha, Sumit; Kumar, Jitendra
2016-10-01
A simple precise transport model has been proposed using rate equation approach for the characterization of a quantum cascade detector. The resonant tunneling transport is incorporated in the rate equation model through a resonant tunneling current density term. All the major scattering processes are included in the rate equation model. The effect of temperature on the quantum cascade detector characteristics has been examined considering the temperature dependent band parameters and the carrier scattering processes. Incorporation of the resonant tunneling process in the rate equation model improves the detector performance appreciably and reprod