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Empirical Equation (empirical + equation)
Selected AbstractsEmpirical Equation for Calculating the Density of Oxide GlassesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Seiji Inaba The density of oxide glass including silicate, borate, phosphate, tellurite, and germanate glasses were measured using the Archimedes method. On the assumption that the ionic packing ratio is approximately a constant independent of chemical composition, an empirical equation for estimating the density from chemical composition was proposed. The calculated values are in reasonable agreement with the corresponding measured ones. [source] Geomorphic and sedimentological signature of a two-phase outburst ,ood from moraine-dammed Queen Bess Lake, British Columbia, CanadaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2005Jane A. Kershaw Abstract On 12 August 1997, the lower part of Diadem Glacier in the southern Coast Mountains of British Columbia fell into Queen Bess Lake and produced a train of large waves. The waves overtopped the broad end moraine at the east end of the lake and ,ooded the valley of the west fork of Nostetuko River. The displacement waves also incised the out,ow channel across the moraine. Stratigraphic and sedimentologic evidence supports the conclusion that the ,ood had two phases, one related to wave overtopping and a second to breach formation. Empirical equations were used to calculate the peak discharge of the ,ood at various points along the west fork of the Nostetuko valley and to describe the attenuation of the ,ood wave. The velocity of the ,ood was also calculated to determine the time it took for the ,ood to reach the main fork of Nostetuko River. The highest peak discharges were achieved in the upper reach of the valley during the displacement phase of the ,ood. Peak discharge declined rapidly just below the moraine dam, with little change thereafter for approximately 7 km. Empirical formulae and boulder measurements indicate a rise in peak discharge in the lower part of the west fork valley. We suggest that ,ow in the upper part of the valley records the passage of two separate ,ood peaks and that the rise in discharge in the lower part of the valley is due to amalgamation of the wave and breach peaks. Hydraulic ponding in con,ned reaches of the valley extended the duration of the ,ood. In addition, erosion of vegetation and sediment in the channel and valley sides may also have exerted an in,uence on the duration and nature of ,ooding. Sediments were deposited both upstream and downstream of channel constrictions and on a large fan extending out into the trunk Nostetuko River valley. This study extends our understanding of the variety and complexity of outburst ,oods from naturally dammed lakes. It also shows that simple empirical and other models for estimating peak discharges of outburst ,oods are likely to yield erroneous results. Copyright © 2005 John Wiley & Sons, Ltd. [source] TWO-PHASE MODELING AND THE QUALITY OF SOYBEAN SEEDS DRIED IN A COUNTER-CURRENT MOVING BED DRIERJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2004A.F. LACERDA ABSTRACT The purpose of the present work is to study the simultaneous heat and mass transfer between air and soybean seeds in a countercurrent moving bed dryer, based on the application of a two-phase model to the drying process. The numerical solution of the model is obtained by using a computational code based on backwards differential formulae. The experimental data of air humidity and temperature and of seed moisture content and temperature at the dryer outlet are compared to the simulated values, showing a good agreement. This work also analyzes the effect of the main process variables (drying air temperature, air relative humidity, air velocity and solids flow rate) on the soybean seeds quality during drying. Empirical equations fitted to the experimental data are proposed for predicting the soybean seed quality (germination, vigor and fissures) as a function of the investigated variables. [source] A multivariate logistic regression equation to screen for dysglycaemia: development and validationDIABETIC MEDICINE, Issue 5 2005B. P. Tabaei Abstract Aims To develop and validate an empirical equation to screen for dysglycaemia [impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and undiagnosed diabetes]. Methods A predictive equation was developed using multiple logistic regression analysis and data collected from 1032 Egyptian subjects with no history of diabetes. The equation incorporated age, sex, body mass index (BMI), post-prandial time (self-reported number of hours since last food or drink other than water), systolic blood pressure, high-density lipoprotein (HDL) cholesterol and random capillary plasma glucose as independent covariates for prediction of dysglycaemia based on fasting plasma glucose (FPG) , 6.1 mmol/l and/or plasma glucose 2 h after a 75-g oral glucose load (2-h PG) , 7.8 mmol/l. The equation was validated using a cross-validation procedure. Its performance was also compared with static plasma glucose cut-points for dysglycaemia screening. Results The predictive equation was calculated with the following logistic regression parameters: P = 1 + 1/(1 + e,X) = where X = ,8.3390 + 0.0214 (age in years) + 0.6764 (if female) + 0.0335 (BMI in kg/m2) + 0.0934 (post-prandial time in hours) + 0.0141 (systolic blood pressure in mmHg) , 0.0110 (HDL in mmol/l) + 0.0243 (random capillary plasma glucose in mmol/l). The cut-point for the prediction of dysglycaemia was defined as a probability , 0.38. The equation's sensitivity was 55%, specificity 90% and positive predictive value (PPV) 65%. When applied to a new sample, the equation's sensitivity was 53%, specificity 89% and PPV 63%. Conclusions This multivariate logistic equation improves on currently recommended methods of screening for dysglycaemia and can be easily implemented in a clinical setting using readily available clinical and non-fasting laboratory data and an inexpensive hand-held programmable calculator. [source] Upper flammability limits of some organosilicon compoundsFIRE AND MATERIALS, Issue 6 2004Fu-Yu Hshieh Abstract This paper reports the upper flammability limits of 26 organosilicon compounds commonly used in the silicone industry and investigates the correlation between the upper flammability limit and the net heat of combustion. An empirical equation has been developed to predict the upper flammability limit of organosilicon compounds using the net heat of combustion. Copyright © 2004 John Wiley & Sons, Ltd. [source] Prediction of vortex penetration depth at thermal stratification by cavity flow in a branch pipe with closed end (effect of heat radiation condition on temperature fluctuations)HEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2007Kouji Shiina Abstract In a branch pipe with one closed end, the cavity flow penetrates into the branch pipe from the main loop and a thermal boundary layer occurs because the cavity flow is a hot fluid, but heat removal causes a colder fluid in the branch pipe. This thermal stratification may affect the structural integrity. Therefore, a pipe design standard to suppress thermal fatigue should be established. The pipe design standard consists of the maximum penetration depth Lsv and the minimum penetration depth Lsh. In order to establish an evaluation method for Lsh, a visualization test and a temperature fluctuation test were carried out. A theoretical formula for thermal stratification was introduced from the heat balance model. Then the model was used to obtain an empirical equation from the map of fluid temperature fluctuation. This method can predict the vortex penetration depth by cavity flow in horizontal branch pipes. © 2006 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(1):38,55, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20135 [source] Water fluxes at a fluctuating water table and groundwater contributions to wheat water use in the lower Yellow River flood plain, ChinaHYDROLOGICAL PROCESSES, Issue 6 2007Jianfeng Yang Abstract Capillary upflow from and deep percolation to a water table may be important in crop water supply in irrigated areas of the lower Yellow River flood plain, north China. These fluxes at the water table and the variations of the capillary upflow in relation to crop evapotranspiration need to be investigated to quantify the effect of a water table on soil water balance and to improve agricultural water management. A large weighing lysimeter was used to determine daily crop evapotranspiration, daily capillary upflow from and daily percolation to a fluctuating water table during a rotation period with wheat growing in a dry season and maize in a rainy season. The water table depth varied in the range 0·7,2·3 m during the maize growth period and 1·6,2·4 m during the wheat growth period. Experimental results showed that the capillary upflow and the percolation were significant components of the soil water balance. Three distinctly different phases for the water fluxes at the water table were observed through the rotation period: water downward period, the period of no or small water fluxes, and water upward period. It implied that the temporal pattern of these water fluxes at the water table was intimately associated with the temporal distribution of rainfall through the rotation period. An empirical equation was determined to estimate the capillary upflow in relation to wheat evapotranspiration and root zone soil water content for local irrigation scheduling. Coupled with the FAO-Penman,Monteith equation, the equation offers a fast and low cost solution to assess the effect of capillary upflow from a water table on wheat water use. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effects of quasi-nanogel particles on the rheological and mechanical properties of natural rubber: A new insightJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Suman Mitra Abstract The influence of sulfur-crosslinked, quasi-nanosized gels on the rheological and mechanical properties of raw natural rubber (NR) was investigated. Latex gels with different crosslink densities were prepared through the variation of the sulfur-to-accelerator ratio. These gels were characterized by dynamic light scattering, solvent swelling, and mechanical properties. The gels were mixed with raw NR latex at concentrations of 2, 4, 8, and 16 phr, and their effect on the rheological properties of NR was studied by Monsanto processability tester. The presence of gel in raw NR reduced the apparent shear viscosity and die swell considerably. Initially, the viscosity decreased up to a 8 phr gel loading and then increased with an increase in the gel loading. However, the change in the viscosity was related to the crosslink density of the gels. A new empirical equation relating the viscosity, volume fraction of the gels, and crosslink density was proposed. The die swell of gel-filled raw NR was at least 10% lower than that of unfilled raw NR and decreased with an increase in the gel loading. The effect of the gels on the die swell properties was explained through the calculation of the principal normal stress difference of gel-filled NR systems. Scanning electron photomicrographs of the extrudates revealed much better surface smoothness for the gel-filled virgin rubber systems than for the unfilled rubber. The addition of the gels to raw NR increased the modulus and tensile strength, whereas the elongation at break decreased. The effect of the gels on the dynamic mechanical properties of NR was also investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Microbial Inactivation Kinetics during High-Pressure Carbon Dioxide Treatment: Nonlinear Model for the Combined Effect of Temperature and Pressure in Apple JuiceJOURNAL OF FOOD SCIENCE, Issue 8 2008G. Ferrentino ABSTRACT:, Isobaric and isothermal semi-logarithmic survival curves of natural microflora in apple juice treated with high-pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 °C temperatures were fitted with a nonlinear equation to find the values of the coefficient b(P ), b(T ), n(P ), and n(T ). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement (R2 > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: . The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 °C, 13 MPa and 35 and 60 °C, 16 MPa and 35 °C, the model provided log10 reduction residual values (observed value , fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels. [source] Internal energy distribution of peptides in electrospray ionization : ESI and collision-induced dissociation spectra calculationJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 4 2008Alireza Pak Abstract The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom ,DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta -Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (Vc) were linearly correlated with the mean internal energy values ( Equation of state for the viscosity of Lennard-Jones fluids,AICHE JOURNAL, Issue 2 2006Leslie V. Woodcock Abstract A one-parameter model constitutive transport equation for the viscosity of the Lennard-Jones (L-J) fluid that is accurate for all equilibrium states of liquid and gas is proposed: The form of this equation is based upon the soft-sphere scaling laws for the residual density-dependent viscosity discovered originally by Ashurst and Hoover and uses their empirical coefficient (CAH). Enskog's density-independent limit theoretical term (,0) is included to reproduce the viscosity in the limit of zero density accurately. Remaining discrepancies at low temperatures, for both gas and liquid densities, are largely removed when the linear-density Rainwater-Friend coefficient is added. The equation is comparable in accuracy to the 24-parameter empirical equation of state proposed by Rowley and Painter. Comparison with this correlation and previous MD results reveals a discrepancy near the triple point. To test the equation, new MD data for three fluid states are reported. Here, the viscosity is computed from time correlation functions resolved into the single-particle auto- and cross-correlation terms. It is found that, at high density (,* > 0.8), the cross,correlations extend beyond 7, (molecule diameters) and oscillate in sign. This explains the wide scatter of previous MD viscosities for small L-J systems. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source] Empirical Equation for Calculating the Density of Oxide GlassesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Seiji Inaba The density of oxide glass including silicate, borate, phosphate, tellurite, and germanate glasses were measured using the Archimedes method. On the assumption that the ionic packing ratio is approximately a constant independent of chemical composition, an empirical equation for estimating the density from chemical composition was proposed. The calculated values are in reasonable agreement with the corresponding measured ones. [source] Density, Surface Tension, and Viscosity of PbO-B2O3 -SiO2 Glass MeltsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2004Shigeru Fujino The density, surface tension, and viscosity of the melts from the PbO-B2O3 -SiO2 system have been measured at temperatures in the range 1073,1473 K. The effect of composition on these properties was also investigated. The density of the melt was found to increase linearly with increasing PbO content. Molar volume was derived from the density data, and its deviation from the additivity of partial molar volumes was calculated. These deviations in molar volume from those obtained from additivity rules have been used along with the ratio of various coordination numbers of boron (as reported by Bray) to discuss the structure of the melts. The surface tension was found to decrease with decreasing SiO2/B2O3 ratio, and to increase in the range of the PbO content between 30 and 60 mol%, showing a maximum at ,60 mol% PbO, and then decreased with further additions. This result suggested that the surface tension would be affected primarily by the B2O3 content in the range of the PbO content between 30,60 mol%, and mainly by the PbO content in the range of the PbO content >60 mol%, respectively. The viscosity of the melt was found to decrease linearly with increasing PbO content. The results obtained indicate that the increase in viscosity with B2O3 was half that of SiO2 (on a molar basis), and an empirical equation has been proposed for the viscosity as a function of mole fraction. [source] Tropical storm impact in Central AmericaMETEOROLOGICAL APPLICATIONS, Issue 1 2006Sabino Palmieri Abstract In this study of tropical storm impacts in Central America, the relationship between physical variables (available in ,real time') and damage is explored, and a simple tool for early approximate evaluation of the impact is developed. Land track and energy dissipation appear as the most interesting parameters that modulate the hurricane impact. Because of the difficulty of attaching a monetary estimate to the damage caused in a large number of cases (as is required in a statistical approach), an ,Impact Index' based on the logarithm of casualties is introduced. Thereafter, within a subset of events in which damage in monetary terms is known, a rough link between damage and the Impact Index is derived. Shortly after a new event, as soon as land track and energy dissipation are known, either by means of an empirical equation or using a contour graph, the Impact Index may be determined. Another empirical equation allows a rough estimate of damage in monetary units, but because this estimate is based on a limited number of cases, it must be treated with caution. The methodology is tested for a small set of independent cases. Vulnerability to tropical cyclones depends not only on natural factors but also on sociopolitical conditions. A coupled sociological and environmental approach is believed to be the best way to improve the early impact estimate methodology. Copyright © 2006 Royal Meteorological Society. [source] The effect on energy expenditure of walking on gradients or carrying burdensAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 4 2010Patricia Ann Kramer The effectiveness of people walking while carrying burdens and/or on gradients has been of interest to anthropologists for some time. No empirical equation exists, however, to assess the energetic expenditure of individuals traveling downhill with burdens and whether or not all people increase their energetic expenditure over unburdened level travel when carrying relatively light burdens (<20% of body mass) remains unclear. To begin to rectify this lacunae, gait parameters, physiological variables, and the energetic expenditure of 11 adults were assessed as they walked with burdens of 5 and 10 kg on a level treadmill and while they walked unburdened on gradients ±8 and ±16%. These data were then compared to predictive equations and data available from the literature. Velocity and body mass were combined with gradient and burden mass, where appropriate, as independent covariates to create predictive equations, which explained >80% of the variation in energetic expenditure. These new equations are appropriate for predicting energetic expenditure in people carrying burdens of <20% of total body mass or walking up and downhill at gradients of <20%. Am. J. Hum. Biol. 2010. © 2010 Wiley-Liss, Inc. [source] Sub-5-fs Real-time Spectroscopy of Transition States in Bacteriorhodopsin During Retinal Isomerization,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2007Takayoshi Kobayashi By using a sub-5-fs visible laser pulse, we have made the first observation of the vibrational spectra of the transition state during trans-cis isomerization in the retinal chromophore of bacteriorhodopsin (bRS68). No instant isomerization of the retinal occurs in spite of electron promotion from the bonding ,-orbital to the anti-bonding ,*-orbital. The difference between the in-plane and out-of-plane vibrational frequencies (about 1150,1250 and 900,1000 cm,1, respectively) is reduced during the first time period. The vibrational spectra after this period became very broad and weak and are ascribed to a "silent state." The silent state lasts for 700,900 fs until the chromophore isomerizes to the cis -C13=C14 conformation. The frequency of the C=C stretching mode was modulated by the torsion mode of the C13=C14 double bond with a period of 200 fs. The modulation was clearly observed for four to five periods. Using the empirical equation for the relation between bond length and stretching frequency, we determined the transitional C=C bond length with about 0.01 Å accuracy during the torsion motion around the double bond with 1-fs time resolution. [source] Migration of Plasticizer between Bonded Propellant InterfacesPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2003Levi Gottlieb Abstract Plasticizer migration across bonded propellant interfaces during cure has been shown to have a measurable effect on propellant properties compared to each propellant by itself. This shows that the curing period is significant to the migration phenomenon. The plasticizer migration has been shown to have a direct influence on tensile strength for short aging periods up to the point the plasticizer reaches equilibrium. The tensile data for short aging periods have been shown to follow an empirical equation connecting the physical characteristics of plasticizer migration with increasing propellant tensile strength. The diffusion coefficient has been evaluated on the basis of this relation from a plot of , versus t1/2 and was in good agreement with the diffusion coefficient from the plasticizer content data. [source] Evaluation of the SWEEP model during high winds on the Columbia Plateau ,EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2009G. Feng Abstract A standalone version of the Wind Erosion Prediction System (WEPS) erosion submodel, the Single-event Wind Erosion Evaluation Program (SWEEP), was released in 2007. A limited number of studies exist that have evaluated SWEEP in simulating soil loss subject to different tillage systems under high winds. The objective of this study was to test SWEEP under contrasting tillage systems employed during the summer fallow phase of a winter wheat,summer fallow rotation within eastern Washington. Soil and PM10 (particulate matter ,10 µm in diameter) loss and soil and crop residue characteristics were measured in adjacent fields managed using conventional and undercutter tillage during summer fallow in 2005 and 2006. While differences in soil surface conditions resulted in measured differences in soil and PM10 loss between the tillage treatments, SWEEP failed to simulate any difference in soil or PM10 loss between conventional and undercutter tillage. In fact, the model simulated zero erosion for all high wind events observed over the two years. The reason for the lack of simulated erosion is complex owing to the number of parameters and interaction of these parameters on erosion processes. A possible reason might be overestimation of the threshold friction velocity in SWEEP since friction velocity must exceed the threshold to initiate erosion. Although many input parameters are involved in the estimation of threshold velocity, internal empirical coefficients and equations may affect the simulation. Calibration methods might be useful in adjusting the internal coefficients and empirical equations. Additionally, the lack of uncertainty analysis is an important gap in providing reliable output from this model. Published in 2009 by John Wiley & Sons, Ltd. [source] Spectral analysis and design approach for high force-to-volume extrusion damper-based structural energy dissipationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2008Geoffrey W. Rodgers Abstract High force-to-volume extrusion damping devices can offer significant energy dissipation directly in structural connections and significantly reduce seismic response. Realistic force levels up to 400,kN have been obtained experimentally validating this overall concept. This paper develops spectral-based design equations for their application. Response spectra analysis for multiple, probabilistically scaled earthquake suites are used to delineate the response reductions due to added extrusion damping. Representative statistics and damping reduction factors are utilized to characterize the modified response in a form suitable for current performance-based design methods. Multiple equation regression analysis is used to characterize reduction factors in the constant acceleration, constant velocity, and constant displacement regions of the response spectra. With peak device forces of 10% of structural weight, peak damping reduction factors in the constant displacement region of the spectra are approximately 6.5,×, 4.0,×, and 2.8,× for the low, medium, and high suites, respectively. At T,=,1,s, these values are approximately 3.6,×, 1.8,×, and 1.4,×, respectively. The maximum systematic bias introduced by using empirical equations to approximate damping reduction factors in design analyses is within the range of +10 to ,20%. The seismic demand spectrum approach is shown to be conservative across a majority of the spectrum, except for large added damping between T,=,0.8 and 3.5,s, where it slightly underestimates the demand up to a maximum of approximately 10%. Overall, the analysis shows that these devices have significant potential to reduce seismic response and damage at validated prototype device force levels. Copyright © 2007 John Wiley & Sons, Ltd. [source] Predicted heats of combustion of some important organosilicon intermediatesFIRE AND MATERIALS, Issue 1 2003Fu-Yu Hshieh Abstract This short communication presents the predicted heats of combustion of 308 organosilicon intermediates. The net and gross heats of combustion were predicted using two previously developed empirical equations. These intermediates cover most of the important organosilicon compounds that are manufactured or used in the silicone industry. Copyright © 2003 John Wiley & Sons, Ltd. [source] A new saturated/unsaturated model for stormwater infiltration systemsHYDROLOGICAL PROCESSES, Issue 25 2008Dale Browne Abstract Infiltration systems are widely used as an effective urban stormwater control measure. Most design methods and models roughly approximate the complex physical flow processes in these systems using empirical equations and fixed infiltration rates to calculate emptying times from full. Sophisticated variably saturated flow models are available, but rarely applied owing to their complexity. This paper describes the development and testing of an integrated one-dimensional model of flow through the porous storage of a typical infiltration system and surrounding soils. The model accounts for the depth in the storage, surrounding soil moisture conditions and the interaction between the storage and surrounding soil. It is a front-tracking model that innovatively combines a soil-moisture-based solution of Richard's equation for unsaturated flow with piston flow through a saturated zone as well as a reservoir equation for flow through a porous storage. This allows the use of a simple non-iterative numerical solution that can handle ponded infiltration into dry soils. The model is more rigorous than approximate stormwater infiltration system models and could therefore be valuable in everyday practice. A range of test cases commonly used to test soil water flow models for infiltration in unsaturated conditions, drainage from saturation and infiltration under ponded conditions were used to test the model along with an experiment with variable depth in a porous storage over saturated conditions. Results show that the model produces a good fit to the observed data, analytical solutions and Hydrus. Copyright © 2008 John Wiley & Sons, Ltd. [source] A BTOP model to extend TOPMODEL for distributed hydrological simulation of large basinsHYDROLOGICAL PROCESSES, Issue 17 2008Kuniyoshi Takeuchi Abstract Topography is a dominant factor in hillslope hydrology. TOPMODEL, which uses a topographical index derived from a simplified steady state assumption of mass balance and empirical equations of motion over a hillslope, has many advantages in this respect. Its use has been demonstrated in many small basins (catchment areas of the order of 2,500 km2) but not in large basins (catchment areas of the order of 10 000,100 000 km2). The objective of this paper is to introduce the Block-wise TOPMODEL (BTOP) as an extension of the TOPMODEL concept in a grid based framework for distributed hydrological simulation of large river basins. This extension was made by redefining the topographical index by using an effective contributing area af(a) (0,f(a),1) per unit grid cell area instead of the upstream catchment area per unit contour length and introducing a concept of mean groundwater travel distance. Further the transmissivity parameter T0 was replaced by a groundwater dischargeability D which can provide a link between hill slope hydrology and macro hydrology. The BTOP model uses all the original TOPMODEL equations in their basic form. The BTOP model has been used as the core hydrological module of an integrated distributed hydrological model YHyM with advanced modules of precipitation, evapotranspiration, flow routing etc. Although the model has been successfully applied to many catchments around the world since 1999, there has not been a comprehensive theoretical basis presented in such applications. In this paper, an attempt is made to address this issue highlighted with an example application using the Mekong basin. Copyright © 2007 John Wiley & Sons, Ltd. [source] Seasonal changes in radiation and evaporation implied from the diurnal distribution of rainfall in the Lower MekongHYDROLOGICAL PROCESSES, Issue 9 2008Kumiko Tsujimoto Abstract Solar radiation is an important input to many empirical equations for estimating evaporation, which in turn plays an important role in the hydrologic cycle in the Lower Mekong River Basin due to the high evaporation potential of the tropical monsoon climate. Few proper meteorological data exist for the Lower Mekong River Basin, however, and the region's meteorological conditions, including seasonal variation in radiation and evaporation, have not been clarified. In this study, ground-based hourly hydrometeorological data were collected at three observation stations located in different land-use types (urban district, paddy area, and lake) in the Lower Mekong River Basin. These data were analysed to investigate the seasonal variation in radiation and evaporation related to the diurnal distribution of rainfall. Contrary to common expectations, our results showed that rainy and dry seasons had nearly the same amount of solar radiation in the Lower Mekong River Basin because (1) rainy seasons had a relatively larger amount of extraterrestrial radiation; (2) no rain fell on nearly half of the days during rainy seasons; and (3) the amount of solar radiation on rainy days reached 88% of that on non-rainy days. The third factor was attributed to the high frequency of evening rainfall. Furthermore, this rainfall,radiation relationship meant that rainy seasons had a large amount of net radiation due to the low reduction ratio of solar radiation and an increase in long-wave incoming radiation. Accordingly, rainy seasons had a high evaporation potential. Moreover, for the rain-fed rice paddies that prevail in this region, sufficient radiation during the rainy season would be a great advantage for rice growing. Copyright © 2008 John Wiley & Sons, Ltd. [source] Depth-integrated, non-hydrostatic model for wave breaking and run-upINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2009Yoshiki Yamazaki Abstract This paper describes the formulation, verification, and validation of a depth-integrated, non-hydrostatic model with a semi-implicit, finite difference scheme. The formulation builds on the nonlinear shallow-water equations and utilizes a non-hydrostatic pressure term to describe weakly dispersive waves. A momentum-conserved advection scheme enables modeling of breaking waves without the aid of analytical solutions for bore approximation or empirical equations for energy dissipation. An upwind scheme extrapolates the free-surface elevation instead of the flow depth to provide the flux in the momentum and continuity equations. This greatly improves the model stability, which is essential for computation of energetic breaking waves and run-up. The computed results show very good agreement with laboratory data for wave propagation, transformation, breaking, and run-up. Since the numerical scheme to the momentum and continuity equations remains explicit, the implicit non-hydrostatic solution is directly applicable to existing nonlinear shallow-water models. Copyright © 2008 John Wiley & Sons, Ltd. [source] Calculation of the Detonation Velocities and Detonation Pressures of Dinitrobiuret (DNB) and Diaminotetrazolium Nitrate (HDAT-NO3)PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 1 2004Janna Geith Abstract The enthalpies of combustion (,combH) of dinitrobiuret (DNB) and diaminotetrazolium nitrate (HDAT-NO3) were determined experimentally using oxygen bomb calorimetry: ,combH(DNB)=5195±200,kJ kg,1, ,combH(HDAT-NO3)=7900±300,kJ kg,1. The standard enthalpies of formation (,fH°) of DNB and HDAT-NO3 were obtained on the basis of quantum chemical computations at the electron-correlated ab initio MP2 (second order Møller-Plesset perturbation theory) level of theory using a correlation consistent double-zeta basis set (cc-pVTZ): ,fH°(DNB)=,353,kJ mol,1, ,1,829,kJ kg,1; ,fH°(HDAT-NO3)=+254,kJ mol,1, +1,558,kJ kg,1. The detonation velocities (D) and detonation pressures (P) of DNB and HDAT-NO3 were calculated using the empirical equations by Kamlet and Jacobs: D(DNB)=8.66,mm,,s,1, P(DNB)=33.9,GPa, D(HDAT-NO3)=8.77,mm,,s,1, P(HDAT-NO3)=33.3,GPa. [source] Hydrodynamics and mass transfer in a pulsed packed columnTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2000Yu Jie Abstract The hydrodynamics and mass transfer characteristics of a pulsed packed column (PPC) filled with a stainless steel super mini ring (SMR), ceramic and stainless steel Raschig rings have been studied using a 30% tributyl phosphate-kerosene (dispersed phase)/acetic acid/water (continuous phase) system. Experiments were performed in a 100 mm internal diameter column with 1.0 m height of packing. The mass transfer and axial mixing parameters were estimated simultaneously from the measured concentration profiles of two-phase based on the backflow model. It was found that pulsation has great influence on hydrodynamics and mass transfer characteristics of PPC with the SMR. Hoxp and Hox decrease significantly with pulsation, whereas flooding velocity decreases only slightly. Comparison among the three types of packing showed that the SMR has superior characteristics both in terms of capacity and mass transfer efficiency. The influence of mass transfer on characteristics of PPC was also studied. New empirical equations of characteristic velocity, Hoxand Hoxd were proposed and good agreement between calculated and experimental data was obtained. Les caractéristiques de l'hydrodynamique et du transfert de matiére dans une colonne pulsée garni (PPC) contenant des super mini-anneaux (SMR) d'acier inoxydable et des anneaux de Raschig de céramique et d'acier inoxydable (s.s.) ont été étudiées à l'aide du système 30% de phosphate de tributyl-kérosène (phase dispersée)/acide acétique/eau (phase continue). On a mené des expériences dans une colonne de 100 mm de diamètre intérieur avec une hauteur de garnissage de 1.0 m. Les paramètres de transfert de matière et de mélange axial ont été estimés simultanément à partir des profils de concentration mesurés de deux phases d'après le modèle de reflux. On a trouvé que la pulsation avait une grande influence sur les caractéristiques de l'hydrodynamique et de transfert de matière de la colonne PPC avec le SMR. Hoxp et Hox diminuent de maniére significative avec la pulsation, tandis que la vitesse d'engorgement ne diminue que Iégèrement. Une comparaison entre les trois types de garnissage montre que le SMR possède des caractéristiques supérieures à la fois en termes de capacité et d'efficacité du transfert de matière. L'influence du transfert de matière sur les caractéristiques de la colonne PPC a également été étudiée. De nouvelles équations empiriques de la vitesse caractéristique, Hox et Hoxd, sont proposées et un bon accord est obtenu entre les données calculées et les données expérhentales. [source] Complex permittivity of sodium chloride solutions at microwave frequenciesBIOELECTROMAGNETICS, Issue 4 2007A. Peyman Abstract The complex permittivity of aqueous solutions at 20,°C has been measured at concentrations between 0.001 and 5,mol/L and over a frequency range 0.13,20,GHz. The results were combined with literature values to derive empirical equations to predict the dielectric behavior of sodium chloride solutions between 0 and 5,mol/L and 5°C,35,°C. Bioelectromagnetics 28:264,274, 2007. © 2007 Wiley-Liss, Inc. [source] Numerical Study on Bubble Formation of a Gas-Liquid Flow in a T-Junction MicrochannelCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2009L. Dai Abstract Bubble emergence in a gas-liquid flow in a T-junction microchannel of 100,,m diameter, operated under a squeezing regime, was simulated with the computational fluid dynamics method. In general, bubble formation in channels includes three stages: expansion, collapse and pinching off. After analyzing and comparing quantitatively the three forces of pressure, surface tension and shear stress acting on the gas thread in the whole process, their effects in the different stages were identified. The collapse stage was the most important for bubble formation and was investigated in detail. It was found that the collapse process was mostly influenced by the liquid superficial velocity, and the rate and time of collapse can be correlated with empirical equations including the liquid superficial velocity, the capillary number and the Reynolds number. [source] The Influence of a Constructional Solution of the Crystallizer with a Jet Pump on Crystal AttritionCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2005A. Matynia Abstract The research results concerning attrition of sodium chloride crystals in two types of jet pump crystallizers are presented. It was demonstrated that in the crystallizer with a jet pump crystals undergo considerable smaller attrition compared to the one equipped with agitator and draft tube (circulation profile). The influence of the initial mean crystal size, crystal volumetric concentration in the suspension and the residence time of the suspension in the crystallizer on the degree of solid phase destruction was determined and quantified in the form of empirical equations. The DTM MSCPR construction demonstrates the least destruction capabilities. [source] The Potential of Surfactant Modified Supercritical Fluids for Dissolving Polar DyesCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2004U. Lewin-Kretzschmar Abstract The solubility of different polar dyes in supercritical carbon dioxide and ethane (scCO2 and scC2H6), both modified and unmodified with various surfactants and solvents was determined at temperatures from 323,373 K and in pressure range from 10,45 MPa. The solubility data were correlated with some empirical equations. Furthermore, dyeing experiments with wool and cotton dyes were conducted in order to characterize the impact of modifiers on the dyeing procedure and coloring properties and to prove the practicability of modified fluid systems for commercial procedures. [source]
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