Weir Formula Research Articles

Evaluation of Different Numerical Approaches to Modeling Flood Flows Over Groynes

AbstractThe hydraulic resistance of groynes is an important factor in the determination of design flood water levels on rivers and the assessment of how much these levels are lowered by modifying the groynes. In standard one‐ or two‐dimensional numerical hydrodynamic models for flood risk management, groynes are commonly represented as subgrid features with a local energy loss according to a weir formula. We tested this representation by using a two‐dimensional horizontal mesh at various groyne submergence degrees by comparing the results with those of flume experiments. We also compared the results with simulations using different 2D and 3D approaches on finer grids that incorporate groynes in the bed topography. In one of the two tested 3D models, complete Reynolds‐averaged Navier‐Stokes equations were solved. The second tested 3D model was constructed simpler by assuming hydrostatic pressure distribution in the vertical direction. We employed Delft3D software in construction and execution of all models. One of the 3D models did predict the hydraulic resistance at low submergence better than the standard model, but it slightly underestimated the resistance at higher submergences. Despite differences in flow characteristics, weirs and groynes were found to produce similar flow resistances for the same height and boundary conditions. Simulations of groyne modifications showed that hydraulic resistance decreased nonlinearly with groyne lowering and streamlining.

Abstract 10593: Resting Energy Expenditure is an Important Factor to Predict Cardiac Mortality in Chronic Heart Failure

Introduction: Parameters derived from cardiopulmonary exercise testing (CPET) with respiratory gas analyzer are important prognostic factors in patients with chronic heart failure (CHF). However, all patients with CHF cannot undergo CPET for reasons such as frailty and comorbidity. On the other hands, resting energy expenditure (REE) derived from respiratory gas analyzer can be easily measured in most patients with CHF, but clinical significance of this parameter had not been fully elucidated in patients with CHF. Aims: We aimed to determine the clinical importance including the prognostic impact of REE in patients with CHF. Methods: A total of 1185 consecutive CHF patients who underwent CPET were enrolled. REE was calculated by Weir's formula (3.941resting oxygen consumption (VO 2 )+1.106resting carbon dioxide production (VCO 2 )). The study population was divided into two groups according to median REE and we compered the clinical characteristics between two groups. Also, we examined the value of REE to predict cardiac mortality in CHF patients. Results: In all subjects, 966 were males, median age was 63 years. Median resting VO 2 was 236 ml/min, median resting VCO 2 was 222 ml/min and median REE was 1178 kcal/day. Patients with low REE (<1178 kcal/day) were older and had higher prevalence of female and anemia, lower body mass index (BMI), more impaired renal function, lower parameters of nutrition such as serum total protein and albumin, higher levels of plasma type-B natriuretic peptide, lower resting VO 2 , lower resting VCO 2 and lower peak VO 2 than those with high REE (>1178 kcal/day). But left ventricular ejection fraction was similar between two groups. Patients with low REE had significantly higher rates of cardiac death, all cause death and composite cardiac event (cardiac death and re-hospitalization due to worsening heart failure). Furthermore, REE was the independent predictor of cardiac death, all-cause death and composite cardiac events in the Cox proportional hazard analysis after adjusted cofounding variables including peak VO 2 . Conclusions: REE as well as peak VO 2 is important predictor of cardiac mortality in patients with CHF.

Abstract 15864: Measured versus Estimated Resting Metabolic Rate in Heart Failure With Preserved Ejection Fraction

Introduction: Obesity is common in heart failure with preserved ejection fraction (HFpEF) and dietary weight loss can improve functional capacity, but sarcopenia and frailty are also frequently present. Little evidence is available regarding resting metabolic rate (RMR) or how commonly used equations to estimate RMR compare to measured RMR in HFpEF. This information is vital for counseling patients on individual caloric needs. Hypothesis: Commonly used estimation equations do not accurately reflect measured RMR in patients with HFpEF. Methods: Resting metabolic rate (RMR) was measured with a metabolic cart for consecutive patients with HFpEF (EF ≥50%) referred for right heart catheterization at the University of Michigan from 2011-2015. Patients with congenital, infiltrative, hypertrophic, or restrictive cardiomyopathy were excluded. The RMR was calculated using the Weir formula: RMR= 1440*[3.94 VO 2 (l/min) + 1.11*VCO 2 (l/min)] kcal/day. Measured RMR and estimations of RMR using the Harris Benedict Equation (HBE), Mifflin-St Jeor Equation (MSJE), and World Health Organization (WHO) equation were compared using paired t-tests and Bland-Altman plots. Results: Patients (n=43) were aged (mean ± SD) 62 ± 11.6 years, 53% female, and BMI 34.9 ± 11. Mean measured RMR from Weir equation was 1514 ± 479 kcal/day. Estimated RMR by HBE was 1784 ± 530, MSJE was 1685 ± 457, and WHO equation was 1816.8 ± 485 kcal/day. All estimations significantly overestimated RMR when compared to the Weir method (>10% difference and p<0.01 for all; Figure A-C). The MSJE had the closest range of agreement to the measured RMR. Conclusions: Estimations of resting metabolic rate in patients with HFpEF demonstrated a fixed bias towards overestimation when compared to measured RMR by metabolic cart. Given HFpEF populations are often obese and are counseled routinely on weight loss, understanding the implicit bias of equations estimating RMR is vital when providing nutritional and dietary counseling.

Estimated Vs. Measured Resting Metabolic Rate to Guide Nutrition Recommendations for Patients with Heart Failure with Reduced Ejection Fraction

Introduction Malnutrition and weight loss among patients with heart failure with reduced ejection fraction (HFrEF) are associated with poor functional status, hospitalization, and death. Nutritional interventions might benefit patients with HFrEF, but few data on resting metabolic rate (RMR) are available to guide such programs. We sought to clarify the relationship between heart failure (HF) severity and RMR and the accuracy of commonly used estimations of RMR in this population. Hypothesis We hypothesized that worsening HF severity would impact RMR and that commonly used estimations of RMR would be inaccurate. Methods We measured RMR with a metabolic cart in 548 consecutive patients with HFrEF at the University of Michigan from 2011 to 2015. The primary outcome of interest was measured RMR using the Weir formula: RMR= 1440*[3.94 VO2 (l/min) + 1.11* VCO2 (l/min)] kcal/day. The primary independent variable was HF severity determined by New York Heart Association function class (NYHA FC). Linear regression adjusted for age, gender, weight, and height was performed to evaluate the impact of HF severity on RMR. Measured RMR and estimations of RMR using the Harris Benedict, Mifflin-St Jeor, and World Health Organization equations, both overall and by NYHA FC, were compared using paired t-tests. Results Patients were aged (mean ± SD) 59 ± 13 years, 73% male, and had an ejection fraction of 19 ± 7%; measured RMR was 1488 ± 416 kcal per day. Worsening HF severity was associated with reduced RMR. In the multivariable model, the predicted RMR for NYHA FC IV patients was -177.5 (95% CI, -246.7 to -108.3, p Conclusions Worsening HF severity is associated with decreasing RMR in patients with HFrEF and discordance of estimations increased with worsening NYHA FC. Estimations of RMR have the potential to introduce clinically meaningful (>10%) error in RMR. Improved understanding of these issues, including their relationship with other measures of HF severity and with body composition, will be necessary to promote adequate nutritional intake for patients with HFrEF.

Hydraulics and Mixing of the Deep Overflow in the Lifamatola Passage of the Indonesian Seas

AbstractHydrographic measurements recently acquired along the thalweg of the Lifamatola Passage combined with historical moored velocity measurements immediately downstream of the sill are used to study the hydraulics, transport, mixing, and entrainment in the dense overflow. The observations suggest that the mean overflow is nearly critical at the mooring site, suggesting that a weir formula may be appropriate for estimating the overflow transport. Our assessment suggests that the weir formulas corresponding to a rectangular, triangular, or parabolic cross section all result in transports very close to the observation, suggesting their potential usage in long-term monitoring of the overflow transport or parameterizing the transport in numerical models. Analyses also suggest that deep signals within the overflow layer are blocked by the shear flow from propagating upstream, whereas the shallow wave modes of the full-depth continuously stratified flow are able to propagate upstream from the Banda Sea into the Maluku Sea. Strong mixing is found immediately downstream of the sill crest, with Thorpe-scale-based estimates of the mean dissipation rate within the overflow up to 1.1 × 10−7 W kg−1 and the region-averaged diapycnal diffusivity within the downstream overflow in the range of 2.3 × 10−3 to 10.1 × 10−3 m2 s−1. Mixing in the Lifamatola Passage results in 0.6–1.2-Sv (1 Sv ≡ 106 m3 s−1) entrainment transport added to the overflow, enhancing the deep-water renewal in the Banda Sea. A bulk diffusivity coefficient estimated in the deep Banda Sea yields 1.6 × 10−3 ± 5 × 10−4 m2 s−1, with an associated downward turbulent heat flux of 9 W m−2.

Experimental Study of Cohesive Embankment Dam Breach Formation due to Overtopping

The recurrent floods in recent decades have imposed a challenge of embankment dam breaching, which needs great attention through improved design methods that are based on risk approach, the evacuation plans for people at risk, etc. In this study, based on the small-scale model tests a series of experiments were conducted to determine the breaching process of cohesive embankment dam using a simplified physical based breach model due to overtopping; the breach process observed during tests in the laboratory and the results from analyzed parameters are described. Five dam models, three of which were constructed with homogenous clay soil while two were sandy-clay mixture tested. The heights of the embankments dam were 0.45 m, and the widths at the crest were 0.20 m. The data from these examinations indicated that headcut erosion played an important role in the process of breach development. Initiation of erosion, flow shear erosion, sidewall bottom erosion, and distinct soil mechanical slope mass failure from the headcut vertically and laterally were all observed during these tests. In this physical based experimental model, the initial scouring position calculated by applying a hydraulic method, the broad crested weir formula used for breaching flow discharge and flow velocity computed based on breach flow discharge. The stability of the side slope failures was estimated by comparing the resisting and deriving force. Further, using data from laboratory experiments, the calculated peak breach discharge, breach characteristics times, breach widths, and breach flow velocity generally agreed well with the measured data and also the knowledge acquired from observed breach process at several stages. Finally, the accuracy of model was checked by root-mean-square-error.

Energy expenditure of patients on ECMO: A prospective pilot study.

An optimal nutritional approach sustained by convenient monitoring of metabolic status and reliable assessment of energy expenditure (EE) may improve the outcome of critically ill patients on extracorporeal membrane oxygenation (ECMO). We previously demonstrated the feasibility of indirect calorimetry (IC)-the standard of care technique to determine caloric targets-in patients undergoing ECMO. This study aims to compare measured with calculated EE during ECMO treatment. We additionally provide median EE values for use in settings where IC is not available. IC was performed in seven stable ECMO patients. Gas exchange was analyzed at the ventilator, and ECMO side and values were introduced in a modified Weir formula to calculate resting EE. Results were compared with EE calculated with the Harris-Benedict equation and with the 25kcal/kg/day ESPEN recommendation. Total median oxygen consumption rate was 196 (Q1-Q3 158-331) mL/min, and total median carbon dioxide production was 150 (Q1-Q3 104-203) mL/min. Clinically relevant differences between calculated and measured EE were observed in all patients. The median EE was 1334 (Q1-Q3 1134-2119) kcal/24 hours or 18 (Q1-Q3 15-27) kcal/kg/day. Compared with measured EE, calculation of EE both over- and underestimated caloric needs during ECMO treatment. Despite a median EE of 21kcal/kg/day, large variability in metabolic rate was found and demands further investigation.

Numerical model for clay core dam breach process due to overtopping considering different failure modes of core wall

Based on the breach mechanism of clay core dam due to overtopping failure, a numerical model for dam breaching process is put forward. In this model, the initial scour position on the downstream slope is determined by means of the characteristics of dam figuration and overtopping flow, the broad-crested weir formula is adopted to calculate breach flow discharge, and a time averaged backward erosion formula is adopted to simulate the dam shell breach. The moment and mechanical equilibrium methods are utilized to model the overturning and sliding failures of the core, respectively. In order to simulate the actual failure mode of the dam, one-and two-sided erosion, as well as dam base erosion, are taken into account. The model adopts the iterative calculation method to simulate the coupling process of water and soil during dam breaching. 10 clay core dam overtopping failure cases which have measured data are adopted to testify the present model. The comparison of measured data and calculated results on peak breach flow, final breach width and failure time shows that the calculated results can meet the engineering requirements, and the statistics of model’s relative errors validate the reasonability of the present model.

Ensemble urban flood simulation in comparison with laboratory-scale experiments: Impact of interaction models for manhole, sewer pipe, and surface flow

An urban flood is an integrated phenomenon that is affected by various uncertainty sources such as input forcing, model parameters, complex geometry, and exchanges of flow among different domains in surfaces and subsurfaces. Despite considerable advances in urban flood modeling techniques, limited knowledge is currently available with regard to the impact of dynamic interaction among different flow domains on urban floods. In this paper, an ensemble method for urban flood modeling is presented to consider the parameter uncertainty of interaction models among a manhole, a sewer pipe, and surface flow. Laboratory-scale experiments on urban flood and inundation are performed under various flow conditions to investigate the parameter uncertainty of interaction models. The results show that ensemble simulation using interaction models based on weir and orifice formulas reproduces experimental data with high accuracy and detects the identifiability of model parameters. Among interaction-related parameters, the parameters of the sewer–manhole interaction show lower uncertainty than those of the sewer–surface interaction. Experimental data obtained under unsteady-state conditions are more informative than those obtained under steady-state conditions to assess the parameter uncertainty of interaction models. Although the optimal parameters vary according to the flow conditions, the difference is marginal. Simulation results also confirm the capability of the interaction models and the potential of the ensemble-based approaches to facilitate urban flood simulation.

Validation of ventilator-derived VCO2 measurements to determine energy expenditure in ventilated critically ill children

Indirect calorimetry (IC) is considered the gold standard to determine resting energy expenditure (REE) but its availability in PICUs worldwide is limited. Ventilator-derived VCO2 could potentially improve the possibility of performing REE measurements. We investigated whether ventilator-derived VCO2 values are comparable to IC-derived VCO2 values and can clinically be used in clinical practice to determine REE. VCO2-values were simultaneously collected in mechanically ventilated children from IC (Deltatrac®) and Servo-I® ventilator on a minute base over at least 10min period of steady state. REE was calculated using the modified Weir formula (for IC) or REE=5.5*VCO2 (L/min)*1440 (for the Servo-I values) and compared with frequently used predictive equations by Schofield and the WHO to calculate REE. Measurements were performed in 41 children; median age 2 years. The mean relative difference between VCO2 measured by IC and Servo-I® was 15.6% (p=0.002), and limits of agreement in the Bland-Altman analysis were wide. Comparable measurements, defined as a difference ≤10% between IC and Servo-I® VCO2 values, were seen in 18 (44%) children, but this proportion was 70% in children ≥15kg. In this group, REE could be accurately predicted using Servo-I® derived VCO2 values and this method was superior to the use of predictive equations. The Servo-I® derived VCO2 values were not sufficiently accurate for the large proportion of children weighing <15kg. In children ≥15kg, VCO2 measurements of the Servo-I® seem sufficiently accurate for use in clinical practice and may be used to determine energy expenditure in the future.

Ventilator-derived carbon dioxide production to assess energy expenditure in critically ill patients: proof of concept.

IntroductionMeasurement of energy expenditure (EE) is recommended to guide nutrition in critically ill patients. Availability of a gold standard indirect calorimetry is limited, and continuous measurement is unfeasible. Equations used to predict EE are inaccurate. The purpose of this study was to provide proof of concept that EE can be accurately assessed on the basis of ventilator-derived carbon dioxide production (VCO2) and to determine whether this method is more accurate than frequently used predictive equations.MethodsIn 84 mechanically ventilated critically ill patients, we performed 24-h indirect calorimetry to obtain a gold standard EE. Simultaneously, we collected 24-h ventilator-derived VCO2, extracted the respiratory quotient of the administered nutrition, and calculated EE with a rewritten Weir formula. Bias, precision, and accuracy and inaccuracy rates were determined and compared with four predictive equations: the Harris–Benedict, Faisy, and Penn State University equations and the European Society for Clinical Nutrition and Metabolism (ESPEN) guideline equation of 25 kcal/kg/day.ResultsMean 24-h indirect calorimetry EE was 1823 ± 408 kcal. EE from ventilator-derived VCO2 was accurate (bias +141 ± 153 kcal/24 h; 7.7 % of gold standard) and more precise than the predictive equations (limits of agreement −166 to +447 kcal/24 h). The 10 % and 15 % accuracy rates were 61 % and 76 %, respectively, which were significantly higher than those of the Harris–Benedict, Faisy, and ESPEN guideline equations. Large errors of more than 30 % inaccuracy did not occur with EE derived from ventilator-derived VCO2. This 30 % inaccuracy rate was significantly lower than that of the predictive equations.ConclusionsIn critically ill mechanically ventilated patients, assessment of EE based on ventilator-derived VCO2 is accurate and more precise than frequently used predictive equations. It allows for continuous monitoring and is the best alternative to indirect calorimetry.

Nutritional-metabolic factors affecting nitrogen balance and substrate utilization in the critically ill.

To determine clinical, anthropometric, metabolic, and nutritional factors affecting nitrogen balance somatic protein status and substrate utilization in critically ill children measured energy expenditure (MEE) was measured by indirect calorimetry within 24 hr of an acute illness, solid organ transplantation, or cardiovascular surgery. Predicted basal metabolic rate was calculated using the Schofield equation. Somatic protein was estimated by the creatinine-height index. Nitrogen balance (NB) was calculated by subtracting the total nitrogen input from output. The net substrate (fat, carbohydrate, and protein) oxidation rates were calculated using the Weir formula modified by Frayn. Sixty-eight NB studies, indirect calorimetric and anthropometric measurements performed in 37 patients. Nitrogen balance was worse when the MEE/Predicted basal metabolic rate ratio was < 0.9 or > 1.1. The incidence of negative NB was 91% when the caloric intake was less than MEE and 9% when it was equal to or greater than MEE (P < 0.05). On day 1, 27% had mild to moderate somatic protein depletion and 5.4% had severe somatic protein depletion. Only the persistence of stress and co-morbidity were associated with the creatinine-height index (P < 0.001). Without Multiple Organ System Failure (MOSF), there was a trend toward positive nitrogen balance by day 7 while with MOSF, negative nitrogen balance persisted even by day 7 (P < 0.05). When caloric intake was less than MEE, mean substrate utilization was 48.6% from lipid, 37.1% from carbohydrate, and 14.3% from proteins. But, when caloric intake was greater than MEE, mean substrate utilization was 83.3% from carbohydrate and 16.7% from protein. Significant negative nitrogen balance and somatic protein depletion develops in critically ill pediatric patients, especially when they are inadequately fed, develop MOSF, or have previous chronic illness. Caloric intake and MOSF independently affect substrate utilization.

A Broad-crested Weir Boundary Condition in Finite Volume Shallow-water Numerical Models

In the literature, the weir boundary condition is usually implemented imposing the weir formula at the boundaries, but this is rigorous only in subcritical steady conditions, and a more general approach is required during transients. With acceptable approximation, the non-submerged broad-crested weir behaves as a bottom step where the energy is conserved and critical conditions are attained at the top. Taking advantage of this observation, the analytic solution of the Riemann problem for the Shallow-water Equations over a dry bottom step is considered in this paper, and the momentum and mass fluxes of the analytic solution of the Riemann problem are used to impose weakly the broad-crested non-submerged weir boundary condition in a Finite Volume scheme.

Rigorous distillation dynamics simulations using a computer algebra

AbstractIn the present paper, Mathematica®, the famous computer algebra, is used to perform steady‐state and dynamic simulations of a multi‐component distillation column. In order to describe the vapor–liquid equilibrium (VLE) relationships and to compute the vapor‐ and liquid‐phase enthalpies, the Soave– Redlich–Kwong equation of state (SRK EOS) is chosen. Rigorous modeling is performed where both mass and energy balance equations are solved. The Francis weir formula is selected to model column hydraulics. All steady‐state results of the column simulations are found to agree very well with those obtained using HYSYS. Finally, some insight into column control is given through the application of both the slope and sensitivity criteria. The computer code, developed at the National Institute of Applied Sciences and Technology (INSAT) in Tunis by the authors, has served to teach several aspects of chemical engineering to senior undergraduate students at INSAT. Indeed, students gain from such code a good understanding of energy and mass balances, column dynamic and control, equations of state and VLE as well as some applied mathematics such as nonlinear algebraic equations, differential‐algebraic systems of equations, and how they can be solved using computer algebra such as Mathematica®. In addition, they learn about major process simulators such as HYSYS. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 20: 193–202, 2012

Energy expenditure of critically ill neonatal foals

Nutritional support in critically ill neonatal foals is of great importance given their high metabolic rate and minimal stores of energy and protein. Nutrient requirements of healthy growing foals have been estimated based on daily milk intake; however, little is known about the resting energy expenditure (REE) of sick foals. To determine REE in critically ill neonatal foals (sepsis and/or hypoxic-ischaemic encephalopathy [HIE] and compare this with REE in control foals. Critically ill newborn foals admitted to the Fundació Hospital Clinic Veterinari, Universitat Autònoma de Barcelona, Spain from March 2009 to February 2011 were included in this study. Healthy neonatal foals and foals with nonsystemic conditions were used as controls. Oxygen consumption and CO2 production were measured with a respiratory monitor connected to a tight fitting facemask and REE (kcal/kg bwt/day) was calculated with the abbreviated Weir formula. Measurements were performed within 24 h of admission and repeatedly during hospitalisation. Twenty-seven foals were included (16 critically ill foals and 11 controls) and a total of 47 measurements were performed. In the critically ill, REE was reduced (mean +/- s.e. 49.5 +/- 2.1 kcal/kg bwt/day) on admission relative to the controls. In surviving foals (n = 5), REE before hospital discharge was not different (68.4 +/- 7.0 kcal/kg bwt/day) from control foals (64.8 +/- 2.7 kcal/kg bwt/day). REE was lower in critically ill foals upon admission (40-50 kcal/kg bwt/day) and normalised before hospital discharge (60-80 kcal/kg bwt/day). Critically ill neonatal foals tolerating enteral feeding would receive approximately their REE when given 10% of their bodyweight in mare's milk daily. For sick neonates unable to tolerate enteral nutrition, provision of 50 kcal/kg bwt/day would be a reasonable goal for parenteral nutrition.

Dynamic simulation and nonlinear control of a rigorous batch reactive distillation

This work deals with the dynamics and control of a high-purity batch distillation column with chemical reaction. A heterogeneous esterification reaction between the acetic acid and butanol takes place to produce butyl acetate. The process model is formulated considering variable liquid holdup, UNIQUAC model for thermodynamic property predictions, nonlinear Francis weir formula for tray hydraulics, pseudohomogeneous model to represent the reaction kinetics and rigorous energy balance. A structured and simple iterative approach is devised to compute the vapor flows with the fast convergence, under the rigorous energy balance. The representative column is treated with a distillate policy based on which, the lightest product, water is removed as distillate at the starting of production phase. As a consequence, the column gets progressively richer with the main product, butyl acetate. In addition, almost complete conversion of the limiting reactant is achieved. In order to maintain the product purity at the top, a nonlinear generic model controller (GMC) in two different forms has been proposed. Finally, a comparative closed-loop performance is addressed. It is shown that the control scheme, along with the effective distillate strategy, leads to almost complete conversion of ingredients and high-purity products.

Semi-parametric model of an overtopped dike breach

This paper uses a semi-parametric approach to model the breaching of overtopped dikes composed of non-cohesive material. The hydraulic discharge is computed on the basis of a broad-crested weir formula, while the erosion is modelled using the Smart sediment transport formula. Breach length is computed on the basis of sediment transport rate where the Exner equation is solved numerically. To simplify the model, two stages of the breach processes are assumed. In stage I the downstream dike crest does not reach the centre line of the original crest and both upstream and downstream edges of the crest move upstream. In stage II the downstream dike crest reaches the centre line of the original crest and it moves vertically downwards. The upstream movement of the dike toe stops, resulting in a decrease of the angle of the downstream face of the dike. A comparison of measured and computed values shows that the numerical computation gives good results in predicting reservoir water level and elevation of the mid-breach.

Three-dimensional non-cohesive earthen dam breach model. Part 1: Theory and methodology

An erosion and force/moment equilibrium based three-dimensional dam breach model is developed for the non-cohesive earthen dam overtopping breach problem. The breach location can be anywhere along the dam. The model considers the topography of the entire dam site. Three-dimensional slope stability along the main direction of flow in the breach channel is checked. A second order hybrid-type of total variation diminishing finite-difference scheme is proposed to simulate the dam breach outflow by solving the two-dimensional shallow water equations. The scheme is shown to accurately reproduce supercritical, subcritical, and transcritical flows for the following analytical or experimental cases: one-dimensional theoretical dam break with initially dry and wet beds, steady flow over a bump, hydraulic jump, one-dimensional dam break with a bottom slope, and two-dimensional dam break with bottom and side slopes. Applications to a simple breach channel show that calculated flows match the broad-crested weir formula and reasonably fit the grids.

Influence of epidural analgesia upon postoperative fatigue

This study examined the effect of epidural analgesia on the development of postoperative fatigue and the ability to ambulate after surgery. Seventeen patients admitted for elective abdominal surgery were randomized to receive postoperative analgesia with a continuous infusion of epidural fentanyl (epidural group) or intermittent intramuscular morphine (non-epidural group). Fatigue was assessed on an analogue scale of 1 (fit) to 10 (fatigued). Steady state measurements of respiratory gas exchange, respiratory rate, tidal volume and heart rate were made before operation and repeated on the third postoperative day. Energy expenditure was calculated from Weir's formula. Ambulatory measurements were made during treadmill walking at a work rate of 20 kpm min-1 (3.3 W). At rest, patients in both groups had a similar cardiorespiratory response to surgery irrespective of the method of analgesia. Subjective feelings of fatigue were significantly greater in those patients who had received epidural analgesia (P less than 0.01) and patients in this group expended significantly more energy in performing the postoperative exercise test than did those in the non-epidural group (P less than 0.05). The use of epidural opiate analgesia does not limit postoperative fatigue in patients undergoing upper abdominal surgery.

제주도 주요하천의 기저유출량 산정

Groundwater in Jeju Island, flowing through main stream, is spring water from underground. To set a fixed quantity of groundwater flowing from surface in a hydrological view, 4 downstream (Woedo stream, Gangjung stream, Yeonwoe stream and Ongpo stream) were selected to calculate the characteristic of baseflow and the base-flow discharge through the data on tachometry. There were 11 to 14 level peak caused by runoff, mostly occurred during monsoon season. Also, duration of runoff was 15 to 25 hours, well reflecting the characteristic of inclined, short stream length in Jeju Island and pervious hydrogeographical feature. In case of Gangjung stream, Yeonwoe stream and Ongpo stream, variation of stream water level by baseflow rose above during summer, which was closely linked to the distribution of seasonal precipitation. From autumn to spring, water level fell below while that of Woedo stream remained the same all year round. Data on the water level observed in Woedo stream and Gangjung stream in every single minutes was applied to weir formula(equation of Oki and Govinda Rao) to calculate baseflow discharge. Also, using the data on current and water level calculated in Ongpo stream and Yeonwoe stream, water level-water flow rating was applied to assess base flow discharge.