Impact of global climate change on stream low flows:A case study of the great Miami river watershed, Ohio, USA

Climate change will profoundly affect hydrological processes at various temporal and spatial scales.This study is focused on assessing the alteration of water resources availability and low flows frequencies driven by changing climates in different time periods of the 21st century.This study evaluates the adaptability of prevailing Global Circulation Models(GCMs)on a particular watershed through streamflow regimes.This analysis was conducted in the Great Miami River Watershed,Ohio by analyzing historical and future simulated streamflow using 10 climate model outputs and the Soil and Water Assessment Tool(SWAT).The climate change scenarios,consisting of ten downscaled Coupled Model Intercomparision Project Phase 5(CMIP5)climate models in combination with two Representative Concentration Pathways(RCP 4.5 and RCP 8.5)were selected based on the correlation between observed records and model outputs.Streamflow for three future periods,2016-2043,2044-2071 and 2072-2099,were independently analyzed and compared with the baseline period(1988-2015).Results from the average of ten models projected that 7-day low flows in the watershed would increase by 19%in the 21st century under both RCPs.This trend was also consistent for both hydrological(7Q10,1Q10)and biological low flow statistics(4B3,1B3).Similarly,average annual flow and monthly flows would also increase in future periods,especially in the summer.The flows simulated by SWAT in response to the majority of climate model projections showed a consistent increase in low flow patterns.However,the flow estimates using the Max-Planck-Institute Earth System Model(MPI-ESM-LR)climate output resulted in the biological based low flows(4B3,1B3)decreasing by 22.5%and 33.4%under RCP 4.5 and 56.9%and 63.7%under RCP 8.5,respectively,in the future when compared to the baseline period.Regardless,the low flow ensemble from the 10 climate models for the 21st century seemed to be slightly higher than that of historical low flows.

Methodology for production logging in oil-in-water flows under low flow rate and high water-cut conditions

This study aimed to obtain the production profiles of oil-in-water flow under low flow rate and high water-cut conditions in oil wells.A combination production profile logging composed of an arc-type conductance sensor(ATCS)and a cross-correlation flow meter(CFM)with a center body is proposed and experimentally evaluated.The ATCS is designed for water holdup measurement,whereas the CFM with a center body is proposed to obtain the mixture velocity.Then,a drift-flux model based on flow patterns is established to predict the individual-phase superficial velocity of oil-in-water flows.Results show that the ATCS possesses high resolution in water holdup measurement and that flow pattern information can be deduced from its signal through nonlinear time series analysis.The CFM can enhance the correlation of upstream and downstream signals and simplify the relationship between the cross-correlation velocity and mixture velocity.On the basis of the drift-flux model,individual-phase superficial velocities can be predicted with high accuracy for different flow patterns.

A NOVEL SLIGHTLY COMPRESSIBLE MODEL FOR LOW MACH NUMBER PERFECT GAS FLOW CALCULATION

By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.

Investigation and numerical simulation of inner-flow of an axial mineflow fan under low flow rate conditions

Because of unstable properties of axial mine flow fans working under conditions of low flow rates, the safety and reliability of fans in their operational zone is reduced. At times, serious vibration may bring about the destruction of equipment or even jeopardize the safety of entire factories. By means of oil flow visualization techniques and numerical simulation, we have investigated the inner-flow of an axial mine flow fan working under low flow rate conditions. The fundamental reasons of complex flow phenomena of the inner-flow of the flow fan under these stated conditions were revealed. At the same time and in order to improve the inner-flow under conditions of low flow rates, a blade separator and air separator were designed. From our tests we found that the blade separator and air separator are two kinds efficient methods to improve the unstable working characteristics of the axial mine flow fan operating under low flow rate conditions. The effect of the improvement of the air separator is stronger than that of the blade separator.

The effects of drainage basin geomorphometry on minimum low flow discharge: the study of small watershed in Kelang River Valley in Peninsular Malaysia

This study investigate the relationships between geomorphometric properties and the minimum low flow discharge of undisturbed drainage basins in the Taman Bukit Cahaya Seri Alam Forest Reserve, Peninsular Malaysia. The drainage basins selected were third-order basins so as to facilitate a common base for sampling and performing an unbiased statistical analyses. Three levels of relationships were observed in the study. Significant relationships existed between the geomorphometric properties as shown by the correlation network analysis; secondly, individual geomorphometric properties were observed to influence minimum flow discharge; and finally, the multiple regression model set up showed that minimum flow discharge(Q min) was dependent of basin area(AU), stream length(LS), maximum relief(Hmax), average relief(HAV) and stream frequency(SF). These findings further enforced other studies of this nature that drainage basins were dynamic and functional entities whose operations were governed by complex interrelationships occurring within the basins. Changes to any of the geomorphometric properties would influence their role as basin regulators thus influencing a change in basin response. In the case of the basin's minimum low flow, a change in any of the properties considered in the regression model influenced the “time to peak' of flow. A shorter time period would mean higher discharge, which is generally considered the prerequisite to flooding. This research also conclude that the role of geomorphometric properties to control the water supply within the stream through out the year even though during the drought and less precipitations months. Drainage basins are sensitive entities and any deteriorations involve will generate reciprocals and response to the water supply as well as the habitat within the areas.

Mathematical Modeling,Field Calibration and Numerical Simulation of Low-Speed Mixed Traffic Flow in Cities

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Numerical Simulation of Stall Flow Control Using a DBD Plasma Actuator in Pulse Mode

A numerical simulation method is employed to investigate the effects of the unsteady plasma body force over the stalled NACA 0015 airfoil at low Reynolds number flow conditions. The plasma body force created by a dielectric barrier discharge actuator is modeled with a phenomenological method for plasma simulation coupled with the compressible Navier-Stokes equations. The governing equations are solved using an efficient implicit finitevolume method. The responses of the separated flow field to the effects of an unsteady body force in various inter- pulses and duty cycles as well as different locations and magnitudes are studied. It is shown that the duty cycle and inter-pulse are key parameters for flow separation control. Additionally, it is concluded that the body force is able to attach the flow and can affect boundary layer grow that Mach number 0.1 and Reynolds number of 45000.

Numerical Study of Air Nozzles on Mild Combustion for Application to Forward Flow Furnace

An attempt was made to extend mild combustion to forward flow furnace, such as the refinery and petrochemical tube furnace. Three dimensional numerical simulation was carried out to study the performance of this furnace. The Eddy Dissipation Concept(EDC) model coupled with the reaction mechanism DRM-19 was used. The prediction showed a good agreement with the measurement. The effect of air nozzle circle(D), air nozzle diameter(d), air nozzle number(N), and air preheating temperature(Tair) on the flow, temperature and species fields, and the CO and NO emissions was investigated. The results indicate that there are four zones in the furnace, viz.: a central jet zone, an ignition zone, a combustion reaction zone, and a flue gas zone, according to the distribution profiles of H_2 CO and OH. The central jet entrains more flue gas in the furnace upstream with an increasing D while the effect of D is negligible in the downstream. The air jet momentum increases with a decreasing d or an increasing Tair, and entrains more flue gas. The effect of N is mainly identified near the burner exit. More heat is absorbed in the radiant section and less heat is discharged to the atmosphere with a decreasing d and an increasing N as evidenced by the flue gas temperature. The CO and NO emissions are less than 50 μL/L and 10 μL/L, respectively, in most of conditions.

A Low Mach Number IMEX Flux Splitting for the Level Set Ghost Fluid Method

Considering droplet phenomena at low Mach numbers,large differences in the magnitude of the occurring characteristic waves are presented.As acoustic phenomena often play a minor role in such applications,classical explicit schemes which resolve these waves suffer from a very restrictive timestep restriction.In this work,a novel scheme based on a specific level set ghost fluid method and an implicit-explicit(IMEX)flux splitting is proposed to overcome this timestep restriction.A fully implicit narrow band around the sharp phase interface is combined with a splitting of the convective and acoustic phenomena away from the interface.In this part of the domain,the IMEX Runge-Kutta time discretization and the high order discontinuous Galerkin spectral element method are applied to achieve high accuracies in the bulk phases.It is shown that for low Mach numbers a significant gain in computational time can be achieved compared to a fully explicit method.Applica-tions to typical droplet dynamic phenomena validate the proposed method and illustrate its capabilities.

Polymer-Based Micro Flow Sensor with Alternative Electronic Signal Interfaces for Low and High Flow Rates

The qualitative and quantitative assessment of gas flow has become increasingly relevant in the use of everyday systems. The micro flow sensor, developed by Innovative Sensor Technology AG （Switzerland）, is by principle a calorimetric flow sensor produced as a micro system on a glass substrate by means of photolithography and glass etching technology. These structures are arranged as a platinum micro heater and sensor in a Wheatstone bridge. The subsequent etching process produces an exposed area of polyimide membrane that is only a few microns thick and includes the resistive sensor structure as the active area. In addition, the RTD （resistance temperature detector） technology included on the sensor allows for the implementation of a variety of electronic biasing and signal processing modes. Since the sensor can be powered and the bridge can be measured in both CTA （constant temperature anemometer） and calorimetric mode, new possibilities are presented for both low and high flow rates with regard to temperature compensation, self-calibration and self-monitoring.

The Problems and Solutions of Rural Labor Flowing in low Marketization Level

Rural labor flowing in low marketization level restricts rural production elements of effective allocation, and restricts the development of rural economy, causes the gap between urban and rural areas to continue expanding. This article has analyzed the reasons of phenomenon, and raised some solutions from abolishing the barrier of the household register, improved rural labor＇ s cultural and skills quality, and built a social security system in rural areas improve the marketization level of rural labor flow.

Retrofit on Low Pressure Cylinder Flow Path Succeeded

The retrofit on flow path of low pressure cylinder of domestic made 200 MW steam turbine undertaken by Longwei Power Generation Technology Service Company Ltd by using Westinghouse technology was successful for the first time on the No. 5 unit of Zhenhai Prover Plant. Zhejiang Province. The test carried out by the Xi’an Thermal Power Research Institute showed that the thermal efficiency after the retrofit

Paradoxical Low Flow Low Gradient Severe Aortic Stenosis—An Under-Recognized Entity

Some patients with severe aortic stenosis (AS), due to restrictive cardiac physiology, paradoxically have relatively low flow and low gradients across stenotic aortic valves despite preserved left ventricular (LV) systolic function. It results in symptoms and reduced quality of life and carries a high mortality. Whilst this form of severe AS, termed paradoxical low flow low gradient (pLFLG), is well reported, patients with this diagnosis experience inappropriate barriers to aortic valve replacement (AVR), the only efficacious treatment. We present the case of an 88-year-old female with 12 months of exertional dyspnoea on a background of hypothyroidism and hypercholesterolemia. Transthoracic echocardiogram (TTE) revealed LV hypertrophy, with a small LV cavity size and reduced stroke volume, yet normal systolic function. A heavily calcified aortic valve was identified with severe aortic stenosis, based on valve area, yet with incongruous mean transvalvular gradient of 25 mmHg (severe ≥ 50 mmHg). Following exclusion of other differential diagnoses, her symptoms were attributed to paradoxical LFLG severe AS. She was however declined definitive transcatheter aortic valve implantation (TAVI) due to her paradoxically low mean aortic gradient. Following further deterioration in her symptoms and supportive quantification of poor exercise performance, she was ultimately re-referred, accepted, and underwent TAVI. Following her AVR, the patient experiences significant improvement in both symptoms and quality of life after only one month. Paradoxical LFLG severe AS remains a well-documented yet under recognized disease. It carries high morbidity and mortality if untreated, yet is significantly less likely to be referred and accepted for intervention. With its prevalence expected to rise with an ageing population, this case serves as a timely reminder for clinicians to address the under recognition of important pathology.

Base Flow Index Evaluation for Yom River,Thailand

The most controversial river in Thailand is the Yom River.It has not been modified by large dam because of several valuable natural resources.Therefore,the river is flooded in rainy season and very low flow in dry season.The low flow causes drought which is much more serious than flooding.The Yom River Basin management is only way to circumvent the low flow problem by studying base flow index(BFI).Base flow analyses for 8 gauging stations along the river were performed by 2 techniques i.e.graphical and modified U.K.Institute of Hydrology(MIH).The mean BFI results from graphical and MIH are 0.37(0.05)and 0.45(0.12).The result from graphical is more reasonable due to its lower standard deviation.BFI values from MIH vary with watershed area which may result from the using of fixing value of N-day at 10.Solution for this problem is ongoing in this study.

Planned second-look laparoscopy in the management of acute mesenteric ischemia

AIM： To investigate the role of second-look laparoscopy in patients with acute mesenteric ischemia （AMI）. METHODS： Between January 2000 and November 2005, 71 patients were operated for the treatment of AMI. The indications for a second-look were low flow state, bowel resection and anastomosis or mesenteric thromboembolectomy performed during the first operation. Regardless of the clinical course of patients, the second-look laparoscopic examination was performed 72 h post-operatively at the bed side in the ICU or operating room. RESULTS： The average time of admission to the hospital after the initation of syrnptoms was 3 d （range, 5 h-9 d）. In 14 patients, laparotomy was performed. In 11 patients, small and/or large bowel necrosis was detected and initial resection and anastomosis were conducted. A low flow state was observed in two patients and superior mesenteric artery thromboembolectomy with small bowel resection was performed in one patient. In 13 patients, a second-look laparoscopic examination revealed normal bowel viability, but in one patient, intestinal necrosis was detected. In two of the patients, a third operation was necessary to correct anastomotic leakage. The overall complication rate was 42.8%, and in-hospital mortality rate was 57.1% （n = 6）. CONCLUSION： Second-look laparoscopy is a minimally invasive, technically simple procedure that is performed for diagnostic as well as therapeutic purposes. The simplicity and ease of this method may encourage wider application to benefit more patients. However, the timing of a second-look procedure is unclear particularly in a patient with anastomosis.

Characteristic Temperatures of Waxy Crude Oils

Gel point or pour point is widely used to evaluate the low temperature flowability of crude oil. However, it is not adequate to describe the gelling properties of waxy crude oils under flow conditions with gel point or pour point, since the theological behavior of crude oils is dependent on shear history. Waxy crude oils tend to gel at a low temperature. Based on gelation theory, the characteristic temperature of waxy crude oil was determined by analyzing viscosity-temperature data. Two mathematical models were developed for calculating characteristic temperatures of virgin crude oils and pour point depressants （PPD） beneficiated crude oils, respectively. By using these two models, the characteristic temperatures of crude oils that have experienced shearing and thermal histories can be predicted. The model for predicting the characteristic temperature of virgin crude oils has an average relative deviation of 4.5%, and all predicted values have a deviation within 2 ℃. Tested by 42 sets of data, the prediction model for crude oil treated with PPD has a high accuracy, with an average relative deviation of 4.2%, and 95.2 percent of predicted values have a deviation within 2 ℃. These two models provide useful ways for predicting the flowability of crude oils in pipelines when only wax content, wax appearance point and gel point are available.

Alfapump®implantable device in management of refractory ascites:An update

Refractory ascites(RA)is a frequent and life-threatening complication of cirrhosis.In selected patients with RA,transjugular intrahepatic portosystemic shunt(TIPS)placement and liver transplantation(LT)are currently considered the best therapeutic alternatives to repeated large volume paracentesis.In patients with a contraindication to TIPS or LT,the alfapump®system(Sequana Medical,Ghent,Belgium)has been developed to reduce the need for iterative paracentesis,and consequently to improve the quality of life and nutritional status.We report here recent data on technical progress made since the first implantation,the efficacy and tolerance of the device,the position of the pump in the therapeutic arsenal for refractory ascites,and the grey areas that remain to be clarified regarding the optimal selection of patients who are potential candidates for this treatment.

COMPUTATIONAL AND EXPERI-MENTAL STUDY ON TIP LEAKAGE VORTEX OF CIRCUMFERENTIAL SKEWED BLADES

In the steady operation condition, the experiments and the numerical simulations are used to investigate the tip leakage flow fields in three low pressure axial flow fans with three kinds of circumferential skewed rotors, including the radial rotor, the forward-skewed rotor and the back- ward-skewed rotor. The three-dimensional viscous flow fields of the fans are computed. In the experiments, the two-dimensional plane particle image velocimetry （PIV） system is used to measure the flow fields in the tip region of three different pitchwise positions of each fan. The results show that the computational results agree well with the experimental data in the flow field of the tip region of each fan. The tip leakage vortex core segments based on method of the eigenmode analysis can display clearly some characteristics of the tip leakage vortex, such as the origination position of tip leak- age vortex, the development of vortex strength, and so on. Compared with the radial rotor, the other two skewed rotors can increase the stability of the tip leakage vortex and the increment in the forward-skewed rotor is more than that in the backward-skewed one. Among the tip leakage vortices of the three rotors, the velocity of the vortex in the forward-skewed rotor is th6 highest in the circumferential direction and the lowest in the axial direction.

On the calculation of the electron temperature flowfield in the DSMC studies of ionized re-entry flows

Currently available procedures of electron temperature calculations in studying ionized flows around reentry spacecraft by the direct simulation Monte Carlo(DSMC)method are analyzed.It is shown that the heat conduction of electrons is not taken into account in these procedures.The contributions of various effects to the electron energy balance are calculated by an example of the RAM-C II capsule,and a numerical solution of the electron energy conservation equation is obtained,which refines the electron temperature distribution used in the DSMC computations.A method of coupled calculation of the electron temperature within the framework of the continuum approach and modelling of ionized gas flow by the DSMC method is proposed.

Responses of Hydrological Processes to Climate Change in the Zhujiang River Basin in the 21st Century

In this study, discharge at the outlet of Xijiang River, the biggest sub-basin of the Zhujiang River, was simulated and projected from 1961 to 2099 using the hydrological model HBV-D. The model uses precipitation and temperature data from CISRO/MK3 5, MPI/ECHAM5, and NCAR/CCSM3 under three greenhouse gas emission scenarios (SRES A2, A1B, B1). The results in water resources and flood frequency suggest that annual precipitation and annual runoff would increase after 2050 relative to the reference period of 1961-1990. In addition, increasing trends have been projected in area averaged monthly precipitation and runoff from May to October, while decreasing trends in those from December to February. More often and larger floods would occur in future. Potential increase in runoff during the low-flow season could ease the pressure of water demand until 2030, but the increase in runoff in the high-flow season, with more often and larger floods, more pressure on flood control after 2050 is expected.