Overflow characteristics of circular weirs: Effects of inflow conditions

The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular-crested weir, and nowadays, the ogee crest weir, Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design, and the associated lower costs. in this study, the writers describe new experiments of circular weir overflows, with eight cylinder sizes, for several weir heights and for five types of inflow conditions: partially developed inflow, fully developed inflow, upstream ramp, upstream undular hydraulic jump, and upstream (breaking) hydraulic jump. Within the range of the experiments, the cylinder size, the weir height DIR and the presence of an upstream ramp had no effect on the discharge coefficient, flow depth at crest, and energy dissipation. But the inflow conditions had substantial effects on the discharge characteristics and flow properties at the crest. Practically, the results indicate that discharge measurements with circular weirs are significantly affected by the upstream flow conditions.

Influence of Parasympathetic Modulation in Doppler Mitral Inflow Velocity in Individuals without Heart Disease

Background: The relation between left ventricular filing velocities determined by Doppler echocardiography and autonomic nervous system function assessed by heart rate variability (HRV) is unclear. The aim of this study was to evaluate the influence of the autonomic nervous system assessed by the time and frequency domain indices of HRV in the Doppler indices of left ventricular diastolic filling velocities in patients without heart disease. Methods: We studied 451 healthy individuals (255 female [56.4%]) with normal blood pressure, electrocardiogram, chest x-ray, and treadmill electrocardiographic exercise stress test results, with a mean age of 43 +/- 12 (range 15-82) years, who underwent transthoracic Doppler echocardiography and 24-hour electrocardiographic ambulatory monitoring. We studied indices of HRV on time (standard deviation [SD] of all normal sinus RR intervals during 24 hours, SD of averaged normal sinus RR intervals for all 5-minute segments, mean of the SD of all normal sinus RR intervals for all 5-minute segments, root-mean-square of the successive normal sinus RR interval difference, and percentage of successive normal sinus RR intervals > 50 ms) and frequency (low frequency, high frequency, very low frequency, low frequency/high frequency ratio) domains relative to peak flow velocity during rapid passive filling phase (E), atrial contraction (A), E/A ratio, E-wave deceleration time, and isovolumic relaxation time. Statistical analysis was performed with Pearson correlation and logistic regression. Results: Peak flow velocity during rapid passive filling phase (E) and atrial contraction (A), E/A ratio, and deceleration time of early mitral inflow did not demonstrate a significant correlation with indices of HRV in time and frequency domain. We found that the E/A ratio was < 1 in 45 individuals (10%). Individuals with an E/A ratio < 1 had lower indices of HRV in frequency domain (except low frequency/high frequency) and lower indices of the mean of the SD of all normal sinus RR intervals for all 5-minute segments, root-mean-square of the successive normal sinus RR interval difference, and percentage of successive normal sinus RR intervals > 50 ms in time domain. Logistic regression demonstrated that an E/A ratio < 1 was associated with lower HF. Conclusion: Individuals with no evidence of heart disease and an E/A ratio < 1 demonstrated a significant decrease in indexes of HRV associated with parasympathetic modulation. (J Am Soc Echocardiogr 2010;23: 762-5.)

A wave of change: Labor market and social security impacts of the EU refugee inflow

The recent massive inflow of refugees to the European Union (EU) raises a number of unanswered questions on the economic impact of this phenomenon. To examine these questions, we constructed an overlapping-generations model that describes the evolution of the skill premium and of the welfare benefit level in relevant European countries, in the aftermath of an inflow of asylum-seekers. In our simulation, relative wages of skilled workers increase between 8% and 11% in the period of the inflow; their subsequent time path is dependent on the initial skill premium. The entry of migrants creates a fiscal surplus of about 8%, which can finance higher welfare benefits in the subsequent periods. These effects are weaker in a scenario where refugees do not fully integrate into the labor market.

Clinical results of autologous infrainguinal revascularization using grafts originating distal to the femoral bifurcation in patients with mild inflow disease.

AIM: Chronic critical limb ischemia (CLI) often requires venous bypass grafting to distal arterial segments. However, graft patency is influenced by the length and quality of the graft and occasionally patients may have limited suitable veins. We investigated short distal bypass grafting from the superficial femoral or popliteal artery to the infrapopliteal, ankle or foot arteries, despite angiographic alterations of inflow vessels, providing that invasive pressure measurement at the site of the planned proximal anastomosis revealed an inflow-brachial pressure difference of <or=10 mmHg. METHODS: Four hundred and twenty-three consecutive infrainguinal bypass grafts were performed for CLI between June, 1999 and November, 2002 at our institution. All patients underwent preoperative clinical examination, arteriography and assessment of the veins by duplex ultrasound. The study group are patients in whom the proximal and distal anastomoses of the bypass are below the femoral bifurcation and the popliteal artery, respectively. Invasive arterial pressure measurements were recorded at the level of the planned proximal anastomosis which was performed at that level if the difference of the inflow-brachial pressure was <or=10 mmHg, irrespective of angiographic alterations of the inflow vessels proximal to the planned anastomosis. All patients had a clinical follow-up included a duplex examination of their graft, at 1 week, 3, 9 and 12 months and, thereafter, annually. No patient was lost to follow-up. RESULTS: Sixty-seven patients underwent 71 short distal bypass grafts in 71 limbs with reversed saphenous vein grafts in 52, in situ saphenous veins in 11, reversed cephalic vein in 1 and composite veins in 7, respectively. Surgical or endovascular interventions to improve inflow were required in 4 limbs (5.6%). The mean follow-up time was 22.5 months and the two-year survival was 92.5%. Primary and secondary patency rates at 2 years were 73% and 93%, respectively, and the limb salvage rate was 98.5%. CONCLUSION: In appropriately selected patients, short distal venous bypass grafts can be performed with satisfactory patency and limb salvage rates even in the presence of morphologic alterations of the inflow vessels providing that these are not hemodynamically significant, or can be corrected intraoperatively.

Avaliação clínica de cães submetidos à parada circulatória total por diferentes períodos de tempo através da técnica de "Inflow Occlusion"

A técnica de "Inflow Occlusion" pode ser utilizada em cirurgias cardíacas quando se pretende manter o coração aberto apenas por alguns minutos, para realização de pequenos reparos. No entanto, a parada circulatória total (PCT), evento decorrente da técnica em questão, pode acarretar severas alterações metabólicas e neurológicas ao paciente. Neste estudo foram utilizados 12 cães sem raça definida, os quais foram divididos em dois grupos, A e B, sendo os mesmos submetidos a 7 e 8 minutos de PCT, respectivamente, utilizando-se da técnica de "Inflow Occlusion". Tentou-se estabelecer normotermia durante os procedimentos cirúrgicos. Avaliações clínica e comportamental foram realizadas nos dois grupos após os procedimentos cirúrgicos e dados bioquímicos foram coletados para comparação entre os períodos pré e pós-operatórios. Ocorreram dois óbitos transoperatórios no grupo B. Alterações clínicas transitórias foram observadas no grupo A até o momento M7 (48 horas após cirurgia), e no grupo B, as mesmas foram mais intensas e presentes mesmo após M7; e em um animal do grupo B foi observada cegueira permanente por todo o período de acompanhamento. Apesar das alterações observadas, há indícios que seja seguro realizar a técnica de "Inflow Occlusion" por até 7 minutos, sendo contra-indicada, no entanto, para períodos mais prolongados.

Predicting fault inflow in iterative software development processes: an industrial evaluation

This paper addresses the need for accurate predictions on the fault inflow, i.e. the number of faults found in the consecutive project weeks, in highly iterative processes. In such processes, in contrast to waterfall-like processes, fault repair and development of new features run almost in parallel. Given accurate predictions on fault inflow, managers could dynamically re-allocate resources between these different tasks in a more adequate way. Furthermore, managers could react with process improvements when the expected fault inflow is higher than desired. This study suggests software reliability growth models (SRGMs) for predicting fault inflow. Originally developed for traditional processes, the performance of these models in highly iterative processes is investigated. Additionally, a simple linear model is developed and compared to the SRGMs. The paper provides results from applying these models on fault data from three different industrial projects. One of the key findings of this study is that some SRGMs are applicable for predicting fault inflow in highly iterative processes. Moreover, the results show that the simple linear model represents a valid alternative to the SRGMs, as it provides reasonably accurate predictions and performs better in many cases.

Limnology of Macrobrachium amazonicum grow-out ponds subject to high inflow of nutrient-rich water and different stocking and harvest management

We evaluated the water characteristics and particle sedimentation in Macrobrachium amazonicum (Heller 1862) grow-out ponds supplied with a high inflow of nutrient-rich water. Prawns were subject to different stocking and harvesting strategies: upper-graded juveniles, lower-graded juveniles, non-graded juveniles + selective harvesting and traditional farming (non-grading juveniles and total harvest only). Dissolved oxygen, afternoon N-ammonia and N-nitrate and soluble orthophosphate were lower in the ponds in comparison with inflow water through the rearing cycle. Ponds stocked with the upper population fraction of graded prawns showed higher turbidity, total suspended solids and total Kjeldahl nitrogen than the remaining treatments. An increase in the chemical oxygen demand:biochemical oxygen demand ratio from inlet (4.9) to pond (7.1-8.0) waters indicated a non-readily biodegradable fraction enhancement in ponds. The sedimentation mean rate ranged from 0.08 to 0.16 mm day(-1) and sediment contained >80% of organic matter. The major factors affecting pond ecosystem dynamic were the organic load (due to primary production and feed addition) and bioturbation caused by stocking larger animals. Data suggest that M. amazonicum grow-out in ponds subjected to a high inflow of nutrient-rich water produce changes in the water properties, huge accumulation of organic sediment at the pond bottom and non-readily biodegradable material in the water column. However, the water quality remains suitable for aquaculture purposes. Therefore, nutrient-rich waters, when available, may represent a source of unpaid nutrients, which may be incorporated into economically valued biomass if managed properly.

Investigation of young water inflow in karst aquifers using SF6–CFC–3H/He–85Kr–39Ar and stable isotope components

Karst aquifers are known for their wide distribution of water transfer velocities. From this observation, a multiple geochemical tracer approach seems to be particularly well suited to provide a significant assessment of groundwater flows, but the choice of adapted tracers is essential. In this study, several common tracers in karst aquifers such as physicochemical parameters, major ions, stable isotopes, and d13C to more specific tracers such as dating tracers – 14C, 3H, 3H–3He, CFC-12, SF6 and 85Kr, and 39Ar – were used, in a fractured karstic carbonated aquifer located in Burgundy (France). The information carried by each tracer and the best sampling strategy are compared on the basis of geochemical monitoring done during several recharge events and over longer time periods (months to years). This study’s results demonstrate that at the seasonal and recharge event time scale, the variability of concentrations is low for most tracers due to the broad spectrum of groundwater mixings. The tracers used traditionally for the study of karst aquifers, i.e., physicochemical parameters and major ions, efficiently describe hydrological processes such as the direct and differed recharge, but require being monitored at short time steps during recharge events to be maximized. From stable isotopes, tritium, and Cl� contents, the proportion of the fast direct recharge by the largest porosity was estimated using a binary mixing model. The use of tracers such as CFC-12, SF6, and 85Kr in karst aquifers provides additional information, notably an estimation of apparent age, but they require good preliminary knowledge of the karst system to interpret the results suitably. The CFC-12 and SF6 methods efficiently determine the apparent age of baseflow, but it is preferable to sample the groundwater during the recharge event. Furthermore, these methods are based on different assumptions such as regional enrichment in atmospheric SF6, excess air, and flow models among others. 85Kr and 39Ar concentrations can potentially provide a more direct estimation of groundwater residence time. Conversely, the 3H–3He method is inefficient in the karst aquifer for dating due to 3He degassing.

Tax differentials and inflow of foreign direct investments : evidence from foreign operations of U.S. multinational companies

This paper concerns the measurement of the impact of tax differentials across countries on inflow of Foreign Direct Investment (FDI) by using comprehensive data on the foreign operations of U.S. multinational corporations that has been collected by the Bureau of Economic Analysis (BEA), the U.S. Department of Commerce. In particular, this research focuses on examining: (1) how responsive FDI locations are to tax differentials across countries, (2) how different the tax effect on FDI inflow is between developed and developing countries, and (3) whether investment location decisions have become more or less sensitive to tax differences between countries over time ranging from the late 1990s to the early 2000s. Estimation results suggest that high rates of corporate income taxation are associated with reduced foreign assets of U.S. multinational firms in all industries by decreasing the return to foreign asset investment. Further, foreign assets of U.S. multinationals in all industries have become more responsive to non-income tax differentials across countries than to income tax differences from 1999 to 2004. Empirical estimates also indicate that foreign investment by American firms is associated with higher tax sensitivity more in developed countries than in those that are developing.

Predicted suspended sediment inflow to the San Francisco Bay system /

Bibliography : leaf 33.

Chesapeake Bay low freshwater inflow study

Mode of access: Internet.

Modelling the effects of inflow parameters on lake water quality

A one-dimensional lake water quality model which includes water temperature, phytoplankton, phosphorus as phosphate, nitrogen as ammonia, nitrogen as nitrate and dissolved oxygen concentrations, previously calibrated for Lake Calhoun (USA) is applied to Uokiri Lake (Japan) for the year 1994. The model simulated phytoplankton and nutrient concentrations in the lake from July to November. Most of the water quality parameters are found to be the same as for Lake Calhoun. To predict probable lake water quality deterioration from algal blooming due to increased nutrient influx from river inflow, the model was run for several inflow water conditions. Effects of inflow nutrient concentration, inflow volume, inflow water temperatures are presented separately. The effect of each factor is considered in isolation although in reality more than one factor can change simultaneously. From the results it is clear that inflow nutrient concentration, inflow volume and inflow water temperature show very regular and reasonable impacts on lake water quality.

Hydraulics of skimming flows on stepped chutes: The effects of inflow conditions?

Modern stepped spillways are typically designed for large discharge capacities corresponding to a skimming flow regime for which flow resistance is predominantly form drag. The writer demonstrates that the inflow conditions have some effect on the skimming flow properties. Boundary layer calculations show that the flow properties at inception of free-surface aeration are substantially different with pressurized intake. The re-analysis of experimental results highlights that the equivalent Darcy friction factor is f similar to 0.2 in average on uncontrolled stepped Chute and f similar to 0.1 on stepped chute with pressurized intake. A simple design chart is presented to estimate the residual flow velocity, and the agreement of the calculations with experimental results is deemed satisfactory for preliminary design.

Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel (Fig. 1 Classical hydraulic jump with partially developed inflow conditions)

Fig. 1. Classical hydraulic jump with partially developed inflow conditions. F1 = 13.6, V1 = 4.7 m/s, B = 0.25 m, h = 0.020 mm, d1 = 0.012 mm, Q = 14 L/s. Photo courtesy of Dr. Hubert Chanson. published in: Geomorphology Volume 82, Issues 1-2, 6 December 2006, Pages 146-159 The Hydrology and Geomorphology of Bedrock Rivers doi:10.1016/j.geomorph.2005.09.024 Submerged and unsubmerged natural hydraulic jumps in a bedrock step-pool mountain channel Brett L. Vallé and Gregory B. Pasternacka