Ordinary Flow Research Articles

Aerodynamic investigation of turbine cooled vane block

The vane block (VB) has been investigated and it gives several important results related to test methods and calculation procedures. The vane block is characterized by a developed film and convective cooling system. Blowing tests demonstrate that there is a weak correlation between cooling type and energy loss. Superposition of these effects is true for the central part over VB height without secondary flows. Coolant discharge increases profile loss and it rises if coolant flow rate is increased. Discharge onto profile convex side through the trailing edge slot influences the most considerably. The discharge through perforation decreases the vane flow capacity and insufficiently influences onto the flow outlet angle, but the trailing edge discharge increases this angle according to loss and mixture flow rate growth. The secondary flows reduce the effect of coolant discharge, which insufficiently changes losses distribution at turbine blades tips and even decreases the secondary losses. The flow outlet angle rises significantly and we are able to calculate it only if we correct the ordinary flow model. In the area of secondary flows, the outlet angle varies insufficiently under any type of cooling. This area should be investigated additionally.

Porous Medium Model in Computational Fluid Dynamics Simulation of a Honeycombed SCR DeNOx Catalyst

AbstractThe commercial computational fluid dynamics software FLUENT was used to simulate the flow and chemical reaction process of a honeycombed SCR DeNOx catalyst. In the calculation model, the porous medium model was applied to describe the wall body region of the honeycombed catalyst and the ordinary flow model in order to define the honeycombed channel region. From the comparison between the two gas diffusion rates within catalyst pore structure and gas medium, their effects on the SCR DeNOx reaction rate were analyzed. A correction factor of the chemical reaction rate was created to modify the porous medium model in order to accurately calculate the chemical reaction process of the catalyst model. The study results indicated that the combination between porous medium model and reaction rate correction factor could compensate the deviation of calculated reaction rate and the interfacial diffusion problems.

A possible modification of groundwater flow equation using coordinate transformations

We described a groundwater model with prolate spheroid coordinates, and introduced a new parameter, namely τ the silhouette influence of the geometric under which the water flows. At first, we supposed that the silhouette influence approaches zero; under this assumption, the modified equation collapsed to the ordinary groundwater flow equation. We proposed an analytical solution to the standard version of groundwater as a function of time, space and uncertainty factor α. Our proposed solution was in good agreement with experimental data. We presented a good approximation to the exponential integral. We obtained an asymptotic special solution to the modified equation by means of the Adomian decomposition and variational iteration methods.

Study of tributary inflows in Lake Iseo with a rotating physical model

The influence of Coriolis force on the currents of large lakes is well acknowledged; very few contributions, however, investigate this aspect in medium-size lakes where its relevance could be questionable. In order to study the area of influence of the two major tributary rivers in Lake Iseo, a rotating vertically distorted physical model of the northern part of this lake was prepared and used, respecting both Froude and Rossby similarity. The model has a horizontal length scale factor of 8000 and a vertical scale factor of 500 and was used both in homogeneous and in thermally stratified conditions. We explored the pattern of water circulation in front of the entrance mouth for different hydrologic scenarios at the beginning of spring and in summer. We neglected the influence of winds. The primary purposes of the model were twofold: i) to increase our level of knowledge of the hydrodynamics of Lake Iseo by verifying the occurrence of dynamical effects related to the Earth’s rotation on the plume of the two tributaries that enter the northern part of the lake and ii) to identify the areas of the lake that can be directly influenced by the tributaries’ waters, in order to provide guidance on water quality monitoring in zones of relevant environmental and touristic value. The results of the physical model confirm the relevant role played by the Coriolis force in the northern part of the lake. Under ordinary flow conditions, the model shows a systematic deflection of the inflowing waters towards the western shore of the lake. The inflow triggers a clockwise gyre within the Lovere bay, to the West of the inflow, and a slow counter-clockwise gyre, to the East of the inflow, that returns water towards the river mouth along the eastern shore. For discharges with higher return period, when only the contribution by Oglio River is relevant, the effect of the Earth’s rotation weakens in the entrance zone and the plume has a more rectilinear pattern, whilst in the far field the current driven by the inflows keeps moving along the western shore. On the basis of these results one could expect that the north-western part of the lake between Castro and Lovere, although not aligned with the tributaries’ axes, is more sensitive to accumulation effects related to river-borne pollution. The results obtained with the physical model are critically compared with data obtained from different sources: the trajectory of a lagrangian drogue; a map of reflectivity data from the lake floor; a map of water turbidity at the intrusion depth. The findings are also confirmed by the results of a 3D numerical model of the lake .

A Shock Wave Attached to a Pointed Obstacle in a Steady flow of a Dissociating Gas

A pointed obstacle is assumed symmetrically placed with respect to a uniform supersonic flow ahead of it. It is assumed that an oblique shock wave attached to the leading edge of the obstacle appears form the vertex so that the flow after the shock is along the surface of the obstacle. In this paper a relation between the curvature of an attached shock wave and that of a stream line is discovered. It is concluded that in a steady flow of an ideal dissociating gas, the stream lines at the rear of a straight attached shock wave are necessarily curved lines, whereas in an ordinary gas flow only a straight line flow is possible behind a straight shock.

수리모형실험과 수치해석을 통한 자연형어도의 어류서식처 평가

It is increasing to make an efforts on preventing natural river environment and preserving natural river ecosystem as development is unavoidable. In the case of inconsistent river flow caused by reservoir development, fishway is an alternative to secure fish diversity and preserve existing river ecosystem but existing fishway was established without full study for their functions. In this study, hydraulic characteristics of natural fishway established on Beakje weir's right side were analyzed. The results show that the fishway has reasonable depth and velocity condition which inhabit condition is enough for a dominant species. For assessing the optimal design of fishway, the Weighted Usable Area (WUA) was calculated by using two dimensional numerical model under the ordinary flow condition. The comparison results for various pool widths in the fishway show that the designed width has maximum WUA for adult Zacco platypus but WUA is maximized with 1m wider pool width than designed width for spawning.

유량-부하량관계식을 이용한 주암호 외남천 유역의 유황별 유달율 산정

The objective of this study is to provide pollutant loads delivery ratio for flow duration in Oenam-cheon watershed, which is upstream watershed of Juam Lake. To calculate the delivery ratio by flow duration, rating curves and discharge-loads curves using measured data were established, then Flow Duration Curve(FDC) and pollutant loads delivery ratio curves were constructed. The results show that the delivery ratios for <TEX>$BOD_5$</TEX> for abundant flow(<TEX>$Q_{95}$</TEX>), ordinary flow(<TEX>$Q_{185}$</TEX>), low flow(<TEX>$Q_{275}$</TEX>), and drought flow(<TEX>$Q_{355}$</TEX>) were 23.9, 12.7, 7.1, and 2.9%, respectively. The delivery ratios of same flow regime for T-N were 58.4, 31.2, 17.2 and 7.1%, respectively. While, the delivery ratios T-P were 17.3, 7.5, 3.4, and 1.1% respectively. In general, delivery ratio of high flow condition showed higher value due to the influence of nonpoint source pollution. Based on the study results, generalized equations were developed for delivery ratio and discharge per unit area, which could be used for ungaged watershed with similar pollution sources.

Treatment of Chemical Production Wastewater Containing Fluorine with Two Kinds of Fluidized Bed Reactor by Induced Crystallization

Keywords: Fluidized bed；Bubbling bed；Induced crystallization；Fluoride removal；Quartz sands Abstract: Through establishing two kinds of experimental device, regular bed and bubbling fluidized bed, it researched the treatment process of producing fluorine-containing wastewater in the method of chemical-induced crystallization. Taking a way of continuous flow, ordinary fluidized bed continuous flow approach measured the amount of fluoride crystals and the treatment effect. Using intermittent operation, bubbling fluidized bed measured the amount of fluoride crystal and the treatment effect. The results show that: ordinary fluidized bed treatment effect worse than the bubbling fluidized bed. Bubbling fluidized bed in a short time large amount of fluoride crystals, can be a lot of fluoride to fluoride content of waste water treatment 10mg / L or less. The technical processing speed, good effect, the reaction vessel is small, simple device, easy to control, with good prospects for practical application.

On Flow through Renal Tubule in case of Periodic Radial Velocity Component

The problem of fluid motion in a renal tubule, in contrast to ordinary flow through cylinder with the impermeable wall, is complicated by the existence of radial velocity generated by reabsorption process. It has been experienced that due to some abnormality the porosity of wall may get hampered in turn radial velocity may become periodic. The main objective of this paper is to read the behaviour of blood flow through renal tubule in case of periodic radial velocity component. It is the fact that the radial component of velocity of blood is responsible to balance the salt concentration between dialyzate and blood stream. Our analysis shows that the blood flow pattern changes and flow is not smooth.

Economic Crisis and Share Price Unpredictability: Reasons and Implications

The volatility of share returns for individual companies increased sharply during the recent financial crisis. The larger part of this increase was due to a dramatic rise – five fold as measured by variance – in idiosyncratic risk. We find that this pattern repeats itself during each major economic reversal going back 85 years. Because idiosyncratic risk is what is involved, this increase cannot be explained by changes in predictions concerning the future course of the economy as a whole. Our first goal is to explain why difficult economic times, which are defined in terms of market wide phenomena, make the future of individual firms more difficult to predict, above and beyond the effects of the more difficult to predict economy as a whole. One explanation is that in crisis times, information about a firm contained in current news may become more important, compared to ordinary times, in predicting its future cash flows relative to the role of the already existing stock of knowledge relevant to making such predictions. A second is that the quality of management becomes more important in crisis times; consequently, the ordinary flow of information about this subject can have bigger impact. A third is that crisis may create uncertainty as to what factors are even important to valuation; because of uncertainty, a broader range of information may be seen to shed light on this question, and therefore move stock prices. We find less convincing two other possible explanations: noise trading and the idea that the increase in idiosyncratic risk is the result of a bad-times-induced separating equilibrium that reveals which firms have fraudulent or inept managers who were able to mask their problems in the preceding good times and which firms have been genuinely well managed all along. Our second goal is to explore the implications of our results for corporate and securities litigation, which, over the last few decades, has become increasingly enmeshed with the empirical analysis of the idiosyncratic portion of share returns of the companies involved. In this connection, we consider the determination of loss causation in fraud-on-the-market class actions, the determination of materiality necessary for a trade on non-public information to violate the law, the determination of what items of information should be subject to a mandatory disclosure, and the extent of deference that should be paid to a corporate board that reject acquisition offers at a premium above pre-offer market price. In each of these areas, we find that there are no simple answers to the question of whether the increase in idiosyncratic risk during periods of crisis would justify a change in practice.

A hydraulic study on the applicability of flood rating curves

Several hydrological studies have shown that river discharge records are affected by significant uncertainty. This uncertainty is expected to be very high for river flow data referred to flood events, when the stage–discharge rating curve is extrapolated far beyond the measurement range. This study examines the standard methodologies for the construction and extrapolation of rating curves to extreme flow depths and shows the need of proper approaches to reduce the uncertainty of flood discharge data. To this end, a comprehensive analysis is performed on a 16km reach of the River Po (Italy) where five hydraulic models (HEC-RAS) were built. The results of five topographical surveys conducted during the last 50 years are used as geometric input. The application demonstrates that hydraulically built stage–discharge curves for the five cases differ only for ordinary flows, so that a common rating curve for flood discharges can be derived. This result confirms the validity of statistical approaches to the estimation of the so-called ‘flood rating curve’, a unique stage–discharge curve based on data of contemporaneous annual maxima of stage and discharge values, which appears insensitive to marginal changes in river geometry.

Classifying Best Access Points for Return of External Flows into Flowsheets

External flows are process streams that come from auxiliary processes or events. They are re-routed into the ordinary flowsheet since they are thought to be too valuable to be sent to any tailings pond. External flows come from multiple sources, e.g. drainage sumps, spillage thickeners, depleted products etc. Therefore, external flows may fit or not fit into an existing flowsheet depending on several factors like, flow rate frequency, dilution ratio variation, chemical and mineralogical composition, particle size or particle morphology. By using Particle Texture Analysis to investigate external flows and compare them with existing ordinary flows it is possible to pinpoint from a process mineralogy via point to what extent the external flow fits into the ordinary processing flowsheet. Results from this information category helps to reach a higher quality of process knowledge and control for every step in the concentrator. Results show that some recycled flows reconnected to the main flow are not connected to the best point. A side effectof the analysis is that some flows may be sent to later grinding stages. Thus, decreasing the load on the primary mill, and increasing the retention time.

Real-time scheduling for reentrant hybrid flow shops: A decision tree based mechanism and its application to a TFT-LCD line

A reentrant hybrid flow shop, typically found in the electronics industry, is an extended system of the ordinary flow shop in such a way that there exist one or more parallel machines at each serial stage and each job has the reentrant product flow, i.e., a job may visit a stage several times. Among the operational issues in reentrant hybrid flow shops, we focus on the scheduling problem that determines the allocation of jobs to the machines at each stage as well as the sequence of the jobs assigned to each machine. Unlike the theoretical approach on reentrant hybrid flow shop scheduling, we suggest a real-time scheduling mechanism with a decision tree when selecting appropriate dispatching rules. The decision tree, one of the commonly used data mining techniques, is adopted to eliminate the computational burden required to carry out simulation runs to select dispatching rules. To illustrate the mechanism suggested in this study, a case study was performed on a thin film transistor-liquid crystal display (TFT-LCD) manufacturing line and the results are reported for various system performance measures.

Chaotic mixer using electro-osmosis at finite Péclet number

Two pressure-driven streams of two miscible liquids can only mix by diffusion in microfluidic channels because of the low Reynolds number. We present an idea to generate mixing by "chaotic advection" in microscale geometries. That is, we consider using induced-charge electro-osmosis to generate a second flow and then modulate between the pressure-driven and induced-charge flows. By using the combined method consisting of the boundary element method, the Lagrangian particle tracking method, and the random-walk method, we analyze mixing efficiency, mixing time, and mixing length, with the effects of modulation frequency and molecular diffusivity, and compare our proposed mixer with other mixers. By this analysis, we find that chaotic mixing can be produced efficiently in a microfluidic channel by switching between pressure-driven and induced-charge flows in a wide range of Péclet number under the specific condition of Strouhal number. By using our proposed mixer, we can expect to realize efficient chaotic mixing with minimum voltage in an ordinary flow channel with a simple structure without an oblique electric field even at large Péclet number.

Morphology transitions at the mouth of River Tenryu

An X-band radar was employed to observe morphological behaviors at the mouth of River Tenryu, Sizuoka, Japan, for 2.5 years from June 2007. Land area of the river channel showed a seasonal variation: it increases in the summer seasons and decreases in winter. The river mouth widens by floods and narrows at ordinary flow periods. Phase difference between water levels in the river and ocean decreases generally in summer and increases in winter. Also, a coefficient representing flow resistance in the estuary showed a similar seasonal variation. The sand bar at the river mouth migrated towards inland in 2009, and water depths of the sea bottom in front of the river mouth estimated by analyzing wave motions captured during storms became milder from 2007 to 2009, suggesting overall coastal slope decreased during the period.

Half Metal, Full Spin

Applied Physics For optimal efficiency in spintronic applications (which replace ordinary charge flow with spin current), host materials should ideally be completely spin-polarized. Unfortunately, not many materials have this property. Heusler alloys constitute an emerging prospect. These are metals, or rather half-metals, in which the conduction band is split into two polarizations—one half occupied, the other empty—thus providing 100% spin polarized current transport. However, the materials studied so far have shown strongly temperature-dependent behavior due to the band structure, making them unsuitable for practical device applications. Shan et al. now show that Fermi-level tuning by the introduction of appropriate dopant atoms, a technique similar to electron or hole enrichment in semiconductors, can be applied to the Heusler alloy Co2FeAl0.5Si0.5. With a spin-polarization exceeding 90% and a weak temperature dependence up to room temperature, the resulting material highlights the potential of Fermi-level tuning for attaining high performance in spintronic applications. Phys. Rev. Lett. 102 , 246601 (2009).

河川の水質形成と集水域の土地利用形態との関係

The relationship between the formation of river water quality and the land use of river watershed at Lake Kasumigaura (Ls. Nishiura and Kitaura) was investigated in this study using measured in situ data and data calculated using a geographic information system (GIS). NO3-N concentrations in river water were high, particularly in L. Kitaura watershed. The NO3-N concentrations increased at a low-water-temperature period and decreased with dilution after rainfall. The relationship between river water quality and land use characteristics in river watershed was examined by principal component analysis. The nitrogen concentrations in river water were correlated with the number of livestock, upland field and forest area in their watershed at ordinary flow. A high correlation was confirmed particularly between the number of pigs and NO3-N concentration. Paddy field and urban area were correlated with phosphorus, organic matter and particulate matter concentrations. During flood due to rainfall, the nitrogen concentrations in small-scale rivers showed a high correlation with only the number of pigs.

A note on a generalized network flow model for manufacturing process

Manufacturing network flow (MNF) is a generalized network model that overcomes the limitation of an ordinary network flow in modeling more complicated manufacturing scenarios, in particular the synthesis of different materials into one product and/or the distilling of one type of material into many different products. Though a network simplex method for solving a simplified version of MNF has been outlined in the literature, more research work is still needed to give a complete answer whether some classical duality and optimality results of the classical network flow problem can be extended in MNF. In this paper, we propose an algorithmic method for obtaining an initial basic feasible solution to start the existing network simplex algorithm, and present a network-based approach to checking the dual feasibility conditions. These results are an extension of those of the ordinary network flow problem.

RRFS에 의한 금강수계의 주요지점별 유역유출지표 개발

In this study, we attempted to develop a watershed runoff index subject to main control points by dividing the Geum River basin into 14 sub-basins. The Yongdam multipurpose dam Daecheong multipurpose dam and Gongju gage station were selected to serve as the main control points of the Geum River basin, and the observed flow of each control point was calculated by the discharge rating curve, whereas the simulated flow was estimated using the Rainfall Runoff Forecasting System (RRFS), user-interfaced software developed by the Korea Water Corporation, based on the Streamflow Synthesis and Reservoir Regulation (SSARR) model developed by the US Army Corps of Engineers. This study consisted of the daily unit observed flow and the simulated flow of the accumulated moving average flow by daily, 5-days, 10-days, monthly, quarterly and annually, and normal monthly/annually flow. We also performed flow duration analysis for each of the accumulated moving average and the normal monthly/annually flows by unit period, and abundant flow, ordinary flow, low flow and drought flow estimated by each flow duration analysis were utilized as watershed runoff index by main control points. Further, as we determined the current flow by unit period and the normal monthly/annually flow through the drought and flood flow analysis subject to each flow we were able to develop the watershed runoff index in a system that can be used to determine the abundance and scarcity of the flow at the corresponding point.

Attraction Without Networks: Recruiting Strangers to Unregistered Protestantism in China

Social movements research points to the role of networks in recruiting intimates and public spaces in recruiting strangers. But for Chinese Protestants, creative outreach strategies can be a substitute for existing relationships and initiate recruitment. In China, public proselytizing is forbidden, religion is rarely mentioned in the media, and direct contact with potential converts is discouraged. To attract strangers, evangelists in China rely on door-to-door proselytizing in the countryside, cultural performances embedded with religious messages in the cities, and one-on-one conversations when the opportunity arises. By contacting targets in the ordinary flow of life and fashioning appeals using resonant language, Protestant recruiters have become adept at attracting non-networked individuals in "safe-enough" spaces that appear in the creases of a reforming Leninist regime. At a general level, the analysis suggests that networks sometimes play a smaller role in recruitment than is commonly thought, at least at first, and that social bonds may be as much a result of recruitment as a precondition for it.