Institute of Scientific and Technical Information of China (English)
蔡兴国; 曹海龙
2001-01-01
Analyses the flow tracing based on power flow, points out that the detachment of reactive power and active power is unrealiable and concludes that the current is the real basic of flow tracing,and proposes the new flow tracing model based on current, which devides the current into active current and reactive current, analyses the theory about the matrix to deal with the precision and realization of the flow tracing, and then proposes a new pricing model by fixed rate and marginal rate, which keeps not only economy information such as congestion cost in marginal cost based pricing, but also benefits to make both ends meet.
Base Flow Model Validation Project
National Aeronautics and Space Administration — The program focuses on turbulence modeling enhancements for predicting high-speed rocket base flows. A key component of the effort is the collection of...
CFD-based Evaluation of Interfacial Flows
Ito, Kei; Ohshima, Hiroyuki; Sakai, Takaaki; Kunugi, Tomoaki
2010-01-01
As an example of the evaluation of interfacial flows, two methodologies were proposed for the evaluation of the GE phenomena. One is the CFD-based prediction methodology and the other is the high-precision numerical simulation of interfacial flows. In the development of the CFD-based prediction methodology, the vortical flow model was firstly constructed based on the Burgers theory. Then, the accuracy of the CFD results, which are obtained on relatively coarse computational mesh without consi...
DIELECTROPHORESIS BASED MICRO FLOW CYTOMETRY
Vykoukal, Jody; Schwartz, Jon A.; Gascoyne, Peter R.C.; Yu, Choongho; Shi, Li
2003-01-01
We report a simplified flow cytometer design that makes use of negative dielectrophoresis (DEP) for particle focusing and integrated optical and AC impedance detectors to enable an inexpensive, compact and robust system for cell and particle characterization. This straightforward, modular design could be applied as a standalone instrument or as a particle detector in an integrated micro total analysis system.
The Information Flow Analyzing Based on CPC
Institute of Scientific and Technical Information of China (English)
ZHANG Zhang; LI Hui
2005-01-01
The information flow chart within product life cycle is given out based on collaborative production commerce (CPC) thoughts. In this chart, the separated information systems are integrated by means of enterprise knowledge assets that are promoted by CPC from production knowledge. The information flow in R&D process is analyzed in the environment of virtual R&D group and distributed PDM. In addition, the information flow throughout the manufacturing and marketing process is analyzed in CPC environment.
Flow Modeling Based Wall Element Technique
Directory of Open Access Journals (Sweden)
Sabah Tamimi
2012-08-01
Full Text Available Two types of flow where examined, pressure and combination of pressure and Coquette flow of confined turbulent flow with a one equation model used to depict the turbulent viscosity of confined flow in a smooth straight channel when a finite element technique based on a zone close to a solid wall has been adopted for predicting the distribution of the pertinent variables in this zone and examined even with case when the near wall zone was extended away from the wall. The validation of imposed technique has been tested and well compared with other techniques.
Process flow measurement based on tracer techniques
International Nuclear Information System (INIS)
Flow measurement methods based on the tracer techniques are the transit time method as well as methods based on tracer dilution. These methods can be applied to the on-site calibration of flowmeters and to measuring the flowrate where no flowmeter is installed. The accuracy of the tracer methods depends on the prevailing measuring conditions. In this report the accuracy of the transit time method under field conditions is estimated to be 1-2% on the 99,7% confidence level. The accuracy of the isotope dilution method is estimated as slightly better, namely about 0.5% at its best. An even better accuracy, about 0.2%, could be achieved by developing the method and the measuring equipment. Tests were carried out with the transit time method for water and steam flow. While measuring water flow the effect of different measuring parameters upon the repeatability of the method were looked into. Such were the number of the detectors and the distance between the measuring points. Different means of tracer injection were tested, as well. These had less effect than expected. The accuracies achieved in steam flow measurements were of the same order of magnitude as in water flow measurements. The tracers used were 137mBa for water flow and 41Ar for steam flow measurements
Duality based optical flow algorithms with applications
DEFF Research Database (Denmark)
Rakêt, Lars Lau
We consider the popular TV-L1 optical flow formulation, and the so-called duality based algorithm for minimizing the TV-L1 energy. The original formulation is extended to allow for vector valued images, and minimization results are given. In addition we consider different definitions of total...... variation regularization, and related formulations of the optical flow problem that may be used with a duality based algorithm. We present a highly optimized algorithmic setup to estimate optical flows, and give five novel applications. The first application is registration of medical images, where X...... chromatograms, where registration only have to be done in one of the two dimensions, resulting in a vector valued registration problem with values having several hundred dimensions. We propose a novel method for solving this problem, where instead of a vector valued data term, the different channels are coupled...
Characteristics-based modelling of flow problems
International Nuclear Information System (INIS)
The method of characteristics is an exact way to proceed to the solution of hyperbolic partial differential equations. The numerical solutions, however, are obtained in the fixed computational grid where interpolations of values between the mesh points cause numerical errors. The Piecewise Linear Interpolation Method, PLIM, the utilization of which is based on the method of characteristics, has been developed to overcome these deficiencies. The thesis concentrates on the computer simulation of the two-phase flow. The main topics studied are: (1) the PLIM method has been applied to study the validity of the numerical scheme through solving various flow problems to achieve knowledge for the further development of the method, (2) the mathematical and physical validity and applicability of the two-phase flow equations based on the SFAV (Separation of the two-phase Flow According to Velocities) approach has been studied, and (3) The SFAV approach has been further developed for particular cases such as stratified horizontal two-phase flow. (63 refs., 4 figs.)
Transformation of Commercial Flows into Physical Flows of Electricity – Flow Based Method
Directory of Open Access Journals (Sweden)
M. Adamec
2009-01-01
Full Text Available We are witnesses of large – scale electricity transport between European countries under the umbrella of the UCTE organization. This is due to the inabilyof generators to satisfy the growing consumption in some regions. In this content, we distinguish between two types of flow. The first type is physical flow, which causes costs in the transmission grid, whilst the second type is commercial flow, which provides revenues for the market participants. The old methods for allocating transfer capacity fail to take this duality into account. The old methods that allocate transmission border capacity to “virtual” commercial flows which, in fact, will not flow over this border, do not lead to optimal allocation. Some flows are uselessly rejected and conversely, some accepted flows can cause congestion on another border. The Flow Based Allocation method (FBA is a method which aims to solve this problem.Another goal of FBA is to ensure sustainable development of expansion of transmission capacity. Transmission capacity is important, because it represents a way to establish better transmission system stability, and it provides a distribution channel for electricity to customers abroad. For optimal development, it is necessary to ensure the right division of revenue allocation among the market participants.This paper contains a brief description of the FBA method. Problems of revenue maximization and optimal revenue distribution are mentioned.
On a Flow-Based Paradigm in Modeling and Programming
Sabah Al-Fedaghi
2015-01-01
In computer science, the concept of flow is reflected in many terms such as data flow, control flow, message flow, information flow, and so forth. Many fields of study utilize the notion, including programming, communication (e.g., Shannon-Weaver communication model), software modeling, artificial intelligence, and knowledge representation. This paper focuses on two approaches that explicitly assert a flow-based paradigm: flow-based programming (FBP) and flowthing modeling (FM). The first is ...
Exploring multi-layer flow network of international trade based on flow distances
Shen, Bin; Zheng, Qiuhua
2015-01-01
Based on the approach of flow distances, the international trade flow system is studied from the perspective of multi-layer flow network. A model of multi-layer flow network is proposed for modelling and analyzing multiple types of flows in flow systems. Then, flow distances are introduced, and symmetric minimum flow distance is presented. Subsequently, we discuss the establishment of the multi-layer flow networks of international trade from two coupled viewpoints, i.e., the viewpoint of commodity flow and that of money flow. Thus, the multi-layer flow networks of international trade is explored. First, trading "trophic levels" are adopted to depict positions that economies occupied in the flow network. We find that the distributions of trading "trophic levels" have the similar clustering pattern for different types of commodity, and there are some regularities between money flow network and commodity flow network. Second, we find that active and competitive countries trade a wide spectrum of products, while ...
Simulation of fires based on flow calculation
International Nuclear Information System (INIS)
The fire simulation based on flow calculation is described in the publication, and the calculated result is compared with the results obtained from fire tests. The tests have been made in Germany in a nuclear power plant removed from service. The simulation describes the flow field of the entire building, the main features of the construction effecting on it and the edge conditions. The fire is described as a given source, the value of which varies as a function of time. Heat transfer into the constructions is described using a separate heat transfer program. The result obtained from calculation describes the flow and temperature fields formed in a fire generally correctly. Due to the used sparse calculation network the results contain locally large deviations. The discrete-transfer radiation calculation method used for calculation of burning and heat transfer, and testing of it are described in the appendix. The method describes the heat radiation propagating diagonally to the calculation network better than the six-flux method used before
On a Flow-Based Paradigm in Modeling and Programming
Directory of Open Access Journals (Sweden)
Sabah Al-Fedaghi
2015-06-01
Full Text Available In computer science, the concept of flow is reflected in many terms such as data flow, control flow, message flow, information flow, and so forth. Many fields of study utilize the notion, including programming, communication (e.g., Shannon-Weaver communication model, software modeling, artificial intelligence, and knowledge representation. This paper focuses on two approaches that explicitly assert a flow-based paradigm: flow-based programming (FBP and flowthing modeling (FM. The first is utilized in programming and the latter in modeling (e.g., software development. Each produces a diagrammatic representation, and these are compared. The purpose is to promote progress in a flow-based paradigm and its utilization in the area of computer science. The resultant analysis highlights the fact that FBP and FM can benefit from each other’s methodology.
Atlas-based analysis of 4D flow CMR: Automated vessel segmentation and flow quantification
Bustamante, Mariana; Petersson, Sven; Eriksson, Jonatan; Alehagen, Urban; Dyverfeldt, Petter; Carlhäll, Carljohan; Ebbers, Tino
2015-01-01
Background Flow volume quantification in the great thoracic vessels is used in the assessment of several cardiovascular diseases. Clinically, it is often based on semi-automatic segmentation of a vessel throughout the cardiac cycle in 2D cine phase-contrast Cardiovascular Magnetic Resonance (CMR) images. Three-dimensional (3D), time-resolved phase-contrast CMR with three-directional velocity encoding (4D flow CMR) permits assessment of net flow volumes and flow patterns retrospectively at any...
Subsampling-based compression and flow visualization
Energy Technology Data Exchange (ETDEWEB)
Agranovsky, Alexy; Camp, David; Joy, I; Childs, Hank
2016-01-19
As computational capabilities increasingly outpace disk speeds on leading supercomputers, scientists will, in turn, be increasingly unable to save their simulation data at its native resolution. One solution to this problem is to compress these data sets as they are generated and visualize the compressed results afterwards. We explore this approach, specifically subsampling velocity data and the resulting errors for particle advection-based flow visualization. We compare three techniques: random selection of subsamples, selection at regular locations corresponding to multi-resolution reduction, and introduce a novel technique for informed selection of subsamples. Furthermore, we explore an adaptive system which exchanges the subsampling budget over parallel tasks, to ensure that subsampling occurs at the highest rate in the areas that need it most. We perform supercomputing runs to measure the effectiveness of the selection and adaptation techniques. Overall, we find that adaptation is very effective, and, among selection techniques, our informed selection provides the most accurate results, followed by the multi-resolution selection, and with the worst accuracy coming from random subsamples.
Knowledge Based Design of Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Dinesh kumar.R
2015-05-01
Full Text Available In the aerospace industry with highly competitive market the time to design and delivery is shortening every day. Pressure on delivering robust product with cost economy is in demand in each development. Even though technology is older, it is new for each customer requirement and highly non-liner to fit one in another place. Gas turbine is considered one of a complex design in the aircraft system. It involves experts to be grouped with designers of various segments to arrive the best output. The time is crucial to achieve a best design and it needs knowledge automation incorporated with CAD/CAE tools. In the present work an innovative idea in the form of Knowledge Based Engineering for axial compressor is proposed, this includes the fundamental design of axial compressor integrated with artificial intelligence in the form of knowledge capturing and programmed with high level language (Visual Basis.Net and embedded into CATIA v5. This KBE frame work eases out the design and modeling of axial compressor design and produces 3D modeling for further flow simulation with fluid dynamic in Ansys-Fluent. Most of the aerospace components are developed through simulation driven product development and in this case it is established for axial compressor.
Physically-based interactive Schlieren flow visualization
Energy Technology Data Exchange (ETDEWEB)
Mccormick, Patrick S [Los Alamos National Laboratory; Brownlee, Carson S [Los Alamos National Laboratory; Pegoraro, Vincent [UNIV OF UTAH; Shankar, Siddharth [UNIV OF UTAH; Hansen, Charles D [UNIV OF UTAH
2009-01-01
Understanding fluid flow is a difficult problem and of increasing importance as computational fluid dynamics produces an abundance of simulation data. Experimental flow analysis has employed techniques such as shadowgraph and schlieren imaging for centuries which allow empirical observation of inhomogeneous flows. Shadowgraphs provide an intuitive way of looking at small changes in flow dynamics through caustic effects while schlieren cutoffs introduce an intensity gradation for observing large scale directional changes in the flow. The combination of these shading effects provides an informative global analysis of overall fluid flow. Computational solutions for these methods have proven too complex until recently due to the fundamental physical interaction of light refracting through the flow field. In this paper, we introduce a novel method to simulate the refraction of light to generate synthetic shadowgraphs and schlieren images of time-varying scalar fields derived from computational fluid dynamics (CFD) data. Our method computes physically accurate schlieren and shadowgraph images at interactive rates by utilizing a combination of GPGPU programming, acceleration methods, and data-dependent probabilistic schlieren cutoffs. Results comparing this method to previous schlieren approximations are presented.
The importance of base flow in sustaining surface water flow in the Upper Colorado River Basin
Miller, Matthew P.; Buto, Susan G.; Susong, David D.; Rumsey, Christine A.
2016-05-01
The Colorado River has been identified as the most overallocated river in the world. Considering predicted future imbalances between water supply and demand and the growing recognition that base flow (a proxy for groundwater discharge to streams) is critical for sustaining flow in streams and rivers, there is a need to develop methods to better quantify present-day base flow across large regions. We adapted and applied the spatially referenced regression on watershed attributes (SPARROW) water quality model to assess the spatial distribution of base flow, the fraction of streamflow supported by base flow, and estimates of and potential processes contributing to the amount of base flow that is lost during in-stream transport in the Upper Colorado River Basin (UCRB). On average, 56% of the streamflow in the UCRB originated as base flow, and precipitation was identified as the dominant driver of spatial variability in base flow at the scale of the UCRB, with the majority of base flow discharge to streams occurring in upper elevation watersheds. The model estimates an average of 1.8 × 1010 m3/yr of base flow in the UCRB; greater than 80% of which is lost during in-stream transport to the Lower Colorado River Basin via processes including evapotranspiration and water diversion for irrigation. Our results indicate that surface waters in the Colorado River Basin are dependent on base flow, and that management approaches that consider groundwater and surface water as a joint resource will be needed to effectively manage current and future water resources in the Basin.
Flow based vs. demand based energy-water modelling
Rozos, Evangelos; Nikolopoulos, Dionysis; Efstratiadis, Andreas; Koukouvinos, Antonios; Makropoulos, Christos
2015-04-01
The water flow in hydro-power generation systems is often used downstream to cover other type of demands like irrigation and water supply. However, the typical case is that the energy demand (operation of hydro-power plant) and the water demand do not coincide. Furthermore, the water inflow into a reservoir is a stochastic process. Things become more complicated if renewable resources (wind-turbines or photovoltaic panels) are included into the system. For this reason, the assessment and optimization of the operation of hydro-power systems are challenging tasks that require computer modelling. This modelling should not only simulate the water budget of the reservoirs and the energy production/consumption (pumped-storage), but should also take into account the constraints imposed by the natural or artificial water network using a flow routing algorithm. HYDRONOMEAS, for example, uses an elegant mathematical approach (digraph) to calculate the flow in a water network based on: the demands (input timeseries), the water availability (simulated) and the capacity of the transmission components (properties of channels, rivers, pipes, etc.). The input timeseries of demand should be estimated by another model and linked to the corresponding network nodes. A model that could be used to estimate these timeseries is UWOT. UWOT is a bottom up urban water cycle model that simulates the generation, aggregation and routing of water demand signals. In this study, we explore the potentials of UWOT in simulating the operation of complex hydrosystems that include energy generation. The evident advantage of this approach is the use of a single model instead of one for estimation of demands and another for the system simulation. An application of UWOT in a large scale system is attempted in mainland Greece in an area extending over 130×170 km². The challenges, the peculiarities and the advantages of this approach are examined and critically discussed.
Transmission tariffs based on optimal power flow
International Nuclear Information System (INIS)
This report discusses transmission pricing as a means of obtaining optimal scheduling and dispatch in a power system. This optimality includes consumption as well as generation. The report concentrates on how prices can be used as signals towards operational decisions of market participants (generators, consumers). The main focus is on deregulated systems with open access to the network. The optimal power flow theory, with demand side modelling included, is briefly reviewed. It turns out that the marginal costs obtained from the optimal power flow gives the optimal transmission tariff for the particular load flow in case. There is also a correspondence between losses and optimal prices. Emphasis is on simple examples that demonstrate the connection between optimal power flow results and tariffs. Various cases, such as open access and single owner are discussed. A key result is that the location of the ''marketplace'' in the open access case does not influence the net economical result for any of the parties involved (generators, network owner, consumer). The optimal power flow is instantaneous, and in its standard form cannot deal with energy constrained systems that are coupled in time, such as hydropower systems with reservoirs. A simplified example of how the theory can be extended to such a system is discussed. An example of the influence of security constraints on prices is also given. 4 refs., 24 figs., 7 tabs
Paper-based flow fractionation system for preconcentration and field-flow fractionation.
Hong, Seokbin; Kwak, Rhokyun; Kim, Wonjung
2015-11-01
We present a novel paper-based flow fractionation system for preconcentration and field-flow fractionation. The paper fluidic system consisting of a straight channel connected with expansion regions can generate a fluid flow with a constant flow rate for 10 min without any external pumping devices. The flow bifurcates with a fraction ratio of up to 30 depending on the control parameters of the channel geometry. Utilizing this simple paper-based bifurcation system, we developed a continuous-flow preconcentrator and a field-flow fractionator on a paper platform. Our experimental results show that the continuous-flow preconcentrator can produce a 33-fold enrichment of the ion concentration and that the flow fractionation system successfully separates the charged dyes. Our study suggests simple, cheap ways to construct preconcentration and field-flow fractionation systems for paper-based microfluidic diagnostic devices. This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIP) (NRF-2015R1A2A2A04006181).
C++ based design flow for reconfigurable image processing systems
Beun, R.; Karkowski, I.; Ditzel, M.
2007-01-01
In this paper a new hardware-software co-design flow for FPGA based image processing systems is described. This flow is fully C++ based and allows specification, verification and semi-automatic generation of all necessary software and hardware components. It allows the involvement of algorithm devel
Debris Flow Hazard Assessment Based on Support Vector Machine
Institute of Scientific and Technical Information of China (English)
YUAN Lifeng; ZHANG Youshui
2006-01-01
Seven factors, including the maximum volume of once flow , occurrence frequency of debris flow , watershed area , main channel length , watershed relative height difference , valley incision density and the length ratio of sediment supplement are chosen as evaluation factors of debris flow hazard degree. Using support vector machine (SVM) theory, we selected 259 basic data of 37 debris flow channels in Yunnan Province as learning samples in this study. We create a debris flow hazard assessment model based on SVM. The model was validated though instance applications and showed encouraging results.
Willatzen, M
2004-05-01
A comparison between three mathematical models frequently used in flow acoustics is presented and discussed with respect to ultrasonic flow-meter performance based on the transit-time method. The flow-meter spoolpiece geometry is assumed to be a cylindrical pipe. Semi-analytical calculations employing the Frobenius power series expansion method are shown for the cases of a constant-, linear-, parabolic-, and cubic-flow profiles although the Frobenius method presented can be applied to any smooth flow profile. It is shown that the so-called deviation of measurement, often used as a measure of the flow-meter accuracy, is strongly dependent on the acoustic mode excited and the flow profile. Furthermore, differences with respect to deviation of measurement results exist among the three mathematical models analyzed. PMID:15110538
Agent Based Reasoning in Multilevel Flow Modeling
DEFF Research Database (Denmark)
Lind, Morten; Zhang, Xinxin
2012-01-01
Multilevel Flow Modeling (MFM) is a modeling method used for modeling complex industrial plant. Currently, MFM is supported with a standalone software tool called MFM Workbench, which is equipped with causal-relation analysis and other functionalities. The aim of this paper is to offer a new design...
Effect of passive flow-control devices on turbulent low-speed base flow
Heidari-Miandoab, Farid
Some configurations of blunt trailing-edge airfoils are known to have a lower pressure drag compared to sharp trailing-edge airfoils. However, this advantage in addition to the structural advantage of a thick trailing-edge airfoil is offset by its high base drag. At subsonic velocities, this is attributed to the low-pressure base flow dominated by a Karman vortex street. In the limiting case, the steady separated flow over a rearward-facing step is attained if the periodically shed vortices from a blunt trailing-edge are suppressed by the addition of a base spiltter-plate. Experimental studies in the Old Dominion University Low-Speed Closed-Circuit Wind Tunnel were conducted to examine the effect of several passive flow-control devices such as Wheeler doublets and wishbone vortex generators, longitudinal surface grooves, base cavities, and serrations on the characteristics of two- and three-dimensional base flows. Flow over flat-plate airfoil and rearward-facing step models was studied in the turbulent incompressible subsonic flow regime. Models with trailing-edge and step-sweep angles of 0, 30, and 45 degrees with respect to the crossflow direction were considered. Constant-temperature hot-wire anemometry, infrared surface thermography, and pitot-static probes were used to conduct flow measurements. The parameters measured included vortex shedding frequency, convective heat-transfer rates, base pressure, and flow reattachment distance. Surveys of mean velocity profiles in the wake were also conducted. Results have shown that most of the flow control devices tested increased the base pressure of the 2-D and 3-D flat-plate airfoils. Use of longitudinal surface grooves resulted in shorter flow reattachment distances and higher convective heat transfer rates downstream of the 2-D rearward-facing steps.
Ricci Flow-based Spherical Parameterization and Surface Registration
Chen, X.; He, H.; G. Zou; Zhang, X; Gu, X.; Hua, J
2013-01-01
This paper presents an improved Euclidean Ricci flow method for spherical parameterization. We subsequently invent a scale space processing built upon Ricci energy to extract robust surface features for accurate surface registration. Since our method is based on the proposed Euclidean Ricci flow, it inherits the properties of Ricci flow such as conformality, robustness and intrinsicalness, facilitating efficient and effective surface mapping. Compared with other surface registration methods u...
Flow properties of water-based drilling fluids
Kristensen, Aleksander
2013-01-01
The objective of this master thesis was to investigate the flow properties of water based drilling fluids, utilizing measurements in both the micro and macro scale. The research was performed on two realistic drilling fluids by the use of a viscometer, a rheometer and a realistic flow loop, where the latter represents the macro scale. The research outcome could possibly improve the understanding of flow behavior in wellbores, and remove uncertainties associated with annular friction. The two...
TGV-based flow estimation for 4D leukocyte transmigration
Frerking, L.; M. Burger; Vestweber, D.; Brune, C.; Louis, Alfred K.; Arridge, Simon; Rundell, Bill
2014-01-01
The aim of this paper is to track transmigrating leukocytes via TGV flow estimation. Recent results have shown the advantages of the nonlinear and higher order terms of TGV regularizers, especially in static models for denoising and medical reconstruction. We present TGV-based models for flow estimation with the goal to get an exact recovery of simple intracellular and extracellular flows, as well as its implication on realistic tracking situations for transmigration through barriers. To stud...
Adaptive muffler based on controlled flow valves.
Šteblaj, Peter; Čudina, Mirko; Lipar, Primož; Prezelj, Jurij
2015-06-01
An adaptive muffler with a flexible internal structure is considered. Flexibility is achieved using controlled flow valves. The proposed adaptive muffler is able to adapt to changes in engine operating conditions. It consists of a Helmholtz resonator, expansion chamber, and quarter wavelength resonator. Different combinations of the control valves' states at different operating conditions define the main working principle. To control the valve's position, an active noise control approach was used. With the proposed muffler, the transmission loss can be increased by more than 10 dB in the selected frequency range. PMID:26093462
Schwarz-based algorithms for compressible flows
Energy Technology Data Exchange (ETDEWEB)
Tidriri, M.D. [ICASE, Hampton, VA (United States)
1996-12-31
To compute steady compressible flows one often uses an implicit discretization approach which leads to a large sparse linear system that must be solved at each time step. In the derivation of this system one often uses a defect-correction procedure, in which the left-hand side of the system is discretized with a lower order approximation than that used for the right-hand side. This is due to storage considerations and computational complexity, and also to the fact that the resulting lower order matrix is better conditioned than the higher order matrix. The resulting schemes are only moderately implicit. In the case of structured, body-fitted grids, the linear system can easily be solved using approximate factorization (AF), which is among the most widely used methods for such grids. However, for unstructured grids, such techniques are no longer valid, and the system is solved using direct or iterative techniques. Because of the prohibitive computational costs and large memory requirements for the solution of compressible flows, iterative methods are preferred. In these defect-correction methods, which are implemented in most CFD computer codes, the mismatch in the right and left hand side operators, together with explicit treatment of the boundary conditions, lead to a severely limited CFL number, which results in a slow convergence to steady state aerodynamic solutions. Many authors have tried to replace explicit boundary conditions with implicit ones. Although they clearly demonstrate that high CFL numbers are possible, the reduction in CPU time is not clear cut.
The Flow Field Analysis and Flow Calculation of Ultrasonic Flowmeter Based on the Fluent Software
Ling Guo; Yue Sun; Ling Liu; Zhixi Shen; Ruizhen Gao; Kai (Jackie) Zhao
2014-01-01
We can build the three-dimensional structure model based on the Gambit software and achieve the distribution of flow field in the pipe and reflux flow condition at the position of transducer in regard to the real position of transducer according to the Fluent software. Under the framework, define the reflux length based on the distance of reflux along the channel and evaluate the effect of reflux on flow field. Then we can correct the power factor with the transmission speed difference method...
Abnormal traffic flow data detection based on wavelet analysis
Directory of Open Access Journals (Sweden)
Xiao Qian
2016-01-01
Full Text Available In view of the traffic flow data of non-stationary, the abnormal data detection is difficult.proposed basing on the wavelet analysis and least squares method of abnormal traffic flow data detection in this paper.First using wavelet analysis to make the traffic flow data of high frequency and low frequency component and separation, and then, combined with least square method to find abnormal points in the reconstructed signal data.Wavelet analysis and least square method, the simulation results show that using wavelet analysis of abnormal traffic flow data detection, effectively reduce the detection results of misjudgment rate and false negative rate.
Calculation of the debris flow concentration based on clay content
Institute of Scientific and Technical Information of China (English)
CHEN; Ningsheng; CUI; Peng; LIU; Zhonggang; WEI; Fangqiang
2003-01-01
The debris flow clay content has very tremendous influence on its concentration (γC). It is reported that the concentration can be calculated by applying the relative polynomial based on the clay content. Here one polynomial model and one logarithm model to calculate the concentration based on the clay content for both the ordinary debris flow and viscous debris flow are obtained. The result derives from the statistics and analysis of the relationship between the debris flow concentrations and clay content in 45 debris flow sites located in the southwest of China. The models can be applied for the concentration calculation to those debris flows that are impossible to observe. The models are available to calculate the debris flow concentration, the principles of which are in the clay content affecting on the debris flow formation, movement and suspending particle diameter. The mechanism of the relationship of the clay content and concentration is clear and reliable. The debris flow is usually of micro-viscous when the clay content is low (<3%), by analyzing the developing tendency on the basics of the relationship between the clay content and debris flow concentration. Indeed, the less the clay content, the less the concentration for most debris flows. The debris flow tends to become the water rock flow or the hyperconcentrated flow with the clay content decrease. Through statistics it is apt to transform the soil into the viscous debris flow when the clay content of ranges is in 3%-18%. Its concentration increases with the increasing of the clay content when the clay content is between 5% and 10%. But the value decreases with the increasing of the clay content when the clay content is between 10% and 18%. It is apt to transform the soil into the mudflow, when the clay content exceeds 18%. The concentration of the mudflow usually decreases with the increase of the clay content, and this developing tendency reverses to that of the micro-viscous debris flow. There is
Agent-Based Collaborative Traffic Flow Management Project
National Aeronautics and Space Administration — We propose agent-based game-theoretic approaches for simulation of strategies involved in multi-objective collaborative traffic flow management (CTFM). Intelligent...
Base-flow index grid for the conterminous United States
U.S. Geological Survey, Department of the Interior — This 1-kilometer raster (grid) dataset for the conterminous United States was created by interpolating base-flow index (BFI) values estimated at U.S. Geological...
TRAFFIC FLOW MODEL BASED ON CELLULAR AUTOMATION WITH ADAPTIVE DECELERATION
Shinkarev, A. A.
2016-01-01
This paper describes continuation of the authors’ work in the field of traffic flow mathematical models based on the cellular automata theory. The refactored representation of the multifactorial traffic flow model based on the cellular automata theory is used for a representation of an adaptive deceleration step implementation. The adaptive deceleration step in the case of a leader deceleration allows slowing down smoothly but not instantly. Concepts of the number of time steps without confli...
Sparse sensing and DMD based identification of flow regimes and bifurcations in complex flows
Kramer, Boris; Boufounos, Petros; Benosman, Mouhacine; Nabi, Saleh
2015-01-01
We present a sparse sensing and Dynamic Mode Decomposition (DMD) based framework to identify flow regimes and bifurcations in complex thermo-fluid systems. Motivated by real time sensing and control of thermal fluid flows in buildings and equipment, we apply this method to a Direct Numerical Simulation (DNS) data set of a 2D laterally heated cavity, spanning several flow regimes ranging from steady to chaotic flow. We exploit the incoherence exhibited among the data generated by different regimes, which persists even if the number of measurements is very small compared to the dimension of the DNS data. We demonstrate that the DMD modes and eigenvalues capture the main temporal and spatial scales in the dynamics belonging to different regimes, and use this information to improve the classification performance of our algorithm. The coarse state reconstruction obtained by our regime identification algorithm can enable robust performance of low order models of flows for state estimation and control.
FLDA: Latent Dirichlet Allocation Based Unsteady Flow Analysis.
Hong, Fan; Lai, Chufan; Guo, Hanqi; Shen, Enya; Yuan, Xiaoru; Li, Sikun
2014-12-01
In this paper, we present a novel feature extraction approach called FLDA for unsteady flow fields based on Latent Dirichlet allocation (LDA) model. Analogous to topic modeling in text analysis, in our approach, pathlines and features in a given flow field are defined as documents and words respectively. Flow topics are then extracted based on Latent Dirichlet allocation. Different from other feature extraction methods, our approach clusters pathlines with probabilistic assignment, and aggregates features to meaningful topics at the same time. We build a prototype system to support exploration of unsteady flow field with our proposed LDA-based method. Interactive techniques are also developed to explore the extracted topics and to gain insight from the data. We conduct case studies to demonstrate the effectiveness of our proposed approach. PMID:26356968
A PRESSURE-BASED ALGORITHM FOR CAVITATING FLOW COMPUTATIONS
Institute of Scientific and Technical Information of China (English)
ZHANG Ling-xin; ZHAO Wei-guo; SHAO Xue-ming
2011-01-01
A pressure-based algorithm for the prediction of cavitating flows is presented. The algorithm employs a set of equations including the Navier-Stokes equations and a cavitation model explaining the phase change between liquid and vapor. A pressure-based method is used to construct the algorithm and the coupling between pressure and velocity is considered. The pressure correction equation is derived from a new continuity equation which employs a source term related to phase change rate instead of the material derivative of density Dp/Dt.Thispressure-based algorithm allows for the computation of steady or unsteady,2-Dor 3-D cavitating flows. Two 2-D cases, flows around a flat-nose cylinder and around a NACA0015 hydrofoil, are simulated respectively, and the periodic cavitation behaviors associated with the re-entrant jets are captured. This algorithm shows good capability of computating time-dependent cavitating flows.
flowCL: ontology-based cell population labelling in flow cytometry
Courtot, Mélanie; Meskas, Justin; Diehl, Alexander D.; Droumeva, Radina; Gottardo, Raphael; Jalali, Adrin; Taghiyar, Mohammad Jafar; Maecker, Holden T.; McCoy, J. Philip; Ruttenberg, Alan; Scheuermann, Richard H.; Brinkman, Ryan R.
2015-01-01
Motivation: Finding one or more cell populations of interest, such as those correlating to a specific disease, is critical when analysing flow cytometry data. However, labelling of cell populations is not well defined, making it difficult to integrate the output of algorithms to external knowledge sources. Results: We developed flowCL, a software package that performs semantic labelling of cell populations based on their surface markers and applied it to labelling of the Federation of Clinical Immunology Societies Human Immunology Project Consortium lyoplate populations as a use case. Conclusion: By providing automated labelling of cell populations based on their immunophenotype, flowCL allows for unambiguous and reproducible identification of standardized cell types. Availability and implementation: Code, R script and documentation are available under the Artistic 2.0 license through Bioconductor (http://www.bioconductor.org/packages/devel/bioc/html/flowCL.html). Contact: rbrinkman@bccrc.ca Supplementary information: Supplementary data are available at Bioinformatics online. PMID:25481008
SIMULATION OF LOW-CONCENTRATION SEDIMENT-LADEN FLOW BASED ON TWO-PHASE FLOW THEORY
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Low concentration sediment-laden flow is usually involved in water conservancy, environmental protection, navigation and so on. In this article, a mathematical model for low-concentration sediment-laden flow was suggested based on the two-phase flow theory, and a solving scheme for the mathematical model in curvilinear grids was worked out. The observed data in the Zhang River in China was used for the verification of the model, and the calculated results of the water level, velocity and river bed deformation are in agreement with the observed ones.
A network-flow based valve-switching aware binding algorithm for flow-based microfluidic biochips
DEFF Research Database (Denmark)
Tseng, Kai-Han; You, Sheng-Chi; Minhass, Wajid Hassan;
2013-01-01
-flow based resource binding algorithm based on breadth-first search (BFS) and minimum cost maximum flow (MCMF) in architectural-level synthesis. The experimental results show that our methodology not only makes significant reduction of valve-switching activities but also diminishes the application completion...... biochip needs more chip-integrated micro-valves, i.e., the basic unit of fluid-handling functionality, to manipulate the fluid flow for biochemical applications. Moreover, frequent switching of micro-valves results in decreased reliability. To minimize the valve-switching activities, we develop a network...
Performance analysis of vortex based mixers for confined flows
Buschhagen, Timo
The hybrid rocket is still sparsely employed within major space or defense projects due to their relatively poor combustion efficiency and low fuel grain regression rate. Although hybrid rockets can claim advantages in safety, environmental and performance aspects against established solid and liquid propellant systems, the boundary layer combustion process and the diffusion based mixing within a hybrid rocket grain port leaves the core flow unmixed and limits the system performance. One principle used to enhance the mixing of gaseous flows is to induce streamwise vorticity. The counter-rotating vortex pair (CVP) mixer utilizes this principle and introduces two vortices into a confined flow, generating a stirring motion in order to transport near wall media towards the core and vice versa. Recent studies investigated the velocity field introduced by this type of swirler. The current work is evaluating the mixing performance of the CVP concept, by using an experimental setup to simulate an axial primary pipe flow with a radially entering secondary flow. Hereby the primary flow is altered by the CVP swirler unit. The resulting setup therefore emulates a hybrid rocket motor with a cylindrical single port grain. In order to evaluate the mixing performance the secondary flow concentration at the pipe assembly exit is measured, utilizing a pressure-sensitive paint based procedure.
Radar Based Flow and Water Level Forecasting in Sewer Systems
DEFF Research Database (Denmark)
Thorndahl, Søren; Rasmussen, Michael R.; Grum, M.;
2009-01-01
This paper describes the first radar based forecast of flow and/or water level in sewer systems in Denmark. The rainfall is successfully forecasted with a lead time of 1-2 hours, and flow/levels are forecasted an additional ½-1½ hours using models describing the behaviour of the sewer system. Both...... radar data and flow/water level model are continuously updated using online rain gauges and online in-sewer measurements, in order to make the best possible predictions. The project show very promising results, and show large potentials, exploiting the existing water infrastructure in future climate...
Elliptic flow based on a relativistic hydrodynamic model
International Nuclear Information System (INIS)
Based on the (3+1)-dimensional hydrodynamic model, the space-time evolution of hot and dense nuclear matter produced in non-central relativistic heavy-ion collisions is discussed. The elliptic flow parameter v2 is obtained by Fourier analysis of the azimuthal distribution of pions and protons which are emitted from the freeze-out hypersurface. As a function of rapidity, the pion and proton elliptic flow parameters both have a peak at midrapidity. (author)
Control volume based modelling of compressible flow in reciprocating machines
DEFF Research Database (Denmark)
Andersen, Stig Kildegård; Thomsen, Per Grove; Carlsen, Henrik
2004-01-01
An approach to modelling unsteady compressible flow that is primarily one dimensional is presented. The approach was developed for creating distributed models of machines with reciprocating pistons but it is not limited to this application. The approach is based on the integral form of the unstea...... presented. The capabilities of the modelling approach are illustrated with a solution to a Stirling engine model that provides results in good agreement with experimental data. Keywords: Simulation, compressible flow, one dimensional, control volume....
Traffic Flow Detection Based on Wireless Sensor Network
Directory of Open Access Journals (Sweden)
Bao-juan Liang
2013-08-01
Full Text Available Detecting traffic flow by in-road inductive loop is the most common methods, but inductive loop is physically large, it is hard to install and maintain, also the classification rate is low. The inductive loops cannot communicate with each other, so they cannot share traffic data with each other. The wireless sensor network has these features: real-time, fault tolerance, scalability and coordination. Applying wireless sensor network into traffic area for traffic flow detection is easier to install, and provide real-time traffic flow for coordinate traffic control, also it can improve the classification rate. A lot of researchers applied the wireless sensor network for traffic flow detection, but no one referred to the coordinate traffic flow detection method. In this paper, we provided a coordinate traffic flow detection framework. Based on this framework, we set up a simple traffic flow detection platform by wireless sensor nodes produced by cross box company to verify this method. We selected four periods, for each period, we got a more than 90% classification rate.
Resolution Enhancement by Incorporating Segmentation-based Optical Flow Estimation
Directory of Open Access Journals (Sweden)
Osama A. Omer
2012-06-01
Full Text Available In this paper, the problem of recovering a high-resolution frame from a sequence of low-resolution frames is considered. High-resolution reconstruction process highly depends on image registration step. Typical resolution enhancement techniques use global motion estimation technique. However, in general, video frames cannot be related through global motion due to the arbitrary individual pixel movement between frame pairs. To overcome this problem, we propose to employ segmentation-based optical flow estimation technique for motion estimation with a modified model for frame alignment. To do that, we incorporate the segmentation with the optical flow estimation in two-stage optical flow estimation. In the first stage, a reference image is segmented into homogeneous regions. In the second stage, the optical flow is estimated for each region rather than pixels or blocks. Then, the frame alignment is accomplished by optimizing the cost function that consists of L1-norm of the difference between the interpolated low-resolution (LR frames and the simulated LR frames. The experimental results demonstrate that using segmentation-based optical flow estimation in motion estimation step with the modified alignment model works better than other motion models such as affine, and conventional optical flow motion models.
Modelling of two-phase flow based on separation of the flow according to velocity
International Nuclear Information System (INIS)
The thesis concentrates on the development work of a physical one-dimensional two-fluid model that is based on Separation of the Flow According to Velocity (SFAV). The conventional way to model one-dimensional two-phase flow is to derive conservation equations for mass, momentum and energy over the regions occupied by the phases. In the SFAV approach, the two-phase mixture is divided into two subflows, with as distinct average velocities as possible, and momentum conservation equations are derived over their domains. Mass and energy conservation are treated equally with the conventional model because they are distributed very accurately according to the phases, but momentum fluctuations follow better the flow velocity. Submodels for non-uniform transverse profile of velocity and density, slip between the phases within each subflow and turbulence between the subflows have been derived. The model system is hyperbolic in any sensible flow conditions over the whole range of void fraction. Thus, it can be solved with accurate numerical methods utilizing the characteristics. The characteristics agree well with the used experimental data on two-phase flow wave phenomena Furthermore, the characteristics of the SFAV model are as well in accordance with their physical counterparts as of the best virtual-mass models that are typically optimized for special flow regimes like bubbly flow. The SFAV model has proved to be applicable in describing two-phase flow physically correctly because both the dynamics and steady-state behaviour of the model has been considered and found to agree well with experimental data This makes the SFAV model especially suitable for the calculation of fast transients, taking place in versatile form e.g. in nuclear reactors
Modelling of two-phase flow based on separation of the flow according to velocity
Energy Technology Data Exchange (ETDEWEB)
Narumo, T. [VTT Energy, Espoo (Finland). Nuclear Energy
1997-12-31
The thesis concentrates on the development work of a physical one-dimensional two-fluid model that is based on Separation of the Flow According to Velocity (SFAV). The conventional way to model one-dimensional two-phase flow is to derive conservation equations for mass, momentum and energy over the regions occupied by the phases. In the SFAV approach, the two-phase mixture is divided into two subflows, with as distinct average velocities as possible, and momentum conservation equations are derived over their domains. Mass and energy conservation are treated equally with the conventional model because they are distributed very accurately according to the phases, but momentum fluctuations follow better the flow velocity. Submodels for non-uniform transverse profile of velocity and density, slip between the phases within each subflow and turbulence between the subflows have been derived. The model system is hyperbolic in any sensible flow conditions over the whole range of void fraction. Thus, it can be solved with accurate numerical methods utilizing the characteristics. The characteristics agree well with the used experimental data on two-phase flow wave phenomena Furthermore, the characteristics of the SFAV model are as well in accordance with their physical counterparts as of the best virtual-mass models that are typically optimized for special flow regimes like bubbly flow. The SFAV model has proved to be applicable in describing two-phase flow physically correctly because both the dynamics and steady-state behaviour of the model has been considered and found to agree well with experimental data This makes the SFAV model especially suitable for the calculation of fast transients, taking place in versatile form e.g. in nuclear reactors. 45 refs. The thesis includes also five previous publications by author.
Characterization of base roughness for granular chute flows
Jing, Lu; Leung, Y F; Sobral, Y D
2016-01-01
Base roughness plays an important role to the dynamics of granular flows but is yet poorly understood due to the difficulty of its quantification. For a bumpy base made by spheres, at least two factors should be considered to characterize its geometric roughness, namely the size ratio of base- to flow-particles and the packing of base particles. In this paper, we propose a definition of base roughness, Ra, which is a function of both the size ratio and the packing arrangement of base particles. The function is generalized for random and regular packing of multi-layered spheres, where the range of possible values of Ra is studied, along with the optimal values to create maximum base roughness. The new definition is applied to granular flows down chute in both two- and three-dimensional configurations. It is proven to be a good indicator of slip condi- tion, and a transition occurs from slip to non-slip condition as Ra increases. Critical values of Ra are identified for the construction of a non-slip base. The ...
Video Texture Synthesis Based on Flow-Like Stylization Painting
Wenhua, Qian; Dan, Xu; Kun, Yue; Zheng, Guan
2014-01-01
The paper presents an NP-video rendering system based on natural phenomena. It provides a simple nonphotorealistic video synthesis system in which user can obtain a flow-like stylization painting and infinite video scene. Firstly, based on anisotropic Kuwahara filtering in conjunction with line integral convolution, the phenomena video scene can be rendered to flow-like stylization painting. Secondly, the methods of frame division, patches synthesis, will be used to synthesize infinite playing video. According to selection examples from different natural video texture, our system can generate stylized of flow-like and infinite video scenes. The visual discontinuities between neighbor frames are decreased, and we also preserve feature and details of frames. This rendering system is easy and simple to implement. PMID:25133253
Modal Decomposition of Synthetic Jet Flow Based on CFD Computation
Directory of Open Access Journals (Sweden)
Hyhlík Tomáš
2015-01-01
Full Text Available The article analyzes results of numerical simulation of synthetic jet flow using modal decomposition. The analyzes are based on the numerical simulation of axisymmetric unsteady laminar flow obtained using ANSYS Fluent CFD code. Three typical laminar regimes are compared from the point of view of modal decomposition. The first regime is without synthetic jet creation with Reynolds number Re = 76 and Stokes number S = 19.7. The second studied regime is defined by Re = 145 and S = 19.7. The third regime of synthetic jet work is regime with Re = 329 and S = 19.7. Modal decomposition of obtained flow fields is done using proper orthogonal decomposition (POD where energetically most important modes are identified. The structure of POD modes is discussed together with classical approach based on phase averaged velocities.
RELIABLE VALIDATION BASED ON OPTICAL FLOW VISUALIZATION FOR CFD SIMULATIONS
Institute of Scientific and Technical Information of China (English)
姜宗林
2003-01-01
A reliable validation based on the optical flow visualization for numerical simulations of complex flowfields is addressed in this paper.Several test cases,including two-dimensional,axisymmetric and three-dimensional flowfields,were presented to demonstrate the effectiveness of the validation and gain credibility of numerical solutions of complex flowfields.In the validation,images of these flowfields were constructed from numerical results based on the principle of the optical flow visualization,and compared directly with experimental interferograms.Because both experimental and numerical results are of identical physical representation,the agreement between them can be evaluated effectively by examining flow structures as well as checking discrepancies in density.The study shows that the reliable validation can be achieved by using the direct comparison between numerical and experiment results without any loss of accuracy in either of them.
Video Texture Synthesis Based on Flow-Like Stylization Painting
Directory of Open Access Journals (Sweden)
Qian Wenhua
2014-01-01
Full Text Available The paper presents an NP-video rendering system based on natural phenomena. It provides a simple nonphotorealistic video synthesis system in which user can obtain a flow-like stylization painting and infinite video scene. Firstly, based on anisotropic Kuwahara filtering in conjunction with line integral convolution, the phenomena video scene can be rendered to flow-like stylization painting. Secondly, the methods of frame division, patches synthesis, will be used to synthesize infinite playing video. According to selection examples from different natural video texture, our system can generate stylized of flow-like and infinite video scenes. The visual discontinuities between neighbor frames are decreased, and we also preserve feature and details of frames. This rendering system is easy and simple to implement.
Visualization of pulsatile flow for magnetic nanoparticle based therapies
Wentzel, Andrew; Yecko, Philip
2015-11-01
Pulsatile flow of blood through branched, curved, stenosed, dilated or otherwise perturbed vessels is more complex than flow through a straight, uniform and rigid tube. In some magnetic hyperthermia and magnetic chemo-therapies, localized regions of magnetic nanoparticle laden fluid are deliberately formed in blood vessels and held in place by magnetic fields. The effect of localized magnetic fluid regions on blood flow and the effect of the pulsatile blood flow on such magnetic fluid regions are poorly understood and difficult to examine in vivo or by numerical simulation. We present a laboratory model that facilitates both dye tracer and particle imaging velocimetry (PIV) studies of pulsatile flow of water through semi-flexible tubes in the presence of localized magnetic fluid regions. Results on the visualization of flows over a range of Reynolds and Womersley numbers and for several different (water-based) ferrofluids are compared for straight and curved vessels and for different magnetic localization strategies. These results can guide the design of improved magnetic cancer therapies. Support from the William H. Sandholm Program of Cooper Union's Kanbar Center for Biomedical Engineering is gratefully acknowledged.
Adjoint-based Optimal Flow Control for Compressible DNS
Otero, J Javier; Sandberg, Richard D
2016-01-01
A novel adjoint-based framework oriented to optimal flow control in compressible direct numerical simulations is presented. Also, a new formulation of the adjoint characteristic boundary conditions is introduced, which enhances the stability of the adjoint simulations. The flow configuration chosen as a case study consists of a two dimensional open cavity flow with aspect ratio $L/H=3$ and Reynolds number $Re=5000$. This flow configuration is of particular interest, as the turbulent and chaotic nature of separated flows pushes the adjoint approach to its limit. The target of the flow actuation, defined as cost, is the reduction of the pressure fluctuations at the sensor location. To exploit the advantages of the adjoint method, a large number of control parameters is used. The control consists of an actuating sub-domain where a two-dimensional body force is applied at every point within the sub-volume. This results in a total of $2.256 \\cdot 10^6$ control parameters. The final actuation achieved a successful ...
Towards Separation of Concerns in Flow-Based Programming
DEFF Research Database (Denmark)
Zarrin, Bahram; Baumeister, Hubert
2015-01-01
Flow-Based Programming (FBP) is a programming paradigm that models software systems as a directed graph of predefined processes which run asynchronously and exchange data through input and output ports. FBP decomposes software systems into a network of processes. However there are concerns...
Percussive and Proboscis Based Lunar Heat Flow Probes
Mumm, E.; Zacny, K.; Kumar, N.
2009-12-01
The subsurface temperature of the Moon is strongly influenced by the diurnal, annual, and precession fluctuations of the insolation. Therefore, to measure the heat flow, the probe has to be inserted to a depth of at least 3m. There are a number of ways the heat flow probe can be deployed. These methods differ in many ways such as simplicity and mass of the deployment system, power required to deploy it, extent of thermal isolation between temperature sensors and between sensors themselves and surface system (deployment system, lander, electronics box etc), thermal sensor placement within the hole (radiative as opposed to conducive coupling), and methods of deployment. The percussive based heat flow probe utilizes a percussive approach to drive a small diameter (20mm) cone penetrometer to >3 meter depths, deploying ring-like thermal sensors every 30 cm. It leaves only small sensors in the borehole, maximizing measurement sensitivity by minimizing thermal coupling from the lander to the electrical tether. The proboscis based heat flow probe utilizes a pneumatic (gas) approach to lower the heat flow probe, a lenticular tape, to 3 meters. The system offers extremely low mass, volume, and simple deployment.
Polyaffine parametrization of image registration based on geodesic flows
DEFF Research Database (Denmark)
Hansen, Michael Sass; Thorup, Signe Strann; Warfield, Simon K.
2012-01-01
Image registration based on geodesic flows has gained much popularity in recent years. We describe a novel parametrization of the velocity field in a stationary flow equation. We show that the method offers both precision, flexibility, and simplicity of evaluation. With our representation, which ...... of geodesic shooting for computational anatomy. We avoid to do warp field convolution by interpolation in a dense field, we can easily calculate warp derivatives in a reference frame of choice, and we can consequently avoid interpolation in the image space altogether....
A particle-based method for granular flow simulation
Chang, Yuanzhang
2012-03-16
We present a new particle-based method for granular flow simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the momentum governing equation to handle the friction of granular materials. Viscosity force is also added to simulate the dynamic friction for the purpose of smoothing the velocity field and further maintaining the simulation stability. Benefiting from the Lagrangian nature of the SPH method, large flow deformation can be well handled easily and naturally. In addition, a signed distance field is also employed to enforce the solid boundary condition. The experimental results show that the proposed method is effective and efficient for handling the flow of granular materials, and different kinds of granular behaviors can be well simulated by adjusting just one parameter. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.
An engineering based approach for hydraulic computations in river flows
Di Francesco, S.; Biscarini, C.; Pierleoni, A.; Manciola, P.
2016-06-01
This paper presents an engineering based approach for hydraulic risk evaluation. The aim of the research is to identify a criteria for the choice of the simplest and appropriate model to use in different scenarios varying the characteristics of main river channel. The complete flow field, generally expressed in terms of pressure, velocities, accelerations can be described through a three dimensional approach that consider all the flow properties varying in all directions. In many practical applications for river flow studies, however, the greatest changes occur only in two dimensions or even only in one. In these cases the use of simplified approaches can lead to accurate results, with easy to build and faster simulations. The study has been conducted taking in account a dimensionless parameter of channels (ratio of curvature radius and width of the channel (R/B).
Cycle-flow-based module detection in directed recurrence networks
Banisch, Ralf; Djurdjevac Conrad, Nataša
2014-12-01
We present a new cycle-flow-based method for finding fuzzy partitions of weighted directed networks coming from time series data. We show that this method overcomes essential problems of most existing clustering approaches, which tend to ignore important directional information by considering only one-step, one-directional node connections. Our method introduces a novel measure of communication between nodes using multi-step, bidirectional transitions encoded by a cycle decomposition of the probability flow. Symmetric properties of this measure enable us to construct an undirected graph that captures the information flow of the original graph seen by the data and apply clustering methods designed for undirected graphs. Finally, we demonstrate our algorithm by analyzing earthquake time series data, which naturally induce (time-)directed networks.
Flow-based reputation: more than just ranking
Simone, Antonino; Zannone, Nicola
2012-01-01
The last years have seen a growing interest in collaborative systems like electronic marketplaces and P2P file sharing systems where people are intended to interact with other people. Those systems, however, are subject to security and operational risks because of their open and distributed nature. Reputation systems provide a mechanism to reduce such risks by building trust relationships among entities and identifying malicious entities. A popular reputation model is the so called flow-based model. Most existing reputation systems based on such a model provide only a ranking, without absolute reputation values; this makes it difficult to determine whether entities are actually trustworthy or untrustworthy. In addition, those systems ignore a significant part of the available information; as a consequence, reputation values may not be accurate. In this paper, we present a flow-based reputation metric that gives absolute values instead of merely a ranking. Our metric makes use of all the available information....
Fluid experimental flow estimation based on an optical-flow scheme
Energy Technology Data Exchange (ETDEWEB)
Corpetti, T. [Cemagref 17, Rennes (France); Maison de la Recherche, Laboratoire COSTEL UMR 6554 LETG, Rennes Cedex (France); Heitz, D.; Arroyo, G.; Santa-Cruz, A. [Cemagref 17, Rennes (France); Memin, E. [Universitaire de Beaulieu, IRISA/INRIA Campus, Rennes Cedex (France)
2006-01-01
We present in this paper a novel approach dedicated to the measurement of velocity in fluid experimental flows through image sequences. Unlike most of the methods based on particle image velocimetry (PIV) approaches used in that context, the proposed technique is an extension of ''optical-flow'' schemes used in the computer vision community, which includes a specific enhancement for fluid mechanics applications. The method we propose enables to provide accurate dense motion fields. It includes an image based integrated version of the continuity equation. This model is associated to a regularization functional, which preserve divergence and vorticity blobs of the motion field. The method was applied on synthetic images and on real experiments carried out to allow a thorough comparison with a state-of-the-art PIV method in conditions of strong local free shear. (orig.)
Eng, K.; Milly, P.C.D.
2007-01-01
Base flow recession information is helpful for regional estimation of low-flow characteristics. However, analyses that exploit such information generally require a continuous record of streamflow at the estimation site to characterize base flow recession. Here we propose a simple method for characterizing base flow recession at low-flow partial record stream gauges (i.e., sites with very few streamflow measurements under low-streamflow conditions), and we use that characterization as the basis for a practical new approach to low-flow regression. In a case study the introduction of a base flow recession time constant, estimated from a single pair of strategically timed streamflow measurements, approximately halves the root-mean-square estimation error relative to that of a conventional drainage area regression. Additional streamflow measurements can be used to reduce the error further.
The Flow Field Analysis and Flow Calculation of Ultrasonic Flowmeter Based on the Fluent Software
Directory of Open Access Journals (Sweden)
Ling Guo
2014-01-01
Full Text Available We can build the three-dimensional structure model based on the Gambit software and achieve the distribution of flow field in the pipe and reflux flow condition at the position of transducer in regard to the real position of transducer according to the Fluent software. Under the framework, define the reflux length based on the distance of reflux along the channel and evaluate the effect of reflux on flow field. Then we can correct the power factor with the transmission speed difference method in the ideal condition and obtain the matching expression of power correction factor according to the practice model. In the end, analyze the simulation experience and produce the sample table based on the proposed model. The comparative analysis of test results and simulation results demonstrates the validity and feasibility of the proposed simulation method. The research in this paper will lay a foundation for further study on the optimization of ultrasonic flowmeter, enhance the measurement precision, and extend the application of engineering.
Vortex-based spatiotemporal characterization of nonlinear flows
Byrne, Gregory A.
Although the ubiquity of vortices in nature has been recognized by artists for over seven centuries, it was the work of artist and scientist Leonardo da Vinci that provided the monumental transition from an aesthetic form to a scientific tool. DaVinci used vortices to describe the motions he observed in air currents, flowing water and blood flow in the human heart. Five centuries later, the Navier-Stokes equations allow us to recreate the swirling motions of fluid observed in nature. Computational fluid dynamic (CFD) simulations have provided a lens through which to study the role of vortices in a wide variety of modern day applications. The research summarized below represents an effort to look through this lens and bring into focus the practical use of vortices in describing nonlinear flows. Vortex-based spatiotemporal characterizations are obtained using two specific mathematical tools: vortex core lines (VCL) and proper orthogonal decomposition (POD). By applying these tools, we find that vortices continue to provide new insights in the realm of biofluids, urban flows and the phase space of dynamical systems. The insights we have gained are described in this thesis. Our primary focus is on biofluids. Specifically, we seek to gain new insights into the connection between vortices and vascular diseases in order to provide more effective methods for clinical diagnosis and treatment. We highlight several applications in which VCL and POD are used to characterize the flow conditions in a heart pump, identify stenosis in carotid arteries and validate numerical models against PIV-based experimental data. Next, we quantify the spatial complexity and temporal stability of hemodynamics generated by a database of 210 patient-specific aneurysm geometries. Visual classifications of the hemodynamics are compared to the automated, quantitative classifications. The quantities characterizing the hemodynamics are then compared to clinical data to determine conditions that are
Lithium-Based High Energy Density Flow Batteries
Bugga, Ratnakumar V. (Inventor); West, William C. (Inventor); Kindler, Andrew (Inventor); Smart, Marshall C. (Inventor)
2014-01-01
Systems and methods in accordance with embodiments of the invention implement a lithium-based high energy density flow battery. In one embodiment, a lithium-based high energy density flow battery includes a first anodic conductive solution that includes a lithium polyaromatic hydrocarbon complex dissolved in a solvent, a second cathodic conductive solution that includes a cathodic complex dissolved in a solvent, a solid lithium ion conductor disposed so as to separate the first solution from the second solution, such that the first conductive solution, the second conductive solution, and the solid lithium ionic conductor define a circuit, where when the circuit is closed, lithium from the lithium polyaromatic hydrocarbon complex in the first conductive solution dissociates from the lithium polyaromatic hydrocarbon complex, migrates through the solid lithium ionic conductor, and associates with the cathodic complex of the second conductive solution, and a current is generated.
Numerical simulation of base flow with hot base bleed for two jet models
Institute of Scientific and Technical Information of China (English)
Wen-jie YU; Yong-gang YU; Bin NI
2014-01-01
In order to improve the benefits of base bleed in base flow field, the base flow with hot base bleed for two jet models is studied. Two-dimensional axisymmetric NaviereStokes equations are computed by using a finite volume scheme. The base flow of a cylinder afterbody with base bleed is simulated. The simulation results are validated with the experimental data, and the experimental results are well reproduced. On this basis, the base flow fields with base bleed for a circular jet model and an annulus jet model are investigated by selecting the injection temperature from 830 K to 2200 K. The results show that the base pressure of the annular jet model is higher than that of the circular jet model with the changes of the injection parameter and the injection temperature. For the circular jet model, the hot gases are concentrated in the vicinity of the base. For the annular jet model, the bleed gases flow into the shear layer directly so that the hot gases are concentrated in the shear layer. The latter temperature distribution is better for the increase of base pressure.
A thermistor based sensor for flow measurement in water
Moore, John P.
2003-01-01
There is limited experimental data describing the mixing processes and coherent velocity structures near the surface of the ocean. These play an important part in the interactions between the atmosphere and the ocean and thus affect the climate of the earth. A robust, low cost thermistor based sensor suitable for use in the detection and quantification of velocity structures has been designed and developed. The flow sensor, a thermal anemometer, consists of a self-heated thermistor that is ma...
Novel Quinone-Based Couples for Flow Batteries
Huskinson, Brian Thomas; Nawar, Saraf; Gerhardt, Michael; Aziz, Michael J.
2013-01-01
Flow batteries are of interest for low-cost grid-scale electrical energy storage in the face of rising electricity production from intermittent renewables like wind and solar. We report on investigations of redox couples based on the reversible protonation of small organic molecules called quinones. These molecules can be very inexpensive and may therefore offer a low cost per kWh of electrical energy storage. Furthermore they are known to rapidly undergo oxidation and reduction with high rev...
Flow cytometry-based invasion phenotyping assay for malaria
sprotocols
2015-01-01
Authors: Michel Theron, Richard Hesketh, Sathish Subramanian & Julian Rayner ### Abstract To facilitate the scale-up of erythrocyte invasion phenotyping for Plasmodium falciparum, we have developed a novel platform based on two-color flow cytometry that distinguishes parasite invasion from parasite growth. Target cells that had one or more receptors removed using enzymatic treatment were prelabeled with intracellular dyes CFDA-SE or DDAO-SE, incubated with P. falciparum parasites,...
Nanoparticle-based assays in automated flow systems: A review
Energy Technology Data Exchange (ETDEWEB)
Passos, Marieta L.C. [LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, n° 228, 4050-313 Porto (Portugal); Pinto, Paula C.A.G., E-mail: ppinto@ff.up.pt [LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, n° 228, 4050-313 Porto (Portugal); Santos, João L.M., E-mail: joaolms@ff.up.pt [LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, n° 228, 4050-313 Porto (Portugal); Saraiva, M. Lúcia M.F.S., E-mail: lsaraiva@ff.up.pt [LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, n° 228, 4050-313 Porto (Portugal); Araujo, André R.T.S. [LAQV, REQUIMTE, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua Jorge Viterbo Ferreira, n° 228, 4050-313 Porto (Portugal); Unidade de Investigação para o Desenvolvimento do Interior, Instituto Politécnico da Guarda, Av. Dr. Francisco de Sá Carneiro, n° 50, 6300-559 Guarda (Portugal)
2015-08-19
Nanoparticles (NPs) exhibit a number of distinctive and entrancing properties that explain their ever increasing application in analytical chemistry, mainly as chemosensors, signaling tags, catalysts, analytical signal enhancers, reactive species generators, analyte recognition and scavenging/separation entities. The prospect of associating NPs with automated flow-based analytical is undoubtedly a challenging perspective as it would permit confined, cost-effective and reliable analysis, within a shorter timeframe, while exploiting the features of NPs. This article aims at examining state-of-the-art on continuous flow analysis and microfluidic approaches involving NPs such as noble metals (gold and silver), magnetic materials, carbon, silica or quantum dots. Emphasis is devoted to NP format, main practical achievements and fields of application. In this context, the functionalization of NPs with distinct chemical species and ligands is debated in what concerns the motivations and strengths of developed approaches. The utilization of NPs to improve detector's performance in electrochemical application is out of the scope of this review. The works discussed in this review were published in the period of time comprised between the years 2000 and 2013. - Highlights: • The state of the art of flowing stream systems comprising NPs was reviewed. • The use of different types of nanoparticles in each flow technique is discussed. • The most expressive and profitable applications are summarized. • The main conclusions and future perspectives were compiled in the final section.
Flow visualization of silicon-based micro pulsating heat pipes
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Two sets of silicon-based micro pulsating heat pipes(SMPHPs) with trapezoidal cross section having hydraulic diameters of 352 μm(#1) and 394 μm(#2) respectively were fabricated for the first time using MEMS technology.With FC-72 as the working fluid,the start-up,steady operation state,as well as flow patterns were investigated using a CCD camera.It was found that the start-up process of these two SMPHPs was rather rapid.At the start-up period,no nucleation was observed,and the vapor plugs at the evaporator U-bends were formed mainly due to the breakup of liquid slugs.At the steady operation state,self-sustained oscillation with large amplitudes dominated the flow behavior when the inclination angle varied from 10° to 90°,but the nucleate boiling and bulk circulation were observed only in SMPHP #2.While bubbly,slug/plug,annular/semi-annular,and wavy-annular flows were observed in both two SMPHPs,the injection flow only appeared in SMPHP #2.
Limitations of Adjoint-Based Optimization for Separated Flows
Otero, J. Javier; Sharma, Ati; Sandberg, Richard
2015-11-01
Cabin noise is generated by the transmission of turbulent pressure fluctuations through a vibrating panel and can lead to fatigue. In the present study, we model this problem by using DNS to simulate the flow separating off a backward facing step and interacting with a plate downstream of the step. An adjoint formulation of the full compressible Navier-Stokes equations with varying viscosity is used to calculate the optimal control required to minimize the fluid-structure-acoustic interaction with the plate. To achieve noise reduction, a cost function in wavenumber space is chosen to minimize the excitation of the lower structural modes of the structure. To ensure the validity of time-averaged cost functions, it is essential that the time horizon is long enough to be a representative sample of the statistical behaviour of the flow field. The results from the current study show how this scenario is not always feasible for separated flows, because the chaotic behaviour of turbulence surpasses the ability of adjoint-based methods to compute time-dependent sensitivities of the flow.
Topography-based flow-directional roughness: potential and challenges
Trevisani, Sebastiano; Cavalli, Marco
2016-04-01
Surface texture analysis applied to high-resolution digital terrain models (HRDTMs) is a promising approach for extracting useful fine-scale morphological information. Surface roughness, considered here as a synonym of surface texture, can have a discriminant role in the detection of different geomorphic processes and factors. Very often, the local morphology presents, at different scales, anisotropic characteristics that could be taken into account when calculating or measuring surface roughness. The high morphological detail of HRDTMs permits the description of different aspects of surface roughness, beyond an evaluation limited to isotropic measures of surface roughness. The generalization of the concept of roughness implies the need to refer to a family of specific roughness indices capable of capturing specific multiscale and anisotropic aspects of surface morphology. An interesting set of roughness indices is represented by directional measures of roughness that can be meaningful in the context of analyzed and modeled flow processes. Accordingly, we test the application of a flow-oriented directional measure of roughness based on the geostatistical bivariate index MAD (median of absolute directional differences), which is computed considering surface gravity-driven flow direction. MAD is derived from a modification of a variogram and is specifically designed for the geomorphometric analysis of HRDTMs. The presented approach shows the potential impact of considering directionality in the calculation of roughness indices. The results demonstrate that the use of flow-directional roughness can improve geomorphometric modeling (e.g., sediment connectivity and surface texture modeling) and the interpretation of landscape morphology.
Compact and tunable size-based dielectrophoretic flow fractionation
International Nuclear Information System (INIS)
A compact and tunable size-based flow fractionation microchip using negative dielectrophoresis (DEP) is presented in this paper. In the microchip, a sample containing a mixture of particles is hydrodynamically focused in a contraction section and then sorted by size after flowing over planar interdigitated electrodes. The electrodes and flow chamber were aligned at an angle of 45° to produce effective sorting. 1, 2.5 and 4.8 µm polystyrene (PS) particles were successfully separated into three distinct streams in a short distance (1 mm) and collected in different outlet channels. The sorting was subjected to flow rates and electric potential. The experimental sorting efficiencies of 1, 2.5 and 4.8 µm particles reached 97.2%, 79.6% and 99.8%, respectively. With the same device, lipid vesicle sorting was demonstrated. 86.9% of vesicles larger than 10 µm were effectively extracted from the sample stream. Likewise, sorting of other biological particles can be achieved in the same fashion. (paper)
Nanoparticle-based assays in automated flow systems: A review
International Nuclear Information System (INIS)
Nanoparticles (NPs) exhibit a number of distinctive and entrancing properties that explain their ever increasing application in analytical chemistry, mainly as chemosensors, signaling tags, catalysts, analytical signal enhancers, reactive species generators, analyte recognition and scavenging/separation entities. The prospect of associating NPs with automated flow-based analytical is undoubtedly a challenging perspective as it would permit confined, cost-effective and reliable analysis, within a shorter timeframe, while exploiting the features of NPs. This article aims at examining state-of-the-art on continuous flow analysis and microfluidic approaches involving NPs such as noble metals (gold and silver), magnetic materials, carbon, silica or quantum dots. Emphasis is devoted to NP format, main practical achievements and fields of application. In this context, the functionalization of NPs with distinct chemical species and ligands is debated in what concerns the motivations and strengths of developed approaches. The utilization of NPs to improve detector's performance in electrochemical application is out of the scope of this review. The works discussed in this review were published in the period of time comprised between the years 2000 and 2013. - Highlights: • The state of the art of flowing stream systems comprising NPs was reviewed. • The use of different types of nanoparticles in each flow technique is discussed. • The most expressive and profitable applications are summarized. • The main conclusions and future perspectives were compiled in the final section
A Flow SPR Immunosensor Based on a Sandwich Direct Method.
Tomassetti, Mauro; Conta, Giorgia; Campanella, Luigi; Favero, Gabriele; Sanzò, Gabriella; Mazzei, Franco; Antiochia, Riccarda
2016-01-01
In this study, we report the development of an SPR (Surface Plasmon Resonance) immunosensor for the detection of ampicillin, operating under flow conditions. SPR sensors based on both direct (with the immobilization of the antibody) and competitive (with the immobilization of the antigen) methods did not allow the detection of ampicillin. Therefore, a sandwich-based sensor was developed which showed a good linear response towards ampicillin between 10(-3) and 10(-1) M, a measurement time of ≤20 min and a high selectivity both towards β-lactam antibiotics and antibiotics of different classes. PMID:27187486
Energy-Based Voronoi Partition in Constant Flow Environments
Ru, Yu
2011-01-01
As is well known, energy cost can greatly impact the deployment of battery-powered sensor networks in remote environments such as rivers or oceans. Motivated by this, we propose here an energy-based metric and associate energy-based Voronoi partitions with mobile vehicles in constant flows. The metric corresponds to the minimum energy that a vehicle requires to move from one point to another in the flow environment, and the resulting partition can be used by the vehicles in cooperative control tasks such as task assignment and coverage. Based on disk-based and asymptote-based approximations of the Voronoi regions, we determine a subset (or lower bound) and superset (or upper bound) of an agent's Voronoi neighbors. We then show that, via simulations, the upper bound is tight and its cardinality remains bounded as the number of generators increases. Finally, we propose efficient algorithms to compute the upper bound (especially when the generators dynamically change), which enables the fast calculation of Voron...
Violence detection based on histogram of optical flow orientation
Yang, Zhijie; Zhang, Tao; Yang, Jie; Wu, Qiang; Bai, Li; Yao, Lixiu
2013-12-01
In this paper, we propose a novel approach for violence detection and localization in a public scene. Currently, violence detection is considerably under-researched compared with the common action recognition. Although existing methods can detect the presence of violence in a video, they cannot precisely locate the regions in the scene where violence is happening. This paper will tackle the challenge and propose a novel method to locate the violence location in the scene, which is important for public surveillance. The Gaussian Mixed Model is extended into the optical flow domain in order to detect candidate violence regions. In each region, a new descriptor, Histogram of Optical Flow Orientation (HOFO), is proposed to measure the spatial-temporal features. A linear SVM is trained based on the descriptor. The performance of the method is demonstrated on the publicly available data sets, BEHAVE and CAVIAR.
Redox flow batteries based on supporting solutions containing chloride
Energy Technology Data Exchange (ETDEWEB)
Li, Liyu; Kim, Soowhan; Yang, Zhenguo; Wang, Wei; Nie, Zimin; Chen, Baowei; Zhang, Jianlu; Xia, Guanguang
2015-07-07
Redox flow battery systems having a supporting solution that contains Cl.sup.- ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO.sub.4.sup.2- and Cl.sup.- ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V.sup.2+ and V.sup.3+ in a supporting solution and a catholyte having V.sup.4+ and V.sup.5+ in a supporting solution. The supporting solution can contain Cl.sup.- ions or a mixture of SO.sub.4.sup.2- and Cl.sup.- ions.
Redox flow batteries based on supporting solutions containing chloride
Energy Technology Data Exchange (ETDEWEB)
Li, Liyu; Kim, Soowhan; Yang, Zhenguo; Wang, Wei; Zhang, Jianlu; Chen, Baowei; Nie, Zimin; Xia, Guanguang
2014-01-14
Redox flow battery systems having a supporting solution that contains Cl.sup.- ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO.sub.4.sup.2- and Cl.sup.- ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V.sup.2+ and V.sup.3+ in a supporting solution and a catholyte having V.sup.4+ and V.sup.5+ in a supporting solution. The supporting solution can contain Cl.sup.- ions or a mixture of SO.sub.4.sup.2- and Cl.sup.- ions.
Redox flow batteries based on supporting solutions containing chloride
Energy Technology Data Exchange (ETDEWEB)
Li, Liyu; Kim, Soowhan; Yang, Zhenguo; Wang, Wei; Nie, Zimin; Chen, Baowei; Zhang, Jianlu; Xia, Guanguang
2015-09-01
Redox flow battery systems having a supporting solution that contains Cl.sup.- ions can exhibit improved performance and characteristics. Furthermore, a supporting solution having mixed SO.sub.4.sup.2- and Cl.sup.- ions can provide increased energy density and improved stability and solubility of one or more of the ionic species in the catholyte and/or anolyte. According to one example, a vanadium-based redox flow battery system is characterized by an anolyte having V.sup.2+ and V.sup.3+ in a supporting solution and a catholyte having V.sup.4+ and V.sup.5+ in a supporting solution. The supporting solution can contain Cl.sup.- ions or a mixture of SO.sub.4.sup.2- and Cl.sup.- ions.
FPGA Based High Performance Optical Flow Computation Using Parallel Architecture
Directory of Open Access Journals (Sweden)
N.Devi
2012-03-01
Full Text Available The proposed work describes a highly parallel architecture for high performance optical flow computation. This system implements the efficient Lucas and Kanade algorithm with multi-scale extension for the computation of large motion estimations. This work deals with the architecture, evaluation of the accuracy and system performance. It also has extension to the original L&K algorithm. So the capable of working is larger than the standard mono scale approaches. In this proposed system, Matlab and Modelsim simulation are selected for local optical flow algorithms due to their potential for a high-performance massive parallelization. The results are obtained with a throughput of one pixel per clock cycle along the whole processing scheme by using the fine-pipeline based architecture.
Flow-Based Specification of Time Design Requirements
Directory of Open Access Journals (Sweden)
Sabah Al-Fedaghi
2015-08-01
Full Text Available This paper focuses on design requirements in real-time systems where information is processed to produce a response within a specified time. Nowadays, computer control applications embedded in chips have grown in significance in many aspects of human life. These systems need a high level of reliability to gain the trust of users. Ensuring correctness in the early stages of the design process is especially a major challenge in these systems. Faulty requirements lead to errors in the final product that have to be fixed later, often at a high cost. A crucial step in this process is modeling the intended system. This paper explores the potential of flow-based modeling in expressing design requirements in real-time systems that include time constraints and synchronization. The main emphasized problem is how to represent time. The objective is to assist real-time system requirement engineers, in an early state of the development, to express the timing behavior of the developed system. Several known examples are modeled and the results point to the viability of the flow-based representation in comparison with such time specifications as state-based and line-based modeling.
Pipe flow of pumping wet shotcrete based on lubrication layer.
Chen, Lianjun; Liu, Guoming; Cheng, Weimin; Pan, Gang
2016-01-01
Wet shotcrete can reduce dust and improve supporting strength, however, safe and efficient pipage is a key technical part of wet shotcrete process. The paper studied the pipe flow law of wet shotcrete based on lubrication layer by build the experimental pumping circuit of wet shotcrete that can carry out a number of full-scale pumping tests. The experimental results show there was a linear relationship between pressure loss and flow rate. Combined with the Buckingham rheological equation, the computing equations of the yield shear stress and plastic viscosity were deduced through linear regression. A simple analytical method allowing for a rough estimation of the pumping pressure was proposed and used when considering the lubrication layer of wet shotcrete in pipes. In addition, two kinds of particulate distributive models were established along the time axial to analyze the formation of lubrication layer which is related with particles migration. By computational fluid dynamics simulation, the lubrication layer thickness of different mix proportions was estimated. A new method for measuring the thickness of lubrication layer was proposed to verify it by binarization processing. Finally, according to the comparative analysis of experiments, simulation and computed value, it can be seen that the lubrication layer plays a key role in the process of wet shotcrete flow and with the increase of lubrication layer thickness pipe pressure declines gradually. PMID:27386389
File-based data flow in the CMS Filter Farm
Andre, J.-M.; Andronidis, A.; Bawej, T.; Behrens, U.; Branson, J.; Chaze, O.; Cittolin, S.; Darlea, G.-L.; Deldicque, C.; Dobson, M.; Dupont, A.; Erhan, S.; Gigi, D.; Glege, F.; Gomez-Ceballos, G.; Hegeman, J.; Holzner, A.; Jimenez-Estupiñán, R.; Masetti, L.; Meijers, F.; Meschi, E.; Mommsen, R. K.; Morovic, S.; Nunez-Barranco-Fernandez, C.; O'Dell, V.; Orsini, L.; Paus, C.; Petrucci, A.; Pieri, M.; Racz, A.; Roberts, P.; Sakulin, H.; Schwick, C.; Stieger, B.; Sumorok, K.; Veverka, J.; Zaza, S.; Zejdl, P.
2015-12-01
During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.
Accurate Multisteps Traffic Flow Prediction Based on SVM
Directory of Open Access Journals (Sweden)
Zhang Mingheng
2013-01-01
Full Text Available Accurate traffic flow prediction is prerequisite and important for realizing intelligent traffic control and guidance, and it is also the objective requirement for intelligent traffic management. Due to the strong nonlinear, stochastic, time-varying characteristics of urban transport system, artificial intelligence methods such as support vector machine (SVM are now receiving more and more attentions in this research field. Compared with the traditional single-step prediction method, the multisteps prediction has the ability that can predict the traffic state trends over a certain period in the future. From the perspective of dynamic decision, it is far important than the current traffic condition obtained. Thus, in this paper, an accurate multi-steps traffic flow prediction model based on SVM was proposed. In which, the input vectors were comprised of actual traffic volume and four different types of input vectors were compared to verify their prediction performance with each other. Finally, the model was verified with actual data in the empirical analysis phase and the test results showed that the proposed SVM model had a good ability for traffic flow prediction and the SVM-HPT model outperformed the other three models for prediction.
File-Based Data Flow in the CMS Filter Farm
Energy Technology Data Exchange (ETDEWEB)
Andre, J.M.; et al.
2015-12-23
During the LHC Long Shutdown 1, the CMS Data Acquisition system underwent a partial redesign to replace obsolete network equipment, use more homogeneous switching technologies, and prepare the ground for future upgrades of the detector front-ends. The software and hardware infrastructure to provide input, execute the High Level Trigger (HLT) algorithms and deal with output data transport and storage has also been redesigned to be completely file- based. This approach provides additional decoupling between the HLT algorithms and the input and output data flow. All the metadata needed for bookkeeping of the data flow and the HLT process lifetimes are also generated in the form of small “documents” using the JSON encoding, by either services in the flow of the HLT execution (for rates etc.) or watchdog processes. These “files” can remain memory-resident or be written to disk if they are to be used in another part of the system (e.g. for aggregation of output data). We discuss how this redesign improves the robustness and flexibility of the CMS DAQ and the performance of the system currently being commissioned for the LHC Run 2.
GIS-BASED 1-D DIFFUSIVE WAVE OVERLAND FLOW MODEL
Energy Technology Data Exchange (ETDEWEB)
KALYANAPU, ALFRED [Los Alamos National Laboratory; MCPHERSON, TIMOTHY N. [Los Alamos National Laboratory; BURIAN, STEVEN J. [NON LANL
2007-01-17
This paper presents a GIS-based 1-d distributed overland flow model and summarizes an application to simulate a flood event. The model estimates infiltration using the Green-Ampt approach and routes excess rainfall using the 1-d diffusive wave approximation. The model was designed to use readily available topographic, soils, and land use/land cover data and rainfall predictions from a meteorological model. An assessment of model performance was performed for a small catchment and a large watershed, both in urban environments. Simulated runoff hydrographs were compared to observations for a selected set of validation events. Results confirmed the model provides reasonable predictions in a short period of time.
Crowd Analysis by Using Optical Flow and Density Based Clustering
DEFF Research Database (Denmark)
Santoro, Francesco; Pedro, Sergio; Tan, Zheng-Hua; Moeslund, Thomas B.
2010-01-01
In this paper, we present a system to detect and track crowds in a video sequence captured by a camera. In a first step, we compute optical flows by means of pyramidal Lucas-Kanade feature tracking. Afterwards, a density based clustering is used to group similar vectors. In the last step, it is...... applied a crowd tracker in every frame, allowing us to detect and track the crowds. Our system gives the output as a graphic overlay, i.e it adds arrows and colors to the original frame sequence, in order to identify crowds and their movements. For the evaluation, we check when our system detect certains...
A review on flow characterization methods for cereal grain-based powders.
Ambrose, R P Kingsly; Jan, Shumaila; Siliveru, Kaliramesh
2016-01-30
Flow difficulties during handling, storage, and processing are common in cereal grain-based powder industries. The many studies that focus on the flow properties of powders can be classified as flow indicators, shear properties, and dynamic flow properties. The non-uniformity of physical and chemical characteristics of the individual particles that make up the bulk solid of cereal grain-based powders adds complexity to the characterization of flow behavior. Even so, knowledge of flow behavior is critical to the design of productive and cost-effective equipment for handling and processing of these powders. Because many factors influence flow, a single property/index value may not satisfactorily quantify the flow or no-flow of powders. For powders of biological origin, chemical composition and environmental factors such as temperature and relative humidity complicate flow characterization. This review focuses on the specific flow characteristics that directly affect powder flow during handling, processing, and storage. PMID:26095631
Hisamoto, Hideaki; Horiuchi, Takayuki; Hibara, Akihide; Tokeshi, Manabu; Kitamori, Takehiko
A new fluid flow inside the microchannel was successfully developed. The flow created here involves segmented flow injection of plural organic phases into a microchannel followed by contact with a single aqueous phase to form stable organic-aqueous two-layer flow inside the microchannel. Fundamental study on the developed flow inside the microchannel was performed by monitoring the dye-doped segmented organic phases by thermal lens microscopy (TLM). Excellent repeatability and very small injection volume in developing segmented flow were realized. The new fluid flow created here is expected to allow us multi-ion sensing, which is not easily demonstrated by conventional ion sensor technology using a solvent polymeric membrane, by combining with neutral ionophore-based ion pair extraction using plural numbers of organic phases containing different ionophore molecules.
Universal Verification Methodology Based Register Test Automation Flow.
Woo, Jae Hun; Cho, Yong Kwan; Park, Sun Kyu
2016-05-01
In today's SoC design, the number of registers has been increased along with complexity of hardware blocks. Register validation is a time-consuming and error-pron task. Therefore, we need an efficient way to perform verification with less effort in shorter time. In this work, we suggest register test automation flow based UVM (Universal Verification Methodology). UVM provides a standard methodology, called a register model, to facilitate stimulus generation and functional checking of registers. However, it is not easy for designers to create register models for their functional blocks or integrate models in test-bench environment because it requires knowledge of SystemVerilog and UVM libraries. For the creation of register models, many commercial tools support a register model generation from register specification described in IP-XACT, but it is time-consuming to describe register specification in IP-XACT format. For easy creation of register model, we propose spreadsheet-based register template which is translated to IP-XACT description, from which register models can be easily generated using commercial tools. On the other hand, we also automate all the steps involved integrating test-bench and generating test-cases, so that designers may use register model without detailed knowledge of UVM or SystemVerilog. This automation flow involves generating and connecting test-bench components (e.g., driver, checker, bus adaptor, etc.) and writing test sequence for each type of register test-case. With the proposed flow, designers can save considerable amount of time to verify functionality of registers. PMID:27483924
Flow-based market coupling. Stepping stone towards nodal pricing?
International Nuclear Information System (INIS)
For achieving one internal energy market for electricity by 2014, market coupling is deployed to integrate national markets into regional markets and ultimately one European electricity market. The extent to which markets can be coupled depends on the available transmission capacities between countries. Since interconnections are congested from time to time, congestion management methods are deployed to divide the scarce available transmission capacities over market participants. For further optimization of the use of available transmission capacities while maintaining current security of supply levels, flow-based market coupling (FBMC) will be implemented in the CWE region by 2013. Although this is an important step forward, important hurdles for efficient congestion management remain. Hence, flow based market coupling is compared to nodal pricing, which is often considered as the most optimal solution from theoretical perspective. In the context of decarbonised power systems it is concluded that advantages of nodal pricing are likely to exceed its disadvantages, warranting further development of FBMC in the direction of nodal pricing.
Bipartite graph-based control flow checking for COTS-based small satellites
Directory of Open Access Journals (Sweden)
Wang Honghao
2015-06-01
Full Text Available Single event upset (SEU effect, caused by highly energized particles in aerospace, threatens the reliability and security of small satellites composed of commercial-off-the-shelves (COTS. SEU-induced control flow errors (CFEs may cause unpredictable behavior or crashes of COTS-based small satellites. This paper proposes a generic software-based control flow checking technique (CFC and bipartite graph-based control flow checking (BGCFC. To simplify the types of illegal branches, it transforms the conventional control flow graph into the equivalent bipartite graph. It checks the legality of control flow at runtime by comparing a global signature with the expected value and introduces consecutive IDs and bitmaps to reduce the time and memory overhead. Theoretical analysis shows that BGCFC can detect all types of inter-node CFEs with constant time and memory overhead. Practical tests verify the result of theoretical analysis. Compared with previous techniques, BGCFC achieves the highest error detection rate, lower time and memory overhead; the composite result in evaluation factor shows that BGCFC is the most effective one among all these techniques. The results in both theory and practice verify the applicability of BGCFC for COTS-based small satellites.
Study of the Gas-Liquid Two-Phase Flow Measuring Method Based on the V-Cone Flow Meter
Dong, Feng; Hu, Jun
2007-06-01
The paper presents a proper correlation for measuring air-water two-phase flow based on the V-Cone flow meter (β=0.65). The calibrating methods of discharge coefficient and the corrective coefficient θ of V-Cone were introduced. On the basis of theoretical and experimental studies, the Lin Zonghu correlation was studied. The relationship between θ and static pressure (P) or gas-liquid density ratio was obtained. The root-square-errows of gas mass flow and that of liquid mass flow were 2.25% and 2.23% respectively according to the modified Lin Zonghu correlation.
Space Launch System Base Heating Test: Environments and Base Flow Physics
Mehta, Manish; Knox, Kyle; Seaford, Mark; Dufrene, Aaron
2016-01-01
NASA MSFC and CUBRC designed and developed a 2% scale SLS propulsive wind tunnel test program to investigate base flow effects during flight from lift-off to MECO. This type of test program has not been conducted in 40+ years during the NASA Shuttle Program. Dufrene et al paper described the operation, instrumentation type and layout, facility and propulsion performance, test matrix and conditions and some raw results. This paper will focus on the SLS base flow physics and the generation and results of the design environments being used to design the thermal protection system.
Müller, T.; Hoffmann, T.
2012-04-01
Debris flows play a crucial role in the coupling of hillslope-sediment sources and channels in mountain environments. In most landscape evolution models (LEMs), the sediment transport by debris flows is (if at all) often represented by simple empirical rules. This generally results from the mismatch of the coarse resolution of the LEMs and the small scale impacts of debris flow processes. To extend the accuracy and predictive power of LEMs, either a higher resolution of LEMs in combination with process-based debris flow models or a better parametrisation of subpixel scale debris flow processes is necessary. Furthermore, the simulation of sediment transport by debris flows is complicated by their episodic nature and unknown factors controlling the frequency and magnitude of events. Here, we present first results using a slope stability model (SINMAP) and an event-based debris flow routing model (SCIDDICA-S4c) to simulate the effects of debris flows in LEMs. The model was implemented in the XULU modelling platform developed by the Department of Computer Science at the University of Bonn. The combination of the slope stability model and the event-based routing and mass balance model enables us to simulate the triggering and routing of debris flow material through the iteration of single events over several thousand years. Although a detailed calibration and validation remains to be done, the resulting debris flow-affected areas in a test elevation model correspond well with data gained from a geomorphological mapping of the corresponding area, justifying our approach. The increased computation speed allows to run high resolution LEM in convenient short time at relatively low cost. This should encourage the development of more detailed LEMs, in which process-based models should be incorporated.
Quadrature-based Lattice Boltzmann Model for Relativistic Flows
Blaga, Robert
2016-01-01
A quadrature-based finite-difference lattice Boltzmann model is developed that is suitable for simulating relativistic flows of massless particles. We briefly review the relativistc Boltzmann equation and present our model. The quadrature is constructed such that the stress-energy tensor is obtained as a second order moment of the distribution function. The results obtained with our model are presented for a particular instance of the Riemann problem (the Sod shock tube). We show that the model is able to accurately capture the behavior across the whole domain of relaxation times, from the hydrodynamic to the ballistic regime. The property of the model of being extendable to arbitrarily high orders is shown to be paramount for the recovery of the analytical result in the ballistic regime.
Tropical cyclogenesis: a numerical diagnosis based on helical flow organization
International Nuclear Information System (INIS)
A numerical diagnosis for tropical cyclogenesis is proposed based on nearcloud-resolving atmospheric simulation. Calculation and analyses of helical and energetic characteristics together with hydro- and thermodynamic flow fields allow the diagnosis of tropical cyclogenesis as an event when the primary and secondary circulations become linked on system scales thereby making the nascent large-scale vortex helical. A key process of vertical vorticity generation from horizontal components and its amplification by special convective coherent structures – Vortical Hot Towers (VHTs) – is highlighted. The process is found to be a pathway for generation of a velocity field with linked vortex lines of horizontal and vertical vorticity on local and system scales. The role of VHTs as connectors of the primary and secondary circulation is emphasized
Grid-Based Hydrodynamics in Astrophysical Fluid Flows
Teyssier, Romain
2015-08-01
In this review, the equations of hydrodynamics, magnetohydrodynamics, and radiation hydrodynamics are presented, together with their corresponding nonideal source terms. I overview the current landscape of modern grid-based numerical techniques with an emphasis on numerical diffusion, which plays a fundamental role in stabilizing the solution but is also the main source of errors associated with these numerical techniques. I discuss in great detail the inclusion of additional important source terms, such as cooling and gravity. I also show how to modify classic operator-splitting techniques to avoid undesirable numerical errors associated with these additional source terms, in particular in the presence of highly supersonic flows. I finally present various mesh adaptation strategies that can be used to minimize these numerical errors. To conclude, I review existing astrophysical software that is publicly available to perform simulations for such astrophysical fluids.
High energy sodium based room temperature flow batteries
Shamie, Jack
As novel energy sources such as solar, wind and tidal energies are explored it becomes necessary to build energy storage facilities to load level the intermittent nature of these energy sources. Energy storage is achieved by converting electrical energy into another form of energy. Batteries have many properties that are attractive for energy storage including high energy and power. Among many different types of batteries, redox flow batteries (RFBs) offer many advantages. Unlike conventional batteries, RFBs store energy in a liquid medium rather than solid active materials. This method of storage allows for the separation of energy and power unlike conventional batteries. Additionally flow batteries may have long lifetimes because there is no expansion or contraction of electrodes. A major disadvantage of RFB's is its lower energy density when compared to traditional batteries. In this Thesis, a novel hybrid Na-based redox flow battery (HNFB) is explored, which utilizes a room temperature molten sodium based anode, a sodium ion conducting solid electrolyte and liquid catholytes. The sodium electrode leads to high voltages and energy and allows for the possibility of multi-electron transfer per molecule. Vanadium acetylacetonate (acac) and TEMPO have been investigated for their use as catholytes. In the vanadium system, 2 electrons transfers per vanadium atom were found leading to a doubling of capacity. In addition, degradation of the charged state was found to be reversible within the voltage range of the cell. Contamination by water leads to the formation of vanadyl acetylacetonate. Although it is believed that vanadyl complex need to be taken to low voltages to be reduced back to vanadium acac, a new mechanism is shown that begins at higher voltages (2.1V). Vanadyl complexes react with excess ligand and protons to reform the vanadium complex. During this reaction, water is reformed leading to the continuous cycle in which vanadyl is formed and then reduced back
Trends in Flow-based Biosensing Systems for Pesticide Assessment
Directory of Open Access Journals (Sweden)
Jean-Louis Marty
2006-10-01
Full Text Available This review gives a survey on the state of the art of pesticide detection usingflow-based biosensing systems for sample screening. Although immunosensor systems havebeen proposed as powerful pesticide monitoring tools, this review is mainly focused onenzyme-based biosensors, as they are the most commonly employed when using a flowsystem. Among the different detection methods able to be integrated into flow-injectionanalysis (FIA systems, the electrochemical ones will be treated in more detail, due to theirhigh sensitivity, simple sample pretreatment, easy operational procedures and real-timedetection. During the last decade, new trends have been emerging in order to increase theenzyme stability, the sensitivity and selectivity of the measurements, and to lower thedetection limits. These approaches are based on (i the design of novel matrices for enzymeimmobilisation, (ii new manifold configurations of the FIA system, sometimes includingminiaturisation or lab-on-chip protocols thanks to micromachining technology, (iii the useof cholinesterase enzymes either from various commercial sources or genetically modifiedwith the aim of being more sensitive, (iv the incorporation of other highly specificenzymes, such as organophosphate hydrolase (OPH or parathion hydrolase (PH and (v thecombination of different electrochemical methods of detection. This article discusses thesenovel strategies and their advantages and limitations.
Obtaining Internet Flow Statistics by Volunteer-Based System
DEFF Research Database (Denmark)
Pedersen, Jens Myrup; Bujlow, Tomasz
2012-01-01
and groups of users, and as such be useful also for segmentation of users intro groups. We present results with data collected from real users over several months; in particular we demonstrate how the system can be used for studying flow characteristics - the amount of TCP and UDP flows, average flow lengths...
Institute of Scientific and Technical Information of China (English)
Zheng Yingren; Deng Chujian; Wang Jinglin
2010-01-01
At present,associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials.So the stress characteristic line conforms to the velocity line.It is proved that geotechnical materials do not abide by the associated flow rule.It is impossible for the stress characteristic line to conform to the velocity line.Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle,so that the velocity line must be studied by non-associated flow rule.According to limit analysis theory,the theory of slip line field is put forward in this paper,and then the ultimate boating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow rule individually.These two results are identical since the ultimate bearing capacity is independent of flow rule.On the contrary,the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associated flow rule is incorrect.
Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control
Cary, Robert E.
2015-12-08
Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.
Multiphase flow parameter estimation based on laser scattering
Vendruscolo, Tiago P.; Fischer, Robert; Martelli, Cicero; Rodrigues, Rômulo L. P.; Morales, Rigoberto E. M.; da Silva, Marco J.
2015-07-01
The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time.
Multiphase flow parameter estimation based on laser scattering
International Nuclear Information System (INIS)
The flow of multiple constituents inside a pipe or vessel, known as multiphase flow, is commonly found in many industry branches. The measurement of the individual flow rates in such flow is still a challenge, which usually requires a combination of several sensor types. However, in many applications, especially in industrial process control, it is not necessary to know the absolute flow rate of the respective phases, but rather to continuously monitor flow conditions in order to quickly detect deviations from the desired parameters. Here we show how a simple and low-cost sensor design can achieve this, by using machine-learning techniques to distinguishing the characteristic patterns of oblique laser light scattered at the phase interfaces. The sensor is capable of estimating individual phase fluxes (as well as their changes) in multiphase flows and may be applied to safety applications due to its quick response time. (paper)
Ruthenium based redox flow battery for solar energy storage
International Nuclear Information System (INIS)
Research highlights: → Undivided redox flow battery employing porous graphite felt electrodes was used. → Ruthenium acetylacetonate dissolved in acetonitrile was the electrolyte. → Charge/discharge conditions were determined for both 0.02 M and 0.1 M electrolytes. → Optimum power output of 0.180 W was also determined for 0.1 M electrolyte. → 55% voltage efficiency was obtained when battery was full of electrolytes. -- Abstract: The technical performance for the operation of a stand alone redox flow battery system for solar energy storage is presented. An undivided reactor configuration has been employed along with porous graphite felt electrodes and ruthenium acetylacetonate as electrolyte in acetonitrile solvent. Limiting current densities are determined for concentrations of 0.02 M and 0.1 M ruthenium acetylacetonate. Based on these, operating conditions for 0.02 M ruthenium acetylacetonate are determined as charging current density of 7 mA/cm2, charge electrolyte superficial velocity of 0.0072 cm/s (through the porous electrodes), discharge current density of 2 mA/cm2 and discharge electrolyte superficial velocity of 0.0045 cm/s. An optimum power output of 35 mW is also obtained upon discharge at 2.1 mA/cm2. With an increase in the concentration of ruthenium species from 0.02 M to 0.1 M, the current densities and power output are higher by a factor of five approximately (at same superficial velocities) due to higher mass transport phenomenon. Moreover at 0.02 M concentration the voltage efficiency is better for battery full of electrolytes prior to charging (52.1%) in comparison to an empty battery (40.5%) due to better mass transport phenomenon. Voltage efficiencies are higher as expected at concentrations of 0.1 M ruthenium acetylacetonate (55% when battery is full of electrolytes and 48% when empty) showing that the all-ruthenium redox flow battery has some promise for future applications in solar energy storage. Some improvements for the system are
Visual guidance based on optic flow: a biorobotic approach.
Franceschini, Nicolas
2004-01-01
This paper addresses some basic questions as to how vision links up with action and serves to guide locomotion in both biological and artificial creatures. The thorough knowledge gained during the past five decades on insects' sensory-motor abilities and the neuronal substrates involved has provided us with a rich source of inspiration for designing tomorrow's self-guided vehicles and micro-vehicles, which will be able to cope with unforeseen events on the ground, under water, in the air, in space, on other planets, and inside the human body. Insects can teach us some useful tricks for designing agile autonomous robots. Since constructing a "biorobot" first requires exactly formulating the biological principles presumably involved, it gives us a unique opportunity of checking the soundness and robustness of these principles by bringing them face to face with the real physical world. "Biorobotics" therefore goes one step beyond computer simulation. It leads to experimenting with real physical robots which have to pass the stringent test of the real world. Biorobotics provide us with a new tool, which can help neurobiologists and neuroethologists to identify and investigate worthwhile issues in the field of sensory-motor control. Here we describe some of the visually guided terrestrial and aerial robots we have developed since 1985 on the basis of our biological findings. All these robots behave in response to the optic flow, i.e., they work by measuring the slip speed of the retinal image. Optic flow is sensed on-board by miniature electro-optical velocity sensors. The very principle of these sensors was based on studies in which we recorded the responses of single identified neurons to single photoreceptor stimulation in a model visual system: the fly's compound eye. PMID:15477039
Free-surface flow simulations for discharge-based operation of hydraulic structure gates
Erdbrink, C.D.; Krzhizhanovskaya, V.V.; P. M. A. Sloot
2013-01-01
We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in the operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow co...
DEFF Research Database (Denmark)
2009-01-01
Flow er en positiv, koncentreret tilstand, hvor al opmærksomhed er samlet om en bestemt aktivitet, som er så krævende og engagerende, at man må anvende mange mentale ressourcer for at klare den. Tidsfornemmelsen forsvinder, og man glemmer sig selv. 'Flow' er den første af en række udsendelser om...
Modeling of Breaching Due to Overtopping Flow and Waves Based on Coupled Flow and Sediment Transport
He, Zhiguo; Zhao, Liang; Wu, Ganfeng; Pähtz, Thomas
2015-01-01
Breaching of earthen or sandy dams/dunes by overtopping flow and waves is a complicated process with strong, unsteady flow, high sediment transport, and rapid bed changes in which the interactions between flow and morphology should not be ignored. This study presents a depth-averaged two-dimensional (2D) coupled flow and sediment transport model to investigate the flow and breaching processes with and without waves. Bed change and variable flow density are included in the flow continuity and momentum equations to consider the impacts of sediment transport. The model adopts the non-equilibrium approach for total-load sediment transport and specifies different repose angles to handle non-cohesive embankment slope avalanching. The equations are solved using an explicit finite volume method on a rectangular grid with the improved Godunov-type central upwind scheme and the nonnegative reconstruction of the water depth method to handle mixed-regime flows near the breach. The model has been tested against two sets o...
Correlation-based Transition Modeling for External Aerodynamic Flows
Medida, Shivaji
Conventional turbulence models calibrated for fully turbulent boundary layers often over-predict drag and heat transfer on aerodynamic surfaces with partially laminar boundary layers. A robust correlation-based model is developed for use in Reynolds-Averaged Navier-Stokes simulations to predict laminar-to-turbulent transition onset of boundary layers on external aerodynamic surfaces. The new model is derived from an existing transition model for the two-equation k-omega Shear Stress Transport (SST) turbulence model, and is coupled with the one-equation Spalart-Allmaras (SA) turbulence model. The transition model solves two transport equations for intermittency and transition momentum thickness Reynolds number. Experimental correlations and local mean flow quantities are used in the model to account for effects of freestream turbulence level and pressure gradients on transition onset location. Transition onset is triggered by activating intermittency production using a vorticity Reynolds number criterion. In the new model, production and destruction terms of the intermittency equation are modified to improve consistency in the fully turbulent boundary layer post-transition onset, as well as ensure insensitivity to freestream eddy viscosity value specified in the SA model. In the original model, intermittency was used to control production and destruction of turbulent kinetic energy. Whereas, in the new model, only the production of eddy viscosity in SA model is controlled, and the destruction term is not altered. Unlike the original model, the new model does not use an additional correction to intermittency for separation-induced transition. Accuracy of drag predictions are improved significantly with the use of the transition model for several two-dimensional single- and multi-element airfoil cases over a wide range of Reynolds numbers. The new model is able to predict the formation of stable and long laminar separation bubbles on low-Reynolds number airfoils that
Simulation-based patient flow analysis in an endoscopy unit
DEFF Research Database (Denmark)
Koo, Pyung-Hoi; Nielsen, Karl Brian; Jang, Jaejin;
2010-01-01
, low quality of care and high healthcare cost. This article addresses patient flow problems at a Gastrointestinal endoscopy unit. We attempt to analyze the main factors that contribute to the inefficient patient flow and process bottlenecks and to propose efficient patient scheduling and staff......One of the major elements in improving efficiency of healthcare services is patient flow. Patients require a variety of healthcare resources as they receive healthcare services. Poor management of patient flow results in long waiting time of patients, under/over utilization of medical resources...... allocation alternatives to increase the system efficiency. Simulation models are used to examine various healthcare operational strategies....
DEFF Research Database (Denmark)
Knoop, Hans Henrik
2006-01-01
FLOW. Orden i hovedet på den fede måde Oplevelsesmæssigt er flow-tilstanden kendetegnet ved at man er fuldstændig involveret, fokuseret og koncentreret; at man oplever stor indre klarhed ved at vide hvad der skal gøres, og i hvilket omfang det lykkes; at man ved at det er muligt at løse opgaven...
Water flow based geometric active deformable model for road network
Leninisha, Shanmugam; Vani, Kaliaperumal
2015-04-01
A width and color based geometric active deformable model is proposed for road network extraction from remote sensing images with minimal human interception. Orientation and width of road are computed from a single manual seed point, from which the propagation starts both right and left hand directions of the starting point, which extracts the interconnected road network from the aerial or high spatial resolution satellite image automatically. Here the propagation (like water flow in canal with defined boundary) is restricted with color and width of the road. Road extraction is done for linear, curvilinear (U shape and S shape) roads first, irrespective of width and color. Then, this algorithm is improved to extract road with junctions in a shape of L, T and X along with center line. Roads with small break or disconnected roads are also extracts by a modified version of this same algorithm. This methodology is tested and evaluated with various remote sensing images. The experimental results show that the proposed method is efficient and extracting roads accurately with less computation time. However, in complex urban areas, the identification accuracy declines due to the various sizes of obstacles, over bridges, multilane etc.
Adjoint-based airfoil shape optimization in transonic flow
Gramanzini, Joe-Ray
The primary focus of this work is efficient aerodynamic shape optimization in transonic flow. Adjoint-based optimization techniques are employed on airfoil sections and evaluated in terms of computational accuracy as well as efficiency. This study examines two test cases proposed by the AIAA Aerodynamic Design Optimization Discussion Group. The first is a two-dimensional, transonic, inviscid, non-lifting optimization of a Modified-NACA 0012 airfoil. The second is a two-dimensional, transonic, viscous optimization problem using a RAE 2822 airfoil. The FUN3D CFD code of NASA Langley Research Center is used as the ow solver for the gradient-based optimization cases. Two shape parameterization techniques are employed to study their effect and the number of design variables on the final optimized shape: Multidisciplinary Aerodynamic-Structural Shape Optimization Using Deformation (MASSOUD) and the BandAids free-form deformation technique. For the two airfoil cases, angle of attack is treated as a global design variable. The thickness and camber distributions are the local design variables for MASSOUD, and selected airfoil surface grid points are the local design variables for BandAids. Using the MASSOUD technique, a drag reduction of 72.14% is achieved for the NACA 0012 case, reducing the total number of drag counts from 473.91 to 130.59. Employing the BandAids technique yields a 78.67% drag reduction, from 473.91 to 99.98. The RAE 2822 case exhibited a drag reduction from 217.79 to 132.79 counts, a 39.05% decrease using BandAids.
Load flow analysis: Base cases, data, diagrams, and results
Energy Technology Data Exchange (ETDEWEB)
Portante, E.C.; Kavicky, J.A.; VanKuiken, J.C.; Peerenboom, J.P.
1997-10-01
This report describes how an electric utility system is modeled by using load flow techniques to establish a validated power flow case suitable for simulating and evaluating alternative system scenarios. Details of the load flow model are supported by additional technical and descriptive information intended to correlate modeled electrical system parameters with the corresponding physical equipment that makes up the system. Pictures and technical specifications of system equipment from the utility, public, or vendor are provided to support this association for many system components. The report summarizes the load flow model construction, simulation, and validation and describes the general capabilities of an information query system designed to access load flow parameters and other electrical system information.
Compact Mass Flow Meter Based on a Micro Coriolis Flow Sensor
Directory of Open Access Journals (Sweden)
Remco Wiegerink
2013-03-01
Full Text Available In this paper we demonstrate a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 1 g/h (for water at a pressure drop < 1 bar. It has a zero stability of 2 mg/h and an accuracy of 0.5% reading for both liquids and gases. The temperature drift between 10 and 50 °C is below 1 mg/h/°C. The meter is robust, has standard fluidic connections and can be read out by means of a PC or laptop via USB. Its performance was tested for several common gases (hydrogen, helium, nitrogen, argon and air and liquids (water and isopropanol. As in all Coriolis mass flow meters, the meter is also able to measure the actual density of the medium flowing through the tube. The sensitivity of the measured density is ~1 Hz.m3/kg.
Space Launch System Base Heating Test: Environments and Base Flow Physics
Mehta, Manish; Knox, Kyle S.; Seaford, C. Mark; Dufrene, Aaron T.
2016-01-01
The NASA Space Launch System (SLS) vehicle is composed of four RS-25 liquid oxygen-hydrogen rocket engines in the core-stage and two 5-segment solid rocket boosters and as a result six hot supersonic plumes interact within the aft section of the vehicle during flight. Due to the complex nature of rocket plume-induced flows within the launch vehicle base during ascent and a new vehicle configuration, sub-scale wind tunnel testing is required to reduce SLS base convective environment uncertainty and design risk levels. This hot-fire test program was conducted at the CUBRC Large Energy National Shock (LENS) II short-duration test facility to simulate flight from altitudes of 50 kft to 210 kft. The test program is a challenging and innovative effort that has not been attempted in 40+ years for a NASA vehicle. This paper discusses the various trends of base convective heat flux and pressure as a function of altitude at various locations within the core-stage and booster base regions of the two-percent SLS wind tunnel model. In-depth understanding of the base flow physics is presented using the test data, infrared high-speed imaging and theory. The normalized test design environments are compared to various NASA semi-empirical numerical models to determine exceedance and conservatism of the flight scaled test-derived base design environments. Brief discussion of thermal impact to the launch vehicle base components is also presented.
Cloud-based large-scale air traffic flow optimization
Cao, Yi
The ever-increasing traffic demand makes the efficient use of airspace an imperative mission, and this paper presents an effort in response to this call. Firstly, a new aggregate model, called Link Transmission Model (LTM), is proposed, which models the nationwide traffic as a network of flight routes identified by origin-destination pairs. The traversal time of a flight route is assumed to be the mode of distribution of historical flight records, and the mode is estimated by using Kernel Density Estimation. As this simplification abstracts away physical trajectory details, the complexity of modeling is drastically decreased, resulting in efficient traffic forecasting. The predicative capability of LTM is validated against recorded traffic data. Secondly, a nationwide traffic flow optimization problem with airport and en route capacity constraints is formulated based on LTM. The optimization problem aims at alleviating traffic congestions with minimal global delays. This problem is intractable due to millions of variables. A dual decomposition method is applied to decompose the large-scale problem such that the subproblems are solvable. However, the whole problem is still computational expensive to solve since each subproblem is an smaller integer programming problem that pursues integer solutions. Solving an integer programing problem is known to be far more time-consuming than solving its linear relaxation. In addition, sequential execution on a standalone computer leads to linear runtime increase when the problem size increases. To address the computational efficiency problem, a parallel computing framework is designed which accommodates concurrent executions via multithreading programming. The multithreaded version is compared with its monolithic version to show decreased runtime. Finally, an open-source cloud computing framework, Hadoop MapReduce, is employed for better scalability and reliability. This framework is an "off-the-shelf" parallel computing model
MEMS-based flow cytometry: microfluidics-based cell identification system by fluorescent imaging.
Wu, W K; Liang, C K; Huang, J Z
2004-01-01
This study utilizes MEMS technology to realize a novel low-cost microfluidics-based biochip system for flow-type cell handling. Powered by vacuum pump, the microfluidic driving system enables cells to move in order one by one in the biochip by an effect of sheath flow prefocus. Then, cells are guided to a fluorescent inspection region where two detection tasks such as cell image identification and cell counting are conducted. Currently, the glass-based biochip has been manufactured and all the related devices have been well set up in our laboratory. With this proposed prototype system, typical results about cell separation of yeast cell and PC-3 cell are available and their separated images are also presented, respectively. PMID:17270801
Sienkiewicz, Andrzej; Ferreira, Ana Maria da Costa; Danner, Birgit; Scholes, Charles P.
1999-02-01
We report methodology which combines recently developed dielectric resonator-based, rapid-mix, stopped-flow EPR (appropriate for small, aqueous, lossy samples) with rapid scanning of the external (Zeeman) magnetic field where the scanning is preprogrammed to occur at selected times after the start of flow. This methodology gave spectroscopic information complementary to that obtained by stopped-flow EPR at single fields, and with low reactant usage, it yielded more graphic insight into the time evolution of radical and spin-labeled species. We first used the ascorbyl radical as a test system where rapid scans triggered after flow was stopped provided "snapshots" of simultaneously evolving and interacting radical species. We monitored ascorbyl radical populations either as brought on by biologically damaging peroxynitrite oxidant or as chemically and kinetically interacting with a spectroscopically overlapping nitroxide radical. In a different biophysical application, where a spin-label lineshape reflected rapidly changing molecular dynamics of folding spin-labeled protein, rapid scan spectra were taken during flow with different flow rates and correspondingly different times after the mixing-induced inception of protein folding. This flow/rapid scan method is a means for monitoring early immobilization of the spin probe in the course of the folding process.
Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project
Oliva-Buisson, Yvette J.
2014-01-01
Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.
Non-Aqueous Li-Based Redox Flow Batteries
Hamelet, Stéphane; Tzedakis, Théodore; Leriche, Jean- Bernard; Sailler, Sébastien; Larcher, Dominique; Taberna, Pierre-Louis; Simon, Patrice; Tarascon, Jean-Marie
2012-01-01
Redox flow batteries have gained renewed interest for grid storage applications. This work focuses on the effect of various chemical/physical parameters on the performance of the LiFePO4/LiPF6 EC-DMC/Li redox flow system. A methodical study of the influence of the content of active material and of the flow rate, coupled with electrochemical and hydrodynamic characterizations, have been carried out in order to better understand the various ‘migration’ and ‘diffusion’ limitations, as well as to...
Simulation of SBLOCA based on an Improved Choked Flow Model for RELAP5/MOD3 Code
International Nuclear Information System (INIS)
This paper is a continuation of the present author's previous publication dealing with a new choked flow model for two-phase flow. The model based on a hyperbolic one-dimensional two-fluid model, where in the momentum equations the terms representing the interfacial pressure difference has been included in lieu of the virtual mass force terms. The new choked flow model is an improvement upon the choked flow model of the current RELAP5/MOD3 code, which itself is based on the Trapp-Ransom method. The author compares the predictions of this improved model with Trapp-Ransom model and Henry-Fauske model, for an assumed flow in a vertical pipe. The author simulates a typical PWR system with a hypothetical SBLOCA as well, and compares the system behaviors predicted by RELAP5/MOD3, based on the aforementioned choked flow models. He shows that the improved choked flow model leads to better predictions
Zheng, Qiong; Xing, Feng; Li, Xianfeng; Ning, Guiling; Zhang, Huamin
2016-08-01
Vanadium flow battery holds great promise for use in large scale energy storage applications. However, the power density is relatively low, leading to significant increase in the system cost. Apart from the kinetic and electronic conductivity improvement, the mass transport enhancement is also necessary to further increase the power density and reduce the system cost. To better understand the mass transport limitations, in the research, the space-varying and time-varying characteristic of the mass transport polarization is investigated based on the analysis of the flow velocity and reactant concentration in the bulk electrolyte by modeling. The result demonstrates that the varying characteristic of mass transport polarization is more obvious at high SoC or high current densities. To soften the adverse impact of the mass transport polarization, a new rectangular plug flow battery with a plug flow and short flow path is designed and optimized based on the mass transport polarization regulation (reducing the mass transport polarization and improving its uniformity of distribution). The regulation strategy of mass transport polarization is practical for the performance improvement in VFBs, especially for high power density VFBs. The findings in the research are also applicable for other flow batteries and instructive for practical use.
Aircraft Proximity Maps Based on Data-Driven Flow Modeling
National Aeronautics and Space Administration — With the forecast increase in air traffic demand over the next decades, it is imperative to develop tools to provide traffic flow managers with the information...
A service and value based approach to estimating environmental flows
DEFF Research Database (Denmark)
Korsgaard, Louise; Jensen, R.A.; Jønch-Clausen, Torkil;
2008-01-01
An important challenge of Integrated Water Resources Management (IWRM) is to balance water allocation between different users and uses. While economically and/or politically powerful users have relatively well developed methods for quantifying and justifying their water needs, this is not the case...... a matter of sustaining ecosystems but also a matter of supporting humankind/livelihoods. One reason for the marginalisation of environmental flows is the lack of operational methods to demonstrate the inherently multi-disciplinary link between environmental flows, ecosystem services and economic...... environmental flows assessment methodologies. The SPI approach is a pragmatic and transparent tool for incorporating ecosystems and environmental flows into the evaluation of water allocation scenarios, negotiations of trade-offs and decision-making in IWRM....
Traffic Flow Detection Based on Wireless Sensor Network
Bao-juan Liang
2013-01-01
Detecting traffic flow by in-road inductive loop is the most common methods, but inductive loop is physically large, it is hard to install and maintain, also the classification rate is low. The inductive loops cannot communicate with each other, so they cannot share traffic data with each other. The wireless sensor network has these features: real-time, fault tolerance, scalability and coordination. Applying wireless sensor network into traffic area for traffic flow detection is easier to ins...
Wind-Induced Ventilation Based on the Separated Flow Region
Directory of Open Access Journals (Sweden)
Mostafa Rahimi
2016-01-01
Full Text Available An experimental investigation was conducted to study the potential use of the pressure reduction within the separated flow region followed by the wake at the leeward direction of a solid surface in natural ventilation of buildings. Air flow with mean velocity up to 7 m/s was directed onto a solid surface (circular plate and a semi-spherical surface behind which the top end of a vertical vent pipe had been placed. Pressure reduction at the exit section of the pipe, which was well inside the separated flow region, induced an air flow within the pipe. This air flow rate from the stagnant surroundings into the wake region was measured under different geometrical configurations and for various wind velocities. The study revealed that the pressure reduction within the separated flow region would be applicable for natural ventilation of different spaces at least as an auxiliary system. The spaces include; sanitary places, crop protection stocks, industrial workshops and other spaces where no regular ventilation is required.
Compact mass flow meter based on a micro Coriolis flow sensor
Sparreboom, W.; Katerberg, M.R.; Lammerink, T.S.J.; Postma, F.M.; Haneveld, J.; Groenesteijn, J.; Wiegerink, R.J.; Lötters, J.C.
2012-01-01
In this paper we present a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 2 g/h (for water at a pressure drop of 2 bar). It has a zero stability of 2 mg/h and an accuracy of 0.5% reading. The temperature drift between 10 and 50 ºC is below 1 mg/h/ºC. The meter is robust, has standard fluidic connections and can be read out by a PC or laptop via USB. Its performance was tested for several common gases (helium, nitrogen, argon and air) and liquids (water and IPA).
Compact mass flow meter based on a micro coriolis flow sensor
Remco Wiegerink; Theo Lammerink; Jarno Groenesteijn; Jeroen Haneveld; Ferry Postma; Marcel Katerberg; Wouter Sparreboom; Jan van de Geest; Joost Lötters
2013-01-01
In this paper we demonstrate a compact ready-to-use micro Coriolis mass flow meter. The full scale flow is 1 g/h (for water at a pressure drop < 1 bar). It has a zero stability of 2 mg/h and an accuracy of 0.5% reading for both liquids and gases. The temperature drift between 10 and 50 °C is below 1 mg/h/°C. The meter is robust, has standard fluidic connections and can be read out by means of a PC or laptop via USB. Its performance was tested for several common gases (hydrogen, helium, nitrog...
Dasari, Teja; Toloui, Mostafa; Guala, Michele; Hong, Jiarong
2015-11-01
Super-large-scale particle image velocimetry and flow visualization techniques using natural snow particles have been shown as an effective tool to probe the structure of the flow around full-scale wind turbines (Hong et al. Nature Comm. 2014). Here we present a follow-up study based on the data collected during a deployment around the 2.5 MW wind turbine at EOLOS Wind Energy Research Station on April, 4th, 2014. The dataset includes the snow visualization of flow fields from different perspectives in the near wake of the turbine. The motions of the dominant coherent structures including tip, blade root, hub and tower vortices, represented by the snow voids, are examined with the objective of quantifying and correlating their behavior with the meteorological and turbine operating conditions. Some preliminary studies on flow-structure interaction are also performed by correlating the data from strain gauges, accelerometers mounted on the turbine blades, with the flow measurements. The statistical analysis of the motions of blade induced vortices shows a clear impact of atmospheric turbulence and vortex interaction on flow development in the near wake. The result further indicates a strong connection between near-wake vorticity field, turbine operation and structure deformations. The work was supported by National Science Foundation (NSF-CBET-1454259) and the research infrastructure was supported by Department of Energy.
International Nuclear Information System (INIS)
We report the development of a self-resonant flow sensor based on a resonant frequency shift due to flow-induced vibrations. The vibration of a microcantilever beam, induced by a turbulent flow, is modulated with its own natural frequency, and the resonant frequency is shifted by a surface stress on the beam due to fluid drag force. The vibration induced by air flow is measured by using a piezoelectric PZT material on a silicon cantilever beam. The theoretical resonant frequencies of two cantilever beams (lengths: 610 µm and 2000 µm) are 12416 Hz and 1155 Hz, respectively. For the air flow velocities of 2.8 m s−1 and 9.7 m s−1, the shifted resonant frequencies of the cantilever beam whose length is 610 µm are 12 810 Hz and 15 602 Hz, respectively. Sensitivities of the two self-resonant flow sensors with the 610 and 2000 µm long beams are approximately 384 ± 15 Hz/(m/s) and 20.4 ± 0.6 Hz/(m/s), respectively.
flowCL: ontology-based cell population labelling in flow cytometry
Courtot, Mélanie; Meskas, Justin; Diehl, Alexander D.; Droumeva, Radina; Gottardo, Raphael; Jalali, Adrin; Taghiyar, Mohammad Jafar; Maecker, Holden T; McCoy, J. Philip; Ruttenberg, Alan; Scheuermann, Richard H.; Brinkman, Ryan R
2014-01-01
Motivation: Finding one or more cell populations of interest, such as those correlating to a specific disease, is critical when analysing flow cytometry data. However, labelling of cell populations is not well defined, making it difficult to integrate the output of algorithms to external knowledge sources.
Shan Yang; Xiangqian Tong
2016-01-01
Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverte...
Flow improvers for water injection based on surfactants
Energy Technology Data Exchange (ETDEWEB)
Oskarsson, H.; Uneback, I.; Hellsten, M.
2006-03-15
In many cases it is desirable to increase the flow of injection water when an oil well deteriorates. It is very costly in offshore operation to lay down an additional water pipe to the injection site. Flow improvers for the injection water will thus be the most cost-effective way to increase the flow rate. During the last years water-soluble polymers have also been applied for this purpose. These drag-reducing polymers are however only slowly biodegraded which has been an incentive for the development of readily biodegradable surfactants as flow improvers for injection water. A combination of a zwitterionic and an anionic surfactant has been tested in a 5.5 inch, 700 m long flow loop containing sulphate brine with salinity similar to sea water. A drag reduction between 75 and 80% was achieved with 119 ppm in solution of the surfactant blend at an average velocity of 1.9 m/s and between 50 and 55% at 2.9 m/s. The surfactants in this formulation were also found to be readily biodegradable in sea water and low bio accumulating which means they have an improved environmental profile compared to the polymers used today. Due to the self-healing properties of the drag-reducing structures formed by surfactants, these may be added before the pump section - contrary to polymers which are permanently destroyed by high shear forces. (Author)
Flow improvers for water injection based on surfactants
International Nuclear Information System (INIS)
In many cases it is desirable to increase the flow of injection water when an oil well deteriorates. It is very costly in offshore operation to lay down an additional water pipe to the injection site. Flow improvers for the injection water will thus be the most cost-effective way to increase the flow rate. During the last years water-soluble polymers have also been applied for this purpose. These drag-reducing polymers are however only slowly biodegraded which has been an incentive for the development of readily biodegradable surfactants as flow improvers for injection water. A combination of a zwitterionic and an anionic surfactant has been tested in a 5.5 inch, 700 m long flow loop containing sulphate brine with salinity similar to sea water. A drag reduction between 75 and 80% was achieved with 119 ppm in solution of the surfactant blend at an average velocity of 1.9 m/s and between 50 and 55% at 2.9 m/s. The surfactants in this formulation were also found to be readily biodegradable in sea water and low bio accumulating which means they have an improved environmental profile compared to the polymers used today. Due to the self-healing properties of the drag-reducing structures formed by surfactants, these may be added before the pump section - contrary to polymers which are permanently destroyed by high shear forces. (Author)
An Examination of Game-Based Learning from Theories of Flow Experience and Cognitive Load
Lai, Chih-Hung; Chu, Chih-Ming; Liu, Hsiang-Hsuan; Yang, Shun-Bo; Chen, Wei-Hsuan
2013-01-01
This study aims to discuss whether game-based learning with the integration of games and digital learning could enhance not only the flow experience in learning but achieve the same flow experience in pure games. In addition, the authors discovered that whether the game-based learning could make learners to reveal higher cognitive load. The…
Peters, E.; Lanen, van H.A.J.
2005-01-01
A new filter to separate base flow from streamflow has developed that uses observed groundwater levels. To relate the base flow to the observed groundwater levels, a non-linear relation was used. This relation is suitable for unconfined aquifers with deep groundwater levels that do not respond to in
Flow Detection Based on Traffic Video Image Processing
Directory of Open Access Journals (Sweden)
Peng Shen
2013-10-01
Full Text Available Because in the traffic video image processing, the background image gotten from background modeling by traditional k-means clustering algorithm shows a lot of noises, thus the improvement of k-means clustering algorithm is proposed, and has been applied to the vehicle flow detection of traffic video image. By analyzing the vehicle detection method and comparing the flow detection algorithm, the improved k-means clustering algorithm is experimentally tested at last, and carries out software implementation. The experiment shows that the improved algorithm after background modeling is superior to the traditional one in time complexity, it has better adaptivity and robustness, which has increased the effect of vehicle flow detection.
Base flow separation: A comparison of analytical and mass balance methods
Lott, Darline A.; Stewart, Mark T.
2016-04-01
Base flow is the ground water contribution to stream flow. Many activities, such as water resource management, calibrating hydrological and climate models, and studies of basin hydrology, require good estimates of base flow. The base flow component of stream flow is usually determined by separating a stream hydrograph into two components, base flow and runoff. Analytical methods, mathematical functions or algorithms used to calculate base flow directly from discharge, are the most widely used base flow separation methods and are often used without calibration to basin or gage-specific parameters other than basin area. In this study, six analytical methods are compared to a mass balance method, the conductivity mass-balance (CMB) method. The base flow index (BFI) values for 35 stream gages are obtained from each of the seven methods with each gage having at least two consecutive years of specific conductance data and 30 years of continuous discharge data. BFI is cumulative base flow divided by cumulative total discharge over the period of record of analysis. The BFI value is dimensionless, and always varies from 0 to 1. Areas of basins used in this study range from 27 km2 to 68,117 km2. BFI was first determined for the uncalibrated analytical methods. The parameters of each analytical method were then calibrated to produce BFI values as close to the CMB derived BFI values as possible. One of the methods, the power function (aQb + cQ) method, is inherently calibrated and was not recalibrated. The uncalibrated analytical methods have an average correlation coefficient of 0.43 when compared to CMB-derived values, and an average correlation coefficient of 0.93 when calibrated with the CMB method. Once calibrated, the analytical methods can closely reproduce the base flow values of a mass balance method. Therefore, it is recommended that analytical methods be calibrated against tracer or mass balance methods.
CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS
DEFF Research Database (Denmark)
Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik;
2010-01-01
The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats. A...... reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency...
A contribution about ferrofluid based flow manipulation and locomotion systems
Energy Technology Data Exchange (ETDEWEB)
Zimmermann, K; Zeidis, I; Bohm, V; Popp, J [TU Ilmenau, Fak. f. Maschinenbau, FG Technische Mechanik, Max-Planck-Ring 12, 98693 Ilmenau (Germany)], E-mail: klaus.zimmermann@tu-ilmenau.de, E-mail: jana.popp@tu-ilmenau.de
2009-02-01
With the background of developing apedal bionic inspired locomotion systems for future application fields like autonomous (swarm) robots, medical engineering and inspection systems, this article presents a selection of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realised. The locomotion of an object is caused in the first example by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.
A contribution about ferrofluid based flow manipulation and locomotion systems
International Nuclear Information System (INIS)
With the background of developing apedal bionic inspired locomotion systems for future application fields like autonomous (swarm) robots, medical engineering and inspection systems, this article presents a selection of locomotion systems with bifluidic flow control using ferrofluid. By controlling the change of shape, position and pressure of the ferrofluid in a secondary low viscous fluid by magnetic fields locomotion of objects or the ferrofluid itself can be realised. The locomotion of an object is caused in the first example by a ferrofluid generated flow of the secondary fluid and in the second and third case by the direct alteration of the ferrofluid position.
Thermistor based, low velocity isothermal, air flow sensor
International Nuclear Information System (INIS)
The semiconductor thermistor technology is applied as a flow sensor to measure low isothermal air velocities (<2 ms−1). The sensor is subjected to heating and cooling cycles controlled by a multifunctional timer. In the heating stage, the alternating current of a main AC power supply source guarantees a uniform thermistor temperature distribution. The conditioning circuit assures an adequate increase of the sensors temperature and avoids the thermal disturbance of the flow. The power supply interruption reduces the consumption from the source and extends the sensors life time. In the cooling stage, the resistance variation of the flow sensor is recorded by the measuring chain. The resistive sensor parameters proposed vary significantly and feature a high sensitivity to the flow velocity. With the aid of a computer, the data transfer, storage and analysis provides a great advantage over the traditional local anemometer readings. The data acquisition chain has a good repeatability and low standard uncertainties. The proposed method measures isothermal air mean velocities from 0.1 ms−1 to 2 ms−1 with a standard uncertainty error less than 4%. (paper)
Flow logic for language-based safety and security
DEFF Research Database (Denmark)
Hansen, René Rydhof
2005-01-01
the Flow Logic framework for static analysis is particularly useful this regard. In order to support and illustrate the above points, a number of program analyses are developed for the Carmel programming language, a variant of the low-level language used on Java smart cards. The analyses are formally...
Basin Division Method for TIN-based DEM with Face-Node-Edge Flow Mode
International Nuclear Information System (INIS)
The basin serving as a basic unit is of great importance for flood inundation and other hydrological fields. Most existing basin division methods have been proposed for a raster-based DEM and used in some hydrological software, such as the ArcHydro tool and the RiverTool. Unfortunately, raster has some limitations when compared to TIN; specifically, it cannot depict real ground water flow accurately and reasonably. Referring to the natural law of gravity, which dictates water flowing from high to low areas, we present a Face-Node-Edge (FNE) flow mode for TIN-based DEM. The FNE flow mode assumes the water on each triangle facet flows to its lowest node initially. The water on the lowest node then flows along the steepest edge to its neighbour node; the flow continues until the neighbour nodes' elevations are higher than its own. Meanwhile, upstream triangles pass their flow flags to the downstream triangles along the flow path. After that we can generate basins according to the flags. The case studies demonstrate that the proposed FNE flow mode and basin division method for TIN-based DEM are correct, which can provide more reasonable basin division results than raster, e.g., the ArcHydro tool
CIS-Based Risk Assessment of Debris Flow Disasters in the Upper Reach of Yangtze River
Institute of Scientific and Technical Information of China (English)
HAN Yongshun; LIU Hongjiang; ZHONG Dunlun; SU Fenghuan; LI Chaokui
2007-01-01
This paper discussed theory and methodologies of debris-flow risk assessment and established an implementation process according to indicators of debris-flow hazard degree, vulnerability, risk degree, etc. Among these methodologies, historical and potential hazard degree was comprehensively considered into hazard assessment and hazard index was presented to indicate the debris-flow hazard degree. Regarding debris-flow vulnerability assessment, its statistical data and calculating procedure were based on the hazard-degree regionalization instead of administrative divisions, which improved the assessing scientificity and precision. These quantitative methodologies integrated with Geography Information System (GIS) were applied to the risk assessment of debris flows in the upper reach of Yangtze River. Its results were in substantial agreement on investigation data and the actual distribution of debris flows, which showed that these principles and methodologies were reasonable and feasible and can provide basis or reference for debris-flow risk assessment and disaster management.
Fluent-based numerical simulation of flow centrifugal fan
Institute of Scientific and Technical Information of China (English)
LI Xian-zhang
2011-01-01
Testing centrifugal fan flow field by physical laboratory is difficult because the testing system is complex and the workload is heavy, and the results observed by naked-eye deviates far from the actual value. To address this problem, the computational fluid dynamics software FLUENT was applied to establish three-dimensional model of the centrifugal fan. The numeral model was verified by comparing simulation data to experimental data. The pressure centrifugal fan and the speed changes in distribution in centrifugal fan was simulated by computational fluid dynamics software FLUENT. The simulation results show that the gas flow velocity in the impeller increases with impeller radius increase. Static pressure gradually increases when gas from the fan access is imported through fan impeller leaving fans.
Accurate Multisteps Traffic Flow Prediction Based on SVM
Zhang Mingheng; Zhen Yaobao; Hui Ganglong; Chen Gang
2013-01-01
Accurate traffic flow prediction is prerequisite and important for realizing intelligent traffic control and guidance, and it is also the objective requirement for intelligent traffic management. Due to the strong nonlinear, stochastic, time-varying characteristics of urban transport system, artificial intelligence methods such as support vector machine (SVM) are now receiving more and more attentions in this research field. Compared with the traditional single-step prediction method, the mul...
Security and Network monitoring based on Internet flow measurements
Wagner, Cynthia
2012-01-01
Today's networks face continuously arising new threats, making analysis of network data for the detection of anomalies in current operational networks essential. Network operators have to deal with the analysis of huge volumes of data. To counter this main issue, dealing with IP flows (also known as Netflows) records is common in network management. However in modern networks, even Netflow records still represent a high volume of data. Interest in traffic classification as well as attack and...
Multiphase flow measurement using gamma-based techniques
Arubi, Isaac Marcus Tesi
2011-01-01
The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves. This has led oil companies to develop smaller/marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective soluti8ons of on-line continuous multiphase flow measurement. The pattern recognition approach for clamp-on multiphase measurement employed in this resea...
Scenario based security evaluation: Generic OpenFlow network
Lähteenmäki, Jarno
2014-01-01
Demand for network programmability was recognized when development of protocolsslowed down due to network inflexibilities in 1980s. Research speeded up andmany proposals were made to solve architectural issues during 2000s. Academicworld put up an initiative to build up new programmable network architecturelater 2000s. OpenFlow was born.In modern public network infrastructures the security of the network architectureis crucial to archive data confidentiality, integrity and authenticity, yet h...
MANAGEMENT FINANCIAL FLOWS OF CONSTRUCTION ENTERPRISES BASED LOGISTICS BUDGETING
Bubenko, P.
2014-01-01
The aim of the paper is the development of scientific knowledge and understandings of place value and essence of logistics budgeting.Proved that increasing the competitiveness of budgeting should improve mechanisms of logistics processes, which leads to the creation of new economic category logistics budgeting. We consider such economic categories as cash flow, budget, budgeting, logistics, analyzes and presents the advantages and disadvantages of budgeting and budgeting logistics enterprises...
Characteristic-Based Split Meshless Solution for Couette Flow
Directory of Open Access Journals (Sweden)
Mužík Juraj
2014-05-01
Full Text Available The paper deals with use of the meshless method for incompressible fluid flow analysis. There are many formulations of the meshless methods. The article presents the Meshless Local Petrov-Galerkin method (MLPG - local weak formulation of the Navier-Stokes equations. The shape function construction is the crucial part of the meshless numerical analysis in the construction of shape functions. The article presents the radial point interpolation method (RPIM for the shape functions construction
GPU-Based Parallelized Solver for Large Scale Vascular Blood Flow Modeling and Simulations.
Santhanam, Anand P; Neylon, John; Eldredge, Jeff; Teran, Joseph; Dutson, Erik; Benharash, Peyman
2016-01-01
Cardio-vascular blood flow simulations are essential in understanding the blood flow behavior during normal and disease conditions. To date, such blood flow simulations have only been done at a macro scale level due to computational limitations. In this paper, we present a GPU based large scale solver that enables modeling the flow even in the smallest arteries. A mechanical equivalent of the circuit based flow modeling system is first developed to employ the GPU computing framework. Numerical studies were employed using a set of 10 million connected vascular elements. Run-time flow analysis were performed to simulate vascular blockages, as well as arterial cut-off. Our results showed that we can achieve ~100 FPS using a GTX 680m and ~40 FPS using a Tegra K1 computing platform. PMID:27046603
Intense transport of bed load - modeling based on experimentally observed flow structure
Matoušek, Václav
2016-04-01
A modeling approach is discussed which enables to predict characteristics of steady uniform open-channel flow carrying a large amount of sediment (bed load). The approach considers a layered structure of the sediment-laden flow and employs conditions at layer interfaces to evaluate the flow slope, depth, the thickness of the layers and flow rates of both the sediment and sediment-water mixture. It is based on experimental observations obtained for lightweight granular materials in a laboratory tilting flume. Besides visual observations of a development of the layered structure of the flow, detailed profiles of the longitudinal velocity were collected together with integral characteristics of the flow (depths and slopes, flow rates) in the flume. Values of the grain velocity and concentration at the interfaces were determined from the measurements and observations. In the upper plane bed regime of bed load transport, the flow structure appears to be composed of up to three distinct layers (water layer, linear collisional layer and dense sliding layer). Depending on a value of the bed Shields parameter (and associated flow conditions) the number of layers may change and the thicknesses of the particular layers vary. It appears that collisional layers in flows in which they dominate the flow depth (typically Shields bigger than 1) exhibit a virtually constant value of the collisional-layer Richardson number. Velocity and concentration profiles across the collisional layer can be considered linear. At the bottom of the flow, the Coulomb yield criterion with the assumption of the zero fluid contribution balances the bed shear stress applied by the flowing mixture of water and sediment. These features are employed in the discussed modeling approach and lead to a depth-averaged flow model composed of a set of balance and constitutive equations. A kinetic-theory based formula for granular shear stress at the bottom of the collisional layer is added to close the set of
Detection and Identification of Android Malware Based on Information Flow Monitoring
Andriatsimandefitra, Radoniaina; Viet Triem Tong, Valérie
2015-01-01
Information flow monitoring has been mostly used to detect privacy leaks. In a previous work, we showed that they can also be used to characterize Android malware behaviours and in the current one we show that these flows can also be used to detect and identify Android malware. The characterization consists in computing automatically System Flow Graphs that describe how a malware disseminates its data in the system. In the current work, we propose a method that uses these SFG- based malware p...
An effective depression filling algorithm for DEM-based 2-dimensional surface flow modelling
Zhu, D.; Ren, Q.; Xuan, Y.; Y. Chen; Cluckie, I.
2012-01-01
The surface runoff process in fluvial/pluvial flood modelling is often simulated employing a two-dimensional (2-D) diffusive wave approximation to described by grid based digital elevation models (DEMs). However, a serious problem of this approach may arise when using a 2-D surface flow model which exchanges flows through adjacent cells, or conventional rink removal algorithms which also allow flow to be exchanged along diagonal directions, due to the existence of artificial depression in ...
An effective depression filling algorithm for DEM-based 2-D surface flow modelling
Zhu, D.; Ren, Q.; Xuan, Y.; Y. Chen; I. D. Cluckie
2013-01-01
The surface runoff process in fluvial/pluvial flood modelling is often simulated employing a two-dimensional (2-D) diffusive wave approximation described by grid based digital elevation models (DEMs). However, this approach may cause potential problems when using the 2-D surface flow model which exchanges flows through adjacent cells, with conventional sink removal algorithms which also allow for flow exchange along diagonal directions, due to the existence of artificial dep...
Satellite Angular Velocity Estimation Based on Star Images and Optical Flow Techniques
Giancarmine Fasano; Giancarlo Rufino; Domenico Accardo; Michele Grassi
2013-01-01
An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares...
An optical fiber Fabry-Perot flow measurement technology based on partial bend structure
Yang, Huijia; Jiang, Junfeng; Zhang, Xuezhi; Pan, Yuheng; Zhu, Wanshan; Zhou, Xiang; Liu, Tiegen
2016-08-01
An optical fiber Fabry-Perot (F-P) flow measurement technology is presented, which is based on partial bend structure. A 90° partial bend structure is designed to achieve the non-probe flow measurement with a pressure difference. The fluid simulation results of partial bend structure show that the error of the pressure difference is below 0.05 kPa during steady flow. The optical fiber F-P sensor mounted on the elbow with pressure test accuracy of 1% full scale is used to measure the fluid flow. Flow test results show that when the flow varies from 1 m3/h to 6.5 m3/h at ambient temperature of 25 °C, the response time is 1 s and the flow test accuracy is 4.5% of the F-P flow test system, proving that the F-P flow test method based on partial bend structure can be used in fluid flow measurement.
Huang, Pao-Cheng; Wang, Min-Haw; Chen, Ming-Kun; Jang, Ling-Sheng
2016-05-01
Flow rate sensing is a critical issue for piezoelectric-based micropump systems. This paper describes experimental analysis of flow rate sensing in a peristaltic micropump system. Sensing can be integrated with such a pump using piezoelectric actuators based on the time-phase-shift (TPS) method. To do this, an evaluation-window is added on the falling edge of the driving pulse to help detect the flow velocity without affecting the flow rate. We fabricate a prototype piezoelectric peristaltic micropump with three chambers and three piezoelectric actuators. The middle actuator works not only as an actuator for driving fluid but also as a transducer for sensing flow rate. An evaluation-window is performed to ascertain the relationship between the flow rate and the phase shift of output-signal responses from the transducer. The experimental results show that the evaluation-window response of flow rates in a piezoelectric peristaltic micropump has rates of from 5.56‒33.36 μl s-1. The results are extended to propose a practical flow rate sensor, the design of which can be realized easily in the piezoelectric peristaltic micropump system for sensorless responses that can detect flow rate without any sensors or circuits. The proposed TPS method is real-time, integrated, fast, efficient, and suitable for flow rate detection in piezoelectric peristaltic micropumps.
Calculation of the Instream Ecological Flow of the Wei River Based on Hydrological Variation
Directory of Open Access Journals (Sweden)
Shengzhi Huang
2014-01-01
Full Text Available It is of great significance for the watershed management department to reasonably allocate water resources and ensure the sustainable development of river ecosystems. The greatly important issue is to accurately calculate instream ecological flow. In order to precisely compute instream ecological flow, flow variation is taken into account in this study. Moreover, the heuristic segmentation algorithm that is suitable to detect the mutation points of flow series is employed to identify the change points. Besides, based on the law of tolerance and ecological adaptation theory, the maximum instream ecological flow is calculated, which is the highest frequency of the monthly flow based on the GEV distribution and very suitable for healthy development of the river ecosystems. Furthermore, in order to guarantee the sustainable development of river ecosystems under some bad circumstances, minimum instream ecological flow is calculated by a modified Tennant method which is improved by replacing the average flow with the highest frequency of flow. Since the modified Tennant method is more suitable to reflect the law of flow, it has physical significance, and the calculation results are more reasonable.
Research on Underwater Vehicle Based on Multiphase Flow Control
Directory of Open Access Journals (Sweden)
Zhang Xiaoshi
2015-01-01
Full Text Available The commercial software ANSYS CFX is used for modeling the hydrodynamic characteristics of submarine-launched vehicle. In the numerical simulations, the SST (Shear Stress Transport turbulence model is employed to describe the turbulence phenomenon occurring in the continuous fluid. The Rayleigh-Plesset equations are applied to analyze the cavitation phenomenon. Three-dimensional numerical simulation was carried out to study the cavity shape, the surface pressure distribution and the drag force with different flow control. The result shows that the gas and the number of ventilation holes control to show any significant impact on the cavity shape and the surface pressure are effective measures to decrease resistance.
Graphene-based battery electrodes having continuous flow paths
Zhang, Jiguang; Xiao, Jie; Liu, Jun; Xu, Wu; Li, Xiaolin; Wang, Deyu
2014-05-24
Some batteries can exhibit greatly improved performance by utilizing electrodes having randomly arranged graphene nanosheets forming a network of channels defining continuous flow paths through the electrode. The network of channels can provide a diffusion pathway for the liquid electrolyte and/or for reactant gases. Metal-air batteries can benefit from such electrodes. In particular Li-air batteries show extremely high capacities, wherein the network of channels allow oxygen to diffuse through the electrode and mesopores in the electrode can store discharge products.
Navier-Stokes solutions for two-dimensional subsonic base flow
Rudy, D. H.
1984-01-01
Methods for determining the effects of mass injection from the trailing edge of a bluff body at low speeds and in transonic flow were numerically studied along with an unmodified blunt-based body to gain insight into the effects of vortex shedding on the base drag. The methodology used to obtain finite-difference solutions to the Navier-Stokes equations for subsonic compressible two-dimensional near-wake flows is presented. The effectiveness of an introduced outflow boundary condition which minimizes reflections back into the computational domain was demonstrated with the solution of a model vortex problem. Calculations of the near-wake flow past a circular cylinder were in excellent agreement with experimental data. Laminar-flow solutions for a blunt-based model with and without a base cavity and with mass injection into the wake agreed qualitatively with experimental observations. The drag reduction capability provided by such base modifications was demonstrated.
3D CFD computations of trasitional flows using DES and a correlation based transition model
DEFF Research Database (Denmark)
Sørensen, Niels N.; Bechmann, Andreas; Zahle, Frederik
2011-01-01
The present article describes the application of the correlation based transition model of Menter et al. in combination with the Detached Eddy Simulation (DES) methodology to two cases with large degree of flow separation typically considered difficult to compute. Firstly, the flow is computed over...
Control Synthesis for the Flow-Based Microfluidic Large-Scale Integration Biochips
DEFF Research Database (Denmark)
Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan;
2013-01-01
In this paper we are interested in flow-based microfluidic biochips, which are able to integrate the necessary functions for biochemical analysis on-chip. In these chips, the flow of liquid is manipulated using integrated microvalves. By combining severalmicrovalves, more complex units, such...
Treatment of Insomnia Based on the Midnight-Noon Ebb-Flow
Institute of Scientific and Technical Information of China (English)
YANG Dong-dong; CHEN Han-bing; WANG Xin-zhong
2010-01-01
@@ The midnight-noon ebb-flow is an ancient TCM theory, which studies the law of ebb-flow and excessdecline of qi and blood of channels and zang-fu organs of the human body, based on hour of the day, yin-yang, and location.
Directory of Open Access Journals (Sweden)
Liushuai CAO
2016-01-01
Full Text Available To estimate the maneuverability of a submarine at the early design stage, an accurate evaluation of the hydrodynamic coefficients is important. In a collaborative exercise, the authors performed calculations on the bare hull DRAPA SUBOFF submarine to investigate the capability of viscous-flow solvers to predict the forces and moments as well as flow field around the body. A typical simulation program was performed for both the steady drift tests and rotating arm tests. The same grid topology based on multi-block mesh strategy was used to discretize the computational domain. A procedure designated drift sweep was implemented to automatically increment the drift angle during the simulation of steady drift tests. The rotating coordinate system was adopted to perform the simulation of rotating arm tests. The Coriolis force and centrifugal force due to the computation in a rotating frame of reference were treated explicitly and added to momentum equations as source terms. Lastly, the computed forces and moment as a function of angles of drift in both conditions are compared with experimental results and literature values. They always show the correct trend. Flow field quantities including pressure coefficients and vorticity and axial velocity contours are also visualized to vividly describe the evolution of flow motions along the hull.
Robust PCA-Based Abnormal Traffic Flow Pattern Isolation and Loop Detector Fault Detection
Institute of Scientific and Technical Information of China (English)
JIN Xuexiang; ZHANG Yi; LI Li; HU Jianming
2008-01-01
One key function of intelligent transportation systems is to automatically detect abnormal traffic phenomena and to help further investigations of the cause of the abnormality. This paper describes a robust principal components analysis (RPCA)-based abnormal traffic flow pattern isolation and loop detector fault detection method. The results show that RPCA is a useful tool to distinguish regular traffic flow from abnor-mal traffic flow patterns caused by accidents and loop detector faults. This approach gives an effective traffic flow data pre-processing method to reduce the human effort in finding potential loop detector faults. The method can also be used to further investigate the causes of the abnormality.
Pressure Based Method for Solving Viscous Incompressible Flows using Rhie and Chow Interpolation
Directory of Open Access Journals (Sweden)
Anjan H1 , N.Sreenivasalu Reddy2 , Kanchiraya S3
2014-07-01
Full Text Available In this paper a pressure based finite volume method is formulated to solve the viscous incompressible flows using rhie chow interpolation. The method involves employing a different interpolation for advective velocities and provides a connection between the nodal velocity and pressure so there is no odd-even decoupling. The present solver is tested for one Dimensional diffusion problem with and without source term, potential flow equation, and laminar viscous incompressible flows. The results are compared with existing results in the literature. The present study has established that numerical method can provide a reasonable good solution for incompressible viscous flows
Deng, Shijie; Wang, Peng; Liu, Shengnan; Zhao, Tianze; Xu, Shanzhi; Guo, Mingjiang; Yu, Xinglong
2016-01-01
A novel microfluidic flow rate detection method based on surface plasmon resonance (SPR) temperature imaging is proposed. The measurement is performed by space-resolved SPR imaging of the flow induced temperature variations. Theoretical simulations and analysis were performed to demonstrate a proof of concept using this approach. Experiments were implemented and results showed that water flow rates within a wide range of tens to hundreds of μL/min could be detected. The flow rate sensor is resistant to disturbances and can be easily integrated into microfluidic lab-on-chip systems. PMID:27347960
Anisotropic optical flow algorithm based on self-adaptive cellular neural network
Zhang, Congxuan; Chen, Zhen; Li, Ming; Sun, Kaiqiong
2013-01-01
An anisotropic optical flow estimation method based on self-adaptive cellular neural networks (CNN) is proposed. First, a novel optical flow energy function which contains a robust data term and an anisotropic smoothing term is projected. Next, the CNN model which has the self-adaptive feedback operator and threshold is presented according to the Euler-Lagrange partial differential equations of the proposed optical flow energy function. Finally, the elaborate evaluation experiments indicate the significant effects of the various proposed strategies for optical flow estimation, and the comparison results with the other methods show that the proposed algorithm has better performance in computing accuracy and efficiency.
Exponential decay of shearing stress during jerky flows in a Zr-based bulk metallic glass
Directory of Open Access Journals (Sweden)
J. W. Qiao
2013-03-01
Full Text Available Presently, an exponential decay of shearing stresses with the time during jerky flows in a Zr-based bulk metallic glass is revealed. The flow stresses with the time satisfy the following equation: σ = A · e−B · x, where A = −158.24*exp ( − N/47.60 + 1939.63 (N = 1, 2, 3…, and the mean value of obtained B is −0.13 with a Normal distribution. During jerky flows, the viscous shearing layer is formed, and the exponential decay of shear banding is present. The evolvement of shear bands is explained by the consumption of free volumes during flows.
Periodic Flows to Chaos Based on Discrete Implicit Mappings of Continuous Nonlinear Systems
Luo, Albert C. J.
This paper presents a semi-analytical method for periodic flows in continuous nonlinear dynamical systems. For the semi-analytical approach, differential equations of nonlinear dynamical systems are discretized to obtain implicit maps, and a mapping structure based on the implicit maps is employed for a periodic flow. From mapping structures, periodic flows in nonlinear dynamical systems are predicted analytically and the corresponding stability and bifurcations of the periodic flows are determined through the eigenvalue analysis. The periodic flows predicted by the single-step implicit maps are discussed first, and the periodic flows predicted by the multistep implicit maps are also presented. Periodic flows in time-delay nonlinear dynamical systems are discussed by the single-step and multistep implicit maps. The time-delay nodes in discretization of time-delay nonlinear systems were treated by both an interpolation and a direct integration. Based on the discrete nodes of periodic flows in nonlinear dynamical systems with/without time-delay, the discrete Fourier series responses of periodic flows are presented. To demonstrate the methodology, the bifurcation tree of period-1 motion to chaos in a Duffing oscillator is presented as a sampled problem. The method presented in this paper can be applied to nonlinear dynamical systems, which cannot be solved directly by analytical methods.
Towards a von Karman dynamo: numerical studies based on experimental flows
Ravelet, F; Daviaud, F; Leorat, J; Chiffaudel, Arnaud; Daviaud, Francois; Leorat, Jacques; Ravelet, Florent; ccsd-00003337, ccsd
2004-01-01
Numerical studies of a kinematic dynamo based on von K{\\'a}rm{\\'a}n type flows between two counterrotating disks in a finite cylinder are reported. The flow has been optimized using a water model experiment, varying the driving impellers configuration. A solution leading to dynamo action for the mean flow has been found. This solution may be achieved in VKS2, the new sodium experiment to be performed in Cadarache, France. The optimization process is briefly described and discussed, then the effects of adding a stationary conducting layer around the flow on the threshold, on the shape of the neutral mode and on the magnetic energy balance are studied. Finally, the possible processes involved into kinematic dynamo action in a von Karman flow are reviewed and discussed. Among the possible processes we highlight the joint effect of the boundary-layer radial velocity shear and of the Ohmic dissipation localized at the flow/outer-shell boundary.
Schallhorn, Paul; Majumdar, Alok
2012-01-01
This paper describes a finite volume based numerical algorithm that allows multi-dimensional computation of fluid flow within a system level network flow analysis. There are several thermo-fluid engineering problems where higher fidelity solutions are needed that are not within the capacity of system level codes. The proposed algorithm will allow NASA's Generalized Fluid System Simulation Program (GFSSP) to perform multi-dimensional flow calculation within the framework of GFSSP s typical system level flow network consisting of fluid nodes and branches. The paper presents several classical two-dimensional fluid dynamics problems that have been solved by GFSSP's multi-dimensional flow solver. The numerical solutions are compared with the analytical and benchmark solution of Poiseulle, Couette and flow in a driven cavity.
Non-reacting flow visualization of supersonic combustor based on cavity and cavity-strut flameholder
Zhao, Yanhui; Liang, Jianhan; Zhao, Yuxin
2016-04-01
Nano-particle planer laser scattering and particle image velocimetry technology are employed to observe the flow field of scramjet combustors based on cavity and cavity-strut flameholder. Density field and velocity distribution inside combustors are obtained. Mainstream fluid enters into cavity nearby side wall in experimental observation because side wall shock waves interact with bottom wall boundary layer. Cavity fluid is entrained into mainstream in the middle of combustor meanwhile. Flow past cavity displays obvious three dimensional characteristics in both combustors. But cavity-strut combustor displays asymmetrical flow field because of strut configuration. Mass exchange between mainstream and cavity fluid is evaluated by statistic mass flow rate into cavity. Mass flow rate near side wall is raised to 6.62 times of the value in the middle of cavity combustor while it is 5.1 times in cavity-strut combustor. Further study is needed to injection strategies and realistic flow characteristics on condition of combustion.
Are Flow Injection-based Approaches Suitable for Automated Handling of Solid Samples?
DEFF Research Database (Denmark)
Miró, Manuel; Hansen, Elo Harald; Cerdà, Victor
electrolytic or aqueous leaching, on-line dialysis/microdialysis, in-line filtration, and pervaporation-based procedures have been successfully implemented in continuous flow/flow injection systems. In this communication, the new generation of flow analysis, including sequential injection, multicommutated flow......, multisyringe flow injection, and micro-Lab-on-valve are presented as appealing approaches for on-line handling of solid samples. Special emphasis is given to the capability of flow systems to accommodate sequential extraction protocols for partitioning of trace elements and nutrients in environmental solids (e.......g., soils, sediments, sludges), and thus, ascertaining the potential mobility, bioavailability and eventual impact of anthropogenic elements on biota [2]. In this context, the principles of sequential injection-microcolumn extraction (SI-MCE) for dynamic fractionation are explained in detail along with the...
Modelling Shear Flows with SPH and Grid Based Methods
Junk, Veronika; Heitsch, Fabian; Burkert, Andreas; Wetzstein, Markus; Schartmann, Marc; Price, Daniel
2010-01-01
Given the importance of shear flows for astrophysical gas dynamics, we study the evolution of the Kelvin-Helmholtz instability (KHI) analytically and numerically. We derive the dispersion relation for the two-dimensional KHI including viscous dissipation. The resulting expression for the growth rate is then used to estimate the intrinsic viscosity of four numerical schemes depending on code-specific as well as on physical parameters. Our set of numerical schemes includes the Tree-SPH code VINE, an alternative SPH formulation developed by Price (2008), and the finite-volume grid codes FLASH and PLUTO. In the first part, we explicitly demonstrate the effect of dissipation-inhibiting mechanisms such as the Balsara viscosity on the evolution of the KHI. With VINE, increasing density contrasts lead to a continuously increasing suppression of the KHI (with complete suppression from a contrast of 6:1 or higher). The alternative SPH formulation including an artificial thermal conductivity reproduces the analytically ...
Composite separators and redox flow batteries based on porous separators
Li, Bin; Wei, Xiaoliang; Luo, Qingtao; Nie, Zimin; Wang, Wei; Sprenkle, Vincent L.
2016-01-12
Composite separators having a porous structure and including acid-stable, hydrophilic, inorganic particles enmeshed in a substantially fully fluorinated polyolefin matrix can be utilized in a number of applications. The inorganic particles can provide hydrophilic characteristics. The pores of the separator result in good selectivity and electrical conductivity. The fluorinated polymeric backbone can result in high chemical stability. Accordingly, one application of the composite separators is in redox flow batteries as low cost membranes. In such applications, the composite separator can also enable additional property-enhancing features compared to ion-exchange membranes. For example, simple capacity control can be achieved through hydraulic pressure by balancing the volumes of electrolyte on each side of the separator. While a porous separator can also allow for volume and pressure regulation, in RFBs that utilize corrosive and/or oxidizing compounds, the composite separators described herein are preferable for their robustness in the presence of such compounds.
Organic non-aqueous cation-based redox flow batteries
Energy Technology Data Exchange (ETDEWEB)
Jansen, Andrew N.; Vaughey, John T.; Chen, Zonghai; Zhang, Lu; Brushett, Fikile R.
2016-03-29
The present invention provides a non-aqueous redox flow battery comprising a negative electrode immersed in a non-aqueous liquid negative electrolyte, a positive electrode immersed in a non-aqueous liquid positive electrolyte, and a cation-permeable separator (e.g., a porous membrane, film, sheet, or panel) between the negative electrolyte from the positive electrolyte. During charging and discharging, the electrolytes are circulated over their respective electrodes. The electrolytes each comprise an electrolyte salt (e.g., a lithium or sodium salt), a transition-metal free redox reactant, and optionally an electrochemically stable organic solvent. Each redox reactant is selected from an organic compound comprising a conjugated unsaturated moiety, a boron cluster compound, and a combination thereof. The organic redox reactant of the positive electrolyte is selected to have a higher redox potential than the redox reactant of the negative electrolyte.
DEFF Research Database (Denmark)
Heerwagen, Søren T; Hansen, Marc A; Schroeder, Torben V; Ladefoged, Søren D; Lönn, Lars
2012-01-01
Purpose: To test the clinical performance of catheter-based thermodilution and Doppler ultrasound of the feeding brachial artery for blood flow measurements during hemodialysis vascular access interventions.Methods: Thirty patients with arteriovenous fistulas who underwent 46 interventions had...
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries
Energy Technology Data Exchange (ETDEWEB)
Wei, Xiaoliang; Xu, Wu; Vijayakumar, M.; Cosimbescu, Lelia; Liu, Tianbiao L.; Sprenkle, Vincent L.; Wang, Wei
2014-12-03
We will present a novel design lithium-organic non-aqueous redox flow battery based on a TEMPO catholyte. This RFB produced desired electrochemical performance exceeding most of the currently reported nonaqueous RFB systems.
National Aeronautics and Space Administration — Polymer electrolyte membrane water electrolysis units are currently designed to require active water flow and phase separation, or are based on a passive vapor...
Wu, Fu-Chun; Chang, Ching-Fu; Shiau, Jenq-Tzong
2015-05-01
The full range of natural flow regime is essential for sustaining the riverine ecosystems and biodiversity, yet there are still limited tools available for assessment of flow regime alterations over a spectrum of temporal scales. Wavelet analysis has proven useful for detecting hydrologic alterations at multiple scales via the wavelet power spectrum (WPS) series. The existing approach based on the global WPS (GWPS) ratio tends to be dominated by the rare high-power flows so that alterations of the more frequent low-power flows are often underrepresented. We devise a new approach based on individual deviations between WPS (DWPS) that are root-mean-squared to yield the global DWPS (GDWPS). We test these two approaches on the three reaches of the Feitsui Reservoir system (Taiwan) that are subjected to different classes of anthropogenic interventions. The GDWPS reveal unique features that are not detected with the GWPS ratios. We also segregate the effects of individual subflow components on the overall flow regime alterations using the subflow GDWPS. The results show that the daily hydropeaking waves below the reservoir not only intensified the flow oscillations at daily scale but most significantly eliminated subweekly flow variability. Alterations of flow regime were most severe below the diversion weir, where the residual hydropeaking resulted in a maximum impact at daily scale while the postdiversion null flows led to large hydrologic alterations over submonthly scales. The smallest impacts below the confluence reveal that the hydrologic alterations at scales longer than 2 days were substantially mitigated with the joining of the unregulated tributary flows, whereas the daily-scale hydrologic alteration was retained because of the hydropeaking inherited from the reservoir releases. The proposed DWPS approach unravels for the first time the details of flow regime alterations at these intermediate scales that are overridden by the low-frequency high-power flows when
Free-surface flow simulations for discharge-based operation of hydraulic structure gates
Erdbrink, C D; Sloot, P M A
2014-01-01
We combine non-hydrostatic flow simulations of the free surface with a discharge model based on elementary gate flow equations for decision support in operation of hydraulic structure gates. A water level-based gate control used in most of today's general practice does not take into account the fact that gate operation scenarios producing similar total discharged volumes and similar water levels may have different local flow characteristics. Accurate and timely prediction of local flow conditions around hydraulic gates is important for several aspects of structure management: ecology, scour, flow-induced gate vibrations and waterway navigation. The modelling approach is described and tested for a multi-gate sluice structure regulating discharge from a river to the sea. The number of opened gates is varied and the discharge is stabilized with automated control by varying gate openings. The free-surface model was validated for discharge showing a correlation coefficient of 0.994 compared to experimental data. A...
Investigation of vortical flow over bluff bodies with base cavities
Institute of Scientific and Technical Information of China (English)
Shu-Cheng Pan; Jin-Sheng Cai
2012-01-01
Based on our previous research about drag reduction in term of the base cavity length using two dimensional simulations,this paper describes a numerical study of a bluff body of which the number of base cavities is successively increased and the cavity geometries are also modified to assume different shapes.Here we attempt to find an effective configuration to reduce the drag by increasing the number of base cavities.The numerical simulations examining varied number of base cavities reveal the presence of different strength of vortices in the wake zone which is the reason why the drag coefficients are distinctly different for different cases.In the case with double and triple rectangular cavities,we use the pressure contours snapshots at successive time instants to describe the wake evolution.We further investigate the effect of variable base cavity shapes for a constant cavity length at an identical time instant.A total of two different geometries of base cavities are discussed here:the rectangular and the sinusoidal cavities with sharp and rounded trailing edges,respectively.The numerical results reveal that the former is an effective drag reduction configuration which can produce a significant base pressure recovery corresponding to the strength of the vortices shown in the pressure contour figures.While the latter shows no obvious reduction in drag coefficient and a similar intensity of vortex in the wake zone compared with the unmodified case.Reductions in drag are observed for all the investigated cavity configurations,and additionally it is found that the magnitude of the reduction bears a direct relationship with the number of the cavities up to a certain minimum value.
Traffic Flow Analysis Based Flow Control Mechanism for next Generation Network
Directory of Open Access Journals (Sweden)
D. Karunkuzhali
2013-01-01
Full Text Available Wireless communication is also one of the fastest growing technologies all over the world in the digital and multimedia communication. The cellular communication which is a part of wireless communication following infra-structure based networking. The cellular network has introduced the packet switching in addition to circuit switching in the Second Generation (2 G and it extends the features such as MMS in the 2.5 G, Video Conferencing in 3 G and IP networking in the 4 G. It is in progress to extend its capability through the 5G. Now, 5 G in cellular communication become more important and expected networking technologies. This fifth generation and above, is termed Next Generation Network (NGN. The NGN will offer heterogeneous connectivity on IP based broadband cellular communication. The NGN will leads to flexibility in the handling, mobility, reduced installation time, comparatively lower initial cost and nil maintenance cost on the user perception.
Morais, Inês P. A.; Miró, Manuel; Manera, Matias; Estela, José Manuel; Cerdà, Víctor; Souto, M. Renata S.; Rangel, António O S S
2004-01-01
In this work, a novel flow-through solid-phase based chemiluminescence (CL) optical sensor is described for the trace determination of orthophosphate in waters exploiting the multisyringe flow injection analysis (MSFIA) concept with multicommutation. The proposed time-based injection flow system relies upon the in-line derivatisation of the analyte with ammonium molybdate in the presence of vanadate, and the transient immobilisation of the resulting heteropolyacid in a N-vinylpyrroli...
International Nuclear Information System (INIS)
Internal and external flows are characterized by friction factors and drag coefficients, respectively. Their definitions are based on pressure drop and drag force and thus are very different in character. From a thermodynamics point of view in both cases dissipation occurs which can uniformly be related to the entropy generation in the flow field. Therefore we suggest to account for losses in the flow field by friction factors and drag coefficients that are based on the overall entropy generation due to the dissipation in the internal and external flow fields. This second law analysis (SLA) has been applied to internal flows in many studies already. Examples of this flow category are given together with new cases of external flows, also treated by the general SLA-approach. (paper)
Institute of Scientific and Technical Information of China (English)
Gao Zhong-Ke; Hu Li-Dan; Jin Ning-De
2013-01-01
We generate a directed weighted complex network by a method based on Markov transition probability to represent an experimental two-phase flow.We first systematically carry out gas-liquid two-phase flow experiments for measuring the time series of flow signals.Then we construct directed weighted complex networks from various time series in terms of a network generation method based on Markov transition probability.We find that the generated network inherits the main features of the time series in the network structure.In particular,the networks from time series with different dynamics exhibit distinct topological properties.Finally,we construct two-phase flow directed weighted networks from experimental signals and associate the dynamic behavior of gas-liquid two-phase flow with the topological statistics of the generated networks.The results suggest that the topological statistics of two-phase flow networks allow quantitative characterization of the dynamic flow behavior in the transitions among different gas-liquid flow patterns.
Research on traffic flow forecasting model based on cusp catastrophe theory
Institute of Scientific and Technical Information of China (English)
张亚平; 裴玉龙
2004-01-01
This paper intends to describe the relationship between traffic parameters by using cusp catastrophe theory and to deduce highway capacity and corresponding speed forecasting value through suitable transformation of catastrophe model. The five properties of a catastrophe system are outlined briefly, and then the data collected on freeways of Zhujiang River Delta, Guangdong province, China are examined to ascertain whether they exhibit qualitative properties and attributes of the catastrophe model. The forecasting value of speed and capacity for freeway segments are given based on the catastrophe model. Furthermore, speed-flow curve on freeway is drawn by plotting out congested and uncongested traffic flow and the capacity value for the same freeway segment is also obtained from speed-flow curve to test the feasibility of the application of cusp catastrophe theory in traffic flow analysis. The calculating results of catastrophe model coincide with those of traditional traffic flow models regressed from field observed data, which indicates that the deficiency of traditional analysis of relationship between speed, flow and occupancy in two-dimension can be compensated by analysis of the relationship among speed, flow and occupancy based on catastrophe model in three-dimension. Finally, the prospects and problems of its application in traffic flow research in China are discussed.
International Nuclear Information System (INIS)
We generate a directed weighted complex network by a method based on Markov transition probability to represent an experimental two-phase flow. We first systematically carry out gas—liquid two-phase flow experiments for measuring the time series of flow signals. Then we construct directed weighted complex networks from various time series in terms of a network generation method based on Markov transition probability. We find that the generated network inherits the main features of the time series in the network structure. In particular, the networks from time series with different dynamics exhibit distinct topological properties. Finally, we construct two-phase flow directed weighted networks from experimental signals and associate the dynamic behavior of gas-liquid two-phase flow with the topological statistics of the generated networks. The results suggest that the topological statistics of two-phase flow networks allow quantitative characterization of the dynamic flow behavior in the transitions among different gas—liquid flow patterns. (general)
Flow pattern based correlations of two-phase pressure drop in rectangular microchannels
Energy Technology Data Exchange (ETDEWEB)
Choi, Chiwoong, E-mail: chiwoongchoi@gmail.com [Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, San 31, Hyoja Dong 790-784 (Korea, Republic of); Kim, Moohwan [Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang, San 31, Hyoja Dong 790-784 (Korea, Republic of)
2011-12-15
Highlights: Black-Right-Pointing-Pointer Glass microchannels with embedded pressure ports were fabricated to obtain accurate measurements. Black-Right-Pointing-Pointer The assessments of seven HFM (Homogeneous Flow Model) and ten SFM (Separated Flow Model) were conducted. Black-Right-Pointing-Pointer The results indicate models shows best estimations. Black-Right-Pointing-Pointer In addition, the pressure drop is well agreed with flow pattern tendency. Black-Right-Pointing-Pointer Based on two-phase flow patterns, new correlations were proposed for both homogeneous and separated flow types. - Abstract: Numerous pressure drop correlations for microchannels have been proposed; most of them can be classified as either a homogeneous flow model (HFM) or a separated flow model (SFM). However, the predictions of these correlations have not been compared directly because they were developed in experiments conducted under a range of conditions, including channel shape, the number of channels, channel material and the working fluid. In this study, single rectangular microchannels with different aspect ratios and hydraulic diameters were fabricated in a photosensitive glass. Adiabatic water-liquid and Nitrogen-gas two-phase flow experiments were conducted using liquid superficial velocities of 0.06-1.0 m/s, gas superficial velocities of 0.06-72 m/s and hydraulic diameters of 141, 143, 304, 322 and 490 {mu}m. A pressure drop in microchannels was directly measured through embedded ports. The flow pattern was visualized using a high-speed camera and a long-distance microscope. A two-phase pressure drop in the microchannel was highly related to the flow pattern. Data were used to assess seven different HFM viscosity models and ten SFM correlations, and new correlations based on flow patterns were proposed for both HFMs and SFMs.
Flow pattern based correlations of two-phase pressure drop in rectangular microchannels
International Nuclear Information System (INIS)
Highlights: ► Glass microchannels with embedded pressure ports were fabricated to obtain accurate measurements. ► The assessments of seven HFM (Homogeneous Flow Model) and ten SFM (Separated Flow Model) were conducted. ► The results indicate models shows best estimations. ► In addition, the pressure drop is well agreed with flow pattern tendency. ► Based on two-phase flow patterns, new correlations were proposed for both homogeneous and separated flow types. - Abstract: Numerous pressure drop correlations for microchannels have been proposed; most of them can be classified as either a homogeneous flow model (HFM) or a separated flow model (SFM). However, the predictions of these correlations have not been compared directly because they were developed in experiments conducted under a range of conditions, including channel shape, the number of channels, channel material and the working fluid. In this study, single rectangular microchannels with different aspect ratios and hydraulic diameters were fabricated in a photosensitive glass. Adiabatic water-liquid and Nitrogen-gas two-phase flow experiments were conducted using liquid superficial velocities of 0.06–1.0 m/s, gas superficial velocities of 0.06–72 m/s and hydraulic diameters of 141, 143, 304, 322 and 490 μm. A pressure drop in microchannels was directly measured through embedded ports. The flow pattern was visualized using a high-speed camera and a long-distance microscope. A two-phase pressure drop in the microchannel was highly related to the flow pattern. Data were used to assess seven different HFM viscosity models and ten SFM correlations, and new correlations based on flow patterns were proposed for both HFMs and SFMs.
Research on the Prediction of VNN Neural Network Traffic Flow Model Based on Chaotic Algorithm
Directory of Open Access Journals (Sweden)
Yin Lisheng
2013-06-01
Full Text Available This paperresearches on the prediction of traffic flow chaotic time series based on VNNTF neural network. First, the traffic flow time series chaotic feature is extracted by chaos theory. Pretreatment for traffic flow time series and the VNNTP neural networks model was build by this. Second, principles of neural network learning algorithm VNNTF is described. Based on chaotic learning algorithm, the neural network traffic Volterra learning algorithm isdesigned for fast learning algorithm. Last, a single-step prediction of traffic flow chaotic time series is researched by VNNTF network model based on chaotic algorithm. The results showed that the VNNTF network model predictive performance is better than the Volterra prediction filter and the BP neural network by the simulation results and root-mean-square value.
Characterization of a silicon nanowire-based cantilever air-flow sensor
International Nuclear Information System (INIS)
Silicon nanowire (SiNW)-based cantilever flow sensors with three different cantilever sizes (10 × 50, 20 × 90 and 40 × 100 µm2) and various SiNW lengths (2, 5 and 10 µm) have been designed for air velocity sensing. The total device thickness is around 3 µm, which consists of the bottom SiO2 layer (0.5 µm) and the top SiNx layer (2.5 µm). In addition, the SiNx layer is used to compensate the initial stress and also enhance the device immunity to air-flow-induced vibrations significantly. To experience the maximum strain induced by the air flow, SiNWs are embedded at the clamp point where the cantilever is anchored to the substrate. Taking advantage of the superior properties of SiNWs, the reported flow sensor shows outstanding air-flow-sensing capability in terms of sensitivity, linearity and hysteresis. With only a supply voltage of 0.1 V and the high initial resistance of the piezoresistive SiNWs, significant energy saving is reached in contrast to the thermal-based flow sensors as well as other recently reported piezoresistive designs. Last but not least, the significant size reduction of our device demonstrates the great scalability of SiNW-based flow sensors. (paper)
Design of Experience and Flow in Movement-based Interaction
Nijholt, Anton; Dijk, van Betsy; Reidsma, Dennis; Egges, A.; Kamphuis, A.; Overmars, M.
2008-01-01
Movement-based and exertion interfaces assume that their users move. Users have to perform exercises, they have to dance, they have to golf or football, or they want to train particular bodily skills. Many examples of those interfaces exist, sometimes asking for subtle interaction between user and i
Observations on Experience and Flow in Movement-Based Interaction
Nijholt, Anton; Pasch, Marco; Dijk, van Betsy; Reidsma, Dennis; Heylen, Dirk; England, David
2011-01-01
Movement-based interfaces assume that their users move. Users have to perform exercises, they have to dance, they have to golf or football, or they want to train particular bodily skills. Many examples of those interfaces exist, sometimes asking for subtle interaction between user and interface and
New Multiphase Matrix Converter Based Device for Power Flow Control
Jerzy Szczepanik; Tomasz Sieńko
2013-01-01
The article presents the concept of new matrix converter (MC) based device working as a phase shifting control device in a power system. The multiphase MC is working under an innovative control algorithm specially dedicated to the proposed application. The work presents the results of the simulation of the MC work in this application as well as the analysis of the MC properties.
LES based POD analysis of Jet in Cross Flow
DEFF Research Database (Denmark)
Cavar, Dalibor; Meyer, Knud Erik; Jakirlic, S.;
2010-01-01
The paper presents results of a POD investigation of the LES based numerical simulation of the jet-in-crossflow (JICF) flowfield. LES results are firstly compared to the pointwise LDA measurements. 2D POD analysis is then used as a comparison basis for PIV measurements and LES, and finally 3D POD...
Numerical simulation of multi-dimensional two-phase flow based on flux vector splitting
Energy Technology Data Exchange (ETDEWEB)
Staedtke, H.; Franchello, G.; Worth, B. [Joint Research Centre - Ispra Establishment (Italy)
1995-09-01
This paper describes a new approach to the numerical simulation of transient, multidimensional two-phase flow. The development is based on a fully hyperbolic two-fluid model of two-phase flow using separated conservation equations for the two phases. Features of the new model include the existence of real eigenvalues, and a complete set of independent eigenvectors which can be expressed algebraically in terms of the major dependent flow parameters. This facilitates the application of numerical techniques specifically developed for high speed single-phase gas flows which combine signal propagation along characteristic lines with the conservation property with respect to mass, momentum and energy. Advantages of the new model for the numerical simulation of one- and two- dimensional two-phase flow are discussed.
Lagrangian filtered density function for LES-based stochastic modelling of turbulent dispersed flows
Innocenti, A; Chibbaro, S
2016-01-01
The Eulerian-Lagrangian approach based on Large-Eddy Simulation (LES) is one of the most promising and viable numerical tools to study turbulent dispersed flows when the computational cost of Direct Numerical Simulation (DNS) becomes too expensive. The applicability of this approach is however limited if the effects of the Sub-Grid Scales (SGS) of the flow on particle dynamics are neglected. In this paper, we propose to take these effects into account by means of a Lagrangian stochastic SGS model for the equations of particle motion. The model extends to particle-laden flows the velocity-filtered density function method originally developed for reactive flows. The underlying filtered density function is simulated through a Lagrangian Monte Carlo procedure that solves for a set of Stochastic Differential Equations (SDEs) along individual particle trajectories. The resulting model is tested for the reference case of turbulent channel flow, using a hybrid algorithm in which the fluid velocity field is provided b...
Xing, Fangyuan; Wang, Honghuan; Yin, Hongxi; Li, Ming; Luo, Shenzi; Wu, Chenguang
2016-02-01
With the extensive application of cloud computing and data centres, as well as the constantly emerging services, the big data with the burst characteristic has brought huge challenges to optical networks. Consequently, the software defined optical network (SDON) that combines optical networks with software defined network (SDN), has attracted much attention. In this paper, an OpenFlow-enabled optical node employed in optical cross-connect (OXC) and reconfigurable optical add/drop multiplexer (ROADM), is proposed. An open source OpenFlow controller is extended on routing strategies. In addition, the experiment platform based on OpenFlow protocol for software defined optical network, is designed. The feasibility and availability of the OpenFlow-enabled optical nodes and the extended OpenFlow controller are validated by the connectivity test, protection switching and load balancing experiments in this test platform.
Energy Technology Data Exchange (ETDEWEB)
Na, Young Su; Lee, Joon Sik [Seoul National Univ., Seoul (Korea, Republic of); Kim, Kenneth D. [University of Tennessee, Knoxville (United States)
2009-07-01
This study compares the effective thermal diffusivities of water-based Alumina nanofluid under convective flow condition with those under static condition. In general, the thermal diffusivity is defined by the thermal conductivity and heat capacity under static condition. In this study, the thermal diffusivities under fully developed laminar flow in a circular tube were calculated by measuring temperatures without using the thermal properties. In contrast with the strong temperature dependence on the effective thermal diffusivities under static condition, those under convective flow condition increased with decreasing mean fluid temperature induced by increasing volume flow rate at constant heat flux. This opposite trend of the temperature dependence on the effective thermal diffusivities under convective flow condition was explained by particle migration due to stronger thermophoresis diffusivity than Brownian diffusivity.
New Multiphase Matrix Converter Based Device for Power Flow Control
Directory of Open Access Journals (Sweden)
Jerzy Szczepanik
2013-12-01
Full Text Available The article presents the concept of new matrix converter (MC based device working as a phase shifting control device in a power system. The multiphase MC is working under an innovative control algorithm specially dedicated to the proposed application. The work presents the results of the simulation of the MC work in this application as well as the analysis of the MC properties.
Jepsen, S. M.; Harmon, T. C.; Shi, Y.
2016-04-01
Calibration of watershed models to the shape of the base flow recession curve is a way to capture the important relationship between groundwater discharge and subsurface water storage in a catchment. In some montane Mediterranean regions, such as the midelevation Providence Creek catchment in the southern Sierra Nevada of California (USA), nearly all base flow recession occurs after snowmelt, and during this time evapotranspiration (ET) usually exceeds base flow. We assess the accuracy to which watershed models can be calibrated to ET-dominated base flow recession in Providence Creek, both in terms of fitting a discharge time-series and realistically capturing the observed discharge-storage relationship for the catchment. Model parameters estimated from calibrations to ET-dominated recession are compared to parameters estimated from reference calibrations to base flow recession with ET-effects removed ("potential recession"). We employ the Penn State Integrated Hydrologic Model (PIHM) for simulations of base flow and ET, and methods that are otherwise general in nature. In models calibrated to ET-dominated recession, simulation errors in ET and the targeted relationship for recession (-dQ/dt versus Q) contribute substantially (up to 57% and 46%, respectively) to overestimates in the discharge-storage differential, defined as d(lnQ)/dS, relative to that derived from water flux observations. These errors result in overestimates of deep-subsurface hydraulic conductivity in models calibrated to ET-dominated recession, by up to an order of magnitude, relative to reference calibrations to potential recession. These results illustrate a potential opportunity for improving model representation of discharge-storage dynamics by calibrating to the shape of base flow recession after removing the complicating effects of ET.
An Optical Flow-Based Full Reference Video Quality Assessment Algorithm.
K, Manasa; Channappayya, Sumohana S
2016-06-01
We present a simple yet effective optical flow-based full-reference video quality assessment (FR-VQA) algorithm for assessing the perceptual quality of natural videos. Our algorithm is based on the premise that local optical flow statistics are affected by distortions and the deviation from pristine flow statistics is proportional to the amount of distortion. We characterize the local flow statistics using the mean, the standard deviation, the coefficient of variation (CV), and the minimum eigenvalue ( λ min ) of the local flow patches. Temporal distortion is estimated as the change in the CV of the distorted flow with respect to the reference flow, and the correlation between λ min of the reference and of the distorted patches. We rely on the robust multi-scale structural similarity index for spatial quality estimation. The computed temporal and spatial distortions, thus, are then pooled using a perceptually motivated heuristic to generate a spatio-temporal quality score. The proposed method is shown to be competitive with the state-of-the-art when evaluated on the LIVE SD database, the EPFL Polimi SD database, and the LIVE Mobile HD database. The distortions considered in these databases include those due to compression, packet-loss, wireless channel errors, and rate-adaptation. Our algorithm is flexible enough to allow for any robust FR spatial distortion metric for spatial distortion estimation. In addition, the proposed method is not only parameter-free but also independent of the choice of the optical flow algorithm. Finally, we show that the replacement of the optical flow vectors in our proposed method with the much coarser block motion vectors also results in an acceptable FR-VQA algorithm. Our algorithm is called the flow similarity index. PMID:27093720
Directory of Open Access Journals (Sweden)
Shan Yang
2016-01-01
Full Text Available Power flow calculation and short circuit calculation are the basis of theoretical research for distribution network with inverter based distributed generation. The similarity of equivalent model for inverter based distributed generation during normal and fault conditions of distribution network and the differences between power flow and short circuit calculation are analyzed in this paper. Then an integrated power flow and short circuit calculation method for distribution network with inverter based distributed generation is proposed. The proposed method let the inverter based distributed generation be equivalent to Iθ bus, which makes it suitable to calculate the power flow of distribution network with a current limited inverter based distributed generation. And the low voltage ride through capability of inverter based distributed generation can be considered as well in this paper. Finally, some tests of power flow and short circuit current calculation are performed on a 33-bus distribution network. The calculated results from the proposed method in this paper are contrasted with those by the traditional method and the simulation method, whose results have verified the effectiveness of the integrated method suggested in this paper.
An efficient flow-based botnet detection using supervised machine learning
DEFF Research Database (Denmark)
Stevanovic, Matija; Pedersen, Jens Myrup
2014-01-01
introduces a novel flow-based detection system that relies on supervised machine learning for identifying botnet network traffic. For use in the system we consider eight highly regarded machine learning algorithms, indicating the best performing one. Furthermore, the paper evaluates how much traffic needs to...... be observed per flow in order to capture the patterns of malicious traffic. The proposed system has been tested through the series of experiments using traffic traces originating from two well-known P2P botnets and diverse non-malicious applications. The results of experiments indicate that the...... system is able to accurately and timely detect botnet traffic using purely flow-based traffic analysis and supervised machine learning. Additionally, the results show that in order to achieve accurate detection traffic flows need to be monitored for only a limited time period and number of packets per...
Traffic Flow Analysis Model based Routing Protocol For Multi-Protocol Label Switching Network
Directory of Open Access Journals (Sweden)
E. R. Naganathan
2011-01-01
Full Text Available Problem statement: Multi-Protocol Label Switching (MPLS is a mechanism which is used in high-performance telecommunications networks that directs and carries data from one network node to the next with the help of labels. Traffic management is still an issue in MPLS network as it involves high speed internet. Approach: This study proposed a traffic flow analysis of the real time MPLS traffic and segregates the MPLS traffic as three major class based on the outcome of traffic flow analysis. Using the traffic class. This study proposed a reliable transmission methodology which provides traffic free routing in the MPLS networks. Results: The proposed traffic flow analysis based reliable routing model overcomes the network traffic and provides effective routing by offering traffic free path. Conclusion: The proposed traffic flow analysis model outperforms existing routing protocol and offers comparatively negligible packet loss.
Information flow model based on network security of Nuclear Power Plant
International Nuclear Information System (INIS)
In order to precisely describe the information flow from 1E degree to non 1E degree subsets of the network in the Nuclear Power Plant network, a new security information flow mathematics model based on this network is given in this paper. This model incorporated the new concept of the planar-classification function, which combined the classification of the sub-network and the classification of object. Safety classification of the objects was divided based on the function values and the information flow policy is described with the function values of two objects. Strict mathematic verification showed that this information flow model is reasonable and safe, which can reflect the safety requirements of the Nuclear Power Plant network. (author)
Institute of Scientific and Technical Information of China (English)
FAN Wei; ZHANG Hongli; WANG Tao; PENG Guangzheng; ONEYAMA Naotake
2009-01-01
Regulators are important components in pneumatic system, and their flow-rate characteristics are the key parameters for designers. According to the correlatively international standard and national standard of China, which describe the flow-rate characteristics measurement method of pneumatic regulators, the pressure and the flow are measured point by point, and then the flow-rate characteristics curve is plotted point to point. This method has some disadvantages, such as equipment complexity, much air consumption, and low efficiency. To settle the problems presented above, this paper puts forward a new high efficient and energy saving flow-rate characteristics measurement method of regulators, which is based on the pressure response when charging and discharging to an isothermal tank without any flow meters. The measurement principle, the system and the steps are introduced. And the tracking differentiator is used for the data processing of the pressure difference. Two typical kinds of regulators were experimentally investigated, and their flow-rate characteristics curves were obtained with the new and the conventional method, respectively. Comparatively, it's proved that this new method is feasible because it is not only able to meet the demand of the measurement precision, but also to save energy and improve efficiency. Compared to the conventional method, the new method takes only about 1/10 amount of time and consumes about only 1/30 amount of air. Hopefully it will be able to serve as an international standard of flow-rate characteristics measurement method of regulators.
On the transition of base flow recession from early stage to late stage
Ghosh, Debapi K.; Wang, Dingbao; Zhu, Tingju
2016-02-01
This paper is focused on the transition of base flow recession from early stage to late stage. The volume flow rate that takes place when such a transition occurs is identified for each of the twenty-three recession events observed at the Panola Mountain Research Watershed (PMRW) in Georgia, USA, using a newly developed cumulative regression analysis method. Meanwhile, the flow at the watershed outlet, which was recorded when the discharge at the perennial stream head diminishes to zero, is identified for each recession event. As evidenced by a correlation coefficient of 0.90, these two characteristic flows are found to be highly correlated, suggesting a fundamental linkage between the transition of base flow recession from early stage to late stage and the drying up of ephemeral streams. During the early stage, the contraction of ephemeral streams largely controls the recession behavior, whereas in the late stage when perennial streams dominate the flowing streams, the contraction of flowing streams is minimal and groundwater hydraulics governs the recession behavior.
An effective depression filling algorithm for DEM-based 2-D surface flow modelling
Directory of Open Access Journals (Sweden)
D. Zhu
2013-02-01
Full Text Available The surface runoff process in fluvial/pluvial flood modelling is often simulated employing a two-dimensional (2-D diffusive wave approximation described by grid based digital elevation models (DEMs. However, this approach may cause potential problems when using the 2-D surface flow model which exchanges flows through adjacent cells, with conventional sink removal algorithms which also allow for flow exchange along diagonal directions, due to the existence of artificial depression in DEMs. In this paper, we propose an effective method for filling artificial depressions in DEM so that the problem can be addressed. We firstly analyse two types of depressions in DEMs and demonstrate the issues caused by the current depression filling algorithms using the surface flow simulations from the MIKE SHE model built for a medium-sized basin in Southeast England. The proposed depression-filling algorithm for 2-D overland flow modelling is applied and evaluated by comparing the simulated flows at the outlet of the catchment represented by DEMs at various resolutions (50 m, 100 m and 200 m. The results suggest that the existence of depressions in DEMs can substantially influence the overland flow estimation and the new depression filling algorithm is shown to be effective in tackling this issue based upon the comparison of simulations for sink-dominated and sink-free DEMs, especially in the areas with relatively flat topography.
The base-line DataFlow system of the ATLAS Trigger and DAQ
Beck, H P; Dos Anjos, A; Barisonzi, M; Beretta, M; Blair, R; Bogaerts, A; Boterenbrood, H; Botterill, David R; Ciobotaru, M; Cortezon, E; Cranfield, R; Crone, G J; Dawson, J; Di Girolamo, B; Dobinson, Robert W; Ermoline, Y; Ferrer, M; Francis, D; Gadomski, S; Gameiro, S; Golonka, P; Gorini, B; Green, B; Gruwé, M; Haas, S; Haeberli, C; Hasegawa, Y; Hauser, R; Hinkelbein, C; Hughes-Jones, R E; Knezo, E; Jansweijer, P; Joos, M; Kaczmarska, A; Kieft, G; Korcyl, K; Kugel, A; Lankford, A; Lehmann, G; Le Vine, M J; Liu, W; Maeno, T; Maia, M; Mapelli, L; Martin, L; McLaren, R; Meirosu, C; Misiejuk, A; Mommsen, R K; Mornacchi, Giuseppe; Müller, M; Nagasaka, Y; Nakayoshi, Y; Papadopoulos, I M; Petersen, J; Pinto, P; Prigent, D; Pérez-Réale, V; Schlereth, J L; Shimojima, M; Spiwoks, R; Stancu, S; Strong, J; Tremblet, L J; Vermeulen, J C; Werner, P; Wickens, F J; Yasu, Y; Yu, M; Zobernig, H; Zurek, M
2004-01-01
The base-line design and implementation of the ATLAS DAQ DataFlow system is described. The main components realizing the DataFlow system, their interactions, bandwidths and rates are being discussed and performance measurements on a 10% scale prototype for the final Atlas TDAQ DataFlow system are presented. This prototype is a combination of custom design components and of multi-threaded software applications implemented in C++ and running in a Linux environment on commercially available PCs interconnected by a fully switched gigabit Ethernet network.
Design criteria of a chemical reactor based on a chaotic flow
Tang, X. Z.; Boozer, A. H.
1998-01-01
We consider the design criteria of a chemical mixing device based on a chaotic flow, with an emphasis on the steady-state devices. The merit of a reactor, defined as the $Q$-factor, is related to the physical dimension of the device and the molecular diffusivity of the reactants through the local Lyapunov exponents of the flow. The local Lyapunov exponent can be calculated for any given flow field and it can also be measured in experimental situations. Easy-to-compute formulae are provided to...
Traffic Flow Prediction Model for Large-Scale Road Network Based on Cloud Computing
Directory of Open Access Journals (Sweden)
Zhaosheng Yang
2014-01-01
Full Text Available To increase the efficiency and precision of large-scale road network traffic flow prediction, a genetic algorithm-support vector machine (GA-SVM model based on cloud computing is proposed in this paper, which is based on the analysis of the characteristics and defects of genetic algorithm and support vector machine. In cloud computing environment, firstly, SVM parameters are optimized by the parallel genetic algorithm, and then this optimized parallel SVM model is used to predict traffic flow. On the basis of the traffic flow data of Haizhu District in Guangzhou City, the proposed model was verified and compared with the serial GA-SVM model and parallel GA-SVM model based on MPI (message passing interface. The results demonstrate that the parallel GA-SVM model based on cloud computing has higher prediction accuracy, shorter running time, and higher speedup.
Influence of Base Oil Polarity on the Transient Shear Flow of Biodegradable Lubricating Greases
Directory of Open Access Journals (Sweden)
Martin Fiedler
2015-09-01
Full Text Available The scope of this study is to elucidate the physical mechanisms influencing the transient flow behavior of lubricating greases based on biogenic oleochemicals from a polarity point of view. This includes the mutually interacting influence of base oil polarity and thickening agents on the rheologically-measured mechanical structural degradation in transient shear flow. Due to the high temperature dependence of Keesom forces in the background of polar-active bond mechanisms, the analysis of the transient flow response as a function of temperature allows to attribute the observed influences to differences in base oil polarity. In general, clay-thickened greases show a greater tendency to be rheologically influenced by base oil polarities than soap-thickened lubricating greases.
Power flow tracing based method for allocation of transmission service cost to transactions
Institute of Scientific and Technical Information of China (English)
李卫东; 刘娆; 魏立明
2004-01-01
Based on the concepts of objective fact and subjeetive desire proposed in this paper, the problens that exist in the nodal injections-based and transaction-based transmission service allocation scheme are pointed out. To get around the problems above, a novel transmission service allocation scheme is proposed which considers the power flow distribution and the transaetion impact on the system simultaneously so that the issues of "Cross-subsidies" and "Counter flow" can be avoided. The principle of the scheme is illustrated using two simple networks with 7 cases. The results show that the proposed scheme can satisfy the properties necessary for the development and growth of the electricity market.
Innovation, demand, and finance in an agent based-stock flow consistent model
Caiani, Alessandro; Caverzas, Eugenio; Godin, Antoine,; Riccetti, Luca; Russo, Alberto; Gallegati, Mauro; Kinsella, Stephen; Stiglitz, Joseph
2014-01-01
We present an agent based stock flow consistent macroeconomic model with heterogeneous agents interacting through a decentralized matching process across multiple markets with multiple assets. The model is consistent across both the micro and macroeconomic levels, by providing a detailed, comprehensive, and rigorous accounting of real and financial flows and stocks. We implement the model using a brand new Java programming platform, explicitly designed for AB-SFC models.
Exponential Smoothing Method of Base Flow Separation and Its Impact on Continuous Loss Estimates
G. A. Tularam; M. Ilahee
2008-01-01
The calculation of loss is vital for design flood estimation models and in order to estimate continuing loss (CL), proportional loss (PL) and volumetric runoff coefficient, the surface runoff has to be separated from the total given in a stream flow hydrograph. To obtain the volume of surface runoff from the streamflow hydrograph, baseflow separation becomes necessary and in this paper a few base flow separation methods are explored and an appropriate method selected to assess to impact of ba...
Modeling Material Flow Behavior during Hot Deformation Based on Metamodeling Methods
Gang Xiao; Qinwen Yang; Luoxing Li; Zhengbing Xu
2015-01-01
Modeling material flow behavior is an essential step to design and optimize the forming process. In this context, four popular metamodel types Kriging, radial basis function, multivariate polynomial, and artificial neural network are investigated as potential methods for modeling the flow behavior of 6013 aluminum alloy. Based on the experimental data from hot compression tests, the modeling performance of these four methods was tested and subsequently compared from different aspects. It is f...
An Iterative Fingerprint Enhancement Algorithm Based on Accurate Determination of Orientation Flow
Dube, Simant
2009-01-01
We describe an algorithm to enhance and binarize a fingerprint image. The algorithm is based on accurate determination of orientation flow of the ridges of the fingerprint image by computing variance of the neighborhood pixels around a pixel in different directions. We show that an iterative algorithm which captures the mutual interdependence of orientation flow computation, enhancement and binarization gives very good results on poor quality images.
Flow Control Strategy for the High Speed Network Based on Control Theory
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Design of an effective congestion control scheme is a hot topic in the development of computer network. The flow control scheme can adjust the packet sending rate in source host, thus effectively avoiding the network congestion. This paper proposes a new flow control scheme based on discrete control theory. The simulation results show that this method can adjust the sending rate and queue level in buffer rapidly and effectively. The method is easy to implement and applicable to high speed networks.
A CASE STUDY IN PROJECT BASED LEARNING USING FLOW VISUALISATION
Directory of Open Access Journals (Sweden)
MUSHTAK AL-ATABI
2007-12-01
Full Text Available Engineering Design modules, usually introduced in the first and second year’s undergraduate Mechanical Engineering courses, present a unique platform to practice the Project Based Learning (PBL. PBL is a widely accepted technique that can be used to achieve two major educational goals; affirming the theoretical principles studied in other modules and developing the professional skill essential for graduates such as team working and effective communication skills. In this paper we describe the use of PBL to enhance the understanding of turbulence, a classical problem in fluid mechanics. The project is carried out in the “Mechanical Engineering Design & Professional Skills” Module, which requires the students to construct the Prandtl recirculating water channel. The skills and knowledge involved not only fluid mechanics, but design, material selections and engineering mechanics, making it a truly multi-disciplinary project.
A Step-by-Step Design Methodology for a Base Case Vanadium Redox-Flow Battery
Moore, Mark; Counce, Robert M.; Watson, Jack S.; Zawodzinski, Thomas A.; Kamath, Haresh
2012-01-01
The purpose of this work is to develop an evolutionary procedure to be used by Chemical Engineering students for the base-case design of a Vanadium Redox-Flow Battery. The design methodology is based on the work of Douglas (1985) and provides a profitability analysis at each decision level so that more profitable alternatives and directions can be…
The Curriculum System Development of Sightseeing Agriculture Major Based on Work Flow
Chen, Sujuan; Chen, Guoyuan; Wang, Chengzhong
2014-01-01
From the position setting of sightseeing agriculture businesses and ability analysis, this paper analyzes the career action field based on training objectives of sightseeing agriculture major and determines the typical tasks and career action field. According to the major teaching design of career action field, this paper introduces the systematic curriculum system of sightseeing agriculture major based on work flow.
The Curriculum System Development of Sightseeing Agriculture Major Based on Work Flow
Institute of Scientific and Technical Information of China (English)
Sujuan; CHEN; Guoyuan; CHEN; Chengzhong; WANG
2014-01-01
From the position setting of sightseeing agriculture businesses and ability analysis,this paper analyzes the career action field based on training objectives of sightseeing agriculture major and determines the typical tasks and career action field. According to the major teaching design of career action field,this paper introduces the systematic curriculum system of sightseeing agriculture major based on work flow.
Study of an ammonia-based wet scrubbing process in a continuous flow system
Energy Technology Data Exchange (ETDEWEB)
Mao, James X.; Lee, Anita S.; Kitchin, John R.; Nulwala, Hunaid B.; Luebke, David R.; Damodaran, Krishnan
2013-01-01
A continuous gas and liquid flow, regenerative scrubbing process for CO{sub 2} capture was demonstrated at the bench-scale level. An aqueous ammonia-based solution captures CO{sub 2} from simulated flue gas in an absorber and releases a nearly pure stream of CO{sub 2} in the regenerator. After the regeneration, the solution of ammonium compounds is recycled to the absorber. The design of a continuous flow unit was based on earlier exploratory results from a semi-batch reactor, where a CO{sub 2} and N{sub 2} simulated flue gas mixture flowed through a well-mixed batch of ammonia-based solution. During the semi-batch tests, the solution was cycled between absorption and regeneration steps to measure the carrying capacity of the solution at various initial ammonia concentrations and temperatures. Consequentially, a series of tests were conducted on the continuous unit to observe the effect of various parameters on CO{sub 2} removal efficiency and regenerator effectiveness within the flow system. The parameters that were studied included absorber temperature, regenerator temperature, initial NH{sub 3} concentration, simulated flue gas flow rate, liquid solvent inventory in the flow system, and height of the packed-bed absorber. From this testing and subsequent testing, ammonia losses from both the absorption and regeneration steps were quantified, and attempts were made to maintain steady state during operations. Implications of experimental results with respect to process design are discussed.
Alonso González, Carlos; Gortazar y Landecho, Javier; Baeza Sanz, Domingo; García de Jalón Lastra, Diego
2008-01-01
The operation of small hydroelectric dams built on mountain streams induce changes in stream flow regimes that are manifested not only in the intensity of flow events, but also in the variability and frequency of high- and low-flow episodes. Former studies have shown the influence of flow variability upon the dynamics of a resident brown trout population, especially that related to the stream flow regime during spawning, incubation and emerging periods. As these life-stages are known to deter...
Kashchenko, O.
2010-01-01
The article is devoted topical questions of organization of accounting and internal check cash flow and payment on base business of automobile maintenance servicing. Defined the problem of accounting and control cash flows are formulated proposals to address them.
International Nuclear Information System (INIS)
The internal flow evolution of the pump was induced with impeller movement. In various conditions, the peak load on centrifugal blade under the change of rotational speed or flow rate was also changed. It would cause an error when inertia load with a safety coefficient (that was difficult to ascertain) was applied in structure design. In order to accurately analyze the impeller stress under various conditions and improve the reliability of pump, based on a mixed flow pump model, the stress distribution characteristic was analyzed under different flow rates and rotational speeds. Based on a three-dimensional calculation model including impeller, guide blade, inlet and outlet, the three-dimension incompressible turbulence flow in the centrifugal pump was simulated by using the standard k-epsilon turbulence model. Based on the sequentially coupled simulation approach, a three-dimensional finite element model of impeller was established, and the fluid-structure interaction method of the blade load transfer was discussed. The blades pressure from flow simulation, together with inertia force acting on the blade, was used as the blade loading on solid surface. The Finite Element Method (FEM) was used to calculate the stress distribution of the blade respectively under inertia load, or fluid load, or combined load. The results showed that the blade stress changed with flow rate and rotational speed. In all cases, the maximum stress on the blade appeared on the pressure side near the hub, and the maximum static stress increased with the decreasing of the flow rate and the increasing of rotational speed. There was a big difference on the static stress when inertia load, fluid load and combined loads was applied respectively. In order to more accurately calculate the stress distribution, the structure analysis should be conducted due to combined loads. The results could provide basis for the stress analysis and structure optimization of pump
Hu, F. F.; Chen, T.; Wu, D. Z.; Wang, L. Q.
2013-12-01
The internal flow evolution of the pump was induced with impeller movement. In various conditions, the peak load on centrifugal blade under the change of rotational speed or flow rate was also changed. It would cause an error when inertia load with a safety coefficient (that was difficult to ascertain) was applied in structure design. In order to accurately analyze the impeller stress under various conditions and improve the reliability of pump, based on a mixed flow pump model, the stress distribution characteristic was analyzed under different flow rates and rotational speeds. Based on a three-dimensional calculation model including impeller, guide blade, inlet and outlet, the three-dimension incompressible turbulence flow in the centrifugal pump was simulated by using the standard k-epsilon turbulence model. Based on the sequentially coupled simulation approach, a three-dimensional finite element model of impeller was established, and the fluid-structure interaction method of the blade load transfer was discussed. The blades pressure from flow simulation, together with inertia force acting on the blade, was used as the blade loading on solid surface. The Finite Element Method (FEM) was used to calculate the stress distribution of the blade respectively under inertia load, or fluid load, or combined load. The results showed that the blade stress changed with flow rate and rotational speed. In all cases, the maximum stress on the blade appeared on the pressure side near the hub, and the maximum static stress increased with the decreasing of the flow rate and the increasing of rotational speed. There was a big difference on the static stress when inertia load, fluid load and combined loads was applied respectively. In order to more accurately calculate the stress distribution, the structure analysis should be conducted due to combined loads. The results could provide basis for the stress analysis and structure optimization of pump.
Brownlee, C.
2011-11-01
Understanding fluid flow is a difficult problem and of increasing importance as computational fluid dynamics (CFD) produces an abundance of simulation data. Experimental flow analysis has employed techniques such as shadowgraph, interferometry, and schlieren imaging for centuries, which allow empirical observation of inhomogeneous flows. Shadowgraphs provide an intuitive way of looking at small changes in flow dynamics through caustic effects while schlieren cutoffs introduce an intensity gradation for observing large scale directional changes in the flow. Interferometry tracks changes in phase-shift resulting in bands appearing. The combination of these shading effects provides an informative global analysis of overall fluid flow. Computational solutions for these methods have proven too complex until recently due to the fundamental physical interaction of light refracting through the flow field. In this paper, we introduce a novel method to simulate the refraction of light to generate synthetic shadowgraph, schlieren and interferometry images of time-varying scalar fields derived from computational fluid dynamics data. Our method computes physically accurate schlieren and shadowgraph images at interactive rates by utilizing a combination of GPGPU programming, acceleration methods, and data-dependent probabilistic schlieren cutoffs. Applications of our method to multifield data and custom application-dependent color filter creation are explored. Results comparing this method to previous schlieren approximations are finally presented. © 2011 IEEE.
System-Level Modeling and Synthesis of Flow-Based Microfluidic Biochips
DEFF Research Database (Denmark)
Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan
Microfluidic biochips are replacing the conventional biochemical analyzers and are able to integrate the necessary functions for biochemical analysis on-chip. There are several types of microfluidic biochips, each having its advantages and limitations. In this paper we are interested in flow......-based biochips, in which the flow of liquid is manipulated using integrated microvalves. By combining several microvalves, more complex units, such as micropumps, switches, mixers, and multiplexers, can be built. Although researchers have proposed significant work on the system-level synthesis of droplet......-based biochips, which manipulate droplets on a two-dimensional array of electrodes, no research on system-level synthesis of flow-based biochips has been reported so far. The focus has been on application modeling and component-level simulation. Therefore, for the first time to our knowledge, we propose a system...
A Novel Mobile Personalized Recommended Method Based on Money Flow Model for Stock Exchange
Directory of Open Access Journals (Sweden)
Qingzhen Xu
2014-01-01
Full Text Available Personalized recommended method is widely used to recommend commodities for target customers in e-commerce sector. The core idea of merchandise personalized recommendation can be applied to financial field, which can also achieve stock personalized recommendation. This paper proposes a new recommended method using collaborative filtering based on user fuzzy clustering and predicts the trend of those stocks based on money flow. We use M/G/1 queue system with multiple vacations and server close-down time to measure practical money flow. Based on the indicated results of money flow, we can select the more valued stock to recommend to investors. The experimental results show that the proposed method provides investors with reliable practical investment guidance and receiving more returns.
Architectural Synthesis of Flow-Based Microfluidic Large-Scale Integration Biochips
DEFF Research Database (Denmark)
Minhass, Wajid Hassan; Pop, Paul; Madsen, Jan;
2012-01-01
Microfluidic biochips are replacing the conventional biochemical analyzers and are able to integrate the necessary functions for biochemical analysis on-chip. In this paper we are interested in flow-based biochips, in which the flow of liquid is manipulated using integrated microvalves. By......,we propose a top-down architectural synthesis methodology for the flow-based biochips. Starting from a given biochemical application and a microfluidic component library, we are interested in synthesizing a biochip architecture, i.e., performing component allocation from the library based on the biochemical...... application, generating the biochip schematic (netlist) and then performing physical synthesis (deciding the placement of the microfluidic components on the chip and performing routing of the microfluidic channels), such that the application completion time is minimized. We evaluate our proposed approach by...
Component-cost and performance based comparison of flow and static batteries
Hopkins, Brandon J.; Smith, Kyle C.; Slocum, Alexander H.; Chiang, Yet-Ming
2015-10-01
Flow batteries are a promising grid-storage technology that is scalable, inherently flexible in power/energy ratio, and potentially low cost in comparison to conventional or "static" battery architectures. Recent advances in flow chemistries are enabling significantly higher energy density flow electrodes. When the same battery chemistry can arguably be used in either a flow or static electrode design, the relative merits of either design choice become of interest. Here, we analyze the costs of the electrochemically active stack for both architectures under the constraint of constant energy efficiency and charge and discharge rates, using as case studies the aqueous vanadium-redox chemistry, widely used in conventional flow batteries, and aqueous lithium-iron-phosphate (LFP)/lithium-titanium-phosphate (LTP) suspensions, an example of a higher energy density suspension-based electrode. It is found that although flow batteries always have a cost advantage (kWh-1) at the stack level modeled, the advantage is a strong function of flow electrode energy density. For the LFP/LTP case, the cost advantages decreases from ∼50% to ∼10% over experimentally reasonable ranges of suspension loading. Such results are important input for design choices when both battery architectures are viable options.
Estimation of reservoir and remaining oil prediction based on flow unit analysis
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Through natural partition and clustering analysis,four kinds of flow units were distinguished in Pu53 block,Pucheng Oilfield. Taking the short-term cycle as studying unit,the two-dimensional distribution of each type of flow units was forecasted and the short-term cycle was classified into four types based on the two-dimensional characteristics of the flow units. The remaining oil was predicted by conceptual simulation,qualitative analysis and quantitative modeling. The results showed obvious control of the characteristics of reservoir flow units to the remaining oil. E and G units in type I and type II short-term cycles which are distributed continuously in large areas are mostly flooded,while the uncontrolled small isolated G flow unit in type III short-term cycles which were mainly made of F flow unit and F flow unit with continuous distribution become the accumulating place for remaining oil. Thus the development adjustment strategy should optimize the development of small-scale E and G units,strengthen the development of type III short-term cycles,and block out type I short-term cycles. This strategy improves the development of Pu53 block obviously.
Institute of Scientific and Technical Information of China (English)
LIU Jing-Quan; YOSHIKAWA Hidekazu; ZHOU Yang-Ping
2005-01-01
Complex energy and environment system, especially nuclear fuel cycle system recently raised social concerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only under the condition that those conflicting issues are gotten a consensus between stakeholders with different knowledge background, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has been developed to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle system based on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theory of human being. Its character is that MFM models define a set of mass, energy and information flow structures on multiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representation and the means-end and part-whole hierarchical flow structure to make the represented process easy to be understood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system were selected to be simulated and some analysis processes such as economics analysis, environmental analysis and energy balance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finally the simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycle and its levelised cost analysis will be represented as feasible examples.
International Nuclear Information System (INIS)
Complex energy and environment system, especially nuclear fuel cycle system recently raised social concerns about the issues of economic competitiveness, environmental effect and nuclear proliferation. Only under the condition that those conflicting issues are gotten a consensus between stakeholders with different knowledge background, can nuclear power industry be continuingly developed. In this paper, a new analysis platform has been developed to help stakeholders to recognize and analyze various socio-technical issues in the nuclear fuel cycle sys- tem based on the functional modeling method named Multilevel Flow Models (MFM) according to the cognition theory of human being, Its character is that MFM models define a set of mass, energy and information flow structures on multiple levels of abstraction to describe the functional structure of a process system and its graphical symbol representation and the means-end and part-whole hierarchical flow structure to make the represented process easy to be understood. Based upon this methodology, a micro-process and a macro-process of nuclear fuel cycle system were selected to be simulated and some analysis processes such as economics analysis, environmental analysis and energy balance analysis related to those flows were also integrated to help stakeholders to understand the process of decision-making with the introduction of some new functions for the improved Multilevel Flow Models Studio, and finally the simple simulation such as spent fuel management process simulation and money flow of nuclear fuel cycle and its levelised cost analysis will be represented as feasible examples. (authors)
International Nuclear Information System (INIS)
Recently numerous studies have applied complex network based models to study the performance and vulnerability of infrastructure systems under various types of attacks and hazards. But how effective are these models to capture their real performance response is still a question worthy of research. Taking the Chinese railway system as an example, this paper selects three typical complex network based models, including purely topological model (PTM), purely shortest path model (PSPM), and weight (link length) based shortest path model (WBSPM), to analyze railway accessibility and flow-based vulnerability and compare their results with those from the real train flow model (RTFM). The results show that the WBSPM can produce the train routines with 83% stations and 77% railway links identical to the real routines and can approach the RTFM the best for railway vulnerability under both single and multiple component failures. The correlation coefficient for accessibility vulnerability from WBSPM and RTFM under single station failures is 0.96 while it is 0.92 for flow-based vulnerability; under multiple station failures, where each station has the same failure probability fp, the WBSPM can produce almost identical vulnerability results with those from the RTFM under almost all failures scenarios when fp is larger than 0.62 for accessibility vulnerability and 0.86 for flow-based vulnerability
Seo, Hyeon-Seok; Boo, Jin-Hyo; Kim, Youn-Jea
2015-10-01
This study numerically investigated the flow characteristics in a rectangular enclosure filled with oil-based ferrofluid (EFH-1, Ferrotec.) under the influence of external magnetic fields. The rectangular enclosure contained obstacles with different shapes, such as a rectangle and a triangle mounted on the top and bottom wall surfaces. In order to generate external magnetic fields, a permanent magnet was located in the lower part of the rectangular enclosure, and its direction was selected to be either horizontal or vertical. Our results showed that the ferrofluid flow fields were affected by the applied external magnetic field direction and eddy flow phenomena in the working fluid were generated in the vicinity of high magnetic flux density distributions, such as at the edge of the permanent magnet. It was also confirmed that the magnetophoretic force distributions in the analysis model played a significant role in the development of the ferrofluid flow fields. PMID:26726349
The Research of Traffic Flow Assignment Model based on the Network Calculus of Computer Network
Directory of Open Access Journals (Sweden)
Jiayao Liu
2012-01-01
Full Text Available The existing dynamic traffic assignment researches mostly based on ideal hypothesis conditions which can analyze the affection of all kinds of traffic parameters on traffic flow and find out characteristics of various types of traffic distribution, but there is rarely have accurate calculation of flow distribution model. The study will first apply the network equilibrium theory into dynamic traffic flow assignment. Using Leaky Bucket Controller and Network Calculus, complicated traffic elements will incorporate into unified mathematical model called T-S Constrained Model, we can deduce flow assignment rate which is in a delay-limited constraints. The simulation results manifest that the model can not only solves congestion, but also reduce average delay of every path, it can extremely improve the traffic capacity of road network. The accurate assignment solutions will have significant impact on traffic engineering implementation.
Rail Transit Normality Passenger Flow Forecasting ModelBased on PSO-SMO
Institute of Scientific and Technical Information of China (English)
SongsongPang; Jianchu Kang; Yan Zhang
2012-01-01
With the increasing problems occurred frequently in traffic jams and accidents, increasing attention has been paid for the forecast for the rail transit passenger flow. Meanwhile, the ability to correctly predict the normality transit passenger flow plays a vital role for the analysis of large-scale events, weather and other unusual factors' impacts on passengers. In this paper, based on PSO-SMO (Particle Swarm Optimization-Sequential Minimal Optimization), a rail transit normality passenger flow forecasting model can be presented as follows. Firstly, a specific model can be built in use of the SMO algorithm. And then, combination of the model built above, the method of PSO-CV (Cross Validation) is introduced to optimize parameters. Finally, the model with optimal parameters extracts the training sample characteristics and the prediction passenger flow can be output. The results show that more than 80% of the data points' prediction relative error are less than 10%, certificating the validity of the model.
International Nuclear Information System (INIS)
The structural investigation of reactor materials are usually by calculations determining the working conditions of particulars elements of fuel assemblies or the hole reactor core. For this analysis the mathematical model of heat flow phenomena was proposed which enable the calculations of temperature field within the assembly. The differential equations for mass, energy and momentum of cooling medium conservation in coaxial and transversal flow direction enable the steady state and transient analysis for the cases of change in heat flow in cooling medium velocity and the pressure in the assembly. The introduced empire correlation which are completing the set of equations make possible the analysis for violent changes of cladding temperature of fuel elements for cooling medium in two-phase flow. The computer program basing on the presented model was prepared for the calculations of initial parameters necessary for beginning the cladding and fuel material structural investigations. (author)
A novel, microscope based, non invasive Laser Doppler flowmeter for choroidal blood flow assessment
Strohmaier, C; Werkmeister, RM; Bogner, B; Runge, C; Schroedl, F; Brandtner, H; Radner, W; Schmetterer, L; Kiel, JW; Grabnerand, G; Reitsamer, HA
2011-01-01
Impaired ocular blood flow is involved in the pathogenesis of numerous ocular diseases like glaucoma or AMD. The purpose of the present study was to introduce and validate a novel, microscope based, non invasive laser Doppler flowmeter (NILDF) for measurement of blood flow in the choroid. The custom made NI-LDF was compared with a commercial fiber optic based laser Doppler flowmeter (Perimed PF4000). Linearity and stability of the NI-LDF were assessed in a silastic tubing model (i.d. 0.3 mm) ...
UNIFIED COMPUTATION OF FLOW WITH COMPRESSIBLE AND INCOMPRESSIBLE FLUID BASED ON ROE'S SCHEME
Institute of Scientific and Technical Information of China (English)
HUANG Dian-gui
2006-01-01
A unified numerical scheme for the solutions of the compressible and incompressible Navier-Stokes equations is investigated based on a time-derivative preconditioning algorithm. The primitive variables are pressure, velocities and temperature. The time integration scheme is used in conjunction with a finite volume discretization. The preconditioning is coupled with a high order implicit upwind scheme based on the definition of a Roe's type matrix. Computational capabilities are demonstrated through computations of high Mach number, middle Mach number, very low Mach number, and incompressible flow. It has also been demonstrated that the discontinuous surface in flow field can be captured for the implementation Roe's scheme.
[Application of three heat pulse technique-based methods to determine the stem sap flow].
Wang, Sheng; Fan, Jun
2015-08-01
It is of critical importance to acquire tree transpiration characters through sap flow methodology to understand tree water physiology, forest ecology and ecosystem water exchange. Tri-probe heat pulse sensors, which are widely utilized in soil thermal parameters and soil evaporation measurement, were applied to implement Salix matsudana sap flow density (Vs) measurements via heat-ratio method (HRM), T-Max method (T-Max) and single-probe heat pulse probe (SHPP) method, and comparative analysis was conducted with additional Grainer's thermal diffusion probes (TDP) measured results. The results showed that, it took about five weeks to reach a stable measurement stage after TPHP installation, Vs measured with three methods in the early stage after installation was 135%-220% higher than Vs in the stable measurement stage, and Vs estimated via HRM, T-Max and SHPP methods were significantly linearly correlated with Vs estimated via TDP method, with R2 of 0.93, 0.73 and 0.91, respectively, and R2 for Vs measured by SHPP and HRM reached 0.94. HRM had relatively higher precision in measuring low rates and reverse sap flow. SHPP method seemed to be very promising to measure sap flow for configuration simplicity and high measuring accuracy, whereas it couldn' t distinguish directions of flow. T-Max method had relatively higher error in sap flow measurement, and it couldn' t measure sap flow below 5 cm3 · cm(-2) · h(-1), thus this method could not be used alone, however it could measure thermal diffusivity for calculating sap flow when other methods were imposed. It was recommended to choose a proper method or a combination of several methods to measure stem sap flow, based on specific research purpose. PMID:26685585
A numerical study of unsteady two-dimensional subsonic compressible base flow
Rudy, David Henry
In subsonic flow, the wake behind a two dimensional body with a blunt trailing edge is dominated by a regular array of alternately shed vortices. This separated flow produces a low pressure on the base of the body, resulting in a drag component known as the base drag, which can constitute a major portion of the total drag of the body in many cases. One of the devices that was found to reduce the base drag in wind-tunnel experiments is a trailing-edge cavity. However, the flow mechanisms responsible for this drag reduction were not determined from the limited experimental data available. Therefore, the unsteady flow past a slender two-dimensional body with and without a trailing-edge cavity were studied using numerical solutions of the Navier-Stokes equations. The solution procedure utilized an explicit finite-difference scheme with second or fourth order accuracy in a space and second order accuracy in time. A major element in the solution procedure was the selection of an outflow boundary condition which minimized reflection from the boundary back into the solution domain. This solution was verified in computations of subsonic flow past square and circular cylinders, for which excellent agreement was obtained between computed shedding frequencies and experimental data. Solutions for the slender body were obtained. The computed shedding frequency was found to increase with increasing Reynolds numbers.
Cavitation erosion prediction based on analysis of flow dynamics and impact load spectra
Energy Technology Data Exchange (ETDEWEB)
Mihatsch, Michael S., E-mail: michael.mihatsch@aer.mw.tum.de; Schmidt, Steffen J.; Adams, Nikolaus A. [Institute of Aerodynamics and Fluid Mechanics, Technische Universität München, Boltzmannstr. 15, D-85748 Garching (Germany)
2015-10-15
Cavitation erosion is the consequence of repeated collapse-induced high pressure-loads on a material surface. The present paper assesses the prediction of impact load spectra of cavitating flows, i.e., the rate and intensity distribution of collapse events based on a detailed analysis of flow dynamics. Data are obtained from a numerical simulation which employs a density-based finite volume method, taking into account the compressibility of both phases, and resolves collapse-induced pressure waves. To determine the spectrum of collapse events in the fluid domain, we detect and quantify the collapse of isolated vapor structures. As reference configuration we consider the expansion of a liquid into a radially divergent gap which exhibits unsteady sheet and cloud cavitation. Analysis of simulation data shows that global cavitation dynamics and dominant flow events are well resolved, even though the spatial resolution is too coarse to resolve individual vapor bubbles. The inviscid flow model recovers increasingly fine-scale vapor structures and collapses with increasing resolution. We demonstrate that frequency and intensity of these collapse events scale with grid resolution. Scaling laws based on two reference lengths are introduced for this purpose. We show that upon applying these laws impact load spectra recorded on experimental and numerical pressure sensors agree with each other. Furthermore, correlation between experimental pitting rates and collapse-event rates is found. Locations of high maximum wall pressures and high densities of collapse events near walls obtained numerically agree well with areas of erosion damage in the experiment. The investigation shows that impact load spectra of cavitating flows can be inferred from flow data that captures the main vapor structures and wave dynamics without the need for resolving all flow scales.
Cavitation erosion prediction based on analysis of flow dynamics and impact load spectra
International Nuclear Information System (INIS)
Cavitation erosion is the consequence of repeated collapse-induced high pressure-loads on a material surface. The present paper assesses the prediction of impact load spectra of cavitating flows, i.e., the rate and intensity distribution of collapse events based on a detailed analysis of flow dynamics. Data are obtained from a numerical simulation which employs a density-based finite volume method, taking into account the compressibility of both phases, and resolves collapse-induced pressure waves. To determine the spectrum of collapse events in the fluid domain, we detect and quantify the collapse of isolated vapor structures. As reference configuration we consider the expansion of a liquid into a radially divergent gap which exhibits unsteady sheet and cloud cavitation. Analysis of simulation data shows that global cavitation dynamics and dominant flow events are well resolved, even though the spatial resolution is too coarse to resolve individual vapor bubbles. The inviscid flow model recovers increasingly fine-scale vapor structures and collapses with increasing resolution. We demonstrate that frequency and intensity of these collapse events scale with grid resolution. Scaling laws based on two reference lengths are introduced for this purpose. We show that upon applying these laws impact load spectra recorded on experimental and numerical pressure sensors agree with each other. Furthermore, correlation between experimental pitting rates and collapse-event rates is found. Locations of high maximum wall pressures and high densities of collapse events near walls obtained numerically agree well with areas of erosion damage in the experiment. The investigation shows that impact load spectra of cavitating flows can be inferred from flow data that captures the main vapor structures and wave dynamics without the need for resolving all flow scales
Yang, Hui; Cheng, Lei; Yuan, Jian; Zhang, Jie; Zhao, Yongli; Lee, Young
2015-06-01
With the rapid growth of data center services, the elastic optical network is a very promising networking architecture to interconnect data centers because it can elastically allocate spectrum tailored for various bandwidth requirements. In case of a link failure, to ensure a high-level quality of service (QoS) for user request after the failure becomes a research focus. In light of it, in this paper, we propose and experimentally demonstrate multipath protection for data center services in OpenFlow-based software defined elastic optical network testbed aiming at improving network reliability. We first propose an OpenFlow-based software defined elastic optical network architecture for data center service protection. Then, based on the proposed architecture, multipath protection scheme is figured based on the importance level of the service. To implement the proposed scheme in the architecture, OpenFlow protocol is extended to support multipath protection in elastic optical network. The performance of our proposed multipath protection scheme is evaluated by means of experiment on our OpenFlow-based testbed. The feasibility of our proposed scheme is also demonstrated in software defined elastic optical networks.
Comparison of different base flow separation methods in a lowland catchment
Directory of Open Access Journals (Sweden)
S. Uhlenbrook
2009-11-01
Full Text Available Assessment of water resources available in different storages and moving along different pathways in a catchment is important for its optimal use and protection, and also for the prediction of floods and low flows. Moreover, understanding of the runoff generation processes is essential for assessing the impacts of climate and land use changes on the hydrological response of a catchment. Many methods for base flow separation exist, but hardly one focuses on the specific behaviour of temperate lowland areas. This paper presents the results of a base flow separation study carried out in a lowland area in the Netherlands. In this study, field observations of precipitation, groundwater and surface water levels and discharges, together with tracer analysis are used to understand the runoff generation processes in the catchment. Several tracer and non-tracer based base flow separation methods were applied to the discharge time series, and their results are compared.
The results show that groundwater levels react fast to precipitation events in this lowland area with shallow groundwater tables. Moreover, a good correlation was found between groundwater levels and discharges suggesting that most of the measured discharge also during floods comes from groundwater storage. It was estimated using tracer hydrological approaches that approximately 90% of the total discharge is groundwater displaced by event water mainly infiltrating in the northern part of the catchment, and only the remaining 10% is surface runoff. The impact of remote recharge causing displacement of near channel groundwater during floods could also be motivated with hydraulic approximations. The results show further that when base flow separation is meant to identify groundwater contributions to stream flow, process based methods (e.g. the rating curve method; Kliner and Knezek, 1974 are more reliable than other simple non-tracer based methods. Also, the recursive filtering method
Comparison of different base flow separation methods in a lowland catchment
Directory of Open Access Journals (Sweden)
A. L. Gonzales
2009-04-01
Full Text Available Assessment of water resources kept in different storages and moving along different pathways in a catchment is important for its optimal use and protection, and also for the prediction of floods and low flows. Moreover, understanding of the runoff generation processes is essential for assessing the impacts of climate and land use changes on the hydrological response of a catchment. Many methods for base flow separation exist, but hardly one focuses on the specific behaviour of temperate lowland areas. This paper presents the results of a base flow separation study carried out in a lowland area in the Netherlands. In this research, field observations of precipitation, groundwater and surface water levels and discharges, together with tracer analysis are used to understand the runoff generation processes in the catchment. Several tracer and non-tracer based base flow separation methods were applied to the discharge time series, and their results are compared.
The results show that groundwater levels react fast to precipitation events in this lowland area with shallow groundwater tables. Moreover, a good correlation was found between groundwater levels and discharges meaning that most of the measured discharge also during floods comes from the groundwater storage. It was determined using tracer hydrological approaches that approximately 90% of the total discharge is groundwater displaced by event water infiltrating in the northern part of the catchment, and only the remaining 10% is surface runoff. The impact of remote recharge causing displacement of near channel groundwater during floods could also be motivated with hydraulic approximations. The results show further that when base flow separation is meant to separate groundwater contributions to stream flow, process based methods (e.g. rating curve method; Kliner and Knezek, 1974 are more reliable than other simple non-tracer based methods. Also, the recursive filtering method (proposed
Generation increases at Cofrentes Nuclear Power Plant based on accurate feedwater flow measurement
International Nuclear Information System (INIS)
This paper discusses the application of Caldon LEFM ultrasonic flow and temperature measurement systems at Cofrentes Nuclear Power Plant. Based on plant instrumentation, Cofrentes engineering personnel estimated an 8 to 10 MW electric shortfall in generation due to venturi nozzle fouling. An external LEFM ultrasonic flow measurement system installed in October 2000 showed a shortfall of about 9 MW electric, consistent with expectations. The plant has increased generation by using the more accurate ultrasonic system to correct for the venturi nozzle bias. Following the recovery of generation lost to venturi fouling, Cofrentes plans to upgrade the flow meter to Caldon's LEFM CheckPlus system. This system is sufficiently accurate to warrant re-licensing for a power up-rate of up to 1,7% based on improved thermal power measurement. (author)
Yu, Miao; Chen, Zongzheng; Xiang, Cheng; Liu, Bo; Xie, Handi; Qin, Kairong
2016-03-01
Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier. The microfluidic device overcomes the weakness of the traditional ones, which have been only based upon either stagnation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addition, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system. It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and conveniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.
Wang, Chao; Ji, Ming; Zhang, Ying; Jiang, Wentao; Lu, Xiaoyan; Wang, Jiaoying; Yang, Heng
2016-01-01
The electronic image stabilization technology based on improved optical-flow motion vector estimation technique can effectively improve the non normal shift, such as jitter, rotation and so on. Firstly, the ORB features are extracted from the image, a set of regions are built on these features; Secondly, the optical-flow vector is computed in the feature regions, in order to reduce the computational complexity, the multi resolution strategy of Pyramid is used to calculate the motion vector of the frame; Finally, qualitative and quantitative analysis of the effect of the algorithm is carried out. The results show that the proposed algorithm has better stability compared with image stabilization based on the traditional optical-flow motion vector estimation method.
Yu, Miao; Chen, Zongzheng; Xiang, Cheng; Liu, Bo; Xie, Handi; Qin, Kairong
2016-06-01
Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the relationship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier. The microfluidic device overcomes the weakness of the traditional ones, which have been only based upon either stagnation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addition, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system. It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and conveniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.
Lakshminarayana, B.; Ho, Y.; Basson, A.
1993-01-01
The objective of this research is to simulate steady and unsteady viscous flows, including rotor/stator interaction and tip clearance effects in turbomachinery. The numerical formulation for steady flow developed here includes an efficient grid generation scheme, particularly suited to computational grids for the analysis of turbulent turbomachinery flows and tip clearance flows, and a semi-implicit, pressure-based computational fluid dynamics scheme that directly includes artificial dissipation, and is applicable to both viscous and inviscid flows. The values of these artificial dissipation is optimized to achieve accuracy and convergency in the solution. The numerical model is used to investigate the structure of tip clearance flows in a turbine nozzle. The structure of leakage flow is captured accurately, including blade-to-blade variation of all three velocity components, pitch and yaw angles, losses and blade static pressures in the tip clearance region. The simulation also includes evaluation of such quantities of leakage mass flow, vortex strength, losses, dominant leakage flow regions and the spanwise extent affected by the leakage flow. It is demonstrated, through optimization of grid size and artificial dissipation, that the tip clearance flow field can be captured accurately. The above numerical formulation was modified to incorporate time accurate solutions. An inner loop iteration scheme is used at each time step to account for the non-linear effects. The computation of unsteady flow through a flat plate cascade subjected to a transverse gust reveals that the choice of grid spacing and the amount of artificial dissipation is critical for accurate prediction of unsteady phenomena. The rotor-stator interaction problem is simulated by starting the computation upstream of the stator, and the upstream rotor wake is specified from the experimental data. The results show that the stator potential effects have appreciable influence on the upstream rotor wake
Evaluation of inhomogeneous model and the LCS based investigation in multiphase flows
International Nuclear Information System (INIS)
In this paper, an evaluation of inhomogeneous model for computations of gas-liquid two-phase flow is presented, and the mechanism of gas-liquid two-phase flow in a bubble column is studied based on Finite-Time Lyapunov Exponents (FTLE) and Lagrangian Coherent Structures (LCS). The simulation is conducted with the homogeneous and inhomogeneous models respectively, and the numerical results are compared with the experimental data. It is shown that the inhomogeneous model can calculate the force of the gas more accurately and simulates the details of transient flows well due to the consideration of the interaction between the two phases. With inhomogeneous model, the periodic fluctuation of the bubble hose is captured and the velocity distribution coincides exactly with the experimental data. For the gas-liquid two-phase flow in the bubble column, the process of gaseous flow injected into water can be divided into two stages: the gas rising and gas fluctuation. The Lagrangian Coherent Structures (LCS) which consist of the ridges of the FTLE field can capture the boundary of vortex and the interface between the forward and backward flows in the liquid region, and the LCS have unique value for representing the divergence extent of neighboring particles in regions with different dynamics characteristics
Seo, Hyeon-Seok; Boo, Jin-Hyo; Kim, Youn-Jea
2015-11-01
The characteristics of thermomagnetic convective flow in a rectangular enclosure heated from below and filled with oil-based nanofluid (EFH-1, Ferrotec.), so called ferrofluid, were numerically investigated. The enclosure contained obstacles with rectangular or triangular configurations mounted on the top and bottom walls. To generate homogeneous magnetic fields, a permanent magnet with a uniform magnetic field strength of 600 kA/m was located in the lower part of the rectangular enclosure, and specified the horizontal or vertical direction. Coupling calculations between thermal-flow field and magnetic field in the analysis model were performed using the commercial code, COMSOL Multiphysics. Results showed that the ferrofluid flow fields were affected by the applied external magnetic field directions and that the eddy flow phenomena in the rectangular enclosure were generated in the vicinity of the section of high magnetic flux density fields such as the edge of the permanent magnet. The effect of parameters like temperature distributions and local Nusselt number (Nu) profiles on the thermomagnetic convective flow was graphically depicted with various flow conditions. PMID:26726559
Method for Flow Measurement in Microfluidic Channels Based on Electrical Impedance Spectroscopy
Arjmandi, Nima; Van Roy, Willem; Lagae, Liesbet; Borghs, Gustaaf; 10.1007/s10404-011-0843-0
2012-01-01
We have developed and characterized two novel micro flow sensors based on measuring the electrical impedance of the interface between the flowing liquid and metallic electrodes embedded on the channel walls. These flow sensors are very simple to fabricate and use, are extremely compact and can easily be integrated into most microfluidic systems. One of these devices is a micropore with two tantalum/platinum electrodes on its edges; the other is a micro channel with two tantalum /platinum electrodes placed perpendicular to the channel on its walls. In both sensors the flow rate is measured via the electrical impedance between the two metallic electrodes, which is the impedance of two metal-liquid junctions in series. The dependency of the metal-liquid junction impedance on the flow rate of the liquid has been studied. The effects of different parameters on the sensor's outputs and its noise behavior are investigated. Design guidelines are extracted and applied to achieve highly sensitive micro flow sensors wit...
Application of recently developed elliptic blending based models to separated flows
International Nuclear Information System (INIS)
Highlights: ► The study focuses on elliptic blending near-wall models. ► Models are compared on 2- and 3-dimensional separating flows. ► Conclusions are ambiguous on 2-d flows. ► Predictive superiority of Reynolds stress models over eddy viscosity model appear on 3-d flows. - Abstract: This paper considers the application of four Reynolds-Averaged Navier Stokes (RANS) models to a range of progressively complex test cases, exhibiting both 2-d and 3-d flow separation. Two Eddy Viscosity Models (EVM) and two Reynolds Stress Transport Models (RSM) are employed, of which two (one in each category) are based on elliptic blending formulations. By both reviewing the conclusions of previous studies, and from the present calculations, this study aims at gaining more insight into the importance of two modelling features for these flows: the usage of turbulence anisotropy resolving schemes, and the near-wall limiting behaviour. In general the anisotropy and near wall treatment offered by both elliptic blending models is observed to offer some improvement over other models tested, although this is not always the case for the 2-d flows, where (as ever) a single “best candidate” model does not emerge.
An effective depression filling algorithm for DEM-based 2-dimensional surface flow modelling
Directory of Open Access Journals (Sweden)
D. Zhu
2012-09-01
Full Text Available The surface runoff process in fluvial/pluvial flood modelling is often simulated employing a two-dimensional (2-D diffusive wave approximation to described by grid based digital elevation models (DEMs. However, a serious problem of this approach may arise when using a 2-D surface flow model which exchanges flows through adjacent cells, or conventional rink removal algorithms which also allow flow to be exchanged along diagonal directions, due to the existence of artificial depression in DEMs. This study firstly analyses the two types of depressions in DEMs and reviews the current depression filling algorithms with a medium sized basin in South-East England, the Upper Medway Catchment (220 km^{2} used to demonstrate the depression issue in 2-D surface runoff simulation by MIKE SHE with different DEM resolutions (50 m, 100 m and 200 m. An alternative depression-filling algorithm for 2-D overland flow modelling is developed and evaluated by comparing the simulated flows at the outlet of the catchment. This result suggests that the depression estimates at different grid resolution of DEM highly influences overland flow estimation and the new depression filling algorithm is shown to be effective in tackling this issue when comparing simulations in sink-dominated and sink-free digital elevation models, especially for depressions in relatively flat areas on digital land surface models.
Multi-phase flow monitoring with electrical impedance tomography using level set based method
Energy Technology Data Exchange (ETDEWEB)
Liu, Dong [Department of Applied Physics, University of Eastern Finland, Kuopio FIN-70211 (Finland); Khambampati, Anil Kumar [Institute for Nuclear Science and Technology, Jeju National University, Jeju 690-756 (Korea, Republic of); Kim, Sin [School of Energy Systems Engineering, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Kim, Kyung Youn, E-mail: kyungyk@jejunu.ac.kr [Department of Electronic Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of)
2015-08-15
Highlights: • LSM has been used for shape reconstruction to monitor multi-phase flow using EIT. • Multi-phase level set model for conductivity is represented by two level set functions. • LSM handles topological merging and breaking naturally during evolution process. • To reduce the computational time, a narrowband technique was applied. • Use of narrowband and optimization approach results in efficient and fast method. - Abstract: In this paper, a level set-based reconstruction scheme is applied to multi-phase flow monitoring using electrical impedance tomography (EIT). The proposed scheme involves applying a narrowband level set method to solve the inverse problem of finding the interface between the regions having different conductivity values. The multi-phase level set model for the conductivity distribution inside the domain is represented by two level set functions. The key principle of the level set-based method is to implicitly represent the shape of interface as the zero level set of higher dimensional function and then solve a set of partial differential equations. The level set-based scheme handles topological merging and breaking naturally during the evolution process. It also offers several advantages compared to traditional pixel-based approach. Level set-based method for multi-phase flow is tested with numerical and experimental data. It is found that level set-based method has better reconstruction performance when compared to pixel-based method.
Exponential Smoothing Method of Base Flow Separation and Its Impact on Continuous Loss Estimates
Directory of Open Access Journals (Sweden)
G. A. Tularam
2008-01-01
Full Text Available The calculation of loss is vital for design flood estimation models and in order to estimate continuing loss (CL, proportional loss (PL and volumetric runoff coefficient, the surface runoff has to be separated from the total given in a stream flow hydrograph. To obtain the volume of surface runoff from the streamflow hydrograph, baseflow separation becomes necessary and in this paper a few base flow separation methods are explored and an appropriate method selected to assess to impact of baseflow on loss estimates. The process of separation requires a base flow separation coefficient and this coefficient (α is selected from individual study catchments from 3 to 5 rainfall streamflow events of the same catchments based on sensitivity analysis. The selected α value of individual catchments is then applied to other rainfall streamflow events of a given catchment. It has been observed that a small degree of error in the selection of α value does not seem to affect the estimates of the CL, PL or runoff coefficient. Hence, the more practical base flow separation method used in this paper may be applied to other rural catchments for baseflow separation in design loss studies.
Dynamic melt flow of nanocomposites based on poly-epsilon-caprolactam
DEFF Research Database (Denmark)
Utracki, Leszek; Lyngaae-Jørgensen, Jørgen
2002-01-01
The dynamic flow behavior of polyamide-6 (PA-6) and a nanocomposite (PNC) based on it was studied. The latter resin contained 2 wt% of organoclay. The two materials were blended in proportions of 0, 25, 50, 75, and 100 wt% PNC. The dynamic shear rheological properties of well-dried specimens were...
Fifth Graders' Flow Experience in a Digital Game-Based Science Learning Environment
Zheng, Meixun
2012-01-01
This mixed methods study examined the flow experience of 5th graders in the CRYSTAL ISLAND game-based science learning environment. Participants were 73 5th graders from a suburban public school in the southeastern US. Quantitative data about students' science content learning and attitudes towards science was collected via pre-and post…
RESEARCH OF INNER FLOW IN A DOUBLE BLADES PUMP BASED ON OPENFOAM
Institute of Scientific and Technical Information of China (English)
LIU Hou-lin; REN Yun; WANG Kai; WU Deng-hao; RU Wei-min; TAN Ming-gao
2012-01-01
The inner flow analysis of centrifugal pumps has gradually become an important issue for the hydraulic design and performance improvement.Nowadays,CFD simulation toolbox of pump inner flow mainly contains commercial tools and open source tools.There are some detects for commercial CFD software for the numerical simulation of 3-D turbulent internal flow in pump,especially in capturing the flow characteristics under the off-design operating conditions.Additionally,it is difficult for researchers to do further investigation because of the undeclared source.Therefore,an open source software like Open Field Operation and Manipulation (OpenFOAM) is increasingly popular with researchers from all over the world.In this paper,a new computational study was implemented based on the original solver and was used to directly simulate the steady-state inner flow in a double blades pump,with the specific speed is 111.In order to disclose the characteristics deeply,three research schemes were conducted.The ratios (Q/Qd) of the flow rate are 0.8,1.0 and 1.2,respectively.The simulation results were verified with the Particle Imaging Velocimetry (PIV) experimental results,and the numerical calculation results agree well with the experimental data.Meanwhile,the phenomena of flow separation under the off-design operating conditions are well captured by OpenFOAM.The results indicate that OpenFOAM possesses obvious strong predominance in computing the internal flow field of pump.The analysis results can also be used as the basis for the further research and the improvement of centrifugal pump.
Flow-injection amperometric glucose biosensors based on graphene/Nafion hybrid electrodes
Energy Technology Data Exchange (ETDEWEB)
Choi, Bong Gill, E-mail: k1811@kaist.ac.kr [Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, Daejeon 305-701 (Korea, Republic of); Im, Jinkyu, E-mail: JINQ@paran.com [Department of Chemistry and Research Institute of Basic Sciences, Kyung Hee University, 1 Hoegidong, Dongdamoongu, Seoul (Korea, Republic of); Kim, Hoon Sik, E-mail: khs2004@khu.ac.kr [Department of Chemistry and Research Institute of Basic Sciences, Kyung Hee University, 1 Hoegidong, Dongdamoongu, Seoul (Korea, Republic of); Park, HoSeok, E-mail: phs0727@khu.ac.kr [Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1 Seochon-dong, Giheung-gu, Youngin-si, Gyeonggi-do 446-701 (Korea, Republic of)
2011-11-30
Graphical abstract: Amperometric biosensors based on graphene hybrids showed the fast, sensitive, and stable amperometric responses in the flow injection system for automatically monitoring glucose. Display Omitted Highlights: > Flow-injection amperometric glucose biosensors were fabricated using reduced graphene oxide/Nafion hybrids. > The electrochemical kinetics of biosensors were comprehensively investigated by analysing electron transfer rate, charge transfer resistance, and ion diffusion coefficient, respectively. > The biosensors exhibited the fast, sensitive, and stable amperometric responses in the flow injection system for detecting glucose. - Abstract: In this research, we demonstrated the fabrication of flow-injection amperometric glucose biosensors based on RGO/Nafion hybrids. The nanohybridization of the reduced graphene oxide (RGO) by Nafion provided the fast electron transfer (ET) for the sensitive amperometric biosensor platforms. The ET rate (k{sub s}) and the charge transfer resistance (R{sub CT}) of GOx-RGO/Nafion hybrids were evaluated to verify the accelerated ET. Moreover, hybrid biosensors revealed a quasi-reversible and surface controlled process, as confirmed by the low peak-to-peak ({Delta}E{sub p}) and linear relations between I{sub p} and scan rate ({nu}). Hybrid biosensors showed the fast response time of {approx}3 s, the sensitivity of 3.8 {mu}A mM{sup -1} cm{sup -2}, the limit of detection of 170 {mu}M, and the linear detection range of 2-20 mM for the flow-injection amperometric detection of glucose. Furthermore, interference effect of oxidizable species such as ascorbic acid (AA) and uric acid (UA) on the performance of hybrid biosensors was prevented at the operating potential of -0.20 V even under the flow injection mode. Therefore, the fast, sensitive, and stable amperometric responses of hybrid biosensors in the flow injection system make it highly suitable for automatically monitoring glucose.
Flow-injection amperometric glucose biosensors based on graphene/Nafion hybrid electrodes
International Nuclear Information System (INIS)
Graphical abstract: Amperometric biosensors based on graphene hybrids showed the fast, sensitive, and stable amperometric responses in the flow injection system for automatically monitoring glucose. Display Omitted Highlights: → Flow-injection amperometric glucose biosensors were fabricated using reduced graphene oxide/Nafion hybrids. → The electrochemical kinetics of biosensors were comprehensively investigated by analysing electron transfer rate, charge transfer resistance, and ion diffusion coefficient, respectively. → The biosensors exhibited the fast, sensitive, and stable amperometric responses in the flow injection system for detecting glucose. - Abstract: In this research, we demonstrated the fabrication of flow-injection amperometric glucose biosensors based on RGO/Nafion hybrids. The nanohybridization of the reduced graphene oxide (RGO) by Nafion provided the fast electron transfer (ET) for the sensitive amperometric biosensor platforms. The ET rate (ks) and the charge transfer resistance (RCT) of GOx-RGO/Nafion hybrids were evaluated to verify the accelerated ET. Moreover, hybrid biosensors revealed a quasi-reversible and surface controlled process, as confirmed by the low peak-to-peak (ΔEp) and linear relations between Ip and scan rate (ν). Hybrid biosensors showed the fast response time of ∼3 s, the sensitivity of 3.8 μA mM-1 cm-2, the limit of detection of 170 μM, and the linear detection range of 2-20 mM for the flow-injection amperometric detection of glucose. Furthermore, interference effect of oxidizable species such as ascorbic acid (AA) and uric acid (UA) on the performance of hybrid biosensors was prevented at the operating potential of -0.20 V even under the flow injection mode. Therefore, the fast, sensitive, and stable amperometric responses of hybrid biosensors in the flow injection system make it highly suitable for automatically monitoring glucose.
Muskingum equation based downstream sediment flow simulation models for a river system
Institute of Scientific and Technical Information of China (English)
Briti Sundar Sil; Parthasarathi Choudhury
2016-01-01
Applications of sediment transport and water flow characteristics based sediment transport simulation models for a river system are presented in this study. An existing water–sediment model and a new sediment–water model are used to formulate the simulation models representing water and sediment movement in a river system. The sediment–water model parameters account for water flow characteristics embodying sediment transport properties of a section. The models are revised formulations of the multiple water inflows model describing water movement through a river system as given by the Muskingum principle. The models are applied to a river system in Mississippi River basin to estimate downstream sediment concentration, sediment discharge, and water discharge. River system and the river section parameters are estimated using a revised and the original multiple water inflows models by applying the genetic algorithm. The models estimate downstream sediment transport rates on the basis of upstream sediment/water flow rates to a system. Model performance is evaluated by using standard statistical criteria;downstream water discharge resulting from the original multiple water inflows model using the estimated river system parameters indicate that the revised models satisfactorily describe water movement through a river system. Results obtained in the study demonstrate the applicability of the sediment transport and water flow characteristics-based simulation models in predicting downstream sediment transport and water flow rates in a river system.
Liu, Jintao; Chen, Xi; Zhang, Xingnan; Hoagland, Kyle D.
2012-04-01
Recently developed hillslope storage dynamics theory can represent the essential physical behavior of a natural system by accounting explicitly for the plan shape of a hillslope in an elegant and simple way. As a result, this theory is promising for improving catchment-scale hydrologic modeling. In this study, grid digital elevation model (DEM) based algorithms for determination of hillslope geometric characteristics (e.g., hillslope units and width functions in hillslope storage dynamics models) are presented. This study further develops a method for hillslope partitioning, established by Fan and Bras (1998), by applying it on a grid network. On the basis of hillslope unit derivation, a flow distance transforms method (TD∞) is suggested in order to decrease the systematic error of grid DEM-based flow distance calculation caused by flow direction approximation to streamlines. Hillslope width transfer functions are then derived to convert the probability density functions of flow distance into hillslope width functions. These algorithms are applied and evaluated on five abstract hillslopes, and detailed tests and analyses are carried out by comparing the derivation results with theoretical width functions. The results demonstrate that the TD∞ improves estimations of the flow distance and thus hillslope width function. As the proposed procedures are further applied in a natural catchment, we find that the natural hillslope width function can be well fitted by the Gaussian function. This finding is very important for applying the newly developed hillslope storage dynamics models in a real catchment.
Zheng, Dandan; Hou, Huirang; Zhang, Tao
2016-04-01
For ultrasonic gas flow rate measurement based on ultrasonic exponential model, when the noise frequency is close to that of the desired signals (called similar-frequency noise) or the received signal amplitude is small and unstable at big flow rate, local convergence of the algorithm genetic-ant colony optimization-3cycles may appear, and measurement accuracy may be affected. Therefore, an improved method energy genetic-ant colony optimization-3cycles (EGACO-3cycles) is proposed to solve this problem. By judging the maximum energy position of signal, the initial parameter range of exponential model can be narrowed and then the local convergence can be avoided. Moreover, a DN100 flow rate measurement system with EGACO-3cycles method is established based on NI PCI-6110 and personal computer. A series of experiments are carried out for testing the new method and the measurement system. It is shown that local convergence doesn't appear with EGACO-3cycles method when similar-frequency noises exist and flow rate is big. Then correct time of flight can be obtained. Furthermore, through flow calibration on this system, the measurement range ratio is achieved 500:1, and the measurement accuracy is 0.5% with a low transition velocity 0.3 m/s. PMID:26821309
International Nuclear Information System (INIS)
The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr)
Shen, J. F.; Li, Y. J.; Liu, Z. Q.; Tang, X. L.
2013-12-01
The Large Eddy Simulation method with sliding mesh technique has been used for analyzing the unsteady flow in an axial-flow pump at five different flow rates. The tip leakage flow in the tip-gap region and the pressure pulsations on the blade surface were examined. The results indicate that the agreement between predicted pump performance and experimental data was reasonably good. The dominate tip-leakage vortex(TLV) extended to the pressure side of the neighboring blade for all five investigated flow rates. As the flow rate increases from 0.7Qd to 1.2Qd, the angle between the dominate TLV and the blade reduced from 20 deg to 14 deg. The results also showed that the amplitude of pressure fluctuation on the near-tip zone of the blade surface increases as the flow rate farer from the design flow rate, especially on the pressure side of the blade. At the 0.7Qd operation condition, the pressure fluctuation amplitude of the monitoring point PP3 (at the near-tip zone on the pressure side of the blade close to the blade leading edge) was 8.5 times of the one at design flow rate, and the high-frequency(18fr) pulsation occurred due to tip leakage vortex. When the flow rate was more than 1.0Qd, the pressure fluctuations of PP3 was dominated by the rotation frequency(fr).
DEFF Research Database (Denmark)
Thorndahl, Søren; Poulsen, Troels Sander; Bøvith, Thomas;
2012-01-01
Forecast based flow prediction in drainage systems can be used to implement real time control of drainage systems. This study compares two different types of rainfall forecasts – a radar rainfall extrapolation based nowcast model and a numerical weather prediction model. The models are applied as...... performance of the system is found using the radar nowcast for the short leadtimes and weather model for larger lead times....
DEFF Research Database (Denmark)
Thorndahl, Søren Liedtke; Poulsen, Troels Sander; Bøvith, Thomas;
2012-01-01
Forecast based flow prediction in drainage systems can be used to implement real time control of drainage systems. This study compares two different types of rainfall forecasts – a radar rainfall extrapolation based nowcast model and a numerical weather prediction model. The models are applied as...... performance of the system is found using the radar nowcast for the short leadtimes and weather model for larger lead times....
Will it rise or will it fall? Managing the complex effects of urbanization on base flow
Bhaskar, Aditi; Beesley, Leah; Burns, Matthew J.; Fletcher, T. D.; Hamel, Perrine; Oldham, Carolyn; Roy, Allison
2016-01-01
Sustaining natural levels of base flow is critical to maintaining ecological function as stream catchments are urbanized. Research shows a variable response of stream base flow to urbanization, with base flow or water tables rising in some locations, falling in others, or elsewhere remaining constant. The variable baseflow response is due to the array of natural (e.g., physiographic setting and climate) and anthropogenic (e.g., urban development and infrastructure) factors that influence hydrology. Perhaps as a consequence of this complexity, few simple tools exist to assist managers to predict baseflow change in their local urban area. This paper addresses this management need by presenting a decision support tool. The tool considers the natural vulnerability of the landscape, together with aspects of urban development in predicting the likelihood and direction of baseflow change. Where the tool identifies a likely increase or decrease it guides managers toward strategies that can reduce or increase groundwater recharge, respectively. Where the tool finds an equivocal result, it suggests a detailed water balance be performed. The decision support tool is embedded within an adaptive-management framework that encourages managers to define their ecological objectives, assess the vulnerability of their ecological objectives to changes in water table height, and monitor baseflow responses to urbanization. We trial our framework using two very different case studies: Perth, Western Australia, and Baltimore, Maryland, USA. Together, these studies show how pre-development water table height, climate and geology together with aspects of urban infrastructure (e.g., stormwater practices, leaky pipes) interact such that urbanization has overall led to rising base flow (Perth) and falling base flow (Baltimore). Greater consideration of subsurface components of the water cycle will help to protect and restore the ecology of urban freshwaters.
International Nuclear Information System (INIS)
Graphical abstract: -- Highlights: •Flow amperometric enzymatic biosensor was constructed. •The biosensor is based on a reactor of a novel material – porous silver solid amalgam. •Tubular amalgam detector was used for determination of decrease of O2 concentration. •Covalent bonds amalgam−thiol−enzyme contributed to the sensor long-term stability. •LOD of glucose was 0.01 mmol L−1 with RSD = 1.3% (n = 11). -- Abstract: A flow amperometric enzymatic biosensor for the determination of glucose was constructed. The biosensor consists of a flow reactor based on porous silver solid amalgam (AgSA) and a flow tubular detector based on compact AgSA. The preparation of the sensor and the determination of glucose occurred in three steps. First, a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed at the porous surface of the reactor. Second, enzyme glucose oxidase (GOx) was covalently immobilized at MUA-layer using N-ethyl-N′-(3-dimethylaminopropyl) carboimide and N-hydroxysuccinimide chemistry. Finally, a decrease of oxygen concentration (directly proportional to the concentration of glucose) during enzymatic reaction was amperometrically measured on the tubular detector under flow injection conditions. The following parameters of glucose determination were optimized with respect to amperometric response: composition of the mobile phase, its concentration, the potential of detection and the flow rate. The calibration curve of glucose was linear in the concentration range of 0.02–0.80 mmol L−1 with detection limit of 0.01 mmol L−1. The content of glucose in the sample of honey was determined as 35.5 ± 1.0 mass % (number of the repeated measurements n = 7; standard deviation SD = 1.2%; relative standard deviation RSD = 3.2%) which corresponds well with the declared values. The tested biosensor proved good long-term stability (77% of the current response of glucose was retained after 35 days)
Zhi-jian Wang; Jian-she Zheng; Lu-lu Li; Shuai Luo
2013-01-01
The three-dimensional flow physical model of any stage of the 20BZ4 multistage centrifugal pump is built which includes inlet region, impeller flow region, guide-vane flow region and exit region. The three-dimensional unsteady turbulent flow numerical model is created based on Navier-Stoke solver and standard k-ε turbulent equations. The method of multireference frame (MRF) and SIMPLE algorithm are used to simulate the flow in multistage centrifugal pump based on FLUENT software. The distribu...
Kaleidaseq: A Web-Based Tool to Monitor Data Flow in a High Throughput Sequencing Facility
Dedhia, Neilay N.; McCombie, W. Richard
1998-01-01
Tracking data flow in high throughput sequencing is important in maintaining a consistent number of successfully sequenced samples, making decisions on scheduling the flow of sequencing steps, resolving problems at various steps and tracking the status of different projects. This is especially critical when the laboratory is handling a multitude of projects. We have built a Web-based data flow tracking package, called Kaleidaseq, which allows us to monitor the flow and quality of sequencing s...
Yan, Yajing; Ferro-Famil, Laurent; Gay, Michel; Fallourd, Renaud; Trouvé, Emmanuel; Vernier, Flavien
2013-01-01
International audience In this paper, an attempt of Alpine glacier flow modeling is performed based on a series of high resolution TerraSAR-X SAR images and a Digital Elevation Model. First, a glacier flow model is established according to the fluid mechanics theory in a simplified framework. Second, the displacement field over the glacier obtained from the sub-pixel image correlation of a series of TerraSAR-X SAR images is used to refine the model obtained previously. The comparison betwe...
Traffic Flow Analysis Model based Routing Protocol For Multi-Protocol Label Switching Network
E.R. Naganathan; Rajagopalan, S.; P. H. Raj
2011-01-01
Problem statement: Multi-Protocol Label Switching (MPLS) is a mechanism which is used in high-performance telecommunications networks that directs and carries data from one network node to the next with the help of labels. Traffic management is still an issue in MPLS network as it involves high speed internet. Approach: This study proposed a traffic flow analysis of the real time MPLS traffic and segregates the MPLS traffic as three major class based on the outcome of traffic flow analysis. U...
Wave propagation of the traffic flow dynamic model based on wavefront expansion
Institute of Scientific and Technical Information of China (English)
李莉; 施鹏飞
2004-01-01
This paper discusses propagation of perturbations along traffic flow modeled by a modified second-order macroscopic model through the wavefront expansion technique. The coefficients in this expansion satisfy a sequence of transport equations that can be solved analytically. One of these analytic solutions yields information about wavefront shock. Numerical simulations based on a Padé approximation of this expansion were done at the end of this paper and results showed that propagation of perturbations at traffic flow speed conforms to the theoretical analysis results.
A MEMS-based Air Flow Sensor with a Free-standing Micro-cantilever Structure
Che-Ming Chiang; Chia-Yen Lee; Yu-Hsiang Wang
2007-01-01
This paper presents a micro-scale air flow sensor based on a free-standing cantilever structure. In the fabrication process, MEMS techniques are used to deposit a silicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitride layer to form a piezoresistor, and the resulting structure is then etched to create a freestanding micro-cantilever. When an air flow passes over the surface of the cantilever beam, the beam deflects in the downward direction, resulting in...
Demonstration of a plasma mirror based on a laminar flow water film
Energy Technology Data Exchange (ETDEWEB)
Panasenko, Dmitriy; Shu, Anthony; Gonsalves, Anthony; Nakamura, Kei; Matlis, Nicholas; Toth, Csaba; Leemans, Wim
2011-07-22
A plasma mirror based on a laminar water film with low flow speed 0.5-2 cm/s has been developed and characterized, for use as an ultrahigh intensity optical reflector. The use of flowing water as atarget surface automatically results in each laser pulse seeing a new interaction surface and avoids the need for mechanical scanning of the target surface. In addition, the breakdown of water does notproduce contaminating debris that can be deleterious to vacuum chamber conditions and optics, such as is the case when using conventional solid targets. The mirror exhibits 70percent reflectivity, whilemaintaining high-quality of the reflected spot.
DEFF Research Database (Denmark)
Miró, Manuel; Hartwell, Supaporn Kradtap; Jakmunee, Jaroon; Grudpan, Kate; Hansen, Elo Harald
2008-01-01
Solid-phase extraction (SPE) is the most versatile sample-processing method for removal of interfering species and/or analyte enrichment. Although significant advances have been made over the past two decades in automating the entire analytical protocol involving SPE via flow-injection approaches...... overcoming the above shortcomings, so-called bead-injection (BI) analysis, based on automated renewal of the sorbent material per assay exploiting the various generations of flow-injection analysis. It addresses novel instrumental developments for implementing BI and a number of alternatives for online...
Room Temperature, Hybrid Sodium-Based Flow Batteries with Multi-Electron Transfer Redox Reactions
Shamie, Jack S.; Caihong Liu; Shaw, Leon L.; Vincent L. Sprenkle
2015-01-01
We introduce a new concept of hybrid Na-based flow batteries (HNFBs) with a molten Na alloy anode in conjunction with a flowing catholyte separated by a solid Na-ion exchange membrane for grid-scale energy storage. Such HNFBs can operate at ambient temperature, allow catholytes to have multiple electron transfer redox reactions per active ion, offer wide selection of catholyte chemistries with multiple active ions to couple with the highly negative Na alloy anode, and enable the use of both a...
3D CFD computations of transitional flows using DES and a correlation based transition model
DEFF Research Database (Denmark)
Sørensen, Niels N.
process can be important for the aerodynamic performance. Today, the most widespread approach is to use fully turbulent computations, where the transitional process is ignored and the entire boundary layer on the wings or airfoils is handled by the turbulence model. The correlation based transition model...... has lately shown promising results, and the present paper describes the application of the model to predict the drag and shedding frequency for flow around a cylinder from sub to super-critical Reynolds numbers. Additionally, the model is applied to the flow around the DU-96 airfoil, at high angles of...
Surface-tension-driven Stokes flow: A numerical method based on conformal geometry
Buchak, Peter; Crowdy, Darren G.
2016-07-01
A novel numerical scheme is presented for solving the problem of two dimensional Stokes flows with free boundaries whose evolution is driven by surface tension. The formulation is based on a complex variable formulation of Stokes flow and use of conformal mapping to track the free boundaries. The method is motivated by applications to modelling the fabrication process for microstructured optical fibres (MOFs), also known as "holey fibres", and is therefore tailored for the computation of multiple interacting free boundaries. We give evidence of the efficacy of the method and discuss its performance.
Intube two-phase flow probabilities based on capacitance signal clustering
Canière, Hugo; T'Joen, Christophe; De Paepe, Michel
2009-01-01
To study the objectivity in flow pattern mapping of horizontal two-phase flow in macroscale tubes, a capacitance sensor is developed for use with refrigerants. Sensor signals are gathered with R410A in an 8mm I.D. smooth tube at a saturation temperature of 15°C in the mass velocity range of 200 to 500kg/m²s and vapour quality range from 0 to 1 in steps of 0.025. A visual classification based on high speed camera images is made for comparison reasons. A statistical analysis of the sensor signa...
Sazhin, O.
2013-01-01
An analytical model of the thermal flow sensor has been developed. The results of analytical model application are utilized to develop a thermal flow microsensor with optimal functional characteristics. The technology to manufacture the microsensor is described. A prototype of the microsensor suitable to be used in the mass air flow meter has been designed. The basic characteristics of the microsensor are presented. © 2013 Elsevier Ltd.
Fan, Xiaofeng; Wang, Jiangfeng
2016-06-01
The atomization of liquid fuel is a kind of intricate dynamic process from continuous phase to discrete phase. Procedures of fuel spray in supersonic flow are modeled with an Eulerian-Lagrangian computational fluid dynamics methodology. The method combines two distinct techniques and develops an integrated numerical simulation method to simulate the atomization processes. The traditional finite volume method based on stationary (Eulerian) Cartesian grid is used to resolve the flow field, and multi-component Navier-Stokes equations are adopted in present work, with accounting for the mass exchange and heat transfer occupied by vaporization process. The marker-based moving (Lagrangian) grid is utilized to depict the behavior of atomized liquid sprays injected into a gaseous environment, and discrete droplet model 13 is adopted. To verify the current approach, the proposed method is applied to simulate processes of liquid atomization in supersonic cross flow. Three classic breakup models, TAB model, wave model and K-H/R-T hybrid model, are discussed. The numerical results are compared with multiple perspectives quantitatively, including spray penetration height and droplet size distribution. In addition, the complex flow field structures induced by the presence of liquid spray are illustrated and discussed. It is validated that the maker-based Eulerian-Lagrangian method is effective and reliable.
In vitro flow cytometry-based screening platform for cellulase engineering.
Körfer, Georgette; Pitzler, Christian; Vojcic, Ljubica; Martinez, Ronny; Schwaneberg, Ulrich
2016-01-01
Ultrahigh throughput screening (uHTS) plays an essential role in directed evolution for tailoring biocatalysts for industrial applications. Flow cytometry-based uHTS provides an efficient coverage of the generated protein sequence space by analysis of up to 10(7) events per hour. Cell-free enzyme production overcomes the challenge of diversity loss during the transformation of mutant libraries into expression hosts, enables directed evolution of toxic enzymes, and holds the promise to efficiently design enzymes of human or animal origin. The developed uHTS cell-free compartmentalization platform (InVitroFlow) is the first report in which a flow cytometry-based screened system has been combined with compartmentalized cell-free expression for directed cellulase enzyme evolution. InVitroFlow was validated by screening of a random cellulase mutant library employing a novel screening system (based on the substrate fluorescein-di-β-D-cellobioside), and yielded significantly improved cellulase variants (e.g. CelA2-H288F-M1 (N273D/H288F/N468S) with 13.3-fold increased specific activity (220.60 U/mg) compared to CelA2 wildtype: 16.57 U/mg). PMID:27184298
In vitro flow cytometry-based screening platform for cellulase engineering
Körfer, Georgette; Pitzler, Christian; Vojcic, Ljubica; Martinez, Ronny; Schwaneberg, Ulrich
2016-01-01
Ultrahigh throughput screening (uHTS) plays an essential role in directed evolution for tailoring biocatalysts for industrial applications. Flow cytometry-based uHTS provides an efficient coverage of the generated protein sequence space by analysis of up to 107 events per hour. Cell-free enzyme production overcomes the challenge of diversity loss during the transformation of mutant libraries into expression hosts, enables directed evolution of toxic enzymes, and holds the promise to efficiently design enzymes of human or animal origin. The developed uHTS cell-free compartmentalization platform (InVitroFlow) is the first report in which a flow cytometry-based screened system has been combined with compartmentalized cell-free expression for directed cellulase enzyme evolution. InVitroFlow was validated by screening of a random cellulase mutant library employing a novel screening system (based on the substrate fluorescein-di-β-D-cellobioside), and yielded significantly improved cellulase variants (e.g. CelA2-H288F-M1 (N273D/H288F/N468S) with 13.3-fold increased specific activity (220.60 U/mg) compared to CelA2 wildtype: 16.57 U/mg). PMID:27184298
Institute of Scientific and Technical Information of China (English)
YOU Yancheng; BUANGA Bj(o)rn; HANNEMANN Volker; L(U)DEKE Heinrich
2012-01-01
The flows behind the base of a generic rocket,at both hypersonic and subsonic flow conditions,are numerically studied.The main concerns are addressed to the evaluation of turbulence models and the using of grid adaptation techniques.The investigation focuses on two configurations,related to hypersonic and subsonic experiments.The applicability tests of different turbulence models are conducted on the level of two-equation models calculating the steady state solution of the Reynolds-averaged Navier-Stokes(RANS) equations.All used models,the original Wilcox k-ω,the Menter shear-stress transport (SST) and the explicit algebraic Reynolds stress model(EARSM) formulation,predict an asymmetric base flow in both cases caused by the support of the models.A comparison with preliminary experimental results indicates a preference for the SST and EARSM results over the results from the older k-ω model.Sensitivity studies show no significant influence of the grid topology or the location of the laminar to turbulent transition on the base flow field,but a strong influence of even small angles of attack is reported from the related experiments.
Reedy, Todd Mitchell
An experimental investigation evaluating the effects of flow control on the near-wake downstream of a blunt-based axisymmetric body in supersonic flow has been conducted. To better understand and control the physical phenomena that govern these massively separated high-speed flows, this research examined both passive and active flow-control methodologies designed to alter the stability characteristics and structure of the near-wake. The passive control investigation consisted of inserting splitter plates into the recirculation region. The active control technique utilized energy deposition from multiple electric-arc plasma discharges placed around the base. The flow-control authority of both methodologies was evaluated with experimental diagnostics including particle image velocimetry, schlieren photography, surface flow visualization, pressure-sensitive paint, and discrete surface pressure measurements. Using a blowdown-type wind tunnel reconstructed specifically for these studies, baseline axisymmetric experiments without control were conducted for a nominal approach Mach number of 2.5. In addition to traditional base pressure measurements, mean velocity and turbulence quantities were acquired using two-component, planar particle image velocimetry. As a result, substantial insight was gained regarding the time-averaged and instantaneous near-wake flow fields. This dataset will supplement the previous benchmark point-wise laser Doppler velocimetry data of Herrin and Dutton (1994) for comparison with new computational predictive techniques. Next, experiments were conducted to study the effects of passive triangular splitter plates placed in the recirculation region behind a blunt-based axisymmetric body. By dividing the near-wake into 1/2, 1/3, and 1/4 cylindrical regions, the time-averaged base pressure distribution, time-series pressure fluctuations, and presumably the stability characteristics were altered. While the spatial base pressure distribution was
Lü, Xiao-jing; Li, Ning; Weng, Chun-sheng
2016-03-01
Compared with traditional sampling-based sensing method, absorption spectroscopy technology is well suitable for detonation flow diagnostics, since it can provide with us fast response, nonintrusive, sensitive solution for situ measurements of multiple flow-field parameters. The temperature and concentration test results are the average values along the laser path with traditional absorption spectroscopy technology, while the boundary of detonation flow external field is unknown and it changes all the time during the detonation engine works, traditional absorption spectroscopy technology is no longer suitable for detonation diagnostics. The trend of line strength with temperature varies with different absorption lines. By increasing the number of absorption lines in the test path, more information of the non-uniform flow field can be obtained. In this paper, based on multispectral absorption technology, the reconstructed model of detonation flow external field distribution was established according to the simulation results of space-time conservation element and solution element method, and a diagnostic method of detonation flow external field was given. The model deviation and calculation error of the least squares method adopted were studied by simulation, and the maximum concentration and temperature calculation error was 20.1% and 3.2%, respectively. Four absorption lines of H2O were chosen and detonation flow was scanned at the same time. The detonation external flow testing system was set up for the valveless gas-liquid continuous pulse detonation engine with the diameter of 80 mm. Through scanning H2O absorption lines with a high frequency of 10 kHz, the on-line detection of detonation external flow was realized by direct absorption method combined with time-division multiplexing technology, and the reconstruction of dynamic temperature distribution was realized as well for the first time, both verifying the feasibility of the test method. The test results
Experimental study on unsteady open channel flow and bedload transport based on a physical model
Cao, W.
2015-12-01
Flow in a nature river are usually unsteady, while nearly all the theories about bedload transport are on the basis of steady, uniform flow, and also with supposed equilibrium state of sediment transport. This is may be one of the main reasons why the bedload transport formulas are notoriously poor accuracy to predict the bedload. The aim of this research is to shed light on the effect of unsteadiness on the bedload transport based on experimental studies. The novel of this study is that the experiments were not carried out in a conventional flume but in a physical model, which are more similar to the actual river. On the other hand, in our experiments, multiple consecutive flood wave were reproduced in the physical model, and all the flow and sediment parameters are based on a large number of data obtained from many of identical flood waves. This method allow us to get more data for one flood, efficiently avoids the uncertainty of bedload rate only for one single flood wave, due to the stochastic fluctuation of the bedload transport. Three different flood waves were selected in the experiments. During each run of experiment, the water level of five different positions along the model were measured by ultrasonic water level gauge, flow velocity at the middle of the channel were measured by two dimensional electromagnetic current meter. Moreover, the bedload transport rate was measured by a unique automatic trap collecting and weighing system at the end of the physical model. The results shows that the celerity of flood wave propagate varies for different flow conditions. The velocity distribution was approximately accord with log-law profile during the entire rising and falling limb of flood. The bedload transport rate show intensity fluctuation in all the experiments, moreover, for different flood waves, the moment when the shear stress reaches its maximum value is not the exact moment when the sediment transport rate reaches its maximum value, which indicates
International Nuclear Information System (INIS)
To predict the behavior of air-water two-phase flows in a centrifugal pump impeller, a three-dimensional numerical method is proposed based on a bubbly flow model. If it is assumed that the mixtures are homogeneous bubbly flow containing fine bubbles compared with the characteristic length of the impeller channel, then the equations of motion of the mixtures are represented by those of liquid phase and its velocity is expressed as a potential for the quasi-harmonic equation. The equations are solved by use of the finite element method to obtain the velocities and pressures, and the equation of motion of an air bubble is integrated numerically on this flow field to obtain the void fraction. These calculations are repeated until the solutions converge. The results obtained show good agreement with experiments within the range of bubbly flow regime. (author)
Zhou, Gang; Davidson, Lars; Olsson, Erik
This paper presents computations of transonic aerodynamic flow simulations using a pressure-based Euler/Navier-Stokes solver. In this work emphasis is focused on the implementation of higher-order schemes such as QUICK, LUDS and MUSCL. A new scheme CHARM is proposed for convection approximation. Inviscid flow simulations are carried out for the airfoil NACA 0012. The CHARM scheme gives better resolution for the present inviscid case. The turbulent flow computations are carried out for the airfoil RAE 2822. Good results were obtained using QUICK scheme for mean motion equation combined with the MUSCL scheme for k and ɛ equations. No unphysical oscillations were observed. The results also show that the second-order and thir-dorder schemes yielded a comparable accuracy compared with the experimental data.
Video-based measurement and data analysis of traffic flow on urban expressways
Institute of Scientific and Technical Information of China (English)
Xian-Qing Zheng; Zheng Wu; Shi-Xiong Xu; Ming-Min Guo; Zhan-Xi Lin; Ying-Ying Zhang
2011-01-01
A new video-based measurement is proposed to collect and investigate traffic flow parameters.The output of the measurement is velocity-headway distance data pairs.Because density can be directly acquired by the reciprocal of headway distance, the data pairs have the advantage of better simultaneity than those from common detectors.By now,over 33 000 pairs of data have been collected from two road sections in the cities of Shanghai and Zhengzhou.Through analyzing the video files recording traffic movements on urban expressways, the following issues are studied: laws of vehicle velocity changing with headway distance, proportions of different driving behaviors in the traffic system, and characteristics of traffic flow in snowy days.The results show that the real road traffic is very complex, and factors such as location and climate need to be taken into consideration in the formation of traffic flow models.
Design criteria of a chemical reactor based on a chaotic flow
Tang, X Z
1998-01-01
We consider the design criteria of a chemical mixing device based on a chaotic flow, with an emphasis on the steady-state devices. The merit of a reactor, defined as the $Q$-factor, is related to the physical dimension of the device and the molecular diffusivity of the reactants through the local Lyapunov exponents of the flow. The local Lyapunov exponent can be calculated for any given flow field and it can also be measured in experimental situations. Easy-to-compute formulae are provided to estimate the $Q$-factor given either the exact spatial dependence of the local Lyapunov exponent or its probability distribution function. The requirements for optimization are made precise in the context of local Lyapunov exponents.
Wavelet-based adaptive numerical simulation of unsteady 3D flow around a bluff body
de Stefano, Giuliano; Vasilyev, Oleg
2012-11-01
The unsteady three-dimensional flow past a two-dimensional bluff body is numerically simulated using a wavelet-based method. The body is modeled by exploiting the Brinkman volume-penalization method, which results in modifying the governing equations with the addition of an appropriate forcing term inside the spatial region occupied by the obstacle. The volume-penalized incompressible Navier-Stokes equations are numerically solved by means of the adaptive wavelet collocation method, where the non-uniform spatial grid is dynamically adapted to the flow evolution. The combined approach is successfully applied to the simulation of vortex shedding flow behind a stationary prism with square cross-section. The computation is conducted at transitional Reynolds numbers, where fundamental unstable three-dimensional vortical structures exist, by well-predicting the unsteady forces arising from fluid-structure interaction.
Predicting commuter flows in spatial networks using a radiation model based on temporal ranges
Ren, Yihui; Wang, Pu; González, Marta C; Toroczkai, Zoltán
2014-01-01
Understanding network flows such as commuter traffic in large transportation networks is an ongoing challenge due to the complex nature of the transportation infrastructure and of human mobility. Here we show a first-principles based method for traffic prediction using a cost based generalization of the radiation model for human mobility, coupled with a cost-minimizing algorithm for efficient distribution of the mobility fluxes through the network. Using US census and highway traffic data we show that traffic can efficiently and accurately be computed from a range-limited, network betweenness type calculation. The model based on travel time costs captures the lognormal distribution of the traffic and attains a high Pearson correlation coefficient (0.75) when compared to real traffic. Due to its principled nature, this method can inform many applications related to human mobility driven flows in spatial networks, ranging from transportation, through urban planning to mitigation of the effects of catastrophic e...
Directory of Open Access Journals (Sweden)
Song Rui
2013-01-01
Full Text Available Accurate prediction and understanding of the disorder microstructures in the porous media contribute to acquiring the macroscopic physical properties such as conductivity, permeability, formation factor, elastic moduli etc. Based on the rock serial sectioning images of Berea sandstone acquired by the core scanning system developed by our research group, the reconstructed rock model is established in the Mimics software and the extracted pore network of the porous rock is accomplished by the self-programming software in C++ programming language based on the revised Medial axis based algorithm and the Maximal ball algorithm. Using a lattice Boltzmann method, the single and two C phase flow are accomplished. Both of the pore-scale networks and the seepage mechanism of the single- and two Cphase flow are identical with the benchmark experimental data.
Analytical method for softness abrasive flow field based on discrete phase model
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined,constituted restrained abrasive flow passage,and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage,realize micro cutting for passage wall,and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces,and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established,the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method,and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure,and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time,it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity,pressure and material removing rate. By tracking near-wall particles,it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement,so the feasibility of the SAFM method can be reaffirmed.
Recession-based hydrological models for estimating low flows in ungauged catchments in the Himalayas
Directory of Open Access Journals (Sweden)
H. G. Rees
2004-01-01
Full Text Available The Himalayan region of Nepal and northern India experiences hydrological extremes from monsoonal floods during July to September, when most of the annual precipitation falls, to periods of very low flows during the dry season (December to February. While the monsoon floods cause acute disasters such as loss of human life and property, mudslides and infrastructure damage, the lack of water during the dry season has a chronic impact on the lives of local people. The management of water resources in the region is hampered by relatively sparse hydrometerological networks and consequently, many resource assessments are required in catchments where no measurements exist. A hydrological model for estimating dry season flows in ungauged catchments, based on recession curve behaviour, has been developed to address this problem. Observed flows were fitted to a second order storage model to enable average annual recession behaviour to be examined. Regionalised models were developed, using a calibration set of 26 catchments, to predict three recession curve parameters: the storage constant; the initial recession flow and the start date of the recession. Relationships were identified between: the storage constant and catchment area; the initial recession flow and elevation (acting as a surrogate for rainfall; and the start date of the recession and geographic location. An independent set of 13 catchments was used to evaluate the robustness of the models. The regional models predicted the average volume of water in an annual recession period (1st of October to the 1st of February with an average error of 8%, while mid-January flows were predicted to within ±50% for 79% of the catchments in the data set. Keywords: Himalaya, recession curve, water resources, ungauged catchment, regionalisation, low flows
Janiga, Gábor; Daróczy, László; Berg, Philipp; Thévenin, Dominique; Skalej, Martin; Beuing, Oliver
2015-11-01
The optimal treatment of intracranial aneurysms using flow diverting devices is a fundamental issue for neuroradiologists as well as neurosurgeons. Due to highly irregular manifold aneurysm shapes and locations, the choice of the stent and the patient-specific deployment strategy can be a very difficult decision. To support the therapy planning, a new method is introduced that combines a three-dimensional CFD-based optimization with a realistic deployment of a virtual flow diverting stent for a given aneurysm. To demonstrate the feasibility of this method, it was applied to a patient-specific intracranial giant aneurysm that was successfully treated using a commercial flow diverter. Eight treatment scenarios with different local compressions were considered in a fully automated simulation loop. The impact on the corresponding blood flow behavior was evaluated qualitatively as well as quantitatively, and the optimal configuration for this specific case was identified. The virtual deployment of an uncompressed flow diverter reduced the inflow into the aneurysm by 24.4% compared to the untreated case. Depending on the positioning of the local stent compression below the ostium, blood flow reduction could vary between 27.3% and 33.4%. Therefore, a broad range of potential treatment outcomes was identified, illustrating the variability of a given flow diverter deployment in general. This method represents a proof of concept to automatically identify the optimal treatment for a patient in a virtual study under certain assumptions. Hence, it contributes to the improvement of virtual stenting for intracranial aneurysms and can support physicians during therapy planning in the future. PMID:26472308
Tóth, Ádám; Havril, Tímea; Simon, Szilvia; Galsa, Attila; Monteiro Santos, Fernando A.; Müller, Imre; Mádl-Szőnyi, Judit
2016-08-01
Groundwater flow, driven, controlled and determined by topography, geology and climate, is responsible for several natural surface manifestations and affected by anthropogenic processes. Therefore, flowing groundwater can be regarded as an environmental agent. Numerical simulation of groundwater flow could reveal the flow pattern and explain the observed features. In complex geologic framework, where the geologic-hydrogeologic knowledge is limited, the groundwater flow model could not be constructed based solely on borehole data, but geophysical information could aid the model building. The integrated model construction was presented via the case study of the Tihany Peninsula, Hungary, with the aims of understanding the background and occurrence of groundwater-related environmental phenomena, such as wetlands, surface water-groundwater interaction, slope instability, and revealing the potential effect of anthropogenic activity and climate change. The hydrogeologic model was prepared on the basis of the compiled archive geophysical database and the results of recently performed geophysical measurements complemented with geologic-hydrogeologic data. Derivation of different electrostratigraphic units, revealing fracturing and detecting tectonic elements was achieved by systematically combined electromagnetic geophysical methods. The deduced information can be used as model input for groundwater flow simulation concerning hydrostratigraphy, geometry and boundary conditions. The results of numerical modelling were interpreted on the basis of gravity-driven regional groundwater flow concept and validated by field mapping of groundwater-related phenomena. The 3D model clarified the hydraulic behaviour of the formations, revealed the subsurface hydraulic connection between groundwater and wetlands and displayed the groundwater discharge pattern, as well. The position of wetlands, their vegetation type, discharge features and induced landslides were explained as
Liquid-liquid extraction based on a new flow pattern: Two-fluid Taylor-Couette flow
Baier, Gretchen
The exploitation of flow instabilities that can occur in rotating flows is investigated as a new approach to liquid extraction. Two immiscible liquids are radially stratified by centrifugal force in the annulus between corotating coaxial cylinders. The inner cylinder is rotated above a critical speed to form Taylor vortices in one or both of the fluids. This flow pattern produces a relatively small amount interfacial surface area that is of highly active for interphase mass transfer. Continuous processing is also possible with the addition of countercurrent axial flow. The present study includes: (1)A review of aqueous- aqueous and reversed micelle extraction techniques, the commercially available centrifugal extractors, and one fluid Taylor-Couette flow and its variations. (2)A theoretical analysis to predict the onset of the two- fluid Taylor-Couette instability in the presence of countercurrent axial flow. (3)Theoretical predictions for interphase mass transfer using penetration theory and computational fluid dynamics. (4)The demonstration of two-fluid Taylor-Couette flow with countercurrent axial flow in the laboratory, including: (1) fluid mechanics studies to determine the onset of vortices, and (2) mass transfer studies to characterize intraphase and interphase mass transfer. The agreement between the experiments and theory is good for both the fluid mechanics and the mass transfer. Furthermore, the extraction performance is quite promising with the mass transfer coefficient approximately proportional to the vortex strength. Even higher extraction efficiencies should be obtainable with even larger relative rotation rates or cylinder modification to promote vortex formation. Besides two-fluid Taylor-Couette flow, other instabilities can also occur. With low viscosity fluids at low rotation rates, the ``barber pole'' pattern is observed experimentally and is believed to be a lingering gravitational effect. At high countercurrent axial flowrates, the linear
Gong, An; Gu, Shuang-Shuang; Wang, Jun; Sheng, Sheng; Wu, Fu-An
2015-10-01
A segmented flow containing a buffer-ionic liquid/solvent in a micro-channel reactor was applied to synthesize isoquercitrin by the hesperidinase-catalyzed selective hydrolysis of rutin, based on a novel system of reaction coupling with separation. Within the developed microchannel reactor with one T-shaped inlet and outlet, the maximum isoquercitrin yield (101.7 ± 2.6%) was achieved in 20 min at 30 °C and 4 μL/min. Compared with a continuous-flow reactor, reaction rate was increased 4-fold due to a glycine-sodium hydroxide:[Bmim][BF4]/glycerol triacetate (1:1, v/v) system that formed a slug flow in microchannel and significantly increased mass transfer rates. The mass transfer coefficient significantly increased and exhibited a linear relationship with the flow rate. Hesperidinase could be efficiently reused at least 5 times, without losing any activity. The bonding mechanism and secondary structure of hesperidinase indicated that hesperidinase had a greater affinity to rutin at a production rate of 4 μL/min in this segmented flow microreactor. PMID:26163760
3D MHD free surface fluid flow simulation based on magnetic-field induction equations
International Nuclear Information System (INIS)
The purpose of this paper is to present our recent efforts on 3D MHD model development and our results based on the technique derived from induced-magnetic-field equations. Two important features are utilized in our numerical method to obtain convergent solutions. First, a penalty factor is introduced in order to force the local divergence free condition of the magnetic fields. The second is that we extend the insulating wall thickness to ensure that the induced magnetic field at its boundaries is null. These simulation results for lithium film free surface flows under NSTX outboard mid-plane magnetic field configurations have shown that 3D MHD effects from a surface normal field gradient cause return currents to interact with surface normal fields and produce unfavorable MHD forces. This leads to a substantial change in flow pattern and a reduction in flow velocity, with most of the flow spilling over one side of the chute. These critical phenomena can not be revealed by 2D models. Additionally, a design which overcomes these undesired flow characteristics is obtained
A wireless flow sensor based on magnetic higher-order harmonic fields
International Nuclear Information System (INIS)
The design and fabrication of a wireless, passive flow sensor based on changes in magnetic higher-order harmonic fields is described. The sensor consisted of a flow channel, a permanent magnetic strip (biasing element) and a magnetically soft ferromagnetic strip (sensing element). The biasing element was attached on the channel's wall in parallel to the flow direction, while the sensing element was applied on the opposite wall at a small angle to the flow direction. Flowing water in the channel created a pressure on the sensing element's surface, causing a deflection that varied its separation distance from the biasing element. The change in the separation distance in turn altered the biasing field experienced by the sensing element, causing a shift in its higher-order harmonic fields that could be measured remotely through a magnetic coil. The novelty of this sensor is its wireless, passive nature, which is ideal for applications where wire connections are prohibited. In addition, this sensor can be used on a disposable basis due to its simple design and relatively low material cost
Reliability-based assessment of flow assurance of hot waxy crude pipelines
Energy Technology Data Exchange (ETDEWEB)
Jinjun, Zhang; Wenke, Zhang; Jianlin, Ding; Bo, Yu [China University of Petroleum - Beijing (CUPB), Beijing (China)
2009-07-01
Waxy crude is characterized by its high pour point. Pipeline blockage may occur after prolonged shutdown of a pipeline due to crude oil gelation. Another flow assurance problem is the instable operation at a flow rate below the lowest allowable operation flow rate which is dependent on heat transfer of the pipeline and the viscosity vs. temperature relation of the crude pumped. Besides, for pipelines with thick wax deposition layer, massive depletion of wax deposit in some cases such as pipeline restart at high expelling pressure may also result in blockage of the pipeline, and the pig may be jammed during pigging as a result of thick wax deposition. Conventionally, assessment of these risks has been made by using the deterministic approach. However, many related physical quantities are subject to uncertainty and contribute to reliability of flow assurance. Therefore, the probabilistic approach is suggested and a framework of reliability based assessment of flow assurance of waxy crude pipelines is proposed in this paper. Discussions are also made on the limit state functions and target safety level. In the future study, development of an efficient and robust stochastic-numerical method is crucial. (author)
DEFF Research Database (Denmark)
Noeth, Nadine-Nicole; Keller, Stephan Sylvest; Boisen, Anja
2014-01-01
For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different...
Directory of Open Access Journals (Sweden)
Nadine Noeth
2013-12-01
Full Text Available For devices such as bio-/chemical sensors in microfluidic systems, flow fluctuations result in noise in the sensor output. Here, we demonstrate in-line monitoring of flow fluctuations with a cantilever-like sensor integrated in a microfluidic channel. The cantilevers are fabricated in different materials (SU-8 and SiN and with different thicknesses. The integration of arrays of holes with different hole size and number of holes allows the modification of device sensitivity, theoretical detection limit and measurement range. For an average flow in the microliter range, the cantilever deflection is directly proportional to the flow rate fluctuations in the microfluidic channel. The SiN cantilevers show a detection limit below 1 nL/min and the thinnest SU-8 cantilevers a detection limit below 5 nL/min. Finally, the sensor is applied for in-line monitoring of flow fluctuations generated by external pumps connected to the microfluidic system.
Analysis of Base-Case Particle Tracking Results of the Base-Case Flow Fields (ID:U0160)
International Nuclear Information System (INIS)
The purpose of this analysis is to provide insight into the unsaturated-zone (UZ) subsystem performance through particle tracking analyses of the base-case flow fields. The particle tracking analyses will not be used directly in total-system performance-assessment (TSPA) calculations per se. The objective of this activity is to evaluate the transport of radionuclides through the unsaturated zone and to determine how different system parameters such as matrix diffusion, sorption, water-table rise, and perched water influence the transport to the water table. Plots will be generated to determine normalized cumulative breakthrough curves for selected radionuclides. The scope of this work is limited to the particle tracking analyses of ''base-case'' flow fields that are to be used by the code FEHM (Finite Element Heat and Mass; Zyvoloski 1997) for particle tracking simulations in ''Total System Performance Assessment-Site Recommendation Report'' (TSPA-SR)
Analysis of Base-Case Particle Tracking Results of the Base-Case Flow Fields (ID:U0160)
Energy Technology Data Exchange (ETDEWEB)
C.K. Ho
2000-01-19
The purpose of this analysis is to provide insight into the unsaturated-zone (UZ) subsystem performance through particle tracking analyses of the base-case flow fields. The particle tracking analyses will not be used directly in total-system performance-assessment (TSPA) calculations per se. The objective of this activity is to evaluate the transport of radionuclides through the unsaturated zone and to determine how different system parameters such as matrix diffusion, sorption, water-table rise, and perched water influence the transport to the water table. Plots will be generated to determine normalized cumulative breakthrough curves for selected radionuclides. The scope of this work is limited to the particle tracking analyses of ''base-case'' flow fields that are to be used by the code FEHM (Finite Element Heat and Mass; Zyvoloski 1997) for particle tracking simulations in ''Total System Performance Assessment-Site Recommendation Report'' (TSPA-SR).
Liu, C Q
2008-01-01
In this paper, an improved FRF-based substructure synthesis method combined with power flow analysis is presented and is used for performing a vehicle axle noise analysis. The major transfer paths of axle noise transmitted from chassis to vehicle body are identified and ranked based on power flows transmitted through bushings between the chassis and body. To calculate the power flows, it is necessary to know the reaction forces and the vibrations at the bushing locations on the body side. To ...
Open critical area model and extraction algorithm based on the net flow-axis
International Nuclear Information System (INIS)
In the integrated circuit manufacturing process, the critical area extraction is a bottleneck to the layout optimization and the integrated circuit yield estimation. In this paper, we study the problem that the missing material defects may result in the open circuit fault. Combining the mathematical morphology theory, we present a new computation model and a novel extraction algorithm for the open critical area based on the net flow-axis. Firstly, we find the net flow-axis for different nets. Then, the net flow-edges based on the net flow-axis are obtained. Finally, we can extract the open critical area by the mathematical morphology. Compared with the existing methods, the nets need not to divide into the horizontal nets and the vertical nets, and the experimental results show that our model and algorithm can accurately extract the size of the open critical area and obtain the location information of the open circuit critical area. (interdisciplinary physics and related areas of science and technology)
Study of Flow Characteristics of Tundish Based on Digital Image Velocimetry Technique
Huang, Jun; Zhang, Yongjie; Zhang, Yazhu; Zhang, Yakun; Ye, Xin; Wang, Baofeng
2016-07-01
A synthetic hydraulic simulation platform of continuous casting was established based on the digital image velocimetry technique, which was an effective method to obtain flow characteristics. The full physical models of ultrathick slab continuous casting tundish and reduced scale six-stand T-type tundish were simulated before industrial production to assess the effectiveness of these devices and to optimize the tundish design with external heating. The flow and residence time distribution curves obtained by noncontact measurement were investigated based on the digital image technology. The random velocity fluctuations were consequences of the swirl or eddies generated by turbulent flow from the inlet to outlet section. These swirl or eddies tended to be a large circle in the middle of the tundish and small in the vicinity of the wall. The geometric parameters of the tundish were one of the most important factors for tundish design, although the flow control device was important. As a whole, the results derived from physical modeling were in good agreement with those obtained from numerical simulation.
Estimation of Reversed Flow in Long Pipeline Based on Axial Vibration Model of Dense Paste
Directory of Open Access Journals (Sweden)
Fuyan Lyu
2016-01-01
Full Text Available Intense axial vibration of the paste and the reversed flow make damage to the transportation system and lag the transport progress. This paper analyzed the axial vibration of the paste by building the vibration model according to the working situations of the system. The amount of the reversed flow share is then estimated based on the formed axial vibration model. The estimation of the reversed flow is carried out by counting the amount of the decompressed paste in certain time, which is being relative to the displacement in a single process of the vibration in numerical. The estimation of the reversed flow share of coal slime paste under certain transportation conditions was given and compared with the result based on the wave velocity method. It is evident that the introduction of axial vibration model into the study of the pipeline transportation system is feasible and reasonable, which also supplements the theoretical foundation for the analysis of dense paste vibrations in pipeline transportation system and its impacts on the system.
Simulation of bidirectional pedestrian flow in transfer station corridor based on multi forces
Institute of Scientific and Technical Information of China (English)
周雪梅; 纪翔峰; 黄凰; 杨晓光
2014-01-01
A good understanding of pedestrian movement in the transfer corridor is vital for the planning and design of the station, especially for efficiency and safety.A multi-force vector grid model was presented to simulate the movement of bidirectional pedestrian flow based on cellular automata and forces between pedestrians. The model improves rule-based characteristics of cellular automata, details forces between pedestrians and solves pedestrian collisions by a several-step updating method to simulate pedestrian movements. Two general scenarios in corridor were simulated. One is bidirectional pedestrian flow simulation with isolation facility, and the other is bidirectional pedestrian flow simulation without isolation facility, where there exists disturbance in the middle. Through simulation, some facts can be seen that pedestrians in the case with isolation facility have the largest speed and pedestrians in the case without isolation facility have the smallest speed; pedestrians in the case of unidirectional flow have the largest volume and pedestrians in the case of without isolation facility have the smallest volume.
Directory of Open Access Journals (Sweden)
Zhi-jian Wang
2013-01-01
Full Text Available The three-dimensional flow physical model of any stage of the 20BZ4 multistage centrifugal pump is built which includes inlet region, impeller flow region, guide-vane flow region and exit region. The three-dimensional unsteady turbulent flow numerical model is created based on Navier-Stoke solver and standard k-ε turbulent equations. The method of multireference frame (MRF and SIMPLE algorithm are used to simulate the flow in multistage centrifugal pump based on FLUENT software. The distributions of relative velocity, absolute velocity, static pressure, and total pressure in guide vanes and impellers under design condition are analyzed. The simulation results show that the flow in impeller is mostly uniform, without eddy, backflow, and separation flow, and jet-wake phenomenon appears only along individual blades. There is secondary flow at blade end and exit of guide vane. Due to the different blade numbers of guide vane and impeller, the total pressure distribution is asymmetric. This paper also simulates the flow under different working conditions to predict the hydraulic performances of centrifugal pump and external characteristics including flow-lift, flow-shaft power, and flow-efficiency are attained. The simulation results are compared with the experimental results, and because of the mechanical losses and volume loss ignored, there is a little difference between them.
Directory of Open Access Journals (Sweden)
Hailong Xu
2016-01-01
Full Text Available Rotated blades are key mechanical components in turbomachinery and high cycle fatigues often induce blade cracks. Accurate detection of small cracks in rotated blades is very significant for safety, reliability, and availability. In nature, a breathing crack model is fit for a small crack in a rotated blade rather than other models. However, traditional vibration displacements-based methods are less sensitive to nonlinear characteristics due to small breathing cracks. In order to solve this problem, vibration power flow analysis (VPFA is proposed to analyze nonlinear dynamic behaviors of rotated blades with small breathing cracks in this paper. Firstly, local flexibility due to a crack is derived and then time-varying dynamic model of the rotated blade with a small breathing crack is built. Based on it, the corresponding vibration power flow model is presented. Finally, VPFA-based numerical simulations are done to validate nonlinear behaviors of the cracked blade. The results demonstrate that nonlinear behaviors of a crack can be enhanced by power flow analysis and VPFA is more sensitive to a small breathing crack than displacements-based vibration analysis. Bifurcations will occur due to breathing cracks and subharmonic resonance factors can be defined to identify breathing cracks. Thus the proposed method can provide a promising way for detecting and predicting small breathing cracks in rotated blades.
Institute of Scientific and Technical Information of China (English)
NIU Junchuan; GE Peiqi; HOU Cuirong; LIM C W; SONG Kongjie
2009-01-01
For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flexible bases of laminated beams. In the model, the laminated beam bases are simulated by the first-order shear deformation laminated plate theory, which is relatively simple and economic but accurate in predicting the vibration solutions of flexible isolation systems with laminated beam bases in comparison with classical laminated beam theories and higher order theories. On the basis of the presented model, substructure technique and variational principle are employed to obtain the governing equation of the isolation system and the power flow solution. Then, the vibration characteristics of the flexible isolation systems with laminated bases are investigated. Several numerical examples are given to show the validity and efficiency of the presented model. It is concluded that the presented model is the extension of the classical one and it can obtain more accurate power flow solutions.
A route-based decomposition for the Multi-Commodity k-splittable Maximum Flow Problem
DEFF Research Database (Denmark)
Gamst, Mette
2012-01-01
The Multi-Commodity k-splittable Maximum Flow Problem routes flow through a capacitated graph such that each commodity uses at most k paths and such that the total amount of routedflow is maximized. This paper proposes a branch-and-price algorithm based on a route-based Dantzig-Wolfe decomposition...
Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Base-Flow Index
U.S. Geological Survey, Department of the Interior — This tabular data set represents the mean base-flow index expressed as a percent, compiled for every catchment in NHDPlus for the conterminous United States. Base...
Hazards Assessment of Regional Debris Flows Based on Geographic Information Science
Institute of Scientific and Technical Information of China (English)
JIANG Xiaobo; GUI Peng
2007-01-01
Supported by the spatial analysis feature of geographic information science and assessment model of regional debris flows, hazards degrees of the debris flows in the Upper Yangtze River Watershed (UYRW) are divided into five grades based on grid cell. The area of no danger, light danger, medium danger, severe danger and extreme severe danger regions respectively are 278 000, 288 000, 217 000, 127 000, 15 000 km2. Furthermore, the counties in the UYRW are classified into four classes based on the hazards degrees in each county. The number of severe danger, medium danger, light danger and no danger counties respectively are 49, 82, 77 and 105. The assessment results will be provided for the hazards forecasting and mitigation in the UYRW and ongoing regionalization of Main Function Regions in China as data and technique framework.
Trajectory Analysis of Fuel Injection into Supersonic Cross Flow Based on Schlieren Method
Institute of Scientific and Technical Information of China (English)
YANG Hui; LI Feng; SUN Baigang
2012-01-01
Trajectory analysis of fuel injection into supersonic cross flow is studied in this paper.A directly-connected wind tunnel is constructed to provide stable supersonic freestream.Based on the test rig,the schlieren system is established to reveal the fuel injection process visually.Subsequently,the method of quantitative schlieren is adopted to obtain data of both fuel/air interface and bow shock with the aid of Photoshop and Origin.Finally,the mechanism based on two influential factors of fuel injection angle and fuel injection driven pressure,is researched by vector analysis.A dimensionless model is deduced and analyzed.The curve fitting result is achieved.The relationship between the data and the two influential factors is established.The results provide not only the quantitative characteristics of the fuel injection in supersonic cross flow but also the valuable reference for the future computational simulation.
Petri Nets Based Modelling of Control Flow for Memory-Aid Interactive Programs in Telemedicine
Khoromskaia, V K
2004-01-01
Petri Nets (PN) based modelling of the control flow for the interactive memory assistance programs designed for personal pocket computers and having special requirements for robustness is considered. The proposed concept allows one to elaborate the programs which can give users a variety of possibilities for a day-time planning in the presence of environmental and time restrictions. First, a PN model for a known simple algorithm is constructed and analyzed using the corresponding state equations and incidence matrix. Then a PN graph for a complicated algorithm with overlapping actions and choice possibilities is designed, supplemented by an example of its analysis. Dynamic behaviour of this graph is tested by tracing of all possible paths of the flow of control using the PN simulator. It is shown that PN based modelling provides reliably predictable performance of interactive algorithms with branched structures and concurrency requirements.
MEDUSA - An overset grid flow solver for network-based parallel computer systems
Smith, Merritt H.; Pallis, Jani M.
1993-01-01
Continuing improvement in processing speed has made it feasible to solve the Reynolds-Averaged Navier-Stokes equations for simple three-dimensional flows on advanced workstations. Combining multiple workstations into a network-based heterogeneous parallel computer allows the application of programming principles learned on MIMD (Multiple Instruction Multiple Data) distributed memory parallel computers to the solution of larger problems. An overset-grid flow solution code has been developed which uses a cluster of workstations as a network-based parallel computer. Inter-process communication is provided by the Parallel Virtual Machine (PVM) software. Solution speed equivalent to one-third of a Cray-YMP processor has been achieved from a cluster of nine commonly used engineering workstation processors. Load imbalance and communication overhead are the principal impediments to parallel efficiency in this application.
Rambabu, C.; Obulesu, Y. P.; Saibabu, Ch.
2014-07-01
This work presents particle swarm optimization (PSO) based method to solve the optimal power flow in power systems incorporating flexible AC transmission systems controllers such as thyristor controlled phase shifter, thyristor controlled series compensator and unified power flow controller for security enhancement under single network contingencies. A fuzzy contingency ranking method is used in this paper and observed that it effectively eliminates the masking effect when compared with other methods of contingency ranking. The fuzzy based network composite overall severity index is used as an objective to be minimized to improve the security of the power system. The proposed optimization process with PSO is presented with case study example using IEEE 30-bus test system to demonstrate its applicability. The results are presented to show the feasibility and potential of this new approach.
Development of a transient boiling transition analysis method based on a film flow model
International Nuclear Information System (INIS)
A new single-channel, transient boiling transition (BT) prediction method based on a film flow model has been developed for a core thermal-hydraulic code. This method could predict onset and location of dryout and rewetting under transient conditions mechanically based on the dryout criterion and with consideration of the spacer effect. The developed method was applied to analysis of steady-state and transient BT experiments using BWR fuel bundle mock-ups for verification. Comparisons between calculated results and experimental data showed that the developed method tended to predict occurrence of rewetting earlier, however, onset time of BT and maximum rod surface temperature were well predicted within 0.6 s and 20degC, respectively. Moreover, it was confirmed that consideration of the spacer effect on liquid film flow rate on the rod surface was required to predict dryout phenomena accurately under transient conditions. (author)
Plume Interaction and Base Flow Analysis of a Twin Engine Flight Vehicle
Chandra Murty, Mamidi Sri Rama; Chakraborty, Debasis
2016-06-01
3D RANS simulations are performed to study the multi jet interactions of a twin engine gimbal configuration of an aerospace vehicle at different time instants. Simulations captured all the essential features of the flow field and interaction between the neighboring jets did not occur because of low altitudes and moderate under-expansion of the jets considered in the simulations. For higher gimbal angle, two jets were the closest but still did not interact. Detail exploration of the downstream flow field revealed that the distinct features of the jets are retained at the farthest downstream locations; although the pressure field reached the uniformity. Average base pressure ratios for the three different time instances are 0.91, 0.547 and 0.522 and maximum base temperature is of the order 800 K.
Yoshida, Hiroaki
2016-01-01
In this paper we investigate the hydrodynamic permeance of water through graphene-based membranes, inspired by recent experimental findings on graphene-oxide membranes. We consider the flow across multiple graphene layers having nanoslits in a staggered alignment, with an inter-layer distance ranging from sub- nanometer to a few nanometers. We compare results for the permeability obtained by means of molecular dynamics simulations to continuum predictions obtained by using the lattice Boltzmann calculations and hydrodynamic modelization. This highlights that, in spite of extreme confinement, the permeability across the graphene-based membrane is quantitatively predicted on the basis of a continuum expression, taking properly into account entrance and slippage effects of the confined water flow. Our predictions refute the breakdown of hydrodynamics at small scales in these membrane systems. They constitute a benchmark to which we compare published experimental data.
Survey on Parameters of Fingerprint Classification Methods Based On Algorithmic Flow
Directory of Open Access Journals (Sweden)
Dimple Parekh
2011-09-01
Full Text Available Classification refers to assigning a given fingerprint to one of the existing classes already recognized inthe literature. A search over all the records in the database takes a long time, so the goal is to reduce thesize of the search space by choosing an appropriate subset of database for search. Classifying afingerprint images is a very difficult pattern recognition problem, due to the minimal interclassvariability and maximal intraclass variability. This paper presents a sequence flow diagram which willhelp in developing the clarity on designing algorithm for classification based on various parametersextracted from the fingerprint image. It discusses in brief the ways in which the parameters are extractedfrom the image. Existing fingerprint classification approaches are based on these parameters as inputfor classifying the image. Parameters like orientation map, singular points, spurious singular points,ridge flow, transforms and hybrid feature are discussed in the paper.
A Rate-Based Flow Control Mechanism for AvoidingCongestion
Institute of Scientific and Technical Information of China (English)
张孝林; 王宇宏; 吴介一
2002-01-01
The rate-based flow control mechanisms for the Available Bit Rate (ABR) service are used to share the available bandwidth of a bottleneck switch connected to a bottleneck link fairly and reasonably among many competitive users, and to maintain the buffer queue length of the switch at a desired level in order to avoid congestion in Asynchronous Transfer Mode (ATM) networks. In this paper, a control theoretic approach that uses a DeadbeatResponse (DR) controller to the design of a rate-based flow control mechanism is presented.The mechanism has a simple structure and is robust in the sense that its stability is not sensitive to the change of the number of active Virtual Connections (VCs). Simulation results show that this mechanism not only ensures fair share of the bandwidth for all active VCs regardless of the number of hops they traverse but also has the advantages of fast convergence, no oscillation,and high link bandwidth utilization.
Discrete Adjoint-Based Design for Unsteady Turbulent Flows On Dynamic Overset Unstructured Grids
Nielsen, Eric J.; Diskin, Boris
2012-01-01
A discrete adjoint-based design methodology for unsteady turbulent flows on three-dimensional dynamic overset unstructured grids is formulated, implemented, and verified. The methodology supports both compressible and incompressible flows and is amenable to massively parallel computing environments. The approach provides a general framework for performing highly efficient and discretely consistent sensitivity analysis for problems involving arbitrary combinations of overset unstructured grids which may be static, undergoing rigid or deforming motions, or any combination thereof. General parent-child motions are also accommodated, and the accuracy of the implementation is established using an independent verification based on a complex-variable approach. The methodology is used to demonstrate aerodynamic optimizations of a wind turbine geometry, a biologically-inspired flapping wing, and a complex helicopter configuration subject to trimming constraints. The objective function for each problem is successfully reduced and all specified constraints are satisfied.
Coded illumination for motion-blur free imaging of cells on cell-phone based imaging flow cytometer
Saxena, Manish; Gorthi, Sai Siva
2014-10-01
Cell-phone based imaging flow cytometry can be realized by flowing cells through the microfluidic devices, and capturing their images with an optically enhanced camera of the cell-phone. Throughput in flow cytometers is usually enhanced by increasing the flow rate of cells. However, maximum frame rate of camera system limits the achievable flow rate. Beyond this, the images become highly blurred due to motion-smear. We propose to address this issue with coded illumination, which enables recovery of high-fidelity images of cells far beyond their motion-blur limit. This paper presents simulation results of deblurring the synthetically generated cell/bead images under such coded illumination.
Demirer, R Murat; Özerdem, Mehmet Siraç; Bayrak, Coskun; Mendi, Engin
2013-12-01
Analysis of directional information flow patterns among different regions of the brain is important for investigating the relation between ECoG (electrocorticographic) and mental activity. The objective is to study and evaluate the information flow activity at different frequencies in the primary motor cortex. We employed Granger causality for capturing the future state of the propagation path and direction between recording electrode sites on the cerebral cortex. A grid covered the right motor cortex completely due to its size (approx. 8 cm×8 cm) but grid area extends to the surrounding cortex areas. During the experiment, a subject was asked to imagine performing two activities: movement of the left small finger and/or movement of the tongue. The time series of the electrical brain activity was recorded during these trials using an 8×8 (0.016-300 Hz band with) ECoG platinum electrode grid, which was placed on the contralateral (right) motor cortex. For detection of information flow activity and communication frequencies among the electrodes, we have proposed a method based on following steps: (i) calculation of analytical time series such as amplitude and phase difference acquired from Hilbert transformation, (ii) selection of frequency having highest interdependence for the electrode pairs for the concerned time series over a sliding window in which we assumed time series were stationary, (iii) calculation of Granger causality values for each pair with selected frequency. The information flow (causal influence) activity and communication frequencies between the electrodes in grid were determined and shown successfully. It is supposed that information flow activity and communication frequencies between the electrodes in the grid are approximately the same for the same pattern. The successful employment of Granger causality and Hilbert transformation for the detection of the propagation path and direction of each component of ECoG among different sub
Web-Based Predictive Analytics to Improve Patient Flow in the Emergency Department
Buckler, David L.
2012-01-01
The Emergency Department (ED) simulation project was established to demonstrate how requirements-driven analysis and process simulation can help improve the quality of patient care for the Veterans Health Administration's (VHA) Veterans Affairs Medical Centers (VAMC). This project developed a web-based simulation prototype of patient flow in EDs, validated the performance of the simulation against operational data, and documented IT requirements for the ED simulation.
Chiu, Megan Z; Linnes, Jacqueline
2015-01-01
Paper-based point-of-care (POC) diagnostics is a growing field in global health due to the extreme portability, accuracy, affordability, and ease of use of these tests. Advancements in recent years have led to more accurate detection and improved functionality using multistep molecular diagnostics. Many such assays utilize lateral flow detection strips for visualization of diagnostic results by eye, which limits the results to qualitative Yes/No readouts. This project focused on combining rec...
High temperature ultrasonic gas flow sensor based on lead free piezoelectric material
Krsmanovic, Dalibor
2011-01-01
The review of current technologies for measurement of gas velocity in stack flow applications is undertaken and it is shown that the ultrasonic time-of-flight method is the most suitable and offers a number of advantages over alternatives. Weakness of current piezoelectric based transducers are identified as the inability to operate at temperatures above 400 ?C due to limitation of piezoelectric materials used, and a case for development of an alternative high temperature material is put forw...
The importance of biotic entrainment for base flow fluvial sediment transport
Rice, Stephen P.; Johnson, Matthew F.; Mathers, Kate; Reeds, Jake; Extence, Chris
2016-05-01
Sediment transport is regarded as an abiotic process driven by geophysical energy, but zoogeomorphological activity indicates that biological energy can also fuel sediment movements. It is therefore prudent to measure the contribution that biota make to sediment transport, but comparisons of abiotic and biotic sediment fluxes are rare. For a stream in the UK, the contribution of crayfish bioturbation to suspended sediment flux was compared with the amount of sediment moved by hydraulic forcing. During base flow periods, biotic fluxes can be isolated because nocturnal crayfish activity drives diel turbidity cycles, such that nighttime increases above daytime lows are attributable to sediment suspension by crayfish. On average, crayfish bioturbation contributed at least 32% (474 kg) to monthly base flow suspended sediment loads; this biotic surcharge added between 5.1 and 16.1 t (0.21 to 0.66 t km-2 yr-1) to the annual sediment yield. As anticipated, most sediment was moved by hydraulic forcing during floods and the biotic contribution from baseflow periods represented between 0.46 and 1.46% of the annual load. Crayfish activity is nonetheless an important impact during baseflow periods and the measured annual contribution may be a conservative estimate because of unusually prolonged flooding during the measurement period. In addition to direct sediment entrainment by bioturbation, crayfish burrowing supplies sediment to the channel for mobilization during floods so that the total biotic effect of crayfish is potentially greater than documented in this study. These results suggest that in rivers, during base flow periods, bioturbation can entrain significant quantities of fine sediment into suspension with implications for the aquatic ecosystem and base flow sediment fluxes. Energy from life rather than from elevation can make significant contributions to sediment fluxes.
Determination of Ciprofloxacin by Flow Injection Analysis Based on Chemiluminescence System
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A novel flow injection chemiluminescence (CL) method for the determination of ciprofloxacin (CPLX) was reported. The proposed method is based on luminescence produced by KMnO4-Na2S2O4-Tb3+-CPLX chemiluminescence (CL) system. The effects of some critical experimental conditions were discussed and the optimization of working condithe recoveries of real sample analyses were in the range from 110 ± 4 to 104 ± 4.
Reasoning About Information Flow Security of Separation Kernels with Channel-based Communication
Zhao, Yongwang; Sann, David; Zhang, Fuyuan; Liu, Yang
2015-01-01
Assurance of information flow security by formal methods is mandated in security certification of separation kernels. As an industrial standard for separation kernels, ARINC 653 has been complied with by mainstream separation kernels. Security of functionalities defined in ARINC 653 is thus very important for the development and certification of separation kernels. This paper presents the first effort to formally specify and verify separation kernels with ARINC 653 channel-based communication...
Transient Stability Constrained Optimal Power Flow Using Teaching Learning-Based Optimization
Aparajita Mukherjee; Sourav Paul; Provas Kumar Roy
2014-01-01
Transient stability constrained optimal power flow (TSC-OPF) is a non-linear optimization problem which is not easy to deal directly because of its huge dimension. In order to solve the TSC-OPF problem efficiently, a relatively new optimization technique named teaching learning based optimization (TLBO) is proposed in this paper. TLBO algorithm simulates the teachingâ€“learning phenomenon of a classroom to solve multi-dimensional, linear and nonlinear problems with appreciable efficiency. Lik...
Reconstruction of tau decays based on particle flow techniques at ATLAS
International Nuclear Information System (INIS)
The reconstruction of the substructure of tau decays can improve the tau energy resolution and is important for various measurements involving tau polarization, such as the spin-parity state of the newly discovered Boson in the tau decay channel. A tau reconstruction algorithm for ATLAS based on particle flow is scheduled to be ready in 2013. This presentation introduces ongoing efforts and compares possible implementations.
Control Flow Graph Based Multiclass Malware Detection Using Bi-normal Separation
Akshay Kapoor; Sunita Dhavale
2016-01-01
Control flow graphs (CFG) and OpCodes extracted from disassembled executable files are widely used for malware detection. Most of the research in static analysis is focused on binary class malware detection which only classifies an executable as benign or malware. To overcome this issue, CFG based multiclass malware detection system that automatically classifies the malware into their respective families is proposed. The use Bi-normal separation (BNS) as a feature scoring metric. Experimental...
Simulation-Based Planning and Control of Transport Flows in Port Logistic Systems
Antonio Diogo Passos Lima; Frederico Werner de Mascarenhas; Enzo Morosini Frazzon
2015-01-01
In highly dynamic and uncertain transport conditions, transport transit time has to be continuously monitored so that the service level is ensured at a proper cost. The aim of this research is to propose and to test a procedure which allows an agile planning and control of transport flows in port logistic systems. The procedure couples an agent-based simulation and a queueing theory model. In this paper, the transport scheduling performed by an agent at the intermodal terminal was taken into ...
Virtual water flows in the EU27: A consumption-based approach
Serrano, Ana; Guan, Dabo; Duarte, Rosa; Paavola, Jouni
2016-01-01
The use of water resources has traditionally been studied by accounting for the volume of water removed from sources for specific uses. This approach focuses on surface and groundwater only and it ignores that international trade of products with substantial amounts of embodied water can have an impact on domestic water resources. Using current economic and environmental data, we conduct a consumption-based assessment of virtual water flows in the European Union (EU27). We find that the total...
Xuan Wu; Bo Yu(Brookhaven National Lab); Yi Wang
2013-01-01
Direct numerical simulation has been performed to study a polymer drag-reducing channel flow by using a discrete-element model. And then, wavelet analyses are employed to investigate the multiresolution characteristics of velocity components based on DNS data. Wavelet decomposition is applied to decompose velocity fluctuation time series into ten different frequency components including approximate component and detailed components, which show more regular intermittency and burst events in dr...
Optimization-based islanding of power networks using piecewise linear AC power flow
Trodden, Paul; Bukhsh, Waqquas; Grothey, Andreas; McKinnon, Kenneth
2013-01-01
In this paper, a flexible optimization-based framework for intentional islanding is presented. The decision is made of which transmission lines to switch in order to split the network while minimizing disruption, the amount of load shed, or grouping coherent generators. The approach uses a piecewise linear model of AC power flow, which allows the voltage and reactive power to be considered directly when designing the islands. Demonstrations on standard test networks show thatsolution of the p...
Optimization-based Islanding of Power Networks using Piecewise Linear AC Power Flow
Trodden, P. A.; Bukhsh, W. A.; Grothey, A.; McKinnon, K. I. M.
2013-01-01
In this paper, a flexible optimization-based framework for intentional islanding is presented. The decision is made of which transmission lines to switch in order to split the network while minimizing disruption, the amount of load shed, or grouping coherent generators. The approach uses a piecewise linear model of AC power flow, which allows the voltage and reactive power to be considered directly when designing the islands. Demonstrations on standard test networks show that solution of the ...
Flatness-based control of open-channel flow in an irrigation canal using SCADA
Rabbani, T.; Munier, S.; Dorchies, D.; Malaterre, P.O.; Bayen, A.; Litrico, X.
2009-01-01
Open channels are used to distribute water to large irrigated areas. In these systems, ensuring timely water delivery is essential to reduce operational water losses. This article derives a method for open-loop control of open channel flow, based on the Hayami model, a parabolic partial differential equation resulting from a simplification of the Saint-Venant equations. The open-loop control is represented as infinite series using differential flatness. Experimental results show the effective...
Design and application of a flow cell for carbon-film based electrochemical enzyme biosensors
Barsan, Madalina M.; Klincar, Janja; Batic, Martin; Christopher M. A. Brett
2007-01-01
A flow cell has been designed for use with an electrochemical enzyme biosensor, based on low-cost carbon-film electrodes. Three types of mediators were used: cobalt and copper hexacyanoferrates and poly(neutral red) (PNR), covered with glucose oxidase (GOx) immobilised by cross-linking with glutaraldehyde in the presence of bovine serum albumin or inside a oxysilane sol-gel network. Mixtures of sol-gel precursors were made from 3-aminopropyl-triethoxysilane (APTOS) together with methyltrimeth...
Magnússon, Sindri; Chathuranga Weeraddana, Pradeep; Fischione, Carlo
2014-01-01
The optimal power flow (OPF) problem, which plays a central role in operating electrical networks is considered. The problem is nonconvex and is in fact NP hard. Therefore, designing efficient algorithms of practical relevance is crucial, though their global optimality is not guaranteed. Existing semi-definite programming relaxation based approaches are restricted to OPF problems where zero duality holds. In this paper, an efficient novel method to address the general nonconvex OPF problem is...
Numerical study of turbulent trailing-edge flows with base cavity effects using URANS
Do, Thau; Chen, Li; Tu, Jiyuan
2010-10-01
Turbulent flows over lifting surfaces exhibiting trailing-edge vortex shedding often cause adverse and complex phenomena, such as self-induced vibration and noise. In this paper, a numerical study on flow past a blunt-edged two-dimensional NACA 0015 section and the same section with various base cavity shapes and sizes at high Reynolds numbers has been performed using the unsteady Reynolds-averaged Navier-Stokes (URANS) approach with the realisable κ-ɛ turbulence model. The equations are solved using the control volume method of second-order accuracy in both spatial and time domains. The assessment of the application of URANS for periodic trailing-edge flow has shown that reasonable agreement is achieved for both the time-averaged and fluctuating parameters of interest, although some differences exist in the prediction of the near-wake streamwise velocity fluctuation magnitudes. The predicted Strouhal numbers of flows past the squared-off blunt configuration with varying degrees of bluntness agree well with published experimental measurements. It is found that the intensity of the vortex strengths at the trailing-edge is amplified when the degree of bluntness is increased, leading to an increase in the mean square pressure fluctuations. The numerical prediction shows that the presence of the base cavity at the trailing-edge does not change the inherent Strouhal number of the 2D section examined. However, it does have an apparent effect on the wake structure, local pressure fluctuations and the lift force fluctuations. It is observed that the size of the cavity has more influence on the periodic trailing-edge flow than its shape does.
Code validation for the magnetohydrodynamic flow at high Hartmann Number based on unstructured grid
International Nuclear Information System (INIS)
Highlights: • In this paper, a numerical code named MTC-H 2.0 based on unstructured mash was developed and validated. • In the code, a current density conservative scheme is used to ensure the conservative of current, Krylov subspace method and AMG method were used to improve the computing performance. • Both analytical and experimental cases were chosen to validate the code at high Hartmann number. • The code has good computing performance, and numerical results matched well with the analytical and experimental results. -- Abstract: In order to analyze the magnetohydrodynamic (MHD) effect in liquid metal fusion blanket, a parallel and high performance numerical code was developed to study MHD flows at high Hartmann Number based on the unstructured grid. In this code, the induced current and the Lorentz force were calculated with a current density conservative scheme, while the incompressible Navier–Stokes equations with the Lorentz force included as a source term was solved by projection method, a set of method were used to improve the computing performance such as Krylov subspace method and AMG method. To validate this code, three benchmarks of MHD flow at high Hartmann Number were conducted. The first benchmark was the case of Shercliff fully development flow, the second benchmark was the MHD flow in a circular pipe with changing external magnetic field, and the third benchmark was the MHD flow in a pipe with sudden expansion. In these cases the Hartmann Numbers were from 1000 to 6000. The code good computing performance, and numerical results show matched well with the analytical and experimental results
A Thermally-Regenerative Ammonia-Based Flow Battery for Electrical Energy Recovery from Waste Heat.
Zhu, Xiuping; Rahimi, Mohammad; Gorski, Christopher A; Logan, Bruce
2016-04-21
Large amounts of low-grade waste heat (temperatures industrial, geothermal, and solar-based processes. Using thermally-regenerative ammonia solutions, low-grade thermal energy can be converted to electricity in battery systems. To improve reactor efficiency, a compact, ammonia-based flow battery (AFB) was developed and tested at different solution concentrations, flow rates, cell pairs, and circuit connections. The AFB achieved a maximum power density of 45 W m(-2) (15 kW m(-3) ) and an energy density of 1260 Wh manolyte (-3) , with a thermal energy efficiency of 0.7 % (5 % relative to the Carnot efficiency). The power and energy densities of the AFB were greater than those previously reported for thermoelectrochemical and salinity-gradient technologies, and the voltage or current could be increased using stacked cells. These results demonstrated that an ammonia-based flow battery is a promising technology to convert low-grade thermal energy to electricity. PMID:26990485
Li, Minghua; Hikihara, Takashi
2008-01-01
The redox (Reduction-Oxidation) flow battery is one of the most promising rechargeable batteries due to its ability to average loads and output of power sources. The transient characteristics are well known as the remarkable feature of the battery. Then it can also compensate for a sudden voltage drop. The dynamics are governed by the chemical reactions, fluid flow, and electrical circuit of its structure. This causes the difficulty of the analysis at transient state. This paper discusses the...
Image-based analysis of blood flow modification in stented aneurysms
Cebral, Juan; Mut, Fernando; Appanaboyina, Sunil; Löhner, Rainald; Miranda, Carlos; Escrivano, Esteban; Lylyk, Pedro; Putman, Christopher
2009-02-01
Currently there is increased interest in the use of stents as flow diverters for the treatment of intracranial aneurysms, especially wide necked aneurysms that are difficult to treat by coil embolization or surgical clipping. This paper presents image-based patient-specific computational models of the hemodynamics in cerebral aneurysms before and after treatment with a stent alone, with the goal of better understanding the hemodynamic effects of these devices and their relation to the outcome of the procedures. Stenting of cerebral aneurysms is a feasible endovascular treatment option for aneurysms with wide necks that are difficult to treat with coils or by surgical clipping. However, this requires stents that are capable of substantially modifying the intra-aneurysmal flow pattern in order to cause thrombosis of the aneurysm. The results presented in this paper show that the studied stent was able to change significantly the hemodynamic characteristics of the aneurysm. In addition, it was shown that patient-specific computational models constructed from medical images are capable of realistically representing the in vivo hemodynamic characteristics observed during conventional angiography examinations before and after stenting. This indicates that these models can be used to better understand the effects of different stent designs and to predict the alteration in the hemodynamic pattern of a given aneurysm produced by a given flow diverter. This is important for improving current design of flow diverting devices and patient treatment plans.
Development of a risk monitoring system for nuclear power plants based on GO-FLOW methodology
International Nuclear Information System (INIS)
Highlights: • A method for developing Living PSA is proposed. • Living PSA is easy to update with online modification to system model file. • A risk monitoring system is designed and developed using the GO-FLOW. • The risk monitoring system is useful for plant daily operation risk management. - Abstract: The paper presents a risk monitoring system developed based on GO-FLOW methodology which is a success-oriented system reliability modeling technique for phased mission as well as time-dependent problems analysis. The risk monitoring system is designed to receive information on plant configuration changes either from equipment failures, operator interventions, or maintenance activities, then update the Living PSA model with online modification to the system GO-FLOW model file which contains all the functional modes of equipment represented by a proposed generalized GO-FLOW modeling structure, and display risk values graphically. The risk monitoring system can be used to assist safety engineers and plant operators in their maintenance management and daily operation risk management at NPPs
An Image-Based Model of Fluid Flow Through Lymph Nodes.
Cooper, Laura J; Heppell, James P; Clough, Geraldine F; Ganapathisubramani, Bharathram; Roose, Tiina
2016-01-01
The lymphatic system returns fluid to the bloodstream from the tissues to maintain tissue fluid homeostasis. Lymph nodes distributed throughout the system filter the lymphatic fluid. The afferent and efferent lymph flow conditions of lymph nodes can be measured in experiments; however, it is difficult to measure the flow within the nodes. In this paper, we present an image-based modelling approach to investigating how the internal structure of the node affects the fluid flow pathways within the node. Selective plane illumination microscopy images of murine lymph nodes are used to identify the geometry and structure of the tissue within the node and to determine the permeability of the lymph node interstitium to lymphatic fluid. Experimental data are used to determine boundary conditions and optimise the parameters for the model. The numerical simulations conducted within the model are implemented in COMSOL Multiphysics, a commercial finite element analysis software. The parameter fitting resulted in the estimate that the average permeability for lymph node tissue is of the order of magnitude of [Formula: see text]. Our modelling shows that the flow predominantly takes a direct path between the afferent and efferent lymphatics and that fluid is both filtered and absorbed across the blood vessel boundaries. The amount that is absorbed or extravasated in the model is dependent on the efferent lymphatic lumen fluid pressure. PMID:26690921
Flow-acoustic Characterisation of a Cavity-based Combustor Configuration
Directory of Open Access Journals (Sweden)
Krishna Kant Agarwal
2011-10-01
Full Text Available This study concerns the flow-acoustic characterisation of a cavity-based combustor configuration. A well-validated numerical tool has been used to simulate the unsteady, two-dimensional reacting flow. Initially, a conventional flow over a cavity with dimensions and conditions corresponding to a compact cavity combustor was studied. Cavity mass injections in the form of fuel and air injections required for trapped vortex formation were then employed and the resonance features of this configuration were studied. The results indicate that the cavity depth mode resonance mechanism is dominant at the conditions studied in this work and that the oscillation frequencies do not change with cavity air injection. This observation is important since it implies that the only important variable which can alter resonant frequencies is the cavity depth. With combustion, the pressure oscillation amplitude was observed to increases significantly due to periodic entrainment of the cavity air jet and fluctuation of fuel-air mixture composition to produce highly fluctuating heat-release rates. The underlying mechanisms of the unsteady flow in the cavity combustor identified in this study indicate the strong dependence of the acoustics on the cavity injection strategies.Defence Science Journal, 2011, 61(6, pp.523-528, DOI:http://dx.doi.org/10.14429/dsj.61.870
International Nuclear Information System (INIS)
This paper introduces a new method to illuminate the nuclear accident by Multilevel Flow Model, and based on the method, a web-based nuclear accident illumination system is proposed to represent the current nuclear accident in nuclear power plant of Japan in an understandable way. The MFM is a means-end and part-whole modeling method to describe the structure and the intention of a plant process. The relationship between the MFM functions enables accident prediction for a plant process. Thus, a web-based accident illumination system based by MFM can describe the nuclear accident in the nuclear power plant clearly and be accessed by public to make the public get to know and understand the nuclear power and nuclear risk. The public can build their own confidence of the nuclear power by their understanding of the nuclear accident with this system and this is helpful to build a harmonious development environment for nuclear power. (author)
RANS-based simulation of turbulent wave boundary layer and sheet-flow sediment transport processes
DEFF Research Database (Denmark)
Fuhrman, David R.; Schløer, Signe; Sterner, Johanna
2013-01-01
with bed and suspended load descriptions, the latter based on an unsteady turbulent-diffusion equation, for simulation of sheet-flow sediment transport processes. In addition to standard features common within such RANS-based approaches, the present model includes: (1) hindered settling velocities at high......A numerical model coupling the horizontal component of the incompressible Reynolds-averaged Navier–Stokes (RANS) equationswith two-equation k−ω turbulence closure is presented and used to simulate a variety of turbulent wave boundary layer processes. The hydrodynamic model is additionally coupled...
Optimal Graph Based Segmentation using Flow Lines with Application to Airway Wall Segmentation
DEFF Research Database (Denmark)
Petersen, Jens; Nielsen, Mads; Lo, Pechin Chien Pau;
2011-01-01
surfaces with high curvature or complex shapes but the proposed columns, based on properly generated flow lines, which are non-intersecting, guarantee solutions that do not self-intersect and are better able to handle such surfaces. The method is applied to segment human airway walls in computed tomography...... images. Comparison with manual annotations on 649 cross-sectional images from 15 different subjects shows significantly smaller contour distances and larger area of overlap than are obtained with recently published graph based methods. Airway abnormality measurements obtained with the method on 480 scan...
Optimal graph based segmentation using flow lines with application to airway wall segmentation
DEFF Research Database (Denmark)
Petersen, Jens; Nielsen, Mads; Lo, Pechin;
2011-01-01
surfaces with high curvature or complex shapes but the proposed columns, based on properly generated flow lines, which are non-intersecting, guarantee solutions that do not self-intersect and are better able to handle such surfaces. The method is applied to segment human airway walls in computed tomography...... images. Comparison with manual annotations on 649 cross-sectional images from 15 different subjects shows significantly smaller contour distances and larger area of overlap than are obtained with recently published graph based methods. Airway abnormality measurements obtained with the method on 480 scan...
MODIFIED BOTTLENECK-BASED PROCEDURE FOR LARGE-SCALE FLOW-SHOP SCHEDULING PROBLEMS WITH BOTTLENECK
Institute of Scientific and Technical Information of China (English)
ZUO Yan; GU Hanyu; XI Yugeng
2006-01-01
A new bottleneck-based heuristic for large-scale flow-shop scheduling problems with a bottleneck is proposed, which is simpler but more tailored than the shifting bottleneck (SB)procedure. In this algorithm, a schedule for the bottleneck machine is first constructed optimally and then the non-bottleneck machines are scheduled around the bottleneck schedule by some effective dispatching rules. Computational results show that the modified bottleneck-based procedure can achieve a tradeoff between solution quality and computational time comparing with SB procedure for medium-size problems. Furthermore it can obtain a good solution in quite short time for large-scale scheduling problems.
Integrated potentiometric detector for use in chip-based flow cells
Tantra; Manz
2000-07-01
A new kind of potentiometric chip sensor for ion-selective electrodes (ISE) based on a solvent polymeric membrane is described. The chip sensor is designed to trap the organic cocktail inside the chip and to permit sample solution to flow past the membrane. The design allows the sensor to overcome technical problems of ruggedness and would therefore be ideal for industrial processes. The sensor performance for a Ba2+-ISE membrane based on a Vogtle ionophore showed electrochemical behavior similar to that observed in conventional electrodes and microelectrode arrangements. PMID:10905321
Coral proxy record of decadal-scale reduction in base flow from Moloka'i, Hawaii
Prouty, N.G.; Jupiter, S.D.; Field, M.E.; McCulloch, M.T.
2009-01-01
Groundwater is a major resource in Hawaii and is the principal source of water for municipal, agricultural, and industrial use. With a growing population, a long-term downward trend in rainfall, and the need for proper groundwater management, a better understanding of the hydroclimatological system is essential. Proxy records from corals can supplement long-term observational networks, offering an accessible source of hydrologie and climate information. To develop a qualitative proxy for historic groundwater discharge to coastal waters, a suite of rare earth elements and yttrium (REYs) were analyzed from coral cores collected along the south shore of Moloka'i, Hawaii. The coral REY to calcium (Ca) ratios were evaluated against hydrological parameters, yielding the strongest relationship to base flow. Dissolution of REYs from labradorite and olivine in the basaltic rock aquifers is likely the primary source of coastal ocean REYs. There was a statistically significant downward trend (-40%) in subannually resolved REY/Ca ratios over the last century. This is consistent with long-term records of stream discharge from Moloka'i, which imply a downward trend in base flow since 1913. A decrease in base flow is observed statewide, consistent with the long-term downward trend in annual rainfall over much of the state. With greater demands on freshwater resources, it is appropriate for withdrawal scenarios to consider long-term trends and short-term climate variability. It is possible that coral paleohydrological records can be used to conduct model-data comparisons in groundwater flow models used to simulate changes in groundwater level and coastal discharge. Copyright 2009 by the American Geophysical Union.
de Croon, Guido C H E
2016-02-01
The visual cue of optical flow plays an important role in the navigation of flying insects, and is increasingly studied for use by small flying robots as well. A major problem is that successful optical flow control seems to require distance estimates, while optical flow is known to provide only the ratio of velocity to distance. In this article, a novel, stability-based strategy is proposed for monocular distance estimation, relying on optical flow maneuvers and knowledge of the control inputs (efference copies). It is shown analytically that given a fixed control gain, the stability of a constant divergence control loop only depends on the distance to the approached surface. At close distances, the control loop starts to exhibit self-induced oscillations. The robot can detect these oscillations and hence be aware of the distance to the surface. The proposed stability-based strategy for estimating distances has two main attractive characteristics. First, self-induced oscillations can be detected robustly by the robot and are hardly influenced by wind. Second, the distance can be estimated during a zero divergence maneuver, i.e., around hover. The stability-based strategy is implemented and tested both in simulation and on board a Parrot AR drone 2.0. It is shown that the strategy can be used to: (1) trigger a final approach response during a constant divergence landing with fixed gain, (2) estimate the distance in hover, and (3) estimate distances during an entire landing if the robot uses adaptive gain control to continuously stay on the 'edge of oscillation.' PMID:26740501
Energy Technology Data Exchange (ETDEWEB)
Josypčuk, Bohdan, E-mail: josypcuk@jh-inst.cas.cz [J. Heyrovský Institute of Physical Chemistry of AS CR, v.v.i., Department of Biophysical Chemistry, Dolejskova 3, Prague (Czech Republic); Barek, Jiří [Charles University in Prague, Faculty of Science, University Center of Excellence UNCE “Supramolecular Chemistry”, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Albertov 6, CZ-128 43 Prague 2 (Czech Republic); Josypčuk, Oksana [J. Heyrovský Institute of Physical Chemistry of AS CR, v.v.i., Department of Biophysical Chemistry, Dolejskova 3, Prague (Czech Republic); Charles University in Prague, Faculty of Science, University Center of Excellence UNCE “Supramolecular Chemistry”, Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Albertov 6, CZ-128 43 Prague 2 (Czech Republic)
2013-05-17
Graphical abstract: -- Highlights: •Flow amperometric enzymatic biosensor was constructed. •The biosensor is based on a reactor of a novel material – porous silver solid amalgam. •Tubular amalgam detector was used for determination of decrease of O{sub 2} concentration. •Covalent bonds amalgam−thiol−enzyme contributed to the sensor long-term stability. •LOD of glucose was 0.01 mmol L{sup −1} with RSD = 1.3% (n = 11). -- Abstract: A flow amperometric enzymatic biosensor for the determination of glucose was constructed. The biosensor consists of a flow reactor based on porous silver solid amalgam (AgSA) and a flow tubular detector based on compact AgSA. The preparation of the sensor and the determination of glucose occurred in three steps. First, a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed at the porous surface of the reactor. Second, enzyme glucose oxidase (GOx) was covalently immobilized at MUA-layer using N-ethyl-N′-(3-dimethylaminopropyl) carboimide and N-hydroxysuccinimide chemistry. Finally, a decrease of oxygen concentration (directly proportional to the concentration of glucose) during enzymatic reaction was amperometrically measured on the tubular detector under flow injection conditions. The following parameters of glucose determination were optimized with respect to amperometric response: composition of the mobile phase, its concentration, the potential of detection and the flow rate. The calibration curve of glucose was linear in the concentration range of 0.02–0.80 mmol L{sup −1} with detection limit of 0.01 mmol L{sup −1}. The content of glucose in the sample of honey was determined as 35.5 ± 1.0 mass % (number of the repeated measurements n = 7; standard deviation SD = 1.2%; relative standard deviation RSD = 3.2%) which corresponds well with the declared values. The tested biosensor proved good long-term stability (77% of the current response of glucose was retained after 35 days)
Allocation of fixed transmission cost based on power flow tracing algorithm
Institute of Scientific and Technical Information of China (English)
ZHANG Qian; YU Ji-hui
2005-01-01
In the electricity market, charging based on the traditional spot electricity price often results in the payment imbalance of electric network, and goes against the development of the power system. So, it is necessary to modify the spot price. The key of the modification lies in how to calculate the fixed unit transmission cost of each node, that is how to allocate the fixed transmission cost to users.To solve this problem, we develop a power flow tracing algrithm to modify the spot price. We put forward a path searching method based on the graph theory after studying the fundamental principle of power flow tracing and apply the method to the downstream tracing algorithm and upstream tracing algorithm according to the proportional distribution principle. Furthermore, to improve the computational efficiency of the algorithm, we introduce the branch expunction method to optimize the node order. By using the result of power flow tracing to get fixed node transmission cost and introducing it to modify the spot price, we obtain the synthetical price.The application to a 5-bus system prove the algorithm feasible.
Directory of Open Access Journals (Sweden)
Qichun Bing
2015-01-01
Full Text Available Short-term traffic flow prediction is one of the most important issues in the field of adaptive traffic control system and dynamic traffic guidance system. In order to improve the accuracy of short-term traffic flow prediction, a short-term traffic flow local prediction method based on combined kernel function relevance vector machine (CKF-RVM model is put forward. The C-C method is used to calculate delay time and embedding dimension. The number of neighboring points is determined by use of Hannan-Quinn criteria, and the CKF-RVM model is built based on genetic algorithm. Finally, case validation is carried out using inductive loop data measured from the north–south viaduct in Shanghai. The experimental results demonstrate that the CKF-RVM model is 31.1% and 52.7% higher than GKF-RVM model and GKF-SVM model in the aspect of MAPE. Moreover, it is also superior to the other two models in the aspect of EC.
Yao, Li; Teng, Jun; Zhu, Mengya; Zheng, Lei; Zhong, Youhao; Liu, Guodong; Xue, Feng; Chen, Wei
2016-11-15
Here, we describe a disposable multi-walled carbon nanotubes (MWCNTs) labeled nucleic acid lateral flow strip biosensor for rapid and sensitive detection of aqueous mercury ions (Hg(2+)). Unlike the conventional colloidal gold nanoparticle based strip biosensors, the carboxylated MWCNTs were selected as the labeling substrate because of its high specific surface area for immobilization of recognition probes, improved stability and enhanced detection sensitivity of the strip biosensor. Combining the sandwich-type of T-Hg(2+)-T recognition mechanism with the optical properties of MWCNTs on lateral flow strip, optical black bands were observed on the lateral flow strips. Parameters (such as membrane category, the MWCNTs concentration, the amount of MWCNT-DNA probe, and the volume of the test probe) that govern the sensitivity and reproducibility of the sensor were optimized. The response of the optimized biosensor was highly linear over the range of 0.05-1ppb target Hg(2+), and the detection threshold was estimated at 0.05 ppb within a 15-min assay time. The sensitivity was 10-fold higher than the conventional colloidal gold based strip biosensor. More importantly, the stability of the sensor was also greatly improved with the usage of MWCNTs as the labeling. PMID:27183284
Ward, Adam S.; Schmadel, Noah M.; Wondzell, Steven M.; Harman, Ciaran; Gooseff, Michael N.; Singha, Kamini
2016-02-01
Solute transport along riparian and hyporheic flow paths is broadly expected to respond to dynamic hydrologic forcing by streams, aquifers, and hillslopes. However, direct observation of these dynamic responses is lacking, as is the relative control of geologic setting as a control on responses to dynamic hydrologic forcing. We conducted a series of four stream solute tracer injections through base flow recession in each of two watersheds with contrasting valley morphology in the H.J. Andrews Experimental Forest, monitoring tracer concentrations in the stream and in a network of shallow riparian wells in each watershed. We found hyporheic mean arrival time, temporal variance, and fraction of stream water in the bedrock-constrained valley bottom and near large roughness elements in the wider valley bottom were not variable with discharge, suggesting minimal control by hydrologic forcing. Conversely, we observed increases in mean arrival time and temporal variance and decreasing fraction stream water with decreasing discharge near the hillslopes in the wider valley bottom. This may indicate changes in stream discharge and valley bottom hydrology control transport in less constrained locations. We detail five hydrogeomorphic responses to base flow recession to explain observed spatial and temporal patterns in the interactions between streams and their valley bottoms. Models able to account for the transition from geologically dominated processes in the near-stream subsurface to hydrologically dominated processes near the hillslope will be required to predict solute transport and fate in valley bottoms of headwater mountain streams.
Study of density field measurement based on NPLS technique in supersonic flow
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Due to the influence of shock wave and turbulence, supersonic density field exhibits strongly inhomogeneous and unsteady characteristics. Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution, limitation of measuring 3D density field, and low signal to noise ratio (SNR). A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field. This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles, which would display the density fluctuation due to the influence of shock waves and vortexes. The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper, and the results reveal shock wave, turbulent boundary layer in the flow with the spatial resolution of 93.2 μm/pixel. By analyzing the results at interval of 5 μs, temporal evolution of density field can be observed.
Study of density field measurement based on NPLS technique in supersonic flow
Institute of Scientific and Technical Information of China (English)
TIAN LiFeng; YI ShiHe; ZHAO YuXin; HE Lin; CHENG ZhongYu
2009-01-01
Due to the influence of shock wave and turbulence,supersonic density field exhibits strongly inho-mogeneous and unsteady characteristics.Applying traditional density field measurement techniques to supersonic flows yields three problems: low spatiotemporal resolution,limitation of measuring 3D density field,and low signal to noise ratio (SNR).A new method based on Nano-based Planar Laser Scattering (NPLS) technique is proposed in this paper to measure supersonic density field.This method measures planar transient density field in 3D supersonic flow by calibrating the relationship between density and concentration of tracer particles,which would display the density fluctuation due to the influence of shock waves and vortexes.The application of this new method to density field measurement of supersonic optical bow cap is introduced in this paper,and the results reveal shock wave,turbulent boundary layer in the flow with the spatial resolution of 93.2 pm/pixel.By analyzing the results at interval of 5 μs,temporal evolution of density field can be observed.
Institute of Scientific and Technical Information of China (English)
Miao Yu; Zongzheng Chen; Cheng Xiang; Bo Liu; Handi Xie; Kairong Qin
2016-01-01
Single cell trapping in vitro by microfluidic device is an emerging approach for the study of the rela-tionship between single cells and their dynamic biochemical microenvironments. In this paper, a hydrodynamic-based microfluidic device for single cell trapping is designed using a combination of stagnation point flow and physical barrier. The microfluidic device overcomes the weakness of the tra-ditional ones, which have been only based upon either stag-nation point flows or physical barriers, and can conveniently load dynamic biochemical signals to the trapped cell. In addi-tion, it can connect with a programmable syringe pump and a microscope to constitute an integrated experimental system. It is experimentally verified that the microfluidic system can trap single cells in vitro even under flow disturbance and con-veniently load biochemical signals to the trapped cell. The designed micro-device would provide a simple yet effective experimental platform for further study of the interactions between single cells and their microenvironments.
Park, Hyunwook; Pan, Xiaomin; Lee, Changhoon; Choi, Jung-Il
2016-06-01
A novel immersed boundary (IB) method based on an implicit direct forcing (IDF) scheme is developed for incompressible viscous flows. The key idea for the present IDF method is to use a block LU decomposition technique in momentum equations with Taylor series expansion to construct the implicit IB forcing in a recurrence form, which imposes more accurate no-slip boundary conditions on the IB surface. To accelerate the IB forcing convergence during the iterative procedure, a pre-conditioner matrix is introduced in the recurrence formulation of the IB forcing. A Jacobi-type parameter is determined in the pre-conditioner matrix by minimizing the Frobenius norm of the matrix function representing the difference between the IB forcing solution matrix and the pre-conditioner matrix. In addition, the pre-conditioning parameter is restricted due to the numerical stability in the recurrence formulation. Consequently, the present pre-conditioned IDF (PIDF) enables accurate calculation of the IB forcing within a few iterations. We perform numerical simulations of two-dimensional flows around a circular cylinder and three-dimensional flows around a sphere for low and moderate Reynolds numbers. The result shows that PIDF yields a better imposition of no-slip boundary conditions on the IB surfaces for low Reynolds number with a fairly larger time step than IB methods with different direct forcing schemes due to the implicit treatment of the diffusion term for determining the IB forcing. Finally, we demonstrate the robustness of the present PIDF scheme by numerical simulations of flow around a circular array of cylinders, flows around a falling sphere, and two sedimenting spheres in gravity.
Event-Based Computation of Motion Flow on a Neuromorphic Analog Neural Platform.
Giulioni, Massimiliano; Lagorce, Xavier; Galluppi, Francesco; Benosman, Ryad B
2016-01-01
Estimating the speed and direction of moving objects is a crucial component of agents behaving in a dynamic world. Biological organisms perform this task by means of the neural connections originating from their retinal ganglion cells. In artificial systems the optic flow is usually extracted by comparing activity of two or more frames captured with a vision sensor. Designing artificial motion flow detectors which are as fast, robust, and efficient as the ones found in biological systems is however a challenging task. Inspired by the architecture proposed by Barlow and Levick in 1965 to explain the spiking activity of the direction-selective ganglion cells in the rabbit's retina, we introduce an architecture for robust optical flow extraction with an analog neuromorphic multi-chip system. The task is performed by a feed-forward network of analog integrate-and-fire neurons whose inputs are provided by contrast-sensitive photoreceptors. Computation is supported by the precise time of spike emission, and the extraction of the optical flow is based on time lag in the activation of nearby retinal neurons. Mimicking ganglion cells our neuromorphic detectors encode the amplitude and the direction of the apparent visual motion in their output spiking pattern. Hereby we describe the architectural aspects, discuss its latency, scalability, and robustness properties and demonstrate that a network of mismatched delicate analog elements can reliably extract the optical flow from a simple visual scene. This work shows how precise time of spike emission used as a computational basis, biological inspiration, and neuromorphic systems can be used together for solving specific tasks. PMID:26909015
Optimal Folding of Data Flow Graphs based on Finite Projective Geometry using Lattice Embedding
Choudhary, Swadesh; Patkar, Sachin
2011-01-01
A number of computations exist, especially in area of error-control coding and matrix computations, whose underlying data flow graphs are based on finite projective-geometry(PG) based balanced bipartite graphs. Many of these applications are actively being researched upon. Almost all these applications need bipartite graphs of the order of tens of thousands in practice, whose nodes represent parallel computations. To reduce its implementation cost, reducing amount of system/hardware resources during design is an important engineering objective. In this context, we present a scheme to reduce resource utilization when performing computations derived from PG-based graphs. In a fully parallel design based on PG concepts, the number of processing units is equal to the number of vertices, each performing an atomic computation. To reduce the number of processing units used for implementation, we present an easy way of partitioning the vertex set. Each block of partition is then assigned to a processing unit. A proce...
Label-free single cell analysis with a chip-based impedance flow cytometer
Pierzchalski, Arkadiusz; Hebeisen, Monika; Mittag, Anja; Di Berardino, Marco; Tarnok, Attila
2010-02-01
For description of cellular phenotypes and physiological states new developments are needed. Axetris' impedance flow cytometer (IFC) (Leister) is a new promising label-free alternative to fluorescence-based flow cytometry (FCM). IFC measures single cells at various frequencies simultaneously. The frequencies used for signal acquisition range from 0.1 to 20 MHz. The impedance signal provides information about cell volume (ionophore valinomycin. Changes in membrane potential were detectable at the level of cytoplasm conductivity (>4 MHz) and membrane capacitance (1-4 MHz). Our data indicate that IFC can be a valuable alternative to conventional FCM for various applications in the field of cell death and physiology. The work will be extended to address further potential applications of IFC in biotechnology and biomedical cell analysis, as well as in cell sorting.
MRI-based aortic blood flow model in 3D ballistocardiography.
Lejeune, L; Prisk, G K; Nonclercq, A; Migeotte, P-F
2015-08-01
Ballistocardiography (BCG) is a non-invasive technique which measures the acceleration of a body induced by cardiovascular activity, namely the force exerted by the beating heart. A one dimensional aortic flow model based on the transmission lines theory is developped and applied to the simulation of three dimensional BCG. A four-element Windkessel model is used to generate the pressure-wave. Using transverse MRI slices of a human subject, a reconstruction of the aorta allows the extraction of parameters used to relate the local change in mass of the 1D flow model to 3D acceleration BCG. Simulated BCG curves are then compared qualitatively with the ensemble average curves of the same subject recorded in sustained microgravity. Confirming previous studies, the main features of the y-axis are well simulated. The simulated z-axis, never attempted before, shows important similarities. The simulated x-axis is less faithful and suggests the presence of reflections. PMID:26737946
REAL-TIME FACE RECOGNITION BASED ON OPTICAL FLOW AND HISTOGRAM EQUALIZATION
Directory of Open Access Journals (Sweden)
D. Sathish Kumar
2013-05-01
Full Text Available Face recognition is one of the intensive areas of research in computer vision and pattern recognition but many of which are focused on recognition of faces under varying facial expressions and pose variation. A constrained optical flow algorithm discussed in this paper, recognizes facial images involving various expressions based on motion vector computation. In this paper, an optical flow computation algorithm which computes the frames of varying facial gestures, and integrating with synthesized image in a probabilistic environment has been proposed. Also Histogram Equalization technique has been used to overcome the effect of illuminations while capturing the input data using camera devices. It also enhances the contrast of the image for better processing. The experimental results confirm that the proposed face recognition system is more robust and recognizes the facial images under varying expressions and pose variations more accurately.
Directory of Open Access Journals (Sweden)
Ion SMEUREANU
2009-01-01
Full Text Available Nowadays, business interoperability is one of the key factors for assuring competitive advantage for the participant business partners. In order to implement business cooperation, scalable, distributed and portable collaborative systems have to be implemented. This article presents some of the mostly used technologies in this field. Furthermore, it presents a software application architecture based on Business Process Modeling Notation standard and automated semantic web service coupling for modeling business flow in a collaborative manner. The main business processes will be represented in a single, hierarchic flow diagram. Each element of the diagram will represent calls to semantic web services. The business logic (the business rules and constraints will be structured with the help of OWL (Ontology Web Language. Moreover, OWL will also be used to create the semantic web service specifications.
A PC-based inverse design method for radial and mixed flow turbomachinery
Skoe, Ivar Helge
1991-01-01
An Inverse Design Method suitable for radial and mixed flow turbomachinery is presented. The codes are based on the streamline curvature concept; therefore, it is applicable for current personal computers from the 286/287 range. In addition to the imposed aerodynamic constraints, mechanical constraints are imposed during the design process to ensure that the resulting geometry satisfies production consideration and that structural considerations are taken into account. By the use of Bezier Curves in the geometric modeling, the same subroutine is used to prepare input for both aero and structural files since it is important to ensure that the geometric data is identical to both structural analysis and production. To illustrate the method, a mixed flow turbine design is shown.
Time-resolved fuel injector flow characterisation based on 3D laser Doppler vibrometry
Crua, Cyril
2015-01-01
In order to enable investigations of the fuel flow inside unmodified injectors, we have developed a new experimental approach to measure time-resolved vibration spectra of diesel nozzles using a three dimensional laser vibrometer. The technique we propose is based on the triangulation of the vibrometer and fuel pressure transducer signals, and enables the quantitative characterisation of quasi-cyclic internal flows without requiring modifications to the injector, the working fluid, or limiting the fuel injection pressure. The vibrometer, which uses the Doppler effect to measure the velocity of a vibrating object, was used to scan injector nozzle tips during the injection event. The data were processed using a discrete Fourier transform to provide time-resolved spectra for valve-closed-orifice, minisac and microsac nozzle geometries, and injection pressures ranging from 60 to 160MPa, hence offering unprecedented insight into cyclic cavitation and internal mechanical dynamic processes. A peak was consistently f...
International Nuclear Information System (INIS)
The largest source of uncertainty in the calculation of reactor power can be attributed to the limited accuracy and potential for undetected degradation of conventional flow nozzles and venturis used for feedwater flow measurement. UFM installations have been carried out with regulatory approval in PWRs and BWRs in the USA, regulatory approval is being progressed for trial installations on commercial nuclear units in Japan, and installations are being considered for PHWRs in Canada. Installations use permanently mounted chordal measurement transducer arrays in laboratory calibrated pipe spools to achieve a measurement accuracy of ±0.28%. In addition to high accuracy, measurement systems have evolved to be highly reliable, with redundancy and self-checking features built in to eliminate failures and the potential for drift and inadvertent overpower conditions. Outputs can be used for thermal power measurement and for feedwater flow process control. Measurement frequency can be set to be compatible with existing systems for thermal power measurement and process control. Contributors to thermal power measurement uncertainty are examined, and the range of potential measurement uncertainty recapture (MUR) is identified. Using industry-accepted practices to carry out MUR calculations, the available thermal power uprate can be predicted. Based on the combined uncertainty of all of the process parameters used in on-line thermal power calculations and the uncertainty assumed in the original licensing basis, available thermal power uprates vary between 1.5 and 2.5% of full power (FP). As the year-to-year power demand in Canada increases, nuclear energy continues to play an essential role in providing secure, stable and affordable electricity. Nuclear energy remains cost-competitive compared to other energy resources while eliminating greenhouse gas emissions. In the last decade, great progress has been achieved in developing new technologies applicable to NPPs, especially
DNS based analysis of liquid phase turbulence kinetic energy equation for bubbly two-phase flow
International Nuclear Information System (INIS)
While the modeling of turbulent single phase flows has already reached a certain level of maturity, models for the turbulence in bubble flows are still under development. The majority of models is based on the transport equation for liquid phase turbulence kinetic energy (kL) which is recast by extending the k-equation for single phase flow with empirical closure terms to account for the dispersed phase. In this paper we investigate bubble-induced liquid phase pseudo-turbulence by direct numerical simulations (DNS) based on the volume-of-fluid method. Simulations are performed for a regular array of ellipsoidal bubbles (gas hold up a 0.8%) and for a monodisperse swarm of 8 bubbles (a 6.4 %) rising in a plane vertical channel within an otherwise stagnant liquid. In the three bubble swarm simulations the liquid viscosity is varied by a factor of 10, resulting in a change of the bubble shape from ellipsoidal to spherical, a decrease of the average bubble rise velocity by a factor of 5 and a decrease of kL by a factor of 20. The DNS data are used to perform a detailed quantitative analysis of the analytical balance equation for kL. The evaluation comprises single-phase-like terms (diffusion, dissipation, production) as well as the interfacial term that only exists for two-phase flows. The general conclusion to be drawn for the considered bubbly flows is the prominent role of the interfacial term. Because the production term due to shear stresses is so low that it can be neglected, the interfacial term is the only one that feeds the liquid phase turbulence. The different closure terms in the analytical kL-equation are compared with respective closure assumptions for the modeled kL-equation implemented in two-phase k-l, k-e and ASM turbulence models. We find that - for the bubbly flows studied here - the conventional modelling of single-phase-like terms totally fails. Encouraging results are, however, obtained for modeling of the interfacial term. A detailed analysis of
von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian; Rickenmann, Dieter
2016-04-01
Debris flows are frequent natural hazards that cause massive damage. A wide range of debris flow models try to cover the complex flow behavior that arises from the inhomogeneous material mixture of water with clay, silt, sand, and gravel. The energy dissipation between moving grains depends on grain collisions and tangential friction, and the viscosity of the interstitial fine material suspension depends on the shear gradient. Thus a rheology description needs to be sensitive to the local pressure and shear rate, making the three-dimensional flow structure a key issue for flows in complex terrain. Furthermore, the momentum exchange between the granular and fluid phases should account for the presence of larger particles. We model the fine material suspension with a Herschel-Bulkley rheology law, and represent the gravel with the Coulomb-viscoplastic rheology of Domnik & Pudasaini (Domnik et al. 2013). Both composites are described by two phases that can mix; a third phase accounting for the air is kept separate to account for the free surface. The fluid dynamics are solved in three dimensions using the finite volume open-source code OpenFOAM. Computational costs are kept reasonable by using the Volume of Fluid method to solve only one phase-averaged system of Navier-Stokes equations. The Herschel-Bulkley parameters are modeled as a function of water content, volumetric solid concentration of the mixture, clay content and its mineral composition (Coussot et al. 1989, Yu et al. 2013). The gravel phase properties needed for the Coulomb-viscoplastic rheology are defined by the angle of repose of the gravel. In addition to this basic setup, larger grains and the corresponding grain collisions can be introduced by a coupled Lagrangian particle simulation. Based on the local Savage number a diffusive term in the gravel phase can activate phase separation. The resulting model can reproduce the sensitivity of the debris flow to water content and channel bed roughness, as
VR-based interactive CFD data comparison of flow fields in a human nasal cavity
Gerndt, Andreas; Kuhlen, Torsten; van Reimersdahl, Thomas; Haack, Matthias; Bischof, Christian
2004-05-01
The Virtual Reality Center Aachen is developing a Virtual Reality based operation planning system in cooperation with aerodynamics scientists and physicians of several clinical centers. This system is meant to help the preparation of nose surgeries aimed at the elimination of respiratory diseases. A core part is the interactive comparison of experimental data and simulation data in the area of fluid dynamics. In a first step, data comparison is to depict the differences between healthy noses and diseased noses. Later on, data comparison should supply evidence for successful virtual surgeries, which finally results in guidance on the real operation. During virtual surgery sessions, scientists can interactively explore, analyze, annotate, and compare various medical and aerodynamics data sets. Image-based methods are used to extract several features in one image and between compared data sets. The determination of linked features between different data sets is a particular challenge because of their different time frames, scales, and distortions. An optimized human computer interface enables the user to interact intuitively within a virtual environment in order to select and deal with these data sets. Additionally to this interactive exploration, the system also allows automatic searches for cut plane and key frame candidates corresponding to given feature patterns. The comparison system makes use of an already implemented parallelized Computational Fluid Dynamics (CFD) postprocessing, which also extracts enhanced flow features that allow automatic detection of relevant flow regions. Beside vortex detection, the computation of critical points including flow field segmentation is a current research activity. These flow features are favored characteristics for the comparison and help considerably to classify different nose geometries and operation recommendations.
Threshold-based generic scheme for encrypted and tunneled Voice Flows Detection over IP Networks
Directory of Open Access Journals (Sweden)
M. Mazhar U. Rathore
2015-07-01
Full Text Available VoIP usage is rapidly growing due to its cost effectiveness, dramatic functionality over the traditional telephone network and its compatibility with public switched telephone network (PSTN. In some countries, like Pakistan, the commercial usage of VoIP is prohibited. Internet service providers (ISPs and telecommunication authorities are interested in detecting VoIP calls to either block or prioritize them. So detection of VoIP calls is important for both types of authorities. Signature-based, port-based, and pattern-based VoIP detection techniques are inefficient due to complex and confidential security and tunneling mechanisms used by VoIP. In this paper, we propose a generic, robust, efficient, and practically implementable statistical analysis-based solution to identify encrypted, non-encrypted, or tunneled VoIP media (voice flows using threshold values of flow statistical parameters. We have made a comparison with existing techniques and evaluated our system with respect to accuracy and efficiency. Our system has 97.54% direct rate and .00015% false positive rate.
Predicting pedestrian flow: a methodology and a proof of concept based on real-life data.
Davidich, Maria; Köster, Gerta
2013-01-01
Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For instance, our analysis of pedestrian motion under natural conditions at a major German railway station reveals that the values for free-flow velocities and the flow-density relationship differ significantly from widely used literature values. It is thus necessary to calibrate and validate the model against relevant real-life data to make it capable of reproducing and predicting real-life scenarios. In this work we aim at constructing such realistic pedestrian stream simulation. Based on the analysis of real-life data, we present a methodology that identifies key parameters and interdependencies that enable us to properly calibrate the model. The success of the approach is demonstrated for a benchmark model, a cellular automaton. We show that the proposed approach significantly improves the reliability of the simulation and hence the potential prediction accuracy. The simulation is validated by comparing the local density evolution of the measured data to that of the simulated data. We find that for our model the most sensitive parameters are: the source-target distribution of the pedestrian trajectories, the schedule of pedestrian appearances in the scenario and the mean free-flow velocity. Our results emphasize the need for real-life data extraction and analysis to enable predictive simulations. PMID:24386186
Predicting pedestrian flow: a methodology and a proof of concept based on real-life data.
Directory of Open Access Journals (Sweden)
Maria Davidich
Full Text Available Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For instance, our analysis of pedestrian motion under natural conditions at a major German railway station reveals that the values for free-flow velocities and the flow-density relationship differ significantly from widely used literature values. It is thus necessary to calibrate and validate the model against relevant real-life data to make it capable of reproducing and predicting real-life scenarios. In this work we aim at constructing such realistic pedestrian stream simulation. Based on the analysis of real-life data, we present a methodology that identifies key parameters and interdependencies that enable us to properly calibrate the model. The success of the approach is demonstrated for a benchmark model, a cellular automaton. We show that the proposed approach significantly improves the reliability of the simulation and hence the potential prediction accuracy. The simulation is validated by comparing the local density evolution of the measured data to that of the simulated data. We find that for our model the most sensitive parameters are: the source-target distribution of the pedestrian trajectories, the schedule of pedestrian appearances in the scenario and the mean free-flow velocity. Our results emphasize the need for real-life data extraction and analysis to enable predictive simulations.
Achleitner, S; De Toffol, S; Engelhard, C; Rauch, W
2005-01-01
In river stretches being subjected to flow regulation, usually for the purpose of energy production (e.g. Hydropower) or flood protection (river barrage), a special measure can be taken against the effect of combined sewer overflows (CSOs). The basic idea is the temporal increase of the river base flow (during storm weather) as an in-stream measure for mitigation of CSO spilling. The focus is the mitigation of the negative effect of acute pollution of substances. The measure developed can be seen as an application of the classic real time control (RTC) concept onto the river system. Upstream gate operation is to be based on real time monitoring and forecasting of precipitation. The main objective is the development of a model based predictive control system for the gate operation, by modelling of the overall wastewater system (incl. the receiving water). The main emphasis is put on the operational strategy and the appropriate short-term forecast of spilling events. The potential of the measure is tested for the application of the operational strategy and its ecological and economic feasibility. The implementation of such an in-stream measure into the hydropower's operational scheme is unique. Advantages are (a) the additional in-stream dilution of acute pollutants entering the receiving water and (b) the resulting minimization of the required CSO storage volume. PMID:16248184
Institute of Scientific and Technical Information of China (English)
Ken USHIJIMA; Mitsuteru IRIE; Neni SINTAWARDANI; Jovita TRIASTUTI; Umi HAMIDAH; Tadaharu ISHIKAWA; Naoyuki FUNAMIZU
2013-01-01
Material flow analysis （MFA） and value flow analysis （VFA） were applied to the sanitation system in an urban slum in Indonesia. Based on the results of the MFA and VFA, garbage and excreta disposal costs were evaluated to be 0.7% and 1.1%, respectively, of per capita income. Such value flows seem reasonable in light of the recognized affordability to pay （ATP） standard. However, current excreta disposal methods create negative impacts on downstream populations. Because such disadvantages do not go back to disposers, but passed to downstream, the current value flow structure does not motivate individual toilet users to install treatment facility. Based on current material and value flow structures, a resource recycling sanitation system scenario was examined. Based on VFA, an affordable initial cost for such a system was calculated; this was found to be comparable in price to a cheaper composting toilet that is currently available in the market.
Improvements of Critical Heat Flux Models Based on the Viscous Potential Flow Theory
Energy Technology Data Exchange (ETDEWEB)
Kim, Byoung Jae; Lee, Jong Hyuk; Kim, Kyung Doo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2014-10-15
Kelvin-Helmholtz instability is analyzed based on a potential flow of inviscid fluids. However, if the viscosity effect is taken into consideration, a nonuniform flow occurs due to the shear stress at the interface. The idea to incorporate the effects of fluid viscosities into the Kelvin-Helmholtz instability can be found in the viscous potential flow theory. Joseph and Liao showed that the potential (irrotational) flow of viscous fluids satisfies the Navier- Stokes equation. For the potential flow, since the vorticity is identically zero, the viscous term vanishes in the Navier-Stokes equation; the motion of fluid is governed by the Bernoulli equation. However, the viscous stresses do not vanish in general. Therefore, the viscous pressure is entered through the normal stress balance at the interface. In the viscous potential flow, the shear stress is neglected at the interface and wall, and thus there is a velocity slip at the interface. These treatments are consistent with the fact that the interface waves are induced more by pressure than by shear force. Funada and Joseph presented a viscous potential flow analysis of the Kelvin-Helmholtz instability. Funada et al. carried out a stability analysis of a circular fluid jet into another fluid. Funada and Joseph considered the capillary instability. The viscous potential flow analysis is more accurate than the inviscid flow analysis in terms of the growth rate. Therefore, the critical condition of the Kelvin-Helmholtz instability can be predicted more accurately than the inviscid flow analysis. In this study, the interfacial instabilities of viscous potential flows are applied to critical heat flux models for saturated pool boiling on infinite horizontal surfaces, with the aim of including the effects of fluid viscosities. The critical conditions of the circular jet and Kelvin- Helmholtz instabilities are incorporated into the hydrodynamic theory model and liquid macrolayer dryout model. Circular jet instabilities is
Improvements of Critical Heat Flux Models Based on the Viscous Potential Flow Theory
International Nuclear Information System (INIS)
Kelvin-Helmholtz instability is analyzed based on a potential flow of inviscid fluids. However, if the viscosity effect is taken into consideration, a nonuniform flow occurs due to the shear stress at the interface. The idea to incorporate the effects of fluid viscosities into the Kelvin-Helmholtz instability can be found in the viscous potential flow theory. Joseph and Liao showed that the potential (irrotational) flow of viscous fluids satisfies the Navier- Stokes equation. For the potential flow, since the vorticity is identically zero, the viscous term vanishes in the Navier-Stokes equation; the motion of fluid is governed by the Bernoulli equation. However, the viscous stresses do not vanish in general. Therefore, the viscous pressure is entered through the normal stress balance at the interface. In the viscous potential flow, the shear stress is neglected at the interface and wall, and thus there is a velocity slip at the interface. These treatments are consistent with the fact that the interface waves are induced more by pressure than by shear force. Funada and Joseph presented a viscous potential flow analysis of the Kelvin-Helmholtz instability. Funada et al. carried out a stability analysis of a circular fluid jet into another fluid. Funada and Joseph considered the capillary instability. The viscous potential flow analysis is more accurate than the inviscid flow analysis in terms of the growth rate. Therefore, the critical condition of the Kelvin-Helmholtz instability can be predicted more accurately than the inviscid flow analysis. In this study, the interfacial instabilities of viscous potential flows are applied to critical heat flux models for saturated pool boiling on infinite horizontal surfaces, with the aim of including the effects of fluid viscosities. The critical conditions of the circular jet and Kelvin- Helmholtz instabilities are incorporated into the hydrodynamic theory model and liquid macrolayer dryout model. Circular jet instabilities is
DRIFT: a network analysis computer program based on drift-flux model for two-phase flow
International Nuclear Information System (INIS)
A general description on various two-phase flow models used in the analysis of water reacter safety is given. An introduction to TRIFT, a one dimentional two-phase flow system analysis code based on nonequilibrium driftflux model, is presented. It also includes the calculation for a simple example and a summary on the characteristics of the code
International Nuclear Information System (INIS)
Highlights: • Design and testing of non invasive and passive SmCo based PMFM. • SmCo PMFM has 55% lower weight than existing ALNICO-V PMFM. • SmCo PMFM has 102% higher sensitivity than existing ALNICO-V PMFM. • Design optimization and sensitivity estimation of SmCo PMFM with FEM analysis. • Review of flow measurement techniques for Liquid sodium in large SS pipes. - Abstract: Liquid sodium is used as coolant in sodium cooled fast reactors (SFR) due to its favorable nuclear properties and excellent heat transfer properties. Good electrical conductivity of sodium is effectively utilized for measurement of flow in primary and secondary circuits of the reactor. Alnico-V based permanent magnet flow meters (PMFM) are used to measure the flow of liquid sodium in stainless steel (SS) pipes of diameter ranging from 15 NB (Nominal Bore) to 800 NB. These PMFMs become bulky and heavy and are less sensitive for flow measurement in large pipes with diameter above 100 NB. To increase the sensitivity and reduce the weight, a new PMFM suitable for 100 NB pipe is designed and developed with SmCo magnet. The performance of SmCo based flow meter is evaluated experimentally in an existing sodium loop by varying sodium temperature and flow rate. Overall weight and sensitivity of the new design is compared with Alnico-V flow meters. Three dimensional Finite Element Modeling (FEM) is carried out to establish, modeling as an alternate method for calibration. In modeling and simulation, magnetic field distribution across the flow meter pipe and its effects on flow meter voltage signals are analyzed. The effect of sodium temperature on flow meter voltage signal and its variation with change in sodium flow rate are predicted by modeling and compared with experimental results
Energy Technology Data Exchange (ETDEWEB)
S.M. Ghiaasiaan and Seppo Karrila
2006-03-20
Flow characteristics of fibrous paper pulp-water-air slurries were investigated in a vertical circular column 1.8 m long, with 5.08 cm diameter. Flow structures, gas holdup (void fraction), and the geometric and population characteristics of gas bubbles were experimentally investigated, using visual observation, Gamma-ray densitometry, and flash X-ray photography. Five distinct flow regimes could be visually identified: dispersed bubbly, layered bubbly, plug, churn-turbulent, and slug. Flow regime maps were constructed, and the regime transition lines were found to be sensitive to consistency. The feasibility of using artificial neural networks (ANNs) for the identification of the flow regimes, using the statistical characteristics of pressure fluctuations measured by a single pressure sensor, was demonstrated. Local pressure fluctuations at a station were recorded with a minimally-intrusive transducer. Three-layer, feed-forward ANNs were designed that could identify the four major flow patterns (bubbly, plug, churn, and slug) well. The feasibility of a transportable artificial neural network (ANN) - based technique for the classification of flow regimes was also examined. Local pressures were recorded at three different locations using three independent but similar transducers. An ANN was designed, trained and successfully tested for the classification of the flow regimes using one of the normalized pressure signals (from Sensor 1). The ANN trained and tested for Sensor 1 predicted the flow regimes reasonably well when applied directly to the other two sensors, indicating a good deal of transportability. An ANN-based method was also developed, whereby the power spectrum density characteristics of other sensors were adjusted before they were used as input to the ANN that was based on Sensor 1 alone. The method improved the predictions. The gas-liquid interfacial surface area concentration was also measured in the study. The gas absorption technique was applied
Initial assessment of facial nerve paralysis based on motion analysis using an optical flow method.
Samsudin, Wan Syahirah W; Sundaraj, Kenneth; Ahmad, Amirozi; Salleh, Hasriah
2016-03-14
An initial assessment method that can classify as well as categorize the severity of paralysis into one of six levels according to the House-Brackmann (HB) system based on facial landmarks motion using an Optical Flow (OF) algorithm is proposed. The desired landmarks were obtained from the video recordings of 5 normal and 3 Bell's Palsy subjects and tracked using the Kanade-Lucas-Tomasi (KLT) method. A new scoring system based on the motion analysis using area measurement is proposed. This scoring system uses the individual scores from the facial exercises and grades the paralysis based on the HB system. The proposed method has obtained promising results and may play a pivotal role towards improved rehabilitation programs for patients. PMID:26578273
Directory of Open Access Journals (Sweden)
Senay Tewolde
2015-01-01
Full Text Available Epilepsy is the third most common neurological illness, affecting 1% of the world’s population. Despite advances in medicine, about 25 to 30% of the patients do not respond to or cannot tolerate the severe side effects of medical treatment, and surgery is not an option for the majority of patients with epilepsy. The objective of this article is to review the current state of research on seizure detection based on cerebral blood flow (CBF data acquired by thermal diffusion flowmetry (TDF, and CBF-based seizure prediction. A discussion is provided on the applications, advantages, and disadvantages of TDF in detecting and localizing seizure foci, as well as its role in seizure prediction. Also presented are an overview of the present challenges and possible future research directions (along with methodological guidelines of the CBF-based seizure detection and prediction methods.
Robust optimization-based DC optimal power flow for managing wind generation uncertainty
Boonchuay, Chanwit; Tomsovic, Kevin; Li, Fangxing; Ongsakul, Weerakorn
2012-11-01
Integrating wind generation into the wider grid causes a number of challenges to traditional power system operation. Given the relatively large wind forecast errors, congestion management tools based on optimal power flow (OPF) need to be improved. In this paper, a robust optimization (RO)-based DCOPF is proposed to determine the optimal generation dispatch and locational marginal prices (LMPs) for a day-ahead competitive electricity market considering the risk of dispatch cost variation. The basic concept is to use the dispatch to hedge against the possibility of reduced or increased wind generation. The proposed RO-based DCOPF is compared with a stochastic non-linear programming (SNP) approach on a modified PJM 5-bus system. Primary test results show that the proposed DCOPF model can provide lower dispatch cost than the SNP approach.
Nelson, M; Alling, A; Dempster, W F; van Thillo, M; Allen, John
2003-01-01
Research and design of subsurface flow wetland wastewater treatment systems for a ground-based experimental prototype Mars Base facility has been carried out, using a subsurface flow approach. These systems have distinct advantages in planetary exploration scenarios: they are odorless, relatively low-labor and low-energy, assist in purification of water and recycling of atmospheric CO2, and will support some food crops. An area of 6-8 m2 may be sufficient for integration of wetland wastewater treatment with a prototype Mars Base supporting 4-5 people. Discharge water from the wetland system will be used as irrigation water for the agricultural crop area, thus ensuring complete recycling and utilization of nutrients. Since the primary requirements for wetland treatment systems are warm temperatures and lighting, such bioregenerative systems may be integrated into early Mars base habitats, since waste heat from the lights may be used for temperature maintenance in the human living environment. "Wastewater gardens (TM)" can be modified for space habitats to lower space and mass requirements. Many of its construction requirements can eventually be met with use of in-situ materials, such as gravel from the Mars surface. Because the technology requires little machinery and no chemicals, and relies more on natural ecological mechanisms (microbial and plant metabolism), maintenance requirements are minimized, and systems can be expected to have long operating lifetimes. Research needs include suitability of Martian soil and gravel for wetland systems, system sealing and liner options in a Mars Base, and wetland water quality efficiency under varying temperature and light regimes. PMID:14503520
Nelson, M.; Alling, A.; Dempster, W. F.; van Thillo, M.; Allen, John
Research and design of subsurface flow wetland wastewater treatment systems for a ground-based experimental prototype Mars Base facility has been carried out, using a subsurface flow approach. These systems have distinct advantages in planetary exploration scenarios: they are odorless, relatively low-labor and low-energy, assist in purification of water and recycling of atmospheric CO2, and will support some food crops. An area of 6-8 m2 may be sufficient for integration of wetland wastewater treatment with a prototype Mars Base supporting 4-5 people. Discharge water from the wetland system will be used as irrigation water for the agricultural crop area, thus ensuring complete recycling and utilization of nutrients. Since the primary requirements for wetland treatment systems are warm temperatures and lighting, such bioregenerative systems may be integrated into early Mars base habitats, since waste heat from the lights may be used for temperature maintenance in the human living environment. "Wastewater gardens ™" can be modified for space habitats to lower space and mass requirements. Many of its construction requirements can eventually be met with use of in-situ materials, such as gravel from the Mars surface. Because the technology requires little machinery and no chemicals, and relies more on natural ecological mechanisms (microbial and plant metabolism), maintenance requirements are minimized, and systems can be expected to have long operating lifetimes. Research needs include suitability of Martian soil and gravel for wetland systems, system sealing and liner options in a Mars Base, and wetland water quality efficiency under varying temperature and light regimes.
Galanti, Eli; Kaspi, Yohai
2015-11-01
The nature of the large scale flow on Jupiter below the cloud level is still unknown. The observed surface wind might be confined to the upper layers, or be a manifestation of deep cylindrical flow. Moreover, it is possible that in the case where the observed wind is superficial, there exists deep flow that is completely separated from the surface. To date, all models linking the wind (via the induced density nomalies) to the gravity field to be measured by Juno, consider only wind flow related to the observed could level wind. Some assume full cylindrical flow while others allow for the wind to decay with depth.Here we explore the possibility of complex wind dynamics that include both the upper-layer wind, and a deep flow that is completely detached from the flow above it. The surface flow is based on the observed cloud level flow and is set to decay with depth. The deep flow is constructed synthetically to produce cylindrical structures with variable width and magnitude, thus allowing for a wide range of possible setups of the unknown deep flow. This flow is also set to decay when approaching the surface flow in coordination with the exponential decay rate. The combined 3D flow is then related to the density anomalies via a dynamical model, taking into account oblateness effects as well, and the resulting density field is then used to calculate the gravitational moments. An adjoint inverse model is constructed for the dynamical model, thus allowing backward integration of the dynamical model, from the expected observations of the gravity moments to the parameters controlling the setup of the deep and surface flows. We show that the model can be used for examination of various scenarios, including cases in which the deep flow is dominating over the surface wind. The novelty of our adjoint based inversion approach is in the ability to identify complex dynamics including deep cylindrical flows that have no manifestation in the observed cloud-level wind. Furthermore
Research on Micro-Flow Self-Sensing Actuators Based on Piezoelectric Ceramic Stack
Institute of Scientific and Technical Information of China (English)
Yan-Bo Wei; Li-Ping Shi; Xi-Wen Wei; Jie Huang
2014-01-01
The paper is concerned with the micro-flow self-sensing actuators, the work of which is based on the secondary piezoelectric effect. The piezoelectric ceramic stack can yield micro-displacement due to its first inverse piezoelectric effect. Therefore, we apply this micro-displacement to cell micro-flow injection. Moreover, due to the charge of the secondary direct piezoelectric effect, the piezoelectric ceramic stack is able to detect the force and displacement in the injection by itself. The experiments of first inverse piezoelectric effect and secondary direct piezoelectric effect are conducted. The experiment results show that, subjected to 0-60 V input, the piezoelectric ceramic stack can generate 13�45 μm displacement, and control accuracy can achieve 2 nm. It can completely meet the needs of cell micro-flow injection. Also, the experiments demonstrate that the micro-displacement due to the first inverse piezoelectric effect can be well self-sensed by the electric charge due to the secondary direct piezoelectric effect.
Molecule-based approach for computing chemical-reaction rates in upper atmosphere hypersonic flows.
Energy Technology Data Exchange (ETDEWEB)
Gallis, Michail A.; Bond, Ryan Bomar; Torczynski, John Robert
2009-08-01
This report summarizes the work completed during FY2009 for the LDRD project 09-1332 'Molecule-Based Approach for Computing Chemical-Reaction Rates in Upper-Atmosphere Hypersonic Flows'. The goal of this project was to apply a recently proposed approach for the Direct Simulation Monte Carlo (DSMC) method to calculate chemical-reaction rates for high-temperature atmospheric species. The new DSMC model reproduces measured equilibrium reaction rates without using any macroscopic reaction-rate information. Since it uses only molecular properties, the new model is inherently able to predict reaction rates for arbitrary nonequilibrium conditions. DSMC non-equilibrium reaction rates are compared to Park's phenomenological non-equilibrium reaction-rate model, the predominant model for hypersonic-flow-field calculations. For near-equilibrium conditions, Park's model is in good agreement with the DSMC-calculated reaction rates. For far-from-equilibrium conditions, corresponding to a typical shock layer, the difference between the two models can exceed 10 orders of magnitude. The DSMC predictions are also found to be in very good agreement with measured and calculated non-equilibrium reaction rates. Extensions of the model to reactions typically found in combustion flows and ionizing reactions are also found to be in very good agreement with available measurements, offering strong evidence that this is a viable and reliable technique to predict chemical reaction rates.
Analysis of Phase Transition in Traffic Flow based on a New Model of Driving Decision
International Nuclear Information System (INIS)
Different driving decisions will cause different processes of phase transition in traffic flow. To reveal the inner mechanism, this paper built a new cellular automaton (CA) model, based on the driving decision (DD). In the DD model, a driver's decision is divided into three stages: decision-making, action, and result. The acceleration is taken as a decision variable and three core factors, i.e. distance between adjacent vehicles, their own velocity, and the preceding vehicle's velocity, are considered. Simulation results show that the DD model can simulate the synchronized flow effectively and describe the phase transition in traffic flow well. Further analyses illustrate that various density will cause the phase transition and the random probability will impact the process. Compared with the traditional NaSch model, the DD model considered the preceding vehicle's velocity, the deceleration limitation, and a safe distance, so it can depict closer to the driver preferences on pursuing safety, stability and fuel-saving and has strong theoretical innovation for future studies. (interdisciplinary physics and related areas of science and technology)
Analysis of Phase Transition in Traffic Flow based on a New Model of Driving Decision
Peng, Yu; Shang, Hua-Yan; Lu, Hua-Pu
2011-07-01
Different driving decisions will cause different processes of phase transition in traffic flow. To reveal the inner mechanism, this paper built a new cellular automaton (CA) model, based on the driving decision (DD). In the DD model, a driver's decision is divided into three stages: decision-making, action, and result. The acceleration is taken as a decision variable and three core factors, i.e. distance between adjacent vehicles, their own velocity, and the preceding vehicle's velocity, are considered. Simulation results show that the DD model can simulate the synchronized flow effectively and describe the phase transition in traffic flow well. Further analyses illustrate that various density will cause the phase transition and the random probability will impact the process. Compared with the traditional NaSch model, the DD model considered the preceding vehicle's velocity, the deceleration limitation, and a safe distance, so it can depict closer to the driver preferences on pursuing safety, stability and fuel-saving and has strong theoretical innovation for future studies.
Artificial intelligence based models for stream-flow forecasting: 2000-2015
Yaseen, Zaher Mundher; El-shafie, Ahmed; Jaafar, Othman; Afan, Haitham Abdulmohsin; Sayl, Khamis Naba
2015-11-01
The use of Artificial Intelligence (AI) has increased since the middle of the 20th century as seen in its application in a wide range of engineering and science problems. The last two decades, for example, has seen a dramatic increase in the development and application of various types of AI approaches for stream-flow forecasting. Generally speaking, AI has exhibited significant progress in forecasting and modeling non-linear hydrological applications and in capturing the noise complexity in the dataset. This paper explores the state-of-the-art application of AI in stream-flow forecasting, focusing on defining the data-driven of AI, the advantages of complementary models, as well as the literature and their possible future application in modeling and forecasting stream-flow. The review also identifies the major challenges and opportunities for prospective research, including, a new scheme for modeling the inflow, a novel method for preprocessing time series frequency based on Fast Orthogonal Search (FOS) techniques, and Swarm Intelligence (SI) as an optimization approach.
Numerical Study of Violent Impact Flow Using a CIP-Based Model
Directory of Open Access Journals (Sweden)
Qiao-ling Ji
2013-01-01
Full Text Available A two-phase flow model is developed to study violent impact flow problem. The model governed by the Navier-Stokes equations with free surface boundary conditions is solved by a Constrained Interpolation Profile (CIP-based high-order finite difference method on a fixed Cartesian grid system. The free surface is immersed in the computation domain and expressed by a one-fluid density function. An accurate Volume of Fluid (VOF-type scheme, the Tangent of Hyperbola for Interface Capturing (THINC, is combined for the free surface treatment. Results of another two free surface capturing methods, the original VOF and CIP, are also presented for comparison. The validity and utility of the numerical model are demonstrated by applying it to two dam-break problems: a small-scale two-dimensional (2D and three-dimensional (3D full scale simulations and a large-scale 2D simulation. Main attention is paid to the water elevations and impact pressure, and the numerical results show relatively good agreement with available experimental measurements. It is shown that the present numerical model can give a satisfactory prediction for violent impact flow.
Institute of Scientific and Technical Information of China (English)
LIU Zhengxian; WANG Xuejun; DAI Jishuang; ZHANG Chuhua
2009-01-01
A second-order mixing difference scheme with a limiting factor is deduced with the reconstruction gra-dient method and applied to discretizing the Navier-Stokes equation in an unstructured grid. The transform of non-orthogonal diffusion items generated by the scheme in discrete equations is provided. The Delaunay triangulation method is improved to generate the unstructured grid. The computing program based on the SIMPLE algorithm in an unstructured grid is compiled and used to solve the discrete equations of two types of incompressible viscous flow. The numerical simulation results of the laminar flow driven by lid in cavity and flow behind a cylinder are compared with the theoretical solution and experimental data respectively. In the former case, a good agreement is achieved in the main velocity and drag coefficient curve. In the latter case, the numerical structure and development of vortex under several Reynolds numbers match well with that of the experiment. It is indicated that the factor dif-ference scheme is of higher accuracy, and feasible to be applied to Navier-Stokes equation.
Research on monthly flow uncertain reasoning model based on cloud theory
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In view of the mid and long term runoff forecasting containing many uncertain factors,this paper constructs a uncertain reasoning model (UR) based on the cloud theory to solve the problem of uncertain reasoning.Firstly,in the proposed model,a classification method,i.e.,attribute oriented induction maximum variance (MaxVar),is used to divide the runoff series into different intervals,which are softened and described by the cloud membership with expected value (Ex),entropy (En) and hyper-entropy (He),then an uncertain reasoning rule set is constructed by means of the runoff value generalization and applied to monthly flow for uncertain prediction.Next,a new modification formula is used to calculate He in runoff forecasting,and a confident level probability prediction interval is obtained by statistical method.Finally,this paper takes the monthly flow of Manwan station in China as an example and uses UR model,LSSVM model,and ARMA model to calculate the monthly flow,respectively.The results show that the UR model has the highest prediction accuracy compared to other models,and that it not only provides random output but also supports probability interval prediction.
A new cut-based algorithm for the multi-state flow network reliability problem
International Nuclear Information System (INIS)
Many real-world systems can be modeled as multi-state network systems in which reliability can be derived in terms of the lower bound points of level d, called d-minimal cuts (d-MCs). This study proposes a new method to find and verify obtained d-MCs with simple and useful found properties for the multi-state flow network reliability problem. The proposed algorithm runs in O(mσp) time, which represents a significant improvement over the previous O(mp2σ) time bound based on max-flow/min-cut, where p, σ and m denote the number of MCs, d-MC candidates and edges, respectively. The proposed algorithm also conquers the weakness of some existing methods, which failed to remove duplicate d-MCs in special cases. A step-by-step example is given to demonstrate how the proposed algorithm locates and verifies all d-MC candidates. As evidence of the utility of the proposed approach, we present extensive computational results on 20 benchmark networks in another example. The computational results compare favorably with a previously developed algorithm in the literature. - Highlights: • A new method is proposed to find all d-MCs for the multi-state flow networks. • The proposed method can prevent the generation of d-MC duplicates. • The proposed method is simpler and more efficient than the best-known algorithms
A case study of fluid flow in fractured rock mass based on 2-D DFN modeling
Han, Jisu; Noh, Young-Hwan; Um, Jeong-Gi; Choi, Yosoon
2014-05-01
A two dimensional steady-state fluid flow through fractured rock mass of an abandoned copper mine in Korea is addressed based on discrete fracture network modeling. An injection well and three observation wells were installed at the field site to monitor the variations of total heads induced by injection of fresh water. A series of packer tests were performed to estimate the rock mass permeability. First, the two dimensional stochastic fracture network model was built and validated for a granitic rock mass using the geometrical and statistical data obtained from surface exposures and borehole logs. This validated fracture network model was combined with the fracture data observed on boreholes to generate a stochastic-deterministic fracture network system. Estimated apertures for each of the fracture sets using permeability data obtained from borehole packer tests were discussed next. Finally, a systematic procedure for fluid flow modeling in fractured rock mass in two dimensional domain was presented to estimate the conductance, flow quantity and nodal head in 2-D conceptual linear pipe channel network. The results obtained in this study clearly show that fracture geometry parameters (orientation, density and size) play an important role in the hydraulic behavior of fractured rock masses.
Passivity-Based Output-Feedback Control of Turbulent Channel Flow
Heins, Peter H; Sharma, Ati S
2016-01-01
This paper describes a robust linear time-invariant output-feedback control strategy to reduce turbulent fluctuations, and therefore skin-friction drag, in wall-bounded turbulent fluid flows, that nonetheless gives performance guarantees in the nonlinear turbulent regime. The novel strategy is effective in reducing the supply of available energy to feed the turbulent fluctuations, expressed as reducing a bound on the supply rate to a quadratic storage function. The nonlinearity present in the equations that govern the dynamics of the flow is known to be passive and can be considered as a feedback forcing to the linearised dynamics (a Lur'e decomposition). Therefore, one is only required to control the linear dynamics in order to make the system close to passive. The ten most energy-producing spatial modes of a turbulent channel flow were identified. Passivity-based controllers were then generated to control these modes. The controllers require measurements of streamwise and spanwise wall-shear stress, and the...
Stability study of flow in a 90° bend based on the energy gradient theory
International Nuclear Information System (INIS)
The energy gradient theory is used to analyze numerical simulation of the flow in a 90 degree bend with square cross-section. The Reynolds number based on the cross-sectional width and the averaged velocity is 158, 394 and 790, respectively. It is found that at Re = 790, the value of the energy gradient function K increases with the fluid entering the curved section, causing flow instability and forming a pair of secondary vortices; then the secondary vortices gradually stabilizes and the value of K decreases. At the exit of the bend, the total pressure distribution in the cross-section presents serious distortion, which leads to a transition of two vortices to four vortices. With the flow ahead, the maximum of K rises again, resulting in the transition of four vortices to eight vortices. At the low Reynolds number (Re = 158 and Re = 394), there is only one pair of vortices due to the low value of K, which are stable. This study shows that the occurrence of instability is closely related to the evolution of energy gradient function K
Testing of RANS Turbulence Models for Stratified Flows Based on DNS Data
Venayagamoorthy, S. K.; Koseff, J. R.; Ferziger, J. H.; Shih, L. H.
2003-01-01
In most geophysical flows, turbulence occurs at the smallest scales and one of the two most important additional physical phenomena to account for is strati cation (the other being rotation). In this paper, the main objective is to investigate proposed changes to RANS turbulence models which include the effects of stratifi- cation more explicitly. These proposed changes were developed using a DNS database on strati ed and sheared homogenous turbulence developed by Shih et al. (2000) and are described more fully in Ferziger et al. (2003). The data generated by Shih, et al. (2000) (hereinafter referred to as SKFR) are used to study the parameters in the k- model as a function of the turbulent Froude number, Frk. A modified version of the standard k- model based on the local turbulent Froude number is proposed. The proposed model is applied to a stratified open channel flow, a test case that differs significantly from the flows from which the modified parameters were derived. The turbulence modeling and results are discussed in the next two sections followed by suggestions for future work.
Kornet, Kacper
2014-01-01
We put forward a new type of spectral method for the direct numerical simulation of flows where anisotropy or very fine boundary layers are present. The mean idea is to take advantage of the fact that such structures are dissipative and that their presence should reduce the number of degrees of freedom of the flow, when paradoxically, their fine resolution incurs extra computational cost in most current methods. The principle of this method is to use a functional basis with elements that already include these fine structure so as to avoid these extra costs. This leads us to develop an algorithm to implement a spectral method for arbitrary functional bases, and in particular, non-orthogonal ones. We construct a basic implementation of this algorithm to simulate Magnetohydrodynamic (MHD) channel flows with an externally imposed, transverse magnetic field, where very thin boundary layers are known to develop along the channel walls. In this case, the sought functional basis can be built out of the eigenfunctions...
Thickness-based adaptive mesh refinement methods for multi-phase flow simulations with thin regions
International Nuclear Information System (INIS)
In numerical simulations of multi-scale, multi-phase flows, grid refinement is required to resolve regions with small scales. A notable example is liquid-jet atomization and subsequent droplet dynamics. It is essential to characterize the detailed flow physics with variable length scales with high fidelity, in order to elucidate the underlying mechanisms. In this paper, two thickness-based mesh refinement schemes are developed based on distance- and topology-oriented criteria for thin regions with confining wall/plane of symmetry and in any situation, respectively. Both techniques are implemented in a general framework with a volume-of-fluid formulation and an adaptive-mesh-refinement capability. The distance-oriented technique compares against a critical value, the ratio of an interfacial cell size to the distance between the mass center of the cell and a reference plane. The topology-oriented technique is developed from digital topology theories to handle more general conditions. The requirement for interfacial mesh refinement can be detected swiftly, without the need of thickness information, equation solving, variable averaging or mesh repairing. The mesh refinement level increases smoothly on demand in thin regions. The schemes have been verified and validated against several benchmark cases to demonstrate their effectiveness and robustness. These include the dynamics of colliding droplets, droplet motions in a microchannel, and atomization of liquid impinging jets. Overall, the thickness-based refinement technique provides highly adaptive meshes for problems with thin regions in an efficient and fully automatic manner
Man, Jun; Li, Weixuan; Zeng, Lingzao; Wu, Laosheng
2016-06-01
The ensemble Kalman filter (EnKF) has gained popularity in hydrological data assimilation problems. As a Monte Carlo based method, a sufficiently large ensemble size is usually required to guarantee the accuracy. As an alternative approach, the probabilistic collocation based Kalman filter (PCKF) employs the polynomial chaos expansion (PCE) to represent and propagate the uncertainties in parameters and states. However, PCKF suffers from the so-called "curse of dimensionality". Its computational cost increases drastically with the increasing number of parameters and system nonlinearity. Furthermore, PCKF may fail to provide accurate estimations due to the joint updating scheme for strongly nonlinear models. Motivated by recent developments in uncertainty quantification and EnKF, we propose a restart adaptive probabilistic collocation based Kalman filter (RAPCKF) for data assimilation in unsaturated flow problems. During the implementation of RAPCKF, the important parameters are identified and active PCE basis functions are adaptively selected at each assimilation step; the "restart" scheme is utilized to eliminate the inconsistency between updated model parameters and states variables. The performance of RAPCKF is systematically tested with numerical cases of unsaturated flow models. It is shown that the adaptive approach and restart scheme can significantly improve the performance of PCKF. Moreover, RAPCKF has been demonstrated to be more efficient than EnKF with the same computational cost.
Satellite angular velocity estimation based on star images and optical flow techniques.
Fasano, Giancarmine; Rufino, Giancarlo; Accardo, Domenico; Grassi, Michele
2013-01-01
An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components. PMID:24072023
Crowd Motion Analysis Based on Social Force Graph with Streak Flow Attribute
Directory of Open Access Journals (Sweden)
Shaonian Huang
2015-01-01
Full Text Available Over the past decades, crowd management has attracted a great deal of attention in the area of video surveillance. Among various tasks of video surveillance analysis, crowd motion analysis is the basis of numerous subsequent applications of surveillance video. In this paper, a novel social force graph with streak flow attribute is proposed to capture the global spatiotemporal changes and the local motion of crowd video. Crowd motion analysis is hereby implemented based on the characteristics of social force graph. First, the streak flow of crowd sequence is extracted to represent the global crowd motion; after that, spatiotemporal analogous patches are obtained based on the crowd visual features. A weighted social force graph is then constructed based on multiple social properties of crowd video. The graph is segmented into particle groups to represent the similar motion patterns of crowd video. A codebook is then constructed by clustering all local particle groups, and consequently crowd abnormal behaviors are detected by using the Latent Dirichlet Allocation model. Extensive experiments on challenging datasets show that the proposed method achieves preferable results in the application of crowd motion segmentation and abnormal behavior detection.
Energy Technology Data Exchange (ETDEWEB)
Man, Jun; Li, Weixuan; Zeng, Lingzao; Wu, Laosheng
2016-06-01
The ensemble Kalman filter (EnKF) has gained popularity in hydrological data assimilation problems. As a Monte Carlo based method, a relatively large ensemble size is usually required to guarantee the accuracy. As an alternative approach, the probabilistic collocation based Kalman filter (PCKF) employs the polynomial chaos to approximate the original system. In this way, the sampling error can be reduced. However, PCKF suffers from the so-called "curse of dimensionality". When the system nonlinearity is strong and number of parameters is large, PCKF could be even more computationally expensive than EnKF. Motivated by most recent developments in uncertainty quantification, we propose a restart adaptive probabilistic collocation based Kalman filter (RAPCKF) for data assimilation in unsaturated flow problems. During the implementation of RAPCKF, the important parameters are identified and active PCE basis functions are adaptively selected. The "restart" technology is used to eliminate the inconsistency between model parameters and states. The performance of RAPCKF is tested with numerical cases of unsaturated flow models. It is shown that RAPCKF is more efficient than EnKF with the same computational cost. Compared with the traditional PCKF, the RAPCKF is more applicable in strongly nonlinear and high dimensional problems.
Park, Emily S; Jin, Chao; Guo, Quan; Ang, Richard R; Duffy, Simon P; Matthews, Kerryn; Azad, Arun; Abdi, Hamidreza; Todenhöfer, Tilman; Bazov, Jenny; Chi, Kim N; Black, Peter C; Ma, Hongshen
2016-04-01
Circulating tumor cells (CTCs) offer tremendous potential for the detection and characterization of cancer. A key challenge for their isolation and subsequent analysis is the extreme rarity of these cells in circulation. Here, a novel label-free method is described to enrich viable CTCs directly from whole blood based on their distinct deformability relative to hematological cells. This mechanism leverages the deformation of single cells through tapered micrometer scale constrictions using oscillatory flow in order to generate a ratcheting effect that produces distinct flow paths for CTCs, leukocytes, and erythrocytes. A label-free separation of circulating tumor cells from whole blood is demonstrated, where target cells can be separated from background cells based on deformability despite their nearly identical size. In doping experiments, this microfluidic device is able to capture >90% of cancer cells from unprocessed whole blood to achieve 10(4) -fold enrichment of target cells relative to leukocytes. In patients with metastatic castration-resistant prostate cancer, where CTCs are not significantly larger than leukocytes, CTCs can be captured based on deformability at 25× greater yield than with the conventional CellSearch system. Finally, the CTCs separated using this approach are collected in suspension and are available for downstream molecular characterization. PMID:26917414
International Nuclear Information System (INIS)
An alternative approach for solution of the collisional Boltzmann equation for a lattice architecture is presented. In the proposed method, termed the collisional lattice Boltzmann method (cLBM), the effects of spatial transport are accounted for via a streaming operator, using a lattice framework, and the effects of detailed collisional interactions are accounted for using the full collision operator of the Boltzmann equation. The latter feature is in contrast to the conventional lattice Boltzmann methods (LBMs) where collisional interactions are modeled via simple equilibrium based relaxation models (e.g. BGK). The underlying distribution function is represented using weights and fixed velocity abscissas according to the lattice structure. These weights are evolved based on constraints on the evolution of generalized moments of velocity according to the collisional Boltzmann equation. It can be shown that the collision integral can be reduced to a summation of elementary integrals, which can be analytically evaluated. The proposed method is validated using studies of canonical microchannel Couette and Poiseuille flows (both body force and pressure driven) and the results are found to be in good agreement with those obtained from conventional LBMs and experiments where available. Unlike conventional LBMs, the proposed method does not involve any equilibrium based approximations and hence can be useful for simulation of highly nonequilibrium flows (for a range of Knudsen numbers) using a lattice framework. (paper)
Satellite Angular Velocity Estimation Based on Star Images and Optical Flow Techniques
Directory of Open Access Journals (Sweden)
Giancarmine Fasano
2013-09-01
Full Text Available An optical flow-based technique is proposed to estimate spacecraft angular velocity based on sequences of star-field images. It does not require star identification and can be thus used to also deliver angular rate information when attitude determination is not possible, as during platform de tumbling or slewing. Region-based optical flow calculation is carried out on successive star images preprocessed to remove background. Sensor calibration parameters, Poisson equation, and a least-squares method are then used to estimate the angular velocity vector components in the sensor rotating frame. A theoretical error budget is developed to estimate the expected angular rate accuracy as a function of camera parameters and star distribution in the field of view. The effectiveness of the proposed technique is tested by using star field scenes generated by a hardware-in-the-loop testing facility and acquired by a commercial-off-the shelf camera sensor. Simulated cases comprise rotations at different rates. Experimental results are presented which are consistent with theoretical estimates. In particular, very accurate angular velocity estimates are generated at lower slew rates, while in all cases the achievable accuracy in the estimation of the angular velocity component along boresight is about one order of magnitude worse than the other two components.
Czech Academy of Sciences Publication Activity Database
Kašička, Václav; Koval, Dušan; Šolínová, Veronika; Sázelová, Petra; Barth, Tomislav; Hlaváček, Jan; Slaninová, Jiřina
Bratislava: Slovak University of Technology, 2008 - (Sádecká, J.), L09/1-L09/4 ISSN 1335-5236. [International Conference Analytical Methods and Human Health /17./. Nový Smokovec (SK), 20.10.2008-23.10.2008] R&D Projects: GA ČR(CZ) GA203/06/1044; GA ČR GA203/08/1428 Institutional research plan: CEZ:AV0Z40550506 Keywords : capillary electrophoresis * free-flow electrophoresis * peptide-based pharmaceuticals Subject RIV: CB - Analytical Chemistry, Separation
Apaydın, Hasbi; Kitiş, Şükrü
2014-01-01
In this study, an automation system is designed for bakeries, biscuit factories, flour and bakery products used dough kneading and dosing machines. This microprocessor-based design, made of 5-flowing flour and water dispensing operation. For this, the area is very easy to become available and can be programmed PIC16F877A microcontroller used. This automation system isn’t used in most of the plants and mixing ratios. Therefore the operator’s ability and speed very important for mixing ratios a...
Research on target tracking in coal mine based on optical flow method
Xue, Hongye; Xiao, Qingwei
2015-03-01
To recognize, track and count the bolting machine in coal mine video images, a real-time target tracking method based on the Lucas-Kanade sparse optical flow is proposed in this paper. In the method, we judge whether the moving target deviate from its trajectory, predicate and correct the position of the moving target. The method solves the problem of failure to track the target or lose the target because of the weak light, uneven illumination and blocking. Using the VC++ platform and Opencv lib we complete the recognition and tracking. The validity of the method is verified by the result of the experiment.
Rapid identification of Yersinia pestis and Brucella melitensis by chip-based continuous flow PCR
Dietzsch, Michael; Hlawatsch, Nadine; Melzer, Falk; Tomaso, Herbert; Gärtner, Claudia; Neubauer, Heinrich
2012-06-01
To combat the threat of biological agents like Yersinia pestis and Brucella melitensis in bioterroristic scenarios requires fast, easy-to-use and safe identification systems. In this study we describe a system for rapid amplification of specific genetic markers for the identification of Yersinia pestis and Brucella melitensis. Using chip based PCR and continuous flow technology we were able to amplify the targets simultaneously with a 2-step reaction profile within 20 minutes. The subsequent analysis of amplified fragments by standard gel electrophoresis requires another 45 minutes. We were able to detect both pathogens within 75 minutes being much faster than most other nucleic acid amplification technologies.
A derives grid-based model for simulation of pedestrian flow
Institute of Scientific and Technical Information of China (English)
Min-jie CHEN; Günter B(A)RWOLFF; Hartmut SCHWANDT
2009-01-01
We present a derived grid-based model for the simulation of pedestrian flow. Interactions among pedestrians are considered as the result of forces within a certain neighbourhood. Unlike the social force model, the forces here, as in Newtonian physics, are proportional to the inverse of the square of the distance. Despite the notion of neighbourhood and the underlying grid, this model differs from the existing cellular automaton (CA) models in that the pedestrians are treated as individuals. Bresenham's algorithm for line rastering is applied in the step calculation.
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Wavelet transform is used to analyze the scaling rule convection flow from two aspects. By utilizing the method of extended self similarity (ESS), one can find the obtained scaling exponent agrees well with the one obtained from the temperature data in a experiment of wind tunnel. And then we propose a newly defined formula based on wavelet transform, and can determine the scaling exponent ξ(q) of temperature data. The obtained results demonstrate that we can correctly extract ξ(q) by using the method which is named as wavelet transform maximum modulus (WTMM).``
Rainfall measurement based on in-situ storm drainage flow sensors
DEFF Research Database (Denmark)
Ahm, Malte; Rasmussen, Michael Robdrup
2016-01-01
Data for adjustment of weather radar rainfall estimations are mostly obtained from rain gauge observations. However, the density of rain gauges is often very low. Yet in many urban catchments, runoff sensors are typically available which can measure the rainfall indirectly. By utilising these...... sensors, it may be possible to improve the ground rainfall estimate, and thereby improve the quantitative precipitation estimation from weather radars for urban drainage applications. To test the hypothesis, this paper presents a rainfall measurement method based on flow rate measurements from well...
Sanz Prat, A.; Lu, C.; Cirpka, O. A.
2014-12-01
Travel-time based models are presented as an alternative to traditional spatially explicit models to solve nonlinear reactive-transport problems. The main advantage of the travel-time approach is that it does not require multi-dimensional characterization of physical and chemical parameters, and transport is one-dimensional. Spatial dimensions are replaced by groundwater travel time, defined as the time required by a water particle to reach an observation point or the outflow boundary, respectively. The fundamental hypothesis is that locations of the same groundwater age exhibit the same reactive-species concentrations. This is true in strictly advective-reactive transport in steady-state flows if the coefficients of reactions are uniform and the concentration is uniform over the inflow boundary. We hypothesize that the assumption still holds when adding some dispersion in coupled flow and transport dynamics. We compare a two-dimensional, spatially explicit, bioreactive, advective-dispersive transport model, considered as "virtual truth", with three 1-D travel-time based models which differ by the conceptualization of longitudinal dispersion: (i) neglecting dispersive mixing altogether, (ii) introducing a local-scale longitudinal dispersivity constant in time and space, and (iii) using an effective longitudinal dispersivity that increases linearly with distance. We consider biodegradation of organic matter catalyzed by non-competitive inhibitive microbial populations. The simulated inflow contains oxygen, nitrate, and DOC. The domain contains growing aerobic and denitrifying bacteria, the latter being inhibited by oxygen. This system is computed in 1-D, and in 2-D heterogeneous domains. We conclude that the conceptualization of nonlinear bioreactive transport in complex multi-dimensional domains by quasi 1-D travel-time models is valid for steady-state flow if the reactants are introduced over a wide cross-section, flow is at quasi-steady state, and dispersive
Optimization of Financial Flow Management Based on Estimates of Regional Multiplicative Effects
Directory of Open Access Journals (Sweden)
Denis Aleksandrovich Tatarkin
2015-12-01
Full Text Available The article deals with questions of increasing the management efficiency of the regional financial resources. As the main hypothesis, the idea of the optimization of the management of the regional financial flows based on the multiplicative economic effect is proved. This measure will allow to evaluate more efficiently the impact of the regional socio-economic policy. The article presents a multifactor model of the management of the regional financial flows on the regional level — the matrix of financial flows, based on the principles of the general economic equilibrium theory, the balance method of «input-output» and the methodology of national accounts. The paper introduces a methodology for the integration of the regional consolidated budget balance in a matrix of financial flows. Matrix multipliers of the consolidated budget balance are calculated for some regions of the Russian Federation allowing to model the economic multiplicative effects resulting from impact of different types of exogenous factors on the economic development of the regions, such as to predict the impact of fiscal redistribution on the GRP and income, to assess the impact of foreign investment on economic growth, to explore the effectiveness of the federal tax policy at the regional level. The article shows that the multiplier effect depends on several factors, including the foreign trade relations of the region, its dependence on imports, the share of value added in gross output, as well as the household savings. Various levels of government can use the author’s approach during development of strategies for socio-economic development, in assessing the extent and direction of the influence of exogenous factors on the economy of the territory, as well as in analyzing the investment initiatives from the private sector applying for state financial support for projects. In the conclusion, the ways of improving the management of financial flows on the basis of
Diwakar, S. V.; Das, Sarit K.; Sundararajan, T.
2009-12-01
A new Quadratic Spline based Interface (QUASI) reconstruction algorithm is presented which provides an accurate and continuous representation of the interface in a multiphase domain and facilitates the direct estimation of local interfacial curvature. The fluid interface in each of the mixed cells is represented by piecewise parabolic curves and an initial discontinuous PLIC approximation of the interface is progressively converted into a smooth quadratic spline made of these parabolic curves. The conversion is achieved by a sequence of predictor-corrector operations enforcing function ( C0) and derivative ( C1) continuity at the cell boundaries using simple analytical expressions for the continuity requirements. The efficacy and accuracy of the current algorithm has been demonstrated using standard test cases involving reconstruction of known static interface shapes and dynamically evolving interfaces in prescribed flow situations. These benchmark studies illustrate that the present algorithm performs excellently as compared to the other interface reconstruction methods available in literature. Quadratic rate of error reduction with respect to grid size has been observed in all the cases with curved interface shapes; only in situations where the interface geometry is primarily flat, the rate of convergence becomes linear with the mesh size. The flow algorithm implemented in the current work is designed to accurately balance the pressure gradients with the surface tension force at any location. As a consequence, it is able to minimize spurious flow currents arising from imperfect normal stress balance at the interface. This has been demonstrated through the standard test problem of an inviscid droplet placed in a quiescent medium. Finally, the direct curvature estimation ability of the current algorithm is illustrated through the coupled multiphase flow problem of a deformable air bubble rising through a column of water.
Gharamti, M. E.
2014-03-01
Isothermal compositional flow models require coupling transient compressible flows and advective transport systems of various chemical species in subsurface porous media. Building such numerical models is quite challenging and may be subject to many sources of uncertainties because of possible incomplete representation of some geological parameters that characterize the system\\'s processes. Advanced data assimilation methods, such as the ensemble Kalman filter (EnKF), can be used to calibrate these models by incorporating available data. In this work, we consider the problem of estimating reservoir permeability using information about phase pressure as well as the chemical properties of fluid components. We carry out state-parameter estimation experiments using joint and dual updating schemes in the context of the EnKF with a two-dimensional single-phase compositional flow model (CFM). Quantitative and statistical analyses are performed to evaluate and compare the performance of the assimilation schemes. Our results indicate that including chemical composition data significantly enhances the accuracy of the permeability estimates. In addition, composition data provide more information to estimate system states and parameters than do standard pressure data. The dual state-parameter estimation scheme provides about 10% more accurate permeability estimates on average than the joint scheme when implemented with the same ensemble members, at the cost of twice more forward model integrations. At similar computational cost, the dual approach becomes only beneficial after using large enough ensembles.
International Nuclear Information System (INIS)
Highlights: ► First time, duplex competitive bead-based flow cytometric immunoassay was developed using ODs. ► Antibody-coated QD detection probes and antigen-immobilized microspheres were synthesized. ► The two model target analytes were low molecular weight compounds of microbial and chemical origin. ► The determination of different water types was possible after simple filtration of samples. - Abstract: In answer to the ever-increasing need to perform the simultaneous analysis of environmental hazards, microcarrier-based multiplex technologies show great promise. Further integration with biofunctionalized quantum dots (QDs) creates new opportunities to extend the capabilities of multicolor flow cytometry with their unique fluorescence properties. Here, we have developed a competitive microbead-based flow cytometric immunoassay using QDs fluorescent labels for simultaneous detection of two analytes, bringing the benefits of sensitive, rapid and easy-of-manipulation analytical tool for environmental contaminants. As model target compounds, the cyanobacterial toxin microcystin-LR and the polycyclic aromatic hydrocarbon compound benzo[a]pyrene were selected. The assay was carried out in two steps: the competitive immunological reaction of multiple targets using their exclusive sensing elements of QD/antibody detection probes and antigen-coated microsphere, and the subsequent flow cytometric analysis. The fluorescence of the QD-encoded microsphere was thus found to be inversely proportional to target analyte concentration. Under optimized conditions, the proposed assay performed well within 30 min for the identification and quantitative analysis of the two environmental contaminants. For microcystin-LR and benzo[a]pyrene, dose–response curves with IC50 values of 5 μg L−1 and 1.1 μg L−1 and dynamic ranges of 0.52–30 μg L−1 and 0.13–10 μg L−1 were obtained, respectively. Recovery was 92.6–106.5% for 5 types of water samples like bottled
A PSO based unified power flow controller for damping of power system oscillations
International Nuclear Information System (INIS)
On the basis of the linearized Phillips-Herffron model of a single-machine power system, we approach the problem of select the best input control signal of the unified power flow controller (UPFC) and design optimal UPFC based damping controller in order to enhance the damping of the power system low frequency oscillations. The potential of the UPFC supplementary controllers to enhance the dynamic stability is evaluated. This controller is tuned to simultaneously shift the undamped electromechanical modes to a prescribed zone in the s-plane. The problem of robustly UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multiobjective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using particle swarm optimization technique (PSO) that has a strong ability to find the most optimistic results. To ensure the robustness of the proposed damping controller, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller is demonstrated through eigenvalue analysis, nonlinear time-domain simulation and some performance indices studies. The results analysis reveals that the tuned PSO based UPFC controller using the proposed multiobjective function has an excellent capability in damping power system low frequency oscillations and enhance greatly the dynamic stability of the power systems. Moreover, the system performance analysis under different operating conditions show that the δE based controller is superior to the mB based controller.
A method for spectral DNS of low Rm channel flows based on the least dissipative modes
Kornet, Kacper; Pothérat, Alban
2015-10-01
We put forward a new type of spectral method for the direct numerical simulation of flows where anisotropy or very fine boundary layers are present. The main idea is to take advantage of the fact that such structures are dissipative and that their presence should reduce the number of degrees of freedom of the flow, when paradoxically, their fine resolution incurs extra computational cost in most current methods. The principle of this method is to use a functional basis with elements that already include these fine structures so as to avoid these extra costs. This leads us to develop an algorithm to implement a spectral method for arbitrary functional bases, and in particular, non-orthogonal ones. We construct a basic implementation of this algorithm to simulate magnetohydrodynamic (MHD) channel flows with an externally imposed, transverse magnetic field, where very thin boundary layers are known to develop along the channel walls. In this case, the sought functional basis can be built out of the eigenfunctions of the dissipation operator, which incorporate these boundary layers, and it turns out to be non-orthogonal. We validate this new scheme against numerical simulations of freely decaying MHD turbulence based on a finite volume code and it is found to provide accurate results. Its ability to fully resolve wall-bounded turbulence with a number of modes close to that required by the dynamics is demonstrated on a simple example. This opens the way to full-blown simulations of MHD turbulence under very high magnetic fields. Until now such simulations were too computationally expensive. In contrast to traditional methods the computational cost of the proposed method, does not depend on the intensity of the magnetic field.
International Nuclear Information System (INIS)
A detailed two-phase flow simulation code with interface tracking method (TPFIT) has been developed at the Japan Atomic Energy Research Institute. This code is based on an advanced gas-liquid interface-tracking model. It is expected that the developed code will be able to simulate two-phase flow behavior in detail. In this paper, single-channel two-phase single-bubble flow experiments are simulated by the TPFIT code. The test section is a circular tube. The test section flow channel diameter and length are 25 mm and 500 mm, respectively. The analyzed model is composed of a tetragonal lattice with a mesh width of 1.0 mm. A non-slip wall and constant exit pressure are selected as boundary conditions. The working fluids are air and water at room temperature and atmospheric pressure. The calculation parameters are the ratio of the bubble equivalence and tube diameters. A single air bubble is set the bottom of the test section at the initial condition. The analyzed lifting bubble velocities were 12 to 17% lower than the experimental values. The analyzed bubble shapes produced by TPFIT code were well conformable with Tomiyama's bubble shape model. The vortexes generated by the near wake of a bubble could be simulated using the TPFIT code. The TPFIT code has a potential to simulate two-phase flow behavior in sufficient detail. (author)
Flow Regime Identification of Gas-liquid Two-phase Flow Based on HHT%基于HHT的气液两相流流型识别
Institute of Scientific and Technical Information of China (English)
孙斌; 张宏建; 程路; 赵玉晓
2006-01-01
A new method to identify flow regime in two-phase flow was presented, based on signal processing of differential pressure using Hilbert Huang transform (HHT). Signals obtained from a Venturi meter were decomposed into different intrinsic mode functions (IMFs) with HHT, then the energy fraction of each intrinsic mode and the mean value of residual function were calculated, from which the rules of flow regime identification were summarized. Experiments were carried out on two-phase flow in the horizontal tubes with 50mm and 40mm inner diameter, while water flowrate was in the range of 1.3m3·h-1 to 10.5m3·h-1, oil flowrate was from 4.2m3·h-1 to 7.0m3·h-1 and gas flowrate from 0 to 15m3·h-1. The results show that the proposed rules have high precision for single phase, bubbly, and slug, plug flow regime identification, which are independent of not only properties of two-phase fluid. In addition, the method can meet the need of industrial application because of its simple calculation.
Some free boundary problems in potential flow regime usinga based level set method
Energy Technology Data Exchange (ETDEWEB)
Garzon, M.; Bobillo-Ares, N.; Sethian, J.A.
2008-12-09
Recent advances in the field of fluid mechanics with moving fronts are linked to the use of Level Set Methods, a versatile mathematical technique to follow free boundaries which undergo topological changes. A challenging class of problems in this context are those related to the solution of a partial differential equation posed on a moving domain, in which the boundary condition for the PDE solver has to be obtained from a partial differential equation defined on the front. This is the case of potential flow models with moving boundaries. Moreover the fluid front will possibly be carrying some material substance which will diffuse in the front and be advected by the front velocity, as for example the use of surfactants to lower surface tension. We present a Level Set based methodology to embed this partial differential equations defined on the front in a complete Eulerian framework, fully avoiding the tracking of fluid particles and its known limitations. To show the advantages of this approach in the field of Fluid Mechanics we present in this work one particular application: the numerical approximation of a potential flow model to simulate the evolution and breaking of a solitary wave propagating over a slopping bottom and compare the level set based algorithm with previous front tracking models.
Novel cobalt base superalloy and its high-temperature flow behavior
Institute of Scientific and Technical Information of China (English)
TANG Chunfeng; PAN Feng; QU Xuanhui; DUAN Baihua; WANG Tianjian; HE Xinbo
2008-01-01
A novel cobalt base superalloy containing titanium and aluminum was investigated through metallography, tensile test, and high-temperature isothermal compression deformation. The results show that proper content of titanium and aluminum with can improve the strength and ductility of the cobalt base superalloy. The Co3(Ti,Al) compound with L12 structure precipitates when the novel superalloy is aged at 800℃ for 20h. The ε phase with hcp structure also precipitates when the superalloy is deformed by 28% and then aged at 650℃ for 4h. The ε phase can exist at 800℃. The superalloy has excellent high-temperature mechanical properties. Its maximum flow stress at 850℃ is in the range of 360-475MPa when the strain rate is between 0.0021 and 2.1 s-1. The flow stress of the superalloy during high-temperature deformation can be described by the Zener-Hollomon parameter with a hot deformation activation energy of 397 kJ.mol-1.
Directory of Open Access Journals (Sweden)
Juan R. Diaz
2014-01-01
Full Text Available Multimedia traffic can be forwarded through a wireless ad hoc network using the available resources of the nodes. Several models and protocols have been designed in order to organize and arrange the nodes to improve transmissions along the network. We use a cluster-based framework, called MWAHCA architecture, which optimizes multimedia transmissions over a wireless ad hoc network. It was proposed by us in a previous research work. This architecture is focused on decreasing quality of service (QoS parameters like latency, jitter, and packet loss, but other network features were not developed, like load balance or fault tolerance. In this paper, we propose a new fault tolerance mechanism, using as a base the MWAHCA architecture, in order to recover any multimedia flow crossing the wireless ad hoc network when there is a node failure. The algorithm can run independently for each multimedia flow. The main objective is to keep the QoS parameters as low as possible. To achieve this goal, the convergence time must be controlled and reduced. This paper provides the designed protocol, the analytical model of the algorithm, and a software application developed to test its performance in a real laboratory.
Air-breathing membraneless laminar flow-based fuel cells: Do they breathe enough oxygen?
International Nuclear Information System (INIS)
Highlights: ► Limiting factors of air-breathing laminar-flow based fuel cell (LFFC) is analyzed. ► A numerical model for LFFC is developed. ► Air breathing process is not a limiting factor at the present stage. ► Oxygen starvation is significant when the cell current density exceeds 200 mA cm−2. - Abstract: Laminar flow-based fuel cell (LFFC) is a relatively new type of fuel cell that does not require the use of proton exchange membrane. While the first-generation LFFC uses dissolved oxygen at the cathode, the second-generation LFFC (2G-LFFC) adopts a more advanced air-breathing design for achieving high power density. The architecture and operational mechanisms of a 2G-LFFC are more complex. In order to gain detailed understanding of the 2G-LFFC, an integrated CFD/electrochemical kinetics modeling study has been conducted to analyze the cell limiting factors and sufficiency of the oxidant supply from air. It is found that under most typical operating conditions, the 2G-LFFC free-breathing mode can supply sufficient oxygen to the electrode reactive surface for cathode half-cell reaction, indicating that the air breathing process is not a limiting factor to the cell performance. However, oxygen starvation will become a major performance limiting factor when the anode is enhanced for higher current density. The results presented in this paper provide useful design guidance for future development of LFFC
The efficacy of centralized flow rate control in 802.11-based wireless mesh networks
Jamshaid, K.
2013-06-13
Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.
Heat-Flow-Driven Oligonucleotide Gelation Separates Single-Base Differences.
Morasch, Matthias; Braun, Dieter; Mast, Christof B
2016-06-01
DNA phase transitions are often induced by the addition of condensation agents or by dry concentration. Herein, we show that the non-equilibrium setting of a moderate heat flow across a water-filled chamber separates and gelates DNA strands with single-base resolution. A dilute mix of DNA with two slightly different gel-forming sequences separates into sequence-pure hydrogels under constant physiological solvent conditions. A single base change in a 36 mer DNA inhibits gelation. Only sequences with the ability to form longer strands are concentrated, further elongated, and finally gelated by length-dependent thermal trapping. No condensation agents, such as multivalent ions, were added. Equilibrium aggregates from dry concentration did not show any sequence separation. RNA is expected to behave identically owing to its equal thermophoretic properties. The highly sequence-specific phase transition points towards new possibilities for non-equilibrium origins of life. PMID:27060490
Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests.
He, Wei; Wang, Yueke; Xing, Kefei; Deng, Wei; Zhang, Zelong
2016-01-01
A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF) for space instruments. A model for the system functional error rate (SFER) is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA) is presented. Based on experimental results of different ions (O, Si, Cl, Ti) under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10-3(error/particle/cm2), while the MTTF is approximately 110.7 h. PMID:27583533
Review of Fluorescence-Based Velocimetry Techniques to Study High-Speed Compressible Flows
Bathel, Brett F.; Johansen, Criag; Inman, Jennifer A.; Jones, Stephen B.; Danehy, Paul M.
2013-01-01
This paper reviews five laser-induced fluorescence-based velocimetry techniques that have been used to study high-speed compressible flows at NASA Langley Research Center. The techniques discussed in this paper include nitric oxide (NO) molecular tagging velocimetry (MTV), nitrogen dioxide photodissociation (NO2-to-NO) MTV, and NO and atomic oxygen (O-atom) Doppler-shift-based velocimetry. Measurements of both single-component and two-component velocity have been performed using these techniques. This paper details the specific application and experiment for which each technique has been used, the facility in which the experiment was performed, the experimental setup, sample results, and a discussion of the lessons learned from each experiment.
Research on the Food Safety Information Management System based on the Data Flow Technology
Directory of Open Access Journals (Sweden)
Zhang Yonghua
2015-09-01
Full Text Available Food is the paramount necessity of the people. Food is the material foundation of human survival and food safety is the most basic insurance. Food safety crisis management mechanism of local government has an important significance on deepening the theoretical research of food safety crisis management perfecting the food safety management function and management mechanism. This study conducted a deep research on the food security issues from public management crisis management theory, institutional economics and other theories; and based on the food security crisis management it carried a research on mechanism in order to put forward feasible policies and suggestions on food safety problem for local government. The food safety information management system based on data flow technology is also constructed in this study.
Development of a Water Based, Critical Flow, Non-Vapor Compression cooling Cycle
Energy Technology Data Exchange (ETDEWEB)
Hosni, Mohammad H.
2014-03-30
Expansion of a high-pressure liquid refrigerant through the use of a thermostatic expansion valve or other device is commonplace in vapor-compression cycles to regulate the quality and flow rate of the refrigerant entering the evaporator. In vapor-compression systems, as the condensed refrigerant undergoes this expansion, its pressure and temperature drop, and part of the liquid evaporates. We (researchers at Kansas State University) are developing a cooling cycle that instead pumps a high-pressure refrigerant through a supersonic converging-diverging nozzle. As the liquid refrigerant passes through the nozzle, its velocity reaches supersonic (or critical-flow) conditions, substantially decreasing the refrigerant’s pressure. This sharp pressure change vaporizes some of the refrigerant and absorbs heat from the surrounding conditions during this phase change. Due to the design of the nozzle, a shockwave trips the supersonic two-phase refrigerant back to the starting conditions, condensing the remaining vapor. The critical-flow refrigeration cycle would provide space cooling, similar to a chiller, by running a secondary fluid such as water or glycol over one or more nozzles. Rather than utilizing a compressor to raise the pressure of the refrigerant, as in a vapor-cycle system, the critical-flow cycle utilizes a high-pressure pump to drive refrigerant liquid through the cooling cycle. Additionally, the design of the nozzle can be tailored for a given refrigerant, such that environmentally benign substances can act as the working fluid. This refrigeration cycle is still in early-stage development with prototype development several years away. The complex multi-phase flow at supersonic conditions presents numerous challenges to fully understanding and modeling the cycle. With the support of DOE and venture-capital investors, initial research was conducted at PAX Streamline, and later, at Caitin. We (researchers at Kansas State University) have continued development
Energy Technology Data Exchange (ETDEWEB)
Marc Cremer; Kirsi St. Marie; Dave Wang
2003-04-30
This is the first Semiannual Technical Report for DOE Cooperative Agreement No: DE-FC26-02NT41580. The goal of this project is to systematically assess the sensitivity of furnace operational conditions to burner air and fuel flows in coal fired utility boilers. Our approach is to utilize existing baseline furnace models that have been constructed using Reaction Engineering International's (REI) computational fluid dynamics (CFD) software. Using CFD analyses provides the ability to carry out a carefully controlled virtual experiment to characterize the sensitivity of NOx emissions, unburned carbon (UBC), furnace exit CO (FECO), furnace exit temperature (FEGT), and waterwall deposition to burner flow controls. The Electric Power Research Institute (EPRI) is providing co-funding for this program, and instrument and controls experts from EPRI's Instrument and Controls (I&C) Center are active participants in this project. This program contains multiple tasks and good progress is being made on all fronts. A project kickoff meeting was held in conjunction with NETL's 2002 Sensors and Control Program Portfolio Review and Roadmapping Workshop, in Pittsburgh, PA during October 15-16, 2002. Dr. Marc Cremer, REI, and Dr. Paul Wolff, EPRI I&C, both attended and met with the project COR, Susan Maley. Following the review of REI's database of wall-fired coal units, the project team selected a front wall fired 150 MW unit with a Riley Low NOx firing system including overfire air for evaluation. In addition, a test matrix outlining approximately 25 simulations involving variations in burner secondary air flows, and coal and primary air flows was constructed. During the reporting period, twenty-two simulations have been completed, summarized, and tabulated for sensitivity analysis. Based on these results, the team is developing a suitable approach for quantifying the sensitivity coefficients associated with the parametric tests. Some of the results of the CFD
An Early Warning System from debris flows based on ground vibration monitoring data
Arattano, Massimo; Coviello, Velio
2015-04-01
-2014. The algorithm is based on the real time processing of ground vibration data detected by three vertical geophones. During the testing period, two debris flow events occurred that were both correctly detected by the algorithm with a relatively limited number of false alarms.
Huang, Ming-Chieh
This dissertation presents a method and apparatus for rapid measurement of fluid pH value in a microscale volume. The fluorescence of indicators immobilized on polymer microbeads is a function of the concentration of an analyte. This was determined in a silicon microfabricated flow channel. The sizes of microbeads can be determined by the scattering signal, so this system could be used to analyze several analytes at the same time by using beads of different sizes which are sensitive to different analytes. The fluorescent indicator Carboxy-SNAFL I was immobilized by Molecular Probes on amino-functionalized polystyrene beads of 5 mum diameter. These pH-sensitive microbeads were used in this apparatus to measure the pH of sample solutions. The intensities of two fluorescent peaks (at 560 nm and at 620 run) were measured, their ratio was dependent on the pH value of the analyte. We discriminated bead diameter by monitoring the intensity of the scattered excitation signal. In the measurement of the light scattering signal, the standard deviation/bead diameter (SD/D) for the 10.3 mum beads was ˜26%. The major error is caused by varying positions of the beads in the microchannel. In order to decrease the SD/D of scattering signal and thus increase the number of distinct bead types that can be identified, a low Reynolds number silicon/pyrex microfluidic device that forces particles flowing in a microchannel to a tightly-focused equilibrium position was designed and fabricated. When scattering signals from 10 mum polymer beads were measured, we observed that the tight equilibrium position attained by the particles resulted in a much smaller standard deviation of the scattering signal than was observed in other microflow channel devices that did not focus the particles to equilibrium positions. Another applications of this device is also discussed. We show that this particle-focusing channel may be used in a micro-fluidic flow sensor.
Developing Training Image-Based Priors for Inversion of Subsurface Geophysical and Flow Data
Caers, J.
2014-12-01
Forecasting in subsurface formations, whether for groundwater, storage or oil & gas production, can rely on a wealth of geological information. Currently, most of this information remains underused in both the theory and practice of forecasting based on inverse models which heavily relies on spatial covariances and multi-Gaussian theory. By means of real field studies, I will provide an outline of how such geological information can be accounted through the construction and validation of a large set of training images and the generation of model realizations with MPS (multiple-point geostatistics). Often most critical in solving such inverse problems is the development of prior models that are later used for posterior sampling or stochastic search. I propose therefore a two-stage approach where the first stage consists of a validation of the training image-based prior with the geophysical and flow data. This stage will require only the generation of a few (100s) geological models and the forward modeling of the data response on these models. For geophysical data, the validation consists of comparing histograms of multi-scale wavelet transforms between the forward models and the field data. For flow data, the validation is based on a reduction of dimensionality of the forward response and the data using multi-dimensional scaling. The outcome of this validation is an estimate of the prior probability assigned to each training image, with several training images getting assigned zero probability (incompatible with field data). These prior probabilities are used in the second stage to actually invert for the data using stochastic search. In such stochastic search, I avoid parameterizing the model space and present methods that efficiently perform a direct search in the space of the validated training image-based prior model realizations.
Mr.P.Nagasekhar Reddy
2014-01-01
The Unified Power Flow Controller (UPFC) is used to control the flow of power in the transmission systems by controlling the impedance, voltage magnitude and phase angle. The Unified Power Flow Controller (UPFC) is the most versatile and complex power electronic equipment that has emerged for the control and optimization of power flow in electrical power transmission system. Installing the UPFC makes it possible to control an amount of real power flow through the line. This co...
Node-based parallel mesh generation and finite element solver for high speed compressible flows
International Nuclear Information System (INIS)
A node-based parallel mesh generation and finite element procedure for high speed compressible flows is presented. In general, the numerical analysis of flows with shock waves requires very fine computational grids and consumes a lot of computing time. For such large amounts of calculations, parallel computing is very effective. However, a lot of parallel techniques for CFD focus strictly on the solution of the system of equations, while the mesh generation process is not parallelized in many cases. In the present work, we attempt seamless parallel computing involving pre-processing and main-processing for compressible flows. The finite elements are generated in the local area around each node and the finite element assembly operations are carried out node-by-node. In this method, both pre-processing and main-processing are parallelized by means of the nodal identification number. Load balancing is achieved by simply allocating equal number of nodes to each processor. Furthermore, the amount of the communication among processors is minimized by reordering the nodal identification number using the parallel graph partitioning library, ParMETIS. As for the numerical scheme for compressible Euler equations, the two-step Taylor-Galerkin method is employed. In order to remove the numerical instability, artificial viscosity based on the Lapidus model is applied. The concept of an element in the usual FEM is represented by a data structure of the connectivity between a central node and associated satellite nodes. The communication among different processors is required if and only if associated satellite nodes exist in other processors. The present method is implemented on distributed memory systems such as a PC cluster and a commercial massively paralleled computer. The performance of the method is illustrated by computing of supersonic flows over a forward facing step. These examples show that crisp shock waves are effectively computed on multiple processors. The total
Canacci, Victor A.; Braun, M. Jack
1994-01-01
The experimental approach presented here offers a nonintrusive, qualitative and quantitative evaluation of full field flow patterns applicable in various geometries in a variety of fluids. This Full Flow Field Tracking (FFFT) Particle Image Velocimetry (PIV) technique, by means of particle tracers illuminated by a laser light sheet, offers an alternative to Laser Doppler Velocimetry (LDV), and intrusive systems such as Hot Wire/Film Anemometry. The method makes obtainable the flow patterns, and allows quantitative determination of the velocities, accelerations, and mass flows of an entire flow field. The method uses a computer based digitizing system attached through an imaging board to a low luminosity camera. A customized optical train allows the system to become a long distance microscope (LDM), allowing magnifications of areas of interest ranging up to 100 times. Presented in addition to the method itself, are studies in which the flow patterns and velocities were observed and evaluated in three distinct geometries, with three different working fluids. The first study involved pressure and flow analysis of a brush seal in oil. The next application involved studying the velocity and flow patterns in a cowl lip cooling passage of an air breathing aircraft engine using water as the working fluid. Finally, the method was extended to a study in air to examine the flows in a staggered pin arrangement located on one side of a branched duct.
Medhi, Biswajit; Hegde, Gopalakrishna M; Gorthi, Sai Siva; Reddy, Kalidevapura Jagannath; Roy, Debasish; Vasu, Ram Mohan
2016-08-01
A simple noninterferometric optical probe is developed to estimate wavefront distortion suffered by a plane wave in its passage through density variations in a hypersonic flow obstructed by a test model in a typical shock tunnel. The probe has a plane light wave trans-illuminating the flow and casting a shadow of a continuous-tone sinusoidal grating. Through a geometrical optics, eikonal approximation to the distorted wavefront, a bilinear approximation to it is related to the location-dependent shift (distortion) suffered by the grating, which can be read out space-continuously from the projected grating image. The processing of the grating shadow is done through an efficient Fourier fringe analysis scheme, either with a windowed or global Fourier transform (WFT and FT). For comparison, wavefront slopes are also estimated from shadows of random-dot patterns, processed through cross correlation. The measured slopes are suitably unwrapped by using a discrete cosine transform (DCT)-based phase unwrapping procedure, and also through iterative procedures. The unwrapped phase information is used in an iterative scheme, for a full quantitative recovery of density distribution in the shock around the model, through refraction tomographic inversion. Hypersonic flow field parameters around a missile-shaped body at a free-stream Mach number of ∼8 measured using this technique are compared with the numerically estimated values. It is shown that, while processing a wavefront with small space-bandwidth product (SBP) the FT inversion gave accurate results with computational efficiency; computation-intensive WFT was needed for similar results when dealing with larger SBP wavefronts. PMID:27505389
A calorimetric system based on the LKB 10700-1 flow microcalorimeter
International Nuclear Information System (INIS)
An electrically calibrated and computer-controlled apparatus based on the LKB 10700-1 flow microcalorimeter was set up and tested by determining the enthalpies of dilution of aqueous solutions of sucrose and HCl at 298.15 K. The obtained results are in good agreement with the corresponding reference values recommended in the literature. The quality of the calorimetric signal in terms of noise, linearity and baseline drift, and the instrument time constant were analyzed. Also investigated were the influences of the flow rate and of the viscosity of the calorimetric liquid on the position of the baseline. The new calibration system enables powers ∼25 times smaller than those possible with the original one to be released inside the calorimetric cells. Electrical calibrations carried out with water as the sole calorimetric liquid indicated that the precision of the calibration constant, ε, quickly improved from ∼9% to ∼0.4% with the increase of the input power, P, from ∼2 µW to ∼50 µW, and stabilized at ∼0.1% for P ≥ 100 µW. The calibration constant was also found to linearly increase with the flow rate of the calorimetric liquid and to vary by less than 1% over a period of eight months under similar experimental conditions. Finally a new experimental procedure for heat of dilution measurements, which combines calibration and experiment in a single run, was evaluated. This method allows a significant economy in experiment time with apparently no accuracy loss relative to the conventional procedure recommended in the literature
A lightweight, flow-based toolkit for parallel and distributed bioinformatics pipelines
Directory of Open Access Journals (Sweden)
Cieślik Marcin
2011-02-01
Full Text Available Abstract Background Bioinformatic analyses typically proceed as chains of data-processing tasks. A pipeline, or 'workflow', is a well-defined protocol, with a specific structure defined by the topology of data-flow interdependencies, and a particular functionality arising from the data transformations applied at each step. In computer science, the dataflow programming (DFP paradigm defines software systems constructed in this manner, as networks of message-passing components. Thus, bioinformatic workflows can be naturally mapped onto DFP concepts. Results To enable the flexible creation and execution of bioinformatics dataflows, we have written a modular framework for parallel pipelines in Python ('PaPy'. A PaPy workflow is created from re-usable components connected by data-pipes into a directed acyclic graph, which together define nested higher-order map functions. The successive functional transformations of input data are evaluated on flexibly pooled compute resources, either local or remote. Input items are processed in batches of adjustable size, all flowing one to tune the trade-off between parallelism and lazy-evaluation (memory consumption. An add-on module ('NuBio' facilitates the creation of bioinformatics workflows by providing domain specific data-containers (e.g., for biomolecular sequences, alignments, structures and functionality (e.g., to parse/write standard file formats. Conclusions PaPy offers a modular framework for the creation and deployment of parallel and distributed data-processing workflows. Pipelines derive their functionality from user-written, data-coupled components, so PaPy also can be viewed as a lightweight toolkit for extensible, flow-based bioinformatics data-processing. The simplicity and flexibility of distributed PaPy pipelines may help users bridge the gap between traditional desktop/workstation and grid computing. PaPy is freely distributed as open-source Python code at http://muralab.org/PaPy, and
Fitzgerald, Alex; Roy, James W.; Smith, James E.
2015-09-01
Elevated levels of nutrients, especially phosphorus, in urban streams can lead to eutrophication and general degradation of stream water quality. Contributions of phosphorus from groundwater have typically been assumed minor, though elevated concentrations have been associated with riparian areas and urban settings. The objective of this study was to investigate the importance of groundwater as a pathway for phosphorus and nitrogen input to a gaining urban stream. The stream at the 28-m study reach was 3-5 m wide and straight, flowing generally eastward, with a relatively smooth bottom of predominantly sand, with some areas of finer sediments and a few boulders. Temperature-based methods were used to estimate the groundwater flux distribution. Detailed concentration distributions in discharging groundwater were mapped using in-stream piezometers and diffusion-based peepers, and showed elevated levels of soluble reactive phosphorus (SRP) and ammonium compared to the stream (while nitrate levels were lower), especially along the south bank, where groundwater fluxes were lower and geochemically reducing conditions dominated. Field evidence suggests the ammonium may originate from nearby landfills, but that local sediments likely contribute the SRP. Ammonium and SRP mass discharges with groundwater were then estimated as the product of the respective concentration distributions and the groundwater flux distribution. These were determined as approximately 9 and 200 g d-1 for SRP and ammonium, respectively, which compares to stream mass discharges over the observed range of base flows of 20-1100 and 270-7600 g d-1, respectively. This suggests that groundwater from this small reach, and any similar areas along Dyment's Creek, has the potential to contribute substantially to the stream nutrient concentrations.
An Evolutionary Approach to the Delineation of Functional Areas Based on Travel-to-work Flows
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
This paper presents a new approach to the delineation of local labor markets based on evolutionary computation. The aim of the exercise is the division of a given territory into functional regions based on travel-to-work flows. Such regions are defined so that a high degree of inter-regional separation and of intra-regional integration in both cases in terms of commuting flows is guaranteed.Additional requirements include the absence of overlap between delineated regions and the exhaustive coverage of the whole territory.The procedure is based on the maximization of a fitness function that measures aggregate intra-region interaction under constraints of inter-region separation and minimum size. In the experimentation stage, two variations of the fitness function are used, and the process is also applied as a final stage for the optimization of the results from one of the most successful existing methods, which are used by the British authorities for the delineation of travel-to-work areas (TTWAs). The empirical exercise is conducted using real data for a sufficiently large territory that is considered to be representative given the density and variety of travel-to-work patterns that it embraces. The paper includes the quantitative comparison with alternative traditional methods, the assessment of the performance of the set of operators which has been specifically designed to handle the regionalization problem and the evaluation of the convergence process. The robustness of the solutions, something crucial in a research and policy-making context, is also discussed in the paper.
Azad, Ariful; Rajwa, Bartek; Pothen, Alex
2016-01-01
We describe algorithms for discovering immunophenotypes from large collections of flow cytometry samples and using them to organize the samples into a hierarchy based on phenotypic similarity. The hierarchical organization is helpful for effective and robust cytometry data mining, including the creation of collections of cell populations’ characteristic of different classes of samples, robust classification, and anomaly detection. We summarize a set of samples belonging to a biological class or category with a statistically derived template for the class. Whereas individual samples are represented in terms of their cell populations (clusters), a template consists of generic meta-populations (a group of homogeneous cell populations obtained from the samples in a class) that describe key phenotypes shared among all those samples. We organize an FC data collection in a hierarchical data structure that supports the identification of immunophenotypes relevant to clinical diagnosis. A robust template-based classification scheme is also developed, but our primary focus is in the discovery of phenotypic signatures and inter-sample relationships in an FC data collection. This collective analysis approach is more efficient and robust since templates describe phenotypic signatures common to cell populations in several samples while ignoring noise and small sample-specific variations. We have applied the template-based scheme to analyze several datasets, including one representing a healthy immune system and one of acute myeloid leukemia (AML) samples. The last task is challenging due to the phenotypic heterogeneity of the several subtypes of AML. However, we identified thirteen immunophenotypes corresponding to subtypes of AML and were able to distinguish acute promyelocytic leukemia (APL) samples with the markers provided. Clinically, this is helpful since APL has a different treatment regimen from other subtypes of AML. Core algorithms used in our data analysis are
Huang, Xiaolin; Aguilar, Zoraida P; Xu, Hengyi; Lai, Weihua; Xiong, Yonghua
2016-01-15
Membrane-based lateral flow immunochromatographic strip (LFICS) is widely used in various fields because of its simplicity, rapidity (detection within 10min), and low cost. However, early designs of membrane-based LFICS for preliminary screening only provide qualitative ("yes/no" signal) or semi-quantitative results without quantitative information. These designs often suffer from low-signal intensity and poor sensitivity and are only capable of single analyte detection, not simultaneous multiple detections. The performance of existing techniques used for detection using LFICS has been considerably improved by incorporating different kinds of nanoparticles (NPs) as reporters. NPs can serve as alternative labels and improve analytical sensitivity or limit of detection of LFICS because of their unique properties, such as optical absorption, fluorescence spectra, and magnetic properties. The controlled manipulation of NPs allows simultaneous or multiple detections by using membrane-based LFICS. In this review, we discuss how colored (e.g., colloidal gold, carbon, and colloidal selenium NPs), luminescent (e.g., quantum dots, up-converting phosphor NPs, and dye-doped NPs), and magnetic NPs are integrated into membrane-based LFICS for the detection of target analytes. Gold NPs are also featured because of their wide applications. Different types and unique properties of NPs are briefly explained. This review focuses on examples of NP-based LFICS to illustrate novel concepts in various devices with potential applications as screening tools. This review also highlights the superiority of NP-based approaches over existing conventional strategies for clinical analysis, food safety, and environmental monitoring. This paper is concluded by a short section on future research trends regarding NP-based LFICS. PMID:26318786
Directory of Open Access Journals (Sweden)
Yao Xiao
2015-01-01
Full Text Available This paper aimed to analyze the influence of drivers’ behavior of phone use while driving on traffic flow, including both traffic efficiency and traffic safety. An improved cellular automaton model was proposed to simulate traffic flow with distracted drivers based on the Nagel-Schreckenberg model. The driving characters of drivers using a phone were first discussed and a value representing the probability to use a phone while driving was put into the CA model. Simulation results showed that traffic flow rate was significantly reduced if some drivers used a phone compared to no phone use. The flow rate and velocity decreased as the proportion of drivers using a phone increased. While, under low density, the risk of traffic decreased first and then increased as the distracted drivers increased, the distracted behavior of drivers, like using a phone, could reduce the flow rate by 5 percent according to the simulation.
Institute of Scientific and Technical Information of China (English)
Gaiping Zhao; Jie Wu; Shixiong Xu; M. W. Collins; Quan Long; Carola S. K(o)nig; Yuping Jiang; Jian Wang; A. R. Padhani
2007-01-01
A coupled intravascular-transvascular-interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network.This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels.Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille's law and Darcy's law, respectively, transvascular flow is described by Starling's law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convectionon the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.
International Nuclear Information System (INIS)
An approach for unification of theoretical critical hea flux (CHF) prediction is suggested based on liquid film dryout for flow boiling in uniformly heated tubes. The model successively calculates CHF for bubbly and annular flow with incorporating flow regime transition criteria using a single governing equation for the liquid film on a heated wall with regard to the mass transfer at the film interface. Assessment was conducted with large experimental data sets (9821) from KAIST CHF data bank and the model was proved to have reasonable prediction accuracy with the average error and RMS error of 0.8% and 19.2%, respectively. The error and parametric CHF trend analysis of the model revealed the need for the consideration of slug flow and mass transfer terms in bubbly flow for a more reliable model. (author)
International Nuclear Information System (INIS)
A unified critical heat flux prediction model for flow boiling in uniformly heated tubes is suggested based on liquid film dryout. The model successively calculates CHF for bubbly and annular flow with implication of flow regime transition criteria using single governing equation for the liquid film on a heated wall with regard to the mass transfer at the film interface. Assessment was conducted with large experimental data (9821) from KAIST CHF data bank and the model was proved to have reasonable prediction accuracy with the average error and RMS error of 0.8 % and 19.2 %, respectively. The error and parametric CHF trend analysis of the model revealed needs for the implication of slug flow and mass transfer terms in bubbly flow for a more reliable model
CCFL model based on the hyperbolic two-fluid equations and non-uniform flow interface shape
International Nuclear Information System (INIS)
The maximum flow rates of gas and liquid phases which flow in opposite-directions (counter-current flow) are limited by a phenomenon known as a Counter-Current Flow Limitation (CCFL or Flooding). The mass and momentum conservation equations for each phase were established to build a first-order hyperbolic partial derivative equations system. A new CCFL model is developed based on the characteristic equation of the hyperbolic PDE system. The present model has its application to the case in which a non-uniform flow is developed around a square or sharp-edged entrance of liquid phase. The model is able to be used to predict the operating-limit of components in which mass and heat transfer are taking place between liquid and gas phases
Wakatsuki, Tsuyoshi; Sato, Masato; Inomata, Yasuhiro; Takeda, Naofumi; Aoki, Shinya
2016-04-01
In Japan, debris flows generally occur by fluidization of colluviums of soil slips after heavy rainfall on steep slopes. For the reduction of debris-flow disasters, the relationship among geomorphic quantities of the mountainous small drainage basin, the arrival of the debris flow to the basin outlet, and rainfall characteristics was examined by using the distribution maps of slope movements and digital elevation models (DEM) on five granite slopes. The results showed that there were geomorphic thresholds determining the lower limit of the arrival of the debris flow to the basin outlet based on the drainage area and the relief ratio. The geomorphic thresholds become smaller with an increase in rainfall amount, which increases the debris-flow risk in many basins.
Optical flow based Kalman filter for body joint prediction and tracking using HOG-LBP matching
Nair, Binu M.; Kendricks, Kimberley D.; Asari, Vijayan K.; Tuttle, Ronald F.
2014-03-01
We propose a real-time novel framework for tracking specific joints in the human body on low resolution imagery using optical flow based Kalman tracker without the need of a depth sensor. Body joint tracking is necessary for a variety of surveillance based applications such as recognizing gait signatures of individuals, identifying the motion patterns associated with a particular action and the corresponding interactions with objects in the scene to classify a certain activity. The proposed framework consists of two stages; the initialization stage and the tracking stage. In the initialization stage, the joints to be tracked are either manually marked or automatically obtained from other joint detection algorithms in the first few frames within a window of interest and appropriate image descriptions of each joint are computed. We employ the use of a well-known image coding scheme known as the Local Binary Patterns (LBP) to represent the joint local region where this image coding removes the variance to non-uniform lighting conditions as well as enhances the underlying edges and corner. The image descriptions of the joint region would then include a histogram computed from the LBP-coded ROI and a HOG (Histogram of Oriented Gradients) descriptor to represent the edge information. Next the tracking stage can be divided into two phases: Optical flow based detection of joints in corresponding frames of the sequence and prediction /correction phases of Kalman tracker with respect to the joint coordinates. Lucas Kanade optical flow is used to locate the individual joints in consecutive frames of the video based on their location in the previous frame. But more often, mismatches can occur due to the rotation of the joint region and the rotation variance of the optical flow matching technique. The mismatch is then determined by comparing the joint region descriptors using Chi-squared metric between a pair of frames and depending on this statistic, either the prediction
Directory of Open Access Journals (Sweden)
P. Nair
2010-01-01
Full Text Available The development of a numerical procedure based on AUSM+-UP scheme using higher order accurate reconstruction method is presented. A code based on this is used for the simulation of film cooling for reentry module. Here the convective fluxes are evaluated using AUSM+-UP scheme. Least square based derivative evaluation is used to compute diffusive fluxes. The numerical code has been successfully validated using standard experimental data for counter flow injection. Analysis has been carried out for a simple axisymmetric reentry module with and without film cooling, for a free stream Mach number of 8.0. The predicted adiabatic wall temperatures were compared for both the cases. Film cooling is found to be effective for this configuration and injected coolant remains confined to the boundary layer formed by the free stream from nose tip to the aft end of the module. Numerical simulation of film cooling provides vital information required for design of effective cooling system such as number of counter flow injectors, their dimensions and locations, injection pressure and temperature, mass flow rate required etc.
AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System
Directory of Open Access Journals (Sweden)
Mohammed Abdeljalil DJEHAF
2014-02-01
Full Text Available Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current and FACTS (Flexible AC Transmission Systems provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system interconnection and for control of power flow as well. The major benefit of HVDC is its incorporated ability for fault-current blocking, which is not possible with synchronous AC links. In addition, HVDC can effectively support the surrounding AC systems in case of transient fault conditions and it serves as firewall against cascading disturbances. This paper presents a comparison between HVDC link and an HVAC link in a 29 Bus multimachine system, based on load flow analysis using Newton-Raphson method for the AC link case, and sequential method for the HVDC link case.
A Theory for Optical flow-based Transport on Image Manifolds
Nagaraj, Sriram; Baraniuk, Richard G
2011-01-01
An image articulation manifold (IAM) is the collection of images formed when an object is articulated in front of a camera. IAMs arise in a variety of image processing and computer vision applications, where they provide a natural low-dimensional embedding of the collection of high-dimensional images. To date IAMs have been studied as embedded submanifolds of Euclidean spaces. Unfortunately, their promise has not been realized in practice, because real world imagery typically contains sharp edges that render an IAM non-differentiable and hence non-isometric to the low-dimensional parameter space under the Euclidean metric. As a result, the standard tools from differential geometry, in particular using linear tangent spaces to transport along the IAM, have limited utility. In this paper, we explore a nonlinear transport operator for IAMs based on the optical flow between images and develop new analytical tools reminiscent of those from differential geometry using the idea of optical flow manifolds (OFMs). We d...
Institute of Scientific and Technical Information of China (English)
Liu Hui; He Shunli
2008-01-01
Segmental perforation is widely used for horizontal wells.However,the flow of fluid in porous media is a com-plex problem.Using the Fourier transform,principle of potential superposition,trigonometric function transform,as-ymptotic analyses,a pressure solution of a pseudo steady-state flow model in 3D circular-boxed media has been estab-lished.Comparing with the productivity of vertical wells,an equivalence radius model can be obtained.Based on the model,a method of evaluating the productivity of segmental perforation horizontal well is presented by means of principle of superposition.It shows that the equivalence radius is different for various positions of horizontal wells;the output of both ends of horizontal wells is greater than the others under the same length of perforation interval;it is more important to obtain high productivity by increasing the length of perforation interval than enlarging the spacing between perforation intervals.The result of this research can be used to ascertain the yield of each perforated interval.
Directory of Open Access Journals (Sweden)
Hao Lei
2015-12-01
Full Text Available Trip travel time reliability is an important measure of transportation system performance and a key factor affecting travelers’ choices. This paper explores a method for estimating travel time distributions for corridors that contain multiple bottlenecks. A set of analytical equations are used to calculate the number of queued vehicles ahead of a probe vehicle and further capture many important factors affecting travel times: the prevailing congestion level, queue discharge rates at the bottlenecks, and flow rates associated with merges and diverges. Based on multiple random scenarios and a vector of arrival times, the lane-by-lane delay at each bottleneck along the corridor is recursively estimated to produce a route-level travel time distribution. The model incorporates stochastic variations of bottleneck capacity and demand and explains the travel time correlations between sequential links. Its data needs are the entering and exiting flow rates and a sense of the lane-by-lane distribution of traffic at each bottleneck. A detailed vehicle trajectory data-set from the Next Generation SIMulation (NGSIM project has been used to verify that the estimated distributions are valid, and the sources of estimation error are examined.