Flow Splitting Research Articles

Isolation and Identification of Two Phenolic Compounds from a Moderately Cytotoxic Fraction of Cousinia verbascifolia Bunge.

Background:Little information is available about chemical components of the Cousinia genus. A primary cytotoxicity screening on Cousinia verbascifolia showed moderate cytotoxic activity against OVCAR-3 ovarian and HT-29 colon cancer cells. Therefore, the aim of this study is a phytochemical investigation to identify the compounds responsible for this bioactivity.Materials and Methods:Extraction was done through percolation and fractionations by reverse phase column chromatography and normal column chromatography. Using standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay Fr.b8 with moderate cytotoxicity was selected for identification of major components. Fr.b8 was subjected to polyamide column chromatography. More purification was done using a new modified recycle high-performance liquid chromatography (HPLC) with flow splitter.Results:Two known compounds: Apigenin (flavone) and caffeic acid (phenolic acid) were obtained from phenolic bioactive fraction for the first time from this plant.Conclusions:Apigenin and caffeic acid with known antitumor and matrix metalloproteinase inhibitory effects seem to be the bioactive components responsible for moderate cytotoxicity of phenolic fraction. Recycle HPLC following with flow splitting is a new method useful for isolation of closely eluted compounds in HPLC chromatogram.

Simultaneous Forming and Joining by Linear Flow Splitting - From Basic Mechanisms to the Continuous Manufacturing Line

Abstract The public demand for an efficient and sustainable use of energy resources has led to a more consequent use of lightweight constructions. In the automotive sector for example, weight reduction is achieved by a structural construction with branched parts by reinforcing ribs or by a combination of materials with different strengths. To join these assemblies, different joining by forming processes are used. Mostly forming and joining takes place in separate processes. The innovative forming technology of linear flow splitting offers advantages with regard to the production of lightweight parts and the joining by plastic deformation at the same time. Residual stresses in the manufactured profiles are used in the linear flow splitting process for an additional mechanical joining of profiles and other parts. Here, the forming and mechanical joining zones do not coincide, which is different to conventional joining technologies. The study at hand presents the tensile joining mechanism in the forming process of linear flow splitting in detail and shows the implemented manufacturing line for simultaneous forming and joining in the process of linear flow splitting.

Manufacturing‐induced material properties of linear flow split and linear bend split profiles

In this work the two massive forming processes linear flow splitting and linear bend splitting, which generate profiles from sheet metal, are evaluated with respect to characteristic manufacturing‐induced material properties of the produced parts. Resulting microstructural features such as grain size and shape as well as crystallographic textures are linked to mechanical properties such as strength, ductility and anisotropic elasticity and general rules for their evolution are defined. Residual stress distributions are detailed and discussed with regard to the causing geometrical and forming process related aspects. The aim of this paper is to give a comprehensive overview of the properties of profiles produced by linear flow splitting and linear bend splitting and to illustrate general rules for their evolution in order to provide guidelines for an optimized product development process which allows a beneficial use of the manufacturing‐induced properties.

Analysis of different fatigue damage accumulation theories and damage parameters based on experiments with the steel HC340LA

Different theories for the fatigue life estimation under variable amplitude loading were analysed and compared based on experimental test of specimens of the steel HC340LA. Some of the most representative models and damage parameters were selected: The parameter PSWT; the parameter PJ, based on fracture mechanics of short cracks; the non‐linear‐continuous‐damage (NLCD) model, based on continuum damage mechanics and the energy‐based damage theory from Ellyin. Each method was illustrated and discussed also basing on the experimental results obtained with specimens of the steel HC340LA in as‐received state and with specimens of the same material after the process of linear flow splitting. The use of the parameter of Smith‐Watson Topper seemed to be the most suitable for the evaluation of fatigue life for HC340LA.

Collision energy dependence of elliptic flow splitting between particles and their antiparticles from an extended multiphase transport model

Based on an extended multiphase transport model, which includes mean-field potentials in both the partonic and hadronic phases, uses the mix-event coalescence, and respects charge conservation during the hadronic evolution, we have studied the collision energy dependence of the elliptic flow splitting between particles and their antiparticles. This extended transport model reproduces reasonably well the experimental data at lower collision energies but only describes qualitatively the elliptic flow splitting at higher beam energies. The present study thus indicates the existence of other mechanisms for the elliptic flow splitting besides the mean-field potentials and the need of further improvements of the multiphase transport model.

Benefits of stress superposition in combined bending-linear flow splitting process

Linear flow splitting is a multi-station sheet-bulk metal forming process which allows continuous production of bifurcated profiles without joining, lamination or external heating of sheet metal. This process induces high hydrostatic stresses in the forming zone which leads to an elevated formability of the workpiece material. The aim of this research is to bend linear flow split profiles in transverse direction in a continuous manner. This is achieved by combining the linear flow splitting process with a continuous bending process. An analytical and a numerical model are described in this paper which predict bending moments for different radii. Results from both models are validated with experimental results. It is found that combining the linear flow splitting with a bending process leads to a severe reduction in the bending moments due to superposition of stresses in the forming zone. The superposition maintains the cross sectional shape of the bent profiles.

Application of RAD Sequencing for Evaluating the Genetic Diversity of Domesticated Panax notoginseng (Araliaceae).

Panax notoginseng, a traditional Chinese medicinal plant, has been cultivated and domesticated for approximately 400 years, mainly in Yunnan and Guangxi, two provinces in southwest China. This species was named according to cultivated rather than wild individuals, and no wild populations had been found until now. The genetic resources available on farms are important for both breeding practices and resource conservation. In the present study, the recently developed technology RADseq, which is based on next-generation sequencing, was used to analyze the genetic variation and differentiation of P. notoginseng. The nucleotide diversity and heterozygosity results indicated that P. notoginseng had low genetic diversity at both the species and population levels. Almost no genetic differentiation has been detected, and all populations were genetically similar due to strong gene flow and insufficient splitting time. Although the genetic diversity of P. notoginseng was low at both species and population levels, several traditional plantations had relatively high genetic diversity, as revealed by the He and π values and by the private allele numbers. These valuable genetic resources should be protected as soon as possible to facilitate future breeding projects. The possible geographical origin of Sanqi domestication was discussed based on the results of the genetic diversity analysis.

A study on springback of bending linear flow split profiles

The bending of linear flow split profiles made up of high strength materials involves high bending loads leading to high springback and geometrical defects. In addition, the linear flow split profiles are made stronger due to the high plastic deformation applied by the process itself. The bending method proposed in this paper combines the linear flow splitting process with a movable bending tool. The aim of the research was to investigate the effect of superimposed stresses exerted by the linear flow splitting process on bending load and springback of the profile by using a finite element model. The latter was validated by means of experimental results. The results show that the bending loads and the springback were reduced by increasing the superposition of stress applied by the linear flow splitting process. The reduction in the bending loads leads to a reduction in the cross-sectional distortion. Furthermore, the springback was compensated by controlling the amount of superimposed stress.

Hybrid level set method based on image diffusion

In this paper, a new hybrid diffusion-based level set method is proposed to efficiently address the complex image segmentation problem. Different from the traditional methods, the proposed method is performed on image diffusion space rather than intensity space. Firstly, the nonlinear diffusion based on total variation flow and additive operator splitting scheme is performed on the original intensity image to obtain the diffused image. Then, the local diffusion energy term is constructed by performing homomorphic unsharp masking operation on diffused image so as to implement a local piecewise constant search. To avoid trapping into local minimum produced by local energy, the global diffusion energy term is formed by approximating diffused image in a global piecewise constant way. Besides, the regularization energy term is included to have penalization effect on evolving contour length and maintenance of level set function being signed distance function. By minimizing the overall energy functional which is a linear combination of local energy, global energy and regularization energy, the evolving contour can be driven to approach the object boundary. The experiments on different characteristics of complex images have shown that the proposed method can achieve satisfying segmentation performance accompanied with some good properties, i.e. the robustness to initial parameter and contour setting, noise insensitivity, quick and stable convergence.

Pressure-Minimization Method for Prediction of Two-Phase-Flow Splitting

Summary Looped gas/liquid multiphase-flow pipelines are used by the oil and gas industry to reduce pressure drop and increase flow capacity. They can be installed alone as a flow splitter or combined in series to form a manifold. Application of looped lines is not unique to the petroleum industry; they are also applied in other industries such as nuclear and chemical. However, there has not yet been a comprehensive fundamental investigation of the flow behavior or predictive methods available for such systems because of the complexity involved with respect to process variables such as flow patterns, fluid properties, phase velocities, and pipe geometry. Uneven splitting of the gas and liquid phases between the two looped lines can cause malfunction of the downstream processing equipment; therefore, a total of 65 experiments at different flow conditions in a looped-lines system using different-diameter looped-line configurations are conducted in this study to investigate the pressure drop during uneven flow splitting. Most of the experiments are carried out with slug flow at the system inlet, while flow patterns such as slug flow, dispersed flow, and stratified flow are observed in the looped pipes. A computational algorithm is developed for predicting gas/liquid two-phase-flow splitting in the looped lines on the basis of energy minimization. The algorithm predicts the uneven splitting of the two phases and the corresponding pressure drop across the loop. Additionally, the model shows that maximum pressure drop occurs when there is equal splitting in the looped lines. Good agreements have been achieved between the measured and predicted flow splitting and pressure drop across the looped lines.

Energy-aware traffic engineering in hybrid SDN/IP backbone networks

Software Defined Networking (SDN) can effectively improve the performance of traffic engineering and has promising application foreground in backbone networks. Therefore, new energy saving schemes must take SDN into account, which is extremely important considering the rapidly increasing energy consumption from Telecom and ISP networks. At the same time, the introduction of SDN in a current network must be incremental in most cases, for both technical and economic reasons. During this period, operators have to manage hybrid networks, where SDN and traditional protocols coexist. In this paper, we study the energy efficient traffic engineering problem in hybrid SDN/IP networks. We first formulate the mathematic optimization model considering SDN/IP hybrid routing mode. As the problem is NP-hard, we propose the fast heuristic algorithm named HEATE (Hybrid Energy-Aware Traffic Engineering). In our proposed HEATE algorithm, the IP routers perform the shortest path routing using the distribute OSPF link weight optimization. The SDNs perform the multi-path routing with traffic flow splitting by the global SDN controller. The HEATE algorithm finds the optimal setting of OSPF link weight and splitting ratio of SDNs. Thus traffic flow is aggregated onto partial links and the underutilized links can be turned off to save energy. By computer simulation results, we show that our algorithm has a significant improvement in energy efficiency in hybrid SDN/IP networks.

Climatology of Heavy Orographic Rainfall Induced by Tropical Cyclones over Madagascar: From Synoptic to Mesoscale Perspectives

Variability of and generation mechanisms for Madagascar rainfall are studied by conducting climatological, synoptic and mesoscale analyses. It is found the rainfall variability is highly sensitive to seasons with high variability in summer (Nov-Apr). The rainfall in summer is controlled by the Intertropical Convergence Zone (ITCZ) and orographic rainfall associated with tropical cyclones (TCs), while the rainfall in winter (May-Oct) is controlled by trade winds and local orographic rainfall along the eastern coast. Synoptic analysis reveals that major climate variations in summer are associated with ITCZ position, which is closely related to TC genesis locations and quasi-biennial oscillation (QBO). Linkages between El-Niño Southern Oscillation Index (ENSO) and Southern Oscillation Index (SOI) are identified as the cause of inconsistent dry or wet summers. Mesoscale analysis depicts the importance of the orographic effects on prevailing wind, which are controlled by the orography in both seasons. In winter, the prevailing trade winds over the Southwest Indian Ocean are from the east and are split to the north and south when it impinges on Malagasy Mountains. On the other hand, in summer the prevailing easterlies are weaker leading to the production of lee vortices, in addition to the flow splitting upstream of the mountain. Thus, the flow is classified into two regimes: (a) flow-over regime with no lee vortices under high Froude number (Fr=1.2-1.8) flow, and (b) flow-around regime with lee vortices under low Fr (=0.88-1.16) flow. A case study of TC Domoina (1984) indicates that the long-lasting heavy rainfall was induced by the strong orographic blocking of Madagascar. The shorter-term (e.g., 2 days) heavy orographic precipitation is characterized by large VH ∙Ñh which is composed by two common ingredients, namely a strong low-level wind normal to the mountain (VH) and a steep mountain slope (∇h).

Spin transport in intermediate-energy heavy-ion collisions as a probe of in-medium spin–orbit interactions

The spin up-down splitting of collective flows in intermediate-energy heavy-ion collisions as a result of the nuclear spin–orbit interaction is investigated within a spin- and isospin-dependent Boltzmann–Uehling–Uhlenbeck transport model SIBUU12. Using a Skyrme-type spin–orbit coupling quadratic in momentum, we found that the spin splittings of the directed flow and elliptic flow are largest in peripheral Au+Au collisions at beam energies of about 100–200 MeV/nucleon, and the effect is considerable even in smaller systems especially for nucleons with high transverse momenta. The collective flows of light clusters of different spin states are also investigated using an improved dynamical coalescence model with spin. Our study can be important in understanding the properties of in-medium nuclear spin–orbit interactions once the spin-dependent observables proposed in this work can be measured.

CFD for wastewater treatment: an overview

Computational fluid dynamics (CFD) is a rapidly emerging field in wastewater treatment (WWT), with application to almost all unit processes. This paper provides an overview of CFD applied to a wide range of unit processes in water and WWT from hydraulic elements like flow splitting to physical, chemical and biological processes like suspended growth nutrient removal and anaerobic digestion. The paper's focus is on articulating the state of practice and research and development needs. The level of CFD's capability varies between different process units, with a high frequency of application in the areas of final sedimentation, activated sludge basin modelling and disinfection, and greater needs in primary sedimentation and anaerobic digestion. While approaches are comprehensive, generally capable of incorporating non-Newtonian fluids, multiphase systems and biokinetics, they are not broad, and further work should be done to address the diversity of process designs. Many units have not been addressed to date. Further needs are identified throughout, but common requirements include improved particle aggregation and breakup (flocculation), and improved coupling of biology and hydraulics.

A highly localized high‐precipitation event over Corsica

In the framework of the Hydrological Cycle of the Mediterranean Experiment (HyMeX), the high precipitation event (HPE) of 23 October 2012 is investigated. In the morning, a highly localized convective system developed over the southeast of Corsica, close to Porto‐Vecchio. Its precipitation maximum is estimated at over 100 mm within 6 h. The Meso‐NH model is used with a horizontal grid spacing of 2.5 km to simulate the HPE. Different input datasets and starting times are used to assess the predictability of the event and the large spread of this initial condition ensemble indicates low predictability. Among the nine ensemble members only one captures the timing and location of the event.When the horizontal grid spacing is reduced to 500 m, precipitation is more widespread, maximum values are lower, and individual convective cells are smaller. Random perturbations to model physics are used to obtain a second ensemble, which shows less spread than the initial condition ensemble. The HPE over Porto‐Vecchio is present in all members of the physics ensemble with varying intensity while precipitation away from orography is more sensitive. Flattening the Corsican orography removes the HPE while blocking the cold northerly inflow into the Mediterranean basin increases its duration and intensity.From the analyses and simulations it is shown that the HPE of 23 October 2012 was located over a convergence line resulting from flow splitting and lee‐side convergence of the northerly boundary‐layer flow impinging the Corsican mountains. Moist air located east of the island was fed into this convergence line by northerly low‐level winds and southeasterly winds aloft advected the cells inland along the stationary convergence line, allowing large precipitation accumulations over a relatively small area.

A Novel Flow Regulation Protocol to Optimize the End-to-End Performance and Fairness Over LEO Satellite Network

The major challenge in the utilization of satellite network for the Internet access is its differing nature with wired network. To increase the performance of TCP-based applications over satellite network, performance enhancement proxies (PEP) had been incorporated. However, the existing PEP solutions have violated the end-to-end semantics of Internet applications. To solve this problem and to meet the future needs of the communication network, next-generation transport architecture (Iyengar and Ford in flow splitting with fate sharing in a next-generation transport services architecture, 2009; in A next-generation transport services architecture, 2009. http://tools.ietf.org/html/draft-iyengar-ford-tng-00) has been proposed. In this architecture, flow regulation functions (flow regulation layer) are factored out from end-to-end best delivery (endpoint layer). As a contribution to this research direction, we propose a novel flow regulation protocol to control the flows in terms of congestion, error and fairness over the Low Earth Orbit satellite environment. Simulation results reveal that the proposed protocol can provide optimized end-to-end performance (high throughput, high goodput and high information efficiency) without violating end-to-end semantics, and it also meets the network-level objective of fairness among the flows.

MARS: Multiple Access Radio Scheduling for a Multi-homed Mobile Device in Soft-RAN

In order to improve the Quality-of-Service (QoS) of latency sensitive applications in next-generation cellular networks, multi-path is adopted to transmit packet stream in real-time to achieve high-quality video transmission in heterogeneous wireless networks. However, multi-path also introduces two important challenges: out-of-order issue and reordering delay. In this paper, we propose a new architecture based on Software Defined Network (SDN) for flow aggregation and flow splitting, and then design a Multiple Access Radio Scheduling (MARS) scheme based on relative Round-Trip Time (RTT) measurement. The QoS metrics including end-to-end delay, throughput and the packet out-of-order problem at the receiver have been investigated using the extensive simulation experiments. The performance results show that this SDN architecture coupled with the proposed MARS scheme can reduce the end-to-end delay and the reordering delay time caused by packet out-of-order as well as achieve a better throughput than the existing SMOS and Round-Robin algorithms.

Analytical and Computational Analysis of Flow Splitting in Multiple, Parallel Channels Systems

Previous analytical results on flow splitting are generalized to consider multiple boiling channels systems. The analysis is consistent with the approximations usually adopted in the use of systems codes (like RELAP5 and TRACE5, among others) commonly applied to perform safety analyses of nuclear power plants. The problem is related to multiple, identical, parallel boiling channels, connected through common plena. A theoretical model limited in scope explains this flow splitting without reversal. The unified analysis performed and the confirmatory computational results found are summarized in this paper. New maps showing the zones where this behavior is predicted are also shown considering again twin pipes. Multiple pipe systems have been found not easily amenable for analytical analysis when dealing with more than four parallel pipes. However, the particular splitting found (flow along N pipes dividing in one standalone pipe flow plus N -1 identical pipe flows) has been verified up to fourteen pipes, involving calculations in systems with even and odd number of pipes using the RELAP5 systems thermal-hydraulics code.

Research on the influence of the band edge processing on the process of linear flow splitting

Sheet metal is available in a wide range of properties and material composition. There are standardized quality characteristics for mechanical and geometrical properties in the plane of the sheet. However, the band edges are influenced by the correspondent metal working process and the properties may vary or be unknown. The forming zone of the manufacturing process linear flow splitting is located at the band edge. Thus, the knowledge of probable influences of metal working induced band edge properties on the process of linear flow splitting is essential and this knowledge will be presented in the following article.

Chiral vortical wave and induced flavor charge transport in a rotating quark-gluon plasma

We show the existence of a new gapless collective excitation in a rotating fluid system with chiral fermions, named as the Chiral Vortical Wave (CVW). The CVW has its microscopic origin at the quantum anomaly and macroscopically arises from interplay between vector and axial charge fluctuations induced by vortical effects. The wave equation is obtained both from hydrodynamic current equations and from chiral kinetic theory and its solutions show nontrivial CVW-induced charge transport from different initial conditions. Using the rotating quark-gluon plasma in heavy ion collisions as a concrete example, we show the formation of induced flavor quadrupole in QGP and estimate the elliptic flow splitting effect for Lambda baryons that may be experimentally measured.