Sample records for centrifugal force

  1. [Galileo and centrifugal force]. (United States)

    Vilain, Christiane

    This work intends to focus on Galileo's study of what is now called "centrifugal force," within the framework of the Second Day of his Dialogo written in 1632, rather than on the previously published commentaries on the topic. Galileo proposes three geometrical demonstrations in order to prove that gravity will always overcome centrifugalforce, and that the potential rotation of the Earth, whatever its speed, cannot in any case project objects beyond it. Each of these demonstrations must consequently contain an error and it has seemed to us that the first one had not been understood up until now. Our analysis offers an opportunity to return to Galileo's geometrical representation of dynamical questions; actually, we get an insight into the sophistication of Galileo's practices more than into his mistakes. Our second point, concerning the historiography of the problem, shows an evolution from anachronic critics to more contextual considerations, in the course of the second half of the twentieth century.

  2. Confusion around the tidal force and the centrifugal force

    CERN Document Server

    Matsuda, Takuya; Boffin, Henri M J


    We discuss the tidal force, whose notion is sometimes misunderstood in the public domain literature. We discuss the tidal force exerted by a secondary point mass on an extended primary body such as the Earth. The tidal force arises because the gravitational force exerted on the extended body by the secondary mass is not uniform across the primary. In the derivation of the tidal force, the non-uniformity of the gravity is essential, and inertial forces such as the centrifugal force are not needed. Nevertheless, it is often asserted that the tidal force can be explained by the centrifugal force. If we literally take into account the centrifugal force, it would mislead us. We therefore also discuss the proper treatment of the centrifugal force.

  3. Modeling of Centrifugal Force Field and the Effect on Filling and Solidification in Centrifugal Casting (United States)

    Sheng, Wenbin; Ma, Chunxue; Gu, Wanli


    Based on the steady flow in a tube, a mathematical model has been established for the consideration of centrifuging force field by combining the equations of continuity, conservation of momentum and general energy. Effects of centrifugal field on the filling and solidification are modeled by two accessional terms: centrifugal force and Chorios force. In addition, the transfer of heat by convection is considered to achieve a coupling calculation of velocity field and temperature field. The solution of pressure item is avoided by introducing the stream function ψ(x,y) and the eddy function ξ(x,y). Corresponding difference formats for the simultaneous equations of centrifugal filling, the accessional terms and the solidifying latent heat have been established by the finite difference technique. Furthermore, the centrifugal filling and solidification processes in a horizontal tube are summarized to interpret the mechanism by which internal defects are formed in centrifugal castings.

  4. Centripetal Acceleration and Centrifugal Force in General Relativity (United States)

    Bini, D.; de Felice, F.; Jantzen, R. T.


    In nonrelativistic mechanics noninertial observers studying accelerated test particle motion experience a centripetal acceleration which, once interpreted as a centrifugal force acting on the particle, allows writing the particle's equation of motion in a Newtonian form, simply by adding the inertial force contribution to that of the external forces in the acceleration-equals-force equation. In general relativity centripetal and centrifugal acceleration generalizing the classical concepts must be properly (geometrically) defined. This requires a relative Frenet-Serret frame approach based on a family of test observers.

  5. Massively parallel single-molecule manipulation using centrifugal force

    CERN Document Server

    Halvorsen, Ken


    Precise manipulation of single molecules has already led to remarkable insights in physics, chemistry, biology and medicine. However, widespread adoption of single-molecule techniques has been impeded by equipment cost and the laborious nature of making measurements one molecule at a time. We have solved these issues with a new approach: massively parallel single-molecule force measurements using centrifugal force. This approach is realized in a novel instrument that we call the Centrifuge Force Microscope (CFM), in which objects in an orbiting sample are subjected to a calibration-free, macroscopically uniform force-field while their micro-to-nanoscopic motions are observed. We demonstrate high-throughput single-molecule force spectroscopy with this technique by performing thousands of rupture experiments in parallel, characterizing force-dependent unbinding kinetics of an antibody-antigen pair in minutes rather than days. Additionally, we verify the force accuracy of the instrument by measuring the well-est...

  6. Effect of centrifugal forces on dimensional error of bored shapes (United States)

    Arsuaga, M.; de Lacalle, L. N. López; Lobato, R.; Urbikain, G.; Campa, F.


    Boring operations of deep holes with a slender boring bar are often hindered by the precision because of their low static stiffness and high deformations. Because of that, it is not possible to remove much larger depths of cuts than the nose radius of the tool, unlike the case of turning and face milling operations, and consequently, the relationship between the cutting force distribution, tool geometry, feed rate and depth of cut becomes non-linear and complex. This problem gets worse when working with a rotating boring head where apart from the cutting forces and the variation of the inclination angle because of shape boring, the bar and head are affected by de centrifugal forces. The centrifugal forces, and therefore the centrifugal deflection, will vary as a function of the rotating speed, boring bar mass distribution and variable radial position of the bar in shape boring. Taking in to account all this effects, a load and deformation model was created. This model has been experimentally validated to use as a corrector factor of the radial position of the U axis in the boring head.

  7. Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces. (United States)

    Eral, Huseyin Burak; Safai, Eric R; Keshavarz, Bavand; Kim, Jae Jung; Lee, Jisoek; Doyle, P S


    A controlled synthesis of polymeric particles is becoming increasingly important because of emerging applications ranging from medical diagnostics to self-assembly. Centrifugal synthesis of hydrogel microparticles is a promising method, combining rapid particle synthesis and the ease of manufacturing with readily available laboratory equipment. This method utilizes centrifugal forces to extrude an aqueous polymer solution, sodium alginate (NaALG) through a nozzle. The extruded solution forms droplets that quickly cross-link upon contact with aqueous calcium chloride (CaCl2) solution to form hydrogel particles. The size distribution of hydrogel particles is dictated by the pinch-off behavior of the extruded solution through a balance of inertial, viscous, and surface tension stresses. We identify the parameters dictating the particle size and provide a numerical correlation predicting the average particle size. Furthermore, we create a phase map identifying different pinch-off regimes (dripping without satellites, dripping with satellites, and jetting), explaining the corresponding particle size distributions, and present scaling arguments predicting the transition between regimes. By shedding light on the underlying physics, this study enables the rational design and operation of particle synthesis by centrifugal forces.

  8. Stopping intense beams of internally cold molecules via centrifugal forces (United States)

    Wu, Xing; Gantner, Thomas; Zeppenfeld, Martin; Chervenkov, Sotir; Rempe, Gerhard


    Cryogenic buffer-gas cooling produces intense beams of internally cold molecules. It offers a versatile source for studying collision dynamics and reaction pathways in the cold regime, and could open new avenues for controlled chemistry, precision spectroscopy, and exploration of fundamental physics. However, an efficient deceleration of these beams still presents a challenge. Here, we demonstrate that intense and continuous beams of electrically guided molecules produced by a cryogenic buffer-gas cell can be brought to a halt by the centrifugal force in a rotating frame. Various molecules (e.g. CH3F and CF3CCH) are decelerated to below 20m /s at a corresponding output intensity of ~ 6 ×109mm-2 .s-1 . In addition, our RF-resonant depletion detection shows that up to 90 % rotational-state purity can be achieved in the so-produced slow molecular beams.


    Directory of Open Access Journals (Sweden)

    V. V. Hubovich


    Full Text Available The influence of centrifugal force on dynamics of the burning wave spread and the carbide particles distribution in metallic alloy in the process of SVS-casting is considered. It was concluded that centrifugal force can be used for production of materials with gradient of the hardening particles concentration.

  10. Centrifugal force induces human ligamentum flavum fibroblasts inflammation through activation of JNK and p38 pathways. (United States)

    Chao, Yuan-Hung; Tsuang, Yang-Hwei; Sun, Jui-Sheng; Sun, Man-Ger; Chen, Ming-Hong


    Inflammation has been proposed to be an important causative factor in ligamentum flavum hypertrophy. However, the mechanisms of mechanical load on inflammation of ligamentum flavum remain unclear. In this study, we used an in vitro model of human ligamentum flavum fibroblasts subjected to centrifugal force to elucidate the effects of mechanical load on cultured human ligamentum flavum fibroblasts; we further studied its molecular and biochemical mechanisms. Human ligamentum flavum fibroblasts were obtained from six patients undergoing lumbar spine surgery. Monolayer cultures of human ligamentum flavum fibroblasts were subjected to different magnitudes of centrifugal forces. Cell viability, cell death, biochemical response, and molecular response to centrifugal forces were analyzed. It was found that centrifugal stress significantly suppressed cell viability without inducing cell death. Centrifugal force at 67.1 g/cm(2) for 60 min significantly increases the production of prostaglandin E2 and nitric oxide as well as gene expression of proinflammatory cytokines, including interleukin (IL)-1α, IL-1β and IL-6, showed that centrifugal force-dependent induction of cyclooxygense-2 and inducible NO synthase required JNK and p38 mitogen-activated protein kinase, but not ERK 1/2 activities. This study suggested that centrifugal force does induce inflammatory responses in human ligamentum flavum fibroblasts. The activation of both JNK and p38 mitogen-activated protein kinase mechanotransduction cascades is a crucial intracellular mechanism that mediates cyclooxygense-2/prostaglandin E2 and inducible NO synthase/nitric oxide production.

  11. Flow Field of Metallic Fluid Acted by Electromagnetic and Centrifugal Force

    Institute of Scientific and Technical Information of China (English)

    QIU Yi-qing; LUO Zong-an; JIA Guang-lin; LIU Xiang-hua; WANG Guo-dong


    According to the principle of electromagnetism and hydrodynamics, a mathematical model of flow field for metallic fluid acted by electromagnetic and centrifugal forces was established. The calculation results showed that the relative velocity between metallic fluid layers rises and the absolute rotational velocity of metallic fluid falls with the increase of magnetic induction intensity. The increase of centrifugal revolution hardly affects the relative velocity between metallic fluid layers, but can enhance the absolute rotational velocity of metallic fluid.

  12. Huygens' principle, the free Schrodinger particle and the quantum anti-centrifugal force

    DEFF Research Database (Denmark)

    Cirone, M.A.; Dahl, Jens Peder; Fedorov, M.


    Huygens' principle following from the d'Alembert wave equation is not valid in two-dimensional space. A Schrodinger particle of vanishing angular momentum moving freely in two dimensions experiences an attractive force-the quantum anti-centrifugal force-towards its centre. We connect these two...

  13. Expression of myosin heavy-chain mRNA in cultured myoblasts induced by centrifugal force. (United States)

    Kurokawa, Katsuhide; Sakiyama, Koji; Abe, Shinichi; Hiroki, Emi; Naito, Kaoru; Nakajima, Kazunori; Takeda, Tomotaka; Inoue, Takashi; Ide, Yoshinobu; Ishigami, Keiichi


    Ballistic muscle training leads to hypertrophy of fast type fibers and training for endurance induces that of slow type fibers. Numerous studies have been conducted on electrical, extending and magnetic stimulation of cells, but the effect of centrifugal force on cells remains to be investigated. In this study, we investigated the effect of stimulating cultured myoblasts with centrifugal force at different speeds on cell proliferation and myosin heavy-chain (MyHC) mRNA expression in muscle fiber. Stimulation of myoblasts was carried out at 2 different speeds for 20 min using the Himac CT6D, a desk centrifuge, and cells were observed at 1, 3 and 5 days later. Number of cells 1 and 5 days after centrifugal stimulation was significantly larger in the 62.5 x g and 4,170 x g stimulation groups than in the control group. Expression of MyHC-2b mRNA 1 day after centrifugal stimulation was significantly higher in the 2 stimulation groups than in the control group. Almost no expression of MyHC-2a was observed in any group at 1 and 3 days after centrifugal stimulation. However, 5 days after stimulation, MyHC-2a was strongly expressed in the 2 stimulation groups in comparison to the control group. Three days after centrifugal stimulation, expression of MyHC-1 was significantly higher in the 2 stimulation groups than in the control group. The results of this study clarified the effect of different centrifugal stimulation speeds on muscle fiber characteristics, and suggest that centrifugal stimulation of myoblasts enhances cell proliferation.

  14. Radial forces in a centrifugal compressor; Experimental investigation by using magnetic bearings and static pressure distribution (United States)

    Reunanen, Arttu; Larjola, Jaakko


    The volute of a centrifugal compressor causes a non-uniform pressure distribution which leads to a radial force on the impeller. This force was measured using magnetic bearings. In addition, the radial force was estimated using the static pressure distribution measured at the impeller outlet. The impeller force was found to be the highest at choke, the lowest at the design flow and moderate at stall. The radial force determined from the pressure measurements was only slightly different from the force obtained from the bearing measurements. The rotational speed was seen to affect the force to some extent.

  15. Radial Forces in a Centrifugal Compressor; Experimental Investigation by Using Magnetic Bearings and Static Pressure Distribution

    Institute of Scientific and Technical Information of China (English)

    Arttu REUNANEN; Jaakko LARJOLA


    The volute of a centrifugal compressor causes a non-uniform pressure distribution which leads to a radial force on the impeller. This force was measured using magnetic bearings. In addition, the radial force was estimated using the static pressure distribution measured at the impeller outlet. The impeller force was found to be the highest at choke, the lowest at the design flow and moderate at stall. The radial force determined from the pressure measurements was only slightly different from the force obtained from the bearing measurements. The rotational speed was seen to affect the force to some extent.

  16. Rotordynamic forces generated by discharge-to-suction leakage flows in centrifugal pumps

    Institute of Scientific and Technical Information of China (English)

    LIU Quan-zhong; WANG Hong-jie; LIU Zhan-sheng


    In order to investigate the flow-induced vibration in the shroud passage of centrifugal pump and pre-dict rotordynamic forces of centrifugal pump rotor system,an analysis of rotordynamic forces arising from shrou-ded centnlugal pump is presented.CFD techniques were utilized to analyze the full three-dimensional viscous,primary/secondary flow field in a centrifugal pump impeller to determine rotordynamic forces. Multiple quasi-steady solutions of an eccentric three-dimensional model at different whirl frequency ratios yielded the rotordy-namic forces. The skew-symmetric stiffness,damping,and mass matrices were obtained by second-order least-squares analysis.Simulation of the coupled primary/secondary flow field was conducted,and the complex flow the flow field of a shroud passage were achieved including the mean velocity and pressure,as well as the eddy in a large scale of flow field due to viscosity.The rotordynamic force coefficients were calculat-ed,and the results were in good agreement with those of experiment except for the direct inertial coefficient without the consideration of whirling forces from the impeller primary flow passage.

  17. Comparison of rotordynamic fluid forces in axial inducers and centrifugal turbopump impellers (United States)

    d'Agostino, Luca


    The paper illustrates and compares the results of the experimental campaigns carried out in the Cavitating Pump Rotordynamic Test Facility (CPRTF) at Alta, Italy, under ESA funding for the characterization of the lateral rotordynamic fluid forces acting on high-head axial inducers and centrifugal turbopump impellers for space propulsion applications. The configurations presented here refer to a three-bladed tapered-hub, variable-pitch, inducer (DAPROT3) and a single-stage centrifugal pump (VAMPIRE) with vaneless diffuser and single spiral volute. Both the centrifugal pump and the inducer have been designed by means of reduced order models specifically developed by the author and his collaborators for the geometric definition and performance prediction of this kind of hydraulic turbomachinery. Continuous spectra of the rotordynamic forces acting on the impellers as functions of the whirl frequency have been obtained by means of the novel technique recently developed and demonstrated at Alta. The influence of the rotor whirl motion, flow rate, cavitating conditions, and liquid temperature (thermal cavitation effects) on the rotordynamic fluid forces is illustrated and the observed differences in their behavior in axial inducers and centrifugal turbpumps are discussed and interpreted in the light of the outcome of recent cavitation visualization experiments carried out by the Chemical Propulsion Team at Alta.

  18. Solidification and remelting of Al through Al2O3 fibrous preform under centrifugal force

    Institute of Scientific and Technical Information of China (English)

    HU Guo-xin; LIU Jian-ju; ZHANG Li-xiang; TIAN Qin-wei


    The solidification and remelting of molten aluminum through a porous preform under centrifugal force field were modeled numerically. The results show that the transient solidification and remelting phenomena appear on the infiltration front and can be divided into two distinct regions: the remelting region and solid-liquid congruent melting region. The decrease of porosity always results in the increase of moving velocity difference between the infiltration front and the remelting front, which leads to the increase of the solid-liquid congruent region extent. But for the decrease of the rotational frequency, the difference of moving velocity between infiltration front and remelting front decreases, which leads to the decrease of regional extent. The infiltration front moving velocity is mainly influenced by the centrifugal infiltration pressure, whereas the remelting front moving velocity is mainly influenced by the material thermodynamics. The transient solidification and remelting phenomena are the intercoupling results between the centrifugal infiltration dynamics and the material thermodynamics.

  19. Hydraulic forces caused by annular pressure seals in centrifugal pumps (United States)

    Iino, T.; Kaneko, H.


    The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity.

  20. Reconstitution of Human Ion Channels into Solvent-free Lipid Bilayers Enhanced by Centrifugal Forces. (United States)

    Hirano-Iwata, Ayumi; Ishinari, Yutaka; Yoshida, Miyu; Araki, Shun; Tadaki, Daisuke; Miyata, Ryusuke; Ishibashi, Kenichi; Yamamoto, Hideaki; Kimura, Yasuo; Niwano, Michio


    Artificially formed bilayer lipid membranes (BLMs) provide well-defined systems for functional analyses of various membrane proteins, including ion channels. However, difficulties associated with the integration of membrane proteins into BLMs limit the experimental efficiency and usefulness of such BLM reconstitution systems. Here, we report on the use of centrifugation to more efficiently reconstitute human ion channels in solvent-free BLMs. The method improves the probability of membrane fusion. Membrane vesicles containing the human ether-a-go-go-related gene (hERG) channel, the human cardiac sodium channel (Nav1.5), and the human GABAA receptor (GABAAR) channel were formed, and the functional reconstitution of the channels into BLMs via vesicle fusion was investigated. Ion channel currents were recorded in 67% of the BLMs that were centrifuged with membrane vesicles under appropriate centrifugal conditions (14-55 × g). The characteristic channel properties were retained for hERG, Nav1.5, and GABAAR channels after centrifugal incorporation into the BLMs. A comparison of the centrifugal force with reported values for the fusion force revealed that a centrifugal enhancement in vesicle fusion was attained, not by accelerating the fusion process but by accelerating the delivery of membrane vesicles to the surface of the BLMs, which led to an increase in the number of membrane vesicles that were available for fusion. Our method for enhancing the probability of vesicle fusion promises to dramatically increase the experimental efficiency of BLM reconstitution systems, leading to the realization of a BLM-based, high-throughput platform for functional assays of various membrane proteins.

  1. Experimental and Numerical Investigation of Radial Forces Acting on Centrifugal Pump Impeller

    Directory of Open Access Journals (Sweden)

    Karaskiewicz Krzysztof


    Full Text Available The paper presents the results of measurements and predictions of radial thrust in centrifugal pump with specific speed ns = 26. In the pump tested, a volute with rectangular cross-section was used. The tests were carried out for several rotational speeds, including speeds above and below the nominal one. Commercial code ANSYS Fluent was used for the calculations. Apart from the predictions of the radial force, the calculations of axial thrust were also conducted, and correlation between thrust and the radial force was found. In the range of the measured rotational speeds, similarity of radial forces was checked.


    Directory of Open Access Journals (Sweden)

    Athina Lampridi-Kemou


    Full Text Available Before the third Egyptian revolution in early 2011, the Muslim Brotherhood was considered the only real opposition capable of challenging the hegemonic government of the Egyptian regime, owing to the popular support the organisation enjoyed; much greater than that of the opposition parties. However, change has not come through the Brotherhood, but through the Egyptian people themselves. In all these years that the Brotherhood has existed on the Egyptian political stage, neither its significant logistic and economic resources nor its dominant role in opposition politics have contributed to any change in the country’s power structure. The aim of this article is to show that the policies adopted by the Muslim Brotherhood in their interaction with the Hosni Mubarak government – both when they were in confrontation and in phases of accommodation – have only helped to maintain the status quo, and that they have, therefore, constituted a centripetal force with respect to the regime. This analysis may also offer a few clues as to the organisation’s future behaviour.


    Institute of Scientific and Technical Information of China (English)

    Molchanov Ⅴ. Ⅰ.; Paraev Ⅴ. Ⅴ.


    We describe the earlier unknown, when applied to global tectonics, centrifugal inertial mechanism of lithosphere plate moving under the effect of forces appearing as a result of Earth's planetary rotation. The mechanism stated gives an insight into global tectonics of plates with the indirect participation of emanation streams which, in their turn, are the derivatives of centrifugal and inertial forces of planetary motion. The application of this mechanism provides a logical explanation for the regularities of global tectogenesis including the formation of mountain ridges mainly of submeridional and sublatitudinal strike,and also the drift of continental plates from the east to the west and from the south to the north. The mechanism clarifies the significance of the Arctic and the Antarctic Circles as geodynamic barriers.

  4. Theoretical and numerical analysis of coal dust separated by centrifugal force for working and heading faces

    Institute of Scientific and Technical Information of China (English)

    Shiqiang Chen; Haiqiao Wang; Yiqun Li; Haijiao Cui; Jie Zhao; Xiaowei Zhang


    In order to meet engineering needs of Chinese underground coal mines, a new dust-collecting fan, a device of dust separated by centrifugal force in driven cyclone passageway (DCCP) was designed. In centrifugal dust removal section (CDRS) of DCCP, a general equation is derived from the principle of force equilibrium. According to CDRS structure parameters and fan running parameters, the general equation is simplified, and the simplest equation is calculated numerically by MATLAB. The calculation results illustrate that increasing quantity of air current is against dust removal, but it is beneficial to dust removal by increasing the radius of driven spiral blade and increasing the particle diameter of coal dust. The conclusions show that the dust-collecting structure parameters coupled with the fan running parameters is a novel optimization approach to dust-collection fan for working and heading faces, which is especially suitable for Chinese underground mines.

  5. Spreading of thin rotating films: Competition of thermal Marangoni, centrifugal, and gravitational forcing (United States)

    Dijksman, Joshua; Mukhopadhyay, Shomeek; Behringer, Robert


    We experimentally probe the quasi static spreading of a sessile drop on a substrate under the influence of competing gravitational, thermo capillary (Marangoni) and centrifugal forcing. We use silicone oil on a prewetted silicon wafer, and we employ an interferometric technique to study the evolution of the film height profile. We discuss our results in the context of recent theory developed by Bostwick et al.

  6. A Novel Fabrication Method for Functionally Graded Materials under Centrifugal Force: The Centrifugal Mixed-Powder Method

    Directory of Open Access Journals (Sweden)

    Eri Miura-Fujiwara


    Full Text Available One of the fabrication methods for functionally graded materials (FGMs is a centrifugal solid-particle method, which is an application of the centrifugal casting technique. However, it is the difficult to fabricate FGMs containing nano-particles by the centrifugal solid-particle method. Recently, we proposed a novel fabrication method, which we have named the centrifugal mixed-powder method, by which we can obtain FGMs containing nano-particles. Using this processing method, Cu-based FGMs containing SiC particles and Al-based FGMs containing TiO2 nano-particles on their surfaces have been fabricated. In this article, the microstructure and mechanical property of Cu/SiC and Al/TiO2 FGMs, fabricated by the centrifugal mixed-powder method are reviewed.

  7. Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump. (United States)

    Pai, C N; Shinshi, T; Shimokohbe, A


    Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

  8. Mold Filling Behavior of Melts with Different Viscosity under Centrifugal Force Field

    Institute of Scientific and Technical Information of China (English)


    Recently proposed mathematical model for mold filling processes under centrifugal force field conditions and the computer codes were first tested through the sample simulation of gravity mold filling process for a benchmark plate-casting, which were compared with quoted experimental observations. The model and the developed computer program were then applied to the numerical simulation of centrifugal field mold filling processes for a thin-section casting with a titanium alloy melt of assumed viscosity of 1.2 and 12.0 mm2/s, respectively. The computation result comparison shows that the flow behaviors of the filling melts are basically similar to each other although the less viscous melt tends to fill into the thin section casting cavity faster.

  9. Effect of Perturbations in the Coriolis and Centrifugal Forces on the Stability of 4 in the Relativistic R3BP

    Indian Academy of Sciences (India)

    Jagadish Singh; Nakone Bello


    The centrifugal and Coriolis forces do not appear as a result of physically imposed forces, but are due to a special property of a rotation. Thus, these forces are called pseudo-forces or `fictitious forces’. They are merely an artifact of the rotation of the reference frame adopted. This paper studies the motion of a test particle in the neighbourhood of the triangular point 4 in the framework of the perturbed relativistic restricted three-body problem (R3BP) when small perturbations are conferred to the centrifugal and Coriolis forces. It is found that the position and stability of the triangular point are affected by both the relativistic factor and small perturbations in the Coriolis and centrifugal forces. As an application, the Sun–Earth system is considered.

  10. Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    CAO Wei-dong; DAI Xun; HU Qi-xiang


    The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h,H=60 m,n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head (NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model (κ-ε). It is found that axial force of pump with radical reflux balance holes of 5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

  11. Social network influences on smoking, drinking and drug use in secondary school: centrifugal and centripetal forces. (United States)

    Fletcher, Adam; Bonell, Chris


    We explore how school experiences and social networks structure young people's substance use in different institutional contexts. The concepts of 'selection' and 'influence' are situated within the context of bounded agency, counter-school cultures and Bourdieusian notions of capital. We employed individual and group interviews, network-mapping, and observations at two contrasting English secondary schools. Both schools were characterised by extended social network structures that appeared to influence patterns of substance use, although the mechanisms via which this occurred varied according to school context. At Grange House school (suburban context) a minority of students from disadvantaged families were alienated by the attainment-focused regime, marginalised by a strong peer-led centrifugal force pushing them outwards, and substance use was an alternative source of bonding and identity for these students. In contrast, at North Street a centripetal force operated whereby the majority of students were pulled towards highly-visible, normative markers of 'safe', 'road culture', such as cannabis use and gang-involvement, as they attempted to fit in and survive in an inner-city school environment. We conclude that health inequalities may be reproduced through these distinctive centrifugal and centripetal forces in different institutional contexts, and this should be the focus of quantitative examination in the UK and elsewhere.

  12. Effects of centrifugal and Coriolis forces on the mold-filling behavior of titanium melts in vertically rotating molds

    Institute of Scientific and Technical Information of China (English)

    Xu Daming; Jia Limin; Fu Hengzhi


    The vertical centrifugal-casting technique is widely used in the manufacture of various irregularly-shaped castings of advanced structural alloys with thin walls, complex shapes and/or large sizes. These castings are used in the increasing applications in aero-space/aviation industries, human teeth/bone repairs with near-net shaped components, etc. In a vertically rotating casting system, the mold-filling processes of alloy melts, coupled with solidification-heat transfer, may be much more complicated, because they are driven simultaneously by gravity, centrifugal and Codolis forces. In the present work, an N-S/VOF-equations-based model, solved using a SOLA-VOF algorithm, under a rotating coordinate system was applied to numerically investigate the impacts of centrifugal and Coriolis forces on metallic melt mold-filling processes in different vertical centrifugal-casting configurations with different mold-rotation rates using an authors' computer-codes system. The computational results show that the Coriolis force may cause remarkable variations in the flow patterns in the casting-part-cavities of a large horizontal-section area and directly connected to the sprue via a short ingate in a vertical centrifugal-casting process. A "turn-back" mold-filling technique, which only takes advantage of the centrifugal force in a transient rotating melt system, has been confirmed to be a rational centrifugal-casting process in order to achieve smooth and layer-by-layer casting-cavities-filling control. The simulated mold-filling processes of Ti-6Al-4V alloy melt, in a vertical centrifugal-casting system with horizontally-connected plate-casting cavities, show reasonable agreement with experimental results from the literature.

  13. Centrifugal instability of Stokes layers in crossflow: the case of a forced cylinder wake

    CERN Document Server

    D'Adamo, Juan; Wesfreid, José Eduardo


    The wake flow around a circular cylinder at $Re\\approx100$ performing rotatory oscillations has been thoroughly discussed in the literature, mostly focusing on the modifications to the natural B\\'enard-von K\\'arm\\'an vortex street that result from the forced shedding modes locked to the rotatory oscillation frequency. The usual experimental and theoretical frameworks at these Reynolds numbers are quasi-two-dimensional, since the secondary instabilities bringing a three-dimensional structure to the cylinder wake flow occur only at higher Reynolds numbers. In the present paper we show that a three-dimensional structure can appear below the usual three-dimensionalization threshold, when forcing with frequencies lower than the natural vortex shedding frequency, at high amplitudes, as a result of a previously unreported mechanism: a pulsed centrifugal instability of the oscillating Stokes layer at the wall of the cylinder. The present numerical investigation lets us in this way propose a physical explanation for t...

  14. Analysis of Forced Spatial Vibrations of a Centrifugal Pump Impeller with Axial Forces Balancing Device (United States)

    Zhulyov, A.; Martsinkovsky, V.; Kundera, C.


    In this paper, a model of a pump impeller with annular seals and a balancing device, used as a combined support-seal assembly, is considered. The forced coupled radial, angular and axial vibrations of the rotor are determined with consideration of linearized inertial, damping, gyroscopic, positional and circulating forces and moments acting on the impeller from the side of the fluid flow in annular seals. The theoretical analysis is supplemented with a numerical example, the amplitude frequency characteristics are shown.

  15. Evaluation of hydraulic radial forces on the impeller by the volute in a centrifugal rotary blood pump. (United States)

    Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich


    In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study.

  16. Fabrication of Al-Al3Ti/Ti3Al Functionally Graded Materials under a Centrifugal Force

    Directory of Open Access Journals (Sweden)

    Yoshimi Watanabe


    Full Text Available Fabrication of Al-Al3Ti functionally graded materials (FGMs under the centrifugal force has recently attracted some attention. The controlled compositional gradient of the fabricated FGMs, the low cost of the process, and the good mold filling, are the main advantages of the centrifugal method (CM. Using the conventional CM techniques such as the centrifugal solid-particle method and centrifugal in-situ method, FGMs rings with gradually distributed properties could be achieved. As a more practical choice, the centrifugal mixed-powder method (CMPM was recently proposed to obtain FGMs containing nano-particles selectively dispersed in the outer surface of the fabricated parts. However, if a control of the particles morphology, compound formulas or sizes, is desired, another CM technique is favored. As a development of CMPM, our novel reaction centrifugal mixed-powder method (RCMPM has been presented. Using RCMPM, Al‑Al3Ti/Ti3Al FGMs with good surface properties and temperature controlled compositional gradient could be achieved. In this short review, this novel method will be discussed in detail and the effect of RCMPM processing temperature on the reinforcement particles morphology, size and distribution through the fabricated samples, will be reviewed.

  17. Effect of Coriolis force on counter-current chromatographic separation by centrifugal partition chromatography. (United States)

    Ikehata, Jun-Ichi; Shinomiya, Kazufusa; Kobayashi, Koji; Ohshima, Hisashi; Kitanaka, Susumu; Ito, Yoichiro


    The effect of Coriolis force on the counter-current chromatographic separation was studied using centrifugal partition chromatography (CPC) with four different two-phase solvent systems including n-hexane-acetonitrile (ACN); tert-butyl methyl ether (MtBE)-aqueous 0.1% trifluoroacetic acid (TFA) (1:1); MtBE-ACN-aqueous 0.1% TFA (2:2:3); and 12.5% (w/w) polyethylene glycol (PEG) 1000-12.5% (w/w) dibasic potassium phosphate. Each separation was performed by eluting either the upper phase in the ascending mode or the lower phase in the descending mode, each in clockwise (CW) and counterclockwise column rotation. Better partition efficiencies were attained by the CW rotation in both mobile phases in all the two-phase solvent systems examined. The mathematical analysis also revealed the Coriolis force works favorably under the CW column rotation for both mobile phases. The overall results demonstrated that the Coriolis force produces substantial effects on CPC separation in both organic-aqueous and aqueous-aqueous two-phase systems.

  18. An intuitive approach to inertial forces and the centrifugal force paradox in general relativity

    CERN Document Server

    Jonsson, Rickard


    As the velocity of a rocket in a circular orbit near a black hole increases, the outwardly directed rocket thrust must increase to keep the rocket in its orbit. This feature might appear paradoxical from a Newtonian viewpoint, but we show that it follows naturally from the equivalence principle together with special relativity and a few general features of black holes. We also derive a general relativistic formalism of inertial forces for reference frames with acceleration and rotation. The resulting equation relates the real experienced forces to the time derivative of the speed and the spatial curvature of the particle trajectory relative to the reference frame. We show that an observer who follows the path taken by a free (geodesic) photon will experience a force perpendicular to the direction of motion that is independent of the observers velocity. We apply our approach to resolve the submarine paradox, which regards whether a submerged submarine in a balanced state of rest will sink or float when given a...

  19. Three-dimensional unsteady flow and forces in centrifugal impellers with circumferential distortion of the outlet static pressure

    Energy Technology Data Exchange (ETDEWEB)

    Fatsis, A.; Pierret, S.; Braembussche, R. van den [von Karman Inst. for Fluid Dynamics, Rhode-St.-Genese (Belgium). Turbomachinery Dept.


    This paper describes the numerical investigation of the centrifugal impeller response to downstream static pressure distortions imposed by volutes at off-design operations. An unsteady three-dimensional Euler solver with nonreflecting upstream and downstream boundary conditions and phase-lagged periodicity conditions is used for this purpose. The mechanisms governing the unsteady flow field are analyzed. A parametric study shows the influence of the acoustic Strouhal number on the amplitude of the flow perturbations. Radial forces calculated on backward leaned and radial ending centrifugal impellers show nonnegligible influence of the impeller geometry.

  20. Visual feedback of the moving arm allows complete adaptation of pointing movements to centrifugal and Coriolis forces in human subjects. (United States)

    Bourdin, C; Gauthier, G; Blouin, J; Vercher, J L


    A classical visuo-manual adaptation protocol carried out on a rotating platform was used to test the ability of subjects to adapt to centrifugal and Coriolis forces when visual feedback of the arm is manipulated. Three main results emerge: (a) an early modification of the initial trajectory of the movements takes place even without visual feedback of the arm; (b) despite the change in the initial trajectory, the new external force decreases the accuracy of the pointing movements when vision is precluded; (c) a visual adaptive phase allows complete adaptation of the pointing movements performed in a modified gravitoinertial field. Therefore vision would be essential for subjects to completely adapt to centrifugal and Coriolis forces. However, other sensory signals (i.e. vestibular and proprioceptive) may constitute the basis for early but partial correction of the pointing movements.

  1. Centrifugal forces within usually-used magnitude elicited a transitory and reversible change in proliferation and gene expression of osteoblastic cells UMR-106. (United States)

    Li, Juan; Jiang, Lingyong; Liao, Ga; Chen, Guoping; Liu, Ying; Wang, Jun; Zheng, Yi; Luo, Songjiao; Zhao, Zhihe


    Centrifugation is an important step in biochemical and molecular biological researches. But the effects of centrifugal stress on cells are still unclear. In this study, osteoblastic cells UMR-106 were subjected to a moderate centrifugal stress at 209 x g for 10 min. Then the cell proliferation and gene transcription after centrifugation were analyzed with flow cytometry and Real-time RT-PCR techniques, respectively. The result showed that the cell proliferation and mRNA expression of Runx2/Cbfa1, Collagen I and osteocalcin changed shortly after centrifugal loading, but recovered to pre-load levels within 24 h. A dose-response study of exposure cells to centrifugal force at 209, 253 and 301 x g showed that the centrifugal forces within usually-used range can rapidly influenced the mRNA expression of the osteoblast-specific genes, but no statistical differences were found among the three centrifugal magnitudes. And the fast regulation in the investigated genes was proved to be related to increased c-fos mRNA levels and subsequent activation of RTK and integrity of cytoskeleton construction. The result showed that the osteoblastic cells displayed a fast auto-regulation to usually-used centrifugal stress through multiple signal pathways.

  2. Estimation of changes in dynamic hydraulic force in a magnetically suspended centrifugal blood pump with transient computational fluid dynamics analysis. (United States)

    Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori


    The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.

  3. The effect of centrifugation at various g force levels on rheological properties of rat, dog, pig and human red blood cells. (United States)

    Kiss, Ferenc; Toth, Eniko; Miszti-Blasius, Kornel; Nemeth, Norbert


    Laboratory investigations often require centrifugation of blood samples for various erythrocyte tests. Although there is a lack of data about the effect of centrifugation at various g force levels on erythrocyte rheological properties. We aimed to investigate the effect of a 10-minute centrifugation at 500, 1000 or 1500 g at 15°C of rat, dog, pig and human venous (K3-EDTA, 1.5 mg/ml) blood samples. Hematological parameters, erythrocyte deformability, cell membrane stability, osmotic gradient ektacytometry (osmoscan) and erythrocyte aggregation were determined. Hematological and erythrocyte deformability parameters showed interspecies differences, centrifugation caused no significant alterations. Cell membrane stability for human erythrocytes centrifuged at higher g level showed less decrease in deformability. Osmoscan O min parameter showed slight elevation in dog centrifuged aliquots. Erythrocyte aggregation parameters changed unexpectedly. Rat and dog erythrocyte aggregation indices significantly dropped in centrifuged aliquots. Pig erythrocyte aggregation indices increased significantly after centrifugation. Human erythrocyte aggregation was the most stable one among the investigated species. The used centrifugation protocols caused the largest alterations in erythrocyte aggregation in a controversial way among the investigated species. On the other hand, erythrocyte deformability parameters were stable, cell membrane stability and osmoscan data show minor shifts.

  4. A finite element perturbation method for computing fluid-induced forces on a centrifugal impeller rotating and whirling in a volute casing

    NARCIS (Netherlands)

    Jonker, J.B.; Essen, van T.G.


    A finite element based method has been developed for computing time-averaged fluid-induced radial excitation forces and rotor dynamic forces on a two-dimensional centrifugal impeller rotating and whirling in a volute casing. In this method potential flow theory is used, which implies the assumption

  5. Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blades of Different Blade Outlet Angles

    Directory of Open Access Journals (Sweden)

    Yasuyuki Nishi


    Full Text Available Single-blade centrifugal impellers for sewage systems undergo both unsteady radial and axial thrusts. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces and determine the generation mechanism behind them. In this study, we conducted component analyses of radial and axial thrusts of closed, single-blade centrifugal pumps with different blade outlet angles by numerical analysis while considering leakage flow. The results revealed the effect of the blade outlet angle on the components of radial and axial thrusts. For increased flow rates, the time-averaged values of the pressure component were similar for all impellers, although its fluctuating components were higher for impellers with larger blade outlet angles. Moreover, the fluctuating inertia component of the impeller with a blade outlet angle of 8° decreased as the flow rate increased, whereas those with 16° and 24° angles increased. Therefore, the radial thrust on the hydraulic part was significantly higher for impellers with high blade outlet angles.


    Directory of Open Access Journals (Sweden)

    A. A. Sukhotsky


    Full Text Available The paper describes development of the methodology for optimization of parameters for an additional operating force mechanism in a device for pneumo-centrifugal machining of glass balls. Specific feature in manufacturing glass balls for micro-optics in accordance with technological process for obtaining ball-shaped workpieces is grinding and polishing of spherical surface in a free state. In this case component billets of future balls are made in the form of cubes and the billets are given preliminary a form of ball with the help of rough grinding. An advanced method for obtaining ball-shaped work-pieces from brittle materials is a pneumocentrifugal machining. This method presupposes an application of two conic rings with abrasive working surfaces which are set coaxially with large diameters to each other and the billets are rolled along these rings. Rotation of the billets is conveyed by means of pressure medium.The present devices for pneumo-centrifugal machining are suitable for obtaining balls up to 6 mm. Machining of the work-pieces with full spherical surfaces and large diameter is non-productive due to impossibility to ensure a sufficient force on the billet in the working zone. For this reason the paper proposes a modified device where an additional force on the machined billet is created by upper working disc that is making a reciprocating motion along an axis of abrasive conic rings. The motion is realized with the help of a cylindrical camshaft mechanism in the form of a ring with a profile working end face and the purpose of present paper is to optimize parameters of the proposed device.The paper presents expressions for calculation of constitutive parameters of the additional operating force mechanism including parameters of loading element motion, main dimensions of the additional operating force mechanism and parameters of a profile element in the additional operating force mechanism.Investigation method is a mathematical

  7. Microfluidic devices, systems, and methods for quantifying particles using centrifugal force (United States)

    Schaff, Ulrich Y.; Sommer, Gregory J.; Singh, Anup K.


    Embodiments of the present invention are directed toward microfluidic systems, apparatus, and methods for measuring a quantity of cells in a fluid. Examples include a differential white blood cell measurement using a centrifugal microfluidic system. A method may include introducing a fluid sample containing a quantity of cells into a microfluidic channel defined in part by a substrate. The quantity of cells may be transported toward a detection region defined in part by the substrate, wherein the detection region contains a density media, and wherein the density media has a density lower than a density of the cells and higher than a density of the fluid sample. The substrate may be spun such that at least a portion of the quantity of cells are transported through the density media. Signals may be detected from label moieties affixed to the cells.

  8. Freeze-out extraction of monocarboxylic acids from water into acetonitrile under the action of centrifugal forces (United States)

    Bekhterev, V. N.


    It is established that the efficiency of the freezing-out extraction of monocarboxylic acids C3-C;8 and sorbic acid from water into acetonitrile increases under the action of centrifugal forces. The linear growth of the partition coefficient in the homologous series of C2-C8 acids with an increase in molecule length, and the difference between the efficiency of extracting sorbic and hexanoic acid, are discussed using a theoretical model proposed earlier and based on the adsorption-desorption equilibrium of the partition of dissolved organic compounds between the resulting surface of ice and the liquid phase of the extract. The advantages of the proposed technique with respect to the degree of concentration over the method of low-temperature liquid-liquid extraction are explained in light of the phase diagram for the water-acetonitrile mixture.

  9. Squeezing Force of the Magnetorheological Fluid Isolating Damper for Centrifugal Fan in Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Jin Huang


    Full Text Available Magnetorheological (MR disk-type isolating dampers are the semi-active control devices that use MR fluids to produce controllable squeezing force. In this paper, the analytical endeavor into the fluid dynamic modeling of an MR isolating damper is reported. The velocity and pressure distribution of an MR fluid operating in an axisymmetric squeeze model are analytically solved using a biviscosity constitutive model. Analytical solutions for the flow behavior of MR fluid flowing through the parallel channel are obtained. The equation for the squeezing force is derived to provide the theoretical foundation for the design of the isolating damper. The result shows that with the increase of the applied magnetic field strength, the squeezing force is increased.

  10. CENTRIFUGE APPARATUS (United States)

    Skarstrom, C.; Urey, H.C.; Cohen, K.


    A high-speed centrifuge for the separation of gaseous isotopes is designed comprising a centrifugal pump mounted on the outlet of a centrifuge bowl and arranged to pump the heavy and light fractions out of the centrifuge bowl in two separate streams.

  11. Centrifugal pumps

    CERN Document Server

    Gülich, Johann Friedrich


    This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The d...

  12. Centrifugal pump handbook

    CERN Document Server

    Pumps, Sulzer


    This long-awaited new edition is the complete reference for engineers and designers working on pump design and development or using centrifugal pumps in the field. This authoritative guide has been developed with access to the technical expertise of the leading centrifugal pump developer, Sulzer Pumps. In addition to providing the most comprehensive centrifugal pump theory and design reference with detailed material on cavitation, erosion, selection of materials, rotor vibration behavior and forces acting on pumps, the handbook also covers key pumping applications topics and operational


    Skarstrom, C.


    A centrifugal separator is described for separating gaseous mixtures where the temperature gradients both longitudinally and radially of the centrifuge may be controlled effectively to produce a maximum separation of the process gases flowing through. Tbe invention provides for the balancing of increases and decreases in temperature in various zones of the centrifuge chamber as the result of compression and expansions respectively, of process gases and may be employed effectively both to neutralize harmful temperature gradients and to utilize beneficial temperaturc gradients within the centrifuge.

  14. Centrifugal pumps

    CERN Document Server

    Anderson, HH


    Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The

  15. Centrifugal Sieve for Size-Segregation/ Beneficiation of Regolith Project (United States)

    National Aeronautics and Space Administration — Utilizing centrifugal force as the primary body-force, combined with both shearing flow and vibratory motion the proposed centrifugal-sieve separators can provide...

  16. Centrifugally decoupling touchdown bearings (United States)

    Post, Richard F


    Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

  17. Influence of relative centrifugal force on platelet concentration%相对离心力对浓缩血小板的实验研究

    Institute of Scientific and Technical Information of China (English)

    任贵汝; 范恩勇; 孙海英; 杨增旺


    目的探讨相对离心力(relative centrifugal force,RCF)对浓缩血小板(platelets concentrate,PC)的影响.方法利用分离富血小板血浆(platelet-rich plasma,PRP)法制备浓缩血小板.根据相对离心力的不同,分为试验组(A、B、C、D4组)和正常对照组.结果试验组较正常对照组在血小板(PLT)含量、红细胞(RBC)混入量、残余白细胞(WBC)等方面的差异均具有统计学意义(P<0.01).结论相对离心力过高或过低都会影响浓缩血小板的质量.

  18. 离心泵转子动力学模型中流体力的简化%Simplification of Fluid Force in Rotordynamic Model of Centrifugal Pumps

    Institute of Scientific and Technical Information of China (English)

    蒋爱华; 华宏星; 陈长盛; 李国平; 周璞; 章艺


    Simplification of the fluid force applied on impeller can significantly raise the accuracy of computation of centrifugal pump vibration incited by the fluid. In this paper, a rotor dynamic model including four discs, three shaft sections and a pump base is built for the workbench based on D'Alembert principle. Then fluid force on the impeller is simplified as 20 % fluid weight in impeller, 40 % fluid weight in impeller, and a concentrated force as well as a torque by CFD respectively. Finally, the transient response analysis is carried out by Newmark-implicit algorithm. The result shows that the base vibration incited by the fluid force during centrifugal pump operation can be effectively gained by simplifying the fluid force on the impeller to a concentrated force and a torque, and the amplitudes of acceleration and displacement of the base vibration by simplifying the fluid force to concentrated force and torque are much larger than those by simplifying the fluid force as 20 % and 40 % fluid weight in the impeller respectively. Also, the acceleration and displacement amplitudes by 40%fluid weight in the impeller are larger than those by 20%fluid weight in the impeller.%采用叶轮流体力的简化方式可以提高离心泵流体激励诱发振动的计算的准确程度。根据达朗伯原理对试验台架建立了包含离心泵基座的四圆盘三轴段转子动力学模型;将流体力分别简化为叶轮内20%流体质量、40%流体质量、CFD集中力与力矩,采用Newmark-隐式算法对转子动力学模型进行瞬态响应分析。结果表明,将叶轮上流体力简化为CFD;所得集中力与力矩时;可有效得出离心泵运转过程中流体激励所诱发的基座振动。而所获得的基座振动位移与加速度幅值均远大于将流体力简化为叶轮内20%或40%流体质量所获得的基座振动数值。另一方面,将流体力简化为叶轮内40%流体质量所获得的基座振动大于简化为叶轮内20

  19. Effect of Perturbations in Coriolis and Centrifugal Forces on the Nonlinear Stability of Equilibrium Point in Robe's Restricted Circular Three-Body Problem

    Directory of Open Access Journals (Sweden)

    P. P. Hallan


    Full Text Available The effect of perturbations in Coriolis and cetrifugal forces on the nonlinear stability of the equilibrium point of the Robe's (1977 restricted circular three-body problem has been studied when the density parameter K is zero. By applying Kolmogorov-Arnold-Moser (KAM theory, it has been found that the equilibrium point is stable for all mass ratios μ in the range of linear stability 8/9+(2/3((43/25ϵ1−(10/3ϵ<μ<1, where ϵ and ϵ1 are, respectively, the perturbations in Coriolis and centrifugal forces, except for five mass ratios μ1=0.93711086−1.12983217ϵ+1.50202694ϵ1, μ2 = 0.9672922−0.5542091ϵ+ 1.2443968ϵ1, μ3=0.9459503−0.70458206ϵ+ 1.28436549ϵ1, μ4=0.9660792−0.30152273ϵ + 1.11684064ϵ1, μ5=0.893981−2.37971679ϵ + 1.22385421ϵ1, where the theory is not applicable.

  20. Motion of a Point Mass in a Rotating Disc: A Quantitative Analysis of the Coriolis and Centrifugal Force

    Directory of Open Access Journals (Sweden)

    Haddout Soufiane


    Full Text Available In Newtonian mechanics, the non-inertial reference frames is a generalization of Newton’s laws to any reference frames. While this approach simplifies some problems, there is often little physical insight into the motion, in particular into the effects of the Coriolis force. The fictitious Coriolis force can be used by anyone in that frame of reference to explain why objects follow curved paths. In this paper, a mathematical solution based on differential equations in non-inertial reference is used to study different types of motion in rotating system. In addition, the experimental data measured on a turntable device, using a video camera in a mechanics laboratory was conducted to compare with mathematical solution in case of parabolically curved, solving non-linear least-squares problems, based on Levenberg-Marquardt’s and Gauss-Newton algorithms.

  1. Motion of a Point Mass in a Rotating Disc: A Quantitative Analysis of the Coriolis and Centrifugal Force (United States)

    Haddout, Soufiane


    In Newtonian mechanics, the non-inertial reference frames is a generalization of Newton's laws to any reference frames. While this approach simplifies some problems, there is often little physical insight into the motion, in particular into the effects of the Coriolis force. The fictitious Coriolis force can be used by anyone in that frame of reference to explain why objects follow curved paths. In this paper, a mathematical solution based on differential equations in non-inertial reference is used to study different types of motion in rotating system. In addition, the experimental data measured on a turntable device, using a video camera in a mechanics laboratory was conducted to compare with mathematical solution in case of parabolically curved, solving non-linear least-squares problems, based on Levenberg-Marquardt's and Gauss-Newton algorithms.

  2. Centrifugal pyrocontactor (United States)

    Chow, Lorac S.; Leonard, Ralph A.


    A method for mixing and separating immiscible liquid salts and liquid metals in a centrifugal contractor. The method includes introducing the liquids into an annular mixing zone and intensely mixing the liquids using vertical vanes attached to a rotor cooperating with vertical baffles, a horizontal baffle, and bottom vanes attached to the contactor housing. The liquids enter the contactor in the range of 700-800 degrees Celsius. The liquids are separated in the rotor into a dense phase and a light phase which are discharged from the contactor.

  3. Research on influencing factors of consolidation theory applicability in centrifugal force field%离心力场中固结理论适用性的影响因素研究

    Institute of Scientific and Technical Information of China (English)

    张莎莎; 谢永利


    为了明晰在较高的离心力场中,离心加速度及模型高度的变化对饱和土体固结理论适用性影响,提高离心力场中试验结果的可靠性,依据常规固结试验仪,研制了离心力场下的固结试验装置,并以此为基础,针对饱和砂土、典型海相土及河相土进行了不同离心力场下的固结模拟试验研究,同时对其试验时间与不同理论计算时间进行对比分析.结果表明,离心机模拟土体固结沉降时,离心加速度越大对总沉降量的影响也越大;在离心力场下,Terzaghi一维固结理论的应用有一定的局限性;不均匀离心力场和较高的模型高度对饱和土固结试验结果的影响较大,土体自重应予以考虑;现有离心模型试验的时间比尺应根据试验条件进行修正.%In order to research the impact of centrifugal model test results from the change of acceleration and the model height and improve the accuracy of centrifuge test results, based on conventional consolidation test instrument, The consolidation test device in centrifugal force field was developed. Taking the consolidation simulation of saturated sand, marine soil and saturated loess in different centrifugal acceleration field as subject, the comparison of test time and different theoretical computation time were analyzed. It is indicated that there are two phases in the consolidation process of saturated soil in centrifugal model test, namely the quick consolidation and the sequent slow consolidation. The quick consolidation process is mainly influenced by centrifugal acceleration. The application Terzaghi one-dimensional consolidation theory has its limitations in centrifugal force field. Uneven distribution and high of centrifugal acceleration on the model has a greater impact on the results, were the impact of soil weight must be considered. The existing time scale formula should be corrected by the test conditions.

  4. Solid-phase based on-chip DNA purification through a valve-free stepwise injection of multiple reagents employing centrifugal force combined with a hydrophobic capillary barrier pressure. (United States)

    Zhang, Hainan; Tran, Hong Hanh; Chung, Bong Hyun; Lee, Nae Yoon


    In this paper, we demonstrate a simple technique for sequentially introducing multiple sample liquids into microchannels driven by centrifugal force combined with a hydrophobic barrier pressure and apply the technique for performing solid-phase based on-chip DNA purification. Three microchannels with varying widths, all equipped with independent sample reservoirs at the inlets, were fabricated on a hydrophobic elastomer, poly(dimethylsiloxane) (PDMS). First, glass beads were packed inside the reaction chamber, and a whole cell containing the DNA extract was introduced into the widest channel by applying centrifugal force for physical adsorption of the DNA onto the glass beads. Next, washing and elution solutions were sequentially introduced into the intermediate and narrowest microchannels, respectively, by gradually increasing the amount of centrifugal force. Through a precise manipulation of the centrifugal force, the DNA adsorbed onto the glass beads was successfully washed and eluted in a continuous manner without the need to introduce each solution manually. A stepwise injection of liquids was successfully demonstrated using multiple ink solutions, the results of which corresponded well with the theoretical analyses. As a practical application, the D1S80 locus of human genomic DNA, which is widely used for forensic purposes, was successfully purified using the microdevice introduced in this study, as demonstrated through successful target amplification. This will pave the way for the construction of a control-free valve system for realizing on-chip DNA purification, which is one of the most labor-intensive and hard-to-miniaturize components, on a greatly simplified and miniaturized platform employing hydrophobic PDMS.

  5. 压水室结构对离心泵径向力影响的数值分析%Numerical analysis the influence of collector configurations on radial force for centrifugal pumps

    Institute of Scientific and Technical Information of China (English)

    江伟; 李国君; 张新盛


    采用SST k-ω湍流模型对不同压水室结构:单蜗壳、双蜗壳、导叶和蜗壳匹配同一叶轮的离心泵进行定常和非定常数值模拟.根据数值计算结果比较并分析3种不同结构压水室离心泵外特性、定常和非定常径向力特性.结果表明,在全流量下,单蜗壳和双蜗壳离心泵流量-扬程曲线变化平缓,效率高效区较宽;单蜗壳离心泵径向力远大于其他2种形式离心泵;导叶式离心泵径向力方向随着流量增加基本不变,其他2种形式离心泵径向力方向随着流量的增加变化较大且从隔舌向蜗壳出口移动;单蜗壳离心泵和双蜗壳离心泵径向力整体变化趋势呈椭圆分布,导叶式离心泵径向力变化无规律性;单蜗壳离心泵径向力平衡较差,瞬态径向力幅度波动远大于其他2种形式离心泵.分析结果可对离心泵径向力的认识和设计提供依据.%Using SST k - ω turbulent model, both steady and unsteady numerical methods were applied to simulate centrifugal pumps with various collectors of single volute, double volute, and vaned diffuser with a volute, in which the same impeller was adopted. The overall characteristics, steady and unsteady radial forces characteristics of the centrifugal pumps with three different collectors were compared and analyzed according to the simulated results. The results show that the curves of capacity-head of both single volute and double volute centrifugal pump are flat and the high efficiency areas are relatively wide. Radial force of the single volute centrifugal pump is much larger than that of the other two. As flow rate increases, radial force direction of the vaned centrifugal pump changes slightly, while those of the other two change greatly and move from the tongue to the volute exit. The overall trend of radial forces of single volute and double volute centrifugal pumps is elliptic distribution, and that of the vaned centrifugal pump is irregular. Radial

  6. Unshrouded Centrifugal Turbopump Impeller (United States)

    Prueger, George; Williams, Morgan; Chen, Wei; Paris, John; Stewart, Eric; Williams, Robert


    The ratio of rocket engine thrust to weight is a limiting constraint in placing more payload into orbit at a low cost. A key component of an engine's overall weight is the turbopump weight, Reducing the turbopump weight can result in significant engine weight reduction and hence, increased delivered payload. There are two main types of pumps: centrifugal and axial pumps. These types of pumps can be further sub-divided into those with shrouds and those without shrouds (unshrouded pumps). Centrifugal pumps can achieve the same pump discharge pressure as an axial pump and it requires fewer pump stages and lower pump weight than an axial pump. Also, with unshrouded centrifugal pumps (impeller), the number of stages and weight can be further reduced. However. there are several issues with regard to using an unshrouded impeller: 1) there is a pump performance penalty due to the front open face recirculation flow; 2) there is a potential pump axial thrust problem from the unbalanced front open face and the back shroud face; and, 3) since test data is very linu'ted for this configuration, there is uncertainty in the magnitude and phase of the rotordynamics forces due to the front impeller passage. The purpose of the paper is to discuss the design of an unshrouded impeller and to examine the design's hydrodynamic performance, axial thrust, and rotordynamics performance. The design methodology will also be discussed. This work will help provide some guidelines for unshrouded impeller design. In particular, the paper will discuss the design of three unshrouded impellers - one with 5 full and 5 partial blades (5+5). one with 6+6 blades and one with 8+8 blades. One of these designs will be selected for actual fabrication and flow test. Computational fluid dynamics (CFD) is used to help design and optimize the unshrouded impeller. The relative pump performance penalty is assessed by comparing the CFD results of the unshrouded impeller with the equivalent shrouded impeller for a

  7. Possible biomedical applications and limitations of a variable-force centrifuge on the lunar surface: A research tool and an enabling resource (United States)

    Cowing, Keith L.


    Centrifuges will continue to serve as a valuable research tool in gaining an understanding of the biological significance of the inertial acceleration due to gravity. Space- and possibly lunar-based centrifuges will play a significant and enabling role with regard to the human component of future lunar and martian exploration, both as a means of accessing potential health and performance risks and as a means of alleviating these risks. Lunar-based centrifuges could be particularly useful as part of a program of physiologic countermeasures designed to alleviate the physical deconditioning that may result from prolonged exposure to a 1/6-g environment. Centrifuges on the lunar surface could also be used as part of a high-fidelity simulation of a trip to Mars. Other uses could include crew readaptation to 1 g, waste separation, materials processing, optical mirror production in situ on the Moon, and laboratory specimen separation.

  8. 饱和土二维固结试验在离心力场条件下的适用性分析%The Applicability of Two-dimensional Consolidation Test of Saturated Soil in Centrifugal Force Filed

    Institute of Scientific and Technical Information of China (English)

    张莎莎; 谢永利; 刘保健


    土工离心模型试验技术是各类土工物理模型试验中相似性能最好的模型试验,由于试验条件限制,通常认为其进行的都是一维单面排水固结试验,而实际工程中,地基的侧向排水会加速超静水压力的消散,对其固结沉降有较大影响.为了探索更接近于实际情况的土体固结特性,及其在二维排水条件下饱和土的离心模型固结特点,基于离心机模型箱的改造设计,对典型区域饱和土体的二维固结特性进行了离心模型试验研究及其试验结果的对比分析.结果表明,在离心力场条件下,固结系数对土体的试验结果影响较大,固结系数较小的饱和土样二维固结试验特性更接近于理论;土工离心模型试验具有饱和土二维固结特性研究的基础条件.%Geotechnical centrifugal model test similar to the best performance in various types of geotechnical physical model test. Because of the test conditions, centrifugal model test is used to be one-dimensional consolidation test. In fact, lateral drainage of ground will accelerate the dissipation of excess hydrostatic pressure and affect the consolidation settlement. In order to study more practical features of saturated soil consolidation in the two-dimensional drainage conditions centrifuge model test, the centrifuge model box is transformation designed. Typical causes of saturated soil in different areas under the two-dimensional drainage conditions of centrifugal consolidation tests are studied. It is indicated that, in the centrifugal consolidation force filed conditions, the consolidation characteristics of saturated soil with smaller consolidation coefficient was closer to two-dimensional consolidation theory. Geotechnical centrifuge model test can provide foundation conditions for a two-dimensional consolidation test of saturated soil.

  9. The Relationship between Centrifugal Force,Centripetal Force and Innovation Performance of Heterogeneous Team with Shared Leadership as Moderator%异质性团队离心力、向心力与创新绩效:以共享领导为调节变量

    Institute of Scientific and Technical Information of China (English)

    董欣; 杨皎平; 李庆满


    The influence of team heterogeneity on its innovation performance is studied with centrifugal force and centripetal force as intermediary variables and shared leadership as moderator .Regression analysis has show n that member heteroge‐neity increases centrifugal force and decreases centripetal force ,and both the centrifugal force and the centripetal force are positive related to the innovation performance .Furthermore ,the positive relationship between member heterogeneity and the team centrifugal force is positively adjusted by the shared leadership , how ever , the negative relationship betw een member heterogeneity and the team centripetal force is negatively adjusted by the shared leadership .%以离心力和向心力为中介变量,以共享领导为调节变量,实证考察了高技术企业研发团队成员异质性对团队创新绩效的影响。研究发现:成员异质性一方面增加了团队向心力而具有创新优势,另一方面增加了离心力而具有创新劣势;共享领导作为调节变量,正向调节了成员异质性与团队离心力的正相关关系,负向调节了成员异质性与团队向心力的负相关关系。

  10. 地球自转及天体作用力对精密离心机的影响%Influence of Earth’s Rotation and Celestial Forces on Precision Centrifuge

    Institute of Scientific and Technical Information of China (English)

    凌明祥; 王珏; 宁菲; 卢永刚; 李明海; 黎启胜


    Objective To satisfy acceleration’s precision of 10-6 precision centrifuge. Methods Considering misalignment angles between accelerometer and centrifuge,between centrifuge and earth,Coriolis acceleration generated by earth’s rotation acting on the input axis of accelerometer was deduced employing homogeneous coordinate transform matrix. The mathematical expression of acceleration generated by the Moon and the Sun on precision centrifuge was also built. The order of magnitude and impact of Coriolis acceleration,the Moon and the Sun’s force were calculated and analyzed. Results Coriolis acceleration’s order of magnitude was 10-5 m/s2. The order of magnitude of the Moon and the Sun ’s force was 10-6 m/s2. Conclusion As to our developed precision centrifuge,the influence of Coriolis acceleration must be considered and compensated while the influence of Moon and Sun’s force can be neglected.%目的:研究地球自转产生的科里奥利力及天体作用力对高精度精密离心机的影响规律。方法考虑精密离心机实际存在的各种失准角,采用齐次变换方法推导由地球自转在加速度计输入轴上产生的科里奥利加速度数学表达式;建立天体作用力对精密离心机上加速度计影响的数学关系式。结果科氏加速度对精密离心机的影响量级为10-5 m/s2;月球和太阳作用力的最大影响量级之和为10-6 m/s2。结论对于10-6量级精度的精密离心机,必须补偿科氏加速度的影响;月球和太阳作用力的影响可以忽略不计。

  11. Fabrication of Al/Diamond Particles Functionally Graded Materials by Centrifugal Sintered-Casting Method (United States)

    Watanabe, Yoshimi; Shibuya, Masafumi; Sato, Hisashi


    The continuous graded structure of functionally graded materials (FGMs) can be created under a centrifugal force. Centrifugal sintered-casting (CSC) method, proposed by the authors, is one of the fabrication methods of FGM under centrifugal force. This method is a combination of the centrifugal sintering method and centrifugal casting method. In this study, Al/diamond particle FGM was fabricated by the proposed method.


    Energy Technology Data Exchange (ETDEWEB)

    Daniel J. Stepan; Bradley G. Stevens; Melanie D. Hetland


    The overall project consists of several integrated research phases related to the applicability, continued development, demonstration, and commercialization of the SpinTek centrifugal membrane filtration process. Work performed during this reporting period consisted of Phase 2 evaluation of the SpinTek centrifugal membrane filtration technology and Phase 3, Technology Partnering. During Phase 1 testing conducted at the EERC using the SpinTek ST-IIL unit operating on a surrogate tank waste, a solids cake developed on the membrane surface. The solids cake was observed where linear membrane velocities were less than 17.5 ft/s and reduced the unobstructed membrane surface area up to 25%, reducing overall filtration performance. The primary goal of the Phase 2 research effort was to enhance filtration performance through the development and testing of alternative turbulence promoter designs. The turbulence promoters were designed to generate a shear force across the entire membrane surface sufficient to maintain a self-cleaning membrane capability and improve filtration efficiency and long-term performance. Specific Phase 2 research activities included the following: System modifications to accommodate an 11-in.-diameter, two-disk rotating membrane assembly; Development and fabrication of alternative turbulence promoter designs; Testing and evaluation of the existing and alternative turbulence promoters under selected operating conditions using a statistically designed test matrix; and Data reduction and analysis; The objective of Phase 3 research was to demonstrate the effectiveness of SpinTek's centrifugal membrane filtration as a pretreatment to remove suspended solids from a liquid waste upstream of 3M's WWL cartridge technology for the selective removal of technetium (Tc).

  13. Fluid-induced Forces in Centrifugal Pump under Given Rotordynamic Parameters%给定转子动力学参数的离心泵内部流体力研究

    Institute of Scientific and Technical Information of China (English)

    潘中永; 陈士星; 吴燕兰; 张大庆; 李彦军


    通过数值模拟和试验,研究了涡动情况下偏心距和涡动频率比对离心泵内外特性的影响.在给定一系列转子动力学参数条件下,采用RNG k-ε湍流模型对包含前后泵腔在内的全流场进行数值模拟,分析了偏心距对离心泵外特性的影响和涡动频率比对离心泵内部流场的影响,研究了离心泵内部流体力的分布情况以及偏心距和涡动频率比对离心泵内部流体力的影响.研究结果表明:随着偏心距的增大,泵高效区范围变窄;流体力的法向分力Fn、切向分力Ft均与涡动频率比ω/Ω近似呈二次函数关系,这种二次函数关系与偏心距大小相关;叶轮受到的流体力主要来源于叶轮内部流体,且叶轮内部流体周向压力分布不均.对于离心泵来说,当ω/Ω>O时,叶轮内的旋涡较少,水力损失较小,对涡动效果有抑制作用;当ω/Ω<0时,叶轮内旋涡较多,水力损失较大,对涡动效果有促进作用.%The effect of eccentricity and whirl frequency ratio on the internal and external characteristics of a centrifugal pump was investigated numerically and experimentally.Under a series of given rotordynamic parameters,the RNG k-ε turbulence model was applied in the simulation of whole flow field including front and back shrouds of pump.The influence of eccentricity on the external characteristics of the centrifugal pump and the impact of whirl frequency ratio on the internal flow field were analyzed.Then the distribution of the fluid-induced forces in the centrifugal pump and the effect of eccentricity and whirl frequency ratio on the fluid-induced forces in the centrifugal pump were investigated.According to the results,it could be drawn that the high efficiency area of centrifugal pump narrows as the eccentricity increases.Normal fluid force component Fn and tangential fluid force component Ft were both approximate into a quadratic function relation against the whirl frequency ratio

  14. 离心力、时间对富血小板血浆中生长因子浓度的影响%The Influence of Centrifugal Force and Time on Growth Factor Concentration in Platelet Rich Plasma

    Institute of Scientific and Technical Information of China (English)

    林颢; 孙杰聪; 李广盛; 郑锦畅; 魏波


    Objective To detect the concentration of TGF-β in platelet rich plasma (PRP) that was prepared under dif erent centrifugal force and time, and make a related analysis. Aiming to investigate the most appropriate centrifugal force and time for preparing PRP. Methods Collect 200ml peripheral blood from volunteers, anticoagulated it with EDTA at stored at 4℃ for later use. Ful-automatic blood analyzer was used for the platelet counting, isolated the PRP by quadratic centrifugation (with dif erent centrifugal force and time),then counted the platelet again with full-automatic blood analyzer. The concentration of TGF-β in PRP was detected by ELISA detection. Results The concentration of platelet in peripheral blood was 146.36í109/L, and in PRP was (757.27±55.07)í109L.The concentration of TGF-β in PRP was (737.68±62.7)ng/ml.We found that the concentration of TGF-β in PRP that isolated under 900g,10min combined with 700g,10min was the highest (881.5í10)9/L,824.2 ng/ml).Conclusion The quality of PRP the preparation is closely related to the centrifugal force and time. The appropriate centrifugation and time is more likely to a get high concentration of PRP that rich in growth factors.%目的探索应用不同的离心速度来制备的富血小板血浆(platelet rich plasma,PRP)中TGF生长因子的含量,并做相关分析,尝试阐明制备PRP最合适的离心次数及速度。方法采集自愿者外周血200ml,应用EDTA抗凝,4º保存以备用。应用全自动血液分析仪进行血小板计数,采用二次离心法(不同的离心速度、时间)分离出PRP,再次用全自动血液分析仪进行血小板计数,然后用ELISA法检测所得的PRP中的TGF-β的浓度。结果外周血中的血小板浓度为146.36×109L,PRP的血小板浓度为(757.27±55.07)×109L。 PRP中的TGF-β浓度为(737.68±62.7)ng/ml。其中以900g,10min,700g,10min,这个离心速度与时间组合所得的PRP血小板

  15. Gas dynamics in strong centrifugal fields

    Energy Technology Data Exchange (ETDEWEB)

    Bogovalov, S.V.; Kislov, V.A.; Tronin, I.V. [National research nuclear university “MEPhI”, Kashirskoje shosse, 31,115409, Moscow (Russian Federation)


    Dynamics of waves generated by scopes in gas centrifuges (GC) for isotope separation is considered. The centrifugal acceleration in the GC reaches values of the order of 106g. The centrifugal and Coriolis forces modify essentially the conventional sound waves. Three families of the waves with different polarisation and dispersion exist in these conditions. Dynamics of the flow in the model GC Iguasu is investigated numerically. Comparison of the results of the numerical modelling of the wave dynamics with the analytical predictions is performed. New phenomena of the resonances in the GC is found. The resonances occur for the waves polarized along the rotational axis having the smallest dumping due to the viscosity.

  16. Dewatering of fine coal using hyperbaric centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Ramazan Asmatulu; Gerald H. Luttrell; Roe-Hoan Yoon [Virginia Polytechnic Institute and State University, Blacksburg, VA (US). Center for Advanced Separation Technologies


    Many coal preparation plants are forced to discard their fine coal because of the inability of existing technologies to reduce the moisture content of this product to an acceptable level. In an effort to overcome this problem, a new mechanical dewatering method has been developed that combines centrifugation with pressure filtration. The process, which may be referred to as hyperbaric centrifugation, is capable of producing a drier product than can be achieved using either filtration or centrifugation alone. The test data obtained from batch experiments show that the new method can reduce cake moisture to 10% or below for many fine coal product streams.

  17. The Analysis of the Effects of Centrifugal Force on the Wind Turbine Blade Structural Properties%离心力对风力发电机组叶片结构性能的影响分析

    Institute of Scientific and Technical Information of China (English)

    羊森林; 赵萍; 钟贤和; 李杰


    The effects of stiffening caused by the rotating centrifugal force on the blade structural properties were studied, basing on one type of MW wind turbine blade. The results show that the natural frequency of blade increase significantly, the displacements and strains decrease obviously due to the effects of rotating centrifugal force. Meanwhile, the blade structure stability was enhanced to some extent. The analysis results have good reference to the design of wind turbine blades in future.%基于某兆瓦级大型风力发电机组,研究了离心力引起的刚化效应对风电机组叶片结构性能的影响。结果表明,离心力将使叶片的低阶固有频率显著增加,叶片的位移变形和应变显著减小,同时在一定程度上提升了叶片的结构稳定性。分析结果对后续风电叶片的设计具有参考和借鉴意义。

  18. Combination Of Investment And Centrifugal Casting (United States)

    Creeger, Gordon A.


    Modifications, including incorporation of centrifugal casting, made in investment-casting process reducing scrap rate. Used to make first- and second-stage high-pressure-fuel-turbopump nozzles, containing vanes with thin trailing edges and other thin sections. Investment mold spun for short time while being filled, and stopped before solidification occurs. Centrifugal force drives molten metal into thin trailing edges, ensuring they are filled. With improved filling, preheat and pour temperatures reduced and solidification hastened so less hot tearing.

  19. Centrifuge modeling of monopiles

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte


    To gain a larger knowledge of the monopile foundation concept, centrifuge modeling is used by the geotechnical group at DTU. The centrifuge operated at DTU is a beam centrifuge and was built in 1976. In the recent years it has been upgraded with onboard data acquisition and control systems. The c...... from centrifuge tests performed on large diameter piles installed in dry sand.......To gain a larger knowledge of the monopile foundation concept, centrifuge modeling is used by the geotechnical group at DTU. The centrifuge operated at DTU is a beam centrifuge and was built in 1976. In the recent years it has been upgraded with onboard data acquisition and control systems....... The capabilities of the centrifuge at DTU makes it possible to obtain a scale factor of 85 in experiments which equals a soil volume in prototype scale of a diameter of 40 meters and a depth of 40 meters. This paper describes centrifuge modeling theory, the centrifuge setup at DTU and as an example show results...

  20. 叶片包角对泵作透平水力径向力的影响%Effect of blade wrap angle on the radial force of centrifugal pump as turbine

    Institute of Scientific and Technical Information of China (English)

    代翠; 孔繁余; 董亮; 张慧; 冯子政


    In order to study the effects of blade wrap angle on the radial force of a centrifugal pump as turbine,a single volute vaneless counter-rotating centrifugal pump was chosen as the research object.In the study,the blade wrap angle was varied from 100°to 115°and 130°,while the volute and other geometric parameters were kept constant.The transient flow characteristics under various operating conditions in the whole flow passage of the centrifugal pump as turbine were studied numerically by using the computational fluid mechanics software CFX.The results show that when the blade warp angle increases beyond a certain value,the radial force on the impeller reduces slightly at low flow rates and obviously at high flow rates.The radial force on the volute reduces and moves to the fourth quadrant as the blade warp angle increases.The blade warp angle should be within a suitable range to ensure a lower radial force level at higher flow rates.%为研究叶片包角对离心泵作透平瞬态水力径向力的影响,以一台蜗壳式离心泵反转作透平为研究对象,保持叶轮和蜗壳其他几何参数不变,应用计算流体力学软件 CFX 对泵作透平全流道内多工况瞬态流动特性进行数值计算,并对预测性能进行了试验验证。结果表明,作用在叶轮上的径向力,当叶片包角增加超过一定值时小流量工况下减小不明显,而大流量下减小显著。随包角增加,作用于蜗壳上的径向力减小并向第四象限偏移。叶片包角存在一个合适的取值范围,使得泵作透平运行在大流量工况下时径向力较小。

  1. Possible segregation caused by centrifugal titanium casting. (United States)

    Watanabe, K; Okawa, S; Kanatani, M; Nakano, S; Miyakawa, O; Kobayashi, M


    The possibility of the segregation under solidification process using a centrifugal casting machine was investigated using an electron probe microanalyzer with elemental distribution map, line analysis and quantitative analysis. When a very small quantity of platinum was added to local molten titanium during the casting process, macroscopic segregation was observed under conditions of density difference of 0.1 g/cm3 at the most, confirming that the centrifugal force of the casting machine is extremely strong. When a Ti-6Al-4V alloy was cast, however, no macroscopic segregation was observed. The centrifugal force of the casting machine examined in the present study hardly results in the body-force segregation in this titanium alloy.


    Cohen, K.


    A method of isotope separation is described in which two streams are flowed axially of, and countercurrently through, a cylindrical centrifuge bowl. Under the influence of a centrifugal field, the light fraction is concentrated in a stream flowing through the central portion of the bowl, whereas the heavy fraction is concentrated in a stream at the periphery thereof.

  3. Computer simulation for centrifugal mold filling of precision titanium castings

    Institute of Scientific and Technical Information of China (English)


    Computer simulation codes were developed based on a proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings (CASM-3D for Windows). Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings under a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section precision castings.

  4. Research on the development of the centrifugal spinning

    Directory of Open Access Journals (Sweden)

    Zhang Zhiming


    Full Text Available Centrifugal spinning is a new and efficient method to produce nanofibers quickly. It makes use of the centrifugal force instead of high voltage to produce the nanofibers. The centrifugal spinning has many advantages such as no high voltage, high yield, simple structure, no pollution and can be applied to high polymer material, ceramic and metal material. In order to have more understand about this novel nanofibers formation method, this paper introduces the method of centrifugal spinning and the effect of rotation speed, the properties of material such as viscosity and solvent evaporation, collector distance which have an impact on nanofibers morphology and diameter were also analyzed.


    Institute of Scientific and Technical Information of China (English)

    Dong Longlei; Yan Guirong; Li Ronglin


    The mechanical characteristics of the electro-hydraulic servo system in the centrifuge field are analyzed.The hydraulic pressure law in the centrifuge field indicates the existence of the centrifuge hydraulic pressure.The mechanical characteristics of the slide-valve and the dual nozzle flapper valve are studied,and it is found that the centrifuge field can not only increase the driving force or moment of the function units,but also decrease the stability of the components.Finally by applying Gauss minimum constraint principle,the dynamic model of the electro-hydraulic vibrator in the centrifuge field is established,and the mechanical restriction of the system is also presented.The study will be helpful for the realization of the combined vibration and centrifuge test system.


    Directory of Open Access Journals (Sweden)

    Adedipe Oyewole


    Full Text Available The design and fabrication of a centrifugal casting machine was successfully carried out. The operation of the machine was based on the principle of centrifugal force. Suitable design theory, analysis and calculation were adopted carried out in the course of the work. The mold is bolted to the base plate which can rotate at moderatespeeds thereby forcing the molten metal against the inner walls of the mold. This machine could be used to cast small engineering components. The centrifugal force on the machine was determined to be 3207.3N, while the required power on the machine was 854.7W. A test was carried out on the fabricated centrifugal casting machine with aluminum alloy and the machine was able to cast 6kg of aluminum alloy and the casting was successful.

  7. 双蜗壳式双吸泵隔板结构对叶轮径向力的影响%Influence of Rib Structure in Double-volute Centrifugal Pumps on the Impeller Radial Force

    Institute of Scientific and Technical Information of China (English)

    肖若富; 吕腾飞; 王福军


    Double-volute casings were introduced to reduce the radial force that is inherent in single-volute designs. A general three-dimensional computational fluid dynamics ( CFD) simulation of a double-volute centrifugal pump was presented to predict hydraulic performance and impeller radial force. By using the shear stress transport ( SST) k - to turbulent model, the simulation results in the form of characteristic curves were compared with the experimental data. The result presented that the head and efficiency of the original double-volute pump drop were 21. 8% and 41. 3% respectively at design point due to the failed dividing rib (splitter) in the volute casing. Thus, with the aim to analyze the effects of rib structure on pumps, three optimized rib schemes were designed to reduce the impeller radial force and keep the hydraulic performance. Three factors were considered in the rib design; start point, end point and curve equation. According to the steady numerical simulation result in each optimized scheme by CFD, No. 2 scheme reduced about half of the radial force while keeping the hydraulic performance. A method in designing the rib structure for double-volute centrifugal pumps was provided.%分别对单、双蜗壳式双吸泵10个工况点进行全三维流道的数值模拟和试验测试,发现由于双蜗壳式泵内部隔板设计不合理,导致双蜗壳泵较单蜗壳泵在原设计工况点的扬程、效率分别相对下降了21.8%和41.3%.依据双蜗壳设计基本原理,对隔板结构提出3种改进方案,利用雷诺时均方法( RANS)和SSTk -ω湍流模型对每一方案进行全三维流道的定常数值模拟.模拟和试验结果表明:2号双蜗壳泵既保持了泵原有的水力性能,又能够有效地减小叶轮径向力,因此得到双蜗壳式双吸泵中隔板结构的最优设计模型:起始位置为隔舌绕基圆旋转180°、曲线方程为对数螺旋线、终止位置为隔板起始点旋转180°.

  8. Maryland Centrifugal Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hassam, Adil; Ellis, Richard F


    The Maryland Centrifugal Experiment (MCX) Project has investigated the concepts of centrifugal plasma confinement and stabilization of instabilities by velocity shear. The basic requirement is supersonic plasma rotation about a shaped, open magnetic field. Overall, the MCX Project attained three primary goals that were set out at the start of the project. First, supersonic rotation at Mach number upto 2.5 was obtained. Second, turbulence from flute interchange modes was found considerably reduced from conventional. Third, plasma pressure was contained along the field, as evidenced by density drops of x10 from the center to the mirror throats.

  9. Perceived radial translation during centrifugation

    NARCIS (Netherlands)

    Bos, J.E.; Correia Grácio, B.J.


    BACKGROUND: Linear acceleration generally gives rise to translation perception. Centripetal acceleration during centrifugation, however, has never been reported giving rise to a radial, inward translation perception. OBJECTIVE: To study whether centrifugation can induce a radial translation percepti

  10. Pumps, Centrifugal and Reciprocating (United States)


    guidance for preparing test plans and conducting test programs to evaluate the effectiveness and suitability for military use of centrifugal and...This page is intentionally blank.)   US ARMY DEVELOPMENTAL TEST COMMAND TEST...Satisfy the needs of MIL-STD-4612. High-Altitude Electromagnetic Pulse ( HEMP ) Test Facility Satisfy the needs of MIL-STD-461. Rail Impact Test

  11. Centrifugal atomisation of alloys

    Energy Technology Data Exchange (ETDEWEB)

    Li Huiping [School of Mechanical and Materials Engineering, Univ. of Surrey, Guilford (United Kingdom); Dept. of Inorganic Materials, East China Univ. of Science and Technology, Shanghai, SH (China); Tsakiropoulos, P. [School of Mechanical and Materials Engineering, Univ. of Surrey, Guilford (United Kingdom); Johnson, T. [Tetronics Ltd., Faringdon, Oxfordshire (United Kingdom)


    Centrifugal atomisation using a rotating disk is described and compared to REP and PREP. Results of calculations of models describing the interaction of a melt with a rotating disk, the formation of thin film on the disk and the break up of the thin film and its atomisation at the edge of the disk are compared with experimental results. (orig.)

  12. Central centrifugal cicatricial alopecia

    Directory of Open Access Journals (Sweden)

    Collin Blattner


    Full Text Available Central centrifugal cicatricial alopecia is a common cause of progressive permanent apical alopecia. This unique form of alopecia includes entities previously know as "hot comb alopecia," "follicular degeneration syndrome," "pseudopelade" in African Americans and "central elliptical pseudopelade" in Caucasians. The etiology appears to be multifactorial and the condition occurs in all races.

  13. Force

    CERN Document Server

    Graybill, George


    Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.

  14. Centripetal/Centrifugal Family Style of Families with Aggressive and Non-Aggressive Boys. (United States)

    Hurst, Duane F.; And Others

    Research on family interaction has characterized family style on centripetal and centrifugal dimensions, representing opposing natures with their own continua. Centripetal forces produce binding, or a prolonged process of separation of parent and child; centrifugal forces preciptate expelling, or hastened separation and premature autonomy. To…

  15. The theory of the centrifugal mechanism of feeding-in in bent crystals



    For a particle channeled in the bent crystal planes (axes), the phenomenon of "bending dechanneling", which is a particle transition to a random state due to centrifugal force, is well known. We consider an analytical theory of the reverse phenomenon, i.e., feeding from a random state to a channeled state due to centrifugal force in a crystal with variable curvature.

  16. Shallow water model for horizontal centrifugal casting (United States)

    Boháček, J.; Kharicha, A.; Ludwig, A.; Wu, M.


    A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to zero velocity on the mould wall, gravity, and energy transport by the flow. Additionally, a 1D sub-model was implemented to consider the heat transfer in the radial direction from the solidifying shell to the mould. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free liquid surface and the outer wall of the mould. Several cases were simulated with the following assumed initial conditions: constant height of the liquid metal (10, 20, and 30 mm), uniform temperature of the free liquid surface (1755 K). The simulation results have shown that while the solidification front remained rather flat, the free surface was disturbed by waves. The amplitude of waves increased with the liquid height. Free surface waves diminished as the solidification proceeded.

  17. Parameter Study of Melt Spun Polypropylene Fibers by Centrifugal Spinning (United States)


    synthesis of C/Fe3O4 composite nanofibers and their application for high performance lithium-ion batteries . J Power Sources. 2008;83:717–723. 2. Zhang...spinning process . Eur Polym J. 2013;49:3834–3845. 9 1 DEFENSE TECHNICAL (PDF) INFORMATION CTR DTIC OCA 2 DIRECTOR (PDF) US ARMY RESEARCH...composites, and energy harvesting to tissue engineering and drug delivery. Centrifugal spinning is a new technique that uses centrifugal forces to form

  18. Centrifugal unbalance detection system (United States)

    Cordaro, Joseph V.; Reeves, George; Mets, Michael


    A system consisting of an accelerometer sensor attached to a centrifuge enclosure for sensing vibrations and outputting a signal in the form of a sine wave with an amplitude and frequency that is passed through a pre-amp to convert it to a voltage signal, a low pass filter for removing extraneous noise, an A/D converter and a processor and algorithm for operating on the signal, whereby the algorithm interprets the amplitude and frequency associated with the signal and once an amplitude threshold has been exceeded the algorithm begins to count cycles during a predetermined time period and if a given number of complete cycles exceeds the frequency threshold during the predetermined time period, the system shuts down the centrifuge.

  19. A Maxwellian Valve based on centrifugal forces

    Directory of Open Access Journals (Sweden)

    Lyndsay G.M. Gordon


    Full Text Available Abstract: A mechanism is described which can create a chemical potential gradient from a single heat reservoir. The mechanism is equivalent to a Maxwellian valve. Heat supplies the energy through thermal fluctuations to form the gradient contrary to the second law. A quantitative analysis of the system is given.

  20. Centrifugally activated bearing for high-speed rotating machinery (United States)

    Post, Richard F.


    A centrifugally activated bearing is disclosed. The bearing includes an annular member that extends laterally and radially from a central axis. A rotating member that rotates about the central axis relative to the annular member is also included. The rotating member has an interior chamber that surrounds the central axis and in which the annular member is suspended. Furthermore, the interior chamber has a concave shape for retaining a lubricant therein while the rotating member is at rest and for retaining a lubricant therein while the rotating member is rotating. The concave shape is such that while the rotating member is rotating a centrifugal force causes a lubricant to be forced away from the central axis to form a cylindrical surface having an axis collinear with the central axis. This centrifugally displaced lubricant provides restoring forces to counteract lateral displacement during operation.

  1. Comparative analysis of discrete exosome fractions obtained by differential centrifugation

    DEFF Research Database (Denmark)

    Jeppesen, Dennis Kjølhede; Hvam, Michael L; Primdahl-Bengtson, Bjarke


    BACKGROUND: Cells release a mixture of extracellular vesicles, amongst these exosomes, that differ in size, density and composition. The standard isolation method for exosomes is centrifugation of fluid samples, typically at 100,000×g or above. Knowledge of the effect of discrete...... ultracentrifugation speeds on the purification from different cell types, however, is limited. METHODS: We examined the effect of applying differential centrifugation g-forces ranging from 33,000×g to 200,000×g on exosome yield and purity, using 2 unrelated human cell lines, embryonic kidney HEK293 cells and bladder...... of phenol red and cleared by 200,000×g overnight centrifugation. The centrifugation tube fill level impacted the sedimentation efficacy. Comparative analysis by NTA, protein quantification, and detection of exosomal and contamination markers identified differences in vesicle size, concentration...

  2. Central centrifugal cicatricial alopecia. (United States)

    Whiting, David A; Olsen, Elise A


    A progressive scarring alopecia of the central scalp is commonly seen in young to middle-aged females of African descent. It usually starts at the vertex or mid top of the scalp and gradually spreads centrifugally, hence, the unifying term of central centrifugal cicatricial alopecia. The clinical pattern is suggestive of female pattern alopecia, but a lack of follicular pores indicative of scarring is present. It can progress for years before slowly burning out. The etiology is unknown but genetic factors may be important. It is often associated with a history of traumatic hairstyling involving heat, traction, and chemicals. However, most patients of African descent without this disorder have similar styling habits. Nonetheless, avoidance of physical and chemical trauma to the scalp hair, the use of suitable shampoos and conditioners, and the encouragement of natural hairstyles may be helpful. Any infection should be treated. Topical or intralesional corticosteroids and systemic antibiotics may be useful and topical minoxidil should be tried with the hope of preventing further scarring and encouraging regrowth of recovering follicles. Current research into the etiology of this disorder will help to foster much-needed clinical trials of therapeutic agents.

  3. Centrifugal shot blast system

    Energy Technology Data Exchange (ETDEWEB)



    This report describes a demonstration of Concrete cleaning, Inc., modified centrifugal shot blast technology to remove the paint coating from concrete flooring. This demonstration is part of the Chicago Pile-5 (CP-5) Large-Scale Demonstration Project (LSDP) sponsored by the US Department of Energy (DOE), office of Science and Technology (OST), Deactivation and Decommissioning Focus Area (DDFA). The objective of the LSDP is to select and demonstrate potentially beneficial technologies at the Argonne National Laboratory-East (ANL) CP-5 Research Reactor. The purpose of the LSDP is to demonstrate that using innovative and improved decontamination and decommissioning (D and D) technologies from various sources can result in significant benefits, such as decreased cost and increased health and safety, as compared with baseline D and D technologies. Potential markets exist for the innovative centrifugal shot blast system at the following sites: Fernald Environmental Management Project, Los Alamos, Nevada, Oak Ridge Y-12 and K-25, Paducah, Portsmouth Gaseous Diffusion site, and the Savannah River Site. This information is based on a revision to the OST Linkage Tables dated August 4, 1997.

  4. Centrifugal microfluidic platforms: advanced unit operations and applications. (United States)

    Strohmeier, O; Keller, M; Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N


    Centrifugal microfluidics has evolved into a mature technology. Several major diagnostic companies either have products on the market or are currently evaluating centrifugal microfluidics for product development. The fields of application are widespread and include clinical chemistry, immunodiagnostics and protein analysis, cell handling, molecular diagnostics, as well as food, water, and soil analysis. Nevertheless, new fluidic functions and applications that expand the possibilities of centrifugal microfluidics are being introduced at a high pace. In this review, we first present an up-to-date comprehensive overview of centrifugal microfluidic unit operations. Then, we introduce the term "process chain" to review how these unit operations can be combined for the automation of laboratory workflows. Such aggregation of basic functionalities enables efficient fluidic design at a higher level of integration. Furthermore, we analyze how novel, ground-breaking unit operations may foster the integration of more complex applications. Among these are the storage of pneumatic energy to realize complex switching sequences or to pump liquids radially inward, as well as the complete pre-storage and release of reagents. In this context, centrifugal microfluidics provides major advantages over other microfluidic actuation principles: the pulse-free inertial liquid propulsion provided by centrifugal microfluidics allows for closed fluidic systems that are free of any interfaces to external pumps. Processed volumes are easily scalable from nanoliters to milliliters. Volume forces can be adjusted by rotation and thus, even for very small volumes, surface forces may easily be overcome in the centrifugal gravity field which enables the efficient separation of nanoliter volumes from channels, chambers or sensor matrixes as well as the removal of any disturbing bubbles. In summary, centrifugal microfluidics takes advantage of a comprehensive set of fluidic unit operations such as

  5. Centrifugal microfluidics for biomedical applications. (United States)

    Gorkin, Robert; Park, Jiwoon; Siegrist, Jonathan; Amasia, Mary; Lee, Beom Seok; Park, Jong-Myeon; Kim, Jintae; Kim, Hanshin; Madou, Marc; Cho, Yoon-Kyoung


    The centrifugal microfluidic platform has been a focus of academic and industrial research efforts for almost 40 years. Primarily targeting biomedical applications, a range of assays have been adapted on the system; however, the platform has found limited commercial success as a research or clinical tool. Nonetheless, new developments in centrifugal microfluidic technologies have the potential to establish wide-spread utilization of the platform. This paper presents an in-depth review of the centrifugal microfluidic platform, while highlighting recent progress in the field and outlining the potential for future applications. An overview of centrifugal microfluidic technologies is presented, including descriptions of advantages of the platform as a microfluidic handling system and the principles behind centrifugal fluidic manipulation. The paper also discusses a history of significant centrifugal microfluidic platform developments with an explanation of the evolution of the platform as it pertains to academia and industry. Lastly, we review the few centrifugal microfluidic-based sample-to-answer analysis systems shown to date and examine the challenges to be tackled before the centrifugal platform can be more broadly accepted as a new diagnostic platform. In particular, fully integrated, easy to operate, inexpensive and accurate microfluidic tools in the area of in vitro nucleic acid diagnostics are discussed.

  6. Gas centrifuge purge method (United States)

    Theurich, Gordon R.


    1. In a method of separating isotopes in a high speed gas centrifuge wherein a vertically oriented cylindrical rotor bowl is adapted to rotate about its axis within an evacuated chamber, and wherein an annular molecular pump having an intake end and a discharge end encircles the uppermost portion of said rotor bowl, said molecular pump being attached along its periphery in a leak-tight manner to said evacuated chamber, and wherein end cap closure means are affixed to the upper end of said rotor bowl, and a process gas withdrawal and insertion system enters said bowl through said end cap closure means, said evacuated chamber, molecular pump and end cap defining an upper zone at the discharge end of said molecular pump, said evacuated chamber, molecular pump and rotor bowl defining a lower annular zone at the intake end of said molecular pump, a method for removing gases from said upper and lower zones during centrifuge operation with a minimum loss of process gas from said rotor bowl, comprising, in combination: continuously measuring the pressure in said upper zone, pumping gas from said lower zone from the time the pressure in said upper zone equals a first preselected value until the pressure in said upper zone is equal to a second preselected value, said first preselected value being greater than said second preselected value, and continuously pumping gas from said upper zone from the time the pressure in said upper zone equals a third preselected value until the pressure in said upper zone is equal to a fourth preselected value, said third preselected value being greater than said first, second and fourth preselected values.

  7. Stable isotope enrichment using a plasma centrifuge (United States)

    Krishnan, Mahadevan; Bures, Brian; Madden, Robert


    A primary goal of the Department of Energy's Isotope Development and Production for Research and Applications Program (Isotope Program) within the Office of Nuclear Physics (NP) is to produce isotopes that are in short supply in the U.S. and of which there exists no or insufficient domestic commercial production capability. A vacuum arc plasma centrifuge is a rigid rotor column of metal plasma in which centrifugal forces re-distribute ions radially according to their mass/charge ratio. Early work demonstrated rotation at 2 million rpm and separation of various stable isotopes. The spinning plasma column had a Gaussian flux profile, peaked on the rigid rotor axis. This work adopts a more efficient approach, with the plasma created as a hollow column, wherein the flux is concentrated at larger radii where the centrifugal action is highest. By tailoring the vacuum arc discharge geometry, the rotation rate can also be increased to ˜10 million rpm. Data from Cu, Al and other metal plasmas will be presented and discussed in light of enriched stable isotopes needed for research and medicine.

  8. Adiabatic field-free alignment of asymmetric top molecules with an optical centrifuge

    CERN Document Server

    Korobenko, A


    We use an optical centrifuge to align asymmetric top $\\mathrm{SO_2}$ molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment which persists after the molecules are released from the centrifuge. Periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 degrees, permanent field-free alignment offers new ways of controlling molecules with laser light.

  9. Computer precision simulation for titanium casting centrifugal mold filling of prescision titanium castings

    Directory of Open Access Journals (Sweden)

    Daming XU


    Full Text Available Computer simulation codes were developed based on proposed mathematical model for centrifugal mold filling processes and previous computer software for 3D mold filling and solidification of castings. Sample simulations were implemented for mold filling processes of precision titanium castings under gravity and different centrifugal casting techniques. The computation results show that the alloy melt has a much stronger mold filling ability for thin section castings unde a centrifugal force field than that only under the gravity. A "return back" mold filling manner is showed to be a reasonable technique for centrifugal casting processes, especially for thin section prcision castings.

  10. Bioreactor-free tissue engineering: directed tissue assembly by centrifugal casting. (United States)

    Mironov, Vladimir; Kasyanov, Vladimir; Markwald, Roger R; Prestwich, Glenn D


    Casting is a process by which a material is introduced into a mold while it is liquid, allowed to solidify in a predefined shape inside the mold, and then removed to give a fabricated object, part or casing. Centrifugal casting could be defined as a process of molding using centrifugal forces. Although the centrifugal casting technology has a long history in metal manufacturing and in the plastics industry, only recently has this technology attracted the attention of tissue engineers. Initially, centrifugation was used to optimize cell seeding on a solid scaffold. More recently, centrifugal casting has been used to create tubular scaffolds and both tubular and flat multilayered, living tissue constructs. These newer applications were enabled by a new class of biocompatible in situ crosslinkable hydrogels that mimic the extracellular matrix. Herein the authors summarize the state of the art of centrifugal casting technology in tissue engineering, they outline associated technological challenges, and they discuss the potential future for clinical applications.

  11. Sedimentation of a suspension in a centrifugal field. (United States)

    Lueptow, R M; Hübler, W


    To model centrifugal sedimentation of biological suspensions, the time history of sedimentation of particles in a centrifugal field was considered for two geometries: a tube and a cylindrical container. The Kynch theory for batch gravitational settling in Cartesian coordinates based on mass conservation was extended to include a centrifugal sedimentation force, cylindrical coordinates, and the Hawksley-Vand hindered settling model. The resulting quasi-linear partial differential equation was solved by the method of characteristics. The combination of radial dependence of the sedimentation force and cylindrical geometry in the centrifugal case results in several differences in the time-position history diagram of the sedimentation process compared to the gravitational case. First, instead of a region of uniform concentration equal to the initial concentration, a region of concentration that is continuously decreasing with time results. Second, in the region of particle accumulation, curved constant concentration contours result instead of straight lines. Finally, a secondary shock that is dependent upon the initial concentration and the radius ratio of the rotating vessel appears in the centrifugal case. The time history of the concentration for a particle suspension with an initial concentration typical of blood is presented.

  12. Pasteurization of grapefruit juice using a centrifugal ultraviolet light irradiator (United States)

    The pharmaceutical industry uses UV irradiators to inactivate viruses in liquids without heat. The penetration depth of UV in some liquids, such as serum plasma, can be short. To overcome this, very thin films may be produced by centrifugal force, small diameter tubing, or other means. Many liquid f...

  13. Pasteurization of Grapefruit Juice using a Centrifugal Ultraviolet Light Device (United States)

    The pharmaceutical industry uses UV devices to nonthermally inactivate viruses in liquids. To overcome the low penetration depth of UV in some liquids, such as serum plasma, thin films are formed by centrifugal force. Liquid foods also have low UV penetration depths. Studies are lacking on nontherma...

  14. Microwave assisted centrifuge and related methods (United States)

    Meikrantz, David H [Idaho Falls, ID


    Centrifuge samples may be exposed to microwave energy to heat the samples during centrifugation and to promote separation of the different components or constituents of the samples using a centrifuge device configured for generating microwave energy and directing the microwave energy at a sample located in the centrifuge.

  15. Development of a WES Centrifuge, (United States)


    centrifuge chamber during a long centrifuge flight ANS&A have suggested that a more practical and economical alternative would be to provide thermal barriers around...specifications and costs can be prepared, as follows; (10) Constant temperature and temperature gradient control system based on thermal barriers both...CONTROL SYSTEM Design study by ANS&A for constant temperature and temperature gradient control system based on thermal barriers both external to and

  16. Aspiration spiral-flow type centrifugal flotation machine

    Institute of Scientific and Technical Information of China (English)



    Aspiration spiral flow type centrifugal flotation machine takes full advantage of centrifugal force field and gravitational field, and strengthens flotation of coal slurry. As a new-type flotation machine of high efficiency, its key component is bubble generator. Which completes the process of ore pulp inflation and liberalization. The design, parameters and working principle of bubble generator provide the design of the same device in similar equipment with reference. The result of industrial operation shows that this machine is of such features as small occupational area, greater concentration ratio, high processing capacity, high efficiency and lower investment etc.

  17. Hyperbolically Shaped Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Romuald Puzyrewski; Pawel Flaszy(n)ski


    Starting from the classical centrifugal compressor, cone shaped in meridional cross section, two modifications are considered on the basis of results from 2D and 3D flow models. The first modification is the change of the meridional cross section to hyperbolically shaped channel. The second modification, proposed on the basis of 2D axisymmetric solution, concerns the shape of blading. On the strength of this solution the blades are formed as 3D shaped blades, coinciding with the recent tendency in 3D designs. Two aims were considered for the change of meridional compressor shape. The first was to remove the separation zone which appears as the flow tums from axial to radial direction. The second aim is to uniformize the flow at exit of impeller. These two goals were considered within the frame of 2D axisymmetric model. Replacing the cone shaped compressor by a hyperbolically shaped one, the separation at the corner was removed. The disc and shroud shape of the compressor was chosen in the way which satisfies the condition of most uniform flow at the compressor exit. The uniformity of exit flow from the rotor can be considered as the factor which influences the performance of the diffuser following the rotor. In the 2D model a family of stream surfaces of S1 type is given in order to find S2 surfaces which may be identified with the midblade surfaces of compressor blading. A computation of 3D type has been performed in order to establish the relations between 2D and 3D models in the calculation of flow parameters. In the presented example the 2D model appears as the inverse model which leads to 3D shape of blading whereas the 3D model has been used for the direct solution. In the presented example the confrontation of two models, 2D and 3D, leads to a better understanding of the application of these models to the design procedure.

  18. Centrifugation. A theoretical study of oxygen enrichment by centrifugation

    Energy Technology Data Exchange (ETDEWEB)

    Kierkegaard, P.; Raetz, E.


    In the present paper we first investigate what happens if we fill a cylinder with air, close it and rotate it. The results show that no matter which peripheral speed is used, it is not possible by means of the radial separation effect alone, to enrich the oxygen concentration from the previous 21% to more then 23.3%, which is of no practical value. In case of a too low enrichment in one centrifuge, the wanted material from this centrifuge can be used as an input for a second centrifuge and so on, in this way forming a cascade of centrifuges. Oxygen will be enriched in each step, until the desired concentration is reached. Cascading was the technology in the very beginning by enrichment plants for uraniumhexaflouride, used for atomic weapons and nuclear power plants. In this study we try to avoid cascading by aiming for higher separation factors. Therefore, we next investigate the possibilities of using a countercurrent centrifuge where in principle the enriched gas is subjected to several centrifugation in the same centrifuge. The calculations show, that in this way it is possible to produce nearly a 100% pure oxygen (polluted with some heavier molecules like argon) in one machine. Our third step was to calculate the amount of oxygen produced per hour. Using a countercurrent centrifuge of the Zippe type, 100 cm high and 20 cm in diameter, it is or will be possible in the near future to produce 17 g enriched air per hour enriched to 50% oxygen. That corresponds to processing 1 m{sup 3} atmospherical air in the period of approximately 24 hours. This is not very impressive. Our fourth step was to estimate the amount of power used for producing this amount of oxygen. A rough, but complicated, estimate shows that the power consumption at the production level will be about the double of the consumption used today. The overall conclusion is, that centrifugation as a production method for oxygen (or nitrogen) will not be competitive with the currently used method in the

  19. 离心作用下人牙周膜细胞内诱导型一氧化氮合酶和胱硫醚分解酶的表达%Expression of inducible nitric oxide synthase and cystathionine-γ-lyase in cultured human periodontal ligament cells following centrifugal force stimulation

    Institute of Scientific and Technical Information of China (English)

    廖崇珊; 华咏梅; 冯欣华


    目的 研究在离心力作用下人牙周膜细胞内的诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)和硫化氢合酶胱硫醚分解酶(cystat hionine-γ-lyase,CSE)的表达变化.方法 采用组织块-酶消化联合法培养人牙周膜细胞,对细胞施加离心力(167 g),SABC法染色及胞浆透光度检测iNOS和CSE在10、30、60、90、120和240 min不同加力时间点的表达变化.结果 正常人牙周膜细胞内几乎无iNOS和CSE表达;加力10 min,iNOS和CSE有表达(P<0.01);之后两种酶表达逐渐加强,加力60 min,iNOS和CSE表达达到高峰(P<0.01);之后逐渐减弱,加力240min,iNOS和CSE恢复到基础水平.结论 离心力可诱导人牙周膜细胞内iNOS和CSE的表达短暂性升高,提示一氧化氮(N())和硫化氢(H2S)可能参与了牙周组织改建中的力学信号转导过程.%Objective This study was to examine the changes of inducible nitric oxide synthase (iNOS) and hydrogen sulfide (H2S) synthase,cystathionine-γ-lyase (CSE) in cultured Human periodontal ligament fibrohlasts (HPDLFs)in response to centrifugal force stimulation. Methods Cultured HPDLFs with the method of tissue-enzymatic digestion were stimulated mechanically by centrifugal force (167 g) for 10,30,60,90,120 and 240 min,respectively.The expression of iNOSand CSE were analyzed by Streptavidin-biotin complex (SABC) immunocytochemistry combined with cytoplasmic light transmission measurement.Results The basal levels of iNOS and CSE in the HPDLFs were very low.Application of centrifugal force for 10 min resulted in a rapid increase in the iNOS and CSE expression (P<0.01).The expression levels gradually increased to a peak 60 min after applying force (P<0.01),then declined to the basal level at 240 min of sustained force.Conclusions Centrifugal force induced the expression of HPDLFs iNOS and CSE in the same pattern within a narrow time frame,suggesting iNOS and CSE may play an essential role in periodontium remodeling.

  20. Centrifuge-Based Fluidic Platforms (United States)

    Zoval, Jim; Jia, Guangyao; Kido, Horacio; Kim, Jitae; Kim, Nahui; Madou, Marc

    In this chapter centrifuge-based microfluidic platforms are reviewed and compared with other popular microfluidic propulsion methods. The underlying physical principles of centrifugal pumping in microfluidic systems are presented and the various centrifuge fluidic functions such as valving, decanting, calibration, mixing, metering, heating, sample splitting, and separation are introduced. Those fluidic functions have been combined with analytical measurements techniques such as optical imaging, absorbance and fluorescence spectroscopy and mass spectrometry to make the centrifugal platform a powerful solution for medical and clinical diagnostics and high-throughput screening (HTS) in drug discovery. Applications of a compact disc (CD)-based centrifuge platform analyzed in this review include: two-point calibration of an optode-based ion sensor, an automated immunoassay platform, multiple parallel screening assays and cellular-based assays. The use of modified commercial CD drives for high-resolution optical imaging is discussed as well. From a broader perspective, we compare the technical barriers involved in applying microfluidics for sensing and diagnostic as opposed to applying such techniques to HTS. The latter poses less challenges and explains why HTS products based on a CD fluidic platform are already commercially available, while we might have to wait longer to see commercial CD-based diagnostics.

  1. Analysis of cantilever NEMS in centrifugal-fluidic systems (United States)

    Mohsen-Nia, Mohsen; Abadian, Fateme; Abadian, Naeime; Dehkordi, Keivan Mosaiebi; Keivani, Maryam; Abadyan, Mohamadreza


    Electromechanical nanocantilevers are promising for using as sensors/detectors in centrifugal-fluidic systems. For this application, the presence of angular speed and electrolyte environment should be considered in the theoretical analysis. Herein, the pull-in instability of the nanocantilever incorporating the effects of angular velocity and liquid media is investigated using a size-dependent continuum theory. Using d’Alembert principle, the angular speed is transformed into an equivalent centrifugal force. The electrochemical and dispersion forces are incorporated considering the corrections due to the presence of electrolyte media. Two different approaches, i.e., the Rayleigh-Ritz method (RRM) and proposing a lumped parameter model (LPM), were applied to analyze the system. The models are validated with the results presented in literature. Impacts of the angular velocity, electrolyte media, dispersion forces, and size effect on the instability characteristics of the nanocantilever are discussed.

  2. The Effect of Moment of Inertia on the Liquids in Centrifugal Microfluidics

    Directory of Open Access Journals (Sweden)

    Esmail Pishbin


    Full Text Available The flow of liquids in centrifugal microfluidics is unidirectional and dominated by centrifugal and Coriolis forces (i.e., effective only at T-junctions. Developing mechanisms and discovering efficient techniques to propel liquids in any direction other than the direction of the centrifugal force has been the subject of a large number of studies. The capillary force attained by specific surface treatments, pneumatic energy, active and passive flow reciprocation and Euler force have been previously introduced in order to manipulate the liquid flow and push it against the centrifugal force. Here, as a new method, the moment of inertia of the liquid inside a chamber in a centrifugal microfluidic platform is employed to manipulate the flow and propel the liquid passively towards the disc center. Furthermore, the effect of the moment of inertia on the liquid in a rectangular chamber is evaluated, both in theory and experiments, and the optimum geometry is defined. As an application of the introduced method, the moment of inertia of the liquid is used in order to mix two different dyed deionized (DI waters; the mixing efficiency is evaluated and compared to similar mixing techniques. The results show the potential of the presented method for pumping liquids radially inward with relatively high flow rates (up to 23 mm3/s and also efficient mixing in centrifugal microfluidic platforms.

  3. Effect of gelatin on the water dispersion and centrifugal purification of single-walled carbon nanotubes (United States)

    Hanium Maria, Kazi; Mieno, Tetsu


    We report a convenient and effective procedure for the water dispersion and purification of single-walled carbon nanotubes (SWNTs). The purification procedure involves a combination of dispersion and centrifugation, in which gelatin; an environmentally friendly material is used as a dispersing agent. It has been found that an aqueous solution of gelatin effectively disperses SWNTs for more than a month. Another advantage of using gelatin as a dispersing agent is that it can be easily removed by washing with water and filtration. The centrifugation procedure employs a centrifugal force of about 2500 times the gravitational force to separate the particles. Although carbonaceous and metallic impurities usually have higher density than SWNTs in arc-produced carbon soot, the centrifugation can easily remove impurities leaving undamaged SWNTs in solution when appropriate centrifugal force and a centrifugation time are used. Centrifugation is carried out for three times to sufficiently remove impurities. Finally, the SWNTs are separated from the gelatin by heating in water and filtering.


    Smith, W.Q.


    An apparatus is presented for remotely determining the alignment of a centrifuge. The centrifage shaft is provided with a shoulder, upon which two followers ride, one for detecting radial movements, and one upon the shoulder face for determining the axial motion. The followers are attached to separate liquid filled bellows, and a tube connects each bellows to its respective indicating gage at a remote location. Vibrations produced by misalignment of the centrifuge shaft are transmitted to the bellows, and tbence through the tubing to the indicator gage. This apparatus is particularly useful for operation in a hot cell where the materials handled are dangerous to the operating personnel.

  5. Generalized anti-centrifugal potential

    Energy Technology Data Exchange (ETDEWEB)

    Dandoloff, Rossen [Laboratoire de Physique Theorique et Modelisation, Universite de Cergy-Pontoise, F-95302 Cergy-Pontoise (France); Jensen, Bjørn [Department of Micro and Nano Systems Technology, Vestfold University College, N-3103 Tønsberg (Norway); Saxena, Avadh, E-mail: [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)


    We generalize the quantum anti-centrifugal potential in the two-dimensional Euclidean plane to two-dimensional surfaces embedded in three-dimensional Euclidean space. We consider the sphere with two caps removed in some detail. We show that quantum particles in this space are “pushed” towards either of the cap boundaries. We also consider the two-dimensional Euclidean plane with an elliptic area removed and compute the quantum anti-centrifugal potential on the elliptic boundary. It is argued that a sufficiently thin electrically conducting nano-wire shaped as an ellipse will exhibit an inhomogeneous charge distribution due to this quantum potential.

  6. Latex micro-balloon pumping in centrifugal microfluidic platforms. (United States)

    Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Al-Faqheri, Wisam; Thio, Tzer Hwai Gilbert; Kazemzadeh, Amin; Madou, Marc


    Centrifugal microfluidic platforms have emerged as point-of-care diagnostic tools. However, the unidirectional nature of the centrifugal force limits the available space for multi-step processes on a single microfluidic disc. To overcome this limitation, a passive pneumatic pumping method actuated at high rotational speeds has been previously proposed to pump liquid against the centrifugal force. In this paper, a novel micro-balloon pumping method that relies on elastic energy stored in a latex membrane is introduced. It operates at low rotational speeds and pumps a larger volume of liquid towards the centre of the disc. Two different micro-balloon pumping mechanisms have been designed to study the pump performance at a range of rotational frequencies from 0 to 1500 rpm. The behaviour of the micro-balloon pump on the centrifugal microfluidic platforms has been theoretically analysed and compared with the experimental data. The experimental data show that the developed pumping method dramatically decreases the required rotational speed to pump liquid compared to the previously developed pneumatic pumping methods. It also shows that within a range of rotational speed, a desirable volume of liquid can be stored and pumped by adjusting the size of the micro-balloon.

  7. Comparative analysis of discrete exosome fractions obtained by differential centrifugation

    Directory of Open Access Journals (Sweden)

    Dennis K. Jeppesen


    Full Text Available Background: Cells release a mixture of extracellular vesicles, amongst these exosomes, that differ in size, density and composition. The standard isolation method for exosomes is centrifugation of fluid samples, typically at 100,000×g or above. Knowledge of the effect of discrete ultracentrifugation speeds on the purification from different cell types, however, is limited. Methods: We examined the effect of applying differential centrifugation g-forces ranging from 33,000×g to 200,000×g on exosome yield and purity, using 2 unrelated human cell lines, embryonic kidney HEK293 cells and bladder carcinoma FL3 cells. The fractions were evaluated by nanoparticle tracking analysis (NTA, total protein quantification and immunoblotting for CD81, TSG101, syntenin, VDAC1 and calreticulin. Results: NTA revealed the lowest background particle count in Dulbecco's Modified Eagle's Medium media devoid of phenol red and cleared by 200,000×g overnight centrifugation. The centrifugation tube fill level impacted the sedimentation efficacy. Comparative analysis by NTA, protein quantification, and detection of exosomal and contamination markers identified differences in vesicle size, concentration and composition of the obtained fractions. In addition, HEK293 and FL3 vesicles displayed marked differences in sedimentation characteristics. Exosomes were pelleted already at 33,000×g, a g-force which also removed most contaminating microsomes. Optimal vesicle-to-protein yield was obtained at 67,000×g for HEK293 cells but 100,000×g for FL3 cells. Relative expression of exosomal markers (TSG101, CD81, syntenin suggested presence of exosome subpopulations with variable sedimentation characteristics. Conclusions: Specific g-force/k factor usage during differential centrifugation greatly influences the purity and yield of exosomes. The vesicle sedimentation profile differed between the 2 cell lines.

  8. Theory and experiments on centrifuge cratering (United States)

    Schmidt, R. M.; Holsapple, K. A.


    Centrifuge experimental techniques provide possibilities for laboratory simulation of ground motion and cratering effects due to explosive loadings. The results of a similarity analysis for the thermomechanical response of a continuum show that increased gravity is a necessary condition for subscale testing when identical materials for both model and prototype are being used. The general similarity requirements for this type of subscale testing are examined both theoretically and experimentally. The similarity analysis is used to derive the necessary and sufficient requirements due to the general balance and jump equations and gives relations among all the scale factors for size, density, stress, body forces, internal energy, heat supply, heat conduction, heat of detonation, and time. Additional constraints due to specific choices of material constitutive equations are evaluated separately. The class of constitutive equations that add no further requirements is identified. For this class of materials, direct simulation of large-scale cratering events at small scale on the centrifuge is possible and independent of the actual constitutive equations. For a rate-independent soil it is shown that a small experiment at gravity g and energy E is similar to a large event at 1 G but with energy equal to g3E. Consequently, experiments at 500 G with 8 grams of explosives can be used to simulate a kiloton in the field. A series of centrifuge experiments was performed to validate the derived similarity requirements and to determine the practicality of applying the technique to dry granular soils having little or no cohesion. Ten shots using Ottawa sand at various gravities confirmed reproducibility of results in the centrifuge environment, provided information on particle size effects, and demonstrated the applicability of the derived similitude requirements. These experiments used 0.5-4 grams of pentaerythritol-tetranitrate (PETN) and 1.7 grams of lead-azide explosives. They

  9. Mechanically driven centrifugal pyrolyzer (United States)

    Linck, Martin Brendan; Bush, Phillip Vann


    An apparatus for fast pyrolysis of biomass and other solid organic materials including a vertically oriented cylindrical vessel having a solids outlet proximate the bottom thereof, a vapor outlet, a top wall forming at least one opening, and an adjacent heated side wall. Disposed within the cylindrical vessel and extending through the at least one opening in the top wall is a rotor having a rotatable shaft coincident with the longitudinal axis of the cylindrical vessel to which is attached at least one substantially vertically oriented blade having one edge connected directly or indirectly with the rotatable shaft and having an opposite edge spaced apart from the heated side wall, whereby a non-radial, preferably tangential, force is imparted on the feedstock in the cylindrical vessel. Also disclosed is a method for fast pyrolysis of biomass and other solid organic materials.

  10. Theory of batchwise centrifugal casting

    NARCIS (Netherlands)

    Biesheuvel, P. Maarten; Nijmeijer, Arian; Verweij, Henk


    In batchwise centrifugal casting a cylindrical mold is filled with suspension and rotated rapidly around its axis. This results in the movement of the particulate phase toward the cylinder wall and the formation of a tubular cast. Theory is presented for particle transport in the suspension phase an


    Directory of Open Access Journals (Sweden)

    V. Ju. Stetsenko


    Full Text Available It is shown that the way of centrifugal casting into water-cooled mould with vertical rotation axis enables to receive hollow slugs with diameter 100–250 mm, with height under 200 mm with wall thickness under 15 mm of antifriction silumin АК15М3, which will replace expensive antifriction bronze.

  12. Design of a centrifugal blood pump: Heart Turcica Centrifugal. (United States)

    Demir, Onur; Biyikli, Emre; Lazoglu, Ismail; Kucukaksu, Suha


    A prototype of a new implantable centrifugal blood pump system named Heart Turcica Centrifugal (HTC) was developed as a left ventricular assist device (LVAD) for the treatment of end-stage cardiac failure. In the development of HTC, effects of blade height and volute tongue profiles on the hydraulic and hemolytic performances of the pump were investigated. As a result, the prototype was manufactured using the best blade height and volute tongue profiles. Performance of the prototype model was experimentally evaluated in a closed-loop flow system using water as the medium. The hydraulic performance requirement of an LVAD (5 L/min flow rate against a pressure difference of 100 mm Hg) was attained at 2800 rpm rotational speed.

  13. Fabrication of silk fibroin film using centrifugal casting technique for corneal tissue engineering. (United States)

    Lee, Min Chae; Kim, Dong-Kyu; Lee, Ok Joo; Kim, Jung-Ho; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Kim, Su Hyeon; Park, Chan Hum


    Films prepared from silk fibroin have shown potential as biomaterials in tissue engineering applications for the eye. Here, we present a novel process for fabrication of silk fibroin films for corneal application. In this work, fabrication of silk fibroin films was simply achieved by centrifugal force. In contrast to the conventional dry casting method, we carried out the new process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force was imposed on an aluminum tube containing silk fibroin solution. In the present study, we also compared the surface roughness, mechanical properties, transparency, and cell proliferation between centrifugal and dry casting method. In terms of surface morphology, films fabricated by the centrifugal casting have less surface roughness than those by the dry casting. For elasticity and transparency, silk fibroin films obtained from the centrifugal casting had favorable results compared with those prepared by dry casting. Furthermore, primary human corneal keratocytes grew better in films prepared by the centrifugal casting. Therefore, our results suggest that this new fabrication process for silk fibroin films offers important potential benefits for corneal tissue regeneration.

  14. Centrifugal Blower for Personal Air Ventilation System (PAVS) - Phase 1 (United States)



  15. Centrifugal separator devices, systems and related methods (United States)

    Meikrantz, David H.; Law, Jack D.; Garn, Troy G.; Todd, Terry A.; Macaluso, Lawrence L.


    Centrifugal separator devices, systems and related methods are described. More particularly, fluid transfer connections for a centrifugal separator system having support assemblies with a movable member coupled to a connection tube and coupled to a fixed member, such that the movable member is constrained to movement along a fixed path relative to the fixed member are described. Also, centrifugal separator systems including such fluid transfer connections are described. Additionally, methods of installing, removing and/or replacing centrifugal separators from centrifugal separator systems are described.

  16. Centrifugal pumps and allied machinery

    CERN Document Server

    Anderson, HH


    This book will be of vital interest to all engineers and designers concerned with centrifugal pumps and turbines. Including statistical information derived from 20000 pumps and 700 turbines with capacities of 5gpm to 5000000gpm, this book offers the widest range and scope of information currently available. Statistical analyses suggest practical methods of increasing pump performance and provide valuable data for new design aspects.

  17. A Forced Jet System for the Cooling of Cutting Tools. (United States)

    Cutting tools , *Coolant pumps, *Machine tools, *Metals, Machine shop practice, High pressure, Force(Mechanics), Centrifugal pumps, Mist, Jet streams, Lubricants, Machining, Friction, Surface finishing, Safety

  18. Modeling on Fluid Flow and Inclusion Motion in Centrifugal Continuous Casting Strands (United States)

    Wang, Qiangqiang; Zhang, Lifeng; Sridhar, Seetharaman


    During the centrifugal continuous casting process, unreasonable casting parameters can cause violent level fluctuation, serious gas entrainment, and formation of frozen shell pieces at the meniscus. Thus, in the current study, a three-dimensional multiphase turbulent model was established to study the transport phenomena during centrifugal continuous casting process. The effects of nozzle position, casting and rotational speed on the flow pattern, centrifugal force acting on the molten steel, level fluctuation, gas entrainment, shear stress on mold wall, and motion of inclusions during centrifugal continuous casting process were investigated. Volume of Fluid model was used to simulate the molten steel-air two-phase. The level fluctuation and the gas entrainment during casting were calculated by user-developed subroutines. The trajectory of inclusions in the rotating system was calculated using the Lagrangian approach. The results show that during centrifugal continuous casting, a large amount of gas was entrained into the molten steel, and broken into bubbles of various sizes. The greater the distance to the mold wall, the smaller the centrifugal force. Rotation speed had the most important influence on the centrifugal force distribution at the side region. Angular moving angle of the nozzle with 8° and keeping the rotation speed with 60 revolutions per minute can somehow stabilize the level fluctuation. The increase of angular angle of nozzle from 8 to 18 deg and rotation speed from 40 to 80 revolutions per minute favored to decrease the total volume of entrained bubbles, while the increase of distance of nozzle moving left and casting speed had reverse effects. The trajectories of inclusions in the mold were irregular, and then rotated along the strand length. After penetrating a certain distance, the inclusions gradually moved to the center of billet and gathered there. More work, such as the heat transfer, the solidification, and the inclusions entrapment

  19. Centrifugal Infiltration of Porous Ceramic Preforms by the Liquid Al Alloy – Theoretical Background and Experimental Verification

    Directory of Open Access Journals (Sweden)

    Dolata A.J.


    Full Text Available The goal of this work is the description of phenomena occurring during centrifugal infiltration of porous ceramic materials by liquid Al alloy. In this method, the pressure required to infiltration of liquid metal into pores of ceramic is generated by centrifugal force. From the beginning it was assumed that the porous ceramic material will create reinforcement layer in specific area of the casting. The forces that influence on the liquid metal during mould centrifugation and heat exchange between ceramic preform and metal alloy within the area of the front of infiltration were considered in the analysis. The paper presents also selected experiment results.

  20. Centrifuge facilities at Technical University of Denmark

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane; Krogsbøll, Anette Susanne; Hededal, Ole


    The geotechnical group at the Danish Technical University (DTU) operates a geotechnical beam centrifuge. The centrifuge was build in 1976 and has been upgraded through the years, latest with onboard data and control systems. The centrifuge concept involves an increased gravity field in which...... the physical model is placed and tested. The capabilities of the centrifuge at DTU makes it possible to obtain a scale factor of 75-85 in the tests which equals a soil volume in prototype scale of ø40m and a depth of 36 m. The centrifuge facilities at DTU have through the years been used for testing various...... geotechnical issues, such as suction anchors, tension piles in clay, active earth pressures on sheet piles and group effects for lateral loaded piles. The paper describes physical modelling in general, the centrifuge, present setups and shows samples of obtained results....

  1. Empirical Design Considerations for Industrial Centrifugal Compressors

    Directory of Open Access Journals (Sweden)

    Cheng Xu


    Full Text Available Computational Fluid Dynamics (CFD has been extensively used in centrifugal compressor design. CFD provides further optimisation opportunities for the compressor design rather than designing the centrifugal compressor. The experience-based design process still plays an important role for new compressor developments. The wide variety of design subjects represents a very complex design world for centrifugal compressor designers. Therefore, some basic information for centrifugal design is still very important. The impeller is the key part of the centrifugal stage. Designing a highly efficiency impeller with a wide operation range can ensure overall stage design success. This paper provides some empirical information for designing industrial centrifugal compressors with a focus on the impeller. A ported shroud compressor basic design guideline is also discussed for improving the compressor range.

  2. Isolation of exosomes by differential centrifugation: Theoretical analysis of a commonly used protocol (United States)

    Livshts, Mikhail A.; Khomyakova, Elena; Evtushenko, Evgeniy G.; Lazarev, Vassili N.; Kulemin, Nikolay A.; Semina, Svetlana E.; Generozov, Edward V.; Govorun, Vadim M.


    Exosomes, small (40-100 nm) extracellular membranous vesicles, attract enormous research interest because they are carriers of disease markers and a prospective delivery system for therapeutic agents. Differential centrifugation, the prevalent method of exosome isolation, frequently produces dissimilar and improper results because of the faulty practice of using a common centrifugation protocol with different rotors. Moreover, as recommended by suppliers, adjusting the centrifugation duration according to rotor K-factors does not work for “fixed-angle” rotors. For both types of rotors - “swinging bucket” and “fixed-angle” - we express the theoretically expected proportion of pelleted vesicles of a given size and the “cut-off” size of completely sedimented vesicles as dependent on the centrifugation force and duration and the sedimentation path-lengths. The proper centrifugation conditions can be selected using relatively simple theoretical estimates of the “cut-off” sizes of vesicles. Experimental verification on exosomes isolated from HT29 cell culture supernatant confirmed the main theoretical statements. Measured by the nanoparticle tracking analysis (NTA) technique, the concentration and size distribution of the vesicles after centrifugation agree with those theoretically expected. To simplify this “cut-off”-size-based adjustment of centrifugation protocol for any rotor, we developed a web-calculator.

  3. Concept designs of nonrotating-type centrifugal blood pump and basic study on output characteristics of the oscillating disk-type centrifugal pump. (United States)

    Kabei, N; Tuichiya, K; Sakurai, Y


    When designing a turbo-type blood pump as an artificial heart, the gap between a rotating shaft and a pump housing should be perfectly sealed to prevent any leakage or contamination through a seal. In addition, blood coagulation in a blood chamber must be avoided. To overcome these problems, we proposed five different nonrotating-type turbo pumps: a caudal-fin-type axial-flow pump, a caudal-fin-type centrifugal pump, a nutating-column-type centrifugal pump, a nutating-collapsible-tube-type centrifugal pump, and an oscillating-disk-type centrifugal pump. We selected and developed the oscillating-disk-type centrifugal pump that consists of a disk, a driving rod, a seal, an oscillation mechanism, and a pump housing. The disk is mounted on the end of the rod, which is connected to a high-speed DC motor through an oscillation mechanism. The rod and the disk do not rotate, but they oscillate in the pump housing. This movement of the disk generates forward fluid flow around the axis (i.e., the rotational fluid flow). Centrifugal force due to fluid rotation supports the pressure difference between the outlet and the inlet. The diameter of the disk is 39 mm, the maximum inner diameter of the pump housing is 40 mm, and the volume of the blood chamber for 25 degrees' oscillation is 16.9 ml. The performance of the pump was tested in a mock circulatory system.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Centrifugal quantum states of neutrons (United States)

    Nesvizhevsky, V. V.; Petukhov, A. K.; Protasov, K. V.; Voronin, A. Yu.


    We propose a method for observation of the quasistationary states of neutrons localized near a curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror Fermi potential. This phenomenon is an example of an exactly solvable “quantum bouncer” problem that can be studied experimentally. It could provide a promising tool for studying fundamental neutron-matter interactions, as well as quantum neutron optics and surface physics effects. We develop a formalism that describes quantitatively the neutron motion near the mirror surface. The effects of mirror roughness are taken into account.

  5. Cavitation Effects in Centrifugal Pumps- A Review

    Directory of Open Access Journals (Sweden)

    Maxime Binama


    Full Text Available Cavitation is one of the most challenging fluid flow abnormalities leading to detrimental effects on both the centrifugal pump flow behaviors and physical characteristics. Centrifugal pumps’ most low pressure zones are the first cavitation victims, where cavitation manifests itself in form of pitting on the pump internal solid walls, accompanied by noise and vibration, all leading to the pump hydraulic performance degradation. In the present article, a general description of centrifugal pump performance and related parameters is presented. Based on the literature survey, some light were shed on fundamental cavitation features; where different aspects relating to cavitation in centrifugal pumps were briefly discussed

  6. Centrifugal separators and related devices and methods (United States)

    Meikrantz, David H.; Law, Jack D.; Garn, Troy G.; Macaluso, Lawrence L.; Todd, Terry A.


    Centrifugal separators and related methods and devices are described. More particularly, centrifugal separators comprising a first fluid supply fitting configured to deliver fluid into a longitudinal fluid passage of a rotor shaft and a second fluid supply fitting sized and configured to sealingly couple with the first fluid supply fitting are described. Also, centrifugal separator systems comprising a manifold having a drain fitting and a cleaning fluid supply fitting are described, wherein the manifold is coupled to a movable member of a support assembly. Additionally, methods of cleaning centrifugal separators are described.

  7. Virgin Coconut Oil Production by Centrifugation Method



    The virgin coconut oil (VCO) production by centrifugation method was studied. The production of VCO was studied by using various centrifugation speed, temperature and time intervals. The results showed that the yield of VCO was 13.53% at 12000rpm, at 120 minutes. The highest yield of VCO was 13.80% at centrifugation temperature of 40oC. The concentration of lauric acid present in the samples with variables of centrifugation temperatures, speed, and time intervals were 0.4543µg, 6.2367µg, and ...

  8. Virgin Coconut Oil Production by Centrifugation Method

    Directory of Open Access Journals (Sweden)



    Full Text Available The virgin coconut oil (VCO production by centrifugation method was studied. The production of VCO was studied by using various centrifugation speed, temperature and time intervals. The results showed that the yield of VCO was 13.53% at 12000rpm, at 120 minutes. The highest yield of VCO was 13.80% at centrifugation temperature of 40oC. The concentration of lauric acid present in the samples with variables of centrifugation temperatures, speed, and time intervals were 0.4543µg, 6.2367µg, and 6.4894µg respectively.

  9. Active pneumatic control of centrifugal microfluidic flows for lab-on-a-chip applications. (United States)

    Clime, Liviu; Brassard, Daniel; Geissler, Matthias; Veres, Teodor


    This paper reports a novel method of controlling liquid motion on a centrifugal microfluidic platform based on the integration of a regulated pressure pump and a programmable electromechanical valving system. We demonstrate accurate control over the displacement of liquids within the system by pressurizing simultaneously multiple ports of the microfluidic device while the platform is rotating at high speed. Compared to classical centrifugal microfluidic platforms where liquids are solely driven by centrifugal and capillary forces, the method presented herein adds a new degree of freedom for fluidic manipulation, which represents a paradigm change in centrifugal microfluidics. We first demonstrate how various core microfluidic functions such as valving, switching, and reverse pumping (i.e., against the centrifugal field) can be easily achieved by programming the pressures applied at dedicated access ports of the microfluidic device. We then show, for the first time, that the combination of centrifugal force and active pneumatic pumping offers the possibility of mixing fluids rapidly (~0.1 s) and efficiently based on the creation of air bubbles at the bottom of a microfluidic reservoir. Finally, the suitability of the developed platform for performing complex bioanalytical assays in an automated fashion is demonstrated in a DNA harvesting experiment where recovery rates of about 70% were systematically achieved. The proposed concept offers the interesting prospect to decouple basic microfluidic functions from specific material properties, channel dimensions and fabrication tolerances, surface treatments, or on-chip active components, thus promoting integration of complex assays on simple and low-cost microfluidic cartridges.

  10. Effect of Mould Wall Thickness on Rate of Solidification of Centrifugal Casting

    Directory of Open Access Journals (Sweden)



    Full Text Available In Centrifugal Casting process the centrifugal force presses the metal against the inner wall of the metal mould, resulting in rapid solidification of the molten metal. However the solidification structures like structural uniformity and structural character of the solidified metal of centrifugal casting is of great importance, regarding to its mechanical properties. The solidification time of the casting is dependent upon the various parameters like speed ofrotation of the mold, mould wall temperature, heat transfer coefficient at the metal-mold interface, mould wall thickness, material of the mould and so on. In this paper experimental study of effect of mould wall thickness on solidification of the centrifugal casting has been discussed. As the mould wall thickness increases, due to the chilling effect, the solidification time decreases. Fine grains are observed in castings produced in thick walled mould and coarse grains are observed in thin walled moulds. Brinel Hardness of the casting was measured.


    Institute of Scientific and Technical Information of China (English)

    LI Zhi-bin; WANG Zhao-lin; WANG Tian-shu; LIU Ning


    The influences of nonlinear centrifugal force to large overall attitude motion of coupled rigid-flexible system was investigated. First the nonlinear model of the coupled rigidflexible system was deduced from the idea of "cenlrifugal potential field", and then the dynamic effects of the nonlinear centrifugal force to system attitude motion were analyzed by approximate calculation; At last, the Lyapunov function based on energy norm was selected,in the condition that only the measured values of attitude and attitude speed are available,and it is proved that the PD feedback control law can ensure the attitude stability during large angle maneuver.

  12. Centrifuge modelling of offshore monopile foundation

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Hededal, Ole


    centrifuge tests on a laterally loaded monopile in dry sand. The prototype dimension of the piles was modelled to a diameter of 1 meter and penetration depth on 6 meter. The test series were designed in order to investigate the scaling laws in the centrifuge both for monotonic and cyclic loading...

  13. Centrifugal innervation of the mammalian olfactory bulb. (United States)

    Matsutani, Shinji; Yamamoto, Noboru


    Although it has been known for decades that the mammalian olfactory bulb receives a substantial number of centrifugal inputs from other regions of the brain, relatively few data have been available on the function of the centrifugal olfactory system. Knowing the role of the centrifugal projection and how it works is of critical importance to fully understanding olfaction. The centrifugal fibers can be classified into two groups, a group that release neuromodulators, such as noradrenaline, serotonin, or acetylcholine, and a group originating in the olfactory cortex. Accumulating evidence suggests that centrifugal neuromodulatory inputs are associated with acquisition of odor memory. Because the distribution of the terminals on these fibers is diffuse and widespread, the neuromodulatory inputs must affect diverse subsets of bulbar neurons at the same time. In contrast, knowledge of the role of centrifugal fibers from the olfactory cortical areas is limited. Judging from recent morphological evidence, these fibers may modify the activity of neurons located in sparse and discrete loci in the olfactory bulb. Given the modular organization of the olfactory bulb, centrifugal fibers from the olfactory cortex may help coordinate the activities of restricted subsets of neurons belonging to distinct functional modules in an odor-specific manner. Because the olfactory cortex receives inputs from limbic and neocortical areas in addition to inputs from the bulb, the centrifugal inputs from the cortex can modulate odor processing in the bulb in response to non-olfactory as well as olfactory cues.

  14. Rotor for a pyrolysis centrifuge reactor

    DEFF Research Database (Denmark)


    The present invention relates to a rotor for a pyrolysis centrifuge reactor, said rotor comprising a rotor body having a longitudinal centre axis, and at least one pivotally mounted blade being adapted to pivot around a pivot axis under rotation of the rotor body around the longitudinal centre axis....... Moreover, the present invention relates to a pyrolysis centrifuge reactor applying such a rotor....

  15. Determination of the Heat Transfer Coefficient at the Metal-Mold Interface During Centrifugal Casting (United States)

    Vacca, Santiago; Martorano, Marcelo A.; Heringer, Romulo; Boccalini, Mário


    The heat transfer coefficient at the metal-mold interface ( h MM) has been determined for the first time during the centrifugal casting of a Fe-C alloy tube using the inverse solution method. To apply this method, a centrifugal casting experiment was carried out to measure cooling curves within the tube wall under a mold rotation speed of 900 rpm, imposing a centrifugal force 106 times as large as the gravity force (106 G). As part of the solution method, a comprehensive heat transfer model of the centrifugal casting was also developed and coupled to an optimization algorithm. Finally, the evolution of h MM with time that gives the minimum squared error between measured and calculated cooling curves was obtained. The determined h MM is approximately 870 W m-2 K-1 immediately after melt pouring, decreasing to about 50 W m-2 K-1 when the average temperature of the tube is ~973 K (700 °C), after the end of solidification. Despite the existence of a centrifugal force that could enhance the metal-mold contact, these values are lower than those generally reported for static molds with or without an insulating coating at the mold inner surface. The implemented model shows that the heat loss by radiation is dominant over that by convection at the tube inner surface, causing the formation of a solidification front that meets another front coming from the outer surface of the tube.

  16. Centrifugal membrane filtration -- Task 9

    Energy Technology Data Exchange (ETDEWEB)



    The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., the developer of a centrifugal membrane filtration technology, to demonstrate applications for the SpinTek technology within the US Department of Energy (DOE) Environmental management (EM) Program. The technology uses supported microporous membranes rotating at high rpm, under pressure, to separate suspended and colloidal solids from liquid streams, yielding a solids-free permeate stream and a highly concentrated solids stream. This is a crosscutting technology that falls under the Efficient Separations and Processing Crosscutting Program, with potential application to tank wastes, contaminated groundwater, landfill leachate, and secondary liquid waste streams from other remediation processes, including decontamination and decommissioning systems. Membrane-screening tests were performed with the SpinTek STC-X4 static test cell filtration unit, using five ceramic membranes with different pore size and composition. Based on permeate flux, a 0.25-{micro}m TiO{sub 2}/Al{sub 2}O{sub 3} membrane was selected for detailed performance evaluation using the SpinTek ST-IIL centrifugal membrane filtration unit with a surrogate tank waste solution. An extended test run of 100 hr performed on a surrogate tank waste solution showed some deterioration in filtration performance, based on flux, apparently due to the buildup of solids near the inner portion of the membrane where relative membrane velocities were low. Continued testing of the system will focus on modifications to the shear pattern across the entire membrane surface to affect improved long-term performance.

  17. Low-molecular weight plasma proteome analysis using centrifugal ultrafiltration. (United States)

    Greening, David W; Simpson, Richard J


    The low-molecular weight fraction (LMF) of the human plasma proteome is an invaluable source of biological information, especially in the context of identifying plasma-based biomarkers of disease. This protocol outlines a standardized procedure for the rapid/reproducible LMF profiling of human plasma samples using centrifugal ultrafiltration fractionation, followed by 1D-SDS-PAGE separation and nano-LC-MS/MS. Ultrafiltration is a convective process that uses anisotropic semipermeable membranes to separate macromolecular species on the basis of size. We have optimized centrifugal ultrafiltration for plasma fractionation with respect to buffer and solvent composition, centrifugal force, duration and temperature to facilitate >95% recovery, and enrichment of low-M (r) components from human plasma. Using this protocol, >260 unique peptides can be identified from a single plasma profiling experiment using 100 μL of plasma (Greening and Simpson, J Proteomics 73:637-648, 2010). The efficacy of this method is demonstrated by the identification, for the first time, of several plasma proteins (e.g., protein KIAA0649 (Q9Y4D3), rheumatoid factor D5, serine protease inhibitor A3, and transmembrane adapter protein PAG) previously not reported in extant high-confidence Human Proteome Organization Plasma Proteome Project datasets.

  18. Roller and Centrifugal Pumps: A Retrospective Comparison of Bleeding Complications in Extracorporeal Membrane Oxygenation. (United States)

    Halaweish, Ihab; Cole, Adam; Cooley, Elaine; Lynch, William R; Haft, Jonathan W


    Centrifugal pumps are increasingly used for extracorporeal membrane oxygenation (ECMO) rather than roller pumps. However, shear forces induced by these types of continuousflow pumps are associated with acquired von Willebrand factor deficiency and bleeding complications. This study was undertaken to compare adverse bleeding complications with the use of centrifugal and roller pumps in patients on prolonged ECMO support. The records of all adult ECMO patients from June 2002 to 2013 were retrospectively reviewed using the University of Michigan Health System database and the Extracorporeal Life Support Organization registry, focusing on patients supported for at least 5 days. Ninety-five ECMO patients met criteria for inclusion (48 roller vs. 47 centrifugal pump). Indications included pulmonary (79%), cardiac (15%), and extracorporeal cardiopulmonary resuscitation (6%), without significant difference between the two groups. Despite lower heparin anticoagulation (10.9 vs. 13.7 IU/kg/hr) with centrifugal pumps, there was a higher incidence of nonsurgical bleeding (gastrointestinal, pulmonary, and neurological) in centrifugal pump patients (26.1 vs. 9.0 events/1,000 patient-days, p = 0.024). In conclusion, in our historical comparison, despite reduced anticoagulation, ECMO support using centrifugal pumps was associated with a higher incidence of nonsurgical bleeding. The mechanisms behind this are multifactorial and require further investigation.

  19. Centrifuge workers study. Phase II, completion report

    Energy Technology Data Exchange (ETDEWEB)

    Wooten, H.D.


    Phase II of the Centrifuge Workers Study was a follow-up to the Phase I efforts. The Phase I results had indicated a higher risk than expected among centrifuge workers for developing bladder cancer when compared with the risk in the general population for developing this same type of cancer. However, no specific agent could be identified as the causative agent for these bladder cancers. As the Phase II Report states, Phase I had been limited to workers who had the greatest potential for exposure to substances used in the centrifuge process. Phase II was designed to expand the survey to evaluate the health of all employees who had ever worked in Centrifuge Program Departments 1330-1339 but who had not been interviewed in Phase I. Employees in analytical laboratories and maintenance departments who provided support services for the Centrifuge Program were also included in Phase II. In December 1989, the Oak Ridge Associated Universities (ORAU), now known as Oak Ridge Institute for Science and Education (ORISE), was contracted to conduct a follow-up study (Phase II). Phase H of the Centrifuge Workers Study expanded the survey to include all former centrifuge workers who were not included in Phase I. ORISE was chosen because they had performed the Phase I tasks and summarized the corresponding survey data therefrom.

  20. Accuracy assessment on the analysis of unbound drug in plasma by comparing traditional centrifugal ultrafiltration with hollow fiber centrifugal ultrafiltration and application in pharmacokinetic study. (United States)

    Zhang, Lin; Zhang, Zhi-Qing; Dong, Wei-Chong; Jing, Shao-Jun; Zhang, Jin-Feng; Jiang, Ye


    In present study, accuracy assessment on the analysis of unbound drug in plasma was made by comparing traditional centrifugal ultrafiltration (CF-UF) with hollow fiber centrifugal ultrafiltration (HFCF-UF). We used metformin (MET) as a model drug and studied the influence of centrifugal time, plasma condition and freeze-thaw circle times on the ultrafiltrate volume and related effect on the measurement of MET. Our results demonstrated that ultrafiltrate volume was a crucial factor which influenced measurement accuracy of unbound drug in plasma. For traditional CF-UF, the ultrafiltrate volume cannot be well-controlled due to a series of factors. Compared with traditional CF-UF, the ultrafiltrate volume by HFCF-UF can be easily controlled by the inner capacity of the U-shaped hollow fiber inserted into the sample under enough centrifugal force and centrifugal time, which contributes to a more accurate measurement. Moreover, the developed HFCF-UF method achieved a successful application in real plasma samples and exhibited several advantages including high precision, extremely low detection limit and perfect recovery. The HFCF-UF method offers the advantage of highly satisfactory performance in addition to being simple and fast in pretreatment, with these characteristics being consistent with the practicability requirements in current scientific research.

  1. Combining ergometer exercise and artificial gravity in a compact-radius centrifuge (United States)

    Diaz, Ana; Trigg, Chris; Young, Laurence R.


    Humans experience physiological deconditioning during space missions, primarily attributable to weightlessness. Some of these adverse consequences include bone loss, muscle atrophy, sensory-motor deconditioning, and cardiovascular alteration, which may lead to orthostatic intolerance when astronauts return to Earth. Artificial gravity could provide a comprehensive countermeasure capable of challenging all the physiological systems at once, particularly if combined with exercise, thereby maintaining overall health during extended exposure to weightlessness. A new Compact Radius Centrifuge (CRC) platform was designed and built on the existing Short Radius Centrifuge (SRC) at the Massachusetts Institute of Technology (MIT). The centrifuge has been constrained to a radius of 1.4 m, the upper radial limit for a centrifuge to fit within an International Space Station (ISS) module without extensive structural alterations. In addition, a cycle ergometer has been added for exercise during centrifugation. The CRC now includes sensors of foot forces, cardiovascular parameters, and leg muscle electromyography. An initial human experiment was conducted on 12 subjects to analyze the effects of different artificial gravity levels (0 g, 1 g, and 1.4 g, measured at the feet) and ergometer exercise intensities (25 W warm-up, 50 W moderate and 100 W vigorous) on the musculoskeletal function as well as motion sickness and comfort. Foot forces were measured during the centrifuge runs, and subjective comfort and motion sickness data were gathered after each session. Preliminary results indicate that ergometer exercise on a centrifuge may be effective in improving musculoskeletal function. The combination is well tolerated and motion sickness is minimal. The MIT CRC is a novel platform for future studies of exercise combined with artificial gravity. This combination may be effective as a countermeasure to space physiological deconditioning.

  2. Deburring by centrifugal barrel tumbling

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, L.K.


    The reliability of small precision mechanisms greatly depends upon the production of burr-free, sharp-edged parts. Centrifugal barrel finishing (Harperizing) is one of the few processes capable of producing these conditions. Burrs less than 0.001-in. thick by 0.001-in. high (25.4 x 25.4 can be removed from 303 Se stainless steel, 1018 steel, and 6061-T6 aluminum with dimensional changes in the order of 0.0001-in. (2.54 and final edge radii of 0.003 in. (76.2 These conditions can be produced in batch lots in 20 minutes or less. Surface finishes can be reduced from 45 to 25 or 35 microinches (1.15 to 0.68 or 0.89, with 60-minute cycle times. Stock losses appear to be repeatable within +-0.00006 in. (1.524 Very small parts receive less action than parts 0.5 in. (12.7 mm) in dia.

  3. Molecular structure and centrifugal distortion in methylthioethyne

    NARCIS (Netherlands)

    Engelsen, D. den


    The investigation of the microwave spectra of five isotopic species of methylthioethyne, HCCSCH3 enabled a fairly reliable calculation to be made of bond lengths and angles. The centrifugal distortion parameters are related to molecular vibrations.

  4. Geotechnical Centrifuge Studies of Unsaturated Transport (United States)

    Smith, R. W.; Mattson, E. D.; Palmer, C. D.


    Improved understanding of contaminant migration in heterogeneous, variably saturated porous media is required to better define the long-term stewardship requirements for U.S. Department of Energy (DOE) lands and to assist in the design of effective vadose-zone barriers to contaminant migrations. A geotechnical centrifuge provides an experimental approach to explore vadose zone transport over a wide range of relevant conditions in time frames not possible for conventional bench-top experiments. Our research to date resulted in the design, construction, and testing of in-flight experimental apparatus allowing the replication of traditional bench top unsaturated transport experiments using the 2-meter radius geotechnical centrifuge capabilities at the Idaho National Laboratory. Additionally we conducted a series of unsaturated 1-dimenstional column experiments using conservative tracers to evaluate the effects of increased centrifugal acceleration on derived transport properties and assessing the scaling relationships for these properties. Our experimental results indicated that breakthrough times for a conservative tracer decreased significantly and systematically as a function of increased centrifugal acceleration. Differences between these experimental results and estimates based on predictive scaling rules are due to slight moisture content differences between experiments at different centrifugal accelerations. In contrast, dispersion coefficients varied systemically with centrifugal acceleration in accordance with predictive scaling rules. The results we obtained in this study indicate that the centrifuge technique is a viable experimental method for the study of subsurface processes where gravitational acceleration is important. The geotechnical centrifuge allows experiments to be completed more quickly than tests conducted at 1-gravity and can be used to experimentally address important scaling issues, and permits experiments under a range of conditions that

  5. Hydrodynamic impeller stiffness, damping, and inertia in the rotordynamics of centrifugal flow pumps (United States)

    Jery, S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.


    The lateral hydrodynamic forces experienced by a centrifugal pump impeller performing circular whirl motions within several volute geometries were measured. The lateral forces were decomposed into: (1) time averaged lateral forces and (2) hydrodynamic force matrices representing the variation of the lateral forces with position of the impeller center. It is found that these force matrices essentially consist of equal diagonal terms and skew symmetric off diagonal terms. One consequence of this is that during its whirl motion the impeller experiences forces acting normal and tangential to the locus of whirl. Data on these normal and tangential forces are presented; it is shown that there exists a region of positive reduced whirl frequencies, within which the hydrodynamic forces can be destablizing with respect to whirl.

  6. Clinical experience with the Sarns centrifugal pump. (United States)

    Curtis, J J; Walls, J T; Demmy, T L; Boley, T M; Schmaltz, R A; Goss, C F; Wagner-Mann, C C


    Since October 1986, we have had experience with 96 Sarns centrifugal pumps in 72 patients (pts). Heparinless left atrial to femoral artery or aorta bypass was used in 14 pts undergoing surgery on the thoracic aorta with 13 survivors (93%). No paraplegia or device-related complications were observed. In 57 patients, the Sarns centrifugal pump was used as a univentricular (27 pts) or biventricular (30 pts) cardiac assist device for postcardiotomy cardiogenic shock. In these patients, cardiac assist duration ranged from 2 to 434 h with a hospital survival rate of 29% in those requiring left ventricular assist and 13% in those requiring biventricular assist. Although complications were ubiquitous in this mortally ill patient population, in 5,235 pump-hours, no pump thrombosis was observed. Hospital survivors followed for 4 months to 6 years have enjoyed an improved functional class. We conclude that the Sarns centrifugal pump is an effective cardiac assist device when used to salvage patients otherwise unweanable from cardiopulmonary bypass. Partial left ventricular bypass using a centrifugal pump has become our procedure of choice for unloading the left ventricle and for maintenance of distal aortic perfusion pressure when performing surgery on the thoracic aorta. This clinical experience with the Sarns centrifugal pump appears to be similar to that reported with other centrifugal assist devices.

  7. A Turbidity Test Based Centrifugal Microfluidics Diagnostic System for Simultaneous Detection of HBV, HCV, and CMV

    Directory of Open Access Journals (Sweden)

    Hung-Cheng Chang


    Full Text Available This paper presents a LAMP- (loop-mediated isothermal amplification- based lab-on-disk optical system that allows the simultaneous detection of hepatitis B virus, hepatitis C virus, and cytomegalovirus. The various flow stages are controlled in the proposed system using different balance among centrifugal pumping, Coriolis pumping, and the capillary force. We have implemented a servo system for positioning and speed control for the heating and centrifugal pumping. We have also successfully employed a polymer light-emitting diode section for turbidity detection. The easy-to-use one-click system can perform diagnostics in less than 1 hour.

  8. Centrifuge modelling of lateral displacement of buried pipelines; Modelagem fisica centrifuga de flambagem lateral de dutos

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Jose Renato Moreira da Silva de; Almeida, Marcio de Souza Soares de; Marques, Maria Esther Soares; Almeida, Maria Cascao Ferreira de [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE); Costa, Alvaro Maia da [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)


    This work discusses soil-structure interaction applied to the buckling phenomena of buried pipelines subjected to heated oil flow. A set of physical modelling tests on lateral buckling of pipelines buried on soft clay is presented using COPPE/UFRJ geotechnical centrifuge. A 1:30 pipeline model was moved side ward through a soft clay layer during centrifuge flight, varying the burial depth, in order to simulate the lateral buckling in plane strain condition. The results show different behaviour concerning horizontal and vertical forces measured at pipeline level due to soil reaction. (author)

  9. The application of two-dimensional centrifugation to clinical chemistry testing. (United States)

    Holen, J T; Schultz, S G; Wong, S T


    We have developed a new clinical chemistry analyzer, the VISION System, which uses centrifugal force to separate whole blood, measure reagent and plasma volumes, and complete all steps required for a spectrophotometric analysis. The system is based on a multichambered test pack containing liquid reagents, which can be centrifuged in two planes oriented at right angles to each other. The analyzer regulates the temperature, timing and optical measurements for up to 10 different test packs in the same run. We have demonstrated good precision and accuracy on 6 clinical chemistry analytes, 2 enzymes, potassium and theophylline using this system.

  10. Quantum fictitious forces

    DEFF Research Database (Denmark)

    Bialynicki-Birula, I; Cirone, M.A.; Dahl, Jens Peder


    We present Heisenberg's equation of motion for the radial variable of a free non-relativistic particle in D dimensions. The resulting radial force consists of three contributions: (i) the quantum fictitious force which is either attractive or repulsive depending on the number of dimensions, (ii......) a singular quantum force located at the origin, and (iii) the centrifugal force associated with non-vanishing angular momentum. Moreover, we use Heisenberg's uncertainty relation to introduce a lower bound for the kinetic energy of an ensemble of neutral particles. This bound is quadratic in the number...... of atoms and can be traced back to the repulsive quantum fictitious potential. All three forces arise for a free particle: "Force without force"....

  11. Quantum fictitious forces

    Energy Technology Data Exchange (ETDEWEB)

    Bialynicki-Birula, I. [Center for Theoretical Physics, Polish Academy of Sciences, Warsaw (Poland); Abt. fuer Quantenphysik, Univ. Ulm, Ulm (Germany); Cirone, M.A.; Straub, F.; Schleich, W.P. [Abt. fuer Quantenphysik, Univ. Ulm, Ulm (Germany); Dahl, J.P. [Abt. fuer Quantenphysik, Univ. Ulm, Ulm (Germany); Chemical Physics, Dept. of Chemistry, Technical Univ. of Denmark, Lyngby (Denmark); Seligman, T.H. [Centro de Ciencias Fisicas, Univ. of Mexico (UNAM), Cuernavaca (Mexico)


    We present Heisenberg's equation of motion for the radial variable of a free non-relativistic particle in D dimensions. The resulting radial force consists of three contributions: (i) the quantum fictitious force which is either attractive or repulsive depending on the number of dimensions, (ii) a singular quantum force located at the origin, and (iii) the centrifugal force associated with non-vanishing angular momentum. Moreover, we use Heisenberg's uncertainty relation to introduce a lower bound for the kinetic energy of an ensemble of neutral particles. This bound is quadratic in the number of atoms and can be traced back to the repulsive quantum fictitious potential. All three forces arise for a free particle: ''Force without force''. (orig.)

  12. On the saturation of the centrifugally excited curvature drift instability in AGN magnetospheres

    CERN Document Server

    Osmanov, Z


    We study a saturation process of the centrifugally driven curvature drift instability (CDI) in AGN magnetospheres close to the light cylinder surface to examine the twisting of magnetic field lines leading to the free motion of AGN winds, that completely kills the instability. Considering the Euler, continuity, and induction equations, by taking into account the resonant conditions, we derive the growth rate of the CDI. We show that due to the centrifugal effects, the rotational energy is efficiently pumped directly into the drift modes, that leads to the generation of a toroidal component of the magnetic field. As a result, the magnetic field lines transform into such a configuration when particles do not experience any forces and since the instability is centrifugally driven, at this stage the CDI is completely killed.

  13. Effects of centrifugation on transmembrane water loss from normal and pathologic erythrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Kaperonis, A.A.; Chien, S.


    Plasma /sup 125/I-albumin was used as a marker of extracellular dilution in order to study the effect of high-speed centrifugation on transmembrane water distribution in several types of human red cells, including normal (AA), hemoglobin variants (beta A, AS, SC, beta S, and SS), and those from patients with hereditary spherocytosis. SS and AA erythrocytes were also examined for changes in intracellular hemoglobin concentration of three different density fractions and with increasing duration of spin. The minimum force and duration of centrifugation required to impair water permeability were found to vary with the red cell type, the anticoagulant used (heparin or EDTA), the initial hematocrit of the sample centrifuged, as well as among the individual erythrocyte fractions within the same sample. When subjecting pathologic erythrocytes to high-speed centrifugation, the /sup 125/I-albumin dilution technique can be used to determine whether the centrifugation procedure has led to an artifactual red cell water loss and to correct for this when it does occur. An abnormal membrane susceptibility to mechanical stress was demonstrated in erythrocytes from patients with hereditary spherocytosis and several hemoglobinopathies.

  14. Centrifugal acceleration in the magnetotail lobes

    Directory of Open Access Journals (Sweden)

    H. Nilsson


    Full Text Available Combined Cluster EFW and EDI measurements have shown that cold ion outflow in the magnetospheric lobes dominates the hydrogen ion outflow from the Earth's atmosphere. The ions have too low kinetic energy to be measurable with particle instruments, at least for the typical spacecraft potential of a sunlit spacecraft in the tenuous lobe plasmas outside a few RE. The measurement technique yields both density and bulk velocity, which can be combined with magnetic field measurements to estimate the centrifugal acceleration experienced by these particles. We present a quantitative estimate of the centrifugal acceleration, and the velocity change with distance which we would expect due to centrifugal acceleration. It is found that the centrifugal acceleration is on average outward with an average value of about of 5 m s−2. This is small, but acting during long transport times and over long distances the cumulative effect is significant, while still consistent with the relatively low velocities estimated using the combination of EFW and EDI data. The centrifugal acceleration should accelerate any oxygen ions in the lobes to energies observable by particle spectrometers. The data set also put constraints on the effectiveness of any other acceleration mechanisms acting in the lobes, where the total velocity increase between 5 and 19 RE geocentric distance is less than 5 km s−1.

  15. A Review of Biomedical Centrifugal Microfluidic Platforms

    Directory of Open Access Journals (Sweden)

    Minghui Tang


    Full Text Available Centrifugal microfluidic or lab-on-a-disc platforms have many advantages over other microfluidic systems. These advantages include a minimal amount of instrumentation, the efficient removal of any disturbing bubbles or residual volumes, and inherently available density-based sample transportation and separation. Centrifugal microfluidic devices applied to biomedical analysis and point-of-care diagnostics have been extensively promoted recently. This paper presents an up-to-date overview of these devices. The development of biomedical centrifugal microfluidic platforms essentially covers two categories: (i unit operations that perform specific functionalities, and (ii systems that aim to address certain biomedical applications. With the aim to provide a comprehensive representation of current development in this field, this review summarizes progress in both categories. The advanced unit operations implemented for biological processing include mixing, valving, switching, metering and sequential loading. Depending on the type of sample to be used in the system, biomedical applications are classified into four groups: nucleic acid analysis, blood analysis, immunoassays, and other biomedical applications. Our overview of advanced unit operations also includes the basic concepts and mechanisms involved in centrifugal microfluidics, while on the other hand an outline on reported applications clarifies how an assembly of unit operations enables efficient implementation of various types of complex assays. Lastly, challenges and potential for future development of biomedical centrifugal microfluidic devices are discussed.

  16. Regularized thin-fiber model for nanofiber formation by centrifugal spinning (United States)

    Taghavi, S. M.; Larson, R. G.


    We propose a regularized thin-fiber (string) model that overcomes past numerical limitations and allows determination of the steady fiber velocity and diameter of a semi-infinite Newtonian viscous fiber emerging from a nozzle rotating about an axis in the presence of centrifugal, inertial, and viscous forces of arbitrary magnitudes. The results are controlled by two dimensionless groups, namely, the Rossby number Rb expressing the ratio of inertial to centrifugal forces and the Reynolds number Re, the ratio of inertial to viscous forces. We find that for Rb 0.5, regularization is not required, the curvature in fiber trajectory is increased by viscosity, and the solution at large distances along the spin line does not converge to the inviscid result. Regimes of behavior in the plane formed by Re and Rb are mapped out and example behavior is given for each regime.

  17. Development Status-quo of Centrifugal Spinning Technology%离心纺丝技术的发展现状

    Institute of Scientific and Technical Information of China (English)

    黄冬徽; 陈廷; 吴丽莉


    离心纺丝是一种利用离心力进行纺丝的新型微纳米纤维制备技术。本文介绍了离心纺丝的基本原理,综述了离心纺丝设备的发展现状,阐述了纺丝过程中工艺参数对纤维的形貌、直径及结晶度的影响。%Centrifugal spinning is a new micro-nano fiber manufacturing technology by the use of centrifugal force. The fundamental principle of centrifugal spinning and development status-quo of the centrifugal spinning equipments were introduced in this paper. Besides, the effects of the process parameters on the morphology, diameter and crystallinity of fibers were stated.

  18. Microstructures in Centrifugal Casting of SiCp/AlSi9Mg Composites with Different Mould Rotation Speeds

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; SUN Wenju; LI Bo; XUIE Hansong; LIU Changming


    Two ingots were produced by centrifugal casting at mould rotational speeds of 600 rpm and 800 rpm using 20 vol% SiCp/AlSi9Mg composite melt, respectively. The microstructure along the radial direction of cross-sectional sample of ingots was presented. SiC particles migrated towards the external circumference of the tube, and the distribution of SiC particles became uniform under centrifugal force. Voids in 20 vol% SiCp/AlSi9Mg composite melt migrated towards the inner circumference of the tube. The quantitative analysis results indicated that not only SiC particles but also primary a phases segregated greatly in centrifugal casting resulting from the transportation behavior of constitutions with different densities in the SiCp/AlSi9Mg composite melt. In addition, the eutectic Si was broken owing to the motion of SiCp/AlSi9Mg composite melt during centrifugal casting.

  19. Analysis of Secondary Flows in Centrifugal Impellers

    Directory of Open Access Journals (Sweden)

    Brun Klaus


    Full Text Available Secondary flows are undesirable in centrifugal compressors as they are a direct cause for flow (head losses, create nonuniform meridional flow profiles, potentially induce flow separation/stall, and contribute to impeller flow slip; that is, secondary flows negatively affect the compressor performance. A model based on the vorticity equation for a rotating system was developed to determine the streamwise vorticity from the normal and binormal vorticity components (which are known from the meridional flow profile. Using the streamwise vorticity results and the small shear-large disturbance flow method, the onset, direction, and magnitude of circulatory secondary flows in a shrouded centrifugal impeller can be predicted. This model is also used to estimate head losses due to secondary flows in a centrifugal flow impeller. The described method can be employed early in the design process to develop impeller flow shapes that intrinsically reduce secondary flows rather than using disruptive elements such as splitter vanes to accomplish this task.

  20. Cardio-postural interactions and short-arm centrifugation. (United States)

    Blaber, Andrew; Goswami, Nandu; Xu, Da; Laurin, Alexendre

    INTRODUCTION: We are interested in mechanisms associated with orthostatic tolerance. In previous studies we have shown that postural muscles in the calf contribute to both posture and blood pressure regulation during orthostatic stress. In this study we investigated the relationship between cardiovascular and postural muscle control before, during and after short arm human centrifuge (SAHC) up to 2.2 G. METHODS: Eleven healthy young subjects (6 m, 5 f), with no history of cardiovascular disease, falls or orthostatic hypotension, participated. All were familiarized with the SAHC with 10 minutes at 1-G at the feet. Each subject was instrumented in the supine position on the SAHC for beat-to-beat ECG and blood pressure (Portapres derived SBP). Bilateral lower leg EMG was collected from four leg postural muscles: tibialis anterior, medial gastrocnemius, lateral gastrocnemius, and medial soleus. Transdermal differential recording of signals was performed using an 8-channel EMG system, (Myosystem 1200, Noraxon Inc., Arizona, USA). Postural sway data of the body COP was computed from the force and moment data collected with a force platform (Accusway, AMTI, MA, USA). Before and after SAHC, the subject stood on a force platform with their gaze fixed on a point at eye level, closed their eyes and stood quietly for 5 min. A final stand was conducted 30 min after centrifugation with supine rest in between. During clockwise centrifugation (10-min 1g and 10-min 2.2g at the foot) the subjects’ head was hooded and in the dark. The subject’s body was restrained into the rotation arm with a parachute harness and given additional body support with a foot-plate. ECG, EMG and BP data were collected throughout and centre of pressure trajectory (COP) collected during the stand test. Subjects were requested to relax and not to voluntarily contract the leg muscles; however, they were not to suppress contractions as they occurred involuntarily or by reflex. A Continuous Wavelet

  1. Detection methods for centrifugal microfluidic platforms

    DEFF Research Database (Denmark)

    Burger, Robert; Amato, Letizia; Boisen, Anja


    Centrifugal microfluidics has attracted much interest from academia as well as industry, since it potentially offers solutions for affordable, user-friendly and portable biosensing. A wide range of so-called fluidic unit operations, e.g. mixing, metering, liquid routing, and particle separation......, have been developed and allow automation and integration of complex assay protocols in lab-on-a-disc systems. Besides liquid handling, the detection strategy for reading out the assay is crucial for developing a fully integrated system. In this review, we focus on biosensors and readout methods...... for the centrifugal microfluidics platform and cover optical as well as mechanical and electrical detection principles....

  2. Dual asymmetric centrifugation (DAC)--a new technique for liposome preparation. (United States)

    Massing, Ulrich; Cicko, Sanja; Ziroli, Vittorio


    This is the first report on the use of a "dual asymmetric centrifuge (DAC)" for preparing liposomes. DAC differs from conventional centrifugation by an additional rotation of the sample around its own vertical axis: While the conventional centrifugation constantly pushes the sample material outwards, this additional rotation constantly forces the sample material towards the center of the centrifuge. This unique combination of two contra rotating movements results in shear forces and thus, in efficient homogenization. We demonstrated that it is possible to prepare liposomes by DAC, by homogenizing a rather concentrated blend of hydrogenated phosphatidylcholine and cholesterol (55:45 mol%) and 0.9% NaCl-solution, which results in a viscous vesicular phospholipid gel (VPG). The resulting VPG can subsequently be diluted to a conventional liposome dispersion. Since DAC is intended to make sterile preparations of liposomes, or to entrap toxic/radioactive compounds, the process was performed within a sealed vial. It could be shown that the DAC speed, the lipid concentration, the homogenization time and the addition of a mixing aid (glass beads) are all critical for the size of the liposomes. Optimized conditions resulted in liposomes of 60+/-5 nm and a trapping efficacy of 56+/-3.3% for the model compound calcein.

  3. Centrifugal Pump Experiment for Chemical Engineering Undergraduates (United States)

    Vanderslice, Nicholas; Oberto, Richard; Marrero, Thomas R.


    The purpose of this paper is to describe a Centrifugal Pump Experiment that provided an experiential learning experience to chemical engineering undergraduates at the University of Missouri in the spring of 2010 in the Unit Operations Laboratory course. Lab equipment was used by senior students with computer-based data and control technology. In…


    This document is an evaluation of the performance of the Retech, Inc. Plasma Centrifugal Furnace (PCF) and its applicability as a treatment for soils contaminated with organic and/or inorganic compounds. Both the technical and economic aspectsof the technology were examined. A...

  5. Performance of a Centrifugal Slurry Pump

    Directory of Open Access Journals (Sweden)

    Hawas Yahya Bajawi


    Full Text Available The aim of this study was to experimentally investigate the effect of speed, concentration and size of slurry on the performance of a centrifugal pump. For this purpose a facility was built where the performance of a centrifugal slurry pump was examined using aggregate slurry. Three sizes of slurry with three concentrations and at three impeller speeds were used for the performance investigations of a centrifugal slurry pump. As a reference performance the performance of centrifugal slurry pump was also tested with clean water. The performance of pump has been reported as variations of head, power and efficiency at various flow rates along with the system characteristics of the pump. The results reveal that the pump performance is grossly affected by the type of slurry, its concentration and size. Besides this the variation in speed also affects the performance as is observed in pumps with water. The maximum decrease in the head, with respect to clear water, at the operating point was found to be 47% for aggregate for size 20 mm, 15% concentration and 2600 rpm. The maximum decrement in efficiency at operating point for aggregate was found to be 47% for 4 mm size, 15% concentration and at 2200 rpm. The power increment requirement for aggregate was 9% for 4 mm size, 15% concentration and 2600 rpm.

  6. Predicting Droplet Formation on Centrifugal Microfluidic Platforms (United States)

    Moebius, Jacob Alfred

    Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system. Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzable solution. Volume definition is one such step. The focus of this thesis is the development of a model predicting monodispersed droplet formation and the application of droplets as a technique for volume definition. First, a background of droplet microfluidic platforms is presented, along with current biological analysis technologies and the advantages of integrating such technologies onto microfluidic platforms. Second, background and theories of centrifugal microfluidics is given, followed by theories relevant to droplet emulsions. Third, fabrication techniques for centrifugal microfluidic designs are discussed. Finally, the development of a model for predicting droplet formation on the centrifugal microfluidic platform are presented for the rest of the thesis. Predicting droplet formation analytically based on the volumetric flow rates of the continuous and dispersed phases, the ratios of these two flow rates, and the interfacial tension between the continuous and dispersed phases presented many challenges, which will be discussed in this work. Experimental validation was completed using continuous phase solutions of different interfacial tensions. To conclude, prospective applications are discussed with expected challenges.

  7. Centrifugal Casting of Tubular Perovskite Membranes

    NARCIS (Netherlands)

    Mertins, Frederic H.B.; Kruidhof, Henk; Bouwmeester, Henny J.M.


    Dense tubular membranes were produced by centrifugal casting of an aqueous suspension, containing powder particles of the mixed-conducting perovskite La0.5Sr0.5CoO3−δ and a dispersant. The resulting green bodies were dried and sintered to produce tubes with a maximum length of 12 cm, having a relat

  8. Evaluation of an improved centrifugal casting machine. (United States)

    Donovan, T E; White, L E


    A Type III gold alloy, a silver-palladium alloy, and a base metal alloy were cast in two different centrifugal casting machines. With the number of complete cast mesh squares as an indicator of castability, the Airspin casting machine produced superior castings with all three alloys. The base metal alloy produced the greatest number of complete squares with both casting machines.

  9. Pressure distribution in centrifugal dental casting. (United States)

    Nielsen, J P


    Equations are developed for liquid metal pressure in centrifugal dental casting, given the instantaneous rotational velocity, density, and certain dimensions of the casting machine and casting pattern. A "reference parabola" is introduced making the fluid pressure concept more understandable. A specially designed specimen demonstrates experimentally the reference parabola at freezing.

  10. A multiple disk centrifugal pump as a blood flow device. (United States)

    Miller, G E; Etter, B D; Dorsi, J M


    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps.

  11. Application of IMHOFLOT G-cell centrifugal flotation technology

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, R.; Fletcher, M.; Vathavooran, A.; Singh, A. [Maelgwyn Mining Services Ltd., Cardiff (United Kingdom)


    The Imhoflot G-Cell, a new development in the pneumatic flotation technology (which incorporates centrifugal forces in the separating vessel), is a recent innovation in the mineral processing world. The G-Cell was invented by Dr Rainer Imhof and commercialized by Maelgwyn Mineral Services Ltd. In a short time span a number of plants and units have been successfully commissioned in the mineral processing industry. In addition, a number of industrial G-Cell flotation plants are in the process of construction for the purpose of coal preparation and environmental remediation. In this paper two industrial installations have been highlighted, together with a pilot plant test programme investigating ultra-fine flotation recovery for a base metal operation.

  12. Casting defects of Ti-6Al-4V alloy in vertical centrifugal casting processes with graphite molds (United States)

    Jia, Limin; Xu, Daming; Li, Min; Guo, Jingjie; Fu, Hengzhi


    Numerical simulation and experimental investigation are utilized to analyze the casting defects of Ti-6Al-4V alloy formed under different vertical centrifugal casting conditions in graphite molds. Mold rotating rates of 0, 110 and 210 rpm are considered in experimental process. Results show that centrifugal forces have significant effects on the quantity of both macropores and microdefects (micropores, microcracks and inclusions). The relative amount of all macro- and micro-scopic casting defects decreases from 62.4 % to 24.8 % with the increasing of the centrifugal force, and the macropore quantity in stepped casting decreases exponentially with the increase of the gravitation coefficient. The relative proportions of both micropores and microcracks decrease with the mold-rotating rate increase, but the relative proportion of inclusions increases significantly. Besides this, the mold-filling sequence is proved to be an important factor in casting quality control.

  13. Evolution of microstructure in centrifugal cast Al-Cu alloy

    Directory of Open Access Journals (Sweden)

    Sui Yanwei


    Full Text Available In this research, the effects of centrifugal radius and mould rotation speed on microstructure in centrifugal-cast Al-Cu alloy have been investigated. The results show that, with increase of the centrifugal radius or mould rotation speed, the grain size of centrifugal-cast Al-Cu alloy decreases gradually, while the content of white phases containing the Al2Cu precipitated from α-phase, divorced eutectic and regular eutectic microstructure increases, leading to higher Cu macrosegregation. The variation level of microstructure in centrifugal-cast Al-Cu alloy at 600 rpm of mould rotation speed is greater than that at 300 rpm.

  14. Fabrication of Al/Al3Ti Functionally Graded Materials by Reaction Centrifugal Mixed-Powder Method (United States)

    El-Hadad, Shimaa; Sato, Hisashi; Miura-Fujiwara, Eri; Watanabe, Yoshimi


    Formation of compositional gradient in Al/Al3Ti Functionally graded materials (FGMs) fabricated by the centrifugal method (CM) depends mainly on the centrifugal force and the processing temperature. In this study, a novel centrifugal method, reaction centrifugal mixed-powder method (RCMPM), was proposed to fabricate Al/Al3Ti FGMs under fixed centrifugal force (G=80). The effects of RCMPM processing temperature on the formation of Al3Ti intermetallics, its morphology and its distribution in the fabricated Al/Al3Ti FGMs have been investigated. Fine granular Al3Ti were observed at relatively lower processing temperature while the known coarse platelet-like particles of Al3Ti could be achieved at higher casting temperatures. Moreover, Ti3Al intermetallics compound and unreacted Ti phases are also observed along with Al3Ti particles. In addition, distribution of Al3Ti intermetallics size and their volume fraction showed a significant change when the Al/Al3Ti FGMs processed at different temperatures relative to the liquidus temperature of the master alloy.

  15. Meridional Considerations of the Centrifugal Compressor Development

    Directory of Open Access Journals (Sweden)

    C. Xu


    Full Text Available Centrifugal compressor developments are interested in using optimization procedures that enable compressor high efficiency and wide operating ranges. Recently, high pressure ratio and efficiency of the centrifugal compressors require impeller design to pay attention to both the blade angle distribution and the meridional profile. The geometry of the blades and the meridional profile are very important contributions of compressor performance and structure reliability. This paper presents some recent studies of meridional impacts of the compressor. Studies indicated that the meridional profiles of the impeller impact the overall compressor efficiency and pressure ratio at the same rotational speed. Proper meridional profiles can improve the compressor efficiency and increase the overall pressure ratio at the same blade back curvature.

  16. Fault Detection and Isolation in Centrifugal Pumps

    DEFF Research Database (Denmark)

    Kallesøe, Carsten

    Centrifugal pumps are used in a variety of different applications, such as water supply, wastewater, and different industrial applications. Some pump installations are crucial for the applications to work. Failures can lead to substantial economic losses and can influence the life of many people...... when they occur. Therefore, detection of faults, if possible in an early stage, and isolation of their causes are of great interest. Especially fault detection, which can be used for predictive maintenance, can decrease working expenses and increase the reliability of the application in which the pump...... is placed. The topic of this work is Fault Detection and Identification in centrifugal pumps. Different approaches are developed with special focus on robustness. Robustness with respect to disturbances, unknown parts of the system, and parameter variations are considered. All developed algorithms...

  17. Removal of primary iron rich phase from aluminum-silicon melt by centrifugal separation

    Directory of Open Access Journals (Sweden)

    Seong Woo Kim


    Full Text Available Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of Al-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in Al-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two Al-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for Al-12Si-1.7Fe alloy. And they are 82% and 18% for Al-12Si-3.4Fe alloy, respectively.

  18. Analysis of Secondary Flows in Centrifugal Impellers



    Secondary flows are undesirable in centrifugal compressors as they are a direct cause for flow (head) losses, create nonuniform meridional flow profiles, potentially induce flow separation/stall, and contribute to impeller flow slip; that is, secondary flows negatively affect the compressor performance. A model based on the vorticity equation for a rotating system was developed to determine the streamwise vorticity from the normal and binormal vorticity components (which are known from the me...

  19. Centrifugal shot blasting. Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)


    At the US Department of Energy (DOE) Fernald Environmental Management Project (FEMP), the Facilities Closure and Demolition Projects Integrated Remedial Design/Remedial Action (RD/RA) work plan calls for the removal of one inch (1 in) depth of concrete surface in areas where contamination with technetium-99 has been identified. This report describes a comparative demonstration between two concrete removal technologies: an innovative system using Centrifugal Shot Blasting (CSB) and a modified baseline technology called a rotary drum planer.

  20. Predicting Droplet Formation on Centrifugal Microfluidic Platforms


    Moebius, Jacob Alfred


    Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system.Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzabl...

  1. Centrifugal compressor design choices for chillers

    Energy Technology Data Exchange (ETDEWEB)

    Brasz, J.J. [United Technologies Carrier, New York, NY (United States)


    The use of centrifugal compressors in the air conditioning and refrigeration industry is currently limited to large water cooled chillers varying in size from about 0.5 to 6 MW cooling capacity. These systems are primarily used for comfort or process cooling applications. All systems try to chill relatively large amounts of indoor or process water by a few degrees Celsius in a refrigerant evaporator. The heat removed from the chilled water is released together with the heat of compression in a refrigerant condenser to cooling tower water, from where it is discharged to the atmosphere. Different centrifugal compressor design concepts are used by the various chiller manufacturers: single-stage versus multi-stage, vaneless versus vaned diffuser, hermetic versus open-drive motors, shrouded versus open impellers, fixed versus variable diffuser geometry, low- versus high-pressure refrigerant. This variability seems strange for a mature industry like the air conditioning and refrigeration industry. This paper will show that the reason for this variability is the product compromise between the various conflicting system requirements with respect to size, cost, efficiency and refrigerant choice. The different system applications of the chillers (e.g. comfort cooling in a equatorial region versus process cooling in a moderate climate zone) play another major role in selecting an optimal centrifugal compression concept. Some general recommendations will be given for applications where a clear choice can be made. (Author)

  2. CFD Simulation of Annular Centrifugal Extractors

    Directory of Open Access Journals (Sweden)

    S. Vedantam


    Full Text Available Annular centrifugal extractors (ACE, also called annular centrifugal contactors offer several advantages over the other conventional process equipment such as low hold-up, high process throughput, low residence time, low solvent inventory and high turn down ratio. The equipment provides a very high value of mass transfer coefficient and interfacial area in the annular zone because of the high level of power consumption per unit volume and separation inside the rotor due to the high g of centrifugal field. For the development of rational and reliable design procedures, it is important to understand the flow patterns in the mixer and settler zones. Computational Fluid Dynamics (CFD has played a major role in the constant evolution and improvements of this device. During the past thirty years, a large number of investigators have undertaken CFD simulations. All these publications have been carefully and critically analyzed and a coherent picture of the present status has been presented in this review paper. Initially, review of the single phase studies in the annular region has been presented, followed by the separator region. In continuation, the two-phase CFD simulations involving liquid-liquid and gas-liquid flow in the annular as well as separator regions have been reviewed. Suggestions have been made for the future work for bridging the existing knowledge gaps. In particular, emphasis has been given to the application of CFD simulations for the design of this equipment.

  3. Circadian rhythm of leaf movement in Capsicum annuum observed during centrifugation (United States)

    Chapman, D. K.; Brown, A. H.; Dahl, A. O.


    Plant circadian rhythms of leaf movement in seedlings of the pepper plant (Capsicum annuum L., var. Yolo Wonder) were observed at different g-levels by means of a centrifuge. Except for the chronically imposed g-force all environmental conditions to which the plants were exposed were held constant. The circadian period, rate of change of amplitude of successive oscillations, symmetry of the cycles, and phase of the rhythm all were found not to be significantly correlated with the magnitude of the sustained g-force.

  4. Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects (United States)

    Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.


    Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

  5. Self-Assembly of Ag Nanoparticles Induced by Centrifuging and Broken by Silanization. (United States)

    Yang, Ping; Zhang, Yulan


    A novel method was developed to assemble Ag nanoparticles (NPs) into chain-like structures. The assembly of the NPs was created by suspending in an ethanol and water solution as well as centrifuging at a high speed (a force of more than 29 Kg for the NPs with an average diameter of 18 nm). The composition of solvents and centrifuged speeds of samples play important roles for the formation of regular assemblies. The number of Ag NPs in the chain-like assemblies was adjusted by changing centrifuging forces. The assemblies of the NPs were fixed by a SiO2 coating through a St6ber synthesis. In addition, the assemblies were broken through a silanization process because of partially hydrolyzed tetraethyl-orthosilicate molecules adsorbed on the surface of Ag NPs to form a SiO2 layer opposite aggregation. A slow silanization process made Ag NPs monodispersed in solutions, in which Ag/SiO2 core/shell NPs were created.

  6. An experimental study on the rotating stall in vaneless diffuser of centrifugal blower with radial type impeller

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.H. [Yonsei University Graduate School, Seoul (Korea, Republic of); Cho, K.R. [Yonsei University, Seoul (Korea, Republic of)


    The vaneless diffusers are widely used in industrial centrifugal compressors which are required to operate within a wide flow range. When very high pressure gases are handled by centrifugal compressor, rotating stall is a serious problem because of the occurrence of large aerodynamic exciting forces. Rotating stall mostly often occurs in the impellers but it can occur in vaneless diffusers as well. In this experimental study, the rotating stall in vaneless diffuser with radial type centrifugal impeller was measured by changing the flow rate with I-type, X-type hot-wire. As the result, it was cleared which type of rotating stall of the impeller stall would occur and how many stall cells would appear relating with the flow rate. As the flow rate reduced, the propagation speed of rotating stall was reduced. But the stall cell number unchanged with respect to the flow rate. (author). 7 refs., 13 figs.

  7. Centrifugation-assisted Assembly of Colloidal Silica into Crack-Free and Transferrable Films with Tunable Crystalline Structures. (United States)

    Fan, Wen; Chen, Min; Yang, Shu; Wu, Limin


    Self-assembly of colloidal particles into colloidal films has many actual and potential applications. While various strategies have been developed to direct the assembly of colloidal particles, fabrication of crack-free and transferrable colloidal film with controllable crystal structures still remains a major challenge. Here we show a centrifugation-assisted assembly of colloidal silica spheres into free-standing colloidal film by using the liquid/liquid interfaces of three immiscible phases. Through independent control of centrifugal force and interparticle electrostatic repulsion, polycrystalline, single-crystalline and quasi-amorphous structures can be readily obtained. More importantly, by dehydration of silica particles during centrifugation, the spontaneous formation of capillary water bridges between particles enables the binding and pre-shrinkage of the assembled array at the fluid interface. Thus the assembled colloidal films are not only crack-free, but also robust and flexible enough to be easily transferred on various planar and curved substrates.

  8. Fabrication of bulk metallic glasses by centrifugal casting method


    R. Nowosielski; R. Babilas


    Purpose: The aim of the present work is characterization of the centrifugal casting method, apparatus andproduced amorphous materials, which are also known as bulk metallic glassesDesign/methodology/approach: The studied centrifugal casting system consists of two main parts: castingapparatus and injection system of molten alloy. The described centrifugal casting method was presented bypreparing a casting apparatus “CentriCast – 5”. The apparatus includes a cylindrical copper mold, which isrot...

  9. A curious spacetime entirely free of centrifugal acceleration

    CERN Document Server

    Dadhich, Naresh


    In the Einstein gravity, besides the usual gravitational and centrifugal potential there is an additional attractive term that couples these two together. It is fun to enquire whether the latter could fully counteract the centrifugal repulsion everywhere making the spacetime completely free of the centrifugal acceleration. We present here such a curious spacetime metric and it produces a global monopole like stresses going as $~1/r^2$ in an AdS spacetime.

  10. Design and Prototyping of Micro Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Shimpei Mizuki; Gaku Minorikawa; Toshiyuki Hirano; Yuichiro Asaga; Naoki Yamaguchi; Yutaka Ohta; Eisuke Outa


    In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity. The conventional 1D prediction method, CFD and the inverse design were attempted. The prototyped compressor was driven by using a turbocharger and the performance characteristics were measured.

  11. Rotational spectroscopy with an optical centrifuge

    CERN Document Server

    Korobenko, Aleksey; Hepburn, John W; Milner, Valery


    We demonstrate a new spectroscopic method for studying electronic transitions in molecules with extremely broad range of angular momentum. We employ an optical centrifuge to create narrow rotational wave packets in the ground electronic state of $^{16}$O$_2$. Using the technique of resonance-enhanced multi-photon ionization, we record the spectrum of multiple ro-vibrational transitions between $X^3\\Sigma_{g}^{-}$ and $C^3\\Pi_{g}$ electronic manifolds of oxygen. Direct control of rotational excitation, extending to rotational quantum numbers as high as $N\\gtrsim 120$, enables us to interpret the complex structure of rotational spectra of $C^3\\Pi_{g}$ beyond thermally accessible levels.

  12. Development of liquid nitrogen Centrifugal Pump

    Energy Technology Data Exchange (ETDEWEB)

    Abe, M; Sagiyama, R; Tsuchiya, H [Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Takayama, T [Institute for Molecular Science, National Institutes of Natural Sciences, 38 Nishigo-Naka, Myodaiji, Okazaki, Aichi 444-8585 (Japan); Torii, Y [OMNIX, 1-15-3 Nishishinjuku, Shinjuku, Tokyo, 160-0023 (Japan); Nakamura, M [YN Nakamura Ltd, 3-9-25 Ohjima, Koto, Tokyo, 136-0072 (Japan); Hoshino, Y [JECC TORISHA Co. Ltd, 2-8-52 Yoshinodai, Kawagoe-shi, Saitama, 350-0833 (Japan); Odashima, Y [Department of Basic Sciences, University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902 (Japan)], E-mail:


    Usually liquid nitrogen (LN{sub 2}) transfer from a container to a laboratory equipment takes place by applying pressure to the container to push out liquid or pouring liquid into the cryostat directly by lifting the container. In order to overcome inconvenience of pressuring or lifting containers, we have been developing the Liquid Nitrogen Centrifugal Pump of a small electric turbine pump. Significant advantages that both reducing time to fill LN{sub 2}and controlling the flow rate of liquid into the cryostat are obtained by introducing this pump. We have achieved the lift of about 800mm with the vessel's opening diameter of 28mm.

  13. Experimental Research on Desulfurization of Fine Coal Using an Enhanced Centrifugal Gravity Separator

    Institute of Scientific and Technical Information of China (English)

    TAO You-jun; LUO Zhen-fu; ZHAO Yue-min; TAO Daniel


    A desulphurization experimental study under the effects of compounding physical force fields has been described for < 0.5 mm fine particles of high sulfur coal. A statistical test using the Box-Behnken Design of experiments was conducted to evaluate the effects of individual operating variables and their interactions on desulfurization of fine coal using an enhanced centrifugal gravity separator. A model describing the relation between desulphurization efficiency of pyrite sulfur and different operating variables has been designed. The interactions between different factors on the pyrite sulfur desulphurization efficiency have been analysed. The optimal test conditions for desulfarization are extracted from the Design-Expert 6.0 software. Finally, the advantage of centrifugal gravity separation for fine coal is pointed out.

  14. Design and Analysis of a Novel Centrifugal Braking Device for a Mechanical Antilock Braking System. (United States)

    Yang, Cheng-Ping; Yang, Ming-Shien; Liu, Tyng


    A new concept for a mechanical antilock braking system (ABS) with a centrifugal braking device (CBD), termed a centrifugal ABS (C-ABS), is presented and developed in this paper. This new CBD functions as a brake in which the output braking torque adjusts itself depending on the speed of the output rotation. First, the structure and mechanical models of the entire braking system are introduced and established. Second, a numerical computer program for simulating the operation of the system is developed. The characteristics of the system can be easily identified and can be designed with better performance by using this program to studying the effects of different design parameters. Finally, the difference in the braking performance between the C-ABS and the braking system with or without a traditional ABS is discussed. The simulation results indicate that the C-ABS can prevent the wheel from locking even if excessive operating force is provided while still maintaining acceptable braking performance.

  15. Low speed centrifugal casting of Functionally Graded solid cast ingot by anomalous particle distribution (United States)

    Mer, K. K. S.; Ray, S.


    Functionally graded cylindrical ingot of Al-Al2O3 composite synthesized by centrifugal casting shows particle distribution and hardness decreasing radially from the outer radius to inner radius. The progressive decrease in alumina content and hardness from the outer radius towards the center may be attributed to higher centrifugal force acting on relatively denser alumina particles during rotation, as compared to that acting on lighter alloy melt. It is also observed, as one moves down from the top to the bottom of cast ingot the alumina content decreases. This is surprising in view of higher density of alumina particles relative to the melt. The particle settling should have resulted at more particles towards the bottom, but distribution observed is in contradiction.

  16. Inference of optimal speed for sound centrifugal casting of Al-12Si alloys (United States)

    Agari, Shailesh Rao; Mukunda, P. G.; Rao, Shrikantha S.; Sudhakar, K. G.


    True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.

  17. Separative power of an optimised concurrent gas centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Bogovalov, Sergey; Boman, Vladimir [National Research Nuclear University (MEPHI), Moscow (Russian Federation)


    The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to δU = 12.7 (V/700 m/s)2(300 K/T)(L/1 m) kg·SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

  18. [Design and optimization of a centrifugal pump for CPCR]. (United States)

    Pei, J; Tan, X; Chen, K; Li, X


    Requirements for an optimal centrifugal pump, the vital component in the equipment for cardiopulmonary cerebral resuscitation(CPCR), have been presented. The performance of the Sarns centrifugal pump (Sarns, Inc./3M, Ann arbor, MI, U.S.A) was tested. The preliminarily optimized model for CPCR was designed according to the requirements of CPCR and to the comparison and analysis of several clinically available centrifugal pumps. The preliminary tests using the centrifugal pump made in our laboratory(Type CPCR-I) have confirmed the design and the optimization.

  19. Separative Power of an Optimised Concurrent Gas Centrifuge

    Directory of Open Access Journals (Sweden)

    Sergey Bogovalov


    Full Text Available The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to δU = 12.7 (V/700 m/s2(300 K/T(L/1 m kg·SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

  20. Technical Note: The use of an interrupted-flow centrifugation method to characterise preferential flow in low permeability media

    Directory of Open Access Journals (Sweden)

    R. A. Crane


    Full Text Available We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge induced flow, no flow and centrifuge induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force level. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite clay dominated core samples. All samples exhibited a non-Fickian tracer breakthrough (early tracer arrival, combined with a decrease in tracer concentration immediately after each period of interrupted-flow. This is indicative of dual (or multi porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s and the low hydraulic conductivity domain during interrupted-flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash–Sutcliffe model efficiency coefficient was >0.97 for all samples. In combination interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.

  1. Fabrication of tubular tissue constructs by centrifugal casting of cells suspended in an in situ crosslinkable hyaluronan-gelatin hydrogel. (United States)

    Mironov, Vladimir; Kasyanov, Vladimir; Zheng Shu, Xiao; Eisenberg, Carol; Eisenberg, Leonard; Gonda, Steve; Trusk, Thomas; Markwald, Roger R; Prestwich, Glenn D


    Achieving the optimal cell density and desired cell distribution in scaffolds is a major goal of cell seeding technologies in tissue engineering. In order to reach this goal, a novel centrifugal casting technology was developed using in situ crosslinkable hyaluronan-based (HA) synthetic extracellular matrix (sECM). Living cells were suspended in a viscous solution of thiol-modified HA and thiol-modified gelatin, a polyethyleneglycol diacrylate crosslinker was added, and a hydrogel was formed during rotation. The tubular tissue constructs consisting of a densely packed cell layer were fabricated with the rotation device operating at 2000 rpm for 10 min. The majority of cells suspended in the HA mixture before rotation were located inside the layer after centrifugal casting. Cells survived the effect of the centrifugal forces experienced under the rotational regime employed. The volume cell density (65.6%) approached the maximal possible volume density based on theoretical sphere packing models. Thus, centrifugal casting allows the fabrication of tubular constructs with the desired redistribution, composition and thickness of cell layers that makes the maximum efficient use of available cells. Centrifugal casting in this sECM would enable rapid fabrication of tissue-engineered vascular grafts, as well as other tubular and planar tissue-engineered constructs.

  2. Stress Analysis of the Centrifugal Pump Pipe%离心泵管道应力浅析

    Institute of Scientific and Technical Information of China (English)



    结合离心泵管口受力要求及应力分析原则,分析与探讨如何建立离心泵管道应力计算模型,涉及泵的模拟、管道计算温度的选取、泵与储罐之间的柔性连接,以及泵管口受力和力矩的控制途径等。%Combine the force requirements and stress principles of the centrifugal pump pipe nozzle ,analyze and discuss how to establish the stress calculation model of the centrifugal pump ,w hich including the pump simulation ,pipe calculated temperature option , flexible connection between the pump and tank ,and control ways for pump pipe nozzle force and moment of force .

  3. Postcardiotomy centrifugal assist: a single surgeon's experience. (United States)

    Curtis, Jack J; McKenney-Knox, Charlotte A; Wagner-Mann, Colette C


    Because of the infrequent application of cardiac assist devices for postcardiotomy heart failure, most published reports include the results of learning curves from multiple surgeons. Between October 1986 and June 2001, a single surgeon used 35 Sarns Centrifugal Pumps as ventricular assist devices in 21 patients with severe hemodynamic compromise after open heart surgery (0.88% incidence). Patients' ages ranged from 39 to 77 (mean, 59.6 years). Three patients required right ventricular assist devices, 4 left ventricular assist devices, and 14 had biventricular assist devices. For all, the indication for application was inability to wean from cardiopulmonary bypass despite multiple inotropes and intraaortic balloon pumping. All were expected to be intraoperative deaths without further mechanical assistance. Patients were assisted from 2 to 434 h (median, 48 h). Fifteen patients (71.4%) were weaned from device(s), and 11 patients (52.4%) were hospital survivors. Actuarial survival in those dismissed from the hospital was 78% at 5 years and 39% at 10 years. Patients facing certain demise after cardiac surgery can be salvaged with temporary centrifugal mechanical assist. Results are competitive with that achieved with more sophisticated devices. Hospital survivors enjoy reasonable longevity.

  4. Some aversive characteristics of centrifugally generated gravity. (United States)

    Altman, F.


    The effective weight of rats was manipulated by centrifugation. Two effective weight levels were obtained. In three escape avoidance conditions a lever press produced a change from a base level of 2.1 g to a response level of 1.1 g. In a punishment condition a response produced a change from a 1.1 g level to a 2.1 g level and in an extinction condition responses had no effect on the 2.1 g effective weight level present. All changes took 30 sec and were maintained for an additional 10 sec before a return to base level was initiated. When responses occurred closer together than the 40 sec, they delayed the return to base level by 40 sec. This 40 sec interval is referred to as response-contingent-time. The response rate and amount of response-contingent-time served as the data. The results confirmed previous data that centrifugation is aversive. The results are interpreted as indicating that the aversiveness is attributable to the increase in effective weight, and that rats can discriminate the different angular velocity-radius of rotation combinations used.

  5. Centrifugally Stimulated Exospheric Ion Escape at Mercury (United States)

    Delcourt, Dominique; Seki, K.; Terada, N.; Moore, Thomas E.


    We investigate the transport of ions in the low-altitude magnetosphere magnetosphere of Mercury. We show that, because of small spatial scales, the centrifugal effect due to curvature of the E B drift paths can lead to significant particle energization in the parallel direction. We demonstrate that because of this effect, ions with initial speed smaller than the escape speed such as those produced via thermal desorption can overcome gravity and escape into the magnetosphere. The escape route of this low-energy exosphere originating material is largely controlled by the magnetospheric convection rate. This escape route spreads over a narrower range of altitudes when the convection rate increases. Bulk transport of low-energy planetary material thus occurs within a limited region of space once moderate magnetospheric convection is established. These results suggest that, via release of material otherwise gravitationally trapped, the E B related centrifugal acceleration is an important mechanism for the net supply of plasma to the magnetosphere of Mercury.


    Institute of Scientific and Technical Information of China (English)

    Yu Sirong; Zhang Xinping; He Zhenming; Liu Yaohui


    Based on continuum theory and moving law of particles, a model is presented to obtain gradient distribution of particles in centrifugal accelerating field, by which the particle distribution in gradient composite material can be predicted. The simulation shows with increases in rotating time, four regions gradually appear from the internal periphery to the external one, they are free region, transition region, steady region and surface reinforced region,and the latest three regions are defined as a rich region. Finally, the steady region disappears, and the rich region only includes transition region and surface reinforced region. The influences of centrifugal acceleration coefficient G,primary volume fraction (0,pouring temperature (p and density difference between the particle and the metal matrix on particles gradient distribution are studied in detail. The results of the theoretical analysis agree with experiment ones. Both of analysis and experiment results indicate that with the increase in G and (p, the particle distribution becomes more centralized and the consistence of particle in the surface periphery becomes larger.

  7. Liquid Metering Centrifuge Sticks (LMCS): A Centrifugal Approach to Metering Known Sample Volumes for Colorimetric Solid Phase Extraction (C-SPE) (United States)

    Gazda, Daniel B.; Schultz, John R.; Clarke, Mark S.


    Phase separation is one of the most significant obstacles encountered during the development of analytical methods for water quality monitoring in spacecraft environments. Removing air bubbles from water samples prior to analysis is a routine task on earth; however, in the absence of gravity, this routine task becomes extremely difficult. This paper details the development and initial ground testing of liquid metering centrifuge sticks (LMCS), devices designed to collect and meter a known volume of bubble-free water in microgravity. The LMCS uses centrifugal force to eliminate entrapped air and reproducibly meter liquid sample volumes for analysis with Colorimetric Solid Phase Extraction (C-SPE). C-SPE is a sorption-spectrophotometric platform that is being developed as a potential spacecraft water quality monitoring system. C-SPE utilizes solid phase extraction membranes impregnated with analyte-specific colorimetric reagents to concentrate and complex target analytes in spacecraft water samples. The mass of analyte extracted from the water sample is determined using diffuse reflectance (DR) data collected from the membrane surface and an analyte-specific calibration curve. The analyte concentration can then be calculated from the mass of extracted analyte and the volume of the sample analyzed. Previous flight experiments conducted in microgravity conditions aboard the NASA KC-135 aircraft demonstrated that the inability to collect and meter a known volume of water using a syringe was a limiting factor in the accuracy of C-SPE measurements. Herein, results obtained from ground based C-SPE experiments using ionic silver as a test analyte and either the LMCS or syringes for sample metering are compared to evaluate the performance of the LMCS. These results indicate very good agreement between the two sample metering methods and clearly illustrate the potential of utilizing centrifugal forces to achieve phase separation and metering of water samples in microgravity.

  8. High Efficiency Centrifugal Compressor for Rotorcraft Applications (United States)

    Medic, Gorazd; Sharma, Om P.; Jongwook, Joo; Hardin, Larry W.; McCormick, Duane C.; Cousins, William T.; Lurie, Elizabeth A.; Shabbir, Aamir; Holley, Brian M.; Van Slooten, Paul R.


    The report "High Efficiency Centrifugal Compressor for Rotorcraft Applications" documents the work conducted at UTRC under the NRA Contract NNC08CB03C, with cost share 2/3 NASA, and 1/3 UTRC, that has been extended to 4.5 years. The purpose of this effort was to identify key technical barriers to advancing the state-of-the-art of small centrifugal compressor stages; to delineate the measurements required to provide insight into the flow physics of the technical barriers; to design, fabricate, install, and test a state-of-the-art research compressor that is representative of the rear stage of an axial-centrifugal aero-engine; and to acquire detailed aerodynamic performance and research quality data to clarify flow physics and to establish detailed data sets for future application. The design activity centered on meeting the goal set outlined in the NASA solicitation-the design target was to increase efficiency at higher work factor, while also reducing the maximum diameter of the stage. To fit within the existing Small Engine Components Test Facility at NASA Glenn Research Center (GRC) and to facilitate component re-use, certain key design parameters were fixed by UTRC, including impeller tip diameter, impeller rotational speed, and impeller inlet hub and shroud radii. This report describes the design effort of the High Efficiency Centrifugal Compressor stage (HECC) and delineation of measurements, fabrication of the compressor, and the initial tests that were performed. A new High-Efficiency Centrifugal Compressor stage with a very challenging reduction in radius ratio was successfully designed, fabricated and installed at GRC. The testing was successful, with no mechanical problems and the running clearances were achieved without impeller rubs. Overall, measured pressure ratio of 4.68, work factor of 0.81, and at design exit corrected flow rate of 3 lbm/s met the target requirements. Polytropic efficiency of 85.5 percent and stall margin of 7.5 percent were

  9. Separative power of an optimised concurrent gas centrifuge

    CERN Document Server

    Bogovalov, S V


    The problem of separation of uranium isotopes in a concurrent gas centrifuge is solved analytically. Separative power of the optimized concurrent gas centrifuges equals to $\\delta U=12.7(V/700~{\\rm m/s})^2 (300 ~{\\rm K}/T)L, ~{\\rm kg ~SWU/yr}$, where $L$ and $V$ are the length and linear velocity of the rotor of the gas centrifuge, $T$ is the temperature. This formula well agrees with an empirical separative power of counter current gas centrifuges. The optimal value of the separative power is not unique on the plane $(p_w,v_z)$, where $p_w$ is pressure at the wall of the rotor and $v_z$ is axial velocity of the gas. This value is constant on a line defined by the equation $p_wv_z=constant$. Equations defining the mass flux and the electric power necessary to support the rotation of the gas centrifuge are obtained.

  10. [Hemodynamic analysis of a centrifugal blood pump]. (United States)

    Wang, Yang; Yang, Ming; Xu, Zihao; Zhuang, Xiaoqi; Li, Qilei; Xu, Liang


    This paper built the mathematical model of a centrifugal blood pump, which was designed by ourselves, combined it with that of the human cardiovascular system and simulated the coupling system using Matlab. Then we set up the experiment platform, linked the blood pump to mock human cardiovascular system in case of three-stage heart failure, and measured aortic pressure and flow under different speed. The comparison between experiment results and simulation results not only indicates the coupling model is correct and the blood pump works well, but also shows that with the increase of blood pump speed, the pulsation of aortic pressure and flow will be reduced, this situation will affect the structure and function of blood vessels.

  11. Centrifugal acceleration of plasma in pulsar magnetosphere

    Indian Academy of Sciences (India)

    R T Gangadhara; V Krishna


    We present a relativistic model for the centrifugal acceleration of plasma bunches and the coherent radio emission in pulsar magnetosphere. We find that rotation broadens the width of leading component compared to the width of trailing component. We explain this difference in the component widths using the nested cone emission geometry. We estimate the effect of pulsar spin on the Stokes parameters, and find that the inclination between the rotation and magnetic axes can introduce an asymmetry in the circular polarization of the conal components. We analyse the single pulse polarization data of PSR B0329+54 at 606 MHz, and find that in its conal components, one sense of circular polarization dominates in the leading component while the other sense dominates in the trailing component. Our simulation shows that changing the sign of the impact parameter changes the sense of circular polarization as well as the swing of polarization angle.

  12. Numerical simulation of centrifugal casting of pipes (United States)

    Kaschnitz, E.


    A numerical simulation model for the horizontal centrifugal pipe casting process was developed with the commercial simulation package Flow3D. It considers - additionally to mass, energy and momentum conservation equations and free surface tracking - the fast radial and slower horizontal movement of the mold. The iron inflow is not steady state but time dependent. Of special importance is the friction between the liquid and the mold in connection with the viscosity and turbulence of the iron. Experiments with the mold at controlled revolution speeds were carried out using a high-speed camera. From these experiments friction coefficients for the description of the interaction between mold and melt were obtained. With the simulation model, the influence of typical process parameters (e.g. melts inflow, mold movement, melt temperature, cooling media) on the wall thickness of the pipes can be studied. The comparison to results of pipes from production shows a good agreement between simulation and reality.


    Energy Technology Data Exchange (ETDEWEB)

    Peralta, J.; López-Valverde, M. A. [Instituto de Astrofísica de Andalucía (CSIC), Glorieta de la Astronomía, 18008 Granada (Spain); Imamura, T. [Institute of Space and Astronautical Science-Japan Aerospace Exploration Agency 3-1-1, Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Read, P. L. [Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford (United Kingdom); Luz, D. [Centro de Astronomia e Astrofísica da Universidade de Lisboa (CAAUL), Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa (Portugal); Piccialli, A., E-mail: [LATMOS, UVSQ, 11 bd dAlembert, 78280 Guyancourt (France)


    This paper is the second in a two-part study devoted to developing tools for a systematic classification of the wide variety of atmospheric waves expected on slowly rotating planets with atmospheric superrotation. Starting with the primitive equations for a cyclostrophic regime, we have deduced the analytical solution for the possible waves, simultaneously including the effect of the metric terms for the centrifugal force and the meridional shear of the background wind. In those cases where the conditions for the method of the multiple scales in height are met, these wave solutions are also valid when vertical shear of the background wind is present. A total of six types of waves have been found and their properties were characterized in terms of the corresponding dispersion relations and wave structures. In this second part, we study the waves' solutions when several atmospheric approximations are applied: Lamb, surface, and centrifugal waves. Lamb and surface waves are found to be quite similar to those in a geostrophic regime. By contrast, centrifugal waves turn out to be a special case of Rossby waves that arise in atmospheres in cyclostrophic balance. Finally, we use our results to identify the nature of the waves behind atmospheric periodicities found in polar and lower latitudes of Venus's atmosphere.

  14. Numerical analysis and centrifugal modeling of LNAPLs transport in subsurface system

    Institute of Scientific and Technical Information of China (English)


    The transport of non-aqueous phase liquids (NAPLs) in unsaturated soils and groundwater is an important research topic in geo-environmental engineering. In this paper, the mechanism of light NAPLs (LNAPLs) transport in subsurface system is briefly introduced, and the mass transport equations, fluid flow equations, and the constitutive model of relative permeability - saturation - capillary pressure are discussed. Then the numerical method is introduced to simulate the multiphase flow problems in porous media, and the tempospatial distribution of LNAPLs is obtained. Moreover, different boundary conditions are employed in numerical simulation to investigate its effect on transport behavior. To verify the numerical data, centrifugal tests are conducted to model the LNAPLs migration in unsaturated soils and groundwater. The calculation results are agreeable with the experimental findings of centrifugal modeling, which indicates that LNAPLs from leaking point move downwards due to gravity force, and form a high concentration zone above the capillary fringe, and then spread out laterally along the groundwater table. Some LNAPL enters groundwater system to further migrate. The combination of numerical simulation and centrifuge modeling can be a useful means to study the transport behavior of LNAPLs in subsurface system.

  15. Fabrication of highly aligned fibrous scaffolds for tissue regeneration by centrifugal spinning technology

    Energy Technology Data Exchange (ETDEWEB)

    Loordhuswamy, Amalorpava Mary [Department of Textile Technology, Anna University, Chennai 600025 (India); Krishnaswamy, Venkat Raghavan; Korrapati, Purna Sai [Department of Biomaterials, CSIR-Central Leather Research Institute, Chennai 600020 (India); Thinakaran, Senthilram [Department of Textile Technology, Anna University, Chennai 600025 (India); Rengaswami, Giri Dev Venkateshwarapuram, E-mail: [Department of Textile Technology, Anna University, Chennai 600025 (India)


    Centrifugal spinning (C-Spin) is an emerging technology which uses centrifugal force to produce ultrafine fibers. Being a voltage free technique it can overcome the limitations of electrospinning. Owing to the unique characteristic features such as high surface area to volume ratio, porosity, mechanical strength and fiber alignment, centrifugal spun (C-spun) fibrous mat has a wide range of scope in various biomedical applications. Higher degree of fiber alignment can be effortlessly achieved by the C-Spin process. In order to prove the versatility of C-Spin system with respect to fiber alignment, Polycaprolactone (PCL) and gelatin were spun taking them as model polymers. The morphological analysis revealed that highly aligned ultrafine fibers with smooth surface are achieved by C-Spinning. Hydrophilicity, porosity and mechanical property results confirm that the C-spun mat is more suitable for tissue engineering applications. In vitro and in vivo experiments proved that the scaffolds are biocompatible and can be efficiently used as a wound dressing material. - Highlights: • Highly aligned PCL/gelatin fibrous scaffolds were prepared by C-Spinning system. • Degree of fiber alignment was influenced by the proportion of gelatin in the blends. • Direction of cell growth was parallel to the direction of fiber alignment. • C-Spun matrices can efficiently accelerate faster wound healing.

  16. Fabrication of highly aligned fibrous scaffolds for tissue regeneration by centrifugal spinning technology. (United States)

    Loordhuswamy, Amalorpava Mary; Krishnaswamy, Venkat Raghavan; Korrapati, Purna Sai; Thinakaran, Senthilram; Rengaswami, Giri Dev Venkateshwarapuram


    Centrifugal spinning (C-Spin) is an emerging technology which uses centrifugal force to produce ultrafine fibers. Being a voltage free technique it can overcome the limitations of electrospinning. Owing to the unique characteristic features such as high surface area to volume ratio, porosity, mechanical strength and fiber alignment, centrifugal spun (C-spun) fibrous mat has a wide range of scope in various biomedical applications. Higher degree of fiber alignment can be effortlessly achieved by the C-Spin process. In order to prove the versatility of C-Spin system with respect to fiber alignment, Polycaprolactone (PCL) and gelatin were spun taking them as model polymers. The morphological analysis revealed that highly aligned ultrafine fibers with smooth surface are achieved by C-Spinning. Hydrophilicity, porosity and mechanical property results confirm that the C-spun mat is more suitable for tissue engineering applications. In vitro and in vivo experiments proved that the scaffolds are biocompatible and can be efficiently used as a wound dressing material.


    Institute of Scientific and Technical Information of China (English)

    LI Ya-lin; YUAN Shou-qi; TANG Yue; YUAN Jian-ping


    The Basset-Boussinesq-Oseen (BBO) equation can be used for most flows to trace the motion of a particle,but in a centrifugal pump,among the forces that act on the particles,one should also include those due to the impeller rotation,as additional effects.This paper firstly reviews various approximations of the BBO equation for the motion of dispersion particles in a viscous fluid.Then based on the motion equation for particles in low Reynolds number centrifugal pumps,a formula for calculating the tracking characteristics of tracer particles is deduced through the Fourier integral transformation.After that the deviations of the particle motion from the fluid motion,as predicted by the various approximations,are discussed and compared.At last,with an emphasis on the Particle Image Velocimetry (PIV) results,the tracking characteristics of particles are estimated.Also,advantages and disadvantages of different tracer particles are discussed and suitable tracer particles for application in PIV studies for flow fields in centrifugal pumps are suggested.

  18. Task 9 -- Centrifugal membrane filtration. Semi-annual report, April 1--September 30, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Stepan, D.J.; Grafsgaard, M.E.


    This project is designed to establish the utility of a novel centrifugal membrane filtration technology for the remediation of liquid mixed waste streams at US Department of Energy (DOE) facilities in support of the DOE Environmental Management (EM) program. The Energy and Environmental Research Center (EERC) has teamed with SpinTek Membrane Systems, Inc., a small business and owner of the novel centrifugal membrane filtration technology, to establish the applicability of the technology to DOE site remediation and the commercial viability of the technology for liquid mixed waste stream remediation. The technology is a uniquely configured process that makes use of ultrafiltration and centrifugal force to separate suspended and dissolved solids from liquid waste streams, producing a filtered water stream and a low-volume contaminated concentrate stream. This technology has the potential for effective and efficient waste volume minimization, the treatment of liquid tank wastes, the remediation of contaminated groundwater plumes, and the treatment of secondary liquid waste streams from other remediation processes, as well as the liquid waste stream generated during decontamination and decommissioning activities.

  19. A novel, compact disk-like centrifugal microfluidics system for cell lysis and sample homogenization. (United States)

    Kido, Horacio; Micic, Miodrag; Smith, David; Zoval, Jim; Norton, Jim; Madou, Marc


    In this paper, we present the design and characterization of a novel platform for mechanical cell lysis of even the most difficult to lyse cell types on a micro or nanoscale (maximum 70 microL total volume). The system incorporates a machined plastic circular disk assembly, magnetic field actuated microfluidics, centrifugal cells and tissue homogenizer and centrifugation system. The mechanism of tissue disruption of this novel cell homogenization apparatus derives from the relative motion of ferromagnetic metal disks and grinding matrices in a liquid medium within individual chambers of the disk in the presence of an oscillating magnetic field. The oscillation of the ferromagnetic disks or blades produces mechanical impaction and shear forces capable of disrupting cells within the chamber both by direct action of the blade and by the motion of the surrounding lysis matrix, and by motion induced vortexing of buffer fluid. Glass beads or other grinding media are integrated into each lysis chamber within the disk to enhance the transfer of energy from the oscillating metal blade to the cells. The system also achieves the centrifugal elimination of solids from each liquid sample and allows the elution of clarified supernatants via siphoning into a collection chamber fabricated into the plastic disk assembly. This article describes system design, implementation and validation of proof of concept on two samples--Escherichia coli and Saccharomyces cerevisiae representing model systems for cells that are easy and difficult to lyse, respectively.

  20. A straight path centrifugal blood pump concept in the Capiox centrifugal pump. (United States)

    Kijima, T; Oshiyama, H; Horiuchi, K; Nogawa, A; Hamasaki, H; Amano, N; Nojiri, C; Fukasawa, H; Akutsu, T


    This article describes comparative studies of a newly developed "straight path" centrifugal pump (Capiox centrifugal pump) targeted for open-heart surgery and circulatory support. A unique straight path design of the rotor was very effective in reducing the pump's rotational speed and prime volume. This pump was evaluated for hydraulics, hemolysis, depriming characteristics, cavitation, and heat generation. Two commercially available centrifugal pumps, the Biomedicus cone-type pump and the Sarns 3M impeller-type pump, were used as controls. The new pump required the lowest pump speed to produce the same flow rates under the same pressure loads and demonstrated the lowest hemolysis and the lowest temperature rise with the outlet clamped. The air volume required to deprime the new pump was one-third to one-half that for the other pumps, and no sign of cavitation was observed even if a small amount of air was introduced to the pump inlet under a negative pressure of 200 mm Hg.

  1. Numerical simulation of dynamic flow characteristics in a centrifugal water pump with three-vaned diffuser

    Directory of Open Access Journals (Sweden)

    Zhi-Jun Shuai


    Full Text Available The complex three-dimensional turbulent flow field in a centrifugal water pump with three asymmetrical diffusers was numerically simulated. The characteristics of pressure and force fluctuations inside the model pump were investigated. Fast Fourier transformation was performed to obtain the spectra of pressure and force fluctuations. It indicates that the dominant frequency of pressure fluctuations is the blade passing frequency in all the sub-domains inside the pump and the first blade passing frequency energy (first order of blade passing frequency is the most significant. The dominant frequency of pressure fluctuations at the location of diffuser outlet is featured by low frequency (less than 1 Hz, which may be due to the locally generated eddy structures. Besides, the dominant frequency force fluctuations on the impeller blades are also the blade passing frequency. The existence of the three asymmetrical diffusers has damping effect on the pressure fluctuation amplitude and energy amplitude of pressure fluctuations in the diffuser domain dramatically, which indicates that the diffusers can effectively control the hydraulically excited vibration in the pump. Besides, the prediction of the dominant frequency of pressure fluctuations inside the pump can help to utilize the pump effectively and to extend the pump life. The main findings of this work can provide prediction of the pump performance and information for further optimal design of centrifugal pumps as well.

  2. Influence of flow patterns on chromatographic efficiency in centrifugal partition chromatography. (United States)

    Marchal, L; Foucaul, A; Patissier, G; Rosant, J M; Legrand, J


    Visualization of flow patterns in centrifugal partition chromatography (CPC) was performed with an asynchronous camera and a stroboscope triggered by the CPC rotor, allowing a channel to be selected and observed regardless of rotational speed. Three main types of flow states were noted as a function of rotational speed and flow-rate: jets stuck along channel walls, broken jets and atomization. Our observations emphasize the importance of Coriolis force on flow shape. Chromatographic efficiency was related to the dispersion of the mobile phase in the stationary phase.

  3. High-Throughput DNA Array for SNP Detection of KRAS Gene Using a Centrifugal Microfluidic Device. (United States)

    Sedighi, Abootaleb; Li, Paul C H


    Here, we describe detection of single nucleotide polymorphism (SNP) in genomic DNA samples using a NanoBioArray (NBA) chip. Fast DNA hybridization is achieved in the chip when target DNAs are introduced to the surface-arrayed probes using centrifugal force. Gold nanoparticles (AuNPs) are used to assist SNP detection at room temperature. The parallel setting of sample introduction in the spiral channels of the NBA chip enables multiple analyses on many samples, resulting in a technique appropriate for high-throughput SNP detection. The experimental procedure, including chip fabrication, probe array printing, DNA amplification, hybridization, signal detection, and data analysis, is described in detail.

  4. The American Gas Centrifuge Past, Present, and Future

    Energy Technology Data Exchange (ETDEWEB)

    Waters, Dean


    The art of gas centrifugation was born in 1935 at the University of Virginia when Dr. Jesse Beams demonstrated experimentally the separation of chlorine isotopes using an ultra-high speed centrifuge. Dr. Beam’s experiment initiated work that created a rich history of scientific and engineering accomplishment in the United States in the art of isotope separation and even large scale biological separation by centrifugation. The early history of the gas centrifuge development was captured in a lecture and documented by Dr. Jesse Beams in 1975. Much of Dr. Beams lecture material is used in this paper up to the year 1960. Following work by Dr. Gernot Zippe at the University of Virginia between 1958 and 1960, the US government embarked on a centrifuge development program that ultimately led to the start of construction of the Gas Centrifuge Enrichment Plant in Piketon Ohio in the late 1970’s. The government program was abandoned in 1985 after investing in the construction of two of six planned process buildings, a complete supply chain for process and centrifuge parts, and the successful manufacture and brief operation of an initial complement of production machines that would have met 15 percent of the planned capacity of the constructed process buildings. A declining market for enriched uranium, a glut of uranium enrichment capacity worldwide, and the promise of a new laser based separation process factored in the decision to stop the government program. By the late 1990’s it had become evident that gas centrifugation held the best promise to produce enriched uranium at low cost. In1999, the United States Enrichment Corporation undertook an initiative to revive the best of the American centrifuge technology that had been abandoned fourteen years earlier. This is an exciting story and one that when complete will enable the United States to maintain its domestic supply and to be highly competitive in the world market for this important energy commodity. (auth)

  5. Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation

    KAUST Repository

    Akbulut, Ozge


    This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge. © 2012 American Chemical Society.

  6. Influence of G-forces on venous and nervous systems (United States)

    Dyskin, Y. A.; Prives-Bardina, R. A.; Tikhonova, L. P.


    Cats and rabbits were subjected to rotation in the centrifuge. Controls were maintained to determine the individual tolerance to g-forces. Thickening of the vascular wall was found to occur due to the g-forces' effect, as well as other vascular changes. Nervous changes included edema and chromatolysis of the nerve cells.

  7. Influence of milk centrifugation, brining and ripening conditions in preventing gas formation by Clostridium spp. in Gouda cheese. (United States)

    Su, Y C; Ingham, S C


    This study examined milk centrifugation, increased salt concentration, and low ripening temperature as potential strategies to prevent late blowing caused by gas-forming Clostridium spp. in Gouda cheese. The survival of clostridia spores in cheese brine and their ability to enter Gouda cheese during brining was also evaluated. Centrifugation (3000 x g for 30 s) of contaminated milk resulted in > 60% spore reduction, with increased spore reduction at greater centrifugal forces. Low levels of C. tyrobutyricum and C. sporogenes spores survived in saturated (23%, w/v) brine with 2% (v/v) added whey at 15 degrees C for 63 days, while C. beijerinckii and C. butyricum spores were not detectable on days 4 and 35, respectively. Spores of C. tyrobutyricum in brine infiltrated Gouda cheese during 2 h of brining at 13 degrees C resulted in production of small gas holes during ripening. In Gouda cheese slurry stored at 13 degrees C, three C. tyrobutyricum strains plus one of three C. sporogenes strains germinated in the slurry with no added salt. Of three C. tyrobutyricum strains stored at 13 degrees C in slurries with higher water-phase salt concentrations of 2.4 and 3.6%, two strains and one strain germinated, respectively. No germination of spores was detected in any cheese slurry stored at 5 or 8 degrees C. Milk centrifugation, increased percent water-phase salt, absence of spores in brine, and decreased ripening temperature are all potentially important measures against gas production by Clostridium spp. in Gouda cheese.

  8. Failure analysis of a polymer centrifugal impeller

    Directory of Open Access Journals (Sweden)

    Nikhil K. Kar


    Full Text Available A failure analysis investigation was performed on a fractured polymer impeller used in a respiratory blower. Light microscopy, scanning electron microscopy and finite element analysis techniques were utilized to characterize the mode(s of failure and fracture surfaces. A radial split down the impeller center was observed with symmetric fracture faces about the impeller bore. Fractographic analysis revealed brittle fracture features including Wallner lines, mirror, mist and hackle features stemming from the impeller bore, emanating radially outward. Crazed fibrils and faint fatigue striations suggest that intermittent load cycling led to initiation, and rapid propagation of multiple crack fronts originating along the impeller lip. Finite element analysis revealed a flexural condition induces localized stresses along the impeller lip. Significant wear features were also observed within the impeller bore, which may have contributed to premature failure of the impeller. The brittle fracture morphology and defects within the impeller bore suggest that premature failure occurred because of multiple interacting factors including: intermittently high centrifugal velocities, imbalance bore and shaft conditions, defects within the bore caused by machining, and stress concentrations along the circumference of the impeller lip.

  9. Central centrifugal cicatricial alopecia: challenges and solutions

    Directory of Open Access Journals (Sweden)

    Herskovitz I


    Full Text Available Ingrid Herskovitz, Mariya Miteva Department of Dermatology and Cutaneous Surgery, University of Miami L Miller School of Medicine, Miami, FL, USA Abstract: Central centrifugal cicatricial alopecia (CCCA is the most common scarring alopecia among African American women. Data about epidemiology, etiology, genetic inheritance, and management are scarce and come from individual reports or small series. CCCA has been associated with hot combing and traumatic hair styling for years; however, studies fail to confirm it as the sole etiologic factor. It has been shown in a small series that CCCA can be inherited in an autosomal dominant fashion, with a partial penetrance and a strong modifying effect of hairstyling and sex. CCCA presents clinically as a central area of progressive irreversible hair loss that expands to the periphery. A patchy form has also been described. Dermoscopy is helpful to identify the optimal site for the biopsy, which establishes the diagnosis. Well-designed randomized controlled trials are needed to discover the optimal management. At this point, patients are advised to avoid traction and chemical treatments; topical and intralesional steroids, calcineurin inhibitors, and minoxidil can be helpful in halting the progression. Keywords: hair loss, alopecia, dermatoscopy, dermoscopy, trichoscopy, black scalp, African American, scarring alopecia

  10. Central centrifugal cicatricial alopecia: challenges and solutions. (United States)

    Herskovitz, Ingrid; Miteva, Mariya


    Central centrifugal cicatricial alopecia (CCCA) is the most common scarring alopecia among African American women. Data about epidemiology, etiology, genetic inheritance, and management are scarce and come from individual reports or small series. CCCA has been associated with hot combing and traumatic hair styling for years; however, studies fail to confirm it as the sole etiologic factor. It has been shown in a small series that CCCA can be inherited in an autosomal dominant fashion, with a partial penetrance and a strong modifying effect of hairstyling and sex. CCCA presents clinically as a central area of progressive irreversible hair loss that expands to the periphery. A patchy form has also been described. Dermoscopy is helpful to identify the optimal site for the biopsy, which establishes the diagnosis. Well-designed randomized controlled trials are needed to discover the optimal management. At this point, patients are advised to avoid traction and chemical treatments; topical and intralesional steroids, calcineurin inhibitors, and minoxidil can be helpful in halting the progression.

  11. Novel design for centrifugal counter-current chromatography: VI. Ellipsoid column. (United States)

    Gu, Dongyu; Yang, Yi; Xin, Xuelei; Aisa, Haji Akber; Ito, Yoichiro


    A novel ellipsoid column was designed for centrifugal counter-current chromatography. Performance of the ellipsoid column with a capacity of 3.4 mL was examined with three different solvent systems composed of 1-butanol-acetic acid-water (4:1:5, v/v) (BAW), hexane-ethyl acetate-methanol-0.1 M HCl (1:1:1:1, v/v) (HEMH), and 12.5% (w/w) PEG1000 and 12.5% (w/w) dibasic potassium phosphate in water (PEG-DPP) each with suitable test samples. In dipeptide separation with BAW system, both stationary phase retention (Sf) and peak resolution (Rs) of the ellipsoid column were much higher at 0° column angle (column axis parallel to the centrifugal force) than at 90° column angle (column axis perpendicular to the centrifugal force), where elution with the lower phase at a low flow rate produced the best separation yielding Rs at 2.02 with 27.8% Sf at a flow rate of 0.07 ml/min. In the DNP-amino acid separation with HEMW system, the best results were obtained at a flow rate of 0.05 ml/min with 31.6% Sf yielding high Rs values at 2.16 between DNP-DL-glu and DNP-β-ala peaks and 1.81 between DNP-β-ala and DNP-L-ala peaks. In protein separation with PEG-DPP system, lysozyme and myolobin were resolved at Rs of 1.08 at a flow rate of 0.03 ml/min with 38.9% Sf. Most of those Rs values exceed those obtained from the figure-8 column under similar experimental conditions previously reported.

  12. Detection of Non-metallic Inclusions in Centrifugal Continuous Casting Steel Billets (United States)

    Wang, Qiangqiang; Zhang, Lifeng; Seetharaman, Sridhar; Yang, Shufeng; Yang, Wen; Wang, Yi


    In the current study, automated particle analysis was employed to detect non-metallic inclusions in steel during a centrifugal continuous casting process of a high-strength low alloy steel. The morphology, composition, size, area fraction, amount, and spatial distribution of inclusions in steel were obtained. Etching experiment was performed to reveal the dendrite structure of the billet and to discuss the effect of centrifugal force on the distribution of oxide inclusions in the final solidified steel by comparing the solidification velocity with the critical velocity reported in literature. It was found that the amount of inclusions was highest in samples from the tundish (~250 per mm2), followed by samples from the mold (~200 per mm2), and lowest in billet samples (~86 per mm2). In all samples, over 90 pct of the inclusions were smaller than 2μm. In steel billets, the content of oxides, dual-phase oxide-sulfides, and sulfides in inclusions were found to be 10, 30, and 60 pct, respectively. The dual-phase inclusions were oxides with sulfides precipitated on the outer surface. Oxide inclusions consisted of high Al2O3 and high MnO which were solid at the molten steel temperature, implying that the calcium treatment was insufficient. Small oxide inclusions very uniformly distributed on the cross section of the billet, while there were more sulfide inclusions showing a banded structure at the outside 25 mm layer of the billet. The calculated solidification velocity was higher than the upper limit at which inclusions were entrapped by the solidifying front, revealing that for oxide inclusions smaller than 8μm in this study, the centrifugal force had little influence on its final distribution in billets. Instead, oxide inclusions were rapidly entrapped by solidifying front.

  13. Centrifuging Step-Screw Conveyor for Regolith Project (United States)

    National Aeronautics and Space Administration — A variety of ISRU operations will utilize lunar regolith as feedstock. The proposed centrifuging step-screw conveyor concept will provide a well controlled robust,...


    Institute of Scientific and Technical Information of China (English)

    Li Jun; Liu Lijun; Feng Zhenping


    Application of the multiobjective evolutionary algorithms to the aerodynamic optimization design of a centrifugal impeller is presented. The aerodynamic performance of a centrifugal impeller is evaluated by using the three-dimensional Navier-Stokes solutions. The typical centrifugal impeller is redesigned for maximization of the pressure rise and blade load and minimization of the rotational total pressure loss at the given flow conditions. The B閦ier curves are used to parameterize the three-dimensional impeller blade shape. The present method obtains many reasonable Pareto optimal designs that outperform the original centrifugal impeller. Detailed observation of the certain Pareto optimal design demonstrates the feasibility of the present multiobjective optimization method tool for turbomachinery design.


    A demonstration of the Retech, Inc. Plasma Centrifugal Furnace (PCF) was conducted under the Superfund Innovative Technology Evaluation (SITE) Program at the Department of Energy's (DOE's) Component Development and Integration Facility in Butte, Montana. The furnace uses heat gen...

  16. Manufacture of hollow ingots using centrifugal casting machines (United States)

    Pomeshchikov, A. G.; Greneva, T. S.; Baidachenko, V. I.; Berezin, V. I.


    Centrifugal machines are proposed for the foundry created at the Almalyk Mining and Smelting Factory in order to produce hollow ingots of a liquid metal made by remelting of consumable electrodes in a refractory accumulating crucible.

  17. Fluent-based numerical simulation of flow centrifugal fan

    Institute of Scientific and Technical Information of China (English)

    LI Xian-zhang


    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.

  18. 21 CFR 862.2140 - Centrifugal chemistry analyzer for clinical use. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Centrifugal chemistry analyzer for clinical use... Instruments § 862.2140 Centrifugal chemistry analyzer for clinical use. (a) Identification. A centrifugal chemistry analyzer for clinical use is an automatic device intended to centrifugally mix a sample and...

  19. Rapid detection of simulated bacteremia by centrifugation and filtration.


    Herlich, M B; Schell, R F; Francisco, M.; Le Frock, J L


    A centrifugation-filtration procedure was developed to expedite the recovery of microorganisms from blood. Fresh whole human blood was inoculated with various aerobic and facultatively anaerobic microorganisms (3 to 18 per ml). The seeded blood was carefully overlaid on a Ficoll-Hypaque gradient (density, 1.114 g/ml) and centrifuged (400 x g) for 45 min at ambient temperature. The entire gradient (plasma, leukocytes, and Ficoll-Hypaque) was removed and filtered through a 0.22-micrometer membr...


    Institute of Scientific and Technical Information of China (English)


    The modeling of the rotor-support system of a typical centrifuge is discussed. The impedance matching method, cooperating with Riccati transfer matrix method and modal analysis method are adopted to calculate its dynamic characteristics. The influences of the main parts to the critical speeds are analyzed. Based on the analysis, a critical speed in the operating speed range is tuned successfully, and thus the dynamic characteristics of the centrifuge are much improved.

  1. Synthesis and Analytical Centrifugation of Magnetic Model Colloids


    Luigjes, B.


    This thesis is a study of the preparation and thermodynamic properties of magnetic colloids. First, two types of magnetic model colloids are investigated: composite colloids and single-domain nanoparticles. Thermodynamics of magnetic colloids is studied using analytical centrifugation, including a specially adapted centrifuge for measuring heavy and strongly light absorbing colloids. Magnetic composite colloids can be prepared from thermodynamically stable Pickering emulsions of 3-methacrylox...

  2. Design and Characterization of a Centrifugal Compressor Surge Test Rig



    A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characte...

  3. Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration. (United States)

    Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A; Kotha, Shiva P


    PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min(-1). During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.

  4. Uplifting behavior of shallow buried pipe in liquefiable soil by dynamic centrifuge test. (United States)

    Huang, Bo; Liu, Jingwen; Lin, Peng; Ling, Daosheng


    Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure.

  5. Uplifting Behavior of Shallow Buried Pipe in Liquefiable Soil by Dynamic Centrifuge Test

    Directory of Open Access Journals (Sweden)

    Bo Huang


    Full Text Available Underground pipelines are widely applied in the so-called lifeline engineerings. It shows according to seismic surveys that the damage from soil liquefaction to underground pipelines was the most serious, whose failures were mainly in the form of pipeline uplifting. In the present study, dynamic centrifuge model tests were conducted to study the uplifting behaviors of shallow-buried pipeline subjected to seismic vibration in liquefied sites. The uplifting mechanism was discussed through the responses of the pore water pressure and earth pressure around the pipeline. Additionally, the analysis of force, which the pipeline was subjected to before and during vibration, was introduced and proved to be reasonable by the comparison of the measured and the calculated results. The uplifting behavior of pipe is the combination effects of multiple forces, and is highly dependent on the excess pore pressure.

  6. Centrifuge model tests oftheformation mechanism of coarse sand debris flow

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jian; ZHOU Yun-hong; LI Ye-xun; WANG Zi-han


    Using the self-developed visualization test apparatus, centrifuge model tests at 20g were carried out to research the macro and microscopic formation mechanism of coarse sand debris flows. Theformationmodeand soil-water interaction mechanism of the debris flows were analyzed from both macroscopic and microscopic pointsof view respectively usinghigh digital imaging equipment and micro-structure analysis software Geodip. The test results indicate that the forming process of debris flow mainly consists of three stages, namely the infiltration and softening stage, theoverall slide stage,and debris flow stage. Theessenceof simulated coarse sand slope forming debris flow is that local fluidization cause slope to wholly slide. The movement of small particles forms a transient stagnantlayer with increasing saturation, causing soil shear strength lost and local fluidization. When the driving force of the saturated soil exceeds the resisting force, debris flowhappensonthecoarse sand slope immediately.

  7. On-chip preparation of calcium alginate particles based on droplet templates formed by using a centrifugal microfluidic technique. (United States)

    Liu, Mei; Sun, Xiao-Ting; Yang, Chun-Guang; Xu, Zhang-Run


    A novel chip-based approach for the fabrication of oblate spheriodal calcium alginate particles was developed by combining the droplet template method and the centrifugal microfluidic strategy. Circular chips with multiple radial channels were designed. Sodium alginate solutions in radial channels were flung into CaCl2 solutions in the form of droplets under centrifugal force, and the droplets transformed into particles through cross-linking reaction. The size and morphology of particles could be controlled by regulating the centrifugal force, the channel geometry and the distance between the channel outlet and the CaCl2 solution. The throughput of particle production was evidently enhanced by increasing the number of radial channels to 48 and 64. The coefficients of variation of particle sizes were in the range of 5.2-5.6%, which indicated the monodisperse particles could be prepared by using the present method. With the chip configuration readily modified, the same platform could be used to produce Janus particles. The Janus particles showed clear interfaces owing to the high flight speed and the rapid gelling process of the droplets. This method would be capable of generating particles with complicated morphology and multifunction from diverse polymeric materials.

  8. Separation of active laccases from Pleurotus sapidus culture supernatant using aqueous two-phase systems in centrifugal partition chromatography. (United States)

    Schwienheer, C; Prinz, A; Zeiner, T; Merz, J


    For the production of bio active compounds, e.g., active enzymes or antibodies, a conserved purification process with a minimum loss of active compounds is necessary. In centrifugal partition chromatography (CPC), the separation effect is based on the different distribution of the components to be separated between two immiscible liquid phases. Thereby, one liquid phase is kept stationary in chambers by a centrifugal field and the mobile phase is pumped through via connecting ducts. Aqueous two phase systems (ATPS) are known to provide benign conditions for biochemical products and seem to be promising when used in CPC for purification tasks. However, it is not known if active biochemical compounds can "survive" the conditions in a CPC where strong shear forces can occur due to the two-phasic flow under centrifugal forces. Therefore, this aspect has been faced within this study by the separation of active laccases from a fermentation broth of Pleurotus sapidus. After selecting a suitable ATPS and operating conditions, the activity yield was calculated and the preservation of the active enzymes could be observed. Therefore, CPC could be shown as potentially suitable for the purification of bio-active compounds.

  9. Exosome enrichment of human serum using multiple cycles of centrifugation. (United States)

    Kim, Jeongkwon; Tan, Zhijing; Lubman, David M


    In this work, we compared the use of repeated cycles of centrifugation at conventional speeds for enrichment of exosomes from human serum compared to the use of ultracentrifugation (UC). After removal of cells and cell debris, a speed of 110 000 × g or 40 000 × g was used for the UC or centrifugation enrichment process, respectively. The enriched exosomes were analyzed using the bicinchoninic acid assay, 1D gel separation, transmission electron microscopy, Western blotting, and high-resolution LC-MS/MS analysis. It was found that a five-cycle repetition of UC or centrifugation is necessary for successful removal of nonexosomal proteins in the enrichment of exosomes from human serum. More significantly, 5× centrifugation enrichment was found to provide similar or better performance than 5× UC enrichment in terms of enriched exosome protein amount, Western blot band intensity for detection of CD-63, and numbers of identified exosome-related proteins and cluster of differentiation (CD) proteins. A total of 478 proteins were identified in the LC-MS/MS analyses of exosome proteins obtained from 5× UCs and 5× centrifugations including many important CD membrane proteins. The presence of previously reported exosome-related proteins including key exosome protein markers demonstrates the utility of this method for analysis of proteins in human serum.

  10. Experience with the Sarns centrifugal pump in postcardiotomy ventricular failure. (United States)

    Curtis, J J; Walls, J T; Schmaltz, R; Boley, T M; Nawarawong, W; Landreneau, R J


    The reported clinical use of the Sarns centrifugal pump (Sarns, Inc./3M, Ann Arbor, Mich.) as a cardiac assist device for postcardiotomy ventricular failure is limited. During a 25-month period ending November 1988, we used 40 Sarns centrifugal pumps as univentricular or biventricular cardiac assist devices in 27 patients who could not be weaned from cardiopulmonary bypass despite maximal pharmacologic and intraaortic balloon support. Eighteen men and nine women with a mean age of 60.4 years (28 to 83) required assistance. Left ventricular assist alone was used in 12 patients, right ventricular assist in 2, and biventricular assist in 13. The duration of assist ranged from 2 to 434 hours (median 45). Centrifugal assist was successful in weaning 100% of the patients. Ten of 27 patients (37%) improved hemodynamically, allowing removal of the device(s), and 5 of 27 (18.5%) survived hospitalization. Survival of patients requiring left ventricular assist only was 33.3% (4/12). Complications were common and included renal failure, hemorrhage, coagulopathy, ventricular arrhythmias, sepsis, cerebrovascular accident, and wound infection. During 3560 centrifugal pump hours, no pump thrombosis was observed. The Sarns centrifugal pump is an effective assist device when used to salvage patients who otherwise cannot be weaned from cardiopulmonary bypass. Statistical analysis of preoperative patient characteristics, operative risk factors, and postoperative complications failed to predict which patients would be weaned from cardiac assist or which would survive.

  11. Recovery of materials from waste printed circuit boards by vacuum pyrolysis and vacuum centrifugal separation. (United States)

    Zhou, Yihui; Wu, Wenbiao; Qiu, Keqiang


    In this research, a two-step process consisting of vacuum pyrolysis and vacuum centrifugal separation was employed to treat waste printed circuit boards (WPCBs). Firstly, WPCBs were pyrolysed under vacuum condition at 600 °C for 30 min in a lab-scale reactor. Then, the obtained pyrolysis residue was heated under vacuum until the solder was melted, and then the molten solder was separated from the pyrolysis residue by the centrifugal force. The results of vacuum pyrolysis showed that the type-A of WPCBs (the base plates of which was made from cellulose paper reinforced phenolic resin) pyrolysed to form an average of 67.97 wt.% residue, 27.73 wt.% oil, and 4.30 wt.% gas; and pyrolysis of the type-B of WPCBs (the base plates of which was made from glass fiber reinforced epoxy resin) led to an average mass balance of 72.20 wt.% residue, 21.45 wt.% oil, and 6.35 wt.% gas. The results of vacuum centrifugal separation showed that the separation of solder was complete when the pyrolysis residue was heated at 400 °C, and the rotating drum was rotated at 1200 rpm for 10 min. The pyrolysis oil and gas can be used as fuel or chemical feedstock after treatment. The pyrolysis residue after solder separation contained various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The recovered solder can be reused directly and it can also be a good resource of lead and tin for refining.

  12. Centrifuge modelling of drained lateral pile - soil response

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte

    of rigid piles. The tests have been performed in homogeneously dense dry or saturated Fontainebleau sand in order to mimic simplified drained offshore soil conditions. Approximately half of the tests have been carried out to investigate the centrifuge procedure in order to create a methodology of testing...... for monopiles today. Therefore it appears that the methodology for monopiles lacks scientific justification and a better understanding of rigid piles is needed. More than 70 centrifuge tests on laterally loaded rigid model piles have been carried out in connection with this thesis to get a better understanding...... that enables the transformation of result from tests in model scale to prototype scale. The grain size to pile diameter ratio, the non-linear stress distribution and the pile installation was identified from this investigation as important parameters in reliable scaling of centrifuge results. The remaining...

  13. Investigation of Surge Behavior in a Micro Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    Shimpei MIZUKI; Yuichiro ASAGA; Yushi ONO; Hoshio TSUJITA


    This paper reports the experimental and theoretical study of the surge occurred in prototyping an ultra micro centrifugal compressor. As the first step, the 10 times size model of an ultra micro centrifugal compressor having the 40 mm outer diameter was designed and manufactured. The detailed experimental investigations for the transient behavior of surge with several different values of B parameter were carried out. The experimental results during the surge were compared with those obtained by the non-linear lumped parameter theory in order to validate the effectiveness of the theoretical surge model for the micro centrifugal compressor. As a result, the quite different behavior of the surge appeared for the different values of B both in the experiment and in the analysis.

  14. Passively Shunted Piezoelectric Damping of Centrifugally-Loaded Plates (United States)

    Duffy, Kirsten P.; Provenza, Andrew J.; Trudell, Jeffrey J.; Min, James B.


    Researchers at NASA Glenn Research Center have been investigating shunted piezoelectric circuits as potential damping treatments for turbomachinery rotor blades. This effort seeks to determine the effects of centrifugal loading on passively-shunted piezoelectric - damped plates. Passive shunt circuit parameters are optimized for the plate's third bending mode. Tests are performed both non-spinning and in the Dynamic Spin Facility to verify the analysis, and to determine the effectiveness of the damping under centrifugal loading. Results show that a resistive shunt circuit will reduce resonant vibration for this configuration. However, a tuned shunt circuit will be required to achieve the desired damping level. The analysis and testing address several issues with passive shunt circuit implementation in a rotating system, including piezoelectric material integrity under centrifugal loading, shunt circuit implementation, and tip mode damping.

  15. Centrifuge modeling of shallow foundation on soft soil

    Energy Technology Data Exchange (ETDEWEB)

    Leung, P.K.; Ku, H.Y.; Pane, V.; Schiffman, R.L.


    A series of centrifuge model tests was performed to study the behavior of shallow foundations on soft normally consolidated clay. The model tests included testing of foundation models with one-dimensional, plane strain, and axially symmetric geometries. The nonlinear consolidation properties of the soil were determined using specially developed laboratory testing techniques. The centrifuge test data were then compared with conventional and finite strain theories for consolidation assessment, as well as a limit analysis solution for foundation stability considerations. It is found that centrifuge testing coupled with careful laboratory testing provides a useful tool to validate analytical procedures. It has demonstrated that the finite strain theory and the limit analysis solution are valid procedures for the determination of consolidation settlement and foundation penetration of shallow foundations on soft soil, respectively.

  16. Studies on preparation of aceclofenac pellets by centrifugal granulator

    Directory of Open Access Journals (Sweden)

    Zibin GAO

    Full Text Available To prepare aceclofenac pellets by centrifugal granulation. Using 90~100 g of starch pellets as the core pellets,100 g of aceclofenac mixed with 50 g of microcrystalline cellulose(MCC and 4 g talc, methyl cellulose (HPMC as binder,the aceclofenac pellets were prepared by centrifugal granulation .And evaluate the quality of the pellets. The aceclofenac pellets had high yield and less losses,the pellets had a partical size of 0.70~0.88 mm(18~24 mesh)and had uniform particle size .the moisture ,drug content and dissolution meet the requirement . Aceclofenac pellets were prepared by the process of centrifugal granulation .The preparation prescription and process parameters were optimized by single factor method .and the pellets meet the standard requirements.

  17. Centrifuge modelling of a laterally cyclic loaded pile

    DEFF Research Database (Denmark)

    Klinkvort, Rasmus Tofte; Leth, Caspar Thrane; Hededal, Ole


    A total number of 9 static and 6 cyclic centrifuge tests on laterally loaded piles in very dense, dry sand was erformed. The prototype dimensions of the piles were 1 meter in diameter and penetration depths varying from 6 to 10 meters. The static tests were used to investigate the initial subgrade...... reaction modulus and as a reference for cyclic tests. For the cyclic tests the accumulation of deflections and the change in secant stiffness of the soil from repetitive loading were investigated. From all the tests carried out accumulations of deflections were seen. rom the centrifuge tests it was seen...

  18. Secondary Containment Design for a High Speed Centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, K.W.


    Secondary containment for high speed rotating machinery, such as a centrifuge, is extremely important for operating personnel safety. Containment techniques can be very costly, ungainly and time consuming to construct. A novel containment concept is introduced which is fabricated out of modular sections of polycarbonate glazed into a Unistrut metal frame. A containment study for a high speed centrifuge is performed which includes the development of parameters for secondary containment design. The Unistrut/polycarbonate shield framing concept is presented including design details and proof testing procedures. The economical fabrication and modularity of the design indicates a usefulness for this shielding system in a wide variety of containment scenarios.

  19. Deep eutectic solvents in countercurrent and centrifugal partition chromatography. (United States)

    Roehrer, Simon; Bezold, Franziska; García, Eva Marra; Minceva, Mirjana


    Deep eutectic solvents (DESs) were evaluated as solvents in centrifugal partition chromatography, a liquid-liquid chromatography separation technology. To this end, the partition coefficients of ten natural compounds of different hydrophobicity were determined in non-aqueous biphasic systems containing DES. The influence of the composition of DESs and the presence of water in the biphasic system on the partition coefficient were also examined. In addition, several process relevant physical properties of the biphasic system, such as the density and viscosity of the phases, were measured. A mixture of three to four hydrophobic compounds was successfully separated in a centrifugal partition extractor using a heptane/ethanol/DES biphasic system.

  20. Model Based Fault Detection in a Centrifugal Pump Application

    DEFF Research Database (Denmark)

    Kallesøe, Carsten; Cocquempot, Vincent; Izadi-Zamanabadi, Roozbeh


    A model based approach for fault detection in a centrifugal pump, driven by an induction motor, is proposed in this paper. The fault detection algorithm is derived using a combination of structural analysis, observer design and Analytical Redundancy Relation (ARR) design. Structural consideration...... is capable of detecting four different faults in the mechanical and hydraulic parts of the pump.......A model based approach for fault detection in a centrifugal pump, driven by an induction motor, is proposed in this paper. The fault detection algorithm is derived using a combination of structural analysis, observer design and Analytical Redundancy Relation (ARR) design. Structural considerations...

  1. A study of the Coriolis effect on the fluid flow profile in a centrifugal bioreactor. (United States)

    Detzel, Christopher J; Thorson, Michael R; Van Wie, Bernard J; Ivory, Cornelius F


    Increasing demand for tissues, proteins, and antibodies derived from cell culture is necessitating the development and implementation of high cell density bioreactors. A system for studying high density culture is the centrifugal bioreactor (CCBR), which retains cells by increasing settling velocities through system rotation, thereby eliminating diffusional limitations associated with mechanical cell retention devices. This article focuses on the fluid mechanics of the CCBR system by considering Coriolis effects. Such considerations for centrifugal bioprocessing have heretofore been ignored; therefore, a simpler analysis of an empty chamber will be performed. Comparisons are made between numerical simulations and bromophenol blue dye injection experiments. For the non-rotating bioreactor with an inlet velocity of 4.3 cm/s, both the numerical and experimental results show the formation of a teardrop shaped plume of dye following streamlines through the reactor. However, as the reactor is rotated, the simulation predicts the development of vortices and a flow profile dominated by Coriolis forces resulting in the majority of flow up the leading wall of the reactor as dye initially enters the chamber, results are confirmed by experimental observations. As the reactor continues to fill with dye, the simulation predicts dye movement up both walls while experimental observations show the reactor fills with dye from the exit to the inlet. Differences between the simulation and experimental observations can be explained by excessive diffusion required for simulation convergence, and a slight density difference between dyed and un-dyed solutions. Implications of the results on practical bioreactor use are also discussed.

  2. Liquid flow on a rotating disk prior to centrifugal atomization and spray deposition (United States)

    Zhao, Y. Y.; Jacobs, M. H.; Dowson, A. L.


    Video observations of the flow patterns that develop on a rotating disk during centrifugal atomization and spray deposition, and subsequent metallographic studies conducted on solid skulls removed from the disk after processing, have indicated a circular discontinuity or hydraulic jump, which is manifested by a rapid increase in the thickness of the liquid metal and by a corresponding decrease in the radial velocity. A mathematical model has been developed that is capable of predicting both the occurrence and location of the jump, and the associated changes in the thickness profile and in the radial and tangential velocities of the liquid metal. Good correlations have been observed between model predictions and the flow patterns observed on the skull after atomization, and the effects of changes in material and operational parameters such as kinematic viscosity, volume flow rate, metallostatic head, and disk rotation speed have been quantified. Liquid metal flow is controlled primarily by the volume flow rate and by the metallostatic head prior to the hydraulic jump and by the centrifugal forces after the jump. The implications of these observations in terms of the atomization process are discussed.

  3. An implantable seal-less centrifugal pump with integrated double-disk motor. (United States)

    Schima, H; Schmallegger, H; Huber, L; Birgmann, I; Reindl, C; Schmidt, C; Roschal, K; Wieselthaler, G; Trubel, W; Losert, U


    Thrombus formation and sealing problems at the shaft as well as the compact and efficient design of the driving unit have been major difficulties in the construction of a long-term implantable centrifugal pump. To eliminate the problems of the seal, motor size, and efficiency, two major steps were taken by modifying the Vienna implantable centrifugal pump. First, a special driving unit was developed, in which the permanent magnets of the motor themselves are used for coupling the force into the rotor. Second, the rotor shaft in the pumping chamber was eliminated by adopting a concept recently presented by Ohara. The rotor is supported by 3 pins, which run on a carbon disk, whose concave shape leads to stabilization. The device has the following specifications: size: 65 mm (diameter) by 35 mm (height), 101 cm3; priming volume 30 cm3, 240 g; and a 6-pole brushless double disk DC motor. The required input power of the described prototype is 15 W at 150 mm Hg, 5 L/min (overall eta = 11%), and has an in vitro index of hemolysis (IH) of 0.0046 g/100 L. The test for in vitro thrombus growth exhibited far less thrombus formation in the new design than in designs with axles. In conclusion, the design of a special driving unit and the elimination of the axle led to the construction of a small pump with very low blood traumatization.

  4. Microstructural characteristics and properties in centrifugal casting of SiC_p/Zl104 composite

    Institute of Scientific and Technical Information of China (English)

    WANG Kai; XUE Han-song; ZOU Mao-hua; LIU Chang-ming


    The microstructural characteristics and Brinell hardness of a cylinder produced by centrifugal casting were investigated using 20% (volume fraction) SiC_p/Zl104 composites.Macrostructure and XRD analysis show that most of SiC particles segregate to the external circumference of the cylinder,the other SiC particles maintain in the inner circumference of the cylinder,and a free particle zone is left in the middle circumference of the cylinder.Microstructural characteristics and quantitative assessment of SiC particles show that most of congregated SiC particles in 20%SiC_p/Zl104 composites are dispersed by centrifugal force,and the other congregated SiC particles and most of alumina oxide are segregated to the inner circumference of the cylinder.The SiC particles in aluminum melt can promote the refinement of primary α(Al) during solidification,and fine primary α(Al) grains can also promote the uniform distribution of SiC particles.Brinell hardness of SiC_p/Zl104 composites is connected with not only the volume fraction of SiC particles,but also the distribution of SiC particles in matrix alloy.


    Institute of Scientific and Technical Information of China (English)


    Numerical investigations of the 'banding' microstructure formation during solidifica-tion of Ti-6Al-4V alloy in the centrifugal casting are conducted using a multi-scale model, which combines the finite difference method (FDM) at the macroscale with a cellular automaton (CA) model at the microscale. The macro model is used to simu-late the fluid flow and heat transfer throughout the casting. The micro model is used to predict the nucleation and growth of microstructures. With the proposed model,numerical simulations are performed to study the influences of the nucleation density,mould rotation speed, and casting size upon the 'banding' microstructure formation. It is noted that changing the nucleation density has a minor effect on the microstructure formation. The rotation speed promotes the formation of 'banding' microstructure,which is more noticeable for larger size castings. The major mechanism responsi-ble for this 'banding' phenomenon is the spatial variation in cooling rates created by centrifugal force.

  6. Light forces in ultracold photoassociation

    CERN Document Server

    Gómez, E; Lett, P D; Tiesinga, E; Turner, L D


    We study the time-resolved photoassociation of ultracold sodium in an optical dipole trap. The photoassociation laser excites pairs of atoms to molecular states of large total angular momentum at high intensities (above 20 kW/cm$^{2}$). Such transitions are generally suppressed at ultracold temperatures by the centrifugal barriers for high partial waves. Time-resolved ionization measurements reveal that the atoms are accelerated by the dipole potential of the photoassociation beam. We change the collision energy by varying the potential depth, and observe a strong variation of the photoassociation rate. These results demonstrate the important role of light forces in cw photoassociation at high intensities.

  7. Mechanism of Gas Intrusion into Molten Metal during Horizontal Centrifugal Casting

    Institute of Scientific and Technical Information of China (English)

    NI Feng; ZHANG Xhan-ling; YANG Di-xin; BI Xiao-qin; ZHANG Yong-zhen


    A mechanism of gas intrusion into molten metal during horizontal centrifugal casting was introduced .Based upon this concept, a special pouring method was suggested ,which can effectively prevent the pinhole defects in horizontal centrifugal castings.

  8. Centrifugal Model Tests on Railway Embankments of Expansive Soils

    Institute of Scientific and Technical Information of China (English)


    Based on the centrifugal model tests on railway embankments of expansive soil in Nanning-Kunming railway,the author studied several embankments under different physical conditions. The stress and strain states and settlement of the embankments were analyzed, and the obtained results can be used as a reference to field construction.

  9. Liquid egg white pasteurization using a centrifugal UV irradiator (United States)

    Studies are lacking on UV nonthermal pasteurization of liquid egg white (LEW). The objective of this study was to inactivate Escherichia coli using a UV irradiator that centrifugally formed a thin film of LEW on the inside of a rotating cylinder. The LEW was inoculated with E. coli K12 to approximat...


    The plasma centrifugal furnace is a thermal technology which uses the heat generated from a plasma torch to decontaminate metal and organic contaminated waste. This is accomplished by melting metal-bearing solids and, in the process, thermally destroying organic contaminants. The...

  11. 14 CFR 35.35 - Centrifugal load tests. (United States)


    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: PROPELLERS Tests and Inspections § 35.35 Centrifugal load tests. The applicant must demonstrate that a propeller complies with paragraphs (a), (b) and (c) of this section without evidence of...

  12. Application of antioxidants and centrifugation for cryopreservation of boar spermatozoa. (United States)

    Zhang, Wei; Yi, Kangle; Chen, Chao; Hou, Xiaofeng; Zhou, Xu


    Although cryopreserved boar semen has been available since 1975, a major breakthrough in commercial application has not yet occurred due to the high susceptibility of boar spermatozoa to damage during cryopreservation and the complicated process required for deep freezing. In recent years, the application of antioxidants during the cryopreservation of boar semen has been the subject of considerable research aimed at improving the quality of post-thaw semen. Centrifugation is necessary before using cryopreservation protocols for freezing boar spermatozoa. Studies of the effect of different centrifugation regimens on boar sperm recovery, yield and cryosurvival have made significant contributions. Therefore this review elucidates results of recent applications of various antioxidants and centrifugation regimens used in efforts to improve cryopreservation of boar spermatozoa. This review is intended to enhance understanding of the roles of these antioxidants and centrifugation regimens with respect to mechanisms that increase resistance to cryodamage of boar spermatozoa. In addition, the discussion addresses the need for developing an objective evaluation of effectiveness and estimating the prospect of application of new techniques for the cryopreservation of boar semen and its use in artificial insemination.

  13. Flow pattern in reverse-flow centrifugal separators

    NARCIS (Netherlands)

    Peng, W; Hoffmann, AC; Boot, PJAJ; Udding, A; Dries, HWA; Ekker, A; Kater, J


    Experimental flow patterns, determined by Laser Doppler Anemometry (LDA) for two types of reverse-flow centrifugal separators, are presented. The flow patterns in (a) a conventional cylinder-on-cone cyclone with tangential inlet and (b) a swirl tube with vane-generated swirl and a cylindrical body a

  14. Vibratory centrifuge for the dewatering of coal sludge

    Energy Technology Data Exchange (ETDEWEB)

    Schiele, H.; Schlebusch, L.


    A vibratory centrifuge for the dewatering of coal sludge, washed small coal or slack which comprises a revolvable conical screen which has a diameter that increases towards its discharge end. The conical screen is vibratable in an axial direction and includes radial steps each having a height of at least 20 mm to rearrangement or loosen the material in the zone of each step.

  15. Synthesis and Analytical Centrifugation of Magnetic Model Colloids

    NARCIS (Netherlands)

    Luigjes, B.


    This thesis is a study of the preparation and thermodynamic properties of magnetic colloids. First, two types of magnetic model colloids are investigated: composite colloids and single-domain nanoparticles. Thermodynamics of magnetic colloids is studied using analytical centrifugation, including a s

  16. Numerical Simulation and Cold Modeling experiments on Centrifugal Casting (United States)

    Keerthiprasad, Kestur Sadashivaiah; Murali, Mysore Seetharam; Mukunda, Pudukottah Gopaliengar; Majumdar, Sekhar


    In a centrifugal casting process, the fluid flow eventually determines the quality and characteristics of the final product. It is difficult to study the fluid behavior here because of the opaque nature of melt and mold. In the current investigation, numerical simulations of the flow field and visualization experiments on cold models have been carried out for a centrifugal casting system using horizontal molds and fluids of different viscosities to study the effect of different process variables on the flow pattern. The effects of the thickness of the cylindrical fluid annulus formed inside the mold and the effects of fluid viscosity, diameter, and rotational speed of the mold on the hollow fluid cylinder formation process have been investigated. The numerical simulation results are compared with corresponding data obtained from the cold modeling experiments. The influence of rotational speed in a real-life centrifugal casting system has also been studied using an aluminum-silicon alloy. Cylinders of different thicknesses are cast at different rotational speeds, and the flow patterns observed visually in the actual castings are found to be similar to those recorded in the corresponding cold modeling experiments. Reasonable agreement is observed between the results of numerical simulation and the results of cold modeling experiments with different fluids. The visualization study on the hollow cylinders produced in an actual centrifugal casting process also confirm the conclusions arrived at from the cold modeling experiments and numerical simulation in a qualitative sense.

  17. Centrifugally driven microfluidic disc for detection of chromosomal translocations

    DEFF Research Database (Denmark)

    Brøgger, Anna Line; Kwasny, Dorota; Bosco, Filippo G.


    and prognosis of patients. In this work we demonstrate a novel, centrifugally-driven microfluidic system for controlled manipulation of oligonucleotides and subsequent detection of chromosomal translocations. The device is fabricated in the form of a disc with capillary burst microvalves employed to control...

  18. Centrifuge modelling of rigid piles in soft clay

    DEFF Research Database (Denmark)

    Klinkvort, R.T.; Poder, M.; Truong, P.;


    of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...

  19. Ocular torsion before and after 1 hour centrifugation

    NARCIS (Netherlands)

    Groen, E.; Graaf, B. de; Bles, W.; Bos, J.E.


    To assess a possible otolith contribution to effects observed following prolonged expo-sure to hyper gravity, we used video-oculography to measure ocular torsion during static and dynamic conditions of lateral body tilt (roll) before and after one hour of centrifugation with a Gx-load of 3G. Static

  20. Gas-liquid Two Phase Flow Modelling of Incompressible Fluid and Experimental Validation Studies in Vertical Centrifugal Casting (United States)

    Zhou, J. X.; Shen, X.; Yin, Y. J.; Guo, Z.; Wang, H.


    In this paper, Gas-liquid two phase flow mathematic models of incompressible fluid were proposed to explore the feature of fluid under certain centrifugal force in vertical centrifugal casting (VCC). Modified projection-level-set method was introduced to solve the mathematic models. To validate the simulation results, two methods were used in this study. In the first method, the simulation result of basic VCC flow process was compared with its analytic solution. The relationship between the numerical solution and deterministic analytic solution was presented to verify the correctness of numerical algorithms. In the second method, systematic water simulation experiments were developed. In this initial experiment, special experimental vertical centrifugal device and casting shapes were designed to describe typical mold-filling processes in VCC. High speed camera system and data collection devices were used to capture flow shape during the mold-filling process. Moreover, fluid characteristic at different rotation speed (from 40rpm, 60rpmand 80rpm) was discussed to provide comparative resource for simulation results. As compared with the simulation results, the proposed mathematical models could be proven and the experimental design could help us advance the accuracy of simulation and further studies for VCC.

  1. Effect of casting speed and delay time on the residual stresses in centrifugal casting of aluminium rods

    Directory of Open Access Journals (Sweden)

    Adesoji A. OYEDEJI


    Full Text Available Longitudinal slitting technique has been employed to determine the residual stresses in centrifugal cast aluminium rods. Residual stresses were found to decrease with increase in casting speed in the centrifugal casting. The residual stresses of the aluminium rods cast at speeds of 100, 200, 300, 400 and 500rpm and at zero (0 second delay time have lower residual stresses as compared to those cast at the same varying casting speeds at ten (10 seconds delay time. At the different casting speeds, residual stress ratio (g was found to decrease with increase in the casting speeds with values of 40.91%, 31.82%, 22.73%, 13.64% and 9.09% at zero second delay time, while at ten seconds delay time the residual stress ratios were 68.18%, 59.09%, 54.55%, 50.00% and 36.36% respectively. Reduction in residual stress with increase in speed and delay time is attributed to the greater centrifugal forces created by the increasing casting speeds on the solidification of the molten aluminium.

  2. Fault-tolerant strategies for an implantable centrifugal blood pump using a radially controlled magnetic bearing. (United States)

    Pai, Chi Nan; Shinshi, Tadahiko


    In our laboratory, an implantable centrifugal blood pump (CBP) with a two degrees-of-freedom radially controlled magnetic bearing (MB) to support the impeller without contact has been developed to assist the pumping function of the weakened heart ventricle. In order to maintain the function of the CBP after damage to the electromagnets (EMs) of the MB, fault-tolerant strategies for the CBP are proposed in this study. Using a redundant MB design, magnetic levitation of the impeller was maintained with damage to up to two out of a total of four EMs of the MB; with damage to three EMs, contact-free support of the impeller was achieved using hydrodynamic and electromagnetic forces; and with damage to all four EMs, the pump operating point, of 5 l/min against 100 mmHg, was achieved using the motor for rotation of the impeller, with contact between the impeller and the stator.

  3. Diagnosis of the Thermal Bow of a Shaft in a Three Stage Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)


    In practice many turbo-machines driven by motors are started up to operational speed within a very short time, i.e. in less than 20 seconds. For this type of machines the compatibility of thermal deformation of the rotor structure must be taken into account in the machine design, or the thermal deformation will be constrained and a huge resultant force can cause the shaft bending and consequently resulting in violent vibrations. In this paper, detection of thermal bow of a shaft in a three stage centrifugal compressor in a petrochemical plant is presented. The diagnostic results show that the thermal bow was induced by the incompatibility of axial thermal deformation of the rotor structure. A remedial action allowing free axial thermal expansion of the outer parts of the rotor is suggested.

  4. Centrifugo-pneumatic multi-liquid aliquoting - parallel aliquoting and combination of multiple liquids in centrifugal microfluidics. (United States)

    Schwemmer, F; Hutzenlaub, T; Buselmeier, D; Paust, N; von Stetten, F; Mark, D; Zengerle, R; Kosse, D


    The generation of mixtures with precisely metered volumes is essential for reproducible automation of laboratory workflows. Splitting a given liquid into well-defined metered sub-volumes, the so-called aliquoting, has been frequently demonstrated on centrifugal microfluidics. However, so far no solution exists for assays that require simultaneous aliquoting of multiple, different liquids and the subsequent pairwise combination of aliquots with full fluidic separation before combination. Here, we introduce the centrifugo-pneumatic multi-liquid aliquoting designed for parallel aliquoting and pairwise combination of multiple liquids. All pumping and aliquoting steps are based on a combination of centrifugal forces and pneumatic forces. The pneumatic forces are thereby provided intrinsically by centrifugal transport of the assay liquids into dead end chambers to compress the enclosed air. As an example, we demonstrate simultaneous aliquoting of 1.) a common assay reagent into twenty 5 μl aliquots and 2.) five different sample liquids, each into four aliquots of 5 μl. Subsequently, the reagent and sample aliquots are simultaneously transported and combined into twenty collection chambers. All coefficients of variation for metered volumes were between 0.4%-1.0% for intra-run variations and 0.5%-1.2% for inter-run variations. The aliquoting structure is compatible to common assay reagents with a wide range of liquid and material properties, demonstrated here for contact angles between 20° and 60°, densities between 789 and 1855 kg m(-3) and viscosities between 0.89 and 4.1 mPa s. The centrifugo-pneumatic multi-liquid aliquoting is implemented as a passive fluidic structure into a single fluidic layer. Fabrication is compatible to scalable fabrication technologies such as injection molding or thermoforming and does not require any additional fabrication steps such as hydrophilic or hydrophobic coatings or integration of active valves.

  5. German chemical plants with particular reference to centrifuges

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, F.


    This report consisted of 9 reports. Report No. 1 was about Elmore Metall A. G., Schlandern on Siegburg. Two divisions of works in this factory were: (1) tube-drawing section for copper, steel, and zinc, with old machinery; (2) a section making electrolytically-deposited copper cylinders up to 100'' diameter, of high purity and excellent mechanical properties. The electrolytically-deposited copper cylinders were produced in lead-lined wooden tanks. Report No. 2 was about H. Krantz Maschinenfabrik, Aachen. This firm specialized in hydro-extractors, confined to types suitable for laundries and textile work. The machines built were of sizes from 800 mm to 1,8000 mm basket diameter. Report No. 3 was about O. Doerries A. G., Vorm Banning, and Seyfold Duren. This firm specialized in paper-making machinery, including centrifugal grit extractors for the treatment of paper stock. Erkensators number 4 and number 4L were compared in this report. Reports No. 4 and No. 5 were about I. G. Farbenindustrie, Dormagen, and Elberfeld. General information about the continuously-operating centrifuges was given. Report No. 6 was about Glanstoff Courtald between Cologne and Dormagen, where they used two methods of extracting water from viscose cakes, (1) by multiple-hinged candle hydro-extractors, and (2) by converted spinning pots. Report No. 7 was about Matthers and Weber, Duisberg, and gave general information about two kinds of centrifuges, (1) for crude bi-carbonate, and (2) for refined bi-carbonate. Report No. 8 was about Westfalia Separator A. G., Oelde; where the high-speed centrifuges of the ''cream separator'' or Laval type were made. Report No. 9 was about Escher Wyss, Ravensburg, where centrifuges, water turbines, spray dryers, and paper-making machinery were manufactured.

  6. Design and implementation of fluidic micro-pulleys for flow control on centrifugal microfluidic platforms. (United States)

    Soroori, Salar; Kulinsky, Lawrence; Kido, Horacio; Madou, Marc


    Microfluidic discs have been employed in a variety of applications for chemical analyses and biological diagnostics. These platforms offer a sophisticated fluidic toolbox, necessary to perform processes that involve sample preparation, purification, analysis, and detection. However, one of the weaknesses of such systems is the uni-directional movement of fluid from the disc center to its periphery due to the uni-directionality of the propelling centrifugal force. Here we demonstrate a mechanism for fluid movement from the periphery of a hydrophobic disc toward its center that does not rely on the energy supplied by any peripheral equipment. This method utilizes a ventless fluidic network that connects a column of working fluid to a sample fluid. As the working fluid is pushed by the centrifugal force to move toward the periphery of the disc, the sample fluid is pulled up toward the center of the disc analogous to a physical pulley where two weights are connected by a rope passed through a block. The ventless network is analogous to the rope in the pulley. As the working fluid descends, it creates a negative pressure that pulls the sample fluid up. The sample and working fluids do not come into direct contact and it allows the freedom to select a working fluid with physical properties markedly different from those of the sample. This article provides a demonstration of the "micro-pulley" on a disc, discusses underlying physical phenomena, provides design guidelines for fabrication of micro-pulleys on discs, and outlines a vision for future micro-pulley applications.

  7. 21 CFR 864.9275 - Blood bank centrifuge for in vitro diagnostic use. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Blood bank centrifuge for in vitro diagnostic use... Manufacture Blood and Blood Products § 864.9275 Blood bank centrifuge for in vitro diagnostic use. (a) Identification. A blood bank centrifuge for in vitro diagnostic use is a device used only to separate blood...

  8. 40 CFR Appendix - Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC... (United States)


    ... Limits for Open Molding, Centrifugal Casting, and SMC Manufacturing Operations Where the Standards Are..., Table 5 Alternative Organic HAP Emissions Limits for Open Molding, Centrifugal Casting, and SMC... casting—CR/HS 3,4 A vent system that moves heated air through the mold 27 lb/ton. 8. Centrifugal...

  9. A novel technique using the Hendrickx centrifuge for extracting winter sporangia of Synchytrium endobioticum from soil

    NARCIS (Netherlands)

    Wander, J.G.N.; Berg, van den W.; Boogert, van den P.H.J.F.; Lamers, J.G.; Leeuwen, van G.C.M.; Hendrickx, G.; Bonants, P.J.M.


    A zonal centrifugation method, known as the Hendrickx centrifuge technique, was tested for routine detection of winter sporangia of Synchytrium endobioticum in soil. In four experiments the ability of the Hendrickx centrifuge to extract the sporangia from soil was compared with a method used by the

  10. 77 FR 65360 - Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps); Auburn, NY (United States)


    ... Foreign-Trade Zones Board Grant of Authority for Subzone Status (Centrifugal and Submersible Pumps... subzone at the centrifugal and submersible pump manufacturing and warehousing facilities of Xylem Water... activity related to the manufacturing of centrifugal and submersible pumps and related controllers at...

  11. An in-line spectrophotometer on a centrifugal microfluidic platform for real-time protein determination and calibration. (United States)

    Ding, Zhaoxiong; Zhang, Dongying; Wang, Guanghui; Tang, Minghui; Dong, Yumin; Zhang, Yixin; Ho, Ho-Pui; Zhang, Xuping


    In this paper, an in-line, low-cost, miniature and portable spectrophotometric detection system is presented and used for fast protein determination and calibration in centrifugal microfluidics. Our portable detection system is configured with paired emitter and detector diodes (PEDD), where the light beam between both LEDs is collimated with enhanced system tolerance. It is the first time that a physical model of PEDD is clearly presented, which could be modelled as a photosensitive RC oscillator. A portable centrifugal microfluidic system that contains a wireless port in real-time communication with a smartphone has been built to show that PEDD is an effective strategy for conducting rapid protein bioassays with detection performance comparable to that of a UV-vis spectrophotometer. The choice of centrifugal microfluidics offers the unique benefits of highly parallel fluidic actuation at high accuracy while there is no need for a pump, as inertial forces are present within the entire spinning disc and accurately controlled by varying the spinning speed. As a demonstration experiment, we have conducted the Bradford assay for bovine serum albumin (BSA) concentration calibration from 0 to 2 mg mL(-1). Moreover, a novel centrifugal disc with a spiral microchannel is proposed for automatic distribution and metering of the sample to all the parallel reactions at one time. The reported lab-on-a-disc scheme with PEDD detection may offer a solution for high-throughput assays, such as protein density calibration, drug screening and drug solubility measurement that require the handling of a large number of reactions in parallel.

  12. A centrifuge CO2 pellet cleaning system (United States)

    Foster, C. A.; Fisher, P. W.; Nelson, W. D.; Schechter, D. E.


    An advanced turbine/CO2 pellet accelerator is being evaluated as a depaint technology at Oak Ridge National Laboratory (ORNL). The program, sponsored by Warner Robins Air Logistics Center (ALC), Robins Air Force Base, Georgia, has developed a robot-compatible apparatus that efficiently accelerates pellets of dry ice with a high-speed rotating wheel. In comparison to the more conventional compressed air 'sandblast' pellet accelerators, the turbine system can achieve higher pellet speeds, has precise speed control, and is more than ten times as efficient. A preliminary study of the apparatus as a depaint technology has been undertaken. Depaint rates of military epoxy/urethane paint systems on 2024 and 7075 aluminum panels as a function of pellet speed and throughput have been measured. In addition, methods of enhancing the strip rate by combining infra-red heat lamps with pellet blasting and by combining the use of environmentally benign solvents with the pellet blasting have also been studied. The design and operation of the apparatus will be discussed along with data obtained from the depaint studies.

  13. Effect of Excess Gravitational Force on Cultured Myotubes in Vitro

    Directory of Open Access Journals (Sweden)

    Shigehiro Hashimoto


    Full Text Available An effect of an excess gravitational force on cultured myoblasts has been studied in an experimental system with centrifugal force in vitro. Mouse myoblasts (C2C12 were seeded on a culture dish of 35 mm diameter, and cultured in the Dulbecco's Modified Eagle's Medium until the sub-confluent condition. To apply the excess gravitational force on the cultured cells, the dish was set in a conventional centrifugal machine. Constant gravitational force was applied to the cultured cells for three hours. Variations were made on the gravitational force (6 G, 10 G, 100 G, 500 G, and 800 G with control of the rotational speed of the rotator in the centrifugal machine. Morphology of the cells was observed with a phasecontrast microscope for eight days. The experimental results show that the myotube thickens day by day after the exposure to the excess gravitational force field. The results also show that the higher excess gravitational force thickens myotubes. The microscopic study shows that myotubes thicken with fusion each other.

  14. Calibration of gyro error model coefficients on precision centrifuge with counter-rotating platform%《中国惯性技术学报》征稿简则

    Institute of Scientific and Technical Information of China (English)


    In order to accurately calibrate the gyro drift coefficients, a coordinate system was set up based on the precision centrifuge with counter-rotating platform, and the attitude relationship between two adjacent coordinate systems were analyzed in consideration of the error sources. Precise angular velocity input for each axis of gyro was derived by using direction cosine matrices, and the nominal value of each specific force input was given as well. Combined with the gyro's static error model, various harmonic amplitude expressions were deduced including gyro drift coefficients. By using centrifuge to provide two different harmonic accelerations, and sampling the output of gyro at each sampling time, the amplitudes of 0-2nd harmonics were obtained through Fourier analysis. The drift coefficients were identified by least square method based on the relationship between harmonic amplitude expressions and drift coefficients. The test simulation results show that the calibration of the gyro drift coefficients on centrifuge with counter-rotating platform can effectively avoid some of the centrifuge errors, and other centrifuge errors only have significant impacts on D1, Ds, DIO and DOs whose accurate calibration can be achieved by compensating the centrifuge errors.

  15. Environmental and centrifugal factors influencing the visco-elastic properties of oral biofilms in vitro. (United States)

    Peterson, Brandon W; Busscher, Henk J; Sharma, Prashant K; van der Mei, Henny C


    Centrifugal compaction causes changes in the surface properties of bacterial cells. It has been shown previously that the surface properties of planktonic cells change with increasing centrifugal compaction. This study aimed to analyze the influences of centrifugal compaction and environmental conditions on the visco-elastic properties of oral biofilms. Biofilms were grown out of a layer of initially adhering streptococci, actinomyces or a combination of these. Different uni-axial deformations were induced on the biofilms and the load relaxations were measured over time. Linear-Regression-Analysis demonstrated that both the centrifugation coefficient for streptococci and induced deformation influenced the percentage relaxation. Centrifugal compaction significantly influenced relaxation only upon compression of the outermost 20% of the biofilm (p centrifugal compaction of initially adhering, centrifuged bacteria extend to the visco-elastic properties of biofilms, indicating that the initial bacterial layer influences the structure of the entire biofilm.

  16. Centrifugal microfluidic platform for ultrasensitive detection of botulinum toxin. (United States)

    Koh, Chung-Yan; Schaff, Ulrich Y; Piccini, Matthew E; Stanker, Larry H; Cheng, Luisa W; Ravichandran, Easwaran; Singh, Bal-Ram; Sommer, Greg J; Singh, Anup K


    We present an innovative centrifugal microfluidic immunoassay platform (SpinDx) to address the urgent biodefense and public health need for ultrasensitive point-of-care/incident detection of botulinum toxin. The simple, sample-to-answer centrifugal microfluidic immunoassay approach is based on binding of toxins to antibody-laden capture particles followed by sedimentation of the particles through a density-media in a microfluidic disk and quantification by laser-induced fluorescence. A blind, head-to-head comparison study of SpinDx versus the gold-standard mouse bioassay demonstrates 100-fold improvement in sensitivity (limit of detection = 0.09 pg/mL), while achieving total sample-to-answer time of capture beads and detection antibodies) are disconnected from the disk architecture and the reader, facilitating rapid development of new assays. SpinDx can also serve as a general-purpose immunoassay platform applicable to diagnosis of other conditions and diseases.

  17. Stage-efficiency of centrifugal extractor used in nuclear industry

    Institute of Scientific and Technical Information of China (English)

    吴秋林; 景山; 王兴海; 宋崇立


    The stage-efficiency of a single-stage prototype (d70) centrifugal extractor and the cascade is tested by HNO3-Nd3+ and 30%TRPO-kerosene system. The experimental results of the single-stage centrifugal extractor show that the carryover of the two phases decreases with increasing ratio of the two flow rate and rotation rate and the stage efficiency increases with not only decreasing total flow rate but also increasing rotor speed. However, the experimental results of the cascade show that the average stage efficiency of the cascade increases with not only decreasing total flow rate but also increasing rotor speed in both three-stage mode and two-stage mode.

  18. Dynamical System Analysis of Unsteady Phenomena in Centrifugal Compressor

    Institute of Scientific and Technical Information of China (English)

    YasuyukiKomatsubara; ShimpeiMizuki


    Surge and rotating stall occurring in a centrifugal compressor system are investigated by using a phase portrait reconstruction method.From experimentally measured time series of data,the method clarified the cyclic behavior of surge.For rotating stall,there still remain problems in the phase portrait due to the chaotic behavior.However,the results obtained by the present method are able to provide new insights to the modelings for surge and rotating stall.Surge and roatting stall occurring in a centrifugal compressor system are investigated by using a phase portrait reconstruction method.From experimentally measured time series of data,the method clarified the cylcic behavior of surge.For rotating stall,there still remain problems in the phase portrait due to the chaotic behavior.However,the results obtained by the present method are able to provide new insights to the modelings for surge and rotating stall.

  19. The simulation and performance of a centrifugal chiller (United States)

    Jackson, W. L.; Chen, F. C.; Hwang, B. C.

    A computer simulation model was developed to analyze the performance of a water-cooled centrifugal chiller. The model is based on a heat pump thermodynamic cycle and empirical correlations for the performance of the system components. The system simulated is composed of a variable-speed centrifugal compressor with a hot-gas bypass option for capacity control, two shell-and-tube heat exchangers, and an expansion device. The model was validated and calibrated against the experimental test results of a 125-ton chiller. The performance of a similar chiller system at various operating conditions and design modifications was analyzed. System performance comparisons were made between a baseline case, cases with high-performance heat exchanger tubes and compressor motor, and various variable-speed compressor operating strategies. It was found that significant performance improvement can be realized by using variable-speed drive and on-demand control strategy.

  20. Centrifuge modeling of PGD response of buried pipe

    Institute of Scientific and Technical Information of China (English)

    Michael O'Rourke; Vikram Gadicherla; Tarek Abdoun


    A new centrifuge based method for determining the response of continuous buried pipe to PGD is presented.The physical characteristics of the RPI's 100 g-ton geotechnical centrifuge and the current lifeline experiment split-box are described: The split-box contains the model pipeline and surrounding soil and is manufactured such that half can be offset, in flight, simulating PGD. In addition, governing similitude relations which allow one to determine the physical characteristics,(diameter, wall thickness and material modulus of elasticity) of the model pipeline are presented. Finally, recorded strains induced in two buried pipes with prototype diameters of 0.63 m and 0.95 m (24 and 36 inch) subject to 0.6 and 2.0 meters (2and 6 feet) of full scale fault offsets and presented and compared to corresponding FE results.

  1. Hemocompatibility of a hydrodynamic levitation centrifugal blood pump. (United States)

    Yamane, Takashi; Maruyama, Osamu; Nishida, Masahiro; Kosaka, Ryo; Sugiyama, Daisuke; Miyamoto, Yusuke; Kawamura, Hiroshi; Kato, Takahisa; Sano, Takeshi; Okubo, Takeshi; Sankai, Yoshiyuki; Shigeta, Osamu; Tsutsui, Tatsuo


    A noncontact type centrifugal pump without any complicated control or sensing modules has been developed as a long-term implantable artificial heart. Centrifugal pumps with impellers levitated by original hydrodynamic bearings were designed and have been modified through numerical analyses and in vitro tests. The hemolysis level was reduced by changing the pressure distribution around the impeller and subsequently expanding the bearing gap. Thrombus formation in the bearing was examined with in vitro thrombogenesis tests and was reduced by changing the groove shapes to increase the bearing-gap flow to 3% of the external flow. Unnecessary vortices around the vanes were also eliminated by changing the number of vanes from four to six.

  2. Considerations in designing a centrifugal atomiser for metal powder production

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Y.Y. [Department of Engineering, The University of Liverpool, Liverpool L69 3GH (United Kingdom)]. E-mail:


    In centrifugal atomisation for metal powder production, the key to the control of the particle sizes is the design of the atomiser. This paper studies the main issues concerned in designing a centrifugal atomiser and provides guidance on the selection of an electric motor, radius of atomiser, slope angle of atomiser wall and flow rate of cooling water. In the selection of the atomiser radius, the power and material constraints as well as the hydraulic jump radius need to be considered. A cup atomiser with a slope angle of 60-70{sup o} would result in small spray droplets and thus a fine powder. The water cooling system needs to be assessed by examining the heat flow in the solid metal layer and in the atomiser.

  3. Production of centrifugal fields greater than 100 million times gravity. (United States)

    Katano, R; Shimizu, S


    A high-speed rotation instrument to produce centrifugal fields greater than 100 million times gravity has been constructed. Small, solid, spherical high-carbon chromium steel rotors are suspended magnetically in high vacuum and spun by a rotating magnetic field. It is found that the spinning rotor explodes when the calculated average value of stress in the meridian plane reaches about 1.2 times the tensile strength of the material. The maximum speed of rotation so far achieved for more than a few days without bursting was obtained with a rotor of 1.50 mm diameter. The speed of 2.11 x 10(5) rev/s corresponded to a centrifugal field of 1.34 x 10(8) times gravity. Our instrument will find application in the study of nuclear atomic phenomena.

  4. Operation of Droplet-Microfluidic Devices with a Lab Centrifuge

    Directory of Open Access Journals (Sweden)

    Noorsher Ahmed


    Full Text Available Microfluidic devices are valuable for a variety of biotechnology applications, such as synthesizing biochemical libraries, screening enzymes, and analyzing single cells. However, normally, the devices are controlled using specialized pumps, which require expert knowledge to operate. Here, we demonstrate operation of poly(dimethylsiloxane devices without pumps. We build a scaffold that holds the device and reagents to be infused in a format that can be inserted into a 50 mL falcon tube and spun in a common lab centrifuge. By controlling the device design and centrifuge spin speed, we infuse the reagents at controlled flow rates. We demonstrate the encapsulation and culture of clonal colonies of red and green Escherichia coli in droplets seeded from single cells.

  5. Centrifuge Modeling of Piles Subjected to Lateral Loads (United States)

    Brant, Logan; Ling, Hoe I.

    There are many applications where piles are employed to absorb and deflect lateral impact loads. Structural elements of this type are used to protect infrastructure and are commonly found at marine sites. A series of model tests have been conducted using Columbia University's centrifuge facility to better understand the performance of piles subjected to these loading conditions. A device was designed to install and laterally load single model piles during centrifuge flight. This device uniquely contains two lateral loading systems, one which allows static testing and another appropriate for dynamic tests. This research examines the behavior of tubular steel piles embedded within dry or saturated soil and subjected to varied rates of lateral loading. This investigation provides insight on the contribution of lateral loading rates to the behavior of piles.

  6. 试验环境条件对离心机稳定性影响分析%Analysis of the influence of environmental conditions on centrifuge stability

    Institute of Scientific and Technical Information of China (English)

    王世明; 刘雨; 任顺清


    The impact of external environmental factors on centrifuge stability was analyzed under working condition,and the influences of environmental temperature,angular inclination modification and linear vibration of foundation on the specific force generated by centrifuge were discussed respectively.The results show that three kinds of errors should be real-time monitored and measured while inertial devices are calibrated on the centrifuge,and the calibration accuracy of inertial devices on centrifuge can be improved through making compensation for these errors.%对精密离心机工作的外部环境因素对离心机稳定性影响进行分析,讨论环境温度变化、地基倾角变化及地基线振动对离心机提供的输入比力影响,结果表明实际离心机试验时需对3项误差进行实时监测,补偿各项误差后可提高离心机惯性器件标定精度。

  7. Scalp psoriasis associated with central centrifugal cicatricial alopecia

    Directory of Open Access Journals (Sweden)

    Krista N. Larson


    Full Text Available Scalp psoriasis is a very common dermatological condition with a variety of presentations, but only rarely presents as severe alopecia. We present a case of a 50-year-old female with many years of recalcitrant hair loss that was thought to be secondary to central centrifugal cicatricial alopecia which was later diagnosed as psoriasis. This case highlights an interesting presentation and rare complication of a common disease.

  8. Dynamical system analysis of unstable flow phenomena in centrifugal blower

    Directory of Open Access Journals (Sweden)

    Garcia David


    Full Text Available Methods of dynamical system analysis were employed to analyze unsteady phenomena in a centrifugal blower. Pressure signals gathered at different control points were decomposed into their Principal Components (PCs by means of Singular Spectrum Analysis (SSA. Certain number of PCs was considered in the analysis based on their statistical correlation. Projection of the original signal onto its PCs allowed to draw the phase trajectory that clearly separated non-stable blower working conditions from its regular operation.

  9. A Review of Centrifugal Testing of Gasoline Contamination and Remediation


    Jay N. Meegoda; Liming Hu


    Leaking underground storage tanks (USTs) containing gasoline represent a significant public health hazard. Virtually undetectable to the UST owner, gasoline leaks can contaminate groundwater supplies. In order to develop remediation plans one must know the extent of gasoline contamination. Centrifugal simulations showed that in silty and sandy soils gasoline moved due to the physical process of advection and was retained as a pool of free products above the water table. However, in clayey soi...

  10. Computational and Experimental Study of an Industrial Centrifugal Compressor Volute

    Institute of Scientific and Technical Information of China (English)

    HarriPitkanen; HannuEsa; 等


    A centrifugal compressor with a vaneless diffuser was studied experimentally and numericallly.The main target of the study was to analyze the volute flow.Two different volute geometries was studied.The numerical solution was done by using a steady-state RANS code at both design and off-design conditions.Both calculated and measured pressure and velocity distributions are presented.

  11. Centrifuge modeling of rocking-isolated inelastic RC bridge piers


    Loli, Marianna; Knappett, Jonathan A; Brown, Michael J.; Anastasopoulos, Ioannis; GAZETAS, George


    Experimental proof is provided of an unconventional seismic design concept, which is based on deliberately underdesigning shallow foundations to promote intense rocking oscillations and thereby to dramatically improve the seismic resilience of structures. Termed rocking isolation, this new seismic design philosophy is investigated through a series of dynamic centrifuge experiments on properly scaled models of a modern reinforced concrete (RC) bridge pier. The experimental method reproduces th...

  12. Centrifugal stretching of 170Hf in the interacting boson model

    Directory of Open Access Journals (Sweden)

    Werner V.


    Full Text Available We present the results of a recent experiment to deduce lifetimes of members of the ground state rotational band of 170Hf, which show the effect of centrifugal stretching in this deformed isotope. Results are compared to the geometrical confined beta-soft(CBS rotor model, as well as to the interacting boson model (IBM. Two methods to correct for effects due to the finite valence space within the IBM are proposed.

  13. Comparative hemolysis study of clinically available centrifugal pumps. (United States)

    Naito, K; Suenaga, E; Cao, Z L; Suda, H; Ueno, T; Natsuaki, M; Itoh, T


    Centrifugal pumps have become important devices for cardiopulmonary bypass and circulatory assistance. Five types of centrifugal pumps are clinically available in Japan. To evaluate the blood trauma caused by centrifugal pumps, a comparative hemolysis study was performed under identical conditions. In vitro hemolysis test circuits were constructed to operate the BioMedicus BP-80 (Medtronic, BioMedicus), Sarns Delphin (Sarns/3M Healthcare), Isoflow (St. Jude Medical [SJM]), HPM-15 (Nikkiso), and Capiox CX-SP45 (Terumo). The hemolysis test loop consisted of two 1.5 m lengths of polyvinyl chloride tubing with a 3/8-inch internal diameter, a reservoir with a sampling port, and a pump head. All pumps were set to flow at 6 L/min against the total pressure head of 120 mm Hg. Experiments were conducted simultaneously for 6 h at room temperature (21 degrees C) with fresh bovine blood. Blood samples for plasma-free hemoglobin testing were taken, and the change in temperature at the pump outlet port was measured during the experiment. The mean pump rotational speeds were 1,570, 1,374, 1,438, 1,944, and 1,296 rpm, and the normalized indexes of hemolysis were 0.00070, 0.00745, 0.00096, 0.00066, 0.00090 g/100 L for the BP-80, Sarns, SJM, Nikkiso, and Terumo pumps, respectively. The change in temperature at the pump outlet port was the least for the Nikkiso pump (1.8 degrees C) and the most with the SJM pump (3.8 degrees C). This study showed that there is no relationship between the pump rotational speed (rpm) and the normalized index of hemolysis in 5 types of centrifugal pumps. The pump design and number of impellers could be more notable factors in blood damage.

  14. Prenatal centrifugation: A model for fetal programming of adult weight? (United States)

    Baer, Lisa A.; Rushing, Linda; Wade, Charles E.; Ronca, April E.


    'Fetal programming' is a newly emerging field that is revealing astounding insights into the prenatal origins of adult disease, including metabolic, endocrine, and cardiovascular pathophysiology. In the present study, we tested the hypothesis that rat pups conceived, gestated and born at 2-g have significantly reduced birth weights and increased adult body weights as compared to 1-g controls. Offspring were produced by mating young adult male and female rats that were adapted to 2-g centrifugation. Female rats underwent conception, pregnancy and birth at 2-g. Newborn pups in the 2-g condition were removed from the centrifuge and fostered to non-manipulated, newly parturient dams maintained at 1-g. Comparisons were made with 1-g stationary controls, also cross- fostered at birth. As compared to 1-g controls, birth weights of pups gestated and born at 2-g were significantly reduced. Pup body weights were significantly reduced until Postnatal day (P)12. Beginning on P63, body weights of 2-g-gestated offspring exceeded those of 1-g controls by 7-10%. Thus, prenatal rearing at 2-g restricts neonatal growth and increases adult body weight. Collectively, these data support the hypothesis that 2-g centrifugation alters the intrauterine milieu, thereby inducing persistent changes in adult phenotype.

  15. Numerical Analysis and Centrifuge Modeling of Shallow Foundations

    Institute of Scientific and Technical Information of China (English)

    罗强; 栾茂田; 杨蕴明; 王忠涛; 赵守正


    The influence of non-coaxial constitutive model on predictions of dense sand behavior is investigated in this paper. The non-coaxial model with strain softening plasticity is applied into finite-element program ABAQUS, which is first used to predict the stress-strain behavior and the non-coaxial characteristic between the orientations of the principal stress and principal plastic strain rate in simple shear tests. The model is also used to predict load settlement responses and bearing capacity factors of shallow foundations. A series of centrifuge tests for shallow foundations on saturated dense sand are performed under drained conditions and the test results are compared with the corresponding numerical results. Various footing dimensions, depths of embedment, and footing shapes are considered in these tests. In view of the load settlement relationships, the stiffness of the load-displacement curves is significantly affected by the non-coaxial model compared with those predicted by the coaxial model, and a lower value of non-coaxial modulus gives a softer response. Considering the soil behavior at failure, the coaxial model predictions of bearing capacity factors are more advanced than those of centrifuge test results and the non-coaxial model results;besides, the non-coaxial model gives better predictions. The non-coaxial model predictions are closer to those of the centrifuge results when a proper non-coaxial plastic modulus is chosen.

  16. Subchronic centrifugal mechanical assist in an unheparinized calf model. (United States)

    Wagner-Mann, C; Curtis, J; Mann, F A; Turk, J; Demmy, T; Turpin, T


    The purpose of this study was to determine whether the major centrifugal pumps currently in use in the United States (Medtronic, BioMedicus BioPump and Carmeda-coated BioPump, Sarns 3M centrifugal pump, and St. Jude Medical Lifestream) could function as left mechanical assist devices in the subchronic (72 h) unheparinized calf model. Calves were instrumented for left atrial to aorta ex vivo assist, and the pump flow was set at 3.5 +/- 0.4 L/min. Two calves (Sarns 3M and St. Jude) survived 72 h of pumping without clinical complications. The other 2 calves died at 62 and 66 h (Medtronic BioPump and Carmeda-coated BioPump, respectively); both had pelvic limb paralysis. The seal of the Sarns 3M pump head ruptured after approximately 36 h of pumping and required replacement. On postmortem examination, pump-associated thromboembolic lesions were detected in 3 of the 4 calves in one or more of the following organs: kidneys, pancreas, abomasum, duodenum, ileum, spleen, and lumbar spinal cord. The calf with the Sarns 3M pump had no discernable lesions. Because of the clinical abnormalities and postmortem lesions in the unheparinized calf model, it was suggested that anticoagulation is necessary for conducting centrifugal mechanical assist studies in calves using presently available technology.

  17. Modelling of horizontal centrifugal casting of work roll (United States)

    Xu, Zhian; Song, Nannan; Tol, Rob Val; Luan, Yikun; Li, Dianzhong


    A numerical model to simulate horizontal centrifugal roll castings is presented in this paper. In order to simulate the flow fluid and solidification of horizontal centrifugal roll casting correctly, the model uses a body fitted mesh technique to represent the geometry. This new method maps a plate layer mesh to a circular mesh. The smooth body fitted mesh method gives more accurate calculation results for cylindrical geometries. A velocity depending on the angular velocity and inner radius of the mould is set up as a velocity boundary condition. The fluid flow coupled with heat transfer and solidification in a rapidly rotating roll is simulated. A gravity free falling method is applied as a pouring condition. A moveable pouring system is also used in the simulations. High speed steel is used to produce the work roll. Two different gating positions and a moveable gating system are simulated in this paper. Results show that the position of pouring system has a significant influence on the temperature distribution. The temperature distribution at a fixed central pouring system is more favourable than the distribution from a side pouring system. A moving gating system method is a better way to obtain a uniform temperature field in centrifugal casting and offers an alternative for existing techniques.

  18. Bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump. (United States)

    Kosaka, Ryo; Yoshida, Fumihiko; Nishida, Masahiro; Maruyama, Osamu; Kawaguchi, Yasuo; Yamane, Takashi


    The purpose of the present study is to investigate a bearing gap adjustment for improvement of levitation performance in a hydrodynamically levitated centrifugal blood pump to realize a blood pump with a low hemolysis level. The impeller levitates axially by balancing a gravitational force, buoyancy, a magnetic force, and hydrodynamic forces on the top and bottom sides of the impeller. To adjust the levitation position of the impeller, the balance of acting forces on the impeller was adjusted by changing the shroud area on the bottom impeller. Three pumps having various shroud area were prepared as tested models: 817 mm(2) (HH-S), 875 mm(2) (HH-M) and 931 mm(2) (HH-L). First, for evaluating the bearing gap adjustment, the bearing gap was estimated by calculating a balancing position of the acting forces on the impeller. We actually measured the gravitational force, buoyancy and the magnetic force, and numerically analyzed hydrodynamic forces on the top and bottom sides of the impeller. Second, to verify accuracy of the estimated bearing gap, the measurement test of the bearing gap was performed. Finally, an in-vitro hemolysis test was performed to evaluate a hemolysis level of the pump. As a result, bottom bearing gaps were estimated as 40 μm (HH-S), 60 μm (HH-M) and 238 μm (HH-L). In the measurement test, bottom bearing gaps were measured as 63 μm (HH-S), 219 μm (HH-M), and 231 μm (HH-L). The estimated bearing gaps had positively correlated with the measured bearing gaps in relation to the shroud area on the impeller. In the hemolysis test, hemolysis level in every model was almost equivalent to that of BPX-80, when the bearing gap was adjusted greater than 60 μm. We could adjust the bearing gap by changing the shroud area on the impeller for improvement of levitation performance to realize a blood pump with a low hemolysis level.

  19. Microstructures of Al-Al3Ti functionally graded materials fabricated by centrifugal solid-particle method and centrifugal in situ method (United States)

    Watanabe, Yoshimi; Zhou, Qi; Sato, Hisashi; Fujii, Toshiyuki; Inamura, Tomonari


    Methods of fabrication by centrifugal casting for functionally graded materials (FGMs) can be classified into two categories on the basis of the relationship between the process temperature and the liquidus temperature of a master alloy. They are the centrifugal solid-particle method and centrifugal in situ method, which could be carried out at process temperatures lower and higher than the liquidus temperature of the master alloy, respectively. In a previous study, it was found that the microstructures of Al-Al3Ti FGMs fabricated by the centrifugal in situ method processed at 1600 °C were different from those fabricated by the centrifugal solid-particle method processed at 800 °C. Although it is expected that the FGMs fabricated by the centrifugal in situ method processed at approximately the liquidus temperature should show extraordinary microstructures, those microstructures have not been observed. In this study, the microstructures of Al-Al3Ti FGMs fabricated at 1000 °C (centrifugal solid-particle method) and 1200 °C (centrifugal in situ method) were investigated.

  20. Water Drainage from Unsaturated Soils in a Centrifuge Permeameter (United States)

    Ornelas, G.; McCartney, J.; Zhang, M.


    This study involves an analysis of water drainage from an initially saturated silt layer in a centrifuge permeameter to evaluate the hydraulic properties of the soil layer in unsaturated conditions up to the point where the water phase becomes discontinuous. These properties include the soil water retention curve (SWRC) and the hydraulic conductivity function (HCF). The hydraulic properties of unsaturated silt are used in soil-atmosphere interaction models that take into account the role of infiltration and evaporation of water from soils due to atmospheric interaction. These models are often applied in slope stability analyses, landfill cover design, aquifer recharge analyses, and agricultural engineering. The hydraulic properties are also relevant to recent research concerning geothermal heating and cooling, as they can be used to assess the insulating effects of soil around underground heat exchangers. This study employs a high-speed geotechnical centrifuge to increase the self-weight of a compacted silt specimen atop a filter plate. Under a centrifuge acceleration of N times earth's gravity, the concept of geometric similitude indicates that the water flow process in a small-scale soil layer will be similar to those in a soil layer in the field that is N times thicker. The centrifuge acceleration also results in an increase in the hydraulic gradient across the silt specimen, which causes water to flow out of the pores following Darcy's law. The drainage test was performed until the rate of liquid water flow out of the soil layer slowed to a negligible level, which corresponds to the transition point at which further water flow can only occur due to water vapor diffusion following Fick's law. The data from the drainage test in the centrifuge were used to determine the SWRC and HCF at different depths in the silt specimen, which compared well with similar properties defined using other laboratory tests. The transition point at which liquid water flow stopped (and

  1. Labor Force (United States)

    Occupational Outlook Quarterly, 2012


    The labor force is the number of people ages 16 or older who are either working or looking for work. It does not include active-duty military personnel or the institutionalized population, such as prison inmates. Determining the size of the labor force is a way of determining how big the economy can get. The size of the labor force depends on two…

  2. Improvement of hemocompatibility for hydrodynamic levitation centrifugal pump by optimizing step bearings. (United States)

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi


    We have developed a hydrodynamic levitation centrifugal blood pump with a semi-open impeller for a mechanically circulatory assist. The impeller levitated with original hydrodynamic bearings without any complicated control and sensors. However, narrow bearing gap has the potential for causing hemolysis. The purpose of the study is to investigate the geometric configuration of the hydrodynamic step bearing to minimize hemolysis by expansion of the bearing gap. Firstly, we performed the numerical analysis of the step bearing based on Reynolds equation, and measured the actual hydrodynamic force of the step bearing. Secondly, the bearing gap measurement test and the hemolysis test were performed to the blood pumps, whose step length were 0 %, 33 % and 67 % of the vane length respectively. As a result, in the numerical analysis, the hydrodynamic force was the largest, when the step bearing was around 70 %. In the actual evaluation tests, the blood pump having step 67 % obtained the maximum bearing gap, and was able to improve the hemolysis, compared to those having step 0% and 33%. We confirmed that the numerical analysis of the step bearing worked effectively, and the blood pump having step 67 % was suitable configuration to minimize hemolysis, because it realized the largest bearing gap.

  3. Dispersion Forces

    CERN Document Server

    Buhmann, Stefan Yoshi


    In this book, a modern unified theory of dispersion forces on atoms and bodies is presented which covers a broad range of advanced aspects and scenarios. Macroscopic quantum electrodynamics is shown to provide a powerful framework for dispersion forces which allows for discussing general properties like their non-additivity and the relation between microscopic and macroscopic interactions. It is demonstrated how the general results can be used to obtain dispersion forces on atoms in the presence of bodies of various shapes and materials. Starting with a brief recapitulation of volume I, this volume II deals especially with bodies of irregular shapes, universal scaling laws, dynamical forces on excited atoms, enhanced forces in cavity quantum electrodynamics, non-equilibrium forces in thermal environments and quantum friction. The book gives both the specialist and those new to the field a thorough overview over recent results in the field. It provides a toolbox for studying dispersion forces in various contex...

  4. Microfluidic Integration of a Cloth-Based Hybridization Array System (CHAS) for Rapid, Colorimetric Detection of Enterohemorrhagic Escherichia coli (EHEC) Using an Articulated, Centrifugal Platform. (United States)

    Geissler, Matthias; Clime, Liviu; Hoa, Xuyen D; Morton, Keith J; Hébert, Harold; Poncelet, Lucas; Mounier, Maxence; Deschênes, Mylène; Gauthier, Martine E; Huszczynski, George; Corneau, Nathalie; Blais, Burton W; Veres, Teodor


    We describe the translation of a cloth-based hybridization array system (CHAS), a colorimetric DNA detection method that is used by food inspection laboratories for colony screening of pathogenic agents, onto a microfluidic chip format. We also introduce an articulated centrifugal platform with a novel fluid manipulation concept based on changes in the orientation of the chip with respect to the centrifugal force field to time the passage of multiple components required for the process. The platform features two movable and motorized carriers that can be reoriented on demand between 0 and 360° during stage rotation. Articulation of the chip can be used to trigger on-the-fly fluid dispensing through independently addressable siphon structures or to relocate solutions against the centrifugal force field, making them newly accessible for downstream transfer. With the microfluidic CHAS, we achieved significant reduction in the size of the cloth substrate as well as the volume of reagents and wash solutions. Both the chip design and the operational protocol were optimized to perform the entire process in a reliable, fully automated fashion. A demonstration with PCR-amplified genomic DNA confirms on-chip detection and identification of Escherichia coli O157:H7 from colony isolates in a colorimetric multiplex assay using rfbO157, fliCH7, vt1, and vt2 genes.

  5. Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

    Directory of Open Access Journals (Sweden)

    Elizabeth I. Braun


    Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

  6. Topological analysis of the formation of Jet-Wake flow pattern in centrifugal impeller channel

    Institute of Scientific and Technical Information of China (English)

    ZHENG Qun; LIU Shun-long


    Topological analyses are carried out for the numerical results of internal flow field in centrifugal impeller. Topological rules of the singular point characteristics of the limiting streamline are derived and used to determine three dimensional separation patterns in centrifugal impeller and to verify the numerical results. The results reveal that the wake is saddle to nodal closed separation and the formation, its onset point and its developing process of Jet-Wake Flow pattern in centrifugal impeller are presented in this paper.

  7. Mathematical model of the component mixture distribution in the molten cast iron during centrifugation (sedimentation) (United States)

    Bikulov, R. A.; Kotlyar, L. M.


    For the development and management of the manufacturing processes of axisymmetric articles with compositional structure by centrifugal casting method [1,2,3,4] is necessary to create a generalized mathematical model of the dynamics of component mixture in the molten cast iron during centrifugation. In article. based on the analysis of the dynamics of two-component mixture at sedimentation, a method of successive approximations to determine the distribution of a multicomponent mixture by centrifugation in a parabolic crucible is developed.

  8. Methods of observation of the centrifugal quantum states of neutrons (United States)

    Cubitt, R.; Nesvizhevsky, V. V.; Petukhov, A. K.; Voronin, A. Yu.; Pignol, G.; Protasov, K. V.; Gurshijants, P.


    We propose methods for observation of the quasi-stationary states of neutrons, localized near a curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror's optical potential. This phenomenon is an example of an exactly solvable "quantum bouncer" problem that can be studied experimentally. It could provide a new tool for studying fundamental neutron-matter interactions, neutron quantum optics and surface physics effects. The feasibility of observation of such quantum states has been proven in first experiments.

  9. Methods of observation of the centrifugal quantum states of neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cubitt, R. [Institut Laue-Langevin (ILL), 6 rue Jules Horowitz, F-38042 Grenoble (France); Nesvizhevsky, V.V., E-mail: nesvizhevsky@ill.e [Institut Laue-Langevin (ILL), 6 rue Jules Horowitz, F-38042 Grenoble (France); Petukhov, A.K. [Institut Laue-Langevin (ILL), 6 rue Jules Horowitz, F-38042 Grenoble (France); Voronin, A.Yu., E-mail: [P.N. Lebedev Physical Institute, 53 Leninsky Prospekt, 119991 Moscow (Russian Federation); Pignol, G.; Protasov, K.V. [Laboratoire de Physique Subatomique et de Cosmologie (LPSC), IN2P3-CNRS, UJF, 53, Avenue des Martyrs, F-38026 Grenoble (France); Gurshijants, P. [Institute of Solid State Physics (ISSP), Institutskaya Street 2, 142432 Chernogolovka, Moscow Region (Russian Federation)


    We propose methods for observation of the quasi-stationary states of neutrons, localized near a curved mirror surface. The bounding effective well is formed by the centrifugal potential and the mirror's optical potential. This phenomenon is an example of an exactly solvable 'quantum bouncer' problem that can be studied experimentally. It could provide a new tool for studying fundamental neutron-matter interactions, neutron quantum optics and surface physics effects. The feasibility of observation of such quantum states has been proven in first experiments.

  10. Capture into resonance and phase space dynamics in optical centrifuge

    CERN Document Server

    Armon, Tsafrir


    The process of capture of a molecular enesemble into rotational resonance in the optical centrifuge is investigated. The adiabaticity and phase space incompressibility are used to find the resonant capture probability in terms of two dimensionless parameters P1,P2 characterising the driving strength and the nonlinearity, and related to three characteristic time scales in the problem. The analysis is based on the transformation to action-angle variables and the single resonance approximation, yielding reduction of the three-dimensional rotation problem to one degree of freedom. The analytic results for capture probability are in a good agreement with simulations. The existing experiments satisfy the validity conditions of the theory.

  11. Centrifugal experimental study of suction bucket foundations under dynamic loading (United States)

    Lu, Xiaobing; Wu, Yongren; Jiao, Bintian; Wang, Shuyun


    Centrifugal experiments were carried out to investigate the responses of suction bucket foundations under horizontal and vertical dynamic loading. It is shown that when the loading amplitude is over a critical value, the sand at the upper part around the bucket is softened or even liquefied. The excess pore pressure decreases from the upper part to the lower part of the sand layer in the vertical direction and decreases radially from the bucket’s side wall in the horizontal direction. Large settlements of the bucket and the sand layer around the bucket are induced by dynamic loading. The dynamic responses of the bucket with smaller height (the same diameter) are heavier.

  12. Silver nanodisks: size selection via centrifugation and optical properties. (United States)

    Germain, V; Brioude, A; Ingert, D; Pileni, M P


    Silver nanodisks, having two different sizes, and spherical particles are synthesized by soft chemistry. By using centrifugation, nanodisks are mainly selected. The experimental absorption spectra of these nanodisks with different sizes are compared to those simulated using the discrete dipole approximation method. For small nanodisk sizes, the nanodisk shape is neglected and the simulated spectra closest to the experiments are obtained by assuming a spheroidal particle. Conversely, for larger nanodisks, the precise geometries represented by snip and aspect ratio are needed for good agreement between experiments and simulations.

  13. Multi-stage mixer-settler planet centrifuge. Preliminary studies on partition of macromolecules with organic-aqueous and aqueous-aqueous two-phase solvent systems. (United States)

    Ito, Y; Zhang, T Y


    A rotary-seal-free planetary centrifuge holds a separation column which consists of multiple partition units (ca. 200) connected in series with transfer tubes. In the cavity of each partition unit the transfer tube extends to form a mixer which vibrates to stir the contents under an oscillating force field generated by the planetary motion of the centrifuge. Consequently, solutes locally introduced at the inlet of the column are subjected to an efficient partition process in each partition unit and separated according to their partition coefficients. The mixer tube equipped with a flexible silicone rubber joint was found to produce excellent results for partition with viscous polymer phase systems. The capability of the method was demonstrated on separation of cytochrome c and lysozyme using a PEG-aqueous dibasic potassium phosphate-aqueous two-phase solvent system.

  14. Characteristics of backflow vortex cavitation in screw centrifugal pump%螺旋离心泵内回流涡空化特性

    Institute of Scientific and Technical Information of China (English)

    邓育轩; 李仁年; 韩伟; 杨文洁; 李正贵; 张毅鹏


    Screw centrifugal pump has swirling backflow under a wide range of flow rates. The backflow vortex structure occurs in the shear layer between the main flow and the swirling backflow. The pressure at the core of a backflow vortex is lower than the ambient pressure due to the centrifugal force on the vertical flow which results in cavitation if the core pressure becomes lower than the vapor pressure. This is called backflow vortex cavitation. In order to study the backflow vortex cavitation, a screw centrifugal pump was designed for experimental studies. The clearance between vane rim and cover plate was 2.9 mm in this screw centrifugal pump. By using the high speed video picture, we observed two backflow vortex cavitation clouds extending upstream from the tip at the screw centrifugal pump inlet, covering a wide range of flow rates. We also found that under a certain net positive suction head (NPSH), i.e., when the flow rate was decreased, the volume of the two backflow vortex cavitation cloud was decreased. Experimental studies on the backflow vortex cavitation from this screw centrifugal pump have provided novel insight of the characteristics of backflow vortex cavitation, but the limited information has not lead to the complete understanding of the phenomena. In addition to blade surface and backflow vortex cavitations, tip leakage cavitation occurred for screw centrifugal pump with tip clearance. With these types of cavitation, the flow in a screw centrifugal pump presented a very complicated three-dimensional structure. Since experiment results give limited information, numerical simulation plays an important role to further understand such complicate flow phenomena. Using the CFD code, the fundamental characteristics of the backflow vortex cavitation was investigated in detail. It was found that the backflow vortices were formed in a circumferentially twisted manner at the boundary between the swirling backflow and the straight inlet flow. When the flow rate

  15. The Monitoring Of Running Stability For The Tripod Type Centrifuge%三足式离心机运行稳定性的监控

    Institute of Scientific and Technical Information of China (English)



    The tripod type centrifuge is widely used for the production department of light industry, chemical industry, medicine and metallurgy etc. It is a kind of equipment which is used to separate solid particles or crystals from solutions or mixed liquid. The running stability of this kind of centrifuge is depended on the water-penetrability of separated liquid. To a liquid with good water-penetrability, materials have entered onto a screen grate which always carries an eccentric load by reason of an uneven distribution,so that the suspended materials have created the disturbing dynamic source of centrifuge caused by centrifugal forces. When the disturbing forces have increased with the eccentric load of materials to reach at a certain degree, the suspended materials, will tumble down and the centrifuge will appear unstable in running state. This phenomenon has become a problem child of tripod type centrifuge.%三足式离心机广泛应用于轻工、化工、医疗以及冶金工业等生产部门,是从溶液中分离出晶体或固体颗粒的一种设备。该型离心机的运行稳定性,取决于被分离液体的透水性。对于透水性良好的物料,进入筛栏后往往分布不均形成偏载,由此产生的离心力构成了对离心机机体运行的扰动力源,当此力源强度随偏载量达到一定程度后,机体将产生倾翻,离心机将出现运行失稳,这种现象已成为三足式离心机运行中的一个急需解决的问题。

  16. Determination of strength behaviour of slope supported by vegetated crib walls using centrifuge model testing (United States)

    Sudan Acharya, Madhu


    The crib retaining structures made of wooden/bamboo logs with live plants inside are called vegetative crib walls which are now becoming popular due to their advantages over conventional civil engineering walls. Conventionally, wooden crib walls were dimensioned based on past experiences. At present, there are several guidelines and design standards for machine finished wooden crib walls, but only few guidelines for the design and construction of vegetative log crib walls are available which are generally not sufficient for an economic engineering design of such walls. Analytical methods are generally used to determine the strength of vegetated crib retaining walls. The crib construction is analysed statically by satisfying the condition of static equilibrium with acceptable level of safety. The crib wall system is checked for internal and external stability using conventional monolithic and silo theories. Due to limitations of available theories, the exact calculation of the strength of vegetated wooden/bamboo crib wall cannot be made in static calculation. Therefore, experimental measurements are generally done to verify the static analysis. In this work, a model crib construction (1:20) made of bamboo elements is tested in the centrifuge machine to determine the strength behaviour of the slope supported by vegetated crib retaining wall. A geotechnical centrifuge is used to conduct model tests to study geotechnical problems such as the strength, stiffness and bearing capacity of different structures, settlement of embankments, stability of slopes, earth retaining structures etc. Centrifuge model testing is particularly well suited to modelling geotechnical events because the increase in gravitational force creates stresses in the model that are equivalent to the much larger prototype and hence ensures that the mechanisms of ground movements observed in the tests are realistic. Centrifuge model testing provides data to improve our understanding of basic mechanisms

  17. Size-isolation of ultrasound-mediated phase change perfluorocarbon droplets using differential centrifugation. (United States)

    Mercado, Karla P; Radhakrishnan, Kirthi; Stewart, Kyle; Snider, Lindsay; Ryan, Devin; Haworth, Kevin J


    Perfluorocarbon droplets that are capable of an ultrasound-mediated phase transition have applications in diagnostic and therapeutic ultrasound. Techniques to modify the droplet size distribution are of interest because of the size-dependent acoustic response of the droplets. Differential centrifugation has been used to isolate specific sizes of microbubbles. In this work, differential centrifugation was employed to isolate droplets with diameters between 1 and 3 μm and 2 and 5 μm from an initially polydisperse distribution. Further, an empirical model was developed for predicting the droplet size distribution following differential centrifugation and to facilitate the selection of centrifugation parameters for obtaining desired size distributions.

  18. High Order Centrifugal Distortion Corrections to Energy Levels of Asymmetric Top Molecules

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-Yan; LIU Xiao-Yong; LIU Hong-Ping; GUO Yuan-Qing; HUANG Guang-Ming; LIN Jie-Li; GAO Hui


    High order centrifugal distortion terms have been derived and added to the effective Hamiltonian of asymmetric top molecules. Based on this Hamiltonian, a program in Fortran 77 has been developed for spectral analysis of asymmetric top molecules. The high order centrifugal distortion terms are found to be non-negligible even for the low-lying rotational transitions of molecules, such as Ha 18O, subjected to severe centrifugal distortion effect,and for the high-lying rotational transitions of molecules, such as 14N16O2 subjected to the moderate centrifugal distortion effect.

  19. Dinâmicas centrípetas e centrífugas na formação do Estado monárquico no Brasil: o papel do Conselho Geral da Província de São Paulo Centripetal and centrifugal forces in the creation of the monarchic state in Brazil: the role of the General Council of the Province of São Paulo

    Directory of Open Access Journals (Sweden)

    Marisa Saenz Leme


    Full Text Available O presente artigo avalia a formação e o funcionamento do Conselho Geral da Província de São Paulo durante o Primeiro Império. Organismo previsto na Constituição de 1824, com funções que podem ser consideradas um embrião do Poder Legislativo provincial, organizou-se efetivamente na província de São Paulo em 1828, quando o governo de D. Pedro I já se desgastava. O significado de sua existência no contexto das dinâmicas centrífugas e centrípetas atuantes na primeira construção do Estado no Brasil independente constituem o principal objetivo da presente análise.The present article examines the creation and development of São Paulo Provincial General Council during the First Empire of Brazil. As outlined in the Brazilian Constitution of 1824, the organ had functions that can be viewed as an embryonic provincial legislative power, and was actually established in the Province of São Paulo by 1828, when the government of Dom Pedro I was already becoming exhausted. The main focus of the present analysis is the significance of the Council's existence in the midst of the centrifugal and centripetal dynamics acting during the creation of Brazil's first independent state.

  20. Methodology for optimally sized centrifugal partition chromatography columns. (United States)

    Chollet, Sébastien; Marchal, Luc; Jérémy Meucci; Renault, Jean-Hugues; Legrand, Jack; Foucault, Alain


    Centrifugal Partition Chromatography (CPC) is a separation process based on the partitioning of solutes between two partially miscible liquid phases. There is no solid support for the stationary phase. The centrifugal acceleration is responsible for both stationary phase retention and mobile phase dispersion. CPC is thus a process based on liquid-liquid mass transfer. The separation efficiency is mainly influenced by the hydrodynamics of the phases in each cell of the column. Thanks to a visualization system, called "Visual CPC", it was observed that the mobile phase can flow through the stationary phase as a sheet, or a spray. Hydrodynamics, which directly governs the instrument efficiency, is directly affected during scale changes, and non-linear phenomena prevent the successful achievement of mastered geometrical scale changes. In this work, a methodology for CPC column sizing is proposed, based on the characterization of the efficiency of advanced cell shapes, taking into account the hydrodynamics. Knowledge about relationship between stationary phase volume, cell efficiency and separation resolution in CPC allowed calculating the optimum cell number for laboratory and industrial scale CPC application. The methodology is highlighted with results on five different geometries from 25 to 5000 mL, for two applications: the separation of alkylbenzene by partitioning with heptane/methanol/water biphasic system; and the separation of peptides by partitioning with n-butanol/acetic acid/water (4/1/5) biphasic system. With this approach, it is possible to predict the optimal CPC column length leading to highest productivity.

  1. Design Attributes and Scale Up Testing of Annular Centrifugal Contactors

    Energy Technology Data Exchange (ETDEWEB)

    David H. Meikrantz; Jack D. Law


    Annular centrifugal contactors are being used for rapid yet efficient liquid- liquid processing in numerous industrial and government applications. Commercialization of this technology began eleven years ago and now units with throughputs ranging from 0.25 to 700 liters per minute are readily available. Separation, washing, and extraction processes all benefit from the use of this relatively new commercial tool. Processing advantages of this technology include: low in-process volume per stage, rapid mixing and separation in a single unit, connection-in-series for multi-stage use, and a wide operating range of input flow rates and phase ratios without adjustment. Recent design enhancements have been added to simplify maintenance, improve inspection ability, and provide increased reliability. Cartridge-style bearing and mechanical rotary seal assemblies that can include liquid-leak sensors are employed to enhance remote operations, minimize maintenance downtime, prevent equipment damage, and extend service life. Clean-in-place capability eliminates the need for disassembly, facilitates the use of contactors for feed clarification, and can be automated for continuous operation. In nuclear fuel cycle studies, aqueous based separations are being developed that efficiently partition uranium, actinides, and fission products via liquid-liquid solvent extraction. Thus, annular centrifugal contactors are destined to play a significant role in the design of such new processes. Laboratory scale studies using mini-contactors have demonstrated feasibility for many such separation processes but validation at an engineering scale is needed to support actual process design.

  2. Design and Characterization of a Centrifugal Compressor Surge Test Rig

    Directory of Open Access Journals (Sweden)

    Kin Tien Lim


    Full Text Available A detailed description of a new centrifugal compressor surge test rig is presented. The objective of the design and development of the rig is to study the surge phenomenon in centrifugal compression systems and to investigate a novel method of surge control by active magnetic bearing servo actuation of the impeller axial tip clearance. In this paper, we focus on the design, initial setup, and testing of the rig. The latter two include the commissioning of the rig and the experimental characterization of the compressor performance. The behavior of the compressor during surge is analyzed by driving the experimental setup into surge. Two fundamental frequencies, 21 Hz and 7 Hz, connected to the surge oscillation in the test rig are identified, and the observed instability is categorized according to the intensity of pressure fluctuations. Based on the test results, the excited pressure waves are clearly the result of surge and not stall. Also, they exhibit the characteristics of mild and classic surge instead of deep surge. Finally, the change in the compressor performance due to variation in the impeller tip clearance is experimentally examined, and the results support the potential of the tip clearance modulation for the control of compressor surge. This is the first such demonstration of the feasibility of surge control of a compressor using active magnetic bearings.

  3. Flow in a Low Specific Speed Centrifugal Pump Using PIV

    Directory of Open Access Journals (Sweden)

    Cui Dai


    Full Text Available The interflow plays important roles in centrifugal pump design. In order to study the effect of rotation and z-axis on internal flow, two-dimensional particle image velocimetry (PIV measurements have been performed to measure the steady velocity field on three planes in all impeller passages of a low specific-speed centrifugal pump. The results show that the relative velocity flows in blade passages are obviously different in terms of the positions of the blade relative to the tongue. The interaction between the impeller and tongue changes the occurrence and development of low velocity region with time. From shroud to hub, the relative velocity gradually increases, and the minimum value moves toward the suction surface. On the midplane, the magnitude increases with increased flow rate from pressure surface to suction surface, while at the shroud and hub, the measured velocity first increases with decreased flow rate from the blade pressure surface to nearly ζ = 0.5 to 0.6.

  4. Centrifugal compression of soft particle packings: theory and experiment. (United States)

    Nordstrom, K N; Verneuil, E; Ellenbroek, W G; Lubensky, T C; Gollub, J P; Durian, D J


    An exact method is developed for computing the height of an elastic medium subjected to centrifugal compression, for arbitrary constitutive relation between stress and strain. Example solutions are obtained for power-law media and for cases where the stress diverges at a critical strain--for example as required by packings composed of deformable but incompressible particles. Experimental data are presented for the centrifugal compression of thermo-responsive N-isopropylacrylamide (NIPA) microgel beads in water. For small radial acceleration, the results are consistent with Hertzian elasticity, and are analyzed in terms of the Young elastic modulus of the bead material. For large radial acceleration, the sample compression asymptotes to a value corresponding to a space-filling particle volume fraction of unity. Therefore we conclude that the gel beads are incompressible, and deform without deswelling. In addition, we find that the Young elastic modulus of the particulate gel material scales with cross-link density raised to the power 3.3±0.8, somewhat larger than the Flory expectation.

  5. In-vitro assessment of centrifugal pumps for ventricular assist. (United States)

    Jakob, H; Kutschera, Y; Palzer, B; Prellwitz, W; Oelert, H


    Currently two major types of centrifugal pumps are commercially available for ventricular assist: the Biomedicus-cone (Group I) and the Centrimed-impeller pump (now Sarns 3M) (Group II). To compare them for blood trauma and hemolysis, an in-vitro experiment was designed with a Stöckert roller pump as a standard control (Group III). The in-vitro circuit was constructed consisting of a pump head, electromagnetic flow probe, polyvinyl chloride tubing and a reservoir, identical for all groups. Human ACD blood was used for priming and was circulated with a flow rate of 2 L/min for 24 h. Blood samples were taken at 0, 1, 3, 6, 12, and 24 h and zero control values were subtracted from the resulting data per time interval. Among the 16 parameters studied, a highly significant difference in favor of Group I was found for glutamate oxalacetate transaminase (GOT) and lactate dehydrogenase (p less than 0.0001) and for the free plasma hemoglobin (p less than 0.0001) after 12 and 24 h, respectively. The hemolytic index (Allen) again was lowest for group I in contrast to Groups II and III (0.012 versus 0.060 and 1.70) after 24 h. All other parameters studied did not render significant differences between the systems tested. The authors conclude that the Biomedicus pump currently is the least traumatic centrifugal pump for ventricular assist.

  6. Platelet function and hemolysis in centrifugal pumps: in vitro investigations. (United States)

    Steines, D; Westphal, D; Göbel, C; Reul, H; Rau, G


    The effects of centrifugal pumps on blood components other than erythrocytes, namely platelets and their interaction with the coagulation system, are not very well known. In a comparative study with three centrifugal pumps (BioMedicus BP-80, St. Jude Isoflow, and Sarns Delphin) and the Stockert roller pump hemolysis, platelet counts, thromboplastin and partial thromboplastin times, as well as resonance thrombography (RTG) parameters for the assessment of platelet and coagulation function were evaluated in vitro. Normalized indices of hemolysis (NIH) with ACD anticoagulation after 360 minutes were 0.008+/-0.004 (Isoflow), 0.018+/-0.017 (BP-80), 0.085+/-0.051 (Delphin), and 0.049+/-0.010 g/1001 (roller pump). Plasmatic coagulation was activated in all circuits. Platelet function was severely inhibited by the BP-80, indicated by increase in RTG platelet time to 358%+/-150% of initial values compared to 42%+/-29% (Isoflow), 40%+/-20% (Delphin), and 12%+/-10% (roller pump). Fibrin polymerization was affected similarly. The large surface area of the BP-80 leads to an extensive activation of platelets and plasminogen.

  7. Numerical Study of Unsteady Flow in Centrifugal Cold Compressor (United States)

    Zhang, Ning; Zhang, Peng; Wu, Jihao; Li, Qing

    In helium refrigeration system, high-speed centrifugal cold compressor is utilized to pumped gaseous helium from saturated liquid helium tank at low temperature and low pressure for producing superfluid helium or sub-cooled helium. Stall and surge are common unsteady flow phenomena in centrifugal cold compressors which severely limit operation range and impact efficiency reliability. In order to obtain the installed range of cold compressor, unsteady flow in the case of low mass flow or high pressure ratio is investigated by the CFD. From the results of the numerical analysis, it can be deduced that the pressure ratio increases with the decrease in reduced mass flow. With the decrease of the reduced mass flow, backflow and vortex are intensified near the shroud of impeller. The unsteady flow will not only increase the flow loss, but also damage the compressor. It provided a numerical foundation of analyzing the effect of unsteady flow field and reducing the flow loss, and it is helpful for the further study and able to instruct the designing.

  8. Experiments on Plasma Injection into a Centrifugally Confined System (United States)

    Messer, S.; Bomgardner, R.; Brockington, S.; Case, A.; Witherspoon, F. D.; Uzun-Kaymak, I.; Elton, R.; Young, W.; Teodorescu, C.; Morales, C. H.; Ellis, R. F.


    We describe the cross-field injection of plasma into a centrifugally-confined system. Two different types of plasma railgun have been installed on the Maryland Centrifugal Experiment (MCX) in an attempt to drive that plasma's rotation. The initial gun was a coaxial device designed to mitigate the blowby instability. The second one was a MiniRailgun with a rectangular bore oriented so that the MCX magnetic field augments the railgun's internal magnetic field. Tests at HyperV indicate this MiniRailgun reaches much higher densities than the original gun, although muzzle velocity is slightly reduced. We discuss the impact of these guns on MCX for various conditions. Initial results show that even for a 2 kG field, firing the MiniRailgun modifies oscillations of the MCX diamagnetic loops and can impact the core current and voltage. The gun also has a noticeable impact on MCX microwave emissions. These observations suggest plasma enters the MCX system. We also compare diagnostic data collected separately from MCX for these and other guns, focussing primarily on magnetic measurements.

  9. LISSAT Analysis of a Generic Centrifuge Enrichment Plant

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, H; Elayat, H A; O?Connell, W J; Szytel, L; Dreicer, M


    The U.S. Department of Energy (DOE) is interested in developing tools and methods for use in designing and evaluating safeguards systems for current and future plants in the nuclear power fuel cycle. The DOE is engaging several DOE National Laboratories in efforts applied to safeguards for chemical conversion plants and gaseous centrifuge enrichment plants. As part of the development, Lawrence Livermore National Laboratory has developed an integrated safeguards system analysis tool (LISSAT). This tool provides modeling and analysis of facility and safeguards operations, generation of diversion paths, and evaluation of safeguards system effectiveness. The constituent elements of diversion scenarios, including material extraction and concealment measures, are structured using directed graphs (digraphs) and fault trees. Statistical analysis evaluates the effectiveness of measurement verification plans and randomly timed inspections. Time domain simulations analyze significant scenarios, especially those involving alternate time ordering of events or issues of timeliness. Such simulations can provide additional information to the fault tree analysis and can help identify the range of normal operations and, by extension, identify additional plant operational signatures of diversions. LISSAT analyses can be used to compare the diversion-detection probabilities for individual safeguards technologies and to inform overall strategy implementations for present and future plants. Additionally, LISSAT can be the basis for a rigorous cost-effectiveness analysis of safeguards and design options. This paper will describe the results of a LISSAT analysis of a generic centrifuge enrichment plant. The paper will describe the diversion scenarios analyzed and the effectiveness of various safeguards systems alternatives.

  10. Numerical modeling of centrifuge cyclic lateral pile load experiments

    Institute of Scientific and Technical Information of China (English)

    Nikos Gerolymos; Sandra Escoffer; George Gazetas; Jacques Gamier


    To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimental p-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including: soil plastification at an early stage of loading, "pinching" behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. (1974) for sand, is also presented.

  11. Strong Force

    CERN Document Server

    Without the strong force, there could be no life. The carbon in living matter is synthesised in stars via the strong force. Lighter atomic nuclei become bound together in a process called nuclear fusion. A minor change in this interaction would make life impossible. As its name suggests, the strong force is the most powerful of the 4 forces, yet its sphere of influence is limited to within the atomic nucleus. Indeed it is the strong force that holds together the quarks inside the positively charged protons. Without this glue, the quarks would fly apart repulsed by electromagnetism. In fact, it is impossible to separate 2 quarks : so much energy is needed, that a second pair of quarks is produced. Text for the interactive: Can you pull apart the quarks inside a proton?

  12. Numerical Research on Hydraulically Generated Vibration and Noise of a Centrifugal Pump Volute with Impeller Outlet Width Variation

    Directory of Open Access Journals (Sweden)

    Houlin Liu


    Full Text Available The impeller outlet width of centrifugal pumps is of significant importance for numbers of effects. In the paper, these effects including the performance, pressure pulsations, hydraulically generated vibration, and noise level are investigated. For the purpose, two approaches were used to predict the vibration and sound radiation of the volute under fluid excitation force. One approach is the combined CFD/FEM analysis for structure vibration, and then the structure response obtained from the FEM analysis is treated as the boundary condition for BEM analysis for sound radiation. The other is the combined CFD/FEM/BEM coupling method. Before the numerical methods were used, the simulation results were validated by the vibration acceleration of the monitoring points on the volute. The vibration and noise were analyzed and compared at three flow conditions. The analysis of the results shows that the influences of the sound pressure of centrifugal pumps on the structure appear insignificant. The relative outlet width b2* at nq(SI = 26.7 in this paper should be less than 0.06, based on an overall consideration of the pump characteristics, pressure pulsations, vibration and noise level.

  13. Determination for the Entrapment Criterion of Non-metallic Inclusions by the Solidification Front During Steel Centrifugal Continuous Casting (United States)

    Wang, Qiangqiang; Zhang, Lifeng


    In the current study, the three-dimensional fluid flow, heat transfer, and solidification in steel centrifugal continuous casting strands were simulated. The volume of fluid model was used to solve the multiphase phenomena between the molten steel and the air. The entrapment and final distribution of inclusions in the solidified shell were studied with the discussion on the effect of rotation behavior of the caster system. Main results indicate that after applying the rotation of the shell, the fluid flow transformed from a recirculation flow to a rotation flow in the mold region and was driven to flow around in the casting direction. As the distance below the meniscus increased, the distribution of the tangential speed of the flow and the centrifugal force along one diameter of the strand became symmetrical gradually. The jet flow from the nozzle hardly impinged on the same location on the shell due to the rotation of the shell during solidification. Thus, the shell thickness on the same height was uniform around, and the thinning shell and a hot spot on the surface of shell were avoided. Both of the measurement and the calculation about the distribution of oxide inclusions along the radial direction indicated the number of inclusions at the side and the center was more than that at the quarter on the cross section of billet. With a larger diameter, inclusions tended to be entrapped toward the center area of the billet.

  14. Numerical Research about Influence of Blade Outlet Angle on Flow-Induced Noise and Vibration for Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Ailing Yang


    Full Text Available A hybrid numerical method was used to calculate the flow-induced noise and vibration of the centrifugal pump in the paper. The unsteady flows inside the centrifugal pumps with different blade outlet angles were simulated firstly. The unsteady pressure on the inner surface of the volute and the unsteady force applied on the impeller were analyzed. Then the vibration of the volute and sound field were calculated based on an acoustic-vibro-coupling method. The results show that the pump head has increased 7% while the hydraulic efficiency decreased 11.75% as blade outlet angles increased from 18° to 39°. The amplitude of pressure fluctuation at the first blade passing frequency has decreased but increased at the second-order blade passing frequency as the angle growing. The total fluctuation power near volute tongue goes up about 12% every 3° increment of blade outlet angle. The results also show that vibrating-velocity of the volute at second-order blade passing frequency is much higher than at other frequencies, and the velocity increases rapidly as blade outlet angle varies from 18° to 39°. At the same time, the sound pressure level outside the pump has increased about 8.6 dB when the angle increased from 18° to 39°.

  15. Incidence of electrocardiographic changes during cytapheresis using an intermittent flow centrifuge, haemonetics V50 and a continuous flow centrifuge, AS104. (United States)

    Komatsu, F; Kajiwara, M


    Electrocardiographic (ECG) monitoring was performed during cytapheresis and the incidence of ECG changes was compared between methods of intermittent flow centrifugation using the Haemonetics V50 with apheresis donors and continuous flow centrifugation with the AS104 for peripheral blood stem cell (PBSC) collection from patients. ST depression, inverted T wave and other ECG changes were found in 49 (14.3%) of the 342 cytaphereses carried out by the intermittent flow centrifugation method and in 8 (4.7%) of the 169 PBSC collections by the continuous flow centrifugation method. This difference was significant (P < 0.05). The hemodynamic changes in the procedure with the AS104 seem to be small. This is considered to be important for prevention of serious ST and T wave changes.

  16. Proposal of Unique Process Pump with Floating Type Centrifugal Impeller (Preliminarily Report : Axial Thrust of Impeller with Driving Shaft) (United States)

    Kawashima, Ryunosuke; Kanemoto, Toshiaki; Sakamoto, Kengo; Uno, Mitsuo


    The authors have proposed the unique centrifugal pump, in which the impeller dose not have the driving shaft but is driven by the magnetic induction, namely Lorentz force, without the stay. Then, the rotating posture of the impeller is not stable, just like UFO. To make the rotating posture of the impeller stable irrespective of the operating condition, the pressure in the impeller casing was investigated experimentally while the impeller rotates at the steady state, as the preliminarily stage. The pressure, as well known, fluctuates periodically in response to the blade number. Besides, the pressure on the impeller shrouds decreases with the increase of the gap between the front shroud and the suction cover where the water leaks to the suction pipe, and is distorted in the peripheral direction. Such pressure conditions contribute directly to the hydraulic force acting on the impeller. The unstable behaviors of the impeller are induced from the above hydraulic forces, which change unsteadily in the radial and the peripheral directions in the impeller casing. The forces are affected by not only the operating condition but also the rotating posture of the impeller.

  17. Numerical Calculation of the Three-Dimensional Swirling Flow Inside the Centrifugal Pump Volutes

    Directory of Open Access Journals (Sweden)

    E. Cezmi Nursen


    Full Text Available The flow inside the volute of a centrifugal pump is threedimensional and, depending upon the position of the inlet relative to the cross-section center line, a single or double swirling flow occurs. The purpose of this study was the calculation of the three-dimensional swirling flow inside the centrifugal pump volute.

  18. Weak Force

    CERN Multimedia

    Without the weak force, the sun wouldn't shine. The weak force causes beta decay, a form of radioactivity that triggers nuclear fusion in the heart of the sun. The weak force is unlike other forces: it is characterised by disintegration. In beta decay, a down quark transforms into an up quark and an electron is emitted. Some materials are more radioactive than others because the delicate balance between the strong force and the weak force varies depending on the number of particles in the atomic nucleus. We live in the midst of a natural radioactive background that varies from region to region. For example, in Cornwall where there is a lot of granite, levels of background radiation are much higher than in the Geneva region. Text for the interactive: Move the Geiger counter to find out which samples are radioactive - you may be surprised. It is the weak force that is responsible for the Beta radioactivity here. The electrons emitted do not cross the plastic cover. Why do you think there is some detected radioa...

  19. High Technology Centrifugal Compressor for Commercial Air Conditioning Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ruckes, John


    R&D Dynamics, Bloomfield, CT in partnership with the State of Connecticut has been developing a high technology, oil-free, energy-efficient centrifugal compressor called CENVA for commercial air conditioning systems under a program funded by the US Department of Energy. The CENVA compressor applies the foil bearing technology used in all modern aircraft, civil and military, air conditioning systems. The CENVA compressor will enhance the efficiency of water and air cooled chillers, packaged roof top units, and other air conditioning systems by providing an 18% reduction in energy consumption in the unit capacity range of 25 to 350 tons of refrigeration The technical approach for CENVA involved the design and development of a high-speed, oil-free foil gas bearing-supported two-stage centrifugal compressor, CENVA encompassed the following high technologies, which are not currently utilized in commercial air conditioning systems: Foil gas bearings operating in HFC-134a; Efficient centrifugal impellers and diffusers; High speed motors and drives; and System integration of above technologies. Extensive design, development and testing efforts were carried out. Significant accomplishments achieved under this program are: (1) A total of 26 builds and over 200 tests were successfully completed with successively improved designs; (2) Use of foil gas bearings in refrigerant R134a was successfully proven; (3) A high speed, high power permanent magnet motor was developed; (4) An encoder was used for signal feedback between motor and controller. Due to temperature limitations of the encoder, the compressor could not operate at higher speed and in turn at higher pressure. In order to alleviate this problem a unique sensorless controller was developed; (5) This controller has successfully been tested as stand alone; however, it has not yet been integrated and tested as a system; (6) The compressor successfully operated at water cooled condensing temperatures Due to temperature

  20. Cell adhesion to plasma electrolytic oxidation (PEO) titania coatings, assessed using a centrifuging technique. (United States)

    Robinson, H J; Markaki, A E; Collier, C A; Clyne, T W


    The adhesion of bovine chondrocytes and human osteoblasts to three titania-based coatings, formed by plasma electrolytic oxidation (PEO), was compared to that on uncoated Ti-6Al-4V substrates, and some comparisons were also made with plasma sprayed hydroxyapatite (HA) coatings. This was done using a centrifuge, with accelerations of up to 160,000 g, so as to induce buoyancy forces that created normal or shear stresses at the interface. It is shown that, on all surfaces, it was easier to remove cells under normal loading than under shear loading. Cell adhesion to the PEO coatings was stronger than that on Ti-6Al-4V and similar to that on HA. Cell proliferation rates were relatively high on one of the PEO coatings, which was virtually free of aluminium, but low on the other two, which contained significant levels of aluminium. It is concluded that the Al-free PEO coating offers promise for application to prosthetic implants.

  1. Development of a Compact Maglev Centrifugal Blood Pump Enclosed in a Titanium Housing (United States)

    Pai, Chi Nan; Shinshi, Tadahiko; Asama, Junichi; Takatani, Setsuo; Shimokohbe, Akira

    A compact centrifugal blood pump consisting of a controlled two-degrees-of-freedom radial magnetic bearing and a brushless DC motor enclosed in a titanium housing has been developed for use as an implantable ventricular assist device. The magnetic bearing also supports axial and angular motions of the impeller via a magnetic coupling. The top housing is made of pure titanium, while the impeller and the stator are coated with pure titanium and Ti-6Al-7Nb, respectively, to improve the biocompatibility of the pump. The combination of pure titanium and titanium alloy was chosen because of the sensitivity of eddy current type displacement sensors through the intervening conducting wall. The dimensions of the pump are 69.0 mm in diameter and 28.5 mm in height. During a pump performance test, axial shifting of the impeller due to hydraulic forces led to variations in the rotational positioning signal, causing loss of control of the rotational speed. This problem was solved by conditioning the rotational positioning signal. With a flow rate of 5 l/min against a head pressure of 100 mmHg, the power consumption and efficiency of the pump were 5.5 W and 20%, respectively. Furthermore, the hemolysis of the blood pump was 43.6% lower when compared to that of a commercially available pump.

  2. Fluid-Structure Interaction Analysis on Turbulent Annular Seals of Centrifugal Pumps during Transient Process

    Directory of Open Access Journals (Sweden)

    Qinglei Jiang


    Full Text Available The current paper studies the influence of annular seal flow on the transient response of centrifugal pump rotors during the start-up period. A single rotor system and three states of annular seal flow were modeled. These models were solved using numerical integration and finite difference methods. A fluid-structure interaction method was developed. In each time step one of the three annular seal models was chosen to simulate the annular seal flow according to the state of rotor systems. The objective was to obtain a transient response of rotor systems under the influence of fluid-induced forces generated by annular seal flow. This method overcomes some shortcomings of the traditional FSI method by improving the data transfer process between two domains. Calculated results were in good agreement with the experimental results. The annular seal was shown to have a supportive effect on rotor systems. Furthermore, decreasing the seal clearance would enhance this supportive effect. In the transient process, vibration amplitude and critical speed largely changed when the acceleration of the rotor system increased.

  3. Centrifuge modelling of the pushover failure of an electricity transmission tower

    Energy Technology Data Exchange (ETDEWEB)

    Richards, D.J. [Southampton Univ. (United Kingdom). School of Civil Engineering and the Environment; White, D.J. [Western Australia Univ., Crawley, WA (Australia). Centre for Offshore Foundation Systems, Faculty of Engineering, Computing and Mathematics


    The foundation systems of broad-based lattice power transmission towers must be designed to resist uplift, lateral and downward forces arising from the tower's weight, and tension within the conductor wires and wind loadings. This study investigated foundation failure mechanisms during the rapid horizontal pushover of a power transmission tower. The centrifuge model tests were designed to simulate a wind gust loading or broken transmission line response. The tower was supported on 4 pad foundations set in clay and backfilled with sand. The loads at each foundation were measured during fast and flow pushover. The influence of tensile resistance mobilized at the underside of the footings was investigated. The measured performance of the tower footings showed good agreement with results obtained from a series of tests conducted to measure a single footing subjected to vertical loading. Tower response was back-analyzed as a simple push-pull model. The calculated uplift capacity of the footing backfill showed good agreement with the observed response of tower footings subjected to slow pushover. The additional capacity mobilized during fast pushover was caused by tensile resistance created by the reverse bearing capacity beneath the base of the footings. 30 refs., 3 tabs., 11 figs.

  4. The potential of centrifugal casting for the production of near net shape uranium parts

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, E. [United States Air Force Academy, Colorado Springs, CO (US). Dept. of Engineering Mechanics


    This report was written to provide a detailed summary of a literature survey on the near net shape casting process of centrifugal casting. Centrifugal casting is one potential casting method which could satisfy the requirements of the LANL program titled Near Net Shape Casting of Uranium for Reduced Environmental, Safety and Health Impact. In this report, centrifugal casting techniques are reviewed and an assessment of the ability to achieve the near net shape and waste minimization goals of the LANL program by using these techniques is made. Based upon the literature reviewed, it is concluded that if properly modified for operation within a vacuum, vertical or horizontal centrifugation could be used to safely cast uranium for the production of hollow, cylindrical parts. However, for the production of components of geometries other than hollow tubes, vertical centrifugation could be combined with other casting methods such as semi-permanent mold or investment casting.

  5. Numerical study of a high-speed miniature centrifugal compressor (United States)

    Li, Xiaoyi

    A miniature centrifugal compressor is a key component of reverse Brayton cycle cryogenic cooling system. The system is commonly used to generate a low cryogenic temperature environment for electronics to increase their efficiency, or generate, store and transport cryogenic liquids, such as liquid hydrogen and oxygen, where space limit is also an issue. Because of space limitation, the compressor is composed of a radial IGV, a radial impeller and an axial-direction diffuser (which reduces the radial size because of smaller diameter). As a result of reduction in size, rotating speed of the impeller is as high as 313,000 rpm, and Helium is used as the working fluid, in order to obtain the required static pressure ratio/rise. Two main characteristics of the compressor---miniature and high-speed, make it distinct from conventional compressors. Higher compressor efficiency is required to obtain a higher COP (coefficient of performance) system. Even though miniature centrifugal compressors start to draw researchers' attention in recent years, understanding of the performance and loss mechanism is still lacking. Since current experimental techniques are not advanced enough to capture details of flow at miniature scale, numerical methods dominate miniature turbomachinery study. This work numerically studied a high speed miniature centrifugal compressor with commercial CFD code. The overall performance of the compressor was predicted with consideration of interaction between blade rows by using sliding mesh model. The law of similarity of turbomachinery was validated for small scale machines. It was found that the specific ratio effect needs to be considered when similarity law is applied. But Reynolds number effect can be neglected. The loss mechanism of each component was analyzed. Loss due to turning bend was significant in each component. Tip leakage loss of small scale turbomachines has more impact on the impeller performance than that of large scale ones. Because the

  6. Use of partially shrouded impeller in a small centrifugal compressor

    Institute of Scientific and Technical Information of China (English)

    Jin Tang; Teemu Turunen-Saaresti; Jaakko Larjola


    Numerical analysis is conducted for the 3-dimensional impeller and vaneless diffuser of a small centrifugal compressor. The influence of impeller tip clearance on the flow field of the impeller is investigated. Detailed investigation on the leaking flow across the tip clearance of the impeller shows that the leaking flow rate is higher near the exit of the impeller than that near the inlet of the impeller. Based on this phenomenon, a new partially shrouded impeller is designed. The impeller is shrouded near the exit of the impeller. Numerical results show that the secondary flow region becomes smaller at the exit of the impeller. Better performance is achieved than that with the unshrouded impeller.

  7. Approaches to stable operation of shaftless centrifugal pump (United States)

    Kawashima, Ryunosuke; Uno, Mitsuo; Kanemoto, Toshiaki


    The shaft-less impeller of the centrifugal pump, which is driven by the magnetic induction, was developed. The impeller rotates under the floating condition without any control device. The floating condition of the impeller is realized by utilizing the pressure in pump casing. The pump performance and the rotational behavior of the impeller were investigated experimentally. It has found that the floating position of the impeller become quite unstable in a partial flow rate operation. And the pressure distribution at the casing wall affects the rotational posture of the impeller. This paper presents the effect of the casing treatment on the rotational posture of the impeller and the pressure distribution. The reasonable casing treatment is available for the stable rotational posture of the impeller.

  8. Centrifugal photovoltaic and photogalvanic effects driven by structured light

    CERN Document Server

    Wätzel, Jonas


    Much efforts are devoted to material structuring in a quest to enhance the photovoltaic effect. We show that structuring light in a way it transfers orbital angular momentum to semiconductor-based rings results in a steady charge accumulation at the outer boundaries that be utilized for the generation of an open circuit voltage or a photogalvanic (bulk photovoltaic) type current. This effect which stems both from structuring light and matter (confinement potentials), can be magnified even at fixed moderate intensities, by increasing the orbital angular momentum of light which strengthens the effective centrifugal potential that repels the charge outwards. Based on a full numerical time propagation of the carriers wave functions in the presence of light pulses we demonstrate how the charge buildup leads to a useable voltage or directed photocurrent whose amplitudes and directions are controllable by the light pulse parameters.

  9. Centrifugal experimental study of suction bucket foundations under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    Xiaobing Lu; Yongren Wu; Bintian Jiao; Shuyun Wang


    Centrifugal experiments were carded out to investigate the responses of suction bucket foundations under horizontal and vertical dynamic loading. It is shown that when the loading amplitude is over a critical value, the sand at the upper part around the bucket is softened or even liq-uefied. The excess pore pressure decreases from the upper part to the lower part of the sand layer in the vertical direc-tion and decreases radially from the bucket's side wall in the horizontal direction. Large settlements of the bucket and the sand layer around the bucket are induced by dynamic load-ing. The dynamic responses of the bucket with smaller height (the same diameter) are heavier.

  10. Effect of Fluid Viscosity on Centrifugal Pump Performance

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nohhyeong [GS Caltex Corporation, Daejeon (Korea, Republic of)


    The characteristics of centrifugal pump performance according to fluid viscosity change were studied experimentally. A small volute pump with low specific speed was tested by changing the viscosity of an aqueous solution of sugar and glycerin, which is considered a Newtonian fluid. After finishing the test, the total head, shaft horsepower, and pump efficiency were compared with those of a water pump. The results are summarized as follows: when the fluid viscosity is increased, the shut-off head shows very little change but the total head decreases gradually as the flow increases, and this makes the H-Q curve leaning rapidly, and when the fluid viscosity is increased, the shaft horsepower shows very little change at the shutoff condition; however, the shaft horsepower increases more rapidly with an increase in the flow and viscosity.

  11. Centrifugal photovoltaic and photogalvanic effects driven by structured light. (United States)

    Wätzel, J; Berakdar, J


    Much efforts are devoted to material structuring in a quest to enhance the photovoltaic effect. We show that structuring light in a way it transfers orbital angular momentum to semiconductor-based rings results in a steady charge accumulation at the outer boundaries that can be utilized for the generation of an open circuit voltage or a photogalvanic (bulk photovoltaic) type current. This effect which stems both from structuring light and matter confinement potentials, can be magnified even at fixed moderate intensities, by increasing the orbital angular momentum of light which strengthens the effective centrifugal potential that repels the charge outwards. Based on a full numerical time propagation of the carriers wave functions in the presence of light pulses we demonstrate how the charge buildup leads to a useable voltage or directed photocurrent whose amplitudes and directions are controllable by the light pulse parameters.

  12. Ultrasound treatment of centrifugally atomized 316 stainless steel powders (United States)

    Rawers, James C.; McCune, Robert A.; Dunning, John S.


    The Bureau of Mines is studying the surface characteristics of rapidly solidified powders and the potential for surface modification of fine powders prior to consolidation. The surface modification and work hardening of fine powders were accomplished by applying high-energy ultrasound to centrifugally atomized austenitic 316 stainless steel powders suspended in liquid media. Cavitation implosion changed the surface morphology, hammering the surface and occasionally fretting off microchips of work-hardened metal. Ultrasound-cavitation work-hardened metal powder surfaces producing a strained, duplex austenite face-centered cubic (fcc)-martensite body-centered tetragonal (bct) phase structure. The amount of work hardening depended upon the quantity of ultrasound energy used, considering both power level and experimental time. Work hardening was relatively independent of the liquid media used.

  13. Operational Experience with a Cryogenic Axial-Centrifugal Compressor

    CERN Document Server

    Decker, L; Löhlein, K; Purtschert, W; Ziegler, B L; Lebrun, P; Tavian, L; Brunovsky, I; Tucek, L


    The Large Hadron Collider (LHC), presently under construction at CERN, requires large refrigeration capacity at 1.8 K. Compression of gaseous helium at cryogenic temperatures is therefore inevitable. Together with subcontractors, Linde Kryotechnik has developed a prototype machine. This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating at ambient temperature. Integrated in a test facility for superconducting magnets the machine has been commissioned without major problems and successfully gone through the acceptance test in autumn 1995. Subsequent steps were initiated to improve efficiency of this prototype. This paper describes operating experience gained so far and reports on measured performance prior to and after constructional modifications.

  14. Performance Improvement of a Centrifugal Compressor by Passive Means

    Directory of Open Access Journals (Sweden)

    N. Sitaram


    Full Text Available The present experimental investigation deals with performance improvement of a low-speed centrifugal compressor by inexpensive passive means such as turbulence generator placed at different positions and partial shroud near the rotor blade tip. The experiments are carried out at three values of tip clearance, namely 2.2%, 5.1%, and 7.9% of rotor blade height at the exit. Performance tests are carried out for a total of 13 configurations. From these measurements, partial shroud is found to give the best performance. The improvement in the compressor performance may be due to the reduction of tip leakage flows by the small extension of partial shroud (2 mm on the pressure surface side. Although there is nominal change in performance due to turbulence generator (TG, TG has beneficial effect of increased operating range.

  15. Approaches to Stable Operation of Shaftless Centrifugal Pump

    Institute of Scientific and Technical Information of China (English)

    Ryunosuke Kawashima; Mitsuo Uno; Toshiaki Kanemoto


    The shaft-less impeller of the centrifugal pump, which is driven by the magnetic induction, was developed. The impeller rotates under the floating condition without any control device. The floating condition of the impeller is realized by utilizing the pressure in pump casing. The pump performance and the rotational behavior of the im-peUer were investigated experimentally. It has found that the floating position of the impeller become quite unsta-ble in a partial flow rate operation. And the pressure distribution at the casing wall affects the rotational posture of the impeller. This paper presents the effect of the casing treatment on the rotational posture of the impeller and the pressure distribution. The reasonable casing treatment is available for the stable rotational posture of the impeller.

  16. A cryogenic axial-centrifugal compressor for superfluid helium refrigeration

    CERN Document Server

    Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L


    CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.

  17. A Novel Aerodynamic Design Method for Centrifugal Compressor Impeller

    Directory of Open Access Journals (Sweden)

    Mahdi Nili-Ahmadabadi


    Full Text Available This paper describes a new quasi-3D design method for centrifugal compressor impeller. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA, and a quasi-3D analysis. Euler equation is solved on the impeller meridional plane. The unknown boundaries (hub and shroud of numerical domain are iteratively modified by BSA until a target pressure distribution in flow passage is reached. To validate the quasi-3D analysis code, existing compressor impeller is investigated experimentally. Comparison between the quasi-3D analysis and the experimental results shows good agreement. Also, a full 3D Navier-Stokes code is used to analyze the existing and designed compressor numerically. The results show that the momentum decrease near the shroud wall in the existing compressor is removed by hub-shroud modifications resulting an improvement in performance by 0.6 percent.


    Institute of Scientific and Technical Information of China (English)

    NI Yongyan; YUAN Shouqi; PAN Zhongyong; YUAN Jianping


    For the purpose of detecting the cavitation of centrifugal pump onsite and real time, the vibration signals on varied operation conditions of both cavitation and non-cavitation obtained through acceleration sensors were analyzed. When cavitation occurs, the cavities near the leading edge of the blade will appear periodic oscillating, which will induce quasi-synchronous vibration. The frequency of the quasi-synchronous vibration symmetrically appears on the two sides of the blade passing frequency, by which the cavitation incipiency can be detected. During the developing process of the cavitation, as the severe complexity of the unsteady flow, it is very difficult to detect the development of cavitation by classical analysis methods. Fractal method of Higuchi is successfully used for detecting the incipiency, fully development of cavitation and the development between them.

  19. Rigorous buoyancy driven bubble mixing for centrifugal microfluidics. (United States)

    Burger, S; Schulz, M; von Stetten, F; Zengerle, R; Paust, N


    We present batch-mode mixing for centrifugal microfluidics operated at fixed rotational frequency. Gas is generated by the disk integrated decomposition of hydrogen peroxide (H2O2) to liquid water (H2O) and gaseous oxygen (O2) and inserted into a mixing chamber. There, bubbles are formed that ascent through the liquid in the artificial gravity field and lead to drag flow. Additionaly, strong buoyancy causes deformation and rupture of the gas bubbles and induces strong mixing flows in the liquids. Buoyancy driven bubble mixing is quantitatively compared to shake mode mixing, mixing by reciprocation and vortex mixing. To determine mixing efficiencies in a meaningful way, the different mixers are employed for mixing of a lysis reagent and human whole blood. Subsequently, DNA is extracted from the lysate and the amount of DNA recovered is taken as a measure for mixing efficiency. Relative to standard vortex mixing, DNA extraction based on buoyancy driven bubble mixing resulted in yields of 92 ± 8% (100 s mixing time) and 100 ± 8% (600 s) at 130g centrifugal acceleration. Shake mode mixing yields 96 ± 11% and is thus equal to buoyancy driven bubble mixing. An advantage of buoyancy driven bubble mixing is that it can be operated at fixed rotational frequency, however. The additional costs of implementing buoyancy driven bubble mixing are low since both the activation liquid and the catalyst are very low cost and no external means are required in the processing device. Furthermore, buoyancy driven bubble mixing can easily be integrated in a monolithic manner and is compatible to scalable manufacturing technologies such as injection moulding or thermoforming. We consider buoyancy driven bubble mixing an excellent alternative to shake mode mixing, in particular if the processing device is not capable of providing fast changes of rotational frequency or if the low average rotational frequency is challenging for the other integrated fluidic operations.

  20. Approach to novel design of CO2 based centrifugal compressor

    Directory of Open Access Journals (Sweden)

    Kura Tomasz


    Full Text Available Even though turbomachinery design issues have been investigated almost since the beginning of engineering, its optimization process is still important. With the development of refrigeration devices and ORC based distributed generation facilities, a need for efficient and low-energy compressors and turbines became even more demanding. Such machines working with typical fluid, like air, are well described, but there is a room regarding the fluids like CO2, vapour of organic fluids, etc. The main objective of present studies is to propose a numerical model of the centrifugal compressor, with CO2 as the working fluid. Such unit may be a part of refrigeration cycle. Commonly, the scroll or piston compressors are used in such cases, however some discussed disadvantages show that the novel designs should be looked for. Properly designed centrifugal compressors can have higher efficiency than the presently used. Three dimensional analyses of proposed geometries were conducted – using a model including heat, mass and momentum conservation laws as well as ideal gas law. Verification of the proposed mesh and results was performed in the basis of values obtained using theoretical and empirical equations. With about 700 000 control volumes in the validated model, error of the results was no higher than 5%, with only about 1% in regards to the thermal parameters. Two design proposals were analysed, with performance maps as the main comparison factor. Apart from performance characteristics, the pressure and velocity fields were presented, showing the process of flow structure optimization. The main goal was to reduce negative effects of pressure and velocity gradients on the performance. Proposed precursory design might be a good starting point for further development of compressors. The results of numerical analysis were promising and shows the possibility of proposed design usage in practical applications, however to obtain deep understanding of the

  1. Carnosol purification. Scaling-up centrifugal partition chromatography separations. (United States)

    Bouju, Elodie; Berthod, Alain; Faure, Karine


    This paper illustrates the application of a recently proposed protocol allowing the scale-up prediction on hydrostatic countercurrent chromatography columns (centrifugal partition chromatographs or CPC). A commercial extract of rosemary (Rosmarinus officinalis L.) was used as the starting material containing 0.48% of carnosol, an active pharmaceutical ingredient with great potential. After a rapid method development on a small-scale 35-mL CPC instrument that allowed for the determination of the solvent system and maximum sample concentration and volume, the purification was transferred on two larger instruments using the "free space between peaks" method. The method takes into account the technical limitations of the larger instruments, such as pressure and/or maximum centrifugal field, and allows, by simply running an analytical-sized injection on the large scale rotor, to give an accurate prediction of the maximum sample load and best throughput. The 0.27g of rosemary extract maximum load on a 35-mL CPC was transferred as a 1.9g load on a 254-mL medium size CPC and 9g load on a 812-mL CPC. The maximum process efficiency of 3.1mg of carnosol per hour obtained on the small 35-mL column was transferred on the 254-mL CPC giving 8.3mg/h and, on the larger 812-mL column 49.4mg of carnosol could be obtained per hour. If the scaling-up in CPC instruments is not directly homothetic, it can be highly predictable through a few simple experiments.

  2. Flow Characteristics of a Pipe Diffuser for Centrifugal Compressors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Sun


    Full Text Available The pipe diffuser, an efficient kind of radial bladed diffuser, is widely used in centrifugal compressors for gas turbine engines. This paper investigates flow characteristics of a pipe diffuser for centrifugal compressors by solving three-dimensional Reynolds-averaged Navier-Stokes equations. The results show that the pipe diffuser is adaptable to high Mach number incoming flows, and its unique leading edge could uniform the flow distortion. Numerical analysis indicates that the choke in pipe diffuser occurs suddenly, which leads to the dramatically steep performance curves near choke condition. Besides, it is found that the first half flow passage is particularly important to the pipe diffuser performance as it influences the choking behavior, the static pressure distribution, and the matching, so more attention should be paid to this region when designing or optimizing a pipe diffuser. Two counter-rotating vortices generated in the diffuser inlet region are captured by numerical simulation, and they can exist in the downstream of the diffuser passage. More detailed analysis show that these two vortices dominate the flow structure in the whole diffuser passage by shifting flow to certain positions and forming high-momentum flow cells and wake flow cells. The leading edge formed by the intersection of adjacent diffuser passages significantly affects this pair of vortices. In addition, these two vortices also affect the flow separation in pipe diffuser flow passages, they suppress separation near the front wall and back wall while facilitate separation at center locations. Therefore, it is recommended to design the leading edge of the pipe diffuser carefully to control the vortices and obtain a better flow field.

  3. Effect of Al-5Ti-B Inoculant Addition on the Graded Microstructure of Centrifugally Cast Al-13.8 wt.% Mg2Si Composite

    Directory of Open Access Journals (Sweden)

    A. Samadi


    Full Text Available To evaluate the effect of inoculant addition on functionally graded microstructure of centrifugally cast Al-Mg2Si composites, two cylinders of Al-13.8 wt.% Mg2Si with and without the addition of 1 wt.% Al-5Ti-B inoculant were cast in a vertical centrifugal casting machine. The chemical composition, microstructures and microstructural phases of the different radial sections of the cast cylinders were studied using induction coupled plasma (ICP method, optical/scanning electron microscopes, and X-ray diffractometry, respectively. The results showed that in the inoculant content cylinder, owing to the prevailing thermal regime as well as the specific mode of eutectic solidification in this composite, the titanium and boron compounds were segregated towards the middle layer of the cylinder and caused the formation of primary Mg2Si particles and non-eutectic Al ( in this layer. In addition, due to the effect of centrifugal force during solidification, a higher volume fraction of the light primary Mg2Si particles, according to Stocks law, was segregated towards the inner layer of the cast cylinders.

  4. Mixing Experiments with Shoshonitic and Trachytic Melts using a High-Temperature Centrifuge and a Viscometer: a comparative study (United States)

    de Campos, Cristina; Dorfman, Alexander; Perugini, Diego; Kolzenburg, Stephan; Petrelli, Maurizio; Dingwell, Donald B.


    Evidence of cyclic replenishment of the shallow magmatic reservoir with deeper alkali basaltic (shoshonitic) magma (Campi Flegrei, in Italy; see Arienzo et al., 2008, Bull. Volcanol.) motivated this study. Results from different mixing experiments using natural volcanic samples from this region will be presented. The end-member melts derive from the Agnano-Monte Spina (trachytic) and Minopoli (shoshonitic) eruptions. Based on previous isotopic data, these are thought to be the most suitable counterparts for simulating the extreme interacting compositions in this system. In order to study the mixing dynamics between these natural magmas, we performed time series of convection-diffusion experiments using two different techniques: 1) a high-temperature centrifuge and 2) a viscometer. For the centrifuge experiments the rotating speed was 1850 revolutions per minute and the acceleration 10 3 g. In this way, dynamic conditions closer to those calculated for magma chambers (Reynolds Numbers [Re] around 102) could be simulated. For every experiment, a 4 mm thick disk of previously homogenized crystal free shoshonitic glass and an 8 mm thick disk of homogenized crystal free trachytic glass were loaded in a 5mm diameter Pt capsule. The capsule was then sealed on both sides, but for a small opening on the upper end, allowing intersticial degassing during the acceleration. Samples were arranged in a buoyantly unstable geometry, where the denser material is placed at the inner side of the rotating circle (basaltic trachyandesite, ρ=2.63 g/cm3 at 1169oC) and the lighter material at the external side (trachyte, ρ=2.45 g/cm3 at ~1000oC). Temperature has been kept constant at 1,200oC during all experimental runs, with a negligible thermal gradient (< 1°C). Forced convection was applied via centrifugal acceleration and density instabilities. Results from three experimental runs with the centrifuge: after 5, 20 and 120 min will be discussed. The second set of experiments consisted

  5. Estimating mechanical blood trauma in a centrifugal blood pump: laser Doppler anemometer measurements of the mean velocity field. (United States)

    Pinotti, M; Paone, N


    A laser Doppler anemometer (LDA) was used to obtain the mean velocity and the Reynolds stress fields in the inner channels of a well-known centrifugal vaneless pump (Bio-pump). Effects of the excessive flow resistance against which an occlusive pump operates in some surgical situations, such as cardiopulmonary bypass, are illustrated. The velocity vector field obtained from LDA measurements reveals that the constraint-forced vortex provides pumping action in a restricted area in the core of the pump. In such situations, recirculating zones dominate the flow and consequently increase the damage to blood cells and raise the risk of thrombus formation in the device. Reynolds normal and shear stress fields were obtained in the entry flow for the channel formed by two rotating cones to illustrate the effects of flow disturbances on the potential for blood cell damage.

  6. Centrifuge model test on dynamic behavior of group-pile foundation With inclined piles and its numerical simulation

    Institute of Scientific and Technical Information of China (English)

    Feng ZHANG; Katsunori OKAWA; Makoto KIMURA


    In this paper, dynamic behavior of a grouppile foundation with inclined piles in loose sand has been investigated with centrifuge model tests. The test results are also simulated with elastoplastic dynamic finite ele-ment method, in which, not only sectional force of piles, stress of ground, but also deformation of piles are calcu-lated using a three-dimensional elastoplastic dynamic finite element analysis (Code name: DGPILE-3D). The numerical analyses are conducted with a full system in which a superstructure, a pile foundation and surround-ing ground are considered together so that interaction between pile foundation and soils can be properly simu-lated because the nonlinearities of both the pile and the ground are described with suitable constitutive models. Different types of piles, vertical pile or inclined pile, are considered in order to verify the different characteristics of a group pile foundation with inclined piles. The validity of the calculation is verified by the model tests.

  7. 40 CFR 63.5810 - What are my options for meeting the standards for open molding and centrifugal casting operations... (United States)


    ... standards for open molding and centrifugal casting operations at new and existing sources? 63.5810 Section... § 63.5810 What are my options for meeting the standards for open molding and centrifugal casting... (d) of this section to meet the standards for open molding or centrifugal casting operations in...

  8. Vertical hydraulic conductivity of a clayey-silt aquitard: accelerated fluid flow in a centrifuge permeameter compared with in situ conditions

    Directory of Open Access Journals (Sweden)

    W. A. Timms


    Full Text Available Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, extraction of fuels from strata such as coal beds, and confinement of waste within the earth. Characterizing low or negligible flow rates and transport of solutes can require impractically long periods of field or laboratory testing, but is necessary for evaluations over regional areas and over multi-decadal timescales. The current work reports a custom designed centrifuge permeameter (CP system, which can provide relatively rapid and reliable hydraulic conductivity (K measurement compared to column permeameter tests at standard gravity (1g. Linear fluid velocity through a low K porous sample is linearly related to g-level during a CP flight unless consolidation or geochemical reactions occur. The CP module is designed to fit within a standard 2 m diameter, geotechnical centrifuge with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length. At maximum RPM the resultant centrifugal force is equivalent to 550g at base of sample or a total stress of ~2 MPa. K is calculated by measuring influent and effluent volumes. A custom designed mounting system allows minimal disturbance of drill core samples and a centrifugal force that represents realistic in situ stress conditions is applied. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the resultant K value. Vertical hydraulic conductivity (Kv results from CP testing of core from the sites in the same clayey silt formation varied (10−7 to 10−9 m s−1, n = 14 but higher than 1g column permeameter tests of adjacent core using deionized water (10−9 to 10−11 m s−1, n = 7. Results at one site were similar to in situ Kv values (3 × 10−9 m s−1 from pore pressure responses within a 30 m clayey sequence in a homogenous area of the formation. Kv sensitivity to sample heterogeneity was

  9. Modeling the desired direction in a force-based model for pedestrian dynamics

    CERN Document Server

    Chraibi, Mohcine; Schadschneider, Andreas; Seyfried, Armin


    We introduce an enhanced model based on the generalized centrifugal force model. Furthermore, the desired direction of pedestrians is investigated. A new approach leaning on the well-known concept of static and dynamic floor-fields in cellular automata is presented. Numerical results of the model are presented and compared with empirical data.

  10. Forced Snaking (United States)

    Ponedel, Benjamin; Knobloch, Edgar


    We study spatial localization in the real subcritical Ginzburg-Landau equation ut =m0 u +m1 cos2/π l x u +uxx +d | u | 2 u -| u | 4 u with spatially periodic forcing. When d > 0 and m1 = 0 this equation exhibits bistability between the trivial state u = 0 and a homogeneous nontrivial state u =u0 with stationary localized structures which accumulate at the Maxwell point m0 = - 3d2 / 16 . When spatial forcing is included its wavelength is imprinted on u0 creating conditions favorable to front pinning and hence spatial localization. We use numerical continuation to show that under appropriate conditions such forcing generates a sequence of localized states organized within a snakes-and-ladders structure centered on the Maxwell point, and refer to this phenomenon as forced snaking. We determine the stability properties of these states and show that longer lengthscale forcing leads to stationary trains consisting of a finite number of strongly localized, weakly interacting pulses exhibiting foliated snaking.

  11. In vitro pulsatility analysis of axial-flow and centrifugal-flow left ventricular assist devices. (United States)

    Stanfield, J Ryan; Selzman, Craig H


    Recently, continuous-flow ventricular assist devices (CF-VADs) have supplanted older, pulsatile-flow pumps, for treating patients with advanced heart failure. Despite the excellent results of the newer generation devices, the effects of long-term loss of pulsatility remain unknown. The aim of this study is to compare the ability of both axial and centrifugal continuous-flow pumps to intrinsically modify pulsatility when placed under physiologically diverse conditions. Four VADs, two axial- and two centrifugal-flow, were evaluated on a mock circulatory flow system. Each VAD was operated at a constant impeller speed over three hypothetical cardiac conditions: normo-tensive, hypertensive, and hypotensive. Pulsatility index (PI) was compared for each device under each condition. Centrifugal-flow devices had a higher PI than that of axial-flow pumps. Under normo-tension, flow PI was 0.98 ± 0.03 and 1.50 ± 0.02 for the axial and centrifugal groups, respectively (p centrifugal pumps, respectively (p = 0.01). Under hypotension, PI was 0.73 ± 0.02 and 0.78 ± 0.02 for the axial and centrifugal groups, respectively (p = 0.13). All tested CF-VADs were capable of maintaining some pulsatile-flow when connected in parallel with our mock ventricle. We conclude that centrifugal-flow devices outperform the axial pumps from the basis of PI under tested conditions.

  12. Effect of pumping chamber on performance of non-overload centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    谷云庆; 吴登昊; 牟介刚; 蒋兰芳; 代东顺; 施瀚昱; 郑水华


    In order to specify the characteristics of un-overloaded centrifugal pumps, the IH100-65-200 pump was chosen as the model pump. Different calculation models for centrifugal pumps were established under different pumping chamber sectional parameters. In the numerical simulation of the centrifugal pumps flow field, the shaft power, head, efficiency, and the changes of the internal flow field under different sectional areas and sectional shapes were studied with the RNGk−εturbulence model, and the influence of the pumping chamber section characteristics of the non-overloaded centrifugal pumps were analyzed. The results show that sectional areas have a significant impact on the non-overload characteristics of centrifugal pumps. The shaft power and head of centrifugal pump are increasing with a lager sectional area, by which the gradient of head curves decreases. The efficiency is improved under a large flow rate condition, but the head and the efficiency are reduced at a small flow rate. It is also observed that the sectional shapes have less influence on the shaft power, the hydraulic performance and flow field characteristics of a centrifugal pump.

  13. Geometric optimization of a step bearing for a hydrodynamically levitated centrifugal blood pump for the reduction of hemolysis. (United States)

    Kosaka, Ryo; Yada, Toru; Nishida, Masahiro; Maruyama, Osamu; Yamane, Takashi


    A hydrodynamically levitated centrifugal blood pump with a semi-open impeller has been developed for mechanical circulatory assistance. However, a narrow bearing gap has the potential to cause hemolysis. The purpose of the present study is to optimize the geometric configuration of the hydrodynamic step bearing in order to reduce hemolysis by expansion of the bearing gap. First, a numerical analysis of the step bearing, based on lubrication theory, was performed to determine the optimal design. Second, in order to assess the accuracy of the numerical analysis, the hydrodynamic forces calculated in the numerical analysis were compared with those obtained in an actual measurement test using impellers having step lengths of 0%, 33%, and 67% of the vane length. Finally, a bearing gap measurement test and a hemolysis test were performed. As a result, the numerical analysis revealed that the hydrodynamic force was the largest when the step length was approximately 70%. The hydrodynamic force calculated in the numerical analysis was approximately equivalent to that obtained in the measurement test. In the measurement test and the hemolysis test, the blood pump having a step length of 67% achieved the maximum bearing gap and reduced hemolysis, as compared with the pumps having step lengths of 0% and 33%. It was confirmed that the numerical analysis of the step bearing was effective, and the developed blood pump having a step length of approximately 70% was found to be a suitable configuration for the reduction of hemolysis.

  14. Ultrasound-Assisted Extraction, Centrifugation and Ultrafiltration: Multistage Process for Polyphenol Recovery from Purple Sweet Potatoes

    Directory of Open Access Journals (Sweden)

    Zhenzhou Zhu


    Full Text Available This work provides an evaluation of an ultrasound-assisted, combined extraction, centrifugation and ultrafiltration process for the optimal recovery of polyphenols. A purple sweet potato (PSP extract has been obtained using ultrasonic circulating extraction equipment at a power of 840 W, a frequency of 59 kHz and using water as solvent. Extract ultrafiltration, using polyethersulfone (PES, was carried out for the recovery of polyphenol, protein and anthocyanin. Pre-treatment, via the centrifugation of purple sweet potato extract at 2500 rpm over 6 min, led to better polyphenol recovery, with satisfactory protein removal (reused for future purposes, than PSP extract filtration without centrifugation. Results showed that anthocyanin was efficiently recovered (99% from permeate. The exponential model fit well with the experimental ultrafiltration data and led to the calculation of the membrane’s fouling coefficient. The optimization of centrifugation conditions showed that, at a centrifugation speed of 4000 rpm (1195× g and duration of 7.74 min, the optimized polyphenol recovery and fouling coefficient were 34.5% and 29.5 m−1, respectively. The removal of proteins in the centrifugation process means that most of the anthocyanin content (90% remained after filtration. No significant differences in the intensities of the HPLC-DAD-ESI-MS2 peaks were found in the samples taken before and after centrifugation for the main anthocyanins; peonidin-3-feruloylsophoroside-5-glucoside, peonidin-3-caffeoyl-p-hydroxybenzoylsophoroside-5-glucoside, and peonidin-3-caffeoyl-feruloyl sophoroside-5-glucoside. This proves that centrifugation is an efficient method for protein removal without anthocyanin loss. This study considers this process an ultrasound-assisted extraction-centrifugation-ultrafiltration for purple sweet potato valorization in “green” technology.

  15. Intermolecular forces. (United States)

    Buckingham, A D


    The nature of molecular interactions is examined. Intermolecular forces are divided into long-range and short-range components; the former operate at distances where the effects of electron exchange are negligible and decrease as an inverse power of the separation. The long-range interactions may be subdividied into electrostatic, induction and dispersion contributions, where the electrostatic component is the interaction of the permanent charge distributions and the others originate in the fluctuations in the distributions. Typical magnitudes of the various contributions are given. The forces between macroscopic bodies are briefly considered, as are the effects of a medium. Some of the manifestations of molecular interactions are discussed.

  16. On the "force-free surface " of the magnetized celestial bodies

    CERN Document Server

    Epp, V


    The field of a uniformly magnetized rotating sphere is studied with special attention to the surface where the electric and magnetic fields are orthogonal to each other. The equation of this surface, valid at arbitrary distances from the rotating magnetized sphere, is obtained. Inside the light cylinder this surface can be considered as a force-free surface, i.e. as a place where the particles with strong radiation damping can be trapped due to their energy loss. Outside the light cylinder this surface makes just a geometric locus which moves with a superlight velocity around the axis of rotation. The 2- and 3-dimensional plots of the force-free surface are constructed. Estimation of influence of the centrifugal force on the particle dynamics is made. It is shown, that in case of strong magnetic field the centrifugal force is negligible small everywhere except a narrow neighbourhood of the light cylinder.

  17. Comparative Centrifugal Distortion Analysis in Rotational Spectra of Propanol and Isopropanol Molecules (United States)

    Qajar, Ch. O.; Kazimova, S. B.


    We have compared the effect of centrifugal distortion on the rotational spectra of isopropanol and propanol molecules in the microwave frequency range. We identified 61 rotational transitions of the propanol molecule with rotational quantum numbers up to J = 36 inclusive. We show that in order to satisfactorily take into account centrifugal distortion in the isopropanol molecule, it is sufficient to use only the quartic and sextic terms, while in calculating the rotational transitions of the propanol molecule we need to include all the way up to dectic centrifugal distortion constants.

  18. [Usefulness of the Centrifuge Accommodation Module for analyzing gravity responses in plant seedlings]. (United States)

    Hoson, T


    Onboard centrifuges are indispensable tools for clarifying the effects of microgravity on various physiological processes in plant seedlings. Centrifuges are basically attached to the incubators designed for the International Space Station (ISS). However, because of the limitation in size, that loaded to the Cell Biology Experiment Facility (CBEF) is usable only to some small seedlings such as Arabidopsis. The Centrifuge Accommodation Module (CAM) has great advantages in the size and the amounts of plant materials feasible to load, the quality of acceleration produced, and the easiness of operation on it. The CAM is an apparatus that characterizes the ISS most and its construction on schedule is highly expected.

  19. Study on High-Speed Centrifugal-Regenerative Pump with an Inducer

    Institute of Scientific and Technical Information of China (English)

    朱祖超; 陈鹰; 金庆明; 黄敦回


    The study on high-speed centrifugal-regenerative pumps with an inducer (HCRP) is carried out. Thecombined structure of inducer, centrifugal impeller, and regenerative impeller is presented, and a theoretical parallelcombinatorial hydraulic design method is investigated. The comparative experimental results show that efficiency insmaller capacity region, head coefficient and efficiency in larger capacity region of HCRPs is few lower, much higherand lower than those of high-speed centrifugal pumps, respectively, anci that the suction performance of HCRPs isdetermined only by inducer. HCRPs can be more suitably applied to deliver small-capacity high-head liquids inchemical and petrochemical industries.


    Institute of Scientific and Technical Information of China (English)


    The experimental study is carded out on high-speed centrifugal pumps with three different impellers. The ex-perimental results and analysis show that high-speed centrifugal pumps with a closed complex impeller can achieve thehighest efficiency and the lowest head coefficient followed by those with half-open impeller and open-impeller, and canobtain much easily stable head-capacity characrastic curve, while those with a half-open complex impeller can't. Thecharacteristic curve with a open impeller is almost constant horizontal line before dropping sharply. The results also showthat the axial clearance between pump casing and impeller can influence greatly on the performance of centrifugal pumps.

  1. Hydrodynamic performance and heat generation by centrifugal pumps. (United States)

    Ganushchak, Y; van Marken Lichtenbelt, W; van der Nagel, T; de Jong, D S


    For over a century, centrifugal pumps (CP) have been used in various applications, from large industrial pumps to flow pumps for aquariums. However, the use of CP as blood pumps has a rather short history. Consequently, the hydraulic performance data for a blood CP are limited. The aim of our investigation was to study the hydraulic performance and the heat generation of three commercially available CP: Bio-Medicus Bio-Pump BP80 (Medtronic), Rotaflow (Jostra Medizintechnik), and DeltaStream DP2 (MEDOS Medizintechnik AQ). The study was performed using a circuit primed with a water-glycerin mixture with a dynamic viscosity of 0.00272 pa/s. Pressure-flow curves were obtained by a stepwise stagnation of the pump outlet or inlet. The temperature changes were observed using ThermaCAM SC2000 (Flir Systems). The pumps' performance in close to clinical conditions ('operating region') was analysed in this report. The 'operating region' in the case of the BP80 is positioned around the pressure-flow curve at a pump speed of 3000 rpm. In the case of the Rotaflow, the 'operating region' was between the pump pressure-flow curves at a speed of 3000 and 4000 rpm, and the DP2 was found between 7000 and 8000 rpm. The standard deviation of mean pressure through the pump was used to characterise the stability of the pump. In experiments with outlet stagnation, the BP80 demonstrated high negative association between flow and pressure variability (r = -0.68, p pumps demonstrated significantly higher variability of pressure in experiments with inlet stagnation in comparison to the experiments with outlet stagnation. The rise of relative temperature in the inlet of a pump was closely related to the flow rate. The heating of fluid was more pronounced in the 'zero-flow' mode, especially in experiments with inlet stagnation. In summary, (1) the 'zero-flow' regime, which is described in the manuals of some commercially-available pumps, is the use of the pump outside the allowable operating

  2. Oil-free centrifugal hydrogen compression technology demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Heshmat, Hooshang [Mohawk Innovative Technology Inc., Albany, NY (United States)


    One of the key elements in realizing a mature market for hydrogen vehicles is the deployment of a safe and efficient hydrogen production and delivery infrastructure on a scale that can compete economically with current fuels. The challenge, however, is that hydrogen, being the lightest and smallest of gases with a lower viscosity and density than natural gas, readily migrates through small spaces and is difficult to compresses efficiently. While efficient and cost effective compression technology is crucial to effective pipeline delivery of hydrogen, the compression methods used currently rely on oil lubricated positive displacement (PD) machines. PD compression technology is very costly, has poor reliability and durability, especially for components subjected to wear (e.g., valves, rider bands and piston rings) and contaminates hydrogen with lubricating fluid. Even so called “oil-free” machines use oil lubricants that migrate into and contaminate the gas path. Due to the poor reliability of PD compressors, current hydrogen producers often install duplicate units in order to maintain on-line times of 98-99%. Such machine redundancy adds substantially to system capital costs. As such, DOE deemed that low capital cost, reliable, efficient and oil-free advanced compressor technologies are needed. MiTi’s solution is a completely oil-free, multi-stage, high-speed, centrifugal compressor designed for flow capacity of 500,000 kg/day with a discharge pressure of 1200 psig. The design employs oil-free compliant foil bearings and seals to allow for very high operating speeds, totally contamination free operation, long life and reliability. This design meets the DOE’s performance targets and achieves an extremely aggressive, specific power metric of 0.48 kW-hr/kg and provides significant improvements in reliability/durability, energy efficiency, sealing and freedom from contamination. The multi-stage compressor system concept has been validated through full scale

  3. Solanidine isolation from Solanum tuberosum by centrifugal partition chromatography. (United States)

    Attoumbré, Jacques; Giordanengo, Philippe; Baltora-Rosset, Sylvie


    The aim of this investigation was the preparative isolation of solanidine (aglycone of the two main potato glycoalkaloids: α-chaconine and α-solanine) from fresh Solanum tuberosum (cv. Pompadour) material by implementing a new preparation scheme using centrifugal partition chromatography (CPC). A setup for obtaining solanidine by hydrolysis of the glycoalkaloids found in the skin and sprouts of S. tuberosum was first developed. Then its isolation was carried out by the development of CPC conditions: the solvent system used for separation was ethyl acetate/butanol/water in the ratio 42.5:7.5:50 v/v/v, 0.6 g of crude extract were separated with a 8 mL/min flow rate of mobile phase while rotating at 2500 rpm. A run yielded 98 mg of solanidine (86.7% recovery from the crude extract) in a one-step separation. The purity of the isolated solanidine was over 98%. Thus, CPC has proven to be the method of choice to get solanidine of very high purity from S. tuberosum biomass in large quantities.

  4. Design concepts for the Centrifuge Facility Life Sciences Glovebox (United States)

    Sun, Sidney C.; Horkachuck, Michael J.; Mckeown, Kellie A.


    The Life Sciences Glovebox will provide the bioisolated environment to support on-orbit operations involving non-human live specimens and samples for human life sceinces experiments. It will be part of the Centrifuge Facility, in which animal and plant specimens are housed in bioisolated Habitat modules and transported to the Glovebox as part of the experiment protocols supported by the crew. At the Glovebox, up to two crew members and two habitat modules must be accommodated to provide flexibility and support optimal operations. This paper will present several innovative design concepts that attempt to satisfy the basic Glovebox requirements. These concepts were evaluated for ergonomics and ease of operations using computer modeling and full-scale mockups. The more promising ideas were presented to scientists and astronauts for their evaluation. Their comments, and the results from other evaluations are presented. Based on the evaluations, the authors recommend designs and features that will help optimize crew performance and facilitate science accommodations, and specify problem areas that require further study.

  5. Axial and Centrifugal Compressor Mean Line Flow Analysis Method (United States)

    Veres, Joseph P.


    This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.

  6. Performance of a newly developed implantable centrifugal blood pump. (United States)

    Tsukiya, T; Taenaka, Y; Tatsumi, E; Takano, H


    The performance of the newly developed implantable centrifugal blood pump was investigated in vitro. The pump was developed with the end goal of building a versatile system that includes a left ventricular assist system with an internal secondary battery or an implantable biventricular assist system with two implantable blood pumps. The hydrodynamic characteristics and efficiency of the blood pump were evaluated, and the mechanical damage to the blood caused by the blood pump was assessed through a hemolysis test using fresh goat blood. The pump could generate 120 mm Hg at a flow rate of 5 L/min and a motor speed of 2,500 rpm. The electric input power to the pump was approximately 5 watts under these working conditions. The hemolysis caused by the pump was a bit higher than that by the former model, but stayed within an acceptable range. Performance of the pump in vitro was considered sufficient for a left ventricular assist device, although further design improvement is necessary in terms of hemolysis and system efficiency to improve biocompatibility of the pump.

  7. Isolation of Methoxyfuranocoumarins From Ammi majus by Centrifugal Partition Chromatography. (United States)

    Bartnik, Magdalena; Mazurek, Anna Katarzyna


    Pure methoxyfuranocoumarins were isolated from Ammi majus L. by use of low-pressure column chromatography (LPCC) followed by centrifugal partition chromatography (CPC). The concentrated petroleum ether extract from fruits of A. majus was fractionated on a silica gel column using a gradient of ethyl acetate in dichloromethane (0-80%, v/v). Coumarin-rich fractions were analyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography with diode array detection (HPLC/DAD). Xanthotoxin (8-MOP) and isopimpinellin (isoP), structurally similar compounds, were isolated in one fraction (FR6). To avoid multistep and long-lasting TLC preparation, optimization of CPC conditions has been performed. In one run, an effective separation of 8-MOP and isoP was achieved. The two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (10 : 8 : 10 : 9; v/v) in an ascending mode (the aqueous phase was a stationary phase, and the organic phase was a mobile phase), with flow rate 3 mL/min and rotation speed 1,600 r.p.m., was used. The identification and high purities of isolated 8-MOP (98.7%) and isoP (100%) were confirmed by HPLC/DAD assay, when compared with standards. The developed CPC method could be applied to the effective isolation of 8-MOP and isoP from plant extracts. The high purity of obtained compounds makes possible further exploitation of these components in biological studies.

  8. Centrifugal barrel polishing of 1.3 GHz Nb cavities

    Energy Technology Data Exchange (ETDEWEB)

    Tamashevich, Yegor; Foster, Brian [DESY, Hamburg (Germany); Hamburg Univ. (Germany); Navitski, Aliaksandr; Steder, Lea; Elsen, Eckhard [DESY, Hamburg (Germany)


    Superconducting radio-frequency (SRF) cavities are the key components of particle accelerators such as the European X-ray Free Electron Laser (XFEL, under construction) and the planned future International Linear Collider (ILC). Steady progress in surface treatment techniques of SRF cavities in both the achievable quality factor Q and the accelerating electric field Eacc makes new accelerators and ambitious projects feasible. One of the alternative surface preparation techniques which is actually being explored is centrifugal barrel polishing (CBP) pioneered at KEK in Japan in mid-nineties by T. Hiuchi et al. CBP is a mechanical polishing of cavities and results in around 10 x smaller surface roughness and mirror-like surface as compared to chemistry alone. Q and E{sub acc} are expected to be at least as high as for chemically treated cavities. CBP eliminates the bulk chemistry and has the potential to completely replace the chemistry. The University of Hamburg is installing a CBP machine to study it as a cavity preparation and repair technique for 9-cell 1.3 GHz SRF cavities at the Deutsche Elektronen-Synchrotron (DESY). The setup and first commissioning tests will be presented and discussed.

  9. A study on centrifugal casting of high speed steel roll

    Institute of Scientific and Technical Information of China (English)


    High speed steel (HSS) rolls can replace traditional rolls such as alloyed cast iron rolls and powder metallurgical (PM) hard alloy rolls. The main reasons for the replacement are that the wear resistance of low-cost alloyed cast iron rolls is poor and the cost of high-quality PM hard alloy rolls is very high. By means of centrifugal casting, HSS rolls having excellent wear resistance have been manufactured. The hardness of the HSS roll is 65~ 67 HRC, the range of variation is smaller than 2 HRC and its impact toughness is 15 J/cm2. The wear rate of HSS rolls used in the pre-finishing stands of high-speed hot wire-rod rolling mill reaches 2.5 × 10-4 mm per ton steel. Furthermore, the manufacturing cost of HSS rolls is significantly lower than that of PM hard alloy rolls; it is only 30 percent of that of PM hard alloy rolls.

  10. Optimal Design of a Centrifugal Compressor Impeller Using Evolutionary Algorithms

    Directory of Open Access Journals (Sweden)

    Soo-Yong Cho


    Full Text Available An optimization study was conducted on a centrifugal compressor. Eight design variables were chosen from the control points for the Bezier curves which widely influenced the geometric variation; four design variables were selected to optimize the flow passage between the hub and the shroud, and other four design variables were used to improve the performance of the impeller blade. As an optimization algorithm, an artificial neural network (ANN was adopted. Initially, the design of experiments was applied to set up the initial data space of the ANN, which was improved during the optimization process using a genetic algorithm. If a result of the ANN reached a higher level, that result was re-calculated by computational fluid dynamics (CFD and was applied to develop a new ANN. The prediction difference between the ANN and CFD was consequently less than 1% after the 6th generation. Using this optimization technique, the computational time for the optimization was greatly reduced and the accuracy of the optimization algorithm was increased. The efficiency was improved by 1.4% without losing the pressure ratio, and Pareto-optimal solutions of the efficiency versus the pressure ratio were obtained through the 21st generation.

  11. Centrifugal Distortion Causes Anderson Localization in Laser Kicked Molecules (United States)

    Floss, Johannes; Averbukh, Ilya Sh.


    The periodically kicked 2D rotor is a textbook model in nonlinear dynamics. The classical kicked rotor can exhibit truly chaotic motion, whilst in the quantum regime this chaotic motion is suppressed by a mechanism similar to Anderson Localization. Up to now, these effects have been mainly observed in an atom optics analogue of a quantum rotor: cold atoms in a standing light wave. We demonstrate that common linear molecules (like N2, O2, CO2, ...), kicked by a train of short linearly polarized laser pulses, can exhibit a new mechanism for dynamical Anderson Localization due to their non-rigidity. When the pulses are separated by the rotational revival time trev = πℏ / B , the angular momentum J grows ballistically (Quantum Resonance). We show that, due to the centrifugal distortion of fast spinning molecules, above some critical value J =Jcr the Quantum Resonance is suppressed via the mechanism of Anderson Localization. This leads to a non-sinusoidal oscillation of the angular momentum distribution, which may be experimentally observed even at ambient conditions by using current techniques for laser molecular alignment.

  12. Evaluation of floating impeller phenomena in a Gyro centrifugal pump. (United States)

    Nishimura, Ikuya; Ichikawa, S; Mikami, M; Ishitoya, H; Motomura, T; Kawamura, M; Linneweber, J; Glueck, J; Shinohara, T; Nosé, Y


    The Gyro centrifugal pump developed as a totally implantable artificial heart was designed with a free impeller, in which the rotational shaft (male bearing) of the impeller was completely separated from the female bearing. For this type of pump, it is very important to keep the proper magnet balance (impeller-magnet and actuator-magnet) in order to prevent thrombus formation and/or bearing wear. When the magnet balance is not proper, the impeller is jerked down into the bottom bearing. On the other hand, if magnet balance is proper, the impeller lifted off the bottom of the pump housing within a certain range of pumping conditions. In this study, this floating phenomenon was investigated in detail. The floating phenomenon was proved by observation of the impeller behavior using a transparent acrylic pump. The impeller floating phenomenon was mapped on a pump performance curve. The impeller floating phenomenon is affected by the magnet-magnet coupling distance and rotational speed of the impeller. In order to keep the proper magnet balance and to maintain the impeller floating phenomenon at the driving condition of right and left pump, the magnet-magnet coupling distance was altered by a spacer which was installed between the pump and actuator. It became clear that the same pump could handle different conditions (right and left ventricular assist), by just changing the thickness of the spacer. When magnet balance is proper, the floating impeller phenomenon occurs automatically in response to the impeller rev. It is called "the dynamic RPM suspension".

  13. A study on centrifugal charaging pump shaft failure investigation

    Energy Technology Data Exchange (ETDEWEB)

    Jo, S. D.; Kim, B. K. [KEPCO, Woolsan (Korea, Republic of)


    Pump shafts in the centrifugal charging safety injection pumps in PWRs have been subject to occasional failures over the past several years. Service experience showed that the pump shaft failures can result in significant emergency repair and maintenance costs to the plant. Metallurgical investigations of the pump shafts fabricated prior to 1977 confirmed that the cracking was initiated at stress concentrations sitcs, such as a locknut thread root or a split ring groove, and progressed by a high cycle fatigue mechanism. Westinghouse implemented a series of improvements and upgrades to increase the safety margins and to mitigate the effect of the off-design operating conditions. These included design enhancements as well as material condition (heat treatment) modifications. The pump shaft upgrading program significantly improved the design life of the shafts but did not fully mitigate the issue. Investigation of recent failures of the upgraded shafts suggested that these failures are initiated by a combination of off-design loading events such as loss of flow or gas binding and a reduction of pump shaft resistance to cracking due to the aqueous environmental conditions.

  14. Fast Pyrolysis of Lignin Using a Pyrolysis Centrifuge Reactor

    DEFF Research Database (Denmark)

    Trinh, Ngoc Trung; Jensen, Peter Arendt; Sárossy, Zsuzsa


    Fast pyrolysis of lignin from an ethanol plant was investigated on a lab scale pyrolysis centrifuge reactor (PCR) with respect to pyrolysis temperature, reactor gas residence time, and feed rate. A maximal organic oil yield of 34 wt % dry basis (db) (bio-oil yield of 43 wt % db) is obtained...... at temperatures of 500−550 °C, reactor gas residence time of 0.8 s, and feed rate of 5.6 g/min. Gas chromatography mass spectrometry and size-exclusion chromatography were used to characterize the Chemical properties of the lignin oils. Acetic acid, levoglucosan, guaiacol, syringols, and p-vinylguaiacol are found...... to be major chemical components in the lignin oil. The maximal yields of 0.62, 0.67, and 0.38 wt % db were obtained for syringol, p-vinylguaiacol, and guaiacol, respectively. The reactor temperature effect was investigated in a range of 450−600 °C and has a considerable effect on the observed chemical...

  15. Autopsy findings in patients on postcardiotomy centrifugal ventricular assist. (United States)

    Curtis, J J; Walls, J T; Boley, T M; Schmaltz, R A; Demmy, T L


    Reported experience with ventricular assist devices (VAD) routinely includes the rate of thromboembolic events, which is commonly calculated from clinically evident findings. Fifty-four patients have had postcardiotomy circulatory support with the Sarns centrifugal device at our institution. We have reviewed 43 patients who failed to survive VAD support to compare the thromboembolism rate diagnosed clinically to that determined at autopsy. In the 35 patients who had no autopsy, there was one clinically apparent thromboembolic event (2.3%). In eight similar patients who had autopsy, there was no clinically apparent thromboembolism. Five of these eight patients (63%) had acute thromboembolic infarcts determined at autopsy. Three had evidence of pulmonary thromboembolism, two cerebrovascular infarction, two liver infarcts, two splenic infarcts, two kidney infarcts, and one each gastric, pancreatic, prostate, adrenal, cervical, and ileal infarcts. All had left and/or right ventricular infarctions. It is concluded that patients dying following VAD have commonly suffered perioperative myocardial infarction. When evaluating complications associated with VAD, one should consider that the true incidence of thromboembolic events is underestimated by clinical findings.

  16. New approach for porous materials obtaining using centrifugal casting (United States)

    Bălţătescu, O.; Axinte, M.; Barbu, G.; Manole, V.


    It has been presented different methods for obtaining porous materials, (mainly used for metallic foams) and highlighting a new technology developed in the Faculty of Materials science and engineering, of Iasi. Our technology for obtaining porous materials is called centrifugal casting for porous materials. This technology is included in the method number 8: co-pressing of a metal powder with a leachable powder being in the same time a newer approach in the porous materials field. This technology is currently in the developmental phase. Since now we made experiments on the metallic materials, aluminum alloys. The technology is briefly described in this paper. The obtained parts were used for making samples in order to characterize the properties of the materials. The cellular structure of metallic foams requires special precautions that must be taken in characterization and testing. In this paper we have characterized the samples structurally by its cell topology (open cells, closed cells), relative density, cell size and cell shape and anisotropy. Also it was used scanning electron microscopy (SEM) which is straightforward; the only necessary precaution is that relating to surface preparation.

  17. Casting behavior of titanium alloys in a centrifugal casting machine. (United States)

    Watanabe, K; Miyakawa, O; Takada, Y; Okuno, O; Okabe, T


    Since dental casting requires replication of complex shapes with great accuracy, this study examined how well some commercial titanium alloys and experimental titanium-copper alloys filled a mold cavity. The metals examined were three types of commercial dental titanium [commercially pure titanium (hereinafter noted as CP-Ti), Ti-6Al-4V (T64) and Ti-6Al-7Nb (T67)], and experimental titanium-copper alloys [3%, 5% and 10% Cu (mass %)]. The volume percentage filling the cavity was evaluated in castings prepared in a very thin perforated sheet pattern and cast in a centrifugal casting machine. The flow behavior of the molten metal was also examined using a so-called "tracer element technique." The amounts of CP-Ti and all the Ti-Cu alloys filling the cavity were similar; less T64 and T67 filled the cavity. However, the Ti-Cu alloys failed to reach the end of the cavities due to a lower fluidity compared to the other metals. A mold prepared with specially designed perforated sheets was effective at differentiating the flow behavior of the metals tested. The present technique also revealed that the more viscous Ti-Cu alloys with a wide freezing range failed to sequentially flow to the end of the cavity.

  18. Central centrifugal cicatricial alopecia amalgamated with alopecia areata: immunologic findings

    Directory of Open Access Journals (Sweden)

    Ana Maria Abreu Velez


    Full Text Available Introduction: Both scarring and non-scarring alopecias exist; however, rare cases demonstrate features of both classes. Case Report: We describe an interesting alopecia case with amalgamated clinical, histologic and immunopathologic features of scarring and non-scarring alopecia. Specifically, the case displays combined features of alopecia areata (AA and of central centrifugal cicatricial alopecia (CCCA. A 36 year old female presented with symmetric, round, patchy hair loss on her scalp. Methods: Biopsies for hematoxylin and eosin (H&E examination, as well as for special stains, direct immunofluorescence (DIF and immunohistochemistry (IHC were performed. Results: The H&E biopsy revealed focally diminished hair follicular units, and sebaceous gland damage. Perifollicular concentric fibrosis was confirmed by Verhoeff elastin special staining. Antibodies to micelles were noted. Positive IHC staining for CD4, CD8, CD45 and multiple proteases and protease inhibitors was noted around selected follicular unit remnants. Conclusion: We present a rare alopecia, combining histologic features of CCCA with additional, selected immunologic features of AA.

  19. The computer simulation of 3d gas dynamics in a gas centrifuge (United States)

    Borman, V. D.; Bogovalov, S. V.; Borisevich, V. D.; Tronin, I. V.; Tronin, V. N.


    We argue on the basis of the results of 2D analysis of the gas flow in gas centrifuges that a reliable calculation of the circulation of the gas and gas content in the gas centrifuge is possible only in frameworks of 3D numerical simulation of gas dynamics in the gas centrifuge (hereafter GC). The group from National research nuclear university, MEPhI, has created a computer code for 3D simulation of the gas flow in GC. The results of the computer simulations of the gas flows in GC are presented. A model Iguassu centrifuge is explored for the simulations. A nonaxisymmetric gas flow is produced due to interaction of the hypersonic rotating flow with the scoops for extraction of the product and waste flows from the GC. The scoops produce shock waves penetrating into a working camera of the GC and form spiral waves there.

  20. Centrifuge modeling of one-step outflow tests for unsaturated parameter estimations

    Directory of Open Access Journals (Sweden)

    H. Nakajima


    Full Text Available Centrifuge modeling of one-step outflow tests were carried out using a 2-m radius geotechnical centrifuge, and the cumulative outflow and transient pore pressure were measured during the tests at multiple gravity levels. Based on the scaling law of centrifuge modeling, the measurements generally showed reasonable agreement with prototype data calculated from forward simulations with input parameters determined from standard laboratory tests. The parameter optimizations were examined for three different combinations of input data sets using the test measurements. Within the gravity level examined in this study up to 40 g, the optimized unsaturated parameters compared well when accurate pore pressure measurements were included along with cumulative outflow as input data. The centrifuge modeling technique with its capability to implement variety of instrumentations under well controlled initial and boundary conditions, shortens testing time and can provide significant information for the parameter estimation procedure.

  1. Fast centrifugal partition chromatography as a preparative-scale separation technique for citrus flavones (United States)

    Fast centrifugal partition chromatography (FCPC) is a preparative-scale separations methodology based on the principles of counter current chromatography. Separations by FCPC are typically achieved with higher recoveries and with lower solvent use compared to conventional column chromatography. HSCP...

  2. [Pay attention to physical test and drafting product standards of the centrifuge apparatus]. (United States)

    Xu, Hui; Jia, Yufei; Li, Haixin; Song, Jinzi


    Compare and analyze the standards related to centrifuge apparatus and make corresponding suggestions in allusion to the problems existed in the test method and physical performance during product standard drafting process.


    Directory of Open Access Journals (Sweden)

    V. Yu. Stecenko


    Full Text Available The way of cooling of castings from silumin AK15M3 is developed at the vertical centrifugal casting, enabling to receive bimetallic blanks with high-disperse eutectic and hypereutectic microstructures and minimal allowance for machining.

  4. Numerical simulation for permanent mold centrifugal cast TiAl exhaust valve

    Institute of Scientific and Technical Information of China (English)

    SHENG Wen-bin; LI Dong


    The filling and solidification in centrifugal field, as well as the forming mechanism of off-center porosities were summarized, based on the mathematical model established for the centrifugal cast TiAl exhaust valves.The calculated results show that the centrifugal field results in the phenomenon that the flow in the valve cavity consists of forward flow and backward flow. The unsymmetrical initial temperature field causes continuous unsymmetrical variation in the following solidification, which makes the final solidified region depart from the cavity axis and then leads to the occurrence of off-center porosity. A series of optimized parameters, including the entrance velocity of 0.6 - 1.3 m/s, the rotation speed higher than 300 r/min, 80 mm or longer entrance length and 400 ℃ or higher preheated temperature of the mold, are suggested for the manufacture of permanent mold centrifugal cast TiAl exhaust valves.

  5. Filling and solidification of TiAl melt in centrifugal field

    Institute of Scientific and Technical Information of China (English)

    SHENG Wen-bin


    A model was established based on the combination of the equation of continuity,the equation of conservation of momentum and the equation of general energy to describe the filling and solidification of TiAl melt by permanent mold centrifugal casting. The model was solved numerically and the filling and solidification processes in the centrifugal field were discussed. The results indicate that the centrifugal field essentially influences the filling and solidification processes of TiAl melt. The melt will first fill the cavity along the back boundary until it reaches the end. After the end is fully filled,the whole cavity will be filled gradually by the way that free surface of the melt moves towards the entrance,hence the entrance is the last part to be filled. Furthermore,the mechanism by which internal defects can be formed in centrifugally cast TiAl components were interpreted.

  6. Nitrogen mineralization from anaerobically digested centrifuge cake and aged air-dried biosolids. (United States)

    Kumar, Kuldip; Hundal, Lakhwinder S; Cox, Albert E; Granato, Thomas


    This study was conducted to estimate nitrogen (N) mineralization of anaerobically digested centrifuge cake from the Stickney Water Reclamation Plant (SWRP) and Calumet Water Reclamation Plant (CWRP), lagoon-aged air-dried biosolids from the CWRP, and Milorganite at three rates of application (0, 12.5 and 25 Mg ha(-1)). The N mineralized varied among biosolids as follows: Milorganite (44%) > SWRP centrifuge cake (35%) > CWRP centrifuge cake (31%) > aged air-dried (13%). The N mineralized in the SWRP cake (32%) and CWRP aged air-dried biosolids (12%) determined from the 15N study were in agreement with the first study. The N mineralization value for centrifuge cake biosolids observed in our study is higher than the value given in the Part 503 rule and Illinois Part 391 guidelines. These results will be used to fine-tune biosolids application rate to match crop N demand without compromising yield while minimizing any adverse effect on the environment.

  7. Practice of centrifugal stable isotope separation for experiments in neutrino physics

    Energy Technology Data Exchange (ETDEWEB)

    Tikhomirov, A.V. [Kurchatov Institute, Moscow (Russian Federation)


    Results of xenon 136, germanium 76 and chromium 50 enrichment with the use of centrifuge cascades are presented. The isotopes are meant for use in experiments in neutrino physics. Tens of kilograms of these isotopes have been produced in Russia, with an enrichment level of an order of magnitude or higher with respect to their natural content. Practical possibilities of using the centrifugal technique both for neutrino investigation and other applications are outlined. 2 tabs., 9 refs.


    Institute of Scientific and Technical Information of China (English)


    A new type of vibrating centrifuge with wider frequency range is designed instead of the traditional one with a single frequency to improve the vibrating effect. With the aid of a new dynamical model, one simulation without considering the visco-elasticity of basis is presented, then the dynamical responses of time and frequency in different scheme are given. The computational results show that the improved vibrating centrifuge possesses a remarkably widened frequency range.

  9. Faults Analysis and Diagnosis of DR J-460 Dish Centrifugal Separator's Helical Gear

    Institute of Scientific and Technical Information of China (English)

    MA Xiao-jian; GAN Xue-hui


    The main faults of dish centrifugal separator's helical gear are described in this paper. In order to diagnose the DR J-460 dish centrifugal separator correctly, the vibration is tested with a helical gear under both normal and abnormal conditions. After comparing several general methods of the gear's fault feature extraction, a new convenient and effective method is presented on the basis of analyzing the vibration spectrum under different rotary velocities.

  10. Comparison of centrifuged liquid based cytology method with conventional brush cytology in oral lesions


    Nidhi Dwivedi; Akhil Agarwal; Vineet Raj; Bina Kashyap; Shaleen Chandra


    Background: Exfoliative cytology is the study of cells that are shed or scrapped off from mucosal surfaces. Centrifuged Liquid based cytology is a modified technique employed in the present study. Aims: To compare the utility of centrifuged liquid based cytology with conventional cytology in oral lesions after staining with Papanicolaou (PAP) stain. Materials and Methods: 50 cases of oral lesions comprising of normal mucosa (n=14), hyperkeratotic lesions (n=17), ulcerated lesions (n=7) and at...

  11. Force decomposition in robot force control (United States)

    Murphy, Steve H.; Wen, John T.


    The unit inconsistency in force decomposition has motivated an investigation into the force control problem in multiple-arm manipulation. Based on physical considerations, it is argued that the force that should be controlled is the internal force at the specified frame in the payload. This force contains contributions due to both applied forces from the arms and the inertial force from the payload and the arms. A least-squares scheme free of unit inconsistency for finding this internal force is presented. The force control issue is analyzed, and an integral force feedback controller is proposed.

  12. New methods and media for the centrifugation of honey bee (Hymenoptera: Apidae) drone semen. (United States)

    Wegener, Jakob; May, Tanja; Kamp, Günter; Bienefeld, Kaspar


    Centrifugation of Apis mellifera L. drone semen is a necessary step in the homogenization of semen pools for the enlargement of the effective breeding population, as well as in the collection of semen by the so-called washing technique. It is also of interest for the removal of cryoprotectants after cryopreservation. The adoption of methods involving semen centrifugation has been hampered by their damaging effect to sperm. Here, we tested four new diluents as well as three additives (catalase, hen egg yolk, and a protease inhibitor), using sperm motility and dual fluorescent staining as indicators of semen quality. Three of the new diluents significantly reduced motility losses after centrifugation, as compared with the literature standard. Values of motility and propidium iodide negativity obtained with two of these diluents were not different from those measured with untreated semen. The least damaging diluent, a citrate-HEPES buffer containing trehalose, was then tested in an insemination experiment with centrifuged semen. Most queens receiving this semen produced normal brood, and the number of sperm reaching the storage organ of the queen was not significantly different from that in queens receiving untreated semen. These results could improve the acceptance of techniques involving the centrifugation of drone semen. The diluent used in the insemination experiment could also serve as semen extender for applications not involving centrifugation.

  13. Feasibility of a Short-Arm Centrifuge for Mouse Hypergravity Experiments (United States)

    Morita, Hironobu; Obata, Koji; Abe, Chikara; Shiba, Dai; Shirakawa, Masaki; Kudo, Takashi; Takahashi, Satoru


    To elucidate the pure impact of microgravity on small mammals despite uncontrolled factors that exist in the International Space Station, it is necessary to construct a 1 g environment in space. The Japan Aerospace Exploration Agency has developed a novel mouse habitat cage unit that can be installed in the Cell Biology Experiment Facility in the Kibo module of the International Space Station. The Cell Biology Experiment Facility has a short-arm centrifuge to produce artificial 1 g gravity in space for mouse experiments. However, the gravitational gradient formed inside the rearing cage is larger when the radius of gyration is shorter; this may have some impact on mice. Accordingly, biological responses to hypergravity induced by a short-arm centrifuge were examined and compared with those induced by a long-arm centrifuge. Hypergravity induced a significant Fos expression in the central nervous system, a suppression of body mass growth, an acute and transient reduction in food intake, and impaired vestibulomotor coordination. There was no difference in these responses between mice raised in a short-arm centrifuge and those in a long-arm centrifuge. These results demonstrate the feasibility of using a short-arm centrifuge for mouse experiments. PMID:26221724

  14. Feasibility of a Short-Arm Centrifuge for Mouse Hypergravity Experiments.

    Directory of Open Access Journals (Sweden)

    Hironobu Morita

    Full Text Available To elucidate the pure impact of microgravity on small mammals despite uncontrolled factors that exist in the International Space Station, it is necessary to construct a 1 g environment in space. The Japan Aerospace Exploration Agency has developed a novel mouse habitat cage unit that can be installed in the Cell Biology Experiment Facility in the Kibo module of the International Space Station. The Cell Biology Experiment Facility has a short-arm centrifuge to produce artificial 1 g gravity in space for mouse experiments. However, the gravitational gradient formed inside the rearing cage is larger when the radius of gyration is shorter; this may have some impact on mice. Accordingly, biological responses to hypergravity induced by a short-arm centrifuge were examined and compared with those induced by a long-arm centrifuge. Hypergravity induced a significant Fos expression in the central nervous system, a suppression of body mass growth, an acute and transient reduction in food intake, and impaired vestibulomotor coordination. There was no difference in these responses between mice raised in a short-arm centrifuge and those in a long-arm centrifuge. These results demonstrate the feasibility of using a short-arm centrifuge for mouse experiments.

  15. Polymethylmethacrylate/Polyacrylonitrile Membranes via Centrifugal Spinning as Separator in Li-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Meltem Yanilmaz


    Full Text Available Electrospun nanofiber membranes have been extensively studied as separators in Li-ion batteries due to their large porosity, unique pore structure, and high electrolyte uptake. However, the electrospinning process has some serious drawbacks, such as low spinning rate and high production cost. The centrifugal spinning technique can be used as a fast, cost-effective and safe technique to fabricate high-performance fiber-based separators. In this work, polymethylmethacrylate (PMMA/polyacrylonitrile (PAN membranes with different blend ratios were produced via centrifugal spinning and characterized by using different electrochemical techniques for use as separators in Li-ion batteries. Compared with commercial microporous polyolefin membrane, centrifugally-spun PMMA/PAN membranes had larger ionic conductivity, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. Centrifugally-spun PMMA/PAN membrane separators were assembled into Li/LiFePO4 cells and these cells delivered high capacities and exhibited good cycling performance at room temperature. In addition, cells using centrifugally-spun PMMA/PAN membrane separators showed superior C-rate performance compared to those using microporous polypropylene (PP membranes. It is, therefore, demonstrated that centrifugally-spun PMMA/PAN membranes are promising separator candidate for high-performance Li-ion batteries.

  16. 离心静电纺丝的模式%Modes of Centrifugal Electrospinning

    Institute of Scientific and Technical Information of China (English)

    彭浩; 张敬男; 李秀红; 宋庆松; 刘勇


    The mechanism and characteristics of centrifugal electrospinning were introduced. According to the different spinning materials,the centrifugal electrospinning was devided into solution centrifugal electrospinning and melt centrifugal electrospinning. The devices of the two type centrifugal electrospinning were divided into two types:conventional mode and revised mode. The structural characteristics,the advantages and disadvantages of all kinds of devices were summarized. The problems of the centrifugal electrospinning were pointed out and some advices for improvement were proposed.%介绍了离心静电纺丝的原理及特点,根据纺丝介质的不同,将离心静电纺丝分为溶液离心静电纺丝和熔体离心静电纺丝两类,并将这两类纺丝方法的装置分为常规模式和改进模式,总结了各种装置的结构特征、纺丝的优缺点。指出了现阶段离心静电纺丝存在的一些问题,并提出了相应的改进方案。

  17. Development of a fully integrated analysis system for ions based on ion-selective optodes and centrifugal microfluidics (United States)

    Johnson, R. D.; Badr, I. H.; Barrett, G.; Lai, S.; Lu, Y.; Madou, M. J.; Bachas, L. G.; Daunert, S. (Principal Investigator)


    A fully integrated, miniaturized analysis system for ions based on a centrifugal microfluidics platform and ion-selective optode membranes is described. The microfluidic architecture is composed of channels, five solution reservoirs, a measuring chamber, and a waste reservoir manufactured onto a disk-shaped substrate of poly(methyl methacrylate). Ion-selective optode membranes, composed of plasticized poly(vinyl chloride) impregnated with an ionophore, a proton chromoionophore, and a lipophilic anionic additive, were cast, with a spin-on device, onto a support layer and then immobilized on the disk. Fluid propulsion is achieved by the centrifugal force that results from spinning the disk, while a system of valves is built onto the disk to control flow. These valves operate based on fluid properties and fluid/substrate interactions and are controlled by the angular frequency of rotation. With this system, we have been able to deliver calibrant solutions, washing buffers, or "test" solutions to the measuring chamber where the optode membrane is located. An analysis system based on a potassium-selective optode has been characterized. Results indicate that optodes immobilized on the platform demonstrate theoretical responses in an absorbance mode of measurement. Samples of unknown concentration can be quantified to within 3% error by fitting the response function for a given optode membrane using an acid (for measuring the signal for a fully protonated chromoionophore), a base (for fully deprotonated chromoionophore), and two standard solutions. Further, the ability to measure ion concentrations by employing one standard solution in conjunction with acid and base and with two standards alone were studied to delineate whether the current architecture could be simplified. Finally, the efficacy of incorporating washing steps into the calibration protocol was investigated.

  18. Defining the needs for gas centrifuge enrichment plants advanced safeguards

    Energy Technology Data Exchange (ETDEWEB)

    Boyer, Brian David [Los Alamos National Laboratory; Erpenbeck, Heather H [Los Alamos National Laboratory; Miller, Karen A [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Ianakiev, Kiril [Los Alamos National Laboratory; Marlow, Johnna B [Los Alamos National Laboratory


    Current safeguards approaches used by the International Atomic Energy Agency (IAEA) at gas centrifuge enrichment plants (GCEPs) need enhancement in order to verify declared low-enriched (LEU) production, detect undeclared LEU production and detect highly enriched uranium (HEU) production with adequate detection probability using nondestructive assay (NDA) techniques. At present inspectors use attended systems, systems needing the presence of an inspector for operation, during inspections to verify the mass and {sup 235}U enrichment of declared UF{sub 6} containers used in the process of enrichment at GCEPs. In verifying declared LEU production, the inspectors also take samples for off-site destructive assay (DA) which provide accurate data, with 0.1% to 0.5% measurement uncertainty, on the enrichment of the UF{sub 6} feed, tails, and product. However, taking samples of UF{sub 6} for off-site analysis is a much more labor and resource intensive exercise for the operator and inspector. Furthermore, the operator must ship the samples off-site to the IAEA laboratory which delays the timeliness of results and interruptions to the continuity of knowledge (CofK) of the samples during their storage and transit. This paper contains an analysis of possible improvements in unattended and attended NDA systems such as process monitoring and possible on-site analysis of DA samples that could reduce the uncertainty of the inspector's measurements and provide more effective and efficient IAEA GCEPs safeguards. We also introduce examples advanced safeguards systems that could be assembled for unattended operation.

  19. Development of centrifugal casting high speed steel rolls

    Institute of Scientific and Technical Information of China (English)

    Hanguang Fu; Aimin Zhao; Jiandong Xing


    The present study aims at developing the high speed steel (HSS) as roll materials to replace the traditional roll materials such as the alloy cast iron and powder metallurgical (PM) hard alloy. The HSS roll billet was formed by centrifugal casting, and the billet was rough machined after soften annealing heat treatment, then it was quenched and tempered to get suitable hardness and toughness. After that the HSS roll was finish machined to the final dimension of φ285 mm in the outer diameter, φ160 mm in the inner diameter and 120 mm in width and its surface hardness was tested. Finally the HSS roll was used in high speed wire rod mill. The test results show that a high and homogeneous hardness can obtain on the work surface of HSS rolls, the surface hardness is 63-65HRC and its variation is smaller than 2HRC. The impact toughness of this kind of HSS is about 16 J/cra2. The results of on-line service investigation in high speed wire rod mill indicate that the HSS rolls have excellent wear resistance, the steel rolling quantity per mm of HSS rolls is 3120 t, the service life-span of HSS rolls is 4 times longer than that of high chromium cast iron rolls and it is close to that of the PM hard alloy rolls. The manufacturing burden of HSS rolls is obviously lower than that of the PM hard alloy rolls, it is only 25% of that of the PM hard alloy rolls.

  20. Direct digital manufacturing of autonomous centrifugal microfluidic device (United States)

    Ukita, Yoshiaki; Takamura, Yuzuru; Utsumi, Yuichi


    This paper presents strategies that attempt to solve two key problems facing the commercialization of microfluidics: cost reduction in microfluidic chip manufacturing and microfluidic device driver development. To reduce the cost of microfluidic chip manufacturing, we propose to use of three-dimensional (3D) printers for direct digital manufacturing (DDM). An evaluation of 3D micro-scale structure printing using several 3D printers is reported, and some of the technical issues to be addressed in the future are suggested. To evaluate micro-scale printing, three types of 3D printers, with the ability to print structures on the scale of several hundred meters, were selected by first screening six 3D printers. Line and space patterns with line widths of 100-500 µm and an aspect ratio of one were printed and evaluated. The estimated critical dimension was around 200 µm. The manufacturing of a monolithic microfluidic chip with embedded channels was also demonstrated. Monolithic microfluidic chips with embedded microchannels having 500 × 500 and 250 × 250 µm2 cross sections and 2-20 mm lengths were printed, and the fidelity of the channel shape, residual supporting material, and flow of liquid water were evaluated. The liquid flow evaluation showed that liquid water could flow through all of the microchannels with the 500 × 500 µm2 cross section, whereas this was not possible through some of the channels with the 250 × 250 µm2 cross section because of the residual resin or supporting material. To reduce the device-driver cost, we propose to use of the centrifugal microfluidic concept. An autonomous microfluidic device that could implement sequential flow control under a steadily rotating condition was printed. Four-step flow injection under a steadily rotating condition at 1500 rpm was successfully demonstrated without any external triggering such as changing the rotational speed.

  1. Sample of CFD optimization of a centrifugal compressor stage (United States)

    Galerkin, Y.; Drozdov, A.


    Industrial centrifugal compressor stage is a complicated object for gas dynamic design when the goal is to achieve maximum efficiency. The Authors analyzed results of CFD performance modeling (NUMECA Fine Turbo calculations). Performance prediction in a whole was modest or poor in all known cases. Maximum efficiency prediction was quite satisfactory to the contrary. Flow structure in stator elements was in a good agreement with known data. The intermediate type stage “3D impeller + vaneless diffuser+ return channel” was designed with principles well proven for stages with 2D impellers. CFD calculations of vaneless diffuser candidates demonstrated flow separation in VLD with constant width. The candidate with symmetrically tampered inlet part b3 / b2 = 0,73 appeared to be the best. Flow separation takes place in the crossover with standard configuration. The alternative variant was developed and numerically tested. The obtained experience was formulated as corrected design recommendations. Several candidates of the impeller were compared by maximum efficiency of the stage. The variant with gas dynamic standard principles of blade cascade design appeared to be the best. Quasi - 3D non-viscid calculations were applied to optimize blade velocity diagrams - non-incidence inlet, control of the diffusion factor and of average blade load. “Geometric” principle of blade formation with linear change of blade angles along its length appeared to be less effective. Candidates’ with different geometry parameters were designed by 6th math model version and compared. The candidate with optimal parameters - number of blades, inlet diameter and leading edge meridian position - is 1% more effective than the stage of the initial design.

  2. Centrifugal contactor operations for UREX process flowsheet. An update

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Candido [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)


    The uranium extraction (UREX) process separates uranium, technetium, and a fraction of the iodine from the other components of the irradiated fuel in nitric acid solution. In May 2012, the time, material, and footprint requirements for treatment of 260 L batches of a solution containing 130 g-U/L were evaluated for two commercial annular centrifugal contactors from CINC Industries. These calculated values were based on the expected volume and concentration of fuel arising from treatment of a single target solution vessel (TSV). The general conclusions of that report were that a CINC V-2 contactor would occupy a footprint of 3.2 m 2 (0.25 m x 15 m) if each stage required twice the nominal footprint of an individual stage, and approximately 1,131 minutes or nearly 19 hours is required to process all of the feed solution. A CINC V-5 would require approximately 9.9 m 2 (0.4 m x 25 m) of floor space but would require only 182 minutes or ~ 3 hours to process the spent target solution. Subsequent comparison with the Modular Caustic Side Solvent Extraction Unit (MCU) at Savannah River Site (SRS) in October 2013 suggested that a more compact arrangement is feasible, and the linear dimension for the CINC V-5 may be reduced to about 8 m; a comparable reduction for the CINC V-2 yields a length of 5 m. That report also described an intermediate-scale (10 cm) contactor design developed by Argonne in the early 1980s that would better align with the SHINE operations as they stood in May 2012. In this report, we revisit the previous evaluation of contactor operations after discussions with CINC Industries and analysis of the SHINE process flow diagrams for the cleanup of the TSV, which were not available at the time of the first assessment.

  3. Neuro-Motor Responses to Daily Centrifugation in Bed-Rested Subjects (United States)

    Reschke, Millard F.; Somers, Jeffery T.; Krnavek, Jody; Fisher, Elizibeth; Ford, George; Paloski, William H.


    It is well known from numerous space flight studies that exposure to micro-g produces both morphological and neural adaptations in the major postural muscles. However, the characteristics and mechanism of these changes, particularly when it may involve the central nervous system are not defined. Furthermore, it is not known what role unloading of the muscular system may have on central changes in sensorimotor function or if centrifugation along the +Gz direction (long body axis) can mitigate both the peripheral changes in muscle function and modification of the central changes in sensorimotor adaptation to the near weightless environment of space flight. The purpose of this specific effort was, therefore, to investigate the efficacy of artificial gravity (AG) as a method for maintaining sensorimotor function in micro-g. Eight male subjects were exposed to daily 1 hr centrifugation during a 21 day 6 degree head-down bed rest study. Seven controls were placed on the centrifuge without rotation. The radius and angular velocity of the centrifuge were adjusted such that each subject experienced a centripetal acceleration of 2.5g at the feet, and approximately 1.0g at the heart. Both the tendon (MSR) and functional stretch reflexes (FSR) were collected using an 80 lb. ft. servomotor controlled via position feedback to provide a dorsiflexion step input to elicit the MSR, and the same step input with a built in 3 sec hold to evoke the FSR. EMG data were obtained from the triceps surae. Supplementary torque, velocity and position data were collected with the EMG responses. All data were digitized and sampled at 4 kHz. Only the MSR data has been analyzed at this time, and preliminary results suggest that those subjects exposed to active centrifugation (treatment group) show only minor changes in MSR peak latency times, either as a function of time spent in bed rest or exposure to centrifugation, while the control subjects show delays in the MSR peak latencies that are

  4. 离心铸造凝固过程的流场和温度场数值模拟%Numerical Simulation on Flow and Temperature Filed in Centrifugal Casting Solidification Process

    Institute of Scientific and Technical Information of China (English)

    徐耀增; 杜振拴; 宋绪丁


    In a centrifugal casting process, the fluid flow and temperature filed eventually determine the quality and characteristics of final high speed steel composite roll. A three dimensional solidification model coupling of heat transfer and flow of molten metal in horizontal centrifugal casting on high speed steel composite roll was established, it can calculate the distribution of temperature filed and flow filed under gravity and centrifugal force by using CFD software FLUENT. The reason for free surface which is eccentrically distributed is also discussed. The analysis results can contribute to the understanding of flow filed in centrifugal casting process and centrifugal casting technology in optimized design.%离心铸造高速钢轧辊的质量和性能取决于离心铸造过程金属液流的流动和温度变化规律.本文建立了高速钢复合轧辊卧式离心铸造在凝固过程中金属液传热和流动的三维耦合模型,采用大型CFD软件FLUENT求解得到重力和离心力作用下的温度场、流场分布,并讨论了金属液自由液面呈偏心分布的原因.分析结果对离心铸造过程中流场的认识和工艺优化设计具有参考意义.

  5. Fluid Redistribution and Heart Rate in Humans During Whole-Body Tilting, G(z) Centrifugation, and Lower Body Negative Pressure (United States)

    Watenpaugh, D. E.; Breit, G. A.; Ballard, R. E.; Murthy, G.; Hargens, A. R.


    Gravity creates blood pressure gradients which redistribute body fluids towards the feet. Positive G(z) centrifugation and lower body negative pressure (LBNP) have been proposed to simulate these and other effects of gravity during long-term existence in microgravity. We hypothesized that the magnitude of upper-to-lower body fluid redistribution would increase according to the following order: short-arm centrifugation (SAC), long-arm centrifugation (LAC), head-up tilt (HUT), and LBNP. To test this hypothesis, we employed strain gauge plethysmography of the neck, thigh and calf during HUT and supine SAC and LAC up to lG(z) at the feet, and during supine LBNP to 100 mm Hg. Supine 100 mm Hg LBNP generates footward force and produces transmural blood pressures in the foot approximately equal to 1 G(z) (90 deg) HUT. Heart rate was measured via cardiotachometry. Control measurements were made while supine. SAC and LAC elicited similar increases in thigh volume at 1 G(z) (2.3 +/- 0.4 and 2.1 +/- 0.1%, respectively; mean +/- se, n greater than or equal to 7). At 100 mm Hg LBNP, thigh volume increased (3.4 +/- 0.3%) significantly more than during l G(z) centrifugation (p less than 0.05). Surprisingly, due to a paradoxical 0.6% reduction of thigh volume between 0.8 and 1.0 G(z) HUT, thigh volume was increased only 0.6 +/- 0.3% at 1 G(z) HUT. The calf demonstrated similar, although less definitive, responses to the various gravitational stimuli. Neck volume tended to decrease less during HUT than during the other stimuli. Heart rate increased similarly during HUT (18 +/- 2 beats/min) and LAC (12 +/- 2 beats/min), and exhibited still greater elevation during LBNP (29 +/- 4 beats/min), yet did not increase during SAC. These results suggest upright posture activates mechanisms that counteract footward fluid redistribution which are not activated during supine applications of simulated gravity. LAC more closely approximated effects of normal gravity (HUT) than LBNP. Therefore

  6. 多级离心泵流场优化及验证%Flow Field Optimization and Experimental Verification of Multi-stage Centrifugal Pumps

    Institute of Scientific and Technical Information of China (English)

    张权; 周盼; 率志君; 李玩幽


    Fluid exciting force is one of the important vibration sources of centrifugal pump which transmits outward through the pump shell and bearings. So, flow field optimization can effectively reduce the fluid exciting forces and vibration sources to improve the centrifugal pump’s vibration characteristic. In this paper, reduction of vibration and noise of a multi-stage centrifugal pump is studied. To begin with, CFD simulation technology is applied to optimize the flow field of the pump in the two aspects of cutting impeller and changing the shape of the volute. Then, the pressure pulsations and flow field excitation forces before and after the optimization are compared and analyzed. Afterwards, the method of cutting impeller is selected considering the requirements of processing technology. Finally the effectiveness is indirectly verified by analyzing the change of vibration response of the pump’s seats. The results show that cutting impeller and changing the tongue shape can reduce the pressure pulsation and fluid exciting force of the pump under blades’frequencies and octave frequencies, and the rear-seat vibration response after the cutting is reduced by 4 dB.%流体激励力是离心泵主要振源之一。通过对离心泵流场进行优化,可有效降低泵组流体激励力,减小离心泵振动。以多级离心泵的减振降噪为研究目的,运用CFD仿真技术从切割叶轮及改变蜗壳形状两个方面对流场进行优化。通过对比优化前后压力脉动以及流场激励力变化,说明优化情况。最后考虑加工工艺要求,选择切割叶轮的优化方法,并通过机脚振动响应的变化间接验证改善效果。结果表明:切割叶轮与改变隔舌形状对离心泵叶频及其倍频下的压力脉动与流体激励力都有减小,切割叶轮后机脚响应降低了4 dB。

  7. Hypolipidemic activities of xanthorrhizol purified from centrifugal TLC. (United States)

    Oon, Seok Fang; Nallappan, Meenakshii; Kassim, Nur Kartinee; Shohaimi, Shamarina; Sa'ariwijaya, Mohd Shazrul Fazry; Tee, Thiam Tsui; Cheah, Yew Hoong


    Hyperlipidemia is defined as the presence of either hypertriglyceridemia or hypercholesterolemia, which could cause atherosclerosis. Although hyperlipidemia can be treated by hypolipidemic drugs, they are limited due to lack of effectiveness and safety. Previous studies demonstrated that xanthorrhizol (XNT) isolated from Curcuma xanthorrhizza Roxb. reduced the levels of free fatty acid and triglyceride in vivo. However, its ability to inhibit cholesterol uptake in HT29 colon cells and adipogenesis in 3T3-L1 cells are yet to be reported. In this study, XNT purified from centrifugal TLC demonstrated 98.3% purity, indicating it could be an alternative purification method. The IC50 values of XNT were 30.81 ± 0.78 μg/mL in HT29 cells and 35.07 ± 0.24 μg/mL in 3T3-L1 adipocytes, respectively. Cholesterol uptake inhibition study using HT29 colon cells showed that XNT (15 μg/mL) significantly inhibited the fluorescent cholesterol analogue NBD uptake by up to 27 ± 3.1% relative to control. On the other hand, higher concentration of XNT (50 μg/mL) significantly suppressed the growth of 3T3-L1 adipocytes (5.9 ± 0.58%) compared to 3T3-L1 preadipocytes (81.31 ± 0.55%). XNT was found to impede adipogenesis of 3T3-L1 adipocytes in a dose-dependent manner from 3.125 to 12.5 μg/mL, where 12.5 μg/mL significantly suppressed 36.13 ± 2.1% of lipid accumulation. We postulate that inhibition of cholesterol uptake, adipogenesis, preadipocyte and adipocyte number may be utilized as treatment modalities to reduce the prevalence of lipidemia. To conclude, XNT could be a potential hypolipidemic agent to improve cardiovascular health in the future.

  8. Effect of self recirculation casing treatment on the performance of a turbocharger centrifugal compressor (United States)

    Gancedo, Matthieu

    Increase in emission regulations in the transport industry brings the need to have more efficient engines. A path followed by the automobile industry is to downsize the size of the internal combustion engine and increase the air density at the intake to keep the engine power when needed. Typically a centrifugal compressor is used to force the air into the engine, it can be powered from the engine shaft (superchargers) or extracting energy contained into the hot exhaust gases with a turbine (turbochargers). The flow range of the compressor needs to match the one of the engine. However compressors mass flow operating range is limited by choke on the high end and surge on the low end. In order to extend the operation at low mass flow rates, the use of passive devices for turbocharger centrifugal compressors was explored since the late 80's. Hence, casing treatments including flow recirculation from the inducer part of the compressor have been shown to move the surge limit to lower flows. Yet, the working mechanisms are still not well understood and thus, to optimize the design of this by-pass system, it is necessary to determine the nature of the changes induced by the device both on the dynamic stability of the pressure delivery and on the flow at the inlet. The compressor studied here features a self-recirculating casing treatment at the inlet. The recirculation passage could be blocked to carry a direct comparison between the cases with and without the flow feature. To grasp the effect on compressor stability, pressure measurements were taken in the different constituting elements of the compressor. The study of the mean pressure variations across the operating map showed that the tongue region is a limiting element. Dynamic pressure measurements revealed that the instabilities generated near the inducer when the recirculation is blocked increase the overall instability levels at the compressor outlet and propagating pressure waves starting at the tongue occurred

  9. A new non-synchronous preparative counter-current centrifuge-the next generation of dynamic extraction/chromatography devices with independent mixing and settling control, which offer a step change in efficiency. (United States)

    Ignatova, Svetlana; Hawes, David; van den Heuvel, Remco; Hewitson, Peter; Sutherland, Ian A


    A new and significantly more robust design of non-synchronous coil planet centrifuge is introduced where the degree of mixing between two immiscible phases can be changed independently from the "g" field required to separate out the phases. A hypothesis that an optimum ratio between the speed of the bobbin and the speed of the rotor can be found to optimise the efficiency of the separation for a given force field is upheld for an intermediate polarity phase system. This paves the way for extensive further research to find the optimum non-synchronous conditions for a range of different phase systems that are desirable for the separation of large molecules, proteins and biologics but can tend to emulsify in the standard "J" type centrifuge systems currently available and routinely in use for aqueous organic phase systems. A step change of up to 30% in resolution and 90% in plate efficiency is demonstrated.

  10. Effects of the number of inducer blades on the anti-cavitation characteristics and external performance of a centrifugal pump

    Energy Technology Data Exchange (ETDEWEB)

    Guo, XiaoMei; Shi, GaoPing [Zhejiang University of Water Resources and Electric Power, Hangzhou (China); Zhu, ZuChao; Cui, BaoLing [Zhejiang Sci-Tech University, Hangzhou (China)


    Installing an inducer upstream of the main impeller is an effective approach for improving the anti-cavitation performance of a high speed centrifugal pump. For a high-speed centrifugal pump with an inducer, the number of inducer blades can affect its internal flow and external performance. We studied the manner in which the number of inducer blades can affect the anti-cavitation characteristics and external performance of a centrifugal pump. We first use the Rayleigh-Plesset equation and the mixture model to simulate the vapor liquid flow in a centrifugal pump with an inducer, and then predict its external performance. Finally, we tested the external performance of a centrifugal pump with 2-, 3- and 4-bladed inducers, respectively. The results show that the simulations of external performance in a centrifugal pump are in accordance with our experiments. Based on this, we obtained vapor volume fraction distributions for the inducer, the impeller, and in the corresponding whole flow parts. We discovered that the vapor volume fraction of a centrifugal pump with a 3- bladed inducer is less than that of a centrifugal pump with 2- or 4-bladed inducers, which means that a centrifugal pump with a 3-bladed inducer has a better external and anti-cavitation performance.

  11. Centrifugal step emulsification applied for absolute quantification of nucleic acids by digital droplet RPA. (United States)

    Schuler, Friedrich; Schwemmer, Frank; Trotter, Martin; Wadle, Simon; Zengerle, Roland; von Stetten, Felix; Paust, Nils


    Aqueous microdroplets provide miniaturized reaction compartments for numerous chemical, biochemical or pharmaceutical applications. We introduce centrifugal step emulsification for the fast and easy production of monodisperse droplets. Homogenous droplets with pre-selectable diameters in a range from 120 μm to 170 μm were generated with coefficients of variation of 2-4% and zero run-in time or dead volume. The droplet diameter depends on the nozzle geometry (depth, width, and step size) and interfacial tensions only. Droplet size is demonstrated to be independent of the dispersed phase flow rate between 0.01 and 1 μl s(-1), proving the robustness of the centrifugal approach. Centrifugal step emulsification can easily be combined with existing centrifugal microfluidic unit operations, is compatible to scalable manufacturing technologies such as thermoforming or injection moulding and enables fast emulsification (>500 droplets per second and nozzle) with minimal handling effort (2-3 pipetting steps). The centrifugal microfluidic droplet generation was used to perform the first digital droplet recombinase polymerase amplification (ddRPA). It was used for absolute quantification of Listeria monocytogenes DNA concentration standards with a total analysis time below 30 min. Compared to digital droplet polymerase chain reaction (ddPCR), with processing times of about 2 hours, the overall processing time of digital analysis was reduced by more than a factor of 4.

  12. Experimental Study on Series Operation of Sliding Vane Pump and Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Tao Li


    Full Text Available A platform for sliding vane pump and centrifugal pump tests is installed to study the series operation of them under different characteristics of pipeline. Firstly, the sliding vane pump and the centrifugal pump work independently, and the performance is recorded. Then, the two types of pumps are combined together, with the sliding vane pump acting as the feeding pump. Comparison is made between the performance of the independently working pump and the performance of series operation pump. Results show that the system flow rate is determined by the sliding vane pump. In order to ensure the stability of the series operation pumping system, the energy consumption required by the pipeline under the system flow should be greater than the pressure energy centrifugal pump can generate. Otherwise, the centrifugal pump can not operate stably, with reflux, swirl, gas-liquid two-phase flow in the runner and strong vibration and noise. The sliding vane pump can be in serial operation with the centrifugal pump under limited conditions.

  13. Influence of recovery method and centrifugation on epididymal sperm from collared peccaries (Pecari tajacu Linnaeus, 1758). (United States)

    Bezerra, José Artur Brilhante; da Silva, Andréia Maria; Peixoto, Gislayne Christianne Xavier; da Silva, Mariana de Araújo; Franco de Oliveira, Moacir; Silva, Alexandre Rodrigues


    In order to establish protocols for gamete recovery from accidentally killed wild animals, or to take advantage of those slaughtered by captive breeders, we assess the influence of two methods on the recovery of epididymal sperm from collared peccaries, and verify the effect of centrifugation on such gametes. Genitalia from nine animals were used. For each animal, one epididymis was processed by flotation and the other was processed by retrograde flushing, both using a buffered media based on Tris. Following recovery, sperm were evaluated for motility, vigor, viability, functional membrane integrity, and morphology. A 1-mL aliquot of each sample was centrifuged, the supernatant removed, and the pellet suspended and evaluated as fresh samples. The sperm characteristics did not differ between the samples collected by flotation or retrograde flushing (P < 0.05). Centrifugation promoted an increase in head and tail defects, thus reducing the percentage of viable sperm (P < 0.05). No other parameter assessed for both methods was affected by centrifugation. In conclusion, epididymal sperm from collared peccaries can be efficiently collected through flotation or retrograde flushing, but not when either is followed by centrifugation.

  14. Prediction and Reduction of Aerodynamic Noise of the Multiblade Centrifugal Fan

    Directory of Open Access Journals (Sweden)

    Shuiqing Zhou


    Full Text Available An aerodynamic and aeroacoustic investigation of the multiblade centrifugal fan is proposed in this paper, and a hybrid technique of combining flow field calculation and acoustic analysis is applied to solve the aeroacoustic problem of multiblade centrifugal fan. The unsteady flow field of the multiblade centrifugal fan is predicted by solving the incompressible Reynolds-averaged Navier-Stokes (RANS equations with conventional computing techniques for fluid dynamics. The principal noise source induced is extracted from the calculation of the flow field by using acoustic principles, and the modeled sources on inner and outer surfaces of the volute are calculated with multiregional boundary element method (BEM. Through qualitative analysis, the sound pressure amplitude distribution of the multiblade centrifugal fan in near field is given and the sound pressure level (SPL spectrum diagram of monitoring points in far field is obtained. Based on the analysis results, the volute tongue structure is adjusted and then a low-noise design for the centrifugal fan is proposed. The comparison of noise tests shows the noise reduction of improved fan model is more obvious, which is in good agreement with the prediction using the hybrid techniques.

  15. Clinical use of centrifugal pumps and the roller pump in open heart surgery: a comparative evaluation. (United States)

    Yoshikai, M; Hamada, M; Takarabe, K; Okazaki, Y; Ito, T


    Centrifugal pumps have been used widely as the main pump in open heart surgery to reduce damage to blood elements and to reduce the activation of the coagulation system. The purpose of this study was the evaluation and comparison of the effects of two types of centrifugal pumps and of one type of roller pump on blood elements, the coagulation system, complements, and immunoglobulins. Two types of centrifugal pumps (Lifestream; St. Jude Medical, Chelmsford, Massachusetts; and BP-80: Medtronic, BioMedicus, Inc., Eden Prairie, Minnesota, U.S.A.) and one roller pump (Mera Co.) were used separately as the main pump for cardiopulmonary bypass (CPB) in 29 patients. Platelet counts, lactate dehydrogenase, antithrombin III, thrombin-antithrombin complex (TAT), complements (C3, C4, and CH50) and immunoglobulins G, A, and M values were measured before and after CPB and compared. Values, except those for TAT, showed no significant difference among the three groups. The TAT values increased less in each of the centrifugal pump groups than in the roller pump group. This finding suggests that thrombin synthesis might be suppressed by the use of a centrifugal pump.

  16. Robust design optimization method for centrifugal impellers under surface roughness uncertainties due to blade fouling (United States)

    Ju, Yaping; Zhang, Chuhua


    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  17. Robust Design Optimization Method for Centrifugal Impellers under Surface Roughness Uncertainties Due to Blade Fouling

    Institute of Scientific and Technical Information of China (English)

    JU Yaping; ZHANG Chuhua


    Blade fouling has been proved to be a great threat to compressor performance in operating stage. The current researches on fouling-induced performance degradations of centrifugal compressors are based mainly on simplified roughness models without taking into account the realistic factors such as spatial non-uniformity and randomness of the fouling-induced surface roughness. Moreover, little attention has been paid to the robust design optimization of centrifugal compressor impellers with considerations of blade fouling. In this paper, a multi-objective robust design optimization method is developed for centrifugal impellers under surface roughness uncertainties due to blade fouling. A three-dimensional surface roughness map is proposed to describe the nonuniformity and randomness of realistic fouling accumulations on blades. To lower computational cost in robust design optimization, the support vector regression (SVR) metamodel is combined with the Monte Carlo simulation (MCS) method to conduct the uncertainty analysis of fouled impeller performance. The analyzed results show that the critical fouled region associated with impeller performance degradations lies at the leading edge of blade tip. The SVR metamodel has been proved to be an efficient and accurate means in the detection of impeller performance variations caused by roughness uncertainties. After design optimization, the robust optimal design is found to be more efficient and less sensitive to fouling uncertainties while maintaining good impeller performance in the clean condition. This research proposes a systematic design optimization method for centrifugal compressors with considerations of blade fouling, providing a practical guidance to the design of advanced centrifugal compressors.

  18. Centrifugal Effects in a Bose-Einstein Condensate

    CERN Document Server

    Kuklov, A B; Levine, A M; Schreiber, W M; Birman, J L; Birman, Joseph L.


    Single particle states in the atomic trap employing the rotating magnetic field are found using the full time-dependent instantaneous trapping potential. These states are compared with those of the effective time-averaged potential. We show that the trapping is possible when the frequency of the rotations exceeds some threshold. Slightly above this threshold the weakly interacting gas of the trapped atoms acquires the properties of a quasi-1D system in the frame rotating together with the field. The role of the atom-atom interaction in changing the ideal gas solution is discussed. We show that in the limit of large numbers of particles the rotating field whose angular frequency is appropriately modulated can be utilized as a driving force principally for the center of mass motion as well as for the angular momentum $L = 2$ normal modes of the Bose condensate. A mechanism of quantum evaporation forced by the rotating field is analyzed.

  19. A centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria. (United States)

    Choi, Goro; Jung, Jae Hwan; Park, Byung Hyun; Oh, Seung Jun; Seo, Ji Hyun; Choi, Jong Seob; Kim, Do Hyun; Seo, Tae Seok


    In this study, we developed a centrifugal direct recombinase polymerase amplification (direct-RPA) microdevice for multiplex and real-time identification of food poisoning bacteria contaminated milk samples. The microdevice was designed to contain identical triplicate functional units and each unit has four reaction chambers, thereby making it possible to perform twelve direct-RPA reactions simultaneously. The integrated microdevice consisted of two layers: RPA reagents were injected in the top layer, while spiked milk samples with food poisoning bacteria were loaded into sample reservoirs in the bottom layer. For multiplex bacterial detection, the target gene-specific primers and probes were dried in each reaction chamber. The introduced samples and reagents could be equally aliquoted and dispensed into each reaction chamber by centrifugal force, and then the multiplex direct-RPA reaction was executed. The target genes of bacteria spiked in milk could be amplified at 39 °C without a DNA extraction step by using the direct-RPA cocktails, which were a combination of a direct PCR buffer and RPA enzymes. As the target gene amplification proceeded, the increased fluorescence signals coming from the reaction chambers were recorded in real-time at an interval of 2 min. The entire process, including the sample distribution, the direct-RPA reaction, and the real-time analysis, was accomplished with a custom-made portable genetic analyzer and a miniaturized optical detector. Monoplex, duplex, and triplex food poisoning bacteria (Salmonella enterica, Escherichia coli O157:H7, and Vibrio parahaemolyticus) detection was successfully performed with a detection sensitivity of 4 cells per 3.2 μL of milk samples within 30 min. By implementing the direct-PRA on the miniaturized centrifugal microsystem, the on-site food poisoning bacteria analysis would be feasible with high speed, sensitivity, and multiplicity.

  20. Centrifuge modelling of large diameter pile in sand subject to lateral loading

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    and cyclic behaviour of large diameter rigid piles in dry sand by use of physical modelling. The physical modelling has been carried out at Department of Civil Engineering at the Danish Technical University (DTU.BYG), in the period from 2005 to 2009. The main centrifuge facilities, and especially...... the equipment for lateral load tests were at the start of the research in 2005 outdated and a major part of the work with the geotechnical centrifuge included renovation and upgrading of the facilities. The research with respect to testing of large diameter piles included:  Construction of equipment...... with embedment lengths of 6, 8 and 10 times the diameter. The tests have been carried out with a load eccentricity of 2.5 m to 6.5 m above the sand surface. The present report includes a description of the centrifuge facilities, applied test procedure and equipment along with presentation of the obtained results....

  1. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films.

    KAUST Repository

    Kim, Jin Young


    Centrifugal casting of composites and ceramics has been widely employed to improve the mechanical and thermal properties of functional materials. This powerful method has yet to be deployed in the context of nanoparticles--yet size-effect tuning of quantum dots is among their most distinctive and application-relevant features. Here we report the first gradient nanoparticle films to be constructed in a single step. By creating a stable colloid of nanoparticles that are capped with electronic-conduction-compatible ligands we were able to leverage centrifugal casting for thin-films devices. This new method, termed centrifugal colloidal casting, is demonstrated to form films in a bandgap-ordered manner with efficient carrier funnelling towards the lowest energy layer. We constructed the first quantum-gradient photodiode to be formed in a single deposition step and, as a result of the gradient-enhanced electric field, experimentally measured the highest normalized detectivity of any colloidal quantum dot photodetector.

  2. A comparative evaluation of fluidized bed assisted drag finishing and centrifugal disk dry finishing

    Directory of Open Access Journals (Sweden)

    M. Barletta


    Full Text Available Drag finishing of brass (Cu-30 wt.% Zn rings using fluidized abrasives, which is a new finishing technology, is comparatively evaluated with centrifugal disk finishing. The comparison was performed by selecting the same abrasive granulates of two different sizes and operating the equipment for the same processing time or at their respective maximum speeds. The experimental analysis investigated the change in workpiece morphology, material removal during finishing and dimensional accuracy. The results showed that each of the types of equipment investigated in the study were capable of a high finishing performance with a relatively short processing time. However, fluidized bed assisted drag finishing was more effective than centrifugal disk finishing in both the achievable quality of the processed parts and reduced processing time. In contrast, centrifugal disk finishing was preferable whenever low erosion and stringent dimensional tolerances were demanded.

  3. Direct calculation of acceleration field through homogeneous transformation for two-axis centrifuge

    Institute of Scientific and Technical Information of China (English)

    吴广玉; 任顺清; 陈希军


    A precision centrifuge is an inertial navigation test equipment used for calibrating the characteristicsof accelerometers with high overloading, and a two-axis centrifuge can be used to generate either constant accel-eration or harmonic acceleration. The moving trajectory equation about the origin of the accelerometer coordinatesystem in a two-axis centrifuge was directly deduced through homogeneous transformation. The acceleration vec-tor of the origin in accelerometer coordinate system was achieved by making the second derivative of this trajec-tory equation. The acceleration components were acquired by decomposing this acceleration vector along thethree axes of the accelerometer coordinate system. The correctness of the homogeneous transformation was veri-fied through vector analysis.

  4. Enhanced versatility of fluid control in centrifugal microfluidic platforms using two degrees of freedom. (United States)

    Cao, Xiaobao; deMello, A J; Elvira, K S


    Centrifugal microfluidic platforms have significant potential in commercial applications because of their operational flexibility and minimal external infrastructure requirements. However, the dynamic and real-time control of fluid flow within traditional centrifugal microfluidic platforms is problematic. To address this significant limitation, we propose a two degrees of freedom platform, in which a digital servo is located at each end of an arm driven by a motor. This allows for reversible inward pumping between multiple chambers with perfect efficiency. Furthermore, the addition of a second degree of freedom allows position-based pressure controlled burst valves to be accessed and operated in an independent fashion. To demonstrate the efficacy of this technical innovation, we show rapid and configurable flow switching between three target chambers within a centrifugal microfluidic device.

  5. Influence of Prewhirl Regulation by Inlet Guide Vanes on Cavitation Performance of a Centrifugal Pump

    Directory of Open Access Journals (Sweden)

    Lei Tan


    Full Text Available The influence of prewhirl regulation by inlet guide vanes (IGVs on a centrifugal pump performance is investigated experimentally and numerically. The experimental results show that IGVs can obviously change the head and increase the efficiency of the tested centrifugal pump over a wide range of flow rates. Although the cavitation performance is degraded, the variation of the cavitation critical point is less than 0.5 m. Movement of the computed three-dimensional streamlines in suction pipe and impeller are analyzed in order to reveal the mechanism how the IGVs realize the prewhirl regulation. The calculated results show that the influence of IGVs on the cavitation performance of centrifugal pump is limited by a maximum total pressure drop of 1777 Pa, about 7.6% of the total pressure at the suction pipe inlet for a prewhirl angle of 24°.

  6. Optimization and analysis of centrifugal pump considering fluid-structure interaction. (United States)

    Zhang, Yu; Hu, Sanbao; Zhang, Yunqing; Chen, Liping


    This paper presents the optimization of vibrations of centrifugal pump considering fluid-structure interaction (FSI). A set of centrifugal pumps with various blade shapes were studied using FSI method, in order to investigate the transient vibration performance. The Kriging model, based on the results of the FSI simulations, was established to approximate the relationship between the geometrical parameters of pump impeller and the root mean square (RMS) values of the displacement response at the pump bearing block. Hence, multi-island genetic algorithm (MIGA) has been implemented to minimize the RMS value of the impeller displacement. A prototype of centrifugal pump has been manufactured and an experimental validation of the optimization results has been carried out. The comparison among results of Kriging surrogate model, FSI simulation, and experimental test showed a good consistency of the three approaches. Finally, the transient mechanical behavior of pump impeller has been investigated using FSI method based on the optimized geometry parameters of pump impeller.


    Institute of Scientific and Technical Information of China (English)

    LI Jun; FENG Zhen-ping; TSUKAMOTO Hiroshi


    This paper presents a hydrodynamic redesign of the conventional vaned diffuser into the low solidity vaned diffuser for the maximum static pressure recovery in a centrifugal pump. A Bezier curve representation for profile description was coupled with a blade-to-blade flow calculation and a real-coded genetic algorithm. A low solidity vaned diffuser of 0.89 in solidity was obtained through the present optimum design. Numerical analysis and experimental test were made to evaluate the hydrodynamic performance of the centrifugal pump with the designed low solidity vaned diffuser and original vaned diffuser. The obtained results demonstrate that the centrifugal pump with the optimized vaned diffuser has compact size compared with the original one while the performance requirements have been met.

  8. The margin of safety in the use of a straight path centrifugal blood pump. (United States)

    Kijima, T; Nojiri, C; Oshiyama, H; Horiuchi, K; Nogawa, A; Hamasaki, H; Ogihara, M; Katsuda, H S; Amano, N; Fukasawa, H


    A new centrifugal blood pump with a rotor that arranges 6 straight paths radially was developed for open heart surgery and temporary circulatory support. We describe comparative studies of the margin of safety in the practical use of the new pump. This pump was evaluated for temperature increase, cavitation, and pressure sensitivity. Two commercially available centrifugal pumps, the Biomedicus cone type and the Sarns 3M impeller type, were used as control pumps. The temperature increase in the new pump was four times slower than in the impeller pump when the outlet and the inlet of the pump was clamped. No sign of cavitation was observed when 0.1 ml air was introduced to the pump inlet under a negative pressure of 200 mm Hg in fresh bovine blood. As for pressure sensitivity of centrifugal pumps in practical applications, circuit resistance was a more essential factor than flow-pressure curves of the pump.

  9. Numerical Simulation of Solidification of Work Roll in Centrifugal Casting Process

    Institute of Scientific and Technical Information of China (English)

    Nannan Song; Yikun Luan; Yunlong Bai; Z.A. Xu; Xiuhong Kang; Dianzhong Li


    A program on the solidification process of horizontal centrifugal casting coupled with eutectic carbides segregation has been developed in this paper. Due to the geometrical features of work roll, a cylindrical coordinate system was used. The temperature field of the outer layer at the end of filling process was imported as the initial temperature condition for the solidification process. The model of eutectic carbides segregation caused by different densities between eutectic MC and the molten steel was coupled in the program. The temperature field of the outer layer of work roll during horizontal centrifugal casting process was investigated. Results show that the outer layer has a "sandwich shape" solid fraction manner. Results also indicate that the segregation of eutectic MC is quite severe during centrifugal casting process. It forms four zones of different content of carbides in radial direction. The simulated results of MC carbides segregation phenomenon agree with the experimental observations.

  10. Solidified structure of thin-walled titanium parts by vertical centrifugal casting

    Directory of Open Access Journals (Sweden)

    Wu Shiping


    Full Text Available The solidified structure of the thin-walled and complicated Ti-6Al-4V castings produced by the vertical centrifugal casting process was studied in the present work. The results show that the wall thickness of the section is featured with homogeneously distributed fine equiaxial grains, compared with the microstructure of the thick-walled section. The grain size of the castings has a tendency to decrease gradually with the increasing of the centrifugal radius. The inter-lamellar space in thick-walled casting parts is bigger than that of the thin-walled parts, and the profile of inter-lamellar space is not susceptible to the centrifugal radius.

  11. Single-step fabrication of quantum funnels via centrifugal colloidal casting of nanoparticle films (United States)

    Kim, Jin Young; Adinolfi, Valerio; Sutherland, Brandon R.; Voznyy, Oleksandr; Kwon, S. Joon; Kim, Tae Wu; Kim, Jeongho; Ihee, Hyotcherl; Kemp, Kyle; Adachi, Michael; Yuan, Mingjian; Kramer, Illan; Zhitomirsky, David; Hoogland, Sjoerd; Sargent, Edward H.


    Centrifugal casting of composites and ceramics has been widely employed to improve the mechanical and thermal properties of functional materials. This powerful method has yet to be deployed in the context of nanoparticles--yet size-effect tuning of quantum dots is among their most distinctive and application-relevant features. Here we report the first gradient nanoparticle films to be constructed in a single step. By creating a stable colloid of nanoparticles that are capped with electronic-conduction-compatible ligands we were able to leverage centrifugal casting for thin-films devices. This new method, termed centrifugal colloidal casting, is demonstrated to form films in a bandgap-ordered manner with efficient carrier funnelling towards the lowest energy layer. We constructed the first quantum-gradient photodiode to be formed in a single deposition step and, as a result of the gradient-enhanced electric field, experimentally measured the highest normalized detectivity of any colloidal quantum dot photodetector.

  12. An Experimental Investigation on the Drying of Sliced Food Products in Centrifugal Fluidized Bed

    Institute of Scientific and Technical Information of China (English)

    M.H.Shi; Y.L.Hao; 等


    An experimental investigation on the fluidization and drying characteristics of sliced food products in a centrifugal fluidized bed dryer was carried out,The rotaing speed ranges from 300 rpm to 500 rpm.Sliced potato and radish were used as the testing materials.The results show that the sliced materials can be fluidized well in the centrifugal fluidized bed.The fluidized curve has a maximum value and the critical fluidized velocities vary with the type of the test material,its shape and dimension as well as operating parameters.The sliced food materials can be dried very well and fast in the centrifugal fluidized bed with a large productivity.The factors that influence the drying process were examined and discussed.The final shape and inner structure of the dried products were observed.The water recovery characteristics of the drried products were also investigated.

  13. Performance analysis on solid-liquid mixed flow in a centrifugal pump (United States)

    Ning, C.; Wang, Y.


    In order to study the solid-liquid mixed flow hydraulic characteristics of centrifugal pump, the Pro/E software was used for three-dimensional modeling of centrifugal pump chamber. By using the computational fluid dynamics software CFX, the numerical simulation calculation of solid-liquid two-phase flow within whole flow passage of centrifugal pump was conducted. Aim at different particle diameters, the Reynolds-averaged N-S equations with the RNG k-Ɛ turbulence model and SIMPLEC algorithm were used to simulate the two-phase flow respectively on the condition of different volume fraction. The influence of internal flow characteristic on pump performance was analyzed. On the conditions of different particle diameter and different volume fraction, the turbulence kinetic energy and particle concentration are analyzed. It can be found that the erosion velocity ratio on the flow channel wall increases along with the increasing of the volume fraction

  14. Parametric Study and Design Optimization of Centrifugal Pump Impeller-A Review

    Directory of Open Access Journals (Sweden)

    Vijaypratap R Singh ,


    Full Text Available Centrifugal pumps are widely used for irrigation, water supply plants, steam power plants, sewage, oil refineries, chemical plants, hydraulic power service, food processing factories and mines, because of their suitability in practically any service. Therefore it is necessary to find out the design parameters and working conditions that yield optimal output and maximum efficiency with lowest power consumption. Study indicates that Computational fluid dynamics (CFD analysis is being increasingly applied in the design of centrifugal pumps. With the aid of the CFD approach, the complex internal flows in water pump impellers, can be well predicted, to speed up the pump design procedure. This paper exposes the various research work carried out in this direction especially in the content of parametric study and optimization of centrifugal pump impeller using CFD tool and DoE technique. Literature surveys indicate that very restricted work has been done in this area.

  15. Damages on pumps and systems the handbook for the operation of centrifugal pumps

    CERN Document Server

    Merkle, Thomas


    Damage on Pumps and Systems. The Handbook for the Operation of Centrifugal Pumps offers a combination of the theoretical basics and practical experience for the operation of circulation pumps in the engineering industry. Centrifugal pumps and systems are extremely vulnerable to damage from a variety of causes, but the resulting breakdown can be prevented by ensuring that these pumps and systems are operated properly. This book provides a total overview of operating centrifugal pumps, including condition monitoring, preventive maintenance, life cycle costs, energy savings and economic aspects. Extra emphasis is given to the potential damage to these pumps and systems, and what can be done to prevent breakdown. Addresses specific issues about pumping of metal chips, sand, abrasive dust and other solids in fluidsEmphasis on economic and efficiency aspects of predictive maintenance and condition monitoring Uses life cycle costs (LCC) to evaluate and calculate the costs of pumping systems

  16. Evaluation of conventional castaneda and lysis centrifugation blood culture techniques for diagnosis of human brucellosis. (United States)

    Mantur, Basappa G; Mangalgi, Smita S


    We investigated the role of the lysis centrifugation blood culture technique over the conventional Castaneda technique for the diagnosis of human brucellosis. The lysis centrifugation technique has been found to be more sensitive in both acute (20% higher sensitivity; P < 0.00001) and chronic (40% higher sensitivity; P = 0.087) forms of brucellosis. The major advantage of lysis centrifugation was in the mean detection time, which was only 2.4 days in acute and 2.7 days in chronic cases, with 103 out of 110 (93.6%) and 17 out of 20 (85%) cultures from acute and chronic brucellosis, respectively, detected before the conventional culture was positive. Our results confirmed the potential usefulness of the lysis technique in diagnosis and institution of appropriate antibiotic therapy.

  17. Effects of Continuous and Interrupted Forces on Gene Transcription in Periodontal Ligament Cells in Vitro

    Directory of Open Access Journals (Sweden)

    Seyed Nasser Ostad


    Full Text Available The biological mechanisms of tooth movement are based on the response of periodontal tissues to mechanical forces. The final result of these responses is remodeling of the extracellular matrix. Tissue reactions may vary depending upon the type, magnitude and duration of the applied forces. The purpose of the present study was to analyze the effects of centrifugal force on the transcription of collagen type-I (Col-I, matrix metalloproteinase-1 (MMP-1, and tissue inhibitor of metalloproteinase- 1 (TIMP-1 genes in human periodontal ligament (PDL fibroblasts. Human fibroblasts obtained from the PDL were cultured and subjected to centrifugal forces (36.3 g/cm2 for 30, 60 and 90 min continuously. This was also carried out interruptedly, three times for 30 min and six times for 15 min. The mRNAs encoding for Col-I, MMP-1, and TIMP-1 were quantified using RT-PCR. The mRNA levels of Col-I and MMP-1 were increased when continuous force was applied for 30 min and 60 min respectively. The interrupted force had almost no effect on Col-I, MMP-1 and TIMP-1 genes. These results indicate that continuous forces may have a greater effect in inducing gene expression during the remodeling process of PDL compared to interrupted forces with short rest periods.

  18. Short communication. Stallion sperm quality after combined ejaculate fractionation and colloidal centrifugation

    Directory of Open Access Journals (Sweden)

    Francisco Crespo


    Full Text Available This study investigated the possible additive benefit of ejaculate fractionation and colloidal centrifugation on stallion sperm quality. Using an open-end artificial vagina, the sperm-rich fraction (FRAC-1 was separated from the rest of the ejaculate (FRAC-2 and a third sperm sample representing the combined ejaculate was reconstituted post-ejaculation (RAW. Each semen sample was processed for colloidal centrifugation. The percentage of abnormal spermatozoa was 17.8 ± 7.0% in RAW and 14.6 ± 9.5% in FRAC-1 but decreased to 11.4 ± 4.7% and 9.6 ± 6.9% respectively, after colloidal centrifugation. A sperm DNA fragmentation index of 10.9 ± 5.1% was observed in RAW and 7.5 ± 2.4% in FRAC-1 semen collected with the AV but this decreased to 7.8 ± 2.8% and 5.2 ± 2.3% after colloidal centrifugation. The rate of increase in sperm DNA fragmentation during the first 6 h of incubation at 37 ºC was 1.8 ± 0.9% per hour in RAW semen and 2.0 ± 2.0% per hour in FRAC-1 but this significantly decreased to 1.3 ± 1.4% and 0.9 ± 0.8% respectively after colloidal centrifugation. While stallion seminal characteristics can be improved using colloidal centrifugation, further enhancement is possible if the ejaculate is initially fractionated.

  19. Centrifugation:an important pre-analytic procedure that influences plasma microRNA quantification during blood processing

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hui Zheng; Cui Cui; Xin-Xi Zhou; Yi-Xin Zeng; Wei-Hua Jia


    Circulating microRNAs are robustly present in plasma or serum and have become a research focus as biomarkers for tumor diagnosis and prognosis. Centrifugation is a necessary procedure for obtaining high-quality blood supernatant. Herein, we investigated one-step and two-step centrifugations, two centrifugal methods routinely used in microRNA study, to explore their effects on plasma microRNA quantification. The microRNAs obtained from one-step and two-step centrifugations were quantified by microarray and TaqMan-based real-time quantitative polymerase chain reaction (Q-PCR). Dynamic light scattering was performed to explore the difference underlying the two centrifugal methods. The results from the microarray containing 1,347 microRNAs showed that the signal detection rate was greatly decreased in the plasma sample prepared by two-step centrifugation. More importantly, the microRNAs missing in this plasma sample could be recovered and detected in the precipitate generated from the second centrifugation. Consistent with the results from microarray, a marked decrease of three representative microRNAs in two-step centrifugal plasma was validated by Q-PCR. According to the size distribution of all nanoparticles in plasma, there were fewer nanoparticles with size >1,000 nm in two-step centrifugal plasma. Our experiments directly demonstrated that different centrifugation methods produced distinct quantities of plasma microRNAs. Thus, exosomes or protein complexes containing microRNAs may be involved in large nanoparticle formation and may be precipitated after two-step centrifugation. Our results remind us that sample processing methods should be first considered in conducting research.

  20. Centrifugal separation and equilibration dynamics in an electron-antiproton plasma

    CERN Document Server

    Andresen, G B; Baquero-Ruiz, Marcelo; Bertsche, William; Bowe, Paul D; Butler, Eoin; Cesar, Claudio L; Chapman, Steven; Charlton, Michael; Deller, A; Eriksson, S; Fajans, Joel; Friesen, Tim; Fujiwara, Makoto C; Gill, David R; Gutierrez, A; Hangst, Jeffrey S; Hardy, Walter N; Hayden, Michael E; Humphries, Andrew J; Hydomako, Richard; Jonsell, Svante; Madsen, Niels; Menary, Scott; Nolan, Paul; Olin, Art; Povilus, Alexander; Pusa, Petteri; Robicheaux, Francis; Sarid, Eli; Silveira, Daniel M; So, Chukman; Storey, James W; Thompson, Robert I; van der Werf, Dirk P; Wurtele, Jonathan S; Yamazaki, Yasunori


    Charges in cold, multiple-species, non-neutral plasmas separate radially by mass, forming centrifugally-separated states. Here, we report the first detailed measurements of such states in an electron-antiproton plasma, and the first observations of the separation dynamics in any centrifugally-separated system. While the observed equilibrium states are expected and in agreement with theory, the equilibration time is approximately constant over a wide range of parameters, a surprising and as yet unexplained result. Electron-antiproton plasmas play a crucial role in antihydrogen trapping experiments.