WorldWideScience

Sample records for magnetic nanocarrier bearing

  1. A multifunctional magnetic nanocarrier bearing fluorescent dye for targeted drug delivery by enhanced two-photon triggered release.

    Science.gov (United States)

    Banerjee, Shashwat S; Chen, Dong-Hwang

    2009-05-06

    We report a novel nanoformulation for targeted drug delivery which utilizes nanophotonics through the fusion of nanotechnology with biomedical application. The approach involves an energy-transferring magnetic nanoscopic co-assembly fabricated of rhodamine B (RDB) fluorescent dye grafted gum arabic modified Fe(3)O(4) magnetic nanoparticle and photosensitive linker by which dexamethasone drug is conjugated to the magnetic nano-assembly. The advantage offered by this nanoformulation is the indirect photo-triggered-on-demand drug release by efficient up-converting energy of the near-IR (NIR) light to higher energy and intraparticle energy transfer from the dye grafted magnetic nanoparticle to the linker for drug release by cleavage. The synthesized nanoparticles were found to be of ultra-small size (13.33 nm) and are monodispersed in an aqueous suspension. Dexamethasone (Dexa) drug conjugated to RDB-GAMNP by photosensitive linker showed appreciable release of Dexa by photo-triggered response on exposure to radiation having a wavelength in the NIR region whereas no detectable release was observed in the dark. Photo-triggered response for the nanoformulation not bearing the rhodamine B dye was drastically less as less Dexa was released on exposure to NIR radiation which suggest that the photo-cleavage of linker and release of Dexa mainly originated from the indirect excitation through the uphill energy conversions based on donor-acceptor model FRET. The promising pathway of nanophotonics for the on-demand release of the drug makes this nanocarrier very promising for applications in nanomedicine.

  2. Magnetic Bearing

    Science.gov (United States)

    1996-01-01

    AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

  3. Axial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2008-01-01

    Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

  4. Cryogenic Hybrid Magnetic Bearing

    Science.gov (United States)

    Meeks, Crawford R.; Dirusso, Eliseo; Brown, Gerald V.

    1994-01-01

    Cryogenic hybrid magnetic bearing is example of class of magnetic bearings in which permanent magnets and electromagnets used to suspend shafts. Electromagnets provide active control of position of shaft. Bearing operates at temperatures from -320 degrees F (-196 degrees C) to 650 degrees F (343 degrees C); designed for possible use in rocket-engine turbopumps, where effects of cryogenic environment and fluid severely limit lubrication of conventional ball bearings. This and similar bearings also suitable for terrestrial rotating machinery; for example, gas-turbine engines, high-vacuum pumps, canned pumps, precise gimbals that suspend sensors, and pumps that handle corrosive or gritty fluids.

  5. Radial Halbach Magnetic Bearings

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  6. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  7. Synthesis of thermosensitive magnetic nanocarrier for controlled sorafenib delivery

    Energy Technology Data Exchange (ETDEWEB)

    Heidarinasab, Amir [Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Ahmad Panahi, Homayon [Department of Chemistry, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Faramarzi, Mehdi, E-mail: faramarzi.iaug@gmail.com [Department of Chemical Engineering, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Farjadian, Fatemeh [Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz (Iran, Islamic Republic of)

    2016-10-01

    Allyl glycidyl ether/N-isopropylacrylamide-grafted magnetic nanoparticles were prepared using silica-coated magnetic nanoparticles as a substrate for radical copolymerization of allyl glycidyl ether and N-isopropylacrylamide. Chitosan was coupled with the prepared nanoparticles by opening the epoxy ring of the allyl glycidyl ether. The thermosensitive magnetic nanocarrier (TSMNC) obtained can be applied as a potent drug carrier. The TSMNC structure was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, vibrating sample magnetometer, and elemental analysis. Its morphology and size were investigated using field emission scanning electron microscopy, transmission electron microscopy and dynamic light scattering. The feasibility of employing the TSMNC for adsorption and in vitro controlled release of the chemotherapeutic agent sorafenib was tested. The effect of the adsorption parameters of pH, temperature, and loading time of sorafenib onto TSMNC was evaluated. The adsorption data was fitted to the Langmuir and Freundlich isotherms and the relevant parameters derived. The drug release profile indicated that 88% of the adsorbed drug was released within 35 h at 45 °C and drug release was Fickian diffusion-controlled. The results confirmed that the TSMNC has a high adsorption capacity at low temperature and good controlled release in a slow rate at a high temperature and could be developed for further application as a drug nanocarrier. - Graphical abstract: Magnetic nanoparticles were functionalized with chitosan and N-isopropylacrylamide. It was evaluated for sorafenib (SFB) adsorption and tested as a controlled-release system in response to changes in temperature. The TSMNC showed superparamagnetic properties with a high adsorption capacity and desirable controlled release at below and above LCST. Display Omitted - Highlights: • A TSMNC was synthesized for controlled

  8. Magnetic bearings for cryogenic turbomachines

    Science.gov (United States)

    Iannello, Victor; Sixsmith, Herbert

    1991-01-01

    Magnetic bearings offer a number of advantages over gas bearings for the support of rotors in cryogenic turboexpanders and compressors. Their performance is relatively independent of the temperature or pressure of the process gas for a large range of conditions. Active magnetic bearing systems that use capacitive sensors have been developed for high speed compressors for use in cryogenic refrigerators. Here, the development of a magnetic bearing system for a miniature ultra high speed compressor is discussed. The magnetic bearing has demonstrated stability at rotational speeds exceeding 250,000 rpm. This paper describes the important features of the magnetic bearing and presents test results demonstrating its performance characteristics.

  9. Magnetic Bearing Consumes Low Power

    Science.gov (United States)

    Studer, P. A.

    1982-01-01

    Energy-efficient linear magnetic bearing maintains a precise small separation between its moving and stationary parts. Originally designed for cryogenic compressors on spacecraft, proposed magnetic bearing offers an alternative to roller or gas bearing in linear motion system. Linear noncontacting bearing operates in environments where lubricants cannot be used.

  10. Hybrid superconductor magnet bearings

    Science.gov (United States)

    Chu, Wei-Kan

    1995-01-01

    Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

  11. Magnetic bearings grow more attractive

    Science.gov (United States)

    1993-10-01

    Advances in materials and electronics have enabled designers to devise simpler, smaller magnetic bearings. As a result, costs have dropped, widening the applications for these very-low-friction devices. Avcon (Advanced Controls Technology) has patented a permanent-magnet bias actively controlled bearing. Here high-energy rare earth permanent-magnet materials supply the basic bearing load levitation, while servo-driven electromagnets generate stabilization and centering forces for motion contol. Previous heavy-duty magnetic bearings used electromagnets entirely for suspension and control, which led to large bearings and control systems with higher power requirements. Avcon has developed several types of permanent-magnet bias bearings. The simplest is the radial repulsion bearing. Avcon's homopolar permanent-magnet bias active bearing is the most versatile of the company's designs.

  12. Aerospace applications of magnetic bearings

    Science.gov (United States)

    Downer, James; Goldie, James; Gondhalekar, Vijay; Hockney, Richard

    1994-01-01

    Magnetic bearings have traditionally been considered for use in aerospace applications only where performance advantages have been the primary, if not only, consideration. Conventional wisdom has been that magnetic bearings have certain performance advantages which must be traded off against increased weight, volume, electric power consumption, and system complexity. These perceptions have hampered the use of magnetic bearings in many aerospace applications because weight, volume, and power are almost always primary considerations. This paper will review progress on several active aerospace magnetic bearings programs at SatCon Technology Corporation. The magnetic bearing programs at SatCon cover a broad spectrum of applications including: a magnetically-suspended spacecraft integrated power and attitude control system (IPACS), a magnetically-suspended momentum wheel, magnetic bearings for the gas generator rotor of a turboshaft engine, a vibration-attenuating magnetic bearing system for an airborne telescope, and magnetic bearings for the compressor of a space-rated heat pump system. The emphasis of these programs is to develop magnetic bearing technologies to the point where magnetic bearings can be truly useful, reliable, and well tested components for the aerospace community.

  13. Prototype testing of magnetic bearings

    Science.gov (United States)

    Plant, David P.; Jayaraman, Chaitanya P.; Frommer, David A.; Kirk, James A.; Anand, Davinder K.

    1987-01-01

    The testing and evaluation of the performance of a magnetic bearing assembly for flywheel energy storage applications are discussed. The experimental set up for determining the passive radial stiffness, active radial stiffness, and curent force sensitivity of the coils follows the method developed by Frommer (1986). Magnetic bearings design should preclude saturation and current limiting in the desired operating range, so that the system will be linear. A larger linear range will lead to a more stable magnetic bearing.

  14. Touchdown Ball-Bearing System for Magnetic Bearings

    Science.gov (United States)

    Kingsbury, Edward P.; Price, Robert; Gelotte, Erik; Singer, Herbert B.

    2003-01-01

    The torque-limited touchdown bearing system (TLTBS) is a backup mechanical-bearing system for a high-speed rotary machine in which the rotor shaft is supported by magnetic bearings in steady-state normal operation. The TLTBS provides ball-bearing support to augment or supplant the magnetic bearings during startup, shutdown, or failure of the magnetic bearings. The TLTBS also provides support in the presence of conditions (in particular, rotational acceleration) that make it difficult or impossible to control the magnetic bearings or in which the magnetic bearings are not strong enough (e.g., when the side load against the rotor exceeds the available lateral magnetic force).

  15. Diacyllipid micelle-based nanocarrier for magnetically guided delivery of drugs in photodynamic therapy.

    Science.gov (United States)

    Cinteza, Ludmila O; Ohulchanskyy, Tymish Y; Sahoo, Yudhisthira; Bergey, Earl J; Pandey, Ravindra K; Prasad, Paras N

    2006-01-01

    We report the design, synthesis using nanochemistry, and characterization of a novel multifunctional polymeric micelle-based nanocarrier system, which demonstrates combined function of magnetophoretically guided drug delivery together with light-activated photodynamic therapy. Specifically, the nanocarrier consists of polymeric micelles of diacylphospholipid-poly(ethylene glycol) (PE-PEG) coloaded with the photosensitizer drug 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), and magnetic Fe3O4 nanoparticles. The nanocarrier shows excellent stability and activity over several weeks. The physicochemical characterizations have been carried out by transmission electron micrography and optical spectroscopy. An efficient cellular uptake has been confirmed with confocal laser scanning microscopy. The loading efficiency of HPPH is practically unaffected upon coloading with the magnetic nanoparticles, and its phototoxicity is retained. The magnetic response of the nanocarriers was demonstrated by their magnetically directed delivery to tumor cells in vitro. The magnetophoretic control on the cellular uptake provides enhanced imaging and phototoxicity. These multifunctional nanocarriers demonstrate the exciting prospect offered by nanochemistry for targeting photodynamic therapy.

  16. Magnetic Bearings at Draper Laboratory

    Science.gov (United States)

    Kondoleon, Anthony S.; Kelleher, William P.; Possel, Peter D.

    1996-01-01

    Magnetic bearings, unlike traditional mechanical bearings, consist of a series of components mated together to form a stabilized system. The correct design of the actuator and sensor will provide a cost effective device with low power requirements. The proper choice of a control system utilizes the variables necessary to control the system in an efficient manner. The specific application will determine the optimum design of the magnetic bearing system including the touch down bearing. Draper for the past 30 years has been a leader in all these fields. This paper summarizes the results carried out at Draper in the field of magnetic bearing development. A 3-D radial magnetic bearing is detailed in this paper. Data obtained from recently completed projects using this design are included. One project was a high radial load (1000 pound) application. The second was a high speed (35,000 rpm), low loss flywheel application. The development of a low loss axial magnetic bearing is also included in this paper.

  17. Nonlinear Control of Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    Khac Duc Do; Dang Hoe Nguyen; Thanh Binh Nguyen

    2010-01-01

    In this paper, recent results controling nonlinear systems with output tracking error constraints are applied to the design of new tracking controllers for magnetic bearings. The proposed controllers can force the rotor to track a bounded and sufficiently smooth refer-ence trajectory asymptotically and guarantee non-contactedness be-tween the rotor and the stator of the magnetic bearings. Simulation results are included to illustrate the effectiveness of the proposed con-trollers.

  18. A Passive Magnetic Bearing Flywheel

    Science.gov (United States)

    Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

    2002-01-01

    A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  19. Active Magnetic BearingsMagnetic Forces

    DEFF Research Database (Denmark)

    Kjølhede, Klaus

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... validation and leads to novel approaches in identifying crucial rotor parameters. This is the main focus of this paper, where an intelligent AMB is being developed with the aim of aiding the accurate identification of damping and stiffness coefficients of journal bearings and seals. The main contribution...... of the magnetic forces are led by using different experimental tests: (I) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor; (II) by measuring the input current and bearing...

  20. Magnetically guided central nervous system delivery and toxicity evaluation of magneto-electric nanocarriers

    Science.gov (United States)

    Kaushik, Ajeet; Jayant, Rahul D.; Nikkhah-Moshaie, Roozbeh; Bhardwaj, Vinay; Roy, Upal; Huang, Zaohua; Ruiz, Ariel; Yndart, Adriana; Atluri, Venkata; El-Hage, Nazira; Khalili, Kamel; Nair, Madhavan

    2016-01-01

    Least component-based delivery of drug-tagged-nanocarriers across blood-brain-barriers (BBB) will allow site-specific and on-demand release of therapeutics to prevent CNS diseases. We developed a non-invasive magnetically guided delivery of magneto-electric nanocarriers (MENCs), ~20 nm, 10 mg/kg, across BBB in C57Bl/J mice. Delivered MENCs were uniformly distributed inside the brain, and were non-toxic to brain and other major organs, such as kidney, lung, liver, and spleen, and did not affect hepatic, kidney and neurobehavioral functioning. PMID:27143580

  1. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  2. Magnetic bearings with zero bias

    Science.gov (United States)

    Brown, Gerald V.; Grodsinsky, Carlos M.

    1991-01-01

    A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

  3. Trend of Self-bearing Motors(Magnetic Bearings)

    OpenAIRE

    上野, 哲; Satoshi, UENO; 立命館大学

    2008-01-01

    This paper introduces a trend of a self-bearing motor that combines the functions of a motor and active magnetic bearing. The self-bearing motor has advantages, such as miniaturization, low cost, and high speed rotation in addition to the advantages of the active magnetic bearing. Various types of self-bearing motors such as a radial type, axial type, permanent magnet type, induction type, and reluctance type, have been proposed. In this paper, technologies and applications of the self-bearin...

  4. Axial force calculation of passive magnetic bearing

    National Research Council Canada - National Science Library

    Vučković Ana N; Raičević Nebojša B; Ilić Saša S; Aleksić Slavoljub R; Perić Mirjana T

    2014-01-01

    .... Configuration like this one resembles the one passive magnetic bearing has. Force calculation is performed using semi analytical approach based on fictitious magnetization charges and discretization technique...

  5. Fault Tolerant Homopolar Magnetic Bearings

    Science.gov (United States)

    Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

    2003-01-01

    Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

  6. Electromechanical properties of radial active magnetic bearings

    OpenAIRE

    Antila, Matti

    1998-01-01

    Nonideal properties of the electromagnetic actuators in radial active magnetic bearings are studied. The two dimensional nonlinear stationary finite element method is used to determine the linearised parameters of a radial active magnetic bearing. The method is verified on two test machines. The accuracy is 10-15 % in the magnetic saturation region. The effect of magnetic saturation on the bearing dynamics is studied based on the root locus diagrams of the closed loop system. These diagrams s...

  7. Current leads and magnetic bearings

    Science.gov (United States)

    Hull, J. R.

    1993-10-01

    Since the discovery of high temperature superconductors (HTS's), Argonne National Laboratory (ANL) has been active in a broad spectrum of activities in developing these materials for applications. Work at every stage of development has involved industrial collaboration in order to accelerate commercialization. While most of the development work has been devoted to improving the properties of current-carrying wires, some effort has been devoted to applications that can utilize HTS's with properties available now or in the near future. In this paper, advances made in the area of current leads and magnetic bearings are discussed.

  8. Multimodal magnetic nano-carriers for cancer treatment: Challenges and advancements

    Science.gov (United States)

    Aadinath, W.; Ghosh, Triroopa; Anandharamakrishnan, C.

    2016-03-01

    Iron oxide nanoparticles (IONPs) have been a propitious topic for cancer treatment in recent years because of its multifunctional theranostic applications under magnetic field. Two such widely used applications in cancer biology are gradient magnetic field guided targeting and alternative magnetic field (AMF) induced local hyperthermia. Gradient magnetic field guided targeting is a mode of active targeting of therapeutics conjugated with iron oxide nanoparticles. These particles also dissipate heat in presence of AMF which causes thermal injury to the cells of interest, for example tumour cells and subsequent death. Clinical trials divulge the feasibility of such magnetic nano-carrier as a promising candidate in cancer biology. However, these techniques need further investigations to curtail certain limitations manifested. Recent progresses in response have shrunken the barricade to certain extent. In this context, principles, challenges associated with these applications and recent efforts made in response will be discussed.

  9. Automated Assistance for Designing Active Magnetic Bearings

    Science.gov (United States)

    Imlach, Joseph

    2008-01-01

    MagBear12 is a computer code that assists in the design of radial, heteropolar active magnetic bearings (AMBs). MagBear12 was developed to help in designing the system described in "Advanced Active-Magnetic-Bearing Thrust-Measurement System". Beyond this initial application, MagBear12 is expected to be useful for designing AMBs for a variety of rotating machinery. This program incorporates design rules and governing equations that are also implemented in other, proprietary design software used by AMB manufacturers. In addition, this program incorporates an advanced unpublished fringing-magnetic-field model that increases accuracy beyond that offered by the other AMB-design software.

  10. Magnetic norbornene polymer as multiresponsive nanocarrier for site specific cancer therapy.

    Science.gov (United States)

    Rao N, Vijayakameswara; Ganivada, Mutyala Naidu; Sarkar, Santu; Dinda, Himadri; Chatterjee, Koushik; Dalui, Tanmoy; Das Sarma, Jayasri; Shunmugam, Raja

    2014-02-19

    A site-specific, stimuli-responsive nanocarrier has been synthesized by conjugating folate, magnetic particles and doxorubicin to the backbone of norbornene polymer. Monomers, namely, cis-5-norbornene-6-(diethoxyphosphoryl)hexanote (mono 1), norbornene grafted poly(ethyleneglycol)-folate (mono 2), and norbornene derived doxorubicin (mono 3) are carefully designed to demonstrate the smart nanorcarrier capabilities. The synthesis and complete characterization of all three monomers are elaborately discussed. Their copolymerization is done by controlled/living ring-opening metathesis polymerization (ROMP) to get the triblock copolymer PHOS-FOL-DOX. NMR spectroscopy and gel permeation chromatography confirm the formation of the triblock copolymer, while FT-IR spectroscopy, thermogravimetric analysis, along with transmission electron microscope confirm the anchoring of iron particle (Fe3O4) to the PHOS-FOL-DOX. Drug release profile shows the importance of having the hydrazone linker that helps to release the drug exactly at the mild acidic conditions resembling the pH of the cancerous cells. The newly designed nanocarrier shows greater internalization (about 8 times) due to magnetic field. Also, increased intracellular DOX release is observed due to the folate receptor. From these results, it is clear that PHOS-FOL-DOX has the potential to act as a smart nanoreservoir with the magnetic field guidance, folate receptor targeting, and finally pH stimulation.

  11. Cyclodextrin conjugated magnetic colloidal nanoparticles as a nanocarrier for targeted anticancer drug delivery

    Science.gov (United States)

    Banerjee, Shashwat S.; Chen, Dong-Hwang

    2008-07-01

    A novel magnetic nanocarrier (CD-GAMNPs) was fabricated for targeted anticancer drug delivery by grafting cyclodextrin (CD) onto gum arabic modified magnetic nanoparticles (GAMNPs) using hexamethylene diisocyanate (HMDI) as a linker. Analyses by transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the product had a mean diameter of 17.1 nm and a mean hydrodynamic diameter of 44.1 nm. The CD grafting was confirmed by Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) indicated that the amount of CD grafted on the GAMNPs was 16.8 mg g-1. The study on the loading of anticancer drug all-trans-retinoic acid (retinoic acid) revealed that the newly fabricated magnetic nanocarrier possessed a considerably higher adsorption capability as compared to GAMNPs due to the special hydrophobic cavity structure of CD, which could act as a host-guest complex with retinoic acid. Furthermore, it was found that the complexation of CD-GAMNPs with retinoic acid was exothermic and the presence of a surfactant (sodium dodecyl sulfate) led to the decrease in the inclusion of retinoic acid because the linear structure of sodium dodecyl sulfate made it easier to enter the cavity of CD as compared to less linear retinoic acid. In addition, the in vitro release profile of retinoic acid from CD-GAMNPs was characterized by an initial fast release followed by a delayed release phase.

  12. Cyclodextrin conjugated magnetic colloidal nanoparticles as a nanocarrier for targeted anticancer drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Banerjee, Shashwat S; Chen, D.-H. [Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)], E-mail: chendh@mail.ncku.edu.tw

    2008-07-02

    A novel magnetic nanocarrier (CD-GAMNPs) was fabricated for targeted anticancer drug delivery by grafting cyclodextrin (CD) onto gum arabic modified magnetic nanoparticles (GAMNPs) using hexamethylene diisocyanate (HMDI) as a linker. Analyses by transmission electron microscopy (TEM) and dynamic light scattering (DLS) revealed that the product had a mean diameter of 17.1 nm and a mean hydrodynamic diameter of 44.1 nm. The CD grafting was confirmed by Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) indicated that the amount of CD grafted on the GAMNPs was 16.8 mg g{sup -1}. The study on the loading of anticancer drug all-trans-retinoic acid (retinoic acid) revealed that the newly fabricated magnetic nanocarrier possessed a considerably higher adsorption capability as compared to GAMNPs due to the special hydrophobic cavity structure of CD, which could act as a host-guest complex with retinoic acid. Furthermore, it was found that the complexation of CD-GAMNPs with retinoic acid was exothermic and the presence of a surfactant (sodium dodecyl sulfate) led to the decrease in the inclusion of retinoic acid because the linear structure of sodium dodecyl sulfate made it easier to enter the cavity of CD as compared to less linear retinoic acid. In addition, the in vitro release profile of retinoic acid from CD-GAMNPs was characterized by an initial fast release followed by a delayed release phase.

  13. Chitosan-Gated Magnetic-Responsive Nanocarrier for Dual-Modal Optical Imaging, Switchable Drug Release, and Synergistic Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Mu, Qingxin [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Revia, Richard [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Wang, Kui [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Zhou, Xuezhe [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Pauzauskie, Peter J. [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA; Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Zhou, Shuiqin [Department of Chemistry, The College of Staten Island, City University of New York, Staten Island NY 10314 USA; Zhang, Miqin [Department of Materials Science and Engineering, University of Washington, Seattle WA 98195 USA

    2017-01-25

    In this study, we present a multifunctional yet structurally simple nanocarrier that has a high drug loading capacity, releases drug in response to onset of an AC magnetic field, and can serve as a long-term imaging contrast agent and effectively kills cancer cells by synergistic action. This nanocarrier (HMMC-NC) has a spherical shell structure with a center cavity of 80 nm in diameter. The shell is comprised of two layers: an inner layer of magnetite that exhibits superparamagnetism and an outer layer of mesoporous carbon embedded with carbon dots that exhibit photoluminescence property. Thus in addition to being a drug carrier, HMMC-NC is also a contrast agent for bioimaging. The switchable drug release is enabled by the chitosan molecules attached on the nanocarrier as the switching material which turns on or off the drug release in response to the application or withdrawal of an AC magnetic field.

  14. Permanent Magnetic Bearing for Spacecraft Applications

    Science.gov (United States)

    Morales, Winfredo; Fusaro, Robert; Kascak, Albert

    2008-01-01

    A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

  15. Non-contacting "snubber bearing" for passive magnetic bearing systems

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2017-08-22

    A new non-contacting magnetic "snubber" bearing is provided for application to rotating systems such as vehicular electromechanical battery systems subject to frequent accelerations. The design is such that in the equilibrium position the drag force of the snubber is very small (milliwatts). However in a typical case, if the rotor is displaced by as little as 2 millimeters a large restoring force is generated without any physical contact between the stationary and rotating parts of the snubber bearing.

  16. In vivo anticancer evaluation of the hyperthermic efficacy of anti-human epidermal growth factor receptor-targeted PEG-based nanocarrier containing magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Baldi G

    2014-06-01

    Full Text Available Giovanni Baldi,1 Costanza Ravagli,1 Filippo Mazzantini,1 George Loudos,2 Jaume Adan,3 Marc Masa,3 Dimitrios Psimadas,2 Eirini A Fragogeorgi,2 Erica Locatelli,4 Claudia Innocenti,5,6 Claudio Sangregorio,5,7 Mauro Comes Franchini4 1CERICOL, Sovigliana-Vinci, Italy; 2Technological Educational Institute of Athens, Athens, Greece; 3Leitat Technological Center, Barcelona, Spain; 4Department of Industrial Chemistry Toso Montanari, University of Bologna, Bologna, 5Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM, 6Dipartimento di Chimica U Schiff, Università di Firenze, Firenze, 7Centro Nazionale delle Ricerche (ICCOM – CNR, Firenze, Italy Abstract: Polymeric nanoparticles with targeting moieties containing magnetic nanoparticles as theranostic agents have considerable potential for the treatment of cancer. Here we report the chemical synthesis and characterization of a poly(D,L-lactide-co-glycolide-b-poly(ethylene glycol-based nanocarrier containing iron oxide nanoparticles and human epithelial growth factor receptor on the outer shell. The nanocarrier was also radiolabeled with 99mTc and tested as a theranostic nanomedicine, ie, it was investigated for both its diagnostic ability in vivo and its therapeutic hyperthermic effects in a standard A431 human tumor cell line. Following radiolabeling with 99mTc, the biodistribution and therapeutic hyperthermic effects of the nanosystem were studied noninvasively in vivo in tumor-bearing mice. A substantial decrease in tumor size correlated with an increase in both nanoparticle concentration and local temperature was achieved, confirming the possibility of using this multifunctional nanosystem as a therapeutic tool for epidermoid carcinoma. Keywords: magnetic nanoparticles, polymeric nanocarriers, skin cancer, hyperthermia, single-photon emission computed tomography, imaging

  17. Active magnetic bearings applied to industrial compressors

    Science.gov (United States)

    Kirk, R. G.; Hustak, J. F.; Schoeneck, K. A.

    1993-01-01

    The design and shop test results are given for a high-speed eight-stage centrifugal compressor supported by active magnetic bearings. A brief summary of the basic operation of active magnetic bearings and the required rotor dynamics analysis are presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofits of magnetic bearings in existing machinery are discussed with supporting analysis of a four-stage centrifugal compressor. The current status of industrial machinery in North America using this new support system is presented and recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  18. Passive Magnetic Bearing With Ferrofluid Stabilization

    Science.gov (United States)

    Jansen, Ralph; DiRusso, Eliseo

    1996-01-01

    A new class of magnetic bearings is shown to exist analytically and is demonstrated experimentally. The class of magnetic bearings utilize a ferrofluid/solid magnet interaction to stabilize the axial degree of freedom of a permanent magnet radial bearing. Twenty six permanent magnet bearing designs and twenty two ferrofluid stabilizer designs are evaluated. Two types of radial bearing designs are tested to determine their force and stiffness utilizing two methods. The first method is based on the use of frequency measurements to determine stiffness by utilizing an analytical model. The second method consisted of loading the system and measuring displacement in order to measure stiffness. Two ferrofluid stabilizers are tested and force displacement curves are measured. Two experimental test fixtures are designed and constructed in order to conduct the stiffness testing. Polynomial models of the data are generated and used to design the bearing prototype. The prototype was constructed and tested and shown to be stable. Further testing shows the possibility of using this technology for vibration isolation. The project successfully demonstrated the viability of the passive magnetic bearing with ferrofluid stabilization both experimentally and analytically.

  19. Bioconjugation of recombinant tissue plasminogen activator to magnetic nanocarriers for targeted thrombolysis

    Directory of Open Access Journals (Sweden)

    Yang HW

    2012-10-01

    Full Text Available Hung-Wei Yang,1,* Mu-Yi Hua,1,* Kun-Ju Lin,2,* Shiaw-Pyng Wey,3 Rung-Ywan Tsai,4 Siao-Yun Wu,5 Yi-Ching Lu,5 Hao-Li Liu,6 Tony Wu,7 Yunn-Hwa Ma5 1Chang Gung Molecular Medicine Research Center, Department of Chemical and Materials Engineering, 2Molecular Imaging Center, Department of Nuclear Medicine, Chang Gung Memorial Hospital, Kuei-Shan, Tao-Yuan, Taiwan, Republic of China; 3Department of Medical Imaging and Radiological Sciences, 4Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Hsin-chu, Taiwan, Republic of China; 5Department of Physiology and Pharmacology and Healthy Aging Research Center, 6Department of Electrical Engineering, Chang Gung University, Kuei-Shan, Tao-Yuan, Taiwan, Republic of China; 7Department of Neurology, Chang Gung University College of Medicine and Memorial Hospital, Tao-Yuan, Taiwan, Republic of China*These authors contributed equally to this workAbstract: Low-toxicity magnetic nanocarriers (MNCs composed of a shell of poly [aniline-co-N-(1-one-butyric acid aniline] over a Fe3O4 magnetic nanoparticle core were developed to carry recombinant tissue plasminogen activator (rtPA in MNC-rtPA for targeted thrombolysis. With an average diameter of 14.8 nm, the MNCs exerted superparamagnetic properties. Up to 276 µg of active rtPA was immobilized per mg of MNCs, and the stability of the immobilized rtPA was greatly improved during storage at 4°C and 25°C. In vitro thrombolysis testing with a tubing system demonstrated that magnet-guided MNC-rtPA showed significantly improved thrombolysis compared with free rtPA and reduced the clot lysis time from 39.2 ± 3.2 minutes to 10.8 ± 4.2 minutes. In addition, magnet-guided MNC-rtPA at 20% of the regular rtPA dose restored blood flow within 15–25 minutes of treatment in a rat embolism model without triggering hematological toxicity. In conclusion, this improved system is based on magnetic targeting accelerated thrombolysis and is

  20. Active magnetic bearings for optimum turbomachinery design

    Science.gov (United States)

    Hustak, J.; Kirk, R. G.; Schoeneck, K. A.

    1985-01-01

    The design and shop test results are given for a high speed eight stage centrifugal compressor supported by active magnetic bearings. A brief summary of the rotor dynamics analysis is presented with specific attention given to design considerations for optimum rotor stability. The concerns for retrofit of magnetic bearings in existing machinery are discussed with supporting analysis of a four stage centrifugal compressor. Recommendations are given on design and analysis requirements for successful machinery operation of either retrofit or new design turbomachinery.

  1. Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Jansen, Mark

    2004-01-01

    The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

  2. Active Magnetic Bearings. Postgraduate Seminar on Electromechanics

    Energy Technology Data Exchange (ETDEWEB)

    Lantto, E.; Tommila, V.; Arkkio, A.

    2007-07-01

    The papers in the seminar on electromagnetics are published only as power point slides. The titles of the different papers are: Introduction to magnetic bearings, Magnetic field and forces, Actuators, amplifiers and sensors, System theory, rotordynamics and control, Diagnostics, applications and standardisation.

  3. Coated Conductors for the Magnetic Bearing Application

    Science.gov (United States)

    Sass, Felipe; Dias, Daniel Henrique Nogueira; Sotelo, Guilherme Gonçalves; Júnior, Rubens de Andrade

    The second generation (2G) of superconductor wires have been considered for several applications lately. This work presents a preliminary study of superconducting magnetic bearings (SMB) using 2G wires as passive levitators. A superconducting block using stacked 2G wires was built to evaluate the magnetic bearing behavior, thought levitation force measurements, when a permanent magnet cylinder approaches or moves away from the block. The superconducting block was compared with an YBCO bulk with nearly the same dimensions and the results show a promising potential for this application.

  4. Fault Tolerant Magnetic Bearing Testing and Conical Magnetic Bearing Development for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Clark, Daniel

    2004-01-01

    During the six month tenure of the grant, activities included continued research of hydrostatic bearings as a viable backup-bearing solution for a magnetically levitated shaft system in extreme temperature environments (1000 F), developmental upgrades of the fault-tolerant magnetic bearing rig at the NASA Glenn Research Center, and assisting in the development of a conical magnetic bearing for extreme temperature environments, particularly turbomachinery. It leveraged work from the ongoing Smart Efficient Components (SEC) and the Turbine-Based Combined Cycle (TBCC) program at NASA Glenn Research Center. The effort was useful in providing technology for more efficient and powerful gas turbine engines.

  5. Novel Integration Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  6. Magnetic remanence of hematite-bearing murals

    Science.gov (United States)

    Lanza, R.; Zanella, E.; Saudino, S.

    2009-12-01

    We report on a series of experiments designed to test the ability of hematite-bearing colors to record the direction of the ambient magnetic field. Plasterboards accurately oriented with respect to the Earth's magnetic field were painted with red tempera colors prepared with hematite pigments. Magnetic measurements indicate that the color film retains a remanent magnetization and acquires a well developed magnetic fabric. The remanence direction is close to, yet slightly deviated from the Earth's magnetic field. The deviation is interpreted to result from preferential alignment of the pigment grains parallel to the plasterboard surface and depends on both its orientation with respect to magnetic north and the degree of magnetic anisotropy of the color film, which in turn varies according to the pigment used. Investigation of the magnetic remanence of murals may complement archaeomagnetic information derived from traditional materials such as baked and fired structures.

  7. Novel Integrated Radial and Axial Magnetic Bearing

    Science.gov (United States)

    Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

  8. Flywheel energy storage with superconductor magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT); Hull, John R. (Hinsdale, IL)

    1993-01-01

    A flywheel having superconductor bearings has a lower drag to lift ratio that translates to an improvement of a factor of ten in the rotational decay rate. The lower drag results from the lower dissipation of melt-processed YBCO, improved uniformity of the permanent magnet portion of the bearings, operation in a different range of vacuum pressure from that taught by the art, and greater separation distance from the rotating members of conductive materials.

  9. Passive magnetic bearings for vehicular electromechanical batteries

    Energy Technology Data Exchange (ETDEWEB)

    Post, R

    1996-03-01

    This report describes the design of a passive magnetic bearing system to be used in electromechanical batteries (flywheel energy storage modules) suitable for vehicular use. One or two such EMB modules might, for example, be employed in a hybrid-electric automobile, providing efficient means for power peaking, i.e., for handling acceleration and regenerative braking power demands at high power levels. The bearing design described herein will be based on a ''dual-mode'' operating regime.

  10. High Performance Magnetic Bearings for Aero Applications

    Science.gov (United States)

    Allaire, P. E.; Knospe, C. R.; Williams, R. D.; Lewis, D. W.; Barrett, L. E.; Maslen, E. H.; Humphris, R. R.

    1997-01-01

    Several previous annual reports were written and numerous papers published on the topics for this grant. That work is not repeated here in this final report. Only the work completed in the final year of the grant is presented in this final report. This final year effort concentrated on power loss measurements in magnetic bearing rotors. The effect of rotor power losses in magnetic bearings are very important for many applications. In some cases, these losses must be minimized to maximize the length of time the rotating machine can operate on a fixed energy or power supply. Examples include aircraft gas turbine engines, space devices, or energy storage flywheels. In other applications, the heating caused by the magnetic bearing must be removed. Excessive heating can be a significant problem in machines as diverse as large compressors, electric motors, textile spindles, and artificial heart pumps.

  11. AN INVESTIGATION OF MAGNETIC BEARING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Gürcan SAMTAŞ

    2007-02-01

    Full Text Available The magnetic bearing consists of levitating a shaft so that it is free to rotate about its axis. The magnetic bearing has the advantages of being very quiet work and very cleanliness because there is no mechanical friction or lubricants. The shaft has two permanent magnets attached to it. These two magnets determine a straight line rotation axis of the rotor shaft. The magnets are radially levitated and centered within a cavity by a passive permanent magnetic field in the adding stator housing assembly. The levitation and centering of the shaft axially is stabilized by a closed loop electronic servo circuit that regulates an electromagnetic field in the stator housing that pushes and pulls on the shaft magnets. The rotor weight can be between one gram and forty five thousand, four hundred grams. In 1985, the first magnetic bearing was developed that it had used to applications of gas turbines and other compressors. In these days, they can be used by many applications which are Medical, Transportation, Machine and Tools Industry, Aerospace, Vacuum and Clean room Environments... etc.

  12. Critical Pressures of the Thrust Bearing Using a Magnetic Fluid

    OpenAIRE

    長屋, 幸助; 武田, 定彦; 佐藤, 淳; 井開, 重男; 関口, 肇; 斉藤, 登

    1990-01-01

    This paper proposes a thrust bearing lubricated by a magnetic fluid under a magnetic field. The critical pressures of the bearing versus the magnitude of the magnetic flux densities have been investigated experimentally. It is clarified that the critical pressures of the proposed bearing are larger than those of the normal lubricant bearing under high speeds.

  13. Magnetic Fe3O4-graphene composites as targeted drug nanocarriers for pH-activated release

    Science.gov (United States)

    Fan, Xiujuan; Jiao, Guozheng; Zhao, Wei; Jin, Pengfei; Li, Xin

    2013-01-01

    A novel nanocarrier of magnetic Fe3O4-graphene nanocomposites (MGNs) was proposed as an effective drug delivery system for cancer treatment. The nanocarrier was synthesized by covalently attaching modified Fe3O4 nanoparticles onto water-soluble graphene sheets via the formation of an amide bond with the aid of 1-ethyl-3-(3-dimethyaminopropyl) carbodiimide. The obtained MGNs exhibited excellent dispersibility and stability in aqueous solution and they also exhibited superparamagnetic properties with a saturation magnetization of 23.096 emu g-1. An efficient loading of 5-fluorouracil (5-FU) on MGNs as high as 0.35 mg mg-1 was obtained. Furthermore, the in vitro drug release of 5-FU was examined in pH 6.9 and pH 4.0 buffers at 37 °C, and showed strong pH dependence. Transmission electron microscope observations revealed that MGNs can be internalized efficiently by HepG2 cells. More importantly, the cytotoxicity evaluation shows that the resulting MGNs exhibit excellent biocompatibility. The as-prepared nanocarrier system combined the advantages of the superparamagnetic iron oxide nanoparticles and water-soluble graphene sheets, which will find many potential applications in biomedicine and biomaterials.

  14. Dynamic interaction between rotor and axially-magnetized passive magnetic bearing considering magnetic eccentricity

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar

    2014-01-01

    Passive magnetic bearings are known due to the excellent characteristics in terms of friction and no requirement of additional energy sources to work. However, passive magnetic bearings do not provide damping, are not stable and, depending on their design, may also introduce magnetic eccentricity....... Such magnetic eccentricities are generated by discrepancies in magnet fabrication. In this framework the main focus of the work is the theoretical as well as experimental investigation of the nonlinear dynamics of a rotor-bearing system with strong emphasis on the magnetic eccentricities and non......-linear stiffness. In this investigation passive magnetic bearings using axially- aligned neodymium cylinder magnets are investigated. The cylinder magnets are axially magnetised for rotor as well as bearings. Compared to bearings with radial magnetisation, the magnetic stiffness of axially-aligned bearings...

  15. MAGNETIC FLUID BEARINGS OF MINING EQUIPMENT

    Directory of Open Access Journals (Sweden)

    I. Gorlov

    2012-01-01

    Full Text Available The paper considers a problem pertaining to selection friction pair materials for plain bearings of mining equipment which are lubricated with  nano-dispersed magnetic oil. Methodology for equipment tests, technology for obtaining new anti-friction materials (polymer, ceramic, amorphous and investigation results are presented in the paper.

  16. Preparation and characterization of magnetic gold nanoparticles to be used as doxorubicin nanocarriers.

    Science.gov (United States)

    Elbialy, Nihal Saad; Fathy, Mohammed Mahmoud; Khalil, Wafaa Mohamed

    2014-11-01

    Magnetic targeted drug delivery (MTD), using magnetic gold nanoparticles (Fe3O4@Au NPs) conjugated with an anti-cancer drug is a promise modality for cancer treatment. In this study, Fe3O4@Au NPs were prepared and functionalized with thiol-terminated polyethylene glycol (PEG), then loaded with anti-cancer drug doxorubicin (DOX). The physical properties of the prepared NPs were characterized using different techniques. Transmission electron microscopy (TEM) revealed the mono dispersed nature of Fe3O4@Au NPs with an average size of 20 nm which was confirmed using Dynamic light scattering (DLS) measurements. Zeta potential measurements along with UV-VIS spectroscopy demonstrated surface DOX loading on Fe3O4@Au NPs. Energy Dispersive X-ray Spectroscopy (EDX) assured the existence of both iron and gold elements in the prepared NPs. The paramagnetic properties of the prepared NPs were assessed by vibrating sample magnetometer (VSM). The maximum DOX-loading capacity was 100 μg DOX/mg of Fe3O4@Au NPs. It was found that DOX released more readily at acidic pH. In vitro studies on MCF-7 cell line elucidated that DOX loaded Fe3O4@Au NPs (Fe3O4@Au-PEG-DOX) have more potent therapeutic effect than free DOX. Knowledge gained in this study may open the door to pursue Fe3O4@Au NPs as a viable nanocarriers for different molecules delivery in many diagnostic and therapeutic applications.

  17. Combination radial and thrust magnetic bearing

    Science.gov (United States)

    Blumenstock, Kenneth A. (Inventor)

    2002-01-01

    A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

  18. High performance magnetic bearing systems using high temperature superconductors

    Science.gov (United States)

    Abboud, Robert G.

    1998-01-01

    A magnetic bearing apparatus and a method for providing at least one stabilizing force in a magnetic bearing structure with a superconducting magnetic assembly and a magnetic assembly, by providing a superconducting magnetic member in the superconducting magnetic assembly with a plurality of domains and arranging said superconducting magnetic member such that at least one domain has a domain C-axis vector alignment angularly disposed relative to a reference axis of the magnetic member in the magnetic assembly.

  19. Magnetic paclitaxel nanoparticles inhibit glioma growth and improve the survival of rats bearing glioma xenografts.

    Science.gov (United States)

    Zhao, Ming; Liang, Chao; Li, Anmin; Chang, Jin; Wang, Hanjie; Yan, Runmin; Zhang, Jiajing; Tai, Junli

    2010-06-01

    Paclitaxel has fared poorly in clinical trials against brain glioma. We hypothesized that superparamagnetic nanocarriers may enhance its bioactivities by delivering it into the brain. The magnetic paclitaxel nanoparticles (MPNPs) were fabricated and their cytotoxicity against glioma was tested both in vitro and in glioma-bearing rats. MPNPs exhibited superparamagnetism and produced an extended release of paclitaxel over 15 days in vitro. They were easily internalized into glioma cells and exerted remarkable toxicity, as free paclitaxel did. Furthermore, after intravenous injection of MPNPs to glioma-bearing rats and magnetic targeting with a 0.5 T magnet, drug content increased for 6- to 14-fold in implanted glioma and 4.6- to 12.1-fold in the normal brain compared to free paclitaxel. The survival of glioma-bearing rats was significantly prolonged after magnetic targeting therapy with MPNPs. MPNPs efficiently delivered paclitaxel into brain glioma by magnetic targeting and enhance its antitumor activity. They are promising for local chemotherapy for malignant glioma.

  20. A Comparison of Experimental and Theoretical Results for Magnetic Bearings

    Science.gov (United States)

    Hibbs, Robert I., Jr.; Scharrer, Joseph K.; Galvin, Bonnie A.; Galvin, Mark W.

    2000-01-01

    A comprehensive program was undertaken to experimentally characterize the static and dynamic characteristics of a heteropolar magnetic bearing and to develop nonlinear theoretical models capable of accurately predicting magnetic bearing performance. This paper presents the results for the static characteristics of the magnetic bearing and a comparison with the predictions from the analytical model. The results indicate that the nonlinear theoretical model can accurately predict the static characteristics of the magnetic bearing.

  1. EXPERIMENTAL APPARATUS FOR EXAMINATION OF MAGNETIC FLUID LUBRICATED THURST BEARING

    Directory of Open Access Journals (Sweden)

    Józef SALWIŃSKI

    2014-06-01

    Full Text Available In recent years, there has been development of the structure of thrust bearing with magnetic fluids . The essence of this type of bearing is to maintain a liquid lubricant in a very narrow gap with magnetic fluid by a magnetic field. Such systems can act as the bearing lubrication and sealing. This paper presents description of the experimental apparatus for examination magnetic fluid lubricated thrust bearing. Description of the construction and characteristics of the measuring possibilities ware presented.

  2. Passive magnetic bearing for a horizontal shaft

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F.

    2003-12-02

    A passive magnetic bearing is composed of a levitation element and a restorative element. The levitation element is composed of a pair of stationary arcuate ferromagnetic segments located within an annular radial-field magnet array. The magnet array is attached to the inner circumference of a hollow shaft end. An attractive force between the arcuate segments and the magnet array acts vertically to levitate the shaft, and also in a horizontal transverse direction to center the shaft. The restorative element is comprised of an annular Halbach array of magnets and a stationary annular circuit array located within the Halbach array. The Halbach array is attached to the inner circumference of the hollow shaft end. A repulsive force between the Halbach array and the circuit array increases inversely to the radial space between them, and thus acts to restore the shaft to its equilibrium axis of rotation when it is displaced therefrom.

  3. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  4. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  5. Ultralow Friction in a Superconducting Magnetic Bearing

    Science.gov (United States)

    Bornemann, Hans J.; Siegel, Michael; Zaitsev, Oleg; Bareiss, Martin; Laschuetza, Helmut

    1996-01-01

    Passive levitation by superconducting magnetic bearings can be utilized in flywheels for energy storage. Basic design criteria of such a bearing are high levitation force, sufficient vertical and horizontal stability and low friction. A test facility was built for the measurement and evaluation of friction in a superconducting magnetic bearing as a function of operating temperature and pressure in the vacuum vessel. The bearing consists of a commercial disk shaped magnet levitated above single grain, melt-textured YBCO high-temperature superconductor material. The superconductor was conduction cooled by an integrated AEG tactical cryocooler. The temperature could be varied from 50 K to 80 K. The pressure in the vacuum chamber was varied from 1 bar to 10(exp -5) mbar. At the lowest pressure setting, the drag torque shows a linear frequency dependence over the entire range investigated (0 less than f less than 40 Hz). Magnetic friction, the frequency independent contribution, is very low. The frequency dependent drag torque is generated by molecular friction from molecule-surface collisions and by eddy currents. Given the specific geometry of the set-up and gas pressure, the molecular drag torque can be estimated. At a speed of 40 Hz, the coefficient of friction (drag-to-lift ratio) was measured to be mu = 1.6 x 10(exp -7) at 10(exp -5) mbar and T = 60 K. This is equivalent to a drag torque of 7.6 x 10(exp -10) Nm. Magnetic friction causes approx. 1% of the total losses. Molecular friction accounts for about 13% of the frequency dependent drag torque, the remaining 87% being due to eddy currents and losses from rotor unbalance. The specific energy loss is only 0.3% per hour.

  6. Performance of repulsive type magnetic bearing system under nonuniform magnetization of permanent magnet

    OpenAIRE

    Ohji, T.; Mukhopadhyay, S. C.; Iwahara, Masayoshi; Yamada, Sotoshi

    2000-01-01

    Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, the...

  7. Fault Tolerant Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Choi, Benjamin; Provenza, Andrew

    2001-01-01

    NASA Glenn Research Center (GRC) has developed a Fault-Tolerant Magnetic Bearing Suspension rig to enhance the bearing system safety. It successfully demonstrated that using only two active poles out of eight redundant poles from each radial bearing (that is, simply 12 out of 16 poles dead) levitated the rotor and spun it without losing stability and desired position up to the maximum allowable speed of 20,000 rpm. In this paper, it is demonstrated that as far as the summation of force vectors of the attracting poles and rotor weight is zero, a fault-tolerant magnetic bearing system maintained the rotor at the desired position without losing stability even at the maximum rotor speed. A proportional-integral-derivative (PID) controller generated autonomous corrective actions with no operator's input for the fault situations without losing load capacity in terms of rotor position. This paper also deals with a centralized modal controller to better control the dynamic behavior over system modes.

  8. Direct Model Reference Adaptive Control for a Magnetic Bearing

    Energy Technology Data Exchange (ETDEWEB)

    Durling, Mike [Rensselaer Polytechnic Inst., Troy, NY (United States)

    1999-11-01

    A Direct Model Reference Adaptive Controller (DMRAC) is applied to a magnetic bearing test stand. The bearing of interest is the MBC 500 Magnetic Bearing System manufactured by Magnetic Moments, LLC. The bearing model is presented in state space form and the system transfer function is measured directly using a closed-loop swept sine technique. Next, the bearing models are used to design a phase-lead controller, notch filter and then a DMRAC. The controllers are tuned in simulations and finally are implemented using a combination of MATLAB, SIMULINK and dSPACE. The results show a successful implementation of a DMRAC on the magnetic bearing hardware.

  9. Adaptive Variable Bias Magnetic Bearing Control

    Science.gov (United States)

    Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

    1998-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called Adaptive Variable Bias Control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent, time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical, computer simulation, and experimental results are presented in this paper.

  10. Fail Safe, High Temperature Magnetic Bearings

    Science.gov (United States)

    Minihan, Thomas; Palazzolo, Alan; Kim, Yeonkyu; Lei, Shu-Liang; Kenny, Andrew; Na, Uhn Joo; Tucker, Randy; Preuss, Jason; Hunt, Andrew; Carter, Bart; hide

    2002-01-01

    This paper contributes to the magnetic bearing literature in two distinct areas: high temperature and redundant actuation. Design considerations and test results are given for the first published combined 538 C (1000 F) high speed rotating test performance of a magnetic bearing. Secondly, a significant extension of the flux isolation based, redundant actuator control algorithm is proposed to eliminate the prior deficiency of changing position stiffness after failure. The benefit of the novel extension was not experimentally demonstrated due to a high active stiffness requirement. In addition, test results are given for actuator failure tests at 399 C (750 F), 12,500 rpm. Finally, simulation results are presented confirming the experimental data and validating the redundant control algorithm.

  11. Wide gap, permanent magnet biased magnetic bearing system

    Science.gov (United States)

    Boden, Karl

    1992-01-01

    The unique features and applications of the presented electrical permanent magnetic bearing system essentially result from three facts: (1) the only bearing rotor components are nonlaminated ferromagnetic steel collars or cylinders; (2) all radial and axial forces are transmitted via radial gaps; and (3) large radial bearing gaps can be provided with minimum electric power consumption. The large gaps allow for effective encapsulation and shielding of the rotors at elevated or low temperatures, corrosive or ultra clean atmosphere or vacuum or high pressure environment. Two significant applications are described: (1) a magnetically suspended x ray rotary anode was operated under high vacuum conditions at 100 KV anode potential, 600 C temperature at the rotor collars and speed 18000 rpm with 13 mm radial bearing gap; and (2) an improved Czochralski type crystal growth apparatus using the hot wall method for pulling GaAs single crystals of low dislocation density. Both crystal and crucible are carried and transported by magnetically suspended shafts inside a hermetically sealed housing at 800 C shaft and wall temperature. The radial magnetic bearing gap measures 24 mm.

  12. Performance of ceramic superconductors in magnetic bearings

    Science.gov (United States)

    Kirtley, James L., Jr.; Downer, James R.

    1993-01-01

    Magnetic bearings are large-scale applications of magnet technology, quite similar in certain ways to synchronous machinery. They require substantial flux density over relatively large volumes of space. Large flux density is required to have satisfactory force density. Satisfactory dynamic response requires that magnetic circuit permeances not be too large, implying large air gaps. Superconductors, which offer large magnetomotive forces and high flux density in low permeance circuits, appear to be desirable in these situations. Flux densities substantially in excess of those possible with iron can be produced, and no ferromagnetic material is required. Thus the inductance of active coils can be made low, indicating good dynamic response of the bearing system. The principal difficulty in using superconductors is, of course, the deep cryogenic temperatures at which they must operate. Because of the difficulties in working with liquid helium, the possibility of superconductors which can be operated in liquid nitrogen is thought to extend the number and range of applications of superconductivity. Critical temperatures of about 98 degrees Kelvin were demonstrated in a class of materials which are, in fact, ceramics. Quite a bit of public attention was attracted to these new materials. There is a difficulty with the ceramic superconducting materials which were developed to date. Current densities sufficient for use in large-scale applications have not been demonstrated. In order to be useful, superconductors must be capable of carrying substantial currents in the presence of large magnetic fields. The possible use of ceramic superconductors in magnetic bearings is investigated and discussed and requirements that must be achieved by superconductors operating at liquid nitrogen temperatures to make their use comparable with niobium-titanium superconductors operating at liquid helium temperatures are identified.

  13. Permanent magnet design for high-speed superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (5519 S. Bruner, Hinsdale, IL 60521); Uherka, Kenneth L. (830 Ironwood, Frankfort, IL 60423); Abdoud, Robert G. (13 Country Oaks La., Barrington Hills, IL 60010)

    1996-01-01

    A high temperature superconducting bearing including a permanent magnet rotor levitated by a high temperature superconducting structure. The rotor preferably includes one or more concentric permanent magnet rings coupled to permanent magnet ring structures having substantially triangular and quadrangular cross-sections. Both alternating and single direction polarity magnet structures can be used in the bearing.

  14. Magnetic Bearing Controller Improvements for High Speed Flywheel System

    Science.gov (United States)

    Dever, Timothy P.; Brown, Gerald V.; Jansen, Ralph H.; Kascak, Peter E.; Provenza, Andrew J.

    2003-01-01

    A magnetic bearing control system for a high-speed flywheel system is described. The flywheel utilizes a five axis active magnetic bearing system, using eddy current sensors for position feedback to the bearing controller. Magnetic bearing controller features designed to improve flywheel operation and testing are described. Operational improvements include feed forward control to compensate for rotor imbalance, moving notch filtering to compensate for synchronous and harmonic rotational noise, and fixed notching to prevent rotor bending mode excitation. Testing improvements include adding safe gain, bearing current hold, bearing current zero, and excitation input features. Performance and testing improvements provided by these features are measured and discussed.

  15. An Overview of Magnetic Bearing Technology for Gas Turbine Engines

    Science.gov (United States)

    Clark, Daniel J.; Jansen, Mark J.; Montague, Gerald T.

    2004-01-01

    The idea of the magnetic bearing and its use in exotic applications has been conceptualized for many years, over a century, in fact. Patented, passive systems using permanent magnets date back over 150 years. More recently, scientists of the 1930s began investigating active systems using electromagnets for high-speed ultracentrifuges. However, passive magnetic bearings are physically unstable and active systems only provide proper stiffness and damping through sophisticated controllers and algorithms. This is precisely why, until the last decade, magnetic bearings did not become a practical alternative to rolling element bearings. Today, magnetic bearing technology has become viable because of advances in micro-processing controllers that allow for confident and robust active control. Further advances in the following areas: rotor and stator materials and designs which maximize flux, minimize energy losses, and minimize stress limitations; wire materials and coatings for high temperature operation; high-speed micro processing for advanced controller designs and extremely robust capabilities; back-up bearing technology for providing a viable touchdown surface; and precision sensor technology; have put magnetic bearings on the forefront of advanced, lubrication free support systems. This paper will discuss a specific joint program for the advancement of gas turbine engines and how it implies the vitality of magnetic bearings, a brief comparison between magnetic bearings and other bearing technologies in both their advantages and limitations, and an examination of foreseeable solutions to historically perceived limitations to magnetic bearing.

  16. Control concepts for active magnetic bearings

    Science.gov (United States)

    Siegwart, Roland; Vischer, D.; Larsonneur, R.; Herzog, R.; Traxler, Alfons; Bleuler, H.; Schweitzer, G.

    1992-01-01

    Active Magnetic Bearings (AMB) are becoming increasingly significant for various industrial applications. Examples are turbo-compressors, centrifuges, high speed milling and grinding spindles, vibration isolation, linear guides, magnetically levitated trains, vacuum and space applications. Thanks to the rapid progress and drastic cost reduction in power- and micro-electronics, the number of AMB applications is growing very rapidly. Industrial uses of AMBs leads to new requirements for AMB-actuators, sensor systems, and rotor dynamics. Especially desirable are new and better control concepts to meet demand such as low cost AMB, high stiffness, high performance, high robustness, high damping up to several kHz, vibration isolation, force-free rotation, and unbalance cancellation. This paper surveys various control concepts for AMBs and discusses their advantages and disadvantages. Theoretical and experimental results are presented.

  17. Dynamics of Permanent-Magnet Biased Active Magnetic Bearings

    Science.gov (United States)

    Fukata, Satoru; Yutani, Kazuyuki

    1996-01-01

    Active magnetic radial bearings are constructed with a combination of permanent magnets to provide bias forces and electromagnets to generate control forces for the reduction of cost and the operating energy consumption. Ring-shaped permanent magnets with axial magnetization are attached to a shaft and share their magnet stators with the electromagnets. The magnet cores are made of solid iron for simplicity. A simplified magnetic circuit of the combined magnet system is analyzed with linear circuit theory by approximating the characteristics of permanent magnets with a linear relation. A linearized dynamical model of the control force is presented with the first-order approximation of the effects of eddy currents. Frequency responses of the rotor motion to disturbance inputs and the motion for impulsive forces are tested in the non-rotating state. The frequency responses are compared with numerical results. The decay of rotor speed due to magnetic braking is examined. The experimental results and the presented linearized model are similar to those of the all-electromagnetic design.

  18. A New 1000 F Magnetic Bearing Test Rig

    Science.gov (United States)

    Kascak, Albert F.; Montague, Gerald T.; Brown, Gerald V.; Palazzolo, Alan B.

    1997-01-01

    NASA and the Army are currently exploring the possibility of using magnetic bearings in gas turbine engines. The use of magnetic bearings in gas turbine engines could increase the reliability by eliminating the lubrication system. The use of magnetic bearings could also increase the speed and the size of the shafts in the engine, thus reducing vibrations and possibly eliminating third bearings. Magnetic bearings can apply forces to the shafts and move them so that blade tips and seals do not rub. This could be part of an active vibration cancellation system. Also, whirling (displacing the shaft center line) may delay rotating stall and increase the stall margin of the engine. Magnetic bearings coupled with an integral starter generator could result in a more efficient 'more electric' engine. The IHPTET program, a joint DOD-industry program, has identified a need for a high temperature, (as high as 1200 F), magnetic bearing that could be demonstrated in a phase m engine. A magnetic bearing is similar to an electric motor. The magnetic bearing has a laminated rotor and stator made out of cobalt steel. The stator has a series of coils of wire wound around it. These coils f u. a series of electromagnets around the circumference. These magnets exert a force on the rotor to keep the rotor in the center of the cavity. The centering force is commanded by a controller based on shaft position, (measured by displacement probes). The magnetic bearing can only pull and is basically unstable before active control is applied The engine shafts, bearings, and case form a flexible structure which contain a large number of modes. A controller is necessary to stabilize these modes. A power amplifier is also necessary to provide the current prescribed by the controller to the magnetic bearings. In case of very high loads, a conventional back up bearing will engage and stop the rotor and stator from rubbing.

  19. Passive magnetic bearing systems stabilizer/bearing utilizing time-averaging of a periodic magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2017-10-03

    A high-stiffness stabilizer/bearings for passive magnetic bearing systems is provide where the key to its operation resides in the fact that when the frequency of variation of the repelling forces of the periodic magnet array is large compared to the reciprocal of the growth time of the unstable motion, the rotating system will feel only the time-averaged value of the force. When the time-averaged value of the force is radially repelling by the choice of the geometry of the periodic magnet array, the Earnshaw-related unstable hit motion that would occur at zero rotational speed is suppressed when the system is rotating at operating speeds.

  20. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings....... In the present paper both the technologies are combined with the aim of developing a new kind of hybrid permanent magnetic - gas bearing. This new kind of machine is intended to exploit the benefits of the two technologies while minimizing their drawbacks. The poor start-up and low speed operation performance...... of the gas bearing is balanced by the properties of the passive magnetic one. At high speeds the dynamic characteristics of the gas bearing are improved by offsetting the stator ring of the permanent magnetic bearing. Furthermore this design shows a kind of redundancy, which offers soft failure properties...

  1. Precision Magnetic Bearing Six Degree of Freedom Stage

    Science.gov (United States)

    Williams, M. E.; Trumper, David L.

    1996-01-01

    Magnetic bearings are capable of applying force and torque to a suspended object without rigidly constraining any degrees of freedom. Additionally, the resolution of magnetic bearings is limited only by sensors and control, and not by the finish of a bearing surface. For these reasons, magnetic bearings appear to be ideal for precision wafer positioning in lithography systems. To demonstrate this capability a linear magnetic bearing has been constructed which uses variable reluctance actuators to control the motion of a 14.5 kg suspended platen in five degrees of freedom. A Lorentz type linear motor of our own design and construction is used to provide motion and position control in the sixth degree of freedom. The stage performance results verify that the positioning requirements of photolithography can be met with a system of this type. This paper describes the design, control, and performance of the linear magnetic bearing.

  2. A new magnetic bearing using Halbach magnet arrays for a magnetic levitation stage.

    Science.gov (United States)

    Choi, Young-Man; Lee, Moon G; Gweon, Dae-Gab; Jeong, Jaehwa

    2009-04-01

    Next-generation lithography requires a high precision stage, which is compatible with a high vacuum condition. A magnetic levitation stage with six degrees-of-freedom is considered state-of-the-art technology for a high vacuum condition. The noncontact characteristic of magnetic levitation enables high precision positioning as well as no particle generation. To position the stage against gravity, z-directional electromagnetic levitation mechanisms are widely used. However, if electromagnetic actuators for levitation are used, heat is inevitably generated, which deforms the structures and degrades accuracy of the stage. Thus, a gravity compensator is required. In this paper, we propose a new magnetic bearing using Halbach magnet arrays for a magnetic levitation stage. The novel Halbach magnetic bearing exerts a force four times larger than a conventional magnetic bearing with the same volume. We also discuss the complementary characteristics of the two magnetic bearings. By modifying the height of the center magnet in a Halbach magnetic bearing, a performance compromise between levitating force density and force uniformity is obtained. The Halbach linear active magnetic bearing can be a good solution for magnetic levitation stages because of its large and uniform levitation force.

  3. A Wide Bandwidth Model for the Electrical Impedance of Magnetic BearingS

    Science.gov (United States)

    Meeker, David C.; Maslen, Eric H.; Noh, Myounggyu D.

    1996-01-01

    Magnetic bearings are often designed using magnetic circuit theory. When these bearings are built, however, effects not included in the usual circuit theory formulation have a significant influence on bearing performance. Two significant sources of error in the circuit theory approach are the neglect of leakage and fringing effects and the neglect of eddy current effects. This work formulates an augmented circuit model in which eddy current and flux leakage and fringing effects are included. Through the use of this model, eddy current power losses and actuator bandwidth can be derived. Electrical impedance predictions from the model are found to be in good agreement with experimental data from a typical magnetic bearing.

  4. Analysis of Permanent Magnets Bearings in Flywheel Rotor Designs

    Directory of Open Access Journals (Sweden)

    Prince Owusu-Ansah

    2016-04-01

    Full Text Available This paper discusses analysis of permanent magnet bearing in flywheel rotor designs. This work focuses on the advantages of using permanent magnets in flywheel rotor design as compared to that of the convectional mode of levitating the rotor position. The use of permanent magnet in magnetic bearing design to generate the steady state position of the magnetic field results in less variation of the force exerted on the rotor when it deviates from the nominal position than when an electrical coil is used for the same purpose. Theresults of the analysis shows that the magnetic bearing dynamics as well as its load carryingcapacity improves when the rotor is offset from its central position. The use of permanent magnet compared to current-carrying coils results in smaller overall size of magnetic bearing leading to a more compact system design resulting in improved rotordynamic performance

  5. Nonlinear Control of Large Disturbances in Magnetic Bearing Systems

    Science.gov (United States)

    Jiang, Yuhong; Zmood, R. B.

    1996-01-01

    In this paper, the nonlinear operation of magnetic bearing control methods is reviewed. For large disturbances, the effects of displacement constraints and power amplifier current and di/dt limits on bearing control system performance are analyzed. The operation of magnetic bearings exhibiting self-excited large scale oscillations have been studied both experimentally and by simulation. The simulation of the bearing system has been extended to include the effects of eddy currents in the actuators, so as to improve the accuracy of the simulation results. The results of these experiments and simulations are compared, and some useful conclusions are drawn for improving bearing system robustness.

  6. Cryocooler applications for high-temperature superconductor magnetic bearings.

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, R. C.

    1998-05-22

    The efficiency and stability of rotational magnetic suspension systems are enhanced by the use of high-temperature superconductor (HTS) magnetic bearings. Fundamental aspects of the HTS magnetic bearings and rotational magnetic suspension are presented. HTS cooling can be by liquid cryogen bath immersion or by direct conduction, and thus there are various applications and integration issues for cryocoolers. Among the numerous cryocooler aspects to be considered are installation; operating temperature; losses; and vacuum pumping.

  7. DC Control Effort Minimized for Magnetic-Bearing-Supported Shaft

    Science.gov (United States)

    Brown, Gerald V.

    2001-01-01

    A magnetic-bearing-supported shaft may have a number of concentricity and alignment problems. One of these involves the relationship of the position sensors, the centerline of the backup bearings, and the magnetic center of the magnetic bearings. For magnetic bearings with permanent magnet biasing, the average control current for a given control axis that is not bearing the shaft weight will be minimized if the shaft is centered, on average over a revolution, at the magnetic center of the bearings. That position may not yield zero sensor output or center the shaft in the backup bearing clearance. The desired shaft position that gives zero average current can be achieved if a simple additional term is added to the control law. Suppose that the instantaneous control currents from each bearing are available from measurements and can be input into the control computer. If each control current is integrated with a very small rate of accumulation and the result is added to the control output, the shaft will gradually move to a position where the control current averages to zero over many revolutions. This will occur regardless of any offsets of the position sensor inputs. At that position, the average control effort is minimized in comparison to other possible locations of the shaft. Nonlinearities of the magnetic bearing are minimized at that location as well.

  8. DC Control Effort Minimized for Magnetic-Bearing-Supported Shaft

    Science.gov (United States)

    Brown, Gerald V.

    2001-01-01

    A magnetic-bearing-supported shaft may have a number of concentricity and alignment problems. One of these involves the relationship of the position sensors, the centerline of the backup bearings, and the magnetic center of the magnetic bearings. For magnetic bearings with permanent magnet biasing, the average control current for a given control axis that is not bearing the shaft weight will be minimized if the shaft is centered, on average over a revolution, at the magnetic center of the bearings. That position may not yield zero sensor output or center the shaft in the backup bearing clearance. The desired shaft position that gives zero average current can be achieved if a simple additional term is added to the control law. Suppose that the instantaneous control currents from each bearing are available from measurements and can be input into the control computer. If each control current is integrated with a very small rate of accumulation and the result is added to the control output, the shaft will gradually move to a position where the control current averages to zero over many revolutions. This will occur regardless of any offsets of the position sensor inputs. At that position, the average control effort is minimized in comparison to other possible locations of the shaft. Nonlinearities of the magnetic bearing are minimized at that location as well.

  9. Velocity-Controlled Magnetic Bearings with Solid Cores

    Science.gov (United States)

    Chen, H. Ming; Walton, James

    1996-01-01

    A methodology for designing velocity-controlled magnetic bearings with laminated cores has been extended to those with solid cores. The eddy-current effect of the solid cores is modeled as an opposing magnetomotive force. The bearing control dynamics is formulated in a dimensionless fashion which can be readily reviewed on a root-locus plot for stability. This facilitates the controller design and tuning process for solid core magnetic bearings using no displacement sensors.

  10. Suppression of Base Excitation of Rotors on Magnetic Bearings

    OpenAIRE

    2007-01-01

    This paper deals with rotor systems that suffer harmonic base excitation when supported on magnetic bearings. Magnetic bearings using conventional control techniques perform poorly in such situations mainly due to their highly nonlinear characteristics. The compensation method presented here is a novel optimal control procedure with a combination of conventional, proportional, and differential feedback control. A four-degree-of-freedom model is used for the rotor system, and the bearings a...

  11. Transpermeance Amplifier Applied to Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Jossana Ferreira

    2017-02-01

    Full Text Available The most conventional approach of controlling magnetic forces in active magnetic bearings (AMBs is through current feedback amplifiers: transconductance. This enables the operation of the AMB to be understood in terms of a relatively simple current-based model as has been widely reported on in the literature. The alternative notion of using transpermeance amplifiers, which approximate the feedback of gap flux rather than current, has been in commercial use in some form for at least thirty years, however is only recently seeing more widespread acceptance as a commercial standard. This study explores how such alternative amplifiers should be modeled and then examines the differences in behavior between AMBs equipped with transconductance and transpermeance amplifiers. The focus of this study is on two aspects. The first is the influence of rotor displacement on AMB force, commonly modeled as a constant negative equivalent mechanical stiffness, and it is shown that either scheme actually leads to a finite bandwidth effect, but that this bandwidth is much lower when transpermeance is employed. The second aspect is the influence of eddy currents. Using a very simple model of eddy currents (a secondary short-circuited coil, it is demonstrated that transpermeance amplifiers can recover significant actuator bandwidth compared with transconductance, but at the cost of needing increased peak current headroom.

  12. Mini hemoreliable axial flow LVAD with magnetic bearings: part 3: modeling of demo-magnetic bearing and verification.

    Science.gov (United States)

    Goldowsky, Michael

    2002-01-01

    This paper discusses my previous work on aerospace magnetic bearings during the 1970s and 1980s. Modeling of the magnetic field in the bearing is discussed and stiffness test data are provided, which verifies the model. An LVAD this small was made possible by the use of axial field fringing ring magnetic bearings that are much stronger than the radial field bearings currently used in turbo pumps. The analytical design of a first prototype bearing is discussed in detail that is mainly of interest to bearing designers. Modeling was accurately done without finite element analysis (FEA), which readily provided design insights not easily obtained through FEA. This bearing was not meant to satisfy all specifications of a blood pump. The next prototype, to be reported at the 2001 ASAIO conference, will meet these specifications.

  13. Development and Testing of a Radial Halbach Magnetic Bearing

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2006-01-01

    The NASA John H. Glenn Research Center has developed and tested a revolutionary Radial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Radial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Radial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical applications, manufacturing equipment, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Radial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.

  14. Development and Testing of an Axial Halbach Magnetic Bearing

    Science.gov (United States)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2006-01-01

    The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic thrust bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Axial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Axial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.

  15. Doxorubicin loaded dual pH- and thermo-responsive magnetic nanocarrier for combined magnetic hyperthermia and targeted controlled drug delivery applications

    Science.gov (United States)

    Hervault, Aziliz; Dunn, Alexander E.; Lim, May; Boyer, Cyrille; Mott, Derrick; Maenosono, Shinya; Thanh, Nguyen T. K.

    2016-06-01

    Magnetic nanocarriers have attracted increasing attention for multimodal cancer therapy due to the possibility to deliver heat and drugs locally. The present study reports the development of magnetic nanocomposites (MNCs) made of an iron oxide core and a pH- and thermo-responsive polymer shell, that can be used as both hyperthermic agent and drug carrier. The conjugation of anticancer drug doxorubicin (DOX) to the pH- and thermo-responsive MNCs via acid-cleavable imine linker provides advanced features for the targeted delivery of DOX molecules via the combination of magnetic targeting, and dual pH- and thermo-responsive behaviour which offers spatial and temporal control over the release of DOX. The iron oxide cores exhibit a superparamagnetic behaviour with a saturation magnetization around 70 emu g-1. The MNCs contained 8.1 wt% of polymer and exhibit good heating properties in an alternating magnetic field. The drug release experiments confirmed that only a small amount of DOX was released at room temperature and physiological pH, while the highest drug release of 85.2% was obtained after 48 h at acidic tumour pH under hyperthermia conditions (50 °C). The drug release kinetic followed Korsmeyer-Peppas model and displayed Fickian diffusion mechanism. From the results obtained it can be concluded that this smart magnetic nanocarrier is promising for applications in multi-modal cancer therapy, to target and efficiently deliver heat and drug specifically to the tumour.Magnetic nanocarriers have attracted increasing attention for multimodal cancer therapy due to the possibility to deliver heat and drugs locally. The present study reports the development of magnetic nanocomposites (MNCs) made of an iron oxide core and a pH- and thermo-responsive polymer shell, that can be used as both hyperthermic agent and drug carrier. The conjugation of anticancer drug doxorubicin (DOX) to the pH- and thermo-responsive MNCs via acid-cleavable imine linker provides advanced

  16. THE EDDY LOSSES OF A MAGNETIC THRUST BEARING

    Institute of Scientific and Technical Information of China (English)

    徐华; 王艳

    2004-01-01

    Accurate calculations of losses associated with the operation of magnetic bearings are particularly important for high speed applications where the rotor losses are expected to be large and for some particular applications where even low power losses will be critical. Power losses in the magnetic thrust bearing is often neglected, but if there is misaligned in the rotor and bearing, the magnetic field in the thrust bearing is no longer axisymmetric one, or the dynamic control current in the winding is time dependent one, eddy currents are caused to flow inside the conducting material, then the power losses are very important for magnetic bearing design. This paper presents an analytical model of a thrust magnetic bearing, and the magnetic fields, forces and losses of thrust magnetic bearing are calculated. In the calculations the frequency of dynamic control current is up to 1000Hz, rotating speed is from 60rpm to 1200rpm, and the non-linearity of material is also taken into consideration. The results shows that if the magnetic field is not saturation, the eddy losses is proportional to dynamic control current frequency and a square function of dynamic control current, and also 5/2 power function of shaft's speed.

  17. Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Mehmed, Oral; Johnson, Dexter; Montague, Gerald; Duffy, Kirsten; Jansen, Ralph

    2005-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig is an apparatus for vibration testing of turbomachine blades in a vacuum at rotational speeds from 0 to 40,000 rpm. This rig includes (1) a vertically oriented shaft on which is mounted an assembly comprising a rotor holding the blades to be tested, (2) two actively controlled heteropolar radial magnetic bearings at opposite ends of the shaft, and (3) an actively controlled magnetic thrust bearing at the upper end of the shaft. This rig is a more capable successor to a prior apparatus, denoted the Dynamic Spin Rig (DSR), that included a vertically oriented shaft with a mechanical thrust bearing at the upper end and a single actively controlled heteropolar radial magnetic bearing at the lower end.

  18. Modeling of Hybrid Permanent Magnetic-Gas Bearings

    DEFF Research Database (Denmark)

    Morosi, Stefano; Santos, Ilmar

    2009-01-01

    Modern turbomachinery applications require nowadays ever-growing rotational speeds and high degree of reliability. It then becomes natural to focus the attention of the research to contact-free bearings elements. The present alternatives focus on gas lubricated journal bearings or magnetic bearings...... concentric rings with radial magnetic orientation - analytical expressions for the calculation of the magnetic flux density and forces are employed, opposed to the main literature trend where finite element software is utilized at least for the calculation of the B-field. Numerical analysis shows how...... the rotor equilibrium position can be made independent on the rotational speed and applied load; it becomes function of the passive magnetic bearing offset. By adjusting the offset it is possible to significantly influence the dynamic coefficients of the hybrid bearing....

  19. Hybrid Superconducting Magnetic Bearing (HSMB) for high load devices

    Science.gov (United States)

    McMichael, C. K.; Ma, K. B.; Lamb, M. A.; Lin, M. W.; Chow, L.; Meng, R. L.; Hor, P. H.; Chu, W. K.

    1992-05-01

    Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

  20. Active magnetic bearing system based on sliding mode control

    Science.gov (United States)

    Zhang, Yanhong

    2017-07-01

    A new sliding mode variable structure control algorithm suitable for active magnetic bearing is proposed, which is widely used for nonlinear control system. The model and controller is designed, simulation and experimental parts are also made, according to the switching function and the sliding mode control law. The current of electromagnet is adjusted to realize stable levitation of the rotor. The experimental result shows that the sliding mode variable structure controller is an effective way for magnetic bearing control, and the active magnetic bearing system is a highly nonlinear and advanced control method that can reduce the setting time and the cost.

  1. Magnetic resonance-guided regional gene delivery strategy using a tumor stroma-permeable nanocarrier for pancreatic cancer

    Directory of Open Access Journals (Sweden)

    Wang Q

    2015-07-01

    Full Text Available Qingbing Wang,1,2 Jianfeng Li,3 Sai An,3 Yi Chen,1 Chen Jiang,3 Xiaolin Wang1,2 1Department of Interventional Radiology, Zhongshan Hospital, Fudan University, 2Shanghai Institute of Medical Imaging, 3Key Laboratory of Smart Drug Delivery, Ministry of Education, Department of Pharmaceutics, School of Pharmacy, Fudan University, Shanghai, People’s Republic of China Background: Gene therapy is a very promising technology for treatment of pancreatic ductal adenocarcinoma (PDAC. However, its application has been limited by the abundant stromal response in the tumor microenvironment. The aim of this study was to prepare a dendrimer-based gene-free loading vector with high permeability in the tumor stroma and explore an imaging-guided local gene delivery strategy for PDAC to promote the efficiency of targeted gene delivery.Methods: The experimental protocol was approved by the animal ethics committee of Zhongshan Hospital, Fudan University. Third-generation dendrigraft poly-L-lysines was selected as the nanocarrier scaffold, which was modified by cell-penetrating peptides and gadolinium (Gd chelates. DNA plasmids were loaded with these nanocarriers via electrostatic interaction. The cellular uptake and loaded gene expression were examined in MIA PaCa-2 cell lines in vitro. Permeability of the nanoparticles in the tumor stroma and transfected gene distribution in vivo were studied using a magnetic resonance imaging-guided delivery strategy in an orthotopic nude mouse model of PDAC.Results: The nanocarriers were synthesized with a dendrigraft poly-L-lysine to polyethylene glycol to DTPA ratio of 1:3.4:8.3 and a mean diameter of 110.9±7.7 nm. The luciferases were strictly expressed in the tumor, and the luminescence intensity in mice treated by Gd-DPT/plasmid luciferase (1.04×104±9.75×102 p/s/cm2/sr was significantly (P<0.05 higher than in those treated with Gd-DTPA (9.56×102±6.15×10 p/s/cm2/sr and Gd-DP (5.75×103± 7.45×102 p/s/cm2/sr

  2. Novel maglev pump with a combined magnetic bearing.

    Science.gov (United States)

    Onuma, Hiroyuki; Murakami, Michiko; Masuzawa, Toru

    2005-01-01

    The newly developed pump is a magnetically levitated centrifugal blood pump in which active and passive magnetic bearings are integrated to construct a durable ventricular assist device. The developed maglev centrifugal pump consists of an active magnetic bearing, a passive magnetic bearing, a levitated impeller, and a motor stator. The impeller is set between the active magnetic bearing and the motor stator. The active magnetic bearing uses four electromagnets to control the tilt and the axial position of the impeller. The radial movement of the levitated impeller is restricted with the passive stability dependent upon the top stator and the passive permanent magnetic bearing to reduce the energy consumption and the control system complexity. The top stator was designed based upon a magnetic field analysis to develop the maglev pump with sufficient passive stability in the radial direction. By implementing this analysis design, the oscillating amplitude of the impeller in the radial direction was cut in half when compared with the simple shape stator. This study concluded that the newly developed maglev centrifugal pump displayed excellent levitation performance and sufficient pump performance as a ventricular assist device.

  3. Modeling and Development of RMD Configuration Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    K.P. Lijesh

    2015-06-01

    Full Text Available The low load carrying capacity of Passive Magnetic Bearings (PMBs has restricted their use in many industrial applications. The Rotation Magnetized Direction (RMD configuration has emerged as a strong and viable method that is able to substantially enhance the load carrying capacity of passive magnetic bearings. It consists of both radially and axially polarized passive magnets. But the physical realization of a radially polarized magnet is difficult to achieve. In the present work, a RMD structure consisting of aluminum ring and cubical shaped magnets is proposed by developing the radially polarized magnets required for RMD structure. A theoretical model is derived by simulating the cuboid magnets in form of sector magnets by developing equivalent surface area. An experimental setup was designed and developed to conduct experimental verification. The theoretical model is validated by conducting experiments on RMD configuration magnetic bearing and axially magnetized full ring bearing. The comparison of the load carrying capacity by different configuration is performed and results are presented.

  4. Study of magnetic bearings with high temperature superconductors, phase 3

    Science.gov (United States)

    Eyssa, Y. M.; Huang, X.

    1991-01-01

    Three areas related to the actively controlled radial magnetic bearing concepts are discussed. These areas are: (1) modification to the ac loss calculations of the 1990 report; (2) a continuous changing mechanism to compensate rotor current drop due to ac losses; and (3) design of a proof of principle experiment simulating the proposed bearing concept.

  5. Roles of superconducting magnetic bearings and active magnetic bearings in attitude control and energy storage flywheel

    Science.gov (United States)

    Tang, Jiqiang; Fang, Jiancheng; Ge, Shuzhi Sam

    2012-12-01

    Compared with conventional energy storage flywheel, the rotor of attitude control and energy storage flywheel (ACESF) used in space not only has high speed, but also is required to have precise and stable direction. For the presented superconducting magnetic bearing (SMB) and active magnetic bearing (AMB) suspended ACESF, the rotor model including gyroscopic couples is established originally by taking the properties of SMB and AMB into account, the forces of SMB and AMB are simplified by linearization within their own neighbors of equilibrium points. For the high-speed rigid discal rotor with large inertia, the negative effect of gyroscopic effect of rotor is prominent, the radial translation and tilting movement of rotor suspended by only SMB, SMB with equivalent PMB, or SMB together with PD controlled AMB are researched individually. These analysis results proved originally that SMB together with AMB can make the rotor be stable and make the radial amplitude of the vibration of rotor be small while the translation of rotor suspended by only SMB or SMB and PM is not stable and the amplitude of this vibration is large. For the stability of the high-speed rotor in superconducting ACESF, the AMB can suppress the nutation and precession of rotor effectively by cross-feedback control based on the separated PD type control or by other modern control methods.

  6. Estimator Based Controller for High Speed Flywheel Magnetic Bearing System

    Science.gov (United States)

    Dever, Timothy P.; Brown, Gerald V.; Jansen, Ralph H.

    2002-01-01

    A flywheel system and its operator interface are described. Measurements of magnetic bearing negative stiffness are performed. Two digital magnetic bearing control algorithms (PD and estimator based) are defined and their implementations are described. Tuning of each controller is discussed. Comparison of the two controllers' stability, damping noise, and operating current are described. Results describing the superiority of the estimator-based controller are presented and discussed.

  7. Active magnetic bearings used as exciters for rolling element bearing outer race defect diagnosis.

    Science.gov (United States)

    Xu, Yuanping; Di, Long; Zhou, Jin; Jin, Chaowu; Guo, Qintao

    2016-03-01

    The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge-Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing׳s incipient outer race defect. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  8. Co-encapsulation of magnetic Fe3O4 nanoparticles and doxorubicin into biodegradable PLGA nanocarriers for intratumoral drug delivery

    Directory of Open Access Journals (Sweden)

    Jia Y

    2012-03-01

    Full Text Available Yanhui Jia1, Mei Yuan1, Huidong Yuan1, Xinglu Huang2, Xiang Sui1, Xuemei Cui1, Fangqiong Tang2, Jiang Peng1, Jiying Chen1, Shibi Lu1, Wenjing Xu1, Li Zhang1, Quanyi Guo11Institute of Orthopedics, General Hospital of the Chinese People's Liberation Army, Beijing, People's Republic of China; 2Laboratory of Controllable Preparation and Application of Nanomaterials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, People's Republic of ChinaAbstract: In this study, the authors constructed a novel PLGA [poly(D,L-lactic-co-glycolic acid]-based polymeric nanocarrier co-encapsulated with doxorubicin (DOX and magnetic Fe3O4 nanoparticles (MNPs using a single emulsion evaporation method. The DOX-MNPs showed high entrapment efficiency, and they supported a sustained and steady release of DOX. Moreover, the drug release was pH sensitive, with a faster release rate in an acidic environment than in a neutral environment. In vitro, the DOX-MNPs were easily internalized into murine Lewis lung carcinoma cells and they induced apoptosis. In vivo, the DOX-MNPs showed higher antitumor activity than free DOX solution. Furthermore, the antitumor activity of the DOX-MNPs was higher with than without an external magnetic field; they were also associated with smaller tumor volume and a lower metastases incidence rate. This work may provide a new modality for developing an effective drug delivery system.Keywords: antitumor activity, external magnetic field, intratumoral injection, apoptosis, Lewis lung carcinoma

  9. Three-axis force actuator for a magnetic bearing

    Science.gov (United States)

    Gondhalekar, Vijay (Inventor)

    1998-01-01

    This invention features a three-axis force actuator that axially, radially and rotatably supports a bearing member for frictionless rotation about an axis of rotation generally coincident with a Z-axis. Also featured is a magnetic bearing having such an actuator. The actuator includes an inner member, a magnetic member and a pole assembly having a ring member and four pole extending therefrom. The poles are equi-angular spaced from each other and radially spaced about the Z-axis. The inner member extends along the Z-axis and is a highly magnetic permeable material. The magnetic member is formed about the inner member outer surface, extends along the Z-axis and is configured so one magnetic pole polarity is located at its outer surface and the other polarity pole is located at its inner surface. Preferably, the magnetic member is a radially magnetized permanent magnet. The inner surface of the ring member is magnetically coupled to the magnetic member and a face of each pole is coupled to the bearing member. The magnetic member, the pole assembly, the inner member and the bearing member cooperate to generate a magnetic field that radially and rotatably supports a rotating member secured to the bearing member. The actuator further includes a plurality of electromagnetic coils. Preferably, a coil is formed about each pole and at least 2 coils are formed about the inner member. When energized, the electromagnetic coils generate a modulated magnetic field that stabilizes the rotating member in the desired operational position.

  10. Dynamic characteristics of the rotor in a magnetically suspended control moment gyroscope with active magnetic bearing and passive magnetic bearing.

    Science.gov (United States)

    Tang, Jiqiang; Xiang, Biao; Zhang, Yongbin

    2014-07-01

    For a magnetically suspended control moment gyroscope, stiffness and damping of magnetic bearing will influence modal frequency of a rotor. In this paper the relationship between modal frequency and stiffness and damping has been investigated. The mathematic calculation model of axial passive magnetic bearing (PMB) stiffness is developed. And PID control based on internal model control is introduced into control of radial active magnetic bearing (AMB), considering the radial coupling of axial PMB, a mathematic calculation model of stiffness and damping of radial AMB is established. According to modal analysis, the relationship between modal frequency and modal shapes is achieved. Radial vibration frequency is mainly influenced by stiffness of radial AMB; however, when stiffness increases, radial vibration will disappear and a high frequency bending modal will appear. Stiffness of axial PMB mainly affects the axial vibration mode, which will turn into high-order bending modal. Axial PMB causes bigger influence on torsion modal of the rotor. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  11. Improved operation of magnetic bearings for flywheel energy storage system

    Science.gov (United States)

    Zmood, R. B.; Pang, D.; Anand, D. K.; Kirk, J. A.

    1990-01-01

    Analysis and operation of prototype 500-Wh flywheel at low speeds have shown that many factors affect the correct functioning of the magnetic bearings. An examination is made of a number of these, including magnetic bearing control system nonlinearities and displacement transducer positioning, and their effects upon the successful operation of the suspension system. It is observed that the bearing control system is extremely sensitive to actuator parameters such as coil inductance. As a consequence of the analysis of bearing relaxation oscillations, the bearing actuator design methodology which has previously been used, where coil parameter selection is based upon static considerations, has been revised. Displacement transducer sensors which overcome the collocation problem are discussed.

  12. Advanced Active-Magnetic-Bearing Thrust-Measurement System

    Science.gov (United States)

    Imlach, Joseph; Kasarda, Mary; Blumber, Eric

    2008-01-01

    An advanced thrust-measurement system utilizes active magnetic bearings to both (1) levitate a floating frame in all six degrees of freedom and (2) measure the levitation forces between the floating frame and a grounded frame. This system was developed for original use in measuring the thrust exerted by a rocket engine mounted on the floating frame, but can just as well be used in other force-measurement applications. This system offers several advantages over prior thrust-measurement systems based on mechanical support by flexures and/or load cells: The system includes multiple active magnetic bearings for each degree of freedom, so that by selective use of one, some, or all of these bearings, it is possible to test a given article over a wide force range in the same fixture, eliminating the need to transfer the article to different test fixtures to obtain the benefit of full-scale accuracy of different force-measurement devices for different force ranges. Like other active magnetic bearings, the active magnetic bearings of this system include closed-loop control subsystems, through which the stiffness and damping characteristics of the magnetic bearings can be modified electronically. The design of the system minimizes or eliminates cross-axis force-measurement errors. The active magnetic bearings are configured to provide support against movement along all three orthogonal Cartesian axes, and such that the support along a given axis does not produce force along any other axis. Moreover, by eliminating the need for such mechanical connections as flexures used in prior thrust-measurement systems, magnetic levitation of the floating frame eliminates what would otherwise be major sources of cross-axis forces and the associated measurement errors. Overall, relative to prior mechanical-support thrust-measurement systems, this system offers greater versatility for adaptation to a variety of test conditions and requirements. The basic idea of most prior active-magnetic-bearing

  13. High-Temperature, High-Load-Capacity Radial Magnetic Bearing

    Science.gov (United States)

    Provenza, Andrew; Montague, Gerald; Kascak, Albert; Palazzolo, Alan; Jansen, Ralph; Jansen, Mark; Ebihara, Ben

    2005-01-01

    A radial heteropolar magnetic bearing capable of operating at a temperature as high as 1,000 F (=540 C) has been developed. This is a prototype of bearings for use in gas turbine engines operating at temperatures and speeds much higher than can be withstood by lubricated rolling-element bearings. It is possible to increase the maximum allowable operating temperatures and speeds of rolling-element bearings by use of cooling-air systems, sophisticated lubrication systems, and rotor-vibration- damping systems that are subsystems of the lubrication systems, but such systems and subsystems are troublesome. In contrast, a properly designed radial magnetic bearing can suspend a rotor without contact, and, hence, without need for lubrication or for cooling. Moreover, a magnetic bearing eliminates the need for a separate damping system, inasmuch as a damping function is typically an integral part of the design of the control system of a magnetic bearing. The present high-temperature radial heteropolar magnetic bearing has a unique combination of four features that contribute to its suitability for the intended application: 1. The wires in its electromagnet coils are covered with an insulating material that does not undergo dielectric breakdown at high temperature and is pliable enough to enable the winding of the wires to small radii. 2. The processes used in winding and potting of the coils yields a packing factor close to 0.7 . a relatively high value that helps in maximizing the magnetic fields generated by the coils for a given supplied current. These processes also make the coils structurally robust. 3. The electromagnets are of a modular C-core design that enables replacement of components and semiautomated winding of coils. 4. The stator is mounted in such a manner as to provide stable support under radial and axial thermal expansion and under a load as large as 1,000 lb (.4.4 kN).

  14. Improvements in magnetic bearing performance for flywheel energy storage

    Science.gov (United States)

    Plant, David P.; Anand, Davinder K.; Kirk, James A.; Calomeris, Anthony J.; Romero, Robert L.

    1988-01-01

    The paper considers the development of a 500-Watt-hour magnetically suspended flywheel stack energy storage system. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of noncontacting displacement transducers, and performance enhancements of magnetic bearings. Experimental results show that a stack flywheel energy storage system is feasible technology.

  15. An Integrated Magnetic Circuit Model and Finite Element Model Approach to Magnetic Bearing Design

    Science.gov (United States)

    Provenza, Andrew J.; Kenny, Andrew; Palazzolo, Alan B.

    2003-01-01

    A code for designing magnetic bearings is described. The code generates curves from magnetic circuit equations relating important bearing performance parameters. Bearing parameters selected from the curves by a designer to meet the requirements of a particular application are input directly by the code into a three-dimensional finite element analysis preprocessor. This means that a three-dimensional computer model of the bearing being developed is immediately available for viewing. The finite element model solution can be used to show areas of magnetic saturation and make more accurate predictions of the bearing load capacity, current stiffness, position stiffness, and inductance than the magnetic circuit equations did at the start of the design process. In summary, the code combines one-dimensional and three-dimensional modeling methods for designing magnetic bearings.

  16. High-Temperature Magnetic Bearings for Gas Turbine Engines

    Science.gov (United States)

    1996-01-01

    Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and coordination with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of the bearing times rpm) limit on engine speed and allow active vibration cancellation systems to be used--resulting in a more efficient, "more electric" engine. Finally, the Integrated High-Performance Turbine Engine Technology (IHPTET) Program, a joint Department of Defense/industry program, identified a need for a hightemperature (as high as 1200 F) magnetic bearing that could be demonstrated in a phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator are a series of electrical wire coils that form a series of electric magnets around the circumference. The magnets exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it in the center of the cavity. The engine rotor, bearings, and case form a flexible structure that contains a large number of modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system. Cobalt steel has a curie point greater than 1700 F, and copper wire has a melting point beyond that. Therefore, practical limitations associated with the maximum magnetic field strength in the cobalt steel and the stress in the rotating components limit the temperature to about 1200 F. The objective of this effort is to determine the limits in temperature and speed of a magnetic bearing operating in an engine. Our approach is to use our in

  17. Optimum design of flywheel storage system using superconducting magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Soo Hun; Kim, Jong Soo; Kim, Jung Guen [Ajou University, Suwon (Korea)

    1999-03-01

    The flywheel energy storage system using superconducting magnetic bearings is a device to store electrical energy as rotational kinetic energy by motor and to convert it to electrical energy by generator when it is necessary. An analytical model of the SMB-FESS is necessary to identify the system behavior. At first, we have to model the superconducting magnetic bearings that have different characteristics from mechanical and the electric magnetic bearing. Modeling the SMB is same as estimating the bearing parameter. The theoretical modal parameter is calculated through the equation of motion and the experimental modal parameter is estimated through the impact testing (modal testing). The bearing parameter is searched by using the non-linear least square method until the theoretical result corresponds to the experimental result. The suggested modeling method is verified by comparing experimental and analytical frequency response function. The loss mechanisms associated with the combined effects of magnetic unbalance and hysteretic damping in the superconducting flywheel system have been modeled under the assumption that dynamic characteristics of the bearing can be approximated by a linear, elastic anisotropic spring with complex stiffness. Theoretical energy loss model effected by unbalance is derived from generalized rotational model including gyroscopic effect and generalized response. The validity of suggested energy loss model is confirmed by comparing experimental deceleration curve. (author). 12 refs., 28 figs., 10 tabs.

  18. Magnetic bearings. Theory, design, and application to rotating machinery

    Energy Technology Data Exchange (ETDEWEB)

    Schweitzer, Gerhard [Mechatronics Consulting, Kuesnacht (Switzerland); Maslen, Eric H. (eds.) [Virginia Univ., Charlottesville, VA (United States). Dept. Mechanical and Aerospace Engineering

    2009-07-01

    Compiling the expertise of nine pioneers of the field, Magnetic Bearings - Theory, Design, and Application to Rotating Machinery offers an encyclopedic study of this rapidly emerging field with a balanced blend of commercial and academic perspectives. Every element of the technology is examined in detail, beginning at the component level and proceeding through a thorough exposition of the design and performance of these systems. The roster of authors boasts an average of twenty-five years of work developing magnetic bearing technology - a truly exceptional pool of experience. The book is organized in a logical fashion, starting with an overview of the technology and a survey of the range of applications. A background chapter then explains the central concepts of active magnetic bearings while avoiding a morass of technical details. From here, the reader continues to a meticulous, state-of-the-art exposition of the component technologies and the manner in which they are assembled to form the AMB/rotor system. These system models and performance objectives are then tied together through extensive discussions of control methods for both rigid and flexible rotors, including consideration of the problem of system dynamics identification. Supporting this, the issues of system reliability and fault management are discussed from several useful and complementary perspectives. At the end of the book, numerous special concepts and systems, including micro-scale bearings, self-bearing motors, and self-sensing bearings, are put forth as promising directions for new research and development. Newcomers to the field will find the material highly accessible while veteran practitioners will be impressed by the level of technical detail that emerges from a combination of sophisticated analysis and insights gleaned from many collective years of practical experience. An exhaustive, self-contained text on active magnetic bearing technology, this book should be a core reference for

  19. A Hydrostatic Bearing Test System for Measuring Bearing Load Using Magnetic-Fluid Lubricants.

    Science.gov (United States)

    Weng, Huei Chu; Chen, Lu-Yu

    2016-05-01

    This paper conducts a study on the design of a hydrostatic bearing test system. It involves the determination of viscous properties of magnetic-fluid lubricants. The load of a hydrostatic thrust bearing using a water-based magnetite nanofluid of varying volume flow rate is measured under an applied external induction field via the test system. Results reveal that the presence of nanoparticles in a carrier liquid would cause an enhanced bearing load. Such an effect could be further magnified by increasing the lubricant volume flow rate or the external induction field strength.

  20. Effects of Operational Losses in Active Magnetic Bearing Designs.

    Directory of Open Access Journals (Sweden)

    Prince Owusu-Ansah

    2016-04-01

    Full Text Available This paper studies the effects of different forms of operational losses that are associated with active magnetic bearing designs.Active magnetic bearings are generally considered as having much lower frictional losses as compared to fluid and roller bearings, however AMBs are considered as more complex mechatronic systems, associated with various potential power loss mechanisms during it cycle of operation. Minimizing of losses consist of various measures and depends largely on the requirements of the application,among all these losses, aerodynamic losses are classified as been the more dominant in modern high speed applications and turbomachinery especially in expanders and compressors where its working gases are considered to be under very high pressures and temperaturesVarious forms of losses such as hysteresis, eddy current, iron, aerodynamic have been discussed. The methods of reducing these losses in order reduce energy losses with the ultimate goal of improving bearing efficiency haveall been discussed in this paper

  1. Improvement of azimuthal homogeneity in permanent-magnet bearing rotors

    Science.gov (United States)

    Hull, J. R.; Rossing, T. D.; Mulcahy, T. M.; Uherka, K. L.

    1992-10-01

    Permanent magnets that are levitated and rotating over a bulk high-temperature superconductor (HTS) form the basis of many superconducting bearing designs. Experiments have shown that the rotational-loss 'coefficient of friction' for thrust bearings of this type can be as low as 8 x 10(exp -6). While the loss mechanisms of such bearings are not well understood, the azimuthal homogeneity of the rotating permanent magnet is believed to play an important role in determining the loss. One possible loss mechanism is magnetic hysteresis in the HTS, where the energy loss E per cycle is derived from the critical state model and given by E = K (Delta B)(sup 3)/J(sub c) where K is a geometric coefficient, Delta B is the variation in magnetic field at the surface of the HTS experienced during a rotation of the levitated magnet, and J(sub c) is the critical current density of the HTS. It is clear that a small decrease in Delta B (i.e., decreasing the azimuthal inhomogeneity of the rotating magnetic field) could have profound effects on decreasing E and the rotational coefficient of friction. The role of Delta B is also expected to be significant in reducing losses from eddy currents and other mechanisms. Low rotational losses in HTS bearings have been demonstrated only for levitated masses of several grams. For practical bearings, it is important to obtain these low losses with larger levitated masses. There are two main routes toward decreasing Delta B. The first is to improve the alignment of the magnetic particles during fabrication and to maintain close tolerances on grinding angles during manufacture of the permanent magnet. The second, the subject of this paper, is to provide correctional procedures after the magnet is fabricated.

  2. Fail-Safe Magnetic Bearing Controller Demonstrated Successfully

    Science.gov (United States)

    Choi, Benjamin B.; Provenza, Andrew J.

    2001-01-01

    The Structural Mechanics and Dynamics Branch has successfully demonstrated a fail-safe controller for the Fault-Tolerant Magnetic Bearing rig at the NASA Glenn Research Center. The rotor is supported by two 8-pole redundant radial bearings, and coil failing situations are simulated by manually shutting down their control current commands from the controller cockpit. The effectiveness of the controller was demonstrated when only two active coils from each radial bearing could be used (that is, 14 coils failed). These remaining two coils still levitated the rotor and spun it without losing stability or desired position up to the maximum allowable speed of 20,000 rpm.

  3. Therapeutical Neurotargeting via Magnetic Nanocarrier: Implications to Opiate-Induced Neuropathogenesis and NeuroAIDS.

    Science.gov (United States)

    Sagar, Vidya; Pilakka-Kanthikeel, Sudheesh; Atluri, Venkata S R; Ding, Hong; Arias, Adriana Y; Jayant, Rahul D; Kaushik, Ajeet; Nair, Madhavan

    2015-10-01

    Magnetite (Fe3O4) is the most commonly and extensively explored magnetic nanoparticles (MNPs) for drug-targeting and imaging in the field of biomedicine. Nevertheless, its potential application as safe and effective drug-carrier for CNS (Central Nervous System) anomalies is very limited. Previous studies have shown an entangled epidemic of opioid use and HIV infection and increased neuropathogenesis. Opiate such as morphine, heroine, etc. are used frequently as recreational drugs. Existing treatments to alleviate the action of opioid are less effective at CNS level due to impermeability of therapeutic molecules across brain barriers. Thus, development of an advanced nanomedicine based approach may pave the way for better treatment strategies. We herein report magnetic nanoformulation of a highly selective and potent morphine antagonist, CTOP (D-Pen-Cys-Tyr-DTrp-Orn-Thr-Pen-Thr-NH2), which is impenetrable to the brain. MNPs, synthesized in size range from 25 to 40 nm, were characterized by Transmission electron microscopy and assembly of MNPs-CTOP nanoformulations were confirmed by FTIR spectroscopy and fluorescent detection. Flow-cytometry analysis showed that biological efficacy of this nanoformulation in prevention of morphine induced apoptosis in peripheral blood mononuclear cells remains equivalent to that of free CTOP. Similarly, confocal microscopy reveals comparable efficacy of free and MNPs bound CTOP in protecting modulation of neuronal dendrite and spine morphology during morphine exposure and morphine-treated HIV infection. Further, typical transmigration assay showed increased translocation of MNPs across in vitro blood-brain barrier upon exposure of external magnetic force where barrier integrity remains unaltered. Thus, the developed nanoformulation could be effective in targeting brain by application of external magnetic force to treat morphine addiction in HIV patients.

  4. Applying Standard Industrial Components for Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Bert-Uwe Koehler

    2017-02-01

    Full Text Available With the increasing number of active magnetic bearing applications, satisfying additional requirements is becoming increasingly more important. As for every technology, moving away from being a niche product and achieving a higher level of maturity, these requirements relate to robustness, reliability, availability, safety, security, traceability, certification, handling, flexibility, reporting, costs, and delivery times. Employing standard industrial components, such as those from flexible modular motion control drive systems, is an approach that allows these requirements to be satisfied while achieving rapid technological innovation. In this article, we discuss technical and non-technical aspects of using standard industrial components in magnetic bearing applications.

  5. Estimation of optimum operating point for thrust magnetic bearing with solid magnet

    Institute of Scientific and Technical Information of China (English)

    孙首群; 田育民

    2003-01-01

    A carrying capacity-temperature rise analysis model has been established for analysis of the carrying capacity, temperature rise and carrying capacity-temperature rise characteristic of a thrust magnetic bearing with solid magnet. The results indicate that there must be an optimal operating point for the thrust magnetic beating with solid magnet. The main factors having effect on carrying capacity-temperature rise include static gap and/or ampere-turns. With proper static gap chosen, the bearing can be run near the optimal operating point by adjhusting ampere-turns, thereby optimizing the bearing properties.

  6. Superparamagnetic reconstituted high-density lipoprotein nanocarriers for magnetically guided drug delivery

    Science.gov (United States)

    Sabnis, Sarika; Sabnis, Nirupama A; Raut, Sangram; Lacko, Andras G

    2017-01-01

    Current cancer chemotherapy is frequently associated with short- and long-term side effects, affecting the quality of life of cancer survivors. Because malignant cells are known to overexpress specific surface antigens, including receptors, targeted drug delivery is often utilized to reduce or overcome side effects. The current study involves a novel targeting approach using specifically designed nanoparticles, including encapsulation of the anti-cancer drug valrubicin into superparamagnetic iron oxide nanoparticle (SPION) containing reconstituted high-density lipoprotein (rHDL) nanoparticles. Specifically, rHDL–SPION–valrubicin hybrid nanoparticles were assembled and characterized with respect to their physical and chemical properties, drug entrapment efficiency and receptor-mediated release of the drug valrubicin from the nanoparticles to prostate cancer (PC-3) cells. Prussian blue staining was used to assess nanoparticle movement in a magnetic field. Measurements of cytotoxicity toward PC-3 cells showed that rHDL–SPION–valrubicin nanoparticles were up to 4.6 and 31 times more effective at the respective valrubicin concentrations of 42.4 µg/mL and 85 µg/mL than the drug valrubicin alone. These studies showed, for the first time, that lipoprotein drug delivery enhanced via magnetic targeting could be an effective chemotherapeutic strategy for prostate cancer. PMID:28260891

  7. Room Temperature Characterization of a Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Montague, Gerald; Jansen, Mark; Provenza, Andrew; Jansen, Ralph; Ebihara, Ben; Palazzolo, Alan

    2002-01-01

    Open loop, experimental force and power measurements of a three-axis, radial, heteropolar magnetic bearing at room temperature for rotor speeds up to 20,000 RPM are presented in this paper. The bearing, NASA Glenn Research Center's and Texas A&M's third generation high temperature magnetic bearing, was designed to operate in a 1000 F (540 C) environment and was primarily optimized for maximum load capacity. The experimentally measured force produced by one C-core of this bearing was 630 lb. (2.8 kN) at 16 A, while a load of 650 lbs (2.89 kN) was predicted at 16 A using 1D circuit analysis. The maximum predicted radial load for one of the three axes is 1,440 lbs (6.41 kN) at room temperature. The maximum measured load of an axis was 1050 lbs. (4.73 kN). Results of test under rotating conditions showed that rotor speed has a negligible effect on the bearing's load capacity. A single C-core required approximately 70 W of power to generate 300 lb (1.34 kN) of magnetic force. The room temperature data presented was measured after three thermal cycles up to 1000 F (540 C), totaling six hours at elevated temperatures.

  8. Development of a dc motor with virtually zero powered magnetic bearing

    Science.gov (United States)

    1971-01-01

    The development of magnetic bearings for use in direct current electric motors is discussed. The characteristics of the magnets used in the construction of the bearings are described. A magnetic bearing using steel armoring on permanent magnets was selected for performance tests. The specifications of the motor are presented. The test equipment used in the evaluation is described.

  9. Low-stiction magnetic bearing for satellite application

    Science.gov (United States)

    Rajagopal, K. R.; Sivadasan, K. K.

    2002-05-01

    In this article, the design and development of a low-stiction two-axis-active magnetic bearing used in the reaction wheel of a remote sensing satellite is presented. Conventional design of the magnetic circuit and improvements in the design using finite element (FE) analysis were carried out. The results of investigations carried out to bring down the stiction torque of the magnetic bearing to a very low value of less than 1×10-4 Nm are also presented. Ideally for zero stiction, the cogging between the moving and stationary parts must be zero. In a reaction wheel of the satellite, there will be a permanent magnet brushless dc motor as the drive motor. Magnetic or eddy current sensors present in the motor commutation circuit will induce cogging between the moving and stationary parts. In this work, by properly designing all subsystems, the stiction has been brought down to as low as 0.75×10-4 Nm. Test results of the developed magnetic bearing match fairly with the computed values by FE analysis.

  10. Synchronous Control Effort Minimized for Magnetic-Bearing-Supported Shaft

    Science.gov (United States)

    Brown, Gerald V.

    2001-01-01

    Various disturbances that are synchronous with the shaft speed can complicate radial magnetic bearing control. These include position sensor target irregularities (runout) and shaft imbalance. The method presented here allows the controller to ignore all synchronous harmonics of the shaft position input (within the closed-loop bandwidth) and to respond only to asynchronous motions. The result is reduced control effort.

  11. Identification of Parameters in Active Magnetic Bearing Systems

    DEFF Research Database (Denmark)

    Lauridsen, Jonas Skjødt; Voigt, Andreas Jauernik; Mandrup-Poulsen, Christian

    2016-01-01

    A method for identifying uncertain parameters in Active Magnetic Bearing (AMB) based rotordynamic systems is introduced and adapted for experimental application. The Closed Loop Identification (CLI) method is utilised to estimate the current/force factors Ki and the displacement/force factors Ks...

  12. Identification of Parameters in Active Magnetic Bearing Systems

    DEFF Research Database (Denmark)

    Lauridsen, Jonas Skjødt; Voigt, Andreas Jauernik; Mandrup-Poulsen, Christian

    2016-01-01

    A method for identifying uncertain parameters in Active Magnetic Bearing (AMB) based rotordynamic systems is introduced and adapted for experimental application. The Closed Loop Identification (CLI) method is utilised to estimate the current/force factors Ki and the displacement/force factors Ks...

  13. Vibration Control in Turbomachinery Using Active Magnetic Journal Bearings

    Science.gov (United States)

    Knight, Josiah D.

    1996-01-01

    The effective use of active magnetic bearings for vibration control in turbomachinery depends on an understanding of the forces available from a magnetic bearing actuator. The purpose of this project was to characterize the forces as functions shaft position. Both numerical and experimental studies were done to determine the characteristics of the forces exerted on a stationary shaft by a magnetic bearing actuator. The numerical studies were based on finite element computations and included both linear and nonlinear magnetization functions. Measurements of the force versus position of a nonrotating shaft were made using two separate measurement rigs, one based on strain gage measurement of forces, the other based on deflections of a calibrated beam. The general trends of the measured principal forces agree with the predictions of the theory while the magnitudes of forces are somewhat smaller than those predicted. Other aspects of theory are not confirmed by the measurements. The measured forces in the normal direction are larger than those predicted by theory when the rotor has a normal eccentricity. Over the ranges of position examined, the data indicate an approximately linear relationship between the normal eccentricity of the shaft and the ratio of normal to principal force. The constant of proportionality seems to be larger at lower currents, but for all cases examined its value is between 0.14 and 0.17. The nonlinear theory predicts the existence of normal forces, but has not predicted such a large constant of proportionality for the ratio. The type of coupling illustrated by these measurements would not tend to cause whirl, because the coupling coefficients have the same sign, unlike the case of a fluid film bearing, where the normal stiffness coefficients often have opposite signs. They might, however, tend to cause other self-excited behavior. This possibility must be considered when designing magnetic bearings for flexible rotor applications, such as gas

  14. High Temperature, Permanent Magnet Biased, Fault Tolerant, Homopolar Magnetic Bearing Development

    Science.gov (United States)

    Palazzolo, Alan; Tucker, Randall; Kenny, Andrew; Kang, Kyung-Dae; Ghandi, Varun; Liu, Jinfang; Choi, Heeju; Provenza, Andrew

    2008-01-01

    This paper summarizes the development of a magnetic bearing designed to operate at 1,000 F. A novel feature of this high temperature magnetic bearing is its homopolar construction which incorporates state of the art high temperature, 1,000 F, permanent magnets. A second feature is its fault tolerance capability which provides the desired control forces with over one-half of the coils failed. The construction and design methodology of the bearing is outlined and test results are shown. The agreement between a 3D finite element, magnetic field based prediction for force is shown to be in good agreement with predictions at room and high temperature. A 5 axis test rig will be complete soon to provide a means to test the magnetic bearings at high temperature and speed.

  15. Experimental Contribution to High-Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2007-01-01

    Parameter identification procedures and model validation are major steps toward intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... of the magnetic forces is conducted using different experimental tests: (i) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor (ii) by measuring the input current and bearing...... gap variations, monitoring the bearing input signals. Advantages and drawbacks of the different methodologies are critically discussed. The linearity ranges are experimentally determined and the characterization of magnetic forces with a high accuracy of

  16. Experimental Contribution to High Precision Characterization of Magnetic Forces in Active Magnetic Bearings

    DEFF Research Database (Denmark)

    Kjølhede, Klaus; Santos, Ilmar

    2006-01-01

    Parameter identification procedures and model validation are major steps towards intelligent machines supported by active magnetic bearings (AMB). The ability of measuring the electromagnetic bearing forces, or deriving them from measuring the magnetic flux, strongly contributes to the model...... of the magnetic forces is conducted using different experimental tests: (a) by using hall sensors mounted directly on the poles (precise measurements of the magnetic flux) and by an auxiliary system, composed of strain gages and flexible beams attached to the rotor, (b) by measuring the input current and bearing...... gap variations, monitoring the bearing input signals. Advantages and drawbacks of the different methodologies are critically discussed. The linearity ranges are experimentally determined and the characterization of magnetic forces with a high accuracy of less than 1% is achieved. (%error is normalized...

  17. Flywheel energy storage using superconducting magnetic bearings

    Science.gov (United States)

    Abboud, R. G.; Uherka, K.; Hull, J.; Mulcahy, T.

    Storage of electrical energy on a utility scale is currently not practicable for most utilities, preventing the full utilization of existing base-load capacity. A potential solution to this problem is Flywheel Energy Storage (FES), made possible by technological developments in high-temperature superconducting materials. Commonwealth Research Corporation (CRC), the research arm of Commonwealth Edison Company, and Argonne National Laboratory are implementing a demonstration project to advance the state of the art in high temperature superconductor (HTS) bearing performance and the overall demonstration of efficient Flywheel Energy Storage. Currently, electricity must be used simultaneously with its generation as electrical energy storage is not available for most utilities. Existing storage methods either are dependent on special geography, are too expensive, or are too inefficient. Without energy storage, electric utilities, such as Commonwealth Edison Company, are forced to cycle base load power plants to meet load swings in hourly customer demand. Demand can change by as much as 30% over a 12-hour period and result in significant costs to utilities as power plant output is adjusted to meet these changes. HTS FES systems can reduce demand-based power plant cycling by storing unused nighttime capacity until it is needed to meet daytime demand.

  18. A Hybrid Nonlinear Control Scheme for Active Magnetic Bearings

    Science.gov (United States)

    Xia, F.; Albritton, N. G.; Hung, J. Y.; Nelms, R. M.

    1996-01-01

    A nonlinear control scheme for active magnetic bearings is presented in this work. Magnet winding currents are chosen as control inputs for the electromechanical dynamics, which are linearized using feedback linearization. Then, the desired magnet currents are enforced by sliding mode control design of the electromagnetic dynamics. The overall control scheme is described by a multiple loop block diagram; the approach also falls in the class of nonlinear controls that are collectively known as the 'integrator backstepping' method. Control system hardware and new switching power electronics for implementing the controller are described. Various experiments and simulation results are presented to demonstrate the concepts' potentials.

  19. TWO DIMENTIONAL STATIC MAGNETIC ANALYSIS OF RADIAL MAGNETIC BEARING SYSTEMS WITH DIFFERENT STRUCTURES

    Directory of Open Access Journals (Sweden)

    Yusuf ÖNER

    2005-03-01

    Full Text Available The friction loss of electrical machines is an important problem as like in other rotary machines. In addition, the bearings, where the friction losses occur, also require lubrication at periodic intervals and need to be maintained. In this study, to minimize the friction loss of electrical motor, two dimentional static magnetic analysis of radial magnetic bearing systems with different structures are performed and compared with each other; also, magnetic bearing system with four-pole is realized and applied to an induction motor. In simulation, the forces applied to the rotor of induction motor from designed magnetic bearing system are calculated in a computer by using FEMM software package. In application, when comparing designed magnetic bearing system with mechanical bearings up to the revolution of 350 rpm, it was observed that the loss of no-load operating condition of induction motor is decreased about 15 % with magnetic bearing system. In addition to this, mechanical noisy of the motor is also decreased considerably.

  20. Analysis and design of permanent magnet biased magnetic bearing based on hybrid factor

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2016-03-01

    Full Text Available In this article, hybrid factor is proposed for hybrid magnetic bearing. The hybrid factor is defined as the ratio of the force produced by the permanent magnet and the forces produced by the permanent magnet and current in hybrid magnetic bearing. It is deduced from a certain radial hybrid magnetic bearing using its important parameters such as the current stiffness and displacement stiffness at first and then the dynamic model of magnetically suspended rotor system is established. The relationship between structural parameters and control system parameters is analyzed based on the hybrid factor. Some influencing factors of hybrid factor in hybrid magnetic bearing, such as the size of the permanent magnet, length of air gap, and area of the stator poles, are analyzed in this article. It can be concluded that larger hybrid factor can be caused by the smaller power loss according to the definition of hybrid factor mentioned above. Meanwhile, the hybrid factor has a maximum value, which is related to control system parameters such as proportional factor expect for structural parameters. Finally, the design steps of parameters of hybrid magnetic bearing can be concluded.

  1. Design of a small centrifugal blood pump with magnetic bearings.

    Science.gov (United States)

    Jahanmir, Said; Hunsberger, Andrew Z; Ren, Zhaohui; Heshmat, Hooshang; Heshmat, Crystal; Tomaszewski, Michael J; Walton, James F

    2009-09-01

    Design of a blood pump with a magnetically levitated rotor requires rigorous evaluation of the magnetic bearing and motor requirements and analysis of rotor dynamics and hydraulic performance with attention to hemolysis and thrombosis potential. Given the desired geometric dimensions, the required operating speed, flow in both the main and wash flow regions, and magnetic bearing performance, one of several design approaches was selected for a new prototype. Based on the estimated operating speed and clearance between the rotor and stator, the motor characteristics and dimensions were estimated. The motor stiffness values were calculated and used along with the hydraulic loading due to the fluid motion to determine the best design for the axial and radial magnetic bearings. Radial and axial stability of the left ventricular assist device prototype was verified using finite element rotor dynamic analysis. The analysis indicated that the rotor could be completely levitated and spun to the desired operating speed with low power loss and no mechanical contact. In vitro experiments with a mock loop test setup were performed to evaluate the performance of the new blood pump prototype.

  2. Experimental High Temperature Characterization of a Magnetic Bearing for Turbomachinery

    Science.gov (United States)

    Montague, Gerald; Jansen, Mark; Provenza, Andrew; Palazzolo, Alan; Jansen, Ralph; Ebihara, Ben

    2003-01-01

    Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000 F (538 C) and rotor speeds to 15,000 RPM along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core using 22A was 600 lb. (2.67 kN) at room temperature and 380 lb. (1.69 kN) at 1000 F (538 C). These values were compared with force predictions based on a 1D magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing s load capacity. One C-core required approximately 340 W of power to generate 190 lb. (8.45 kN) of magnetic force at 1000 F (538 C); however the magnetic air gap was much larger than at room temperature. The data presented is after the bearing had already operated six thermal cycles and eleven total (not consecutive) hours at 1000 F (538 C).

  3. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Morii, Y.; Sukedai, M. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetic bearing has been developed. In the hybrid system, effect of the pinning force becomes smaller. Influence of the vibration and the gradient angle in the resonance state is large. The resonance frequency becomes small in the hybrid bearing system. The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  4. Optical fibre bragg gratings based magnetic force measurement of magnetic bearings

    Science.gov (United States)

    Ding, Guoping; Zhou, Zude; Hu, Yefa; Zhou, Jianhua

    2008-12-01

    Magnetic bearings are typical electromechanical systems of high performance. Current-displacement-force relationship between stator and rotor is an important research topic of magnetic bearings. The critical issue is to realize magnetic force online dynamic measurement. This paper presents a novel method on magnetic force measurement of magnetic bearings with optical fibre bragg gratings (FBG), which realizes a non-contact and online force measurement with simple configuration, good noise immunity even when the rotor is running. A novel micro force transducer is designed and fabricated, which is mounted within the stator magnetic pole. To obtain current-displacement-force relationship a FBG based magnetic force measurement test rig is setup to simulate magnetic bearing working states as the stator coils currents, air gap between stator and rotor, rotor speed is adjustable. Magnetic force is measured under three classifications of test conditions and test results are presented. The measurement data show good consistency with the theory analysis and calculation, which means that the FBG based magnetic force measurement is available and of good accuracy.

  5. Adaptive control of an active magnetic bearing with external disturbance.

    Science.gov (United States)

    Dong, Lili; You, Silu

    2014-09-01

    Adaptive back stepping control (ABC) is originally applied to a linearized model of an active magnetic bearing (AMB) system. Our control goal is to regulate the deviation of the magnetic bearing from its equilibrium position in the presence of an external disturbance and system uncertainties. Two types of ABC methods are developed on the AMB system. One is based on full state feedback, for which displacement, velocity, and current states are assumed available. The other one is adaptive observer based back stepping controller (AOBC) where only displacement output is measurable. An observer is designed for AOBC to estimate velocity and current states of AMB. Lyapunov approach proves the stabilities of both regular ABC and AOBC. Simulation results demonstrate the effectiveness and robustness of two controllers. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  6. Active Displacement Control of Active Magnetic Bearing System

    Directory of Open Access Journals (Sweden)

    Kertész Milan

    2014-12-01

    Full Text Available The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES. The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL. APDL is used to create the loops of transient simulations where boundary conditions (BC are updated based upon a “gap sensor” which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  7. Active Displacement Control of Active Magnetic Bearing System

    Science.gov (United States)

    Kertész, Milan; Kozakovič, Radko; Magdolen, Luboš; Masaryk, Michal

    2014-12-01

    The worldwide energy production nowadays is over 3400 GW while storage systems have a capacity of only 90 GW [1]. There is a good solution for additional storage capacity in flywheel energy storage systems (FES). The main advantage of FES is its relatively high efficiency especially with using the active magnetic bearing system. Therefore there exist good reasons for appropriate simulations and for creating a suitable magneto-structural control system. The magnetic bearing, including actuation, is simulated in the ANSYS parametric design language (APDL). APDL is used to create the loops of transient simulations where boundary conditions (BC) are updated based upon a "gap sensor" which controls the nodal position values of the centroid of the shaft and the current density inputs onto the copper windings.

  8. Magnetic Titanohematite Minerals in Uranium-Bearing Sandstones

    Science.gov (United States)

    Reynolds, Richard L.

    1977-01-01

    Detrital grains of the rhombohedral ilmenite (FeT1O3)--hematite (Fe2O3) solid solution series (titanohematites) have been identified by thermomagnetic, reflection microscopic, and X-ray diffraction analysis in six uranium-bearing sandstones in the western United States. Many of the titanohematites are ferrimagnetic and have Curie temperatures ranging from about 70 Deg C to 220 Deg C. Magnetic titanohematite is commonly more abundant than magnetite in many samples and, therefore, should be considered as a major source of the permanent magnetization in these units.

  9. Electrostatic stabilizer for a passive magnetic bearing system

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2016-10-11

    Electrostatic stabilizers are provided for passive bearing systems composed of annular magnets having a net positive stiffness against radial displacements and that have a negative stiffness for vertical displacements, resulting in a vertical instability. Further embodiments are shown of a radial electrostatic stabilizer geometry (using circuitry similar to that employed in the vertical stabilizer). This version is suitable for stabilizing radial (lateral) displacements of a rotor that is levitated by annular permanent magnets that are stable against vertical displacements but are unstable against radial displacements.

  10. Development of REBCO HTS Magnet of Magnetic Bearing for Large Capacity Flywheel Energy Storage System

    Science.gov (United States)

    Mukoyama, Shinichi; Matsuoka, Taro; Furukawa, Makoto; Nakao, Kengo; Nagashima, Ken; Ogata, Masafumi; Yamashita, Tomohisa; Hasegawa, Hitoshi; Yoshizawa, Kazuhiro; Arai, Yuuki; Miyazaki, Kazuki; Horiuchi, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    A flywheel energy storage system (FESS) is a promising electrical storage system that moderates fluctuation of electrical power from renewable energy sources. The FESS can charge and discharge the surplus electrical power repetitively with the rotating energy. Particularly, the FESS that utilizes a high temperature superconducting magnetic bearing (HTS bearing) is lower loss than conventional FESS that has mechanical bearing, and has property of longer life operation than secondary batteries. The HTS bearing consists of a HTS bulk and double-pancake coils used 2nd generation REBCO wires. In the development, the HTS double-pancake coils were fabricated and were provided for a levitation test to verify the possibility of the HTS bearing. We successfully confirmed the magnetic field was achieved to design value, and levitation force in the configuration of one YBCO bulk and five double pan-cake coils was obtained to a satisfactory force of 39.2 kN (4 tons).

  11. A Novel Integral 5-DOFs Hybrid Magnetic Bearing with One Permanent Magnet Ring Used for Turboexpander

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2014-01-01

    Full Text Available We propose a novel combined five-degrees-of-freedom (5-DOFs hybrid magnetic bearing (HMB with only one permanent magnet ring (PMR used for turboexpanders. It has two radial magnetic bearing (RMB units; each has four poles and one thrust magnetic bearing (TMB to control 5-DOFs. Based on one PMR, the bias flux of the two radial magnetic bearing units and the one thrust magnetic bearing unit is constructed. As a result, ultra-high-speed, lower power loss, small size, and low cost can be achieved. Furthermore, the equivalent magnetic circuit method and 3D finite element method (FEM are used to model and analyze the combined 5-DOFs HMB. The force-current, force-position, torque-coil currents, the torque-angle position, and the stiffness models of the combined 5-DOFs HMB are given. Moreover, its coupling problems between the RMB units and the AMB unit are also proposed in this paper. An example is given to clarify the mathematical models and the coupling problems, and the linearized models are proposed for the follow-up controller design.

  12. Repulsive Magnetic Bearing Using a Piezoelectric Actuator for Stabilization

    Science.gov (United States)

    Mizuno, Takeshi; Aizawa, Mitsunori

    A repulsive magnetic bearing system equipped with a piezoelectric actuator for the motion control of permanent magnets is studied experimentally. In this system, the radial motions of the rotor are passively supported by repulsive forces between permanent magnets. The motion in the axial direction is stabilized by moving the permanent magnets for radial suspension with a piezoelectric actuator. In the experiments, a piezoelectric actuator with a stroke of 200µm was installed first. PD and I-PD controllers were applied to achieve levitation without any mechanical contact. It was experimentally shown that the dynamic characteristics of the levitation system could be adjusted by pole assignment. Next the actuator was replaced by an actuator with a stoke of 90µm. Experimental results demonstrated that the rotor can follow stepwise command signal whose magnitude was within ±20µm.

  13. A new self-propelled magnetic bearing with helical windings

    Science.gov (United States)

    Shayak, B.

    2016-12-01

    In this work, a design is proposed for an active, permanent magnet based, self-propelled magnetic bearing, i.e. levitating motor having the following features: (i) simple winding structure, (ii) high load supporting capacity, (iii) no eccentricity sensors, (iv) stable confinement in all translational dimensions, (v) stable confinement in all rotational dimensions, and (vi) high efficiency. This design uses an architecture consisting of a helically wound three-phase stator, and a rotor with the magnets also arranged in a helical manner. Active control is used to excite the rotor at a torque angle lying in the second quadrant. This torque angle is independent of the rotor's position inside the stator cavity; hence the control algorithm is similar to that of a conventional permanent magnet synchronous motor. It is motivated through a physical argument that the bearing rotor develops a lift force proportional to the output torque and that it remains stably confined in space. These assertions are then proved rigorously through a calculation of the magnetic fields, forces and torques. The stiffness matrix of the system is presented and a discussion of stable and unstable operating regions is given.

  14. Using Magnetic Bearing Orbit Information to Maximize Centrifugal Compressor Efficiency at Off-Design Conditions

    OpenAIRE

    2014-01-01

    Active magnetic bearings used on oil-free centrifugal refrigeration compressors have lower stiffness than conventional oil-lubricated journal or rolling element bearings. The lower stiffness of these bearings makes them sensitive to internal flow instabilities that are precursors of rotating stall or compressor surge. At operating conditions far away from surge the internal flow is very stable and the magnetic bearings keep the shaft centered, resulting in a minimal bearing orbit. The interna...

  15. Applied CATIA Secondary Development to Parametric Design of Active Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    Zhang Li

    2016-01-01

    Full Text Available Based on the properties of active magnetic bearing, the electromagnetic parameters and structure parameters are analyzed, parametric design method is introduced to study the structure of active magnetic bearing. Through a program personalization process that is in accordance with active magnetic bearing is established. Personalization process aims to build the parametric model of active magnetic bearings and component library by use of CATIA secondary development. Component library is to build assembly model for a multiple degree of freedom magnetic bearing system. Parametric design is a method that provides the direction for its structural design.

  16. Biodegradation reduces magnetization in oil bearing rocks: magnetization results of a combined chemical and magnetic study

    Science.gov (United States)

    Emmerton, S.; Muxworthy, A. R.; Sephton, M. A.; Williams, W.

    2012-12-01

    A relationship between hydrocarbons and their magnetic signatures has been alluded to for decades but this is the first study to combine geochemical and magnetic data. We report an extended study that identifies a definitive connection between magnetic mineralogy and biodegradation within oil-bearing rocks. Samples from Colombia, Canada Indonesia and the UK were collected and magnetically characterized. A negative linear regression in log space between magnetic susceptibility and the percentage of extractable organic matter was observed for individual reservoirs. To determine if this relationship is due to the activity of bacteria or migration of the oil, the percentage of oil components; aliphatic, aromatics, polars and resins and the biodegradation state of the samples were compared to the magnetic susceptibility and magnetic mineralogy of the samples. Geochemical biomarker data revealed that all oil samples were derived from mature type-II kerogen, which was deposited in oxygen-poor environments allowing for an investigation into biodegradation variations. Biodegradation is the decrease of oil quality through the conversion of aliphatic hydrocarbons to polar constituents mainly through the activity of bacteria. A distinct decrease in magnetic susceptibility was correlated to decreasing oil quality (loss of aliphatic hydrocarbons, more biodegraded), which cannot be rejected at 99% confidence. Further magnetic characterization revealed that the high quality, low biodegradation oils from Colombia have a higher magnetic susceptibility (10-3-10-4 m3kg-1) and are dominated by pseudo-single domain grains of magnetite. The lower quality oils i.e., the UK, Canadian and Indonesian samples, displayed decreased magnetic susceptibility (10-5-10-6 m3kg-1) and pseudo-single domain to multidomain grains of magnetite and hematite. Magnetite and pyrrhotite framboidal material were found in all but the Canadian samples. Therefore, with decreasing oil quality there is a progressive

  17. Folate-bearing doxorubicin-loaded magnetic poly(N-isopropylacrylamide) microspheres as a new strategy for cancer therapy.

    Science.gov (United States)

    Sun, Yong; Chen, Libo; Yu, Jerry; Zhi, Xiuling; Tang, Shaoxian; Zhou, Ping; Wang, Changchun

    2009-08-01

    Doxorubicin is a classic anticancer agent. Recently, numerous strategies have been used to enhance efficacy of drug delivery for cancer treatment. For example, by modifying poly(N-isopropylacrylamide) microspheres, a nanocarrier, makes it more effective. Conjugation with folic acid increases specific targeted drug delivery towards folate receptor-bearing cancer cells to improve anticancer effectiveness by increasing the tissue's local concentration of drugs. In the current studies, we synthesized folate-bearing, doxorubicin-loaded, magnetic, poly(N-isopropylacrylamide) microspheres (FDMPM) to treat breast cancer cells (human SKBR-3). We found efficiency of drug encapsulation very high (95%) at pH above 7.4. Reverse transcription-PCR showed that cancer cells highly expressed folate receptors. Confocal laser scanning microscopy and flow cytometry revealed internalization of the carrier by SKBR-3 in treatments with FDMPM, which was not the case with any other combination for drug delivery (MPM, FMPM, and DMPM). Similarly, SKBR-3 cell growth was inhibited more (assessed by methylthiazolyldiphenyl-tetrazolium bromide and trypan blue exclusion assays) when treated with FDMPM than with any other combinations. Current results confirm our predication and demonstrate that FDMPM has potential as a new targeting strategy in cancer therapy.

  18. Active magnetic bearings - a step towards smart rotating machinery

    Energy Technology Data Exchange (ETDEWEB)

    Nordmann, R.; Aenis, M.; Knopf, E.; Strassburger, S. [Darmstadt Univ. of Technology, Darmstadt (Germany)

    2000-07-01

    In the field of rotating machinery the number of applications of rotating systems running in active magnetic bearings (AMB's) is increasing. In comparison to conventional bearings magnetic bearings are a typical mechatronic product consisting of mechanical, electrical and electronic components. Such systems have the ability to pick up changes in its environment by sensors and to react to the system or process by means of actuators after an appropriate information processing carried out in a microprocessor. Nowadays, rotors in active magnetic bearings already offer a variety of advantages compared to conventional systems. Some of them are the tuning possibilities for stiffness and damping, the absence of friction and wear, the high running speeds, the vibration isolation and possible unbalance compensation, However, there is much more potential in such systems with respect to a smart behavior. With the mechatronic structure of a rotating machinery in AMB's consisting of built-in control, sensors, microprocessors, actuators and last but not least built-in software different novel features like identification, diagnosis, prognosis and correction can be realised. In this way it will be possible to design new machines with higher performance, higher reliability and a longer lifetime. This paper particularly describes a Smart Machine Technology for rotating machines with AMB's and concentrates on the mentioned smart features of identification, diagnosis and correction. After a general description of the smart technology followed by a presentation of the necessary development tools three applications will show the usefulness of this new technology. (Author)

  19. Optimization of active magnetic bearings for automotive flywheel energy storage systems based on soft magnetic materials

    Science.gov (United States)

    Recheis, M.; Schweighofer, B.; Fulmek, P.; Wegleiter, H.

    2013-01-01

    For active magnetically suspended rotors in mobile flywheel energy storage systems the lowest possible weight, smallest size and a low price is required. Since the flywheel is operated in vacuum and very little heat can be dissipated from the rotor, the bearing's magnetic losses have to be as minimal as well. This paper compares the design and optimization of homopolar radial active magnetic bearings with 3 different types of laminated steel. The first type is a standard transformer steel, the second one is high flux cobalt steel and the third one is high flux cobalt steel with high tensile strength.

  20. Numerical computation of the restoring force in a cylindrical bearing containing magnetic liquid

    Directory of Open Access Journals (Sweden)

    Greconici Marian

    2008-01-01

    Full Text Available Present paper deals with the second order of magnetic levitation, applied to a cylindrical bearing holding a magnetized shaft and the magnetic liquid The magnetic restoring force acting on the shaft of the cylindrical bearing. was numerically evaluated, the liquid being considered a nonlinear medium.

  1. Digital control of magnetic bearings in a cryogenic cooler

    Science.gov (United States)

    Feeley, J.; Law, A.; Lind, F.

    1990-01-01

    This paper describes the design of a digital control system for control of magnetic bearings used in a spaceborne cryogenic cooler. The cooler was developed by Philips Laboratories for the NASA Goddard Space Flight Center. Six magnetic bearing assemblies are used to levitate the piston, displacer, and counter-balance of the cooler. The piston and displacer are driven by linear motors in accordance with Stirling cycle thermodynamic principles to produce the desired cooling effect. The counter-balance is driven by a third linear motor to cancel motion induced forces that would otherwise be transmitted to the spacecraft. An analog control system is currently used for bearing control. The purpose of this project is to investigate the possibilities for improved performance using digital control. Areas for potential improvement include transient and steady state control characteristics, robustness, reliability, adaptability, alternate control modes, size, weight, and cost. The present control system is targeted for the Intel 80196 microcontroller family. The eventual introduction of application specific integrated circuit (ASIC) technology to this problem may produce a unique and elegant solution both here and in related industrial problems.

  2. Correlating biodegradation to magnetization in oil bearing sedimentary rocks

    Science.gov (United States)

    Emmerton, Stacey; Muxworthy, Adrian R.; Sephton, Mark A.; Aldana, Milagrosa; Costanzo-Alvarez, Vincenzo; Bayona, German; Williams, Wyn

    2013-07-01

    A relationship between hydrocarbons and their magnetic signatures has previously been alluded to but this is the first study to combine extensive geochemical and magnetic data of hydrocarbon-associated samples. We report a detailed study that identifies a connection between magnetic mineralogy and oil biodegradation within oil-bearing sedimentary units from Colombia, Canada Indonesia and the UK. Geochemical data reveal that all the oil samples are derived from mature type-II kerogens deposited in oxygen-poor environments. Biodegradation is evident to some extent in all samples and leads to a decrease in oil quality through the bacterially mediated conversion of aliphatic hydrocarbons to polar constituents. The percentage of oil components and the biodegradation state of the samples were compared to the magnetic susceptibility and magnetic mineralogy. A distinct decrease in magnetic susceptibility is correlated to decreasing oil quality and the amount of extractable organic matter present. Further magnetic characterization revealed that the high quality oils are dominated by pseudo-single domain grains of magnetite and the lower quality oils by larger pseudo-single domain to multidomain grains of magnetite and hematite. Hence, with decreasing oil quality there is a progressive dominance of multidomain magnetite as well as the appearance of hematite. It is concluded that biodegradation is a dual process, firstly, aliphatic hydrocarbons are removed thereby reducing oil quality and secondly, magnetic signatures are both created and destroyed. This complex relationship may explain why controversy has plagued previous attempts to resolve the connection between magnetics and hydrocarbon deposits. These findings reinforce the importance of bacteria within petroleum systems as well as providing a platform for the use of magnetization as a possible exploration tool to identify subsurface reservoirs and a novel proxy of hydrocarbon migration.

  3. TRANSIENT TEMPERATURE FIELD IN ACTIVE THRUST MAGNETIC BEARING

    Institute of Scientific and Technical Information of China (English)

    Sun Shouqun; Geng Haipeng; Guo Keqian

    2005-01-01

    A transient temperature field model in a thrust magnetic bearing is built in which the heat resources come mainly from the eddy-current loss of solid cores and the copper loss of coils. The transient temperature field, system temperature rise and the thermo-equilibrium state during the rotor starting-up are calculated considering only the copper loss and the eddy-current loss. The numerical results indicate that the temperatures in coils and in magnets rise rapidly, their thermo-equilibrium states are formed within a short time. The temperatures in a thrust-disk and in a rotor rise slowly, their thermo-equilibrium states are formed after a long period time. The temperatures of the thrust-disk and the rotor are far higher than the temperatures of coils and/or magnets after the thermo-equilibrium state has come into being.

  4. The design considerations for a superconducting magnetic bearing system

    Science.gov (United States)

    Cansiz, Ahmet; Yildizer, Irfan

    2014-09-01

    In this paper a high temperature superconducting magnetic bearing is studied with various design considerations. The design of the bearing consists of a rotor with 7.5 kg mass. The stable levitation of the rotor is provided with the Evershed type and superconducting components. The dynamic stability of the rotor is strengthened with the electromagnetic and electrodynamic levitation techniques. The force on the rotor is predicted in terms of semi-analytical frozen image model. The designed driving system sustains stable levitation during the rotation of the rotor and achieves higher rotational speed than that of the torque driver. The results indicate that the designed rotor and driving system have potential solutions for the development of the superconducting flywheel energy storage.

  5. Redundant unbalance compensation of an active magnetic bearing system

    Science.gov (United States)

    Hutterer, Markus; Kalteis, Gerald; Schrödl, Manfred

    2017-09-01

    To achieve a good running behavior of a magnetic levitated rotor, a well-developed position controller and different compensation methods are required. Two very important structures in this context are the reduction of the gyroscopic effect and the unbalance vibration. Both structures have in common that they need the angular velocity information for calculation. For industrial applications this information is normally provided by an angle sensor which is fixed on the rotor. The angle information is also necessary for the field oriented control of the electrical drive. The main drawback of external position sensors are the case of a breakdown or an error of the motor controller. Therefore, the magnetic bearing can get unstable, because no angular velocity information is provided. To overcome this problem the presented paper describes the development of a selfsensing unbalance rejection in combination with a selfsensing speed control of the motor controller. Selfsensing means in this context that no angle sensor is required for the unbalance or torque control. With such structures two redundant speed and angle information sources are available and can be used for the magnetic bearing and the motor controller without the usage of an angle sensor.

  6. Failure Mode and Effect Analysis of Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    K.P. Lijesh

    2016-03-01

    Full Text Available In the present research work Failure Mode and Effect Analysis (FMEA of an Active Magnetic Bearing (AMB has been presented. Various possible failures modes of AMBs and the corresponding effects of those failures on performance of AMBs have been identified. The identified failure modes of AMBs will facilitate designer to incorporate necessary design features that would prevent the occurrence of the failure. The severity, occurrence and detection of the failures modes are determined based on a rating scale of 1 to 5 to quantify the Risk Priority Number (RPN of the failure modes. The methods to eliminate or reduce the high-risk-failure modes are proposed.

  7. Rotordynamic Modelling and Response Characteristics of an Active Magnetic Bearing Rotor System

    Science.gov (United States)

    Free, April M.; Flowers, George T.; Trent, Victor S.

    1996-01-01

    Auxiliary bearings are a critical feature of any magnetic bearing system. They protect the soft iron core of the magnetic bearing during an overload or failure. An auxiliary bearing typically consists of a rolling element bearing or bushing with a clearance gap between the rotor and the inner race of the support. The dynamics of such systems can be quite complex. It is desired to develop a rotordynamic model which describes the dynamic behavior of a flexible rotor system with magnetic bearings including auxiliary bearings. The model is based upon an experimental test facility. Some simulation studies are presented to illustrate the behavior of the model. In particular, the effects of introducing sideloading from the magnetic bearing when one coil fails is studied. These results are presented and discussed.

  8. Superconducting magnetic bearings for machine tools. Phase 1, SBIR program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, G.; Bennett, A.; Downer, J.; Hockney, R.

    1988-01-01

    The research was directed toward investigating the role of superconducting materials in a magnetic bearing system. Superconducting magnetic bearings are shown to offer the potential for vastly improved performance. These bearings are expected to be especially applicable to rotors which have extremely tight position tolerances. The development of superconducting magnetic bearing technology is also expected to allow a number of novel approaches in the development of machinery and systems. Researchers studied an alternative bearing design which employs a superconducting coil and eliminates all conventional magnetic structures. The study has resulted in a design definition and detailed analysis for a superconducting bearing system which is sized to roughly duplicate the air bearing system of an existing air-bearing spindle.

  9. Design of a Micro Milling Setup with an Active Magnetic Bearing Spindle

    NARCIS (Netherlands)

    Kimman, M.H.

    2010-01-01

    This thesis describes the design of a micro milling setup with an active magnetic bearing spindle. Micro milling is the mechanical removal of material with sub millimeter tools. An active magnetic bearing typically consists of a set of magnetic actuators, a control loop and position sensors.

  10. Design of a Micro Milling Setup with an Active Magnetic Bearing Spindle

    NARCIS (Netherlands)

    Kimman, M.H.

    2010-01-01

    This thesis describes the design of a micro milling setup with an active magnetic bearing spindle. Micro milling is the mechanical removal of material with sub millimeter tools. An active magnetic bearing typically consists of a set of magnetic actuators, a control loop and position sensors. Activ

  11. Rotational characteristics in the resonance state of the HTSC-permanent magnet hybrid magnetic bearing

    Science.gov (United States)

    Morii, Y.; Sukedai, M.; Ohashi, S.

    2011-11-01

    The hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. In this paper, influence of the hybrid system on the dynamic characteristics of the rotor is studied. The rotational characteristics in the mechanical resonance state are studied, and the equivalent magnetic spring coefficient is estimated from the experimental results of the load weight. The resonance frequency is measured by the rotation experiments. The rotor achieves stable levitation even in the resonance state. In the hybrid system, effect of the pinning force becomes smaller than that of the lateral force generated by the repulsive force between the two permanent magnets at the smaller air gap. Thus influence of the lateral vibration and the gradient angle in the resonance state becomes larger at a smaller air gap. The equivalent magnetic spring coefficient becomes also small, and the resonance frequency becomes small in the hybrid bearing system.

  12. An Air Bearing Rotating Coil Magnetic Measurement System

    CERN Document Server

    Gottschalk, Stephen C; Taylor, David J; Thayer, William

    2005-01-01

    This paper describes a rotating coil magnetic measurement system supported on air bearings. The design is optimized for measurements of 0.1micron magnetic centerline changes on long, small aperture quadrupoles. Graphite impregnated epoxy resin is used for the coil holder and coil winding forms. Coil holder diameter is 11 mm with a length between supports of 750mm. A pair of coils is used to permit quadrupole bucking during centerline measurements. Coil length is 616mm, inner radius 1.82mm, outer radius 4.74mm. The key features of the mechanical system are simplicity; air bearings for accurate, repeatable measurements without needing warm up time and a vibration isolated stand that uses a steel-topped Newport optical table with air suspension. Coil rotation is achieved by a low noise servo motor controlled by a standalone Ethernet servo board running custom servo software. Coil calibration procedures that correct wire placement errors, tests for mechanical resonances, and other system checks will also be discu...

  13. Bear

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The famous physicist made for his scholars this riddle. A fellow encountered a bear in a wasteland. There was nobody else there. Both were frightened and ran away. Fellow to the north, bear to the west. Suddenly the fellow stopped, aimed his gun to the south and shot the bear. What colour was the bear?

  14. Mechanical Characteristics of a Thrust Magnetic Bearing%推力轴承的力学特性

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Static and dynamic mechanical characteristics of a thrustmagnetic bearing are studied owing to the inclination of the runner disk. The application refers to a thrust magnetic bearing for a turbo-expander/compressor. The static tilt of the runner disk has remarkable influence on the mechanical characteristics of thrust magnetic bearing, it can change the static load distribution between two radial magnetic bearings and will exert violent coupling effect among a thrust magnetic bearing and two radial magnetic bearings. Such a finding can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  15. Control of flexible rotor systems with active magnetic bearings

    Science.gov (United States)

    Lei, Shuliang; Palazzolo, Alan

    2008-07-01

    An approach is presented for the analysis and design of magnetic suspension systems with large flexible rotordynamics models including dynamics, control, and simulation. The objective is to formulate and synthesize a large-order, flexible shaft rotordynamics model for a flywheel supported with magnetic bearings. A finite element model of the rotor system is assembled and then employed to develop a magnetic suspension compensator to provide good reliability and disturbance rejection. Stable operation over the complete speed range and optimization of the closed-loop rotordynamic properties are obtained via synthesis of eigenvalue analysis, Campbell plots, waterfall plots, and mode shapes. The large order of the rotor model and high spin speed of the rotor present a challenge for magnetic suspension control. A flywheel system is studied as an example for realizing a physical controller that provides stable rotor suspension and good disturbance rejection in all operating states. The baseline flywheel system control is determined from extensive rotordynamics synthesis and analysis for rotor critical speeds, mode shapes, frequency responses, and time responses.

  16. Improvement of the Levitation Characteristics in the Magnetic Bearing System Using HTSC-Permanent Magnet Hybrid Structure

    Science.gov (United States)

    Ohashi, Shunsuke

    Magnetic bearing using pining force of a permanent magnet and a high-temperature superconductor has been developed. Additional permanent magnet is introduced to increase the levitation force of the magnetic bearing. In this hybrid magnetic bearing system, levitation force is mainly given by the repulsive force of the permanent magnets, and stability for the lateral direction is given by pining force of the superconductor. The experimental device is developed. A ring type superconductor and a bulk one are examined. Levitation characteristics of the hybrid magnetic bearing are measured. A bulk superconductor shows better characteristics both levitation and lateral stability than ring one. Levitation force of the hybrid system becomes about twice as large as that of the no-hybrid one. Although repulsive force of the permanent magnet decreases lateral stability of the system, its influence becomes small by choosing adequate position of the permanent magnets and the superconductor.

  17. Fault diagnosis of active magnetic bearings based on Gaussian GLRT detector

    DEFF Research Database (Denmark)

    Nagel, Leon; Galeazzi, Roberto; Voigt, Andreas Jauernik

    2016-01-01

    Active magnetic bearings are progressively replacing conventional bearings in many industrial applications, particularly in the energy sector. Magnetic bearings have many advantages such as contactless support and clean operation; however their use also poses some challenges connected...... to their inherent open loop instability. Occurrence of faults in one or more components of an active magnetic bearing may lead to loss of control of the rotor. Timely detection and isolation of faults in an active magnetic bearing could prevent hazardous system behaviour by enabling proper reconfiguration...... of the control system. A structural model of the bearing-rotor system is presented and used to perform a detectability and isolability analysis of faults in the magnetic actuator. Structural detectability and group-wise isolability is concluded for single and multiple faults in the actuators. A Gaussian...

  18. Observer-Based Magnetic Bearing Controller Developed for Aerospace Flywheels

    Science.gov (United States)

    Le, Dzu K.; Provenza, Andrew J.

    2002-01-01

    A prototype of a versatile, observer-based magnetic bearing controller for aerospace flywheels was successfully developed and demonstrated on a magnetic bearing test rig (see the photograph) and an actual flywheel module. The objective of this development included a fast, yet low risk, control development process, and a robust, high-performance controller for a large variety of flywheels. This required a good system model, an efficient development procedure, and a model-based controller that addressed the key problems associated with flywheel and bearing imbalance, sensor error, and vibration. The model used in this control development and tuning procedure included the flexible rotor dynamics and motor-induced vibrations. Such a model was essential for low-risk scheduling of speed-dependent control parameters and for reliable evaluation of novel control strategies. The successfully tested control prototype utilized an extended Kalman filter to estimate the true rotor principal-axis motion from the raw sensor position feedback. For control refinement, the extended Kalman filter also estimated and eliminated the combined effects of mass-imbalance and sensor runouts from the input data. A key advantage of the design based on the extended Kalman filter is its ability to accurately estimate both the rotor's principal-axis position and gyroscopic rates with the least amount of phase lag. This is important for control parameter scheduling to dampen the gyroscopic motions. Because of large uncertainties in the magnetic bearing and imbalance characteristics, this state-estimation scheme alone is insufficient for containing the rotor motion within the desired 1-mil excursion radius. A nonlinear gain adjustment based on an estimation of the principal-axis orbit size was needed to provide a coarse (nonoptimal), but robust, control of the orbit growth. Control current minimization was achieved with a (steepest gradient) search of synchronous errors in the principal

  19. Optimization of active magnetic bearings for automotive flywheel energy storage systems based on soft magnetic materials

    Directory of Open Access Journals (Sweden)

    Wegleiter H.

    2013-01-01

    Full Text Available For active magnetically suspended rotors in mobile flywheel energy storage systems the lowest possible weight, smallest size and a low price is required. Since the flywheel is operated in vacuum and very little heat can be dissipated from the rotor, the bearing’s magnetic losses have to be as minimal as well. This paper compares the design and optimization of homopolar radial active magnetic bearings with 3 different types of laminated steel. The first type is a standard transformer steel, the second one is high flux cobalt steel and the third one is high flux cobalt steel with high tensile strength.

  20. Characteristics of motorized spindle supported by active magnetic bearings

    Institute of Scientific and Technical Information of China (English)

    Xie Zhenyu; Yu Kun; Wen Liantang; Wang Xiao; Zhou Hongkai

    2014-01-01

    A motorized spindle supported by active magnetic bearings (AMBs) is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spin-dle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic char-acteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

  1. Characteristics of motorized spindle supported by active magnetic bearings

    Directory of Open Access Journals (Sweden)

    Xie Zhenyu

    2014-12-01

    Full Text Available A motorized spindle supported by active magnetic bearings (AMBs is generally used for ultra-high-speed machining. Iron loss of radial AMB is very great owing to high rotation speed, and it will cause severe thermal deformation. The problem is particularly serious on the occasion of large power application, such as all electric aero-engine. In this study, a prototype motorized spindle supported by five degree-of-freedom AMBs is developed. Homopolar and heteropolar AMBs are independently adopted as radial bearings. The influences of the two types of radial AMBs on the dynamic characteristics of the motorized spindle are comparatively investigated by theoretical analysis, test modal analysis and actual operation of the system. The iron loss of the two types of radial AMBs is analyzed by finite element software and verified through run-down experiments of the system. The results show that the structures of AMB have less influence on the dynamic characteristics of the motorized spindle. However, the homopolar structure can effectively reduce the iron loss of the radial AMB and it is useful for improving the overall performance of the motorized spindle.

  2. Magnetic bearings: A key technology for advanced rocket engines?

    Science.gov (United States)

    Girault, J. PH.

    1992-01-01

    For several years, active magnetic bearings (AMB) have demonstrated their capabilities in many fields, from industrial compressors to control wheel suspension for spacecraft. Despite this broad area, no significant advance has been observed in rocket propulsion turbomachinery, where size, efficiency, and cost are crucial design criteria. To this respect, Societe Europeenne de Propulsion (SEP) had funded for several years significant efforts to delineate the advantages and drawbacks of AMB applied to rocket propulsion systems. Objectives of this work, relative technological basis, and improvements are described and illustrated by advanced turbopump layouts. Profiting from the advantages of compact design in cryogenic environments, the designs show considerable improvements in engine life, performances, and reliability. However, these conclusions should still be tempered by high recurrent costs, mainly due to the space-rated electronics. Development work focused on this point and evolution of electronics show the possibility to decrease production costs by an order of magnitude.

  3. Magnetic Bearing Amplifier Output Power Filters for Flywheel Systems

    Science.gov (United States)

    Lebron-Velilla, Ramon C.; Jansen, Ralph H.; Palazzolo, Alan; Thomas, Erwin; Kascak, Peter E.; Birchenough, Arthur G.; Dever, Timothy P.

    2003-01-01

    Five power filters and two types of power amplifiers were tested for use with active magnetic bearings for flywheel applications. Filter topologies included low pass filters and low pass filters combined with trap filters at the PWM switching frequency. Two state and three state PWM amplifiers were compared. Each system was evaluated based on current magnitude at the switching frequency, voltage magnitude at 500 kHz, and power consumption. The base line system was a two state amplifier without a power filter. The recommended system is a three state power amplifier with a 50 kHz low pass filter and a 27 kHz trap filter. This system uses 5.57 W. It reduces the switching current by an order of magnitude and the 500 kHz voltage by two orders of magnitude. The relative power consumption varied depending on the test condition between 60 to 130 percent of the baseline.

  4. Flywheel Energy Storage System Suspended by Hybrid Magnetic Bearing

    Science.gov (United States)

    Owusu-Ansah, Prince; Hu, Yefa; Misbawu, Adam

    This work presents a prototype flywheel energy storage system (FESS) suspended by hybrid magnetic bearing (HMB) rotating at a speed of 20000rpm with a maximum storage power capacity of 30W with a maximum tip speed of 300m/s. The design presented is an improvement of most existing FESS, as the design incorporates a unique feature in that the upper and the lower rotor and stator core are tapered which enhances larger thrust and much lower radial force to be exerted on the system. Without any adverse effect being experienced by the model. The work also focuses on the description of developing a prototype FESS suspended by HMB using solid works as a basis of developing in the nearer future a more improved FESS suspended by HMB capable of injecting the ever increasing high energy demand situation in the 21st century and beyond.

  5. Development of superconducting magnetic bearing for flywheel energy storage system

    Science.gov (United States)

    Miyazaki, Yoshiki; Mizuno, Katsutoshi; Yamashita, Tomohisa; Ogata, Masafumi; Hasegawa, Hitoshi; Nagashima, Ken; Mukoyama, Shinichi; Matsuoka, Taro; Nakao, Kengo; Horiuch, Shinichi; Maeda, Tadakazu; Shimizu, Hideki

    2016-12-01

    We have been developing a superconducting magnetic bearing (SMB) that has high temperature superconducting (HTS) coils and bulks for a flywheel energy storage system (FESS) that have an output capability of 300 kW and a storage capacity of 100 kW h (Nagashima et al., 2008, Hasegawa et al., 2015) [1,2]. The world largest-class FESS with a SMB has been completed and test operation has started. A CFRP flywheel rotor that had a diameter of 2 m and weight of 4000 kg had a capability to be rotated at a maximum speed of 6000 min-1. The SMB using superconducting material both for its rotor and stator is capable of supporting the flywheel that had the heavy weight and the high seed rotation mentioned above. This paper describes the design of the SMB and results of the cooling test of the SMB.

  6. Comb-like amphiphilic copolymers bearing acetal-functionalized backbones with the ability of acid-triggered hydrophobic-to-hydrophilic transition as effective nanocarriers for intracellular release of curcumin.

    Science.gov (United States)

    Zhao, Junqiang; Wang, Haiyang; Liu, Jinjian; Deng, Liandong; Liu, Jianfeng; Dong, Anjie; Zhang, Jianhua

    2013-11-11

    The pH-responsive micelles have enormous potential as nanosized drug carriers for cancer therapy due to their physicochemical changes in response to the tumor intracellular acidic microenvironment. Herein, a series of comb-like amphiphilic copolymers bearing acetal-functionalized backbone were developed based on poly[(2,4,6-trimethoxybenzylidene-1,1,1-tris(hydroxymethyl) ethane methacrylate-co-poly(ethylene glycol) methyl ether methacrylate] [P(TTMA-co-mPEGMA)] as effective nanocarriers for intracellular curcumin (CUR) release. P(TTMA-co-mPEGMA) copolymers with different hydrophobic-hydrophilic ratios were prepared by one-step reversible addition fragmentation chain transfer (RAFT) copolymerization of TTMA and mPEGMA. Their molecular structures and chemical compositions were confirmed by (1)H NMR, Fourier transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). P(TTMA-co-mPEGMA) copolymers could self-assemble into nanosized micelles in aqueous solution and displayed low critical micelle concentration (CMC). All P(TTMA-co-mPEGMA) micelles displayed excellent drug loading capacity, due to the strong π-π conjugate action and hydrophobic interaction between the PTTMA and CUR. Moreover, the hydrophobic PTTMA chain could be selectively hydrolyzed into a hydrophilic backbone in the mildly acidic environment, leading to significant swelling and final disassembly of the micelles. These morphological changes of P(TTMA-co-mPEGMA) micelles with time at pH 5.0 were determined by DLS and TEM. The in vitro CUR release from the micelles exhibited a pH-dependent behavior. The release rate of CUR was significantly accelerated at mildly acidic pH of 4.0 and 5.0 compared to that at pH 7.4. Toxicity test revealed that the P(TTMA-co-mPEGMA) copolymers exhibited low cytotoxicity, whereas the CUR-loaded micelles maintained high cytotoxicity for HepG-2 and EC-109 cells. The results indicated that the novel P(TTMA-co-mPEGMA) micelles with low CMC, small and tunable

  7. Computational Analysis of Static and Dynamic Behaviour of Magnetic Suspensions and Magnetic Bearings

    Science.gov (United States)

    Britcher, Colin P. (Editor); Groom, Nelson J.

    1996-01-01

    Static modelling of magnetic bearings is often carried out using magnetic circuit theory. This theory cannot easily include nonlinear effects such as magnetic saturation or the fringing of flux in air-gaps. Modern computational tools are able to accurately model complex magnetic bearing geometries, provided some care is exercised. In magnetic suspension applications, the magnetic fields are highly three-dimensional and require computational tools for the solution of most problems of interest. The dynamics of a magnetic bearing or magnetic suspension system can be strongly affected by eddy currents. Eddy currents are present whenever a time-varying magnetic flux penetrates a conducting medium. The direction of flow of the eddy current is such as to reduce the rate-of-change of flux. Analytic solutions for eddy currents are available for some simplified geometries, but complex geometries must be solved by computation. It is only in recent years that such computations have been considered truly practical. At NASA Langley Research Center, state-of-the-art finite-element computer codes, 'OPERA', 'TOSCA' and 'ELEKTRA' have recently been installed and applied to the magnetostatic and eddy current problems. This paper reviews results of theoretical analyses which suggest general forms of mathematical models for eddy currents, together with computational results. A simplified circuit-based eddy current model proposed appears to predict the observed trends in the case of large eddy current circuits in conducting non-magnetic material. A much more difficult case is seen to be that of eddy currents in magnetic material, or in non-magnetic material at higher frequencies, due to the lower skin depths. Even here, the dissipative behavior has been shown to yield at least somewhat to linear modelling. Magnetostatic and eddy current computations have been carried out relating to the Annular Suspension and Pointing System, a prototype for a space payload pointing and vibration

  8. The role of superconductivity in magnetic bearings for high-load applications

    Science.gov (United States)

    Downer, James; Eisenhaure, David

    1993-01-01

    Slewing of large payloads will require control torque and angular momentum storage capacities that are large in comparison to the capabilities of available control moment gyros (CMG's). SatCon Technology Corporation is currently designing a CMG which may be employed as a slew actuator for large spacecraft or other payloads. The slew actuator employs a type of magnetic bearing which may be used in high load applications. The magnetic bearing is also used to fully gimbal the suspended rotor of the slew actuator. The use of magnetic bearings in angular momentum exchange actuators has the primary advantage that physical contact between the rotor and stator is eliminated. This leads to greatly extended life, increased reliability, and reduced vibrations. Several actuators operating on magnetic bearings have been demonstrated in previous research efforts. These were sized for use in small satellites. For conventional magnetic bearings, which employ magnetic cores, high torsional loading may require that the magnetic structure be excessively massive. An alternative magnetic bearing design which employs a superconducting coil and eliminates conventional magnetic structures is discussed. The baseline approach is to replace the field coil of a conventional magnetic bearing with the superconducting coil.

  9. Overview of magnetic bearing control and linearization approaches for annular magnetically suspended devices

    Science.gov (United States)

    Groom, N. J.

    1984-01-01

    An overview of magnetic bearing control and linearization approaches which have been considered for annular magnetically suspended devices is presented. These devices include the Annular Momentum Control Device and the Annular Suspension and Pointing System. Two approaches were investigated for controlling the magnetic actuator. One approach involves controlling the upper and lower electromagnets differentially about a bias flux. The bias flux can either be supplied by permanent magnets in the magnetic circuit or by bias currents. In the other approach, either the upper electromagnet or the lower electromagnet is controlled depending on the direction of force required. One advantage of the bias flux is that for small gap perturbations about a fixed operating point, the force-current characteristic is linear. Linearization approaches investigated for individual element control include an analog solution of the nonlinear electromagnet force equation and a microprocessor-based table lookup method.

  10. Control of Active Axial Magnetic Bearings for Flywheel-based Energy Storage System

    OpenAIRE

    Morís Gómez, Juan

    2014-01-01

    This thesis deals with the design and implementation of the control system for a Flywheel-based Energy Storage System (FESS) with active magnetic bearings. The thesis focuses on the construction of realistic model of the system according to experimental tests. The simulation model will be used to control the thrust magnetic bearings in order to withstand the flywheel in levitation.

  11. Analysis and experiment of eddy current loss in Homopolar magnetic bearings with laminated rotor cores

    Science.gov (United States)

    Jinji, Sun; Dong, Chen

    2013-08-01

    This paper analyses the eddy current loss in Homopolar magnetic bearings with laminated rotor cores produced by the high speed rotation in order to reduce the power loss for the aerospace applications. The analytical model of rotational power loss is proposed in Homopolar magnetic bearings with laminated rotor cores considering the magnetic circuit difference between Homopolar and Heteropolar magnetic bearings. Therefore, the eddy current power loss can be calculated accurately using the analytical model by magnetic field solutions according to the distribution of magnetic fields around the pole surface and boundary conditions at the surface of the rotor cores. The measurement method of rotational power loss in Homopolar magnetic bearing is proposed, and the results of the theoretical analysis are verified by experiments in the prototype MSCMG. The experimental results show the correctness of calculation results.

  12. Demonstration, Testing and Qualification of a High Temperature, High Speed Magnetic Thrust Bearing

    Science.gov (United States)

    DeWitt, Kenneth

    2005-01-01

    The gas turbine industry has a continued interest in improving engine performance and reducing net operating and maintenance costs. These goals are being realized because of advancements in aeroelasticity, materials, and computational tools such as CFD and engine simulations. These advancements aid in increasing engine thrust-to-weight ratios, specific fuel consumption, pressure ratios, and overall reliability through higher speed, higher temperature, and more efficient engine operation. Currently, rolling element bearing and squeeze film dampers are used to support rotors in gas turbine engines. Present ball bearing configurations are limited in speed (bearings require extensive preventative maintenance in order to assure their safe operation. Since these bearings are at their operational limits, new technologies must be found in order to take advantage of other advances. Magnetic bearings are well suited to operate at extreme temperatures and higher rotational speeds and are a promising solution to the problems that conventional rolling element bearings present. Magnetic bearing technology is being developed worldwide and is considered an enabling technology for new engine designs. Using magnetic bearings, turbine and compressor spools can be radically redesigned to be significantly larger and stiffer with better damping and higher rotational speeds. These advances, a direct result of magnetic bearing technology, will allow significant increases in engine power and efficiency. Also, magnetic bearings allow for real-time, in-situ health monitoring of the system, lower maintenance costs and down time.

  13. Design analysis and performance assessment of hybrid magnetic bearings for a rotary centrifugal blood pump.

    Science.gov (United States)

    Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F

    2009-01-01

    A hybrid magnetic bearing system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact bearings to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic bearing system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust bearing. The control position is continuously adjusted based on the electrical energy in the bearing coils, and thus passive magnetic forces carry static thrust loads to minimize the bearing current. Performance of the magnetic bearing system with associated control algorithm was evaluated at different operating conditions. The bearing current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The bearing parameters predicted by the analysis were validated by the experimental data.

  14. Performance of a continuous flow ventricular assist device: magnetic bearing design, construction, and testing.

    Science.gov (United States)

    Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D

    1998-06-01

    A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.

  15. Linear-Quadratic-Gaussian Regulator Developed for a Magnetic Bearing

    Science.gov (United States)

    Choi, Benjamin B.

    2002-01-01

    Linear-Quadratic-Gaussian (LQG) control is a modern state-space technique for designing optimal dynamic regulators. It enables us to trade off regulation performance and control effort, and to take into account process and measurement noise. The Structural Mechanics and Dynamics Branch at the NASA Glenn Research Center has developed an LQG control for a fault-tolerant magnetic bearing suspension rig to optimize system performance and to reduce the sensor and processing noise. The LQG regulator consists of an optimal state-feedback gain and a Kalman state estimator. The first design step is to seek a state-feedback law that minimizes the cost function of regulation performance, which is measured by a quadratic performance criterion with user-specified weighting matrices, and to define the tradeoff between regulation performance and control effort. The next design step is to derive a state estimator using a Kalman filter because the optimal state feedback cannot be implemented without full state measurement. Since the Kalman filter is an optimal estimator when dealing with Gaussian white noise, it minimizes the asymptotic covariance of the estimation error.

  16. Superconductor-Magnet Bearings With Inherent Stability and Velocity-Independent Drag Torque

    Science.gov (United States)

    Lee, Eun-Jeong; Ma, Ki Bui; Wilson, Thomas L.; Chu, Wei-Kan

    1999-01-01

    A hybrid superconductor magnet bearing system has been developed based on passive magnetic levitation and the flux pinning effect of high-temperature superconductivity. The rationale lies in the unique capability of a high-temperature superconductor (HTS) to enhance system stability passively without power consumption. Characterization experiments have been conducted to understand its dynamic behavior and to estimate the required motor torque for its driving system design. These experiments show that the hybrid HTS-magnet bearing system has a periodic oscillation of drag torque due mainly to the nonuniform magnetic field density of permanent magnets. Furthermore, such a system also suffers from a small superimposed periodic oscillation introduced by the use of multiple HTS disks rather than a uniform annulus of HTS material. The magnitude of drag torque is velocity independent and very small. These results make this bearing system appealing for high-speed application. Finally, design guidelines for superconducting bearing systems are suggested based on these experimental results.

  17. Further Development of an Optimal Design Approach Applied to Axial Magnetic Bearings

    Science.gov (United States)

    Bloodgood, V. Dale, Jr.; Groom, Nelson J.; Britcher, Colin P.

    2000-01-01

    Classical design methods involved in magnetic bearings and magnetic suspension systems have always had their limitations. Because of this, the overall effectiveness of a design has always relied heavily on the skill and experience of the individual designer. This paper combines two approaches that have been developed to aid the accuracy and efficiency of magnetostatic design. The first approach integrates classical magnetic circuit theory with modern optimization theory to increase design efficiency. The second approach uses loss factors to increase the accuracy of classical magnetic circuit theory. As an example, an axial magnetic thrust bearing is designed for minimum power.

  18. Conical Magnetic Bearings Developed for Active Stall Control in Gas Turbine Engines

    Science.gov (United States)

    Trudell, Jeffrey J.; Kascak, Albert F.; Provenza, Andrew J.; Buccieri, Carl J.

    2004-01-01

    Active stall control is a current research area at the NASA Glenn Research Center that offers a great benefit in specific fuel consumption by allowing the gas turbine to operate beyond the onset of stall. Magnetic bearings are being investigated as a new method to perform active stall control. This enabling global aviation safety technology would result in improved fuel efficiency and decreased carbon dioxide emissions, as well as improve safety and reliability by eliminating oil-related delays and failures of engine components, which account for 40 percent of the commercial aircraft departure delays. Active stall control works by perturbing the flow in front of the compressor stage such that it cancels the pressure wave, which causes the compressor to go into stall. Radial magnetic bearings are able to whirl the shaft so that variations in blade tip leakage would flow upstream causing a perturbation wave that could cancel the rotating stall cell. Axial or thrust magnetic bearings cannot be used to cancel the surge mode in the compressor because they have a very low bandwidth and thus cannot modulate at a high enough frequency. Frequency response is limited because the thrust runner cannot be laminated. To improve the bandwidth of magnetic thrust bearings, researchers must use laminations to suppress the eddy currents. A conical magnetic bearing can be laminated, resulting in increased bandwidth in the axial direction. In addition, this design can produce both radial and thrust force in a single bearing, simplifying the installation. The proposed solution combines the radial and thrust bearing into one design that can be laminated--a conical magnetic bearing. The new conical magnetic bearing test rig, funded by a Glenn fiscal year 2002 Director's Discretionary Fund, was needed because none of the existing rigs has an axial degree of freedom. The rotor bearing configuration will simulate that of the main shaft on a gas turbine engine. One conical magnetic bearing

  19. Integration of magnetic bearings in the design of advanced gas turbine engines

    Science.gov (United States)

    Storace, Albert F.; Sood, Devendra K.; Lyons, James P.; Preston, Mark A.

    1994-01-01

    Active magnetic bearings provide revolutionary advantages for gas turbine engine rotor support. These advantages include tremendously improved vibration and stability characteristics, reduced power loss, improved reliability, fault-tolerance, and greatly extended bearing service life. The marriage of these advantages with innovative structural network design and advanced materials utilization will permit major increases in thrust to weight performance and structural efficiency for future gas turbine engines. However, obtaining the maximum payoff requires two key ingredients. The first key ingredient is the use of modern magnetic bearing technologies such as innovative digital control techniques, high-density power electronics, high-density magnetic actuators, fault-tolerant system architecture, and electronic (sensorless) position estimation. This paper describes these technologies. The second key ingredient is to go beyond the simple replacement of rolling element bearings with magnetic bearings by incorporating magnetic bearings as an integral part of the overall engine design. This is analogous to the proper approach to designing with composites, whereby the designer tailors the geometry and load carrying function of the structural system or component for the composite instead of simply substituting composites in a design originally intended for metal material. This paper describes methodologies for the design integration of magnetic bearings in gas turbine engines.

  20. Development and evaluation of magnetic microemulsion: tool for targeted delivery of camptothecin to BALB/c mice-bearing breast cancer.

    Science.gov (United States)

    Natesan, Subramanian; Sugumaran, Abimanyu; Ponnusamy, Chandrasekar; Jeevanesan, Vinoth; Girija, Gangarani; Palanichamy, Rajaguru

    2014-12-01

    Development and evaluation of camptothecin-loaded-microemulsion (ME) and -magnetic microemulsion (MME) for passive/active-targeted delivery to BALB/c mice-bearing breast cancer. Based on the pseudo-ternary phase diagrams camptothecin-loaded-MEs and -MMEs were developed using benzyl alcohol:Captex 300 (3:1), TPGS:Tween 80 (2:1) and water. Furthermore, characterized for their droplet size distribution, magnetic susceptibility and effect of droplet size in plasma and evaluated for in vitro and in vivo targeting potential, drug release, haemolytic potential, cytotoxicity, genotoxicity, in vivo biodistribution and lactone ring stability. Drug-loaded MEs showed uniform droplet distribution, extended drug release (76.07 ± 4.30% at 24 h), acceptable level of haemolytic activity (magnetic field. In vivo biodistribution study documented the active targeting of 5067.56 ± 354.72 ng/gm and passive targeting of 1677.58 ± 134.20 ng/gm camptothecin to breast cancer from MME and ME, respectively. Lactone stability study shows around 80% of the lactone stable at 24 h. Developed ME and MME may act as a promising nanocarrier for efficient targeting of breast cancer tissues.

  1. PRINCIPLES AND PARAMETER DESIGN FOR AC-DC THREE-DEGREE FREEDOM HYBRID MAGNETIC BEARINGS

    Institute of Scientific and Technical Information of China (English)

    ZHU Huangqiu; XIE Zhiyi; ZHU Dehong

    2006-01-01

    To simplify the mechanical structure, decrease the overall system size of the 3-degree freedom axial-radial magnetic bearings and reduce the manufacturing costs as well as operating costs,an innovated AC-DC 3-degree freedom hybrid magnetic bearing is proposed, which is driven by a DC amplifier in axial direction and a 3-phase power converter in radial directions respectively, and the axial and radial bias magnetic fluxes are provided with a common radial polarized permanent magnet ring. The principle producing magnetic suspension forces is introduced. By using equivalent magnetic circuit method, the calculation formulas of magnetic suspension forces and the mathematics models of the system are deduced. Nonlinearities of suspension forces and cross coupling between different degree freedoms are studied further by calculating the suspension forces at different displacements and control currents to validate the feasibility of the mathematics model. Then based on the mathematics models of the bearing, a control method of this novel bearing is designed. Lastly, the methods on parameter design and calculations of the bearing are presented, and an applicable prototype is simulated to analyze the magnetic path by using finite element analysis. The theory analysis and simulation results have shown that this magnetic bearing incorporates the merits of 3-phase AC drive, permanent magnet flux biased and axial-radial combined control, and reduces overall system size and has higher efficiency and lower cost. This innovated magnetic bearing has a wide application in super-speed and super-precision numerical control machine tools, bearingless motors, high-speed flywheels, satellites, etc.

  2. A novel permanent magnetic bearing and its anti-wear effect in impeller total artificial heart

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel permanent magnetic bearing has been developed, which consists of two magnetic rings with different dimensions in the same direction of axial magnetization, located concentrically. Because of the effect of magnetic field, the magnetic rings keep a distance axially from each other. If the distance between the two rings changes, a rehabilitation force is produced to return to the original position. When this distance decreases, a repelling force will be generated; its component in axial direction can be used as a magnetic spring and its radial component can function as a bearing. With this novel permanent magnetic bearing, an impeller total artificial heart (TAH) is designed, manufactured and tested. The rotation is driven radially. On the left and right sides of the rotor magnets, two small magnetic rings are fixed onto the rotor, coupling with two big magnetic rings on both sides of the motor coil, to form the magnetic bearings. Hereby the bearings are used for wear reduction rather than rotor levitation. That means the magnetic bearings counteract the attractive force between the motor coil iron and rotor magnets so as to reduce the friction between the motor stator and rotor. At the left and right ends of the rotor, two impellers with the same width but different diameters are mounted. Thus the device has only one moving part-rotor; both the left pump and the right pump eject the blood synchronically; the volume equilibrium of both pumps can be achieved automatically without need of control. The device weighing 250 g has a length of 60 mm and a diameter of 40 mm at its largest point, and can produce a blood flow up to 150 mm Hg and 6 L/min from left pump, 50 mm Hg and 6 L/min from right pump, at rotating speed of 4000 r/min of the motor. The consumed power is under 10 W.

  3. Design, Modeling and Control of Magnetic Bearings for a Ring-Type Flywheel Energy Storage System

    Directory of Open Access Journals (Sweden)

    Chow-Shing Toh

    2016-12-01

    Full Text Available This study is concerned with the magnetic force models of magnetic bearing in a flywheel energy storage system (FESS. The magnetic bearing is of hybrid type, with axial passive magnetic bearing (PMB and radial hybrid magnetic bearing (HMB. For the PMB, a pair of ring-type Halbach arrays of permanent magnets are arranged vertically to support the rotor weight. For the HMB, a set of ring-type Halbach array is placed on the rotor side, which corresponds to coil sets on the stator side. The HMB can produce both attraction and repulsion forces on the radial direction, depending on the direction of the coil currents. It is found that the ring-type configuration and the differential winding scheme for coil sets can yield linear magnetic force models for both PMB and HMB. Based on the obtained magnetic force model, an integral sliding mode controller is designed for the stable rotor levitation in the radial direction. The experimental results show that the rotor can be stabilized to the bearing center, verifying the accuracy of the magnetic force models and effectiveness of the levitation controller.

  4. Method for obtaining large levitation pressure in superconducting magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    1996-01-01

    A method and apparatus for compressing magnetic flux to achieve high levitation pressures. Magnetic flux produced by a magnetic flux source travels through a gap between two high temperature superconducting material structures. The gap has a varying cross-sectional area to compress the magnetic flux, providing an increased magnetic field and correspondingly increased levitation force in the gap.

  5. Method for obtaining large levitation pressure in superconducting magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    1997-01-01

    A method and apparatus for compressing magnetic flux to achieve high levitation pressures. Magnetic flux produced by a magnetic flux source travels through a gap between two high temperature superconducting material structures. The gap has a varying cross-sectional area to compress the magnetic flux, providing an increased magnetic field and correspondingly increased levitation force in the gap.

  6. A Novel Integrated Structure with a Radial Displacement Sensor and a Permanent Magnet Biased Radial Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    Jinji Sun

    2014-01-01

    Full Text Available In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

  7. A novel integrated structure with a radial displacement sensor and a permanent magnet biased radial magnetic bearing.

    Science.gov (United States)

    Sun, Jinji; Zhang, Yin

    2014-01-24

    In this paper, a novel integrated structure is proposed in order to reduce the axial length of the high speed of a magnetically suspended motor (HSMSM) to ensure the maximum speed, which combines radial displacement sensor probes and the permanent magnet biased radial magnetic bearing in HSMSM. The sensor probes are integrated in the magnetic bearing, and the sensor preamplifiers are placed in the control system of the HSMSM, separate from the sensor probes. The proposed integrated structure can save space in HSMSMs, improve the working frequency, reduce the influence of temperature on the sensor circuit, and improve the stability of HSMSMs.

  8. Femur rotation and patellofemoral joint kinematics: a weight-bearing magnetic resonance imaging analysis

    National Research Council Canada - National Science Library

    Souza, Richard B; Draper, Christie E; Fredericson, Michael; Powers, Christopher M

    2010-01-01

    ...) and pain-free controls using weight-bearing kinematic magnetic resonance imaging. Recently, it has been recognized that patellofemoral malalignment may be the result of femoral motion as opposed to patella motion...

  9. Development of an Anti-Vibration Controller for Magnetic Bearing Cooling Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal outlines a program to develop a vibration-free reverse-Brayton cycle cooling system using specially-tuned magnetic bearings. Such a system is critical...

  10. Experimental measurement and calculation of losses in planar radial magnetic bearings

    Science.gov (United States)

    Kasarda, M. E. F.; Allaire, P. E.; Hope, R. W.; Humphris, R. R.

    1994-05-01

    The loss mechanisms associated with magnetic bearings have yet to be adequately characterized or modeled analytically and thus pose a problem for the designer of magnetic bearings. This problem is particularly important for aerospace applications where low power consumption of components is critical. Also, losses are expected to be large for high speed operation. The iron losses in magnetic bearings can be divided into eddy current losses and hysteresis losses. While theoretical models for these losses exist for transformer and electric motor applications, they have not been verified for magnetic bearings. This paper presents the results from a low speed experimental test rig and compares them to calculated values from existing theory. Experimental data was taken over a range of 90 to 2,800 rpm for several bias currents and two different pole configurations. With certain assumptions agreement between measured and calculated power losses was within 16 percent for a number of test configurations.

  11. Electromechanical simulation and test of rotating systems with magnetic bearing or piezoelectric actuator active vibration control

    Science.gov (United States)

    Palazzolo, Alan B.; Tang, Punan; Kim, Chaesil; Manchala, Daniel; Barrett, Tim; Kascak, Albert F.; Brown, Gerald; Montague, Gerald; Dirusso, Eliseo; Klusman, Steve

    1994-01-01

    This paper contains a summary of the experience of the authors in the field of electromechanical modeling for rotating machinery - active vibration control. Piezoelectric and magnetic bearing actuator based control are discussed.

  12. High-Temperature Magnetic Bearings Being Developed for Gas Turbine Engines

    Science.gov (United States)

    Kascak, Albert F.

    1998-01-01

    Magnetic bearings are the subject of a new NASA Lewis Research Center and U.S. Army thrust with significant industry participation, and cooperation with other Government agencies. The NASA/Army emphasis is on high-temperature applications for future gas turbine engines. Magnetic bearings could increase the reliability and reduce the weight of these engines by eliminating the lubrication system. They could also increase the DN (diameter of bearing times the rpm) limit on engine speed and allow active vibration cancellation systems to be used, resulting in a more efficient, "more electric" engine. Finally, the Integrated High Performance Turbine Engine Technology (IHPTET) program, a joint Department of Defense/industry program, identified a need for a high-temperature (1200 F) magnetic bearing that could be demonstrated in their Phase III engine. This magnetic bearing is similar to an electric motor. It has a laminated rotor and stator made of cobalt steel. Wound around the stator's circumference are a series of electrical wire coils which form a series of electric magnets that exert a force on the rotor. A probe senses the position of the rotor, and a feedback controller keeps it centered in the cavity. The engine rotor, bearings, and casing form a flexible structure with many modes. The bearing feedback controller, which could cause some of these modes to become unstable, could be adapted to varying flight conditions to minimize seal clearances and monitor the health of the system.

  13. Synthesis and coating of cobalt ferrite nanoparticles: a first step toward the obtainment of new magnetic nanocarriers.

    Science.gov (United States)

    Baldi, Giovanni; Bonacchi, Daniele; Franchini, Mauro Comes; Gentili, Denis; Lorenzi, Giada; Ricci, Alfredo; Ravagli, Costanza

    2007-03-27

    Monodisperse and stable cobalt ferrite (CoFe2O4) nanoparticles (5.4 nm) have been produced, coated with mono- and difunctional phosphonic and hydroxamic acids, and fully characterized (using thermogravimetric analysis (TGA), dynamic light scattering (DLS), IR spectroscopy, transmission electron microscopy (TEM), and superconducting quantum interference device (SQUID) measurements). Cobalt leakage of the coated nanoparticles has been also studied. Magnetic measurements show the possible applications in hyperthermia at low frequencies, and for this reason, water-soluble coated CoFe2O4 can be seen as a first step toward the obtainment of novel systems for biomagnetic applications.

  14. Design and Application of a Collocated Capacitance Sensor for Magnetic Bearing Spindle

    Science.gov (United States)

    Shin, Dongwon; Liu, Seon-Jung; Kim, Jongwon

    1996-01-01

    This paper presents a collocated capacitance sensor for magnetic bearings. The main feature of the sensor is that it is made of a specific compact printed circuit board (PCB). The signal processing unit has been also developed. The results of the experimental performance evaluation on the sensitivity, resolution and frequency response of the sensor are presented. Finally, an application example of the sensor to the active control of a magnetic bearing is described.

  15. A new conveyor system based on a passive magnetic levitation unit having repulsive-type magnetic bearings

    Science.gov (United States)

    Ohji, T.; Ichiyama, S.; Amei, K.; Sakui, M.; Yamada, S.

    2004-05-01

    A magnetic repulsive-type conveyor system is proposed as a new application of repulsive-type magnetic bearings, which use repulsive forces between the stator and rotor permanent magnets. The proposed conveyer is composed by aligning many passive magnetic levitation units. Each unit also contains electromagnets to oscillate a levitator shaft in the radial direction. The way of generating vibration and rotation in the conveyance direction was examined by the various excitation methods.

  16. Experimental validation of field cooling simulations for linear superconducting magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Dias, D H N; Motta, E S; Sotelo, G G; De Andrade Jr, R, E-mail: ddias@coe.ufrj.b [Laboratorio de aplicacao de Supercondutores (LASUP), Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil)

    2010-07-15

    For practical stability of a superconducting magnetic bearing the refrigeration process must occur with the superconductor in the presence of the magnetic field (a field cooling (FC) process). This paper presents an experimental validation of a method for simulating this system in the FC case. Measured and simulated results for a vertical force between a high temperature superconductor and a permanent magnet rail are compared. The main purpose of this work is to consolidate a simulation tool that can help in future projects on superconducting magnetic bearings for MagLev vehicles.

  17. Development of superconducting magnetic bearing with superconducting coil and bulk superconductor for flywheel energy storage system

    Science.gov (United States)

    Arai, Y.; Seino, H.; Yoshizawa, K.; Nagashima, K.

    2013-11-01

    We have been developing superconducting magnetic bearing for flywheel energy storage system to be applied to the railway system. The bearing consists of a superconducting coil as a stator and bulk superconductors as a rotor. A flywheel disk connected to the bulk superconductors is suspended contactless by superconducting magnetic bearings (SMBs). We have manufactured a small scale device equipped with the SMB. The flywheel was rotated contactless over 2000 rpm which was a frequency between its rigid body mode and elastic mode. The feasibility of this SMB structure was demonstrated.

  18. Concepts of flywheels for energy storage using autostable high-T(sub c) superconducting magnetic bearings

    Science.gov (United States)

    Bornemann, Hans J.; Zabka, R.; Boegler, P.; Urban, C.; Rietschel, H.

    1994-01-01

    A flywheel for energy storage using autostable high-T(sub c) superconducting magnetic bearings has been built. The rotating disk has a total weight of 2.8 kg. The maximum speed is 9240 rpm. A process that allows accelerated, reliable and reproducible production of melt-textured superconducting material used for the bearings has been developed. In order to define optimum configurations for radial and axial bearings, interaction forces in three dimensions and vertical and horizontal stiffness have been measured between superconductors and permanent magnets in different geometries and various shapes. Static as well as dynamic measurements have been performed. Results are being reported and compared to theoretical models.

  19. Robust stabilization of rotor-active magnetic bearing systems

    Science.gov (United States)

    Li, Guoxin

    Active magnetic bearings (AMBs) are emerging as a beneficial technology for high-speed and high-performance suspensions in rotating machinery applications. A fundamental feedback control problem is robust stabilization in the presence of uncertain destabilizing mechanisms in aeroelastic, hydroelastic dynamics, and AMB feedback. As rotating machines are evolving in achieving high speed, high energy density, and high performance, the rotor and the support structure become increasingly flexible, and highly coupled. This makes rotor-AMB system more challenging to stabilize. The primary objective of this research is to develop a systematic control synthesis procedure for achieving highly robust stabilization of rotor-AMB systems. Of special interest is the stabilization of multivariable systems such as the AMB supported flexible rotors and gyroscopic rotors, where the classical control design may encounter difficulties. To this end, we first developed a systematic modeling procedure. This modeling procedure exploited the best advantages of technology developed in rotordynamics and the unique system identification tool provided by the AMBs. A systematic uncertainty model for rotor-AMB systems was developed, eliminating the iterative process of selecting uncertainty structures. The consequences of overestimation or underestimation of uncertainties were made transparent to control engineers. To achieve high robustness, we explored the fundamental performance/robustness limitations due to rotor-AMB system unstable poles. We examined the mixed sensitivity performance that is closely related to the unstructured uncertainty. To enhance transparency of the synthesis, we analyzed multivariable controllers from classical control perspectives. Based on these results, a systematic robust control synthesis procedure was established. For a strong gyroscopic rotor over a wide speed range, we applied the advanced gain-scheduled synthesis, and compared two synthesis frameworks in

  20. Control of Surge in Centrifugal Compressors by Active Magnetic Bearings Theory and Implementation

    CERN Document Server

    Yoon, Se Young; Allaire, Paul E

    2013-01-01

    Control of Surge in Centrifugal Compressors by Active Magnetic Bearings sets out the fundamentals of integrating the active magnetic bearing (AMB) rotor suspension technology in compressor systems, and describes how this relatively new bearing technology can be employed in the active control of compressor surge. The authors provide a self-contained and comprehensive review of rotordynamics and the fundamentals of the AMB technology. The active stabilization of compressor surge employing AMBs in a machine is fully explored, from the modeling of the instability and the design of feedback controllers, to the implementation and experimental testing of the control algorithms in a specially-constructed, industrial-size centrifugal compression system. The results of these tests demonstrate the great potential of the new surge control method developed in this text. This book will be useful for engineers in industries that involve turbocompressors and magnetic bearings, as well as for researchers and graduate students...

  1. Optimum Design and Analysis of Axial Hybrid Magnetic Bearings Using Multi-Objective Genetic Algorithms

    Science.gov (United States)

    Rao, J. S.; Tiwari, R.

    2012-01-01

    Design optimization of axial hybrid magnetic thrust bearings (with bias magnets) was carried out using multi-objective evolutionary algorithms (MOEAs) and compared with the case of electromagnetic bearings (without bias magnets). Mathematical models of objective functions and associated constraints are presented and discussed. The different aspects of implemented MOEA are discussed. It is observed that the size of the bearing with bias magnets is considerably reduced as compared to the case of those without bias magnets, with the objective function as the minimization of weight for the same operating conditions. Similarly, current densities aret reduced drastically with biased magnets when the objective function is chosen as the minimization of the power loss. For illustration of various performances of the bearing, a typical design has been chosen from the final optimized population by an "a posteriori" approach. Sensitivities for both the objective functions with respect to the outer radius, the inner radius, and the height of coil are observed to be approximately in the ratio 2.5:1.6:1. Analysis of final optimized population has been carried out and is compared with the case without bias magnets and some salient points are observed in the case of using bias magnets.

  2. Nonlinear Control for Magnetic Bearings in Deployment Test Rigs : Simulation and Experimental Results

    NARCIS (Netherlands)

    Scherpen, J.M.A.; Kerk, B. van der; Klaassens, J.B.; Lazeroms, M.; Kan, S.Y.

    1998-01-01

    In this paper three control schemes for a test set-up of a magnetic bearing system for deployment rigs of solar arrays are described. The air gap of the magnet has to be controlled to a constant value independent of the deployment of the solar array. The deployment of the rig has been modeled as a

  3. Nonlinear Control for Magnetic Bearings in Deployment Test Rigs : Simulation and Experimental Results

    NARCIS (Netherlands)

    Scherpen, J.M.A.; Kerk, B. van der; Klaassens, J.B.; Lazeroms, M.; Kan, S.Y.

    1998-01-01

    In this paper three control schemes for a test set-up of a magnetic bearing system for deployment rigs of solar arrays are described. The air gap of the magnet has to be controlled to a constant value independent of the deployment of the solar array. The deployment of the rig has been modeled as a v

  4. Nonlinear Control for Magnetic Bearings in Deployment Test Rigs : Simulation and Experimental Results

    NARCIS (Netherlands)

    Scherpen, J.M.A.; Kerk, B. van der; Klaassens, J.B.; Lazeroms, M.; Kan, S.Y.

    1998-01-01

    In this paper three control schemes for a test set-up of a magnetic bearing system for deployment rigs of solar arrays are described. The air gap of the magnet has to be controlled to a constant value independent of the deployment of the solar array. The deployment of the rig has been modeled as a v

  5. An Overview on Aerospatiale Magnetic Bearing Products for Spacecraft Attitude Control and for Industry

    Science.gov (United States)

    Samuel, Alain; Lechable, Bernard

    1996-01-01

    Aerospatiale magnetic bearings are based on the use of permanent magnets and on the control of the rotor around a zero force equilibrium point. The present developments of magnetic bearing wheels for space applications focus on the versatility of a basic design which leads to a family of reaction and momentum wheels with tailored torque and kinetic momentum, leading to competitive mass and cost. The present industrial applications concern kinetic energy accumulators, medical x-ray rotating devices, avionics equipment, cryotechnic compressors and vacuum pumps.

  6. Dynamic behavior of a magnetic bearing supported jet engine rotor with auxiliary bearings

    Science.gov (United States)

    Flowers, George T.; Xie, Huajun; Sinha, S. C.

    1995-01-01

    This paper presents a study of the dynamic behavior of a rotor system supported by auxiliary bearings. The steady-state behavior of a simulation model based upon a production jet engine is explored over a wide range of operating conditions for varying rotor imbalance, support stiffness, and damping. Interesting dynamical phenomena, such as chaos, subharmonic responses, and double-valued responses, are presented and discussed.

  7. Rotor's Suspension for Vernier-gimballing magnetically suspended flywheel with conical magnetic bearing.

    Science.gov (United States)

    Tang, Jiqiang; Xiang, Biao; Wang, Chun'e

    2015-09-01

    A novel Vernier-gimballing magnetically suspended flywheel with conical magnetic bearing (conical MB) can generate great gyroscopic moment by tilting the high-speed rotor. To output the gyroscopic moment, the high-speed rotor must be suspended stably and can be tilted. But when the rotor tilts, the gap between the stator and rotor of conical MB changes nonlinearly, what will cause the magnetic force and current stiffness of this conical MB to be serious nonlinear. To solve these problems, one kind of adaptive controller based on Lyapunov stability theory is designed by regarding the current stiffness of this conical MB as uncertain parameter. The validity of this adaptive control method is verified on a Vernier-gimballing MSFW with 68 Nms angular momentum and 1.7° maximum tilting angle. All experimental results indicated that this adaptive control has better performances on controlling rotor's stable suspension than existing PID control when the rotor translates or tilts. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  8. Research on a novel high stiffness axial passive magnetic bearing for DGMSCMG

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jinji [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, 100191 (China); Wang, Chun' e [Beijing Institute of Automatic Control Equipment, 100074 (China); Le, Yun [Key Laboratory of Fundamental Science for National Defense, Novel Inertial Instrument and Navigation System Technology, School of Instrument Science and Opto-electronics Engineering, Beihang University, 100191 (China)

    2016-08-15

    To increase the displacement stiffness and decrease power loss of double gimbals magnetically suspended control momentum gyro (DGMSCMG), this paper researches a new structure of axial passive magnetic bearing (APMB). Different from the existing APMB, the proposed APMB is composed of segmented permanent magnets and magnetic rings. The displacement stiffness and angular stiffness expressions are derived by equivalent magnetic circuit method and infinitesimal method based on the end magnetic flux. The relationships are analyzed between stiffness and structure parameters such as length of air gap, length of permanent magnet, height of permanent magnet and end length of magnetic ring. Besides, the axial displacement stiffness measurement method of the APMB is proposed, and it verified the correctness of proposed theoretical method. The DGMSCMG prototype is manufactured and the slow-down characteristic experiment is carried out, and the experimental result reflects the low power loss feature of the APMB. - Highlights: • A novel high stiffness axial passive magnetic bearing for DGMSCMG. • The proposed APMB is composed of segmented permanent magnets and magnetic rings. • The APMB is analyzed by EMCM and infinitesimal method based on the end magnetic flux. • The axial displacement stiffness measurement method of the APMB is proposed. • The DGMSCMG is manufactured and proved the correctness of theoretical analysis.

  9. Magnetic single-walled carbon nanotubes as efficient drug delivery nanocarriers in breast cancer murine model: noninvasive monitoring using diffusion-weighted magnetic resonance imaging as sensitive imaging biomarker

    Directory of Open Access Journals (Sweden)

    Al Faraj A

    2014-12-01

    Full Text Available Achraf Al Faraj,1 Abjal Pasha Shaik,2 Asma Sultana Shaik1,3 1Department of Radiological Sciences, 2Department of Clinical Lab Sciences, College of Applied Medical Sciences, 3Prince Naif Health Research Center, College of Medicine, King Saud University, Riyadh, Saudi Arabia Purpose: Targeting doxorubicin (DOX by means of single-walled carbon nanotube (SWCNT nanocarriers may help improve the clinical utility of this highly active therapeutic agent. Active targeting of SWCNTs using tumor-specific antibody and magnetic attraction by tagging the nanotubes with iron oxide nanoparticles can potentially reduce the unnecessary side effects and provide enhanced theranostics. In the current study, the in vitro and in vivo efficacy of DOX-loaded SWCNTs as theranostic nanoprobes was evaluated in a murine breast cancer model.Methods: Iron-tagged SWCNTs conjugated with Endoglin/CD105 antibody with or without DOX were synthetized and extensively characterized. Their biocompatibility was assessed in vitro in luciferase (Luc2-expressing 4T1 (4T1-Luc2 murine breast cancer cells using TiterTACS™ Colorimetric Apoptosis Detection Kit (apoptosis induction, poly (ADP-ribose polymerase (marker for DNA damage, and thiobarbituric acid-reactive substances (oxidative stress generation assays, and the efficacy of DOX-loaded SWCNTs was evaluated by measuring the radiance efficiency using bioluminescence imaging (BLI. Tumor progression and growth were monitored after 4T1-Luc2 cells inoculation using noninvasive BLI and magnetic resonance imaging (MRI before and after subsequent injection of SWCNT complexes actively and magnetically targeted to tumor sites.Results: Significant increases in apoptosis, DNA damage, and oxidative stress were induced by DOX-loaded SWCNTs. In addition, a tremendous decrease in bioluminescence was observed in a dose- and time-dependent manner. Noninvasive BLI and MRI revealed successful tumor growth and subsequent attenuation along with metastasis

  10. Verification of Spin Magnetic Attitude Control System using air-bearing-based attitude control simulator

    Science.gov (United States)

    Ousaloo, H. S.; Nodeh, M. T.; Mehrabian, R.

    2016-09-01

    This paper accomplishes one goal and it was to verify and to validate a Spin Magnetic Attitude Control System (SMACS) program and to perform Hardware-In-the-Loop (HIL) air-bearing experiments. A study of a closed-loop magnetic spin controller is presented using only magnetic rods as actuators. The magnetic spin rate control approach is able to perform spin rate control and it is verified with an Attitude Control System (ACS) air-bearing MATLAB® SIMULINK® model and a hardware-embedded LABVIEW® algorithm that controls the spin rate of the test platform on a spherical air bearing table. The SIMULINK® model includes dynamic model of air-bearing, its disturbances, actuator emulation and the time delays caused by on-board calculations. The air-bearing simulator is employed to develop, improve, and carry out objective tests of magnetic torque rods and spin rate control algorithm in the experimental framework and to provide a more realistic demonstration of expected performance of attitude control as compared with software-based architectures. Six sets of two torque rods are used as actuators for the SMACS. It is implemented and simulated to fulfill mission requirement including spin the satellite up to 12 degs-1 around the z-axis. These techniques are documented for the full nonlinear equations of motion of the system and the performances of these techniques are compared in several simulations.

  11. Basic Characteristics and Design of a Novel Hybrid Magnetic Bearing for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yanjun Yu

    2016-11-01

    Full Text Available This paper proposes a five-degree-of-freedom (5-DOF hybrid magnetic bearing (HMB for direct-drive wind turbines, which can realize suspension in the 4-DOF radial and 1-DOF axial directions. Only two sets of radial control windings are employed in the proposed HMB because only one set of radial control windings can achieve the 2-DOF suspension in the radial direction. Unlike the traditional active thrust magnetic bearings, this paper uses a cylindrical rotor core without a large thrust disc in the novel HMB. The numbers of the controller, power amplifier and system volume can be reduced in the magnetic suspension system. This paper also presents the structure and basic characteristics of the proposed magnetic bearing. A precision equivalent magnetic circuit analysis of the permanent magnet ring and control magnetic field is conducted in this study, in consideration of the non-uniform distribution of magnetic density. Accordingly, the mathematical models, including the suspension force expression, are derived based on the accurate equivalent magnetic circuit. The basic principle of the structure parameter design is presented, based on the given key parameters. The accuracy of the analytical method is further validated by 3D finite element analysis.

  12. Identifying parameters in active magnetic bearing system using LFT formulation and Youla factorization

    DEFF Research Database (Denmark)

    Lauridsen, Jonas; Sekunda, André Krabdrup; Santos, Ilmar

    2015-01-01

    In this paper, a method for identifying uncertain parameters in a rotordynamic system composed of a flexible rotating shaft, rigid discs and two radial active magnetic bearings is presented. Shaft and disc dynamics are mathematically described using a Finite Element (FE) model while magnetic...... bearing forces are represented by linear springs with negative stiffness. Bearing negative stiffness produces an unstable rotordynamic system, demanding implementation of feedback control to stabilize the rotordynamic system. Thus, to identify the system parameters, closed-loop system identification...... techniques are required., The main focus of the paper relies on how to effectively identify uncertain parameters, such as stiffness and damping force coefficients of bearings and seals in rotordynamic systems. Dynamic condensation method, i.e. pseudo-modal reduction, is used to obtain a reduced order model...

  13. High-speed, high-temperature magnetic bearings for jet turbine engine application

    Energy Technology Data Exchange (ETDEWEB)

    Mekhiche, M.; Nichols, S.; Hevenhill, D.; Oleksy, J.; Young, J.; Kirtley, J.L. [SatCon Technology Corporation, Cambridge, MA (United States)

    2000-08-01

    In order to double today's jet turbine engines' propulsion capability, lightweight, high-efficiency, high-speed and hightemperature components are sought. These requirements put the conventional components such as the mechanical bearings under excessive constraints and make them obsolete. In this context, SatCon Technology Corporation has developed a high-speed, high- temperature (50 krpm, 600 deg. C) magnetic bearing system that has the potential of meeting the requirements described above. This magnetic bearing system, comprised of two radial and one double acting thrust bearings, was successfully tested to 50,000 rpm. This paper describes the development of this system from its design, through its fabrication and final testing. Details on the system and component requirements are presented, along with a step-by step design and trade-off analysis. Test data and their discussion are provided as well. (orig.)

  14. A magnetic bearing momentum wheel for high pointing accuracy and vibration sensitive space applications

    Science.gov (United States)

    Bichler, U. J.

    The paper describes a magnetic bearing momentum wheel (MW-X) theoretically and experimentally with attention given to its low-noise application to spacecraft attitude-control systems. The MW-X gyroscopic actuator comprises a rotor, emergency bearings, a locking mechanisms, and a drive motor, and Vernier gimballing is employed so that the rotor and the momentum vector can be tilted actively with about one degree. The MW-X utilizes a suspension-control system for noise attenuation and active vibration suppression to reduce noise from the sensor surface. The actively controlled magnetic bearing wheels are shown to provide active damping of flexible structures by means of fully controllable translational bearing forces. The MW-X devices are of interest for applications to optical communications links, space telescopes, and earth-observation satellites with high resolutions.

  15. High Speed Operation and Testing of a Fault Tolerant Magnetic Bearing

    Science.gov (United States)

    DeWitt, Kenneth; Clark, Daniel

    2004-01-01

    Research activities undertaken to upgrade the fault-tolerant facility, continue testing high-speed fault-tolerant operation, and assist in the commission of the high temperature (1000 degrees F) thrust magnetic bearing as described. The fault-tolerant magnetic bearing test facility was upgraded to operate to 40,000 RPM. The necessary upgrades included new state-of-the art position sensors with high frequency modulation and new power edge filtering of amplifier outputs. A comparison study of the new sensors and the previous system was done as well as a noise assessment of the sensor-to-controller signals. Also a comparison study of power edge filtering for amplifier-to-actuator signals was done; this information is valuable for all position sensing and motor actuation applications. After these facility upgrades were completed, the rig is believed to have capabilities for 40,000 RPM operation, though this has yet to be demonstrated. Other upgrades included verification and upgrading of safety shielding, and upgrading control algorithms. The rig will now also be used to demonstrate motoring capabilities and control algorithms are in the process of being created. Recently an extreme temperature thrust magnetic bearing was designed from the ground up. The thrust bearing was designed to fit within the existing high temperature facility. The retrofit began near the end of the summer, 04, and continues currently. Contract staff authored a NASA-TM entitled "An Overview of Magnetic Bearing Technology for Gas Turbine Engines", containing a compilation of bearing data as it pertains to operation in the regime of the gas turbine engine and a presentation of how magnetic bearings can become a viable candidate for use in future engine technology.

  16. Magnetic bearings for a high-performance optical disk buffer, volume 1

    Science.gov (United States)

    Hockney, Richard; Adler, Karen; Anastas, George, Jr.; Downer, James; Flynn, Frederick; Goldie, James; Gondhalekar, Vijay; Hawkey, Timothy; Johnson, Bruce

    1990-01-01

    The innovation investigated in this project was the application of magnetic bearing technology to the translator head of an optical-disk data storage device. Both the capability for space-based applications and improved performance are expected to result. The phase 1 effort produced: (1) detailed specifications for both the translator-head and rotary-spindel bearings; (2) candidate hardware configurations for both bearings with detail definition for the translator head; (3) required characteristics for the magnetic bearing control loops; (4) position sensor selection; and (5) definition of the required electronic functions. The principal objective of Phase 2 was the design, fabrication, assembly, and test of the magnetic bearing system for the translator head. The scope of work included: (1) mechanical design of each of the required components; (2) electrical design of the required circuitry; (3) fabrication of the component parts and bread-board electronics; (4) generation of a test plan; and (5) integration of the prototype unit and performance testing. The project has confirmed the applicability of magnetic bearing technology to suspension of the translator head of the optical disk device, and demonstrated the achievement of all performance objectives. The magnetic bearing control loops perform well, achieving 100 Hz nominal bandwidth with phase margins between 37 and 63 degrees. The worst-case position resolution is 0.02 micron in the displacement loops and 1 micron rad in the rotation loops, The system is very robust to shock disturbances, recovering smoothly even when collisions occur between the translator and frame. The unique start-up/shut-down circuit has proven very effective.

  17. A hydrodynamically suspended, magnetically sealed mechanically noncontact axial flow blood pump: design of a hydrodynamic bearing.

    Science.gov (United States)

    Mitamura, Yoshinori; Kido, Kazuyuki; Yano, Tetsuya; Sakota, Daisuke; Yambe, Tomoyuki; Sekine, Kazumitsu; OKamoto, Eiji

    2007-03-01

    To overcome the drive shaft seal and bearing problem in rotary blood pumps, a hydrodynamic bearing, a magnetic fluid seal, and a brushless direct current (DC) motor were employed in an axial flow pump. This enabled contact-free rotation of the impeller without material wear. The axial flow pump consisted of a brushless DC motor, an impeller, and a guide vane. The motor rotor was directly connected to the impeller by a motor shaft. A hydrodynamic bearing was installed on the motor shaft. The motor and the hydrodynamic bearing were housed in a cylindrical casing and were waterproofed by a magnetic fluid seal, a mechanically noncontact seal. Impeller shaft displacement was measured using a laser sensor. Axial and radial displacements of the shaft were only a few micrometers for motor speed up to 8500 rpm. The shaft did not make contact with the bearing housing. A flow of 5 L/min was obtained at 8000 rpm at a pressure difference of 100 mm Hg. In conclusion, the axial flow blood pump consisting of a hydrodynamic bearing, a magnetic fluid seal, and a brushless DC motor provided contact-free rotation of the impeller without material wear.

  18. A Comparison Study of Magnetic Bearing Controllers for a Fully Suspended Dynamic Spin Rig

    Science.gov (United States)

    Choi, Benjamin; Johnson, Dexter; Morrison, Carlos; Mehmed, Oral; Huff, Dennis (Technical Monitor)

    2002-01-01

    NASA Glenn Research Center (GRC) has developed a fully suspended magnetic bearing system for the Dynamic Spin Rig (DSR) that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust bearing and the associated control system were integrated into the DSR to provide noncontact magnetic suspension and mechanical excitation of the 35 lb vertical rotor with blades to induce turbomachinery blade vibration. A simple proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked very well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, and energy savings for the system. The test results of a variety of controllers we demonstrated up to the rig's maximum allowable speed of 10,000 rpm are shown.

  19. Automatic Weight Selection Algorithm for Designing H Infinity controller for Active Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    Sarath S Nair

    2011-01-01

    Full Text Available In recent times active magnetic bearing has got wide acceptance in industries and other special systems. Current researches focus on improving the disturbance rejection properties of magnetic bearings towork well in industrial environment. So far many controllers have been developed to control the system, of which the H∞ controller is found to guarantee robustness and performance. In this paper an automatic weight selection algorithm is proposed to design robust H Infinity controller automatically for active magnetic bearing system and detailed disturbance analysis is done. This paper focuses on the controller implementation point of view and analyses the variation in control current, peak responses and steady state error of the developed controller. Comparison with a well tuned PID controller shows the efficacy of H infinity controller designed using the proposed algorithm.

  20. CONTROL SYSTEM OF MAGNETIC BEARINGS BASED ON LINEAR QUADRATIC METHOD OF OPTIMAL CONTROL STRATEGY

    Institute of Scientific and Technical Information of China (English)

    Zhu Huangqiu

    2005-01-01

    A state equation for radical 4-degree-of-freedom active magnetic bearings is built, and the approach on how to use linear quadratic method of optical control theory to design a centralized and decentralized parameters control system is introduced, and also Matlab language is used to simulate and analyze. The simulation results have proved that the differences are small between centralized parameters and decentralized parameters control system. The conclusions of experiments have shown that decentralized controllers designed from optimal state feedback theory meet the requirements of active magnetic bearing system. The vibration amplitude of the rotor is about 20 μm when the speed of the rotor runs between 0 to 60 000 r/min. This method may be used in the study and design of controllers of magnetic bearings.

  1. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, S., E-mail: ohashi@ipcku.kansai-u.ac.j [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan); Kobayashi, S. [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-10-15

    Magnetic levitation using the pinning force of the YBaCuO high-T{sub c} bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  2. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Science.gov (United States)

    Ohashi, S.; Kobayashi, S.

    2009-10-01

    Magnetic levitation using the pinning force of the YBaCuO high- Tc bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  3. Design Method for the Magnetic Bearing Control System with Fuzzy-PID Approach

    Institute of Scientific and Technical Information of China (English)

    XU Chun-guang; L(U) Dong-ming; HAO Juan

    2008-01-01

    The five degree freedom magnetic bearing is researched and its structure and working principles are introduced also.Based on the fuzzy control technology,combining fuzzy algorithm and PID control method,identifying the transition process mode of the online system to get the PID parameters'self-adjusting,the magnetic bearing system's Fuzzy-PID nonlinear controller is designed by analyzing the system control demands.The Fuzzy-PID nonlinear controller can deal with the magnetic bearing system's open loop instability and strong nonlinearity,and the approach could improve the system's rapidity,adaptability,stability and dynamic characteristics.Comparative analysis and experiments are conducted between linear PID and nonlinear fuzzyPID control methods,the results show that the fuzzy-PID controller is better,and the five-freedom magnetic bearing's rotary precision experiments are conducted by the fuzzy-PID controller,it satisfies the control rotary precision demands and realizes the bearing's steady floating and rotating.

  4. DESIGN AND APPLICATION OF MAGNETIC BEARING SUSPENSION SYSTEM IN A THREE PHASE INDUCTION MOTOR

    Directory of Open Access Journals (Sweden)

    Osman GÜRDAL

    1998-03-01

    Full Text Available The current popularity of suspension and levitation stems no doubt the possibilities in high-speed ground transportation schemes. Although these are both challenging and exciting, there is considerable scope for application of suspension techniques to achieving frictionless bearing. The requirement in this case is often for close tolerances, low power consumption, small airgaps and ingeneral, compactness. Thus, magnetic suspension using DC electromagnets schemes have received more attention than the other techniques of repulsion levitation. Proposed prototype system consists of a conventional stator and its rotor without iron core, set of electromagnets for suspension of rotor shaft and set of compensation circuits feedbacked by optical-transducers. Prototyped system is aimed as a laboratory demonstration tool so there is no challenging to exceed the speeds of 1500 rev/min that is the speed of motor with mechanical bearings. Magnetic bearing suspension system provides a high impact visual demonstration of many principles in undergraduate educational programs in electrical education, e.g., electromagnetic design, PD controlled compensation of a unstable control system and power amplifier design. The system is capable of giving a good comparison between mechanical and magnetic bearing up to speeds 350 rev/min. Power losses without load show about 15% reduction with magnetic bearing. The noise of the motor is also decreased to a low level.

  5. Transverse-displacement stabilizer for passive magnetic bearing systems

    Energy Technology Data Exchange (ETDEWEB)

    Post, Richard F

    2017-03-07

    The invention provides a way re-center a rotor's central longitudinal rotational axis with a desired system longitudinal axis. A pair of planar semicircular permanent magnets are pieced together to form a circle. The flux from each magnet is pointed in in opposite directions that are both parallel with the rotational axis. A stationary shorted circular winding the plane of which is perpendicular to the system longitudinal axis and the center of curvature of the circular winding is positioned on the system longitudinal axis. Upon rotation of the rotor, when a transverse displacement of the rotational axis occurs relative to the system longitudinal axis, the winding will experience a time-varying magnetic flux such that an alternating current that is proportional to the displacement will flow in the winding. Such time-varying magnetic flux will provide a force that will bring the rotor back to its centered position about the desired axis.

  6. Improvement of the rotational characteristics in the HTSC-permanent magnet hybrid bearing using ring shaped magnet

    Science.gov (United States)

    Emoto, Kozo; Sugiyama, Ryo; Takagi, Shogo; Ohashi, Shunsuke

    2013-11-01

    We have developed the hybrid magnetic bearing using permanent magnets and the high-Tc bulk superconductor (HTSC). Pinning force of the HTSC is used for the levitation and the guidance. Repulsive force of the permanent magnets is introduced to increase the load weight of the magnetic bearing. In this system, the stator side permanent magnet has the ring type structure so that both pinning force and repulsive force are used effectively. In this paper, influence of the hybrid system on dynamic characteristics of the rotor is studied. The rotor which is supported by the hybrid magnetic bearing is rotated. Then, vibration and the gradient angle of the rotor are measured until the rotor reaches to the end of the resonance state. Three dimensional numerical analysis of the flux which penetrates on the surface of the HTSC is undertaken. The relation between the dynamic characteristics and the flux is considered, and that of the hybrid system is compared with the non-hybrid one. In the hybrid system, the flux is changed by the influences of the stator side permanent magnet. Vibration and the gradient angle of the hybrid system are shown to be smaller than that of the non-hybrid one.

  7. Single axis controlled hybrid magnetic bearing for left ventricular assist device: hybrid core and closed magnetic circuit.

    Science.gov (United States)

    da Silva, Isaias; Horikawa, Oswaldo; Cardoso, Jose R; Camargo, Fernando A; Andrade, Aron J P; Bock, Eduardo G P

    2011-05-01

    In previous studies, we presented main strategies for suspending the rotor of a mixed-flow type (centrifugal and axial) ventricular assist device (VAD), originally presented by the Institute Dante Pazzanese of Cardiology (IDPC), Brazil. Magnetic suspension is achieved by the use of a magnetic bearing architecture in which the active control is executed in only one degree of freedom, in the axial direction of the rotor. Remaining degrees of freedom, excepting the rotation, are restricted only by the attraction force between pairs of permanent magnets. This study is part of a joint project in development by IDPC and Escola Politecnica of São Paulo University, Brazil. This article shows advances in that project, presenting two promising solutions for magnetic bearings. One solution uses hybrid cores as electromagnetic actuators, that is, cores that combine iron and permanent magnets. The other solution uses actuators, also of hybrid type, but with the magnetic circuit closed by an iron core. After preliminary analysis, a pump prototype has been developed for each solution and has been tested. For each prototype, a brushless DC motor has been developed as the rotor driver. Each solution was evaluated by in vitro experiments and guidelines are extracted for future improvements. Tests have shown good results and demonstrated that one solution is not isolated from the other. One complements the other for the development of a single-axis-controlled, hybrid-type magnetic bearing for a mixed-flow type VAD.

  8. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    Energy Technology Data Exchange (ETDEWEB)

    Curwen, P.W.; Rao, D.K.; Wilson, D.S. [Mechanical Technology Inc., Latham, NY (United States)

    1992-06-01

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, {open_quotes}A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.{close_quotes} The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions.

  9. Magnevad--the world's smallest magnetic-bearing turbo pump.

    Science.gov (United States)

    Goldowsky, Michael

    2004-10-01

    The first animal implant of our Magnevad LVAD is scheduled for the fourth quarter of 2003. This is being performed by the George E. Reed Heart Center of Westchester Medical Center and by New York Medical College; both are in Valhalla, NY. This article summarizes 3 years of development of the miniature axial flow LVAD. Our LVAD has new innovations not found in any other turbo pump to minimize thrombus, blood turbulence, flow separation, and the generation of microemboli. The Magnevad is only 25 mL in volume, similar in size to the Micromed & Jarvik 2000 axial flow turbo pumps that have contacting bearings. US Patent 6 527 699 was issued to Gold Medical on March 4, 2003 and World Wide PCT patents are pending. The discussed improvements (patents pending) are designed to minimize flow separation and turbulence, the precursors of microemboli that lodge in end organs. This problem has been largely ignored in the published literature. A new long-term stable miniature ultrasonic position sensor is used for bearing control. It measures the axial position of the rotor to obtain LVAD differential pressure. Differential pressure is used to obtain pulsating flow and automatic physiologic control. The term "fourth generation pump" is being coined for the Magnevad because in addition to being noncontacting, it inherently measures pump differential pressure on which physiologic control can be based.

  10. Improvement of the rotational characteristics in the HTSC-permanent magnet hybrid bearing using ring shaped magnet

    Energy Technology Data Exchange (ETDEWEB)

    Emoto, Kozo; Sugiyama, Ryo; Takagi, Shogo; Ohashi, Shunsuke, E-mail: k145676@kansai-u.ac.jp

    2013-11-15

    Highlights: •We have developed the HTS-permanent magnet hybrid bearing system. •Three dimensional numerical analysis is undertaken to get the effective hybrid configuration. •Repulsive force and pinning force are combined effectively. •The hybrid system shows better levitation characteristics than the non-hybrid one. •In the mechanical resonance state, vibration of the rotor in the hybrid system is small. -- Abstract: We have developed the hybrid magnetic bearing using permanent magnets and the high-T{sub c} bulk superconductor (HTSC). Pinning force of the HTSC is used for the levitation and the guidance. Repulsive force of the permanent magnets is introduced to increase the load weight of the magnetic bearing. In this system, the stator side permanent magnet has the ring type structure so that both pinning force and repulsive force are used effectively. In this paper, influence of the hybrid system on dynamic characteristics of the rotor is studied. The rotor which is supported by the hybrid magnetic bearing is rotated. Then, vibration and the gradient angle of the rotor are measured until the rotor reaches to the end of the resonance state. Three dimensional numerical analysis of the flux which penetrates on the surface of the HTSC is undertaken. The relation between the dynamic characteristics and the flux is considered, and that of the hybrid system is compared with the non-hybrid one. In the hybrid system, the flux is changed by the influences of the stator side permanent magnet. Vibration and the gradient angle of the hybrid system are shown to be smaller than that of the non-hybrid one.

  11. Multiple attractors in the response of a flexible rotor in active magnetic bearings with geometric coupling

    Energy Technology Data Exchange (ETDEWEB)

    Inayat-Hussain, J I [School of Engineering, Monash University, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor Darul Ehsan (Malaysia)], E-mail: jawaid.inayat-hussain@eng.monash.edu.my

    2008-02-15

    Numerical results on the response of a flexible rotor supported by nonlinear active magnetic bearings are presented. Nonlinearity arising from the magnetic actuator forces that are nonlinear functions of the coil current and the air gap between the rotor and the stator, and from the geometric coupling of the magnetic actuators is incorporated into the mathematical model of the flexible rotor - active magnetic bearing system. For relatively large values of the geometric coupling parameter, the response of the rotor with the variation of the speed parameter within the range 0.05 {<=}{omega} {<=} 5.0 displayed a rich variety of nonlinear dynamical phenomena including sub-synchronous vibrations of periods -2, -3, -6, -9, and -17, quasi-periodicity and chaos. Numerical results also reveal the occurrence of bi-stable operation within certain ranges of the speed parameter where multiple attractors may co-exist at the same speed parameter value depending on the operating speed of the rotor.

  12. GA-BASED PID NEURAL NETVVORK CONTROL FOR MAGNETIC BEARING SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    LI Guodong; ZHANG Qingchun; LIANG Yingchun

    2007-01-01

    In order to overcome the system non-linearity and uncertainty inherent in magnetic bearing systems, a GA(genetic algorithm)-based PID neural network controller is designed and trained to emulate the operation of a complete system (magnetic beating, controller, and power amplifiers).The feasibility of using a neural network to control nonlinear magnetic beating systems with unknown dynamics is demonstrated. The key concept of the control scheme is to use GA to evaluate the candidate solutions (chromosomes), increase the generalization ability of PID neural network and avoid suffering from the local minima problem in network learning due to the use of gradient descent learning method. The simulation results show that the proposed architecture provides well robust performance and better reinforcement learning capability in controlling magnetic bearing systems.

  13. Nonlinear dynamic behaviour of a rotor-foundation system coupled through passive magnetic bearings with magnetic anisotropy - Theory and experiment

    DEFF Research Database (Denmark)

    Enemark, Søren; Santos, Ilmar F.

    2016-01-01

    In this work, the nonlinear dynamic behaviour of a vertical rigid rotor interacting with a flexible foundation by means of two passive magnetic bearings is quantified and evaluated. The quantification is based on theoretical and experimental investigation of the non-uniformity (anisotropy) of the...

  14. Passive magnetic bearing in the 3rd generation miniature axial flow pump-the valvo pump 2.

    Science.gov (United States)

    Okamoto, Eiji; Ishida, Yuya; Yano, Tetsuya; Mitamura, Yoshinori

    2015-06-01

    The new miniature axial flow pump (valvo pump 2) that is installed at the base of the ascending aorta consists of a six-phase stator, an impeller in which four neodymium magnets are incorporated, and passive magnetic bearings that suspend the impeller for axial levitation. The impeller is sustained by hydrodynamic force between the blade tip of the impeller and the inner housing of the stator. The passive magnetic bearing consists of a ring neodymium magnet and a columnar neodymium magnet. The ring neodymium magnet is set in the stationary side and the columnar neodymium magnet is incorporated in the impeller shaft. Both neodymium magnets are coaxially mounted, and the anterior and posterior passive magnetic bearings suspend the impeller by repulsion force against the hydrodynamic force that acts to move the impeller in the inflow port direction. The passive magnetic bearing was evaluated by a tensile test, and the levitation force of 8.5 N and stiffness of 2.45 N/mm was obtained. Performance of the axial flow pump was evaluated by an in vitro experiment. The passive magnetic bearing showed sufficient levitation capacity to suspend the impeller in an axial direction. In conclusion, the passive magnetic bearing is promising to be one of levitation technology for the third-generation axial flow blood pump.

  15. The Avoidance of Saturation Limits in Magnetic Bearing Systems During Transient Excitation

    Science.gov (United States)

    Rutland, Neil K.; Keogh, Patrick S.; Burrows, Clifford R.

    1996-01-01

    When a transient event, such as mass loss, occurs in a rotor/magnetic bearing system, optimal vibration control forces may exceed bearing capabilities. This will be inevitable when the mass loss is sufficiently large and a conditionally unstable dynamic system could result if the bearing characteristic become non-linear. This paper provides a controller design procedure to suppress, where possible, bearing force demands below saturation levels while maintaining vibration control. It utilizes H(sub infinity) optimization with appropriate input and output weightings. Simulation of transient behavior following mass loss from a flexible rotor is used to demonstrate the avoidance of conditional instability. A compromise between transient control force and vibration levels was achieved.

  16. Mini hemoreliable axial flow LVAD with magnetic bearings: part 2: design description.

    Science.gov (United States)

    Goldowsky, Michael

    2002-01-01

    This paper gives the preliminary configuration of the flow geometry used to eliminate bearing thrombus by forced pressure wash-out of the bearing gaps. This left ventricular assist device (LVAD) is physiologically controllable without extraneous sensors based on the measurement of pump differential pressure using the magnetic bearings. Knowing the LVAD differential pressure allows safe cyclic variation of impeller rpm with feedback around differential pressure, which obtains desired pressure pulsatility. Flow pulsatility is known to be of major benefit for minimizing thrombus in both the pump and arteries. It also results in improved perfusion of many organs. The ability of a conventional virtual zero power feedback loop to axially control the bearing in a long-term drift free manor is also explained.

  17. STUDY ON CATASTROPHIC MECHANISM FOR ROTOR DROP TRANSIENT VIBRATION FOLLOWING MAGNETIC BEARING FAILURE

    Institute of Scientific and Technical Information of China (English)

    方之楚

    2002-01-01

    The nonlinear and transient vibration of a rotor, which dropped onto back-up bearings when its active magnetic bearings were out of order, was investigated. After strictly deriving its equations of motion and performing numerical simulations, the timehistories of rotating speed of the dropping rotor, and normal force at the rubbing contact point as well as the frequency spectrum of the vibration displacement of back-up bearings are fully analyzed. It is found that the strong and unsteady forced bending vibration of the unbalanced and damped rotor decelerating through its first bending vibtation of the unbalanced and damped rotor decelerating through its first critical speed as well as chattering at high frequencies caused by the nonlinearity at the rubbing contact point between the journal and back-up bearings may lead to the catastrophic damage of the system.

  18. Electromagnetic Forces in a Hybrid Magnetic-Bearing Switched-Reluctance Motor

    Science.gov (United States)

    Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

    2008-01-01

    Analysis and experimental measurement of the electromagnetic force loads on the hybrid rotor in a novel hybrid magnetic-bearing switched-reluctance motor (MBSRM) have been performed. A MBSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The MBSRM discussed in this report has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of four stator poles, while a second set of four stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Static torque and radial force analysis were done for rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental and the theoretical radial force loads predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

  19. Slider Posture Effects on Air Bearing in a Heat-Assisted Magnetic Recording System

    Directory of Open Access Journals (Sweden)

    Kyaw Sett Myo

    2012-01-01

    Full Text Available This paper reports the effects of slider posture on the slider bearing in a heat-assisted magnetic recording (HAMR system with the direct simulation Monte Carlo (DSMC method. In this HAMR system, the heat issues on the slider bearings are assumed to be caused by a heated spot on the disk and/or slider body itself at various pitch angles. The simulation results show that with a heated spot on the disk, the air bearing pressure and air bearing force that acted on the slider surface will increase when the pitch angle becomes larger. It is also found that the bearing force increases with the heated spot size and the effects of a heated spot become more obvious at a larger pitch angle. On the other hand, the slider body temperature is observed to have a noticeable effect on air bearing pressure and force. The smaller pitch angle enlarges the tendency of bearing force variations with the slider temperature and makes the slider more sensitive to its temperature changes.

  20. A Spaceflight Magnetic Bearing Equipped Optical Chopper with Six-Axis Active Control

    Science.gov (United States)

    Blumenstock, Kenneth A.; Lee, Kenneth Y.; Schepis, Joseph P.

    1998-01-01

    This paper describes the development of an ETU (Engineering Test Unit) rotary optical chopper with magnetic bearings. An ETU is required to be both flight-like, nearly identical to a flight unit without the need for material certifications, and demonstrate structural and performance integrity. A prototype breadboard design previously demonstrated the feasibility of meeting flight performance requirements using magnetic bearings. The chopper mechanism is a critical component of the High Resolution Dynamics Limb Sounder (HIRDLS) which will be flown on EOS-CHEM (Earth Observing System-Chemistry). Particularly noteworthy are the science requirements which demand high precision positioning and minimal power consumption along with full redundancy of coils and sensors in a miniature, lightweight package. The magnetic bearings are unique in their pole design to minimize parasitic losses and utilize collocated optical sensing. The motor is of an unusual disk-type ironless stator design. The ETU design has evolved from the breadboard design. A number of improvements have been incorporated into the ETU design. Active thrust control has been added along with changes to improve sensor stability, motor efficiency, and touchdown and launch survivability. It was necessary to do all this while simultaneously reducing the mechanism volume. Flight-like electronics utilize a DSP (Digital Signal Processor) and contain all sensor electronics and drivers on a single five inch by nine inch circuit board. Performance test results are reported including magnetic bearing and motor rotational losses.

  1. Theoretical and Experimental Investigation of Force Estimation Errors Using Active Magnetic Bearings with Embedded Hall Sensors

    DEFF Research Database (Denmark)

    Voigt, Andreas Jauernik; Santos, Ilmar

    2012-01-01

    This paper gives an original theoretical and experimental contribution to the issue of reducing force estimation errors, which arise when applying Active Magnetic Bearings (AMBs) with pole embedded Hall sensors for force quantification purposes. Motivated by the prospect of increasing the usability...

  2. Optimum control of the active magnetic bearing for various parameters of the program movement

    Science.gov (United States)

    Majorov, S. V.; Makhova, N. N.

    2017-08-01

    We consider the mathematical model of stabilization of the situation of a rotor is given in an active magnetic bearing. Also various options of control system are considered Investigated influence of the program movement and free controller parameters on quality of control process.

  3. Simulation of Internal Damping in a Rotating System Supported by Magnetic Bearings

    Science.gov (United States)

    2007-11-02

    This thesis developed and validated a model for this purpose. An existing rotordynamic Finite Element Method (FEM) model and magnetic bearing...controllers were unable to counteract the destabilizing effects of internal damping during supercritical operation. This improved rotordynamic model and

  4. Development of magnetic bearing system for a new third-generation blood pump.

    Science.gov (United States)

    Lee, Jung Joo; Ahn, Chi Bum; Choi, Jaesoon; Park, Jun Woo; Song, Seung-Joon; Sun, Kyung

    2011-11-01

    A magnetic bearing system is a crucial component in a third-generation blood pump, particularly when we consider aspects such as system durability and blood compatibility. Many factors such as efficiency, occupying volume, hemodynamic stability in the flow path, mechanical stability, and stiffness need to be considered for the use of a magnetic bearing system in a third-generation blood pump, and a number of studies have been conducted to develop novel magnetic bearing design for better handling of these factors. In this study, we developed and evaluated a new magnetic bearing system having a motor for a new third-generation blood pump. This magnetic bearing system consists of a magnetic levitation compartment and a brushless direct current (BLDC) motor compartment. The active-control degree of freedom is one; this control is used for controlling the levitation in the axial direction. The levitation in the radial direction has a passive magnetic levitation structure. In order to improve the system efficiency, we separated the magnetic circuit for axial levitation by using a magnetic circuit for motor drive. Each magnetic circuit in the bearing system was designed to have a minimum gap by placing mechanical parts, such as the impeller blades, outside the circuit. A custom-designed noncontact gap sensor was used for minimizing the system volume. We fabricated an experimental prototype of the proposed magnetic bearing system and evaluated its performance by a control system using the Matlab xPC Target system. The noncontact gap sensor was an eddy current gap sensor with an outer diameter of 2.38 mm, thickness of 0.88 mm, and resolution of 5 µm. The BLDC motor compartment was designed to have an outer diameter of 20 mm, length of 28.75 mm, and power of 4.5 W. It exhibited a torque of 8.6 mNm at 5000 rpm. The entire bearing system, including the motor and the sensor, had an outer diameter of 22 mm and a length of 97 mm. The prototype exhibited sufficient levitation

  5. Riccati difference equation in optimal control for magnetic bearings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; LIU Kun

    2012-01-01

    A model predictive optimal control method for magnetically suspended flywheel is presented.In order to suppress the conical whirl of the rotor caused by gyroscopic effect,the synchronization error is added to the traditional quadratic performance index.The target performance index is composed of the translatory error,the synchronization error,and the control output predicted by the discrete-time state model.The optimal controller is obtained by means of iterating a Riccati difference equation (RDE).Stability of the control scheme is investigated through fake algebraic Riccati technique (FART).The robust performance of the controller with respect to control parameters is studied by simulation.Results of the simulation and experiment on a compact magnetically suspended flywheel demonstrate that the proposed controller with consideration of the synchronization error is very effective to suppress the conical whirl caused by gyroscopic effect.

  6. Rotors on Active Magnetic Bearings: Modeling and Control Techniques

    OpenAIRE

    Tonoli, Andrea; Bonfitto, Angelo; Silvagni, Mario; Suarez, Lester D.

    2012-01-01

    In the last decades the deeper and more detailed understanding of rotating machinery dynamic behavior facilitated the study and the design of several devices aiming at friction reduction, vibration damping and control, rotational speed increase and mechanical design optimization. Among these devices a promising technology is represented by active magnetic actuators which found a great spread in rotordynamics and in high precision applications due to (a) the absence of all fatigue and tribolog...

  7. Fully Suspended, Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig With Forced Excitation

    Science.gov (United States)

    Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Montague, Gerald; Duffy, Kirsten; Mehmed, Oral; Johnson, Dexter; Jansen, Ralph

    2004-01-01

    The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig, a significant advancement in the Dynamic Spin Rig (DSR), is used to perform vibration tests of turbomachinery blades and components under rotating and nonrotating conditions in a vacuum. The rig has as its critical components three magnetic bearings: two heteropolar radial active magnetic bearings and a magnetic thrust bearing. The bearing configuration allows full vertical rotor magnetic suspension along with a feed-forward control feature, which will enable the excitation of various natural blade modes in bladed disk test articles. The theoretical, mechanical, electrical, and electronic aspects of the rig are discussed. Also presented are the forced-excitation results of a fully levitated, rotating and nonrotating, unbladed rotor and a fully levitated, rotating and nonrotating, bladed rotor in which a pair of blades was arranged 180 degrees apart from each other. These tests include the bounce mode excitation of the rotor in which the rotor was excited at the blade natural frequency of 144 Hz. The rotor natural mode frequency of 355 Hz was discerned from the plot of acceleration versus frequency. For nonrotating blades, a blade-tip excitation amplitude of approximately 100 g/A was achieved at the first-bending critical (approximately 144 Hz) and at the first-torsional and second-bending blade modes. A blade-tip displacement of 70 mils was achieved at the first-bending critical by exciting the blades at a forced-excitation phase angle of 908 relative to the vertical plane containing the blades while simultaneously rotating the shaft at 3000 rpm.

  8. Stability Limits of a PD Controller for a Flywheel Supported on Rigid Rotor and Magnetic Bearings

    Science.gov (United States)

    Kascak, Albert F.; Brown, Gerald V.; Jansen, Ralph H.; Dever, TImothy P.

    2006-01-01

    Active magnetic bearings are used to provide a long-life, low-loss suspension of a high-speed flywheel rotor. This paper describes a modeling effort used to understand the stability boundaries of the PD controller used to control the active magnetic bearings on a high speed test rig. Limits of stability are described in terms of allowable stiffness and damping values which result in stable levitation of the nonrotating rig. Small signal stability limits for the system is defined as a nongrowth in vibration amplitude of a small disturbance. A simple mass-force model was analyzed. The force resulting from the magnetic bearing was linearized to include negative displacement stiffness and a current stiffness. The current stiffness was then used in a PD controller. The phase lag of the control loop was modeled by a simple time delay. The stability limits and the associated vibration frequencies were measured and compared to the theoretical values. The results show a region on stiffness versus damping plot that have the same qualitative tendencies as experimental measurements. The resulting stability model was then extended to a flywheel system. The rotor dynamics of the flywheel was modeled using a rigid rotor supported on magnetic bearings. The equations of motion were written for the center of mass and a small angle linearization of the rotations about the center of mass. The stability limits and the associated vibration frequencies were found as a function of nondimensional magnetic bearing stiffness and damping and nondimensional parameters of flywheel speed and time delay.

  9. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    张钢; 虞烈; 谢友柏

    2001-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  10. 径向磁轴承的力学特性%Mechanical Characteristics of Radial Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    张钢; 虞烈; 谢友柏

    2000-01-01

    This paper is based on the example of a radial magnetic bearing possessed of eight-pole, and derives the calculation formulas of static and dynamic mechanical characteristics of the bearing, in which the shape and curvature of surface, eccentricity and tilt of the journal are taken into account. Variations of the static and dynamic characteristics of the radial magnetic bearing versus static tilt parameters of journal are discussed. The outcomes show that the static tilt of the journal has influence on the mechanical characteristics of radial magnetic bearing, and change the static load capacity between two radial magnetic bearings and exert coupling effect between them. To study the dynamics of a practical rotor-magnetic bearing system, at least six stiffness coefficients in each radial magnetic bearing must be considered in ideal case, and twelve stiffness coefficients must be considered in general case of tilting journal. Such a find can be used for the coupled electromechanical dynamics analysis of rotor system equipped with magnetic bearings.

  11. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    Science.gov (United States)

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  12. Development of Y-Ba-Cu-O Superconductors for Magnetic Bearings

    Science.gov (United States)

    Selvamanickam, V.; Pfaffenbach, K.; Sokolowski, R. S.; Zhang, Y.; Salama, K.

    1996-01-01

    The material requirements, material manufacturing and magnetic properties that are relevant to fabrication of High Temperature Superconductor (HTS) magnetic bearings have been discussed. It is found that the seeded-melt-texturing method can be used to fabricate the single domain material that is required to achieve the best magnetic properties. Trapped-field mapping has been used as a non-destructive tool to determine the single-domain nature of the HTS material and quantity of the HTS disks. Both the trapped field and the levitation force of the Y-Ba-Cu-O disks are found to be strongly sensitive to the oxygen content.

  13. Cross Feedback Control of a Magnetic Bearing System: Controller Design Considering Gyroscopic Effects

    Science.gov (United States)

    Ahrens, Markus; Kucera, Ladislav

    1996-01-01

    For flywheel rotors or other rotors with significant ratios of moments of inertia, the influence of gyroscopic effects has to be considered. While conservative or damped systems remain stable even under gyroscopic effects, magnetically suspended rotors can be destabilized with increasing rotational speed. The influence of gyroscopic effects on the stability and behavior of a magnetic bearing system is analyzed. The analysis is carried out with a rigid body model for the rotor and a nonlinear model for the magnetic bearing and its amplifier. Cross feedback control can compensate gyroscopic effects. This compensation leads to better system performance and can avoid instability. Furthermore, the implementation of this compensation is simple. The main structure of a decentralized controller can still be used. It has only to be expanded by the cross feedback path.

  14. A Method for stability analysis of magnetic bearings : Basic stability criteria

    CERN Document Server

    Shayak, B

    2016-01-01

    In this work I outline a general procedure for dynamic modeling and stability analysis of a magnetic bearing, which is a rotating shaft confined inside a chamber through electromagnetic forces alone. I consider the simplest type of self-propelled bearing, namely a permanent magnet synchronous motor and an induction motor rotor freely suspended inside the corresponding stator, and having no eccentricity-fedback control algorithm. Writing Euler's equations for the rotor mechanics and Maxwell's equations for the electromagnetic field leads to a systematic technique for analysing the dynamics of the complete system. Physical arguments indicate that that two essential components for rotor confinement are a spatial gradient in the stator magnetic field and a torque angle lying in the second quadrant. These predictions are confirmed through the linear stability analysis. The direct practical utility of the results is mitigated by the presence of a repeated eigenvalue in the linearized equations. Despite this limitat...

  15. Axial magnetic bearing development for the BiVACOR rotary BiVAD/TAH.

    Science.gov (United States)

    Greatrex, Nicholas A; Timms, Daniel L; Kurita, Nobuyuki; Palmer, Edward W; Masuzawa, Toru

    2010-03-01

    A suspension system for the BiVACOR biventricular assist device (BiVAD) has been developed and tested. The device features two semi-open centrifugal impellers mounted on a common rotating hub. Flow balancing is achieved through the movement of the rotor in the axial direction. The rotor is suspended in the pump casings by an active magnetic suspension system in the axial direction and a passive hydrodynamic bearing in the radial direction. This paper investigates the axial movement capacity of the magnetic bearing system and the power consumption at various operating points. The force capacity of the passive hydrodynamic bearing is investigated using a viscous glycerol solution. Axial rotor movement in the range of +/-0.15 mm is confirmed and power consumption is under 15.5 W. The journal bearing is shown to stabilize the rotor in the radial direction at the required operating speed. Magnetic levitation is a viable suspension technique for the impeller of an artificial heart to improve device lifetime and reduce blood damage.

  16. A Comparison of Porous Structures on the Performance of a Magnetic Fluid Based Rough Short Bearing

    Directory of Open Access Journals (Sweden)

    J.R. Patel

    2013-09-01

    Full Text Available Efforts have been made ​​to study and analyze the comparison of variousporous structures on the performance of a magnetic fluid basedtransversely rough short bearing. The globular sphere model of Kozeny - Carman and Irmay's model of capillary fissures have been subjected to investigations. The transverse surface roughness of the bearing surfaces has been characterized by a stochastic random variable with non zero mean, variance and skewness. The stochastically averaged Reynolds type equation has been solved under suitable boundary conditions to obtain The pressure distribution in turn Which gives the expression for the load carrying capacity. It is found that the magnetization affects the bearing system positively while the bearing suffers owing to transverse roughness. This adverse effect is relatively less in the case of Kozeny - Carman model. The negatively skewed roughness induces an increase in Which load carrying capacity can be channelized to compensate the adverse effect of porosity , at least in the case of Kozeny - Carman model. This compensation in the case of Irmay's model is relatively less. The effect of magnetization responds more in the case of Kozeny - Carman model as compared to Irmay's model.

  17. Numerical analysis of fundamental characteristics of superconducting magnetic bearings for a polarization modulator

    Science.gov (United States)

    Terachi, Yusuke; Terao, Yutaka; Ohsaki, Hiroyuki; Sakurai, Yuki; Matsumura, Tomotake; Sugai, Hajime; Utsunomiya, Shin; Kataza, Hirokazu; Yamamoto, Ryo

    2017-07-01

    We have carried out numerical analysis of mechanical properties of a superconducting magnetic bearing (SMB). A contactless bearing operating at below 10 K with low rotational energy loss is an attractive feature to be used as a rotational mechanism of a polarization modulator for a cosmic microwave background experiment. In such application, a rotor diameter of about 400 mm forces us to employ a segmented magnet. As a result, there is inevitable spatial gap between the segments. In order to understand the path towards the design optimizations, 2D and 3D FEM analyses were carried out to examine fundamental characteristics of the SMBs for a polarization modulator. Two axial flux type SMBs were dealt with in the analysis: (a) the SMB with axially magnetized permanent magnets (PMs), and (b) the SMB with radially magnetized PMs and steel components for magnetic flux paths. Magnetic flux lines and density distributions, electromagnetic force characteristics, spring constants, etc. were compared among some variations of the SMBs. From the numerical analysis results, it is discussed what type, configuration and design of SMBs are more suitable for a polarization modulator.

  18. Radial forces in a centrifugal compressor; Experimental investigation by using magnetic bearings and static pressure distribution

    Science.gov (United States)

    Reunanen, Arttu; Larjola, Jaakko

    2005-03-01

    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.

  19. 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

    2005-01-01

    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.

  20. Synthesis and evaluation of radiolabeled, folic acid-PEG conjugated, amino silane coated magnetic nanoparticles in tumor bearing Balb/C mice

    Directory of Open Access Journals (Sweden)

    Razjouyan Javad

    2015-07-01

    Full Text Available To design a potent agent for positron emission tomography/magnetic resonance imaging (PET/MRI imaging and targeted magnetic hyperthermia-radioisotope cancer therapy radiolabeled surface modified superparamagnetic iron oxide nanoparticles (SPIONs were used as nanocarriers. Folic acid was conjugated for increasing selective cellular binding and internalization through receptor-mediated endocytosis. SPIONs were synthesized by the thermal decomposition of tris (acetylacetonato iron (III to achieve narrow and uniform nanoparticles. To increase the biocompatibility of SPIONs, they were coated with (3-aminopropyl triethoxysilane (APTES, and then conjugated with synthesized folic acid-polyethylene glycol (FA-PEG through amine group of (3-aminopropyl triethoxysilane. Finally, the particles were labeled with 64Cu (t1/2 = 12.7 h using 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid mono (N-hydroxy succinimide ester DOTA-NHS chelator. After the characterization of SPIONs, their cellular internalization was evaluated in folate receptor (FR overexpressing KB (established from a HeLa cell contamination and mouse fibroblast cell (MFB lines. Eventually, active and passive targeting effects of complex were assessed in KB tumor-bearing Balb/C mice through biodistribution studies. Synthesized bare SPIONs had low toxicity effect on healthy cells, but surface modification increased their biocompatibility. Moreover, KB cells viability was reduced when using folate conjugated SPIONs due to FR-mediated endocytosis, while having little effect on healthy cells (MFB. Moreover, this radiotracer had tolerable in vivo characteristics and tumor uptake. In the receptor blocked case, tumor uptake was decreased, indicating FR-specific uptake in tumor tissue while enhanced permeability and retention effect was major mechanism for tumor uptake.

  1. Control Study for Five-axis Dynamic Spin Rig Using Magnetic Bearings

    Science.gov (United States)

    Choi, Benjamin; Johnson, Dexter; Provenza, Andrew; Morrison, Carlos; Montague, Gerald

    2003-01-01

    The NASA Glenn Research Center (GRC) has developed a magnetic bearing system for the Dynamic Spin Rig (DSR) with a fully suspended shaft that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust magnetic bearing and the associated control system were integrated into the DSR to provide magnetic excitation as well as non-contact mag- netic suspension of a 15.88 kg (35 lb) vertical rotor with blades to induce turbomachinery blade vibration. For rotor levitation, a proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, more blade vibration amplitude, and energy savings for the system. The test results of a variety of controllers that were demonstrated up to 10.000 rpm are shown. Furthermore, rotor excitation operation and conceptual study of active blade vibration control are addressed.

  2. MATLAB WEB SERVER AND ITS APPLICATION IN REMOTE COLLABORATIVE DESIGN OF MAGNETIC BEARING SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Acclimatizing itself to the development of network,Math Works Inc constructed a MATLAB Web Server environment by dint of which one can browse the calculation and plots of MATLAB through Internet directly.The installation and use of the environment is introduced.A code established on the platform of MATLAB,which deals with the modal analysis of magnetic bearing system(MBS) supporting rotors of five degrees of freedom and considering the coupling of thrust bearing with radical bearings is modified to work in the environment.The purpose is to realize a remote call of the code by users through Internet for the performance analysis of the system.Such an application is very important to the concurrent design of MBS and for the utilization of distributive knowledge acquisition resources in collaborative design.The work on modification and realization is described and the results are discussed.

  3. Paleomagnetism and environmental magnetism of GLAD800 sediment cores from Bear Lake, Utah and Idaho

    Science.gov (United States)

    Heil, C.W.; King, J.W.; Rosenbaum, J.G.; Reynolds, R.L.; Colman, Steven M.

    2009-01-01

    A ???220,000-year record recovered in a 120-m-long sediment core from Bear Lake, Utah and Idaho, provides an opportunity to reconstruct climate change in the Great Basin and compare it with global climate records. Paleomagnetic data exhibit a geomagnetic feature that possibly occurred during the Laschamp excursion (ca. 40 ka). Although the feature does not exhibit excursional behavior (???40?? departure from the expected value), it might provide an additional age constraint for the sequence. Temporal changes in salinity, which are likely related to changes in freshwater input (mainly through the Bear River) or evaporation, are indicated by variations in mineral magnetic properties. These changes are represented by intervals with preserved detrital Fe-oxide minerals and with varying degrees of diagenetic alteration, including sulfidization. On the basis of these changes, the Bear Lake sequence is divided into seven mineral magnetic zones. The differing magnetic mineralogies among these zones reflect changes in deposition, preservation, and formation of magnetic phases related to factors such as lake level, river input, and water chemistry. The occurrence of greigite and pyrite in the lake sediments corresponds to periods of higher salinity. Pyrite is most abundant in intervals of highest salinity, suggesting that the extent of sulfidization is limited by the availability of SO42-. During MIS 2 (zone II), Bear Lake transgressed to capture the Bear River, resulting in deposition of glacially derived hematite-rich detritus from the Uinta Mountains. Millennial-scale variations in the hematite content of Bear Lake sediments during the last glacial maximum (zone II) resemble Dansgaard-Oeschger (D-O) oscillations and Heinrich events (within dating uncertainties), suggesting that the influence of millennial-scale climate oscillations can extend beyond the North Atlantic and influence climate of the Great Basin. The magnetic mineralogy of zones IV-VII (MIS 5, 6, and 7

  4. Magnetically coupled gear based drive mechanism for contactless continuous rotation using superconducting magnetic bearing below 10 K

    Science.gov (United States)

    Matsumura, T.; Sakurai, Y.; Kataza, H.; Utsunomiya, S.; Yamamoto, R.

    2016-11-01

    We present the design and mechanical performances of a magnetically coupled gear mechanism to drive a levitating rotor magnet of a superconducting magnetic bearing (SMB). The SMB consists of a ring-shaped high-temperature superconducting array (YBCO) and a ring-shaped permanent magnet. This rotational system is designed to operate below 10 K, and thus the design philosophy is to minimize any potential source of heat dissipation. While an SMB provides only a functionality of namely a bearing, it requires a mechanism to drive a rotational motion. We introduce a simple implementation of a magnetically coupled gears between a stator and a rotor. This enables to achieve enough torque to drive a levitating rotor without slip at the rotation frequency of about 1 Hz below 10 K. The rotational variation between the rotor and the drive gear is synchronised within σ = 0.019 Hz. The development of this mechanism is a part of the program to develop a testbed in order to evaluate a prototype half-wave plate based polarization modulator for future space missions. The successful development allows this modulator to be a candidate for an instrument to probe the cosmic inflation by measuring the cosmic microwave background polarization.

  5. Stabilizing Gyroscopic Modes in Magnetic-Bearing-Supported Flywheels by Using Cross-Axis Proportional Gains

    Science.gov (United States)

    Brown, Gerald V.; Kascak, Albert F.; Jansen, Ralph H.; Dever, Timothy P.; Duffy, Kirsten P.

    2006-01-01

    For magnetic-bearing-supported high-speed rotating machines with significant gyroscopic effects, it is necessary to stabilize forward and backward tilt whirling modes. Instability or low damping of these modes can prevent the attainment of desired shaft speed. We show analytically that both modes can be stabilized by using cross-axis proportional gains and high- and low-pass filters in the magnetic bearing controller. Furthermore, at high shaft speeds, where system phase lags degrade the stability of the forward-whirl mode, a phasor advance of the control signal can partially counteract the phase lag. In some range of high shaft speed, the derivative gain for the tilt modes (essential for stability for slowly rotating shafts) can be removed entirely. We show analytically how the tilt eigenvalues depend on shaft speed and on various controller feedback parameters.

  6. Active Magnetic Bearings Stiffness and Damping Identification from Frequency Characteristics of Control System

    Directory of Open Access Journals (Sweden)

    Chaowu Jin

    2016-01-01

    Full Text Available At present, the stiffness and damping identification for active magnetic bearings (AMBs are still in the stage of theoretical analysis. The theoretical analysis indicates that if the mechanical structure and system parameters are determined, AMBs stiffness and damping are only related to frequency characteristic of control system, ignoring operating condition. More importantly, few verification methods are proposed. Considering the shortcomings of the theoretical identification, this paper obtains these coefficients from the experiment by using the magnetic bearing as a sine exciter. The identification results show that AMBs stiffness and damping have a great relationship with the control system and rotating speed. Specifically, at low rotating speed, the stiffness and damping can be obtained from the rotor static suspension by adding the same excitation frequency. However, at high speed, different from the static suspension situation, the AMBs supporting coefficients are not only related to the frequency characteristics of control system, but also related to the system operating conditions.

  7. RESEARCH ON CONTROL OF FLYWHEEL SUSPENDED BY ACTIVE MAGNETIC BEARING SYSTEM WITH SIGNIFICANT GYROSCOPIC EFFECTS

    Institute of Scientific and Technical Information of China (English)

    Zhang Kai; Zhao Lei; Zhao Hongbin

    2004-01-01

    Traditional PID controllers are no longer suitable for magnetic-bearing-supported high-speed flywheels with significant gyroscopic effects.Because gyroscopic effects greatly influence the stability of the flywheel rotor,especially at high rotational speeds.Velocity cross feedback and displacement cross feedback are used to overcome harmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects.A control platform based on RTLinux and a PC is built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, the flywheel successfully runs at over 20 000 r/min.

  8. Influence of active magnetic bearing sensor location on the calculated critical speeds of turbomachinery

    OpenAIRE

    1989-01-01

    The calculation of critical speeds for turbomachinery with active magnetic bearings (AMBs) is of great interest due to the increasing number of applications of this new technology. The potential for increased turbomachine performance through improved AMB design has created the need for a more accurate method for predicting the system's undamped critical speeds. This thesis documents the development of a method which improves the accuracy of critical speed calculation by properl...

  9. Study on the Levitation and Restoring Force Characteristics of the Improved HTS-permanent Magnet Hybrid Magnetic Bearing

    Science.gov (United States)

    Sugiyama, R.; Oguni, K.; Ohashi, S.

    We have developed the hybrid magnetic bearing using permanent magnets and high temperature bulk super conductor (HTS). In this system, the permanent magnet has ring type structure so that the permanent magnet and the HTS can be set to the stator. The pinning force of the HTS is used for the levitation and the guidance. Repulsive force of the permanent magnets was used in the conventional hybrid system. However the restoring force in the guidance direction of the conventional hybrid system decreases by the side slip force of the permanent magnets. In this research, attractive force of permanent magnets is used for increasing the load weight in the guidance direction. In this paper, influence of the hybrid system on the static characteristics of the rotor is studied. Three-dimensional numerical analysis of the linkage flux (in the levitation and the guidance direction) in the HTS is undertaken. The stator side permanent magnet increases the linkage flux of the levitation direction. Therefore in the hybrid system the linkage flux of the levitation direction increases. The levitation and restoring force of the rotor is measured. The levitation force of the hybrid system becomes smaller than that of the non-hybrid one by attractive force. The rotor in the hybrid system is supported by the pinning force and attractive force. The restoring force of the hybrid system becomes larger than that of the non-hybrid one because of increasing the linkage flux of the levitation direction.

  10. Critical speeds and forced response solutions for active magnetic bearing turbomachinery, part 2

    Science.gov (United States)

    Rawal, D.; Keesee, J.; Kirk, R. Gordon

    1991-01-01

    The need for better performance of turbomachinery with active magnetic bearings has necessitated a study of such systems for accurate prediction of their vibrational characteristics. A modification of existing transfer matrix methods for rotor analysis is presented to predict the response of rotor systems with active magnetic bearings. The position of the magnetic bearing sensors is taken into account and the effect of changing sensor position on the vibrational characteristics of the rotor system is studied. The modified algorithm is validated using a simpler Jeffcott model described previously. The effect of changing from a rotating unbalance excitation to a constant excitation in a single plane is also studied. A typical eight stage centrifugal compressor rotor is analyzed using the modified transfer matrix code. The results for a two mass Jeffcott model were presented previously. The results obtained by running this model with the transfer matrix method were compared with the results of the Jeffcott analysis for the purposes of verification. Also included are plots of amplitude versus frequency for the eight stage centrifugal compressor rotor. These plots demonstrate the significant influence that sensor location has on the amplitude and critical frequencies of the rotor system.

  11. H Infinity Control of Magnetic Bearings to Ensure Both System and External Periodic Disturbance Robustness

    Science.gov (United States)

    Jiang, Yuhong; Zmood, R. B.

    1996-01-01

    Both self-excited and forced disturbances often lead to severe rotor vibrations in a magnetic bearing systems with long slender shafts. This problem has been studied using the H-infinity method, and stability with good robustness can be achieved for the linearized model of a magnetic bearing when small transient disturbances are applied. In this paper, the H-infinity control method for self-excited and forced disturbances is first reviewed. It is then applied to the control of a magnetic bearing rotor system. In modelling the system, the shaft is first discretized into 18 finite elements and then three levels of condensation are applied. This leads to a system with three masses and three compliant elements which can be described by six state variable coordinates. Simulation of the resultant system design has been performed at speeds up to 10,000 rpm. Disturbances in terms of different initial displacements, initial impulses, and external periodic inputs have been imposed. The simulation results show that good stability can be achieved under these different transient disturbances using the proposed controller while at the same time reducing the sensitivity to external periodic disturbances.

  12. Load test of Superconducting Magnetic Bearing for MW-class Flywheel Energy Storage System

    Science.gov (United States)

    Mukoyama, S.; Nakao, K.; Sakamoto, H.; Nagashima, K.; Ogata, M.; Yamashita, T.; Miyazaki, K.; Shimizu, H.; Sawamura, H.

    2017-07-01

    A flywheel energy storage system (FESS) stores electrical power as kinetic energy of a rotating flywheel rotor. Since the storage energy of the FESS is proportional to the weight of the rotor and the square of the rotating speed, the heavy weight and high speed rotor leads a FESS to a high power and a high capacity. However a conventional FESS limits in both the rotor weight and the rotating speed because of using mechanical bearings. A superconducting FESS (SFESS) utilizes a superconducting magnetic bearing (SMB) to levitate and rotate the flywheel rotor that has ton class weight and high speed rotation without mechanical contact. As the SFESS with 300 kW demonstrated at Mt. Komekura in Yamanashi prefecture, the SMB in the SFESS levitated the 4-ton rotor. The SMB consisted of a high temperature superconducting magnet (HTS magnet) and a HTS bulk, and utilized a repulsive force between the HTS magnet and the HTS bulk. The demonstration of the SFESS has been carried out successfully at Mt. Komekura. Now the next step development was started to aim a MW-class SFESS. The MW-class SFESS needs the SMB levitated and withstood a 10 ton-class load. This paper describes a design of the 10 ton-class SMB and the result of the load test of the developed SMB

  13. Optimization of an axial flow heart pump with active and passive magnetic bearings.

    Science.gov (United States)

    Glauser, Matthias; Jiang, Wei; Li, Guoxin; Lin, Zongli; Allaire, Paul E; Olson, Don

    2006-05-01

    Optimization of a magnetically suspended left ventricular assist device (LVAD) is crucial. We desire a totally implantable, long-life LVAD that delivers the necessary flow rate, pressure rise, and blood compatibility. By using a novel combination of passive and active magnetic bearings (AMBs), we have developed an axial flow LVAD prototype, the LEV-VAD, which provides an unobstructed blood flow path, preventing stagnation regions for the blood. Our current effort is focused on the optimization of the magnetic suspension system to allow for control of the AMB, minimizing its size and power consumption. The properties of the passive magnetic bearings and AMBs serve as parameter space, over which a cost function is minimized, subject to constraints such as suspension stability and sufficient disturbance rejection capabilities. The design process is expected to lead to the construction of a small prototype pump along with the necessary robust controller for the AMB. Sensitivity of the LVAD performance with respect to various design parameters is examined in-depth and an optimized, more compact LVAD prototype is designed.

  14. Wide area stabilization of a magnetic bearing using exact linearization; Genmitsuna senkeika ni yoru jiki jikuuke no koiki anteika

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, F.; Namerigawa, T.; Murata, T. [Kanazawa University, Ishikawa (Japan)

    1998-03-01

    An active magnetic bearing (AMB) is a bearing to suspend a rotor by magnetic forces without any contact. Feedback control is indispensable for a magnetic bearing, because it is essentially an unstable system. To design a feedback control system, a linear mathematical model of the plant is convenient, however the force of electromagnet is highly nonlinear. Then usually a linear approximation around the operating point is employed, but the obtained linearized model can not express the exact behavior of the system at any other operating points. In this paper, we discuss the wide area stabilization of magnetic bearing using exact linearization approach. At first, we derive a nonlinear mathematical model for a magnetic bearing, then we show this nonlinear system is belong to a class of exactly linearizable nonlinear systems. Next, by using exact linearization method, we transfer the nonlinear model of a magnetic bearing to a linear time invariant state model in spite of change of the operating point and the rotational speed of the rotor. Then we construct the state feedback control system by conventional LQ method. Finally, we evaluate the validity of our proposed method by experiment. 13 refs., 8 figs., 1 tab.

  15. Low loss pole configuration for multi-pole homopolar magnetic bearings

    Science.gov (United States)

    Blumenstock, Kenneth A. (Inventor); Hakun, Claef F. (Inventor)

    2001-01-01

    A new pole configuration for multi-pole homopolar bearings proposed in this invention reduces rotational losses caused by eddy-currents generated when non-uniform flux distributions exist along the rotor surfaces. The new homopolar magnetic bearing includes a stator with reduced pole-to-pole and exhibits a much more uniform rotor flux than with large pole-to-pole gaps. A pole feature called a pole-link is incorporated into the low-loss poles to provide a uniform pole-to-pole gap and a controlled path for pole-to-pole flux. In order to implement the low-loss pole configuration of magnetic bearings with small pole-to-pole gaps, a new stator configuration was developed to facilitate installation of coil windings. The stator was divided into sector shaped pieces, as many pieces as there are poles. Each sector-shaped pole-piece can be wound on a standard coil winding machine, and it is practical to wind precision layer wound coils. To achieve maximum actuation efficiency, it is desirable to use all the available space for the coil formed by the natural geometric configuration. Then, the coils can be wound in a tapered shape. After winding, the sectored-pole-pieces are installed into and fastened by bonding or other means, to a ring of material which encloses the sectored-pole-pieces, forming a complete stator.

  16. Carboxymethyl cellulose (CMC)-loaded Co-Cu doped manganese ferrite nanorods as a new dual-modal simultaneous contrast agent for magnetic resonance imaging and nanocarrier for drug delivery system

    Science.gov (United States)

    Abbasi Pour, Sajjad; Shaterian, Hamid Reza; Afradi, Mojgan; Yazdani-Elah-Abadi, Afshin

    2017-09-01

    We synthesized Co0.25Cu0.25Mn0.5Fe2O4@CMC (CCMFe2O4@CMC) nanorods as a new dual-modal simultaneous for magnetic resonance imaging contrast agent and nanocarrier for drug delivery system. Impact of CCMFe2O4@CMC nanorods were investigated on the longitudinal (T1), transverse (T2) and transverse (T2∗) relaxation times for in vitro MRI contrast agent in water and also for drug delivery system, L-dopa was coated on CCMFe2O4@CMC nanorods and then in vitro drug release test was carried out at three PHs values and different temperatures. In vitro MR imaging demonstrated that r2 value of CCMFe2O4@CMC nanorods is 138.33 mM-1 s-1, CCMFe2O4@CMC is useful as T2 contrast agent relative to other T2 contrast agants. In vitro drug release test shows the amount of released L-dopa from CCMFe2O4@CMC nanorods at medium with pH = 1.2 is more than pH = 5.3 and 7.4.

  17. Linear and Nonlinear Analysis of Magnetic Bearing Bandwidth Due to Eddy Current Limitations

    Science.gov (United States)

    Kenny, Andrew; Palazzolo, Alan

    2000-01-01

    Finite element analysis was used to study the bandwidth of alloy hyperco50a and silicon iron laminated rotors and stators in magnetic bearings. A three dimensional model was made of a heteropolar bearing in which all the flux circulated in the plane of the rotor and stator laminate. A three dimensional model of a plate similar to the region of a pole near the gap was also studied with a very fine mesh. Nonlinear time transient solutions for the net flux carried by the plate were compared to steady state time harmonic solutions. Both linear and quasi-nonlinear steady state time harmonic solutions were calculated and compared. The finite element solutions for power loss and flux bandwidth were compared to those determined from classical analytical solutions to Maxwell's equations.

  18. Cryogenic magnetic bearing scanning mechanism design for the SPICA/SAFARI Fourier transform spectrometer

    Science.gov (United States)

    van den Dool, Teun C.; Hamelinck, Roger F. M. M.; Kruizinga, Bob; Gielesen, Wim L. M.; Braam, Ben C.; Nijenhuis, Jan R.; Loix, Nicolas; Luyckx, Stanislas; van Loon, Dennis; Kooijman, Peter Paul; Swinyard, Bruce M.

    2010-07-01

    TNO, together with its partners Micromega and SRON, have designed a cryogenic scanning mechanism for use in the SAFARI Fourier Transform Spectrometer (FTS) on board of the SPICA mission. The optics of the FTS scanning mechanism (FTSM) consists of two back-to-back cat's-eyes. The optics are mounted on a central "back-bone" tube which houses all the important mechatronic parts: the magnetic bearing linear guiding system, a magnetic linear motor serving as the OPD actuator, internal metrology with nanometer resolution, and a launch lock. A magnetic bearing is employed to enable a large scanning stroke in a small volume. It supports the optics in a free-floating way with no friction, or other non-linearities, enabling sub-nanometer accuracy within a single stage with a stroke of -4 mm to +31.5 mm. Because the FTSM will be used at cryogenic temperatures of 4 Kelvin, the main structure and optics are all constructed from 6061 Aluminum. The overall outside dimensions of the FTSM are: 393 x 130 x 125 mm, and the mass is 2.2 kg.

  19. Design and optimization of an active magnetic thrust bearing for flyhweel energy storage systems

    Science.gov (United States)

    Lam, Siu Kiong

    2011-12-01

    This thesis is motivated in part by the lack of published research pertaining to active magnetic thrust bearings (AMTB), as compared to active magnetic radial bearings (AMRB). This thesis presents one method in implementing AMTBs to provide a near frictionless support to a rotor contained in a vacuum environment, mitigating the concerns of viscous drag and chemical reaction as a result of the exposure to lubricants. An analytical model was first developed to linearize the AMTB against a predefined operating point. A finite element simulation was subsequently conducted to verify the analytical model. The analytical and finite element methods both indicated that the steady state power consumption of the AMTB was approximately 12 W, and there was no occurrence of magnetic saturation within the material. The stress analysis showed that the stresses experienced by the rotor part of the AMTB as it rotated at the maximum rotation speed were well below the yield stress of the material. Lastly, a closed loop feedback network with proportional-integral-derivative (PID) controllers was designed and implemented as the control scheme for keeping the flywheel rotor at a predefined axial position, while the rotor underwent axial position variations due to the external disturbance, thermal expansion, or Poisson contraction effects. The resulting simulations showed that the PID controller was able to stabilize the flywheel rotor 0.3 s after it was disturbed by an external force equaling 10% of its weight.

  20. Dynamic characteristics of a flywheel energy storage system using superconducting magnetic bearings

    CERN Document Server

    Kim, J S

    2003-01-01

    The high-temperature superconducting magnetic bearing flywheel energy storage system (SMB-FESS) is proposed as an efficient energy storage system. It is important to identify the dynamic behaviour and the characteristics of the SMB-FESS. First, a new method for identifying SMB characteristics has been suggested. The suggested modelling method is verified by comparing the experimental and analytical frequency response functions. In this study, the analyses of critical speed and unbalance response are performed using the analytical model. The experimental test has been carried out to verify the result of simulation. A good agreement has been observed between the experiment and the simulation result.

  1. Control of Magnetic Bearings for Rotor Unbalance With Plug-In Time-Varying Resonators.

    Science.gov (United States)

    Kang, Christopher; Tsao, Tsu-Chin

    2016-01-01

    Rotor unbalance, common phenomenon of rotational systems, manifests itself as a periodic disturbance synchronized with the rotor's angular velocity. In active magnetic bearing (AMB) systems, feedback control is required to stabilize the open-loop unstable electromagnetic levitation. Further, feedback action can be added to suppress the repeatable runout but maintain closed-loop stability. In this paper, a plug-in time-varying resonator is designed by inverting cascaded notch filters. This formulation allows flexibility in designing the internal model for appropriate disturbance rejection. The plug-in structure ensures that stability can be maintained for varying rotor speeds. Experimental results of an AMB-rotor system are presented.

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

    Science.gov (United States)

    Pai, Chi Nan; Shinshi, Tadahiko

    2011-10-01

    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. Active Magnetic Bearing Online Levitation Recovery through μ-Synthesis Robust Control

    Directory of Open Access Journals (Sweden)

    Alexander H. Pesch

    2017-01-01

    Full Text Available A rotor supported on active magnetic bearings (AMBs is levitated inside an air gap by electromagnets controlled in feedback. In the event of momentary loss of levitation due to an acute exogenous disturbance or external fault, reestablishing levitation may be prevented by unbalanced forces, contact forces, and the rotor’s dynamics. A novel robust control strategy is proposed for ensuring levitation recovery. The proposed strategy utilizes model-based μ-synthesis to find the requisite AMB control law with unique provisions to account for the contact forces and to prevent control effort saturation at the large deflections that occur during levitation failure. The proposed strategy is demonstrated experimentally with an AMB test rig. First, rotor drop tests are performed to tune a simple touchdown-bearing model. That model is then used to identify a performance weight, which bounds the contact forces during controller synthesis. Then, levitation recovery trials are conducted at 1000 and 2000 RPM, in which current to the AMB coils is momentarily stopped, representing an external fault. The motor is allowed to drive the rotor on the touchdown bearings until coil current is restored. For both cases, the proposed control strategy shows a marked improvement in relevitation transients.

  4. Modeling and Analysis of Coupling Performance of Dynamic Stiffness Models for a Novel Combined Radial-Axial Hybrid Magnetic Bearing

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2014-01-01

    Full Text Available The combined radial-axial magnetic bearing (CRAMB with permanent magnet creating bias flux can reduce the size, cost, and mass and save energy of the magnetic bearing. The CRAMB have three-degree-of-freedom control ability, so its structure and magnetic circuits are more complicated compared to those of the axial magnetic bearing (AMB or radial magnetic bearing (RMB. And the eddy currents have a fundamental impact on the dynamic performance of the CRAMB. The dynamic stiffness model and its cross coupling problems between different degrees of freedom affected for the CRAMB are proposed in this paper. The dynamic current stiffness and the dynamic displacement stiffness models of the CRAMB are deduced by using the method of equivalent magnetic circuit including eddy current effect, but the dynamic current stiffness of the RMB unit is approximately equal to its static current stiffness. The analytical results of an example show that the bandwidth of the dynamic current stiffness of the AMB unit and the dynamic displacement stiffness of the CRAMB is affected by the time-varying control currents or air gap, respectively. And the dynamic current stiffness and the dynamic displacement stiffness between the AMB unit and the RMB unit are decoupled due to few coupling coefficients.

  5. Field cooling of a MgB{sub 2} cylinder around a permanent magnet stack: prototype for superconductive magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Perini, E; Giunchi, G [EDISON S.p.A., R and D Division, Foro Buonaparte 31, 20121 Milano (Italy)], E-mail: elena.perini@edison.it, E-mail: giovanni.giunchi@edison.it

    2009-04-15

    The behaviour of bulk superconductors as levitators of permanent magnets (PMs) has been extensively studied for the textured YBCO high-temperature superconductor material, in the temperature range lower than 77 K, obtaining extremely high trapped fields but also experiencing limitations on the mechanical characteristics of the material and on the possibility to produce large objects. Alternatively, bulk MgB{sub 2}, even if it is superconducting at lower temperatures, has fewer mechanical problems, when fully densified, and presents stable magnetization in the temperature range between 10 and 30 K. With the reactive Mg-liquid infiltration technique we have produced dense MgB{sub 2} bulk cylinders of up to 65 mm diameter and 100 mm height. This kind of cylinder can be consider as a prototype of a passive magnetic bearing for flywheels or other rotating electrical machines. We have conductively cooled one of these superconducting cylinders inside a specially constructed cryostat, and the levitation forces and stiffness, with respect to axial movements of various arrangements of the PM, have been measured as a function of the temperature below T{sub c}. We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

  6. Field cooling of a MgB2 cylinder around a permanent magnet stack: prototype for superconductive magnetic bearing

    Science.gov (United States)

    Perini, E.; Giunchi, G.

    2009-04-01

    The behaviour of bulk superconductors as levitators of permanent magnets (PMs) has been extensively studied for the textured YBCO high-temperature superconductor material, in the temperature range lower than 77 K, obtaining extremely high trapped fields but also experiencing limitations on the mechanical characteristics of the material and on the possibility to produce large objects. Alternatively, bulk MgB2, even if it is superconducting at lower temperatures, has fewer mechanical problems, when fully densified, and presents stable magnetization in the temperature range between 10 and 30 K. With the reactive Mg-liquid infiltration technique we have produced dense MgB2 bulk cylinders of up to 65 mm diameter and 100 mm height. This kind of cylinder can be consider as a prototype of a passive magnetic bearing for flywheels or other rotating electrical machines. We have conductively cooled one of these superconducting cylinders inside a specially constructed cryostat, and the levitation forces and stiffness, with respect to axial movements of various arrangements of the PM, have been measured as a function of the temperature below Tc. We verified the very stable characteristics of the induced magnetization after several cycles of relative movements of the PM and the superconducting cylinder.

  7. Design and parameter estimation of hybrid magnetic bearings for blood pump applications

    Science.gov (United States)

    Lim, Tau Meng; Zhang, Dongsheng; Yang, Juanjuan; Cheng, Shanbao; Low, Sze Hsien; Chua, Leok Poh; Wu, Xiaowei

    2009-10-01

    This paper discusses the design and parameter estimation of the dynamics characteristics of a high-speed hybrid magnetic bearings (HMBs) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet (PM) brushless and sensorless DC motor. It is levitated by two HMBs at both ends in five-degree-of-freedom with proportional-integral-derivative (PID) controllers; among which four radial directions are actively controlled and one axial direction is passively controlled. Test results show that the rotor can be stably supported to speeds of 14,000 rpm. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMBs system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air—in both the radial and axial directions. The radial stiffness of the HMBs is compared to the Ansoft's Maxwell 2D/3D finite element magnetostatic results. Experimental estimation showed that the dynamics characteristics of the HMBs system are dominated by the frequency-dependent stiffness coefficients. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamics properties under normal operating conditions with fluid.

  8. Fractional Order PID Control of Rotor Suspension by Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Parinya Anantachaisilp

    2017-01-01

    Full Text Available One of the key issues in control design for Active Magnetic Bearing (AMB systems is the tradeoff between the simplicity of the controller structure and the performance of the closed-loop system. To achieve this tradeoff, this paper proposes the design of a fractional order Proportional-Integral-Derivative (FOPID controller. The FOPID controller consists of only two additional parameters in comparison with a conventional PID controller. The feasibility of FOPID for AMB systems is investigated for rotor suspension in both the radial and axial directions. Tuning methods are developed based on the evolutionary algorithms for searching the optimal values of the controller parameters. The resulting FOPID controllers are then tested and compared with a conventional PID controller, as well as with some advanced controllers such as Linear Quadratic Gausian (LQG and H ∞ controllers. The comparison is made in terms of various stability and robustness specifications, as well as the dimensions of the controllers as implemented. Lastly, to validate the proposed method, experimental testing is carried out on a single-stage centrifugal compressor test rig equipped with magnetic bearings. The results show that, with a proper selection of gains and fractional orders, the performance of the resulting FOPID is similar to those of the advanced controllers.

  9. Damping control for the vibration in a magnetic bearing using the selective turn-over method

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Fumio; Fujita, Masayuki; Oida, Chikashi; Higashida, Akira

    1988-01-20

    The report presents a device that uses the selective turn-over method to simultaneously achieve stability leviation and shaft vibration damping in a magnetic bearing. The device is applied to a radial-thrust simultaneous control type magnetic bearing that incorporates four pairs (total of eight) of electromagnets to perform control for all of the five degrees of freedom. A mathematical model is developed to simulate the rotor's motions including asymmetric motions. The device employs the Robust servomechanism. For stabilization, the selective turn-over method is used which is higher in accuracy and performance than the ordinary turn-over method that has been conventionally used for stabilization. This permits control of both shaft vibration damping and stability levitation. The stability of levitation and the damping of shaft vibration are investigated at 1,900 rpm, and results obtained are compared with those made with an integral type optimal regulating method. It is demonstrated that the control device using the selective turn-over method has high performance as a servomechanism. (12 figs, 8 refs)

  10. An active homopolar magnetic bearing with high temperature superconductor (HTS) coils and ferromagnetic cores

    Science.gov (United States)

    Brown, G. V.; Dirusso, E.; Provenza, A. J.

    1995-01-01

    A proof-of-feasibility demonstration showed that high temperature superconductor (HTS) coils can be used in a high-load, active magnetic bearing in liquid nitrogen. A homopolar radial bearing with commercially wound HTS (Bi 2223) bias and control coils produced over 200 lb (890 N) radial load capacity (measured non-rotating) and supported a shaft to 14000 rpm. The goal was to show that HTS coils can operate stably with ferromagnetic cores in a feedback controlled system at a current density similar to that in Cu in liquid nitrogen. Design compromises permitted use of circular coils with rectangular cross section. Conductor improvements will eventually permit coil shape optimization, higher current density and higher bearing load capacity. The bias coil, wound with non-twisted, multifilament HTS conductor, required negligible power to carry its direct current. The control coils were wound with monofilament HTS sheathed in Ag. These dissipated negligible power for direct current (i.e. for steady radial load components). When an alternating current (AC) was added, the AC component dissipated power which increased rapidly with frequency and quadratically with AC amplitude. In fact at frequencies above about 2 hz, the effective resistance of the control coil conductor actually exceeds that of the silver which is in electrical parallel with the oxide superconductor. This is at least qualitatively understandable in the context of a Bean-type model of flux and current penetration into a Type II superconductor. Fortunately the dynamic currents required for bearing stability are of small amplitude. These results show that while twisted multifilament conductor is not needed for stable levitation, twisted multifilaments will be required to reduce control power for sizable dynamic loads, such as those due to unbalance.

  11. Lumbar stenosis rates in symptomatic patients using weight-bearing and recumbent magnetic resonance imaging.

    Science.gov (United States)

    Gilbert, John W; Martin, J Chad; Wheeler, Greg R; Storey, Benjamin B; Mick, Gregory E; Richardson, Gay B; Herder, Stephanie L; Gyarteng-Dakwa, Kwadwo

    2011-10-01

    The purpose of this study was to determine the rate of lumbar stenosis detected via magnetic resonance imaging (MRI) in patients with symptomatic foraminal stenosis, lateral recess stenosis, or central stenosis. A retrospective review was performed on 1983 MRI scans from a 2-year period on 1486 symptomatic patients. Of these patients, 761 were scanned in the recumbent position using low-field (0.3 T, Airis II; Hitachi, Twinsburg, Ohio) MRI, and 725 were scanned in an upright sitting position using midfield (0.6 T) open Upright MRI (Fonar Corp, Melville, NY). In total, 986 serial scans (recumbent) and 997 serial scans (weight-bearing) were performed. Of scans performed in the recumbent position, stenoses were identified in 382 scans (38.8%), central stenosis in 119 scans (12%), lateral recess stenosis in 91 scans (9.2%), and foraminal stenosis in 327 scans (33.2%). Of scans performed in a weight-bearing position, stenoses were identified in 565 scans (56.7%), central stenosis in 136 scans (13.6%), lateral recess stenosis in 206 scans (20.7%), and foraminal stenosis in 524 scans (52.6%). The stenosis rates as indicated by MRI interpretation ranged between 38.5% (recumbent) and 56.7% (weight-bearing). These rates are higher than those reported in the medical literature for asymptomatic patients. Further study is needed to determine whether weight-bearing, compared with recumbent, MRI better informs the clinician in the diagnosis of spinal stenosis. Copyright © 2011 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

  12. Testing of a centrifugal blood pump with a high efficiency hybrid magnetic bearing.

    Science.gov (United States)

    Locke, Dennis H; Swanson, Erik S; Walton, James F; Willis, John P; Heshmat, Hooshang

    2003-01-01

    The purpose of this article is to present test results for a second generation, high efficiency, nonpulsatile centrifugal blood pump that is being developed for use as a left ventricular assist device (LVAD). The LVAD pump uses a hybrid passive-active magnetic bearing support system that exhibits extremely low power loss, low vibration, and high reliability under transient conditions and varying pump orientations. A unique feature of the second generation design configuration is the very simple and direct flow path for both main and washing blood flows. The pump was tested in both vertical and horizontal orientations using a standard flow loop to demonstrate the performance and durability of the second generation LVAD. Steady state and transient orientation pump operating characteristics including pressure, flow, speed, temperatures, vibration, and rotor orientation were measured. During the tests, pump performance was mapped at several operating conditions including points above and below the nominal design of 5 L/min at 100 mm Hg pressure rise. Flow rates from 2 to 7 L/min and pressure rises from 50 to 150 mm Hg were measured. Pump speeds were varied during these tests from 2,500 to 3,500 rpm. The nominal design flow of 5 L/min at 100 mm Hg pressure rise was successfully achieved at the design speed of 3,000 rpm. After LVAD performance testing, both 28 day continuous duty and 5 day transient orientation durability tests were completed without incident. A hydrodynamic backup bearing design feasibility study was also conducted. Results from this design study indicate that an integral hydrodynamic backup bearing may be readily incorporated into the second generation LVAD and other magnetically levitated pump rotors.

  13. Application of textured YBCO bulks with artificial holes for superconducting magnetic bearing

    Science.gov (United States)

    Dias, D. H. N.; Sotelo, G. G.; Moysés, L. A.; Telles, L. G. T.; Bernstein, P.; Kenfaui, D.; Aburas, M.; Chaud, X.; Noudem, J. G.

    2015-07-01

    The levitation force between a superconductor and a permanent magnet has been investigated for the development of superconducting magnetic bearings (SMBs). Depending on the proposed application, the SMBs can be arranged with two kinds of symmetries: rotational or linear. The SMBs present passive operation, low level of noise and no friction, but they need a cooling system for their operation. Nowadays the cooling problem may be easily solved by the use of a commercial cryocooler. The levitation force of SMBs is directly related to the quality of the superconductor material (which depends on its critical current density) and the permanent magnet arrangement. Also, research about the YBa2Cu3Ox (Y123) bulk materials has shown that artificial holes enhance the superconducting properties, in particular the magnetic trapped field. In this context, this work proposes the investigation of the levitation force of a bulk Y123 sample with multiple holes and the comparison of its performances with those of conventional plain Y123 superconductors.

  14. Improvement of the levitation stability of the HTSC-permanent magnet hybrid bearing by using the new arrangement of the permanent magnet

    Science.gov (United States)

    Sukedaia, M.; Emoto, K.; Sugiyama, R.; Ohashi, S.

    The hybrid magnetic bearing using permanent magnets and the high temperature superconductor (HTSC) has been developed. Repulsive force of the permanent magnet is introduced to increase the load weight of the magnetic bearing. Effect of the hybrid system has been shown. Although the previous configuration improves the load weight of the rotor, levitation and guidance stability has been decreased because of the repulsive force of the permanent magnet. Three-dimensional numerical analysis of the system has been undertaken to reduce lateral force which decreases lateral stability of the rotor. From the results, effective arrangement of the hybrid system is given. Increment of the load weight is confirmed. Influence of the hybrid system on the pinning force between the HTSC and the permanent magnet is shown to be smaller than previous one.

  15. Design and Mathematical Analysis of a Novel Reluctance Force-Type Hybrid Magnetic Bearing for Flywheel with Gimballing Capability

    Directory of Open Access Journals (Sweden)

    Chun'e Wang

    2013-01-01

    Full Text Available Magnetically suspended flywheel (MSFW with gimballing capability fulfills requirements of precision and maneuvers for space applications. A novel reluctance force-type hybrid magnetic bearing (RFHMB is presented based on analysis of demerits of Lorentz force-type magnetic bearing and common RFHMB. It features that radial and axial magnetic bearing units are integrated into a compact assembly with four separate biased permanent magnets and two conical stators; four radial poles with shoes and rotor made of iron-based amorphousness can reduce eddy loss. Equivalent magnetic circuits of permanent magnets and their control currents are presented. Simulation results indicate flux density fluctuates from 0.272 T to 0.41 T; rotor tilting does not affect the suspension force when rotor only tilts around X-axis or Y-axis. When rotor drifts in X, Y, or Z direction and tilts around X-axis or Y-axis simultaneously, force in corresponding directions slightly increases with tilting angle’s enlargement, but the maximum change does not exceed 14%. Additional tilting torque mainly determined by uniformity of flux density in conical air gaps is 0.05 Nm which is far smaller than 11 Nm in common RFHMB; magnetic suspension force is effectively decoupled among X, Y, and Z directions; results prove that MSFW with gimballing capability theoretically meets maneuvering requirement of spacecraft.

  16. Robust and real-time control of magnetic bearings for space engines

    Science.gov (United States)

    Sinha, Alok; Wang, Kon-Well; Mease, K.; Lewis, S.

    1991-01-01

    Currently, NASA Lewis Research Center is developing magnetic bearings for Space Shuttle Main Engine (SSME) turbopumps. The control algorithms which have been used are based on either the proportional-intergral-derivative control (PID) approach or the linear quadratic (LQ) state space approach. These approaches lead to an acceptable performance only when the system model is accurately known, which is seldom true in practice. For example, the rotor eccentricity, which is a major source of vibration at high speeds, cannot be predicted accurately. Furthermore, the dynamics of a rotor shaft, which must be treated as a flexible system to model the elastic rotor shaft, is infinite dimensional in theory and the controller can only be developed on the basis of a finite number of modes. Therefore, the development of the control system is further complicated by the possibility of closed loop system instability because of residual or uncontrolled modes, the so called spillover problem. Consequently, novel control algorithms for magnetic bearings are being developed to be robust to inevitable parametric uncertainties, external disturbances, spillover phenomenon and noise. Also, as pointed out earlier, magnetic bearings must exhibit good performance at a speed over 30,000 rpm. This implies that the sampling period available for the design of a digital control system has to be of the order of 0.5 milli-seconds. Therefore, feedback coefficients and other required controller parameters have to be computed off-line so that the on-line computational burden is extremely small. The development of the robust and real-time control algorithms is based on the sliding mode control theory. In this method, a dynamic system is made to move along a manifold of sliding hyperplanes to the origin of the state space. The number of sliding hyperplanes equals that of actuators. The sliding mode controller has two parts; linear state feedback and nonlinear terms. The nonlinear terms guarantee that the

  17. Research on the Architecture of the CAD System of a Magnetic Bearing Based on Pattern-oriented

    Institute of Scientific and Technical Information of China (English)

    CHEN Rui-qing; SUN Yan-hua; CHEN Jian-bin; YU Lie

    2006-01-01

    The architecture of the CAD system of a magnetic bearing is established by using pattern-oriented software architecture.Based on the pipe-filter pattern, all the present resources come from different developing environments, aiding the design of a magnetic bearing system, can be integrated into the system. Replacing the original pipes with database, the concurrent design can be realized in the design process,which changes the serial mode of traditional manufacture.The distributed and heterogeneous design resources can be integrated into the system and shared by importing the broker pattern. Combining pipe-filter pattern with broker pattern, the system is opening and easy to maintain and extend.

  18. Vibrational characteristics of a superconducting magnetic bearing employed for a prototype polarization modulator

    Science.gov (United States)

    Sakurai, Yuki; Matsumura, Tomotake; Sugai, Hajime; Katayama, Nobuhiko; Ohsaki, Hiroyuki; Terao, Yutaka; Terachi, Yusuke; Kataza, Hirokazu; Utsunomiya, Shin; Yamamoto, Ryo

    2017-07-01

    We present the vibrational characteristics of a levitating rotor in a superconducting magnetic bearing (SMB) system operating at below 10 K. We develop a polarization modulator that requires a continuously rotating optical element, called half-wave plate (HWP), for a cosmic microwave background polarization experiment. The HWP has to operate at the temperature below 10 K, and thus an SMB provides a smooth rotation of the HWP at the cryogenic temperature of about 10 K with minimal heat dissipation. In order to understand the potential interference to the cosmological observations due to the vibration of the HWP, it is essential to characterize the vibrational properties of the levitating rotor of the SMB. We constructed a prototype model that consists of an SMB with an array of high temperature superconductors, YBCO, and a permanent magnet ring, NdFeB. The rotor position is monitored by a laser displacement gauge, and a cryogenic Hall sensor via the magnetic field. In this presentation, we present the measurement results of the vibration characteristics using our prototype SMB system. We characterize the vibrational properties as the spring constant and the damping, and discuss the projected performance of this technology toward the use in future space missions.

  19. Positional pelvic organ prolapse (POP) evaluation using open, weight-bearing magnetic resonance imaging (MRI).

    Science.gov (United States)

    Friedman, Boris; Stothers, Lynn; Lazare, Darren; Macnab, Andrew

    2015-01-01

    Magnetic resonance imaging (MRI) of patients with pelvic organ prolapse (POP) is completed in the supine position. Open magnetic resonance imaging (MRO) uses vertical magnets, allowing imaging in a variety of upright postures. This pilot study used MRO to evaluate the change of prolapse in different positions compared to non-prolapsed images. In total, 11 women (6 POP, 5 controls) aged 24 to 65 years had 12 MRO images (midline sagittal pelvic line) consecutively when supine, sitting and standing with a full and empty bladder. Lengths between the lowest point of the bladder to the pubococcygeal (PC) and pubopromontoreal (PP) lines in each image were compared, and the ratio of bladder area under the PC and PP lines to the total bladder area. Significant elongation between the PC line and lowest point of the bladder was evident in subjects with POP comparing supine and standing images (p = 0.03), but not controls (p = 0.07). Similarly, this axis was significantly longer in cystocele subjects versus controls only in the standing position. Bladder area under the PC line was significantly increased between supine and standing positions only among subjects with cystocele (p bearing on the staging of POP. Imaging patients when sitting and standing identified that significant changes occur in the maximal descent of the bladder.

  20. Multi-objective optimization design of a high-speed PM machine supported by magnetic bearings

    Science.gov (United States)

    Han, Bangcheng; Xue, Qinghao; Liu, Xu; Wang, Kun

    2017-08-01

    This paper proposes an optimal design method of permanent magnet machine (PMM) with cylindrical permanent magnet supported by magnetic bearings. The objectives of optimization design are minimizing the rotor loss while maximizing the power density of the PMM as well as the 1st order nature frequency of the rotor, and the constraints are size, the strength safety factor and the phase current. A 30 kW, 48,000 r/min PMM designed by the multi-objective optimization method is proposed and the results indicate: the rotor loss is decreased from 393 W to 290 W (is reduced by 26.2%); the power density of the PMM is increased from 1.86 kW/kg to 2.19 kW/kg (is increased by 17.7%); the 1st order nature frequency of the rotor is increased from 1579 Hz to 1812 Hz (is increased by 14.7%). The performances of the PMM are improved after optimization, which are verified by experiment.

  1. A novel integrated 4-DOF radial hybrid magnetic bearing for MSCMG

    Science.gov (United States)

    Jinji, Sun; Ziyan, Ju; Weitao, Han; Gang, Liu

    2017-01-01

    This paper proposes a novel integrated radial hybrid magnetic bearing (RHMB) for application with the small-sized magnetically suspended control moment gyroscope (MSCMG), which can control four degrees of freedom (4-DOFs), including two radial translational DOFs and two radial tilting DOFs, and provide the axial passive resilience. The configuration and working principle of the RHMB are introduced. Mathematical models of radial force, axial resilience and moment are established by using equivalent magnetic circuit method (EMCM), from which the radial force-radial displacement, radial force-current relationships are derived, as well as axial resilience-axial displacement, moment-tilting angle and moment-current. Finite element method (FEM) is also applied to analyze the performance and characteristics of the RHMB. The analysis results are in good agreement with that calculated by the EMCM, which is helpful in designing, optimizing and controlling the RHMB. The comparisons between the performances of the integrated 4-DOF RHMB and the traditional 4-DOF RHMB are made. The contrast results indicate that the proposed integrated 4-DOF RHMB possesses better performance compared to the traditional structure, such as copper loss, current stiffness, and tilting current stiffness.

  2. Bifurcation onset delay in magnetic bearing systems by time varying stiffness

    Science.gov (United States)

    Ghazavi, M. R.; Sun, Q.

    2017-06-01

    We study the nonlinear dynamics behaviours of a rigid rotor supported by magnetic bearings. In particular, we consider the effect of rotor unbalanced mass and geometric coupling. Existing works in literature have mostly focused on a single value of parameter or a smaller range of the nonlinearities introduced by rotor imbalance and geometric coupling. This is partly due to the use of a linear PD controller which limits the system performance. In this paper, we use a nonlinear PD controller by adopting a time varying stiffness term. The control gains are chosen according to the stability chart for a Mathieu's equation. Consequently, we observe a delay in the onset of bifurcation indicating an improved rotor performance.

  3. Development of a cryogenic induction motor for use with a superconducting magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Matsumura, Tomotake [School of Physics and Astronomy, University of Minnesota, Twin Cities, MN 55455 (United States)]. E-mail: tmatsumu@physics.umn.edu; Hanany, Shaul [School of Physics and Astronomy, University of Minnesota, Twin Cities, MN 55455 (United States); Hull, John R. [Energy Technology Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Johnson, Bradley [Cardiff University, 5 The Parade, Queens Buildings Cardiff, CF24 3YB (United Kingdom); Jones, Terry [School of Physics and Astronomy, University of Minnesota, Twin Cities, MN 55455 (United States); Oxley, Paul K. [School of Physics and Astronomy, University of Minnesota, Twin Cities, MN 55455 (United States)

    2005-10-01

    We have constructed a cryogenic induction motor to turn the rotor of a superconducting magnetic bearing (SMB). Both the motor and the SMB are operated at liquid He temperatures. We give a model for the motor and present measurements of its operation. The rotation speed is very stable. Over 8 h it shows an RMS variation of only 0.005 Hz from a mean of 2 Hz. The speed variation within one period of rotation is 3% {+-} 1% implying that the angular position of the rotor can be determined to an accuracy of 1 deg. for all angles of rotation even if angular position is encoded only once every period. Friction and heat dissipation in this motor is dominated by eddy currents. We discuss the application of the motor to astrophysical polarimetry.

  4. Development of a cryogenic induction motor for use with a superconducting magnetic bearing

    Science.gov (United States)

    Matsumura, Tomotake; Hanany, Shaul; Hull, John R.; Johnson, Bradley; Jones, Terry; Oxley, Paul K.

    2005-10-01

    We have constructed a cryogenic induction motor to turn the rotor of a superconducting magnetic bearing (SMB). Both the motor and the SMB are operated at liquid He temperatures. We give a model for the motor and present measurements of its operation. The rotation speed is very stable. Over 8 h it shows an RMS variation of only 0.005 Hz from a mean of 2 Hz. The speed variation within one period of rotation is 3% ± 1% implying that the angular position of the rotor can be determined to an accuracy of 1° for all angles of rotation even if angular position is encoded only once every period. Friction and heat dissipation in this motor is dominated by eddy currents. We discuss the application of the motor to astrophysical polarimetry.

  5. 5th workshop 'Magnetic bearings'. Proceedings; 5. Workshop Magnetlagertechnik. Tagungsband

    Energy Technology Data Exchange (ETDEWEB)

    Gaertner, S.; Rottenbach, T. (comps.)

    2001-07-01

    The workshop investigated the state of the art of magnetic bearings and their applications. It was attended by experts from industry, research institutions and universities who took the chance to exchange their experience and keep abreast of new developments. The proceedings volume contains all papers presented at the meeting, in chronological order. [German] Der Workshop stellt sich zur Aufgabe, sowohl die Fortschritte in Forschung und Entwicklung in der Magnetlagertechnik aufzuzeigen als auch den Stand der Technik an speziellen Anwendungen darzustellen. Die Veranstaltung versteht sich als Forum fuer Forscher und Anwender aus der Industrie, industriellen Forschungseinrichtungen sowie Universitaeten und Hochschulen. Daher steht der Erfahrungsaustausch zwischen Entwicklern, Herstellern und Betreibern im Mittelpunkt. Interessierte Fachleute aus Wissenschaft und Industrie haben hier die Moeglichkeit, sich ueber die Grundlagen, Einsatzmoeglichkeiten und Anwendungsgebiete der Magnetlagertechnologie zu informieren. Im vorliegenden Tagungsband sind die von den Autoren eingereichten Beitraege in der Reihenfolge des Tagungsprogramms wiedergegeben. (orig.)

  6. Predictions of Unbalanced Response of Turbo Compressor Equipped with Active Magnetic Bearings through System Identification

    Energy Technology Data Exchange (ETDEWEB)

    Baek, SeongKi; NOh, Myounggyu; Park, Young Woo [Chungnam National Univ., Daejeon (Korea, Republic of); Lee, Kiwook; Lee, Nam Soo; Jeog, Jinhee [LG Electronics, Gumi (Korea, Republic of)

    2016-01-15

    Since vibrations in rotating machinery is a direct cause of performance degradation and failures, it is very important to predict the level of vibrations as well as have a method to lower the vibrations to an acceptable level. However, the changes in balancing during installation and the vibrational modes of the support structure are difficult to predict. This paper presents a method for predicting the unbalanced response of a turbo-compressor supported by active magnetic bearings (AMBs). Transfer functions of the rotor are obtained through system identification using AMBs. These transfer functions contain not only the dynamics of the rotor but also the vibrational modes of the support structure. Using these transfer functions, the unbalanced response is calculated and compared with the run-up data obtained from a compressor prototype. The predictions revealed the effects of the support structure, validating the efficacy of the method.

  7. Active Magnetic Bearing Rotor Model Updating Using Resonance and MAC Error

    Directory of Open Access Journals (Sweden)

    Yuanping Xu

    2015-01-01

    Full Text Available Modern control techniques can improve the performance and robustness of a rotor active magnetic bearing (AMB system. Since those control methods usually rely on system models, it is important to obtain a precise rotor AMB analytical model. However, the interference fits and shrink effects of rotor AMB cause inaccuracy to the final system model. In this paper, an experiment based model updating method is proposed to improve the accuracy of the finite element (FE model used in a rotor AMB system. Modelling error is minimized by applying a numerical optimization Nelder-Mead simplex algorithm to properly adjust FE model parameters. Both the error resonance frequencies and modal assurance criterion (MAC values are minimized simultaneously to account for the rotor natural frequencies as well as for the mode shapes. Verification of the updated rotor model is performed by comparing the experimental and analytical frequency response. The close agreements demonstrate the effectiveness of the proposed model updating methodology.

  8. Active magnetic bearings dynamic parameters identification from experimental rotor unbalance response

    Science.gov (United States)

    Xu, Yuanping; Zhou, Jin; Di, Long; Zhao, Chen

    2017-01-01

    Active magnetic bearings (AMBs) support rotors using electromagnetic force rather than mechanical forces. It is necessary to accurately identify the AMBs force coefficients since they play a critical role in the rotordynamic analysis including system stability, bending critical speeds and modes of vibrations. This paper proposes a rotor unbalance response based approach to identifying the AMBs stiffness and damping coefficients during rotation. First, a Timoshenko beam finite element (FE) rotor model is created. Second, an identification procedure based on the FE model is proposed. Then based on the experimental rotor unbalance response data from 1200 rpm to 30,000 rpm, the AMBs dynamic force parameters (stiffness and damping) are obtained. Finally, the identified results are verified by comparing the estimated and experimental rotor unbalance responses, which shows high accuracy.

  9. FPGA-Based Digital Current Switching Power Amplifiers Used in Magnetic Bearing Systems

    Science.gov (United States)

    Wang, Yin; Zhang, Kai; Dong, Jinping

    For a traditional two-level current switching power amplifier (PA) used in a magnetic bearing system, its current ripple is obvious. To increase its current ripple performance, three-level amplifiers are designed and their current control is generally based on analog and logical circuits. So the required hardware is complex and a performance increase from the hardware adjustment is difficult. To solve this problem, a FPGA-based digital current switching power amplifier (DCSPA) was designed. Its current ripple was obviously smaller than a two-level amplifier and its control circuit was much simpler than a tri-level amplifier with an analog control circuit. Because of the field-programmable capability of a FPGA chip used, different control algorithms including complex nonlinear algorithms could be easily implemented in the amplifier and their effects could be compared with the same hardware.

  10. Active magnetic bearing control loop modeling for a finite element rotordynamics code

    Science.gov (United States)

    Genta, Giancarlo; Delprete, Cristiana; Carabelli, Stefano

    1994-05-01

    A mathematical model of an active electromagnetic bearing which includes the actuator, the sensor and the control system is developed and implemented in a specialized finite element code for rotordynamic analysis. The element formulation and its incorporation in the model of the machine are described in detail. A solution procedure, based on a modal approach in which the number of retained modes is controlled by the user, is then shown together with other procedures for computing the steady-state response to both static and unbalance forces. An example of application shows the numerical results obtained on a model of an electric motor suspended on a five active-axis magnetic suspension. The comparison of some of these results with the experimental characteristics of the actual system shows the ability of the present model to predict its performance.

  11. Parameter estimation and actuator characteristics of hybrid magnetic bearings for axial flow blood pump applications.

    Science.gov (United States)

    Lim, Tau Meng; Cheng, Shanbao; Chua, Leok Poh

    2009-07-01

    Axial flow blood pumps are generally smaller as compared to centrifugal pumps. This is very beneficial because they can provide better anatomical fit in the chest cavity, as well as lower the risk of infection. This article discusses the design, levitated responses, and parameter estimation of the dynamic characteristics of a compact hybrid magnetic bearing (HMB) system for axial flow blood pump applications. The rotor/impeller of the pump is driven by a three-phase permanent magnet brushless and sensorless motor. It is levitated by two HMBs at both ends in five degree of freedom with proportional-integral-derivative controllers, among which four radial directions are actively controlled and one axial direction is passively controlled. The frequency domain parameter estimation technique with statistical analysis is adopted to validate the stiffness and damping coefficients of the HMB system. A specially designed test rig facilitated the estimation of the bearing's coefficients in air-in both the radial and axial directions. Experimental estimation showed that the dynamic characteristics of the HMB system are dominated by the frequency-dependent stiffness coefficients. By injecting a multifrequency excitation force signal onto the rotor through the HMBs, it is noticed in the experimental results the maximum displacement linear operating range is 20% of the static eccentricity with respect to the rotor and stator gap clearance. The actuator gain was also successfully calibrated and may potentially extend the parameter estimation technique developed in the study of identification and monitoring of the pump's dynamic properties under normal operating conditions with fluid.

  12. Low eddy loss axial hybrid magnetic bearing with gimballing control ability for momentum flywheel

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jiqiang, E-mail: tjq_72@163.com [School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191 (China); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Sun, Jinji; Fang, Jiancheng [School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191 (China); Shuzhi Sam, Ge [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2013-03-15

    For a magnetically suspended momentum flywheel (MSMF), the spinning rotor can be tilted by a pair of the presented axial hybrid magnetic bearing (AHMB) with eight poles and rotates around the radial axes to generate a large torque to maneuver the spacecraft. To improve the control performance and gimballing control ability of the AHMB, characteristics such as magnetic suspension force, angular stiffness and tilting momentum are researched. These segmented stator poles cause the magnetic density in the thrust rotor plate to be uneven unavoidably and the rotational loss is large at high speed, but we optimized the stator poles configuration and caused the thrust rotor plate formed by bulk DT4C and laminated material to make the magnetic density in the thrust rotor plate change less and be smoother. Laminated material such as 1J50 film with a thickness of 0.1 mm can make the variation of the magnetic density in DT4C become very small and the eddy loss of it be negligible, but the stress produced in the 'O' shape stacks by reeling has a bad effect on its power loss. Nanocrystalline can reduce eddy losses and is not affected by the reeling process. Based on the AHBM consisting of the stator with eight improved poles and the presented thrust rotor plate with DT4 and nanocrystalline, the rotational loss of 5-DOF magnetically suspended momentum flywheel with angular momentum of 15 N m s at 5000 rpm has reduced from 23.4 W to 3.2 W, which proved that this AHMB has low eddy loss for the gimballing control ability. - Highlights: Black-Right-Pointing-Pointer Control methods of rotor driven by AHMBs and their characteristics are researched. Black-Right-Pointing-Pointer Optimized stator and rotor of AHMB reduce its eddy losses greatly. Black-Right-Pointing-Pointer Presented the factors affecting the eddy losses of AHMBs. Black-Right-Pointing-Pointer The good performances of AHMB with low eddy loss are proved by experiments.

  13. Test equipment for a flywheel energy storage system using a magnetic bearing composed of superconducting coils and superconducting bulks

    Science.gov (United States)

    Ogata, M.; Matsue, H.; Yamashita, T.; Hasegawa, H.; Nagashima, K.; Maeda, T.; Matsuoka, T.; Mukoyama, S.; Shimizu, H.; Horiuchi, S.

    2016-05-01

    Energy storage systems are necessary for renewable energy sources such as solar power in order to stabilize their output power, which fluctuates widely depending on the weather. Since ‘flywheel energy storage systems’ (FWSSs) do not use chemical reactions, they do not deteriorate due to charge or discharge. This is an advantage of FWSSs in applications for renewable energy plants. A conventional FWSS has capacity limitation because of the mechanical bearings used to support the flywheel. Therefore, we have designed a superconducting magnetic bearing composed of a superconducting coil stator and a superconducting bulk rotor in order to solve this problem, and have experimentally manufactured a large scale FWSS with a capacity of 100 kWh and an output power of 300 kW. The superconducting magnetic bearing can levitate 4 tons and enables the flywheel to rotate smoothly. A performance confirmation test will be started soon. An overview of the superconducting FWSS is presented in this paper.

  14. Variable Parameters PD Control and Stability of a High Rate Rigid Rotor-Journal Active Magnetic Bearing System

    Institute of Scientific and Technical Information of China (English)

    LUO Kai

    2005-01-01

    Stability is a key problem that means whether a high rate rotor-active magnetic bearings system works reliably or not. Aiming at a bearings system described with nonlinear equations, this paper built a linear model according to the system behavior. Considering realization of the control system and behavior of a high rate rotor system (magnetic force is far smaller than input force produced by mass eccentricity) this paper proposes a design method of variable parameters PD control algorithm that can be used universally. The control system was simplified and a mass of adjusting work of control parameters was reduced. Analysis and simulation indicated that the bearings system could get a wider stable region of harmonic motion, and proved that the algorithm is robust and advanced. The control system can be realized because the winding electric currents are positive. The method is convenient for operation and can easily be used for engineering practice.

  15. Magnetic polarity ages of the fossil-bearing strata at the Si hetun section, West Liaoning:A preliminary result

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Rock-magnetic and palaeomagnetic studies have been carried out on the interval of famous fossil-bearing sedimentary rocks and its overlying basalts and underlying basalts at the Sihetun section, West Liaoning Province. Normal polarity was obtained for the sedimentary interval and the underlying basalts, while reversed polarity was found in the overlying basalts. Taking account of the new 40Ar/39Ar ages (Swisher et al., 1999), we classified the fossil-bearing sedimentary interval into the Barremian M3n zone (Early Cretaceous age). Several abnormal horizons on magnetic properties, probably corresponding to the tuffs,were observed in the fossil-bearing sedimentary interval.This implies that the massive bio-extinction may link to dramatic environmental changes that were caused by voleanic eruptions.``

  16. Magnetostatic analysis of a rotor system supported by radial active magnetic bearings

    Directory of Open Access Journals (Sweden)

    Ferfecki P.

    2009-06-01

    Full Text Available The development and the design of a radial active magnetic bearing (AMB reflects a complex process of the multidisciplinary rotor dynamics, electromagnetism and automatic control analysis. Modelling is performed by application of the physical laws from different areas, e.g. Newton's laws of motion and Maxwell's equations. The new approach in the numerical modelling of radial AMB and design methodology allowing automatic generation of primary dimensions of the radial AMB is proposed. Instead of the common way of computation of electromagnetic forces by linearizing at the centre position of the rotor with respect to rotor displacement and coil current, the finite element computation of electromagnetic forces is used. The heteropolar radial AMB consisting of eight pole shoes was designed by means of the built up algorithms for rotor system with two discs fixed on the cantilever shaft. A study of the influence of the nonlinear magnetization characteristics of a rotor and stator material on the equilibrium position of a rotor system is carried out. The performed numerical study shows that results obtained from the analytical nonlinear relation for electromagnetic forces can be considerably different from forces computed with magnetostatic finite element analysis.

  17. Accumulation of nanocarriers in the ovary

    DEFF Research Database (Denmark)

    Schädlich, Andreas; Hoffmann, Stefan; Mueller, Thomas;

    2012-01-01

    Several nanocarrier systems are frequently used in modern pharmaceutical therapies. Within this study a potential toxicity risk of all nanoscaled drug delivery systems was found. An accumulation of several structurally different nanocarriers but not of soluble polymers was detected in rodent...... vivo multispectral fluorescence imaging and confocal laser scanning microscopy. The findings of this study emphasise the role of early and comprehensive in vivo studies in pharmaceutical research. Nanocarrier accumulation in the ovaries may also comprise an important toxicity issue in humans...... but the results might as well open a new field of targeted ovarian therapies....

  18. Magnetic nanocarriers of doxorubicin coated with poly(ethylene glycol) and folic acid: relation between coating structure, surface properties, colloidal stability, and cancer cell targeting.

    Science.gov (United States)

    Kaaki, Karine; Hervé-Aubert, Katel; Chiper, Manuela; Shkilnyy, Andriy; Soucé, Martin; Benoit, Roland; Paillard, Archibald; Dubois, Pierre; Saboungi, Marie-Louise; Chourpa, Igor

    2012-01-17

    We report the efficient one-step synthesis and detailed physicochemical evaluation of novel biocompatible nanosystems useful for cancer therapeutics and diagnostics (theranostics). These systems are the superparamagnetic iron oxide nanoparticles (SPIONs) carrying the anticancer drug doxorubicin and coated with the covalently bonded biocompatible polymer poly(ethylene glycol) (PEG), native and modified with the biological cancer targeting ligand folic acid (PEG-FA). These multifunctional nanoparticles (SPION-DOX-PEG-FA) are designed to rationally combine multilevel mechanisms of cancer cell targeting (magnetic and biological), bimodal cancer cell imaging (by means of MRI and fluorescence), and bimodal cancer treatment (by targeted drug delivery and by hyperthermia effect). Nevertheless, for these concepts to work together, the choice of ingredients and particle structure are critically important. Therefore, in the present work, a detailed physicochemical characterization of the organic coating of the hybrid nanoparticles is performed by several surface-specific instrumental methods, including surface-enhanced Raman scattering (SERS) spectroscopy, X-ray photoelectron spectrometry (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS). We demonstrate that the anticancer drug doxorubicin is attached to the iron oxide surface and buried under the polymer layers, while folic acid is located on the extreme surface of the organic coating. Interestingly, the moderate presence of folic acid on the particle surface does not increase the particle surface potential, while it is sufficient to increase the particle uptake by MCF-7 cancer cells. All of these original results contribute to the better understanding of the structure-activity relationship for hybrid biocompatible nanosystems and are encouraging for the applications in cancer theranostics.

  19. Dynamic Spin Rig Upgraded With a Five- Axis-Controlled Three-Magnetic-Bearing Support System With Forward Excitation

    Science.gov (United States)

    Morrison, Carlos R.; Mehmed, Oral

    2003-01-01

    The NASA Glenn Research Center Dynamic Spin Rig is used for experimental evaluation of vibration analysis methods and dynamic characteristics for rotating systems. Measurements are made while rotors are spun and vibrated in a vacuum chamber. The rig has been upgraded with a new active magnetic bearing rotor support and excitation system. This design is expected to provide operational improvements over the existing rig. The rig will be able to be operated in either the old or new configuration. In the old configuration, two ball bearings support the vertical shaft of the rig, with the test article located between the bearings. Because the bearings operate in a vacuum, lubrication is limited to grease. This limits bearing life and speed. In addition, the old configuration employs two voice-coil electromagnetic shakers to apply oscillatory axial forces or transverse moments to the rotor shaft through a thrust bearing. The excitation amplitudes that can be imparted to the test article with this system are not adequate for components that are highly damped. It is expected that the new design will overcome these limitations.

  20. Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic therapy.

    Science.gov (United States)

    Unterweger, Harald; Subatzus, Daniel; Tietze, Rainer; Janko, Christina; Poettler, Marina; Stiegelschmitt, Alfons; Schuster, Matthias; Maake, Caroline; Boccaccini, Aldo R; Alexiou, Christoph

    2015-01-01

    Combining the concept of magnetic drug targeting and photodynamic therapy is a promising approach for the treatment of cancer. A high selectivity as well as significant fewer side effects can be achieved by this method, since the therapeutic treatment only takes place in the area where accumulation of the particles by an external electromagnet and radiation by a laser system overlap. In this article, a novel hypericin-bearing drug delivery system has been developed by synthesis of superparamagnetic iron oxide nanoparticles (SPIONs) with a hypericin-linked functionalized dextran coating. For that, sterically stabilized dextran-coated SPIONs were produced by coprecipitation and crosslinking with epichlorohydrin to enhance stability. Carboxymethylation of the dextran shell provided a functionalized platform for linking hypericin via glutaraldehyde. Particle sizes obtained by dynamic light scattering were in a range of 55-85 nm, whereas investigation of single magnetite or maghemite particle diameter was performed by transmission electron microscopy and X-ray diffraction and resulted in approximately 4.5-5.0 nm. Surface chemistry of those particles was evaluated by Fourier transform infrared spectroscopy and ζ potential measurements, indicating successful functionalization and dispersal stabilization due to a mixture of steric and electrostatic repulsion. Flow cytometry revealed no toxicity of pure nanoparticles as well as hypericin without exposure to light on Jurkat T-cells, whereas the combination of hypericin, alone or loaded on particles, with light-induced cell death in a concentration and exposure time-dependent manner due to the generation of reactive oxygen species. In conclusion, the combination of SPIONs' targeting abilities with hypericin's phototoxic properties represents a promising approach for merging magnetic drug targeting with photodynamic therapy for the treatment of cancer.

  1. Modeling and Development of a Magnetic Bearing Controller for a High Speed Flywheel System

    Science.gov (United States)

    Dever, Timothy P.; Brown, Gerald V.; Duffy, Kirsten P.; Jansen, Ralph H.

    2005-01-01

    This paper describes a modeling effort used to develop an improved type of magnetic bearing controller, called a modal controller, for use on high speed flywheel systems. The controller design is based on models of the flywheel system, is designed to directly control the natural dynamics of the spinning rotor, and is generic enough to be readily adapted to future flywheel systems. Modeling and development are described for two key controller subsystems: the modal controller subsystem, which allows direct control over the rotor rigid body modes, and the bending mode compensation subsystem, which tracks, and prevents interference from, the rotor bending modes during flywheel operation. Integration of modeling results into the final controller is described and data taken on the NASA Glenn D1 flywheel module during high speed operation are presented and discussed. The improved modal controller described in this paper has been successfully developed and implemented and has been used for regular hands-free operation of the D1 flywheel module up to its maximum operating speed of 60,000 RPM.

  2. Design of Robust Adaptive Unbalance Response Controllers for Rotors with Magnetic Bearings

    Science.gov (United States)

    Knospe, Carl R.; Tamer, Samir M.; Fedigan, Stephen J.

    1996-01-01

    Experimental results have recently demonstrated that an adaptive open loop control strategy can be highly effective in the suppression of unbalance induced vibration on rotors supported in active magnetic bearings. This algorithm, however, relies upon a predetermined gain matrix. Typically, this matrix is determined by an optimal control formulation resulting in the choice of the pseudo-inverse of the nominal influence coefficient matrix as the gain matrix. This solution may result in problems with stability and performance robustness since the estimated influence coefficient matrix is not equal to the actual influence coefficient matrix. Recently, analysis tools have been developed to examine the robustness of this control algorithm with respect to structured uncertainty. Herein, these tools are extended to produce a design procedure for determining the adaptive law's gain matrix. The resulting control algorithm has a guaranteed convergence rate and steady state performance in spite of the uncertainty in the rotor system. Several examples are presented which demonstrate the effectiveness of this approach and its advantages over the standard optimal control formulation.

  3. Tissue Changes During Operational Load Bearing in UH-60 Aircrew Using Magnetic Resonance Imaging.

    Science.gov (United States)

    Games, Kenneth E; Kollock, Roger O; Windham, Jerrod; Fischer, Gregory S; Sefton, JoEllen M

    2015-09-01

    Warfighters involved in mounted operations often experience prolonged periods of tissue loading, leading to injury. Determining how anatomical structures are affected during loading aids in the prevention and treatment of injury. The purpose of this study was to develop a magnetic resonance imaging (MRI) compatible seat system that simulates a UH-60 Blackhawk in-flight sitting posture. Eight men were scanned with a 3.0 Tesla MRI. Scans were collected with and without 6.38 psi of pressure applied to the buttocks via two air bladders and an MRI-compatible robot controller system. Scans revealed that 6.38 psi of pressure applied to the buttocks significantly decreases total soft-tissue thickness beneath the left and right ischial tuberosities by 3.6 and 3.8 mm, respectively. At operational load bearing pressures seen in the UH-60, the soft tissue structures of the buttocks are compressed. These findings aid in our understanding of the etiology of repetitive trauma disorders in aircrew due to prolonged sitting. This study serves as the foundation for future work examining the anatomical changes associated with prolonged restricted sitting and other operational activities. A better understanding of the anatomical characteristics associated with mounted operations is invaluable to the prevention and treatment of injuries reported by warfighters and civilian populations.

  4. Investigation of Combined Motor/Magnetic Bearings for Flywheel Energy Storage Systems

    Science.gov (United States)

    Hofmann, Heath

    2003-01-01

    Dr. Hofmann's work in the summer of 2003 consisted of two separate projects. In the first part of the summer, Dr. Hofmann prepared and collected information regarding rotor losses in synchronous machines; in particular, machines with low rotor losses operating in vacuum and supported by magnetic bearings, such as the motor/generator for flywheel energy storage systems. This work culminated in a presentation at NASA Glenn Research Center on this topic. In the second part, Dr. Hofmann investigated an approach to flywheel energy storage where the phases of the flywheel motor/generator are connected in parallel with the phases of an induction machine driving a mechanical actuator. With this approach, additional power electronics for driving the flywheel unit are not required. Simulations of the connection of a flywheel energy storage system to a model of an electromechanical actuator testbed at NASA Glenn were performed that validated the proposed approach. A proof-of-concept experiment using the D1 flywheel unit at NASA Glenn and a Sundstrand induction machine connected to a dynamometer was successfully conducted.

  5. Study of Design Knowledge Capture (DKC) schemes implemented in magnetic bearing applications

    Science.gov (United States)

    1990-01-01

    A design knowledge capture (DKC) scheme was implemented using frame-based techniques. The objective of such a system is to capture not only the knowledge which describes a design, but also that which explains how the design decisions were reached. These knowledge types were labelled definitive and explanatory, respectively. Examination of the design process helped determine what knowledge to retain and at what stage that knowledge is used. A discussion of frames resulted in the recognition of their value to knowledge representation and organization. The FORMS frame system was used as a basis for further development, and for examples using magnetic bearing design. The specific contributions made by this research include: determination that frame-based systems provide a useful methodology for management and application of design knowledge; definition of specific user interface requirements, (this consists of a window-based browser); specification of syntax for DKC commands; and demonstration of the feasibility of DKC by applications to existing designs. It was determined that design knowledge capture could become an extremely valuable engineering tool for complicated, long-life systems, but that further work was needed, particularly the development of a graphic, window-based interface.

  6. Pumps for cryogenic liquids with superconducting magnetic bearings. Final report; Pumpen fuer kryogene Fluessigkeiten mit supraleitenden Magnetlagern. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Gerlach, G.; Fuchs, G.; Sorber, J.; Brosche, H.; Richter, M.; Frenzel, C.

    2000-07-01

    A liquid nitrogen pump with contactless superconducting magnetic bearings was to be developed on the basis of an available motor with superconducting bearings. Contactless superconducting magnetic bearings require practically no servicing. A high demand for pumps for cryogenic liquids is expected with the impending use of hydrogen as an energy source. The pumping of liquid nitrogen was demonstrated successfully with the new test aggregate. The maximum pumped volume was 17 l/min at a lift of 0.5 m and 6 l/min at a lift of 1 m. In all, 15 hours of operation were registered in the superconducting state of the bearing, which included 2 hours of uninterrupted pump operation. The higher speed range for which magnetic bearings are optimally suited was not reached. Operation at higher frequencies was impossible either because of stronger resonance amplituees or because the power system was too weak. [German] Ziel des Vorhabens war die Entwicklung einer Pumpe fuer fluessigen Stickstoff mit beruehrungslosen supraleitenden Magnetlagern auf der Basis eines vorhandenen supraleitend gelagerten Motors. Die beruehrungslose supraleitende Magnetlager sind praktisch wartungsfrei. Ein Bedarf an Pumpen fuer kryogene Fluessigkeiten entsteht insbesondere durch den in naher Zukunft zu erwartenden Einsatz von Wasserstoff als Energietraeger. Mit dem entworfenen Aggregat wurde das Pumpen von Fluessigstickstoff erfolgreich demonstriert. Der Foerderstrom betrug bei 0,5m Foerderhoehe maximal 17 l/min; beim 1m Foerderhoehe wurden maximal 6 l/min gemessen. Es wurden insgesamt ca. 15 Betriebsstunden in supraleitenden Zustand des Lagers, darunter 2 Stunden ununterbrochener Pumpbetrieb registriert. Der hoehere Drehzahlbereich, fuer den das Magnetlager eigentlich paedestiniert ist, konnte nicht erreicht werden. Ein Betrieb bei hoeheren (Ist-)Frequenzen war nicht moeglich, entweder durch staerkere Resonanzausschlaege oder durch einen zu schwachen Antrieb. (orig.)

  7. Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic therapy

    Directory of Open Access Journals (Sweden)

    Unterweger H

    2015-11-01

    Full Text Available Harald Unterweger,1 Daniel Subatzus,1 Rainer Tietze,1 Christina Janko,1 Marina Poettler,1 Alfons Stiegelschmitt,2 Matthias Schuster,3 Caroline Maake,4 Aldo R Boccaccini,5 Christoph Alexiou11ENT Department, Section of Experimental Oncology and Nanomedicine (SEON, Else Kröner-Fresenius-Stiftung Professorship, University Hospital Erlangen; 2Institute of Glass and Ceramics, Department of Materials Science and Engineering, University Erlangen-Nuremberg, 3Materials for Electronics and Energy Technology, Department of Materials Science and Engineering, University Erlangen-Nürnberg, Erlangen, Germany; 4Institute of Anatomy, University of Zurich, Winterthurerstr, Zurich, Switzerland; 5Institute of Biomaterials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, Germany Abstract: Combining the concept of magnetic drug targeting and photodynamic therapy is a promising approach for the treatment of cancer. A high selectivity as well as significant fewer side effects can be achieved by this method, since the therapeutic treatment only takes place in the area where accumulation of the particles by an external electromagnet and radiation by a laser system overlap. In this article, a novel hypericin-bearing drug delivery system has been developed by synthesis of superparamagnetic iron oxide nanoparticles (SPIONs with a hypericin-linked functionalized dextran coating. For that, sterically stabilized dextran-coated SPIONs were produced by coprecipitation and crosslinking with epichlorohydrin to enhance stability. Carboxymethylation of the dextran shell provided a functionalized platform for linking hypericin via glutaraldehyde. Particle sizes obtained by dynamic light scattering were in a range of 55–85 nm, whereas investigation of single magnetite or maghemite particle diameter was performed by transmission electron microscopy and X-ray diffraction and resulted in approximately 4.5–5.0 nm. Surface chemistry of those

  8. 电磁轴承的原理与应用%Principle and Application of Active Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    严文彩; 李宏冰; 周殿莹

    2013-01-01

    The active magnetic bearing is a new supporting technology in the world,and it began to be study in the mid- 1960s.In the paper, the structure,principle,characteristics of active magetic bearings were introduced,and the developing level and tendency of the active magnetic bearing were analyzed. At last, taking methane expansion compressor in the ethylene plant as an example, matters needing attention during design,type selection and application of the active magetic bearing were discussed.%  电磁轴承技术是国际上20世纪60年代中期开始研究的一项新的支承技术。第一部分简要介绍电磁轴承的结构、原理、特点,并分析了国内外电磁轴承的发展现状及前景。第二部分,以乙烯装置的甲烷膨胀/压缩机为例,阐述了电磁轴承设计选型时的注意事项及其应用。

  9. 3Dwheel: 3-axis low-noise, high-bandwidth attitude actuation from a single momentum wheel using magnetic bearings.

    OpenAIRE

    Seddon, Jon; Pechev, Alexandre

    2009-01-01

    This paper proposes a new concept for attitude actuation for small satellites that uses active magnetic bearings to support and tilt a spinning rotor to provide 3-axis attitude control of the satellite using a single actuator. A controlled 3D motion in the spinning rotor provides a conventional torque output about the momentum axis and a gyroscopic torque output about any direction in the plane normal to the spinning axis. Therefore, a single tilting momentum-wheel can generate torque along t...

  10. Magnetic Properties of Oil-gas-bearing Rocks of The Central Part of Dniper-donetsk Trough

    Science.gov (United States)

    Kuderavets, R.; Maksymchuk, V.; Gorodisky, Y.

    Small amplitude positive local delta F anomalies were revealed by the results of high- accuracy magnetic prospecting in the Dniper-Donets trought over a series of oil-gas- bearing structures. Their nature can be explained by lithofacial and epigenetic rock magnetic variations in the oxidized-reduced zones of carbon deposits. Though, there is no trustable experimental data on magnetic properties of rocks in these zones. To study peculiarities of lateral and vertical magnetic perceptability, mineral rock com- position distribution within oil-gas-bearing areas in Dniper-Donetsk trough a series of investigations of these characteristics have been conducted for productive and un- productive holes. In general, the magnetic perceptability of core from 19 holes, near oil-gas deposits and far from theirs as well were determined. A statistic analysis of the obfained cappa values was done, rock mineral composition in some holes was de- termined. The results make it possible to conclude: 1. The cut is composed mainly of terrigenous rocks and is characterized by a slight differentiation by the magnetic perceptability (0-150x10E-5Si) 2. Small values of rock magnetic perceptability (1- 3x10E-5Si) and dispersion for low Visean substage of low carbon with which oil-gas- bearing of the region under study is closely connected were determined. 3. Statistic analysis proved the existence of some types of cappa distribution within the hole in particular it differs within productive and unproductive formations. 4. Larger values of cappa and their dispersion in comparison with analogical deposits in productive formations, were revealed. 5. A series of secondary epigenic minerals: quartz, kaoli- nite, aragonite, ankerite, dolomite, pirite, hematite, siderite was determined in the de- posit zone and out of it. The largest amount of ironminerals (ankerite, pirite, hematite, siderite) was found in terrigeneous rocks (argillite) located over and under carbon de- posits. The analysis of the

  11. Effect of interleukin-2 treatment combined with magnetic fluid hyperthermia on Lewis lung cancer-bearing mice.

    Science.gov (United States)

    Hu, Runlei; Ma, Shenglin; Ke, Xianfu; Jiang, Hong; Wei, Dongshan; Wang, Wei

    2016-01-01

    The present study aimed to investigate the therapeutic effect of interleukin-2 (IL-2) treatment combined with magnetic fluid hyperthermia (MFH) on Lewis lung cancer-bearing mice. Magnetic fluids were prepared in vitro and directly injected into the tumors in the mice, which were subjected to an alternating magnetic field. The temperature in the tumor reached 43°C and was maintained by controlling the strength of magnetic field for 30 min. Twenty-four hours later, IL-2 was injected directly into the tumors. Mice were divided into four groups: Group I (control), II (MFH), III (IL-2) and IV (IL-2+MFH). The tumor grew gradually in groups II and IV (both Pbearing mice.

  12. Combined magnetic resonance imaging approach for the assessment of in vivo knee joint kinematics under full weight-bearing conditions.

    Science.gov (United States)

    Al Hares, Ghaith; Eschweiler, Jörg; Radermacher, Klaus

    2015-06-01

    The development of detailed and specific knowledge on the biomechanical behavior of loaded knee structures has received increased attention in recent years. Stress magnetic resonance imaging techniques have been introduced in previous work to study knee kinematics under load conditions. Previous studies captured the knee movement either in atypical loading supine positions, or in upright positions with help of inclined supporting backrests being insufficient for movement capture under full-body weight-bearing conditions. In this work, we used a combined magnetic resonance imaging approach for measurement and assessment in knee kinematics under full-body weight-bearing in single legged stance. The proposed method is based on registration of high-resolution static magnetic resonance imaging data acquired in supine position with low-resolution data, quasi-static upright-magnetic resonance imaging data acquired in loaded positions for different degrees of knee flexion. The proposed method was applied for the measurement of tibiofemoral kinematics in 10 healthy volunteers. The combined magnetic resonance imaging approach allows the non-invasive measurement of knee kinematics in single legged stance and under physiological loading conditions. We believe that this method can provide enhanced understanding of the loaded knee kinematics. © IMechE 2015.

  13. Development of a novel shape memory alloy-actuated resettable locking device for magnetic bearing reaction wheel.

    Science.gov (United States)

    Zhang, Xiaoyong; Yan, Xiaojun; Zhang, Shaowei; Nie, Jingxu

    2014-01-01

    The current investigation proposes a shape memory alloy (SMA)-actuated resettable locking device for magnetic bearing reaction wheel. The device employed two SMA wire-based actuators to realize locking and unlocking. Dual-slope mating surfaces were used on one hand to transmit the motion between a moving part and a clamp, and on the other hand to achieve a self-locking linkage in the locking state. Moreover, geometric parameters of the two SMA wires and corresponding bias springs were also designed. Based on the proposed design scheme, four locking devices were manufactured and assembled. Performance and environmental tests were performed to verify the proposed locking device. Test results show that the locking device can protect the magnetic bearing reaction wheel from launch vibration damage, and can withstand the thermal environment in the launch and on-orbit stage. Moreover, the device can be successfully operated for 76 times, and the response time for the locking and unlocking processes under 7 V power supply is 0.9 s and 5.6 s, respectively. Considering the results obtained from these tests, we conclude that the proposed resettable locking device is an attractive alternative technology to conventional motor-driven or pyrotechnics-based technologies, and can be applied reliably in the magnetic bearing reaction wheel.

  14. Unbalanced Magnetic Pull Effect on Stiffness Models of Active Magnetic Bearing due to Rotor Eccentricity in Brushless DC Motor Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Bangcheng Han

    2013-01-01

    Full Text Available We firstly report on an investigation into the unbalanced magnetic pull (UMP effect on the static stiffness models of radial active magnetic bearing (RAMB in brushless DC motor (BDCM in no-loaded and loaded conditions using the finite element method (FEM. The influences of the UMP on the force-control current, force-position, current stiffness, and position stiffness of RAMB are clarified in BDCM with 100 kW rated power. We found the position stiffness to be more susceptible to UMP. The primary source of UMP is the permanent magnets of BDCM. In addition, the performance of RAMB is affected by the UMP ripples during motor commutation and also periodically affected by the angular position of rotor. The characteristic curves of RAMB force versus control current (or rotor position and angular position of rotor affected by the UMP are given. The method is useful in design and optimization of RAMB in magnetically suspended BDCMs.

  15. Preparation of high-quality HTS rings for application in the magnetic bearing of cryotanks and pinning in grain boundaries

    Science.gov (United States)

    Bringmann, B.; Walter, H.; Jooss, Ch.; Leenders, A.; Freyhardt, H. C.

    2002-08-01

    Seeded melt growth of YBCO high-temperature superconductors is one of the most promising preparation techniques to obtain high-quality HTS tiles for application, e.g. in magnetic bearings. Semi-finished HTSL products of complex shapes have to be developed by different seeding and multi-seeding techniques. To obtain large hollow cylinders designed for application in the magnetic bearing of a cryotank a modified multi-seeded melt growth (MSMG) process was employed. This cryotank will be mounted for testing in a vehicle of a major German car manufacturer. The MSMG process introduces grain boundaries into the HTS tiles. For transport current investigations of [0 0 1]-tilt grain boundaries in melt textured YBCO a series of MSMG bicrystals have been prepared. They exhibit a dependence of the critical current density on misorientation angle which is much weaker than the one observed in thin-film bicrystals. The bulk samples have dimensions larger than the magnetic penetration depth along the grain boundary. Thus, flux pinning has to be taken into account. Different contributions to the longitudinal pinning force have to be considered: vortices at grain boundaries can be pinned by magnetic interaction with Abrikosov vortices in the banks, by defects in the grain boundary itself or by defects which are located next to the grain boundary.

  16. Metal–organic coordination architectures of tetrazole heterocycle ligands bearing acetate groups: Synthesis, characterization and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Bo-Wen, E-mail: bowenhu@hit.edu.cn; Zheng, Xiang-Yu; Ding, Cheng

    2015-12-15

    Two new coordination complexes with tetrazole heterocycle ligands bearing acetate groups, [Co(L){sub 2}]{sub n} (1) and [Co{sub 3}(L){sub 4}(N{sub 3}){sub 2}·2MeOH]{sub n} (2) (L=tetrazole-1-acetate) have been synthesized and structurally characterized. Single crystal structure analysis shows that the cobalt-complex 1 has the 3D 3,6-connected (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 8}.10)-ant topology. By introducing azide in this system, complex 2 forms the 2D network containing the [Co{sub 3}] units. And the magnetic properties of 1 and 2 have been studied. - Graphical abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with tetrazole heterocycle ligands bearing acetate groups are reported. - Highlights: • Two novel Cobalt(II) complexes with tetrazole acetate ligands were synthesized. • The magnetic properties of two complexes were studied. • Azide as co-ligand resulted in different structures and magnetic properties. • The new coordination mode of tetrazole acetate ligand was obtained.

  17. Sustained-release from nanocarriers: a review.

    Science.gov (United States)

    Natarajan, Jayaganesh V; Nugraha, Chandra; Ng, Xu Wen; Venkatraman, Subbu

    2014-11-10

    Nanocarriers have been explored for delivering drugs and other bioactive molecules for well over 35years. Since the introduction of Doxil®, a nanoliposomal delivery system for the cancer drug doxorubicin, several products have been approved worldwide. The majority of these products focus on cancer chemotherapy, and utilize the size advantage of nanocarriers to obtain a favourable distribution of the drug carrier in the human body. In general, such carriers do not sustain drug release over more than a few days at best. In this review, we explore the reasons for this, and present an overview of successful research that is capable of generating sustained-release products in non-cancer applications. A variety of nanocarriers have been studied, and their advantages and shortcomings are highlighted in this review. The achievement of sustained release of bioactive molecules opens new doors in nanotherapeutics.

  18. 新型混合径向磁轴承结构及其磁力特性%Structure and magnetic characteristics of novel hybrid radial magnetic bearing

    Institute of Scientific and Technical Information of China (English)

    陈君辉; 杨逢瑜; 聂朝瑞; 李正贵; 杨军; 王鹏雁

    2012-01-01

    Aimed at some problems in the permanent magnetic circuit of available magnetic radial bearings with permanent magnet bias such as small magnetic force, low magnetic flux density, and lack of self-stabilization. A new hybrid radial magnetic bearing structure for vertical axial flow pump was proposed. The nonlinear model and linearization equation of the bearing capacity of the new hybrid radial magnetic bearing were established by using current molecular method and virtual displacement theorem. It was found by a-nalysis that with this permanent magnetic suspension bearing, its self-stabilization would exhibit in some radial degrees of freedom and the total displacement negative stiffness of the system could be reduced. The investigation result showed that the air gap flux density was greatly improved with the new hybrid magnetic bearing when Halbach array structure was used. Current stiffness and displacement rigidity were closely related to initial current and initial gap at the equilibrium position. Around the equilibrium position, the variation of current stiffness and displacement rigidity was linear. With the increase of air gap, its linearity was well kept. With the decrease of air gap, however, a certain nonlinear characteristics exhibited.%针对当前永磁偏置径向磁轴承的永磁磁路的磁通密度低,磁力小,缺乏自稳定的问题,提出一种应用于立式轴流泵的新型混合径向磁轴承结构.应用分子电流法及虚位移定理建立新型混合径向磁轴承承载力的非线性模型及其线性化方程,分析得出新型径向混合磁悬浮轴承在径向某个自由度上具有自稳定的特点,且水磁轴承可以减小系统总的位移负刚度.研究结果表明,采用Halbach阵列结构后,混合磁轴承气隙的磁通密得到很大提高.电流刚度和位移刚度与平衡点的初始电流及初始间隙密切相关,在平衡位置附近电流刚度和位移刚度呈线性变化,当气隙增大时仍保

  19. The Research of Influence of Blood upon the Dynamics of Artificial Ventricle Rotor on Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    E. E. Ovsiannikova

    2015-01-01

    Full Text Available The article studies dynamics of rotor on active magnetic bearings within the mathematical model development of rotor in artificial ventricle. The problem of stabilization of rigid titanium rotor with magnetic inserts on active magnetic bearings is analyzed.The relevance of the research field is caused by high percent of people who are suffering from heart disease. The purposes of work are to create a mathematical model of the rigid rotor and position its center to meet specified requirements for displacement of no more than 0.2 millimeter while rotating with the speed from 5 000 rpm to 10 000 rpm in constant blood flow. The work of AMBs is based on the principle of active magnetic pendant of ferromagnetic solid. The stabilization in adjusted position is accomplished by magnetic forces, which affect the solid from the control electromagnets.The article presents initial data, design scheme, assumptions accepted to solve the problem and derivation of dynamic equation of rotating rigid rotor on AMBs. The decentralized control of magnetic pendant was implemented. The PD control – proportional differential control - was chosen as the base of control system. Its application is widespread due to the simplicity, industrial use and operation stability. The use of decentralized control in dynamics modeling of a rigid rotor in AMBs is physically occurred and has some advantages. One of the most important advantages is the calculation of control parameters by selection of appropriate values of rigidity and damping parameters.The analysis of rotor dynamics was conducted in MATLAB© software package.The modeling was performed to allow observing the system action while the parameters were varied.The conducted research showed that to meet the specified requirements of maximal rotor displacement no more than 0.2 mm the following values of coefficients were required:                                       and The stabilization of the rotor

  20. Experimental treatment of breast cancer-bearing BALB/c mice by artemisinin and transferrin-loaded magnetic nanoliposomes.

    Science.gov (United States)

    Gharib, Amir; Faezizadeh, Zohreh; Mesbah-Namin, Seyed Ali Reza; Saravani, Ramin

    2015-05-01

    The combination of artemisinin and transferrin exhibits versatile anticancer activities. In previous, we successfully prepared artemisinin and transferrin-loaded magnetic nanoliposomes and evaluated their anti-proliferative activity against MCF-7 and MDA-MB-231 cell lines in vitro. In this study, we investigate the in vivo anti-breast cancer activity of artemisinin and transferrin-loaded magnetic nanoliposome against breast transplanted tumors in BALB/c mice model. Artemisinin and transferrin-loaded magnetic nanoliposomes were prepared and characterized for some physiochemical properties. Pieces of tumor tissue from the breast cancer-bearing BALB/c mice were transplanted subcutaneously to the syngeneic female BALB/c mice. In the presence of the external magnet that placed at the breast tumor site, the tissue distribution and tumor-suppressing effects of prepared nanoliposomes on tumor growth was evaluated. The prepared nanoliposomes have fine spherical shape, rough surface, nano-sized diameter and magnetic properties. At 2 h after treatment, the intravenous administration of artemisinin and transferrin-loaded magnetic nanoliposomes followed using the magnetic field approximately produced 10- and 5.5-fold higher levels of artemisinin and transferrin in the tumors, respectively, compared with free artemisinin and transferrin. Moreover, in the presence of an external magnetic field, the prepared nanoliposomes could significantly induce apoptosis in the mice breast cancer cells as well as could reduce tumor volume in tumorized mice at 15 days after treatment. The data suggested that the artemisinin and transferrin-loaded magnetic nanoliposomes would be a good choice for the breast tumor-targeted therapy, due to its high targeting efficiency.

  1. 主动电磁轴承系统的动力学性能分析%Analysis on Dynamic Performance for Active Magnetic Bearing-Rotor System

    Institute of Scientific and Technical Information of China (English)

    严慧燕; 汪希平; 朱礼进; 张直明; 万金贵

    2001-01-01

    In the application of active magnetic bearings (AMB), one of the key problems to be solved is the safety and stability in the sense of rotor dynamics. The project related to the present paper deals with the method for analyzing bearing rotor systems with high rotation speed and specially supported by active magnetic bearings, and studies its rotor dynamics performance, including calculation of the natural frequencies with their distribution characteristics, and the critical speeds of the system. One of the targets of this project is to formulate a theory and method valid for the analysis of the dynamic performance of the active magnetic bearing-rotor system by combining the traditional theory and method of rotor dynamics with the analytical theory and design method based on modern control theory of the AMB system.

  2. Collection of Ni-bearing material from electroless plating waste by magnetic separation with HTS bulk magnet

    Energy Technology Data Exchange (ETDEWEB)

    Oka, T., E-mail: okat@eng.niigata-u.ac.jp [Niigata University, 8050 Ikarashi-Ninocho, Nishi-ku, Niigata 950-2181 (Japan); Fukazawa, H.; Fukui, S.; Ogawa, J.; Sato, T.; Ooizumi, M. [Niigata University, 8050 Ikarashi-Ninocho, Nishi-ku, Niigata 950-2181 (Japan); Tsujimura, M. [Aichi Giken Co., 50-1 Takeshita, Hitotugi-cho, Kariya, Aichi 448-0003 (Japan); Yokoyama, K. [Ashikaga Institute of Technology, 268-1 Ohmae-cho, Ashikaga, Tochigi 326-8558 (Japan)

    2014-01-15

    Highlights: ► The magnetic separation for Ni compounds was conducted by HTS bulk magnet. ► The coarse Ni-sulfate crystals were formed from the Ni-phosphite precipitates. ► Ni-sulfate crystals was separated from the mixture of Ni-sulfate and Ni-phosphite compounds. -- Abstract: The magnetic separation experiment to collect the Ni compounds from the waste liquid of electroless plating processes was conducted in the open-gradient magnetic separation process with the high temperature superconducting bulk magnet system. The magnetic pole containing Gd-based bulk superconductors was activated to 3.45 T at 35 K in the static magnetic field of 5 T with use of a superconducting solenoid magnet. The coarse Ni-sulfate crystals were formed by adding the concentrated sulfuric acid to the Ni-phosphite precipitates which yielded from the plating waste liquid by controlling the temperature and the pH value. The open-gradient magnetic separation technique was employed to separate the Ni-sulfate crystals from the mixture of the Ni-sulfate and Ni-phosphite compounds by the difference between their magnetic properties. And we succeeded in collecting Ni-sulfate crystals preferentially to the Ni-phosphite by attracting them to the magnetic pole soon after the Ni-sulfate crystals began to grow.

  3. Dynamics and stability of rigid rotors levitated by passive cylinder-magnet bearings and driven/supported axially by pointwise contact clutch

    DEFF Research Database (Denmark)

    Andersen, Søren Bøgh; Enemark, Søren; Santos, Ilmar

    2013-01-01

    A stable rotor—supported laterally by passive magnetic bearings and longitudinally by magnetic forces and a clutch—loses suddenly its contact to the clutch and executes abruptly longitudinal movements away from its original equilibrium position as a result of small increases in angular velocity. ...

  4. Advanced nanocarriers for an antitumor peptide

    Energy Technology Data Exchange (ETDEWEB)

    Pippa, Natassa [National and Kapodistrian University of Athens, Department of Pharmaceutical Technology, Faculty of Pharmacy (Greece); Pispas, Stergios [National Hellenic Research Foundation, Theoretical and Physical Chemistry Institute (Greece); Demetzos, Costas, E-mail: demetzos@pharm.uoa.gr [National and Kapodistrian University of Athens, Department of Pharmaceutical Technology, Faculty of Pharmacy (Greece); Sivolapenko, Gregory [University of Patras, Laboratory of Pharmacokinetics, Department of Pharmacy (Greece)

    2013-11-15

    In this work, tigapotide (PCK3145) was incorporated into novel nanocarriers based on polymeric, lipidic, and dendrimeric components, in order to maximize the advantages of the drug delivery process and possibly its biological properties. PCK3145 was incorporated into lipidic nanocarriers composed of Egg phosphatidylcholine (EggPC) and dipalmytoylphosphatidylcholine (DPPC) (EggPC:PCK3145 and DPPC:PCK3145, 9:0.2 molar ratio), into cationic liposomes composed of EggPC:SA:PCK3145 and DPPC:SA:PCK3145 (9:1:0.2 molar ratio) into complexes with the block polyelectrolyte (quaternized poly[3,5-bis(dimethylaminomethylene)hydroxystyrene]-b-poly(ethylene oxide) (QNPHOSEO) and finally into dendrimeric structures (i.e., PAMAM G4). Light scattering techniques are used in order to examine the size, the size distribution and the Z-potential of the nanocarriers in aqueous and biological media. Fluorescence spectroscopy was utilized in an attempt to extract information on the internal nanostructure and microenvironment of polyelectrolyte/PCK3145 aggregates. Therefore, these studies could be a rational roadmap for producing various effective nanocarriers in order to ameliorate the pharmacokinetic behavior and safety issues of antitumor and anticancer biomolecules.

  5. Capacity-controllable nanocarriers for metal ions

    NARCIS (Netherlands)

    Yan, Y.; Keizer, de A.; Cohen Stuart, M.A.; Besseling, N.A.M.

    2009-01-01

    We report on capacity-controllable nanocarrier system for metal ions based on a novel kind of polymeric microemulsion. These microemulsions are formed in mixed systems of negatively charged metal-bisligand coordination polymers (cp), positively charged homopolyelectrolyte (hp), and positive-neutral

  6. Nanocarriers in gene therapy: a review.

    Science.gov (United States)

    Xu, Hongpan; Li, Zhiyang; Si, Jin

    2014-12-01

    With its rapid development in the past few decades, gene therapy has shown potential for use as a standard clinical intervention for the treatment of several conditions, including cancers, infectious diseases, cardiovascular disorders, inner ear disorders, dermatological, ophthalmologic, and neurological pathologies. Current gene therapy is not limited to the delivery of DNA only. Other therapeutic nucleic acid materials such as small interfering RNA, antisense oligonucleotides, or microRNA have also been included into the protocols of gene therapy. The correct choice of vector is a key factor in the success of gene therapy, where both viral and non-viral vectors are commonly used. Viral vectors are associated with some severe side effects (e.g., immunologenicity and carcinogenicity). They show poor target cell specificity, are unable to transfer large-sized genes, and are costly. Therefore, non-viral vectors, especially nanocarriers, have become a realistic alternative to viral vectors for achieving better efficacy in gene therapy. Different types of nanocarriers such as liposomes, metallic and polymeric nanoparticles, dendrimers, gelatins, and quantum dots/rods have been developed, and each shows distinct characteristics. Nevertheless, a variety of new challenges should be properly addressed for ensuring the success of nanocarriers in clinical applications. In this review article, we first discuss the advances and applications of nanocarriers in gene therapy, and then describe the drawbacks and existing challenges of the emerging gene delivery methods based on the use of nanomaterials.

  7. Design and surface modification of potential luminomagnetic nanocarriers for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Ranu K., E-mail: ranu.dutta16@gmail.com; Sharma, Prashant K.; Pandey, Avinash C. [University of Allahabad, Nanophosphor Application Centre (India)

    2010-05-15

    Targeted delivery of therapeutics possesses the potential to localize therapeutic agents to a specific tissue as a mechanism to enhance treatment efficacy and mitigate side effects. Moeities that combine imaging and therapeutic modalities in a single macromolecular construct may confer advantages in the development and applications of nanomedicine. Here is an insight into the synthesis of luminomagnetic (luminescent and magnetic, simultaneously) nanocarriers of ZnO:Fe, synthesized by a simple co-precipitation method and surface modified by the ligand folate. This functionalized luminomagnetic nanocarrier system is a bioconjugation approach which combines the specificity of folate receptors on cancer cells with the excellent optical and magnetic properties of the nanoparticles so as to develop biocompatible molecular imaging agents, drug delivery systems, and hyperthermia agents. The vibrating sample magnetometer (VSM) studies showed clear hysteresis loops having coercivity 5.1 mT with corresponding magnetization of remanence 7.6 x 10{sup -3} emu/g, indicating strong magnetic character of the samples. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements show that these nanoparticles are spherical with 6-9 nm size and hence are quite appropriate for in vivo applications as well. The immobilization of folic acid was confirmed by fourier transform infrared (FTIR) analysis. All these properties make these luminomagnetic nanocarriers one of the most feasible candidates for folate receptor-mediated biomedical applications.

  8. Performance of a Ferrofluid Based Rough Parallel Plate Slider Bearing: A Comparison of Three Magnetic Fluid Flow Models

    Directory of Open Access Journals (Sweden)

    Jimit R. Patel

    2016-01-01

    Full Text Available Efforts have been made to present a comparison of all the three magnetic fluid flow models (Neuringer-Rosensweig model, Shliomis model, and Jenkins model so far as the performance of a magnetic fluid based parallel plate rough slider bearing is concerned. The stochastic model of Christensen and Tonder is adopted for the evaluation of effect of transverse surface roughness. The stochastically averaged Reynolds-type equation is solved with suitable boundary conditions to obtain the pressure distribution resulting in the calculation of load carrying capacity. The graphical results establish that for a bearing’s long life period the Shliomis model may be employed for higher loads. However, for lower to moderate loads, the Neuringer-Rosensweig model may be deployed.

  9. Development of a differentially balanced magnetic bearing and control system for use with a flywheel energy storage system

    Science.gov (United States)

    Higgins, Mark A.; Plant, David P.; Ries, Douglas M.; Kirk, James A.; Anand, Davinder K.

    1992-01-01

    The purpose of a magnetically suspended flywheel energy storage system for electric utility load leveling is to provide a means to store energy during times when energy is inexpensive to produce and then return it to the customer during times of peak power demand when generated energy is most expensive. The design of a 20 kWh flywheel energy storage system for electric utility load leveling applications involves the successful integration of a number of advanced technologies so as to minimize the size and cost of the system without affecting its efficiency and reliability. The flywheel energy storage system uses a carbon epoxy flywheel, two specially designed low loss magnetic bearings, a high efficiency motor generator, and a 60 cycle AC power converter all integrated through a microprocessor controller. The basic design is discussed of each of the components that is used in the energy storage design.

  10. Experimental modeling of the chemical remanent magnetization and Thellier procedure on titanomagnetite-bearing basalts

    Science.gov (United States)

    Gribov, S. K.; Dolotov, A. V.; Shcherbakov, V. P.

    2017-03-01

    The results of the experimental studies on creating chemical and partial thermal remanent magnetizations (or their combination), which are imparted at the initial stage of the laboratory process of the oxidation of primary magmatic titanomagnetites (Tmts) contained in the rock, are presented. For creating chemical remanent magnetization, the samples of recently erupted Kamchatka basalts were subjected to 200-h annealing in air in the temperature interval from 400 to 500°C under the action of the magnetic field on the order of the Earth's magnetic field. After creation of this magnetization, the laboratory modeling of the Thellier-Coe and Wilson-Burakov paleointensity determination procedures was conducted on these samples. It is shown that when the primary magnetization is chemical, created at the initial stage of oxidation, and the paleointensity determined by these techniques is underestimated by 15-20% relative to its true values.

  11. Performance Testing of a Magnetically Suspended Double Gimbal Control Moment Gyro Based on the Single Axis Air Bearing Table

    Directory of Open Access Journals (Sweden)

    Jiancheng Fang

    2012-07-01

    Full Text Available Integrating the advantage of magnetic bearings with a double gimble control moment gyroscope (DGCMG, a magnetically suspended DGCMG (MSDGCMG is an ideal actuator in high-precision, long life, and rapid maneuver attitude control systems. The work presented here mainly focuses on performance testing of a MSDGCMG independently developed by Beihang University, based on the single axis air bearing table. In this paper, taking into sufficient consideration to the moving-gimbal effects and the response bandwidth limit of the gimbal, a special MSDGCMG steering law is proposed subject to the limits of gimbal angle rate and angle acceleration. Finally, multiple experiments are carried out, with different MSDGCMG angular momenta as well as different desired attitude angles. The experimental results indicate that the MSDGCMG has a good gimbal angle rate and output torque tracking capabilities, and that the attitude stability with MSDGCMG as actuator is superior to 10−3°/s. The MSDGCMG performance testing in this paper, carried out under moving-base condition, will offer a technique base for the future research and application of MSDGCMGs.

  12. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  13. Efficient drug-delivery using magnetic nanoparticles--biodistribution and therapeutic effects in tumour bearing rabbits.

    Science.gov (United States)

    Tietze, Rainer; Lyer, Stefan; Dürr, Stephan; Struffert, Tobias; Engelhorn, Tobias; Schwarz, Marc; Eckert, Elisabeth; Göen, Thomas; Vasylyev, Serhiy; Peukert, Wolfgang; Wiekhorst, Frank; Trahms, Lutz; Dörfler, Arnd; Alexiou, Christoph

    2013-10-01

    To treat tumours efficiently and spare normal tissues, targeted drug delivery is a promising alternative to conventional, systemic administered chemotherapy. Drug-carrying magnetic nanoparticles can be concentrated in tumours by external magnetic fields, preventing the nanomaterial from being cleared by metabolic burden before reaching the tumour. Therefore in Magnetic Drug Targeting (MDT) the favoured mode of application is believed to be intra-arterial. Here, we show that a simple yet versatile magnetic carrier-system (hydrodynamic particles diameter magnetic drug targeting (MDT), demonstrating the importance of intra-arterial administration resulting in improved clinical outcomes in the studied animal model compared with intra-venous. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-01-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  15. Foil bearings

    Science.gov (United States)

    Elrod, David A.

    1993-11-01

    The rolling element bearings (REB's) which support many turbomachinery rotors offer high load capacity, low power requirements, and durability. Two disadvantages of REB's are: (1) rolling or sliding contact within the bearing has life-limiting consequences; and (2) REB's provide essentially no damping. The REB's in the Space Shuttle Main Engine (SSME) turbopumps must sustain high static and dynamic loads, at high speeds, with a cryogenic fluid as lubricant and coolant. The pump end ball bearings limit the life of the SSME high pressure oxygen turbopump (HPOTP). Compliant foil bearing (CFB) manufacturers have proposed replacing turbopump REB's with CFB's CFB's work well in aircraft air cycle machines, auxiliary power units, and refrigeration compressors. In a CFB, the rotor only contracts the foil support structure during start up and shut down. CFB damping is higher than REB damping. However, the load capacity of the CFB is low, compared to a REB. Furthermore, little stiffness and damping data exists for the CFB. A rotordynamic analysis for turbomachinery critical speeds and stability requires the input of bearing stiffness and damping coefficients. The two basic types of CFB are the tension-dominated bearing and the bending-dominated bearing. Many investigators have analyzed and measured characteristics of tension-dominated foil bearings, which are applied principally in magnetic tape recording. The bending-dominated CFB is used more in rotating machinery. This report describes the first phase of a structural analysis of a bending-dominated, multileaf CFB. A brief discussion of CFB literature is followed by a description and results of the present analysis.

  16. Nanocarriers for skin delivery of cosmetic antioxidants

    Directory of Open Access Journals (Sweden)

    Lucia Montenegro

    2014-08-01

    Full Text Available The demand of natural skin care products is steadily growing since consumers perceive them as safe. Currently, cosmetic manufacturers are focusing their efforts on developing innovative natural products to address skin-aging signs, thus meeting consumers’ needs of healthy appearance and well-being. To prevent or treat skin aging, topical supplementation with antioxidant is regarded as one of the most promising strategies. However, most antioxidants presently used in skin care formulations show unfavorable physicochemical properties such as excessive lipophilicity or hydrophilicity, chemical instability and poor skin penetration that actively limit their effectiveness after topical application. Therefore, nanocarriers such as liposomes, niosomes, microemulsions and nanoparticles have been widely investigated as delivery systems for antioxidants to improve their beneficial effects in the treatment of skin aging. In this article, the antioxidants most commonly used in anti-aging cosmetic products will be reviewed along with the nanocarriers designed to improve their safety and effectiveness.

  17. Finite element analysis on the electromagnetic fields of active magnetic bearing

    Energy Technology Data Exchange (ETDEWEB)

    Ren, S; Liu, J [School of Mechanical Engineering, Shenyang Ligong University, Shenyang, 110168 (China); Bian, C [Institute of Information Science and Engineering, Northeastern University, Shenyang, 110004 (China)], E-mail: renshy@sina.com

    2008-02-15

    To increase the carrying capacity and reduce the weight and size of AMBs, it is necessary to use a ferromagnetic material with high magnetic flux density, which can make AMBs run in the nonlinear region. The simple linear model before is not gratifying, so some more precise analysis methods are demanded, the finite element method(shorted as FEM) is one of such methods. In this paper, the mathematic model and the simplified calculation of AMB rotor are introduced, and the finite elemental model and its boundary condition are produced. Then, the coupling phenomena of the magnetic fields and the effects of different parameters on the magnetic fields of AMB with a non-homocentric rotor are simulated using the FEM analysis software of ANSYS. The distributions of 2D magnetic lines of force and the flux density in rotor and stator are given. The conclusions are of instructed meaning for the design of AMBs.

  18. Layered Double Hydroxide as Cordycepin Delivery Nanocarrier

    Institute of Scientific and Technical Information of China (English)

    Qin Zheng YANG; Jing YANG; Chang Kai ZHANG

    2006-01-01

    Layered double hydroxide was investigated as cordycepin delivery nanocarrier for the first time in this study. Negatively charged biomolecule-cordycepin was intercalated in the gallery spaces of [Mg-Al-NO3], which was confirmed by the results of X-ray diffraction and electrophoretic mobility. Cell experiment suggested that the new bio-LDH nanohybrid could prevent cordycepin decomposition by adenosine deaminase. This new formulation could possibly be used as a novel form cordycepin intravenous injection.

  19. Carbohydrate nanocarriers in biomedical applications: functionalization and construction.

    Science.gov (United States)

    Kang, Biao; Opatz, Till; Landfester, Katharina; Wurm, Frederik R

    2015-11-21

    The specific targeting of either tumor cells or immune cells in vivo by carefully designed and appropriately surface-functionalized nanocarriers may become an effective therapeutic treatment for a variety of diseases. Carbohydrates, which are prominent biomolecules, have shown their outstanding ability in balancing the biocompatibility, stability, biodegradability, and functionality of nanocarriers. The recent applications of sugar (mono/oligosaccharides and/or polysaccharides) for the development of nanomedicines are summarized in this review, including the application of carbohydrates for the surface-functionalization of various nanocarriers and for the construction of the nanocarrier itself. Current problems and challenges are also addressed.

  20. A contribution on the investigation of the dynamic behavior of rotating shafts with a Hybrid Magnetic Bearing Concept (HMBC) for blower application

    Energy Technology Data Exchange (ETDEWEB)

    Gronek, Martin, E-mail: MGronek@hs-zigr.d [HOCHSCHULE ZITTAU/GOERLITZ-University of Applied Sciences, Institute of Process Technology, Process Automation and Measuring Technology (IPM), Department Mechatronical Systems, Theodor-Koerner-Allee 16, 02763 Zittau (Germany); Rottenbach, Torsten; Worlitz, Frank [HOCHSCHULE ZITTAU/GOERLITZ-University of Applied Sciences, Institute of Process Technology, Process Automation and Measuring Technology (IPM), Department Mechatronical Systems, Theodor-Koerner-Allee 16, 02763 Zittau (Germany)

    2010-10-15

    Within a subproject of the RAPHAEL-Program, which was part of the 6th EURATOM Framework Program supervised by the European Commission, it was investigated whether the use of a Hybrid Magnetic Bearing Concept (HMBC) will be beneficial for a blower application. Within the RAPHAEL program, the subproject 'Component Development' is dealing with R and D of components of High Temperature Reactor Technology (HTR), where a major focus is on safety- and reliability-related issues. That implies special requirements for the support of high speed rotating shafts in HTR-Applications that only can be satisfied by using Active Magnetic Bearings (AMB). Regarding safety and competitiveness, AMBs are considered to be key components for the support of rotating HTR-components due to their technical features. AMBs are characterized by an electromagnetic actuator that is generating the bearing force depending on the clearance between stator and rotor, in which the rotor is levitated. Therefore an active control of the coil current is necessary. Furthermore, Touch Down Bearings (TDB) are needed to avoid damages in case of an emergency shut down or in case of energy supply losses. This contribution provides an internal insight on the advantages of a Hybrid Magnetic Bearing Concept that is characterized by a completely Active Magnetic Bearing-supported vertical arranged rotor and an additional permanent magnetic radial orientated bearing. One benefit of the HMBC is an additional radial guidance of the shaft that may reduce the loads while dropping into the Touch Down Bearings e.g. in case of energy supply losses of the AMBs. Reduced loads on the TDBs will increase their life cycle and the availability of the AMB supported component. The scope of this R and D-Project, which will be described more detailed in this contribution, includes: the analytical modeling and simulation of the dynamic behavior of the Hybrid Magnetic Bearing System; the modification of the completely AMB

  1. A knee brace alters patella position in patellofemoral osteoarthritis: a study using weight bearing magnetic resonance imaging.

    Science.gov (United States)

    Callaghan, M J; Guney, H; Reeves, N D; Bailey, D; Doslikova, K; Maganaris, C N; Hodgson, R; Felson, D T

    2016-12-01

    To assess using weight bearing magnetic resonance imaging (MRIs), whether a patellar brace altered patellar position and alignment in patellofemoral joint (PFJ) osteoarthritis (OA). Subjects age 40-70 years old with symptomatic and a radiographic Kellgren-Lawrence (K-L) evidence of PFJOA. Weight bearing knee MRIs with and without a patellar brace were obtained using an upright open 0.25 T scanner (G-Scan, Easote Biomedica, Italy). Five aspects of patellar position were measured: mediolateral alignment by the bisect offset index, angulation by patellar tilt, patellar height by patellar height ratio (patellar length/patellar tendon length), lateral patellofemoral (PF) contact area and finally a measurement of PF bony separation of the lateral patellar facet and the adjacent surface on the femoral trochlea (Fig. 1). Thirty participants were recruited (mean age 57 SD 27.8; body mass index (BMI) 27.8 SD 4.2); 17 were females. Four patients had non-usable data. Main analysis used paired t tests comparing within subject patellar position with and without brace. For bisect offset index, patellar tilt and patellar height ratio there were no significant differences between the brace and no brace conditions. However, the brace increased lateral facet contact area (P = .04) and decreased lateral PF separation (P = .03). A patellar brace alters patellar position and increases contact area between the patella and femoral trochlea. These changes would lower contact stress at the PFJ. Such changes in patella position in weight bearing provide a possible biomechanical explanation for the success of the PFJ brace in clinical trials on PFJOA. Copyright © 2016. Published by Elsevier Ltd.

  2. Chaos via torus breakdown in the vibration response of a rigid rotor supported by active magnetic bearings

    Energy Technology Data Exchange (ETDEWEB)

    Inayat-Hussain, Jawaid I. [School of Engineering, Monash University Malaysia, No. 2, Jalan Kolej, Bandar Sunway, 46150 Petaling Jaya, Selangor Darul Ehsan (Malaysia)]. E-mail: jawaid.inayat-hussain@eng.monash.edu.my

    2007-02-15

    This work reports on a numerical study undertaken to investigate the response of an imbalanced rigid rotor supported by active magnetic bearings. The mathematical model of the rotor-bearing system used in this study incorporates nonlinearity arising from the electromagnetic force-coil current-air gap relationship, and the effects of geometrical cross-coupling. The response of the rotor is observed to exhibit a rich variety of dynamical behavior including synchronous, sub-synchronous, quasi-periodic and chaotic vibrations. The transition from synchronous rotor response to chaos is via the torus breakdown route. As the rotor imbalance magnitude is increased, the synchronous rotor response undergoes a secondary Hopf bifurcation resulting in quasi-periodic vibration, which is characterized by a torus attractor. With further increase in the rotor imbalance magnitude, this attractor is seen to develop wrinkles and becomes unstable resulting in a fractal torus attractor. The fractal torus is eventually destroyed as the rotor imbalance magnitude is further increased. Quasi-periodic and frequency-locked sub-synchronous vibrations are seen to appear and disappear alternately before the emergence of chaos in the response of the rotor. The magnitude of rotor imbalance where sub-synchronous, quasi-periodic and chaotic vibrations are observed in this study, albeit being higher than the specified imbalance level for rotating machinery, may possibly occur due to a gradual degradation of the rotor balance quality during operation.

  3. Experimental Methodology for Determining Turbomachinery Blade Damping Using Magnetic Bearing Excitation and Non-Contacting Optical Measurements

    Science.gov (United States)

    Provenza, Andrew J.; Duffy, Kirsten P.

    2010-01-01

    Experiments to determine the effects of turbomachinery fan blade damping concepts such as passively shunted piezoelectric materials on blade response are ongoing at the NASA Glenn Research Center. A vertical rotor is suspended and excited with active magnetic bearings (AMBs) usually in a vacuum chamber to eliminate aerodynamic forces. Electromagnetic rotor excitation is superimposed onto rotor PD-controlled support and can be fixed to either a stationary or rotating frame of reference. The rotor speed is controlled with an air turbine system. Blade vibrations are measured using optical probes as part of a Non-Contacting Stress Measurement System (NSMS). Damping is calculated from these measurements. It can be difficult to get accurate damping measurements using this experimental setup and some of the details of how to obtain quality results are seemingly nontrivial. The intent of this paper is to present those details.

  4. Fractional-order system identification and proportional-derivative control of a solid-core magnetic bearing.

    Science.gov (United States)

    Zhong, Jianpeng; Li, Lichuan

    2014-07-01

    This paper presents the application of fractional-order system identification (FOSI) and proportional-derivative (PD(µ)) control to a solid-core magnetic bearing (MB). A practical strategy for closed-loop incommensurate FOSI along with a modified error criterion is utilized to model the MB system and a corresponding, verification experiment is carried out. Based on the identified model, integer-order (IO) PD and fractional-order (FO) PD(µ) controllers are designed and compared with the same specifications. Besides, the relation between the two categories of controllers is discussed by their feasible control zones. Final simulation and experimental results show that the FO PD(µ) controller can significantly improve the transient and steady-state performance of the MB system comparing with the IO PD controller. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  5. Eddy Current Analysis and Optimization for Superconducting Magnetic Bearing of Flywheel Energy Storage System

    Science.gov (United States)

    Arai, Yuuki; Yamashita, Tomohisa; Hasegawa, Hitoshi; Matsuoka, Taro; Kaimori, Hiroyuki; Ishihara, Terumasa

    Levitation and guidance force is electromagnetic generated between a superconducting coil and zero field cooled bulk superconductors used in our flywheel energy storage system (FESS). Because the magnetic field depends on the configuration of the coil and the bulks, the eccentricity and the vibration of a rotor cause fluctuation in the magnetic field which induces eddy current and consequent Joule heat on electric conductors such as cooling plates. Heat generation in the cryogenic region critically reduces the efficiency of the FESS. In this paper, we will report the result of the electromagnetic analysis of the SMB and propose an optimal divided cooling plate for reducing the eddy current and Joule heat.

  6. A novel Planar Magnetic Bearing and Motor Configuration applied in a Positioning Stage

    NARCIS (Netherlands)

    Molenaar, A.

    2000-01-01

    This thesis presents the design and implementation of a fully contactless high precision magnetically suspended position stage with large planar stroke. This stage is the first which is suitable for practical application in vacuum. The underlying electromechanical working principles, modelling and

  7. Inertially stabilized line-of-sight control system using a magnetic bearing with vernier gimbaling capacity

    Science.gov (United States)

    Lin, Zhuchong; Liu, Kun

    2014-11-01

    Line of sight stabilization and control system is widely used in pointing and stabilizing the line of sight of optical sensors. Multi-axis gimbals configurations are commonly used for isolating disturbance from the angular motion of the base where the stabilization platform is mounted. However, in the case of large payload, nonlinear friction and the bandwidth limit of the servo loop can greatly diminish the performance of the whole system. Magnetic actuators, because of their high force per mass capability and non-friction characteristic, are promising means of achieving high-accuracy stabilization. Nevertheless, the gap between magnetic actuators and the payload is very small, which limits the slewing range of the line of sight as well as the angular motion range of the base that can be isolated. A novel two-stage stabilization configuration is developed, which combines multi-axis gimbals configuration and magnetic actuators as well as both of their advantages. At the first stage, a multi-axis gimbals configuration is adopted to isolate the large angular motion of the base while at the second stage magnetic actuators are utilized to perform high-accuracy stabilization. A so-called "stabilizing inside and tracking outside" scheme is carried out to perform two-stage stabilization control. The advantage of this configuration compared with conventional configuration is analyzed through analytical method. Finally, the effectiveness of the design is investigated through simulation studies.

  8. A novel Planar Magnetic Bearing and Motor Configuration applied in a Positioning Stage

    NARCIS (Netherlands)

    Molenaar, A.

    2000-01-01

    This thesis presents the design and implementation of a fully contactless high precision magnetically suspended position stage with large planar stroke. This stage is the first which is suitable for practical application in vacuum. The underlying electromechanical working principles, modelling and a

  9. A novel Planar Magnetic Bearing and Motor Configuration applied in a Positioning Stage

    NARCIS (Netherlands)

    Molenaar, A.

    2000-01-01

    This thesis presents the design and implementation of a fully contactless high precision magnetically suspended position stage with large planar stroke. This stage is the first which is suitable for practical application in vacuum. The underlying electromechanical working principles, modelling and a

  10. A Comparative Analysis of the New Five-Pole and Three-Pole Active Magnet Bearing

    Directory of Open Access Journals (Sweden)

    Pedram Vakili

    2012-07-01

    Full Text Available In recent years, more attention has been given to the active AMBs thanks to their low maintenance cost, suitability for clean environments, and high speed. One of the popular types of AMBs is the three-pole type with integrated and separate cores. Some deficiencies of this type of bearing are its high oscillation, low stability and low efficiency. This paper seeks to analyse the three-pole AMBs and describe their deficiencies and introduce and analyse a new five-pole AMB. The model thus proposed has lower oscillation as well as more stability and efficiency. The five-pole AMB has been simulated by a controller in the presence of disturbance. The results of simulation demonstrate lower vibration and oscillation in the five-pole AMB in comparison with the three-pole model.

  11. Towards Identification of Rotordynamic Properties for Seals in Multiphase Flow Using Active Magnetic Bearings. Design and Commissioning of a Novel Test Facility

    DEFF Research Database (Denmark)

    Voigt, Andreas Jauernik

    scale rotordynamic test bench consisting of two radial active magnetic bearings with an embedded Hall sensor system, a rigid rotor, and a drive unit acts as the hub. In addition, the test facility includes a module facilitating calibration of the state of the art system of Hall sensors which provides...

  12. A drug-specific nanocarrier design for efficient anticancer therapy

    Science.gov (United States)

    Shi, Changying; Guo, Dandan; Xiao, Kai; Wang, Xu; Wang, Lili; Luo, Juntao

    2015-01-01

    The drug-loading properties of nanocarriers depend on the chemical structures and properties of their building blocks. Here, we customize telodendrimers (linear-dendritic copolymer) to design a nanocarrier with improved in vivo drug delivery characteristics. We do a virtual screen of a library of small molecules to identify the optimal building blocks for precise telodendrimer synthesis using peptide chemistry. With rationally designed telodendrimer architectures, we then optimize the drug binding affinity of a nanocarrier by introducing an optimal drug-binding molecule (DBM) without sacrificing the stability of the nanocarrier. To validate the computational predictions, we synthesize a series of nanocarriers and evaluate systematically for doxorubicin delivery. Rhein-containing nanocarriers have sustained drug release, prolonged circulation, increased tolerated dose, reduced toxicity, effective tumor targeting and superior anticancer effects owing to favourable doxorubicin-binding affinity and improved nanoparticle stability. This study demonstrates the feasibility and versatility of the de novo design of telodendrimer nanocarriers for specific drug molecules, which is a promising approach to transform nanocarrier development for drug delivery. PMID:26158623

  13. Development and characterization of magnetic iron oxide nanoparticles with a cisplatin-bearing polymer coating for targeted drug delivery.

    Science.gov (United States)

    Unterweger, Harald; Tietze, Rainer; Janko, Christina; Zaloga, Jan; Lyer, Stefan; Dürr, Stephan; Taccardi, Nicola; Goudouri, Ourania-Menti; Hoppe, Alexander; Eberbeck, Dietmar; Schubert, Dirk W; Boccaccini, Aldo R; Alexiou, Christoph

    2014-01-01

    A highly selective and efficient cancer therapy can be achieved using magnetically directed superparamagnetic iron oxide nanoparticles (SPIONs) bearing a sufficient amount of the therapeutic agent. In this project, SPIONs with a dextran and cisplatin-bearing hyaluronic acid coating were successfully synthesized as a novel cisplatin drug delivery system. Transmission electron microscopy images as well as X-ray diffraction analysis showed that the individual magnetite particles were around 4.5 nm in size and monocrystalline. The small crystallite sizes led to the superparamagnetic behavior of the particles, which was exemplified in their magnetization curves, acquired using superconducting quantum interference device measurements. Hyaluronic acid was bound to the initially dextran-coated SPIONs by esterification. The resulting amide bond linkage was verified using Fourier transform infrared spectroscopy. The additional polymer layer increased the vehicle size from 22 nm to 56 nm, with a hyaluronic acid to dextran to magnetite weight ratio of 51:29:20. A maximum payload of 330 μg cisplatin/mL nanoparticle suspension was achieved, thus the particle size was further increased to around 77 nm with a zeta potential of -45 mV. No signs of particle precipitation were observed over a period of at least 8 weeks. Analysis of drug-release kinetics using the dialysis tube method revealed that these were driven by inverse ligand substitution and diffusion through the polymer shell as well as enzymatic degradation of hyaluronic acid. The biological activity of the particles was investigated in a nonadherent Jurkat cell line using flow cytometry. Further, cell viability and proliferation was examined in an adherent PC-3 cell line using xCELLigence analysis. Both tests demonstrated that particles without cisplatin were biocompatible with these cells, whereas particles with the drug induced apoptosis in a dose-dependent manner, with secondary necrosis after prolonged incubation. In

  14. 飞轮储能用磁力轴承的发展研究%Development Research of Magnetic Bearing Technology for Flywheel Energy Storage System

    Institute of Scientific and Technical Information of China (English)

    陈湘舜; 曾虎彪

    2011-01-01

    飞轮电池以高比能、环境友好等优点成为国内外研究热点.特别是在磁力轴承技术获得突破之后,飞轮储能效率与寿命都得到极大的提高.详细论述了飞轮储能系统中磁力轴承的发展历史与研究现状;对比分析了永磁轴承、电磁轴承和超导磁轴承的优缺点,指出被动磁力轴承对构建经济型飞轮电池的重要性;针对飞轮电池发展的实际需求提出了目前应重点研究的方向.%With the advantages of high energy density, environment friendly and so on, flywheel battery becomes research hotspot at home and abroad.Especially after a breakthrough in the magnetic bearing technology, its energy, storage efficiency and life expectancy have been greatly improved.The history, research status and development trend of magnetic bearing technology for flywheel energy storage system were presented.The merit and demerit of permanent magnetic beating, electromagnetic bearing and superconducting magnetic bearing; were amalyzed in contrast.The importance of passive magnetic bearing on the construction of economical flywheel battery was pointed out.For the actual demand of the flywheel battery development, the focus of current research was proposed.

  15. Determining drug release rates of hydrophobic compounds from nanocarriers.

    Science.gov (United States)

    D'Addio, Suzanne M; Bukari, Abdallah A; Dawoud, Mohammed; Bunjes, Heike; Rinaldi, Carlos; Prud'homme, Robert K

    2016-07-28

    Obtaining meaningful drug release profiles for drug formulations is essential prior to in vivo testing and for ensuring consistent quality. The release kinetics of hydrophobic drugs from nanocarriers (NCs) are not well understood because the standard protocols for maintaining sink conditions and sampling are not valid owing to mass transfer and solubility limitations. In this work, a new in vitroassay protocol based on 'lipid sinks' and magnetic separation produces release conditions that mimic the concentrations of lipid membranes and lipoproteins in vivo, facilitates separation, and thus allows determination of intrinsic release rates of drugs from NCs. The assay protocol is validated by (i) determining the magnetic separation efficiency, (ii) demonstrating that sink condition requirements are met, and (iii) accounting for drug by completing a mass balance. NCs of itraconazole and cyclosporine A (CsA) were prepared and the drug release profiles were determined. This release protocol has been used to compare the drug release from a polymer stabilized NC of CsA to a solid drug NP of CsA alone. These data have led to the finding that stabilizing block copolymer layers have a retarding effect on drug release from NCs, reducing the rate of CsA release fourfold compared with the nanoparticle without a polymer coating.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'.

  16. Magnetocaloric effect in magnetothermally-responsive nanocarriers for hyperthermia-triggered drug release.

    Science.gov (United States)

    Li, Jianbo; Qu, Yang; Ren, Jie; Yuan, Weizhong; Shi, Donglu

    2012-12-21

    The magnetocaloric effects and lower critical solution temperature (LCST) were investigated in a magnetothermally-responsive nanocarrier for magnetothermal drug release under alternating magnetic field (AMF). The Mn(0.2)Zn(0.8)Fe(2)O(4) nanoparticles with low T(c) were dispersed in a polymeric matrix consisting of N-Isopropyl acrylamide (NIPAAm) and N-hydroxymethyl acrylamide (HMAAm). The magnetocaloric effects and LCST of the nanocarriers were characterized by using high-resolution electron transmission microscopy, thermogravimetric analyses, and vibrating sample magnetometer. The maximum self-heating temperature of 42.9 °C was achieved by optimizing the Mn(0.2)Zn(0.8)Fe(2)O(4) concentration in the polymer matrix. By adjusting the NIPAAm to HMAAm ratio, the LCST was controlled at an ideal level of 40.1 °C for efficient thermosensitive drug delivery. Magnetothermally responsive drug release of Doxorubicin, an anticancer drug, was significantly enhanced by application of an external AMF on the nanocarriers. The cytotoxicity experimental results in vitro show good biocompatibility and efficient therapeutic effects in cancer treatment.

  17. Genetically engineered nanocarriers for drug delivery

    Directory of Open Access Journals (Sweden)

    Shi P

    2014-03-01

    Full Text Available Pu Shi, Joshua A Gustafson, J Andrew MacKayDepartment of Pharmacology and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA, USAAbstract: Cytotoxicity, low water solubility, rapid clearance from circulation, and off-target side-effects are common drawbacks of conventional small-molecule drugs. To overcome these shortcomings, many multifunctional nanocarriers have been proposed to enhance drug delivery. In concept, multifunctional nanoparticles might carry multiple agents, control release rate, biodegrade, and utilize target-mediated drug delivery; however, the design of these particles presents many challenges at the stage of pharmaceutical development. An emerging solution to improve control over these particles is to turn to genetic engineering. Genetically engineered nanocarriers are precisely controlled in size and structure and can provide specific control over sites for chemical attachment of drugs. Genetically engineered drug carriers that assemble nanostructures including nanoparticles and nanofibers can be polymeric or non-polymeric. This review summarizes the recent development of applications in drug and gene delivery utilizing nanostructures of polymeric genetically engineered drug carriers such as elastin-like polypeptides, silk-like polypeptides, and silk-elastin-like protein polymers, and non-polymeric genetically engineered drug carriers such as vault proteins and viral proteins.Keywords: polymeric drug carrier, non-polymeric drug carrier, gene delivery, GE drug carriers

  18. Development and characterization of magnetic iron oxide nanoparticles with a cisplatin-bearing polymer coating for targeted drug delivery

    Directory of Open Access Journals (Sweden)

    Unterweger H

    2014-08-01

    Full Text Available Harald Unterweger,1 Rainer Tietze,1 Christina Janko,1 Jan Zaloga,1 Stefan Lyer,1 Stephan Dürr,1 Nicola Taccardi,2 Ourania-Menti Goudouri,3 Alexander Hoppe,3 Dietmar Eberbeck,4 Dirk W Schubert,5 Aldo R Boccaccini,3 Christoph Alexiou1 1ENT Department, Section of Experimental Oncology and Nanomedicine (SEON, Else Kroener-Fresenius-Stiftung-Professorship, University Hospital Erlangen, 2Chair of Chemical Engineering I (Reaction Engineering, 3Institute of Biomaterials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, 4Physikalisch-Technische Bundesanstalt, Berlin, 5Institute of Polymer Materials, Department of Materials Science and Engineering, University Erlangen-Nuremberg, Erlangen, Germany Abstract: A highly selective and efficient cancer therapy can be achieved using magnetically directed superparamagnetic iron oxide nanoparticles (SPIONs bearing a sufficient amount of the therapeutic agent. In this project, SPIONs with a dextran and cisplatin-bearing hyaluronic acid coating were successfully synthesized as a novel cisplatin drug delivery system. Transmission electron microscopy images as well as X-ray diffraction analysis showed that the individual magnetite particles were around 4.5 nm in size and monocrystalline. The small crystallite sizes led to the superparamagnetic behavior of the particles, which was exemplified in their magnetization curves, acquired using superconducting quantum interference device measurements. Hyaluronic acid was bound to the initially dextran-coated SPIONs by esterification. The resulting amide bond linkage was verified using Fourier transform infrared spectroscopy. The additional polymer layer increased the vehicle size from 22 nm to 56 nm, with a hyaluronic acid to dextran to magnetite weight ratio of 51:29:20. A maximum payload of 330 µg cisplatin/mL nanoparticle suspension was achieved, thus the particle size was further increased to around 77 nm with a zeta

  19. Ultrasound-Mediated Local Drug and Gene Delivery Using Nanocarriers

    Directory of Open Access Journals (Sweden)

    Qiu-Lan Zhou

    2014-01-01

    Full Text Available With the development of nanotechnology, nanocarriers have been increasingly used for curative drug/gene delivery. Various nanocarriers are being introduced and assessed, such as polymer nanoparticles, liposomes, and micelles. As a novel theranostic system, nanocarriers hold great promise for ultrasound molecular imaging, targeted drug/gene delivery, and therapy. Nanocarriers, with the properties of smaller particle size, and long circulation time, would be advantageous in diagnostic and therapeutic applications. Nanocarriers can pass through blood capillary walls and cell membrane walls to deliver drugs. The mechanisms of interaction between ultrasound and nanocarriers are not clearly understood, which may be related to cavitation, mechanical effects, thermal effects, and so forth. These effects may induce transient membrane permeabilization (sonoporation on a single cell level, cell death, and disruption of tissue structure, ensuring noninvasive, targeted, and efficient drug/gene delivery and therapy. The system has been used in various tissues and organs (in vitro or in vivo, including tumor tissues, kidney, cardiac, skeletal muscle, and vascular smooth muscle. In this review, we explore the research progress and application of ultrasound-mediated local drug/gene delivery with nanocarriers.

  20. Dextran-functionalized magnetic fluid mediating magnetohyperthermia for treatment of Ehrlich-solid-tumor-bearing mice: toxicological and histopathological evaluations.

    Science.gov (United States)

    Miranda-Vilela, Ana Luisa; Yamamoto, Kelly Reis; Miranda, Kely Lopes Caiado; Matos, Breno Noronha; de Almeida, Marcos Célio; Longo, João Paulo Figueiró; de Souza Filho, José; Fernandes, Juliana Menezes Soares; Sartoratto, Patrícia Pommé Confessori; Lacava, Zulmira Guerrero Marques

    2014-04-01

    Dextran-functionalized maghemite fluid (DexMF) has been tested to treat Ehrlich-solid-tumor-bearing mice, evidencing its potential use in mediating magnetohyperthermia in breast cancer treatment. However, although magnetic nanoparticles tend to accumulate in tumor tissues, part of the nanomaterial can reach the blood stream, and then the organism. The aim of this study was to investigate the acute systemic effects of the intratumoral injection of DexMF mediating magnetohyperthermia in the treatment of an advanced clinical Ehrlich-solid-tumor, assessed through histopathological analyses of liver, kidneys, heart and spleen, comet assay, micronucleus test, hemogram, and serum levels of bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma glutamyl transferase, alkaline phosphatase, creatinine, and urea. The tumor's histopathology and morphometry were used to assess its aggressiveness and regression. DexMF mediating hyperthermia was effective in containing tumor aggressiveness and in inducing tumor regression, besides showing no toxic effects. Its physical characteristics also suggest that it is safe to use in other biomedical applications.

  1. Elimination of Harmonic Force and Torque in Active Magnetic Bearing Systems with Repetitive Control and Notch Filters.

    Science.gov (United States)

    Xu, Xiangbo; Chen, Shao; Liu, Jinhao

    2017-04-04

    Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB) systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load.

  2. Elimination of Harmonic Force and Torque in Active Magnetic Bearing Systems with Repetitive Control and Notch Filters

    Directory of Open Access Journals (Sweden)

    Xiangbo Xu

    2017-04-01

    Full Text Available Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load.

  3. Modal Tilt/Translate Control and Stability of a Rigid Rotor with Gyroscopics on Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    Timothy Dimond

    2012-01-01

    Full Text Available Most industrial rotors supported in active magnetic bearings (AMBs are operated well below the first bending critical speed. Also, they are usually controlled using proportional, integral and derivative controllers, which are set up as modally uncoupled parallel and tilt rotor axes. Gyroscopic effects create mode splitting and a speed-dependent plant. Two AMBs with four axes of control must simultaneously control and stabilize the rotor/AMB system. Various analyses have been published considering this problem for different rotor/AMB configurations. There has not been a fully dimensionless analysis of these rigid rotor AMB systems. This paper will perform this analysis with a modal PD controller in terms of translation mode and tilt mode dimensionless eigenvalues and eigenvectors. The number of independent system parameters is significantly reduced. Dimensionless PD controller gains, the ratio of rotor polar to transverse moments of inertia and a dimensionless speed ratio are used to evaluate a fully general system stability rigid rotor analysis. An objective of this work is to quantify the effects of gyroscopics on rigid rotor AMB systems. These gyroscopic forces reduce the system stability margin. The paper is also intended to help provide a common framework for communication between rotating machinery designers and controls engineers

  4. Cytosolic co-delivery of miRNA-34a and docetaxel with core-shell nanocarriers via caveolae-mediated pathway for the treatment of metastatic breast cancer

    Science.gov (United States)

    Zhang, Li; Yang, Xin; Lv, Yaqi; Xin, Xiaofei; Qin, Chao; Han, Xiaopeng; Yang, Lei; He, Wei; Yin, Lifang

    2017-04-01

    Co-delivery of microRNAs and chemotherapeutic drugs into tumor cells is an attractive strategy for synergetic breast cancer therapy due to their complementary mechanisms. In this work, a core-shell nanocarrier coated by cationic albumin was developed to simultaneously deliver miRNA-34a and docetaxel (DTX) into breast cancer cells for improved therapeutic effect. The co-delivery nanocarriers showed a spherical morphology with an average particle size of 183.9 nm, and they efficiently protected miRNA-34a from degradation by RNase and serum. Importantly, the nanocarriers entered the cytosol via a caveolae-mediated pathway without entrapment in endosomes/lysosomes, thus improving the utilization of the cargo. In vitro, the co-delivery nanocarriers suppressed the expression of anti-apoptosis gene Bcl-2 at both transcription and protein levels, inhibited tumor cell migration and efficiently induced cell apoptosis and cytotoxicity. In vivo, the co-delivery nanocarriers prolonged the blood circulation of DTX, enhanced tumor accumulation of the cargo and significantly inhibited tumor growth and metastasis in 4T1-tumor bearing mice models. Taken together, the present nanocarrier co-loading with DTX and miRNA-34a is a new nanoplatform for the combination of insoluble drugs and gene/protein drugs and provides a promising strategy for the treatment of metastatic breast cancer.

  5. Effects of upright weight bearing and the knee flexion angle on patellofemoral indices using magnetic resonance imaging in patients with patellofemoral instability.

    Science.gov (United States)

    Becher, Christoph; Fleischer, Benjamin; Rase, Marten; Schumacher, Thees; Ettinger, Max; Ostermeier, Sven; Smith, Tomas

    2017-08-01

    This study analysed the effects of upright weight bearing and the knee flexion angle on patellofemoral indices, determined using magnetic resonance imaging (MRI), in patients with patellofemoral instability (PI). Healthy volunteers (control group, n = 9) and PI patients (PI group, n = 16) were scanned in an open-configuration MRI scanner during upright weight bearing and supine non-weight bearing positions at full extension (0° flexion) and at 15°, 30°, and 45° flexion. Patellofemoral indices included the Insall-Salvati Index, Caton-Deschamp Index, and Patellotrochlear Index (PTI) to determine patellar height and the patellar tilt angle (PTA), bisect offset (BO), and the tibial tubercle-trochlear groove (TT-TG) distance to assess patellar rotation and translation with respect to the femur and alignment of the extensor mechanism. A significant interaction effect of weight bearing by flexion angle was observed for the PTI, PTA, and BO for subjects with PI. At full extension, post hoc pairwise comparisons revealed a significant effect of weight bearing on the indices, with increased patellar height and increased PTA and BO in the PI group. Except for the BO, no such changes were seen in the control group. Independent of weight bearing, flexing the knee caused the PTA, BO, and TT-TG distance to be significantly reduced. Upright weight bearing and the knee flexion angle affected patellofemoral MRI indices in PI patients, with significantly increased values at full extension. The observations of this study provide a caution to be considered by professionals when treating PI patients. These patients should be evaluated clinically and radiographically at full extension and various flexion angles in context with quadriceps engagement. Explorative case-control study, Level III.

  6. Robust Stability and Robust H2 and H-infinity Output-Feedback Control of a Magnetic Bearing System via LMI Optimization

    Directory of Open Access Journals (Sweden)

    MohammadReza Davoodi

    2009-12-01

    Full Text Available This paper offers a design procedure for robust stability, robust H-infinity control and robust H2 control via dynamic output feedback for a class of uncertain linear systems. The uncertainties are of norm bounded type. Then in order to support a high-speed energy storage flywheel, these procedures are applied to an active radial magnetic bearing system. The state space matrices of this controller are the solution of some linear matrix inequalities (LMIs.

  7. Nanocarriers for delivery of platinum anticancer drugs☆

    Science.gov (United States)

    Oberoi, Hardeep S.; Nukolova, Natalia V.; Kabanov, Alexander V.; Bronich, Tatiana K.

    2014-01-01

    Platinum based anticancer drugs have revolutionized cancer chemotherapy, and continue to be in widespread clinical use especially for management of tumors of the ovary, testes, and the head and neck. However, several dose limiting toxicities associated with platinum drug use, partial anti-tumor response in most patients, development of drug resistance, tumor relapse, and many other challenges have severely limited the patient quality of life. These limitations have motivated an extensive research effort towards development of new strategies for improving platinum therapy. Nanocarrier-based delivery of platinum compounds is one such area of intense research effort beginning to provide encouraging preclinical and clinical results and may allow the development of the next generation of platinum chemotherapy. This review highlights current understanding on the pharmacology and limitations of platinum compounds in clinical use, and provides a comprehensive analysis of various platinum–polymer complexes, micelles, dendrimers, liposomes and other nanoparticles currently under investigation for delivery of platinum drugs. PMID:24113520

  8. Targeted Delivery of Protein Drugs by Nanocarriers

    Directory of Open Access Journals (Sweden)

    Antonella Battisti

    2010-03-01

    Full Text Available Recent advances in biotechnology demonstrate that peptides and proteins are the basis of a new generation of drugs. However, the transportation of protein drugs in the body is limited by their high molecular weight, which prevents the crossing of tissue barriers, and by their short lifetime due to immuno response and enzymatic degradation. Moreover, the ability to selectively deliver drugs to target organs, tissues or cells is a major challenge in the treatment of several human diseases, including cancer. Indeed, targeted delivery can be much more efficient than systemic application, while improving bioavailability and limiting undesirable side effects. This review describes how the use of targeted nanocarriers such as nanoparticles and liposomes can improve the pharmacokinetic properties of protein drugs, thus increasing their safety and maximizing the therapeutic effect.

  9. Bio-inspired cisplatin nanocarriers for osteosarcoma treatment

    National Research Council Canada - National Science Library

    Zhou, Haidong; Wang, Gangxiang; Lu, Yiyun; Pan, Zhijun

    2016-01-01

    In this study, cisplatin ( cis -diaminedichloroplatinum, CDDP) nanocarriers with phosphorylcholine surface tailoring were developed to enhance the anti-tumor potential of CDDP for the treatment of osteosarcoma. Poly...

  10. Phase diagram and magnetic structures of the Co-bearing dugganites Pb3TeCo3A2O14 (A = V, P).

    Science.gov (United States)

    Silverstein, H J; Sharma, A Z; Stoller, A J; Cruz-Kan, K; Flacau, R; Donaberger, R L; Zhou, H D; Manuel, P; Huq, A; Kolesnikov, A I; Wiebe, C R

    2013-06-19

    Exhibiting rich magnetic behaviour and potentially multiferroic properties, the dugganites, a Te(6+) containing subgroup of the langasite series, are an attractive family of compounds for future study. It was recently shown that Pb-bearing members of the dugganite series undergo distortions away from the P321 symmetry that is characteristic of the langasites. Here, we detail the consequences these distortions have on the magnetism exhibited by Pb3TeCo3V2O14 and Pb3TeCo3P2O14, solving the magnetic structures of both compounds with respect to a new supercell. Using neutron scattering and magnetic susceptibility measurements, we show that small applied magnetic fields can seriously perturb the delicate magnetic states in both of these systems. This is further demonstrated by presenting how doping P(5+) onto the nonmagnetic V(5+) site completely changes the magnetic structure from either of the end series members. Finally, it is shown using inelastic neutron scattering and magnetic susceptibility measurements that Pb3TeCo3V2O14 can be characterized using a model for isosceles trimers, which do not exist in the previously reported P321 subcell.

  11. 交流混合型磁轴承磁场及悬浮力特性分析%Magnetic Field and Characteristic Analysis of Suspension Forces for Radial AC Hybrid Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    张松; 张维煜; 朱熀秋

    2012-01-01

    对交流混合型磁轴承的组成结构和基本工作原理进行了介绍,并针对该交流混合型磁轴承的悬浮力进行了数学模型的建立,而且通过泰勒公式近似获得其线性模型.文中创建了该磁轴承的实体模型,利用Ansoft 软件仿真并分析了该交流磁轴承的磁通分布状况(气隙及磁极内部);采用Ansoft分析软件与MATLAB软件对交流磁轴承悬浮力的非线性变化规律进行了计算分析.仿真结果表明:磁通密度的分布在磁轴承中,其仿真值和理论设计值几乎吻合,说明该磁轴承计算设计的参数有效;基于数学模型和有限元实体模型的交流混合型磁轴承特性分析结果一致,表明该磁轴承的数学模型建立正确,逼近磁轴承实际工作情况下的模型.%Configuration and operation principle of the radial AC hybrid magnetic bearing ( AC HMB) were introduced , the mathematical models of suspension forces were deduced with the method of equivalent magnetic circuits, and the linearity models about the equilibrium position were obtained by using their Taylor expansions. Based on the establishment of finite element solid models of the magnetic bearing in Ansoft finite element analysis software, the magnetic field distributions in air gap and magnetic pole of the AC HMB were calculated. The nonlinear variation of suspension forces of the magnetic bearing was calculated with Ansoft finite element and MATLAB software respectively. The simulation results show that the magnetic field distribution in magnetic bearing is consistent with the theoretical design, and the designing of structural parameters is reasonable. Results also show that the characteristic analysis results based on the mathematical models and finite element solid models of the AC HMB are consistent, and the mathematical model is proved correct, which is close to the model of the magnetic bearing under actual conditions.

  12. Soft Interaction in Liposome Nanocarriers for Therapeutic Drug Delivery

    Directory of Open Access Journals (Sweden)

    Domenico Lombardo

    2016-06-01

    Full Text Available The development of smart nanocarriers for the delivery of therapeutic drugs has experienced considerable expansion in recent decades, with the development of new medicines devoted to cancer treatment. In this respect a wide range of strategies can be developed by employing liposome nanocarriers with desired physico-chemical properties that, by exploiting a combination of a number of suitable soft interactions, can facilitate the transit through the biological barriers from the point of administration up to the site of drug action. As a result, the materials engineer has generated through the bottom up approach a variety of supramolecular nanocarriers for the encapsulation and controlled delivery of therapeutics which have revealed beneficial developments for stabilizing drug compounds, overcoming impediments to cellular and tissue uptake, and improving biodistribution of therapeutic compounds to target sites. Herein we present recent advances in liposome drug delivery by analyzing the main structural features of liposome nanocarriers which strongly influence their interaction in solution. More specifically, we will focus on the analysis of the relevant soft interactions involved in drug delivery processes which are responsible of main behaviour of soft nanocarriers in complex physiological fluids. Investigation of the interaction between liposomes at the molecular level can be considered an important platform for the modeling of the molecular recognition processes occurring between cells. Some relevant strategies to overcome the biological barriers during the drug delivery of the nanocarriers are presented which outline the main structure-properties relationships as well as their advantages (and drawbacks in therapeutic and biomedical applications.

  13. APPLICATION OF SIMPLEX METHOD TO SYSTEM IDENTIFICATIONFOR MAGNETIC BEARINGS%单纯形法实现系统辨识及其在磁轴承中的应用

    Institute of Scientific and Technical Information of China (English)

    杨作兴

    2000-01-01

    A simply and flexible simplex identification method is presented in thispaper for system identification on complex object function in control.This method has been applied to linearize complex nonlinear magneticbearing system. This result is very important to analyze the state ofmagnetic bearing in small range and to explore the method to improve theperformance of magnetic bearing.

  14. Mixed-mu superconducting bearings

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

    1998-01-01

    A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

  15. Self-Assembled Polymeric Micellar Nanoparticles as Nanocarriers for Poorly Soluble Anticancer Drug Ethaselen

    Directory of Open Access Journals (Sweden)

    Yang Zhuoli

    2009-01-01

    Full Text Available Abstract A series of monomethoxy poly(ethylene glycol-poly(lactide (mPEG-PLA diblock copolymers were synthesized, and mPEG-PLA micelle was fabricated and used as a nanocarrier for solubilization and delivery of a promising anticancer drug ethaselen. Ethaselen was efficiently encapsulated into the micelles by the dialysis method, and the solubility of ethaselen in water was remarkably increased up to 82 μg/mL before freeze-drying. The mean diameter of ethaselen-loaded micelles ranged from 51 to 98 nm with a narrow size distribution and depended on the length of PLA block. In vitro hemolysis study indicated that mPEG-PLA copolymers and ethaselen-loaded polymeric micelles had no hemolytic effect on the erythrocyte. The enhanced antitumor efficacy and reduced toxic effect of ethaselen-loaded polymeric micelle when compared with ethaselen-HP-β-CD inclusion were observed at the same dose in H22human liver cancer cell bearing mouse models. These suggested that mPEG-PLA polymeric micelle nanoparticles had great potential as nanocarriers for effective solubilization of poorly soluble ethaselen and further reducing side effects and toxicities of the drug.

  16. R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers. Final report 1.10.1983 - 31.3.1991; F+E-Arbeiten fuer die Weiterentwicklung von Hochtemperaturreaktoren. (1) Fanglagerversuche fuer aktive Magnetlager. (2) Fanglagertest fuer HTR-Geblaese. Abschlussbericht. 1.10.1983 - 31.3.1991

    Energy Technology Data Exchange (ETDEWEB)

    1991-03-14

    When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years` operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL). [Deutsch] Beim Einsatz von aktiven Magnetlagern als Geblaesewellenlagerung sind Geblaesemotor und -lager vor mechanischer Schaedigung im Stoerfall (Beispiel: totaler Stromausfall durch Bruch der Versorgungskabel) zu schuetzen. Um bei derartigen Stoerfaellen die Geblaese sicher abfahren zu koennen, werden sogenannte Fanglager vorgesehen. Diese Fanglager sind Waelzlager, die im Bereich der Geblaesewellenlagerung zusaetzlich angebracht werden, um einen mechanischen Kontakt zwischen Geblaesemotor und -stator zu verhindern. Da fuer die vorgegebenen Randbedingungen, wie - Drehzahl, - Beschleunigung, - Lagerbelastung, - Lagerabmessungen, Umgebungsbedingungen nur geringe Erfahrungen vorlagen, mussten entsprechende Entwicklungen und Versuche durchgefuehrt werden. Hierbei galt es, geeignete Fanglager und die erforderlichen Umgebungsbedingungen zu ermitteln, die es ermoeglichen, die in 40 Betriebsjahren des Reaktors zu erwartenden Ausfaelle der

  17. Tumor-targeting and pH-sensitive lipoprotein-mimic nanocarrier for targeted intracellular delivery of paclitaxel.

    Science.gov (United States)

    Chen, Conghui; Hu, Haiyang; Qiao, Mingxi; Zhao, Xiuli; Wang, Yinjie; Chen, Kang; Guo, Xiong; Chen, Dawei

    2015-03-01

    In the present study, we constructed a tumor-targeting and pH-sensitive lipoprotein-mimic nanocarrier containing paclitaxel (FA-BSA-LC/DOPE-PTX), by adding 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and oleic acid as pH-sensitive components into the formulation of lipid core and then coating with folic acid modified bovine serum albumin (FA-BSA) for tumor targeting activity. In vitro drug release study demonstrated that paclitaxel (PTX) was released from FA-BSA-LC/DOPE in a pH-dependent manner. The vitro cytotoxicity assays showed that all the blank nanocarriers were nontoxic. However, MTT assay showed that FA-BSA-LC/DOPE-PTX was highly cytotoxic. Cellular uptake experiments analyzed with flow cytometry and laser scan confocal microscope (LSCM) revealed that FA-BSA-LC/DOPE was taken up in great amount via folate receptor-mediated endocytosis and pH-sensitive release of drug to cytoplasm. Furthermore, the study of intracellular drug release behavior demonstrated that the FA-BSA-LC/DOPE escaped from lysosomes and released drug into cytoplasm. The in vivo targeting activity showed that the nanocarrier selectively targeted tumor and had long residence time for BSA layer increased the stability in blood. Moreover, FA-BSA-LC/DOPE-PTX produced very marked anti-tumor activity in tumor-bearing mice in vivo. Therefore, FA-BSA-LC/DOPE as biocompatible, tumor-targeting and pH-sensitive lipoprotein-mimic nanocarrier is a promising system for effective intracellular delivery of PTX to tumor.

  18. Engineering the Surface of Smart Nanocarriers Using a pH-/Thermal-/GSH-Responsive Polymer Zipper for Precise Tumor Targeting Therapy In Vivo.

    Science.gov (United States)

    Zhang, Penghui; Wang, Yan; Lian, Jing; Shen, Qi; Wang, Chen; Ma, Bohan; Zhang, Yuchao; Xu, Tingting; Li, Jianxin; Shao, Yongping; Xu, Feng; Zhu, Jun-Jie

    2017-07-18

    Nanocarrier surface chemistry plays a vital role in mediating cell internalization and enhancing delivery efficiency during in vivo chemotherapy. Inspired by the ability of proteins to alter their conformation to mediate functions, a pH-/thermal-/glutathione-responsive polymer zipper consisting of cell-penetrating poly(disulfide)s and thermosensitive polymers bearing guanidinium/phosphate (Gu(+) /pY(-) ) motifs to spatiotemporally tune the surface composition of nanocarriers for precise tumor targeting and efficient drug delivery is developed. Surface engineering allows the nanocarriers to remain undetected during blood circulation and favors passive accumulation at tumor sites, where the acidic microenvironment and photothermal heating break the pY(-) /Gu(+) binding and rupture the zipper, thereby exposing the penetrating shell and causing enhanced cellular uptake via counterion-/thiol-/receptor-mediated endocytosis. The in vivo study demonstrates that by manipulating the surface states on command, the nanocarriers show longer blood circulation time, minimized uptake and drug leakage in normal organs, and enhanced accumulation and efficient drug release at tumor sites, greatly inhibiting tumor growth with only slight damage to normal tissues. If integrated with a photothermal dye approved by the U.S. Food and Drug Administration (FDA), polymer zipper would provide a versatile protocol for engineering nanomedicines with high selectivity and efficiency for clinical cancer treatment. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Precise control of a four degree-of-freedom permanent magnet biased active magnetic bearing system in a magnetically suspended direct-driven spindle using neural network inverse scheme

    Science.gov (United States)

    Sun, Xiaodong; Su, Bokai; Chen, Long; Yang, Zebin; Xu, Xing; Shi, Zhou

    2017-05-01

    The capacity of improving the control accuracy and dynamic performance of a four degree-of-freedom (DOF) permanent magnet biased active magnetic bearing (PMBAMB) system is critical to developing and maintaining a high precision application in a magnetically suspended direct-driven spindle system. The 4-DOF PMBAMB system, however, is a multivariable, strong coupled and nonlinear system with unavoidable and unmeasured external disturbances, in addition to having parameter variations. The satisfactory control performance cannot be obtained by using traditional strategies. Therefore, it is important to present a novel control scheme to construct a robust controller with good closed-loop capability. This paper proposes a new decoupling control scheme for a 4-DOF PMBAMB in a direct-driven spindle system based on the neural network inverse (NNI) and 2- degree-of-freedom (DOF) internal model control method. By combining the inversion of the 4-DOF PMBAMB system with its original system, a new pseudolinear system can be developed. In addition, by introducing the 2-DOF internal model controller into the pseudolinear system to design extra closed-loop controllers, we can effectively eliminate the influence of the unmodeled dynamics to the decoupling control accuracy, as well as adjust the properties of tracking and disturbance rejection independently. The experimental results demonstrate the effectiveness of the proposed control scheme.

  20. Noscapine chemosensitization enhances docetaxel anticancer activity and nanocarrier uptake in triple negative breast cancer

    Science.gov (United States)

    Doddapaneni, Ravi; Patel, Ketan; Chowdhury, Nusrat; Singh, Mandip

    2016-01-01

    Chemosensitization and enhanced delivery to solid tumor are widely explored strategies to augment the anticancer efficacy of existing chemotherapeutics agents. The aim of current research was to investigate the role of low dose Noscapine (Nos) in potentiating docetaxel cytotoxicity and enhancing tumor penetration of nanocarriers. The objectives are; (1) To evaluate the chemo-sensitizing effect of Nos in combination with docetaxel (DTX), and to elucidate the possible mechanism (2) To investigate the effect of low dose Nos on tumor stroma and enhancing nanocarrier uptake in triple negative breast cancer (TNBC) bearing nude mice. Cytotoxicity and flow cytometry analysis of DTX in Nos (4 µM) pre-treated MDA-MB-231 cells showed 3.0-fold increase in cell killing and 30% increase in number of late apoptotic cells, respectively. Stress transducer p38 phosphorylation was significantly upregulated with Nos exposure. DTX showed remarkable downregulation in expression of bcl-2, survivin and pAKT in Nos pre-treated MDA-MB-231 cells. Nos pre-sensitization significantly (p < 0.02) enhanced the anti-migration effect of DTX. In vivo studies in orthotopic TNBC tumor bearing mice showed marked reduction in tumor collagen-I levels and significantly (p < 0.03) higher intra-tumoral uptake of coumarin-6 loaded PEGylated liposomes (7-fold) in Nos treated group. Chemo-sensitization and anti-fibrotic effect of Nos could be a promising approach to increase anticancer efficacy of DTX which can be used for other nanomedicinal products. PMID:27177833

  1. Polyacrylamide based ICG nanocarriers for enhanced fluorescence and photoacoustic imaging

    Science.gov (United States)

    Ray, Aniruddha; Yoon, Hyung Ki; Ryu, HeeJu; Koo Lee, Yong-Eun; Kim, Gwangseong; Wang, Xueding; Kopelman, Raoul

    2013-02-01

    Indocyanine green (ICG) is an FDA approved tricarbocyanine dye. This dye, with a strong absorbance in the near infrared (NIR) region, has been extensively used for fluorescence and photoacoustic imaging in vivo. ICG in its free form, however, has a few drawbacks that limit its in vivo applications, such as non-targetability, tendency to form aggregates which changes its optical properties, fast degradation, short plasma lifetime and reduced fluorescence at body temperature. In order to bypass these inherent drawbacks, we demonstrate a polyacrylamide based nanocarrier that was particularly designed to carry the negatively charged ICG molecules. These nanocarriers are biodegradable, biocompatible and can be specifically targeted to any cell or tissue. Using these nanocarriers we avoid all the problems associated with free ICG, such as degradation, aggregation and short plasma lifetime, and also enhance demonstrate its ability towards photoacoustics and fluorescence imaging.

  2. Assessing biocompatibility of graphene oxide-based nanocarriers: A review.

    Science.gov (United States)

    Kiew, Siaw Fui; Kiew, Lik Voon; Lee, Hong Boon; Imae, Toyoko; Chung, Lip Yong

    2016-03-28

    Graphene oxide (GO)-based nanocarriers have been frequently studied due to their high drug loading capacity. However, the unsatisfactory biocompatibility of these GO-based nanocarriers hampers their use in clinical settings. This review discusses how each of the physicochemical characteristics (e.g., size, surface area, surface properties, number of layers and particulate states) and surface coatings on GO affect its in vitro and in vivo nanotoxicity. We provide an overview on the effect of GO properties on interactions with cells such as red blood cells, macrophages and cell lines, and experimental organisms including rodents, rabbits and Zebrafish, offering some guidelines for development of safe GO-based nanocarriers. We conclude the paper by outlining the challenges involving GO-based formulations and future perspectives of this research in the biomedical field.

  3. Structural Design and Simulation Analysis of Five Freedom Degree Magnetic Bearings Electric Spindle%五自由度磁悬浮电主轴的结构设计与仿真

    Institute of Scientific and Technical Information of China (English)

    陈瑞; 刘贤兴

    2011-01-01

    Based on the traditional structure of five freedom degree magnetic bearings electric spindle, the two parts of five freedom degree magnetic bearings electric spindle were introduced, which were three freedom degree permanent magnet bias mixed magnetic bearings and two freedom degree magnetic bearings asynchronous motor. Firstly, the prototype of five freedom degree magnetic bearings electric spindle was designed, and then the magnetic force and levitation force by electromagnetic analysis software Asoft/Maxwell was analyzed, thus verifying the structure and parameter rationality of the prototype. Finally, the simulation model of control system in Matlab/Simulink was constructed and some related simulation was did, which lays foundation for establishing the control system of the magnetic bearings electric spindle.%在传统五自由度磁悬浮电主轴结构的基础上,提出了一种由永磁偏置三自由度混合磁轴承和二自由度磁悬浮异步电机构成的五自由度磁悬浮电主轴结构.设计了五自由度磁悬浮电主轴的试验样机,通过电磁场分析软件Asoft/Maxwell分析了样机的磁场和悬浮力,验证了所设计样机结构和参数的合理性.在MATLAB/Simulink环境下构建了控制系统的仿真模型,进行了相关的仿真研究,为磁悬浮电主轴数字控制系统的建立奠定了基础.

  4. Plantar fascia evaluation with a dedicated magnetic resonance scanner in weight-bearing position: our experience in patients with plantar fasciitis and in healthy volunteers.

    Science.gov (United States)

    Sutera, R; Iovane, A; Sorrentino, F; Candela, F; Mularo, V; La Tona, G; Midiri, M

    2010-03-01

    This study assessed the usefulness of upright weight-bearing examination of the ankle/hind foot performed with a dedicated magnetic resonance (MR) imaging scanner in the evaluation of the plantar fascia in healthy volunteers and in patients with clinical evidence of plantar fasciitis. Between January and March 2009, 20 patients with clinical evidence of plantar fasciitis (group A) and a similar number of healthy volunteers (group B) underwent MR imaging of the ankle/hind foot in the upright weight-bearing and conventional supine position. A 0.25-Tesla MR scanner (G-Scan, Esaote SpA, Genoa, Italy) was used with a dedicated receiving coil for the ankle/hind foot. Three radiologists, blinded to patients' history and clinical findings, assessed in consensus morphological and dimensional changes and signal intensity alterations on images acquired in both positions, in different sequences and in different planes. In group A, MR imaging confirmed the diagnosis in 15/20 cases; in 4/15 cases, a partial tear of the plantar fascia was identified in the upright weight-bearing position alone. In the remaining 5/20 cases in group A and in all cases in group B, the plantar fascia showed no abnormal signal intensity. Because of the increased stretching of the plantar fascia, in all cases in group A and B, thickness in the proximal third was significantly reduced (pbearing compared with the supine position. Imaging the ankle/hind foot in the upright weight-bearing position with a dedicated MR scanner and a dedicated coil might enable the identification of partial tears of the plantar fascia, which could be overlooked in the supine position.

  5. The timeline of corona formation around silica nanocarriers highlights the role of the protein interactome.

    Science.gov (United States)

    Pisani, Cédric; Gaillard, Jean-Charles; Odorico, Michaël; Nyalosaso, Jeff L; Charnay, Clarence; Guari, Yannick; Chopineau, Joël; Devoisselle, Jean-Marie; Armengaud, Jean; Prat, Odette

    2017-02-02

    Magnetic mesoporous silica nanoparticles (M-MSNs) represent promising targeting tools for theranostics. Engineering the interaction of nanoparticles (NPs) with biological systems requires an understanding of protein corona formation around the nanoparticles as this drives the biological fate of nanocarriers. We investigated the behavior of proteins in contact with M-MSNs by high-throughput comparative proteomics, using human and bovine sera as biological fluids, in order to assess the adsorption dynamics of proteins in these media. Using system biology tools, and especially protein-protein interaction databases, we demonstrated how the protein network builds up within the corona over the course of the experiment. Based on these results, we introduce and discuss the role of the "corona interactome" as an important factor influencing protein corona evolution. The concept of the "corona interactome" is an original methodology which could be generalized to all NP candidates. Based on this, pre-coating nanocarriers with specific proteins presenting minimal interactions with opsonins might provide them with properties such as stealth.

  6. Novel magnetic nanoparticles coated by benzene- and β-cyclodextrin-bearing dextran, and the sorption of polycyclic aromatic hydrocarbon

    DEFF Research Database (Denmark)

    Cho, Eunae; Tahir, Muhammad Nazir; Min Choi, Jae

    2015-01-01

    We present the synthesis of novel magnetic nanoparticles functionalized by benzene- and β-cyclodextrin-derivatized dextran. The grafting strategy was based on the [alkynyl-iron] cluster in the modified dextrans, which were prepared by click reaction from alkyne-modified dextran and benzyl azide...... or mono-6-O-deoxy-monoazido β-cyclodextrin. Characterization was then carried out by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. Using the developed magnetic nanoparticles...... to be significant. Furthermore, the polysaccharide derivative-coated magnetic adsorbents could be recovered by an external magnet for reuse....

  7. Statistic-based Spectral Indicator for Bearing Fault Detection in Permanent-Magnet Synchronous Machines using the Stator Current

    OpenAIRE

    Picot, Antoine; Obeid, Ziad; Régnier, Jérémi; Poignant, Sylvain; Darnis, Olivier; Maussion, Pascal

    2014-01-01

    International audience; In this paper, an original method for bearing fault detection in high speed synchronous machines is presented. This method is based on the statistical process of Welch's periodogram of the stator currents in order to obtain stable and normalized fault indicators. The principle of the method is to statistically compare the current spectrum to a healthy reference so as to quantify the changes over the time. A statistic-based indicator is then constructed by monitoring sp...

  8. Controlled drug release from lung-targeted nanocarriers via chemically mediated shell permeabilisation.

    Science.gov (United States)

    Chen, Hanpeng; Woods, Arcadia; Forbes, Ben; Jones, Stuart

    2016-09-25

    Nanocarriers can aid therapeutic agent administration to the lung, but controlling drug delivery from these systems after deposition in the airways can be problematic. The aim of this study was to evaluate if chemically mediated shell permeabilisation could help manipulate the rate and extent of nanocarrier drug release. Rifampicin was loaded into lipid shell (loading efficiency 41.0±11.4%, size 50nm) and polymer shell nanocarriers (loading efficiency 25.9±2.3%, size 250nm). The drug release at pH 7.4 (lung epithelial pH) and 4.2 (macrophage endosomal pH) with and without the chemical permeabilisers (Pluronic L62D - lipid nanocarriers; H(+)- polymer nanocarriers) was then tested. At pH 7.4 the presence of the permeabilisers increased nanocarrier drug release rate (from 3.2μg/h to 6.8μg/h for lipid shell nanocarriers, 2.3μg/h to 3.4μg/h for polymer shell nanocarriers) and drug release extent (from 50% to 80% for lipid shell nanocarriers, from 45% to 76% for polymer shell nanocarriers). These effects were accompanied by lipid nanocarrier distension (from 50 to 240nm) and polymer shell hydrolysis. At pH 4.2 the polymer nanocarriers did not respond to the permeabiliser, but the lipid nanocarrier maintained a robust drug release enhancement response and hence they demonstrated that the manipulation of controlled drug release from lung-targeted nanocarriers was possible through chemically mediated shell permeabilisation.

  9. Stealth Properties to Improve Therapeutic Efficacy of Drug Nanocarriers

    Directory of Open Access Journals (Sweden)

    Stefano Salmaso

    2013-01-01

    Full Text Available Over the last few decades, nanocarriers for drug delivery have emerged as powerful tools with unquestionable potential to improve the therapeutic efficacy of anticancer drugs. Many colloidal drug delivery systems are underdevelopment to ameliorate the site specificity of drug action and reduce the systemic side effects. By virtue of their small size they can be injected intravenously and disposed into the target tissues where they release the drug. Nanocarriers interact massively with the surrounding environment, namely, endothelium vessels as well as cells and blood proteins. Consequently, they are rapidly removed from the circulation mostly by the mononuclear phagocyte system. In order to endow nanosystems with long circulation properties, new technologies aimed at the surface modification of their physicochemical features have been developed. In particular, stealth nanocarriers can be obtained by polymeric coating. In this paper, the basic concept underlining the “stealth” properties of drug nanocarriers, the parameters influencing the polymer coating performance in terms of opsonins/macrophages interaction with the colloid surface, the most commonly used materials for the coating process and the outcomes of this peculiar procedure are thoroughly discussed.

  10. Analysis on Stiffness of Permanent Magnetic Bearing%轴向磁化永磁轴承的刚度特性分析

    Institute of Scientific and Technical Information of China (English)

    张钢; 殷庆振; 阮娟; 蒋德得; 高刚

    2011-01-01

    利用永磁体等效电流模型,以轴向磁化的永磁轴承为对象建立了刚度矩阵.通过无量纲化,分析了各个尺寸参数对刚度的影响规律,并绘制了相应的变化曲线图,分析结果表明:在轴向力和径向刚度分析中,当R/a>3时,磁环外径作为弱影响参数可以被省略;在倾斜刚度和耦合刚度分析中,外径的影响规律不能被忽略;当磁环的高度和厚度相等时,永磁轴承性能最优.%By using the equivalent electricity model and taking the permanent magnetic bearing in axial magnetizing as the object, the stiffness matrix has been built. Through the dimensionless method, the analysis of the law about the impact of various size parameters on the stiffness has been done and the corresponding graphs have been drawn. The results show that in the analysis of the axial and radial stiffness, when R/a > 3, the ring diameter as a weak effect parameter can be omitted; when analyzing tilt stiffness and coupling stiffness, the influencing law of the diameter can not be ignored; When the height and thickness of the ring are equal, the permanent magnet bearing has the optimum function.

  11. Journal bearing

    Science.gov (United States)

    Menke, John R.; Boeker, Gilbert F.

    1976-05-11

    1. An improved journal bearing comprising in combination a non-rotatable cylindrical bearing member having a first bearing surface, a rotatable cylindrical bearing member having a confronting second bearing surface having a plurality of bearing elements, a source of lubricant adjacent said bearing elements for supplying lubricant thereto, each bearing element consisting of a pair of elongated relatively shallowly depressed surfaces lying in a cylindrical surface co-axial with the non-depressed surface and diverging from one another in the direction of rotation and obliquely arranged with respect to the axis of rotation of said rotatable member to cause a flow of lubricant longitudinally along said depressed surfaces from their distal ends toward their proximal ends as said bearing members are rotated relative to one another, each depressed surface subtending a radial angle of less than 360.degree., and means for rotating said rotatable bearing member to cause the lubricant to flow across and along said depressed surfaces, the flow of lubricant being impeded by the non-depressed portions of said second bearing surface to cause an increase in the lubricant pressure.

  12. Novel magnetic nanoparticles coated by benzene- and β-cyclodextrin-bearing dextran, and the sorption of polycyclic aromatic hydrocarbon.

    Science.gov (United States)

    Cho, Eunae; Tahir, Muhammad Nazir; Choi, Jae Min; Kim, Hwanhee; Yu, Jae-Hyuk; Jung, Seunho

    2015-11-20

    We present the synthesis of novel magnetic nanoparticles functionalized by benzene- and β-cyclodextrin-derivatized dextran. The grafting strategy was based on the [alkynyl-iron] cluster in the modified dextrans, which were prepared by click reaction from alkyne-modified dextran and benzyl azide or mono-6-O-deoxy-monoazido β-cyclodextrin. Characterization was then carried out by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and vibrating sample magnetometry. Using the developed magnetic nanoparticles, the potential for removing polycyclic aromatic hydrocarbons such as phenanthrene and pyrene by sorption onto the nanomaterials was assessed. In the sorption, pi-stacking interactions of the benzene-derivatized dextran and host-guest chemistry of the β-cyclodextrin-derivatized dextran were considered to be significant. Furthermore, the polysaccharide derivative-coated magnetic adsorbents could be recovered by an external magnet for reuse. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. 磁悬浮飞轮储能系统机电耦合动力学特性研究%Investigation on the Dynamics Character of Electromechanical Coupling for Flywheel Energy Storage System Based on Active Magnetic Bearing

    Institute of Scientific and Technical Information of China (English)

    陈峻峰; 刘昆; 肖凯; 王昊泽

    2012-01-01

    根据永磁电机结构,采用解析法分析了转子偏心时气隙磁感强度分布,推导出了储能飞轮系统充放电时受到的不平衡磁吸力和洛伦兹力表达式。构建了电机-磁轴承机电耦合动力学仿真模型,分析了电机产生的不平衡力与磁悬浮飞轮动力学性能的耦合影响。在不平衡力分析基础上,设计了磁轴承系统,抑制了机电耦合的影响。研究结果表明:当系统的电机尺寸较大且应用于高能放电领域时,转子偏心引起电机产生不平衡力较大,飞轮动力学性能变化显著,合理设计磁轴承可以抑制机电耦合。%The coupling between the generator and active magnetic bearing affects the stable operation of flywheel system in flywheel energy storage system based on active magnetic bearing,and restricts the control system design of active magnetic bearing.According to the structure of the generator,an analytical method is adopted to analyse the magnetic flux density distribution in the airgap region considering the rotor eccentricity,and the expressions of the unbalanced magnetic force and the unbalanced Lorentz force are educed when the flywheel energy storage system is charged or discharged.The dynamics simulation model of electromechanical coupling between the generator and active magnetic bearing is established,and the coupling effects between the unbalanced force brought by generator and the flywheel dynamics performance based on active magnetic bearing are analysed.Based on the analysis,an active magnetic bearing system is designed to restrain the electromechanical coupling.The results indicate that when the generator has a big size and the system is used in high electric-power field,the unbalanced force brought by rotor eccentricity in the generator is large,and have obvious impact on the performance of flywheel dynamics.The active magnetic bearing system can be reasonably designed to restrain the electromechanical coupling.

  14. 计及边缘效应的交流混合磁轴承建模%Modeling for AC Hybrid Magnetic Bearings Considering Edge Effect

    Institute of Scientific and Technical Information of China (English)

    朱熀秋; 丁书玲

    2016-01-01

    在混合磁轴承(hybrid magnetic bearing,HMB)建模过程中,通常忽略涡流效应、边缘效应和漏磁等因素,使得悬浮力数学模型精度降低。为了提高模型精度,提出了计及磁极端部边缘效应的混合磁轴承改进模型。该文以交流径向混合磁轴承为例分析其工作原理和磁通分布特性,采用磁场分割法分别求解不同边缘磁通区域的磁导,通过叠加原则获得单个磁极下的总磁导,根据等效磁路法建立径向悬浮力的精确数学模型。实验结果表明:改进前模型计算所得悬浮力与实验所得悬浮力误差接近10%,改进后的数学模型所得悬浮力与实验所得悬浮力误差小于5%。比较结果证明了计及边缘效应能有效提高悬浮力数学模型的精度。%In modeling proceeding of hybrid magnetic bearings (HMBs), factors such as the eddy current effect, the edge effect and the flux leakage are commonly ignored, which decreases the precision of the mathematical model of suspension forces. In order to improve the precision, an improved mathematical model of hybrid magnetic bearings considering the edge effect was established. An AC hybrid magnetic bearing was taken as an example, its working principle and features of flux distribution were analyzed. Then, the magnetic field division method was employed to calculate the permeances of different regions located around the end portion of the pole. The permeances were added by the superposition principle, and the total permeance of the single pole was obtained. The accurate model was obtained by using the equivalent magnetic circuit method. The experimental results show that the error between original model values and experimental values is about 10%, the error between improved model values and experimental values is less than 5%. The results of the comparison have verified that the consideration of the edge effect can effectively improve the precision of the mathematical model

  15. Rotor dynamic behaviour of a high-speed oil-free motor compressor with a rigid coupling supported on four radial magnetic bearings

    Science.gov (United States)

    Schmied, J.; Pradetto, J. C.

    1994-01-01

    The combination of a high-speed motor, dry gas seals, and magnetic bearings realized in this unit facilitates the elimination of oil. The motor is coupled with a quill shaft to the compressor. This yields higher natural frequencies of the rotor than with the use of a diaphragm coupling and helps to maintain a sufficient margin of the maximum speed to the frequency of the second compressor bending mode. However, the controller of each bearing then has to take the combined modes of both machines into account. The requirements for the controller to ensure stability and sufficient damping of all critical speeds are designed and compared with the implemented controller. The calculated closed loop behavior was confirmed experimentally, except the stability of some higher modes due to slight frequency deviations of the rotor model to the actual rotor. The influence of a mechanical damper as a device to provide additional damping to high models is demonstrated theoretically. After all, it was not necessary to install the damper, since all modes cold be stabilized by the controller.

  16. Superconducting bearings for flywheel applications

    DEFF Research Database (Denmark)

    Abrahamsen, A.B.

    2001-01-01

    A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings...

  17. 高温超导磁悬浮轴承研发现状%Research and Development Status of High Temperature Superconducting Magnetic Bearings

    Institute of Scientific and Technical Information of China (English)

    邓自刚; 王家素; 王素玉; 郑珺; 林群煦; 张娅

    2009-01-01

    As one of the most representative applications of self-stable high temperature superconducting magnetic levitation technology, high temperature superconducting magnetic bearing (SMB) can realize passive high-speed rotation without any friction, which provides a new way to markedly improve and upgrade the performance of present machinery and equipment with common bearings. In order to summarize the research and development status of SMB, the typical prototypes are described respectively from America, Germany, Japan and Korea, as well as other domestic and foreign groups. The key technical issues and present hotspot are pointed out and discussed to explain the future development and potential prospect.%高温超导磁悬浮轴承作为具有自稳定优势的高温超导磁悬浮技术最具代表性的应用之一,可实现无源的高速无摩擦旋转运行,为大幅度提高现有机器设备的性能及升级换代提供了新的途径.本文综述了近年来美国、德国、日本和韩国等国内外小组开展的高温超导磁悬浮轴承代表性样机研发现状,探讨了该项技术的关键难点问题,指出了当前研究的热点,阐述了可能的应用前景.

  18. Grizzly bear

    Science.gov (United States)

    Schwartz, C.C.; Miller, S.D.; Haroldson, M.A.; Feldhamer, G.; Thompson, B.; Chapman, J.

    2003-01-01

    The grizzly bear inspires fear, awe, and respect in humans to a degree unmatched by any other North American wild mammal. Like other bear species, it can inflict serious injury and death on humans and sometimes does. Unlike the polar bear (Ursus maritimus) of the sparsely inhabited northern arctic, however, grizzly bears still live in areas visited by crowds of people, where presence of the grizzly remains physically real and emotionally dominant. A hike in the wilderness that includes grizzly bears is different from a stroll in a forest from which grizzly bears have been purged; nighttime conversations around the campfire and dreams in the tent reflect the presence of the great bear. Contributing to the aura of the grizzly bear is the mixture of myth and reality about its ferocity. unpredictable disposition, large size, strength, huge canines, long claws, keen senses, swiftness, and playfulness. They share characteristics with humans such as generalist life history strategies. extended periods of maternal care, and omnivorous diets. These factors capture the human imagination in ways distinct from other North American mammals. Precontact Native American legends reflected the same fascination with the grizzly bear as modern stories and legends (Rockwell 1991).

  19. 基于磁路分析的轴向混合磁轴承径向承载力解析计算%Calculation of Radial Electromagnetic Force of Axial Hybrid Magnetic Bearing Based on Magnetic Circuit Analysis

    Institute of Scientific and Technical Information of China (English)

    张云鹏; 刘淑琴; 李红伟; 范友鹏

    2012-01-01

    研究轴向混合磁轴承实现五自由度悬浮时,需要计算径向承载力与磁轴承结构参数以及永磁体参数之间的关系。为了解决轴向混合磁轴承缺乏径向承载力解析数学模型的问题,该文在分析轴向混合磁轴承磁路以及各部分磁导的基础上,结合稀土永磁体的工作特性,用虚位移法得出了轴向混合磁轴承的径向承载力解析数学模型。模型表明,在小径向位移时,该型的混合磁轴承径向承载力随着径向位移增加而增加,近似线性关系,径向承载力和刚度随轴向气隙增大而减小;磁轴承径向承载力随永磁体的有效长度增加呈现先增大后趋近饱和。利用有限元方法对径向承载力进行仿真计算,仿真结果与模型计算结果基本吻合。%In studying axial hybrid magnetic bearing (HMB) for suspension in five degree of freedom (DOF), the relationship between radial electromagnetic force and magnetic bearing structural parameters and permanent magnet parameters should be calculated. In order to overcome the lack of analytical calculation model for radial electromagnet force of axial HMB, based on magnetic circuit analysis and calculation of magnetic conductance for each parts, the analytical calculation model for radial electromagnet force of axial HMB is proposed in this paper. The analytical formulation of radial electromagnetic force is derived by using virtual displacement method and demagnetization characteristics of the rare earth permanent magnet. It is found that the radial electromagnetic force increases with the radial displacement increasing approximately in linear relationship, and the radial force and stiffness decreases with the axial gap increasing. The radial electromagnetic force increased and then saturated with increasing permanent magnet effective length. The model of axial HMB is simulated by finite-element method software and the simulation results are basically in

  20. Immobilized Pd on magnetic nanoparticles bearing proline as a highly efficient and retrievable Suzuki-Miyaura catalyst in aqueous media.

    Science.gov (United States)

    Nehlig, E; Waggeh, B; Millot, N; Lalatonne, Y; Motte, L; Guénin, E

    2015-01-14

    A magnetically retrievable nanocatalyst was evaluated for a microwave assisted Suzuki-Miyaura reaction in aqueous media. Excellent yields and conversions were obtained with low Pd loadings (down to 0.01 mol% Pd). It was stable up to 6 months in water under aerobic conditions and efficiency remained unaltered even after 7 repeated cycles.

  1. Design requirements to magnetic bearings for primary circuit blowers of high-temperature reactors. Final report; Auslegungsanforderungen an Magnetlager fuer Primaerkuehlgasgeblaese von Hochtemperaturreaktoren. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-12

    To study the operational behaviour of blower shafts with magnetic bearings, a modular computer model was set up based on model laws, which permits to simulate shaft behaviour during dynamic loads acting on the blower shaft. During simulation runs, essential properties of position regulation (guide behaviour, secondary behaviour, and fault behaviour), and the behaviour of the blower shaft in the event of failure of a final stage of magnetic bearing electronics, with not-single-failure-proof and with failure-tolerant design of the final stages, as well as the effects of mechanical vibrations, e.g. as a result of earthquakes, on the behaviour of blower shafts were investigated. In order to transfer the results of the catch bearing tests to other designs of blowers with a vertical blower shaft, transmission laws and procedures were derived from theoretical considerations and from a dimension analysis which, however, could not be verified by means of tests. Application of the test results to horizontally placed blower shafts is possible only in part. The computer simulation model set up for the behaviour of the blower shafts is applicable without significant limitations to other blower shaft arrangements. (orig.). [Deutsch] Zur Untersuchung des Betriebsverhaltens magnetisch gelagerter Geblaesewellen wurde anhand von Modellgesetzen ein modulares Rechenmodell aufgebaut, das die Simulation des Wellenverhaltens bei auf die Geblaesewelle wirkenden dynamischen Belastungen erlaubt. In Simulationslaeufen wurden wesentliche Eigenschaften der Lageregelung (Fuehrungsverhalten, Folgeverhalten und Stoerungsverhalten) und das Verhalten der Geblaesewellen bei Ausfall einer Endstufe der Magnetlagerelektronik bei nicht einzelfehlersicherer und bei fehlertoleranter Ausfuehrung der Endstufen sowie die Auswirkungen mechanischer Erschuetterungen z.B. infolge von Erdbeben auf das Verhalten der Geblaesewelle untersucht. Zur Uebertragung der Ergebnisse der Fanglagerversuche auf andere

  2. Reversibly PEGylated nanocarrier for cisplatin delivery.

    Science.gov (United States)

    Stoyanova, Ekaterina; Mitova, Violeta; Shestakova, Pavletta; Kowalczuk, Agnieszka; Momekov, Georgi; Momekova, Denitsa; Marcinkowski, Andrzej; Koseva, Neli

    2013-03-01

    A star-shaped copolymer bearing a shell of poly(ethylene glycol) (PEG) chains was designed as a carrier of cisplatin. The proposed strategy was based on synthesis of a PEGylating agent and the incorporation of cisplatin as a reversible linker for PEG modification of the star macromolecules. The attachment of PEG chains to the stars and their release under physiological conditions, as well as the changes in particle size and mobility upon drug loading, was evidenced by diffusion ordered NMR spectroscopy (DOSY). The results demonstrated that PEGylation reduced inter-stars cross-linking and increased the stability of the nanocolloidal solution. The formation of PEG shell resulted in higher drug payload and improved drug release profile of the nanoconjugates. The in vitro bioassay in a panel of human tumor cell lines confirmed that the PEGylated conjugates exhibited superior growth inhibitory activity compared to the cisplatin-loaded nonPEGylated carrier.

  3. 磁悬浮轴承技术在风机与泵类设备中的应用现状%Application Status of Magnetic Bearings in Fan and Pump Equipments

    Institute of Scientific and Technical Information of China (English)

    汤士明; 梅磊; 欧阳慧珉

    2013-01-01

    阐述了磁悬浮轴承的基本原理与优点,详细比较了与磁悬浮轴承技术相关的国内外最新研究动态,并研究了其在风机和泵类设备中的应用现状,最后通过分析磁悬浮轴承在空调应用中的技术性和经济性问题得出了其在空调风机、压缩机等设备上具有良好的市场应用前景的结论.%The basic principles of magnetic bearings and its advantages were explained.Its related new developments in home and board were compared in details,and the application status of magnetic bearings in fan and pump equipments was researched.The conclusion that magnetic bearings have a good prospect in air conditioning fans and compressors was gotten through the analysis of technical and economic problems of magnetic bearings application in air conditioning.

  4. Recent Trends in Multifunctional Liposomal Nanocarriers for Enhanced Tumor Targeting

    Directory of Open Access Journals (Sweden)

    Federico Perche

    2013-01-01

    Full Text Available Liposomes are delivery systems that have been used to formulate a vast variety of therapeutic and imaging agents for the past several decades. They have significant advantages over their free forms in terms of pharmacokinetics, sensitivity for cancer diagnosis and therapeutic efficacy. The multifactorial nature of cancer and the complex physiology of the tumor microenvironment require the development of multifunctional nanocarriers. Multifunctional liposomal nanocarriers should combine long blood circulation to improve pharmacokinetics of the loaded agent and selective distribution to the tumor lesion relative to healthy tissues, remote-controlled or tumor stimuli-sensitive extravasation from blood at the tumor’s vicinity, internalization motifs to move from tumor bounds and/or tumor intercellular space to the cytoplasm of cancer cells for effective tumor cell killing. This review will focus on current strategies used for cancer detection and therapy using liposomes with special attention to combination therapies.

  5. Nanocarriers and nanoparticles for skin care and dermatological treatments

    Directory of Open Access Journals (Sweden)

    Sanjeev Gupta

    2013-01-01

    Full Text Available Nanotechnology (nano: One billionth is a novel arena with promising applications in the field of medicine, especially pharmaceuticals for safe and targeted drug delivery. The skin is a phenomenal tool for investigation of nanocarriers for drug delivery for topical and dermatological application. The physicochemical characteristics of the nanoparticles, such as rigidity, hydrophobicity, size and charge are crucial to the skin permeation mechanism. Many nanocarriers such as polymeric, inorganic and lipid nanoparticles and nanoemulsions have been developed and some like carbon nanotubes and fullerenes still need further exploration for future use in skin care and dermatological treatments. Risks of nanopollution and cytotoxicity also need to be kept in mind while exploring various nanoparticles for medical use.

  6. Exosomes as nanocarriers for immunotherapy of cancer and inflammatory diseases.

    Science.gov (United States)

    Tran, Thanh-Huyen; Mattheolabakis, George; Aldawsari, Hibah; Amiji, Mansoor

    2015-09-01

    Cell secreted exosomes (30-100nm vesicles) play a major role in intercellular communication due to their ability to transfer proteins and nucleic acids from one cell to another. Depending on the originating cell type and the cargo, exosomes can have immunosuppressive or immunostimulatory effects, which have potential application as immunotherapies for cancer and autoimmune diseases. Cellular components shed from tumor cells or antigen presenting cells (APCs), such as dendritic cells, macrophages and B cells, have been shown to be efficiently packaged in exosomes. In this review, we focus on the application of exosomes as nanocarriers and immunological agents for cancer and autoimmune immunotherapy. APC-derived exosomes demonstrate effective therapeutic efficacy for the treatment of cancer and experimental autoimmune diseases such as rheumatoid arthritis, inflammatory bowel disease, and multiple sclerosis. In addition to their intrinsic immunomodulating activity, exosomes have many advantages over conventional nanocarriers for drug and gene delivery.

  7. Cancer Therapy Based on Nanomaterials and Nanocarrier Systems

    Directory of Open Access Journals (Sweden)

    Weili Qiao

    2010-01-01

    Full Text Available Targeted delivery of drug molecules to tumor tissue is one of the most interesting and challenging endeavors faced in pharmaceutical field, due to the critical and pharmacokinetically specific environment that exists in tumor. Over these years, cancer targeting treatment has been greatly improved by new tools and approaches based on nanotechnology. The review firstly introduces the specific physical and chemical properties of a serial of nanomaterials, such as nanoparticles, micelles, dendrimers, carbon nanotubes, quantum dots, and nanofibers. It then places great emphasis on their application in the field of cancer therapy when they are used as nanocarrier systems. Based on the current status, the paper further discusses the unsolved problems and makes a perspective for the future prospects of the nanocarrier systems.

  8. Smart conjugated polymer nanocarrier for healthy weight loss by negative feedback regulation of lipase activity

    Science.gov (United States)

    Chen, Yu-Lei; Zhu, Sha; Zhang, Lei; Feng, Pei-Jian; Yao, Xi-Kuang; Qian, Cheng-Gen; Zhang, Can; Jiang, Xi-Qun; Shen, Qun-Dong

    2016-02-01

    Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution.Healthy weight loss represents a real challenge when obesity is increasing in prevalence. Herein, we report a conjugated polymer nanocarrier for smart deactivation of lipase and thus balancing calorie intake. After oral administration, the nanocarrier is sensitive to lipase in the digestive tract and releases orlistat, which deactivates the enzyme and inhibits fat digestion. It also creates negative feedback to control the release of itself. The nanocarrier smartly regulates activity of the lipase cyclically varied between high and low levels. In spite of high fat diet intervention, obese mice receiving a single dose of the nanocarrier lose weight over eight days, whereas a control group continues the tendency to gain weight. Daily intragastric administration of the nanocarrier leads to lower weight of livers or fat pads, smaller adipocyte size, and lower total cholesterol level than that of the control group. Near-infrared fluorescence of the nanocarrier reveals its biodistribution

  9. Polyester-Based, Biodegradable Core-Multishell Nanocarriers for the Transport of Hydrophobic Drugs

    Directory of Open Access Journals (Sweden)

    Karolina A. Walker

    2016-05-01

    Full Text Available A water-soluble, core-multishell (CMS nanocarrier based on a new hyperbranched polyester core building block was synthesized and characterized towards drug transport and degradation of the nanocarrier. The hydrophobic drug dexamethasone was encapsulated and the enzyme-mediated biodegradability was investigated by NMR spectroscopy. The new CMS nanocarrier can transport one molecule of dexamethasone and degrades within five days at a skin temperature of 32 °C to biocompatible fragments.

  10. Lipid nanocarriers: influence of lipids on product development and pharmacokinetics.

    Science.gov (United States)

    Pathak, Kamla; Keshri, Lav; Shah, Mayank

    2011-01-01

    Lipid nanocarriers are on the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery. Owing to their size-dependent properties, lipid nanoparticles offer the possibility for development of new therapeutics and an alternative system to other colloidal counterparts for drug administration. An important point to be considered in the selection of a lipid for the carrier system is its effect on the properties of the nanocarrier and also its intended use, as different types of lipids differ in their nature. Researchers around the globe have tapped the potential of solid lipid nanoparticles (SLNs) in developing formulation(s) that can be administered by various routes such as oral, ocular, parenteral, topical, and pulmonary. Since the start of this millennium, a new generation of lipid nanoparticles, namely nanostructured lipid carriers (NLCs), lipid drug conjugates (LDCs), and pharmacosomes, has evolved that have the potential to overcome the limitations of SLNs. The current review article presents broad considerations on the influence of various types of lipids on the diverse characteristics of nanocarriers, encompassing their physicochemical, formulation, pharmacokinetic, and cytotoxic aspects.

  11. Use of a ring-shaped, passively stable, superconducting magnetic bearing in the ring spinning process; Einsatz eines ringfoermigen, passiv stabilen, supraleitenden Magnetlagers im Ringspinnprozess

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Anne; Sparing, Maria; Berger, Dietmar; Fuchs, Guenter; Schultz, Ludwig [IFW Dresden (Germany). Inst. fuer Metallische Werkstoffe; Hossain, Mahmud; Abdkader, Anwar; Cherif, Chokri [TU Dresden (Germany). ITM

    2015-07-01

    For the integration of a superconducting magnetic bearing in a ring spinning machine a LN{sub 2} continuous flow cryostat was developed, which is needed to cool the superconductor below its transition temperature of ∝91 K and simultaneously ensures that the spinning process takes place at room temperature. The ring spinning process is the most widely used process for spinning yarn. In this case, a loose fiber connection is first stretched in a roller system, then twisted by the so-called spinning ring-ring traveler system, and finally wound on a spindle. The spinning ring is a circular guide, which is mounted around the spindle. On this the ring traveler rotates as yarn guide. The yarn is driven by the rotation of the spindle and there is a balloon-shaped movement of the yarn which results the twist. The productivity of the process is limited by the systematic frictional heat between the yarn, spinning ring and ring travelers. This leads at high speeds to yarn breakage and limits the maximum spindle speed depending on the type of fiber to a maximum of 25,000 U/min. To increase the speed and thus the productivity of the process, the conventional spinning ring-ring rotor system is replaced by a superconducting magnetic bearing. Here floats a NdFeB permanent magnet passively stable over the LN{sub 2} cooled ceramic high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7-x}. Driven by the yarn the permanent magnet rotates, thus ensuring the necessary balloon-shaped yarn movement to twist. Such a bearing has been successfully tested in a ring spinning machine. Preliminary results show a similar yarn quality. [German] Fuer die Integration eines supraleitenden Magnetlagers in eine Ringspinnmaschine wurde ein LN{sub 2}-Durchflusskryostat entwickelt, der noetig ist, um den Supraleiter unter seine Sprungtemperatur von ∝91 K zu kuehlen und gleichzeitig dafuer sorgt, dass der Spinnprozess bei Raumtemperatur ablaeuft. Der Ringspinnprozess ist der am weitesten verbreitete

  12. Hydrophobic nano-carrier for lysozyme adsorption

    Indian Academy of Sciences (India)

    CANAN ALTUNBAS; FULDEN ZEYNEP URAL; MURAT UYGUN; NESIBE AVCIBASI; UGUR AVCIBASI; DENIZ AKTAS UYGUN; SINAN AKGÖL

    2016-04-01

    In this work, poly(HEMA–APH) nanoparticles were synthesized by surfactant-free emulsion polymerization technique.Magnetic behaviour was introduced by simple addition of Fe$_3$O$_4$ into the polymerization medium.Characterization of the nanoparticle was carried out by FTIR, ESR, SEM, AFM and EDX analyses. These synthesized magnetic nanoparticles were used for adsorption of lysozyme. For this purpose, adsorption conditions wereoptimized and maximum lysozyme binding capacity was found to be 278.8 mg g$^{−1}$ polymer in pH 7.0 phosphate buffer at 25$^{\\circ}$C. Desorption and reusability properties of the nanoparticles were investigated and lysozyme adsorption efficiency did not change significantly at the end of the 10 successive reuses.

  13. 风力发电机用同极型磁悬浮轴承的支承性能%Supporting characteristics of the homopolar active magnetic bearing for wind power generator

    Institute of Scientific and Technical Information of China (English)

    谢振宇; 王晓; 周红凯

    2013-01-01

    The setup of vertical axis wind power generator rotor system is built. The homopolar radial active magnetic bearing and the axial active magnetic bearing with the function of suspension and brake synchronously are designed and manufactured. The main design process and configuration parameters are presented. Stability ranges of the control parameters of the active magnetic bearings are tested, the mode frequencies and modal damps of the system are obtained by experimental modal analysis, and the brake function of the axial active magnetic bearing is verified. The results show that the first critical speed of the system is far above the operating rotation speed, there is no resonance when the system is in motion. On the other hand, the axial active magnetic bearing can meet the brake demand and reduce the size and cost of the system.%建立了垂直轴风力发电机转子系统装置,设计制作了同极型径向磁悬浮轴承和具有悬浮与刹车功能的轴向磁悬浮轴承,给出了该装置的主要设计过程和结构参数.测试了磁悬浮轴承控制参数的稳定区域,采用试验模态分析方法获取了系统的模态频率和模态阻尼,并验证了轴向磁悬浮轴承的刹车功能.结果表明,系统的第一阶临界转速远高于最大工作转速,系统在运行时不会出现共振;另外,轴向磁悬浮轴承可以满足刹车制动要求,有利于减小系统的体积和成本.

  14. Superconductor bearings, flywheels and transportation

    Science.gov (United States)

    Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

    2012-01-01

    This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

  15. Preparation of myeloid derived suppressor cells (MDSC) from naive and pancreatic tumor-bearing mice using flow cytometry and automated magnetic activated cell sorting (AutoMACS).

    Science.gov (United States)

    Nelson, Nadine; Szekeres, Karoly; Cooper, Denise; Ghansah, Tomar

    2012-06-18

    sieve. Splenocytes are then Red Blood Cell (RBC) lysed and an aliquot of these leukocytes are stained using fluorochrome-conjugated antibodies against Mac-1 and Gr-1 to immunophenotype MDSC percentages using Flow Cytometry. In a parallel experiment, whole leukocytes from naïve mice are stained with fluorescent-conjugated Gr-1 antibodies, incubated with PE-MicroBeads and positively selected using an automated Magnetic Activated Cell Sorting (autoMACS) Pro Separator. Next, an aliquot of Gr-1(+) leukocytes are stained with Mac-1 antibodies to identify the increase in MDSC percentages using Flow Cytometry. Now, these Gr1(+) enriched leukocytes are ready for FACS sorting of MDSC to be used in comparative analyses (naïve vs. tumor- bearing) in in vivo and in vitro assays.

  16. Using annexin V-coated magnetic beads to capture active tissue factor-bearing microparticles from body fluids.

    Science.gov (United States)

    Gieseler, Frank; Gamperl, Hans; Theophil, Frederike; Stenzel, Inga; Quecke, Tabea; Ungefroren, Hendrik; Lehnert, Hendrik

    2014-02-01

    Microparticles, found in all body fluids including peripheral blood, are important elements that regulate cellular interactions under both physiological and pathological conditions. They play an important role in blood clot formation and increased cell aggregation. However, little is known about the components of the microparticles and their mechanism of action. A method to quantify and assess the underlying mechanism of action of microparticles in pathologies is therefore desirable. We present a specific method to isolate cell-derived microparticles from malignant effusions using annexin V-coated magnetic microbeads. The microparticles can be detected by flow cytometry. Our results show that the microparticles can be isolated with >80% specificity when bound to annexin V-coated magnetic beads, which was originally developed for the detection of apoptotic cells. We also show that the isolated microparticles were still functionally active and can be used for further analysis. Thus, our method enables isolation as well as structural and functional characterisation of the microparticles which are produced in numerous patho-physiological situations. This should help gain a deeper insight into various disease situations, which in turn should pave the way for the development of novel drugs and specific therapy strategies. © 2013 International Federation for Cell Biology.

  17. Dynamic measurement of patello-femoral joint alignment using weight-bearing magnetic resonance imaging (WB-MRI).

    Science.gov (United States)

    Mariani, Silvia; La Marra, Alice; Arrigoni, Francesco; Necozione, Stefano; Splendiani, Alessandra; Di Cesare, Ernesto; Barile, Antonio; Masciocchi, Carlo

    2015-12-01

    Aim of our work was to compare standard and weight-bearing WB-MRI to define their contribution in unmasking patello-femoral (PF) maltracking and to define what measurement of patellar alignment is the most reliable. We prospectively collected 95 non consecutive patients, clinically divided into 2 groups: group A (the control group), including 20 patients (negative for patellar maltracking), and group B including 75 patients (positive for patellar maltracking). The patients underwent a dedicated 0.25 T MRI, in supine and WB position, with knee flexion of 12-15°. The following measurements were performed: Insall-Salvati index (IS), lateral patellar displacement (LPD), lateral patello-femoral angle (LPA) and lateral patellar tilt (LPT). Quantitative and qualitative statistical analyses were performed to compare the results obtained before and after WB-MRI. Measurements were subsequently performed on both groups. Group A patients showed no statistically significant variations at all measurements both on standard and WB-MRI. On the basis of measurements made on standard MRI, group B patients were divided into group B1 (23 patients) (negative or positive at 1 measurement) and group B2 (52 patients) (positive at 2 or more measurements). After WB-MRI, group B1 patients were divided into group B1a (6 patients), in case they remained positive at 0/1 measurement, and group B1b (17 patients), in case they became positive at 2 or more measurements. All group B2 patients confirmed to be positive at 2 or more measurements at WB-MRI. Quantitative statistical analysis showed that LPT and LPA were the most reproducible and clinically useful measurements. Qualitative statistical analysis performed on standard and WB-MRI demonstrated that LPT was the best predictive measurement. This study demonstrates both the high diagnostic value of WB-MRI in unmasking PF-maltracking and the best predictive value of LPT measurement. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. 磁悬浮飞轮用可重复抱式锁紧装置%Repeated clamping locking device for magnetic bearing flywheel

    Institute of Scientific and Technical Information of China (English)

    刘强; 房建成

    2012-01-01

    As the integral carbon fiber slice for a locking device is not easy to disassemble and the one-off locking device can not repeat locking/unlocking in a magnetic bearing flywheel, a novel repeated clamping locking device based on a separate elastic slice as release mechanism was presented. The composition,, operating principles and the scheme of elastic slice for the device were introduced. To be equivalent the elastic slice for a cantilever beam-mass mode, the static and dynamic analysis was performed for the device. Upon this, the structure parameters of high sensitivity were selected as design variables, and the structural strength, unlocking force and the first resonance frequency were concerned. Then, the software of multidisciplinary design optimization (iSIGHT) was used for the optimization of elastic slice. The results indicate that the total mass of elastic slices has been reached to the minimum of 207 g corresponding to 10 elastic slices, which is reduced by 56. 6% compared with initial mass of 477 g. According to optimization results, a locking device was manufactured and it isverified by sine-swept vibration and random vibration. The verification shows that the locking device can protect magnetic bearing flywheels and has great significance and values for space applications of magnetic bearing flywheels.%针对磁悬浮飞轮锁紧装置用整体碳纤维弹片不便拆卸和一次性锁紧装置不可重复锁紧/解锁的缺点,提出了一种基于分立式弹片释放机构的可重复抱式锁紧装置.介绍了锁紧装置的结构、工作原理和弹片方案,通过将弹片释放机构等效为悬臂梁质量块模型,对其进行了静力学和动力学分析.基于分析结果,选择灵敏度较高的结构参数作为优化设计变量,并考虑结构强度、解锁力和一阶共振频率,以软件iSIGHT为平台,对弹片进行多学科优化设计.优化结果表明,弹片个数为10时,弹片总质量达到最小为207 g

  19. Magnetic, structural and geochronologic evidence bearing on volcanic sources and Oligocene Deformation of Ash Flow Tuffs, northeast Nevada

    Science.gov (United States)

    Palmer, H. C.; MacDonald, W. D.; Hayatsu, A.

    1991-02-01

    Magnetic properties of mid-Tertiary volcanic rocks west of Jiggs in northeast Nevada were investigated for the purposes of interpreting igneous, structural, and tectonic processes in this part of the Basin and Range province. Anisotropy of magnetic susceptibility (AMS) patterns reflect flow fabrics and suggest previously unknown sources for these ash flow tuffs. Paleomagnetic and structural evidence suggest counterclockwise relative rotation of the southern part of the area with respect to the north. New stratigraphic, chemical and K-Ar isotopic data support these interpretations. Dacite to rhyolite ash flow tuffs of the Indian Well Formation were subdivided into two main units: the lower and predominant tuff of Jiggs (35.8-37.0 Ma) and the unconformably overlying but areally restricted tuff of Hackwood (30.8 Ma). The Jiggs unit has two polarities whereas the Hackwood has only a reversed polarity remanence. Together these units with tilt correction define a pole (92°E, 87°N, dp = 6°, dm = 8°) for approximately 30-37 Ma. This pole is concordant with coeval North American reference poles, indicating that this zone of approximately 30 km NS extent has not undergone significant vertical axis rotation relative to the North American reference. Andesite lavas of normal magnetic polarity and of 32.5-Ma age characterize the Diamond Hills immediately to the south. We interpret this region, from both structural evidence and discordant paleomagnetic direction, to have rotated approximately 25° counterclockwise relative to the Indian Well volcanic units to the north. The apparent rotation of the Diamond Hills is possibly the result of drag on the left-lateral Garcia fault which limits the Diamond Hills on the southwest. Analysis of AMS data suggests, by patterns of the K1 axes, two distinct sources for the Jiggs unit: a northern buried source and a central partially buried source. Lithologic evidence consistent with proximal vent facies is found near the latter source. An

  20. Tumor radio-sensitivity assessment by means of volume data and magnetic resonance indices measured on prostate tumor bearing rats.

    Science.gov (United States)

    Belfatto, Antonella; White, Derek A; Mason, Ralph P; Zhang, Zhang; Stojadinovic, Strahinja; Baroni, Guido; Cerveri, Pietro

    2016-03-01

    Radiation therapy is one of the most common treatments in the fight against prostate cancer, since it is used to control the tumor (early stages), to slow its progression, and even to control pain (metastasis). Although many factors (e.g., tumor oxygenation) are known to influence treatment efficacy, radiotherapy doses and fractionation schedules are often prescribed according to the principle "one-fits-all," with little personalization. Therefore, the authors aim at predicting the outcome of radiation therapy a priori starting from morphologic and functional information to move a step forward in the treatment customization. The authors propose a two-step protocol to predict the effects of radiation therapy on individual basis. First, one macroscopic mathematical model of tumor evolution was trained on tumor volume progression, measured by caliper, of eighteen Dunning R3327-AT1 bearing rats. Nine rats inhaled 100% O2 during irradiation (oxy), while the others were allowed to breathe air. Second, a supervised learning of the weight and biases of two feedforward neural networks was performed to predict the radio-sensitivity (target) from the initial volume and oxygenation-related information (inputs) for each rat group (air and oxygen breathing). To this purpose, four MRI-based indices related to blood and tissue oxygenation were computed, namely, the variation of signal intensity ΔSI in interleaved blood oxygen level dependent and tissue oxygen level dependent (IBT) sequences as well as changes in longitudinal ΔR1 and transverse ΔR2(*) relaxation rates. An inverse correlation of the radio-sensitivity parameter, assessed by the model, was found with respect the ΔR2(*) (-0.65) for the oxy group. A further subdivision according to positive and negative values of ΔR2(*) showed a larger average radio-sensitivity for the oxy rats with ΔR2(*)<0 and a significant difference in the two distributions (p < 0.05). Finally, a leave-one-out procedure yielded a radio

  1. Axial radial magnetic bearing in magnetic suspending switched reluctance motor application%一种磁悬浮开关磁阻电机用轴向径向磁轴承

    Institute of Scientific and Technical Information of China (English)

    赵旭升; 邓智泉; 汪波

    2011-01-01

    To overcome the defects of the present permanent magnet biased axial radial magnetic bearing,a new permanent magnet biased axial radial magnetic bearing(PARMB) was studied,which was used in magnetic suspending switched reluctance motor application.The configuration and fundamental principle of PARMB were analyzed.The equivalent magnetic circuit was established to deduce the mathematical models of PARMB.The parameter design and calculation were presented.The parameters of the proposed prototype were also given.The 3-D magnetic field simulation was performed by using the finite element software.The theory analysis and the simulation show that the presented PARMB has smaller volume compared to the existed structure,here is no coupling between axial and radial directions,the control is easier than before.Therefore,the proposed PARMB is more suitable for the high speed or low loss occasions.%为了克服现有永磁偏置轴向径向磁轴承的缺陷,研究了一种新型结构的磁悬浮开关磁阻电机用永磁偏置轴向径向磁轴承.分析其结构及工作原理,利用等效磁路法进行分析,得出了轴向悬浮力及径向悬浮力的数学模型,并对数学模型进行了线性化处理,得出了其轴向、径向位移刚度和电流刚度.给出了磁极面积、控制线圈安匝数、定转子结构等主要参数的设计方法,给出了样机参数,用有限元对样机进行了三维仿真分析.理论研究和仿真分析表明:该永磁偏置轴向径向磁轴承结构紧凑,轴向控制磁通和径向控制磁通彼此解耦,控制更加容易,适用于高速、低功耗等场合.

  2. 利用场路结合方法分析磁轴承悬浮力%Levitation force analysis of magnetic bearing by circuit-field combination method

    Institute of Scientific and Technical Information of China (English)

    王大朋; 王凤翔

    2011-01-01

    针对磁轴承悬浮力分析比较复杂的问题,提出利用场路结合分析磁轴承悬浮力的方法.基于磁路法推导了径向磁轴承悬浮力的线性化模型,针对具体的磁轴承系统,利用有限元法分析了磁轴承能够满足线性化模型的偏置电流选择范围和磁轴承转子偏移范围,通过最小二乘法修正了线性化模型的电流刚度系数和位移刚度系数,并对超出线性化模型范围的悬浮力进行了分析,采用多项式拟合的方法推导了悬浮力的非线性模型.对所推导的磁轴承悬浮力模型进行了实验验证.分析及实验结果表明:由于磁饱和等因素的影响,利用磁路法推导的线性悬浮力模型已不能充分描述磁轴承悬浮力特性,通过场路结合方法推导的悬浮力模型能够更准确地计算磁轴承悬浮力.%For the analysis of magnetic force of magnetic bearings is complicated, a levitation force analysis of magnetic bearing based on field-circuit coupled method was used. Firstly, the linear expressions of magnetic levitation force was deduced based on the analysis of magnetic circuit, then the ranges of bias current and operating which can satisfy linear model were analyzed by means of the finite element analysis, through least square method the current rigidity coefficient and displacement rigidity coefficient were modified, and the nonlinear expressions of magnetic levitation force was deduced by polynomial approximation for exceeding linear model range, and finally the finite element method was verified by experiment. The analysis and experimental results show that due to the magnetic saturation and other factors, and the levitation force model which was deduced by using of the magnetic circuit method can not adequately describe the magnetic bearing levitation force characteristics, and the levitation force model which was deduced by field-circuit method can more accurately calculate magnetic bearing levitation force.

  3. Fabrication of a nanocarrier system through self-assembly of plasma protein and its tumor targeting

    Science.gov (United States)

    Gong, Guangming; Zhi, Feng; Wang, Kaikai; Tang, Xiaolei; Yuan, Ahu; Zhao, Lili; Ding, Dawei; Hu, Yiqiao

    2011-07-01

    Human serum albumin (HSA) nanoparticles hold great promise as a nanocarrier system for targeted drug delivery. The objective of this study was to explore the possibility of preparing size controllable albumin nanoparticles using the disulfide bond breaking reagent β-mercaptoethanol (β-ME). The results showed that the protein concentration and temperature had positive effects on the sizes of the albumin nanoparticles, while pH had a negative effect on the rate of nanoparticle formation. The addition of β-ME induced changes in HSA secondary structure and exposed the hydrophobic core of HSA, leading to the formation of nanoparticles. Human serum albumin nanoparticles could be internalized by MCF-7 cells and mainly accumulated in cytoplasm. After injection in tumor bearing mice, the HSA nanoparticles accumulated in tumor tissues, demonstrating the targeting ability of the nanoparticles. Therefore, human serum albumin can be fabricated into nanoparticles by breaking the disulfide bonds and these nanoparticles exhibit high tumor targeting ability. Human serum albumin nanoparticles could be ideal for the targeted delivery of pharmacologically active substances.

  4. Early-stage fault isolation based on frequency response fitted by small-size samples for cryogenic cold compressors with active magnetic bearings

    Science.gov (United States)

    Arpaia, Pasquale; De Vito, Luca; Girone, Mario; Pezzetti, Marco

    2016-01-01

    A model-based method for fault detection and early-stage isolation, applicable when unfaulty conditions can be identified only by a reduced number of trials (even only one), is presented. The basic idea is to model analytically the uncertainty of the unfaulty frequency response and express the fault condition in terms of the noise power variance. A preliminary fault isolation is carried out by sensitivity analysis in order to identify the most influencing model parameters and assess their influence on the estimated noise. Then, during maintenance tests, the noise power is checked to detect the faulty condition. This technique is conceived to check the quality of a critical component in an experimental installation (fault detection and early-stage isolation), as well as to detect its faulty dynamic behaviors over a long horizon maintenance test campaign (condition monitoring). The method was applied to four cold compressors with active magnetic bearings at CERN by proving to be able to detect an actual faulty condition in one of such compressors.

  5. Performances Comparison for a Rotating Shaft Suspended by 4-Axis Radial Active Magnetic Bearings via -Synthesis, Loop-Shaping Design, and Sub(∞with Uncertainties

    Directory of Open Access Journals (Sweden)

    G. Barbaraci

    2011-01-01

    Full Text Available The control systems applied on active magnetic bearing are several. A perfect levitation is characterized by maintaining the operating point condition that is characterized by the center of stator coincident with the geometric center of shaft. The first controller implemented for this purpose is PID controller that is characterized by an algorithm that leads the amplifier to produce control current until the operating point condition is not reached, this is obtained by an integration operator. The effect of an integrator is essential but not necessary for a centered levitation for example in the robust control characterized by a dynamic model depended on plant of system so that it depends on angular speed as LQR controller does. In LQR there is not integrator so there is not a perfectly centered section of shaft with center of stator. On contrary PID controller does not depend on angular speed and it can be easily implemented according some simple rules. Predictive control is another interesting controller characterized by a multiple controller operating in different condition in order to get the minimum of cost function, but also in this case the angular speed is introduce for the same reason discussed before.

  6. Control of a flexible rotor active magnetic bearing test rig:a characteristic model based all-coefficient adaptive control approach

    Institute of Scientific and Technical Information of China (English)

    Long DI; Zongli LIN

    2014-01-01

    Active magnetic bearings (AMBs) have found a wide range of applications in high-speed rotating machinery industry. The instability and nonlinearity of AMBs make controller designs difficult, and when AMBs are coupled with a flexible rotor, the resulting complex dynamics make the problems of stabilization and disturbance rejection, which are critical for a stable and smooth operation of the rotor AMB system, even more difficult. Proportional-integral-derivative (PID) control dominates the current AMB applications in the field. Even though PID controllers are easy to implement, there are critical performance limitations associated with them that prevent the more advanced applications of AMBs, which usually require stronger robustness and performance offered by modern control methods such as H-infinity control andμ-synthesis. However, these advanced control designs rely heavily on the relatively accurate plant models and uncertainty characterizations, which are sometimes difficult to obtain. In this paper, we explore and report on the use of the characteristic model based all-coefficient adaptive control method to stabilize a flexible rotor AMB test rig. In spite of the simple structure of such a characteristic model based all-coefficient adaptive controller, both simulation and experimental results show its strong performance.

  7. Controlling the Stealth Effect of Nanocarriers through Understanding the Protein Corona.

    Science.gov (United States)

    Schöttler, Susanne; Landfester, Katharina; Mailänder, Volker

    2016-07-25

    The past decade has seen a significant increase in interest in the use of polymeric nanocarriers in medical applications. In particular, when used as drug vectors in targeted delivery, nanocarriers could overcome many obstacles for drug therapy. Nevertheless, their application is still impeded by the complex composition of the blood proteins covering the particle surface, termed the protein corona. The protein corona complicates any prediction of cell interactions, biodistribution, and toxicity. In particular, the unspecific uptake of nanocarriers is a major obstacle in clinical studies. This Minireview provides an overview of what we currently know about the characteristics of the protein corona of nanocarriers, with a focus on surface functionalization that reduces unspecific uptake (the stealth effect). The ongoing improvement of nanocarriers to allow them to meet all the requirements necessary for successful application, including targeted delivery and stealth, are further discussed.

  8. Novel Caffeic Acid Nanocarrier: Production, Characterization, and Release Modeling

    Directory of Open Access Journals (Sweden)

    Milad Fathi

    2013-01-01

    Full Text Available This paper deals with the development of novel nanocarriers using layer by layer carbohydrate coating of caffeic acid loaded solid lipid nanoparticles (SLNs to improve stability and colon delivery of the poorly water-soluble caffeic acid. Three biopolymers (chitosan, alginate, and pectin in different concentrations (0.1, 0.25, and 0.5% were electrostatically coated over the SLN surface. The size and zeta potential of produced nanocarriers were measured using photon correlation spectroscopy. Mathematical models (i.e., zero-order, first-order, Higuchi, Ritger-Peppas, reciprocal powered time, Weibull, and quadratic models were used to describe the release and kinetic modeling in gastrointestinal solution (GIS. Also, antioxidant activity of caffeic acid during the release in GIS was investigated using DPPH and reducing activity methods. The prepared treatments coated by alginate-chitosan as well as pectin-chitosan coated SLN at the concentration of 0.1% showed nanosized bead; the latter efficiently retarded the release of caffeic acid in gastric media up to 2.5 times higher than that of SLN. Zeta potential values of coated samples were found to significantly increase in comparison to SLN indicating the higher stability of produced nanocarriers. Antioxidant activity of caffeic acid after gastric release did not result in the same trend as observed for caffeic acid release from different treatments; however, in line with less caffeic acid release in the intestine solution by the effect of coating, lower antioxidant activity was determined at the end stage of the experiment.

  9. Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sohyun [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cha, Song-Hyun [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, Inyoung [School of Civil, Environmental and Architecture Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Park, Soomin [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Yohan [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); Cho, Seonho [National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Park, Youmie, E-mail: youmiep@inje.ac.kr [College of Pharmacy, Inje University, 197 Inje-ro Gimhae, Gyeongnam 621-749 (Korea, Republic of); National Creative Research Initiatives (NCRI) Center for Isogeometric Optimal Design, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2016-01-01

    This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412–417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of − 20.58 to − 48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities. - Highlights

  10. Antibacterial nanocarriers of resveratrol with gold and silver nanoparticles.

    Science.gov (United States)

    Park, Sohyun; Cha, Song-Hyun; Cho, Inyoung; Park, Soomin; Park, Yohan; Cho, Seonho; Park, Youmie

    2016-01-01

    This study focused on the preparation of resveratrol nanocarrier systems and the evaluation of their in vitro antibacterial activities. Gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) for resveratrol nanocarrier systems were synthesized using green synthetic routes. During the synthesis steps, resveratrol was utilized as a reducing agent to chemically reduce gold and silver ions to AuNPs and AgNPs. This system provides green and eco-friendly synthesis routes that do not involve additional chemical reducing agents. Resveratrol nanocarriers with AuNPs (Res-AuNPs) and AgNPs (Res-AgNPs) were observed to be spherical and to exhibit characteristic surface plasmon resonance at 547 nm and at 412-417 nm, respectively. The mean size of the nanoparticles ranged from 8.32 to 21.84 nm, as determined by high-resolution transmission electron microscopy. The face-centered cubic structure of the Res-AuNPs was confirmed by high-resolution X-ray diffraction. Fourier-transform infrared spectra indicated that the hydroxyl groups and C=C in the aromatic ring of resveratrol were involved in the reduction reaction. Res-AuNPs retained excellent colloidal stability during ultracentrifugation and re-dispersion, suggesting that resveratrol also played a role as a capping agent. Zeta potentials of Res-AuNPs and Res-AgNPs were in the range of -20.58 to -48.54 mV. Generally, against Gram-positive and Gram-negative bacteria, the Res-AuNPs and Res-AgNPs exhibited greater antibacterial activity compared to that of resveratrol alone. Among the tested strains, the highest antibacterial activity of the Res-AuNPs was observed against Streptococcus pneumoniae. The addition of sodium dodecyl sulfate during the synthesis of Res-AgNPs slightly increased their antibacterial activity. These results suggest that the newly developed resveratrol nanocarrier systems with metallic nanoparticles show potential for application as nano-antibacterial agents with enhanced activities.

  11. Investigation of nanocarriers and excipients for preparation of nanoembedded microparticles

    DEFF Research Database (Denmark)

    Wang, Yingya; Beck-broichsitter, Moritz; Yang, Mingshi

    2017-01-01

    polymer nanocarriers (poly(lactide-co-glycolide), poly(styrene), chitosan and dendrimers) were used for preparing NEMs by spray-drying. Further, distinct matrix excipients were investigated including sugars (i.e., trehalose, sucrose, mannitol) and polymers (poly(vinyl pyrrolidone) and poly(ethylene glycol...... (trehalose, sucrose, poly(vinyl pyrrolidone)) are superior to spray-dried crystalline excipients (mannitol, poly(ethylene glycol)) for stabilizing NEMs. It is therefore important to select an appropriate excipient for stabilization of a given nanoparticle system and identify a suitable level...

  12. Structure, adsorption and magnetic properties of chiral metal-organic frameworks bearing linear trinuclear secondary building blocks.

    Science.gov (United States)

    Chen, Zilu; Liu, Xianlin; Zhang, Chuanbing; Zhang, Zhong; Liang, Fupei

    2011-03-07

    The reactions of new chiral organic ligands trimesoyltri(L-alanine) (L-TMTAH(3)) or trimesoyltri(D-alanine) (D-TMTAH(3)) with transition metal salts in the presence of an ancillary ligand of 4,4'-bipyridine gave two pairs of three dimensional frameworks [Co(3)(L-TMTA)(2)(4,4'-bpy)(4)]·28H(2)O (1), [Co(3)(D-TMTA)(2)(4,4'-bpy)(4)]·28H(2)O (2) [Ni(3)(L-TMTA)(2)(4,4'-bpy)(4)]·2C(2)H(5)OH·14H(2)O (3) and [Ni(3)(D-TMTA)(2)(4,4'-bpy)(4)]·2C(2)H(5)OH·14H(2)O (4). These compounds were characterized by elemental analysis, IR, and X-ray powder diffraction analysis and the structures of 1-3 were determined from X-ray single crystal diffraction analysis. Complexes 1-4 feature linear trinuclear secondary building blocks [M(3)(COO)(4)](2+) formed via the connection of three metal ions by four carboxylato groups from four TMTA(3-) ligands. Every adjacent two linear trinuclear secondary building blocks are linked by one and three 4,4'-bipyridine molecules along the a and c axis, respectively, to form two-dimensional sheets, which are further connected by TMTA(3-) ligands to construct a porous three dimensional framework with one-dimensional channels. Compound 3 was taken as an example to investigate the adsorption properties of compounds 1-4. It revealed a saturated hydrogen uptake of 216.6 cm(3) g(-1) (2.0 wt%) at 11.1 atm measured at 77 K, a maximum CO(2) uptake of 119.4 cm(3) g(-1) (23.5 wt%) at 19.5 atm measured at 298 K and a saturated CH(4) uptake of 77.8 cm(3) g(-1) (5.6 wt%) at 27.1 atm measured at 298 K. The magnetic studies of complexes 1 and 3 indicate the presence of antiferromagnetic interactions between the metal ions in the two compounds.

  13. Research on Design and Mechanical Properties of Permanent Magnetic Bearings for Vertical Wind Turbines%立式风力发电机用永磁轴承的设计及其力学性能研究

    Institute of Scientific and Technical Information of China (English)

    张钢; 倪晓艇; 孟庆涛; 刘飞; 张坚

    2015-01-01

    To reduce startup wind speed of wind turbines,the structural design and mechanical properties of permanent magnetic bearings for 1 kW vertical wind turbines are studied from perspective of supporting technology.The permanent magnetic bearings are manufactured and assembled.The accuracy of theoretical analysis is verified by loading experi-ments,and the industrial application of the bearings is discussed.The results show that the bearings expand adaptive areas of wind fields,the rotational speed of permanent magnetic levitation wind turbines and generated energy is much higher than that of wind turbines supported by rolling bearings.%为降低风力发电机的启动风速,从支承技术角度对1 kW 立式风力发电机用永磁轴承结构设计及其力学性能进行了研究。对设计的永磁轴承进行了加工和装配,通过加载试验验证了理论分析的准确性,探索了永磁轴承的工业应用。结果表明:该轴承扩大了适应风场的区域,永磁轴承支承的风力发电机的转速及发电量明显高于滚动轴承支承的风力发电机。

  14. Anisotropies of field-dependent in-phase and out-of-phase magnetic susceptibilities of some pyrrhotite-bearing rocks

    Science.gov (United States)

    Hrouda, Frantisek; Chadima, Martin; Jezek, Josef

    2017-04-01

    Pyrrhotite shows strong and non-linear variations of both the in-phase and out-of-phase magnetic susceptibilities with magnetizing field unlike to magnetite and paramagnetic minerals whose susceptibility is field independent if measured in low fields. Consequently, the magnetic sub-fabric of pyrrhotite unaffected by magnetite/paramagnetics can be directly investigated either through the anisotropy of field-dependent in-phase susceptibility (hdAMS) or through the anisotropy of out-of-phase susceptibility (opAMS). If the driving fields used for the susceptibility measurement are really low, within the range of validity of the Rayleigh Law, both the field-dependent component of the hdAMS and the opAMS are represented by the field-independent second rank Rayleigh Tensor. The determination of the Rayleigh Tensor via hdAMS requires the AMS measurements in several fields within the Rayleigh Law range, while in the determination of the Rayleigh Tensor via opAMS the measurement in one field is sufficient. It should be noted that if the AMS is measured by the KLY5 Kappabridge, the opAMS is measured simultaneously with standard in-phase AMS (ipAMS) during one measuring process. The Rayleigh Tensors determined by the above two methods should be more or less identical provided that the opAMS of pyrrhotite is dominantly due to weak field hysteresis, virtually unaffected by electrical eddy currents or viscous relaxation. In a collection of various pyrrhotite-bearing rocks, both the hdAMS and opAMS were investigated using the KLY5 Kappabridge and the correlations between the Rayleigh Tensors determined by the above two methods were made in terms of the anisotropy degree, shape parameter, and the orientations of principal directions. Reasonable correlations were found indicating that the pyrrhotite opAMS is dominantly due to weak field hysteresis. As the opAMS is measured automatically and simultaneously with standard ipAMS, the advantage of the opAMS in the determination of the

  15. 五自由度全永磁轴承系统的稳定悬浮特性分析%Stable Levitation Performance Analysis of Five Degrees of Freedom All Permanent Magnetic Bearing System

    Institute of Scientific and Technical Information of China (English)

    张钢; 孟庆涛; 钟永彦; 张坚; 张海龙; 樊曼

    2015-01-01

    为探讨永磁悬浮轴承系统的稳定悬浮特性,从轴承刚度角度对五自由度全永磁轴承系统的稳定悬浮特性进行了分析。采用等效磁荷理论建立永磁轴承的承载力、承载力矩和刚度的数学表达式,并利用蒙特卡洛法对表达式中存在的四重积分进行求解。探究转子在受迫进动情况下以及受到外力矩干扰时继续保持稳定旋转所需要的最低临界转速。基于轴向永磁轴承与径向永磁轴承的结构,提出一种六磁环五自由度全永磁轴承系统结构模型,对全永磁轴承的转子系统承受轴向和径向外载荷的承载力、力矩和承载刚度进行分析,得出轴向可以承受外载荷而径向无法承受外载荷,即静态下轴向可以稳定悬浮、径向不能稳定悬浮,符合 Earnshaw 定理。利用刚性转子的陀螺惯性力矩来承受全永磁轴承系统的不平衡力矩和外力矩,从而保持转子定轴自稳定悬浮,并对系统稳定悬浮特性进行计算,结果表明转子在超过最低临界转速后是可以实现动态稳定悬浮的,具有一定的工程应用价值。%To investigate the stable levitation performance of permanent magnetic bearings system, the stable levitation performance of the five-DOF permanent magnetic bearing (PMB) system is analyzed from the perspective of bearing stiffness. The analysis formulas of PMB’ s loading capacity, torque and stiffness are established based on the equivalent magnetic charge theory, then use Monte Carlo method to solve the quadruple integral formula to get the result of the force, moment and stiffness. The minimum critical speed for rotor in the case of forced precession and in the situation of external torque is explored. Puts forward a six circular magnetic rings and five DOF all permanent magnetic bearing structure model based on the structure of radial and axial magnetic bearings, the carrying capacity, moment and stiffness of five-DOF PMB

  16. 基于LabVIEW的磁悬浮轴承的静态刚度测量系统%Measurement System of Static Stiffness for Magnetic Bearings Based on LabVIEW

    Institute of Scientific and Technical Information of China (English)

    马骁; 尹成科; 陈琛

    2012-01-01

    Rotors can be suspended in stators through electromagnetic force in magnetic bearings. The static stiffness is one important technical characteristic of magnetic bearings, so it is a necessary procedure to measure static stiffness for magnetic bearings. A static stiffness measurement system was established up for active magnetic bearings in the open-loop control. This system was based on LabVIEW software development platform, and included X - Y - Z precision motorized stages, six-axis force/torque transducer,laser optical displacement sensor,and high precision ammeter for the most part. An industrial personal computer controlled every measurement cell for automatic measurement, acquisition, and data storage. It has the advantage of high automation.%磁悬浮轴承主要利用电磁力使转子悬浮于定子中,其刚度特性是磁悬浮轴承的重要技术指标,因此磁悬浮轴承的刚度测量是检验磁悬浮轴承性能的必要环节.文中建立了适用于混合控制的磁悬浮轴承在开环控制下的静态刚度测量系统.该系统利用LabVIEW软件开发测量平台,由X-Y -Z电控精密位移台、六自由度力传感器、激光位移传感器及高分辨率电流表等设备组成,并由工控机统一控制各测量单元,实现自动测量、自动采集与数据存储等功能,具有自动化程度高的优点.

  17. Hydrodynamic bearings

    CERN Document Server

    Bonneau, Dominique; Souchet, Dominique

    2014-01-01

    This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book describes the rheological models and the equations of lubrication. It also presents the numerical approaches used to solve the above equations by finite differences, finite volumes and finite elements methods.

  18. Hybrid Collagenase Nanocapsules for Enhanced Nanocarrier Penetration in Tumoral Tissues.

    Science.gov (United States)

    Villegas, María Rocío; Baeza, Alejandro; Vallet-Regí, María

    2015-11-01

    Poor penetration of drug delivery nanocarriers within dense extracellular matrices constitutes one of the main liabilities of current nanomedicines. The conjugation of proteolytic enzymes on the nanoparticle surface constitutes an attractive alternative. However, the scarce resistance of these enzymes against the action of proteases or other aggressive agents present in the bloodstream strongly limits their application. Herein, a novel nanodevice able to transport proteolytic enzymes coated with an engineered pH-responsive polymeric is presented. This degradable coat protects the housed enzymes against proteolytic attack at the same time that it triggers their release under mild acidic conditions, usually present in many tumoral tissues. These enzyme nanocapsules have been attached on the surface of mesoporous silica nanoparticles, as nanocarrier model, showing a significatively higher penetration of the nanoparticles within 3D collagen matrices which housed human osteosarcoma cells (HOS). This strategy can improve the therapeutic efficacy of the current nanomedicines, allowing a more homogeneous and deeper distribution of the therapeutic nanosystems in cancerous tissues.

  19. Highlights in nanocarriers for the treatment against cervical cancer.

    Science.gov (United States)

    Medina-Alarcón, Kaila P; Voltan, Aline R; Fonseca-Santos, Bruno; Moro, Isabela Jacob; de Oliveira Souza, Felipe; Chorilli, Marlus; Soares, Christiane Pienna; Dos Santos, André Gonzaga; Mendes-Giannini, Maria J S; Fusco-Almeida, Ana M

    2017-11-01

    Cervical cancer is the second most common malignant tumor in women worldwide and has a high mortality rate, especially when it is associated with human papillomavirus (HPV). In US, an estimated 12,820 cases of invasive cervical cancer and an estimated 4210 deaths from this cancer will occur in 2017. With rare and very aggressive conventional treatments, one sees in the real need of new alternatives of therapy as the delivery of chemotherapeutic agents by nanocarriers using nanotechnology. This review covers different drug delivery systems applied in the treatment of cervical cancer, such as solid lipid nanoparticles (SNLs), liposomes, nanoemulsions and polymeric nanoparticles (PNPs). The main advantages of drug delivery thus improving pharmacological activity, improving solubility, bioavailability to bioavailability reducing toxicity in the target tissue by targeting of ligands, thus facilitating new innovative therapeutic technologies in a too much needed area. Among the main disadvantage is the still high cost of production of these nanocarriers. Therefore, the aim this paper is review the nanotechnology based drug delivery systems in the treatment of cervical cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. How can lipid nanocarriers improve transdermal delivery of olanzapine?

    Science.gov (United States)

    Iqbal, Nimra; Vitorino, Carla; Taylor, Kevin M G

    2017-06-01

    The development of a transdermal nanocarrier drug delivery system with potential for the treatment of psychiatric disorders, such as schizophrenia and bipolar disorder, is described. Lipid nanocarriers (LN), encompassing various solid:liquid lipid compositions were formulated and assessed as potential nanosystems for transdermal delivery of olanzapine. A previously optimized method of hot high pressure homogenization (HPH) was adopted for the production of the LN, which comprised solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and nanoemulsions (NE). Precirol( ®) was selected as the solid lipid for progression of studies. SLN exhibited the best performance for transdermal delivery of olanzapine, based on in vitro release and permeation studies, coupled with results from physicochemical characterization of several solid:liquid lipid formulations. Stability tests, performed to give an indication of long-term storage behavior of the formulations, were in good agreement with previous studies for the best choice of solid:liquid lipid ratio. Overall, these findings highlight the SLN-based formulation as promising for the further inclusion in and production of transdermal patches, representing an innovative therapeutic approach.

  1. Nanocarriers from GRAS Zein Proteins to Encapsulate Hydrophobic Actives.

    Science.gov (United States)

    Weissmueller, Nikolas T; Lu, Hoang D; Hurley, Amanda; Prud'homme, Robert K

    2016-11-14

    One factor limiting the expansion of nanomedicines has been the high cost of the materials and processes required for their production. We present a continuous, scalable, low cost nanoencapsulation process, Flash Nanoprecipitation (FNP) that enables the production of nanocarriers (NCs) with a narrow size distribution using zein corn proteins. Zein is a low cost, GRAS protein (having the FDA status of "Generally Regarded as Safe") currently used in food applications, which acts as an effective encapsulant for hydrophobic compounds using FNP. The four-stream FNP configuration allows the encapsulation of very hydrophobic compounds in a way that is not possible with previous precipitation processes. We present the encapsulation of several model active compounds with as high as 45 wt % drug loading with respect to zein concentration into ∼100 nm nanocarriers. Three examples are presented: (1) the pro-drug antioxidant, vitamin E-acetate, (2) an anticholera quorum-sensing modulator CAI-1 ((S)-3-hydroxytridecan-4-one; CAI-1 that reduces Vibrio cholerae virulence by modulating cellular communication), and (3) hydrophobic fluorescent dyes with a range of hydrophobicities. The specific interaction between zein and the milk protein, sodium caseinate, provides stabilization of the NCs in PBS, LB medium, and in pH 2 solutions. The stability and size changes in the three media provide information on the mechanism of assembly of the zein/active/casein NC.

  2. Recent advances in multifunctional silica-based hybrid nanocarriers for bioimaging and cancer therapy

    Science.gov (United States)

    Lim, Wei Qi; Phua, Soo Zeng Fiona; Xu, Hesheng Victor; Sreejith, Sivaramapanicker; Zhao, Yanli

    2016-06-01

    In recent years, there has been a considerable research focus on integrating cancer cell imaging and therapeutic functions into single nanoscale platforms for better treatment of cancer. This task could often be achieved by incorporating multiple components into a hybrid nanosystem. In this minireview, we highlight different types of silica-based hybrid nanosystems and their recent applications as integrated multifunctional platforms for cancer imaging and treatment. The discussions are divided into several sections focusing on various types of materials employed to integrate with silica, which include silica-metallic nanoparticle based hybrid nanocarriers, silica-gold nanoparticle based hybrid nanocarriers, silica-quantum dot based hybrid nanocarriers, silica-upconversion nanoparticle based hybrid nanocarriers, silica-carbon based hybrid nanocarriers, and organosilica nanocarriers. Therapeutic agents loaded in such hybrids include chemodrugs, proteins, DNA/RNA and photosensitizers. For targeted delivery into tumor sites, targeting ligands such as antibodies, peptides, aptamers, and other small molecules are grafted on the surface of the nanocarriers. At the end of the review, a brief summary and research outlook are presented. This minireview aims to provide a quick update of recent research achievements in the field.

  3. Novel Repeatable Inner Locking Device for Magnetic Bearing Flywheel%磁悬浮飞轮用新型可重复内锁紧机构

    Institute of Scientific and Technical Information of China (English)

    刘强; 曹建树; 房建成; 徐宝东

    2014-01-01

    为减小磁悬浮飞轮整机的体积质量和降低发射成本,提出了一种基于锥面锁紧和摩擦自锁的可重复内锁紧机构,并介绍了其结构、工作原理。根据发射振动条件对锁紧机构进行静力学分析,得到锁紧机构各项锁紧参数。在此基础上,通过选择锁台位置和锥面约束面积,采用有限元法对锁紧状态下的飞轮转子进行动力学模态计算。根据设计结果研制了一套锁紧机构,并通过正弦扫频振动和随机振动模拟卫星发射振动工况,检验锁紧机构对磁悬浮飞轮系统的保护效果。结果显示,振动试验中飞轮系统无明显共振发生,飞轮定、转子间最大相对振动位移为30μm,远小于飞轮保护间隙200μm,表明锁紧机构能够对飞轮系统实施有效保护。%In order to reduce the volume, weight and launch cost of magnetic bearing flywheel as a whole, a repeatable inner loc⁃king device based on conical surface to lock and friction self⁃locking to keep locking was presented. Its composition and operating prin⁃ciple were introduced. According to launch vibration condition, the static analysis of locking device was carried out and the locking pa⁃rameters were obtained. Upon this basis, by choosing locking step position and conical constraint area, the dynamics modals of flywheel rotor under locking state were calculated by finite element method ( FEM) . According to design results, a locking device was devel⁃oped, and vibration working condition of satellite launching was simulated by swept⁃sine vibration and random vibration, so as to verify the protection effects on the magnetic bearing flywheel by the locking device. The result shows that, no resonance occurs during testing of the flywheel, and the maximum relative vibration displacement between stator and rotor is at 30 μm far less than the protection gap of 200 μm, which indicates the locking device can effectively protect flywheel

  4. Green Synthesis of Sub-10 nm Gadolinium-Based Nanoparticles for Sparkling Kidneys, Tumor, and Angiogenesis of Tumor-Bearing Mice in Magnetic Resonance Imaging.

    Science.gov (United States)

    Zhang, Bingbo; Yang, Weitao; Yu, Jiani; Guo, Weisheng; Wang, Jun; Liu, Shiyuan; Xiao, Yi; Shi, Donglu

    2017-02-01

    Gadolinium (Gd)-based nanoparticles are known for their high potential in magnetic resonance imaging (MRI). However, further MRI applications of these nanoparticles are hampered by their relatively large sizes resulting in poor organ/tumor targeting. In this study, ultrafine sub-10 nm and biocompatible Gd-based nanoparticles are synthesized in a bioinspired, environmentally benign, and straightforward fashion. This novel green synthetic strategy is developed for growing dextran-coated Gd-based nanoparticles (GdNPs@Dex). The as-prepared GdNPs@Dex is not only biocompatible but also stable with a sub-10 nm size. It exhibits higher longitudinal and transverse relaxivities in water (r1 and r2 values of 5.43 and 7.502 s(-1) × 10(-3) m(-1) of Gd(3+) , respectively) than those measured for Gd-DTPA solution (r1 and r2 values of 3.42 and 3.86 s(-1) × 10(-3) m(-1) of Gd(3+) , respectively). In vivo dynamic T1 -weighted MRI in tumor-bearing mice shows GdNPs@Dex can selectively target kidneys and tumor, in addition to liver and spleen. GdNPs@Dex is found particularly capable for determining the tumor boundary with clearly enhanced tumor angiogenesis. GdNPs@Dex is also found cleared from body gradually mainly via hepatobiliary and renal processing with no obvious systemic toxicity. With this green synthesis strategy, the sub-10 nm GdNPs@Dex presents promising potentials for translational biomedical imaging applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fuzzy Active Disturbance Rejection Control for Axial Active Magnetic Bearings%轴向主动磁轴承的模糊自抗扰控制

    Institute of Scientific and Technical Information of China (English)

    卢立户; 刘海娟; 诸德宏; 徐荣

    2011-01-01

    为了实现轴向主动磁轴承的准确和稳定控制,根据模糊控制理论和自抗扰控制(ADRC)理论,设计了轴向主动磁轴承模糊自抗扰控制系统,采用模糊控制器整定ADRC中非线性控制参数,并且给出了其控制算法和控制系统的结构.利用软件Matlab/Simulink对所设计的控制系统进行了仿真研究,仿真结果表明:所设计的轴向主动磁轴承模糊自抗扰控制系统具有响应速度快、超调量小、抗干扰能力强和鲁棒性好等特点.%In order to achieve the precise and steady control of axial active magnetic bearing ( AMB), a fuzzy active disturbance rejection control (ADRC) system is designed for axial AMB based on the theory of fuzzy control and AD-RC. The nonlinear parameters of ADRC are designed with fuzzy control,and the control arithmetic and system's configuration are given. The simulation study of control system is operated by the software Matlab/Simulink. The results show that the fuzzy ADRC system for axial AMB has many advantages, such as fast response, small overshoot, strong anti -disturbance and strong robustness.

  6. Polycaprolactone/maltodextrin nanocarrier for intracellular drug delivery: formulation, uptake mechanism, internalization kinetics, and subcellular localization.

    Science.gov (United States)

    Korang-Yeboah, Maxwell; Gorantla, Yamini; Paulos, Simon A; Sharma, Pankaj; Chaudhary, Jaideep; Palaniappan, Ravi

    2015-01-01

    Prostate cancer (PCa) disease progression is associated with significant changes in intracellular and extracellular proteins, intracellular signaling mechanism, and cancer cell phenotype. These changes may have direct impact on the cellular interactions with nanocarriers; hence, there is the need for a much-detailed understanding, as nanocarrier cellular internalization and intracellular sorting mechanism correlate directly with bioavailability and clinical efficacy. In this study, we report the differences in the rate and mechanism of cellular internalization of a biocompatible polycaprolactone (PCL)/maltodextrin (MD) nanocarrier system for intracellular drug delivery in LNCaP, PC3, and DU145 PCa cell lines. PCL/MD nanocarriers were designed and characterized. PCL/MD nanocarriers significantly increased the intracellular concentration of coumarin-6 and fluorescein isothiocyanate-labeled bovine serum albumin, a model hydrophobic and large molecule, respectively. Fluorescence microscopy and flow cytometry analysis revealed rapid internalization of the nanocarrier. The extent of nanocarrier cellular internalization correlated directly with cell line aggressiveness. PCL/MD internalization was highest in PC3 followed by DU145 and LNCaP, respectively. Uptake in all PCa cell lines was metabolically dependent. Extraction of endogenous cholesterol by methyl-β-cyclodextrin reduced uptake by 75%±4.53% in PC3, 64%±6.01% in LNCaP, and 50%±4.50% in DU145, indicating the involvement of endogenous cholesterol in cellular internalization. Internalization of the nanocarrier in LNCaP was mediated mainly by macropinocytosis and clathrin-independent pathways, while internalization in PC3 and DU145 involved clathrin-mediated endocytosis, clathrin-independent pathways, and macropinocytosis. Fluorescence microscopy showed a very diffused and non-compartmentalized subcellular localization of the PCL/MD nanocarriers with possible intranuclear localization and minor colocalization in

  7. [Investigation on the migration and biologic effects of nano FeOx powders under the exposure of extremely low frequency altering electric magnetic field in human heptoma-bearing nude mice in vivo].

    Science.gov (United States)

    Ju, Hui-Xiang; Dai, Zhen-Yu; Sun, Ming-Zhong

    2011-08-01

    To investigate the mechanism and biologic effects of 37 nm magnetic nano FeOx powders (MNPs) on human hepatoma-bearing nude mice. 37 nm MNPs were prepared by coprecipitation methods and then injected into human hepatoma (Bel-7402) bearing-nude mice through the tail vein. After injection of MNPs, the mice were first exposed under static magnetic field and then treated under extremely low frequency altering-electric magnetic field directing to the tumor area. The migration and trafficking of MNPs were determined by MMR. Tumor growth was monitored with calipers every 5 days and tumor volume was calculated on the basis of three-dimensioned measurements. The apoptosis of tumor cells was analyzed by flow cytometry analysis. The expressions of apoptosis-associated proteins Bcl-2, Bax and HSP27 were determined using western-blot analysis. Static magnetic field could direct the migration and trafficking of MNPs to the tumor site with a higher ratio of 98.9%. Extremely Low Frequency Electric-Magnetic Field (EMF) treatment could inhibit the proliferation of tumor cells and prolong the survive time of tumor-bearing mice injected with MNPs. In addition, the survival time of tumor-bearing mice and percentages of prohibition on tumor cell growth were 27.4+/-0.7 days and 37.5+/-0.8% (F = 0.005, P is less than to 0.05), respectively. The results of flow cytometry analyses showed that about 18.1+/-0.6% (F = 0.030, P is less than to 0.05) of tumor cells were induced into early apoptosis. Furthermore, expressions of apoptosis-associated proteins Bcl-2 and Bax were significantly induced by MNPs under EMF treatment. The ratio of Bcl/Bax in both MNPs and EMF treatment group was 0.07+/-0.01, which was much lower than that of control group (0.23+/-0.02) (F = 0.016, P is less than to 0.05). Heat shock protein-27 (Hsp-27) was not significantly induced in different treatment groups. Injection of MNPs with EMF exposure on human hepatoma-bearing nude mice could significantly prolong the

  8. Visualization of thermally activated nanocarriers using in situ atomic force microscopy

    DEFF Research Database (Denmark)

    Dong, M. D.; Howard, K. A.; Oupicky, D.

    2007-01-01

    Thermo-responsive nanocarriers aim to improve the delivery of drugs into target tissue by a process of size-mediated deposition activated by thermal stimuli. The direct imaging of thermally-induced changes in nanocarrier morphology was demonstrated using in situ liquid AFM over a nano-scale and t......-scale and temperature range relevant for clinical approaches. In situ AFM proved to be a unique method for investigating the dynamic conformational changes of individual nanoparticles, promoting its application in the future development of stimuli-responsive nanocarriers....

  9. Magnetic bearing optical delay line

    NARCIS (Netherlands)

    Dool, T.C. van den; Kamphues, F.G.; Fouss, B.; Henrioulle, K.; Hogenhuis, H.

    2004-01-01

    TNO TPD, in close cooperation with Micromega-Dynamics and Dutch Space, has developed an advanced Optical Delay Line (ODL) for use in PRIMA, GENIE and other ground based interferometers. The delay line design is modular and flexible, which makes scaling for other applications a relatively easy task.

  10. Lipid-based nanocarriers for oral peptide delivery.

    Science.gov (United States)

    Niu, Zhigao; Conejos-Sánchez, Inmaculada; Griffin, Brendan T; O'Driscoll, Caitriona M; Alonso, María J

    2016-11-15

    This article is aimed to overview the lipid-based nanostructures designed so far for the oral administration of peptides and proteins, and to analyze the influence of their composition and physicochemical (particle size, zeta potential) and pharmaceutical (drug loading and release) properties, on their interaction with the gastro-intestinal environment, and the subsequent PK/PD profile of the associated drugs. The ultimate goal has been to highlight and comparatively analyze the key factors that may be determinant of the success of these nanocarriers for oral peptide delivery. The article ends with some prospects on the challenges to be addressed for the intended commercial success of these delivery vehicles. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Lycopene from tomatoes: vesicular nanocarrier formulations for dermal delivery.

    Science.gov (United States)

    Ascenso, Andreia; Pinho, Sónia; Eleutério, Carla; Praça, Fabíola Garcia; Bentley, Maria Vitória Lopes Badra; Oliveira, Helena; Santos, Conceição; Silva, Olga; Simões, Sandra

    2013-07-31

    This experimental work aimed to develop a simple, fast, economic, and environmentally friendly process for the extraction of lycopene from tomato and incorporate this lycopene-rich extract into ultradeformable vesicular nanocarriers suitable for topical application. Lycopene extraction was conducted without a cosolvent for 30 min. The extracts were analyzed and incorporated in transfersomes and ethosomes. These formulations were characterized, and the cellular uptake was observed by confocal microscopy. Dermal delivery of lycopene formulations was tested under in vitro and in vivo conditions. Lycopene extraction proved to be quite safe and selective. The vesicular formulation was taken up by the cells, being more concentrated around the nucleus. Epicutaneous application of lycopene formulations decreased the level of anthralin-induced ear swelling by 97 and 87%, in a manner nonstatistically different from the positive control. These results support the idea that the lycopene-rich extract may be a good alternative to the expensive commercial lycopene for incorporation into advanced topical delivery systems.

  12. Using exosomes, naturally-equipped nanocarriers, for drug delivery.

    Science.gov (United States)

    Batrakova, Elena V; Kim, Myung Soo

    2015-12-10

    Exosomes offer distinct advantages that uniquely position them as highly effective drug carriers. Comprised of cellular membranes with multiple adhesive proteins on their surface, exosomes are known to specialize in cell-cell communications and provide an exclusive approach for the delivery of various therapeutic agents to target cells. In addition, exosomes can be amended through their parental cells to express a targeting moiety on their surface, or supplemented with desired biological activity. Development and validation of exosome-based drug delivery systems are the focus of this review. Different techniques of exosome isolation, characterization, drug loading, and applications in experimental disease models and clinic are discussed. Exosome-based drug formulations may be applied to a wide variety of disorders such as cancer, various infectious, cardiovascular, and neurodegenerative disorders. Overall, exosomes combine benefits of both synthetic nanocarriers and cell-mediated drug delivery systems while avoiding their limitations.

  13. Nanocarriers for Delivery of Antioxidants on the Skin

    Directory of Open Access Journals (Sweden)

    María Pilar Vinardell

    2015-10-01

    Full Text Available Skin is protected from the harmful effects of free radicals by the presence of an endogenous antioxidant system. However, when exposed to ultraviolet (UV radiation, there is an imbalance between pro-oxidants and antioxidants, leading to oxidative stress and photoaging of the skin. It has been described that free radicals and other reactive species can cause severe damage to cells and cell components of the skin, which results in skin aging and cancer. To prevent these actions on skin, the use of topical antioxidant supplementation is a strategy used in the cosmetics industry and these antioxidants act on quenching free radicals. There are many studies that demonstrated the antioxidant activity of many phytochemicals or bioactive compounds by free radical scavenging. However, many bioactive substances are unstable when exposed to light or lose activity during storage. The potential sensitivity of these substances to light exposure is of importance in cosmetic formulations applied to skin because photo-degradation might occur, reducing their activity. One strategy to reduce this effect on the skin is the preparation of different types of nanomaterials that allow the encapsulation of the antioxidant substances. Another problem related to some antioxidants is their inefficient percutaneous penetration, which limits the amount of the active ingredient able to reach the site of action in viable epidermis and dermis. In this sense, the encapsulation in polymeric nanoparticles could enhance the permeation of these substances. Nanocarriers offers several advantages over conventional passive delivery, such as increased surface area, higher solubility, improved stability, controlled release, reduced skin irritancy, and protection from degradation. The different nanocarrier systems used in cosmetics include nanolipid delivery systems such as solid lipid nanoparticles (SLN and nanostructured lipid carriers (NLC, nanoemulsions (NEs, nanoparticles (NP

  14. MRI monitoring of nanocarrier accumulation and release using Gadolinium-SPIO co-labelled thermosensitive liposomes

    NARCIS (Netherlands)

    Lorenzato, Cyril; Oerlemans, Chris; van Elk, Merel; Geerts, Willie J C|info:eu-repo/dai/nl/149264399; Denis de Senneville, Baudouin; Moonen, Chrit; Bos, Clemens

    2016-01-01

    Encapsulation of anticancer drugs in triggerable nanocarriers can beneficially modify pharmacokinetics and biodistribution of chemotherapeutic drugs, and consequently increase tumor drug concentration and efficacy, while reducing side effects. Thermosensitive liposomes release their contents trigger

  15. Hydrodynamic interactions for complex-shaped nanocarriers in targeted drug delivery

    Science.gov (United States)

    Wang, Yaohong; Eckmann, David; Radhakrishnan, Ravi; Ayyaswamy, Portonovo

    2014-11-01

    Nanocarrier motion in a blood vessel involves hydrodynamic and Brownian interactions, which collectively dictate the efficacy in targeted drug delivery. The shape of nanocarriers plays a crucial role in drug delivery. In order to quantify the flow and association properties of elliptical nanoparticles, we have developed an arbitrary Lagrangian-Eulerian framework with capabilities to simulate the hydrodynamic motion of nanoparticles of arbitrary shapes. We introduce the quaternions for rotational motion, and two collision models, namely, (a) an impulse-based model for wall-particle collision, and (b) the short-range repulsive Gay-Berne potential for particle-particle collision. We also study the red blood cell and nanocarrier (such as ellipsoid) interactions. We compare our results with those obtained for a hard sphere model for both RBCs and nanocarriers. Supported by NIH through grant U01-EB016027.

  16. Preparation and Photodynamic Anti-tumor Activity of Magnetic Polylactic Acid Nanoparticles Loaded with Photosensitizer

    Institute of Scientific and Technical Information of China (English)

    YANG Xiao-xia; HUANG Hui; CHEN Zhi-long; HUANG Peng; SUN Yun; ZHOU Xing-ping

    2010-01-01

    A novel magnetic nanocarrier was strategically designed and successfully prepared. Photosensitizer 2, 7,12, 18-tetramethyl-3, 8-di-(1-propoxyethyl)-13, 17-bis-( 3-hydroxypropyl ) porphyrin ( PHPP ) wasencapsulated into polylactic acid (PLA)-coated Fe3O4nanoparticles. The diameter of nanocarrier is 30-50 nm by transmission electron micrograph ( TEM ). The encapsulation efficiency of photosensitizer is 27.98% calculated from UV-vis absorption spectra. The nanocarrier shows obvious photocytotoxic activity to Hela299 tumor cells in vitro.

  17. Stealth monoolein-based nanocarriers for delivery of siRNA to cancer cells

    OpenAIRE

    Oliveira, Ana Cristina Norberto Gonçalves; Raemdonck, Koen; Martens, Thomas; Rombouts, Koen; Simón-Vázquez, Rosana; Botelho, C.M.; Lopes, Ivo Edgar Araújo; Lúcio, M.; González-Fernández, África; Real Oliveira, M. Elisabete C.D.; Gomes, Andreia; Braeckmans, Kevin

    2015-01-01

    While the delivery of small interfering RNAs (siRNAs) is an attractive strategy to treat several clinical con- ditions, siRNA-nanocarriers stability after intravenous administration is still a major obstacle for the development of RNA-interference based therapies. But, although the need for stability is well recognized, the notion that strong stabilization can decrease nanocarriers efficiency is sometimes neglected. In this work we evaluated two stealth functionalization strategies to stabili...

  18. Protein corona change the drug release profile of nanocarriers: the "overlooked" factor at the nanobio interface.

    Science.gov (United States)

    Behzadi, Shahed; Serpooshan, Vahid; Sakhtianchi, Ramin; Müller, Beate; Landfester, Katharina; Crespy, Daniel; Mahmoudi, Morteza

    2014-11-01

    The emergence of nanocarrier systems in drug delivery applications has ushered in rapid development of new classes of therapeutic agents which can provide an essential breakthrough in the fight against refractory diseases. However, successful clinical application of nano-drug delivery devices has been limited mainly due to the lack of control on sustained release of therapeutics from the carriers. A wide range of sophisticated approaches employs the formation of crosslinkable, non-crosslinkable, stimuli-responsive polymer nanocarriers in order to enhance their delivery efficiency. Despite the extensive research conducted on the development of various nanocarriers, the effect of the biological milieu on the drug release profile of these constructs is not yet fully investigated. In particular, the formation of a protein corona on the surface of nanocarriers, when they interact with living organisms in vivo is largely decisive for their biological function. Using a number of synthetized (i.e., superparamagnetic iron oxide nanoparticles and polymeric nanocapsules) and commercialized nanocarriers (i.e., Abraxane®, albumin-bound paclitaxel drug), this study demonstrates that the protein corona can shield the nanocarriers and, consequently, alters the release profile of the drugs from the nanocarriers. More specifically, the protein corona could significantly reduce the burst effect of either protein conjugated nanocarriers or carriers with surface loaded drug (i.e., SPIONs). However, the corona shell only slightly changed the release profile of polymeric nanocapsules. Therefore, the intermediary, buffer effect of the protein shells on the surface of nanoscale carriers plays a crucial role in their successful high-yield applications in vivo.

  19. Anti-tumor activity of paclitaxel through dual-targeting lipoprotein-mimicking nanocarrier.

    Science.gov (United States)

    Chen, Conghui; Hu, Haiyang; Qiao, Mingxi; Zhao, Xiuli; Wang, Yinjie; Chen, Kang; Chen, Dawei

    2015-05-01

    In the present study, we devised a strategy that paclitaxel (PTX) with lipid and octadecylamine were prepared to lipid nanoparticle (PTX-LNP) with positive charge, folic acid-modified bovine serum albumin (FB)-coated surface of PTX-LNP through electrostatic attraction and generated the lipoprotein-mimicking nanocomplex (FB-PTX-LNP) for dual-targeting therapy. Bovine serum albumin (BSA) was used as the protein model due to its specific targeting to tumor by increased transendothelial gp60-mediated transport and increased intratumoral accumulation as a result of the secreted protein, acidic and rich in cysteine (SPARC)-albumin interaction. The further conjugating folic acid to BSA achieved the dual active targeting. In vitro cytotoxicity tests suggested FB-PTX-LNP and BSA-PTX-LNP exhibited significantly higher cytotoxic activity against MCF-7 and HepG2 cells compared to PTX-LNP. The cellular uptake experiments indicated that FB-coumarin-6-LNP modified with dual-targeting had a faster and greater cellular uptake when compared to BSA-coumarin-6-LNP and coumarin-6-LNP by MCF-7 cells. Thus, both BSA and FA did play roles in in vitro cytotoxicity and cellular uptake. Furthermore, the targeting ability and therapeutic efficacy of FB-PTX-LNP were assessed in vivo. FB-PTX-LNP produced very marked targeting ability and anti-tumor activity in MDA-MB-231 tumor-bearing mice. These results indicate the protein-lipid nanocomplex FB-PTX-LNP is a potential nanocarrier for Paclitaxel dual-targeting to tumor.

  20. pH- and NIR light responsive nanocarriers for combination treatment of chemotherapy and photodynamic therapy.

    Science.gov (United States)

    Wang, Sheng; Yang, Weitao; Cui, Jing; Li, Xue; Dou, Yan; Su, Lin; Chang, Jin; Wang, Hanjie; Li, Xiaodong; Zhang, Bingbo

    2016-02-01

    The side effects of antitumor drugs and low treatment efficacy are two major challenges of current chemotherapy. To address these issues, we developed a new kind of smart nanocarriers that combine pH-responsive chemotherapy and near-infrared (NIR) light triggered photodynamic therapy. These nanocarriers were based on upconversion nanoparticle (UCN)-loaded folate-conjugated polymeric lipid vesicles (UFPLVs). Merocyanine 540 (MC540), as a photosensitizer, was loaded in the UFPLVs; doxorubicin hydrochloride (DOX), as an antitumor drug, was conjugated to the surfaces of UFPLVs by pH-sensitive hydrazone bonds. The newly developed MC540&DOX-UFPLVs had a nanosized structure with targeting ligand modification, so they had the potential to accumulate into tumor sites via a combination of passive and active targeting effects. An in vitro singlet oxygen test showed that the nanocarriers can generate cytotoxic singlet oxygen successfully under the irradiation of NIR light. In vitro DOX release profiles demonstrated that the nanocarriers can achieve a pH-triggered drug release. It has been demonstrated by a cellular uptake study that the nanocarriers can efficiently deliver drugs and photosensitizers into tumor cells. In vitro and in vivo combination treatments evidenced the high antitumor effects of MC540&DOX-UFPLVs under NIR light irradiation. These results suggest that the MC540&DOX-UFPLVs may be promising nanocarriers for tumor combination therapy applications.